JPH0569127B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a novel method for producing a polyhydroxy compound, and more particularly, to a method for producing a novel and useful polyhydroxy compound having a narrow molecular weight distribution width. Conventional technology Traditionally, amines, acid anhydrides, phenol novolac resins, etc. have been used as curing agents for epoxy resins, but in recent years, high quality products have been used for applications such as laminates and sealants. Due to demands for improved performance and lower prices, phenolic novolac resins were reconsidered.
This resin is particularly suitable for use in electrical and electronic materials. Therefore, the phenol novolac resin is generally obtained by condensation reaction of phenols and formaldehyde in the presence of an acid catalyst, and is a linear chain mainly composed of 2 to 20 phenol nuclei linked by methylene bonds. It is thought to be a molecule. As the above-mentioned raw material phenols, carbolic acid, orthocresol, etc., which usually have one phenolic hydroxyl group, are used, and the resulting resin contains a low molecular weight component consisting of an unreacted phenol monomer and a dinuclear body. . For these reasons, when this resin is used as a curing agent, it is difficult to provide a cured product with a high crosslink density, and the resulting cured product is not satisfactory in terms of heat resistance, chemical resistance, mechanical properties, etc. The disadvantage is that it cannot be done. In addition, conventionally, (1) monohydric phenols such as carbolic acid and orthocresol, (2) para-substituted phenols such as para-substituted alkyl phenols and para-substituted aryl phenols, and (3) formaldehyde are simultaneously charged and the phenol is subjected to a condensation reaction. -Para-substituted phenolic co-condensed novolak resins are also known,
Similar to the general phenol novolac resins mentioned above, this resin also contains low molecular weight components that are thought to act as reaction terminators for epoxy groups, such as dinuclear bodies of carbolic acid and para-substituted phenol monomers, and can be used as desired. cannot exhibit the hardening characteristics of Moreover, the co-condensed novolak resin generally has a wide molecular weight distribution, and even when the content of the carbolic acid monomer is adjusted to 1% by weight or less by operations such as distillation, Mw/Mn
(Mw indicates the weight average molecular weight value and Mn indicates the number average molecular weight value), but it shows a high value of 1.5 or more, and is disadvantageous as a curing agent in terms of handling and workability due to its melt viscosity. Problems to be Solved by the Invention In view of the above-mentioned prior art, the present invention is directed to a new polyfunctional phenolic resin having excellent properties, especially as a curing agent for epoxy resins, and more specifically, to a new polyfunctional phenolic resin that has significantly reduced content of low molecular weight condensates. It is an object of the present invention to provide a method for producing a polyfunctional phenolic resin having a reduced molecular weight distribution and a narrow molecular weight distribution width. Means for solving the problem The above purpose is to solve the problem by
- A dimethylol derivative of a para-substituted phenol selected from alkylphenol and 2,6-dihydroxymethyl-4-arylphenol is reacted with phenols by heating in the presence of an acid catalyst, and then dehydrated and dephenolated to form a dinuclear product. The content of the following components is 5% by weight or less, preferably 2.5% by weight.
This is achieved by a method for producing a polyhydroxy compound, which is characterized by obtaining a polyhydroxy compound in which the trinuclear component content is 30% by weight or more, preferably 40% by weight or more. As a result of intensive research, the present inventors have found that, as mentioned above, a dimethylol derivative of a para-substituted phenol selected from 2,6-dihydroxymethyl-4-alkylphenol and 2,6-dihydroxymethyl-4-arylphenol is used as a starting material. use,
It was discovered that when this is reacted with an excess amount of phenols in the presence of an acid catalyst, the target compound can be obtained by subsequent dehydration and removal of phenols by ordinary distillation operations, etc., and the present invention has now been completed. did. The polyhydroxy compound obtained by the present invention contains almost no low molecular weight components that act as a reaction terminator for epoxy groups, and has a narrow molecular weight distribution, so it is very suitable as a curing agent for epoxy resins. It exhibits excellent curing properties and has a high crosslinking density.
It has the characteristics of providing a cured product with excellent heat resistance, chemical resistance, mechanical properties, etc. In the present invention, the dimethylol derivative of para-substituted phenol used as a starting material is typically, for example, 2,6-dihydroxymethyl-4-methylphenol, 2,6-dihydroxymethyl-4-ethylphenol, 2,6-dihydroxymethyl-4-ethylphenol, -dihydroxymethyl-4-n-probylphenol,
2,6-dihydroxymethyl-4-isopropylphenol, 2,6-dihydroxymethyl-4-
t-Butylphenol, 2,6-dihydroxymethyl-4-amylphenol, 2,6-dihydroxymethyl-4-octylphenol, 2,6-
Examples include dihydroxymethyl-4-phenylphenol. These para-substituted phenol dimethylol derivatives can be produced according to conventional methods. For example, 2,6-dihydroxymethyl-4-alkylphenol is produced as a high-purity solid by reacting the corresponding para-substituted alkylphenol with formaldehyde in the presence of water and a basic catalyst, followed by acid precipitation. You can earn it. Further, in the present invention, as the 2,6-dihydroxymethyl-4-alkylphenol, a resol-type oil obtained by neutralizing the reaction product of the para-substituted alkylphenol and formaldehyde with an acid is used. It can also be used without purification. 2,6-dihydroxymethyl-4-arylphenols can also be produced in the same manner as above. In addition to carbolic acid, the other raw material phenols in the present invention include, for example, cresol,
Examples include para- or ortho-substituted alkylphenols such as xylenol, halogenated phenols such as chlorophenol, and bromophenol. Among these, carbolic acid and cresol are preferred in consideration of reactivity. In the method of the present invention, first, the dimethylol derivative of the para-substituted phenol and the phenols are heated and reacted in the presence of an acid catalyst. The acid catalyst used here is not particularly limited, and any of the various types commonly used in the production of novolac resins can be used. Among these, oxalic acid is particularly suitable. The amount of phenols used in the para-substituted phenol dimethylol derivative is preferably in excess of the methylol group of the derivative, usually about 1.2 to 10 times the molar amount, preferably about 1.5 to 3.0 times the molar amount. This amount corresponds to a range of about 2.4 to 20 times the molar amount of the above derivative itself. If the amount of the phenol used is much less than 1.2 times the mole of the methylol group, the softening point and melt viscosity of the obtained target product will be undesirably high. The above reaction conditions are appropriately determined taking into account the amount of unreacted phenol, the amount of low-molecular condensation products, the amount of high-molecular condensation products, etc. from the reaction, but usually about 50 to 100
℃, preferably about 60-80℃, and it is preferable to heat at the above temperature for about 3-6 hours. In the present invention, dehydration and dephenolization are then performed. This can be carried out specifically according to conventional distillation operations. This distillation method is not particularly limited;
Any of various known methods such as vacuum distillation, thin film distillation, steam distillation, etc. may be used. However, this distillation operation hardly removes condensates of two or more nuclear bodies. In the present invention, as described above, by using an excess of phenols with respect to the dimethylol derivative of the para-substituted phenol, the condensation reaction between the methylol groups of the derivative is suppressed, and the formation of condensates of dinuclear or more is minimized. This is to suppress it. Thus, according to the present invention, the content of binuclear components or less is 5% by weight or less, and the content of trinuclear components is 30% by weight or more (usually in the range of 30 to 80% by weight), A desired polyhydroxy compound with a narrow molecular weight distribution can be obtained. The polyhydroxy compound obtained by the method of the present invention is estimated to be a phenol novolac resin mainly composed of trinuclear bodies in terms of phenol nuclei represented by the following general formula (1).

[In the formula, R ¹ represents an alkyl group or an aryl group, R ² represents a hydrogen atom or an alkyl group, and R ³ represents a hydrogen atom, an alkyl group, or a halogen atom. ]

The polyhydroxy compound obtained by the method of the present invention is very useful as a curing agent for epoxy resins. When used as a curing agent, the polyhydroxy compound of the present invention is blended with various epoxy resins and, if necessary, a curing accelerator and other additives to form an epoxy resin composition, which can be used, for example, to seal electronic parts. It can be suitably used for materials, laminates, powder coatings, etc. Furthermore, the polyhydroxy compound can also be used as a polyol component for polyurethane or as a raw material for epoxy resin. Examples Examples and comparative examples of the method of the present invention are listed below.
The present invention will be explained in more detail, but the present invention is not limited to these examples. In each example, all parts and percentages are based on weight unless otherwise specified. Example 1 After purging the inside of a 1-volume flask equipped with a stirrer, thermometer, and condenser with nitrogen gas, 210 parts (1 mol) of 1,6-dihydroxymethyl-4-t-butylphenol and 282 parts (3 mol) of carbolic acid were added. mole) and oxalic acid
Add 1.4 parts and react at 70°C for 4 hours under a nitrogen stream, then dehydrate under reduced pressure and remove phenol by steam distillation to reduce the phenol monomer content.
The polyhydroxy compound of the present invention was obtained by adjusting the content to 1.0% or less. This is called "compound A." Example 2 A polyhydroxy compound having a phenol monomer content of 1.0% or less was obtained in the same manner as in Example 1, except that the amount of carbolic acid used was changed to 470 parts (5 moles). This is called "compound B." Comparative Example 1 In a 1-volume flask equipped with a stirrer, a thermometer, and a condenser, the atmosphere was replaced with nitrogen gas, and then 188 parts (2 moles) of carbolic acid, 122 parts (1.5 moles) of 37% formalin, and 0.7 parts of oxalic acid were placed. , reacted at reflux temperature in a nitrogen stream for 3 hours, then dehydrated under reduced pressure, removed phenol by steam distillation, and adjusted the phenol monomer content to 1.0% or less,
A polyhydroxy compound was obtained. This is called "comparative compound C." The results of determining the properties of each polyhydroxy compound obtained in the above Examples and Comparative Examples are shown in Table 1 and Table 1.
It is shown in Figs. In Table 1, the content of each component and Mw/Mn are as follows:
It was measured using columns (G-4000H8 and G-2000H8), and the softening point was determined by the ring and ball method.

[Table] In addition, Figures 1 to 3 show the high performance liquid chromatography measuring device (manufactured by Toyo Soda Co., Ltd., HLC-802A,
This is a graph showing the molecular weight distribution measured using CP-8000), in which the horizontal axis represents the elution count number,
The vertical axis shows the peak intensity. As is clear from the comparison of each figure, the polyhydroxy compound obtained by the method of the present invention (Figures 1 and 2) is more
It can be seen that the molecular weight distribution width is narrow and that the main component is trinuclear bodies.

[Brief explanation of drawings]

1 to 3 are graphs showing the molecular weight distributions of the polyhydroxy compounds obtained in Examples 1 and 2 of the present invention and the polyhydroxy compound obtained in Comparative Example 1.

Claims (1)

[Claims] 1 2,6-dihydroxymethyl-4-alkylphenol and 2,6-dihydroxymethyl-4
- A dimethylol derivative of para-substituted phenol selected from aryl phenols and phenols are reacted by heating in the presence of an acid catalyst, and then dehydrated and dephenolated to reduce the content of dinuclear or lower components to 5% by weight or less. Yes, and the content of trinuclear components is 30
1. A method for producing a polyhydroxy compound, characterized by obtaining a polyhydroxy compound having a content of % by weight or more. 2. The method according to claim 1, wherein the charging ratio of the phenols to the dimethylol derivative of the para-substituted phenol is 2.4 to 20 times by mole.