JPH0616788A - Particulate curing agent or particulate curing accelerator, epoxy resin composition containing the same, and curing method - Google Patents

Abstract

(57) [Abstract] [Purpose] A particulate latent curing agent or curing accelerator that can be used in a one-pack type epoxy resin composition, and an epoxy resin composition using the same that is excellent in storage stability and curability. An article and a method for curing the same are provided. [Structure] Fine particles made of an aromatic thermoplastic polymer having a carbonyl group or a sulfonyl group in the molecule contain a curing agent or a curing accelerator. By blending this with an epoxy resin, an epoxy resin composition having good heat curability can be obtained.

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 uses a fine particle curing agent or a fine particle curing accelerator having good storage stability and mechanical strength and does not undergo a curing reaction before use. The present invention relates to a curing method of causing a curing reaction by

[0002]

BACKGROUND OF THE INVENTION Epoxy resins are used in a wide variety of applications such as adhesives, paints, coating agents, encapsulants and laminates. Further, these epoxy resins usually contain various curing agents and curing accelerators.

The widely used epoxy resin composition includes
There is a so-called two-pack type composition in which a curing agent or a curing accelerator such as an amine, a Lewis acid, or an acid anhydride is mixed with an epoxy resin immediately before it is used. In such a two-component type, the epoxy resin and the curing agent are separately stored and used by mixing them as needed, but since the pot life after mixing is relatively short, a large amount should be mixed. Can not be kept, and therefore
When it is used in a large amount, it is necessary to mix it in small amounts many times, resulting in extremely poor work efficiency.

On the other hand, as a means for solving such a problem, a latent curing agent is used, which does not cause a curing reaction even if preliminarily compounded in an epoxy resin and causes a curing reaction by light irradiation or heating. Various one-pack types have been proposed. However, even if these latent curing agents are used, those having excellent storage stability when blended with an epoxy resin are
The curing reaction must be carried out under relatively high temperature conditions, and those that cure under low temperature conditions have the problem of poor storage stability, and those that have a good balance of both storage stability and curability The reality is that it has not been developed yet.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the conventional one-pack type epoxy resin composition and to provide a latent curing agent or curing accelerator that can be used in one-pack type. And Another object of the present invention is to provide an epoxy resin composition containing the above-mentioned curing agent, which has good storage stability and undergoes a curing reaction promptly during use. Furthermore, it aims at providing the curing method of this epoxy resin composition.

[0006]

Therefore, as a result of intensive studies by the present inventors, a curing agent or a curing accelerator was incorporated into fine particles of a thermoplastic polymer having a specific composition to form fine particles. It has been found that the above object can be achieved by blending a resin with an epoxy resin to form a resin composition, and completed the present invention.

That is, the present invention has an average particle size of less than 200 μm, which is composed of a thermoplastic polymer obtained by polycondensing an aromatic monomer having a carbonyl group or a sulfonyl group in the molecule, alone or with another monomer. Melting point of 200 ℃
Providing a particulate curing agent characterized by containing 5 to 50% by weight of the following curing agent, an aromatic monomer having a carbonyl group or a sulfonyl group in the molecule alone or with another monomer Provided is a fine particle-shaped curing accelerator, characterized by containing 5 to 50% by weight of a curing accelerator having a melting point of 200 ° C. or less in fine particles of a thermoplastic polymer formed by polycondensation and having an average particle diameter of less than 200 μm. Provide an epoxy resin composition in which an epoxy resin contains these fine particle curing agent and / or fine particle curing accelerator, and further heat the epoxy resin composition to a predetermined temperature or higher to form a fine particle curing agent. Disclosed is a method for curing an epoxy resin composition, which comprises dissolving in an epoxy resin and conducting a curing reaction.

The fine particle curing agent or the fine particle curing accelerator of the present invention contains the curing agent or the curing accelerator in the fine particles of the thermoplastic polymer, and the average particle diameter thereof is less than 200 μm. , And preferably 30 μm or less. When the average particle size is 200 μm or more, when the epoxy resin composition is blended with the epoxy resin, it cannot be contained homogeneously, so that not only the curing reaction does not occur uniformly, but also the curing time becomes long, which is preferable. Absent.
The average particle size as referred to in the present invention is calculated from a particle size distribution chart using a sedimentation type particle size distribution measuring device.

In the present invention, the thermoplastic polymer constituting the above-mentioned particulate curing agent or particulate curing accelerator is obtained by independently polycondensing an aromatic monomer having a carbonyl group or a sulfonyl group in the molecule. Alternatively, it can be obtained by copolycondensing these monomers with other polycondensable monomers. The thermoplastic polymer obtained has a high mechanical strength and preferably has a glass transition temperature of 120 ° C. or higher in order to withstand the shear stress applied during compounding and mixing with the epoxy resin. Further, in the present invention, those having a weight average molecular weight of about 2,000 to 1,000,000 are preferable from the viewpoints of fine particle formation and cured film formation from an epoxy resin composition. Specific examples of such a thermoplastic polymer include aromatic thermoplastic resins such as polysulfone, polyether sulfone, polyarylate, polycarbonate, polyether ether ketone, polyallyl sulfone, and polyetherimide.

On the other hand, the curing agent or curing accelerator contained in the above-mentioned particulate curing agent or particulate curing accelerator has a melting point of 200 ° C. or less, preferably 1 from the viewpoint of curability.
Those at 50 ° C. or lower are used, and they may be liquid or solid at room temperature. From the viewpoint of uniform curing reactivity and storage stability, these fine particle curing agents or fine particle curing accelerators contain 5 to 50% by weight, preferably 10 to 30% by weight of the above curing agents or curing accelerators. It is contained. If the blending amount is less than 5% by weight, the curing time tends to be long, and if the blending amount exceeds 50% by weight, the amount of the thermoplastic polymer becomes small and the mechanical strength of the fine particles is insufficient. In addition, the storage stability when blended with the epoxy resin decreases, which is not preferable.

Specific examples of such a curing agent include aliphatic tertiary amines such as tributylamine, benzyldimethylamine, 2- (dimethylaminomethyl) phenol and 2,4,6-tris (diaminomethyl) phenol. Such as aromatic tertiary amines and alicyclic tertiary amines, or modified amines thereof, 2-methylimidazole, 2
-Ethylimidazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, 2-dodecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1
-Imidazoles such as benzyl-2-methylimidazole and 1-cyanoethyl-2-methylimidazole, and these imidazoles and acetic acid, lactic acid, salicylic acid, benzoic acid, adipic acid, phthalic acid, citric acid, tartaric acid, maleic acid, triacid An imidazole carboxylate with a meritic acid, a Lewis acid such as boron trifluoride, phosphorus pentafluoride, or the like can be used. In the present invention, a sufficient curing reaction occurs even if a small amount of these curing agents is blended,
Any known amount of a commonly used curing accelerator may be added.

Further, as the curing accelerator that is contained in the fine particles to accelerate the curing reaction, specifically, alkyl-substituted guanidines such as ethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, and the like, 3
-(3,4-Dichlorophenyl) -1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (4-
3-substituted phenyl-1,1-dimethylureas such as chlorophenyl) -1,1-dimethylurea, 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-imidazole such as 2-heptadecylimidazoline, Monoaminopyridines such as 2-aminopyridine, N, N-dimethyl-N- (2-hydroxy-
Examples thereof include amine imides such as 3-allyloxypropyl) amine-N′-lactoimide, triphenylphosphine and salts thereof.

The particulate curing agent or particulate curing accelerator of the present invention containing the above curing agent or curing accelerator in a particulate thermoplastic polymer is, for example, a spray dry method, a coacervation method, or a liquid. It can be obtained by a method such as a medium drying method. The contained state of the curing agent or the curing accelerator in the obtained fine particles is a state in which the curing agent or the curing accelerator is dispersed in the matrix formed from the thermoplastic polymer, a so-called core-shell state, or the like. Any of these may be used, but the former one containing the dispersed state is preferable from the viewpoint of uniform curing reactivity and mechanical strength. Depending on the purpose, a curing agent and a curing accelerator may be contained together in the form of fine particles.

The epoxy resin composition of the present invention contains 1 to 80 parts by weight, preferably 3 to 40 parts by weight of the above-mentioned fine particle curing agent and / or fine particle curing accelerator with respect to 100 parts by weight of the epoxy resin in terms of curability. It can be obtained by blending in a proportion of parts by weight, and if necessary, a latent curing agent, various fillers, additives and the like.

The epoxy resin used may be liquid or solid, and usually has an epoxy equivalent of 100 to 3
Those having an average of two or more epoxy groups in one molecule, which are about 500, can be preferably used. Specifically, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a cycloaliphatic epoxy resin, a hydantoin epoxy resin, a novolac type epoxy resin, a glycidyl ester type epoxy resin, etc. may be used alone or in combination of two or more. it can. Of these, the bisphenol A type epoxy resin is preferably used from the viewpoints of compatibility with the thermoplastic polymer constituting the fine particles, practicality, and economy.

As the latent curing agent that can be optionally blended, a latent curing agent used for heat curing as a curing agent for an epoxy resin can be usually used, and specifically, dicyandiamide type, imidazole type, phenol System, acid anhydride system, acid hydrazide system, fluorinated boron compound system,
Examples thereof include amine imide-based and amine-based epoxy resin curing agents, and these can be used alone or in combination of two or more kinds. The above curing agent is added and mixed in a range of 40 parts by weight or less with respect to 100 parts by weight of the epoxy resin.

Further, as a filler which can be contained in the epoxy resin composition of the present invention as required, silica, clay, gypsum, calcium carbonate, barium sulfate,
Quartz powder, glass fiber, kaolin, mica, alumina, hydrated alumina, aluminum hydroxide, talc, dolomite, zircon, titanium compounds, molybdenum compounds, antimony compounds and the like, silane coupling agents and pigments, antioxidants, Other optional additive components can be appropriately blended depending on the purpose and application. Also, in order to weld to the members to be joined by spot welding, etc., copper or zinc,
It is also possible to add metal powder of nickel, cadmium, stainless steel, aluminum, silver, etc., preferably zinc, nickel, stainless steel, aluminum to impart conductivity to the composition of the present invention. In the case of imparting conductivity, it is preferable to add 25% by weight or more of the above metal powder to the epoxy resin composition.

The composition of the present invention containing the above components is uniformly dispersed at room temperature using a roll, a mixer, a Henschel mixer, a ball mill, a kneader, a disper, and the like.
The composition of the present invention can be obtained by mixing.

The above-mentioned epoxy resin composition is heated to a predetermined temperature or higher to dissolve the thermoplastic polymer constituting the particulate curing agent or the particulate curing accelerator in the epoxy resin to cause a curing reaction. The heating temperature varies depending on the type and amount of the thermoplastic polymer and the type and amount of the epoxy resin, but usually 6
Heat to a temperature of about 0 to 150 ° C. By heating in this way, the thermoplastic polymer forming the fine particles gradually becomes compatible with the epoxy resin, and the curing agent or curing accelerator contained therein causes a curing reaction with the epoxy resin. The compatibility mechanism between the thermoplastic polymer and the epoxy resin is not clear, but it is presumed that the carbonyl group and sulfonyl group present in the thermoplastic polymer are involved.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. In the following, parts and% in the text mean parts by weight and% by weight.

Example 1 Polysulfone (trade name: Udel P-3500, manufactured by Amoco, Tg189 ° C.) as a thermoplastic polymer, and 1-benzyl-2-methylimidazole (melting point 40-50 ° C.) as a curing agent. Was used to obtain the particulate curing agent of the present invention by an in-liquid drying method. The particulate curing agent was spherical with an average particle size of 8 μm, and the elemental analysis revealed that the curing agent content was 20%. A scanning electron micrograph of the particle structure of the obtained particulate curing agent is shown in FIG.

Twenty parts of the particulate curing agent thus obtained was mixed with bisphenol A type epoxy resin (epoxy equivalent of about 190, weight average molecular weight of 380, viscosity of 125 poise (2
5 ° C.)) 100 parts, kneaded in a mixing pot at room temperature for 1 hour, and further passed through a three-roll mill to obtain an epoxy resin composition of the present invention.

Example 2 The epoxy resin composition of the present invention was prepared in the same manner as in Example 1 except that the content of the curing agent in the particulate curing agent was 40% and the compounding amount of the epoxy resin composition was 10 parts. Got

Comparative Example 1 An epoxy resin composition was obtained in the same manner as in Example 1 except that the content of the curing agent in the particulate curing agent was 4% and the compounding amount in the epoxy resin composition was 100 parts. .

Comparative Example 2 Example 1 was repeated except that the curing agent content in the particulate curing agent was 60% and the number of compounding parts in the epoxy resin composition was 7 parts.
An epoxy resin composition was obtained in the same manner as.

Comparative Example 3 Epoxy was prepared in the same manner as in Example 1 except that 1-benzyl-2-methylimidazole was used in place of the particulate curing agent and the compounding amount in the epoxy resin composition was 4 parts. A resin composition was obtained.

Example 3 Average particle size was the same as in Example 1 except that the thermoplastic polymer used in Example 1 was replaced with polyether sulfone (trade name: Victrex 100P, manufactured by ICI Corporation, Tg 225 ° C.). A particulate curing agent having a diameter of 10 μm (curing agent content 18%) was obtained, and an epoxy resin composition of the present invention was obtained in the same manner as in Example 1.

Example 4 Amorphous polyarylate as a thermoplastic polymer (trade name: U polymer (U-100), manufactured by Unitika Ltd., Tg2)
03 ° C.) and 2-undecylimidazole (melting point: 71 ° C.) as a curing agent to obtain a particulate curing agent of the present invention by a coacervation method. The particulate curing agent was spherical with an average particle size of 9 μm, and the elemental analysis revealed that the curing agent content was 32%.

Thirteen parts of the particulate hardener thus obtained was mixed with bisphenol A type epoxy resin (epoxy equivalent of about 190, weight average molecular weight of 380, viscosity of 125 poise (2).
5 ° C.)) 100 parts, kneaded in a mixing pot at room temperature for 1 hour, and further passed through a three-roll mill to obtain an epoxy resin composition of the present invention.

Comparative Example 4 An epoxy resin composition was prepared in the same manner as in Example 4 except that 2-undecylimidazole was used in place of the particulate curing agent, and the compounding amount in the epoxy resin composition was 4 parts. Got

Example 5 Example 4 was repeated except that the thermoplastic polymer used in Example 4 was replaced by polyetherimide (trade name: Ultem 1000, manufactured by GE Plastics Co., Ltd., Tg 217 ° C.).
In the same manner as in (1), a fine particle curing agent having an average particle size of 15 μm (curing agent content: 25%) was obtained, and the epoxy resin composition of the present invention was obtained in the same manner as in Example 4.

Example 6 The average particle size was 7 μm in the same manner as in Example 1 except that the curing agent used in Example 1 was replaced with benzyldimethylamine.
m of the particulate hardener (hardener content 20%) was obtained, and 15 parts of this particulate hardener was added to 100 parts of the epoxy resin used in Example 1 and mixed to obtain the epoxy resin composition of the present invention. It was

Comparative Example 5 An epoxy resin composition was obtained in the same manner as in Example 6 except that benzyldimethylamine was used in place of the particulate curing agent and the compounding amount in the epoxy resin composition was 3 parts. It was

Example 7 The thermoplastic polymer used in Example 6 was polyallyl sulfone (trade name: Radel A-100, manufactured by Amoco, T
g 220 ° C.), but in the same manner as in Example 6 except that the curing agent has a mean particle size of 10 μm and is in the form of fine particles (curing agent content 15%).
Then, the epoxy resin composition of the present invention was obtained in the same manner as in Example 6.

Comparative Example 6 An average was obtained in the same manner as in Example 1 except that the thermoplastic polymer used in Example 1 was changed to polymethyl methacrylate (trade name: Sumipec-B, manufactured by Sumitomo Chemical Co., Ltd., Tg 105 ° C.). Fine particle type hardener with a particle size of 6 μm (hardener content 1
8%), and 23 parts of this particulate curing agent was added to 100 parts of the epoxy resin used in Example 1 and mixed to obtain the epoxy resin composition of the present invention.

Comparative Example 7 The same procedure as in Example 1 was repeated except that the thermoplastic polymer used in Example 1 was changed to polystyrene (trade name: Denka Butyral HRM-2, manufactured by Denki Kagaku Kogyo Co., Ltd., Tg 100 ° C.). Hardening agent with a particle size of 8 μm (hardening agent content 1
6%) and 25 parts of this particulate curing agent was added to 100 parts of the epoxy resin used in Example 1 and mixed to obtain the epoxy resin composition of the present invention.

Example 8 The procedure of Example 1 was repeated except that 4 parts of dicyandiamide was added to the epoxy resin composition as a latent curing agent.
An epoxy resin composition of the present invention was obtained in the same manner as in Example 1.

Example 9 40 parts of the epoxy resin composition of Example 3 was added with 4 parts of dicyandiamide as a latent curing agent and bisphenol A.
An epoxy resin composition of the present invention was obtained in the same manner as in Example 3 except that 60 parts of the type epoxy resin (the same as above) was blended. In addition, 1 contained in the fine particles in the case of this example
-Benzyl-2-methylimidazole was used as a curing accelerator.

Comparative Example 8 In Example 8 (or Example 9), 1-benzyl-2-methylimidazole was used in place of the fine particle curing agent (or fine particle curing accelerator), and was added to the epoxy resin composition. An epoxy resin composition was obtained in the same manner as in Example 8 (or Example 9), except that the compounding number of 1 was 1.

Example 10 The polyether sulfone used in Example 3 and 3- (3,4-dichlorophenyl) -1,1 as a curing accelerator.
Using dimethylurea (melting point 158 ° C.), a particulate curing accelerator of the present invention was obtained by a submerged drying method. The particulate curing accelerator was spherical with an average particle size of 10 μm, and the elemental analysis revealed that the curing accelerator content was 33%.

The particulate curing accelerator 1 thus obtained
5 parts, 100 parts of bisphenol A type epoxy resin (epoxy equivalent of about 190, weight average molecular weight of 380, viscosity of 125 poise (25 ° C.)), 8 parts of dicyandiamide as a latent curing agent at room temperature for 1 hour. The mixture was kneaded and further passed through a three-roll mill to obtain the epoxy resin composition of the present invention.

COMPARATIVE EXAMPLE 9 3- (3,4-dichlorophenyl) -1,1-dimethylurea was used in place of the particulate curing accelerator, and the compounding amount in the epoxy resin composition was changed to 5 parts. An epoxy resin composition was obtained in the same manner as in Example 10.

The properties of the epoxy resin compositions obtained in the above Examples and Comparative Examples were measured according to the test methods shown below, and the results are shown in Table 1.

<Mechanical Stability> Each composition was passed through a three-roll mill and the shape before and after passing was observed with an optical microscope. The judgment is as follows. ◯: No change was observed before and after passing the roll. X: The particulate curing agent is crushed after passing through the roll.

<Dissolution start temperature> Each composition was placed under a temperature rising rate condition of 10 ° C./min, and the behavior of the thermoplastic polymer constituting the fine particles dissolved in the epoxy resin was observed with an optical microscope to find that dissolution The starting temperature was measured. The dissolution behavior of the epoxy resin composition obtained in Example 1 is shown in FIG. 2 as a typical dissolution behavior. Although it did not dissolve at 25 ° C, it started to dissolve at 90 ° C and completely dissolved at 100 ° C to generate bubbles.

<Reaction Initiation Temperature> Temperature at which exothermic peak begins to rise using a differential thermal analyzer (curing reaction initiation temperature)
Was measured.

<Storage Stability> The composition was stored under the conditions of 20 ° C. and 40 ° C., the change with time of viscosity was observed, and the number of days required until the viscosity became 3 times or more of the initial viscosity was measured.

<Curing Property> The curing time at 120 ° C. was measured by the hot plate gel time measuring method. In addition, about Example 10 and the comparative example 9, the measurement temperature was 150 degreeC.

<Adhesiveness> Steel plate (SPCC-SD: 100
Adhesive area 25 × 12.5m on × 25 × 1.6 ^t mm)
m and a layer thickness of 0.12 mm, and cured at 120 ° C. for 15 minutes to prepare a test piece. In addition, Example 1
For 0 and Comparative Example 9, the curing condition was 150 ° C. × 15.
Minutes.

The shear adhesion of the obtained test piece was measured using a Tensilon tensile tester (pulling speed: 5 mm).
/ Min, measurement temperature 23 ° C).

[0051]

[Table 1]

[0052]

INDUSTRIAL APPLICABILITY As described above, the fine particle curing agent or the fine particle curing accelerator of the present invention can be easily blended with an epoxy resin and has sufficient mechanical strength, and has storage stability and curability. It is intended to provide a well-balanced epoxy resin composition excellent in various properties such as.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (× 5000) showing the particle structure of the particulate curing agent obtained in Example 1.

FIG. 2 is an optical electron micrograph (400 times magnification) sequentially showing a process in which the thermoplastic polymer forming the fine particles is dissolved in the epoxy resin by heating the epoxy resin composition obtained in Example 1. ), And (A) 25 ° C.,
(B) 90 ° C, (C) 100 ° C.

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[Procedure amendment]

[Submission date] May 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (× 5000) showing the particle structure of the particulate curing agent obtained in Example 1.

FIG. 2 is a scanning electron micrograph (400 ×) showing a particle structure that changes when the epoxy resin composition obtained in Example 1 is heated to 25 ° C.

FIG. 3 is a scanning electron micrograph (400 ×) showing a particle structure that changes when the epoxy resin composition obtained in Example 1 is heated to 90 ° C.

FIG. 4 is a scanning electron micrograph (400 ×) showing a particle structure that changes when the epoxy resin composition obtained in Example 1 is heated to 100 ° C.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

Claims (6)

[Claims] 1. An average particle diameter 2 comprising a thermoplastic polymer obtained by polycondensing an aromatic monomer having a carbonyl group or a sulfonyl group in the molecule, alone or with another monomer.
A particulate curing agent, characterized in that 5 to 50% by weight of a curing agent having a melting point of 200 ° C. or less is contained in fine particles of less than 00 μm. 2. An average particle size 2 comprising a thermoplastic polymer obtained by polycondensing an aromatic monomer having a carbonyl group or a sulfonyl group in the molecule, alone or with another monomer.
A particulate curing accelerator comprising 5 to 50% by weight of a curing accelerator having a melting point of 200 ° C. or less in fine particles of less than 00 μm. 3. An epoxy resin composition comprising an epoxy resin containing the particulate hardener according to claim 1. 4. An epoxy resin composition comprising an epoxy resin containing the particulate curing accelerator according to claim 2. 5. The epoxy resin composition according to claim 3, further comprising a heat-curable latent curing agent. 6. An epoxy resin composition, characterized in that the epoxy resin composition according to any one of claims 3 to 5 is heated to a predetermined temperature or higher to dissolve the thermoplastic polymer in the epoxy resin and cause a curing reaction. How to cure things.