JP3432286B2 - Method for producing coating composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a coating composition. More specifically, the surface of metal such as iron, plastic, wood, concrete, etc. has scratch resistance, transparency,
The present invention relates to a method for producing a coating composition capable of forming a coating film having excellent boiling water resistance, heat resistance, weather resistance, and adhesion.

[0002]

2. Description of the Related Art Conventionally, various coating compositions containing a silicon compound have been investigated for the purpose of improving scratch resistance. For example, as a method using an alkoxysilane hydrolyzate, Japanese Patent Laid-Open Nos. 53-2565 and 56-56 are available.
22365, JP-A-61-166824 and the like. Further, as a coating composition containing organoalkoxysilane and colloidal silica or colloidal alumina as main components, JP-B-52-39691 and JP-B-5
3-5042, JP-A-54-87736, JP-A-55-
94971, JP-A-56-99236, JP-A-59-6.
It is proposed in Japanese Patent No. 8377. Furthermore, coating compositions using an acrylic copolymer containing an alkoxysilyl group are disclosed in JP-A-3-47871 and JP-A-3-3787.
It is proposed in Japanese Patent Laid-Open No. 54278. Furthermore, in order to exert the respective characteristics of both, it has been noted that a composition obtained by mixing the above-mentioned hydrolyzate of alkoxysilane and an acrylic copolymer is used for coating.

[0003]

However, the coating composition comprising the above mixture has room for improvement in the transparency and boiling water resistance of the resulting coating film. An object of the present invention is to form a coating film having good transparency and boiling water resistance on the surface of metals such as iron, plastics, wood, concrete, etc., and further scratch resistance which the composition originally has. sex,
It is intended to provide a coating composition having heat resistance, weather resistance and adhesion.

[0004]

[Means for Solving the Problems] As a result of extensive studies to solve the above problems, the physical properties of the coating film can be improved by allowing a specific silicate oligomer to coexist during the polymerization of an alkoxysilyl group-containing ethylenically unsaturated monomer. They have found that they can be improved and have reached the present invention. That is, the present invention, in the presence of a silicate oligomer represented by the following general formula [I] in an organic solvent, an alkoxysilyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing (meth) acrylic acid ester and optionally Accordingly, there is provided a method for producing a coating composition of a uniform solution type, which further comprises copolymerizing an alkyl (meth) acrylate.

[Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group)

The present invention will be described in detail below. The silicate oligomer used in the present invention is not particularly limited as long as it is represented by the following general formula [I].

[Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group)

The silicate oligomer can be obtained, for example, by hydrolyzing tetraalkoxysilane or tetraphenoxysilane such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane. n can be adjusted by controlling the hydrolysis rate in this case

The hydrolysis reaction itself can be carried out by a known method. For example, a predetermined amount of water is added to the above tetraalkoxysilane in the presence of an acid catalyst to distill off the alcohol by-produced, usually at room temperature. The reaction is performed at about -100 ° C. The alkoxysilane is hydrolyzed by this reaction, and a liquid silicate oligomer having two or more hydroxyl groups by a condensation reaction (usually an average degree of polymerization of about 2 to 8,
Preferably 3-6) is obtained as a hydrolyzate. The degree of hydrolysis can be appropriately adjusted depending on the amount of water used, but in view of the physical properties of the coating composition or the curing of the coating film, it is usually 40 to 90 in the present invention.
%, Preferably about 60 to 80%. When it is more than the above range, the adhesiveness is lowered, and when it is less than the above range, n is 0.

The tetraalkoxysilicate oligomer thus obtained usually contains about 2 to 10% of a monomer. If this monomer is contained, the storage stability of the coating composition is lacking, the viscosity increases during storage, and it becomes difficult to form a thin film. Therefore, the monomer content should be 1% or less, preferably 0.3% or less. This monomer removal is carried out by flash distillation and vacuum distillation so that

The amount of the silicate oligomer used is 5 to 500 parts by weight, preferably 10 to 400 parts by weight, particularly preferably 10 to 30 parts by weight, based on 100 parts by weight of the monomer to be polymerized.
0 parts by weight. If it is less than this, the hardness of the coating film is remarkably lowered, and if it is more than this, the adhesion to the substrate is remarkably lowered.
Incidentally, if the amount of acrylic monomer is large within the above range, alkali resistance and storage stability are improved, and if the content of silicate oligomer is large, hardness, solvent resistance, weather resistance, and adhesion tend to improve. is there.

The alkoxysilyl group-containing ethylenically unsaturated monomer used in the present invention means γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth). Acryloxydimethyldimethoxysilane, γ- (meth) acryloxytrimethoxysisilane, γ- (meth) acryloxytriethoxysisilane, vinyltriethoxysilane, vinyltripropoxysilane, vinylmethyldiethoxysilane, vinyltri (ethoxymethoxy) ) Silane, allyltrimethoxysilane, P-vinylphenyltrimethoxysilane and the like. Among them, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltriethoxysilane and the like are preferably used.

As the hydroxyl group-containing (meth) acrylic acid ester, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Examples include 3-hydroxypropylpropyl (meth) acrylate and 4-hydroxylbutyl (meth) acrylate.

In the coexisting polymerization, copolymerization of only an alkoxysilyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing (meth) acrylic acid ester may be used.
Copolymerization with (meth) acrylic acid alkyl ester is also possible. The number of carbon atoms of the alkyl group of the (meth) acrylic acid alkyl ester is not particularly limited and any one of about 1 to 20 can be used, but the number of carbon atoms of the alkyl group is 1 to 3 and the number of carbon atoms of the alkyl group. It is preferable to use it in combination with a material having a ratio of 4 or more from the viewpoint of the balance of physical properties of the coating film. (A) Alkyl group-containing (meth) acrylic acid alkyl esters having 1 to 3 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate and the like. Are used alone or in combination of two or more.

Examples of (b) alkyl (meth) acrylates having an alkyl group having 4 or more carbon atoms include butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate and (meth) acrylate. ) Acrylic acid t
-Butyl, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, (meth)
Examples thereof include octyl acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate, which may be used alone or in combination of two or more. As a monomer other than the above, an aromatic monomer such as styrene and vinyltoluene, a vinyl compound such as vinyl acetate and vinyl propionate, and the like are used in combination as necessary.

In the case of copolymerizing only an alkoxysilyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing (meth) acrylic acid ester, the ratio of the monomer to 100 parts by weight of the monomer is the alkoxysilyl group-containing ethylene. 1 to 30% by weight, preferably 5 to 25% by weight of a polyunsaturated monomer,
Hydroxyl group-containing (meth) acrylic acid ester is 70
Advantageously, ˜99% by weight, preferably 75 to 95% by weight.

Further, when the (meth) acrylic acid alkyl ester is used in combination, the proportion of the alkoxysilyl group-containing ethylenically unsaturated monomer in 100 parts by weight of the total amount of the monomers is 1 to 30% by weight, preferably 5 to 25% by weight, hydroxyl group-containing (meth) acrylic acid ester 0.5 to 50
Advantageously, wt%, preferably 1 to 30 wt%, alkyl (meth) acrylate ester is 0.5 to 98 wt%, preferably 1 to 75 wt%. Also (meta)
In the acrylic acid alkyl ester, the ratio of the (meth) acrylic acid alkyl ester (a) having an alkyl group having 1 to 3 carbon atoms and the (meth) acrylic acid alkyl ester (b) having an alkyl group having 4 or more carbon atoms is (a). ) / (B) is 2/8 to 8/2 by weight, preferably 3/7 to 7/3
Is desirable.

By using such a monomer, the crosslinkability with the silicate oligomer is improved. Also, when the coating film is cured, it contracts, internal stress may occur, and problems such as cracks may occur, but to avoid this,
It is preferable to set the glass transition point low depending on the composition ratio of the polymer. A specific temperature range of a suitable glass transition point (Tg) is −20 to 60 ° C.

A feature of the present invention is that an alkoxysilyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing (meth) acrylic acid ester are co-polymerized in the presence of the silicate oligomer in an organic solvent. The method of such coexisting polymerization is not particularly limited, but for example, it can be produced by mixing each component and by a usual radical polymerization method.
The organic solvent used in the present invention, to use as it dissolves starting material monomers and polymers and silicate oligomer
It is necessary to appropriately select the material depending on the substrate to be coated or the coating method. Specific examples of usable organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol, and octanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene. Glycol derivatives such as glycol mono-n-butyl ether, hydrocarbons such as benzene, kerosene, toluene, xylene, methyl acetate, ethyl acetate,
Butyl acetate, methyl acetoacetate, ethyl acetoacetate and other esters, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone and other ketones, and ethyl ether, butyl ether, methyl cellosolve, ethyl cellosolve, dioxane, furan, tetrahydrofuran and other ethers. Can be mentioned. These organic solvents can be used either individually or in combination.

The amount of the solvent used is 20 to 2 with respect to 100 parts by weight of the total amount of the monomer and the silicate oligomer.
It is possible in the range of 00 parts by weight. This composition ratio can be appropriately selected according to the purpose of use. If the amount is less than the above range, there may occur problems during coating, such as difficulty in obtaining a uniform coating film.

As the polymerization catalyst, known radical polymerization catalysts such as azobisisobutyronitrile, benzoyl peroxide, ditertiary butyl peroxide,
Cumene hydroperoxide and the like are used. A suitable temperature for the polymerization is 60 to 150 ° C., and a practical polymerization time is about 6 to 20 hours. The composition of the present invention is
As described above, the organic solvent used at the time of polymerization can be put to practical use as a coating material in the state of being used as it is, but if necessary, it may be used by substituting it with an arbitrary solvent.

The homogeneous solution system of the present invention thus obtained
It is desirable to use a curing catalyst in the coating composition. The curing catalyst can be added and used at the time of use (two-component type), and it is added from the beginning (1
Liquid type) can be stored. Specific examples of the curing catalyst include hydrochloric acid, nitric acid, phosphoric acid, inorganic acids such as boric acid, acetic acid, formic acid, maleic acid, phthalic acid, benzoic acid, organic acids such as paratoluenesulfonic acid, dibutyltin laurylate, dibutyltin octoate, Organotin compounds such as dibutyltin acetate and dioctyltin laurate, organotitanium compounds such as tetrabutyl titanate, tetrapropyl titanate and tetrabutoxy titanate, phosphoric acid esters such as monomethyl phosphate and monoethyl phosphate, γ-aminopropyltrinate Methoxysilane, N
There are silane coupling agents such as -β-aminoethyl-γ-aminopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane.

In addition, organoaluminum compounds such as tris (acetylacetonato) aluminum and tris (ethylacetoacetate) aluminum, tetrabutylzirconate, organozirconium such as butoxytris (acetylacetonato) zirconium, ethylenediamine, diethylenetriamine, piperazine , Amines such as metaphenylenediamine, diethanolamine and triethanolamine, alkali compounds such as sodium hydroxide and potassium hydroxide, and epoxy compounds.
Inorganic acids, organic tin compounds, organic acids and organic aluminum compounds are particularly preferable. The amount of these catalysts used varies depending on the catalyst, but when hydrochloric acid is used, it is preferably about 0.1 to 2 parts by weight with respect to 100 parts by weight of the silicate oligomer.

The method of using the composition of the present invention will be described more specifically. The polymer composition obtained by the above co-polymerization is usually adjusted in concentration, then a curing catalyst is added, and then the composition is applied to a substrate and dried by heating. When R of the silicate oligomer is an alkyl group or a phenyl group, it may be hydrolyzed if necessary. As the base material in this case, iron, stainless steel, aluminum, other metals, alloys,
Applicable to plastic, wood, cement, concrete, etc. Examples of the coating method include brush coating, spin coating, spray coating, depping, roll coating, and gravure printing. The film thickness at this time is preferably 0.1 to 200 μm, more preferably 1 to 100 μm. The composition of the present invention is particularly effective for thickening the coating film, and the conventional one had a high possibility of causing cracks and the like at a thickness exceeding 50 μm, but the present invention made it possible to further thicken the film. When it is thinner than the above range, it is difficult to obtain sufficient scratch resistance, and when it is thicker than the above range, cracks may occur, which is not preferable.

Further, when preparing a coating composition using the composition of the present invention, it is necessary to add a dehydrating agent or an alkyl alcohol having an alkyl group having 1 to 10 carbon atoms in consideration of the stability of the coating composition. There is. As the dehydrating agent in this case,
Trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, trimethyl orthoacetate, triethyl orthoacetate, tripropyl orthoacetate, trimethyl orthopropionate, trimethyl orthopropionate, trimethyl orthoisopropionate, triethyl orthoisopropionate, orthobutyric acid Trimethyl, triethyl orthobutyrate, trimethyl orthoisobutyrate, orthocarboxylic acid esters such as triethyl orthoisobutyrate are used, and the addition amount is 0 to 30 parts by weight, preferably 100 parts by weight of the co-polymerized alkoxysilyl group-containing polymer. 0.
5 to 30 parts by weight, particularly preferably 5 to 25 parts by weight.

Further, as the pigment used in the paint, white pigments such as titanium oxide, calcium carbonate, talc, lithobon, barium sulfate, calcium sulfate, alumina and clay, black pigments such as carbon black and iron black, phthalocyanine blue, Blue pigments such as navy blue and ultramarine blue, yellow pigments such as lake yellow, yellow lead, oak yellow and Hansa yellow, red pigments such as red iron oxide and lake red, orange pigments such as chrome vermillion, green pigments such as phthalocyanine green and chromium oxide. And so on.

Further, other additives for resins can be added to the composition of the present invention within a range that does not impair the curing of the invention. For example, ultraviolet stabilizer, antioxidant, antistatic agent, conductivity imparting agent, scratch resistance imparting agent, compatibilizer, adhesiveness imparting agent, colorant, fluidity improving agent, plasticizer, anti-sagging agent, precipitation Examples include an inhibitor and an antifoaming agent. A sand mill, a disper, a ball mill and the like which are usually used are used for preparing the paint. This paint can be used as a top coat paint for exterior materials such as concrete, mortar buildings, roof tiles, and siding boards, and also as a paint for interiors and floors of buildings, and in particular, it has excellent weather resistance in exterior applications. It can be used as paint.

[0026]

In the present invention, a coating composition which gives a coating film excellent in scratch resistance, transparency, boiling water resistance and storage stability can be obtained.

[0027]

The present invention will be described in more detail based on the following examples and comparative examples, but the invention is not limited to the following examples as long as the gist thereof is not exceeded. The coating film was evaluated by the following methods. (1) Cellotape peeling: In order to evaluate the adhesive strength of the coating film, 11 parallel and 11 horizontal and vertical lines perpendicular to the center of the coating film were drawn at 1 mm intervals until reaching the substrate surface, and 1 in 1 cm ²
I added a grid to make 00 squares. A cellophane adhesive tape (trade name: “Cellotape” made by Nichiban) was strongly adhered to the cross of the grid, and the number of squares without peeling was measured when the tape was rapidly peeled in the direction of 90 degrees.

(2) Pencil hardness: The degree of scratches is determined by JIS K
It was evaluated by a pencil hardness test according to 5400. (3) Boiling water resistance of coating film: The coating film was immersed in hot water of 100 ° C. for 4 hours together with the base material, and the state of gloss and cracking of the coating film was visually observed. The case where the coating film was not glossy or cracked was rated as ◯, and the one where slight glossiness was recognized was rated as Δ. (4) Transparency (haze): Measured according to JIS K-7105.

[Preparation of Silicate Oligomer] Silicate Oligomer A 500 equipped with stirrer, reflux condenser and thermometer
Tetramethoxysilane 2 was added to a 3 ml round bottom flask.
After adding 34 g and 74 g of methanol and mixing, 0.0
22.2 g of 5% hydrochloric acid was added, and a hydrolysis reaction was carried out at an internal temperature of 65 ° C. for 2 hours. Next, the condenser was replaced with an extraction tube, the internal temperature was raised to 150 ° C., the mixture was extracted with methanol and further heated at 150 ° C. for 3 hours to condense to obtain a hydrolyzate. The degree of polymerization was 3 to 6 and the hydroxyl group was 10 or more. The amount of monomers in the tetramethoxysilane oligomer was 5%.

Silicate oligomer B Subsequent to the above, the jacket heated to 100 to 150 ° C. is boiled with tetramethoxysilane oligomer, and the vaporized monomer is discharged out of the system together with the inert gas. The amount of monomers in the tetramethoxysilane oligomer thus obtained was 0.2%. Silicate Oligomer C Tetraethoxysilane is used instead of the above tetramethoxysilane, and the amount of monomers in the oligomer is 0.3% or less. Tetraethoxysilane oligomer (degree of polymerization 3 to 6)
Got

Examples 1 to 3 A flask equipped with a nitrogen inlet tube, a reflux condenser, a thermometer and a stirrer was placed in a flask having 100 parts by weight of γ-methacryloxypropyltrimethoxysilane, 50 parts by weight of 2-hydroxyethyl methacrylate, and methacryl. 500 parts by weight of methyl acidate, 350 parts by weight of n-butyl acrylate, and 500 parts by weight of silicate oligomers A to C (in terms of pure content)
And xylene 420 parts by weight, isopropyl alcohol 8
0 parts by weight and 2 parts by weight of benzoyl peroxide were charged and heated to 90 ° C. to start polymerization. 2 hours after the initiation of polymerization, 30 parts by weight of xylene was added to 8 parts of benzoyl peroxide.
Polymerization was continued for 10 hours while adding a solution in which parts by weight were dissolved. Resin content 72% by weight, viscosity 1900 cps (25
A co-polymerized product of (° C.) Was obtained. Tg was 20 ° C. 600 parts by weight of xylene was added to the above co-polymerized product to obtain a resin content of 54
It was set to% by weight. 0.95 g of 1N hydrochloric acid was added to this solution, and 6
Stir for 30 minutes at 5 ° C. Add this solution to a glass plate (70 mm x
(150 mm × 0.5 mm) was coated with an applicator and then heat-treated at 110 ° C. for 30 minutes. This coating (1
The physical properties of 00 μ) were evaluated by the above methods, and the results are shown in Table 1.

Examples 4 to 5 In the monomer composition of Example 2, 200 parts by weight of γ-methacryloxypropyltrimethoxysilane, 100 parts by weight of 2-hydroxyethyl methacrylate, 350 parts by weight of methyl methacrylate, 200 parts by weight of n-butyl acrylate and 150 parts by weight of styrene (Example 4)
50 parts by weight of γ-methacryloxypropyltriethoxysilane and 1 part of 2-hydroxyethyl methacrylate were used.
The amount was changed to 00 parts by weight, 350 parts by weight of methyl methacrylate, 400 parts by weight of n-butyl acrylate, and 100 parts by weight of styrene (Example 5). Tg was 40 ° C. in Example 4 and 8 ° C. in Example 5. The results are shown in Table 1. Examples 6 to 7 In Example 2, the amount of silicate oligomer used was 1
000 parts by weight (Example 6) and 1500 parts by weight (Example 7). The results are shown in Table 1. Example 8 The same operation as in Example 2 was performed except that dibutyltin dilaurate was used instead of hydrochloric acid. The results are shown in Table 1.

Example 9 The same operation as in Example 2 was carried out except that tris (acetylacetate) aluminum was used instead of hydrochloric acid. The results are shown in Table 1. Control Example 1 In Example 2, the use of the silicate oligomer was omitted during the copolymerization, and the silicate oligomer was mixed after the polymerization. The results are also shown in Table 1. The haze was measured immediately after the mixture was manufactured.

[0034]

[Table 1] Oligomer Cellotape Peeling Pencil Hardness Water Resistance Water Resistance Transparency (Haze) Example 1 A 100/100 HB ○ 0.2 〃 2 B 100/100 HB ○ 0.2 〃 3 C 100/100 HB ○ 0. 2 〃 4 B 100/100 H ○ 0.2 〃 5 B 100/100 F ○ 0.2 〃 6 B 100/100 2H ○ 0.2 〃 7 B 100/100 3H ○ 0.2 〃 8 B 100 / 100 F ○ 0.2 〃 9 B 100/100 F ○ 0.2 Control Example 1 B 100/100 F △ 21.6

[0035]

EFFECTS OF THE INVENTION The uniform solution coating composition of the present invention can form a coating film having high adhesion to each substrate, sufficient hardness, good boiling water resistance and excellent transparency. . Further, it is a coating composition which has excellent storage stability and coating performance and is extremely easy to handle.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08F 283/12 C09D 151/08

Claims (5)

(57) [Claims] 1. A copolymerization of an alkoxysilyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing (meth) acrylic ester in the presence of a silicate oligomer represented by the following general formula [I] in an organic solvent. A method for producing a uniform solution coating composition, comprising: [Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group) 2. The ratio of the alkoxysilyl group-containing ethylenically unsaturated monomer in the total amount of 100 parts by weight of the alkoxysilyl group-containing ethylenically unsaturated monomer and the hydroxyl group-containing (meth) acrylic acid ester is 1 to 1. 30% by weight, and the proportion of hydroxyl group-containing (meth) acrylic acid ester is 70 to 99% by weight.
1. The manufacturing method according to 1 . 3. A total amount 1 of an alkoxysilyl group-containing ethylenically unsaturated monomer, a hydroxyl group-containing (meth) acrylic acid ester and a (meth) acrylic acid alkyl ester.
The proportion of the alkoxysilyl group-containing ethylenically unsaturated monomer in 1 part by weight is 1 to 30% by weight, and the proportion of the hydroxyl group-containing (meth) acrylic acid ester is 0.5 to 50%.
The manufacturing method according to claim 1, wherein the weight% and the ratio of the (meth) acrylic acid alkyl ester are 0.5 to 98% by weight. 4. The method according to any one of claims 1 to 3, characterized by the use of tetramethoxysilane partial hydrolyzate as silicate oligomer. 5. A tetramethoxysilane partial hydrolyzate as silicate oligomer, the preceding claims, monomer amount, characterized by using the following items 1 wt%
Any one of the manufacturing methods.