US20090182099A1

US20090182099A1 - Curable composition

Info

Publication number: US20090182099A1
Application number: US12/279,447
Authority: US
Inventors: Noriko Noro; Katsuyu Wakabayashi; Toshihiko Okamoto
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2006-02-16
Filing date: 2007-02-09
Publication date: 2009-07-16
Also published as: EP1988127A4; DE602007011217D1; EP1990371B1; WO2007094274A1; ATE491752T1; JP5420896B2; EP1985666A1; JPWO2007094276A1; JP5420893B2; US7960459B2; JP5420895B2; JPWO2007094274A1; WO2007094273A1; EP1988127B1; EP1992665A4; ATE491751T1; WO2007094275A1; EP1990371A1; JPWO2007094275A1; WO2007094272A1

Abstract

The present invention has its object to provide a curable composition which comprises an amidine compound as a non-organotin catalyst and shows good elongation, flexibility, surface curability, depth curability and adhesiveness; the above object can be achieved by a non-organotin curable composition which comprises: (A) an organic polymer containing a silyl group capable of crosslinking under siloxane bond formation, the silyl group being a group represented by the general formula (1): —SiR¹X₂; (B) an amidine compound (B-1) as a silanol condensation catalyst; and (C) a carboxylic acid, wherein the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component of the composition and the number of moles (c) of all carboxyl groups in the (C) component of the composition, namely the ratio (b)/(c), is higher than 2.

Description

TECHNICAL FIELD

The present invention relates to a curable composition which comprises an organic polymer containing a silicon atom-bound hydroxyl or hydrolyzable group and containing a silyl group capable of crosslinking under siloxane bond formation (hereinafter referred to as a “reactive silyl group”).

BACKGROUND ART

It is known that organic polymers containing at least one reactive silyl group in the molecule have properties such that they are crosslinked under siloxane bond formation resulting from hydrolysis and other reactions of the reactive silyl group due to moisture and the like, even at room temperature to give rubber-like cured products.
Among these reactive silyl group-containing polymers, those polymers which have a polyoxyalkylene type or polyisobutylene type main chain skeleton are disclosed in Patent Document 1, Patent Document 2 and the like and have already been produced industrially and are in wide use in such fields as sealants, adhesives and coatings.
Curable compositions to be used in preparing sealants, adhesives, coatings and like compositions as well as rubber-like cured products obtained by curing thereof are required to have various characteristics such as curability, adhesiveness, mechanical characteristics and storage stability.
Since moisture in the air causes curing of curable compositions comprising such a reactive silyl group-containing organic polymer as mentioned above, a great difference tends to arise between the curability of the composition inside (depth curability) and the surface curability. In particular, in the case of one-pack type curable compositions containing no moisture therein, a marked difference tends to arise between depth curability and surface curability. Generally desired are curable compositions showing rapid curability not only in the surface layer but also in the depths.
For obtaining cured products from a curable composition comprising a reactive silyl group-containing organic polymer, a silanol condensation catalyst is used. Generally used as the silanol condensation catalyst are organotin type catalysts having a carbon-tin bond such as dibutyltin bis(acetylacetonate), since they render the composition excellent in both surface curability and depth curability simultaneously and cause rapid increase in initial strength of cured products obtained. In recent years, however, the toxicity of organotin type compounds have been pointed out and development of non-organotin catalysts has been looked for.
Patent Document 3, Patent Document 4 and Patent Document 5 disclose, as silanol condensation catalysts, catalyst systems comprising a combination of an amine compound and a carboxylic acid. However, curable compositions using the non-organotin type silanol condensation catalysts described in the above-cited patent documents are sometimes insufficient in surface curability and, further, tend to decrease in adhesiveness with the increasing addition level of carboxylic acid.
On the other hand, while the technology of preparing a non-organotin type silanol condensation catalyst by using an amine compound and the carboxylic acid mentioned above in combination, there are only a relatively small number of examples disclosing a catalyst system in which an amine compound is used alone. Patent Document 6 discloses a technology which uses an aryl group-substituted biguanide compound, such as 1-(o-tolyl)biguanide, as a silanol condensation catalyst. As the description in the example section in Patent Document 6 discloses that cure was effected over such a long period as one week, it is difficult to attain any practical level of curability with a catalyst system using an amine compound alone.
On the other hand, investigations have also been carried out to improve the curability of compositions by modifying the structure of reactive silyl group-containing organic polymers. For example, Patent Document 7 discloses a curable composition containing an organic polymer terminating in a reactive silyl group having three hydroxyl or hydrolyzable groups (such silyl group hereinafter referred to also as a “T terminal group”), for example a trialkoxysilyl group, and it is disclosed that such a T terminal group-containing organic polymer, when an organotin type catalyst is used as a silanol condensation catalyst, shows higher activity as compared with an organic polymer terminating in a reactive silyl group containing two hydroxyl or hydrolyzable groups (such silyl group hereinafter referred to also as a “D terminal group”, for example a dialkoxysilyl group.
As shown above, it is a task very high in degree of difficulty to develop a curable composition satisfactory in all of such practical characteristics as surface curability, depth curability and adhesiveness using a non-organotin type silanol condensation catalyst while retaining the elongation and flexibility of cured products obtained therefrom; under the existing circumstances, however, early development of such composition is earnestly awaited.
Patent Document 1: Japanese Kokai Publication S52-73998
Patent Document 2: Japanese Kokai Publication S63-6041
Patent Document 3: Japanese Kokai Publication H05-117519
Patent Document 4: Japanese Kokai Publication 2001-342363
Patent Document 5: WO 04/31300
Patent Document 6: Japanese Kokai Publication 2005-248175
Patent Document 7: WO 98/47939

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a curable composition which comprises a reactive silyl group-containing organic polymer and an amidine compound as a non-organotin catalyst and shows good elongation, flexibility, surface curability, depth curability and adhesiveness.
The present inventors made intensive investigations to accomplish the above object and, as a result, found that when use is made of a D terminal group-containing organic polymer (A), an amidine compound (B-1) as a silanol condensation catalyst (B) and a carboxylic acid (C) for increasing the catalytic activity and, further, when the ratio between the number of moles (b) of all nitrogen atoms in the component (B-1) contained in the composition and the number of moles (c) of all carboxyl groups in the component (C) contained in the composition, namely the ratio (b)/(c), is higher than 2, a curable composition having good elongation, flexibility, surface curability, depth curability and adhesiveness can be obtained in spite of the catalyst being a non-organotin catalyst. Based on this finding, the present invention has now been completed.
That is, the present invention relates to a non-organotin curable composition, which comprises:
(A) an organic polymer containing a silyl group capable of crosslinking under siloxane bond formation, the silyl group being a group represented by the general formula (1):
—SiR¹X₂ (1)
(wherein R¹represents a group selected from among alkyl groups containing 1 to 20 carbon atoms, aryl groups containing 6 to 20 carbon atoms, aralkyl groups containing 7 to 20 carbon atoms and triorganosiloxy groups represented by (R′)₃SiO— in which R′ is a hydrocarbon group containing 1 to 20 carbon atoms, the three R′ groups may be the same or different, and X represents a hydroxyl group or a hydrolyzable group and the two X groups may be the same or different);
(B) an amidine compound (B-1) as a silanol condensation catalyst; and
(C) a carboxylic acid,
wherein the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component of the composition and the number of moles (c) of all carboxyl groups in the (C) component of the composition, namely the ratio (b)/(c), is higher than 2.
One preferred embodiment relates to the above-mentioned curable composition, wherein a main chain skeleton of the (A) component organic polymer contains at least one atom selected from among a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom.
One further preferred embodiment relates to the above-mentioned curable composition, wherein the (A) component organic polymer comprises at least one species selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers and (meth)acrylate ester polymers.
One further preferred embodiment relates to the above-mentioned curable composition, wherein the polyoxyalkylene polymer is a polyoxypropylene polymer.
One further preferred embodiment relates to the above-mentioned curable composition, which contains the (B-1) component in an amount of 0.001 to 20 parts by weight per 100 parts by weight of the component (A).
Preferred as applications of the curable composition according to the present invention is a sealant or an adhesive which comprises the curable composition as described above.
The present invention provides a curable composition which comprises a reactive silyl group-containing organic polymer and in which an amidine compound is used as a non-organotin catalyst and which is excellent in elongation, flexibility, surface curability, depth curability and adhesiveness.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the present invention is described in detail.
The present invention includes a non-organotin type curable composition which comprises a specific reactive silyl group-containing organic polymer, a specific silanol condensation catalyst and a carboxylic acid. The “non-organotin type curable composition”, so referred to herein, is defined as a composition in which the addition level of an organotin compound is not higher than 50% by weight in the compound components each acting as a silanol condensation catalyst.
In the composition, a D terminal group-containing organic polymer (A) is used as a reactive silyl group-containing organic polymer, an amidine compound (B-1) as a silanol condensation catalyst (B) and a carboxylic acid (C) as a catalytic activity enhancer and the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component contained in the composition and the number of moles (c) of all carboxyl groups in the (C) component contained in the composition, namely the ratio (b)/(c), is higher than 2.
The curable composition of the invention comprises, as an essential constituent (A), a reactive silyl group-containing organic polymer (hereinafter referred to also as “component (A)”, “reactive silyl group-containing organic polymer (A)” or “organic polymer (A)”).
The organic polymer (A) has, on an average, at least one reactive silyl group per molecule. The reactive silyl group, so referred to herein, is an organic group containing hydroxyl groups or hydrolyzable groups each bound to a silicon atom. The reactive silyl group-containing organic polymer (A) is crosslinked under siloxane bond formation as a result of a reaction promoted by a silanol condensation catalyst.
As the reactive silyl group, there may be mentioned groups represented by the general formula (1):
—SiR¹X₂ (1)
(R¹is at least one group selected from the group consisting of groups selected from among alkyl groups containing 1 to 20 carbon atoms, aryl groups containing 6 to 20 carbon atoms, aralkyl groups containing 7 to 20 carbon atoms and triorganosiloxy groups represented by (R′)₃SiO— in which each R′ is a hydrocarbon group containing 1 to 20 carbon atoms and the three R′ groups may be the same or different, and two X groups are independently a hydroxyl group or a hydrolyzable group).
The organic polymer, which terminates in a reactive silyl group represented by the general formula (1) and contains two X groups (each being a hydroxyl group or a hydrolyzable group) bound to the silicon atom, is superior in elongation, flexibility and storage stability to an organic polymer which terminates in a reactive silyl group containing three X groups (each being a hydroxyl group or a hydrolyzable group) bound to the silicon atom.
The curable composition of the present invention, which comprises a reactive silyl group-containing organic polymer (A) as the main component, is better in compatibility with the silanol condensation catalyst, namely the amidine compound (B-1), as compared with a composition which comprises, as the main component, such an inorganic polymer as polydimethylsiloxane, hence is preferred.
The curable composition comprising an organic polymer (A) is excellent in curability and the cured products obtained therefrom are characterized by excellent adhesiveness.
Further, for the same reasons, the organic polymer (A) preferably has a main chain skeleton containing at least one atom selected from among a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom.
The main chain skeleton of the organic polymer (A) is not particularly restricted but includes, polyoxyalkylene type polymers such as polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymers and polyoxypropylene-polyoxybutylene copolymers; ethylene-propylene type copolymers; polyisobutylene, copolymers of isobutylene and isoprene or the like, polychloroprene, polyisoprene, copolymers of isoprene or butadiene and acrylonitrile and/or styrene or the like; polybutadiene and copolymers of isoprene or butadiene and acrylonitrile and styrene or the like; hydrocarbon type polymers such as hydrogenated polyolefin polymers derived from these polyolefin type polymers by hydrogenation; polyester type polymers obtained by condensation of a dibasic acid such as adipic acid and a glycol, or ring-opening polymerization of a lactone (s); (meth)acrylate ester polymers obtained by radical polymerization of such a compound as ethyl (meth)acrylate and butyl (meth)acrylate; vinyl polymers obtained by radical polymerization of such a compound as a (meth)acrylate ester compound, vinyl acetate, acrylonitrile and styrene; graft polymers obtained by polymerizing a vinyl compound in such polymers as mentioned above; polysulfide type polymers; polyamide type polymers such as polyamide 6 produced by ring-opening polymerization of ε-caprolactam, polyamide 6.6 produced by polycondensation of hexamethylenediamine and adipic acid, polyamide 6.10 produced by polycondensation of hexamethylenediamine and sebacic acid, polyamide 11 produced by polycondensation of ε-aminoundecanoic acid, polyamide 12 produced by ring-opening polymerization of ε-aminolaurolactam, and copolymer polyamides composed of a plurality of the polyamides mentioned above; polycarbonate type polymers such as polycarbonates produced by polycondensation of bisphenol A and carbonyl chloride; diallyl phthalate type polymers; and like organic polymers.
Preferred among those mentioned above are organic polymers (A) having, as the main chain skeleton, saturated hydrocarbon type polymers such as polyisobutylene, hydrogenated polyisoprene and hydrogenated polybutadiene, polyoxyalkylene type polymers, (meth)acrylate ester polymers and polysiloxane type polymers, in view of their relatively low glass transition temperature and of good low-temperature resistance of cured products obtained therefrom.
The glass transition temperature of the reactive silyl group-containing organic polymer (A) is not particularly restricted but preferably is not higher than 20° C., more preferably not higher than 0° C., most preferably not higher than −20° C. When the glass transition temperature is higher than 20° C., the viscosity of the curable composition increases in the winter season or in cold districts, developing a tendency toward lowered workability and, further, the flexibility of cured products obtained decreases and the elongation thereof tends to decrease.
The glass transition temperature mentioned above can be determined by DSC measurement according to the method prescribed in JIS K 7121.
A curable composition comprising, as the main component, a saturated hydrocarbon type polymer and an organic polymer whose main chain skeleton is a polyoxyalkylene type polymer and a (meth)acrylate ester polymer is more preferred since, when it is used as an adhesive or sealant, low-molecular-weight components scarcely migrate to (i.e. stain) adherends.
Further, an organic polymer whose main chain skeleton is a polyoxyalkylene type polymer and a (meth)acrylate ester polymer is particularly preferred since it is high in moisture permeability and, when used as a main component of a one-pack type adhesive or sealant, it is excellent in depth curability and gives cured products excellent in adhesiveness. Most preferred is an organic polymer whose main chain skeleton is a polyoxyalkylene type polymer.
The polyoxyalkylene type polymer to be used as the main chain skeleton of the organic polymer (A) is a polymer having a repeating unit represented by the general formula (2):
—R⁴—O— (2)
(R⁴is a straight or branched alkylene group containing 1 to 14 carbon atoms).
The group R⁴in the general formula (2) is not particularly restricted but may be any of the straight or branched alkylene groups containing 1 to 14 carbon atoms and, among those, straight or branched alkylene groups containing 2 to 4 carbon atoms are preferred.
The repeating unit defined by the general formula (2) is not particularly restricted but includes, for example, —CH₂O—, —CH₂CH₂O—, —CH₂CH(CH₃) O—, —CH₂CH(C₂H₅) O—, —CH₂C(CH₃)₂O— and —CH₂CH₂CH₂CH₂O—.
The polyoxyalkylene type polymer may have one repeating unit species or a plurality of repeating unit species. In the case of use in the field of sealants and the like, in particular, an organic polymer (A) in which the main component of the main chain skeleton is a propylene oxide polymer is preferred since such polymer is noncrystalline and relatively low in viscosity.
A method of producing such a polyoxyalkylene type polymer is not particularly restricted but may be any of the methods known in the art. For example, mention may be made of the method using an alkali catalyst such as KOH, the method disclosed in Japanese Kokai Publication S61-215623 which uses, as a catalyst, a transition metal-porphyrin complex, such as a complex obtained by reacting an organoaluminum compound with porphyrin, the methods disclosed in Japanese Kokoku Publications S46-27250 and S59-15336 and U.S. Pat. Nos. 3,278,457, 3,278,458, 3,278,459, 3,427,256, 3,427,334 and 3,427,335, among others, which use, as a catalyst, a composite metal cyanide complex, the method disclosed in Japanese Kokai Publication H10-273512 which uses, as a catalyst, a polyphosphazene salt, and the method disclosed in Japanese Kokai Publication H11-060722 which uses, as a catalyst, a phosphazene compound.
The method of producing a reactive silyl group-containing polyoxyalkylene type polymer is not particularly restricted but may be any of the methods known in the art. For example, mention may be made of the methods disclosed in Japanese Kokoku Publications S45-36319 and S46-12154, Japanese Kokai Publications S50-156599, S54-6096, S55-13767, S55-13468 and S57-164123, Japanese Kokoku Publication H03-2450 and U.S. Pat. Nos. 3,632,557, 4,345,053, 4,366,307 and 4,960,844, among others, and the methods disclosed in Japanese Kokai Publications S61-197631, S61-215622, S61-215623, S61-218632, H03-72527, H03-47825 and H08-231707, among others, according to which polymers high in molecular weight (number average molecular weight of 6,000 or higher) and narrow in molecular weight distribution (Mw/Mn of 1.6 or below) can be obtained.
In formulating the curable composition using the reactive silyl group-containing polyoxyalkylene type polymer mentioned above, the polymer may comprise a single species or a combination of a plurality of species thereof.
The saturated hydrocarbon type polymer to be used as the main chain skeleton of the organic polymer (A) is a polymer whose molecules are substantially free of any carbon-carbon unsaturated bond, except for an aromatic ring, and is excellent in heat resistance, weather resistance, durability and a moisture barrier property.
The saturated hydrocarbon type polymer is not particularly restricted but there may be mentioned (i) polymers derived from an olefin compound containing 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene and isobutylene as the repeating unit species, (ii) polymers derived from a diene type compound, such as butadiene and isoprene as the repeating unit species, and (iii) polymers obtained by copolymerizing the above-mentioned diene type compound and the above-mentioned olefin type compound, followed by hydrogenation. Among these, isobutylene type polymers and hydrogenated polybutadiene type polymers are preferred in view of ease of functional-group introduction into an end thereof, ease of molecular weight control and adjustability of the number of terminal functional groups, among others; isobutylene type polymers are more preferred.
The isobutylene type polymer may be such one that all of the repeating units are derived from isobutylene or a copolymer with another compound. When the isobutylene type copolymer is used as the main chain skeleton, the polymer preferably has an isobutylene-derived repeating unit content, in each molecule, of not lower than 50% by weight, more preferably not lower than 80% by weight, particularly preferably 90 to 99% by weight, so that the cured products obtained may have excellent rubber characteristics.
A method of producing the saturated hydrocarbon type polymer is not particularly restricted but may be any of various conventional polymerization methods. Among them, the living polymerization method the development of which has been remarkable in recent years is preferred and, for example, the Inifer polymerization found by Kennedy et al. (J. P. Kennedy et al., J. Polymer Sci., Polymer Chem. Ed., 1997, 15, p. 2843) may be mentioned as a method of producing isobutylene-based polymers using the living polymerization method. This polymerization method enables introduction of various functional groups into molecular ends and the isobutylene type polymers obtained are known to have a molecular weight of about 500 to 100,000 with a molecular weight distribution of not broader than 1.5.
A method of producing the reactive silyl group-containing saturated hydrocarbon polymer is not particularly restricted but may be any of the methods known in the art, for example the methods disclosed in Japanese Kokoku Publications H04-69659 and H07-108928, Japanese Kokai Publications S63-254149, S64-22904 and H01-197509 and Japanese Patents Nos. 2539445 and 2873395 and Japanese Kokai Publication H07-53882.
In formulating the curable composition using the above-mentioned reactive silyl group-containing saturated hydrocarbon type polymer, the polymer may comprise a single species or a combination of a plurality of species thereof.
A (meth)acrylate ester polymer to be used as the main chain skeleton of the organic polymer (A) is a polymer in which the repeating unit is derived from a (meth)acrylate ester compound. The expression “(meth)acrylate ester” refers to an acrylate ester and/or a methacrylate ester and has the same meaning also in the description which follows.
The (meth)acrylate ester compound to be used as the repeating unit is not particularly restricted but includes such (meth)acrylate compounds as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, toluoyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, γ-(methacryloyloxypropyl)trimethoxysilane, γ-(methacryloyloxypropyl)dimethoxymethylsilane, (meth)acrylic acid-ethylene oxide adducts, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, perfluoroethyl (meth)acrylate, trifluoromethyl (meth)acrylate, bis(trifluoromethylmethyl) (meth)acrylate, 2-trifluoromethyl-2-perfluoroethylethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate and 2-perfluorohexadecylethyl (meth)acrylate.
The (meth)acrylate ester polymer includes copolymers of a (meth)acrylate ester compound and a vinyl compound copolymerizable therewith. The vinyl compound is not particularly restricted but includes: styrene compounds such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, and styrenesulfonic acid and salts thereof; silyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; maleic acid, maleic anhydride, and maleic acid monoalkyl esters and dialkyl esters; fumaric acid and fumaric acid monoalkyl esters and dialkyl esters; maleimide type compounds such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide; nitrile group-containing vinyl compounds such as acrylonitrile and methacrylonitrile; amide group-containing vinyl compounds such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate and vinyl cinnamate; alkenes such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; vinyl chloride, vinylidene chloride, allyl chloride and allyl alcohol. It is also possible to use a plurality of these as copolymerization components.
Among the (meth)acrylate ester polymers obtained from the compounds mentioned above, those organic polymers which comprise, as the main chain skeleton, a copolymer of a styrene compound and a (meth)acrylate compound are preferred since they give cured products excellent in physical properties; those organic polymers which comprise, as the main chain skeleton, a copolymer of an acrylate ester compound and a methacrylate ester compound are more preferred, and those organic polymers which comprise, as the main chain skeleton, a polymer of an acrylate ester compound are particularly preferred.
For use in general architectural fields, the curable composition is required to be low in viscosity, while the cured products obtained therefrom are required to be low in modulus and high in elongation, weather resistance and thermal stability.
More preferred as ones meeting these requirements are organic polymers (A) whose main chain skeleton is derived from a butyl acrylate compound.
On the other hand, for use in automotive or like fields, the cured products obtained are required to be excellent in oil resistance.
More preferred as one giving cured products excellent in oil resistance is an organic polymer (A) whose main chain skeleton is a copolymer mainly derived from ethyl acrylate.
Curable compositions comprising the organic polymer (A) whose main chain skeleton is an ethyl acrylate-based copolymer tend to give cured products somewhat inferior in low-temperature characteristics (low-temperature resistance) in spite of their being excellent in oil resistance. For improving the low-temperature characteristics, replacement is made of a part of ethyl acrylate with butyl acrylate. Since, however, an increased proportion of butyl acrylate tends to impair the good oil resistance, the proportion thereof is preferably not higher than 40%, more preferably not higher than 30%, in cases of a field where oil resistance is required.
The use, as a comonomer component, of 2-methoxyethyl acrylate or 2-ethoxyethyl acrylate which has an oxygen atom introduced into the side chain alkyl group is also preferred for improving low-temperature characteristics and the like without causing decrease in oil resistance.
Since, however, the introduction of an alkoxy group having an ether bond in the side chain tends to render the cured products obtained inferior in thermal stability, the proportion thereof is preferably not higher than 40% in cases of use where thermal stability is required.
As mentioned above, it is possible to obtain an organic polymer (A) whose main chain skeleton is an ethyl acrylate-based copolymer and which is suited for various uses or can meet requirements by selecting the comonomer component species and varying the proportion thereof taking into consideration such physical properties as oil resistance, thermal stability and low temperature characteristics as required of the cured products obtained. For example, there may be mentioned, without any limitative meaning, copolymers of ethyl acrylate, butyl acrylate and 2-methoxyethyl acrylate copolymer (weight ratio: 40-50/20-30/30-20) as examples excellent in balance among such physical properties as oil resistance, thermal stability and low-temperature characteristics.
In the practice of the present invention, these preferred compounds may be copolymerized and, further, block-copolymerized with another compound and, on such occasion, the content of these preferred compounds is preferably not lower than 40% by weight.
A method of producing the (meth)acrylate ester polymer is not particularly restricted but may be any of the methods known in the art. Among them, the living radical polymerization method is preferably used in particular in view of the ease of high-rate introduction of a crosslinking functional group into a molecular chain end and the possibility of obtaining polymers narrow in molecular weight distribution and low in viscosity.
The polymers obtained by ordinary free radical polymerization using, for example, an azo compound or peroxide as a polymerization initiator tend to show an increased molecular weight distribution value generally not lower than 2 and an increased level of viscosity.
Among the methods of producing (meth)acrylate ester polymers using the above-mentioned “living radical polymerization method”, the “atom transfer radical polymerization method” which uses an organic halide or sulfonyl halide compound as an initiator and a transition metal complex as a catalyst is preferred as the method of producing (meth)acrylate ester polymers containing a specific functional group since it has not only such characteristics of the “living radical polymerization” as the narrowness in molecular weight distribution and the capability to give polymers low in viscosity but also a high degree of freedom in selecting the initiator and catalyst and the capability to provide the polymers with a halogen or the like at ends thereof relatively advantageous to functional-group exchange reactions.
As for the atom transfer radical polymerization method, there may be mentioned, for example, the method described in Matyjaszewski et al., Journal of the American Chemical Society (J. Am. Chem. Soc.), 1995, 117, p. 5614.
A method of producing the reactive silyl group-containing (meth)acrylate ester polymer is not particularly restricted but includes, for example, the free radical polymerization method using a chain transfer agent, as disclosed in Japanese Kokoku Publications H03-14068 and H04-55444 and Japanese Kokai Publication H06-211922, the atom transfer radical polymerization method disclosed in Japanese Kokai Publication H09-272714, and the like.
It is also possible to use a (meth)acrylate ester copolymer derived from a plurality of the (meth)acrylate ester compounds mentioned above as the main chain skeleton of the organic polymer (A).
As typical examples of the (meth)acrylate ester copolymer derived from a plurality of (meth)acrylate ester compounds, there may be mentioned copolymers whose main chain skeleton substantially comprises: a repeating unit having an alkyl group containing 1 to 8 carbon atoms as represented by the general formula (3):
—CH₂—C(R⁵)(COOR⁶)— (3)
(R⁵is a hydrogen atom or a methyl group and R⁶is an alkyl group containing 1 to 8 carbon atoms); and a repeating unit having an alkyl group containing 9 or more carbon atoms as represented by the general formula (4):
—CH₂—C(R⁵)(COOR⁷)— (4)
(R⁵is as defined above referring to the general formula (3) and R⁷is an alkyl group containing 9 or more carbon atoms).
The group R⁶in the general formula (3) is not particularly restricted but may be any of the alkyl groups containing 1 to 8 carbon atoms, for example a methyl group, an ethyl group, a propyl group, an n-butyl group, a t-butyl group and a 2-ethylhexyl group; among these, alkyl groups containing 1 to 4 carbon atoms are preferred.
The group R⁶contained in the copolymers is not always restricted to a single alkyl group species.
The group R⁷in the general formula (4) is not particularly restricted but may be any of the alkyl groups containing 9 or more carbon atoms, for example a lauryl group, a dodecyl group, a cetyl group, a stearyl group and a behenyl group. Among these, alkyl groups containing 10 to 30 carbon atoms are preferred and long-chain alkyl groups containing 10 to 20 carbon atoms are more preferred.
The group R⁷contained in the copolymers is not always restricted to a single alkyl group species.
The (meth)acrylate ester copolymer substantially comprises the repeating units defined by the general formula (3) and general formula (4). The term “substantially” as used herein means that the total content of the repeating units defined by the general formulas (3) and (4) in the copolymer is not lower than 50% by weight, and the total content of the repeating units defined by the general formulas (3) and (4) in the copolymer is preferably not lower than 70%.
The content ratio between the repeating units of general formulas (3) and (4) occurring in the copolymer as expressed in terms of the weight ratio (general formula (3): general formula (4)) is preferably 95:5 to 40:60, more preferably 90:10 to 60:40.
The (meth)acrylate ester copolymer comprises a copolymer of (meth)acrylate ester compounds used as the repeating units defined by the general formulas (3) and (4) and a vinyl compound copolymerizable therewith.
As the vinyl compound, there may be mentioned, for example, acrylic acids such as acrylic acid and methacrylic acid; amide group-containing compounds such as acrylamide, methacrylamide, N-methylolacrylamide and N-methylolmethacrylamide, epoxy group-containing compounds such as glycidyl acrylate and glycidyl methacrylate, amino group-containing compounds such as diethylaminoethyl acrylate, diethylaminoethyl methacrylate and aminoethyl vinyl ether; and, further, such compounds as acrylonitrile, styrene, α-methylstyrene, alkyl vinyl ethers, vinyl chloride, vinyl acetate, vinyl propionate and ethylene.
These reactive silyl group-containing organic polymers may be used singly or in combination of two or more species. More specifically, it is also possible to use an organic-polymer blend comprising two or more species selected from the group consisting of reactive silyl group-containing polyoxyalkylene type polymers, reactive silyl group-containing saturated hydrocarbon type polymers and reactive silyl group-containing (meth)acrylate ester polymers.
A method of producing the organic polymer blend comprising a reactive silyl group-containing polyoxyalkylene type polymer and a reactive silyl group-containing (meth) acryl ester polymer is not particularly restricted but there may be mentioned, for example, the methods disclosed in Japanese Kokai Publications S59-122541, S63-112642, H06-172631 and H11-116763, and the like.
The organic-polymer blend comprising a reactive silyl group-containing saturated hydrocarbon type polymer and a reactive silyl group-containing (meth)acrylate ester polymer is not particularly restricted but mention may be made of the polymers disclosed in Japanese Kokai Publications H01-168764 and 2000-186176, and the like.
Further, in addition to those mentioned above, the organic-polymer blends comprising a reactive silyl functional group-containing (meth)acrylate ester polymer can also be produced by a method comprising polymerizing a (meth)acrylate ester monomer in the presence of a reactive silyl group-containing polymer. This production method is not particularly restricted but there may be mentioned, for example, the methods disclosed in Japanese Kokai Publications S59-78223, S59-168014, S60-228516 and S60-228517.
In the main chain skeleton of the organic polymer (A), there may further be present, if necessary, another repeating unit containing, for example, a urethane bond, so long as the effects of the present invention are not significantly lessened thereby.
The urethane bond-containing repeating unit is not particularly restricted but there may be mentioned, for example, a repeating unit comprising a group formed by the reaction between an isocyanato group and an active hydrogen group (the group thus formed is hereinafter referred to also as an “amide segment”).
The amide segment is an organic group represented by the general formula (5):
—NR⁸—C(═O)— (5)
(R⁸is a hydrogen atom or an organic group).
The amide segment is not particularly restricted but includes, for example, a urethane group formed by the reaction between an isocyanato group and a hydroxyl group; a urea group formed by the reaction between an isocyanato group and an amino group; and a thiourethane group formed by the reaction between an isocyanato group and a mercapto group.
Those organic groups formed by the reaction of an active hydrogen in the urethane group, the urea group and the thiourethane group with an isocyanato group also fall within the definition of “amide segment” as given herein.
A method of producing the reactive silyl group-containing organic polymer containing an amide segment in the main chain skeleton thereof is not particularly restricted but there may be mentioned, for example, the method comprising reacting an active hydrogen-terminated organic group-containing organic polymer with an excess of a polyisocyanate compound to give a polymer having an isocyanato group at a polyurethane type main chain end and, thereafter or simultaneously therewith, reacting all or part of the isocyanato groups in the polymer with a group W in a silicon compound represented by the general formula (6):
W—R⁹—SiR¹X₂ (6)
(R⁹is a divalent organic group, more preferably a divalent hydrocarbon group containing 1 to 20 carbon atoms; R¹and the two X groups are as defined hereinabove referring to the general formula (1); and W is a group containing at least one active hydrogen selected from the group consisting of a hydroxyl group, a carboxyl group, a mercapto group and an amino (primary or secondary) group), as disclosed in Japanese Kokoku Publication S46-12154 (U.S. Pat. No. 3,632,557), Japanese Kokai Publications S58-109529 (U.S. Pat. No. 4,374,237), S62-13430 (U.S. Pat. No. 4,645,816), H08-53528 (EP 0676403), and H10-204144 (EP 0831108), Japanese Kohyo Publication 2003-508561 (U.S. Pat. No. 6,197,912), Japanese Kokai Publications H06-211879 (U.S. Pat. No. 5,364,955), H10-53637 (U.S. Pat. No. 5,756,751), H11-100427, 2000-169544, 2000-169545 and 2002-212415, Japanese Patent 3,313,360, U.S. Pat. Nos. 4,067,844 and 3,711,445, Japanese Kokai Publication 2001-323040, and the like.
Mention may also be made of a method comprising reacting an active hydrogen-containing group occurring at an end of an organic polymer with the isocyanato group of a reactive silyl group-containing isocyanate compound represented by the general formula (7):
O═C═N—R⁹—SiR¹X₂ (7)
(R⁹, the two R's and X are as defined above referring to the general formula (6)), as disclosed in Japanese Kokai Publications H11-279249 (U.S. Pat. No. 5,990,257), 2000-119365 (U.S. Pat. No. 6,046,270), S58-29818 (U.S. Pat. No. 4,345,053), H03-47825 (U.S. Pat. No. 5,068,304), H11-60724, 2002-155145 and 2002-249538, WO 03/018658, WO 03/059981, and the like.
The active hydrogen-terminated group-containing organic polymer is not particularly restricted but includes, for example, hydroxyl group-terminated oxyalkylene polymers (polyether polyols), polyacrylic polyols, polyester polyols, hydroxyl group-terminated saturated hydrocarbon type polymers (polyolefin polyols), polythiol compounds and polyamine compounds.
Preferred among these are those organic polymers whose main chain skeleton comprises a polyether polyol, polyacrylic polyol and polyolefin polyol components, since they have a relatively low glass transition temperature and give cured products excellent in low-temperature resistance.
Those organic polymers comprising a polyether polyol component are low in viscosity, have good workability and give cured products showing good depth curability and adhesiveness, hence are particularly preferred. Curable compositions in which an organic polymer containing a polyacrylic polyol and saturated hydrocarbon type polymer component are more preferred since they give cured products having good weather resistance and thermal stability.
The polyether polyol preferably has, on an average, at least 0.7 terminal hydroxyl group per molecule.
The production method thereof is not particularly restricted but may be any of the methods known in the art, including, for example, a polymerization method using an alkali metal catalyst, and a polymerization method of an alkylene oxide using a polyhydroxy compound containing at least two hydroxyl groups per molecule as an initiator in the presence of a double metal cyanide complex or cesium.
Among the polymerization methods mentioned above, the polymerization method using a double metal cyanide complex is preferred since it gives polymers low in degree of unsaturation, narrow in molecular weight distribution (Mw/Mn) and low in viscosity, which give cured products excellent in acid resistance and weather resistance, among others.
The term “polyacrylic polyol” refers to a polyol whose skeleton is a (meth)acrylic acid alkyl ester (co)polymer and whose molecule contains a hydroxyl group.
As for the production method thereof, the living radical polymerization method is preferred and the atom transfer radical polymerization method is more preferred because of capability of their giving polymers narrow in molecular weight distribution and possibly low in viscosity. Also preferred is the polymerization method involving the so-called SGO process in which an acrylic acid alkyl ester type compound is continuously bulk-polymerized under high-temperature and high-pressure conditions, as disclosed in Japanese Kokai Publication 2001-207157. As such a polyacrylic polyol, there may be mentioned ARUFON UH-2000 (product of Toagosei Co., Ltd.), and the like.
The polyisocyanate compound is not particularly restricted but includes, for example, an aromatic type polyisocyanate such as toluene (tolylene) diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate; and an aliphatic type polyisocyanate such as isophorone diisocyanate and hexamethylene diisocyanate.
When the amide segment content is high in the main chain skeleton of the organic polymer serving as the (A) component in the practice of the present invention, the organic polymer shows a high viscosity and sometimes gives a composition poor in workability. Conversely, the amide segment in the main chain skeleton of the (A) component tends to improve the curability of the composition according to the present invention.
The silicon compound defined by the general formula (6) is not particularly restricted but there may be mentioned, for example, amino group-containing silane compounds such as γ-aminopropyldimethoxymethylsilane, N-(β-aminoethyl)-γ-aminopropyldimethoxymethylsilane, γ-(N-phenyl)aminopropyldimethoxymethylsilane, N-ethylaminoisobutyldimethoxymethylsilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-cyclohexylaminomethyldiethoxymethylsilane and N-phenylaminomethyldimethoxymethylsilane; hydroxyl group-containing silane compounds such as γ-hydroxypropyldimethoxymethylsilane; and mercapto group-containing silane compounds such as γ-mercaptopropyldimethoxymethylsilane.
As the silicon compound represented by the general formula (6), there may further be mentioned Michael addition products derived from various α,β-unsaturated carbonyl compounds and a primary amino group-containing silane compound or Michael addition products derived from various (meth)acryloyl group-containing silane compounds and a primary amino group-containing compound, as disclosed in Japanese Kokai Publications H06-211879 (U.S. Pat. No. 5,364,955), H10-53637 (U.S. Pat. No. 5,756,751), H10-204144 (EP 0831108) 2000-169544 and 2000-169545.
The reactive silyl group-containing isocyanate compound defined by the general formula (7) is not particularly restricted but includes, for example, γ-methyldimethoxysilylpropyl isocyanate, γ-methyldiethoxysilylpropyl isocyanate and dimethoxymethylsilylmethyl isocyanate.
As the reactive silyl group-containing isocyanate compound defined by the general formula (7), there may further be mentioned the reaction products derived from a silicon compound of the general formula (6) and an excess of a polyisocyanate compound, as disclosed in Japanese Kokai Publication 2000-119365 (U.S. Pat. No. 6,046,270).
The hydrolyzable group represented by X in the general formula (1) is not particularly restricted but includes those hydrolyzable groups which are known in the art, for example, a hydrogen atom, halogen atoms, and an alkoxy group, an acyloxy group, a ketoxymate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group and an alkenyloxy group. Among these, a hydrogen atom, an alkoxy group, an acyloxy group, a ketoxymate group, an amino group, an amide group, an aminooxy group, a mercapto group and an alkenyloxy group are preferred, and an alkoxy group is more preferred from the viewpoints of mild hydrolyzability and easy handleability.
The group R¹in the general formula (1) is not particularly restricted but includes, for example, an alkyl group such as a methyl group and an ethyl group, a cycloalkyl group such as a cyclohexyl group, an aryl group such as a phenyl group, an aralkyl group such as a benzyl group, and a triorganosiloxy group represented by —OSi(R′)₃wherein R′ is a methyl group, a phenyl group or the like. Among these, a methyl group is preferred.
The reactive silyl group defined by the general formula (1) is not particularly restricted but includes, for example, a dimethoxymethylsilyl group, a diethoxymethylsilyl group and a diisopropoxymethylsilyl group. Among these, a dimethoxymethylsilyl group is preferred since it has high activity and affords good curability and good storage stability.
Further, a diethoxymethylsilyl group is particularly preferred since the alcohol formed upon hydrolysis reaction of the reactive silyl group is highly safe ethanol.
A method of introducing the reactive silyl group is not particularly restricted but includes such methods known in the art as the methods (a) to (c) shown below.
(a) A method comprising: reacting a polymer containing such a functional group as a hydroxyl group in the molecule with an organic compound containing an active group reactive with this functional group as well as an unsaturated group to give an unsaturated group-containing polymer; or copolymerizing a polymer containing such a functional group as a hydroxyl group in the molecule with an unsaturated group-containing epoxy compound to give an unsaturated group-containing polymer, and then reacting the reaction product obtained with a reactive silyl group-containing hydrosilane for hydrosilylation.
(b) A method comprising reacting the unsaturated group-containing organic polymer obtained in the same manner as described above in (a) with a compound containing a mercapto group and a reactive silyl group.
(c) A method comprising reacting an organic polymer containing such a functional group as a hydroxyl group, an epoxy group or an isocyanato group in the molecule with a compound containing a functional group reactive with this function group and a reactive silyl group.
Among these methods, the method (a) or the method (c) in such a mode that a hydroxyl group-terminated polymer is reacted with a compound containing an isocyanato group and reactive silyl group is preferred in view of the fact that a high conversion rate can be attained in a relatively short period of time.
The method (a) is more preferred since curable compositions based on the reactive silyl group-containing organic polymer obtained by the method (a) tends to be lower in viscosity than curable compositions based on the organic polymer obtained by the method (c) and, as a result, curable compositions having good workability can be obtained and, further, the organic polymer obtained by the method (b) has a stronger mercaptosilane-due odor as compared with the organic polymer obtained by the method (a).
The hydrosilane compound to be used in carrying out the method (a) is not particularly restricted but includes, for example, halogenated silanes such as methyldichlorosilane; alkoxysilanes such as methyldimethoxysilane, methyldiethoxysilane, and phenyldimethoxysilane; acyloxysilanes such as methyldiacetoxysilane and phenyldiacetoxysilane; and ketoxymatesilanes such as bis(dimethylketoxymate)methylsilane and bis(cyclohexylketoxymate)methylsilane. Among these, alkoxyhydrosilanes are preferred because of the mild hydrolyzability and easy handleability of curable compositions based on the organic polymer (A) obtained and, among the alkoxyhydrosilanes, methyldimethoxysilane is preferred since curable compositions based on the organic polymer (A) obtained are superior in curability and restorability.
The synthetic method (b) is not particularly restricted but may be, for example, the method of introducing a mercapto group- and reactive silyl group-containing compound into an unsaturated-bond site in the organic polymer by a radical addition reaction in the presence of a radical initiator and/or a radical generation source. The mercapto group- and reactive silyl group-containing compound is not particularly restricted but includes, for example, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane and (mercaptomethyl)methyldiethoxysilane.
The method of reacting a hydroxyl group-terminated polymer with an isocyanato group- and reactive silyl group-containing compound according to the synthetic method (c) is not particularly restricted but may be, for example, a method disclosed in Japanese Kokai Publication H03-47825. The isocyanato group- and reactive silyl group-containing compound is not particularly restricted but includes, for example, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, isocyanatomethyldimethoxymethylsilane and isocyanatomethyldiethoxymethylsilane.
The reactive silyl group-containing organic polymer (A) to be used may have either a straight chain structure or a branched chain structure in the molecule thereof, and the number average molecular weight thereof, as expressed in terms of the value on a polystyrene equivalent basis as derived from the value measured by GPC, is preferably 500 to 100,000, more preferably 1,000 to 50,000, particularly preferably 3,000 to 30,000. When the number average molecular weight is lower than 500, the cured products obtained tend to be inferior in elongation characteristics and, when it is in excess of 100,000, the resulting curable composition becomes high in viscosity and tends to be inferior in workability.
The number of reactive silyl groups contained in each molecule of the organic polymer (A) is preferably not smaller than 1 on an average; it is preferably 1.1 to 5. When the number of reactive silyl groups contained in each molecule is smaller than 1 on an average, the curable composition tends to be inferior in curability and the cured products obtained show a tendency toward failure to exhibit a good rubber elastic behavior.
The reactive silyl group may occur at a main chain end or at a side chain end, or at both. In particular, when the reactive silyl group occurs only at a main chain end, the effective network size in the organic polymer component contained in the cured products obtained becomes increased, so that it becomes easy to obtain rubber-like cured products showing high strength, high elongation and low elastic modulus.
The curable composition according to the present invention comprises, as essential components, an amidine compound (hereinafter sometimes referred to as “component (B)” or “amidine compound (B-1)”) as a silanol condensation catalyst (component (B)) and a carboxylic acid (hereinafter sometimes referred to as “component (C)” or “carboxylic acid (C)”) as a promoter (component (C)).
By using an amidine compound (B-1) as a silanol condensation catalyst, in spite of its being a non-organotin catalyst, it becomes possible for the curable composition according to the present invention to show a high level of curability that cannot have been arrived at with the conventional amine compound-based silanol condensation catalysts known in the art (aliphatic amines, aromatic amines, etc.) and for the cured products obtained to show good adhesiveness against various adherends.
As the conventional amine compound-based silanol condensation catalysts, there may be mentioned, for example, aliphatic primary amines such as methylamine, propylamine, isopropylamine, butylamine, amylamine, 2-ethylhexylamine, laurylamine, stearylamine and cyclohexylamine; aliphatic secondary amines such as dimethylamine, dipropylamine, diisopropylamine, dibutylamine, diamylamine, dioctylamine, bis(2-ethylhexyl)amine, dilaurylamine, dicetylamine, distearylamine and methylstearylamine; aliphatic tertiary amines such as triamylamine, trihexylamine and trioctylamine; aliphatic unsaturated amines such as triallylamine and oleylamine; aromatic amines such as laurylaniline, stearylaniline and triphenylamine; and other amines such as monoethanolamine, diethanolamine, triethanolamine, 3-hydroxypropylamine, diethylenetriamine, triethylenetetramine, benzylamine, 3-methoxypropylamine, 3-lauryloxypropylamine, 3-dimethylaminopropylamine, 3-diethylaminopropylamine, xylylenediamine, ethylenediamine, hexamethylenediamine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine and N-methylmorpholine.
The carboxylic acid (C) to be used in combination with the amidine compound (B-1) plays a role in enhancing the catalytic activity of the amidine compound (B-1).
As regards the mixing ratio between the amidine compound (B-1) and carboxylic acid (C) in the silanol condensation catalyst, the relation between the number of moles of nitrogen atoms derived from the amidine compound (B-1) and the number of moles of carboxyl groups derived from the carboxylic acid (C) is important, and it is important that the mole ratio between them (number (b) of moles of all (B-1)-derived nitrogen atoms/number (c) of moles of all (C)-derived carboxyl groups) be higher than 2 so that curable compositions showing good surface curability, depth curability and adhesiveness may be obtained.
The amidine compound (B-1) is not particularly restricted but may be any of the amidine compounds known in the art. Among them, those amidine compounds represented by the general formula (8) are preferred since they are high in catalytic activity and provide the organic polymer (A) with good curability.
R¹⁰N═CR¹¹—NR₂ ¹² (8)
(R¹⁰, R¹¹and the two R¹²s are independently a hydrogen atom or an organic group. Any two or more of R¹⁰, R¹¹and the two R¹²s may be combined together to form a ring structure.)
Preferred as R¹⁰in the general formula (8) is a hydrogen atom or a hydrocarbon group since, in such a case, the amidine compound is readily available and can provide the organic polymer (A) with good curability; more preferred is a hydrocarbon group in which the carbon atom at position 1 is saturated.
When R¹⁰is an organic group or a hydrocarbon group, the number of carbon atoms therein is preferably 1 to 20, more preferably 1 to 10, since, in such a case, the organic polymer (A) can be provided with good curability.
Preferred as R¹¹in the general formula (8) are a hydrogen atom, a —NR₂ ¹³group (in which the two R¹³s are independently a hydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms), a —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶group (in which R¹⁴, R¹⁵and the two R¹⁶s are independently a hydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms), a —N═C(NR₂ ¹⁷)—NR₂ ¹⁸group (in which the two R¹⁷s and the two R¹⁸s are independently a hydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms) or a hydrocarbon group containing 1 to 20 carbon atoms since, in such a case, the organic polymer (A) can be provided with good curability and the cured products obtained show good adhesiveness; more preferred are a hydrogen atom, a —NR₂ ¹³group (R¹³being as defined above), a —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶group (R¹⁴, R¹⁵and the two R¹⁶s being as defined above), a —N═C(NR₂ ¹⁷)—NR₂ ¹⁸group (the two R¹⁷s and the two R¹⁸s being as defined above) or a hydrocarbon group containing 1 to 10 carbon atoms; particularly preferred are a —NR₂ ¹³group (R¹³being as defined above), a —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶group (R¹⁴, R¹⁵and the two R¹⁶s being as defined above) or a —N═C(NR₂ ¹⁷)—NR₂ ¹⁸group (the two R¹⁷s and the two R¹⁸s being as defined above).
Those amidine compounds of the general formula (8) in which R¹¹is an —NR₂ ¹³group or a like organic group are called guanidine compounds.
Those amidine compounds of the general formula (8) in which R¹¹is such an organic group as the —NR¹⁴—C(═NR¹⁵)—NR₂ ⁵⁶group and —N═C(NR₂ ¹⁷)—NR₂ ¹⁸group mentioned above are called biguanide compounds.
Each of the two R¹²s in the general formula (8) is preferably a hydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group containing 1 to 10 carbon atoms, since, in such a case, the amidine compound is readily available and can provide the organic polymer (A) with good curability.
Since, when R¹¹in the general formula (8) is an —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶group (R¹⁴, R¹⁵and the two R¹⁶s being as defined above), the cured products obtained show good adhesiveness, it is preferred that at least one of R¹⁰, the two R¹²s, R¹⁴, R¹⁵and the two R¹⁶s be an aryl group.
When R¹¹in the general formula (8) is an —NR₂ ¹³group (R¹³being as defined above), the curability of the curable composition tends to decrease with the increase in the number of aryl groups bound to the nitrogen atoms contained in the molecule and, therefore, it is preferred that at least four of R¹⁰, the two R¹²s and the two R¹⁵s be either an organic group other than an aryl group or a hydrogen atom.
In view of their ready availability and their ability to provide the organic polymer (A) with good curability, those amidine compounds represented by the general formula (8) in which any two or more of R¹⁰, R¹¹and the two R¹²s are bound together to form a ring structure are preferred, and those cyclic amidine compounds represented by the general formula (9) are more preferred.
(R¹⁹, R²⁰and R²¹are independently a hydrogen atom or an organic group. R²⁰and R²¹may be bound together to form a ring structure.)
From the viewpoints of ready availability and ability to provide the organic polymer (A) with excellent curability, R¹⁹in the general formula (9) is preferably a divalent hydrocarbon group containing 1 to 10 carbon atoms, more preferably a divalent hydrocarbon group containing 1 to 10 carbon atoms in which the carbon atom at position 1 is saturated, still more preferably a divalent hydrocarbon group containing 1 to 5 carbon atoms in which the carbon atom at position 1 is saturated, particularly preferably a divalent hydrocarbon group containing 2 or 3 carbon atoms in which the carbon atom at position 1 is saturated. From the viewpoints of curability and adhesiveness, R²⁰is preferably a hydrogen atom, an —NR₂ ¹³group (R¹³being as defined above) or a hydrocarbon group containing 1 to 20 carbon atoms, more preferably a hydrogen atom, an —NR₂ ¹³group (R¹³being as defined above) or a hydrocarbon group containing 1 to 10 carbon atoms, particularly preferably an —NR₂ ¹³group (R¹³being as defined above). From the viewpoints of ready availability and ability to provide the organic polymer (A) with excellent curability, R²¹is preferably a hydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group containing 1 to 10 carbon atoms.
From the viewpoint of ready availability and of ability to provide the organic polymer (A) with good curability, it is preferred that R²⁰and R²¹be bound together to form a ring structure.
The amidine compound (B-1) preferably has a melting point of not lower than 23° C., more preferably not lower than 50° C., still more preferably not lower than 80° C., particularly preferably not lower than 120° C. When the melting point is lower than 23° C., an amidine compound (B-1)-derived liquid tends to bleed out, namely flow out onto the surface of the cured product, causing a problem of soiling one's hand upon touching of the hand with the cured product surface. The number of carbon atoms contained in the amidine compound (B-1) represented by the general formula (8) is preferably not smaller than 2, more preferably not smaller than 6, particularly preferably not smaller than 7.
When the number of carbon atoms is smaller than 2 (namely when the molecular weight is low), the volatility of the compound becomes increased, causing a tendency toward pollution of the work environment. It is not necessary to particularly specify the upper limit to the number of carbon atoms contained in the amidine compound (B-1); it is generally preferred, however, that the number be not larger than 10,000.
For the same reasons as mentioned above, the amidine compound (B-1) preferably has a molecular weight of not lower than 60, more preferably not lower than 120, particularly preferably not lower than 130. It is not necessary to particularly specify the upper limit to the molecular weight; it is generally preferred, however, that the molecular weight be not higher than 100,000.
The amidine compound (B-1) (inclusive of the guanidine compound and biguanide compound) is not particularly restricted but includes imidazole compounds such as imidazole, 2-methylimidazole and 2-ethyl-4-methylimidazole; amidine compounds such as 2-methyl-2-imidazoline, 2-ethyl-2-imidazoline, 2-n-propyl-2-imidazoline, 2-isopropyl-2-imidazoline, 2-n-octyl-2-imidazoline, 4,4-dimethyl-2-imidazoline, 4,5-dimethyl-2-imidazoline, 1-(1-aminoethyl)-2-octyl-2-imidazoline, 2-n-undecyl-2-imidazoline, 2-cyclohexyl-2-imidazoline, 2-benzyl-2-imidazoline, 2-phenyl-2-imidazoline, 2-[(3,4-dichlorophenoxy)methyl]-2-imidazoline, 1,4,5,6-tetrahydropyrimidine, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-n-propyl-2-methyl-1,4,5,6-tetrahydropyrimidine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene (DBA-DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN); guanidine compounds such as guanidine, 1,1,2-trimethylguanidine, 1,2,3-trimethylguanidine, 1,1,3,3-tetramethylguanidine, 1,1,2,3,3-pentamethylguanidine, 1-benzylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, 1,3-diphenylguanidine, 1,3-dibenzylguanidine, 1-benzyl-2,3-dimethylguanidine, N-(2-imidazolin-2-yl)-1-naphthalenamine, 2-phenyl-1,3-dicyclohexylguanidine, 1-benzylaminoguanidine, 1-(benzyloxy)guanidine, 1,1′-[4-(dodecyloxy)-m-phenylene]bisguanidine, guanylthiourea, 2-[(5,6,7,8-tetrahydronaphthalen-1-yl)amino]-2-imidazoline, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 7-isopropyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-cyclohexyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-phenyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene and 2,3,5,6-tetrahydro-3-phenyl-1H-imidazo[1,2-a]imidazole; and biguanide compounds such as biguanide, 1-methylbiguanide, 1-n-butylbiguanide, 1-(2-ethylhexyl)biguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide (OTBG), 1-(2-chlorophenyl)biguanide, 1-benzylbiguanide, 2-benzylbiguanide, 3-benzylbiguanide, N,N-diamidinoaniline, 1,5-ethylenebiguanide, 1-morpholinobiguanide, 1-(4-chlorobenzyloxy)biguanide, 1-n-butyl-N²-ethylbiguanide, 1,1′-ethylenebisbiguanide, 1-[3-(diethylamino)propyl]biguanide, 1-[3-(dibutylamino)propyl]biguanide, N′,N″-dihexyl-3,12-diimino-2,4,11,13-tetraazatetradecanedia midine, 1-(morpholinosulfonyl)benzylbiguanide, 1-(hydroxymethyl)biguanide, 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidine and 5-[3-(2,4,5-trichlorophenoxy)propoxy]-1-isopropylbiguanide. Either a single species among these amidine compounds may be incorporated in the curable composition or a combination of a plurality thereof may be incorporated in the curable composition.
Among the amidine compounds mentioned above, biguanide compounds are preferred since the curable compositions obtained show good adhesiveness. More specifically, biguanide, 1-n-butylbiguanide, 1,1-dimethylbiguanide, 1-phenylbiguanide and OTBG are preferred, and OTBG is particularly preferred.
Such cyclic amidine compounds as 2-methyl-2-imidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, DBU and DBN and such cyclic guanidine compounds as TBD, MTBD and 7-cyclohexyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred, and TBD and MTBD are more preferred, in view of their ability to provide the organic polymer (A) with good curability.
From the viewpoint that bleeding out from the cured products obtained can be inhibited, such amidine compounds having a melting point of not lower than 23° C. as TBD, 1-phenylguanidine, 1-n-butylbiguanide, 1,1-dimethylbiguanide, 1-phenylbiguanide and OTBG are preferred, and 1-phenylguanidine and OTBG are more preferred.
The carboxylic acid (C) to be used in combination with the amidine compound (B-1) plays a role in enhancing the catalytic activity of the amidine compound (B-1) and produces the effect of improving the surface curability and depth curability of the curable composition and, at the same time, produces the effect of improving the adhesiveness of the cured products obtained.
The carboxylic acid (C) is not particularly restricted but includes straight-chain saturated fatty acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid and lacceric acid; monoenoic unsaturated fatty acids such as undecylenic acid, linderic acid, tsuzuic acid, physeteric acid, myristoleic acid, 2-hexadecenoic acid, 6-hexadecenoic acid, 7-hexadecenoic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, asclepic acid, vaccenic acid, gadoleic acid, gondoic acid, cetoleic acid, erucic acid, brassidic acid, selacholeic acid, ximenic acid, lumequeic acid, acrylic acid, methacrylic acid, angelic acid, crotonic acid, isocrotonic acid and 10-undecenoic acid; polyenoic unsaturated fatty acids such as linoelaidic acid, linolic acid, 10,12-octadecadienoic acid, hiragonic acid, α-eleostearic acid, β-eleostearic acid, punicic acid, linolenic acid, 8,11,14-eicosatrienoic acid, 7,10,13-docosatrienoic acid, 4,8,11,14-hexadecatetraenoic acid, moroctic acid, stearidonic acid, arachidonic acid, 8,12,16,19-docosatetraenoic acid, 4,8,12,15,18-eicosapentaenoic acid, clupanodonic acid, nisinic acid and docosahexaenoic acid; branched fatty acids such as 1-methylbutyric acid, isobutyric acid, 2-ethylbutyric acid, isovaleric acid, tuberculostearic acid, pivalic acid, 2,2-dimethylbutyric acid, 2-ethyl-2-methylbutyric acid, 2,2-diethylbutyric acid, 2,2-dimethylvaleric acid, 2-ethyl-2-methylvaleric acid, 2,2-diethylvaleric acid, 2,2-dimethylhexanoic acid, 2,2-diethylhexanoic acid, 2,2-dimethyloctanoic acid, 2-ethyl-2,5-dimethylhexanoic acid, neodecanoic acid and versatic acid; triple bond-containing fatty acids such as propiolic acid, tariric acid, stearolic acid, crepenynic acid, xymenynic acid and 7-hexadecynoic acid; alicyclic carboxylic acids such as naphthenic acid, malvalic acid, sterculic acid, hydnocarpic acid, chaulmoogric acid, gorlic acid, 1-methylcyclopentanecarboxylic acid, 1-methylcyclohexanecarboxylic acid, 2-methylbicyclo[2.2.1]-5-heptene-2-carboxylic acid, 1-adamantanecarboxylic acid, bicycle[2.2.1]heptanes-1-carboxylic acid and bicycle[2.2.2]octane-1-carboxylic acid; oxygen-containing fatty acids such as acetoacetic acid, ethoxyacetic acid, glyoxylic acid, glycolic acid, gluconic acid, sabinic acid, 2-hydroxytetradecanoic acid, ipurolic acid, 2,2-dimethyl-3-hydroxypropionic acid, 2-hydroxyhexadecanoic acid, jalapinolic acid, juniperic acid, ambrettolic acid, aleuritic acid, 2-hydroxyoctadecanoic acid, 12-hydroxyoctadecanoic acid, 18-hydroxyoctadecanoic acid, 9,10-dihydroxyoctadecanoic acid, ricinolic acid, camlolenic acid, licanic acid, pheronic acid, cerebronic acid and 2-methyl-7-oxabicyclo[2.2.1]-5-heptene-2-carboxylic acid; and halogen-substituted monocarboxylic acids such as chloroacetic acid, 2-chloroacrylic acid and chlorobenzoic acid.
As far as aliphatic dicarboxylic acids are concerned, there is no particular restriction and there may be mentioned, for example saturated dicarboxylic acids such as adipic acid, azelaic acid, pimelic acid, suberic acid, sebacic acid, ethylmalonic acid, glutaric acid, oxalic acid, malonic acid, succinic acid, oxydiacetic acid, dimethylmalonic acid, ethylmethylmalonic acid, diethylmalonic acid, 2,2-dimethylsuccinic acid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid and 1,2,2-trimethyl-1,3-cyclopentanedicarboxylic acid; and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, acetylenedicarboxylic acid and itaconic acid.
As far as aliphatic polycarboxylic acids are concerned, there is no particular restriction and there may be mentioned, for example, tricarboxylic acids such as aconitic acid, 4,4-dimethylaconitic acid, citric acid, isocitric acid and 3-methylisocitric acid. As aromatic carboxylic acids, there may be mentioned aromatic monocarboxylic acids such as benzoic acid, 9-anthracenecarboxylic acid, atrolactic acid, anisic acid, isopropylbenzoic acid, salicylic acid and toluic acid; and aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, carboxyphenylacetic acid and pyromellitic acid.
Either a single species among the carboxylic acid (C) used in combination with the amidine compound (B-1) may be incorporated into the curable composition or a combination of a plurality thereof may be incorporated into the curable composition.
Among those mentioned above, monocarboxylic acids are more preferred, and chain monocarboxylic acids are still more preferred, in view of their good compatibility with the component (A).
The carboxylic acid (C) preferably has a melting point of not higher than 65° C., more preferably −50 to 50° C., particularly preferably −40 to 35° C. When the melting point of the carboxylic acid is in excess of 65° C., the handling of the acid becomes difficult and the workability tends to become worsened.
The carboxylic acid (C) preferably has 5 to 20 carbon atoms, more preferably 6 to 18 carbon atoms, particularly preferably 8 to 12 carbon atoms. When the number of carbon atoms is in excess of 20, the acid readily becomes a solid and shows a tendency toward decreased compatibility with the component (A) and, therefore, the activity of the curable composition tends to lower. On the other hand, when the number of carbon atoms is not larger than 5, the carboxylic acid increases in volatility and tends to emit an odor at raised levels.
From the viewpoints of availability and workability, as mentioned above, 2-ethylhexanoic acid, octylic acid, oleic acid, naphthenic acid, 2,2-dimethyloctanoic acid, 2-ethyl-2,5-dimethylhexanoic acid, neodecanoic acid and versatic acid are preferred among others.
The addition level of the (B-1) component is not particularly restricted provided that the requirement that the ratio (b)/(c) value mentioned above is higher than 2 is satisfied. Preferably, the addition level is 0.01 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, particularly preferably 1 to 10 parts by weight, per 100 parts by weight of the (A) component organic polymer.
When the addition level of the (B-1) component is below 0.01 part by weight, any practical rate of curing may not be obtained in some instances and, further, sometimes, it becomes difficult for the curing reaction to proceed to a sufficient extent. On the other hand, when the addition level of the (B-1) component is in excess of 20 parts by weight, the pot-life becomes too short, so that the workability tends to become poor.
The addition level of the (C) component is not particularly restricted provided that the requirement that the ratio (b)/(c) value mentioned above is higher than 2 is satisfied. Preferably, the addition level is about 0.01 to 20 parts by weight, more preferably about 0.1 to 10 parts by weight, particularly preferably about 1 to 7 parts by weight, per 100 parts by weight of the (A) component organic polymer. When the addition level of the (C) component is below 0.01 part by weight, any sufficient adhesiveness may not be obtained in some instances. On the other hand, when the addition level of the (C) component is in excess of 20 parts by weight, any practical level of depth curability may not be obtained in some instance.
While the curable composition of the present invention uses an amidine compound as a silanol condensation catalyst, another silanol condensation catalyst may be used, if necessary, in combination with the amidine compound so long as the effects of the present invention will not be reduced.
The silanol condensation catalyst other than the amidine compound is not particularly restricted but includes, for example, carboxylic acid metal salts such as tin carboxylates, lead carboxylates, bismuth carboxylates, potassium carboxylates, calcium carboxylates, barium carboxylates, titanium carboxylates, zirconium carboxylates, hafnium carboxylates, vanadium carboxylates, manganese carboxylates, iron carboxylates, cobalt carboxylates, nickel carboxylates and cerium carboxylates; titanium compounds such as tetrabutyl titanate, tetrapropyl titanate, titanium tetrakis(acetylacetonate), bis(acetylacetonato)diisopropoxytitanium and diisopropoxytitanium bis(ethyl acetoacetate); organotin compounds such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin phthalate, dibutyltin dioctanoate, dibutyltin bis(2-ethylhexanoate), dibutyltin bis(methyl maleate), dibutyltin bis(ethyl maleate), dibutyltin bis(butyl maleate), dibutyltin bis(octyl maleate), dibutyltin bis(tridecyl maleate), dibutyltin bis(benzyl maleate), dibutyltin diacetate, dioctyltin bis(ethyl maleate), dioctyltin bis(octyl maleate), dibutyltin dimethoxide, dibutyltin bis(nonylphenoxide), dibutenyltin oxide, dibutyltin oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(ethyl acetoacetonate), reaction products of dibutyltin oxide-silicate compound and reaction products of dibutyltin oxide-phthalic acid ester; aluminum compounds such as aluminum tris(acetylacetonate), aluminum tris(ethyl acetoacetate) and diisopropoxyaluminum ethyl acetoacetate; zirconium compounds such as zirconium tetrakis(acetylacetonate); various metal alkoxides such as tetrabutoxyhafnium; organic acid phosphoric acid esters; organic sulfonic acids such as trifluoromethanesulfonic acid and dodecylbenzenesulfonic acid; inorganic acids such as hydrochloric acid, phosphoric acid and boronic acid; and so forth.
The use of such a silanol condensation catalyst other than an amidine compound in combination with the amidine compound is expected to enhance the catalytic activity and thus improve the depth curability and surface curability of the curable composition and the adhesiveness and other properties of the cured products obtained. Among those enumerated above, titanium compounds, aluminum compounds and organic sulfonic acids, among others, are preferred since the surface curability of the organic polymer (A) is more enhanced by the use thereof; diisopropoxytitanium bis(ethyl acetoacetate), diisopropoxyaluminum ethyl acetoacetate and dodecylbenzenesulfonic acid are more preferred.
The combined use of titanium compounds is also preferred since the use gives curable compositions with increased strength and elongation; among them, diisopropoxytitanium bis(ethyl acetoacetate) is more preferred. The combined use of sulfonic acids is preferred since the solubility of the amidine compound (B-1) into the curable composition is increased thereby; among them, dodecylbenzenesulfonic acid is more preferred in view of its ready availability.
Since, however, when an organotin compound is used in combination, the toxicity of the curable composition tends to increase with the increase in organotin addition level, the addition level of the organotin compound is preferably as low as possible and, more specifically, it is preferably not higher than 1 part by weight, more preferably not higher than 0.5 part by weight, particularly preferably not higher than 0.05 part by weight, per 100 parts by weight of the organic polymer (A); substantial absence thereof is most preferred.
The organotin compound addition level in the “non-organotin type curable composition” so referred to herein is such that the organotin compound amounts to not more than 50% by weight, preferably not more than 30% by weight, more preferably not more than 10% by weight, particularly preferably not more than 1% by weight, of the compound components acting as silanol condensation catalysts; substantial absence thereof is most preferred. The curable composition of the present invention is preferably a non-organotin type curable composition and, from the viewpoints of toxicity and environmental stress, it is more preferably a tin-free curable composition containing substantially none of such tin compounds as organotin type compounds and tin carboxylates, still more preferably an organotin-free and carboxylic acid metal salt-free curable composition containing substantially none of organotin compounds and various carboxylic acid metal salts, particularly preferably a metal catalyst-free curable composition containing substantially none of the above-mentioned metal element-containing curing catalysts such as carboxylic acid metal salts, titanium compounds, organotin compounds, organoaluminum compounds and zirconium compounds.
In cases where a metal compound other than an organotin is used in combination, the addition level thereof more specifically is preferably not higher than 5 parts by weight, more preferably not higher than 2 parts by weight, per 100 parts by weight of the organic polymer (A), and substantial absence thereof is most preferred.
In the curable composition of the present invention, there may be incorporated a plasticizer if necessary. The plasticizer functions as an agent for adjusting the viscosity and slump characteristics of the curable composition and adjusting the tensile strength, elongation and like mechanical characteristics of the cured products obtained.
The plasticizer is not particularly restricted but includes: phthalic acid esters such as dibutyl phthalate, diheptyl phthalate, bis(2-ethylhexyl) phthalate and butyl benzyl phthalate; nonaromatic dibasic acid esters such as dioctyl adipate, dioctyl sebacate, dibutyl sebacate and isodecyl succinate; aliphatic esters such as butyl oleate and methyl acetylricinoleate; phosphoric acid esters such as tricresyl phosphate and tributyl phosphate; trimellitic acid esters; chlorinated paraffins; hydrocarbon type oils such as alkyldiphenyls and partially hydrogenated terphenyl; process oils; and epoxy type plasticizers such as epoxidized soybean oil and benzyl epoxystearate.
Addition of a polymeric plasticizer containing a polymer component in the molecule is preferred since such addition makes it possible to maintain the initial characteristics of the cured products obtained for a long period of time and, further, improve the drying characteristics (also referred to as applicability) of an alkyd paint when it is applied to the cured products obtained. The polymeric plasticizer is not particularly restricted but includes: vinyl polymers obtained by polymerization of vinyl monomers by various methods; polyalkylene glycol esters such as diethylene glycol dibenzoate, triethylene glycol dibenzoate and pentaerythritol esters; polyester type plasticizers derived from a dibasic acid such as sebacic acid, adipic acid, azelaic acid and phthalic acid and a dihydric alcohol such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol; polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, each having a molecular weight of not lower than 500, preferably not lower than 1000, or polyether derivatives derived from such polyether polyols by esterification or etherification of one or both hydroxyl groups therein; polystyrenes such as polystyrene and poly-α-methylstyrene; polybutadiene, polybutene, polyisobutylene, butadiene-acrylonitrile copolymers, polychloroprene and the like.
Among these polymeric plasticizers, those highly compatible with the organic polymer (A) are preferred and, for example, polyethers and vinyl polymers may be mentioned. Polyethers are more preferred since they provide the curable composition with good surface curability and depth curability and cause no curing retardation after storage; more specifically, polypropylene glycol is particularly preferred.
Further, vinyl polymers are preferred since they have high compatibility with the organic polymer (A) and provide the resulting cured products with good weather resistance and thermal stability; among them, acrylic polymers and/or methacrylic polymers are more preferred, and such acrylic polymers as polyacrylic acid alkyl esters are particularly preferred.
While the method of producing the polyacrylic acid alkyl esters is not particularly restricted, the living radical polymerization method is preferred because of capability of their giving polymers narrow in molecular weight distribution and possibly low in viscosity, and the atom transfer radical polymerization method is more preferred. Also particularly preferred is the method called “SGO process” and disclosed in Japanese Kokai Publication 2001-207157, which comprises continuously bulk-polymerizing an acrylic acid alkyl ester type compound under high temperature and high pressure conditions.
The number average molecular weight of the polymeric plasticizer is generally 500 to 15000, preferably 800 to 10000, more preferably 1000 to 8000, particularly preferably 1000 to 5000, most preferably 1000 to 3000. When the molecular weight of the polymeric plasticizer is too low, the plasticizer may escape from the cured products obtained with the lapse of time due to heat or rainfall and, as a result, it becomes no longer possible to maintain the initial physical characteristics, staining by adhesion of dust may possibly be caused and the alkyd applicability tends to become poor. On the other hand, when the molecular weight is excessively high, the viscosity of the curable composition will increase and the workability tends to become poor.
The molecular weight distribution of the polymeric plasticizer is not particularly restricted but preferably is narrow, for example narrower than 1.80, preferably not wider than 1.70, more preferably not wider than 1.60, still more preferably not wider than 1.50, particularly preferably not wider than 1.40, most preferably not wider than 1.30.
In the case of polyether type polymers, the number average molecular weight is determined by the end-group analysis and, in the case of other polymers, it is determined by the GPC method. The molecular weight distribution (Mw/Mn) is measured by the GPC method (on the polystyrene equivalent basis).
The polymeric plasticizer may be a reactive silyl group-containing one or a silyl group-free one and, in cases where a reactive silyl group-containing polymeric plasticizer is added, the polymeric plasticizer is preferably involved in the curing reaction and thus, the plasticizer can be prevented from migrating from the cured products obtained.
The reactive silyl group-containing polymeric plasticizer is preferably a compound whose silyl group content is, on an average, not more than one, preferably not more than 0.8, per molecule. When a reactive silyl group-containing plasticizer, in particular a reactive silyl group-containing oxyalkylene polymer, is added, it is preferred that the number average molecular weight thereof be lower than that of the organic polymer (A) so that a satisfactory plasticizing effect may be obtained.
The plasticizer to be added may comprise a single species or a combination of a plurality of species. It is also possible to add a low-molecular-weight plasticizer and a polymeric plasticizer in combination. The plasticizer addition may also be made on the occasion of the production of the organic polymer (A).
When a plasticizer is added, the addition level thereof is preferably 5 to 150 parts by weight, more preferably 10 to 120 parts by weight, particularly preferably 20 to 100 parts by weight, per 100 parts by weight of the organic polymer (A). At addition levels lower than 5 parts by weight, there is a tendency for the plasticizing effect to be little produced and, at levels exceeding 150 parts by weight, there arises a tendency for the mechanical strength of the cured products to become insufficient.
In the curable composition of the present invention, there may be incorporated an adhesiveness-imparting agent, if necessary.
The adhesiveness-imparting agent is a compound containing a hydrolyzable silyl group and other functional group(s) in the molecule and, when incorporated into the curable composition, effectively improves the adhesiveness of the resulting cured products to various adherends and/or effectively removes (dehydrates) the moisture contained in the curable composition.
Further, the adhesiveness-imparting agent is a compound capable of not only producing the effects mentioned above but also functioning as a physical property modifier and/or a dispersibility-improving agent for inorganic fillers.
The hydrolyzable silyl group occurring in the adhesiveness-imparting agent may be any of those enumerated hereinabove as examples of the hydrolyzable group. Among those, a methoxy group, an ethoxy group, and the like are preferred because of their proper rate of hydrolysis. The number of hydrolyzable groups contained in each molecule of the adhesiveness-imparting agent is preferably not smaller than 2, particularly preferably not smaller than 3.
As examples of the functional group other than the hydrolyzable silyl group as occurring in the adhesiveness-imparting agent, there may be mentioned a substituted or unsubstituted amino group, mercapto group, epoxy group, carboxyl group, vinyl group, isocyanato group and isocyanurate group, and halogen atoms. In particular, substituted or unsubstituted amino group-containing adhesiveness-imparting agents are preferred since they show good compatibility with the guanidine compound (B-1) and the like. Substituted or unsubstituted amino group-containing adhesiveness-imparting agents are preferred also in view of their ability to enhance the adhesiveness between the cured products obtained and adherends.
The adhesiveness-imparting agent is not particularly restricted but includes aminosilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, 7-(2-aminoethyl)aminopropylmethyldiethoxysilane, 7-(2-aminoethyl)aminopropyltriisopropoxysilane, γ-(2-(2-aminoethyl)aminoethyl)aminopropyltrimethoxysilane, γ-(6-aminohexyl)aminopropyltrimethoxysilane, 3-(N-ethylamino)-2-methylpropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-phenylaminomethyltrimethoxysilane, N-benzyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl)aminomethyltrimethoxysilane and N,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine; ketimine type silanes such as N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, and condensation products resulting from partial condensation of the silanes mentioned above.
Among the adhesiveness-imparting agents mentioned above, γ-aminopropyltrimethoxysilane is particularly preferred from the viewpoints of compatibility, transparency and availability.
The adhesiveness-imparting agent to be incorporated in the curable composition may comprise a single species or a combination of a plurality of species. In selecting the adhesiveness-imparting agent, it is preferred that one containing a hydrolyzable group of the same structure as the hydrolyzable group occurring in the organic polymer (A) so that the surface curability of the curable composition may be prevented from changing during storage. Thus, when the hydrolyzable silyl group in the organic polymer (A) is a methoxysilyl group, an adhesiveness-imparting agent with a methoxysilyl group structure should be selected and, when the hydrolyzable silyl group in the organic polymer (A) is an ethoxysilyl group, an adhesiveness-imparting agent with an ethoxysilyl group structure should be selected.
To the curable composition of the present invention, there may be added a filler, if necessary. The filler is not particularly restricted but includes: reinforcing fillers such as fumed silica, precipitated silica, crystalline silica, fused silica, dolomite, silicic anhydride, hydrous silicic acid and carbon black; heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, diatomaceous earth, calcined clay, clay, talc, titaniumoxide, bentonite, organicbentonite, ferric oxide, fine aluminum powder, flint powder, zinc oxide, activated zinc white, shirasu balloons, glass microballoons, organic microballoons based on a phenol resin or a vinylidene chloride resin, organic powders such as PVC powder and PMMA powder; and fibrous fillers such as asbestos, glass fibers and filaments.
When a filler is added, the addition level thereof is preferably 1 to 250 parts by weight, more preferably 10 to 200 parts by weight, per 100 parts by weight of the organic polymer (A).
On the occasion of using the curable composition as a one-pack type adhesive or sealant, it is preferred, for obtaining good storage stability, that such a filler as mentioned above be uniformly mixed with a dehydrating agent such as calcium oxide and the mixture be allowed to stand in a sealed bag made of an airtight material for a proper period of time for dehydrating and drying, and then used, as disclosed in Japanese Kokai Publication 2001-181532 and the like.
When the cured products obtained are to be used in the fields of application where transparency is required, a polymer powder containing a polymer of methyl methacrylate and the like, and noncrystalline silica, are preferred as the filler to be added, as disclosed in Japanese Kokai Publication H11-302527 and the like; hydrophobic silica and the like, as disclosed in Japanese Kokai Publication 2000-38560 and the like, is more preferred.
The hydrophobic silica, so referred to herein, is a product derived by treating the surface of the silicon dioxide fine powder generally occupied by silanol (—SiOH) groups with an organosilicon halide or an alcohol for conversion of those groups to (—SiO-hydrophobic) groups. The hydrophobic silica is not particularly restricted but includes, for example, products obtained by treating silanol groups occurring on a silicon dioxide fine powder with dimethylsiloxane, hexamethyldisilazane, dimethyldichlorosilane, trimethoxyoctylsilane, trimethylsilane, and the like. The untreated silicon dioxide fine powder whose surface is occupied by silanol (—SiOH) groups is called hydrophilic silica fine powder.
When the cured products obtained are to be used in the fields of application where high strength is required, silicon compounds such as fumed silica, precipitated silica, crystalline silica, fused silica, dolomite, silicic anhydride and hydrous silicic acid; carbon black, surface-treated finely divided calcium carbonate, calcined clay, clay, activated zinc white and the like are preferred as the filler to be added, and the addition level thereof is preferably 1 to 200 parts by weight per 100 parts by weight of the organic polymer (A).
Further, when the cured products obtained are to be used in the fields of application where low strength and high elongation modulus are required, titanium oxide, calcium carbonate such as heavy calcium carbonate, magnesium carbonate, talc, ferric oxide, zinc oxide and shirasu balloons are preferred as the filler to be added, and the addition level thereof is preferably 5 to 200 parts by weight per 100 parts by weight of the organic polymer (A).
When calcium carbonate is added, the tendency toward improvements in the breaking strength, breaking elongation and adhesiveness of the cured products obtained increases as the specific surface area increases. Only one of these filler species may be added or a plurality of species thereof may be added in combination.
The example of addition of a plurality of additives is not particularly restricted but the combined use of a surface-treated fine calcium carbonate and a calcium carbonate larger in particle diameter such as heavy calcium carbonate is preferred since cured products excellent in physical characteristics can be obtained.
Preferred as the surface-treated fine calcium carbonate are those whose particle diameter is not larger than 0.5 μm and whose particle surface has been treated with a fatty acid and a fatty acid salt.
Preferred as the calcium carbonate having a large particle diameter are those whose particle diameter is not smaller than 1 μm and whose particle surface has not been treated.
In cases where the curable composition is required to have good workability (releasability, etc.) or where the surface of the cured products obtained is required to be matted, organic balloons or inorganic balloons are preferred as the filler to be added. These fillers may be surface-treated or non-surface-treated, and only one species thereof may be added or a plurality of species thereof may be added in admixture. For improving the workability (releasability, etc.), the particle diameter of the balloons is preferably not larger than 0.1 mm and, for rendering the cured product surface matted, it is preferably 5 to 300 μm.
The curable composition of the present invention, which gives cured products excellent in chemical resistance, is suited for use, in particular, as a sealant, adhesive or like composition for siding boards in ceramic and like systems and for housing outside-wall joints and outside-wall tiles.
On the occasion of use in such fields of application, the cured products obtained appear or exist on the joints or like observable surfaces and, therefore, it is desirable that the cured product design be in harmony with the outside wall design. In recent years, in particular, the sputtering coating and the addition of colored aggregates, among others, have been employed for providing luxurious outside walls, so that the designs of cured products are becoming more and more important.
For obtaining luxurious designs, a scaly or granular substance is incorporated in the curable composition of the present invention. The addition of a granular substance gives sandy or sandstone-like rough surfaces, and the addition of a scaly substance gives surfaces rendered uneven due to scales.
The cured products obtained are in harmony with luxurious outside walls and are excellent in chemical resistance, so that the luxurious appearance thereof can be maintained for a long period of time.
The scaly or granular substance is not particularly restricted but includes, for example, one disclosed in Japanese Kokai Publication H09-53063, and the diameter thereof is properly selected according to the outside wall material and design and is preferably not smaller than 0.1 mm, more preferably 0.1 to 5.0 mm. In the case of a scaly substance, the thickness of scales is preferably 1/10 to ⅕ (0.01 to 1.00 mm) of the diameter.
The addition level of the scaly or granular substance is properly selected according to the size of the scaly or granular substance, the outside-wall material and design and other factors; preferably, the addition level is 1 to 200 parts by weight per 100 parts by weight of the curable composition.
The material of the scaly or granular substance is not particularly restricted but includes natural products such as silica sand and mica, synthetic rubbers, synthetic resins, and inorganic materials such as alumina. These may be appropriately colored according to the outside wall material, design, and so forth so that the design quality of the composition applied to joints and so forth may be enhanced.
Preferred methods of finishing are those disclosed in Japanese Kokai Publication H09-53063 and the like.
The scaly or granular substance may be incorporated in advance in the curable composition or may be admixed with the curable composition of the occasion of use thereof.
It is also possible, for the same purposes, to add balloons (preferably having an average particle diameter of not smaller than 0.1 mm) to the curable composition, thereby providing the resulting cured product surface with a coarse feel such as a sandy or sandstone feel and, further, contributing to weight reduction. The “balloons” are spherical hollow fillers.
The balloons are not particularly restricted but include, for example, those disclosed in Japanese Kokai Publications H10-251618, H02-129262, H04-8788, H04-173867, H05-1225, H07-113073, H09-53063, 2000-154368 and 2001-164237 and WO 97/05201.
As the material of balloons, there may be mentioned inorganic materials such as glass, shirasu and silica; and organic materials such as phenol resins, urea resins, polystyrene and Saran. Mention may further be made of composite materials of an inorganic material and an organic material; and laminates comprising a plurality of layers. These may be used singly or a plurality species thereof may be used in combination.
It is also possible to use balloons subjected to surface coating treatment, treatment with various surface treatment agents or some other treatment; as typical examples, there may be mentioned organic balloons coated with calcium carbonate, talc, titanium oxide or the like, and inorganic balloons surface-treated with an adhesiveness-imparting agent.
Further, the balloons preferably have a particle diameter of not smaller than 0.1 mm, more preferably 0.2 mm to 5.0 mm, particularly preferably 0.5 mm to 5.0 mm. When the diameter is smaller than 0.1 mm, the addition even in large amounts only increases the viscosity of the composition, sometimes failing to provide the resulting cured products with a coarse feel.
When balloons are added, the addition level thereof can be properly selected according to the intended decorative effect; it is preferred that balloons having a particle diameter of not smaller than 0.1 mm be added in an amount such that the volume concentration thereof in the curable composition amounts to 5 to 25% by volume, more preferably 8 to 22% by volume. When the volume concentration of balloons is below 5% by volume, the desired coarse feel tends to become lost. At level exceeding 25% by volume, the viscosity of the curable composition increases and the workability thereof tends to become poor; further, the modulus of the cured products increases and the fundamental performance characteristics of the sealant or adhesive tend to become impaired.
On the occasion of adding balloons, it is also possible to add, in combination, such an anti-slip agent as the one disclosed in Japanese Kokai Publication 2000-154368 or such an amine compound capable of rendering the resulting cured product surface uneven and matted as the one disclosed in Japanese Kokai Publication 2001-164237. Preferred as the amine compound mentioned above are primary and/or secondary amines having a melting point of 35° C. or higher.
Also usable as the balloons are thermally expandable minute hollow particles disclosed in Japanese Kokai Publication 2004-51701 or 2004-66749, for instance. The “thermally expandable minute hollow particles” are spherical plastic bodies made of a polymer shell material (vinylidene chloride type copolymer, acrylonitrile type copolymer or vinylidene chloride-acrylonitrile copolymer) with a low-boiling compound such as a hydrocarbon containing 1 to 5 carbon atoms as spherically enclosed therein.
By adding thermally expandable minute hollow particles to the curable composition of the present invention, it becomes possible to obtain, without using any organic solvent at all, a thermally removable adhesive composition which, when no more required, can be peeled off with ease only by heating without destruction of the adherend materials. This is based on the mechanism such that when the adhesive portion is heated, the gas pressure inside the shells of the thermally expandable minute hollow particles increases and the polymer shell material is softened and dramatically expanded to cause peeling at the adhesive interface.
When the curable composition of the present invention contains sealant curing particles as well, the cured products obtained can have an uneven rough surface and, thus, the decorative feature thereof can be improved. The preferred diameter, addition level, material and the like of the sealant curing particles are disclosed in Japanese Kokai Publication 2001-115142, and the diameter is preferably 0.1 mm to 1 mm, more preferably 0.2 to 0.5 mm. The addition level is preferably 5 to 100 parts by weight, more preferably 20 to 50 parts by weight, per 100 parts by weight of the curable composition. The material is not particularly restricted but may be any of the materials used in sealing compositions; thus, mention may be made of urethane resins, silicones, modified silicones and polysulfide rubbers, for example.
Among those mentioned above, modified silicone type sealant curing particles are preferred.
To the curable composition of the present invention, there may be added a silicate, if necessary. The silicate acts as a crosslinking agent on the organic polymer (A) and functions to bring about improvements in the restorability, durability and creep resistance of the cured products obtained.
Further, the addition of a silicate brings about improvements in the adhesiveness and water-resistant adhesiveness and in the bond durability under high-temperature and high-pressure conditions. The silicate is not particularly restricted but includes, for example, tetraalkoxysilanes or partial hydrolysis condensation products derived therefrom; more specifically, there may be mentioned tetraalkoxysilanes (tetraalkyl silicates) such as tetramethoxysilane, tetraethoxysilane, ethoxytrimethoxysilane, dimethoxydiethoxysilane, methoxytriethoxysilane, tetra-n-propoxysilane, tetra-1-propoxysilane, tetra-n-butoxysilane, tetra-1-butoxysilane and tetra-t-butoxysilane as well as partial hydrolysis condensation products derived therefrom.
When a silicate is added, the addition level thereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the organic polymer (A).
The tetraalkoxysilane-derived partial hydrolysis condensation product mentioned above is not particularly restricted but includes, for example, products derived from tetraalkoxysilanes by addition of water thereto to cause partial hydrolysis and condensation.
The addition of a tetraalkoxysilane-derived partial hydrolysis condensation product is preferred since such condensation product produces significant improvements in restorability, durability and creep resistance of the cured products obtained as compared with the corresponding composition containing the tetraalkoxysilane added thereto.
Commercially available as the tetraalkoxysilane-derived partial hydrolysis condensation product are, for example, Methyl Silicate 51 and Ethyl Silicate 40 (both being products of Colcoat Co., Ltd.); these can be used as additives.
For the purpose of inhibiting the surface curability of the curable composition from changing during storage, it is preferred that the silicate be selected from among those in which the silicon atom-bound hydrolyzable groups are the same as the hydrolyzable groups in the reactive silyl group occurring in the organic polymer (A). Thus, when the organic polymer (A) contains methoxysilyl groups, a methoxysilyl group-containing silicate is preferably selected and, when the organic polymer (A) contains ethoxysilyl groups, an ethoxysilyl group-containing silicate is preferably selected.
In the curable composition of the invention, there may be incorporated a tackifier, if necessary.
The tackifier is not particularly restricted provided that it is one in common use, irrespective of whether it occurs as a solid or liquid at ordinary temperature. For example, there may be mentioned styrene block copolymers, hydrogenation products derived therefrom, phenol resins, modified phenol resins (e.g. cashew oil-modified phenol resins, tall oil-modified phenol resins), terpene-phenol type resins, xylene-phenol type resins, cyclopentadiene-phenol type resins, coumarone-indene type resins, rosin type resins, rosin ester type resins, hydrogenated rosin ester type resins, xylene type resins, low-molecular-weight polystyrene type resins, styrene copolymer resins, petroleum resins (e.g. C5 hydrocarbon type resins, C9 hydrocarbon type resins, C5C9 hydrocarbon copolymer resins), hydrogenated petroleum resins, terpene type resins, DCPD resins, and petroleum resins. These may be added singly or a plurality thereof may be added in combination.
The styrene block copolymers and hydrogenation products derived therefrom mentioned above are not particularly restricted but include, for example, styrene-butadiene-styrene block copolymers (SBSs), styrene-isoprene-styrene block copolymers (SISs), styrene-ethylenebutylene-styrene block copolymers (SEBSs), styrene-ethylenepropylene-styrene block copolymers (SEPSs) and styrene-isobutylene-styrene block copolymers (SIBSs).
When a tackifier is added, the addition level thereof is preferably 5 to 1,000 parts by weight, more preferably 10 to 100 parts by weight, per 100 parts by weight of the organic polymer (A).
In the curable composition of the present invention, there may be incorporated a solvent or diluent, if necessary. The solvent or diluent is not particularly restricted but includes, for example, aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones and ethers. These may be added singly or a plurality thereof may be added in combination.
When a solvent or diluent is added, the solvent or diluent preferably has a boiling point of 150° C. or higher, more preferably 200° C. or higher, so that the volatile components in the solvent or diluent may be inhibited from dissipating into the air on the occasion of indoor use of the curable composition.
In the curable composition of the present invention, there may be incorporated a physical property modifier, if necessary. The physical property modifier functions so as to adjust the tensile characteristics and hardness of the resulting cured products.
The physical property modifier is not particularly restricted but includes, for example, alkylalkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane and n-propyltrimethoxysilane; alkylisopropenoxysilanes such as dimethyldiisopropenoxysilane, methyltriisopropenoxysilane and γ-glycidoxypropylmethyldiisopropenoxysilane; functional group-containing alkoxysilanes such as γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyldimethylmethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-mercaptopropylmethyldimethoxysilane; silicone varnishes; and polysiloxanes. These may be added singly or a plurality thereof may be added in admixture.
Among such physical property modifiers, those which form, upon hydrolysis, a compound containing a monovalent silanol group in the molecule are preferred since they are effective in reducing the modulus of the resulting cured products without worsening the surface stickiness thereof; among them, those which form, upon hydrolysis, trimethylsilanol are more preferred.
The compounds which form, upon hydrolysis, a compound containing monovalent silanol group in the molecular are not particularly restricted but include: those compounds disclosed in Japanese Kokai Publication H05-117521; compounds derived from an alkyl alcohol, such as hexanol, octanol and decanol, and capable of forming, upon hydrolysis, such an organosilicon compound represented by R₃SiOH as trimethylsilanol; and those compounds disclosed in Japanese Kokai Publication H11-241029 which are compounds derived from a polyhydric alcohol containing 3 or more hydroxyl groups in each molecule, for example trimethylolpropane, glycerol, pentaerythritol or sorbitol, and capable of forming, upon hydrolysis, such an organosilicon compound represented by R₃SiOH as trimethylsilanol.
Further, mention may be made of those compounds disclosed in Japanese Kokai Publication H07-258534 which are derived from an oxypropylene polymer and capable of forming, upon hydrolysis, such an organosilicon compound represented by R₃SiOH as trimethylsilanol and, further, those compounds disclosed in Japanese Kokai Publication H06-279693 which contain a crosslinkable hydrolyzable silyl group and a silyl group capable of forming, upon hydrolysis, a monovalent silanol group-containing compound.
When a physical property modifier is added, the addition level thereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the organic polymer (A).
In the curable composition of the present invention, there may be incorporated a thixotropic agent (anti-sagging agent), if necessary. The term “thixotropic agent” refers to an agent functioning to prevent the curable composition from sagging and improve the workability thereof.
The thixotropic agent is not particularly restricted but includes, for example, polyamide waxes; hydrogenated castor oil derivatives; and metal soaps such as calcium stearate, aluminum stearate and barium stearate. Further, mention may be made of those rubber powders having a particle diameter of 10 to 500 μm which are disclosed in Japanese Kokai Publication H11-349916, and those organic fibers disclosed in Japanese Kokai Publication 2003-155389. These thixotropic agents (antisagging agents) may be added singly or a plurality of species may be added in combination.
When a thixotropic agent is added, the addition level thereof is preferably 0.1 to 20 parts by weight per 100 parts by weight of the organic polymer (A).
In the curable composition of the present invention, there may be incorporated, for example, a compound containing an epoxy group in each molecular, if necessary. By adding an epoxy group-containing compound, it becomes possible to enhance the restorability of the cured products obtained.
The epoxy group-containing compound is not particularly restricted but includes, for example, epoxidized unsaturated fats and oils; epoxidized unsaturated fatty acid esters; alicyclic epoxy compounds; epichlorohydrin derivatives and like compounds; and mixtures thereof. More specifically, there may be mentioned epoxidized soybean oil, epoxidized linseed oil, bis(2-ethylhexyl)-4,5-epoxycyclohexane-1,2-dicarboxylate (E-PS), epoxyoctyl stearate, epoxybutyl stearate and the like. Among these, E-PS is preferred.
When an epoxy compound is added, the addition level thereof is preferably 0.5 to 50 parts by weight per 100 parts by weight of the organic polymer (A).
In the curable composition of the present invention, there may be added a photocurable substance, if necessary. The photocurable substance is a substance capable of undergoing, under the action of light, chemical changes in molecular structure in a short period of time which lead to changes in physical properties such as curing. The addition of a photocurable substance to the curable composition results in the formation of a photocurable substance-based layer on the surface of the cured products obtained and thus in improvements in the stickiness and weather resistance of the cured products.
The photocurable substance is not particularly restricted but includes those known in the art, such as organic monomers, oligomers, resins, and compositions containing any of them; for example, there may be mentioned unsaturated acrylic compounds, vinyl cinnamate polymers and azidized resins.
As the unsaturated acrylic compounds, there may be mentioned monomers, oligomers, or mixtures thereof, containing one or a plurality of acrylic or methacrylic unsaturated groups in each molecule, and, specifically, propylene (or butylene or ethylene) glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate and like monomers or oligoesters having a molecular weight not exceeding 10,000. More specifically, there may be mentioned, for example, such special acrylates as (bifunctional) Aronix M-210, Aronix M-215, Aronix M-220, Aronix M-233, Aronix M-240 and Aronix M-245; (trifunctional) Aronix M-305, Aronix M-309, Aronix M-310, Aronix M-315, Aronix M-320 and Aronix M-325, and (polyfunctional) Aronix M-400 (all Aronix products being available from Toagosei Co., Ltd.). Among these, acrylic functional group-containing compounds are preferred, and compounds containing, on an average, 3 or more acrylic functional groups in each molecule are more preferred.
The vinyl cinnamate polymers are photosensitive resins having cinnamoyl groups as photosensitive groups, which are compounds resulting from esterification of polyvinyl alcohol with cinnamic acid, and many other derivatives of vinyl cinnamate polymers.
The azidized resins are known as photosensitive resins in which azide groups are photosensitive groups and include rubber photosensitive solutions generally containing a diazide compound added as a photosensitizer and, further, those detailed examples are described in “Kankosei Jushi (Photosensitive Resins)” (published Mar. 1, 1972 by Insatsu Gakkai Shuppanbu Ltd., p. 93 ff., p. 106 ff., and p. 117 ff.). These may be used either singly or in admixture, if necessary together with a sensitizer.
In some cases, the addition of a sensitizer such as a ketone and nitro compound or a promoter such as an amine enhances the effect.
When a photocurable substance is added, the addition level thereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the organic polymer (A). At levels of 0.1 part by weight or below, the effect of enhancing the weather resistance of the cured products obtained is very little and, at levels of 20 parts by weight or above, the cured products obtained are too hard, tending to undergo cracking or the like.
In the curable composition of the present invention, there may be incorporated an oxygen-curable substance, if necessary. The oxygen-curable substance can be cured upon reaction with oxygen in the air, and the addition of an oxygen-curable substance makes it possible to reduce the stickiness of the cured product surface and to prevent dirt and dust from adhering to the surface through the formation of a cured layer in the vicinity of the cured product surface obtained.
The oxygen-curable substance is not particularly restricted but may be any of the compounds containing an unsaturated compound capable of reacting with oxygen in the air; thus, for example, there may be mentioned drying oils such as tung oil and linseed oil, and various alkyd resins obtained by modifying such compounds; drying oil-modified acrylic polymers, epoxy type resins and silicone type resins; liquid polymers obtained by polymerizing or copolymerizing such a diene compound(s) as butadiene, chloroprene, isoprene and 1,3-pentadiene, for example 1,2-polybutadiene, 1,4-polybutadiene and C₅-C₈diene polymers; liquid copolymers obtained by copolymerizing such a diene compound with a vinyl compound, such as acrylonitrile and styrene, copolymerizable with the diene compound, in a manner such that the diene compound serve as the main component, for example NBR and SBR; and, further, various modifications thereof (maleinated modifications, boiled oil modifications, etc.).
Among those mentioned above, tung oil and liquid diene type polymers are preferred. The oxygen-curable substance to be added may comprise a single species or a combination of a plurality of species.
When a catalyst and/or metal dryer which are capable of promoting the curing reaction are added in admixture with the oxygen-curable substance, the effect may be enhanced.
The catalyst and metal dryer for promoting the curing reaction are not particularly restricted but include, for example, metal salts such as cobalt naphthenate, lead naphthenate, zirconium naphthenate, cobalt octylate and zirconium octylate, and amine compounds.
When an oxygen-curable substance is added, the addition level thereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the organic polymer (A). At addition levels below 0.1 part by weight, the effect of improving the stain resistance of the cured products obtained tends to become insufficient and, at levels exceeding 20 parts by weight, the tensile characteristics and the like of the cured products obtained tend to become impaired.
Further, the oxygen-curable substance is preferably added in admixture with a photocurable substance, as disclosed in Japanese Kokai Publication H03-160053.
In the curable composition of the present invention, there may be incorporated an antioxidant, if necessary. By adding an antioxidant, it becomes possible to enhance the thermal stability of the cured products obtained.
The antioxidant is not particularly restricted but includes hindered phenol type, monophenol type, bisphenol type and polyphenol type antioxidants. Among these, hindered phenol type antioxidants are preferred. Also preferred are hindered amine type light stabilizers such as Tinuvin 622LD and Tinuvin 144; Chimassorb 944 LD and Chimassorb 119FL (all four being products of Chiba Specialty Chemicals); ADK STAB LA-57, ADK STAB LA-62, ADK STAB LA-67, ADK STAB LA-63 and ADK STAB LA-68 (all five being products of Adeka Corporation); and Sanol LS-770, Sanol LS-765, Sanol LS-292, Sanol LS-2626, Sanol LS-1114 and Sanol LS-744 (all six being product of Sankyo Lifetech Co., Ltd.). Specific examples of the antioxidants are disclosed also in Japanese Kokai Publications H04-283259 and H09-194731.
When an antioxidant is added, the addition level thereof is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the organic polymer (A).
In the curable composition of the present invention, there may be incorporated a light stabilizer, if necessary. By adding a light stabilizer, the cured products obtained can be prevented from undergoing photooxidative degradation.
The light stabilizer is not particularly restricted but includes benzotriazole type, hindered amine type and benzoate type compounds. Among these, hindered amine type light stabilizers are preferred.
When a light stabilizer is added, the addition level thereof is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the organic polymer (A). A specific example of the light stabilizer is disclosed in Japanese Kokai Publication H09-194731 as well.
When such a photocurable substance as an unsaturated acrylic compound is added to the curable composition of the present invention, a tertiary amine group-containing hindered amine type light stabilizer is preferably added as disclosed in Japanese Kokai Publication H05-70531 since, then, the storage stability of the curable composition is improved.
The tertiary amine group-containing hindered amine type light stabilizer is not particularly restricted but includes Tinuvin 622LD, Tinuvin 144 and Chimassorb 119FL (all three being products of Ciba Specialty Chemicals Inc.); ADK STAB LA-57, LA-62, LA-67 and LA-63 (all four being products of Adeka Corporation); and Sanol LS-765, LS-292, LS-2626, LS-1114 and LS-744 (all five being products of Sankyo Lifetech Co., Ltd.)
To the curable composition of the present invention may be added an ultraviolet absorber, if necessary. When an ultraviolet absorber is added to the curable composition, the surface weather resistance of the cured products obtained is improved.
The ultraviolet absorber is not particularly restricted but includes benzophenone type, benzotriazole type, salicylate type, substituted tolyl type and metal chelate type compounds.
Among these, benzotriazole type ultraviolet absorbers are preferred.
When an ultraviolet absorber is added to the curable composition, the addition level thereof is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the organic polymer (A).
The antioxidant, light stabilizer and ultraviolet absorber mentioned above are preferably added in combination to the curable composition and, for example, a phenol or hindered phenol antioxidant, a hindered amine type light stabilizer and a benzotriazole type ultraviolet absorber are preferably added in admixture with the curable composition.
To the curable composition of the present invention may be added a flame retardant, if necessary. The flame retardant is not particularly restricted; thus, for example, phosphorus type flame retardants such as ammonium polyphosphate and tricresyl phosphate; aluminum hydroxide, magnesium hydroxide, and flame retardants such as thermally expandable graphite may be added to the curable composition. The flame retardant to be added thereto may comprise a single species or a combination of a plurality of species.
When a flame retardant is added to the curable composition, the addition level thereof is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, per 100 parts by weight of the organic polymer.
To the curable composition of the present invention may be added, if necessary, various additives other than those mentioned above for the purpose of adjusting various physical properties of the curable composition or of the cured products to be obtained. As such additives, there may be mentioned, for example, curability modifiers, radical inhibitors, metal deactivators, antiozonants, phosphorus type peroxide decomposers, lubricants, pigments, blowing agents, antitermites and antifungal agents. Specific examples of these are disclosed in publications such as Japanese Kokoku Publications H04-69659 and H07-108928, and Japanese Kokai Publications S63-254149, S64-22904 and 2001-72854. These additives may be added singly to the curable composition or a plurality thereof may be added in combination to the curable composition.
In cases where the curable composition is of the one-pack type, the composition contains all components as mixed up in advance and, thus, curing may proceed during storage if moisture is present in formulation components. Therefore, those formulation components which contain moisture are preferably dehydrated and dried prior to addition or dehydrated during compounding and kneading by reducing the pressure, for instance.
When the curable composition is of the two-pack type, it is not necessary to incorporate the curing catalyst in the main component having a reactive silyl group-containing organic polymer and, therefore, even if some moisture is contained in the formulation components, the risk of the progress of curing (gelation) is low; in cases where long-term storage stability is required, however, it is preferred that the formulation components be dehydrated or dried.
As for the method of dehydrating or drying, the method comprising drying by heating or the method comprising dehydrating under reduced pressure are preferred in cases where the formulation components are solids such as powders and, in cases where they are liquids, the vacuum dehydration method and the dehydration method using a synthetic zeolite, activated alumina, silica gel, quick lime, magnesium oxide or the like are preferred and, further, the dehydration method comprising adding an alkoxysilane compound such as n-propyltrimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, methyl silicate, ethyl silicate, γ-mercpatopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane and γ-glycidoxypropyltrimethoxysilane; an oxazolidine compound such as 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine; and an isocyanate compound to the curable composition and allowing the same to react with water contained in the formulation components is also preferred. In this way, the storage stability of the curable composition is improved by the addition of such an alkoxysilane compound, oxazolidine compound and isocyanate compound.
In using vinyltrimethoxysilane or a like alkoxysilane compound capable of reacting with water for the purpose of drying, the addition level thereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the organic polymer (A).
The method of preparing the curable composition of the present invention is not particularly restricted but there may be employed, for example, such a method known in the art as a method comprising combining the formulation components mentioned above and kneading the resulting mixture at ordinary temperature or with heating using a mixer, roller, kneader, or the like, or a method comprising dissolving the formulation components using small portions of an appropriate solvent and then mixing up the solutions.
When exposed to the air, the curable composition of the present invention forms a three-dimensional network structure under the action of atmospheric moisture and thus is cured to give a solid having rubber elasticity.
The curable composition of the present invention can be suitably used in such fields of application as pressure-sensitive adhesives; sealants for buildings, ships, automobiles, roads, etc.; adhesives; impression materials; vibration-proof materials; damping materials; soundproof materials; expanded/foamed materials; coating compositions; spray coatings, etc. Among such fields of application, the use as sealants or adhesives is more preferred since the cured products obtained are excellent in flexibility and adhesiveness.
The curable composition of the present invention can also be used in such fields of application as back cover sealants for a solar cell and like electric and electronic part materials; insulating cover materials for electric wires and cables and other electric insulating materials; elastic adhesives; contact adhesives; spray sealants; crack repair materials; tiling adhesives; powder coating compositions; casting materials; rubber materials for medical use; pressure-sensitive adhesives for medical use; sealants for medical devices; food packaging materials; joint sealants for siding boards and other exterior materials; coating materials; primers; electromagnetic wave shielding conductive materials, thermally conductive materials; hot melt materials; potting agents for electrics and electronics; films; gaskets; various molding materials; rustproof and waterproof sealants for wired glass and laminated-glass edges (cut end faces); liquid sealants for use in automotive parts, electrical machinery parts, various machinery parts, etc.
Further, the curable composition can also be used as various types of hermetically sealants and adhesives since it, either alone or with the aid of a primer, can adhere to a wide range of substrates such as glass, ceramics, wood, metals and resin moldings.
The curable composition of the present invention can also be used in the form of interior panel adhesives, exterior panel adhesives, tiling adhesives, stone pitching adhesives, ceiling finishing adhesives, floor finishing adhesives, wall finishing adhesives, vehicle panel adhesives, electric, electronic and precision apparatus assembling adhesives, direct glazing sealants, double glazing sealants, sealants for SSG systems, or building working joint sealants.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples and comparative examples illustrate the present invention more specifically. These are, however, by no means limitative of the scope of the present invention.

Synthesis Example 1

Propylene oxide was polymerized using polyoxypropylene diol with a molecular weight of about 2,000 as an initiator and a zinc hexacyanocobaltate glyme complex catalyst to give polypropylene oxide having a number average molecular weight of about 25,500 (polystyrene-equivalent molecular weight measured by using a TOSOH model HLC-8120 GPC solvent delivery system, a TOSOH model TSK-GEL H type column, with THF as a solvent). Thereto was then added a methanol solution of NaOMe in an amount of 1.2 equivalents relative to the hydroxyl groups of that hydroxyl-terminated polypropylene oxide, the methanol was distilled off and, further, allyl chloride was added to the residue for conversion of each terminal hydroxyl group to an allyl group. The unreacted allyl chloride was removed by volatilization under reduced pressure. To 100 parts by weight of the crude allyl-terminated polypropylene oxide obtained were added 300 parts by weight of n-hexane and 300 parts by weight of water and, after mixing with stirring, the water was removed by centrifugation. The hexane solution obtained was further mixed with 300 parts by weight of water with stirring, and after the water was removed again by centrifugation, the hexane was removed by volatilization under reduced pressure. In the above manner, allyl-terminated bifunctional polypropylene oxide with a number average molecular weight of about 25,500 was obtained (this product is hereinafter referred to as a “polymer P”).
The polymer (P) (100 parts by weight) was reacted with 0.80 part by weight of methyldimethoxysilane at 90° C. for 5 hours in the presence of 150 ppm of an isopropanol solution of a platinum-vinylsiloxane complex (platinum content: 3% by weight) as a catalyst to give a methyldimethoxysilyl group-terminated polyoxypropylene type polymer (A).
As a result of ¹H-NMR measurement (made in CDCl₃solvent using a Nippon Denshi (JEOL Ltd.) model JNM-LA400), the average number of terminal methyldimethoxysilyl groups per molecule was found to be about 1.3.

Synthesis Example 2

The polymer (P) (100 parts by weight) obtained in Synthesis Example 1 was reacted with 0.95 part by weight of trimethoxysilane at 90° C. for 5 hours in the presence of 150 ppm of an isopropanol solution of a platinum-vinylsiloxane complex (platinum content: 3% by weight) as a catalyst to give a trimethoxysilyl group-terminated polyoxypropylene type polymer (T). As a result of ¹H-NMR measurement, the number of terminal trimethoxysilyl groups was found to be about 1.3 per molecule on an average.

Example 1

Surface-treated colloidal calcium carbonate (120 parts by weight; product of Shiraishi Kogyo Kaisha Ltd., trade name: Hakuenka CCR), 20 parts by weight of titanium oxide (product of Ishihara Sangyo Kaisha Ltd., trade name: Tipaque R-820), 55 parts by weight of a plasticizer (product of Kyowa Hakko Kogyo Co., Ltd., trade name: DIDP), 2 parts by weight of a thixotropic agent (product of Kusumoto Chemicals Ltd., trade name: Disparlon #6500), 1 part by weight of an ultraviolet absorber (product of Ciba Specialty Chemicals Inc., trade name: Tinuvin 327) and 1 part by weight of a light stabilizer (product of Sankyo Co., Ltd., trade name: Sanol LS770) were weighed and admixed with 100 parts by weight of the methyldimethoxysilyl group-terminated polyoxypropylene type polymer (A) obtained in Synthesis Example 1 and, after thorough kneading, the mixture was passed through a three-roll paint mill for dispersion.
Thereafter, the mixture was dehydrated at 120° C. for 2 hours under reduced pressure and, after cooling to a temperature not higher than 50° C., 5 parts by weight of γ-(2-aminoethyl)aminopropyltrimethoxysilane (product of Dow Corning Toray Co., Ltd., trade name: A-1120) as the (D) component adhesiveness-imparting agent, 3 parts by weight of γ-glycidoxypropyltrimethoxysilane (product of Dow Corning Toray Co., Ltd., trade name: A-187), 10 parts by weight of 1-(o-tolyl)biguanide (product of Tokyo Chemical Industry Co., Ltd., abbreviated as OTBG) as the (B-1) component silanol condensation catalyst and 9 parts by weight of neodecanoic acid (product of Japan Epoxy Resins Co., Ltd., trade name: Versatic 10) as the (C) component carboxylic acid were added and kneaded. After kneading under substantially water-free conditions, the resulting mixture was hermetically packed in a moisture-proof container. A one-pack type curable composition was thus obtained.
Since the (B-1) component OTBG has a molecular weight of 191.2 and the (D) component Versatic 10 has a molecular weight of 172.3, the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), was 5.

Example 2

A curable composition was obtained in the same manner as in Example 1 except that Versatic 10 was used in an amount of 4.5 parts by weight. The ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), was 10.

Example 3

A curable composition was obtained in the same manner as in Example 1 except that Versatic 10 was used in an amount of 2.3 parts by weight. The ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), was 20.

Comparative Example 1

A curable composition was obtained in the same manner as in Example 1 except that Versatic 10 used in Example 1 was not used.

Comparative Example 2

A curable composition was obtained in the same manner as in Comparative Example 1 except that the organic polymer (T) was used in lieu of the organic polymer (A) used in Comparative Example 1 and OTBG was used in an amount of 4 parts by weight.

(Surface Curability)

Under constant temperature (23° C.) and constant humidity (50%) conditions, each of the above curable compositions was spread to a thickness of about 3 mm, and the surface of the curable composition was touched gently with a microspatula from time to time and the time required for the composition to become no more sticking to the microspatula was determined. The results thus obtained are shown in Table 1.

(Depth Curability)

Under constant temperature (23° C.) and constant humidity (50%) conditions, a polyethylene tube with an inside diameter of 18 mm and a length of 50 mm was filled with each of the above curable compositions and, after 7 days of curing, the cured portion was taken out and the length of the cured portion was measured. The results thus obtained are shown in Table 1.

(Adhesiveness)

Each of the above curable compositions, in the form of a rectangle having an approximate size of 3.0 cm in length, 1.5 cm in width and 1.0 cm in thickness, was brought into close contact with an adherend substrate (electrolytically colored aluminum, stainless steel and vinyl chloride resin) and cured under constant temperature (23° C.) and constant humidity (50%) conditions for 7 days; then, the adhesiveness was evaluated by 90-degree hand peel test. The adhesiveness evaluation was made in terms of fracture mode. In the case of 80 to 100% cohesive failure, the adhesiveness was evaluated as A; in the case of 40% to below 80% cohesive failure, as B; and in the case of 0% to below 40% cohesive failure, as C. The results thus obtained are shown in Table 1.

	TABLE 1

	Examples	Comparative Examples

	1	2	3	1	2

Composi-	Organic polymer (A)	100	100	100	100
tion	Organic polymer (T)					100

(parts	Filler	Hakuenka CCR	Shiraishi Kogyo	120	120	120	120	120
by wt.)	Titanium oxide	Tipaque R-820	Ishihara Sangyo	20	20	20	20	20
	Plasticizer	DIDP	Kyowa Hakko	55	55	55	55	55
	Thixotropic	Disparlon #6500	Kusumoto	2	2	2	2	2
	agent		Chemicals
	Ultraviolet	Tinuvin 327	Ciba Specialty	1	1	1	1	1
	absorber		Chemicals
	Light stabilizer	Sanol LS770	Sankyo	1	1	1	1	1
	Adhesiveness-	A-1120	Dow Corning Toray	5	5	5	5	5
	imparting agent	A-187	Dow Corning Toray	3	3	3	3	3
	Amidine compound	OTBG	Tokyo Chemical	10	10	10	10	4
	(B)		Industry
	Carboxylic acid	Versatic 10	Japan Epoxy	9	4.5	2.3
	(C)		Resins

(b)/(c)

5

10

20

—

Results	Surface curability (time required for layer formation)	5.5	hours	5.5	hours	8	hours	15	hours	48	minutes
	Depth curability	2.5	mm	2.3	mm	2.1	mm	1.9	mm

	Tensile	100% tensile modulus	0.48	MPa	0.45	MPa	0.47	MPa	0.43	MPa	0.74	MPa
	characteristics	Breaking strength	1.45	MPa	1.50	MPa	1.62	MPa	1.46	MPa	1.35	MPa

Breaking elongation

490%

570%

630%

640%

240%

Adhesiveness (90-degree hand peel)	Electrolytically	B	A	A	B
	colored alminum
	Stainless steel	A	A	A	B
	Vinyl chloride	A	A	A	C
	resin

When, as shown in Examples 1 to 3, OTBG was used as the (B-1) component, Versatic 10 was further added as the (C) component and, further, the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), was higher than 2, the surface curability, depth curability and adhesiveness were good. On the other hand, in Comparative Example 1 in which the addition of the (C) component was omitted, the surface curability, depth curability and adhesiveness were all inferior. In Comparative Example 2 in which the addition of the (C) component was omitted and the trimethoxysilyl group-terminated polyoxypropylene polymer (T) was used, the modulus was high and the elongation was inferior.

Examples 4 to 6 and Comparative Examples 3 and 4

To 100 parts by weight of the methyldimethoxysilyl group-terminated polyoxypropylene type polymer (A) obtained in Synthesis Example 1 were added 120 parts by weight of surface-treated colloidal calcium carbonate (Hakuenka CCR), 20 parts by weight of titanium oxide (Tipaque R-820), 55 parts by weight of a plasticizer (DIDP), 2 parts by weight of a thixotropic agent (Disparlon #6500), 1 part by weight of an ultraviolet absorber (Tinuvin 327) and 1 part by weight of a light stabilizer (Sanol LS770). After thorough kneading, the mixture was passed through a three-roll paint mill for dispersion and dehydrated at 120° C. for 2 hours under reduced pressure; thus, a main composition was prepared. Under constant temperature (23° C.) and constant humidity (50%) conditions, 2 parts by weight of a dehydrating agent (A-171), 3 parts by weight of γ-(2-aminoethyl)aminopropyltrimethoxysilane (product of Dow Corning Toray Co., Ltd., trade name: A-1120) as the (D) component adhesiveness-imparting agent, 1-(o-tolyl) biguanide (OTBG) as the (B-1) component silanol condensation catalyst and neodecanoic acid (Versatic 10) as the (C) component carboxylic acid were added to the main composition according to each formulation given in Table 2. Each compound, in the form of a rectangle having an approximate size of 3.0 cm in length, 1.5 cm in width and 1.0 cm in thickness, was brought into close contact with an adherend substrate (electrolytically colored aluminum, stainless steel and vinyl chloride resin) and cured under constant temperature (23° C.) and constant humidity (50%) conditions for 7 days; then, the adhesiveness was evaluated by 90-degree hand peel test. The results thus obtained are shown in Table 2. The adhesiveness evaluation was made in terms of fracture mode. In the case of 80 to 100% cohesive failure, the adhesiveness was evaluated as A; in the case of 40% to below 80% cohesive failure, as B; and in the case of 0% to below 40% cohesive failure, as C.
The value of the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), is shown for each compound in Table 2.

	TABLE 2

	Examples	Comparative Examples

	4	5	6	3	4

Composition

Main

Organic polymer (A)

100

(parts by wt.)	composition	Filler	Hakuenka CCR	Shiraishi Kogyo	120	120	120	120	120
		Titanium Oxide	Tipaque R-820	Ishihara Sangyo	20	20	20	20	20
		Plasticizer	DIDP	Kyowa Hakko	55	55	55	55	55
		Thixotropic agent	Disparlon #6500	Kusumoto	2	2	2	2	2
				Chemicals
		Ultraviolet absorber	Tinuvin 327	Ciba Specialty	1	1	1	1	1
				Chemicals
		Light stabilizer	Sanol LS770	Sankyo	1	1	1	1	1

Dehydrating agent	A-171	Dow Corning	2	2	2	2	2
		Toray
Adhesiveness-imparting agent	A-1120	Dow Corning	3	3	3	3	3
		Toray
Amidine compound (B)	OTBG	Tokyo Chemical	8.3	8.3	8.3	8.3	2.1
		Industry
Carboxylic acid (C)	Versatic 10	Japan Epoxy	7.5	3.7	1.9	22.5	7.5
		Resins

(b)/(c)

5

10

20

1.7

1.3

Results	Adhesiveness (90-degree hand peel)	Electrolytically	A	A	B	C	C
		colored alminum
		Stainless steel	A	A	A	C	C
		Vinyl chloride	A	A	A	C	C
		resin

When, as shown in Examples 4 to 6, OTBG was used as the (B-1) component, further Versatic 10 was added as the (C) component and the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component and the number of moles (c) of all carboxyl groups in the (C) component, namely the ratio (b)/(c), was higher than 2, the adhesiveness was good.
On the other hand, when the ratio (b)/(c) was not higher than 2, the adhesiveness was inferior, as shown in Comparative Example 3 or 4.

Claims

1. A non-organotin curable composition

which comprises:

(A) an organic polymer containing a silyl group capable of crosslinking under siloxane bond formation, said silyl group being a group represented by the general formula (1):

—SiR¹X₂ (1)

(wherein R¹represents a group selected from among alkyl groups containing 1 to 20 carbon atoms, aryl groups containing 6 to 20 carbon atoms, aralkyl groups containing 7 to 20 carbon atoms and triorganosiloxy groups represented by (R′)₃SiO— in which R′ is a hydrocarbon group containing 1 to 20 carbon atoms, the three R′ groups may be the same or different, and X represents a hydroxyl group or a hydrolyzable group and the two X groups may be the same or different);

(B) an amidine compound (B-1) as a silanol condensation catalyst; and

(C) a carboxylic acid,

wherein the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component of the composition and the number of moles (c) of all carboxyl groups in the (C) component of the composition, namely the ratio (b)/(c), is higher than 2.

2. The curable composition according to claim 1,

wherein a main chain skeleton of the (A) component organic polymer contains at least one atom selected from among a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom.

3. The curable composition according to claim 1,

wherein the (A) component organic polymer comprises at least one species selected from the group consisting of polyoxyalkylene polymers, saturated hydrocarbon polymers and (meth)acrylate ester polymers.

4. The curable composition according to claim 3,

wherein the polyoxyalkylene polymer is a polyoxypropylene polymer.

5. The curable composition according to claim 1,

which contains the (B-1) component in an amount of 0.001 to 20 parts by weight per 100 parts by weight of the component (A).

6. A sealant

which comprises the curable composition according to claim 1.

7. An adhesive

which comprises the curable composition according to claim 1.