JPH10279888A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition improved in the curing performances of an air contact part without detriment to the merits of an anaerobic adhesive by mixing a (meth)acrylic ester with an organic peroxide, a cure accelerator and a moisture-curing urethane prepolymer compound. SOLUTION: The (meth)acrylic ester used is desirably a hydroxyl-free (meth) acrylic ester in view of its storage stability and may be a combination of at least two such esters. The content is 100 pts.wt. The organic peroxide used is a hydroperoxide such as tert. butyl hydroperoxide and is used in an amount of 0.05-10 pts.wt. The cure accelerator used is a tert. amine, a heterocyclic amine or a combination thereof and is used in conjunction with a cure accelerator aid being o-benzoic sulfimide. The amount of use is 0.05-10 pts.wt. The moisture-curing urethane prepolymer compound has a terminal isocyanate group and forms a polymer when crosslinked in the presence of moisture. The structural ratio is 25-400 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anaerobic adhesive composition having improved curability at an air contact portion.

[0002]

2. Description of the Related Art As adhesives using (meth) acrylic monomers, anaerobic adhesives, two-pack type (meth) acrylic adhesives represented by SGA (second generation acrylic adhesives), UV curable adhesives are well known. Of these, anaerobic adhesives are based on the fact that (meth) acrylic monomers are subject to polymerization inhibition by oxygen in the air. These products are manufactured from polyethylene or other resins with high air permeability. About half the amount is filled in the filled container to ensure stability during storage. When this kind of adhesive is filled in, for example, minute gaps of metal and shut off oxygen, the (meth) acrylic monomer is polymerized and hardened. Utilizing this property, anaerobic adhesives are used to prevent bolts and nuts from loosening and to fix bearings and shafts. However, the portion of the adhesive that protrudes from the adherend and is in contact with air (hereinafter, may be abbreviated as “air contact portion”) is subject to polymerization inhibition by oxygen in the air, and therefore remains liquid. And does not cure. Therefore, a troublesome operation such as wiping off the adhesive that has run out or washing the adhesive has been required. Further, when the wiping operation cannot be performed, there has been a problem that the uncured adhesive adheres to others, impairs the aesthetic appearance of the product, and causes odor.

On the other hand, some SGAs represented by a two-component (meth) acrylic adhesive are designed so that curing proceeds to an “air contact portion”. They are,
Curing is started from the inside of the adhesive by the action of the redox catalyst, and with this curing, paraffin wax contained in the adhesive covers the surface of the adhesive and blocks air,
Curing proceeds to the "air contact portion". By applying this technology to anaerobic adhesives, it is conceivable to add paraffin wax to the anaerobic adhesives to improve the cure of the "air contact area". However, sufficient effects can be obtained for the following reasons. I can't. In other words, in order for the paraffin wax to migrate to the surface and block air in the “air contact portion” of the adhesive containing paraffin wax, the internal curing of the adhesive in the air contact portion is essential. However, in the case of an anaerobic adhesive, the inside of the adhesive at the "air contact portion" is not cured due to polymerization inhibition by oxygen in the air, so that sufficient separation and transfer of paraffin wax does not occur. Wax cannot sufficiently cover the surface of the adhesive, and the curing of the “air contact portion” does not proceed.

On the other hand, Japanese Patent Publication No. 4-658876 discloses a redox reaction type acrylic adhesive in which a reactive (meth) acrylic monomer, methacrylic acid, a reducing agent, an organic peroxide, a polyisocyanate compound and a chlorinated rubber are coexisted. An agent composition is disclosed. However, the purpose of the adhesive composition is to improve the curing speed when at least one of the adherends is made of a wooden material and to improve the bonding speed, and to cure the "air contact portion" of the adhesive composition. There is no disclosure of gender.

The following method is used as a method for secondarily curing the "air contact portion" of the anaerobic adhesive. An anaerobic adhesive is mixed with an ultraviolet curing initiator, and ultraviolet light is irradiated with an ultraviolet irradiation device. The air contact surface is hardened by heating at a high temperature. As disclosed in JP-A-53-16049, a substance having an air barrier property is dissolved in an organic solvent and applied. However, the method (1) requires an expensive ultraviolet irradiation device, and has a problem that a portion hardly irradiated with ultraviolet light, such as a corner, cannot be cured. The method (1) not only has a drawback that a heating furnace or a heat source energy is required, but also has a problem that it is difficult to apply to an adherend that dislikes heating, such as an electronic component. Further, the method uses an adhesive and an air-blocking solution in combination, thereby increasing the number of steps.
In addition, there is a disadvantage that the working environment is deteriorated by the solvent contained in the air-blocking solution. In addition, when the adherend is made of plastic, the adherend is eroded by the solvent.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an adhesive composition having an improved curing performance of an "air contact portion" while maintaining the advantages of an anaerobic adhesive. The purpose is to provide.

[0007]

According to the present invention, there is provided a composite of a moisture-curable urethane prepolymer compound and a (meth) acrylic anaerobic curing composition comprising a (meth) acrylic ester, an organic peroxide and a curing accelerator. Adhesives maintain the superior performance of anaerobic adhesives while maintaining the “air contact area”
Have been found to have good curability. That is, according to the present invention, there is provided an adhesive composition comprising (meth) acrylate, an organic peroxide, a curing accelerator, and a moisture-curable urethane prepolymer compound. Further, 100 parts by weight of (meth) acrylate, 0.05 to 10 parts by weight of an organic peroxide, 0.05 to 10 parts by weight of a curing accelerator, and 25 to 400 parts by weight of a moisture-curable urethane prepolymer compound. An adhesive composition is provided. Further, there is provided an adhesive composition characterized in that the (meth) acrylate used in the adhesive composition is selected from those having no hydroxyl group.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The (meth) acrylate used in the present invention is not particularly limited, and alkyl (meth) acrylate, phenoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Hydroxyalkyl (meth) acrylate, poly (meth) acrylate of polyhydric alcohol, epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) obtained by adding (meth) acrylic acid to epoxy resin Acrylates, di (meth) acrylates of alkylene oxide adducts of bisphenol A or bisphenol S, and the like.
It is used in combination of more than one species. Among these, (meth) acrylates having no hydroxyl group are more preferable from the viewpoint of storage stability.

As the organic peroxide, ketone peroxides, dialkyl peroxides, diacyl peroxides, peroxyesters and the like can be used.
Hydroperoxides such as tertiary butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide and paramenthane hydroperoxide are most effective. The compounding amount of the organic peroxide is 0.0 with respect to 100 parts by weight of the (meth) acrylate ester compounded in the adhesive composition of the present invention.
The amount is preferably set to 5 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, from the viewpoints of curability and storage stability of the adhesive composition.

As the curing accelerator, N, N-dimethyl orthotoluidine, N, N-dimethyl metatoluidine, N, N
Tertiary amines such as N-dimethylparatoluidine, N, N-dimethylaniline, N, N-dimethylnaphthylamine and heterocyclic amines such as quinoline, quinaldine, quinoxaline, tetrahydroquinoline, and tetrahydroquinaldine, alone or in combination of two or more Can be used in combination. It is desirable to use o-benzoixulfimide as a curing accelerator together with these curing accelerators. The compounding amount of the curing accelerator is 0.05 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the (meth) acrylic ester mixed in the adhesive composition of the invention.
It is preferable to set the amount to 5 parts by weight from the viewpoint of the curability and storage stability of the adhesive composition.

On the other hand, examples of the moisture-curable polyurethane prepolymer compound used in the present invention include a urethane prepolymer having an isocyanate group at a terminal. The urethane prepolymer having a terminal isocyanate group is a reaction product of a polyhydroxyl compound and a polyisocyanate compound, and is crosslinked and cured to form a polymer while the isocyanate group portion forms a urethane bond due to the presence of moisture.

The polyhydroxyl compounds include polyethylene glycol (PEG); polyoxypropylene glycol (PPG); polyether polyols such as ethylene oxide-propylene oxide copolymer, and polytetramethylene ether glycol (PTMEG); β-methyl-δ-valerolactone (P-β-M
VL); polycaprolactone (PCL); polyester formed from diol / dibasic acid (here, diols include ethylene glycol; diethylene glycol; dipropylene glycol; 1,4-butanediol; 1,6-hexanediol; neopentyl) Glycols; dibasic acids include adipic acid; azelaic acid; sebacic acid; isophthalic acid; terephthalic acid, etc.)
These include polyester polyols alone,
Alternatively, two or more kinds are used in combination.

As the above-mentioned polyisocyanate compound, there can be mentioned those used in the production of ordinary polyurethane resins. Specifically, in addition to MDI and TDI, diphenylmethane-4,4-diisocyanate and modified products thereof, 1,5-naphthalenediisocyanate (ND
I), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), lysine diisocyanate (LDI) and the like. These polyisocyanate compounds may be used alone or in combination of two or more.

The composition ratio of the (meth) acrylic ester and the moisture-curable urethane prepolymer compound is not particularly limited, but the moisture-curable urethane prepolymer compound is added to 100 parts by weight of the (meth) acrylic ester. It is more preferable that the amount is 25 to 400 parts by weight, more preferably 50 to 200 parts by weight, since both the curability and the adhesive strength of the “air contact portion” can be achieved in a well-balanced manner.

The adhesive composition of the present invention contains an organic and / or inorganic filler, a viscosity modifier, a stabilizer, a coloring agent, an antibacterial agent, and the like, as long as the properties of the composition are not impaired. Further, an additive such as a moisture curing accelerator can be blended.

The adhesive composition of the present invention is produced by mixing the above-mentioned (meth) acrylic acid ester, curing accelerator, organic peroxide, moisture-curable urethane prepolymer compound and, if necessary, various additives. . The present adhesive may be in the form of one liquid, or may be in the form of two or more liquids. The grouping when the adhesive composition of the present invention is in the form of two liquids will be described below. Liquid A: (meth) acrylate, curing accelerator Liquid B: organic peroxide, moisture-curable urethane prepolymer compound Liquid A: (meth) acrylic acid ester, curing accelerator, organic peroxide Liquid B: moisture Curable urethane prepolymer compound Liquid A: (meth) acrylate B Liquid: moisture-curable urethane prepolymer compound, curing accelerator, organic peroxide

When the present adhesive is applied to a metal adherend and assembled, for example, the adhesive filled in the metal gap and blocked from air is hardened by anaerobic hardening. On the other hand, in the adhesive that overflows from the metal gap and comes into contact with air, first, the moisture-curable urethane prepolymer is cured by moisture curing, and a cured layer is formed on the surface of the adhesive that overflows from the metal gap. Then, as a result of the formation of the hardened layer, the inside of the adhesive overflowing from the metal gap is blocked from oxygen and hardened.

[0018]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. The following drugs were used in the following Examples and Comparative Examples. <(Meth) acrylic acid ester> A1: tetraethylene glycol dimethacrylate A2: methoxy polyethylene glycol methacrylate A3: dimethacrylate of 2.6 mol of bisphenol A ethylene oxide adduct A4: hydroxypropyl methacrylate <moisture curable urethane Compound> U1: (polyol component: polypropylene glycol, diisocyanate component: MDI, isocyanate component weight ratio: 8%) U2: (polyol component: ethylene glycol, diisocyanate component: MDI, isocyanate component weight ratio: 15%) U3 : (Polyol component: polyol having polybutadiene as main skeleton, diisocyanate component: MDI, isocyanate component weight ratio: 5%) <Curing accelerator> 4 Tetrahydroquinoline <Curing accelerator> -o-Benzoixulfimide <Organic peroxide> -Cumene hydroperoxide The curability of the air contact surface is measured by applying 3 drops of an adhesive on a stainless steel plate. The time when the stickiness was lost by touching with a hand was measured and evaluated. The adhesive strength was evaluated using the return torque as a parameter. For the return torque, the breaking torque and the escape torque were measured according to the following procedure. <Return torque measurement procedure> An adhesive is applied to M10 degreased steel bolts and nuts, and then screwed and bonded. After 24 hours, the return torque is measured using a torque wrench. That is, the value at the time when the bond is broken first is the breaking torque, and then 1/4,
The average value of the values obtained when the motor is rewound 2/4, 3/4 and 1 turn is defined as the escape torque.

Examples 1 to 4, Comparative Example 1 0.8 parts by weight of o-benzoixulfimide and 1,2,3,4 tetrahydroquinoline were added to 100 parts by weight of (meth) acrylate (A1). Then, the mixture was dissolved by adding 0.6 parts by weight and stirring at 80 ° C. for 10 minutes. After cooling to room temperature, 1.0 part by weight of cumene hydroperoxide was added and mixed well.
Next, the moisture-curable urethane compound (U1) is (meth)
An adhesive composition was prepared by mixing the acrylate with the acrylate at a ratio shown in Table 1. With respect to the obtained adhesive composition, the curability and the adhesive strength of the “air contact portion” were measured. Table 2 shows the results.

[Comparative Example 2] With respect to the moisture-curable urethane compound (U1), the curability and adhesive strength of the “air contact portion” were measured. Table 2 shows the results.

[0021]

[Table 1]

[0022]

[Table 2]

As is clear from Table 2, Examples 1 to 4 in which a (meth) acrylic acid ester and a moisture-curable urethane compound are used in combination show a good "air contact portion" curing performance and a good adhesive strength. . On the other hand, in Comparative Example 1 in which the moisture-curable urethane compound was not blended, the “air contact portion” did not cure even after one day. In Comparative Example 2 in which (meth) acrylic acid ester was not blended, the adhesive strength was low.

Examples 5 to 8 100 parts by weight of (meth) acrylates (A2, A3, A4) shown in Table 3 were
0.8 parts by weight of o-benzoixulfimide and 1,2,2
Add 0.6 parts by weight of 3,4 tetrahydroquinoline and add 80 ° C
For 10 minutes to dissolve. After cooling to room temperature, 1.0 part by weight of cumene hydroperoxide was added and mixed, and then the moisture-curable urethane compound (U
1, U2, U3) 100 parts by weight were mixed well to prepare an adhesive composition. With respect to the obtained adhesive composition, the curability and the adhesive strength of the “air contact portion” were measured. Table 4 shows the results.

[0025]

[Table 3]

[0026]

[Table 4]

From Table 4, it can be seen that, instead of the (meth) acrylate (A1) used in Examples 1 to 4 and the moisture-curable urethane prepolymer compound (U1), another (meth) acrylate (A2) was used. , A3, A4) and a moisture-curable urethane prepolymer compound (U2,
It is clear that even when U3) is used, an adhesive composition exhibiting good "air contact portion" curing performance and good adhesive strength can be obtained.

Example 9 3 parts by weight of a salt obtained by reacting 1 mol of o-benzoixulfimide and 1 mol of 1,2,3,4 tetrahydroquinoline were added to 100 parts by weight of methacrylate (A1). The mixture was dissolved by stirring at 80 ° C. for 10 minutes to prepare a solution A. On the other hand, 100 parts by weight of the moisture-curable urethane compound (U1) was added to cumene hydropar
Liquid B was prepared by mixing 1.0 part by weight of the oxide at room temperature. Next, 50 parts by weight of the liquid A and 50 parts by weight of the liquid B were mixed well to obtain an adhesive. With respect to the obtained adhesive, the curability of the “air contact portion” and the adhesive strength were measured. Table 5 shows the results.

[0029]

[Table 5]

From Table 5, it is clear that even when the adhesive composition of the present invention is applied to a two-part adhesive, good "air contact portion" curability and good adhesive strength can be obtained. .

[0031]

As described above, according to the present invention, there is provided an adhesive composition having improved curing performance of the "air contact portion" while maintaining the advantages of the anaerobic adhesive. Thus, the adhesive composition of the present invention has an excellent "air contact portion".
Since it has a curing performance of, it can be said that it is very convenient for the user, since no troublesome work such as wiping off or cleaning the portion protruding from the adherend is required.

Claims (3)

[Claims] 1. An adhesive composition comprising a (meth) acrylate, an organic peroxide, a curing accelerator, and a moisture-curable urethane prepolymer compound. 2. 100 parts by weight of (meth) acrylate, 0.05 to 10 parts by weight of an organic peroxide, 0.05 to 10 parts by weight of a curing accelerator, 25 to 400 parts by weight of a moisture-curable urethane prepolymer compound. The adhesive composition according to claim 1, comprising: 3. The adhesive composition according to claim 1, wherein the (meth) acrylic ester is selected from those having no hydroxyl group.