JPH07206978A - Epoxy resin - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin which is useful as a plastic for composite materials because of its low viscosity, excellent impregnation, moldability, heat resistance and mechanical strength by simultaneous glycidyl-etherification of a bisphenol and a novolak resin. CONSTITUTION:A novolak resin softening at a temperature lower than 110 deg.C and a blsphenol of the formula [R<1> is CH3, CHCH3, C(CH3)2, SO2; R<2> to R<5> are H, a halogen, a 1-5C alkyl] such as bisphenol A are simultaneously glycidyl- etherified with an epihalohydrin or methyl epihalohydrin to give the epoxy resin. The weight ratio of the bisphenol to the novolak resin is preferably in the range of (50 to 90)/(50-10).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a composite plastic material composed of various fibers, which can give a cured product having a low viscosity when mixed with a curing agent, easy molding, and excellent heat resistance and mechanical strength. The present invention relates to an epoxy resin preferably used as.

[0002]

2. Description of the Related Art A composite plastic material obtained by mixing a plastic and a reinforcing material is generally excellent in heat resistance, weather resistance, chemical resistance or mechanical strength and is used in various industrial fields. Epoxy resin is mainly used as a matrix resin which is a base material of the composite plastic material. This is because the epoxy resin has good mechanical properties,
This is also because it has excellent adhesiveness to the reinforcing fibers used for the reinforcing material, and further has good moldability when made into a composite material. A composite plastic composed of an epoxy resin and carbon fiber is particularly expected to be a next-generation main structural material in the field of advanced technology such as the aerospace industry and the automobile industry because of its excellent heat resistance and mechanical strength.

In order to use these advanced technologies as structural materials in the industrial field, higher heat resistance and improved moldability are desired. As a method of increasing the heat resistance, there is a method of increasing the crosslink density by adding a polyfunctional epoxy resin. Among them, the addition of a novolac type epoxy resin is particularly used in many fields from the viewpoint that the price is appropriate. .

However, since the novolac type epoxy resin has a molecular weight distribution, the addition of a large amount or a resin having a large molecular weight will increase the viscosity of the obtained resin. Therefore, when it is used as a resin for a matrix, a reinforcing fiber is used. However, the impregnating property into the resin becomes poor and the resulting composite plastic material is difficult to mold.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to provide an epoxy resin which, when mixed with a curing agent, has a low viscosity, is easy to mold, and can give a cured product having excellent heat resistance and mechanical strength. is there.

[0006]

Means for Solving the Problems As a result of various studies to solve the above-mentioned problems, the present inventors have found that when a bisphenol is glycidyl etherified with epihalohydrin or methylepihalohydrin, a novolak resin is allowed to coexist with the glycidyl ether. The present inventors have found that the epoxy resin obtained in (1) can give a cured product having low viscosity, easy molding, and excellent heat resistance and mechanical strength, leading to the present invention.

That is, according to the present invention, when an epoxy resin obtained by glycidyl etherifying bisphenols with epihalohydrin or methylepihalohydrin is obtained, a novolak resin is allowed to coexist, and an epoxy resin obtained by simultaneously glycidyl etherifying bisphenols and novolak resins is used. provide. Here, the weight ratio of the bisphenols to the novolac resin is 50 to 90/50 to 10,
It is preferably 65 to 90/35 to 10. The reason why the weight ratio of the bisphenols to the novolac resin is within this range is to provide a cured product having good moldability, heat resistance and mechanical strength.

The bisphenols which are the raw materials of the epoxy resin used in the present invention are bisphenols represented by the following formula (1), and bisphenol A, bisphenol F and bisphenol AD are preferable.

[Chemical 1] ^{R 2, R 3, R 4} , R 5 is an alkyl group of 1 to 5 carbon atoms which may be the same or different, is a halogen group or a hydrogen atom.

Here, R ¹ is an isopropylidene group and R ²
Bisphenol A in which R ⁵ is a hydrogen atom is preferable.

The novolak resin used in the present invention is a condensate of formaldehyde and the above-mentioned bisphenols or phenols represented by the following formula (2). The softening point of the novolak resin of the present invention is preferably 110 ° C. or lower. More preferably, it is in the range of 30 ° C to 100 ° C.
If the softening point is less than 30 ° C, the heat resistance of the cured product is insufficient, and if it exceeds 110 ° C, the molecular species of high molecular weight increase, the viscosity increases, and the moldability deteriorates. The number average molecular weight is preferably 300 to 1000, more preferably 300 to 700.

[Chemical 2]

R ¹ and R ² are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or less, or a halogen group. The phenols condensed with formaldehyde are preferably phenol and O-cresol.

Similarly, bisphenols condensed with formaldehyde include bisphenol A and bisphenol A.
D is preferred.

The novolak resin used in the present invention contains 0.2 to 0.8 mol of formaldehyde for 1 mol of the above-mentioned bisphenol and / or phenol, and xylene.
It can be produced by reacting in a solvent such as toluene or without solvent in the presence of an acidic catalyst. Paraformaldehyde may be used as the formaldehyde. Formaldehyde is in this range in order to optimize the softening point and average molecular weight of the novolak resin.

The amount of the solvent used is 100 wt% based on the total amount of the above-mentioned bisphenols and phenols.
It is preferable to set it to 20 to 100 wt%. Examples of the acidic catalyst include mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and organic acids such as P-toluenesulfonic acid and oxalic acid.
Among these, P-toluenesulfonic acid is preferable because it has high acid strength and good compatibility with the reaction substrate.
The amount of the catalyst used is preferably 0.05 to 2 wt% with respect to 100 wt% of the total amount of the charged bisphenols and phenols. More preferably, it is 0.1 to 1 wt%. If the amount of the catalyst is small, the condensation does not proceed and the desired molecular weight of the novolak resin cannot be obtained. If the amount of the catalyst is too large, it is difficult to control the reaction and the molecular weight of the obtained novolak resin is too high. The reaction temperature is 70 to 100 ° C. for 1.5 to 4 hours, and then 100 to 120 ° C. for dehydration condensation reaction. In this case, the dehydration condensation reaction is carried out under reduced pressure, or the condensation water is removed by utilizing azeotrope at reflux in a solvent such as xylene or toluene. The reaction is preferably carried out until no water of condensation is produced. This reaction time is usually 3-5
It's time.

After completion of the reaction, an equivalent amount of alkali is added to the reaction solution to neutralize the acidic catalyst. Examples of the alkali include sodium hydroxide, potassium hydroxide, triethanolaminemorpholine and the like. A non-aqueous solvent may be added to the reaction solution to make a uniform solution, and then the solution may be washed with an alkaline aqueous solution for neutralization. When a solvent is used, the solvent can be distilled off to obtain a novolak resin. The weight ratio of the billphenols used in the present invention to the novolac resin is 50 to 90/50.
10 is preferably 65 to 90/35 to 10. If the amount of the novolac resin component is small, the heat resistance is insufficient, and if it is too large, the viscosity becomes high and the moldability deteriorates.

The above-mentioned simultaneous glycidyl etherification reaction of the bisphenols and the novolak resin can be carried out by various methods following the conventionally known reaction. For example, (a)
Either the method of simultaneously performing the etherification step and the dehydrohalogenation step or the method of (b) sequentially performing the etherification step and the dehydrohalogenation step may be performed. The method of sequentially performing (b) the etherification step and the dehydrohalogenation step is advantageous in that an epoxy resin of stable quality can be obtained. The etherification step is preferably carried out in the presence of an etherification catalyst in an amount of 0.1 to 5 mol% with respect to 1 equivalent of the phenolic hydroxyl group.

Examples of the etherification catalyst used in the etherification step include tertiary amines such as trimethylamine and triethylamine; tertiary phosphines such as triphenylphosphine and tributylphosphine; tetramethylammonium chloride, tetramethylammonium bromide and tetraethylammonium. Quaternary ammonium salts such as chloride, tetramethylammonium bromide, choline chloride; quaternary phosphonium salts such as tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetraphenylphosphonium bromide, triphenylpropylphosphonium bromide; benzyldibutylsulfonium chloride, Tertiary sulfonium salts such as benzyldimethylsulfonium chloride and sodium hydroxide, potassium hydroxide, etc. Inorganic bases and the like. Among these, tetramethylammonium chloride is preferable.

In this etherification step, the reaction is carried out until at least about 50 mol%, preferably 70 mol% or more of the phenolic hydroxyl group is etherified. This reaction is usually carried out at a temperature of 60 to 110 ° C. under an inert atmosphere at 1 to
It will be held for 12 hours.

In the subsequent dehydrohalogenation step, the unreacted epihalohydrin is contained in the reaction as a reaction product of the etherification step. In this reaction, an alkali compound such as the alkali metal hydroxide used in the etherification step, preferably sodium hydroxide, is used as a catalyst.

The amount of the alkali compound used in the dehydrohalogenation step is usually 0.5 times mol or more, preferably 0.8 times mol or more, relative to 1 equivalent of the phenolic hydroxyl group of the novolak resin (A). is there. However, in order to avoid the inconvenience such as gelation of the reaction product, it is desirable that the amount of the alkali compound is 1 mol or less.

The reaction is generally carried out at a temperature of about 60 to 100 ° C. for about 1 to 3 hours, and when sodium hydroxide is used, it can be carried out while removing by-produced water from the reaction system. preferable. Water can be removed by, for example, a method of dehydrating epichlorohydrin-water azeotropically under reduced pressure and returning epichlorohydrin to the reaction system.

After completion of the reaction, the unreacted epihalohydrin is removed by distillation under reduced pressure, the by-product salt is removed by washing with water, and the reaction mixture is optionally diluted with a weak acid such as phosphoric acid and sodium dihydrate of phosphoric acid. After post-treatment such as Japanese-style treatment, the epoxy resin of the present invention can be obtained by filtration and drying. When it is necessary to further reduce the amount of hydrolyzable chlorine, the second dehydrohalogenation reaction may be performed again. The amount of alkali metal hydroxide used to reduce the amount of hydrolyzable chlorine is one of the remaining amount of hydrolyzable chlorine.
˜3 times mole, preferably 1.2 to 2.5 times mole. This reaction is carried out at 60 to 100 ° C for about 1 to 3 hours. A solvent may or may not be used, but when it is used as a solvent, xylene, toluene, MEK, methyl isobutyl ketone and the like are preferable.

The epoxy equivalent of the epoxy resin (B) obtained as described above is usually 210 g / eq or less,
It is preferably 200 to 190 g / eq.

The curing agent used for curing the composition of the present invention is not particularly limited, and examples thereof include acid anhydrides, aromatic polyamines, aliphatic polyamines, imidazole and phenol resins.

Examples of the acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnaphthic anhydride, methylnaphthalenedicarboxylic anhydride,
Pyromellitic dianhydride, trimellitic dianhydride, benzophenone tetracarboxylic dianhydride, dodecyl succinic anhydride, chlorendic anhydride, chloronorbornene dicarboxylic anhydride, etc. are mentioned.

Examples of aromatic polyamines include diaminodiphenylmethane, diaminodiphenylsulfone,
Examples include amine adducts.

Examples of the aliphatic polyamine include triethylenetetramine, diethylenetriamine, menthenediamine, N-aminoethylpiperazine, isophoronediamine, 3,9-bis (3-aminopropyl) -2,
4,8,10-Tetraspiro [5,5] undecane, amine adduct and the like can be mentioned.

Examples of the imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-ethyl-4-methylimidazole azine,
1-benzyl-2-methylimidazole and the like can be mentioned.

Examples of the phenol resin include phenol resin novolac and alkyl-substituted phenol novolac resin.

Further, as the curing agent used in the present invention,
Dicyandiamide, metaxylylenediamine, etc. are also mentioned. Specific examples of the imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2
-Phenylimidazole, 2-undecylimidazole, 2-ethyl-4-methylimidazole azine, 1-
Used from benzyl-2-methylimidazole and the like.

In the present invention, the curing agents may be used alone or in combination of two or more.

As the curing accelerator, the above-mentioned imidazole, tertiary amine and the like can be used.

Examples of the tertiary amine include N, N-
Examples thereof include benzyldimethylamine and 2,4,6-tris (dimethylaminomethyl) phenol.

As the curing accelerator, 1,8-diazabicyclo- [5.4.0] undecene-7 octylate, a complex compound of monoethylamine and boron trifluoride,
1-benzyl-2-methylimidazole, 2-ethyl-
4-methylimidazole, or the one marketed by San Abbott under the trade name: Ucat SA102 may be mentioned.

In the present invention, the above curing accelerators may be used alone or in combination of two or more.

Further, the epoxy resin of the present invention may be blended with other epoxy compounds as long as the purpose thereof is not impaired. As other epoxy compounds, for example,
Bisphenol A type epoxy compound, bisphenol F
Type epoxy compound, 1,1-bis (glycidoxyphenyl) ethane, phenol novolac type epoxy compound,
Examples thereof include o-cresol-novolak type epoxy compounds, glycidyl ester type epoxy compounds, glycidyl amine type epoxy compounds and alicyclic epoxy compounds.

Further, in order to cure the epoxy resin of the present invention to obtain a cured product having flame retardancy, diglycidyl ether of tetrabromobisphenol A or the like may be used in combination.

Further, the composition of the present invention may optionally contain various components in addition to the above components. For example, non-reactive diluents such as phthalates, ethers or esters of glycols, phenols and the like;
Reactive diluents such as long-chain alkylene oxide, butyl glycidyl ether, phenyl glycidyl ether, p-butyl phenyl glycidyl ether; calcium carbonate, clay, asbestos, silica, mica, quartz powder, aluminum powder, graphite, titanium oxide, alumina, Fillers such as iron oxide, glass powder, and glass fiber; coloring agents such as carbon black, toluidine red, Hansa yellow, phthalocyanine blue, and phthalocyanine green.

A composition using the epoxy resin of the present invention is
Each component is preferably blended in the following proportions. Epoxy resin of the present invention: 100 parts by weight Curing agent: 1-150 parts by weight (preferably 3-110 parts by weight, a small amount is possible in the case of dicyandiamide) Curing accelerator: 0.1-3 parts by weight Is melted by heating and mixed, or dissolved and mixed by using a solvent to obtain a composition using the epoxy resin of the present invention. The curing reaction of such a composition is performed by heating at room temperature or about 60 to 250 ° C.

[0040]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, the following physical properties were measured according to the following methods.

(Viscosity) The viscosity was measured at a temperature of 25 ° C. using an E-type viscometer.

(Bending strength, flexural modulus) JIS K69
It measured according to 11. That is, 4 mm x 10 mm x
A 97 mm test piece was used with TOYO BALDWIN Tensilon, a crosshead speed of 1 mm / min, and a maximum load of 5
It measured using the cell of 00 kg.

(Deflection temperature under load) Measured in accordance with JIS K6911. That is, 12.5 mm x 12.5 m
A test piece of m × 125 mm was measured using an apparatus manufactured by Tester Sangyo Co., Ltd.

Reference Example 1 Synthesis of Novolac Resin Using Bisphenol A as Phenol 456 g of bisphenol A and 335 g of toluene were charged in a 1 L separable flask equipped with a condenser, a thermometer, a stirrer, and a dropping container, and the mixture was heated while stirring. Warmed. When the temperature in the flask reached 70 ° C., 2.52 g of oxalic acid dihydrate as a catalyst was added. 37% formalin aqueous solution at 90 ℃ 8
2.7 g was added dropwise over 2 hours. The stirring was continued for another hour under reflux. Water and toluene were removed from the system while raising the temperature. After reaching 150 ° C., the mixture was concentrated under normal pressure for 1 hour, then depressurized and concentrated at 20 mmHg and 150 ° C. for 1 hour to obtain a bisphenol A type novolak resin. The softening point of the obtained resin was 93 ° C. as measured by an automatic softening point measuring device manufactured by METTLER. The hydroxyl equivalent of the obtained novolak resin was 120 g / eq measured by JIS K0070.

(Example 1) 400 g of bisphenol A,
Orthocresol novolac resin 100 g (OCN80 manufactured by Nippon Kayaku Co., softening point 80 ° C., hydroxyl equivalent 139 g / e
q), 1956 g of epichlorohydrin and 39 g of water were charged into a reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and the temperature was raised to 65 ° C. 50 after becoming a homogeneous solution
% Tetramethylammonium chloride (23.1 g) was added and the mixture was stirred for 3 hours. Then under reduced pressure 48% NaOH 33
1.5 g was added dropwise at 70 ° C. for 2 hours, and at the same time excess water was removed by utilizing azeotropy with epichlorohydrin to keep the water content in the system at 2 wt%. The distilled epichlorohydrin was separated from water and then returned to the reaction system. Decompression degree and heating conditions are such that the amount of water removed per unit time from the system is 48% NaO.
It was adjusted to be equal to the sum of the amount of water from H and the amount of water produced in the reaction. After addition of 48% NaOH, 0.5 hr
The mixture was stirred at the same temperature. After completion of the above reaction, unreacted epichlorohydrin and water were distilled off under reduced pressure, and xylene was added to the residue.
50 g and 75 g of water were added, and the mixture was stirred at 80 ° C. and then left standing to carry out liquid separation. When the xylene phase was sampled and analyzed, the concentration of hydrolyzable chlorine was 1.45 wt%. 62 g of 48% NaOH was added to the xylene phase, and the mixture was stirred at 95 ° C. for 2 hours. After completion of the reaction, the gel component was removed, and then 750 g of 25% monosodium phosphate aqueous solution was added for neutralization. Water in the xylene phase was removed azeotropically with xylene, and the inorganic salt was filtered off using a glass filter. The filtrate was dexylene depressurized at 150 ° C. to obtain 680 g of a glycidyl compound which is the epoxy resin of the present invention. The epoxy equivalent of this product is 185
The g / eq hydrolyzable chlorine content was 0.06 wt%.

(Example 2) 260 g of bisphenol A and 229 g of the bisphenol A type novolac resin synthesized in Reference Example 1 were used instead of 260 g of bisphenol A and 190 g of epoxy equivalent in Example 1. / Eq, hydrolyzable chlorine content 0.05w
450 g of t% epoxy resin was obtained.

(Example 3) 80 g of the epoxy resin synthesized in Example 1, 72.6 g of methylhexahydrophthalic anhydride (RIKACID MH-700 manufactured by Shin Nippon Rika), Ucat
0.4 g of -102 (Sun Abbott) was mixed with stirring at 50 ° C to obtain a uniform solution. The viscosity of this product at 25 ° C. was 993 cps. Bending strength, deflection temperature under load, cast into a measuring die at 120 ° C for 2 hours, then 1
A cured product was obtained by heating at 50 ° C. for 2 hours and finally at 170 ° C. for 4 hours. The physical properties of this product are shown in Table 1.

(Example 4) A cured product was obtained in the same manner as in Example 3, except that the epoxy resin synthesized in Example 2 was changed to 80 g and the methylhexahydrophthalic anhydride was changed to 70.8 g. The viscosity of this product before curing is 896.
It was cps (25 ° C). The cured physical properties are shown in Table 1.

Comparative Example 1 Using 584 g of orthocresol novolac resin (OCN80 manufactured by Nippon Kayaku Co., Ltd.), other components and conditions were the same as in Example 1 and epoxy equivalent 2
650 g of a novolac type epoxy resin having 03 g / eq and a hydrolyzable chlorine content of 0.05 wt% was obtained.

Comparative Example 2 504 g of the bisphenol A type novolak resin synthesized in Reference Example 1 was used in the same manner as in Example 1 to obtain a novolak type epoxy resin having an epoxy equivalent of 197 g / eq and a hydrolyzable chlorine content of 0.06 wt%. 60
5 g was obtained.

Comparative Example 3 16 g of the novolac type epoxy resin synthesized in Comparative Example 1, 64 g of bisphenol A type liquid epoxy resin (epoxy equivalent 188 g / eq), 71.4 g of methylhexahydrophthalic anhydride, and Ucat10.
2 0.4 g was performed in the same manner as in Example 3 to obtain a cured product. However, the ratios of the bisfunol A component and the novolac component in the obtained cured product were the same as in Example 3. The viscosity before curing was 1946 cps. The physical properties of the cured product are shown in Table 1.

(Comparative Example 4) 37.4 g of the novolac type epoxy resin synthesized in Comparative Example 2 and bisphenol A type liquid epoxy resin (epoxy equivalent 188 g / eq) 42.6.
g, methyl hexahydrophthalic anhydride 69.8 g, Uc
0.4 g of at-102 was obtained in the same manner as in Example 3 to obtain a cured product. However, bisphenol A in the obtained cured product
The ratio of the component to the bisphenol A novolac component was the same as in Example 4. The viscosity before curing was 3379 cps. The physical properties of the cured product are shown in Table 1.

Comparative Example 5 80 g of bisphenol A type liquid epoxy resin (epoxy equivalent of 188 g / eq), 71.5 g of methylhexahydrophthalic anhydride, Ucat-1
02 0.4 g was treated in the same manner as in Example 3 to obtain a cured product.

[0054]

[0055]

EFFECT OF THE INVENTION The novel epoxy resin of the present invention has a low viscosity when mixed with a curing agent when it is uncured, and has a good impregnation property into a reinforcing material, so that it is easy to mold. Further, the cured product has excellent heat resistance and mechanical strength. Therefore, the epoxy resin of the present invention and various compositions obtained from this epoxy resin are
It can be widely used as a material for composite plastics.

Claims (3)

[Claims] 1. An epoxy resin obtained by coexisting a novolak resin and obtaining a glycidyl ether of a bisphenol and a novolak resin when obtaining an epoxy resin obtained by glycidyl etherifying a bisphenol with epihalohydrin or methylepihalohydrin. 2. The weight ratio of the bisphenols to the novolac resin is 50 to 90/50 to 10.
The epoxy resin described in 1. 3. The epoxy resin according to claim 1, wherein the novolac resin has a softening point of 110 ° C. or lower.