JPH0514724B2 - - Google Patents

Description

[Detailed description of the invention]

The object of the present invention is to easily produce a linear high molecular weight novolac resin that does not contain gel and is soluble in solvents and has a softening point of 145°C or higher, specifically, a random copolymerized novolac resin of p-cresol and o-cresol. The aim is to provide a method for doing so. (Industrial Application Field) The novolak resin obtained by the production method of the present invention has an extremely high softening point, and has excellent solubility in various solvents and compatibility with epoxy resins such as phenol novolac type epoxy resin. ing.
Therefore, this resin can be used for various purposes as a novolak resin, and can be particularly advantageously used as a curing agent for epoxy resins such as phenol novolak type epoxy resins. (Prior Art) Novolak-type phenolic resins are generally produced by polycondensing phenols with aldehydes in the presence of an acidic catalyst. Novolak-type phenolic resins are widely used as thermosetting resins, but their number average molecular weight is approximately 250 to 1000, and obtaining novolak-type phenolic resins with higher molecular weights may cause gelation. This made it virtually impossible or extremely difficult. The reason why phenol does not have a high molecular weight in the novolac type phenol resin production reaction is that the condensation reaction with aldehyde can occur at a total of three positions, two ortho positions and one para position with respect to the OH group, which is likely to cause gelation. is one of the reasons. To this end, conventional methods have used monosubstituted phenols with substituents at the ortho or para position of the OH group as raw materials, and by limiting the number of reaction points to two, gelation has been prevented and high molecular weight resins have been produced. An attempt was made. For example, Journal of Polymer. Science Vol. 20, pp. 75-88 (1956) describes the number average molecular weight (hereinafter referred to as "Mn") obtained by polycondensing p-chlorophenol and formaldehyde.
It has been reported that a high molecular weight novolac-type parachlorophenol resin having a molecular weight of 1,600 to 3,300 or more was obtained, and in the same document, Vol. 32, pp. 221-228 (1958), p-chlorophenol and formaldehyde were It has been reported that a high molecular weight novolac type chlorophenol resin with Mn of 1610 or more or 3640 or more was obtained by polycondensation in the same manner and further acetylation. However, this result was subsequently denied, and it was reported that the Mn of the acetylated product was less than 1250 (Brechin Chemical Society of Japan Vol. 36, p. 580-
585 pages). Also, Industrial Chemistry Journal, Vol. 66, pp. 95-99 (1963)
In this method, Mn is obtained by polycondensing nonylphenol and paraformaldehyde in benzene or toluene using a p-toluenesulfonic acid catalyst.
Novolac resins with Mn of 1555, 2735, or 4560 were obtained; however, the resin with Mn4560 also contained a poorly solvent-soluble component (gel), and the molar ratio of p-cresol and nonylphenol was 2:2. When mixed and polycondensed in step 1, Mn
It has been reported that only 1355 resin could be obtained. These reports indicate that when high-molecular-weight nonylphenol is used as the raw material substituted phenol, a high-molecular-weight resin can be obtained, but from low-molecular-weight cresol, only a relatively low-molecular-weight resin can be obtained at the same degree of polymerization. This shows that the formation of solvent-insoluble matter (gel) is unavoidable if one attempts to obtain a high-molecular-weight resin. In addition, regarding the manufacturing method of high molecular weight ortho-para-cresol copolymerized novolak resin,
It is described in Publication No. 92908. That is, Mn is 550
By reacting the orthocresol novolac resin with 2,6-dimethylol-p-cresol in o-dichlorobenzene solvent in the presence of nitric acid, a linear high molecular weight soluble in dimethylacetamide with Mn of 1930 was obtained. It is stated that an ortho-para-cresol copolymer resin was obtained and that its softening point was 134°C. However, the resin obtained by this method is an ortho/para-cresol block copolymer, and the resin with the highest Mn value (Mn = 1930), the resin with an ortho/para-cresol ratio of 80/20, has a softening point of 134. ℃, and has a relatively low softening point. (Problems to be Solved by the Invention) In short, various methods have been known for producing phenol novolac resins. A simple and easy method for producing gel-free novolak resin has not been found. The present invention is made directly from easily available low molecular weight phenols, which have a significantly high softening point of 145°C or higher, and which have remarkable solubility and compatibility with various solvents and epoxy resins such as novolac type epoxy resins. The object of the present invention is to provide a simple and easy method for producing an excellent gel-free linear high molecular weight novolak resin. (Means for Solving the Problem) The object of the present invention is to use a mixed cresol containing p-cresol and o-cresol in a specific ratio as a raw material phenol, and to prepare the mixed cresol with formaldehyde in a specific polar organic solvent in the presence of an acidic catalyst. This can be achieved by polycondensation reaction with That is, the method for producing a linear high molecular weight cresol novolak resin having a softening point of 145°C or higher according to the present invention is based on p
- 92 to 45 mo% of cresol and 8 to o-cresol
55 mol% of mixed cresol and formaldehyde are combined with alkyl alcohols having 3 to 12 carbon atoms, glycol ethyls of alkyl alcohols having 3 to 12 carbon atoms, benzyl alcohol, and 1 to 1 carbon atoms.
This method is characterized in that the reaction is carried out in a polar solvent selected from the group consisting of 6 alkylcarboxylic acids in the presence of an acidic catalyst. In the present invention, as the raw material phenol, p-cresol is used in an amount of 92 to 45 mol%, preferably 90 to 50 mol%.
A mixed cresol of 8 to 55 mol %, preferably 10 to 50 mol % of o-cresol is used. As the proportion of p-cresol increases (that is, as the proportion of o-cresol decreases), the resulting novolak resin has a higher softening point, but its solubility in solvents and its compatibility with novolak-type epoxy resins deteriorate. In the present invention, the formaldehydes to be reacted with mixed cresol are a general term for formaldehyde and substances that can easily generate formaldehyde in the reaction system, such as formaldehyde solvent solutions (formalin, etc.), paraformaldehyde, trioxane, etc. . Particularly preferred formaldehydes are paraformaldehyde and trioxane. Of course, an aqueous formaldehyde solution such as formalin can be used, but it is not preferred because it increases the water content of the reaction system. The proportion of formaldehyde used in the present invention is 0.57 to 1.5 mol, preferably 0.9 to 1.3 mol, per 1 mol of cresol. If the proportion of formaldehyde used is too small, the resulting resin will not have a high molecular weight and only a low melting point resin will be obtained. Furthermore, if the proportion of formaldehyde used is too high, it may cause gelation of the resulting resin, resulting in a decrease in solubility in solvents or a decrease in compatibility with epoxy resins. The reaction solvent in the present invention has 3 to 3 carbon atoms.
A polar solvent selected from the group consisting of C12 alkyl alcohols, glycol ethers of alkyl alcohols having 3 to 12 carbon atoms, benzyl alcohol, and alkyl carboxylic acids having 1 to 6 carbon atoms is used. Specific examples include alkyl alcohols such as propanol, butanol, amyl alcohol, and hexanol; glycol ethers of alkyl alcohols such as methoxyethanol, ethoxyethanol, and butoxyethanol;
Benzyl alcohol; examples include formic acid, acetic acid, propionic acid, and butyric acid. In the present invention, the specific polar solvent described above is used to react cresol and aldehyde in a solvent that does not have a hydroxyl group or carboxyl group capable of hydrogen bonding in the molecule, such as an aromatic hydrocarbon or an ether. This is because the molecular weight does not increase even when reacted, whereas the molecular weight easily increases when the specific solvent used in the present invention is used. This is thought to be because the polar solvent in the present invention solvates with the phenolic hydroxyl group of the cresol novolak resin through hydrogen bonding, which makes the resin more likely to polymerize. As the reaction catalyst in the present invention, an acid catalyst, preferably an acid containing protons, is used. Examples include inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, and perchloric acid; and organic acids such as p-toluenesulfonic acid and oxalic acid. However, Lewis acids are not preferred. The ratio of acid catalyst used is 100% cresol as raw material.
0.01 to 20 parts by weight, preferably 1 to 20 parts by weight
15 parts by weight. The reaction temperature in the present invention is usually 95°C.
Above, preferably a temperature of 105 to 150°C is used. If the reaction temperature is too low, the reaction rate will be slow; if the reaction temperature is too high, there is a risk of gelation of the resulting resin. To explain in more detail the aspects of the production reaction of the present invention, the reaction components are prepared by thoroughly mixing the raw materials p-cresol and o-cresol in advance,
For example, a raw material cresol mixture, formaldehyde, a reaction solvent, and an acid catalyst are charged in a predetermined ratio, and the mixture is heated slowly while stirring to reach the reaction temperature, and then reacted for a certain period of time, or the raw material cresol mixture, the reaction solvent, and the and an acid catalyst, heated to reach the reaction temperature, then add formaldehydes and an acid catalyst dissolved in a solvent and react for a certain period of time, or prepare a cresol mixture, formaldehydes and a reaction solvent,
A method is used, such as heating with stirring to raise the temperature to around the reaction temperature, and then dropping an acid catalyst or its solvent solution to cause a reaction. If the amount of water in the production reaction system of the present invention is too large, not only will formaldehydes be consumed by side reactions resulting in loss, but it will also hinder the increase in the molecular weight of the produced resin. Further, since high molecular weight novolak resins become insoluble and precipitate in solvents with a high water content, they tend to cause heterogeneous reactions and become a hindrance to increasing the molecular weight of the resin. Therefore, the water content of the reaction system is 15% by weight or less, preferably 10% by weight.
It is desirable to keep it below. For this purpose, a so-called azeotropic solvent (e.g. n
-butanol, etc.), react under reflux, and azeotrope excess water with the solvent to be discharged from the system. In order to separate and recover the produced novolak resin after the completion of the reaction, for example, when a water-soluble solvent (for example, methoxyethanol, ethoxyethanol, formic acid, acetic acid, etc.) is used as the reaction solvent, the reaction product can be Pour into 20 times the volume of water and separate and collect the resin produced as a water-insoluble resin. Also,
When a water-insoluble solvent (for example, n-butanol, n-hexanol, benzyl alcohol, etc.) is used as the reaction solvent, the reaction product is washed with water or neutralized to remove the acid catalyst, and then the reaction solvent is distilled off. The resulting resin is separated and recovered as a molten resin. (Effect) In the present invention, p-
Mixed phenol, which is a mixture of cresol and o-cresol in a specific ratio, is used and the reaction is carried out in a specific reaction solvent in the presence of an acid catalyst, so it has a high softening point of 145°C or higher, and is also suitable for solvents and novolac types. A gel-free, linear, high molecular weight, ortho-para-cresol random copolymerized novolac resin is obtained which has excellent solubility and compatibility with epoxy resins such as epoxy resins. As the proportion of p-cresol in the mixed cresol increases, the resulting novolak resin will have a higher softening point, but its solubility in solvents and compatibility with novolak-type epoxy resins will decrease. As the proportion of p-cresol decreases, the softening point of the produced novolak resin decreases. Furthermore, since the above-mentioned specific polar solvent is used as a reaction solvent, it strongly solvates the cresol novolak resin, making it easy for the resin to polymerize. That is, the above polar solvent has a hydroxyl group or carboxyl group that forms a hydrogen bond in its molecule, and by hydrogen bonding with the phenolic hydroxyl group of the cresol novolak resin, it is strongly solvated, and as a result, the resulting resin becomes a polymer. be converted into As described above, the novolak resin obtained by the production method of the present invention has a significantly high softening point of 145°C or higher, does not contain gel, has excellent solubility in various solvents, and is compatible with epoxy resins such as novolak type epoxy resin. It is a linear high molecular weight para-orthocresol random copolymerized novolak resin with excellent compatibility. In general, the higher the softening point of a novolac resin, the better its stability at high temperatures and the less likely it is to cause thermal decomposition. The novolak resin obtained by the production method of the present invention has a high heat resistance.
It is particularly excellent as a curing agent for epoxy resins such as novolak type epoxy resins. That is, the novolak resin obtained by the production method of the present invention is an epoxy resin manufactured from a dihydric or higher phenol and epichlorohydrin, such as bisphenol A, bisphenol F, brominated bisphenol A, phenol novolak resin, o −
It exhibits excellent compatibility with epoxy resins such as cresol novolak resin, tetraphenolethane, tetrapromobisphenol A, etc., and epoxy resins produced from epichlorohydrin.
If the novolak resin obtained by the production method of the present invention is blended with these epoxy resins as a curing agent and cured, a cured product with extremely excellent heat resistance and mechanical properties can be obtained. Furthermore, the novolac resin obtained by the production method of the present invention is soluble in ethers such as tetrahydrofuran and dioxane; and polar solvents such as dimethylacetamide and dimethylformamide, and does not contain insoluble gel components. , is considered to be a linear high molecular weight para-orthocresol random copolymer resin, but its solubility in solvents is p-
It varies depending on the cresol/o-cresol molar ratio and molecular weight. The higher the molar ratio of p-cresol and the higher the molecular weight, the less soluble it becomes in a solvent. For example, resins with a p-cresol/o-cresol molar ratio of 5/5 and a softening point of 145°C or higher are soluble in the above-mentioned solvents, as well as ketones such as acetone and methyl ethyl ketone; methoxyethanol, ethoxy Glycol ethers such as ethanol; Esters such as acetate;
Although it is soluble in epichlorohydrin and epichlorohydrin, it is sparingly soluble in alcohols such as methanol, ethanol, and butanol. When the p-cresol/o-cresol molar ratio becomes higher than 5/5, the number of types of solvents gradually becoming poorly soluble increases. For example, resins with a molecular weight of 2000 and a softening point of 300°C or higher obtained by copolymerizing at a p-cresol/o-cresol molar ratio of 9/1 include tetrahydrofuran, dioxane, dimethylformamide, and dimethylacetamide. , soluble in solvents such as acetone, methyl ethyl ketone, methoxyethanol, ethoxyethanol, and benzyl alcohol, but alcohols such as methanol, ethanol, butanol;
It is insoluble or sparingly soluble in aromatic hydrocarbons such as benzene and toluene, chloroform, and trichloroethylene. Note that a resin with a softening point of 300°C or higher obtained by using p-cresol alone as the phenol and reacting in the same manner as the method of the present invention has poor solubility in solvents, and is not easily dissolved in tetrahydrofuran or dioxane. , dimethylformamide,
Although it is soluble in dimethylacetamide, it is sparingly soluble or insoluble in the other solvents listed above, and has poor compatibility with novolac type epoxy resins, even at temperatures above 150°C.
Even if it is kneaded with novolak type epoxy resin at a temperature above, it will not be uniformly compatible. The novolak resin obtained by the manufacturing method of the present invention has an Mn value of 1500 to 1,500 by vapor pressure method (VPO) using methyl ethyl ketone or dimethyl acetamide as a solvent.
5000 and the ratio of the weight average molecular weight measured by gel permeation chromatography using tetrahydrofuran as a solvent and the above Mn value (Q)
is within the range of 1.5 to 12, and the resin powder is further softened under a microscope. The softening point measured by the softening point measurement method, which measures the temperature at which the material becomes fluid and transparent, is within the range of 145 to 300°C or higher. The novolac resin obtained by the method described in JP-A No. 56-92908 is an ortho-para-cresol block copolymer with low solubility in solvents, and furthermore, due to its manufacturing method, it is an o-cresol/p-cresol block copolymer. - It is considered difficult to arbitrarily change the cresol molar ratio. In fact, the publication states that the molar ratio between the terminal end of the low molecular weight novolac resin used as the raw material and the -CH ₂ OH group of dimethylol-p-cresol is 1.0.
It is stated that the resin obtained in this case has the highest molecular weight, and that even if a cresol monomer was used instead of a low molecular weight novolak resin and reacted with dimethylol-p-cresol, a high molecular weight resin could not be obtained. has been done. In the examples of the same publication, the o-cresol/p-cresol molar ratio is
We manufacture resins with a molecular weight of 80/20, a molecular weight of 1930, and a softening point of 134°C. On the other hand, when using the production method of the present invention, the p-cresol/o-cresol molar ratio is
It can be changed arbitrarily within the range of 92/8 to 45/55, and the resulting resin has a significantly high softening point.
Moreover, it is an ortho-pararandom copolymer that has excellent solubility despite its high softening point and high p-cresol content, and is also excellent in compatibility with novolak type epoxy resins. In this way, the manufacturing method of the present invention is not only completely different from the manufacturing method described in the publication, but also the resulting novolak resin has a different softening point and copolymerization ratio. They are also completely different in terms of whether they are block copolymers or random copolymers. Next, to explain in detail the use of the novolak resin obtained by the production method of the present invention as a curing agent for epoxy resin, the epoxy resin blended with the novolak resin obtained by the present invention has two or more epoxy resins in the molecule. It is a compound having a group, and the blending ratio is 0.3 to 2.0 mol, preferably 0.5 to 1.5 mol, of the epoxy group of the epoxy resin per 1 mol of the phenolic OH group of the novolac resin. Examples of the epoxy resin include polyphenols such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, orthocresol novolak, and 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane. Epoxy resins manufactured from phenols and epihalohydrin; Epoxy resins manufactured from polyhydric phenols such as catechol, resorcinol, and hydroquinone and epihalohydrin; ethylene glycol, butanediol, pentaerythritol,
Glycidyl ether type epoxy resin of polyhydric alcohol such as polyethylene glycol; alicyclic epoxy resin such as dicyclopentadiene dioxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, vinylcyclohexene dioxide; phthal Epoxy resins include polyglycidyl ester type epoxy resins of acids, polycarboxylic acids such as hexahydrophthalic acid; polyglycidyl amines such as glycidylated products of diaminodiphenylmethane; and epoxy resins such as glycidylated products of aminophenol. Epoxy resins containing such novolac resins contain curing accelerators such as benzyldimethylamine, imidazoles, trisdimethylaminomethylphenol, and BF ₃ -piperidine salts, as well as fillers, mold release agents, and hardening agents as necessary. A combustion agent may be included. For example, a glass cloth is impregnated with a solution obtained by adding a solvent such as acetone or methyl ethyl ketone to the novolak resin, epoxy resin, and curing accelerator obtained by the manufacturing method of the present invention, and dried to produce a prepreg, and the number of sheets obtained is A copper-clad laminate for printed wiring boards can be obtained by stacking the prepreg with steel foil and hot pressing. Furthermore, a molding compound can be obtained by adding an epoxy resin, a hardening accelerator, a filler such as silica, and a lubricant to the novolak resin obtained by the production method of the present invention, and kneading the mixture with heated rolls. This compound is molded using a transfer molding machine or the like and used for semiconductor encapsulation, mechanical parts, etc. Epoxy resin, curing accelerator, and resins such as nylon, polyester, polyvinyl butyral, and carboxylic acid-containing butadiene nitrile rubber are blended into the novolak resin obtained by the manufacturing method of the present invention, and fillers are added as necessary. It can be used as an adhesive. Furthermore, an epoxy resin, a curing accelerator, and a filler are added to the novolak resin obtained by the production method of the present invention, and the mixture is kneaded with heated rolls, cooled, and then crushed with a crusher and sieved to obtain a powder coating. . Next, the novolac resin obtained by the production method of the present invention is soluble in an aqueous alkaline solution. Therefore, for example, if you mix this novolak resin with 1,2-naphthoquinonediazide, dissolve it in a suitable solvent, apply it to a suitable base material and dry it, and then irradiate the resulting coating with ultraviolet rays, only the exposed areas will disappear. Since it can be dissolved in weakly alkaline water, the resin obtained by the production method of the present invention can be used as a resin for photoresist agents. The following is a more detailed description of Examples, Comparative Examples, and Experimental Examples. Example 1 54 g of p-cresol, 54 g of o-cresol, 32 g of paraformaldehyde, and ethyl cellosolve
240g of the solution was placed in a reactor together with 10g of sulfuric acid, and the mixture was reacted at 115°C for 4 hours with stirring. 17g after completion of reaction
After neutralizing by adding NaHCO ₃ and 300 g of water, the reaction solution was poured into water 2 while stirring at high speed, and the precipitated resin was separated and dried to obtain 115 g of novolak resin. Vapor pressure method of this resin (methyl ethyl ketone, 40
The Mn value was 2800 by gel permeation chromatographic analysis of a tetrahydrofuran solution, the Q value was 2.4 by gel permeation chromatography, and the softening point by microscopy was 200°C or higher. In addition, this resin can be used for acetone, methyl ethyl ketone, methoxyethanol, ethoxyethanol,
Tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, ethyl acetate,
It was soluble in epichlorohydrin, but sparingly soluble in methanol and ethanol. Example 2 81 g of p-cresol, 27 g of o-cresol, 32 g of paraformaldehyde and ethyl cellosolve
240g of the solution was placed in a reactor together with 10g of sulfuric acid, and the mixture was reacted at 115°C for 4 hours with stirring. The p-cresol/o-cresol molar ratio in this reaction is 75/
It was 25. After the reaction is complete, 17g of _NaHCO3 and water
After neutralizing by adding 30g, add water 2 while stirring at high speed.
Pour the reaction solution into the container, separate the precipitated resin, and dry it.
114 g of resin was obtained. The Mn of the resin measured by vapor pressure method is 2000,
The softening point of the resin determined by microscopy was 300°C or higher, and the Q value of the resin was 2.2 by GPC. This resin is soluble in solvents such as tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, acetone, methyl ethyl ketone, methoxyethanol ethoxyethanol, butoxyethanol, benzyl alcohol, methyl acetate, epichlorohydrin, etc., but it is soluble in solvents such as methanol, ethanol, butanol, etc. It is insoluble or sparingly soluble in alcohol, aromatic hydrocarbons such as benzene and toluene, and halogenated hydrocarbons such as chloroform and trichloroethylene. Example 3 p-cresol 97.2g, o-cresol 10.8g
35.2 g of paraformaldehyde and 240 g of ethyl cellosolve were placed in a reactor together with 10 g of sulfuric acid, and the mixture was reacted at 115° C. for 6 hours with stirring. The reaction molar ratio of p-cresol/o-cresol in this reaction was 90/10. The reaction product was treated as in Example 2,
116 g of resin was obtained. The Mn of this resin measured by vapor pressure method using dimethylacetamide is 1900, and the softening point of the resin determined by microscopy is 300°C.
That's all. Example 4 54 g of p-cresol and 54 g of o-cresol were dissolved in 400 g of acetic acid, 4 g of sulfuric acid was added, the mixture was placed in a reactor, and the mixture was heated to 110°C. Separately, add 32 g of paraformaldehyde to 200 g of acetic acid, and add 6 g of sulfuric acid.
g was added and heated to 80° C. with stirring to dissolve paraformaldehyde. This paraformaldehyde solution was transferred to a dropping funnel and slowly added dropwise to the above cresol mixed solution over 1 hour to cause a reaction. After the dropping is completed, the temperature is 110°C for 2 more times.
After stirring for a period of time to react, the reaction solution was poured into the water in Step 6 that was being stirred at high speed, and the precipitated resin was separated, washed with water, and dried to obtain 115 g of resin. The Mn of this resin is 2700 by vapor pressure method.
The softening point determined by microscopy was 200°C. Example 5 p-cresol 59.4g, o-cresol 48.6
g, trioxane 30g, p-toluenesulfonic acid
15 g and 240 g of n-butanol were placed in a flask, and the reaction was carried out at 110 to 115° C. for 4 hours while water was removed azeotropically. After washing with water, the reaction product was poured into hexane in step 4 to separate the precipitated resin.
This resin has a Mn of 2900 and a softening point of 200℃
That's all. Example 6 81 g of p-cresol, 27 g of o-cresol, 30 g of trioxane, 360 g of benzyl alcohol, and 15 g of p-toluenesulfonic acid were placed in a reactor.
The reaction was carried out at 140°C for 4 hours. After washing the reaction product with water, it was poured into methanol (Step 8) to separate the precipitated resin. The Mn of this resin is 2200 and the softening point is 300℃
That's all. Comparative example 1 1080g of p-cresol, 37% formalin 3400g
g, 2000 g of 25% NaOH aqueous solution were mixed, reacted at 35°C for 4 hours, separated the formed precipitate, and neutralized with hydrochloric acid to form 2,6-dimethylol-p-cresol.
Obtained 800g. This 2,6-dimethylol-p-cresol
108 g of o-cresol was added to 168 g, placed in a reactor together with 540 g of o-dichlorobenzene and 1.6 ml of 60% nitric acid, and reacted at 175° C. for 4 hours with stirring. After the reaction was completed, the solvent was distilled off under reduced pressure of 10 mmHg, and the temperature was gradually raised to 180° C., and then the molten resin was taken out and cooled. The Mn of this resin is 950 by vapor pressure method.
The softening point determined by microscopy was 130°C. Also,
The p-cresol/o-cresol molar ratio of this resin was 50/50. This resin was soluble in tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, and pyridine, but poorly soluble in aromatic hydrocarbons such as benzene, toluene, and xylene. Comparative example 2 p-cresol 108g, paraformaldehyde
32g of ethyl cellosolve and 800g of ethyl cellosolve were placed in a reactor together with 10g of sulfuric acid, and the mixture was reacted at 115°C for 6 hours with stirring. After the reaction is complete, add 17g of _NaHCO3 and 30g of water.
After neutralizing with
117 g of resin was obtained. This resin had an Mn of 1800 determined by vapor pressure method using dimethylacetamide, and a softening point of 300° C. or higher by microscopy. Although this resin is soluble in tetrahydrofuran, dioxane, dimethylformamide, and dimethylacetamide, it is also soluble in alcohols such as methanol, ethanol, and butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and benzene, toluene, and xylene. It is insoluble in aromatic hydrocarbons, and is soluble in glycol ethers such as methoxyethanol and ethoxyethanol, but it becomes cloudy. Comparative example 3 p-cresol 21.6g, o-cresol 86.4g
g, paraformaldehyde, 32 g, and ethyl cellosolve, 240 g, were placed in a reactor together with 10 g of sulfuric acid, and the reaction was carried out in the same manner as in Example 2. After the same post-treatment, 114 g of resin was obtained. This resin has an Mn of 2600 measured by vapor pressure method and a softening point of 165°C by microscopy.
The Q value determined by GPC was 3.2. This resin was soluble in alcohols such as ethyl alcohol and butanol, tetrahydrofuran, dioxane, dimethylformamide, and acetone, but not in benzene, toluene, chloroform, and trichloroethylene. Experimental Example 1 Using each resin obtained in the above Examples and Comparative Examples, phenol novolac type epoxy resin (Ciel Chemical Co., Ltd. trade name Epicote 154), 2-ethyl-4-methylimidazole, and silica powder were added. , mixed in the proportions shown in Table 1, and heated to 100℃.
The mixture was melt-kneaded for 5 minutes using a hot roll, cooled, and then pulverized. Each of the obtained resin compositions was placed in a mold and cured using a hot press under molding conditions of 170°C and 50 kg/cm ² for 10 minutes, and after demolding, was further post-cured at 230°C for 6 hours. The physical properties of the obtained cured resin were as shown in Table 1.

【table】

[Table] Experimental Example 2 65g of novolac resin obtained in Example 2, phenol novolac type epoxy resin (Epicoat)
154, Ciel Chemical Co., Ltd. (trade name) 100g, BF _3,2 -methylimidazole 1g dissolved in 150g of acetone,
Made with varnish. This varnish was a homogeneously dissolved solution. Impregnate a glass cloth with a thickness of 0.18 mm with this varnish.
It was dried at 160°C for 7 minutes to obtain a B-state prepreg. 8 sheets of this prepreg were stacked, pressed under a pressure of 40Kg/ ^cm2 using a heat press at 180℃, and heated for 10 minutes.
A laminate with a thickness of 1.6 mm was obtained. The laminate was cured by heating at 180°C for 2 hours and then at 230°C for 4 hours. The bending strength of the obtained laminate is 55Kg/mm ² at 20℃,
It was 49Kg/mm ² at 150°C and 40Kg/mm ² at 200°C. Experimental Example 3 25 g of novolac resin obtained in Example 1, epoxidized o-cresol novolac resin (Ciel Chemical Co., Ltd. trade name: Epicote 181, epoxy equivalent: 220)
40g, brominated bisphenol A type epoxy resin (Ciel Chemical Co., Ltd. trade name Epicote 1050, epoxy equivalent 395, Br content 50%) 10g, 2-methylimidazole 0.5g, r-glycidoxypropyltrimethoxysilane 0.5g, Karuna Powerx 1g
and 150 g of silica were mixed and kneaded at 100° C. for 10 minutes using hot rolls, cooled, and then crushed to obtain an epoxy resin molding material. This molding material was subjected to transfer molding at a temperature of 170°C and a pressure of 80 kg/cm ² . 180 more molding resin
It was post-cured at 230°C for 2 hours and 4 hours at 230°C. The bending strength of the cured resin obtained was 14.0 Kg/mm ² . Experimental Example 4 63 g of novolac resin obtained in Example 1, 100 g of bisphenol A type epoxy resin (Ciel Chemical Co., Ltd. trade name Epicote 828, epoxy equivalent 190),
1 g of BF ₃ -2-methylimidazole and 20 g of carboxyl group-containing nitrilogom (product name: Hiker CTBN1300 x 8, manufactured by Ube Industries, Ltd.) were mixed, kneaded for 10 minutes with a hot roll at 100°C, and crushed after cooling to obtain an adhesive. . This adhesive powder was placed on a sandblasted mild steel plate, heated and melted at 140°C, and then another mild steel plate was stacked and bonded. Its shear adhesive strength is
It was 155Kg/cm ² at 20°C and 12Kg/cm ² at 150°C.

Claims (1)

[Scope of Claims] 1. Mixed cresol containing 92 to 45 mol% of p-cresol and 8 to 55 mol% of o-cresol and formaldehyde, an alkyl alcohol having 3 to 12 carbon atoms, an alkyl alcohol having 3 to 12 carbon atoms, A linear product with a softening point of 145°C or higher, characterized by reacting in the presence of an acidic catalyst in a polar solvent selected from the group consisting of glycol ethers of alcohols, benzyl alcohol, and alkyl carboxylic acids having 1 to 6 carbon atoms. Process for producing high molecular weight cresol novolak resin. 2. The method for producing a cresol novolac resin according to claim 1, wherein the mixed cresol is a mixture of 90 to 50 mol% of p-cresol and 10 to 50 mol% of o-cresol.