JPH10251362A - Novolak type resin, epoxy resin, epoxy resin composition and cured product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin, convertible into a cured product excellent in water resistance, adhesion and mechanical strength and useful for applications to molding materials, casting materials, laminating materials, coating materials, adhesives, resists, etc., by providing a specific molecular structure. SOLUTION: (A) This novolak type resin represented by formula II [(n) is 0-10; Me is methyl] is obtained by carrying out the condensation reaction of (i) a compound represented by formula I (X is a halogen, OH or a lower alkoxyl) with (ii) trimethylphenols (e.g. 2,3,6-trimethylphenol) in an amount of 0.3-20mol based on 1mol component (i) in the presence of an acidic catalyst (e.g. p-toluenesulfonic acid) at 40-180 deg.C for 1-10hr. An epoxy resin represented by formula III (G is glycidyl) is prepared by reacting the component A with (iii) an epihalohydrin (e.g. epichlorohydrin) in an excessive amount in the presence of an alkali metallic hydroxide (e.g. sodium hydroxide) at 20-120 deg.C for 1-10hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novolak type resin, an epoxy resin and an epoxy resin composition which give a cured product having excellent water resistance, adhesiveness and mechanical strength.

[0002]

2. Description of the Related Art Epoxy resins can be cured with various curing agents to give cured products having generally excellent mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc. It is used in a wide range of fields, such as laminates, molding materials, and casting materials. Conventionally, there is a liquid and solid bisphenol A type epoxy resin obtained by reacting bisphenol A with epichlorohydrin as the epoxy resin most used industrially. Other liquid bisphenol A type epoxy resin is added to tetrabromobisphenol
A flame-retardant solid epoxy resin obtained by reacting the resin A is used industrially as a general-purpose epoxy resin.

[0003]

However, the above-mentioned general-purpose epoxy resin has a drawback that as the molecular weight increases, the toughness of a cured product obtained by curing the resin increases, but the heat resistance decreases. In addition, when a polyfunctional epoxy resin such as cresol novolak epoxy resin is mixed to compensate for a decrease in heat resistance, the obtained cured product has high heat resistance, but has reduced toughness and adhesiveness, and has a high water absorption. There are drawbacks. On the other hand, with recent remarkable developments in the electronics industry, etc., the water resistance, adhesiveness, and mechanical strength (toughness) required for electrical insulating materials and the like used for these materials have become increasingly severe, and these characteristics have been excellent. The emergence of epoxy resins has been awaited.

[0004]

In view of these circumstances, the present inventors have conducted intensive studies for an epoxy resin which gives a cured product having excellent water resistance, adhesiveness and mechanical strength. As a result, a novolak having a specific molecular structure was obtained. The present inventors have found that a mold resin and an epoxy resin impart excellent water resistance, adhesiveness and mechanical strength to a cured product thereof, thereby completing the present invention.

That is, the present invention relates to (1) Formula (1)

[0006]

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(Wherein, n represents an average value, takes a value of 0 to 10, and Me represents a methyl group.) (2) Formula (2)

[0008]

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(Wherein, n and Me have the same meanings as in formula (1); G represents a glycidyl group); (3) (a) an epoxy resin; An epoxy resin composition containing the novolak resin described in (1), (4) an epoxy resin composition containing (a) the epoxy resin described in (2) above, and (b) a curing agent, (5) (A) the epoxy resin described in the above (2); (b) an epoxy resin composition containing the novolak resin described in the above (1); and (6) the above (3) and (4) containing a curing accelerator. And the epoxy resin composition according to any one of (5), (7) the above (3), (4), which contains an inorganic filler.
(5) and the epoxy resin composition according to any one of (6), (8) the above (3), (4), (5), (6) and (7)
A cured product obtained by curing the epoxy resin composition according to any one of the above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The compound represented by the formula (1) is, for example, a compound represented by the formula (3)

[0011]

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(Wherein, X represents a halogen atom, a hydroxyl group or a lower alkoxyl group). The compound can be obtained by a condensation reaction with a trimethylphenol in the presence of an acid catalyst.

The compound represented by the formula (2) can be obtained, for example, by reacting the compound represented by the formula (1) with epihalohydrin in the presence of an alkali metal hydroxide.

In the formula (3), a halogen atom is preferably a chlorine atom or a bromine atom, and a lower alkoxy group is preferably a methoxy group or an ethoxy group.

Here, specific examples of trimethylphenols that can be used to obtain the compound of the formula (1) include 2,2
Examples include 3,6-trimethylphenol, 2,3,5-trimethylphenol, and 3,4,5-trimethylphenol. One of these trimethylphenols may be used alone, or two or more thereof may be used in combination.

When the above condensation reaction is carried out, the amount of trimethylphenol used is usually 0.3 to 20 mol, preferably 0.4 to 15 mol, per 1 mol of the compound represented by the formula (3).
Is a mole.

In the above condensation reaction, an acid catalyst is used.
Various acid catalysts can be used, but hydrochloric acid, sulfuric acid,
Inorganic or organic acids such as p-toluenesulfonic acid and oxalic acid, and Lewis acids such as boron trifluoride, anhydrous aluminum chloride and zinc chloride are preferable, and p-toluenesulfonic acid, sulfuric acid and hydrochloric acid are particularly preferable. The use amount of these acid catalysts is not particularly limited, but it is preferable to use 0.1 to 30% by weight of the compound represented by the formula (3).

The above condensation reaction can be carried out in the absence of a solvent or in the presence of an organic solvent. Specific examples of the organic solvent that can be used include methyl cellosolve, ethyl cellosolve, toluene, xylene, and methyl isobutyl ketone. The amount of the organic solvent used is usually 50 to 300% by weight, preferably 10 to
0 to 250% by weight. The reaction temperature is usually 40 to 180
℃, reaction time is usually 1 to 10 hours. These organic solvents can be used alone or as a mixture of several types. Further, it is preferable to distill off water or alcohols generated during the reaction outside the system by using a fractionating tube or the like in order to promptly carry out the reaction.

After the completion of the reaction, a water washing treatment is carried out until the pH value of the washing solution of the reaction mixture becomes 3 to 7, preferably 5 to 7. When performing a water washing treatment, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, ammonia, sodium dihydrogen phosphate, and diethylene triamine as necessary. Various basic substances such as organic amines such as triethylenetetramine, aniline, and phenylenediamine may be used as the neutralizing agent. The washing process may be performed according to a conventional method. For example, water in which the neutralizing agent is dissolved is added to the reaction mixture, and the separation and extraction operation is repeated.

After the neutralization treatment, the solvent and unreacted substances are distilled off under reduced pressure heating, and the product is concentrated to obtain the novolak resin of the present invention represented by the formula (1). .

As a method for obtaining the epoxy resin of the present invention from the compound represented by the formula (1), for example, the compound represented by the formula (1) obtained above is mixed with an excess of epichlorohydrin, epibromohydrin, etc. An alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added to the dissolved mixture of epihalohydrin, or 20 to 12
A method of reacting at 0 ° C. for 1 to 10 hours can be adopted.

In the reaction for obtaining the epoxy resin of the present invention, an aqueous solution of the alkali metal hydroxide may be used. In this case, the aqueous solution of the alkali metal hydroxide is continuously added to the reaction system. A method may be employed in which water and epihalohydrin are continuously distilled off under reduced pressure or normal pressure, liquids are separated, water is removed, and epihalohydrin is continuously returned into the reaction system.

A quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide or trimethylbenzylammonium chloride is added as a catalyst to a dissolved mixture of the compound represented by the formula (1) and epihalohydrin at 50 to 150 ° C. A solid or aqueous solution of an alkali metal hydroxide is added to the halohydrin etherified compound of the formula (1) obtained by reacting for 1 to 5 hours, and the mixture is reacted at 20 to 120 ° C. for 1 to 10 hours to remove halogen. A method of hydrogenation (ring closure) may be used. In this case, the amount of the quaternary ammonium salt used is determined by the formula (1)
Is usually 1 to 1 mol of hydroxyl group in the compound represented by
10 g, preferably 2 to 8 g.

The amount of epihalohydrin used in these reactions is usually 1 to 20 mol, preferably 2 to 10 mol, per 1 equivalent of the hydroxyl group of the compound represented by the formula (1). The amount of the alkali metal hydroxide to be used is generally 0.8 to 1. 1 equivalent to 1 equivalent of the hydroxyl group of the compound represented by the formula (1).
It is 5 mol, preferably 0.9 to 1.1 mol. Furthermore,
In order to allow the reaction to proceed smoothly, the reaction is preferably performed by adding an aprotic polar solvent such as dimethyl sulfone or dimethyl sulfoxide in addition to alcohols such as methanol and ethanol.

When alcohols are used, they are used in an amount of usually 2 to 20% by weight, preferably 4 to 15% by weight, based on the amount of epihalohydrin. When an aprotic polar solvent is used, it is usually 5 parts by weight based on the amount of epihalohydrin.
-100% by weight, preferably 10-90% by weight.

After the reaction product of these epoxidation reactions is washed with water or without water washing, under heating and reduced pressure at 110 to 250 ° C.
The epihalohydrin and the solvent are removed at a pressure of 10 mmHg or less. In order to further reduce the amount of hydrolyzable halogenated epoxy resin, the obtained epoxy resin is dissolved in a solvent such as toluene or methyl isobutyl ketone, and an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is used. In addition, further reactions can be performed to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is usually 0.01 to 0.3 mol per 1 equivalent of the hydroxyl group of the compound represented by the formula (1) used for the epoxidation.
Preferably it is 0.05 to 0.2 mol. The reaction temperature is usually 50 to 120 ° C, and the reaction time is usually 0.5 to 2 hours.

After completion of the reaction, the formed salt is removed by filtration, washing with water, and the like, and the solvent such as toluene and methyl isobutyl ketone is distilled off under reduced pressure under heating to obtain the epoxy resin of the present invention.

Hereinafter, the epoxy resin composition of the present invention will be described. In the epoxy resin composition according to (3), (5), (6), or (7), the novolak resin of the present invention acts as a curing agent for the epoxy resin. In this case, the novolak resin of the present invention is used alone. Alternatively, it can be used in combination with another curing agent. When used in combination, the proportion of the novolak resin of the present invention in the total curing agent is preferably at least 30% by weight, particularly preferably at least 40% by weight.

Examples of other curing agents that can be used in combination with the novolak resin of the present invention include, for example, amine compounds, acid anhydride compounds, amide compounds, phenol compounds and the like. Specific examples thereof include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, a polyamide resin synthesized from a dimer of linolenic acid and ethylenediamine, phthalic anhydride, trimellitic anhydride, Pyromellitic anhydride,
Maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolak, aralkylphenol resins and their modified products, imidazole, BF Examples include, but are not limited to, ₃ -amine complexes and guanidine derivatives. These may be used alone,
Two or more kinds may be used in combination.

In the epoxy resin compositions described in (4), (5), (6) and (7), the epoxy resin of the present invention can be used alone or in combination with another epoxy resin. When used together, the proportion of the epoxy resin of the present invention in the total epoxy resin is preferably at least 30% by weight, particularly preferably at least 40% by weight.

Examples of other epoxy resins that can be used in combination with the epoxy resin of the present invention include novolak type epoxy resins,
Bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin and the like can be mentioned, and these may be used alone or in combination of two or more.

In the epoxy resin compositions of (3), (6) and (7), when the novolak resin of the present invention is used as a curing agent, the other epoxy resin or the epoxy resin of the present invention may be used as the epoxy resin. Resin can be used.

In the epoxy resin compositions of (4), (6) and (7), when the epoxy resin of the present invention is used as an epoxy resin, the other curing agent or the novolak of the present invention is used as a curing agent. A mold resin can be used.

The amount of the curing agent used in the epoxy resin composition of the present invention is preferably 0.7 to 1.2 equivalents per equivalent of the epoxy group of the epoxy resin. If the amount is less than 0.7 equivalents or more than 1.2 equivalents with respect to 1 equivalent of epoxy group, curing may be incomplete and good cured physical properties may not be obtained.

When the above curing agent is used, a curing accelerator may be used in combination. Specific examples of the curing accelerator that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol,
1,8-diaza-bicyclo (5,4,0) undecene-
Tertiary amines such as 7, phosphines such as triphenylphosphine, and metal compounds such as tin octylate. The curing accelerator is used in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin as required.

The epoxy resin composition of the present invention optionally contains an inorganic filler. Specific examples of the inorganic filler that can be used include silica, alumina, and talc.
The amount of the inorganic filler occupying 0 to 90% by weight in the epoxy resin composition of the present invention is used. Further, to the epoxy resin composition of the present invention, various compounding agents such as a silane coupling agent, a releasing agent such as stearic acid, palmitic acid, zinc stearate, and calcium stearate, and a pigment can be added.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the above components. The epoxy resin composition of the present invention can be easily made into a cured product by a method similar to a conventionally known method. For example, the epoxy resin of the present invention and a curing agent, and if necessary, a curing accelerator,
An extruder, if necessary, with an inorganic filler, or a compounding agent,
The epoxy resin composition of the present invention was sufficiently mixed by using a kneader, a roll, or the like until it became uniform, and after being melted, molded using a casting or transfer molding machine. The cured product of the present invention can be obtained by heating at ~ 200 ° C for 2 to 10 hours.

Further, the epoxy resin composition of the present invention is dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like, and is used to prepare glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper and the like. A prepreg obtained by impregnating a substrate and drying by heating may be subjected to hot press molding to obtain a cured product. The solvent in this case is usually 10 to 70% by weight, preferably 1% by weight in the mixture of the epoxy resin composition of the present invention and the solvent.
An amount occupying 5 to 65% by weight is used.

Since the cured product of the present invention thus obtained is excellent in heat resistance, water resistance and mechanical strength, it can be used in a wide range of fields requiring heat resistance, water resistance and high mechanical strength. Specifically, it is useful as any electric or electronic material such as a sealing material, a laminate, or an insulating material. Further, it can be used in the fields of molding materials, adhesives, composite materials, paints, and the like.

[0040]

EXAMPLES The present invention will be described more specifically with reference to the following Examples, in which parts are by weight unless otherwise specified.

Example 1 A flask equipped with a thermometer, a dropping funnel, a cooling pipe, a fractionating pipe, and a stirrer was charged with the following formula (4).

[0042]

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121 parts of a compound represented by the following formula: 2,3,6-
143 parts of trimethylphenol were charged and stirred at room temperature while blowing nitrogen. 0.5 parts of p-toluenesulfonic acid (monohydrate) was heated to 50
Add slowly so as not to exceed ° C. Thereafter, the mixture was heated to 120 ° C. in an oil bath, methanol generated was extracted using a fractionating tube, and the mixture was further reacted for 5 hours. After completion of the reaction, 500 ml of methyl isobutyl ketone was further added, and the mixture was transferred to a separating funnel and washed with water. Then, after washing with water until the washing water shows neutrality, the solvent and unreacted 2,3,6-trimethylphenol are removed from the organic layer under heating and reduced pressure, and the following formula (5)

[0044]

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(In the formula, Me represents a methyl group, and the average value of n is 0.47.) 208 parts of the novolak type resin (A) of the present invention represented by the following formula: The resulting novolak resin has a softening point of 85.6 ° C. and a hydroxyl equivalent of 242 g / eq.
Met.

Example 2 A flask equipped with a thermometer, a condenser and a stirrer was charged with 121 parts of the novolak resin (A) obtained in Example 1, 185 parts of epichlorohydrin and 46 parts of dimethyl sulfoxide while purging with nitrogen gas. Dissolved. This was further heated to 45 ° C., and 20.2 parts of flaky sodium hydroxide (99% pure) were added in portions over 90 minutes. Thereafter, the mixture was further reacted at 45 ° C. for 2 hours and at 70 ° C. for 1 hour. After completion of the reaction, dimethyl sulfoxide and epichlorohydrin were distilled off under heating and reduced pressure at 130 ° C., and 259 parts of methyl isobutyl ketone were added to the residue and dissolved.

Further, this solution of methyl isobutyl ketone was heated to 70 ° C., and a 30% by weight aqueous solution of sodium hydroxide was added.
Then, after washing for 1 hour, washing with water was repeated until the pH of the washing solution became neutral. Further, the aqueous layer was separated and removed, and methyl isobutyl ketone was distilled off from the oil layer under reduced pressure by heating using a rotary evaporator.

[0048]

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(In the formula, Me represents a methyl group, G represents a glycidyl group, and the average value of n is 0.47.)
(168 parts) of the epoxy resin (B) of the present invention represented by the following formula: The obtained epoxy resin had a softening point of 73.6 ° C. and an epoxy equivalent of 313 g / eq.

Examples 3 and 4 Orthocresol novolak epoxy resin EOCN1
020 (epoxy equivalent 200g / eq, Nippon Kayaku Co., Ltd.)
Novolak resin (A)
Was added to the epoxy resin (B) as a curing agent with phenol novolak (hydroxyl equivalent 106 g / eq, softening point 83
C., manufactured by Nippon Kayaku Co., Ltd.), epoxy resin (B), novolak type resin (A) as a curing agent, and triphenylphosphine (TPP) as a curing accelerator. Compounded at the ratio shown in the composition column, kneaded with a roll at 70 ° C. for 15 minutes, 150 ° C., molding pressure 50 kg /
180 seconds and transfer molding in cm ^2, followed 1
A test piece was prepared by curing at 60 ° C. for 2 hours and further at 180 ° C. for 8 hours, and the water absorption and Izod impact test values were measured. Table 1 shows the results. The conditions for measuring the water absorption, the copper foil peel strength, and the Izod impact test value are as follows. Also, in the table, the numerical values in the column of the composition of the blend indicate parts by weight.

The water absorption was determined by using a disk-shaped cured product having a diameter of 5 cm and a thickness of 3 mm as a test piece, boiling in water at 100 ° C. for 24 hours, and calculating the weight change before and after the boiling. Copper foil peeling strength The maximum value of the strength (Kg / c) when the copper foil is set on the test piece and cured, and the copper foil is pulled at a constant speed in the direction of 180 degrees.
m) Tensile tester: Tensilon (Orientec Co., Ltd.)
Manufactured) Pulling speed: 200 mm / min. Izod impact test value (KJ / m ² ) Measured according to JIS K-6911

[0052]

Table 1 Example 3 45 Composition of the composition EOCN1020 100 Phenol novolak 34 Novolak type resin (A) 121 77 Epoxy resin (B) 100 100 TPP 11 1 Physical properties of cured product Water absorption 0.72 0.68 0.62 Copper foil Peel strength 2.8 3.1 3.2 Izod impact test value 18.9 20.6 21.5

As shown in Table 1, the cured product of the present invention has a low water absorption,
It is clear that they show high adhesion and high mechanical strength.

[0054]

The novolak type resin and epoxy resin of the present invention can give a cured product having excellent water resistance, adhesiveness and mechanical strength, and can be used as a molding material, a casting material, a laminate material, a paint, an adhesive, a resist. It is extremely useful for a wide range of applications.

Claims (8)

[Claims] (1) Formula (1) (In the formula, n represents an average value, takes a value of 0 to 10, and Me represents a methyl group.) (2) Formula (2) (Where n and Me have the same meanings as in formula (1), and G represents a glycidyl group). 3. An epoxy resin composition comprising: (a) an epoxy resin; and (b) the novolak resin according to claim 1. 4. An epoxy resin composition comprising (a) the epoxy resin according to claim 2 and (b) a curing agent. 5. An epoxy resin composition comprising (a) the epoxy resin according to claim 2 and (b) the novolac resin according to claim 1. 6. A method according to claim 3, wherein the composition contains a curing accelerator.
The epoxy resin composition according to any one of the above. 7. The epoxy resin composition according to claim 3, further comprising an inorganic filler. 8. One of claims 3, 4, 5, 6 and 7
A cured product obtained by curing the epoxy resin composition according to the above item.