JPH01108283A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a cold-setting anaerobic adhesive composition which provides a high bonding rate and has excellent pot life and applicability, by mixing an acrylic monomer, an organic peroxide, a specified reducing agent, and fine hollow siliceous particles. CONSTITUTION:100pts.wt. acrylic monomer (A) {e.g., 2,2- bis[4-(methacryloxydiethoxy)phenyl] propane} is mixed with 0.2-3pts.wt. organic peroxide (B) (e.g., cumene hydroperoxide) encapsulated if required, 0.1-2pts.wt. reducing agent (C) (e.g., dimethyl-p-toluidine) that forms a redox catalyst with component B, and 0.2-20pts.wt. fine hollow siliceous particles (D) (e.g., microballoons of high-strength insoluble glass) having a definite hollow part.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention relates to a one-component adhesive, which has a high adhesion speed to a wide variety of materials and is room temperature curing. ,
This invention relates to an anaerobic adhesive that has improved coating properties by forming a suspension composition that has a long pot life and is more stable.

Since this adhesive composition can be finished to a dry touch, it is suitable as an adhesive for preventing loosening of screws or as an adhesive for laminating laminates.

[Conventional technology]

Conventionally, one-component room-temperature curing adhesives that harden rapidly have been anaerobically cured, mainly containing monomers having acryloyl groups and/or methacryloyl groups (hereinafter referred to as "(meth)acrylate monomers"). sexual compositions have been used.

[Problem that the invention seeks to solve]

Conventional anaerobic curable compositions are compositions that remain oily when in contact with air or oxygen and harden rapidly when removed from air or oxygen.

Therefore, before curing, there are disadvantages such as the risk of chemical burns due to curing accelerators such as oil-based (meth)acrylate monomers, peroxides, or amines, unstable pot life, and the selection of adherend materials. It had

Furthermore, if an inorganic substance with a high sedimentation property is added to the composition for the purpose of imparting thixotropy or increasing adhesive strength, the viscosity of the composition becomes unstable, resulting in poor coating properties. Something happened.

(B) Structure of the invention [Means for solving the problems] The present invention comprises 100 parts by weight of (meth)acrylate monomer, 0 parts by weight of organic peroxide,
．． 2 to 3 parts by weight, 0.1 to 2 parts by weight of a reducing agent that forms a redox system with the organic peroxide, and 0.2 to 20 parts by weight of hollow silicic acid fine particles.

[(meth)acrylate monomer]

The (meth)acrylate monomer of the present invention can be used as it is if it is physically homogeneously mixed with the other components constituting the present invention, but if it is emulsified in water using the method described above, it may cause chemical injuries. This is preferable because it can reduce risks and greatly improve coating properties.

That is, a (meth)acrylate monomer is gradually added to an aqueous solution of a polymer that has surface activity in an aqueous state and has a number average molecular weight of about 3,000 to 50,000 under vigorous stirring. Can be emulsified.

At this time, if a water-soluble polymer and/or an emulsion polymer having film-forming ability are added at the same time as the (meth)acrylate monomer is emulsified or added after the emulsification, the resulting adhesive composition is It is preferable to form a resin film after coating and obtain a coated surface with a dry touch, but it is preferable to use a polymer that has the film-forming ability described below and can emulsify the (meth)acrylate monomer. You can also do it.

Examples of polymers that have film-forming ability and can emulsify (meth)acrylate monomers in water include acrylic ester resins having a copolymer composition of 20 to 50% acrylic acid;
Alternatively, methyl vinyl ether copolymer, polyvinylpyrrolidone, polyvinyl alcohol with a saponification degree of 70 to 98 mol%, ethyl cellulose, hydroxypropyl cellulose, methoxy hydroxypropyl cellulose, ethylene-maleic anhydride copolymer, water-soluble nylon polymer, Water-soluble polymers such as urea-formalin polymers or block copolymers of polyethylene oxide and polypropylene oxide; emulsion polymers such as acrylic acid ester resin emulsions, urethane emulsions, chloroprene polymer emulsions, or butadiene-acrylonitrile emulsions. It will be done.

Among these polymers, polyvinyl alcohol having a degree of saponification of 70 to 98 mol % is preferred because it has a high emulsifying power for (meth)acrylate monomers, and a water-soluble nylon polymer has a high film-forming ability.

Among these polymers, it is preferable to use a mixture of a polymer having a high emulsifying power of the (meth)acrylate monomer and a polymer having a high film-forming ability, since this provides suitable conditions for the method of the present invention.

The (meth)acrylate monomer used in the present invention is methyl (meth)acrylate.

Ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate
Tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, Allyl (meth)
Acrylate, dimethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate Methoxyethyl (meth)acrylate, n-butoxyethyl (meth)
acrylate, sulfopropyl (meth)acrylate,
Mono(meth)acrylates such as 2-hydroxyethyl acryloyl phosphite, acetoxyethyl (meth)acrylate, and methylcarpitol (meth)acrylate; ethylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, 1.3 −
Butanediol di(meth)acrylate, polyester di(meth)acrylate obtained by dehydration condensation of polybasic acid, polyol and (meth)acrylic acid and polyesterification reaction, epoxidized bisphenol A di(meth)acrylate, ethylene glycol, diethylene glycol or Di(meth)acrylate obtained from a condensate consisting of triethylene glycol and epoxidized bisphenol A and (meth)acrylic acid Di(meth)acrylate such as polyurethane di(meth)acrylate obtained from diisocyanate, glycol and hydroxyalkyl (meth)acrylate ) Acrylate; further examples include compounds containing two or more (meth)acrylate structures obtained from glycerin, trimethylolpropane, pentaerythritol, and (meth)acrylic acid.

Among these (meth)acrylate monomers, di(meth)acrylates of ethylene glycol, triethylene glycol or tetraethylene glycol; condensates consisting of ethylene glycol, diethylene glycol or triethylene glycol and epoxidized bisphenol A; Di(meth)acrylate obtained from acrylic acid is preferable because it has a high adhesive strength when used as an adhesive composition.

[Organic peroxide]

Powdered or liquid organic peroxide can be used as it is if it is physically uniformly mixed with the other components constituting the present invention, but by encapsulating it, the pot life is improved and a one-component type is used. A composition that is even more excellent as an adhesive composition can be obtained.

The encapsulation method involves dispersing a finely powdered organic peroxide in a urea-formalin prepolymer obtained by a methylolation reaction at a pH of 7.5 to 9, and then increasing the pH to 2 to 9.
3 and maintaining the reaction temperature at 35 to 45°C and encapsulating the produced polymer while depositing it in the peroxide powder through the methylene reaction, the produced capsules have excellent water resistance and oil resistance. preferable.

As the organic peroxide used in the present invention, hydroperoxide, ketone peroxide, dialkyl peroxide, peroxy ester, diacyl peroxide, etc. can be used, but benzoyl peroxide or meta-toluoyl peroxide is particularly suitable. When used in an adhesive composition, organic peroxides with a strong redox reaction, such as organic peroxides, have a high adhesion ability (but on the other hand, the pot life is shortened), so it is desirable to encapsulate them according to the above-mentioned method.

The amount of organic peroxide used is (meth)acrylate monomer 1
0.2 to 3 parts by weight are required for 00 parts by weight,
Preferably it is 0.5 to 2 parts by weight.

If the amount is less than 0.2 parts by weight, the adhesion ability will not be sufficiently exhibited, while if it exceeds 3 parts by weight, more than the appropriate amount may be mixed in as foreign matter and the adhesion ability may be reduced.

[Reducing agent that forms a redox system with an organic peroxide] The compound can be used dissolved or uniformly dispersed in the (meth)acrylate monomer, but if the (meth)acrylate monomer is emulsified. When used as such, it is preferable to add it at the time of emulsification and emulsify at the same time, or to add it to the dispersion after emulsification to disperse it uniformly.

Specific examples of such compounds include organic acid salts of copper, cobalt, manganese, etc. for organic hydroperoxides or peroxyesters; ethylenethiourea, tetramethylthiourea; , hydrophobic mercapto compounds such as 2-mercaptobenzimidazole; hydrazine tf'b' such as hydrazine, 2-hydroxyhydrazine, benzoylhydrazine, etc.
4-body; sodium p-toluenesulfinate, L-ascorbic acid, triethylenediamine, etc. are used.

Among these, it is preferable to use ethylene thiourea or L-ascorbic acid because the reactivity increases.

For diacyl peroxides, dimethylaniline, dimethyl-p-)luidine, diethyl-p-)luidine, N,N dimethylnyl-anisidine, 0-sulfobenzoic acid imide; further mercaptoethanol, thiomalic acid, thioglycolic acid, Water-soluble mercapto compounds such as thiolactic acid, α-thiobutyric acid, mercabutethylamine, or 0- or m-thiosalicylic acid are used, respectively.

Among these, it is preferable to use dimethyl-P-)luidine or 0-sulfobenzoic acid imide because the reactivity increases.

The amount of the compound used is (meth)acrylate monomer 10
0.1 to 2 parts by weight are required, preferably 0.3 to 2 parts by weight.

When the amount is less than 0.1 parts by weight, the redox reaction is weak and there is no adhesive ability at room temperature or below, while when it exceeds 2 parts by weight, the redox reaction mechanism tends to be unbalanced and the adhesive ability tends to decrease. It's inappropriate.

[Hollow silicic acid fine particles]

The present invention requires the addition of hollow siliceous fine particles to a composition comprising a (meth)acrylate monomer, an organic peroxide, and a reducing agent.

A known example whose technical concept is contrasted with the addition of hollow silicic acid fine particles is a urethane acrylate monomer having a vinyl reaction end and at least one monofunctional short chain monomer having a hydroxyl group at the end. and about 20% to about 70% by weight of the total composition.
There is a method of imparting a high adhesion speed by incorporating a coexisting powder filler in a proportion by weight (Japanese Patent Application Laid-open No. 187014/1983).

The coexisting powder fillers used here are commonly known aluminum metal powder, alumina powder, barium sulfate, calcium carbonate, silica, and magnesium hydroxide, all of which do not have hollow spaces.

On the other hand, the hollow silicic acid fine particles used in the present invention have a clear hollow part and therefore have a small specific gravity.

Hollow silicic acid fine particles can be used as they are if they are physically uniformly mixed with other components constituting the present invention, but
It is preferable to use a capsule-shaped powder containing the hollow silicic acid fine particles obtained by the following method.

That is, hollow silicic acid fine particles whose surfaces are wetted with a hydrophobic liquid in which an organic peroxide is dissolved or dispersed are dispersed in a prepolymer of urea resin or melamine resin obtained by a methylolation reaction, and then the urea resin is Alternatively, a melamine resin wall is generated to cover the surface of the hollow silicic acid particles and the hydrophobic liquid. Using this method, the hollow silicic acid particles can be encapsulated at the same time as the organic peroxide. However, when this capsule is used, peroxide is liberated at the same time as the hollow silicic acid fine particles are destroyed, resulting in increased reactivity.

The hollow silicate fine particles used in the present invention are fine particles obtained by melting and pulverizing sodium silicate, silica sand, and a foaming agent, and expanding this under heating; Fine particles (shirasu balloons) made by heating after adjusting the particle size and foaming with the contained moisture; or granular foams obtained by chemically treating silica sand, granulating it, and firing it in a rotary kiln, etc. When the adhesive composition is aqueous, it is preferable to use a water-resistant adhesive such as a glass balloon or a ceramic adhesive.

The amount of the fine particles used is (meth)acrylate monomer 1
0.00 parts by weight, it is necessary to be 0.2 to 20 parts by weight, preferably 0.5 to 10 parts by weight.

If it is less than 0.2 parts by weight. No effect of use is observed, and on the other hand, if the amount exceeds 20 parts by weight, the fluidity of the composition deteriorates, which is inappropriate.

[Other substances that may be employed in the adhesive composition of the present invention] Talc, silica, alumina, or calcium carbonate, which are commonly used for the purpose of improving the properties of the adhesive composition, for example, to impart thixotropic properties; In order to maintain a long pot life, hydroquinone, methylhydroquinone, 2,4-dinitroanisole or 2,6-ditertiary-butyl p-cresol can be added.

[Effect]

The adhesive composition of the present invention is a one-component composition containing a (meth)acrylate monomer as a main component, in which hollow silicic acid fine particles are added, and the hollow silicic acid fine particles have a clear hollow part. Unlike ordinary inorganic fine particles, since they have a low specific gravity, they are less likely to settle in the composition.

Therefore, it has good viscosity stability and improved coating properties when applied to adherends.

Further, after being applied to an adherend, the hollow silicic acid fine particles accumulate on the surface layer of the oil-based or aqueous composition to form a dry-touch layer, which is of high value in terms of hygiene and safety.

Therefore, products coated with the composition can be easily managed during storage or transportation.

Furthermore, in the bonding process, when pressure or friction is applied to the composition of the present invention, the hollow silicic acid fine particles are easily destroyed and become activated fine particles, which promotes the redox reaction and can be applied to a wide variety of materials during bonding. The adhesion speed can be increased compared to the above.

[Examples and comparative examples]

The present invention will be explained in more detail by giving examples and comparative examples below.

As an evaluation method, the adhesion performance to bolts and screws was conducted using the following test method.

(Coating adhesive composition to bolts and screws) 81IIIn
Yellow chromate and stainless steel (S) with a diameter and length of 40 mm.
so that it fills the groove of the screw made of US304).
0.15 g of the water-free adhesive composition was applied uniformly and the applied adhesive clamp obtained a molded screw.

On the other hand, 0.2 g of the aqueous adhesive composition was uniformly applied and then dried at 80° C. for 20 minutes to obtain a screw with a tack-free film formed on the surface.

(Adhesive Performance Test) (a) Adhesive Test The coated screws described above were tightened with a torque of 230 kg/cam, and after being left at 23°C for 1 hour, the start-up return torque was measured.

(b) Adhesive performance pot life test After continuing to heat the above-mentioned coated screw at 40°C for 2 months, it was tightened with a torque of 230 kg/cot.
The starting return torque after being left at ℃ for 1 hour was measured.

(C) Heat resistance test The coated screws described above were tightened with a torque of 230 kg/cam, continued heating at 120°C for 1 hour,
While holding at "C", the starting return torque was measured.

Example 1 NK BP in a 1β beaker equipped with a homogenizer
E-200 (2,2bis[4-(methacryloxyjethoxy)phenyl]propane, manufactured by Shin-Nakamura Chemical Industry ■) 1
000 g, 10 g of cumene hydroperoxide, 7 g of dimethyl para-toluidine and FTD-202 (high strength insoluble glass microballoon, true specific gravity 0.28 g/
cc.

30 g of Nippon Silikani Co., Ltd. (Particle size: 10 to 100 .mu.l) was added and stirred for 30 minutes to obtain a stable oily suspension.

The liquid was tested according to the evaluation method described above. The results are shown in Table 1.

Examples 2 to 5, Comparative Example 1 In Example 1, the (meth)acrylate monomer, the organic peroxide, the reducing agent that forms a redox system with the organic peroxide, and the type of hollow silicic acid fine particles. Table 1 shows the test results when the amount was changed as shown in Table 1 and the other conditions were the same as in Example 1.

Example 6 Hollow silicic acid fine particles (hollow capsules) with benzoyl peroxide adsorbed on the surface and coated with urea resin were synthesized by the following method, and (meth)acrylate monomer was synthesized by the following method. It was made into an emulsified liquid in a polyvinyl alcohol aqueous solution.

(Synthesis of hollow capsules) 11 Aqueous formalin solution with a concentration of 37% by weight in a flask 35
0 g, urea 131 g, and triethanolamine 1.7
The mixture was stirred at 70″C and 3°Orpm for 2 hours to react.
A prepolymer with a pm viscosity of 7.5 cps was obtained.

Next, the above prepolymer aqueous solution 609 was added to flask 21.
g and 441 g of pure water, dioctyl phthalate 6,
FTD-20212 whose surface was wetted with a paste mixture consisting of 4 g and 6.4 g of benzoyl peroxide.
, 8 g was prepared and dispersed using a homogenizer under stirring at 60 rpm, and then 5 cc of an IN aqueous solution of hydrochloric acid was added to adjust the pH to 2.5.

After that, stirring was continued for 1 hour at 25°C, then for 6 hours at 40'C, and 300cc of pure water was added, and the mixture was heated at 40°C for 3 hours.
The reaction was continued for 14 hours with stirring reduced to 0.00 rpm.

After neutralizing the obtained slurry with an IN aqueous solution of caustic soda,
After washing with pure water and methanol and drying on trays at 4°C, the particle size was 2o~80μI and true specific gravity was 0.95.
g/cc, 5.0% by weight of benzoyl peroxide and 10% by weight of hollow silicic acid particles in terms of active oxygen amount.
A hollow capsule containing the following was obtained.

(Preparation of (meth)acrylate monomer emulsion) 860 g of pure water in a 2°C beaker, Gohsenol GM-14 (partially saponified polyvinyl alcohol with a degree of saponification of 86 mol% and an average degree of polymerization of 1400, manufactured by Nippon Gosei Kagaku Kogyo ■) ) 82.8g, make it into an aqueous solution, and then heat it to 200O with a homogenizer.
Under rpm stirring, the above NK BPE-20010
After 2 hours of stirring, an aqueous emulsion was obtained.

This emulsion had emulsified particles with a particle size of 2 to 6 μm, and a viscosity of 8500 cps at 6 rpm using a B-type viscous needle.

(Preparation of adhesive composition) The entire amount of the (meth)acrylate monomer emulsion obtained above, 200 g of the hollow capsules obtained above, and 7 g of dimethyl para-toluidine were put into a beaker 22,
Stirring was performed using a homogenizer at 2000 rpm for 5 minutes to obtain an aqueous adhesive composition.

Table 1 shows the results obtained for the liquid according to the evaluation method described above.

Examples 7 to 8, Comparative Example 2 In Example 1, the (meth)acrylate monomer, the organic peroxide, the reducing agent that forms a redox system with the organic peroxide, and the type of hollow silicic acid fine particles. Table 1 shows the test results when the amount was changed as shown in Table 1 and the other conditions were the same as in Example 1.

However, in Comparative Example 2, AERO3I L was used instead of FTD-202 in the synthesis process of the hollow capsule of Example 6.
TT600 (Fine powder silica with SiOz content of 99.8% by weight or more, true specific gravity 1.9g/CC% particle size 20-5
0um, manufactured by Nippon Aerosil ■) was used.

(c) Effects of the Invention The adhesive composition of the present invention has a low-temperature reaction type composition containing a (meth)acrylate monomer as a main component, as well as the presence of hollow silicic acid particles. Coating properties are improved through stabilization, and the surface layer of the adherend forms a dry-touch layer, making it suitable for storage and transportation of the adherend.

Furthermore, during the adhesion process, the hollow silicic acid fine particles have great adhesion ability to a wide variety of base materials, making it extremely versatile.

Claims (1)

[Claims] 1. 100 parts by weight of a monomer having an acryloyl group and/or methacryloyl group, 0.2 to 3 parts by weight of an organic peroxide, 0 reducing agent that forms a redox system with the organic peroxide.
．． An adhesive composition comprising 1 to 2 parts by weight and 0.2 to 20 parts by weight of hollow silicic acid fine particles.