JPH05214310A - Epoxy resin adhesive composition - Google Patents

Abstract

(57) [Summary] [Structure] (A) An epoxy resin derived from a compound obtained by adding 2 to 20 moles of ethylene oxide to bisphenol A or bisphenol A to which propylene oxide is added.
An epoxy resin or a mixture of those epoxy resins derived from a compound added with 20 to 20 moles thereof, (B) having a specific glass transition temperature, a weight average particle diameter of core particles, an average thickness of shell and a weight ratio of core / shell. And a core-shell type powdery polymer comprising an acrylate or methacrylate polymer obtained by graft-copolymerizing a specific amount of a crosslinkable monomer as one component of a shell component, and (C)
Provided is an epoxy resin-based adhesive composition having a pseudo-curing property, which contains a heat-activatable curing agent as an essential component. [Effect] It is excellent in impact resistance and adhesive performance such as tensile shear strength and T-shaped peel strength, and can impart pseudo-curability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel epoxy resin-based adhesive composition, more specifically, bisphenol A containing ethylene oxide or propylene oxide in an amount of 2 parts each.
It has an excellent impact resistance and a pseudo-curing property, which is obtained by blending an epoxy resin composed of a compound added with .about.20 mol and a core-shell type powdery polymer whose core and shell are specific (meth) acrylate-based polymers. The present invention relates to an epoxy resin-based adhesive composition.

[0002]

2. Description of the Related Art Conventionally, since epoxy resins have various excellent properties, for example, adhesives, adhesive films, base resins, casting resins, powder molding resins, paints, electronic circuit sealing agents, Widely used in various applications such as base resin for composite materials. However, this epoxy resin has a drawback that its impact resistance is insufficient, and various improvements have been made so far. The method of improving the impact resistance can be roughly divided into a method of improving the chemical structure of the epoxy resin itself and a method of adding a separately prepared impact resistance improver to the epoxy resin, but the former method. By itself, an epoxy resin which can sufficiently satisfy the impact resistance cannot be obtained. on the other hand,
As the latter method, (1) a method of adding a soluble elastomer monomer to an uncured epoxy resin and polymerizing the both simultaneously, (2) a method of adding a compatible elastomer polymer, (3) fine particles Known is a method of dispersing a polymer for improving impact resistance. With regard to the method (1), n-butyl acrylate is mixed with SIPN (Simultaneous interface) in an epoxy resin.
As netrating networks),
A method for producing a rubber domain having a size of 1 to 0.2 μm has been attempted [[J Journal of Polymer Science Symposium (J Polymer Sci. S.
ymposium) ", Vol. 46, pp. 175-190 (1974)], this method generally has drawbacks such as a decrease in the softening point of the product and variations in mechanical strength. Regarding the method (2), various examples have been proposed in which an elastomer component such as a butadiene-acrylonitrile copolymer rubber having carboxyl groups and amino groups as terminal groups is added to modify the rubber, and some of them are put into practical use. However, the product obtained by this method is still not sufficiently satisfactory in terms of impact resistance and toughness for use as a structural adhesive. Regarding the method (3), many impact resistance improvers including polyamide resin-based ones have been proposed, but all of them have the drawback of insufficient pseudo-curability. By the way, it is generally known that when a rubber component having a glass transition temperature of −30 ° C. or less is added as an impact resistance improver for plastics, it acts to absorb external stress and the impact strength is significantly improved. ing. However, when many of these rubber components are mixed with a liquid epoxy resin as a matrix, the dispersibility thereof is easily affected by the mixing conditions, and the resulting composition has unstable storage properties, and thus has a long-term storage stability. Is not practical as an automotive adhesive that requires stability. Further, it is also important for the epoxy resin-based adhesive to have a pseudo-curing property, and in order to impart a pseudo-curing property to the epoxy resin composition, a core-shell type modifier made of a (meth) acrylate-based polymer. Is known to be effective (JP-A-2-80483). Pseudo-curability here refers to the property of solidifying into a non-adhesive or tacky state at a heating temperature lower than the temperature at which a liquid or paste adhesive is thermoset, and such pseudo-curability is as shown below. Have advantages. That is, in the automobile industry, after applying a heat-curable adhesive composition based on an epoxy resin to a metal substrate, bending, cutting, degreasing cleaning, acid treatment and the like may be performed. However, there is a problem that the work environment is deteriorated due to the dropping or scattering of the adhesive, or the removal of the surplus adhesive protruding from the bonded portion, and the pretreatment liquid for coating is easily contaminated due to the elution of the adhesive. On the other hand, by applying adhesive to the base material and then heating it in a short time to form a pseudo-cured product, it becomes easier to remove excess adhesive from the base material, and contamination of the pretreatment liquid The problem of can be solved.

[0003]

Under the above circumstances, the present invention is excellent in impact resistance and adhesive performance such as tensile shear strength and T-shaped peel strength, and at the same time, an epoxy having pseudo-curability is given. The purpose of the present invention is to provide a resin-based adhesive composition.

[0004]

Means for Solving the Problems As a result of intensive studies to develop an epoxy resin-based adhesive composition having the above-mentioned preferable properties, the present inventors have found that it is resistant to epoxy resins having a flexible function. A core-shell type powdery polymer composed of a specific (meth) acrylate polymer is combined as an impact modifier, and a composition containing these and a heat-activatable curing agent for an epoxy resin can achieve the object. Based on this finding, the present invention has been completed.

That is, the present invention relates to (A) an epoxy resin derived from a compound obtained by adding 2 to 20 mol of ethylene oxide to bisphenol A or an epoxy resin derived from a compound obtained by adding 2 to 20 mol of propylene oxide to bisphenol A. Resin or a mixture of these epoxy resins, (B) Tg of acrylate or methacrylate polymer having Tg of -30 ° C or less as a core component, and Tg of 7 or less.
An acrylate or methacrylate polymer at 0 ° C. or higher is used as a shell component, the core particles composed of single or agglomerated particles have a weight average particle size of 0.1 to 3.0 μm, and an average shell thickness of 50 Å or more, Graft polymerization of the core / shell weight ratio in the range of 10/1 to 1/4 is performed by adding a crosslinkable monomer to the shell component in an amount of 0.01 to 5% by weight based on the total amount of the shell component. Provided is an epoxy resin-based adhesive composition having pseudo-curability, which comprises a core-shell type powdery polymer composed of a polymer obtained by copolymerization and (C) a heat-activatable curing agent as essential components. To do.

The present invention will be described in detail below. The epoxy resin used as the component (A) in the composition of the present invention contains bisphenol A containing ethylene oxide in an amount of 2 to 2
It is an epoxy resin derived from a compound added with 0 mol, or an epoxy resin derived from a compound added with 2 to 20 mol of propylene oxide to bisphenol A, or a mixture of these epoxy resins. In the epoxy resin of the component (A), the preferable addition amount of ethylene oxide or propylene oxide added to bisphenol A is in the range of 2 to 20 mol per 1 mol of bisphenol. The epoxy resin as the component (A) can be produced by various production methods. For example, a compound obtained by adding 2 to 20 mol of ethylene oxide or propylene oxide to the hydroxyl group of bisphenol A is reacted with epichlorohydrin at a predetermined ratio. By
The component (A) epoxy resin having various molecular weights can be produced.

As the epoxy resin as the component (A), an ethylene oxide addition type epoxy resin is preferable because each adhesive strength tends to be higher than that of a propylene oxide addition type epoxy resin. In addition,
The epoxy resin as the component (A) may be used in combination with other epoxy resins. Examples of the epoxy resin that can be used in combination include glycidyl ethers such as bisphenol A, bisphenol F, resorcinol and hydrogenated bisphenol A, glycidyl ether types such as polyglycidyl ethers of phenol novolac resin and cresol novolac resin, phthalic acid, and hexahydro. Phthalic acid,
Glycidyl ester type such as tetrahydrophthalic acid, further glycidyl amine type, linear aliphatic epoxide type,
Hydantoin type, dimer acid type, epoxy-modified NBR and the like can be mentioned. These epoxy resins may be used alone or in combination of two or more. When used in combination, the amount of the epoxy resin as the component (A) in the total epoxy resin component of the adhesive composition is 5 to 10.
0 wt% is preferable, and the range of 10-70 wt% is more preferable.

In the composition of the present invention, as the impact resistance improver, the acrylate or methacrylate polymer having a Tg of -30 ° C. or less as the component (B) is used as a core component and the acrylate or methacrylate polymer having a Tg of 70 ° C. or more is used. The polymer has a shell component and the core particles composed of single or agglomerated particles have a weight average particle diameter of 0.1 to 3.0 μm, an average shell thickness of 50 Å or more, and a core / shell weight ratio of 10 / Polymer obtained by graft-polymerizing in the range of 1 to 1/4 and copolymerizing by adding 0.01 to 5% by weight of a crosslinkable monomer to the shell component in the graft polymerization of the shell component. A core-shell type powdery polymer consisting of This core-shell type powdery polymer can be produced by a continuous multistage seed emulsion polymerization method of at least two stages. It is also possible to partially agglomerate the seed latex prepared in the first step by solvent coagulation and the like, and then graft-polymerize it to form a shell.

Hereinafter, typical production examples of the core-shell type powdery polymer will be described. First, in the first stage polymerization,
An acrylate or methacrylate-based monomer having an alkyl group having 2 to 8 carbon atoms, preferably the acrylate or methacrylate-based monomer and a crosslinkable monomer are polymerized to have a glass transition temperature of −30 ° C. or lower, preferably Is -40 to -7
Prepare a rubbery seed polymer at 0 ° C. Examples of the acrylate or methacrylate monomer having an alkyl group having 2 to 8 carbon atoms include ethyl acrylate, propyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate and butyl methacrylate. , Preferably n-butyl acrylate. These may be used alone or in combination of two or more.

The crosslinkable monomer has two or more double bonds having substantially the same reactivity, such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate and butylene glycol dimethacrylate. , Trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate,
Hexanediol diacrylate, hexanediol methacrylate, oligoethylene diacrylate, oligoethylene dimethacrylate, aromatic divinyl monomers such as divinylbenzene, triallyl trimellitate, triallyl isocyanurate and the like can be used. These crosslinkable monomers may be used alone or in combination of two or more kinds.
The amount used is usually 0.01-based on the total weight of the monomers.
It is selected in the range of 5% by weight, preferably 0.1 to 2% by weight.

In addition to the acrylate or methacrylate type monomer and the crosslinkable monomer, other copolymerizable monomers may be used if desired. As the other copolymerizable monomer used as desired, for example, styrene, vinyltoluene, aromatic vinyl compounds such as α-methylstyrene, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, Furthermore, vinylidene cyanide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxybutyl acrylate, 2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, monobutyl maleate, glycidyl methacrylate, butoxyethyl methacrylate and the like can be mentioned. Be done. These may be used alone or in combination of two or more,
The amount used is usually selected in the range of 50% by weight or less based on the total weight of the monomers.

Next, the acrylate or methacrylate polymer particles thus obtained are used as a core, and an acrylate or methacrylate monomer having an alkyl group having 1 to 4 carbon atoms and a crosslinkable monomer are added thereto. The second-stage emulsion polymerization is carried out in which a shell is formed by graft-polymerizing with an acrylate or methacrylate monomer having an alkyl group having 1 to 4 carbon atoms, such as ethyl acrylate. Examples thereof include n-butyl acrylate, methyl methacrylate, and butyl methacrylate. These may be used alone or in combination of two or more, and among these, methyl methacrylate is particularly preferable.

As the crosslinkable monomer, one or more selected from those exemplified in the description of the acrylate- or methacrylate-based polymer forming the core can be selected and used. It is triallyl melitate. The amount of the crosslinkable monomer used is usually selected in the range of 0.01 to 5% by weight, preferably 0.1 to 5% by weight, based on the total weight of the monomers of the shell component. In addition to the acrylate or methacrylate monomer and the crosslinkable monomer, other copolymerizable monomers may be used as desired. As the other copolymerizable monomer used as desired, one kind or two kinds or more can be selected and used from those exemplified in the description of the acrylate or methacrylate polymer forming the core. .. The amount used is based on the total weight of the monomers,
Usually, it is selected within the range of 50% by weight or less.

The glass transition temperature of the acrylate or methacrylate polymer forming the shell needs to be 70 ° C. or higher, preferably 80 to 120 ° C. If it is less than 70 ° C, the storage stability is insufficient when it is mixed with an epoxy resin to form an adhesive composition.
In the following cases, the polymer has high tackiness and may cause clogging of nozzles during spray drying. The latex containing the core-shell type polymer obtained by such multistage emulsion polymerization is usually directly spray-dried to obtain a core-shell type powdery polymer having excellent dispersibility in an epoxy resin. This core-shell type powdery polymer can be obtained by the multistage seed emulsion polymerization method of at least two stages as described above. In some cases, the seed latex prepared in the first stage is partially agglomerated, and then the seed latex is formed thereon. It may be produced by graft polymerization,
Furthermore, after emulsion polymerization, latex particles are coagulated and separated by a salt folding method or a freezing method, and a wet cake prepared by dehydration can be dried in a fluidized bed or the like to obtain agglomerated particles.

The core / shell type powdery polymer thus obtained has a core / shell weight ratio of 10/1 to
It must be in the range of 1/4, preferably 8 /
It is in the range of 1 to 1/3. Core / shell weight ratio is 10 /
When it exceeds 1, various adhesive strengths are greatly reduced, storage stability is deteriorated, and pseudo-curability is not observed. When the core / shell weight ratio is less than 1/4, storage stability and pseudo-curability are improved, but various adhesive strengths, particularly T-shaped peel strength, are significantly reduced. Further, the weight average particle diameter of the core particles composed of the single or agglomerated particles of the core-shell type powdery polymer needs to be in the range of 0.1 to 3.0 μm, preferably 0.15 to 2.0. It is in the range of 0 μm. In this case, the core particles may be polymerized with the shell component subsequent to the polymerization of the core component, or the core particles may be agglomerated by solvent coagulation, salting out coagulation or the like and then polymerized for coating the shell component. .. There are many known methods for secondary aggregation, and any of them can be used.

When the weight average particle diameter of the core particles is less than 0.1 μm, the dispersibility is poor because the surface area is large with the same weight, and the machine of the epoxy resin adhesive composition containing the core-shell type powdery polymer is used. Strength and storage stability are reduced. Further, when the particle size of the core particles exceeds 3.0 μm, various adhesive strengths such as shear strength and peeling strength are significantly reduced. The average thickness of the shell of the core-shell type powdery polymer needs to be 50 Å or more, and preferably in the range of 50 to 5000 Å. If it is less than 50Å, the shell component does not have sufficient covering property, which causes deterioration of storage stability. In the composition of the present invention, the blending amount of the core-shell type powdery polymer as the component (B) is not particularly limited, but is usually the epoxy resin 1 as the component (A).
10 to 100 parts by weight, preferably 1 to 100 parts by weight
It is a proportion of 0 to 50 parts by weight. If this amount is less than 10 parts by weight, the impact resistance improving effect is difficult to be sufficiently exerted, while if it exceeds 100 parts by weight, the viscosity becomes extremely high and it becomes difficult to handle.

In the composition of the present invention, the heat-activatable curing agent for epoxy resin used as the component (C) is, for example, dicyandiamide, 4,4'-diaminodiphenylsulfone, imidazole such as 2-n-heptadecylimidazole. Derivatives, isophthalic acid dihydrazide, N, N
-Dialkylurea derivatives, N, N-dialkylthiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride,
Examples thereof include isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, melamine, guanamine, boron trifluoride complex compound, and trisdimethylaminomethylphenol. These may be used alone, or 2
Although it may be used in combination of two or more species, among these,
Particularly, dicyandiamide is preferable.

The amount of the heat-activatable curing agent as the component (C) is not particularly limited, but is usually 3 to 30 parts by weight, preferably 100 parts by weight of the epoxy resin as the component (A). It is a ratio of 5 to 20 parts by weight. If this amount is less than 3 parts by weight, curing failure will occur, causing a significant decrease in each adhesive strength, and if it exceeds 30 parts by weight, partial decomposition or thermal deterioration will occur due to excessive exothermic reaction during molding.
As a result, each adhesive strength is significantly reduced or discolored. In the composition of the present invention, if desired, adjustment of construction characteristics such as workability and viscosity within a range that does not impair the object of the present invention,
Various additives for the purpose of stability or cost reduction, such as curing accelerators, fillers, pigments, thixotropic agents, flame retardants, antioxidants, release agents, surfactants,
A foaming agent or the like can be added.

Examples of the curing accelerator include alcohols, phenols, mercaptans, dimethylureas, alicyclic compounds, and imidazole. In addition, for cost reduction, viscosity adjustment, etc., as a filler that is usually often mixed, for example, calcium carbonate,
Silica, talc, mica, kaolin clay, celite,
Examples include asbestos, perlite, baryta, silica sand, flake graphite, dolomite limestone, gypsum, and fine aluminum powder. The amount of filler added is (A)
It is used in the range of 5 to 100 parts by weight per 100 parts by weight of the component epoxy resin. In particular, when talc is added as a filler, various adhesive strengths are hardly reduced when the addition amount is up to 20 parts by weight. Furthermore, examples of the pigment include titanium dioxide, litharge, lithopone, zinc oxide, carbon black, and the like, and examples of the thixotropic agent include silicic acid (colloidal silica) such as silicic acid anhydride and hydrous silicic acid, and organic bentonite. Organic type etc. are mentioned. The addition amount of the thixotropic agent is usually 1 to 1 per 100 parts by weight of the epoxy resin of the component (A).
It is selected in the range of 5 parts by weight.

The epoxy resin-based adhesive composition of the present invention comprises
It can be prepared by homogeneously kneading the component (A), the component (B), the component (C) and various optional components used as necessary at room temperature. Examples of the kneader used at this time include a change can mixer, a planetary mixer, a disper, a Henschel mixer, a kneader, an ink roll, and an extruder which are commonly used. The epoxy resin-based adhesive composition of the present invention thus prepared does not contain a core-shell type powdery polymer composed of the epoxy resin as the component (A) and the acrylate or methacrylate polymer as the component (B). Compared with, the impact peel strength and T-shaped peel strength are remarkably improved, and pseudo-curability is also imparted. This epoxy resin-based adhesive composition is applied to the substrate to be adhered by a conventional method such as spraying, sealer gun or brush coating. This substrate to be adhered is usually a metal, and even if rust preventive oil adheres, the composition of the present invention does not impair the adhesion.

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The performance of the adhesive composition was evaluated as follows. (1) Pseudo-curability The composition was heated at 110 ° C. for 5 minutes to cause gelation, the peeling removability was determined, and evaluated according to the following criteria. ◯: The gelled adhesive composition could be easily peeled and removed. Δ: The gelled adhesive composition had low strength and was torn at the removal stage. X: Pseudo-curing was not achieved by heating at 110 ° C. for 5 minutes. (2) Storage stability The ratio of the viscosity with time when stored at 40 ° C for 7 days to the initial viscosity was determined and evaluated according to the following criteria. ◯: The ratio is 1.5 or less Δ: The ratio is greater than 1.5 and 5 or less ×: The ratio is greater than 5 (3) Adhesive strength Using mild steel as the substrate to be adhered, the following method It was evaluated according to. The curing condition was 180 ° C. for 30 minutes. Impact peel strength: JIS K-6855 Tensile shear strength: JIS K-6850, Test piece 1.6
× 25 × 200mm T-shaped peel strength: JIS K-6854, test piece 0.8
× 25 × 200mm

Production Example of Core-Shell Type Powdery Polymer A core component monomer and a crosslinkable monomer described in Table 1 are polymerized to have a predetermined glass transition temperature and a predetermined weight average particle of the core particle. The core-shell type powdery polymer (B-1 to B-) is formed by forming core particles having a diameter and then graft-polymerizing the shell component described in Table 1 to form a shell having a predetermined glass transition temperature. 10) was produced.

Example 1 Bisphenol A to which 6 mol of ethylene oxide was added
Type epoxy resin 40 parts by weight and bisphenol A type epoxy resin 60 parts by weight, core shell type powdery polymer B-1 40 parts by weight and dicyandiamide 10 shown in Table 1.
Parts by weight were added, and the mixture was kneaded with a planetary mixer for 10 minutes and defoamed with a vacuum defoamer to prepare an epoxy resin-based adhesive composition, and the pseudo-curability and storage stability were determined.
Next, the composition was applied to a predetermined steel plate with a doctor knife and heat-treated at 180 ° C. for 30 minutes to prepare an evaluation sample, and each adhesive strength was determined according to the aforementioned JIS method. The evaluation results are as shown in Table 2, and the impact peel strength, the tensile shear strength, and the T-shaped peel strength were high.

Example 2 The same as Example 1 except that the bisphenol A type epoxy resin added with 6 mol of propylene oxide was used in place of the bisphenol A type epoxy resin added with 6 mol of ethylene oxide used in Example 1. It was carried out. As a result, similar to Example 1, each adhesive strength showed a high value.

Example 3 When 20 parts by weight of the filler talc was added to reduce the molding shrinkage of Example 2, the initial viscosity was increased, but the storage stability was improved.

Example 4 Example 4 was repeated except that the type of the core-shell type powdery polymer used in Example 1 was changed from B-1 to B-2. In Example 1, the weight ratio of the core / shell was 1/2, and in Example 4, the polymer was used at 1/4. However, in the latter case, the adhesive strength tended to decrease, and the core / shell was reduced. A weight ratio of 1/4 is a practical limit when the shell layer is thickened. Regarding the pseudo-curability and the storage stability, the same results as in Example 1 were obtained.

Example 5 The procedure of Example 4 was repeated, except that the epoxy resin of the ethylene oxide addition type was replaced with the bisphenol A type epoxy resin having 6 mol of propylene oxide added. In this case, the adhesive strengths were almost the same as those in Example 4, but as already described in Example 2, the comparison of both epoxy resins shows that the ethylene oxide addition type tends to have higher adhesive strength. For this reason, the ethylene oxide addition type was used in all Comparative Examples. The pseudo-curability and storage stability were the same as in Example 1.

Example 6 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-4. The difference between Example 1 and Example 6 is that a resin in which the weight ratio of core / shell is changed from 1/2 to 2/1 is used, whereby various adhesive strengths are equal to or higher than those of Example 1. However, only the pseudo-curability was slightly lowered.

Example 7 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-4. The difference between Example 1 and Example 7 is that only a core component of the polymer was changed from butyl acrylate to 2-ethylhexyl acrylate having a high molecular weight with a similar monomer, and in this case, the same as in Example 1. Each adhesive strength was obtained.

Comparative Example 1 100 parts by weight of a bisphenol A type epoxy resin and 8 parts by weight of dicyandiamide were kneaded in a planetary mixer for 10 minutes and vacuum defoamed to prepare an epoxy resin adhesive composition. The physical properties were evaluated in the same manner as in.
As a result, when the bisphenol A type epoxy resin alone was used, the T-shaped peel strength was extremely low and there was no pseudo-curability.

COMPARATIVE EXAMPLE 2 In Example 1, C.C., which has been used as a structural adhesion modifier in place of the core-shell type powdery polymer, is used. T. B.
N. Was carried out in the same manner as in Example 1 except that was used. In this case, the T-shaped peel strength was lower than in Example 1, there was no pseudo-curability, and the storage stability was somewhat inferior.

Comparative Example 3 The procedure of Example 1 was repeated, except that a polyamide resin, which had been used as a structural adhesion modifier, was added in place of the core-shell type powdery polymer. In this case, each adhesive strength showed a relatively high value. However, they were somewhat inferior to those of Example 1 and had no pseudo-curability.

Comparative Example 4 4 of the bisphenol A type epoxy resin used in Comparative Example 1
Comparative Example 1 was carried out except that the ethylene oxide-added bisphenol A type epoxy resin was replaced. As a result, the impact peel strength and the T-shaped peel strength tended to be slightly improved as compared with those using the bisphenol A type epoxy resin alone. By partially replacing the epoxy resin to which flexibility was imparted by adding ethylene oxide. It was found that the improvement of each adhesive strength can be expected. However, similar to Comparative Example 1, it had no pseudo-curability.

Comparative Example 5 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-5. The difference between Example 1 and Comparative Example 5 is that half of the butyl acrylate, which is the core component of the former polymer, is replaced with the same methyl methacrylate as the shell component of the same polymer. The peel strength was a remarkably low value.

Comparative Example 6 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-6. In the present invention, in order to control the viscosity and storage stability of the adhesive, the shell component is crosslinked to adjust the compatibility of the epoxy resin and the core-shell type powdery polymer, and the crosslinkable monomer at the time of graft polymerization is adjusted. The addition of is an essential condition as claimed. The core-shell type powdery polymer used in this example was carried out without using a crosslinkable monomer when polymerizing the shell component, and in this case, each adhesive strength was relatively good, The storage stability was inferior.

Comparative Example 7 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-7. In this case, both component compositions are exactly the same, but in Example 1, core particles having a weight average particle diameter of 0.5 μm prepared by emulsion polymerization were used, whereas in Example 7, suspension polymerization was used. Further, the core particles having a weight average particle diameter of 12 μm were used, which resulted in poor impact peel strength and T-shaped peel strength.

Comparative Example 8 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-8. When half of the methyl methacrylate of the shell component of Example 1 was replaced with butyl acrylate and polymerized, this resulted in a decrease in adhesive strength and storage stability,
There was no pseudo-curability at all.

Comparative Example 9 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-9. In this case, the same components as in Example 1 were used, but only the core / shell weight ratio was changed from 1/2 to 100/8 to reduce the thickness of the shell layer. The storage stability was inferior, and the pseudo-curability was not observed at all.

Comparative Example 10 The procedure of Example 1 was repeated, except that the core-shell type powdery polymer used in Example 1 was replaced with B-10. Same composition as in Example 1 but with a core / shell weight ratio of 1 /
The use of the one changed from 2 to ⅕ resulted in a significant decrease in the T-shaped peel strength.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

The subscripts in Tables 2 and 3 are as follows. Note) 1): Epoxy resin prepared by reacting epichlorohydrin at a molar ratio of 2/1 with a compound obtained by adding 3 moles of ethylene oxide to both hydroxyl groups of bisphenol A 2): 3 moles of propylene oxide containing both moles of bisphenol A Epoxy resin obtained by reacting the compound added to the above with epichlorohydrin at a molar ratio of 2/1 3): Acrylonitrile-butadiene rubber modified with terminal carboxyl

[0044]

The epoxy resin-based adhesive composition of the present invention contains an epoxy resin derived from a compound obtained by adding 2 to 20 moles of ethylene oxide or propylene oxide to bisphenol A as an epoxy resin, and further has impact resistance. A blend of a core-shell type acrylate or methacrylate powdery polymer as an improver, which has excellent impact resistance and adhesive performance such as tensile shear strength and T-shaped peel strength, and good pseudo-curability. It has features.

[Procedure amendment]

[Submission date] April 1, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Item name to be corrected] 0040

[Correction method] Change

[Correction content]

[0040]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Nakayama 1-2-1, Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa, Japan Zeon Corporation R & D Center (72) Toshio Nagase In-chief, Yakou, Kawasaki-ku, Kawasaki-shi, Kanagawa 2-2-1 Nihon Zeon Co., Ltd. Research and Development Center

Claims (1)

[Claims] 1. An epoxy resin derived from (A) a compound obtained by adding 2 to 20 moles of ethylene oxide to bisphenol A, or an epoxy resin derived from a compound obtained by adding 2 to 20 moles of propylene oxide to bisphenol A, or a resin thereof. A mixture of epoxy resins, (B) T
g is −30 ° C. or less as a core component, Tg is 70 ° C. or more as an acrylate or methacrylate polymer as a shell component, and the weight average particle diameter of core particles composed of single or agglomerated particles is It is 0.1 to 3.0 μm, the average thickness of the shell is 50 Å or more, and the graft polymerization is carried out in the range of the core / shell weight ratio of 10/1 to 1/4. 0.01 to the total amount of shell components
A core-shell type powdery polymer composed of a polymer obtained by adding 5% by weight to 5% by weight, and (C) a heat-activatable curing agent as an essential component. Adhesive composition.