JPH08143823A - 2-cyanoacrylate-based instantaneous adhesive - Google Patents

Abstract

PURPOSE: To obtain the subject adhesive formulated with an NBR-based polymer, suppressed in its setting time delay, having a moderately raised viscosity, capable of exhibiting markedly high peel strength and heat-resistant tensile/shear strength in bonding, and also excellent in preservability. CONSTITUTION: This adhesive is a copolymer obtained by formulating (A) 2- cyanoacrylate with (B) a low-metal NBR-based copolymer with the ash content of <=500ppm and the total of Na and K ion contents of <=30ppm, a copolymer made up of (b1) 15-50wt.% of acrylonitrile unit, (b2) 40-85wt.% of butadiene and/or isoprene unit, (b3) 0-10 (esp. 0.5-10)mol% of a carboxyl-bearing monomer, and (b4) 0-30wt.% of a monomer component copolymerizable with other above monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 2-cyanoacrylate instant adhesive having a significantly improved peeling strength and a remarkably excellent tensile shear strength even after being subjected to a heat history at a high temperature. is there.

[0002]

2. Description of the Related Art 2-Cyanoacrylate instant adhesives have a large adhesive force to most materials regardless of wood, plastics, and metals, and can be applied to adhesion between different kinds of materials. It has the feature that it is possible.

When a 2-cyanoacrylate instant adhesive is used for adhesion, it may be brought to a high temperature condition depending on the use environment, but in general, when heat history is passed, the tensile shear strength decreases and unexpected troubles occur. May occur. Therefore, it is necessary to use a heat-resistant grade of 2-cyanoacrylate instant adhesive when adhering parts of automobiles where the temperature inside the car may rise or adhering parts located near the high temperature source of home appliances. Becomes

Even in applications that are not intended to be used under high temperature conditions, the peel strength is naturally limited by the bonding with 2-cyanoacrylate instant adhesives, and therefore there is a market demand to increase the peel strength. strong.
There is also a strong demand for expanding the choice of applicable adherends by increasing the viscosity of the adhesive.

Polymers have been blended with 2-cyanoacrylate in order to meet the demands of increasing the peel strength and the tensile shear strength and increasing the viscosity. As one of them, 2-cyanoacrylate is blended with nitrile rubber ( NB
R) or carboxy-modified NBR has been proposed as an instant adhesive.

That is, JP-B-43-29477 discloses that 2-cyanoacrylate has (a) a reaction product of a polyester or polyether and a polyisocyanate and has no reactive isocyanate group.
2-Cyanoacrylate instant adhesive containing at least one of (b) an acrylonitrile-butadiene copolymer (NBR) having a carboxyl group and (c) an elastic body containing a copolymer of acrylic ester as a main component. It is shown. The amount of the compounding agent selected from (a), (b) or (c) is 1 to 25% by weight (preferably 2 to 2) based on the whole system.
0% by weight), the purpose of adding the compounding agent is
An object of the present invention is to provide an adhesive which is instantly bonded, has excellent adhesive strength, and has an appropriate viscosity. Out of compounding agents
The carboxy-modified NBR of (b) used in the examples is "Hiker 1072" manufactured by Nippon Zeon Co., Ltd.
And the addition amount is ethyl 2-cyanoacrylate 9
It is 3 parts by weight with respect to 0 parts by weight (or 4 parts by weight with respect to 87 parts by weight of ethyl 2-cyanoacrylate).

In the description of the prior art in Japanese Patent Publication No. 43-29477, there is conventionally known a mixture of 2-cyanoacrylate and acrylonitrile-butadiene copolymer (NBR). It is described that NBR does not exhibit satisfactory properties in terms of adhesive strength and compatibility.

[0008]

As described above, it is necessary to use a heat-resistant grade 2-cyanoacrylate type instant adhesive when adhering parts for automobiles and instant adhering parts for home appliances. However, the commercially available heat-resistant grade 2-cyanoacrylate instant adhesive has a certain amount of heat-resistant tensile shear strength, but when it undergoes a severe heat history, the tensile shear strength decreases and the adhesion reliability is impaired. The current situation is that they do not always meet the intended purpose.

To increase the peel strength and viscosity, 2
The instant adhesive of JP-B-43-29477, which is a mixture of cyanoacrylate and carboxy-modified NBR, does not have the expected effect of improving the peel strength, and can sufficiently meet the recent demands for higher sophistication. It's gone. The carboxy-modified N described in the examples of this publication
The instant adhesive containing BR has a problem that the tensile shear strength is remarkably lowered when it undergoes a heat history at high temperature.

According to the research conducted by the present inventors, one of the reasons why the peel strength and the tensile shear strength of the instant adhesive obtained by blending 2-cyanoacrylate with NBR or carboxy-modified NBR is insufficient is NBR or carboxy-modified NBR. It is considered that there is a limit to the solubility of the compound in 2-cyanoacrylate. In the description of the text of JP-B-43-29477, it is stated that the additive is mixed in an amount of 1 to 25% by weight with respect to the whole system. As used in the examples, the solubility limit is around 4% by weight.

The reason why the heat-resistant tensile shear strength of the instant adhesive obtained by blending 2-cyanoacrylate with NBR or carboxy-modified NBR is remarkably lowered is that conventional NBR or carboxy-modified NBR is obtained by a usual emulsion polymerization method. Therefore, it is considered that the alkali metal soap used in the emulsion polymerization and the metal salt used in solidifying the polymer from the emulsion polymer have a negative effect on the heat-resistant tensile shear strength.

Under the circumstances described above, the present invention provides N
A 2-cyanoacrylate instant adhesive compounded with a BR polymer, which has a retarded set time, has an appropriately increased viscosity, and has excellent peel strength and heat-resistant tensile shear strength upon adhesion. Can be given,
Furthermore, it is an object of the present invention to provide a 2-cyanoacrylate instant adhesive having good storage stability.

[0013]

In the 2-cyanoacrylate instant adhesive of the present invention, the monomer units constituting the copolymer are acrylonitrile (b1) units 15 to 50% by weight,
Butadiene and / or isoprene (b2) units 40-8
5% by weight, carboxyl group-containing monomer (b3) unit 0 to 1
A copolymer comprising 0 mol% and 0 to 30% by weight of another monomer (b4) unit copolymerizable with these monomers, wherein the ash content in the copolymer is 500 ppm or less, Na
A low metal content NBR copolymer (B) having a total ion and K ion content of 30 ppm or less is blended with 2-cyanoacrylate (A).

In this case, a low metal content NBR copolymer
The ratio of the carboxyl group-containing monomer (b3) unit in (B) is
0.5 to 10 mol%, that is, the low metal content NBR-based copolymer (B) is a low metal content carboxy-modified N
A BR-based copolymer is particularly preferable.

The present invention will be described in detail below.

The 2-cyanoacrylate (A) used in the present invention includes alkyl 2-cyanoacrylate (methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, isopropyl 2-cyanoacrylate,
n-propyl 2-cyanoacrylate, isobutyl 2-
Cyanoacrylate, n-butyl 2-cyanoacrylate, etc.), alkoxyethyl 2-cyanoacrylate (methoxyethyl 2-cyanoacrylate, ethoxyethyl 2-cyanoacrylate, etc.), halogenated alkyl 2-
Examples thereof include various 2-cyanoacrylates such as cyanoacrylate (2-chloroethyl 2-cyanoacrylate etc.), alicyclic alkyl 2-cyanoacrylate (cyclohexyl 2-cyanoacrylate etc.) and allyl 2-cyanoacrylate.

In the present invention, the above-mentioned 2-cyanoacrylate (A) contains the low metal content N described in detail below.
The BR copolymer (B) is blended.

This low metal content NBR copolymer (B)
Can be obtained by copolymerizing acrylonitrile (b1) with butadiene and / or isoprene (b2), and it is also preferable to copolymerize a carboxyl group-containing monomer (b3). Further, it may be a copolymer of another monomer (b4) copolymerizable with these monomers.

Among the above-mentioned monomer components, the carboxyl group-containing monomer (b3) includes (meth) acrylic acid, crotonic acid, cinnamic acid, itaconic acid, itaconic anhydride, maleic acid, maleic anhydride, fumaric acid, and citracone. Acids, α, β-ethylenically unsaturated carboxylic acids such as mesaconic acid; itaconic acid, maleic acid, fumaric acid, citraconic acid, monomethyl esters of α, β-ethylenically unsaturated polycarboxylic acids such as mesaconic acid, mono Free carboxyl group-containing esters such as ethyl ester and monopropyl ester;
Release of unsaturated monocarboxylic acid hydroxyalkyl such as monoester of 2-hydroxyethyl (meth) acrylate and succinic acid, monoester of (meth) acrylic acid 2-hydroxyethyl and phthalic acid and polyvalent carboxylic acid Carboxyl group-containing ester; and the like. Among these, (meth) acrylic acid, crotonic acid, cinnamic acid,
Particularly preferred are itaconic acid, maleic acid, monoesters of 2-hydroxyethyl (meth) acrylate and succinic acid, and monoesters of 2-hydroxyethyl (meth) acrylate and phthalic acid. These carboxyl group-containing monomers (b3) can be used alone or in admixture of two or more.

These monomers (acrylonitrile (b
As the other monomer (b4) copolymerizable with 1), butadiene and / or isoprene (b2), and a carboxyl group-containing monomer (b3)), the following monomers are used.

(Meth) acrylic acid ester: methyl (meth) acrylate, ethyl (meth) acrylate, (meth)
Propyl acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, (meth ) Reaction of ethoxyethyl acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, diglycidyl ether of bisphenol A or diglycidyl ether of glycol with (meth) acrylic acid or hydroxyalkyl (meth) acrylate Epoxy (meth) acrylate obtained by the above, urethane (meth) acrylate obtained by the reaction of hydroxyalkyl (meth) acrylate and polyisocyanate, and the like.

Unsaturated hydrocarbons: ethylene, propylene,
Olefins such as 1-butene, 2-butene, isobutene, 1-pentene, and aromatic vinyl monomers such as styrene and methylstyrene.

Monomers having various functional groups other than carboxyl group: glycidyl (meth) acrylate, (meth)
Monomers having epoxy groups such as acryl glycidyl ether; dimethylaminomethyl (meth) acrylate,
Monomers having amino groups such as diethylaminoethyl (meth) acrylate; monomers having amide groups such as (meth) acrylamide, dimethyl (meth) acrylamide; hydroxyl groups such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate Monomers having; monomers having an isocyanate group such as vinyl isocyanate, isocyanate ethyl (meth) acrylate, p-styryl isocyanate; monomers having a phosphoric acid group such as (meth) acryloxyethyl phosphate.

Among the copolymers obtained by copolymerizing the above-mentioned monomer components, acrylonitrile-butadiene- (meth) acrylic acid copolymer, acrylonitrile-butadiene- (meth) acrylic acid- (meth) acrylic acid ester copolymer The polymer is preferable because it has excellent solubility in 2-cyanoacrylate (A).

The NBR copolymer (B) having a low metal content can be solution-polymerized, bulk-polymerized, or JP-A-63-125589.
Although it can be obtained by a special emulsion polymerization as disclosed in Japanese Patent Publication No. JP-A No. 2004-242, it is not always easy to obtain a high molecular weight polymer in solution polymerization and bulk polymerization, and it is not easy to control the reaction. JP 63
It is particularly preferable to employ the emulsion polymerization method disclosed in Japanese Patent Laid-Open No. 125589.

That is, after performing emulsion polymerization using at least a nonionic surfactant, the obtained polymer latex is heated in the presence of a nonionic surfactant and optionally a metal-free electrolyte. By coagulating a rubber-like copolymer, a low metal content NBR-based copolymer
You get (B).

The emulsion polymerization applied to the production of the low metal content NBR type copolymer (B) will be described more specifically. First, in the emulsion polymerization, a general polymerization agent is used in addition to the nonionic surfactant. It can be used, and in this case as well, it is preferable to use one containing no metal compound such as alkali metal as much as possible. However, since these drugs are used in a very small amount, there is no problem in practical use.

In the polymerization, a usual emulsion polymerization method is carried out using a peroxide, a redox compound, an azo compound, a persulfate or the like as a polymerization initiator. In addition, a molecular weight modifier or the like may be used if necessary.

Examples of the nonionic surfactant used as an essential component in emulsion polymerization include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester and polyoxy. Examples thereof include ethyleneoxypropylene block copolymer, alkylsulfinyl alcohol, and fatty acid monoglyceride.

Among the surfactants that can be optionally used in emulsion polymerization, examples of the anionic surfactant include soap, funnel oil, emulsified oil, alkylnaphthalene sulfonate, dodecylbenzene sulfonate, and oleic acid. Salt, alkylbenzene sulfonate, dialkyl sulfosuccinate, lignin sulfonate, alcohol ethoxy sulfate, secondary alkane sulfonate, α-
Examples thereof include olefin sulfonic acid and tamol, and examples of the cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkylpyridinium salt and alkylbenzyldimethylammonium salt.

However, the nonionic surfactant is preferably used in an amount of 30% by weight or more, more preferably 50 to 100% by weight, based on the total amount of the surfactant. The amount of the surfactant is preferably 1 with respect to 100 parts by weight of the monomer.
.About.20 parts by weight, more preferably 2 to 12 parts by weight.

The emulsion polymerization is carried out in a reactor from which oxygen has been removed, at a temperature below the cloud point of the commonly used nonionic surfactant. Here, the cloud point means a temperature at which clouding occurs only when the nonionic surfactant is heated, and is a phenomenon peculiar to the nonionic surfactant.

The monomers, nonionic surfactants, molecular weight regulators, polymerization initiators and the like may be added in total amounts before the reaction starts, or may be arbitrarily added after the reaction starts. In addition, conditions such as temperature and stirring can be arbitrarily changed during the reaction. However, it is necessary to keep the polymerization temperature below the cloud point of the nonionic surfactant used. The polymerization method may be either continuous or batch.

After the monomer is recovered from the polymer latex thus obtained under a reduced pressure or by steam distillation or the like, the latex is heated to a temperature above the cloud point of the nonionic surfactant (coagulation temperature). When heated to 1), the nonionic surface-active phase undergoes phase separation, and as a result, a polymer is instantaneously precipitated and the polymer can be separated. The heating may be performed batchwise in a container or continuously. If the solidification temperature exceeds 100 ° C,
In addition to the heating device, a pressure device is also required.

In this case, coagulation can be carried out at a lower temperature by adding a metal-free electrolyte to the latex. Examples of the metal-free electrolyte include inorganic salts such as ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium nitrate, and ammonium acetate, but are not limited thereto.

The proportion of the electrolyte used is preferably 5 to 100 parts by weight of the polymer component in the polymer latex.
20 parts by weight, more preferably 7 to 15 parts by weight. If the amount of the electrolyte used is less than 5 parts by weight, coagulation may be insufficient, while if it exceeds 20 parts by weight, it is uneconomical and the coagulation property hardly changes.

After the emulsion polymerization as described above, or after recovering the monomers, the polymer latex obtained is simply heated in the presence of a nonionic surfactant and a metal-free electrolyte to coagulate the polymer latex. You can (Metal compounds such as calcium chloride and sodium chloride, which have been conventionally used, are not used as a coagulant in order to prevent mixing of metal components.)

In this case, the heating temperature depends on the type, amount and ratio of the nonionic surfactant / ionic surfactant used.
Although it varies depending on the type and amount of the electrolyte used, the temperature is usually adjusted to 40 to 150 ° C, preferably 60 to 120 ° C. If the heating temperature is lower than 40 ° C., the latex becomes unstable, which is a problem in production. On the other hand, if it exceeds 150 ° C., gelation of the polymer may occur, which is not preferable.

The charging ratio of each monomer component at the time of polymerization is
The monomer units constituting the resulting copolymer are 15 to 50% by weight (preferably 20 to 50% by weight) of acrylonitrile (b1) units.
40% by weight), butadiene and / or isoprene (b
2) a unit of 40 to 85% by weight (preferably 60 to 80% by weight), a carboxyl group-containing monomer (b3) unit of 0 to 10% by mole (preferably 0.5 to 10% by mole, more preferably 1 to 8% by mole) and Other monomer (b4) unit copolymerizable with these monomers 0 to 30% by weight (preferably 0 to
20% by weight).

When the amount of bound acrylonitrile is less than this range or the amount of bound butadiene and / or isoprene is more than this range, the solubility in 2-cyanoacrylate (A) decreases. On the other hand, when the amount of bound acrylonitrile is more than this range or the amount of bound butadiene and / or isoprene is less than this range, the glass transition point (Tg) increases, the elasticity decreases, and the peel strength as an adhesive decreases.

The carboxyl group-containing monomer (b3) is not an essential component, but it is particularly desirable that at least 0.5 mol% thereof is bonded in view of compatibility with the 2-cyanoacrylate (A). When the amount of bound carboxyl groups is extremely small, the effect of improving peel strength and heat-resistant tensile shear strength when used as an adhesive may not be sufficiently exhibited. On the other hand, when the amount of bound carboxyl groups exceeds 10 mol%, the stability of the latex during polymer synthesis is lowered and it becomes difficult to obtain a polymer with good reproducibility.

The other monomer (b4) unit can be introduced mainly from the viewpoint of the balance of physical properties, but the binding amount thereof should be at most 30% by weight, usually 20% by weight, and if it is more than that. The proportion of other monomer components becomes relatively small, the desired physical properties are impaired, and the solubility in 2-cyanoacrylate (A) decreases.

The molecular weight of the low metal content NBR copolymer (B) is not particularly limited, and it can be used from a liquid having a molecular weight of about 2000 to a solid having a molecular weight of 1,000,000. The molecular weight is preferably 100,000 to 200,000 from the balance of the adhesive strength and viscosity (workability) of the instant adhesive obtained by blending with A).

Low metal content The ash content of carboxy-modified NBR (B) and the content of metals such as Na and K are 500 ppm or less (preferably 200 ppm) for the purpose of the present invention.
Or less, more preferably 100 ppm or less), (Na +
It is necessary to pay attention to the conditions for producing the copolymer so that the amount of K) is 30 ppm or less (preferably 20 ppm or less). If either the amount of ash or the amount of (Na + K) exceeds this range, the effect of improving the peel strength and heat-resistant tensile shear strength when blending with 2-cyanoacrylate (A) to prepare an instant adhesive is sufficient. Is not played.

The compounding amount of the low metal content NBR copolymer (B) is 1 part by weight or more (usually 2 parts by weight or more, preferably 3 parts by weight) per 100 parts by weight of the 2-cyanoacrylate (A).
And more preferably 5 parts by weight or more) up to the solubility limit. If the amount is too small,
The effect of improving peel strength and the effect of improving heat resistant tensile shear strength are insufficient. The solubility limit is about 10 parts by weight, although it varies depending on the types of the 2-cyanoacrylate (A) and the low metal content NBR copolymer (B).

In addition to the instant adhesive of the present invention, various additives conventionally used in 2-cyanoacrylate instant adhesives, for example, storage stabilizers, organic solvents,
Plasticizers, polymers (polyacrylates, polymethacrylates, polycyanoacrylates, etc.), fillers, thixotropy improving agents, other heat resistance imparting agents (aromatic acid anhydrides, maleic anhydride, naphthsultone compounds, quinoids, etc.) , Polarity reducing agents, curing accelerators (polyethylene glycol or its derivatives, crown compounds, calexarenes, etc.), curing inhibitors, surfactants, dispersants, colorants, carbonate compounds (ethylene carbonate, etc.), pyrogallol, gallic acid, etc. Can be added as appropriate. Of these, a plasticizer, a polymer, a filler, a thixotropy improver, a colorant and the like can be blended in advance on the side of the low metal content NBR copolymer (B).

[0047]

The low metal content NBR copolymer (B) has a higher solubility in 2-cyanoacrylate (A) than ordinary NBR and ordinary carboxy-modified NBR. About 100 parts by weight of cyanoacrylate (A) can be uniformly dissolved in an amount of about 10 parts by weight.

The instant adhesive of the present invention prepared by blending 2-cyanoacrylate (A) with an appropriate amount of the low metal content NBR copolymer (B) has a greatly improved peel strength. The tensile shear strength after passing through the heat history is also outstanding. Moreover, the storage stability is excellent, and the degree of delay in set time is small, so that the quick adhesion of 2-cyanoacrylate is maintained. Also, since the viscosity of the instant adhesive is appropriately increased by blending the low metal content NBR-based copolymer (B), it is necessary to firmly adhere even to an uneven adherend or a porous adherend. You can

[0049]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, "parts" refers to parts by weight.

Examples 1 to 6, Comparative Examples 1 to 5, Control Example 1 <Preparation of 2-cyanoacrylate and NBR compounding ingredients> The following 2-cyanoacrylate and NBR compounding agents were prepared. Among the characteristic values of the NBR-based compounding agent, the amount of bound acrylonitrile is NC- manufactured by Sumitomo Chemical Co., Ltd.
The nitrogen content was determined using an 800 fully automatic nitrogen analyzer and calculated from this. The amount of bound carboxyl group was determined by a titration method using phenolphthalein as an indicator and an alkali according to a conventional method. The amount of Na and the amount of K were measured by the atomic absorption method. The amount of ash was obtained by placing 2 g of the copolymer in a crucible that had been precisely weighed in advance, baking it in an electric muffle furnace at a temperature of 550 ° C. for 12 hours, and then precisely weighing the amount of ash. The amount of bound butadiene or bound isoprene is automatically determined when the amount of bound acrylonitrile and the amount of bound carboxyl group-containing monomer are determined.

2-Cyanoacrylate (A) (A-1) Ethyl 2-cyanoacrylate (A-2) Isobutyl 2-cyanoacrylate (A-3) Ethoxyethyl 2-cyanoacrylate (A-4) Allyl 2-cyanoacrylate

NBR compounding ingredients (B), (B ') (B-1) Low metal content carboxy-modified N manufactured by Japan Synthetic Rubber Co., Ltd. manufactured according to the emulsion polymerization formulation of (B-2) described later.
BR "PNR-1H". 27% by weight of bound acrylonitrile, 4.0 mol% of bound carboxyl group based on acrylic acid, Mooney viscosity ML _{1 + 4} (100 ° C.) = 60, ash content
0.01% (100ppm), Na content 8ppm, K content 2ppm.

(B-2) Using the emulsion polymerization formulation shown below, emulsion polymerization was carried out at 20 ° C. in a pressure resistant autoclave having an internal volume of 2.0 liters. (Emulsion Polymerization Formulation) Isoprene 60 parts Acrylonitrile 34 parts Methacrylic acid 6 parts Water 220 parts Polyoxyethylene nonylphenol ether 5 parts ("Emulgen 920, cloud point 82 ° C" manufactured by Kao Soap Co., Ltd. 0.4 parts tertiary dodecyl mercaptan) Ammonium sulfate 0.25 part Cyanoethylated diethanolamine 0.15 part

After the polymerization conversion reached 90%, 0.2 part of hydroxylamine sulfate was added to 100 parts of the monomer to terminate the polymerization. Then, heat it up to about 70 under reduced pressure.
After the residual monomer was recovered by steam distillation at ℃, 1 part of alkylated phenol was added as an anti-aging agent, then this polymer latex was put in a pressure vessel and heated to 110 ℃ to coagulate the latex. . The generated crumb was taken out, washed with water, and then dried under reduced pressure at 50 ° C. to obtain a sample for evaluation.

The amount of bound acrylonitrile of the copolymer (B-2) was 33% by weight, the amount of bound carboxyl groups was 3.5 mol%, the Mooney viscosity was ML _{1 + 4} (100 ° C.) = 48, and the ash content was
0.008% (80ppm), Na content 6ppm, K content 1ppm
Met.

(B-3) A low metal content NBR produced according to the emulsion polymerization formulation of (B-2) above. 34% by weight of bound acrylonitrile, Mooney viscosity ML _{1 + 4} (100 ° C.) = 5
6, ash content 0.01% (100ppm), Na content 8ppm, K content 1ppm.

(B'-1) Carboxy-modified NBR "N632S" manufactured by Nippon Synthetic Rubber Co., Ltd. 33% by weight of bound acrylonitrile, 4.0 mol% of bound carboxyl group, Mooney viscosity ML _{1 + 4} (100 ° C.) = 60, amount of ash 0.69% (6
900ppm), Na content 130ppm, K content 28ppm.

(B'-2) Carboxy-modified NBR "XN-3" manufactured by Nippon Synthetic Rubber Co., Ltd. Acrylonitrile bound 2
7% by weight, bonded carboxyl group amount 4.0 mol%, Mooney viscosity ML 1 _{+ 4} (100 ° C.) = 45, ash content 0.27% (27
00ppm), Na content 90ppm, K content 21ppm.

(B'-3) Carboxy-modified NBR "Hiker 1072" manufactured by Nippon Zeon Co., Ltd., which is used in the examples of Japanese Patent Publication No. 43-29477. Ash content is 500pp
Much more than m, (Na + K content) far more than 30 ppm.

<Preparation of Instant Adhesive> A small amount of stabilizer (SO
₂ and hydroquinone) to 2-cyanoacrylate (A), the above-mentioned NBR compounding agents (B) and (B ') are added in a predetermined amount, and the mixture is stirred at room temperature for 12 hours to be dissolved to give an instant adhesive. Was prepared. For Example 6, low polymerization polymethylmethacrylate (PMMA) was also included. As Control Example 1, an ethyl 2-cyanoacrylate instant adhesive in which the NBR compounding agents (B) and (B ') were omitted was also prepared. When preparing the instant adhesives of Comparative Examples 2, 3, and 5, dioctyl phthalate as a plasticizer was added to 2-cyano in accordance with the description of the examples of Japanese Patent Publication No. 43-29477 described in the section of the prior art. 7 parts were blended with 100 parts of the acrylate (A).

<Measurement of Physical Properties> Using the above instant adhesive,
The set time, peel strength and tensile shear strength were measured under the following conditions. The number of tests was 7, respectively, the ones showing the minimum value and the maximum value were discarded, and the average value of the remaining 5 was taken. The results are shown in Tables 1 and 2.

An iron piece having a set time of 25 mm × 100 mm × 1.6 mm was used as a test piece and measured according to JIS K-6821.

A 90 ° peel strength (kgf / 25 mm) at room temperature was measured using an iron piece having a peel strength of 25 mm × 100 mm × 0.5 mm as a test piece.

Using SUS (stainless steel) having a tensile shear strength of 25 mm × 100 mm × 1.5 mm and EPDM (ethylene-propylene terpolymer) of 25 mm × 100 mm × 2.0 mm as test pieces, S
After bonding US-EPDM (contact area 12.5mm
Then, the tensile shear strength (kgf / cm ² ) in the normal state was measured. In order to check the tensile shear strength after heat history, after bonding between SUS and EPDM, leave it at room temperature for 24 hours, then put it in a furnace at a temperature of 120 ° C for 5 hours or 8 hours, and then return to room temperature. After that, the tensile shear strength (kgf / cm ² ) was measured.

[0065]

[Table 1]  Example 1 2 3 4 5 6 2-CA type (A-1) (A-2) (A-3) (A-4) (A-1) (A-1) Combination type (B-1) (B-2) (B- 1) (B-2) (B-3) (B-1) 2-CA / Compounding agent weight ratio 100/7 100/9 100/7 100/7 100/7 100/5 Viscosity (cps / 25 ℃) 1700 1700 2800 1800 1500 1300 Set time (sec) 30 45 50 40 20 60 Normal peel strength (kgf / 25mm) 5.0 3.7 5.1 4.8 4.3 5.1 Tensile shear strength (kgf / cm²) Normal * 5.8 * 6.0 * 5.8 * 5.6 * 5.0 * 5.9 120 ℃, after 5hr 3.0 4.6 1.9 3.5 2.5 3.0 After 120 hours at 8 ° C 2.3 4.0 1.2 2.0 1.8 2.4 (Note) 2-CA is 2-cyanoacrylate. * Indicates material destruction. In Example 6, in addition to (B-1) 100/5, PMMA was added in 100/2.

[0066]

[Table 2] Comparative example Control example 1 2 3 4 5 1 2-CA type (A-1) (A-2) (A-3) (A-1) (A-1) (A-1) Combination type (B '-1) (B'-1) (B'-1) (B'-2) (B'-3)-2-CA / compounding agent weight ratio 100/3 100/3 100/3 100/3 100 / 3-Viscosity (cps / 25 ℃) 35 30 40 32 35 2 Set time (sec) 90 90 120 70 90 2 Normal peel strength (kgf / 25mm) 3.5 2.5 2.5 3.5 3.5 0.8 Tensile shear strength (kgf / cm ² ) Normal state * 5.2 * 3.7 * 5.1 * 5.0 * 5.2 * 5.0 120 ℃, after 5 hours 1.6 1.1 1.0 1.6 1.1 1.0 120 ℃, after 8 hours 1.3 0.8 0.7 1.4 0.9 0.7 (Note) 2-CA is 2-cyanoacrylate. * Indicates material destruction. The upper limits of dissolution of the compounding agents (B'-1), (B'-2), (B'-3) of Comparative Examples 1 to 5 are slightly higher than 100/3, and are 100/5 or 100/7. I couldn't.

From Tables 1 and 2, even if the same NBR compounding agent is used, the usual carboxy-modified NBR (B'-1), (B'-
2), compared to the case of using (B'-3), when using the low metal content carboxy-modified NBR (B-1), (B-2), (B-3),
It can be seen that the following excellent effects can be obtained in combination with the fact that the amount of dissolution in 2-cyanoacrylate can be increased.

That is, the normal peel strength is about 40% in the case of ethyl 2-cyanoacrylate and about 50% in the case of isobutyl 2-cyanoacrylate.
Maximum 2 for ethoxyethyl 2-cyanoacrylate
It can be doubled.

The tensile shear strength after heat treatment at 120 ° C. for 5 hours is about 80% at maximum for ethyl 2-cyanoacrylate, about 4 times at maximum for isobutyl 2-cyanoacrylate, and ethoxyethyl 2-cyanoacrylate. In this case, the maximum can be increased by about 90%. 120
Regarding the tensile shear strength after heat treatment at 8 ° C. for 8 hours, the maximum is 70% or more in the case of ethyl 2-cyanoacrylate, and about 5 times in the case of isobutyl 2-cyanoacrylate.
Maximum 7 for ethoxyethyl 2-cyanoacrylate
It can be increased by about 50%.

In addition, low metal content carboxy-modified NB
When R (B-1), (B-2) and (B-3) are used, the viscosity is moderately increased and the set time delay is small.

In Example 6 in which the low metal content NBR (B-3) containing no carboxyl group was used, it was the same as in Example 1 in which the low metal content carboxy-modified NBR (B-1) was used. Ordinary carboxy-modified N, although it has no effect
Comparative Examples 1, 4, and 5 using BR (B'-1), (B'-2), (B'-3)
It turns out that better results are obtained.

[0072]

INDUSTRIAL APPLICABILITY The NBR copolymer (B) having a low metal content used as a compounding agent in the present invention is a 2-cyanoacrylate compared with a normal NBR or a normal carboxy-modified NBR.
Since it has a high solubility in (A), it can be uniformly dissolved in about 10 parts by weight with respect to 100 parts by weight of 2-cyanoacrylate (A).

In the instant adhesive prepared by blending 2-cyanoacrylate (A) with an appropriate amount of low metal content NBR copolymer (B), a usual carboxy-modified NBR was blended. Compared with instant adhesives, the peel strength is significantly improved, and the tensile shear strength when subjected to heat history at high temperature is remarkably high.

Moreover, no matter what kind of monomer is used as the 2-cyanoacrylate (A), the storage stability is excellent, and the degree of delay of the set time is small, so that the 2-cyanoacrylate has a fast adhesive property. Is maintained. Moreover, since the viscosity of the instant adhesive is appropriately increased, it is possible to perform strong adhesion even to an adherend having irregularities or a porous adherend.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hozumi Sato 1-5-201 Morikayamacho, Yokkaichi-shi, Mie

Claims (3)

[Claims] 1. A monomer unit constituting the copolymer comprises 15 to 50% by weight of an acrylonitrile (b1) unit, 40 to 85% by weight of a butadiene and / or isoprene (b2) unit, and 0 to 0 of a carboxyl group-containing monomer (b3) unit. A copolymer comprising 10 to 10 mol% and 0 to 30% by weight of another monomer (b4) unit copolymerizable with these monomers, wherein the ash content in the copolymer is 500 ppm or less, Na ion and K. A low metal content NBR-based copolymer (B) having a total ion content of 30 ppm or less is treated with 2-cyanoacrylate.
A 2-cyanoacrylate-based instant adhesive compounded in (A). 2. The 2-cyanoacrylate instant adhesive according to claim 1, wherein the proportion of the carboxyl group-containing monomer unit in the low metal content NBR copolymer (B) is 0.5 to 10 mol%. 3. The low-metal content NBR copolymer (B) based on 100 parts by weight of 2-cyanoacrylate (A) is 1 part by weight or more up to the solubility limit. -Cyanoacrylate instant adhesive.