JPH08232940A - Adhesive composition of water dispersion type and bolt or nut using it - Google Patents

Abstract

PURPOSE: To provide the adhesive composition of water dispersion type having excellent adhesive performance and storage stability, and a bolt or nut excellent in the loosening stopping effect using the adhesive composition of water dispersion type. CONSTITUTION: 2-acryl amide-2-methyl propane sulfonic acid salt, micro capsule including organic peroxide, and the reducing agent forming redox reaction with organic peroxide compounded in the monomer having (metha)acryloyl group by the protective colloid consisting of the aqueous polymer to make the adhesive composition of the water dispersion type, and this adhesive composition of the water dispersion type is coated on the threaded part of a bolt or a nut to form the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-dispersible adhesive composition which can be suitably used as a screw loosening adhesive, and more particularly to a water-dispersible room temperature curing adhesive. More specifically, the present invention relates to a one-pack type adhesive capable of forming a non-tacky adhesive film on the surface of an adherend, and a bolt or nut coated with the water-dispersed adhesive composition.

[0002]

2. Description of the Related Art When an adhesive agent for preventing loosening is applied to screw portions of bolts and nuts for the purpose of tightly holding a fixed state, it is usually necessary to prevent loosening at a time with respect to screw portions of many bolts or nuts. The method of applying the adhesive of (1) to form an adhesive film and using the obtained bolt or nut within a period in which the adhesive ability of the adhesive film is maintained. As such an adhesive agent for preventing slackening, conventionally, a monomer mainly having an acryloyl group and / or a methacryloyl group is mainly used, and a polymerization initiator such as a peroxide and a reducing agent is added to the adhesive as needed. Liquid acrylic anaerobic adhesive compositions are known.

As the above one-pack type acrylic anaerobic adhesive composition, it is known that the medium is an organic solvent and the medium is an aqueous solvent, and they are properly used depending on the application. However, in recent years, water-based acrylic anaerobic adhesives have been desired even in the field of adhesives for preventing screws from loosening due to problems of environmental pollution by organic solvents and toxicity to the human body.

[0004]

The above-mentioned water-based acrylic anaerobic adhesive has a problem in the adhesiveness of the adhesive film formed on the surface of the adherend. As an example, as described in JP-A-1-65182, a water dispersion type in which a peroxide microcapsule and a reducing agent are added to an aqueous emulsion of an acrylic monomer is disclosed. When using this as an adhesive to prevent the bolts and nuts from loosening, the adhesive film formed on the bolt surface may come off when tightening the nut, resulting in poor reliability. .

In order to solve such a problem, an alkoxysilane having an amino group is further added to the compounding component of the water-dispersible adhesive disclosed in the above-mentioned Japanese Patent Laid-Open No. 1-65182 to the adherend. Water-dispersed adhesive composition that forms an adhesive film with excellent adhesion (Japanese Patent Application No. 5-28
No. 5900) was proposed by the applicant, but a problem was newly found that the viscosity of this water-dispersed adhesive composition was likely to increase. For this reason, the dipping method coating requires lowering the viscosity of the adhesive, which is extremely difficult to cope with, and when the adherend is made of aluminum, the adhesiveness is insufficient. There was a flaw.

[0006] In view of the present situation, the present invention, for example,
A water-dispersible adhesive composition having high adhesion when applied to the surface of an adherend such as a bolt or a nut, and excellent storage stability, and a slack preventive using the water-dispersible adhesive composition The purpose of the present invention is to provide a highly effective bolt or nut.

[0007]

In order to achieve the above-mentioned object, the water-dispersible adhesive composition of the present invention comprises a monomer having an acryloyl group and / or a methacryloyl group by a protective colloid composed of an aqueous polymer. A solution obtained by emulsifying and dispersing in water is blended with 2-acrylamido-2-methylpropanesulfonate, microcapsules containing an organic peroxide, and a reducing agent that forms a redox with the organic peroxide. It is a feature.

A bolt or nut using the water-dispersible adhesive composition of the present invention is characterized in that a coating film is formed by applying the water-dispersible adhesive composition to the screw portion. Is.

The ratio of the acryloyl group- and / or methacryloyl group-containing monomer to the 2-acrylamido-2-methylpropanesulfonate in the water-dispersible adhesive composition of the present invention is such that the acryloyl group and / or methacryloyl group. It is preferable that the amount of the group-containing monomer is 50 to 98 parts by weight, and the amount of 2-acrylamido-2-methylpropanesulfonate is 2 to 50 parts by weight.

In the water-dispersible adhesive composition of the present invention, a monomer having an acryloyl group and / or a methacryloyl group, which is a main component of the water-dispersible adhesive composition [hereinafter, these have a (meth) acryloyl group It is called a monomer. ] Has 1 (meth) acryloyl group in the molecule.
A (meth) acrylate monomer having one or more is used.

Examples of the monomer having one (meth) acryloyl group in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate and 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, ethoxyethyl (meth)
Examples thereof include acrylate, n-butoxyethyl (meth) acrylate, sulfopropyl (meth) acrylate, sulfoethyl (meth) acrylate, acetoxyethyl (meth) acrylate and methylcarbinol (meth) acrylate.

Further, as the monomer having a plurality of (meth) acryloyl groups in the molecule, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-butanediol di (meth)
Polyester di (meth) acrylate obtained by dehydration condensation of acrylate, polybasic acid, polyol and (meth) acrylic acid, epoxidized bisphenol A di (meth) acrylate, ethylene glycol, diethylene glycol or triethylene glycol and epoxy Di (meth) acrylates such as di (meth) acrylate obtained from condensed bisphenol A and (meth) acrylic acid, diisocyanate, diisocyanate, glycol and polyurethane di (meth) acrylate obtained from hydroxyalkyl (meth) acrylate; Polyhydric alcohols such as glycerin, trimethylolpropane or pentaerythritol and (meth)
Examples thereof include monomers having three or more (meth) acryloyl groups obtained by the reaction of acrylic acid.

Of the above (meth) acrylate monomers,
Di (meth) acrylates of ethylene glycol, triethylene glycol or tetraethylene glycol; from ethylene glycol, diethylene glycol or triethylene glycol and epoxidized bisphenol A, in that an adhesive film having a large adhesive force and a long pot life can be obtained. A di (meth) acrylate obtained from the following condensate and (meth) acrylic acid is preferable.

The pot life in this invention is
A non-adhesive adhesive film is formed on the surface of an adherend with the water-dispersible adhesive composition of the present invention, and the adhesive-containing material thus obtained has an adhesive property for a period until actually used. It refers to the period of maintaining a certain state.

In the water-dispersible adhesive composition of the present invention, the organic peroxide is encapsulated in microcapsules, and the adhesive film formed from the organic peroxide also contains the (meth) acrylate monomer and the organic peroxide. The pot life is long because the objects are separated by the partition of the microcapsules.

The monomer having a (meth) acryloyl group in the present invention is used by emulsifying and dispersing it in water with a protective colloid composed of an aqueous polymer. The monomer having a (meth) acryloyl group is aqueous emulsified. A protective colloid composed of the above-mentioned aqueous polymer is used as a means for achieving this, whereby a non-adhesive adhesive film is obtained when an adhesive is applied to the surface of an adherend.

The preferred aqueous polymer used for the protective colloid contains 20 (meth) acrylic acid monomer units.
Acrylic acid ester-based copolymer, vinyl acetate-based copolymer or methyl vinyl ether-based copolymer, polyvinylpyrrolidone, polyvinyl alcohol having a saponification degree of 70 to 99 mol%, ethyl cellulose, hydroxypropyl cellulose, methoxy Hydroxypropyl cellulose, ethylene-maleic anhydride copolymer,
Examples thereof include water-soluble or water-soluble alcohol-soluble copolyamides, urea resins, melamine resins, and water-soluble or water-dispersible polymers such as block copolymers of polyethylene oxide and polypropylene oxide.

From the viewpoint that the resulting water-dispersible adhesive composition has a high adhesive strength and a long pot life, a more preferable aqueous polymer is soluble in polyvinyl alcohol having a saponification degree of 70 to 99 mol% or an aqueous solvent. It is particularly preferable to use them in combination. The number average molecular weight of the aqueous polymer is preferably 3,000 to 100,000.

In order to aqueous emulsify a monomer having a (meth) acryloyl group using the above aqueous polymer, an aqueous solution or dispersion of the aqueous polymer is stirred at a high speed, and the (meth) acryloyl group is added thereto. It is sufficient to gradually add the monomer having In the above-mentioned aqueous emulsification operation, a preferable usage ratio of the monomer having a (meth) acryloyl group, water and the aqueous polymer is 50 to 250 parts of water per 100 parts of the monomer having a (meth) acryloyl group, and The aqueous polymer is 0.5 to 30 parts, and the more preferable amount of the aqueous polymer is 2 to 20 parts.

The aqueous emulsion of the monomer having a (meth) acryloyl group thus obtained is usually 2
The viscosity at 0 rpm is 500 to 80,000 cps, and the diameter of the monomer oil droplets is 1 to 200 μm.

In the aqueous emulsification of the monomer having a (meth) acryloyl group, if desired, an alkyl sulfate ester salt, an alkylbenzene sulfonate salt, an alkylnaphthalene sulfonate salt, an alkylsulfosuccinate salt, a polyoxyethylene alkyl sulfate ester salt, or a polyoxyethylene alkyl sulfate salt Low molecular weight surfactants such as oxyethylene alkylaryl ethers and sorbitan fatty acid esters may be used.

The 2-acrylamido-2-methylpropanesulfonic acid salt used in the present invention is an alkali metal salt, alkaline earth metal salt or ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid. Examples of the alkali metal include lithium, sodium and potassium, and examples of the alkaline earth metal include calcium, magnesium, beryllium, barium and strontium.

These 2-acrylamido-2-methylpropanesulfonic acid salts are used together with the above-mentioned monomer having a (meth) acryloyl group when the water-dispersible adhesive composition of the present invention exhibits an adhesive function. Polymerize. All of the 2-acrylamido-2-methylpropane sulfonates are easily dissolved or dispersed in water, and can be easily compounded in the water-dispersible adhesive composition of the present invention, and a (meth) acryloyl group is included. It is also excellent in copolymerizability with its own monomers. In the present invention, by using such 2-acrylamido-2-methylpropane sulfonate together with the monomer having a (meth) acryloyl group, the viscosity increase of the adhesive composition can be suppressed. On the other hand, as is clear from the comparative example described below, 2-acrylamide-2-
When methyl propane sulfonic acid was blended as it was, the storage stability of the aqueous solution of the adhesive composition was adversely affected, which was the object. In addition, this 2-acrylamido-2-methylpropane sulfonate combined with the monomer having the (meth) acryloyl group is
Sometimes referred to as all monomers in this invention.

In all the monomers in the present invention, 2-
The preferable ratio of acrylamido-2-methylpropanesulfonate is 2 to 50% by weight, more preferably 5 to 20% by weight. When the amount of 2-acrylamido-2-methylpropane sulfonate is less than 2% by weight, it is difficult to effectively suppress the increase in viscosity of the adhesive composition aqueous solution, while it exceeds 50% by weight. If so, the adhesive property is likely to be deteriorated.

The preferred organic peroxide used in the present invention is cumene hydroperoxide, t
-Butyl hydroperoxide, hydroperoxide such as 1,1,3,3-tetramethylbutyl hydroperoxide, ketone peroxide such as methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, 1,3-bis ( dialkyl peroxide such as t-butylperoxyisopropyl) benzene or 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane,
Peroxyesters such as t-butyl diperadipate and diacyl peroxides such as benzoyl peroxide, parachlorobenzoyl peroxide, m-toluoyl peroxide and the like. The use of benzoyl peroxide or m-toluoyl peroxide is more preferable because it provides a highly redox-reactive and highly adhesive adhesive.

The amount of such organic peroxide used is 0.2 to 10 parts, preferably 0.5 to 4 per 100 parts of all monomers.
It is a department. If the amount used is less than 0.2 parts, the adhesive performance will not be sufficiently exhibited, while if it exceeds 10 parts, the pot life of the adhesive composition will be significantly reduced.

The organic peroxide is added as a microcapsule body, and the interfacial polymerization method is preferable as the microencapsulation method. Specifically, a powdery organic peroxide is dispersed in a prepolymer aqueous solution obtained by reacting urea and formalin or melamine and formalin, and then the pH of the aqueous solution is lowered to 2-3 and the temperature is set to 40. When maintained at -50 ° C, the polycondensation of the above prepolymer proceeds with the powder of the organic peroxide as the nucleus to obtain microcapsules insolubilized in water. The particle size of the capsule is preferably 5 to 100 μm, and the amount of peroxide contained in the capsule is preferably 5 to 30% by weight based on the weight of the capsule.

As the reducing agent which forms a redox with the organic peroxide, a usual redox type radical polymerization initiator can be used, and specifically, ethylenethiourea, dimethyl-p-toluidine, p-tolyldiethanolamine and o. -Sulfobenzoic acid imide and the like can be preferably used. The amount of the reducing agent is 0.1 to 100 parts of all the monomers.
5 parts is necessary, and preferably 0.2 to 2 parts. If the amount of the reducing agent is less than 0.1 part per 100 parts of all the monomers, the adhesion rate at room temperature is significantly reduced, and if it exceeds 5 parts, the adhesive composition causes an increase in viscosity during storage. easy. Furthermore, the ratio of the reducing agent to the organic peroxide is preferably 10 to 500 parts per 100 parts of the organic peroxide.

In the present invention, in order to improve the performance of the resulting water-dispersed adhesive composition, for example, to maintain a long pot life, copper chlorophyll sodium,
Ethylenediaminetetraacetic acid tetrasodium salt, potassium titanate, hydroquinone, methylhydroquinone, 2,4
-Dinitroanisole or 2,6-ditertiarybutyl-p-cresol can be added to the composition. Further, silica fine powder, titanium oxide fine powder, inorganic hollow fine particles, or the like can be used as a tightening torque adjusting agent for bolts and nuts.

The water-dispersible adhesive composition of the present invention is uniformly applied to the surface of an adherend by a roll transfer method, a dip method, or hand coating, and then heated to a temperature of 60 by infrared rays or high frequency. It can be dried by heating to -100 ° C to form an adhesive film. When this water-dispersed adhesive composition is used for fixing bolts and nuts, for example, M10 bolts will be described. The adhesive is applied in a width of 15 mm by a weight of 50 to 150 mg after drying and a temperature of 80 ° C. It may be dried for 20 to 30 minutes.

[0031]

In the water-dispersible adhesive composition of the present invention, 2-acrylamido-2-methylpropanesulfonate is added to the monomer having a (meth) acryloyl group which constitutes the main component of the adhesive composition. As a result, it is possible to suppress an increase in the viscosity of the aqueous solution of the adhesive composition and exhibit excellent adhesive performance. In addition, a bolt or nut having such a water-dispersed adhesive composition applied to a screw portion to form a coating film has the above-mentioned coating film peeled off when tightened due to excellent adhesion of the water-dispersed adhesive composition. Never.

[0032]

EXAMPLES The water-dispersible adhesive composition of the present invention will be specifically described below with reference to Examples and Comparative Examples. Incidentally, the evaluation of the adhesive performance of the adhesive composition of each example to the screw,
It depends on the following test method. [Coating of adhesive composition on screw] 10 mm diameter, 40 length
m (two kinds of yellow chromate treated screw and hard aluminum screw are used) so that 0.2 g of the water-dispersible adhesive composition is evenly applied so that the groove is filled, and then the temperature of 80
The adhesive film was formed on the surface of the screw by drying at 20 ° C. for 20 minutes.

[Adhesiveness test] The screw provided with the adhesive film is tightened with a torque of 300 kgf · cm to tighten the nut, and it is observed whether the adhesive film comes off at that time. The breaking torque after standing for 24 hours was measured. The measurement was performed on 5 test pieces, and the average value of the obtained data of 5 points was shown as the measurement value. In addition,
The breaking torque measured under the above conditions for the screw without adhesive applied, that is, the blank value is 280 kgf · c
It was m.

[Pot Life Test] The above-mentioned coated screw was left for 24 hours at a temperature of 40 ° C. and a relative humidity of 95%, and then the above-mentioned adhesion test was conducted.

Example 1 (1) Preparation of (meth) acrylate Monomer Emulsion 860 g of pure water and Gohsenol GM were placed in a 2 liter beaker.
-14 [partially saponified polyvinyl alcohol having a saponification degree of 86 mol% and an average polymerization degree of 1400, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] 100 g, copper chlorophyll 2 g and o-sulfobenzoic acid imide 5 g were used as an aqueous solution. While stirring at 650 rpm with a propeller-type stirring blade, NK B
PE-200 [2,2 bis (4- (methacryloxydiethoxy) phenyl) propane, Shin-Nakamura Chemical Co., Ltd.
1000 g, dimethyl-p-toluidine 5 g and AQ-nylon A-90 [dimethylamino-substituted nylon, manufactured by Toray Industries, Inc.] 20 g were charged, and stirring was continued for 2 hours to obtain an aqueous emulsion of a (meth) acrylate monomer. Obtained. This emulsion had emulsified particles having a particle size of 2 to 6 μm and had a viscosity of 8000 cps at 6 rpm of a B type viscometer.

(2) Production of encapsulated organic peroxide A 1-liter flask was charged with 350 g of a 37% by weight aqueous formalin solution, 131 g of urea and 1.7 g of triethanolamine, and a propeller-type stirring was conducted at a temperature of 70 ° C. The reaction was performed with stirring using a blade at 300 rpm for 2 hours, whereby the pH was 8.1 and the solution viscosity was 8.3 cp.
An aqueous prepolymer solution of s (measured with a B-type viscometer at 20 rpm) (35% by weight of dimethylol body) was obtained. Then, 257 g of the above prepolymer aqueous solution and 525 g of pure water
Place in a 2 liter beaker and add 1N sulfuric acid to pH.
After adjusting to 2.6, 12.8 g of fine powder of benzoyl peroxide (average particle size 20 μm) was added and the temperature was adjusted to 40
The temperature was raised to 0 ° C., and the mixture was reacted for 6 hours under stirring at 9000 rpm with a homogenizer. Thereafter, the reaction was further continued for 14 hours under stirring at 300 rpm using a propeller type stirring blade. The resulting slurry was neutralized with a 1N aqueous solution of sodium hydroxide and washed with pure water and methanol to obtain a solid content at a temperature of 40.
After drying at ℃, 85.3g of microcapsules were obtained. The particle size of the obtained microcapsules is 5 to 30 μm,
The content ratio of benzoyl peroxide in the inclusion was 15% by weight.

(3) Preparation of Adhesive Composition The acrylate monomer emulsion obtained in (1) above, the encapsulated organic peroxide obtained in (2) above, and 2-acrylamido-2-methyl. 100 g of each sodium salt of propanesulfonic acid salt was placed in a 5 liter beaker and stirred at 2000 rpm for 5 minutes using a lab mixer to obtain a water-dispersed adhesive composition. The storage stability of the water-dispersed adhesive composition was evaluated by the viscosity after the temperature was maintained at 40 ° C. for 1 week. In this example, the liquid viscosity after the heating treatment was 2000 cps. Further, the adhesive properties of the obtained water-dispersed adhesive composition were evaluated by the above-mentioned test method.

The amount and type of 2-acrylamido-2-methylpropane sulfonate used in Examples 2 to 7, Comparative Examples 1 and 2 were changed, or 2-acrylamido-2-methylpropane sulfonic acid was used. Water-dispersed adhesive compositions of Examples 2 to 7 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1 except that no salt was used. After the storage stability test on the water-dispersible adhesive compositions of Examples 2 to 7 (temperature 40 ° C., 1 week)
The liquid viscosity of each was 2500 cps or less. On the other hand, the adhesive compositions of Comparative Examples 1 and 2 had a temperature of 4
Liquid viscosity of 10,000 cps when maintained at 0 ° C for 24 hours
Over. The adhesive properties of these water-dispersed adhesive compositions were evaluated in the same manner as in Example 1. The results are shown in Table 1 together with the results of Example 1. In the table, the salt is 2-acrylamido-2-methylpropanesulfonic acid salt and the acid is 2-acrylamido-2-methylpropanesulfonic acid.

[0039]

[Table 1]

[0040]

Since the water-dispersible adhesive composition of the present invention contains 2-acrylamido-2-methylpropanesulfonate in the composition, the composition has a (meth) acryloyl group-containing monomer. The copolymerization of is very good, and when applied to the surface of the adherend, the resulting adhesive film has excellent adhesion to the adherend and can maintain long-term pot life and storage stability. is there. Further, the bolt or nut obtained by applying the water-dispersible adhesive composition of the present invention to the threaded portion has excellent adhesiveness between the adhesive film and the threaded portion, so that The adhesive film does not peel off when tightened, and high adhesive strength is obtained.

Claims (3)

[Claims] 1. A liquid in which a monomer having an acryloyl group and / or a methacryloyl group is emulsified and dispersed in water with a protective colloid composed of an aqueous polymer, and then added to 2-acrylamido-2-methylpropanesulfonate and an organic peroxide. A water-dispersible adhesive composition comprising a microcapsule containing a substance and a reducing agent which forms a redox with the organic peroxide. 2. A monomer having an acryloyl group and / or a methacryloyl group and 2-acrylamido-2-
The ratio of methyl propane sulfonate to the monomer having an acryloyl group and / or methacryloyl group is 5
The water-dispersible adhesive composition according to claim 1, wherein 0 to 98 parts by weight and 2 to 50 parts by weight of 2-acrylamido-2-methylpropanesulfonate are contained. 3. A bolt or nut characterized in that a coating film is formed by applying the water-dispersible adhesive composition according to claim 1 or 2 to a screw portion.