JPS5834822A - Production of cyanato group-containing phenolic resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin excellent in thermal properties, etc., by reacting a solution of a trialkylammonium salt of novolak, prepared by reacting novolak of a specified MW with a trialkylamine in the presence of an organic solvent, with an excess of a cyanogen halide at a specified temperature. CONSTITUTION:Novolak of number-average MW 300-1,500, represented by the formula, wherein R1-4 are each H or methyl and a is 1-10, is mixed and reacted with a trialkylamine (e.g., triethylamine) in the presence of an organic solvent (e.g., dichloromethane) in such a ratio that one trialkylamine molecule is present per phenolic hydroxyl group to be converted into a cyanato group of the novolak. Then the titled resin is prepared by reacting the resulting solution of a trialkylammonium salt of novolak with an excess of a cyanogen halide at a temperature of 30-65 deg.C (1-2 cyanogen halide molecules are present per ammonium salt of the hydroxyl group to be converted into a cyanate group).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cyanato group-containing phenolic resin.

Conventionally, the manufacturing method of cyanato group-containing phenolic resin is as follows:
A method of reacting a novolak with an average molecular weight of about 600 to 1500 that is soluble in an organic solvent and a cyanogen halide at a temperature of -30 to 65°C in the presence of a base in a solvent (41 Kosho 4
5-11712), a method of reacting a 7-dinol nopolac having a number average molecular weight of 300 or more and less than 600 with cyanogen fluoride in the presence of a base (Japanese Patent Publication No. 53-42076);
However, these documents do not teach a method in which a solution obtained by reacting a novolac and a trialkylamine in the presence of an organic solvent is reacted with an excess cyanogen halide solution. Alternatively, a method of reacting with excess cyanogen halide di- or poly-triflukylammonium ferulate in the presence of a trialkylamine and an organic solvent (
JP-A-5-1-1 osos 7) specifically exemplifies the raw material phenolic hydroxyl group-containing compound from page 3, column 3 to page 4, column 4, and also provides numerous examples. However, there is no mention or suggestion of the use of novolak.

The present inventor conducted intensive studies on an industrial method for producing a cyanato group-containing phenol resin suitable for obtaining a cured resin product with excellent properties such as thermal properties, and found that the phenol novolac should be a trialkylammonium salt. By.

In addition to being well soluble in a solvent such as dichloromethane, the solution of the trialkylammonium salt of this 7-enol novolak contains free trialkyl 7! The present inventors have discovered that it is possible to effectively react with an excess cyanogen halide in an organic solvent solution even in the absence of cyanide, and that a cyanato group-containing phenolic resin with excellent curing properties can be obtained, and the present invention has been completed. It is something.

That is, the present invention has a number average molecular weight of 500 to 1,500.
A cyanato group characterized by reacting volac and trialkylamine in the presence of an organic solvent by mixing to obtain a trialkylammonium salt solution of novolac, and reacting 1 wL of the solution with excess cyanogen halide at a temperature of -30 to 65°C. This is a method for producing resin containing phenol.

The novolak of the present invention has a number average molecular weight of 300 to 1500.
It is a novolak obtained from formaldehyde and seven enols such as phenol, cresol, and xylenol as raw materials, and is represented by the following formula.

(R1-R4 in the formula represent a hydrogen atom or a methyl group,
1B is a positive number from 1 to 10, which may be the same or different. ) Triflukylamine is a compound represented by the following formula % (wherein Ri, Rn, and Rt represent a straight chain or branched alkyl group having 1 to 4 carbon atoms), and is trimethylamine.

Triethylamine, dimethylethylamine, methyldiethylamine, tripipylamine, triisopropyl gamma
J, tributyl urea 17. Examples include.

The above-mentioned novolak and trialkylamine are heated and reacted in the presence of an organic solvent to obtain a trialkylammonium salt solution of novolac. The ratio of novolac to trialkylamine is one molecule of trialkylamine for each phenolic hydroxyl group of the novolak to be cyanated. At this time, if the amount of trialkylamine is less than 1 with respect to the phenolic hydroxyl group to be cyanated, free phenolic hydroxyl groups are generated, and therefore, the cyanate ester group-containing phenol resin obtained by reaction with cyanogen halide The content of unreacted 7-ether hydroxyl groups increases. This unreacted phenolic hydroxyl group in the cyanate ester group-containing phenolic resin does not pose a problem if it exists in a small amount, but if it exists in a large amount, it will affect the curing properties of the cyanate ester group-containing phenol resin. This is not preferable because it lowers the Conversely, if the amount of trialkyl-7mine is used in excess of the phenolic hydroxyl group to be cyanated, the cyanate group-containing phenol resin obtained by the reaction with cyanogen halide may be cured. Although there is no 4IK change in the properties, excessive use of triflukylamine also requires excessive use of cyanogen halide, which leads to deterioration of the 2M unit consumption, which is undesirable.

Cour cyan and boom cyan can be used as the cyanide halide, but chlor cyan is particularly preferred. The amount of cyanogen halide to be used is one or more molecules, preferably 1 to 2 molecules, per triflukylammonium salt of a hydrous acid group to be cyanated from the raw material phenol novolak trialkylammonium salt.

Examples of organic solvents that can be used in the present invention include hydrocarbons, chlorinated hydrocarbons, dihydrocarbons, alcohols, ethers, ketones, and esters. Examples include: petroleum ether, benzene,
toluene.

Xylene, dichloromethane, chloroform, imprisoned chloride, dicoolethane, perchloroethane.

Chlorobenzene, dichlorobenzene, nitromethane,
Nido-benzene, nitrotoluene, methanol, ethanol, propatool or impropanol, diethyl ether, :) isopropyl ether, methyl-1er-
Butyl ether, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl in butyl ketone.

Examples include ethyl acetate and acetonitrile, and preferably,
Dichloromethane, nitromethane, methanol, dioxane, 7setone, methyl in butyl ketone, acetonitrile, and preferred for 4I are dichloromethane and acetone. These solvents are used alone or in mixtures thereof in the presence or absence of small amounts of water.

The reaction temperature is generally -30 to 65°C, preferably -5 to 30°C. This method is generally carried out by introducing a solution of a Novo 1 rank trialkylammonium salt into an organic solvent in which a cyanide halide has been dissolved under stirring. It can be obtained by removing the solvent from under reduced pressure, or by dropping this reaction product liquid into a poor solvent for this resin.

The cyanate ester group-containing phenol resin obtained by the method of the present invention is cured by forming network bonds by heating and/or in the presence of a curing agent, and has a glass transition temperature of, for example, 300°C.
The above-mentioned thermally excellent cured resin product is obtained.

The f1 invention will be explained in more detail below with reference to Examples.

Example 1 Phenol 160y and formalin (CHnO37%)
Mixed solution with 95I @Oxalic acid 0.8I as IIC catalyst
I, add hydrochloric acid (35%) 0.51, 99-100
The mixture was heated at .degree. C. and reacted for 80 minutes under flowing after emulsification, followed by dehydration under reduced pressure to obtain a solid novolak. According to GPC measurement using tetrahydropran as a solvent, 27% of unreacted phenol and n = 00 were found.
2t Total of 3 items is 45%, ≧4 items is 28%,
The number average molecular weight is 32B and its melting point is 65-71℃
Met.

The above phenol novolac 24y51V was dissolved in a mixed solution of triethylamine 24.2 & acetone 491, and under stirring at 0°C, chlorocyan 17I and acetone.
It was added dropwise into the solution of 6B&. The reaction temperature is 5 to 10. '
I invested in C. After the reaction was completed, triethylamine hydrochloride as a by-product was removed by suction F:jlK, and then Pt was concentrated under reduced pressure to obtain a cyanate ester group-containing phenol resin. This resin was in a liquid state and had a number average molecular weight of 480 according to GPC # determination.

According to the IR spectrum, the absorption by the phenolic hydroxyl group near 5400 m-' disappears, and the absorption at 2250 cm-'
A characteristic absorption of dianic acid ester groups was observed, and the hydroxyl groups were substantially [100%] cyanated.

The cured product obtained by melt-molding the phenolic resin containing a cyanate ester group at 150°C and sufficiently curing at 200°C has a glass transition point as determined by the measurement of the coefficient of thermal expansion. The temperature was 3°0°C or higher.

Example 2 A product similar to Example 1 was obtained by carrying out the same procedure as Example 1 except that dichloromethane was used instead of acetone. The glass transition point of this cured product was 600°C or higher - Example 3 Phenol 160y was heated to 90°C, formalin (
CH3057%) 1085/ and 4.6 y of oxalic acid were added dropwise over 2 hours, and then reacted at 90°C for 8 hours. 40℃
After cooling to , the aqueous layer was separated and further washed with 500 d of hot water. Thereafter, the mixture was dehydrated under reduced pressure at 40 iIJl (%) to 160°C to obtain a novolak.

According to GPC, this novolac contains 3% unreacted phenol and fi=o, 23% total of 1m≧4, and 74% of 1m≧4, and has a number average molecular weight of 850. Moreover, the softening point was 124°C.

The above Novolank was dissolved in a mixed bath of 22°5y of triethylamine and 491y of dichloromethane, and under stirring at 0°C, 17yy of Glorcian and 68y of dichloromethane were added. ! /
into the solution. The reaction temperature was kept between 5 and 10°C. After the reaction is complete, the by-product triethyl-? After removing amine hydrochloride by suction filtration, FM was concentrated under reduced pressure to obtain a cyanate ester group-containing phenol resin. This resin showed no inherent melting point and had a number average molecular weight of 1050 according to GPC measurements.

According to the IR spectrum, there was a strong absorption of cyanate ester groups at 2250 cmK, and a slight absorption due to unreacted phenolic hydroxyl groups was observed around 3400 CIK-'. The glass transition point of the molded and cured product of this resin is 26.
8℃ ◇Example 4 n-cresol 108y and formalin (37%) 6
Oxalic acid 0.2II and hydrochloric acid (35%) 0.5y as a catalyst to the mixed solution with 5y. Add IJ/ and lower It wave 4.
React for 5 hours and then.

Dehydration was carried out under reduced pressure to obtain a solid 7 vol. According to GPCK, the total of n:1, 2.5 is 65%.

The number average molecular weight was 550 and the melting point was 85 to 95°C.

The above m-talesol novolac 24.5y was dissolved in a mixed solution of triethylamine 21.1jl and dilak methane 49y, and chlorocyan 15v was added under stirring at 0°C.
, into a solution of dichloromethane 6811. The reaction temperature was kept between 5 and 10°C. After the completion of the reaction, the product triethylamine hydrochloride was removed by suction filtration, and the P solution was concentrated under reduced pressure to obtain 1 containing a cyanate ester group.
1:1 resin was obtained.

The melting point of this resin was 55 to 57°C.

According to the I& spectrum, there was a strong absorption at 2250z-"#C, and the absorption of the phenolic hydroxyl group around 5400aIL-" disappeared. The glass transition point of a molded and cured product of this resin was 300°C or higher.Example 5 5.5 xylenol 122y and formalin (CHso
57%) Oxalic acid as a catalyst in the mixed solution with 61y
Add 0,2II and 0.1y of salt [1 (55%),
Heated at 90°C, emulsified, reacted at 90°C for 2 hours, and then dehydrated under reduced pressure at 60 uH& to 160°C to obtain a solid novolac *According to GPCK, H==1.2
．． The total amount of S was 72%, and the number average molecular weight was 520.

The melting point was 90-98°C.

24.51 of the above novolac to 1 part of triethylamine
B, 9JF was dissolved in a mixed solution of 49 J/dichloromethane, and the solution was added dropwise to a solution of Rollsian 14&' and dichloromethane 68&' with stirring at 0°C. The reaction temperature is 5 to 10
Keep at ℃? Ta. After the reaction was completed, the by-product triethylamine hydrochloride was removed by suction filtration, and then the P solution was concentrated under reduced pressure to obtain Okiya resin containing cyanate ester groups.

This resin has a melting point of 69 to 75°C.

According to the IR spectrum, 22500 II-”K
The absorption of phenolic hydroxyl groups near 3400cxr-'@ disappeared. The glass transition point of a molded and cured product of this resin was 280°C.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative Kazuyoshi Nagano

Claims (1)

[Claims] Novolac having a number average molecular weight of 300 to 15,000 and triflukylamine are combined and reacted in the presence of an organic solvent to obtain a trialkylammonium salt solution of novolac, and the solution is mixed with excess cyanogen halide at a temperature of -30 to 65°C. A method for producing cyanato group-containing phenolic resin characterized by reaction