JP2570400B2 - Adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the Invention [Industrial Application Field] The present invention relates to an adhesive having anaerobic curability, and particularly has a high bonding speed to a wide range of various materials.
The present invention relates to an anaerobic adhesive which is a room temperature curing type and has a long pot life even under high temperature and high humidity conditions.

In this adhesive composition, for example, a one-pack composition obtained by encapsulating an organic peroxide in a capsule is used by pre-coating the composition onto a metal material in advance and forming a coating film with the adhesive composition. It is suitable in the field, for example, as an adhesive for preventing loosening of screws.

[Conventional technology]

Conventionally, as a one-part cold-setting adhesive that cures rapidly, an anaerobic composition mainly composed of a monomer having an acryloyl group and / or a methacryloyl group (hereinafter referred to as “(meth) acrylate monomer”). Curable compositions have been used.

[Problems to be solved by the invention]

Conventional anaerobic curable compositions, under low temperature, low humidity conditions,
A composition that remains oily in contact with air or oxygen and cures rapidly when cut off from air or oxygen.

However, when it is stored under high temperature and high humidity conditions, it has a drawback that the adhesive ability is remarkably reduced. In particular, there has been a great limitation in applications in which a so-called pre-coat is applied to a metal surface in advance and used.

(B) Constitution of the Invention [Means for Solving the Problems] The present invention relates to a method for producing a methacrylic acid or chlorophyll or a metal of chlorophyll or 0.2 to 10 parts by weight per 100 parts by weight of a (meth) acrylate monomer. An adhesive composition containing a substituted product (hereinafter, collectively referred to as "chlorophylls").

[(Meth) acrylate monomer]

The (meth) acrylate monomer in the present invention can be used as it is if it is physically and uniformly mixed with other components constituting the present invention. This is preferable because the danger of the coating can be reduced and the coating property can be greatly improved.

That is, it has surface activity and has a number average molecular weight of 3,000 to 5,000.
The (meth) acrylate monomer can be emulsified by gradually adding the (meth) acrylate monomer to an aqueous solution of a polymer of about 0 under high stirring.

At this time, a water-soluble polymer and / or a water-dispersible polymer having a film-forming ability are added at the same time when the (meth) acrylate monomer is emulsified, or after the (meth) acrylate monomer is emulsified in advance, When added, the resulting adhesive composition forms a resin film on the surface after its application, a dry-touch coated surface can be obtained, and chlorophylls are adsorbed by these film-forming polymers. It is preferable because the pot life of the adhesive composition, which is one of the objects of the present invention, can be more effectively improved.

Further, a polymer having a film forming ability as described later and capable of emulsifying a (meth) acrylate monomer can also be used.

(Meth) acrylate monomers used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate. Acrylate, 2-hydroxyethyl (meth)
Acrylate, allyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, methoxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, sulfopropyl (meth) acrylate, 2-hydroxyethylacryloyl Mono (meth) acrylates such as phosphite, acetoxyethyl (meth) acrylate and methyl carbitol (meth) acrylate; ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-butanediol di ( (Meth) acrylate, polybasic acid and polyol, and acrylic acid and / or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”). Di (meth) acrylate, diisocyanate, glycol and hydroxyalkyl obtained from (meth) acrylic acid and a condensate of acrylate, epoxidized bisphenol A di (meth) acrylate, ethylene glycol, diethylene glycol or triethylene glycol and epoxidized bisphenol A Di (meth) acrylates such as polyurethane di (meth) acrylate obtained from (meth) acrylate;
Further, glycerin, trimethylolpropane, pentaerythritol, and the like, and a compound containing two or more (meth) acrylate structures obtained from (meth) acrylic acid, and the like are included. The (meth) acrylate monomer having an acryloyl group and a methacryloyl group in one molecule can be obtained by using acrylic acid and methacrylic acid as raw materials at the time of production.

Among these (meth) acrylate monomers, di (meth) acrylate of ethylene glycol, triethylene glycol or tetraethylene glycol; condensate of ethylene glycol, diethylene glycol or triethylene glycol and epoxidized bisphenol A and (meth) When di (meth) acrylate obtained from acrylic acid is used as the adhesive composition, the adhesive strength is large, which is preferable.

Next, as a polymer having a film forming ability and capable of emulsifying (meth) acrylate monomer in water, an acrylate resin having (meth) acrylic acid in a copolymer composition of 20 to 50% by weight, Alternatively, methyl vinyl ether copolymer, polyvinyl pyrrolidone, polyvinyl alcohol having a saponification degree of 70 to 99 mol%, ethyl cellulose, hydroxypropyl cellulose, methoxyhydroxypropyl cellulose, ethylene-maleic anhydride copolymer, water-soluble or water and alcohol A nylon polymer soluble in a mixed solvent with
Water-soluble polymers such as urea resins, melamine resins, or block copolymers of polyethylene oxide and polypropylene oxide; water-dispersible polymers such as acrylate resin emulsions, urethane emulsions, chloroprene polymer emulsions, or butadiene-acrylonitrile emulsions Coalescence.

Among these polymers, polyvinyl alcohol having a saponification degree of 70 to 99 mol%, a nylon polymer soluble in water or a mixed solvent of water and an alcohol, or a mixture thereof has a chlorophyll adsorption property. It is preferable because it has an effect of suppressing a redox reaction on the adhesive composition.

Further, among these polymers, it is more preferable to use a mixture of a polymer having a large emulsifying power of a (meth) acrylate monomer and a polymer having a large film-forming ability.

(Organic peroxide)

The powdery or liquid organic peroxide can be used as it is as long as it is physically homogeneously mixed with the other components constituting the present invention. A more excellent composition can be obtained as the adhesive composition.

As a method of encapsulation, the organic peroxide in the form of fine powder is dispersed in a urea-formalin prepolymer obtained by a methylolation reaction at pH 7.5 to 9, and then the pH is lowered to 2-3 and the reaction is carried out. A method of maintaining the temperature at 35 to 45 ° C. and encapsulating the resulting polymer by depositing it on a peroxide powder by a methylene reaction is preferable because the resulting capsule has excellent water resistance and oil resistance.

As the organic peroxide used in the present invention, hydroperoxide, ketone peroxide, dialkyl peroxide, peroxyester, diacyl peroxide, etc. can be used. Particularly, benzoyl peroxide or meta-toluoyl peroxide is used. When an organic peroxide having a strong redox reactivity such as described above is used in an adhesive composition, the potency is increased while the adhesive ability is increased. Therefore, it is preferable to use the organic peroxide encapsulated according to the above method.

The amount of organic peroxide used is (meth) acrylate monomer
For 100 parts by weight, 0.2 to 10 parts by weight is required, and preferably 0.5 to 2 parts by weight.

When the amount is less than 0.2 parts by weight, the adhesive ability is not sufficiently exhibited. On the other hand, when the amount exceeds 10 parts by weight, an excessive amount may be mixed as a foreign substance and the adhesive ability may decrease.

In addition, as described below, when a reducing agent that forms a redox system with an organic peroxide (hereinafter, referred to as a “reducing agent”) is mixed together with the adhesive composition, the amount of the organic peroxide used is reduced. The amount may be small, and the preferred amount is 0.2 to 5 parts by weight.

(Chlorophylls)

In the present invention, it is necessary that chlorophylls coexist in a composition comprising a (meth) acrylate monomer and an organic peroxide.

A well-known example that is technically contrasted with the addition of chlorophylls is an anaerobic mixture obtained by adding a chelating agent containing no = C = N- group to a mixture of an acrylate monomer and a peroxide. Compositions (JP-B-51-20555).

The chlorophylls of the present invention with respect to the chelating agent described above, for example, chlorophyll is schematically represented by the following formula,
It has four pyrrole nuclei, clearly = C =
It has an N-group and is essentially different from the above-mentioned known examples.

Further, the chelating agent used in JP-B-51-20555 aims to increase the stability of the anaerobic composition, and the purpose of the present invention, i.e., the composition under high temperature and high humidity conditions before use. To prevent the redox reactivity of the product from decreasing and losing the desired good curability during use,
The mechanism is different.

Chlorophylls can be used as they are if they are physically homogeneously mixed in the composition of the present invention.
70-99 mol% of polyvinyl alcohol, water-soluble or a nylon polymer soluble in a mixed solvent of water and alcohol, or an aqueous medium in which a mixture thereof is dissolved or dispersed, and adsorbed to these polymers Is particularly preferred.

Specific examples of chlorophylls include chlorophyll and a metal-substituted product of chlorophyll in which magnesium is replaced with copper or zinc in the above formula showing chlorophyll, such as copper chlorophyll and zinc chlorophyll, and chlorophyll further similarly replaced with sodium. Mixtures with the above-mentioned metal substitutes, such as sodium copper chlorophyll and sodium zinc chlorophyll, may be mentioned. Of these, sodium copper chlorophyll is preferred because of its high stability.

The effect of the chlorophyll can be seen if the chlorophyll is used in a small amount in a composition comprising a (meth) acrylate monomer and an organic peroxide.
The amount is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, per 100 parts by weight.

If the amount is less than 0.01 part by weight, the effect of improving the pot life is small, and if it exceeds 5 parts by weight, the effect does not increase.

(Other substances that can be added to the adhesive composition of the present invention)

A reducing agent can be added to the adhesive composition of the present invention for the purpose of further increasing the bonding speed.

The compound can be used by dissolving or uniformly dispersing it in the (meth) acrylate monomer, but when the (meth) acrylate monomer is emulsified and used, it is added uniformly during emulsification. Is preferred.

Specific examples of the compound include organic acid salts such as copper, cobalt and manganese for organic hydroperoxides or peroxyesters when they are used in combination with organic peroxides used simultaneously; ethylene thiourea, tetramethyl thiourea And hydrazine derivatives such as hydrazine, 2-hydroxyhydrazine and benzoylhydrazine; sodium p-toluenesulfinate, L-ascorbic acid, and triethylenediamine.

Of these, the use of ethylene thiourea or L-ascorbic acid is preferred because the reactivity increases.

For diacyl peroxide, dimethylaniline, dimethyl-p-toluidine, diethyl-p-toluidine, N, N dimethyl-p-anisidine, o-sulfobenzoic acid imide; and mercaptoethanol, thiomalic acid, thioglycolic acid, A water-soluble mercapto compound such as thiolactic acid, α-thiobutyric acid, mercaptoethylamine, or o- or m-thiosalicylic acid is used, respectively.

Of these, the use of dimethyl-p-toluidine or o-sulfobenzoic imide is preferred because reactivity is increased.

The amount of the compound used is (meth) acrylate monomer 10
The amount is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 2 parts by weight, based on 0 parts by weight.

When the amount is less than 0.1 part by weight, the redox reactivity is weak. On the other hand, when the amount exceeds 5 parts by weight, the balance of the redox reaction mechanism is lost, and the pot life of the adhesive performance tends to decrease.

For the purpose of improving the properties of the adhesive composition, for example, to impart thixotropic properties, talc, silica, alumina or calcium carbonate, which are usually used, to maintain a long pot life, hydroquinone, methylhydroquinone, 2,4-dinitroanisole or 2,6-ditert-butyl p-cresol can be added.

[Action]

The adhesive composition of the present invention is excellent in both anaerobic adhesive performance and pot life even without using a reducing agent.

Although the reason for this is not clear, it is thought to be due to the specific chelating effect of chlorophylls on metal ions.

(Examples and Comparative Examples)

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The performance of the adhesive composition of the present invention was evaluated by the following test method.

Evaluation in Examples 1 to 5 and Comparative Examples 1 and 2 (a) Coating of adhesive composition to bolts and screws, adhesion test and initial adhesion test 8 mm diameter, 40 mm long yellow chromate and stainless steel (S
Apply 0.2 g of the adhesive composition evenly to the groove of the screw made of US304), immediately tighten the nut with a torque of 230 kgf / cm, and return to the starting torque after leaving it at 23 ° C for 20 minutes (initial adhesion) Test) and the start-up return torque after one hour of standing (adhesion test).

(B) Adhesive performance pot life test After leaving 500 g of the adhesive composition in a beaker made of glass without covering, leaving it in a humidified state at 50 ° C. and a relative humidity of 95% for 2 days, a 230 kgf · cm The nut was tightened with the torque, and the starting return torque after leaving at 23 ° C. for 1 hour was measured.

(C) Heat resistance test Tighten the nut to the coated screw of (a) with a torque of 230 kgf / cm, continue heating at 150 ° C for 30 minutes, and reduce the startup return torque while holding at 150 ° C. It was measured.

Evaluation in Examples 6 to 8 and Comparative Example 3 (Application of adhesive composition to bolts and screws) 8 mm diameter, 40 mm length yellow chromate and stainless steel (S
US304), the water-based adhesive composition 0.2
g, then dried at 80 ° C for 20 minutes,
An adhesive fastening screw having a tack-free film formed on the surface was obtained.

(Adhesion performance and other evaluation tests) (a) Adhesion test and initial adhesion test Tighten a nut to the coated screw with a torque of 230 kgf / cm and leave it at 23 ° C for 20 minutes to start up torque ( (Initial adhesion test) and return torque after standing for 1 hour (adhesion test) were measured.

(B) Pot life test of adhesion performance After the coated screw was left in a humidifier at 50 ° C and a relative humidity of 95% for 5 days, a nut was tightened with a torque of 230 kgf · cm, and the nut was tightened at 23 ° C. The starting return torque after standing for a time was measured.

(C) Heat resistance test Tighten the nut to the coated screw of (a) with a torque of 230 kgf / cm, continue heating at 150 ° C for 30 minutes, and reduce the startup return torque while holding at 150 ° C. It was measured.

Example 1 NK BPE-200 @ 2,2bis [4- (methacryloxydiethoxy) phenyl] propane, Shin-Nakamura Chemical Co., Ltd.
Made 1000g, cumene hydroperoxide 10g, and copper chlorophyll sodium 10g into a 2l beaker,
The mixture was stirred with a laboratory mixer at 1000 rpm for 5 minutes to obtain an adhesive composition.

Table 1 shows the results obtained for the composition according to the evaluation method described above.
It writes in.

Example 2, Comparative Example 1 The type and amount of the (meth) acrylate monomer, organic peroxide, chlorophyll, or reducing agent in Example 1 were changed as shown in Table 1, and other conditions were the same as in Example 1. Table 1 shows the test results of the adhesive composition obtained in exactly the same manner as in Example 1.

Examples 3 to 5 and Comparative Example 2 The type and amount of the (meth) acrylate monomer, organic peroxide, chlorophyll, or reducing agent in Example 1 were changed as shown in Table 1, and the stirring speed was changed. 2000rpm,
Table 1 shows the test results of the adhesive composition obtained in the same manner as in Example 1 except for the other conditions.

Example 6 (Preparation of (meth) acrylate monomer emulsion) In a 2 l beaker, 860 g of pure water and gohsenol GM-14 (partially saponified polyvinyl alcohol having a saponification degree of 86 mol% and an average polymerization degree of 1400, Nippon Synthetic Chemical Industry) 100 g)
It was made into an aqueous solution. Then, under stirring at 650 rpm with a propeller type stirring device, tetrahydrofurfuryl methacrylate 1000
g, and 66.7 g of a methanol solution containing 30% by weight of AQ-nylon A-70 (dimethylamino-substituted nylon, manufactured by Toray Industries, Inc.), and stirred for 2 hours to obtain an aqueous emulsion. "Gohsenol" is a registered trademark.

This emulsion had emulsified particles having a particle size of 2 to 6 μm, and had a viscosity of 6000 cps at 6 rpm in a B-type viscometer.

(Encapsulation of organic peroxide) In a 3 liter flask, a 37% by weight aqueous solution of formalin 10
50 g, 393 g of urea and 5.1 g of toluethanolamine were charged and stirred at 70 ° C. for 2 hours at 300 rpm using a propeller type stirrer, and reacted at pH 8.1 and 60 rpm by a B-type viscometer.
A prepolymer having a viscosity of 7.5 cps was obtained.

Next, 1827 g of the above prepolymer aqueous solution and 1827 g of pure water were charged into a 5 L container, the pH was adjusted to 2.3 with 1N sulfuric acid, 38.4 g of benzoyl peroxide was added, the temperature was raised to 40 ° C, and the mixture was stirred with a homogenizer at 4000 rpm. After reacting for 6 hours, the mixture was stirred for 14 hours with a propeller type stirring device at 300 rpm.
The reaction was continued for hours.

Neutralize the resulting slurry with a 1N aqueous solution of caustic soda,
As a result of washing with pure water and methanol and drying at 40 ° C., a capsule containing 25% by weight of benzoyl peroxide and having a particle size of 20 to 50 μm and containing a urea resin as a film was prepared.
3.6 g was obtained.

(Adjustment of adhesive composition) The total amount of the (meth) acrylate monomer emulsion obtained above (containing 1000 g as (meth) acrylate monomer), 40 g of encapsulated organic peroxide (benzoyl peroxide) 10g), and chlorophyll 10g
Was put into a 2 liter beaker, and stirred with a homogenizer at 1000 rpm for 5 minutes to obtain an aqueous adhesive composition.

Table 1 shows the results of obtaining the liquid according to the above-described evaluation method.

Example 7 and Comparative Example 3 In Example 6, the types and amounts of the (meth) acrylate monomer, organic peroxide, chlorophyll or reducing agent were changed as shown in Table 1, and the other conditions were the same as in Example 6. Table 1 shows the test results when the test was carried out in exactly the same manner as described above.

Example 8 (Preparation of (meth) acrylate monomer emulsion) Except that NK BPE-200 was used as the (meth) acrylate monomer, the (meth) acrylate monomer was used under exactly the same conditions as in Example 6. An emulsion was obtained.

(Encapsulation of Organic Peroxide) A benzoyl peroxide capsule 5 was prepared under the same conditions as in Example 6 except that the scale was 1/3 times that of Example 6.
1.2 g were obtained.

(Adjustment of Adhesive Composition) The total amount of the (meth) acrylate monomer emulsion obtained above, 40 g of encapsulated organic peroxide (containing 10 g as benzoyl peroxide), 7 g of dimethyl paratoluidine, and chlorophyll Put 5g into 2l beaker,
The mixture was stirred at 2000 rpm for 5 minutes with a homogenizer to obtain an aqueous adhesive composition.

Table 2 shows the results obtained for the composition according to the evaluation method described above.
It writes in.

Examples 9 to 15 and Comparative Example 4 The type and amount of the (meth) acrylate monomer, organic peroxide, chlorophyll, or reducing agent in Example 8 were changed as shown in Table 2, and other conditions were as follows. Table 2 shows the test results of the adhesive composition obtained in exactly the same manner as in Example 8.

(C) Effects of the Invention The adhesive composition of the present invention has a long pot life even under severe conditions of high temperature and high humidity, and has a large adhesive ability even under severe conditions for various materials. is there.

The adhesive composition of the present invention is suitable for use in fields where it is pre-coated on a metal material in advance to form a coating film of the adhesive composition, for example, as an adhesive for preventing screws from being loosened.

Claims (1)

(57) [Claims] An adhesive composition comprising 100 parts by weight of a (meth) acrylate monomer, 0.2 to 10 parts by weight of an organic peroxide, and chlorophyll or a metal substitute of chlorophyll.