JPH0715042B2 - Epoxy resin composition and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition which is tough and has excellent heat resistance and adhesiveness, and a method for producing the same. The epoxy resin composition comprises an adhesive, a molding material, a paint, and a sealing material. It is extremely useful as an agent.

[0002]

2. Description of the Related Art Epoxy resins have a well-balanced performance in terms of thermal, mechanical and electrical properties, so adhesives, paints, electric / electronic component materials, civil engineering materials, etc. It is widely used in many fields.
However, since the epoxy resin has the disadvantage that the cured product is hard and brittle, as a method for improving it, a method of incorporating a plasticizing component, or a method of reducing the crosslinking density by using a monofunctional epoxy compound together Etc. were considered.

However, although these methods improve the toughness of the cured product, they are not the fundamental solution because the heat resistance remarkably decreases. Then, the method considered was to modify the epoxy resin with various rubbers. For example, there is a method in which a rubber having a functional group reactive with an epoxy resin or an epoxy resin curing agent introduced into the molecule is allowed to coexist in the curing reaction system of the epoxy resin and reacted. According to this method, the toughness of the epoxy resin is considerably improved, and in some cases, a cured product having good heat resistance can be obtained. However, depending on the type of curing agent used and the curing conditions, the shape of the dispersed rubber particles may change and the effect of improving toughness may not be exerted effectively, or part or all of the rubber may be compatible with the epoxy resin, resulting in heat resistance. There was a problem of deteriorating.

Further, a method is known in which modifying rubber particles obtained by emulsion polymerization are added to an epoxy resin. In this method, the modifying shape of the modifying rubber particles due to curing conditions, etc. Since the compatibilization does not occur, the above problems are solved. The following is known as this type of reforming method. That is, JP-A-52
JP-A-36198 discloses a composition in which a curing agent is added to a mixture of an emulsion elastomer and a liquid or emulsion epoxy resin, and JP-A-53-78237 discloses an acrylic emulsion. A coating composition comprising an epoxy resin and an anticorrosion pigment is disclosed.

With these compositions, the shape of the modifying rubber particles does not change and the modifying effect is not impaired during the curing reaction of the epoxy resin, but neither the epoxy resin nor the modifying rubber particles is used. Since it is an aqueous dispersion, its application range is significantly limited. For these, JP-A-6
1-69827, JP-A-62-50361, JP-A-62-275149, JP-A-62-2.
No. 2849, JP-A-62-22850, JP-A-2-80483, and JP-A-2-117948 disclose compositions in which modifying rubber particles are directly dispersed in an epoxy resin. Has been done. However, in these methods, since the modifying rubber particles obtained by so-called core / shell polymerization are once taken out as a powder and then mixed with an epoxy resin, not only the process is complicated but also
Since it contains a shell component that does not directly contribute to the improvement of toughness, the modifying effect is poor relative to the amount added, and in the method of dispersion polymerization of the polymerizable monomers that make up the rubber in the epoxy resin, the molecular weight of the rubber component is Does not rise sufficiently, the rubber component dissolved in the epoxy resin becomes large and the heat resistance becomes poor, and when the rubber particles are synthesized by emulsion polymerization, there is no compatibility and reactivity with the epoxy resin as an emulsifier, and Since the water-soluble one is used, there are problems that the toughness of the obtained epoxy resin composition is lowered and the water absorption is increased.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to make rubber particles which are substantially incompatible with an epoxy resin have a curing condition of the epoxy resin. Epoxy resin that can be widely used as various molding materials, adhesives, paints, encapsulants, etc., showing excellent toughness, moisture / water resistance and adhesiveness as a whole, without being affected by the like. It is intended to provide a composition.

[0007]

The composition of the epoxy resin composition according to the present invention, which has been able to solve the above-mentioned problems, has a polymerizable monomer component (A) containing an unsaturated carboxylic acid as an essential component, From a water-soluble or water-dispersible terminal alkyl group-containing polymer [Pa] and / or a salt thereof, which is obtained by polymerization in the presence of an alkyl mercaptan (B) having a number of 6 to 18 Having a glass transition temperature of 20 obtained by emulsion polymerization of the (meth) acrylic acid ester-based monomer (C) using the reactive surfactant
(Meth) acrylic acid ester-based polymer particles having a temperature of ℃ or less [P
b] has a gist in that it is dispersed in an epoxy resin, and this epoxy resin composition has
It can be easily obtained by uniformly mixing the above-mentioned (meth) acrylic acid ester-based polymer emulsion obtained by emulsion polymerization with an epoxy resin, and then removing water from this aqueous mixed solution.

[0008]

In the present invention, as the rubber particles dispersed as a toughness improving component in the epoxy resin, a polymerizable monomer (A) containing an unsaturated carboxylic acid as an essential component is used as an alkyl group having 6 to 18 carbon atoms. Water-soluble or water-dispersible acid value of 20 obtained by polymerization in the presence of mercaptan (B).
0 or more terminal alkyl group-containing polymer [Pa] and /
Or using a reactive surfactant consisting of a salt thereof as an emulsifier,
(Meth) acrylic acid ester-based polymer particles [Pb] having a glass transition temperature of 20 ° C. or lower, which are obtained by emulsion polymerization of a (meth) acrylic acid ester-based monomer, are used.

That is, in the present invention, as the emulsifier in the production of the (meth) acrylic acid ester-based polymer particles [Pb], the reactivity of a specific terminal alkyl group-containing polymer [Pa] and / or a salt thereof. It has one characteristic in using a surfactant, and effectively exhibits the function as an emulsifying agent for emulsion polymerization, and as described in detail later, (meth) acrylic acid ester-based polymer particles [P
In order to give b] reactivity with an epoxy resin, a water-soluble or water-dispersible terminal alkyl group-containing polymer [Pa] having an acid value of 200 or more must be used, and its molecular weight is 300. ~ 7000, especially 1000-4000
The range of is preferable.

The unsaturated carboxylic acid used in the synthesis of the terminal alkyl group-containing polymer [Pa] (hereinafter sometimes simply referred to as polymer [Pa]) is hydrophilic by introducing a carboxyl group into the polymer. (Meth) acrylic acid ester-based polymer particles obtained by emulsion polymerization [P
It is used to introduce a functional group capable of reacting with an epoxy resin into b] so that the emulsifier does not remain as an unreacted low molecular weight product in the epoxy resin composition. The type is not particularly limited as long as it has a group and a polymerizable unsaturated group, but preferred examples include (meth) acrylic acid, unsaturated monocarboxylic acids such as crotonic acid, maleic acid, fumaric acid,
Examples thereof include unsaturated dicarboxylic acids such as itaconic acid and half-esterified products of these unsaturated dicarboxylic acids. These may be used alone or in combination of two or more.

As the polymerizable monomer component (A), only the unsaturated carboxylic acid as described above may be used, or if necessary, a suitable amount of a polymerizable monomer other than the unsaturated carboxylic acid may be used in combination. The polymerizable monomer that can be used in combination is not particularly limited as long as it has a copolymerizability with an unsaturated carboxylic acid,
For example, styrene derivatives such as styrene, vinyltoluene, α-methylstyrene, chloromethylstyrene, styrenesulfonic acid and salts thereof; (meth) acrylamide, N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, (Meth) acrylamide derivatives such as N-dimethyl (meth) acrylamide; (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate, and C1-18 (Meth) acrylic acid esters synthesized by esterification reaction with alcohol;
Hydroxy group-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and monoesters of (meth) acrylic acid with polypropylene glycol or polyethylene glycol; ) Ethyl acrylate 2-sulfonic acid and its salt, vinyl sulfonic acid and its salt, vinyl acetate, (meth) acrylonitrile, etc. can be mentioned, and these 1 type (s) or 2 or more types can be used. The polymerizable monomer other than the unsaturated carboxylic acid has an acid value of the obtained terminal alkyl group-containing polymer [Pa] of 20.
The combined amount should be considered so as not to be less than 0. Further, it is preferable to adjust the kind and amount of the obtained terminal alkyl group-containing polymer [Pa] in consideration of compatibility with a polymer produced when emulsion polymerization is performed using the polymer as an emulsifier.

Next, the terminal alkyl group-containing polymer [P
Examples of the alkyl mercaptan (B) used in the production of a] include n-hexyl mercaptan and n.
-Octyl mercaptan, n-dodecyl mercaptan,
Examples thereof include t-dodecyl mercaptan, cetyl mercaptan, and stearyl mercaptan. These can be used alone or in combination of two or more.

The alkyl mercaptan (B) is used to introduce an alkyl group at the terminal of the polymer [Pa] to impart surface activity, and in the alkyl mercaptan having less than 6 carbon atoms, It is not preferable because the stability during emulsion polymerization and the storage stability deteriorate. The amount of the alkyl mercaptan (B) used should be determined according to the desired molecular weight of the polymer [Pa], but usually 2 to 300 parts by weight relative to 100 parts by weight of the polymerizable monomer component (A). Used in the range of.

As the polymerization initiator used for the polymerization of the polymerizable monomer component (A), well-known oil-soluble or water-soluble polymerization initiators can be used, but the terminal alkyl group-containing polymer [Pa] is used efficiently. For good production, the amount used is preferably 1 mol or less, more preferably 0.1 mol or less, relative to 1 mol of the alkyl mercaptan (B).

The polymer [Pa] is obtained by bulk polymerization, solution polymerization,
It can be produced by any method such as suspension polymerization. The polymerization temperature is usually 50 to 150 ° C., and the polymerization time is 1 to 8
Time is common. As the solvent used in the solution polymerization, the polymerizable monomer component (A), the alkyl mercaptan (B), and the radical polymerization initiator are all dissolved,
In addition, any kind may be used as long as it does not inhibit radical polymerization.

The polymer [Pa] itself has a sufficient surface-active ability, but when it is used as a salt of the polymer [Pa] by neutralizing a part or all of the carboxyl groups, it serves as an emulsifier. The effect becomes even better. Examples of the neutralizing agent used here include alkali metal compounds such as sodium hydroxide and potassium hydroxide; alkaline earth metal compounds such as calcium hydroxide and calcium carbonate; ammonia; monomethylamine, dimethylamine, trimethylamine, mono Water-soluble organic amines such as ethylamine, diethylamine, triethylamine, monopropylamine, dimethylpropylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, and diethylenetriamine are listed, and one or more selected from these groups. Can be used. However, when the metal ion in the cured epoxy resin becomes a problem, it is preferable to use ammonia or low-boiling amines such as monomethylamine, dimethylamine and trimethylamine, which scatter at room temperature or by heating.

Next, as the monomer (C) used for producing the (meth) acrylic acid ester-based polymer particles [Pb], methyl, ethyl, propyl, isopropyl, butyl, isobutyl, octyl, 2- A (meth) acrylic acid ester which is an ester compound of a (meth) acrylic acid with a linear or branched aliphatic alkyl alcohol having 1 to 18 carbon atoms such as ethylhexyl, lauryl, stearyl or cyclohexyl or an alicyclic alkyl alcohol. Kinds; hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, hydroxyl group-containing unsaturated monomers such as monoesters of (meth) acrylic acid with polypropylene glycol or polyethylene glycol; epoxy group-containing unsaturated monomer such as glycidyl (meth) acrylate Aziridinyl group-containing unsaturated monomers such as (meth) acryloylaziridine and (meth) acryloyloxyethylaziridine; 2-
Isopropenyl-2-oxazoline, 2-vinyl-2-
Unsaturated monomers containing oxazoline group such as oxazoline; (meth) acrylic acid and ethylene glycol, 1,3
-Butylene glycol, 1,6-hexane glycol,
Polyfunctional (meth) acrylic acid esters containing two or more polymerizable unsaturated groups in the molecule such as esters with polyhydric alcohols such as neopentyl glycol, polyethylene glycol, polypropylene glycol and trimethylolpropane; ) Examples include allyl acrylate,
These can be used alone or in combination of two or more, and further, other copolymerizable monomers such as styrene, vinyltoluene, acronitrile, methacrylonitrile, vinyl acetate, divinyl. It is also possible to copolymerize an appropriate amount of benzene, diallyl phthalate or the like.

In producing the (meth) acrylic acid ester-based polymer particles [Pb], the monomer (C) is used so that the glass transition temperature of the obtained polymer particles [Pb] is 20 ° C. or lower. It is necessary to consider the type and combination of. If the glass transition temperature of the polymer particles [Pb] exceeds 20 ° C., a sufficient toughness improving effect cannot be obtained. A more preferable glass transition temperature of the polymer particles [Pb] is 0 ° C. or lower in the sense that the toughness of the obtained epoxy resin composition is further improved.

The lower the glass transition temperature of the polymer particles [Pb], the higher the toughness improving effect. However, the lower limit of the glass transition temperature of the polymer particles [Pb] obtained by polymerizing a (meth) acrylic acid ester-based monomer currently on the market is about −80 ° C. It is difficult to obtain (meth) acrylic acid ester-based polymer particles having a temperature.

When a monomer (C) having a functional group capable of reacting with a carboxyl group is used as the (meth) acrylic acid ester-based monomer (C), the above-mentioned emulsifier having a carboxyl group ( Since the (meth) acrylic acid ester-based polymer particles [Pb] are bonded more firmly, the toughening effect on the epoxy resin is further enhanced. As such a monomer (C), among those exemplified as the above-mentioned monomer (C), epoxy group-containing polymerizable monomers, aziridinyl group-containing polymerizable monomers, oxazoline group-containing polymerizable monomers Monomers are preferred.

Introducing an appropriate cross-linking structure into the (meth) acrylic acid ester-based polymer particles [Pb] is
It is effective in increasing the toughness of epoxy resin.
As the polymerizable monomer (C) capable of introducing such a crosslinked structure, among the monomers exemplified as the monomer (C), a polyfunctional compound having two or more polymerizable unsaturated groups in the molecule. Preferred examples thereof include a (meth) acrylic acid ester, divinylbenzene, diallyl phthalate, and allyl (meth) acrylate. However, the amount used
It should be suppressed to about 0.5 to 10 parts by weight, and if it exceeds 10 parts by weight, the toughening effect tends to decrease.

There are no particular restrictions on the emulsion polymerization method,
All conventionally known emulsion polymerization methods can be applied. For example, a method in which the above-mentioned terminal alkyl group-containing polymer [Pa] acting as an emulsifier is mixed together with the above-mentioned polymerizable monomer (C), a polymerization catalyst, and water for polymerization, or a so-called monomer dropping method or pre-emulsion method. Furthermore, the (meth) acrylic acid ester-based polymer particles [Pb] can be synthesized by a method such as a seed polymerization method or a multi-stage polymerization method. Polymerization is usually 0 to 100 ° C, preferably 50 to 80 ° C
The polymerization time of about 1 to 10 hours is sufficient.

The amount of the polymer [Pa] used as an emulsifier is not particularly limited, but is preferably 0.5 to 10 parts by weight, more preferably 1 to 3 parts by weight with respect to 100 parts by weight of the polymerizable monomer (C). It is a range of parts. However, in the production process of the epoxy resin composition as described below, the defoaming agent used for the purpose of suppressing foaming due to the emulsifier generated when water is distilled off reduces the physical properties of the epoxy resin cured product as an impurity. The cause is that the amount of polymer [Pa] used is 3
This is because if the amount is controlled to be not more than the weight part, almost no bubbles are generated even during dehydration, so that it is not necessary to use an antifoaming agent and the physical properties of the cured epoxy resin product are not deteriorated.

As the polymerization catalyst used in emulsion polymerization, all known catalysts can be used, but if there is a possibility that an alkali metal, chloride ion, etc. may adversely affect the cured epoxy resin, hydrogen peroxide, peracetic acid, diamine, etc. It is desired to use a polymerization catalyst such as -t-butyl peroxide and 4,4'-azobis (4-cyanopentanoic acid).

There are no particular restrictions on the epoxy resin used in the present invention, and any known epoxy resin can be appropriately selected and used according to its use and required characteristics. For example, bisphenol A, bisphenol F, phenol novolac, cresol novolac, brominated bisphenol A
Glycidyl ethers of phenols such as; glycidyl ethers of alcohols such as butanol, butanediol, polyethylene glycol, polypropylene glycol; glycidyl esters of acids such as hexahydrophthalic acid, dimer acid, etc. Other than the above, it is also possible to use two or more kinds in combination.

In producing the epoxy resin composition according to the present invention, the following method is recommended in terms of simplifying the process and preventing impurities from entering. That is, this is a method in which the emulsion of the (meth) acrylic acid ester-based polymer particles [Pb] is directly mixed with the epoxy resin and water is removed with stirring under normal pressure or reduced pressure.

In the methods proposed so far, a coagulant containing a metal is added, or the cloud point of a nonionic emulsifier is used to coagulate and precipitate rubber particles in an emulsion state, and then the epoxy resin is dried and then dried. It requires a plurality of steps of dispersing in a resin, and not only the steps are complicated, but also metal ions may be mixed in the composition to deteriorate the physical properties of the cured epoxy resin.

However, when the above-mentioned production method defined in the present invention is adopted, it is possible to easily obtain a resin composition in which (meth) acrylic acid ester polymer particles [Pb] are uniformly dispersed in the epoxy resin in one step. You can In this case, if an ordinary low-molecular weight emulsifier is used as an emulsifier and a similar dispersion is to be obtained, bubbles are significantly generated when water is removed and overflows from the container, so that dehydration becomes substantially impossible. .

The reason why the above-mentioned simple production method can be realized in the present invention is that the polymer [Pa] used as an emulsifier is used.
Has a high molecular weight and is strongly bound to the polymer particles [Pb], and therefore has less bubbles in the dehydration step, and the polymer [Pa] has reactivity with the epoxy resin. This is probably because the dispersibility is also good.

In producing the epoxy resin composition,
An emulsion of an epoxy resin and (meth) acrylic acid ester-based polymer particles [Pb] is put into a container equipped with a stirrer and a water removal port, and the mixture is 0 to 150 ° C, preferably 50 to
Water may be removed with stirring at 130 ° C. under reduced pressure of 1 mmHg to 760 mmHg or normal pressure, preferably reduced pressure of 30 mmHg to 600 mmHg.

The amount of the (meth) acrylate polymer particles [Pb] dispersed in the epoxy resin is preferably 1 part by weight to 50 parts by weight, more preferably 100 parts by weight in terms of solid content, based on 100 parts by weight of the epoxy resin. Is 2 to 30 parts by weight. (Meth) acrylic acid ester-based polymer particles [P
If the amount of b] is less than 1 part by weight, the toughening effect is hardly obtained, while if it exceeds 50 parts by weight, the viscosity of the epoxy resin composition becomes too high and the original properties of the epoxy resin are impaired.

The thus obtained epoxy resin composition of the present invention contains, if necessary, quartz glass powder, silica, clay, calcium carbonate, kaolin, talc, titanium oxide,
Of course, it is also possible to blend a filler such as aluminum hydroxide or a pigment.

The epoxy resin composition of the present invention can be used for various purposes by combining with various curing agents. Examples of the curing agent include diethylenetriamine,
Triethylenetetramine, tetraethylenepentamine,
Linear aliphatic amines such as diethylaminopropylamine; various polyamides having different amine values; alicyclic amines such as menthenediamine, isophoronediamine, bis (4-aminocyclohexyl) methane; m-xylenediamine, diamino Aromatic amines such as diphenylmethane, diaminodiphenylsulfone, and m-phenylenediamine; phthalic anhydride, tetrahydrophthalic anhydride,
Hexahydrophthalic anhydride, Methyltetrahydrophthalic anhydride, Methylhexahydrophthalic anhydride, Methyl nadic acid, Dodecyl succinic anhydride, Pyromellitic anhydride, Methylcyclohexene tetracarboxylic acid anhydride, Trimellitic anhydride, Polyazelaic anhydride Anhydrides such as compounds; phenolic hydroxyl group-containing compounds such as phenol novolac and cresol novolac; polymercaptans; 2,4,6-tris (dimethylaminomethyl)
Anionic polymerization catalysts such as phenol and 2-ethyl-4-methylimidazole; Cationic polymerization catalysts such as BF ₃ monoethylamine complex; Dicyandiamide, amine adduct, hydrazide, amidoamine, blocked isocyanate, carbamate, ketimine, aromatic diazonium Examples include latent curing agents such as salts,
One type or two or more types can be used.

[0034]

The epoxy resin composition of the present invention is a uniform dispersion of (meth) acrylic acid ester-based polymer particles in an epoxy resin, to which a dissolution / reaction-deposition type rubber is added. Unlike the conventional toughening epoxy resin composition, there is almost no change in toughening effect due to curing conditions,
Further, since the rubber component dissolved in the epoxy resin is substantially zero, the heat resistance is not deteriorated. Moreover, as compared with the one toughened by the conventional rubber particle emulsion addition method, since the shear component does not exist, a small amount of the compound shows an excellent toughening effect.

Further, by using a polymer having a specific structure having a terminal alkyl group as an emulsifier, foaming during dehydration during production of an epoxy resin composition can be suppressed, and the production becomes extremely simple. Further, the terminal alkyl group-containing polymer used as the emulsifier has reactivity with the epoxy resin, and since these are also distributed in the epoxy resin in a bound state, the obtained epoxy resin composition is tough and It is extremely excellent in water resistance (moisture resistance) and adhesiveness and can be effectively used as an adhesive, a molding material, a paint, a sealant and the like.

[0036]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In the examples, "%" and "parts" mean "% by weight" and "parts by weight" unless otherwise specified.

Reference Example 1 (Production of Emulsifier) 180 parts of isopropyl alcohol was charged into a flask equipped with a stirrer, a reflux condenser, a nitrogen introducing tube, a thermometer, and a dropping funnel, and heated to 81 ° C. while blowing nitrogen. The isopropyl alcohol was refluxed for 10 minutes. Next, 53.6 parts of acrylic acid prepared in advance, 16.5 parts of lauryl methacrylate, and Bremmer PE-200 (polyethylene glycol monomethacrylate manufactured by NOF CORPORATION) 91
Parts, n-13.7 parts of dodecyl mercaptan and 2,2 ^'- azobisisobutyronitrile (AIBN) consisting 0.4 parts polymerizable monomer mixture was added dropwise over 2 hours in the flask. After completion of the dropping, the mixture was aged under reflux for 1 hour to obtain a polymer containing a terminal alkyl group having a solid content of 49.1% [Pa-
1] solution was obtained. The acid value of this polymer [Pa-1] is 2
39, the number average molecular weight was 2,300.

Reference Example 2 (Production of Emulsifier) A polymerizable monomer mixture comprising 70 parts of methacrylic acid, 91 parts of Bremmer PE200 (same as above), 17 parts of n-dodecyl mercaptan and 0.4 parts of AIBN. Polymerization was carried out in the same manner as in Reference Example 1 except that the mixture was used, and the solid content was 49.5%.
-2] was obtained. The acid value of this polymer [Pa-2] was 256, and the number average molecular weight was 2,100.

Reference Example 3 (Production of Emulsifier) As a polymerizable monomer mixture, 145 parts of acrylic acid, 16 parts of styrene, 18 parts of stearyl mercaptan and AIB.
Polymerization was performed in the same manner as in Reference Example 1 except that a polymerizable monomer mixture containing 0.4 part of N was used to obtain a solution of a terminal alkyl group-containing polymer [Pa-3] having a solid content of 49.6%.
The acid value of this polymer [Pa-3] was 630, and the number average molecular weight was 2,800.

Examples 1 to 5 and Comparative Examples 1 to 7 (1) Production of (meth) acrylic acid ester-based polymer A flask equipped with a dropping funnel, a stirrer, a nitrogen introducing tube, a thermometer and a reflux condenser was pure. 63 parts of water was charged and heated to 70 ° C. while gently blowing nitrogen gas. on the other hand,
85 parts of ethyl acrylate, 10 parts of methyl methacrylate,
5 parts of glycidyl methacrylate, 4.1 parts of a solution of the terminal alkyl group-containing polymer [Pa-1] obtained in Reference Example 1, 28
% 0.5% ammonia water and 36 parts ion-exchanged water were thoroughly stirred beforehand and charged into the dropping funnel as a fully emulsified pre-emulsion.

Next, 8 parts of a 5% aqueous solution of 4,4'-azobis (4-cyanopentanoic acid) neutralized with ammonia was poured into the flask, and the above pre-emulsion was added from a dropping funnel over 3 hours and 30 minutes. Dropped. After the dropping was completed, the dropping funnel was washed with 10 parts of ion-exchanged water so that the pre-emulsion did not remain, and the washing solution was added into the flask.
During the dropping of the pre-emulsion, the temperature is maintained at 70 to 75 ° C. After the dropping, the polymerization is terminated by further stirring at the same temperature for 2 hours to give a (meth) acrylic acid ester-based polymer emulsion with a nonvolatile content of 46.0% [1. ] Was obtained.

Further, a (meth) acrylic acid ester-based polymer emulsion was prepared in the same manner as described above except that the terminal alkyl group-containing polymer solution used as the emulsifier and the polymerizable monomer component were changed to those shown in Table 1. [2] to [5] and comparative emulsions [C1] to [C4] were obtained. still,
In Table 1, the glass transition temperature of the emulsion polymer particles is shown as Per after the water is volatilized and removed from the emulsion.
Kind Elmer's differential scanning calorimeter "DSC-"
7 ”.

[0043]

[Table 1]

(2) Production of Epoxy Resin Composition (meth) acrylic acid ester-based polymer emulsions [1] to [5] obtained in the above (1) and comparative emulsion [C
1] to [C4] were placed in a flask equipped with a stirrer, a nitrogen inlet tube, and a condenser, and ion-exchanged water was added to adjust the nonvolatile concentration to 30%. A predetermined amount of Epicoat 828 (bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) was added and stirred to obtain a uniform viscous liquid.
Then, raise the temperature to 70 ° C and gradually increase the degree of vacuum,
Finally, the pressure was reduced to 50 mmHg to remove water. Then 13
While heating to 0 ° C. to completely remove water, the carboxyl group in the emulsifier (terminal alkyl group-containing polymer) was preliminarily reacted with the epoxy resin.

The constitution of the obtained epoxy resin composition (the measuring method is as follows) is shown in Table 2. In addition, in the case of using the comparative emulsions [C1] to [C3], since foaming during dehydration was so strong that water could not be removed to the end, 0.3 part of San Nopco 8034L (manufactured by San Nopco) was added as an antifoaming agent. The same operation was performed from. <Water content in epoxy resin composition> Karl-Fischer Moist
The water content in the epoxy resin composition was measured using a ure meter (KYOTO ELECTRONICS MKS-3p). <Reaction rate of carboxyl group in emulsifier> By titration with 0.1N-NaOH, the amount of carboxyl group per 1 g of (meth) acrylic acid ester-based polymer particles before and after dispersion of epoxy resin was measured, and the reaction rate was calculated from the ratio. It was calculated.

[0046]

[Equation 1]

<Epoxy equivalent> HCl / THF was reacted, and excess HCl was measured by back titration. (3) Cured Product Properties of Epoxy Resin Composition <Adhesion Test> The epoxy resin composition obtained in (2) above was mixed with a curing agent in the ratio shown in Table 2 and an adhesion test was conducted.
As the adherend, a cold-rolled steel sheet having a thickness of 1.5 mm (T-type peeling test: 0.5 mm) was ground with # 100 sandpaper, washed with acetone and degreased. Curing of the adhesive is 80
After heating at 0 ° C for 1 hour, heating was further performed at 150 ° C for 0.5 hour, and the results are shown in Table 2. Tensile shear strength : Performed according to JIS K 6850. Tensile speed 10 mm / min. Warm water resistance : After being immersed in warm water of 80 ° C. for 24 hours, the strength was measured at room temperature (23 ° C.) to examine the warm water resistance. T-type peel strength : Performed according to JIS K 6854. Pulling speed 50 mm / min.

[0048]

[Table 2]

As is clear from Table 2, the epoxy resin composition of the present invention shows little decrease in tensile shear strength after immersion in hot water at 80 ° C. and is also very excellent in T-type peel strength. I understand.

Examples 6 to 12 and Comparative Examples 8 to 12 (1) Production of (meth) acrylic acid ester-based polymer (meth) acrylic acid ester-based polymer emulsions [1] to [5] shown in Table 1 and [C1] to [C4] were used. (2) Production of Epoxy Resin Composition An epoxy resin composition was produced in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 7. Table 3 shows the composition of the obtained epoxy resin composition. (3) Properties of Cured Product of Epoxy Resin Composition The epoxy resin composition obtained in (2) above is mixed with a curing agent in the compounding ratio shown in Table 3 and then molded, and various physical properties of the molded product are tested. The results are also shown in Table 3. The molded product was cured by heating at 85 ° C. for 3 hours and then at 150 ° C. for 3 hours.

<Fracture toughness value> A test piece of the size shown in FIG. 1 was prepared, and a starter crack was made at the tip of the central cutout portion with a razor, and a load-time curve (FIG. 2) was obtained at a speed of 10 mm / min. Then, the fracture toughness value was calculated from the load (Pc) at the time of fracture, the crack length (a), etc. by the following formula.

[0052]

[Equation 2]

<Deflection temperature under load> In accordance with JIS K 7207,
It was measured using Toyo Seiki's HDT & VSPT TESTER. <Water Absorption> The water absorption of a test piece having a thickness of 3 mm was immersed in warm water at 80 ° C. for 24 hours, and the water absorption was determined by the following formula.

[0054]

[Equation 3]

[0055]

[Table 3]

As is clear from Table 3, the epoxy resin composition of the present invention has an increased fracture toughness value without lowering the deflection temperature under load, and has an excellent water absorption rate as compared with conventional materials. It turns out that Further, as is clear from comparison between Example 11 and Comparative Example 10, when compared at the same deflection temperature under load, the cured product of the epoxy resin composition according to the present invention is an epoxy that is toughened by CTBN rubber. It can be seen that the fracture toughness value is twice or more that of the resin composition.

[Brief description of drawings]

FIG. 1 is a dimensional explanatory diagram of a fracture toughness value measurement sample used in Examples.

FIG. 2 is a graph showing a load-time relationship when measuring a fracture toughness value.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masuji Izumibayashi 5-8 Nishimitabicho Suita City, Osaka Prefecture Nippon Shokubai Co., Ltd. Central Research Laboratory (56) Reference JP-A-58-206604 (JP, A) JP-A-58-206603 (JP, A) JP-A-51-49300 (JP, A) JP-B 2-14095 (JP, B2) International publication 89/12618 (WO, A)

Claims (4)

[Claims] 1. A water-soluble compound obtained by polymerizing a polymerizable monomer component (A) containing an unsaturated carboxylic acid as an essential component in the presence of an alkylmercaptan (B) having 6 to 18 carbon atoms. A water-dispersible terminal alkyl group-containing polymer [Pa] having an acid value of 200 or more and / or a reactive surfactant composed of a salt thereof is used as an emulsifier, and a (meth) acrylic acid ester-based monomer (C) is added. An epoxy resin composition characterized in that (meth) acrylic acid ester-based polymer particles [Pb] having a glass transition temperature of 20 ° C. or lower, which are obtained by emulsion polymerization, are dispersed in an epoxy resin. 2. The epoxy resin composition according to claim 1, wherein the (meth) acrylic acid ester-based polymer particles [Pb] have a crosslinked structure. 3. The epoxy resin composition according to claim 1, wherein the (meth) acrylic acid ester-based polymer particles [Pb] have a functional group capable of reacting with a carboxyl group in the molecule. 4. The method according to claim 1, wherein the emulsion of the (meth) acrylic acid ester-based polymer particles [Pb] is uniformly mixed with an epoxy resin, and then water is removed. Method for producing epoxy resin composition.