JP2003313273A - Epoxy resin curing agent and epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an epoxy resin curing agent having high heat resistance and excellent processability. <P>SOLUTION: The epoxy resin curing agent is obtained by heat treating a maleic acid and/or a maleic anhydride and a diamine at a molar ratio of 0.4-2.0:1.0 at 80-200°C in the presence of a novolak type phenolic resin to be added in an amount of 10-90 wt.% and in the absence of a solvent. An epoxy resin composition comprises the above epoxy resin curing agent and an epoxy resin as the essential components. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin curing agent and an epoxy resin composition. More specifically, it relates to an epoxy resin curing agent having high heat resistance and excellent workability, and an epoxy resin composition containing the same.

[0002]

2. Description of the Related Art Epoxy resins are widely used in a wide variety of fields such as electricity, electronics, civil engineering and paints. Since the characteristics of the epoxy resin composition vary greatly depending on not only the type of the epoxy resin monomer as the main component but also the type of the curing agent, selection of the curing agent occupies a great weight in developing the epoxy resin composition. Conventionally, as curing agents, aliphatic amines,
Aromatic amines, acid anhydrides, imidazoles, novolac type phenolic resins and the like are often used. However, the performance of the epoxy resin cured product obtained from these cured products is low in the softening point, or even when using an acid anhydride that gives a cured product with a relatively high softening point, the curing time is long and the electrical resistance is high. The obtained properties were not sufficient, such as the inferior properties. Under such circumstances, imide-based curing agents have been proposed in order to obtain a cured product having higher heat resistance. Examples thereof include those having a structure in which a diamine is added to bismaleimide, and those having a structure in which a terminal of a chain-like polyimide resin is an amino group. However, these curing agents have the drawbacks that the raw materials are expensive and the fluidity of the resin composition is lowered, resulting in poor processability, and they have not been put into practical use.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of intensive studies in view of such problems of conventional epoxy resin cured products, and is an epoxy resin curing agent having high heat resistance and excellent processability. And an epoxy resin composition containing the same.

[0004]

Means for Solving the Problems The present inventor, when a maleic acid or its anhydride and a diamine are reacted in the absence of a solvent to obtain an epoxy resin curing agent, the reaction is carried out in the presence of a novolac type phenol resin. As a result, it has become possible to further improve the fluidity of the epoxy resin composition, and further studies have been carried out to complete the present invention. That is, the present invention is
0.4 to 2 of the maleic acid represented by the general formula (1) and / or the maleic anhydride represented by the general formula (2) and at least one diamine represented by the general formula (3). 10 to 90% by weight at a molar ratio of 0.0: 1.0
Epoxy resin curing agent obtained by heat treatment at 80 to 200 ° C. in the presence of a novolac type phenolic resin and a solvent, and at least two or more epoxy groups in one molecule. Is an epoxy resin composition containing, as an essential component, an epoxy resin having a ratio of 100 parts by weight: 25 to 400 parts by weight.

[0005]

[Chemical 8]

[0006]

[Chemical 9]

[0007]

[Chemical 10] (In formula (1), formula (2) and formula (3), R _{1 to} R ₄ each represent hydrogen or an alkyl group having 4 or less carbon atoms, and X represents a divalent organic group having 4 to 50 carbon atoms. Show.)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin curing agent of the present invention is
Maleic acid and / or maleic anhydride, diamine and novolac type phenolic resin in a predetermined amount ratio,
It is obtained by heat treatment without using a solvent.

The maleic acids represented by the general formula (1) used in the present invention include maleic acid and citraconic acid, and the maleic anhydrides represented by the general formula (2) include maleic anhydride and citraconic anhydride. Examples thereof include acids. Of these, maleic acid and maleic anhydride are preferred because of their high reactivity. The maleic acids and maleic anhydrides may be used alone or in combination of two or more.

The diamine represented by the general formula (3) used in the present invention includes p-phenylenediamine, m-phenylenediamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene and 2,4-diaminotoluene. 2,5-
Diaminotoluene, 2,5-diamino-p-xylene,
2,5-diamino-m-xylene, 2,5-diaminopyridine, 2,6-diaminopyridine, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,
3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylhexafluoropropane, 4,4'-diaminodiphenylhexafluoropropane, 3,3'-diaminodiphenylether, 4, 4'-diaminodiphenyl ether, 3,4 '
-Diaminodiphenyl ether, benzidine, 3,3'-
Diaminobiphenyl, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,
3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 4,4'-methylenedi-o-toluidine, 4,4'-
Methylenedi-2,6-xylidine, 4,4'-methylenedi-2,6-diethylaniline, 3,3'-dimethyl-4,
4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene,
1,4-bis (4-aminophenoxy) benzene, 2,2
-Bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4-
(3-aminophenoxy) phenyl] sulfone, 4,
4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ether,
1,4-diaminobutane, 1,3-diaminopentane,
1,5-diaminopentane, 1,6-diaminohexane,
1,7-diaminoheptane, 1,8-diaminooctane,
1,9-diaminononane, 1,10-diaminodecane,
1,12-diaminododecane, 1,4-diaminocyclohexane, 1,2-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, bis (4-amino-3)
-Methylcyclohexyl) methane, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 4,
4-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, α, ω-bis (3-aminopropyl) polydiphenylsiloxane,
Examples include α, ω-bis (3-aminopropyl) polymethylphenylsiloxane. In particular, when the diamine has a divalent group having a divalent group selected from the groups represented by the general formulas (4) to (7) as X in the general formula (3), heat resistance and processability can be obtained. It is preferable from the viewpoint of satisfying both. These diamines may be used alone or 2
A combination of more than one type may be used.

[0011]

[Chemical 11] (In the formula (4), Y represents a direct bond or a divalent organic group, and R _{5 to} R ₈ each represent hydrogen, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms. )

[0012]

[Chemical 12] (In the formula (5), Z represents a direct bond or a divalent organic group.)

[0013]

[Chemical 13] (In the formula (6), m is an integer of 4 to 30.)

[0014]

[Chemical 14] (In the formula (7), n is an integer of 1 to 20.)

In the method for producing the epoxy resin curing agent of the present invention, the reaction between maleic acid and / or maleic anhydride and diamine is carried out by mixing and heating in the presence of a novolac type phenol resin and without solvent. The main structure of the compound obtained by this reaction is an imide compound having a repeating unit of the general formula (8). It is considered that part of the secondary amino group of this structure and unreacted primary amino group react with the epoxy group. The resulting cured product has a high heat resistance chemically and physically due to the contribution of the imide ring.

[0016]

[Chemical 15] (In the formula (8), R ₉ and R ₁₀ each represent hydrogen or an alkyl group having 4 or less carbon atoms. X represents a divalent organic group having 4 to 50 carbon atoms.)

Examples of the novolac type phenolic resin used in the present invention include phenol novolac resin, cresol novolac resin, and modified novolac resin obtained by modifying a part of these resins with xylene, aniline or the like.
These novolac type phenolic resins may be used alone or in combination of two or more kinds.

In the production of the epoxy resin curing agent of the present invention, by adding it, the fluidity can be increased and the workability can be improved. As a result, when the novolac type phenol resin is not used, the reaction molar ratio of maleic acid and / or maleic anhydride and diamine is 0.4.
The reaction molar ratio of maleic acids and maleic anhydrides can be increased as compared with the range of 0.8: 1.0. Specifically, the molar ratio of maleic acid and / or maleic anhydride and diamine is 0.4 to 2.0: 1.
It can be 0. If the amount of diamine is less than this range, the fluidity is lowered, and there is a problem in terms of processability, and if it is more than that range, the heat resistance is lowered and there is a problem.

The amount ratio of the novolac type phenol resin is 10 to 90% by weight, preferably 20 to 80% by weight. If it is more than this range, there is a problem in heat resistance, and if it is less than this range, the effect of improving fluidity cannot be obtained, which is not preferable.

Conventionally, novolac type phenol resin has been used as an epoxy resin curing agent, but it is general to add a curing catalyst such as a tertiary amine or a phosphorus compound to the resin composition. However, in the epoxy resin composition of the present invention, the use of the epoxy resin curing agent does not require a curing catalyst, but for the purpose of accelerating the curing reaction, addition of a curing catalyst within the range of not lowering the heat resistance is hindered. Absent.

As a synthesis condition in the production of the epoxy resin curing agent of the present invention, the heating temperature is 80 to 200 ° C. When heat treatment is performed at a high temperature exceeding 200 ° C., the reaction is fast, but there is a problem that cross-linking occurs due to a side reaction and the fluidity decreases. On the other hand, when the heating temperature is lower than 80 ° C., the reaction rate sharply decreases, and the heat resistance decreases due to the remaining unreacted component and the reduction in imidization ratio. The reaction time varies depending on the type of raw material and the desired product characteristics, but is on the order of minutes to hours.

The epoxy resin having at least two epoxy groups in one molecule used in the present invention includes bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin. Resin, biphenyl type epoxy resin, alicyclic epoxy resin, phenol novolac type epoxy resin, brominated phenol novolac type epoxy resin, dicyclopentadiene modified phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, aliphatic epoxy resin, poly A glycidyl amine type epoxy resin etc. can be illustrated. These epoxy resins may be used alone or in combination of two or more kinds.

The epoxy resin composition of the present invention contains, as essential components, the epoxy resin curing agent and an epoxy resin having at least two epoxy groups in one molecule, and their respective weight ratios are 100 parts by weight: 25 to 400 parts by weight. It is mixed in the ratio of parts. If the amount is out of this range, the curing reaction does not proceed sufficiently and the strength of the obtained cured product decreases, which is not preferable.

The epoxy resin composition of the present invention also contains
If necessary, fillers such as silica, carbon, glass fiber, rubber powder, release agents such as stearic acid and wax,
Solvent, plasticizer, flame retardant, antioxidant, dispersant, colorant,
Adhesion assistants and the like can be added.

As the method for producing the epoxy resin composition of the present invention, for example, the above epoxy resin curing agent, epoxy resin, and other additives are mixed at room temperature using a mixer, and then the mixture is prepared by using a roll, an extruder or the like. It is obtained by heating and kneading with a kneader, cooling and pulverizing.

[0026]

The present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.

The raw materials used in Examples and Comparative Examples are represented by the following abbreviations. MA: maleic acid MAH: maleic anhydride DDM: 4,4'-diaminodiphenylmethane MDOT: 4,4'-methylenedi-o-toluidine HM: 4,4'-diaminodicyclohexylmethane HMDA: 1,6-diaminohexaneAPS: 1,3-bis (3-aminopropyl) tetramethyldisiloxane NOV-1: phenol novolac (weight average molecular weight 3
000) NOV-2: Phenol novolac (weight average molecular weight 1
000) EOCN: orthocresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN-1020-65) TPP: triphenylphosphine

(Synthesis of Curing Agent H1) 58 parts by weight of MA (0.5 mol) of powder, 198 parts by weight of DDM (1.0 mol) and 64 parts by weight of NOV-1 were used.
The mixture was heated and kneaded at 180 ° C. for 30 minutes with a biaxial kneader to obtain a solid resin-like product. The infrared absorption spectrum of the obtained product showed absorption at about 1770 cm ⁻¹ , which was derived from the carbonyl group of the imide ring, indicating that the product was an imide compound.

(Synthesis of Curing Agents H2 to H5) According to the composition and conditions shown in Table 1, in the same manner as in the synthesis of the curing agent H1,
The curing agents H2 to H5 were synthesized. It was found that the products of all formulations were imide compounds by infrared absorption spectrum measurement, in which absorption derived from the carbonyl group of the imide ring was observed at around 1770 cm ⁻¹ .

[0030]

[Table 1]

Example 1 155 parts by weight of EOCN,
90 parts by weight of curing agent H1 and spherical silica (average particle size 20
750 parts by weight of (μm) and 5 parts by weight of stearic acid were kneaded 20 times at a temperature of 90 ° C. using a heating double roll to obtain a sheet-like product. Then, using a crusher,
This sheet was crushed to obtain a powdery resin composition. The obtained resin composition was press-molded for 5 minutes using a transfer molding machine under conditions of a mold temperature of 175 ° C. and an injection pressure of 7.8 MPa to obtain a plate-shaped molded product. The appearance of the molded product,
It was found that there were no problems and the fluidity and curability were good. Then, using an oven,
After post-curing at 5 ° C. for 5 hours, the glass transition temperature (Tg) and thermal decomposition temperature (Td) were measured to be 240 each.
It was found to be highly heat resistant at ℃ and 400 ℃. In addition, T
g is measured by a thermomechanical analyzer (TMA) at a temperature rising rate of 5 ° C./min, and Td is measured by a thermogravimetric analyzer (TGA) at 5% at a temperature rising rate of 10 ° C./min in air. It was measured as the weight loss temperature.

(Examples 2 to 5) With the formulation shown in Table 2, a resin composition was obtained in the same manner as in Example 1. The press molding test and the Tg and Td measurements were carried out in the same manner as in Example 1, and the results are also shown in Table 2. It was found that in any of the blends, a molded product having good moldability and high heat resistance can be obtained.

[0033]

[Table 2]

(Comparative Examples 1 to 3) With the formulations shown in Table 3, resin compositions were obtained in the same manner as in Example 1. The press molding test and the Tg and Td measurements were performed in the same manner as in Example 1, and the results are also shown in Table 3. When a low molecular weight aromatic amine is used as a curing agent as in Comparative Example 1,
It can be seen that there is no problem in molding processability, but the heat resistance is inferior. When a novolac-type phenol resin oligomer is used as a curing agent as in Comparative Example 2, the curability is poor and the moldability is poor, so a low-molecular curing catalyst is required as in Comparative Example 3, and It can be seen that the heat resistance is inferior even if the molding processability is supplemented by using the curing catalyst.

[0035]

[Table 3]

[0036]

By using the epoxy resin curing agent of the present invention, the heat resistance can be greatly improved without impairing the original workability of the epoxy resin. Due to this property, it is suitable for heat resistant applications in various fields such as electricity, electronics, civil engineering, and paints, and has high utility value.

Claims (3)

[Claims] 1. A maleic acid represented by the general formula (1) and / or a maleic anhydride represented by the general formula (2) and at least one diamine represented by the general formula (3). At a molar ratio of 0.4 to 2.0: 1.0, 10 to 10
An epoxy resin curing agent obtained by heat treatment at 80 to 200 ° C. in the presence of a novolac type phenol resin and a solvent-free condition, which is added at a ratio of 90% by weight. [Chemical 1] [Chemical 2] [Chemical 3] (In formula (1), formula (2) and formula (3), R _{1 to} R ₄ each represent hydrogen or an alkyl group having 4 or less carbon atoms, and X represents a divalent organic group having 4 to 50 carbon atoms. Show.) 2. The diamine contains at least one divalent group selected from the groups represented by the general formulas (4) to (7) as X in the general formula (3). The epoxy resin curing agent according to claim 1. [Chemical 4] (In the formula (4), Y represents a direct bond or a divalent organic group, and R _{5 to} R ₈ each represent hydrogen, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms. ) [Chemical 5] (In the formula (5), Z represents a direct bond or a divalent organic group.) (In the formula (6), m is an integer of 4 to 30.) (In the formula (7), n is an integer of 1 to 20.) 3. The epoxy resin curing agent according to claim 1 or 2 and an epoxy resin having at least two epoxy groups in one molecule as essential components, and the respective quantity ratios are 10.
0 parts by weight: an epoxy resin composition blended in a ratio of 25 to 400 parts by weight.