JP2001059010A - O-cresol novolak type epoxy resin with high softening point, and production of epoxy resin solution and epoxy resin composition each containing the same and the epoxy resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin useful as a varnish for laminates, an epoxy resin for coating materials or a material for hot-melt type adhesives-by including an o-cresol novolak skeleton as the main skeleton and setting its softening point at a specific value or higher. SOLUTION: This epoxy resin is such one as to contain an o-cresol novolak skeleton as the main skeleton and have a softening point of >=100 deg.C. This epoxy resin is obtained by reacting an o-cresol novolak type epoxy resin having a softening point of 60 to 98 deg.C with a 1/30 to 1/9 equivalent of a bifunctional phenolic compound [e.g. methylenebis(o-cresol)]. The above mentioned reaction is desirable to be conducted in an organic solvent such as methyl ethyl ketone, in the presence of a phosphorus-based catalyst such as triphenylphosphine at 60 to 150 deg.C normally for about 1 to 15 h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a varnish for laminated boards,
The present invention relates to an o-cresol-novolak type epoxy resin having a high softening point, which is useful as an epoxy resin for paints, a material for a hot melt type adhesive, and the like.

[0002]

2. Description of the Related Art An o-cresol-novolak type epoxy resin having a high softening point has poor solubility in a solvent, and has problems such as precipitation during the epoxidation reaction and gelation. Only those having a softening point of about 98 ° C. or less are known. On the other hand, an o-cresol-novolak type epoxy resin having a high softening point can improve the glass transition temperature of the cured product, can shorten the gel time and the curing time, and can maintain a high viscosity at the time of spraying in powder coatings and the like. The market demand was strong because of the fact that the film forming ability increased.

[0003]

An object of the present invention is to provide an o-cresol-novolak type epoxy resin having a high softening point. Another object of the present invention is to provide an o-cresol-novolak type epoxy resin having a high softening point without causing gelation or the like, and
An object of the present invention is to provide a method for producing an epoxy resin, which is capable of suppressing the epoxy equivalent to a certain low level and efficiently producing the same.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and have completed the present invention. That is, the present invention provides (1) an epoxy resin having an o-cresol novolak skeleton as a main skeleton and having a softening point of 100 ° C. or more, and (2) an o-cresol having a softening point of 60 to 98 ° C.
1/9 equivalent or less, 1/3 of Lunovolak type epoxy resin
The epoxy resin according to the above (1), which can be obtained by reacting with a bifunctional phenol compound of 0 equivalent or more, and (3) an epoxy resin produced using a phosphine as a catalyst, wherein the phosphine in the epoxy resin is used. Content of 500
The epoxy resin according to the above (2), which is not more than ppm,
(4) An epoxy resin characterized by reacting an o-cresol-novolak type epoxy resin having a softening point of 60 to 98 ° C. with 1/9 equivalent or less and 1/30 equivalent or more of a bifunctional phenol compound. (5) the method for producing an epoxy resin according to the above (4), wherein the reaction is carried out in an organic solvent;
(6) the method for producing an epoxy resin according to the above (4) or (5), wherein the reaction is carried out in the presence of a phosphorus-based catalyst;
An epoxy resin solution containing the epoxy resin and the organic solvent according to any one of (1) to (3), (8) the above (1) to (3).
An epoxy resin composition comprising the epoxy resin according to any one of (3) and a curing agent.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy resin of the present invention having a softening point of 100 ° C. or higher having o-cresol-novolak as a main skeleton has, for example, a softening point of 60 ° C.
An o-cresol novolak type epoxy resin at a temperature of up to 98 ° C. can be reacted with a bifunctional phenol compound in a specific ratio in the absence of a solvent or in the presence of an organic solvent.

[0006] The o-cresol novolak type epoxy resin used herein is an o-cresol obtained by reacting o-cresol with an aldehyde such as formaldehyde in the presence of an acid catalyst and having o-cresol bonded via a methylene group. The phenolic hydroxyl group of the cresol novolac resin can be reacted with epichlorohydrin in a known manner, for example, in the presence of an alkali metal hydroxide. In this case, o-cresol may be obtained by reacting o-cresol with a dimethylol derivative of o-cresol in the presence of an acid catalyst, and using an o-cresol novolak resin obtained as a raw material. Among such o-cresol novolac type epoxy resins, those having a softening point of 60 to 98 ° C, preferably 70 to 95 ° C are used, but an o-cresol novolac type having an industrially obtained softening point of 60 ° C or more is used. Epoxy resins are preferred because the content of the bifunctional epoxy compound is relatively low and the proportion of the bifunctional linear polymer obtained as a result of the reaction between the bifunctional phenol compound and the bifunctional epoxy resin is low.

The organic solvent used as necessary in the reaction for obtaining the epoxy resin of the present invention is preferably a good solvent for the o-cresol-novolak type epoxy resin, for example, aromatic solvents such as toluene and xylene, acetone, methyl ethyl ketone, and the like. Ketone solvents such as methyl isobutyl ketone, ether, dibutyl ether, tetrahydrofuran, dioxane, ethylene glycol monoalkyl ether
Ethers such as ethylene glycol dialkyl ether, propylene glycol mono- or dialkyl ether;
Aprotic polar solvents such as ters, N-methylpyrrolidone, dimethylimidazolidinone, and dimethylformaldehyde; and esters such as ethyl acetate and butyl acetate. These are used in such an amount that the concentration of the epoxy resin becomes 10 to 90% by weight, preferably about 30 to 80% by weight. The reaction can be carried out without a solvent, but the use of a solvent is sometimes preferred in terms of workability. Also,
As described below, it is preferable to use the epoxy resin of the present invention by dissolving it in an organic solvent, since the solution after the reaction can be used as it is.

The bifunctional phenol compound to be reacted is not particularly limited as long as it has two phenolic hydroxyl groups, but is preferably an aromatic compound such as hydroquinone, catecholresorcinol and Alkyl substitution such as methyl group, ethyl group and propyl group, or halogen substitution such as chlorine and bromine can be used. Further, those having two benzene rings can be represented by the following chemical formula.

[0009]

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(Wherein X is an alkylidene group such as a methylene group, an ethylidene group or a propylidene group, a direct bond,
Represents a fluoropropylidene group, a sulfone group, a sulfide group, a carbonyl group, a benzylidene group, or a xylylene group. R _{1 to} R ₆ each independently represent a hydrogen atom, a halogen atom, a methyl group, an ethyl group, a fluoro-substituted alkyl group, an alkenyl group, a cyano group, an acetyl group or a hydroxyl group, and two of R _{1 to} R ₆ Represents a hydroxyl group, and R _{1 to} R
_A compound in which each one of ₃ and R _{4 to} R ₆ is a hydroxyl group is preferable, and a compound in which a hydroxyl group is bonded to the 4,4 ′ position is particularly preferable. Also, naphthalene diols can be used. Of these bifunctional phenol compounds, bisphenol A, bisphenol F, biphenol, methylene-bridged o-cresol, and perfluoropropylidene bisphenol are most preferred. The amount of the bifunctional phenol compound used is 1/9 equivalent or less and 1/30 equivalent or more based on the raw material o-cresol novolac epoxy resin. The more the amount of the bifunctional phenol compound is used, the higher the softening point of the obtained epoxy resin tends to be.

In order to obtain the epoxy resin of the present invention, it is preferable to use a catalyst. As the catalyst, caustic soda,
Caustic alkalis such as caustic potash, imidazoles such as 2-ethyl-4-methylimidazole, amines such as polyamines, and phase transfer catalysts such as tetrabutylammonium bromide, tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide. And phosphorus-based catalysts such as phosphines such as triphenylphosphine, tolylphosphine and methoxy-substituted phosphine, and phosphonium salts such as tetraphenylphosphonium borate. Of these, phosphorus-based catalysts are preferred, and phosphines are particularly preferred.
The amount used is preferably about 0.2 to 3% by weight based on the epoxy resin as the raw material.

The reaction is usually carried out at 50 to 170 ° C, preferably at 60 to 150 ° C. The reaction time depends on the reaction temperature, but is usually about 1 to 15 hours. The reaction system is preferably in an atmosphere of an inert gas such as nitrogen. After completion of the reaction, the reaction is preferably completely stopped by removing or inactivating the catalyst. If the catalyst remains in the target epoxy resin or its solution, when it is combined with a phenol-based, acid anhydride-based, or amine-based curing agent to form a curable composition, storage stability problems may occur. In addition, it is necessary to adjust the dosage of the catalyst to be used each time for the adjustment of the gel time, the problem of the reproducibility of the gel time, and the resulting problem of the stability of the prepreg, This is not preferable because it causes problems such as difficulty in controlling the thickness of the sheet. Also, from the viewpoint of the performance of the obtained resin, it is preferable to remove the catalyst as much as possible. Among the usable catalysts, caustic alkalis and amines can be removed by neutralization and the like, and phase transfer catalysts and phosphonium salts can be removed by washing with water, and phosphines cannot be converted into phosphine oxide by oxidation or reaction with epoxy groups. Can be activated.

When phosphines are used in the reaction for obtaining the epoxy resin of the present invention, the residual amount of phosphines in the epoxy resin is 500 ppm or less, preferably 1 ppm or less.
It is preferably at most 00 ppm. In particular, after obtaining the epoxy resin of the present invention using an organic solvent, it is advantageous in terms of cost as it is as a varnish or as a raw material of the varnish, but the content of phosphines must be kept low. . For reference, a gas chromatographic method is recommended as a method for quantifying triphenylphosphine. Attention should be paid to using a solvent containing peroxide (methyl ethyl ketone, tetrahydrofuran, etc.) at the time of preparing an injection sample, since the value becomes inaccurate.
Methylene chloride can be used without this problem. Also, it is preferable to confirm by a blank test.

In the epoxy resin of the present invention thus obtained, the epoxy group of the o-cresol novolak type epoxy resin reacts with the hydroxyl group of the bifunctional phenol compound, and a part of both reacts with —OCH ₂ CH (OH) CH _2. Although it has a structure linked via an O-bond, the main skeleton in the molecule is a novolak skeleton in which o-cresol is linked via a methylene bond. The softening point of the epoxy resin of the present invention is JIS K
The temperature is 100 ° C. or higher, preferably 105 to 135 ° C. by a measuring method according to −7234.

The epoxy resin of the present invention can be used as a varnish for laminates by mixing with an organic solvent or as an epoxy resin solution synthesized using an organic solvent as described above. In order to use as a varnish for laminates, a curable composition is obtained using the curing agent and catalyst described below, a glass fiber is impregnated to obtain a B-stage prepreg, which is laminated and heat-cured. I do.

Hereinafter, the epoxy resin composition of the present invention will be described. The epoxy resin of the present invention can be made into a curable composition by combining it with a curing agent such as a polyphenol compound, amines, acid anhydrides, imidazoles, and dicyandiamide. Specific examples of the curing agent used in this case include methylenebisaniline, methylenebisalkylaniline, diamines such as diaminodiphenylsulfone, phthalic anhydride, nadic anhydride, acid anhydride such as methylnadic anhydride tetrahydrophthalic anhydride and the like. Products, phenol-novolak, cresol-novolak, aralkylenephenol or naphthol resin known under the trade name of Xyloc, naphthalenediol, bisphenols, biphenols, dicyclopentadiene- Examples include polyphenols such as phenol resin and biphenol bismethylene phenol resin, and amides such as dicyandiamide. The amount of the curing agent used is not particularly limited, but is preferably approximately equivalent to the epoxy equivalent of the epoxy resin. Among them, the use of polyphenols having high moisture resistance and reliability, such as phenol novolak and cresol novolak, is particularly suitable for electronic equipment.

The epoxy resin composition of the present invention optionally contains a curing catalyst. As the curing catalyst, known catalysts such as imidazole-based, phosphine-based, phosphonium borate compounds and tertiary amine-based compounds can be used. For example, phenylimidazole, 1-benzyl-2
Imidazole compounds such as -methylimidazole 2-methylimidazole, phosphine compounds such as triphenylphosphine, tolylphosphine, and methoxy-substituted triphenylphosphine; tetraphenylphosphonium tetraphenylborate; Phosphonium borate compounds such as tetraphenylphosphonium tetranaphthoyloxyborate, and tertiary amine compounds such as diazabicycloundecene and benzyldimethylamine can be used. Of these, phosphine compounds are particularly suitable. It is preferable to use 0.1 to 5% by weight of the epoxy resin composition.

The epoxy resin composition of the present invention comprises silica,
Alumina, calcium carbonate, magnesium hydroxide,
An inorganic filler such as aluminum hydroxide can be filled. Incidentally, a flame-retardant cured product containing no halogen-based flame retardant can also be obtained by using these fillers. The content ratio is suitably from 5 to 90% by weight of the whole composition, and particularly preferably from about 10 to 85% by weight.

The epoxy resin composition of the present invention is obtained by uniformly mixing the above components, and can be used as an adhesive for electronic materials, an adhesive film, a paint, a binder for a laminate, and the like. The curing of the epoxy resin composition of the present invention is 100
It is good to carry out at ~ 250 ° C. When post-curing is performed for several hours at a curing temperature or higher, the performance of the cured product is improved.

[0020]

Next, the present invention will be described more specifically with reference to examples. In the following examples, the unit of the epoxy equivalent is g / eq, and the softening point is JIS K-72.
34 was measured.

Example 1 21.4 g of o-cresol novolak type epoxy resin having a softening point of 90 ° C. (Nippon Kayaku product name: EOCN-104S, epoxy equivalent: 220), 0.7 g of methylenebis (o-cresol) (equivalent ratio: 1 / 17.4), and 10 g of methyl ethyl ketone as a solvent was placed in a 100 ml flask and heated to dissolve. Then this is 70-80 ° C
While stirring, triphenylphosphine was added to the mixture.
2 g was charged and reacted. The epoxy equivalent was followed over time, and the residual amount of triphenylphosphine was determined at the same time. The results are shown below. Reaction temperature Reaction time Epoxy equivalent Amount of triphenylphosphine 70 ° C 5 hours 237 2050ppm 80 ° C 1.5 243 410 80 ° C 5 246 70 (both epoxy equivalent and triphenylphosphine amounts are based on resin excluding solvent) After a total of 11.5 hours, an epoxy equivalent of 253 and a softening point of 11
A methyl ethyl ketone solution of the epoxy resin of the present invention having a triphenylphosphine content of 70 ppm at 6 ° C. was obtained.

Example 2 A reaction was carried out in the same manner as in Example 1. However, the amount of methylene bis (o-cresol) used was 0.98 g (equivalent ratio: 1).
/12.6). After reacting at 80 ° C. for 7 hours, a methyl ethyl ketone solution of the epoxy resin of the present invention having an epoxy equivalent of 262, a softening point of 125 ° C. and a triphenylphosphine content of 80 ppm was obtained.

Example 3 In a flask having a capacity of 200 ml, 42.8 g of an o-cresol novolak type epoxy resin (EOCN-104S: epoxy equivalent 220) and methylene bis (phenol) 2.
07 g (equivalent ratio: 1 / 9.4) and 38 g of methyl isobutyl ketone as a solvent were charged and dissolved by heating. Next, 0.4 g of triphenylphosphine was added thereto while stirring at 70 ° C., and reacted at 100 to 110 ° C. for 4.5 hours. After completion of the reaction, the solvent was distilled off under reduced pressure to obtain an epoxy resin of the present invention having an epoxy equivalent of 265, a softening point of 127 ° C and a triphenylphosphine content of 50 ppm.

Example 4 In a flask having a capacity of 200 ml, 37 g of o-cresol-novolak type epoxy resin (EOCN-104S: epoxy equivalent 220), hexafluoro-2,2'-propylidene (4,4'-bisphenol) 2.2 g (equivalent ratio 1
/12.8), methyl isobutyl ketone 33 as a solvent.
g was added and heated to dissolve. Then this is 70 ° C
While stirring, triphenylphosphine was added to the mixture.
37 g was charged and reacted at 100 to 110 ° C. for 3 hours. After completion of the reaction, methyl isobutyl ketone was distilled off under reduced pressure to obtain an epoxy resin of the present invention having an epoxy equivalent of 256 and a softening point of 120 ° C. The residual amount of triphenylphosphine in the obtained epoxy resin was 40 ppm.

Examples 5 to 7 An epoxy resin having a different residual amount of triphenylphosphine obtained in the same manner as in Examples 1 and 2 except that the reaction time was changed was mixed with an equivalent amount of phenol novolak (softening point 83 ° C.). When 1% by weight of triphenylphosphine was added as a curing agent to the epoxy resin, and the gel time was measured at 175 ° C. (a test method of measuring on a hot plate while stirring with a spatula), the following results were obtained. Was. Comparison between Example 5 and Example 6 shows that the remaining triphenylphosphine has a considerable effect on the gel time of the curable composition. Example 5: Epoxy resin according to Example 1 (remaining amount of triphenylphosphine 1000 ppm) 25 seconds Example 6: Epoxy resin according to Example 1 (remaining amount of triphenylphosphine 70 ppm) 29 seconds Example 7: According to Example 2 Epoxy resin (triphenylphosphine residual amount 80ppm) 23 seconds

[0026]

According to the present invention, it is possible to obtain an o-cresol novolac type skeleton epoxy resin having a high softening point of 100 ° C. or more, which has been difficult to produce in the past. Materials useful for agents, adhesive films, paints, binders for laminated boards, and the like can be provided.

Claims (8)

[Claims] 1. An epoxy resin having an o-cresol novolak skeleton as a main skeleton and having a softening point of 100 ° C. or more. 2. An o-cresol-novolak type epoxy resin having a softening point of 60 to 98 ° C. in an amount of 1/9 equivalent or less,
The epoxy resin according to claim 1, which can be obtained by reacting at least 30 equivalents of a bifunctional phenol compound. 3. The epoxy resin according to claim 2, which is an epoxy resin produced by using a phosphine as a catalyst, wherein the content of the phosphine in the epoxy resin is 500 ppm or less. 4. An o-cresol-novolak type epoxy resin having a softening point of 60 to 98 ° C. in an amount of 1/9 equivalent or less,
A method for producing an epoxy resin, which comprises reacting at least 30 equivalents of a bifunctional phenol compound. 5. The method according to claim 4, wherein the reaction is carried out in an organic solvent. 6. The reaction according to claim 4, wherein the reaction is performed in the presence of a phosphorus-based catalyst.
Or the method for producing an epoxy resin according to 5. 7. An epoxy resin solution containing the epoxy resin according to claim 1 and an organic solvent. 8. An epoxy resin composition comprising the epoxy resin according to claim 1 and a curing agent.