JPH02308876A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of a specific monomer, a specific polymer, an encapsulated organic peroxide and a specific compound, useful as a thread locking adhesive and having excellent storage stability before the collapse of the capsule. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of a monomer having acryloyl or methacryloyl group and emulsified in water [produced by slowly adding (meth)acrylate monomer to an aqueous solution of a surfactant under vigorous agitation] with (B) 0.5-30 pts.wt. of a film-forming polymer emulsified or dispersed in water (preferably polyvinyl alcohol, etc., having a saponification degree of 30-98mol%), (C) 0.2-10 pts.wt. of an encapsulated organic peroxide (preferably containing 10-60wt.% of benzoyl peroxide, etc.), (D) 0.02-5 pts.wt. of a compound of formula (R1 is H or 1-5C alkyl: R2 and R3 are 1-5C alkyl having OH group) and (E) dimethylaniline, talc. etc.

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 particularly high initial adhesion speed, is room temperature curing, and has a short pot life. The present invention relates to an anaerobic adhesive that has long coating properties and is made into an aqueous composition.

Since this adhesive composition can be finished to a dry touch, it is suitable for use in fields where it is applied in advance to the surface of an adherend to form a film of the adhesive composition, such as as an adhesive for screw loosening. It is something.

[Conventional technology]

Conventionally, rapidly curing one-component room-temperature curing adhesives mainly consist of monomers having acryloyl groups and/or methacryloyl groups (hereinafter referred to as "(meth)acrylate monomers"). Anaerobic curable compositions have been used which contain curing accelerators such as peroxides or reducing agents as needed.

[Problem to be solved by the invention]

Conventional anaerobic curable compositions are compositions that remain oily when in contact with air or oxygen under low temperature, low humidity conditions, and rapidly harden when cut off from air or oxygen.

Therefore, before curing, there is a risk of chemical damage due to curing accelerators such as oil-based (meth)acrylate monomers, peroxides, or amines, and poor coating due to selectivity of the adherend or inappropriate viscosity. It had the following drawbacks.

Furthermore, when the composition is stored under conditions of high temperature and high humidity,
It has the disadvantage that the adhesion ability, especially the initial adhesion speed, is significantly reduced. Therefore, in applications where the adhesive composition is applied to the surface of the adherend in advance to form a film of the adhesive composition, so-called pre-coating is not recommended. The use of such compositions has been severely restricted due to the risk of the product being stored in high temperature and high humidity locations.

(B) Structure of the Invention [Means for Solving the Problems] The present invention is directed to the formation of a film formed by emulsifying or dispersing a monomer having an acryloyl group and/or a methacryloyl group in water and emulsifying it in water. Polymer with the ability 0.5
~30 parts by weight, 0.2 parts by weight of encapsulated organic peroxide
10 parts by weight, and 0.02 to 5 parts by weight of a compound having the structure shown below (hereinafter referred to as "aniline derivative").

Here, R1 is hydrogen or an alkyl group having 1 to 5 carbon atoms, R
2 and R3 represent an alkyl group having 1 to 5 carbon atoms and having a hydroxyl group.

[(Meth)acrylate mer emulsified in water] The (meth)acrylate rt>mer used in the present invention is methyl (meth)acrylate.

Ethyl (meth)acrylate-1-, 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 3 n-butoxyethyl (meth)acrylate, sulfopropyl (meth)acrylate, 2-
Mono(meth)acrylates such as hydroxyethyl acryloyl phosphite, acetoxyethyl (meth)acrylate and methylcarpitol (meth)acrylate;
Ethylene glycol di(meth)acrylate Triethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate Polyester di(meth)acrylate obtained by dehydration condensation of polybasic acid, polyol, and (meth)acrylic acid to form a polyester. (Meth)acrylate, epoxidized bisphenol A di(meth)acrylate, ethylene glycol, di(meth)acrylate, diisocyanate, glycol obtained from a condensate consisting of diethylene glycol or triethylene glycol and epoxidized bisphenol A and (meth)acrylic acid. di(meth)acrylates such as polyurethane di(meth)acrylates obtained from Examples include compounds containing more than one.

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.

The method of emulsifying the (meth)acrylate monomer in the present invention is as follows.

When a (meth)acrylate monomer is gradually added to an aqueous surfactant solution under vigorous stirring, the monomer is easily emulsified.

At this time, an adhesive composition obtained by adding a water-soluble polymer and/or a water-dispersible polymer having film-forming ability at the same time as or after emulsifying the (meth)acrylate monomer. The surface after coating is covered with a resin film,
The coated surface has a so-called dry touch, making it easier and safer to handle.

In addition, when using a water-soluble or water-dispersible polymer that has a film-forming ability and can emulsify a (meth)acrylate monomer as described below, the desired product can be obtained in a single step. Therefore, it is preferable.

As surfactants, fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfate ester salts, polyoxyethylene alkylaryl ethers, sorbitan fatty acid esters, glycerin Examples include fatty acid esters and polyoxyethylene alkylamines.

In addition, examples of polymers that have film-forming ability but have a weak surface-active effect include highly hydrophobic emulsion polymers such as urethane resins, chloroprene polymers, butadiene-acrylonitrile copolymers, and styrene-butadiene copolymers. .

Next, a polymer having film-forming ability and capable of emulsifying a (meth)acrylate monomer in water has surface activity and a number average molecular weight of 3000 to 1 in an aqueous solution or water dispersion state.
00,000, for example, acrylic acid ester resins, vinyl acetate copolymers or methyl vinyl ether copolymers, polyvinyl pyrrolidone, which have 30% by weight or more of (meth)acrylic acid units as constituent units of the copolymer.
polyvinyl alcohol with a saponification degree of 30 to 98 mol%,
Ethyl cellulose, hydroxypropyl cellulose, methoxyhydroxypropyl cellulose, ethylene-maleic anhydride copolymer, nylon polymer soluble in water or a mixed solvent of water and alcohol, urea resin, melamine resin, or polyethylene oxide and polypropylene Examples include water-soluble polymers such as block copolymers with oxides; water-dispersible polymers such as acrylic acid ester resin emulsions.

Among these polymers, when polyvinyl alcohol with a degree of saponification of 30 to 98 mol%, a nylon polymer that is soluble in water or a mixed solvent of water and alcohol, or a mixture thereof is used, the resulting adhesive The agent composition is preferable because it forms a good resin film on the surface after coating.

In the emulsification of (meth)acrylate monomers, (meth)
An adhesive composition containing 0.5 to 30 parts by weight of a water-soluble or water-dispersible polymer having film-forming ability per 100 parts by weight of acrylate monomer has a good resin film on the surface after application. form. More preferably, it is 2 to 20 parts by weight.

Further, it is preferable to use water as a base in a ratio of 50 to 250 parts by weight to 100 parts by weight of the (meth)acrylate monomer, and the obtained emulsion has a viscosity of 3,000 to 80,000 cps at 20 rpm using a B-type viscometer. It is preferable that the diameter of the oil droplets of the emulsified (meth)acrylate monomer is 1 to 200 μm.

[Encapsulated organic peroxide]

Powdered or liquid organic peroxides can be easily encapsulated using coacervation or surfactant methods. By encapsulating, the pot life becomes good and a composition that is even more excellent as a one-component adhesive composition can be obtained.

When using the coacervation method, a method of applying a gelatin-gum arabic film is mentioned, but in order to improve water resistance, after coacervation, a prepolymer of urea-formalin-melamine is present and interfacial polymerization is performed. A two-stage encapsulation method in which the steps are sequentially performed is preferred.

In the case of a finely powdered organic peroxide, it is preferable to adopt an interfacial polymerization method. After suspending the substance, the pH is lowered to 2 to 3 and the reaction temperature is maintained at 35 to 45 ° C, and the resulting polymer is encapsulated in peroxide powder by methylenation reaction, This is preferable because the produced capsules have excellent water resistance and oil resistance.

The particle size of the capsule is preferably 10 to 100 μm in view of the stability when mixed with the (meth)acrylate monomer emulsified in water and the necessity of destroying the capsule during adhesion work.
Furthermore, the content of peroxide in the capsule is 10-60
Weight percent is preferred.

As the organic peroxide used in the present invention, hydroperoxide, ketone peroxide, dialkyl peroxide, peroxy ester, diacyl peroxide, etc. can be used, but in particular penzoyl peroxide or m-toluoyl peroxide can be used. It is preferable to use an organic peroxide with strong redox reactivity such as Side because the adhesive performance will be improved.

The amount of the encapsulated organic peroxide used is 0.2 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the (meth)acrylate monomer.

If the amount is less than 0.2 parts by weight, the adhesion performance will not be sufficiently exhibited, while if it exceeds 10 parts by weight, more than the appropriate amount may be mixed in as foreign matter and the adhesive performance may deteriorate.

[Aniline derivative]

The compound can be used by dissolving it in an emulsion of (meth)acrylate monomer, specifically (meth)acrylate monomer.
When emulsifying the acrylate monomer, it can be easily mixed by adding it at the same time.

Specific examples of the compound include N,N-bis-[2-hydroxyethylcyaniline, N.

N-bis-[2-hydroxypropyltoaniline, N
, N-bis-[2-hydroxyethyl]-〇-toluidine, N,N-bis-[2-hydroxyethyl-m-toluidine, N,N-bis-[4,5-dihydroxypentyl-m-toluidine, N,N-bis-[2-hydroxyethyl]-p-toluidine or N,N-bis-
[2-Hydroxypropyl:]-p-)luidine, etc. are mentioned.

Among these, N,N-bis-[2-hydroxyethyl)
-Il+-toluidine and N,N-bis-[2-hydroxypropyl)-p-toluidine are preferred because they are industrially easily available, prolong the pot life of the adhesive composition, and have a high adhesion speed during adhesion. .

The amount of the compound used is (meth)acrylate monomer 1
0.02 to 5 parts by weight are required for 00 parts by weight,
Preferably it is 0.2 to 2 parts by weight.

When the amount is less than 0.02 parts by weight, the life of the adhesive performance before the organic peroxide capsule of the adhesive composition of the present invention is destroyed is short, and the adhesive speed decreases especially when stored in a high temperature and high humidity atmosphere. On the other hand, if 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, which are inappropriate.

[Other substances that may be incorporated into the adhesive composition of the present invention] For the purpose of improving the properties of the adhesive composition, for example, to promote redox reactions, dimethylaniline, N,N-dimethylaniline, dimethyl-p -Toluidine, 0-sulfobenzoic acid imide, sodium copper chlorophyllin, copper phthalocyanine, etc. are used.

Also, to impart thixotropic properties, talc, silica, alumina or calcium carbonate; to maintain a long pot life, hydroquinone, methylhydroquinone, 2,4-dinitroanisole or 2,6-ditertiary-butyl p-cresol etc. can be added.

[Effect]

The adhesive composition of the present invention maintains an aqueous system when applied to an adherend, and furthermore, after drying, the peroxide, which is the main component of the catalyst system, is encapsulated, so that (meth)acrylate single No polymer curing reaction occurs, an oil layer is formed on the surface of the adherend, and a dry-touch film is formed on the surface due to the pre-existing polymer.

On the other hand, during adhesion work, by simply rubbing or applying pressure to the surface of the adherend, the capsules are destroyed, the peroxide comes into contact with the (meth)acrylate monomer, and a curing reaction is initiated to improve the adhesion. is demonstrated.

At this time, the presence of the aniline derivative causes a redox reaction during the curing reaction, increasing the initial adhesion speed.

In addition, the storage stability of the adhesive composition before the capsules are destroyed is improved, and the adhesive ability is less likely to deteriorate even if the adhesive composition is stored for a long period of time, especially under high temperature and high humidity conditions. Become.

The reason for this is that compared to conventional reducing agents, aniline derivatives have a higher vapor pressure and have an OH group in their structure, so they do not adhere to the surface of the pre-existing polymer film at the molecular layer level. It is thought that this is because the film prevents the aniline derivative from being oxidized and evaporating into the outside world.

[Examples and comparative examples]

The present invention will be explained in more detail by giving Examples and Comparative Examples below.

In addition, as an evaluation method, the adhesion performance to screws was performed using the following test method.

(Application of adhesive composition to screws) 0.2 g of the aqueous adhesive composition was evenly applied to a yellow chromate screw of 8 diameters and 40 mm length so that the grooves were filled, and then heated at 60°C. It was dried for 30 minutes to form a tack-free resin film on the surface, and a screw type screw coated with the adhesive composition was obtained.

(Adhesive performance and other evaluation tests) (a) Adhesiveness test O Tighten the above-mentioned coated screw with a torque of 200 kg/cm, and apply the starting return torque after leaving it at 23°C for 2 hours and after leaving it for 24 hours. It was measured.

(b) Adhesive performance pot life test The coated screws were left at 40°C and 80% relative humidity for 30 days, then tightened with a torque of 200 kg/cm, and left at 23°C for 2 hours. The starting return torque was measured.

Example 1 (Production of encapsulated organic peroxide) In order to encapsulate benzoyl peroxide with a urea-formalin resin, a urea-formalin prepolymer was first synthesized by the following method.

1! In a flask, add formalin aqueous solution 3 with a concentration of 37% by weight.
50g, urea 131g and triethanolamine 1.7
g and stirred at 70°C for 2 hours at 300 rpm using a propeller-type stirrer to react until pH 8.1.
and the viscosity at 2Orpm measured by a B-type viscometer is 3.3 c.
A prepolymer with p s was obtained.

Next, 2! at room temperature! Charge 257 g of the above prepolymer aqueous solution and 525 g of pure water in a beaker, and add 15 cc of IN sulfuric acid aqueous solution while stirring at 500 rpm with a homogenizer.
The pH was adjusted to 2.6 by adding 8 times. Benzyl mer oxide fine powder (average particle size 20 μm) 12
．． After adding 8g of water and raising the temperature to 40°C and reacting for 6 hours, 300g of pure water was added and the stirring number was increased to 200Orp.
The reaction was continued for 14 hours.

The resulting slurry was neutralized with an IN aqueous solution of caustic soda,
As a result of washing with pure water and methanol and drying on a tray at 40°C, the content of the urea-formalin resin film was 79.3% by weight, and a polynuclear Hensil with an average particle size of 40 μm was obtained. A capsule of peroxide was obtained.

(Preparation of (meth)acrylate monomer emulsion) 2I! ,
In a beaker, 860 g of pure water, 100 g of 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 ■)
was prepared and made into an aqueous solution. Then use a homogenizer for 20
Under stirring at 0 rpm, NK BPE-200 (2,
2bis[4-(methacryloxyjethoxy)phenyl]propane, manufactured by Shin-Nakamura Chemical Industry ■) 1000g, N',
N-bis-[2-hydroxyethyltoaniline 5g
, and 20 g of AQ-nylon A-90 (water-soluble nylon, manufactured by Toshi Corporation) were added and stirred for 2 hours to obtain an aqueous emulsion.

(Preparation of adhesive composition) To the entire amount of the (meth)acrylate monomer emulsion obtained above, 96.6 g of encapsulated organic peroxide (containing 20 g as benzoyl peroxide) was added,
Stir with a homogenizer at 200 rpm for 5 minutes, and have a viscosity of 12,000 cps with a B-type viscometer at 2 rpm.
An aqueous adhesive composition having a solid content concentration of 61.5% by weight was obtained.

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

Examples 2 to 8, Comparative Example 1 In Example 1, the types and amounts of the (meth)acrylate monomer, organic peroxide, aniline derivative, and film-forming polymer were changed as shown in Table 1. Table 1 shows the test results obtained when the test was carried out in exactly the same manner as in Example 1, except for the other conditions.

(c) Effects of the Invention The adhesive composition of the present invention retains an aqueous system when applied to an adherend, so it is easy to work with and is safe to handle. Furthermore, after drying, the peroxide, which is the main component of the catalyst system, is encapsulated, so the (meth)acrylate monomer does not undergo a curing reaction, and an oil layer is formed on the surface of the adherend, and the surface is pre-existing. Since the film is formed with a dry-touch polymer, it is suitable for storing and transporting adherends.

Furthermore, the adhesive composition of the present invention has a long pot life even when stored under harsh conditions of high temperature and high humidity, and has a high initial adhesion speed.

The adhesive composition of the present invention is suitable for use in fields where it is precoated on a metal material to form a film of the adhesive composition, for example, as an adhesive for locking screws.

Claims (1)

[Claims] 1. 100 parts by weight of a monomer having an acryloyl group and/or methacryloyl group emulsified in water, 0.5 to 30 parts by weight of a polymer having film-forming ability emulsified or dispersed in water.
parts by weight, 0.2 to 10 parts by weight of encapsulated organic peroxide, and 0.02 to 10 parts by weight of a compound having the structure shown below.
An adhesive composition consisting of 5 parts by weight. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Here, R_1 is hydrogen or an alkyl group having 1 to 5 carbon atoms,
R_2 and R_3 represent an alkyl group having 1 to 5 carbon atoms and having a hydroxyl group.