JPS6034567B2 - Manufacturing method of phenolic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a method for producing a phenol resin, and its object is to obtain a phenol resin that contains less reaction phenol and has less mold shrinkage.

Conventionally, phenolic resins used as molding materials are obtained by synthesizing oxalic acid or hydrochloric acid using phenols and formaldehyde as acid catalysts at a molar ratio of 0.5 to 1.0. It usually contains 5-10% unreacted phenol.

When the obtained phenolic resin is used as a molding material and molded, there is a drawback that molding shrinkage is large.

Furthermore, after molding, there is a large amount of shrinkage over time. This seems to be because unreacted phenol remaining in the molded article volatilizes over time. In addition, phenol volatilizes during the production and molding of molding materials and generates a toxic odor, so phenol with less unreacted content has been desired from the viewpoint of the working environment. In recent years, in order to solve this problem, methods for synthesizing resins with less unreacted phenol using methods such as thin film drying have been devised, but this may lead to an increase in the cost of the resin because it is difficult to recover the volatilized phenol. . The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a method for producing a phenolic resin with less unreacted phenol and less molding shrinkage.

However, in the present invention, when a phenol resin is synthesized by reacting phenols with formaldehyde,
The method is characterized in that the resin is synthesized by adding at least 0.01 mole or more of phosphoric acids per mole of phenol as a catalyst, and then neutralizing by adding boric acid to 1.3 volume moles of the phosphoric acids. The present invention will be explained in detail below. The present invention is a method for producing a novolac type phenolic resin by synthesizing phenols and formaldehyde using a catalyst.

The phenols mentioned here include phenol, cresol, nonylphenol, chlorphenol, and the like. Formaldehyde refers to 37% formaldehyde, 50% formaldehyde, parformaldehyde, etc. This phenol and formaldehyde are mixed in a proportion of 0.5 to 1.
In this method, a phenolic resin is obtained by blending the resins in a molar ratio of 0 and carrying out a condensation reaction using phosphoric acids as a catalyst. Phosphoric acids are produced by hydrating diphosphorus pentoxide. orthophosphoric acid,
Metaphosphoric acid, phosphorous acid, hypophosphorous acid, etc. are used, and it is preferable to use them in an amount of at least 0.01 mol or more per 1 mol of phenols. This is because when phosphoric acids are low, a relatively large amount of unreacted phenol remains.
The most preferred range is 0.01 to 0.05 mol.
This is because even if the amount of phosphoric acids exceeds 0.05 mol, the amount of unreacted phenol remains at a certain level, making it difficult to obtain further effects. When these phosphoric acids are used alone, less unreacted components can be obtained, but other acid catalysts such as oxalic acid or hydrochloric acid may be used in combination. In addition, the same effect can be obtained even if the reaction is carried out by increasing the O/P ratio of the phenol resin by using divalent or trivalent metal salts (such as zinc acetate or manganese borate) in combination with phosphoric acids and slowing down the reaction rate. A product containing less unreacted phenol can be obtained. The phenolic resin synthesized in this way is heated to 30°C at a temperature of 120°C or higher during dehydration.
Boric acid or metaboric acid is added in a molar amount 1.5 times the amount of phosphoric acids while heating for at least 1 minute to neutralize the remaining phosphoric acids.

When an alkali is used to neutralize phosphoric acids, it is unsuitable because salts precipitate after neutralization. As described above, in the case of synthesizing a phenol resin by reacting phenols with formaldehyde, the present invention adds at least 0.01 mole or more of phosphoric acid as a catalyst to 1 mole of phenol to synthesize the resin. After synthesis, boric acid is converted into one of the phosphoric acids.
．． Since the phenol resin obtained has a small amount of unreacted phenol, it is difficult to cause caking during storage. Since the amount is small, waste liquid treatment is easy, and it has the advantage of high resin yield. Even when using this resin, the molding material obtained has small mold shrinkage and dimensional change over time, and has low thermal strength. You can get something excellent.

Examples of the present invention are shown below.

Examples 1 to 6 Mix the ingredients in Table 1, react at reflux temperature for 3 hours, add boric acid in an amount 1.5 times the mole of phosphoric acids, boil down to 120 oo, and heat for 30 minutes or more. A phenol resin was obtained by a sum reaction.

Comparative Example A phenol resin was obtained by reacting at reflux temperature for 3 hours using the formulation shown in Table 1 in the same manner as in the example.

Table 1 The physical properties of the phenolic resins obtained in each Example and Comparative Example were measured and the results are shown in Table 2.

Here, unreacted phenol was removed by the bromination method, the number average molecular weight was calculated by GPC, the resin viscosity was measured at 16,000 using a B-type viscometer, and the resin pH was determined by dissolving 5 parts of the resin in 10 parts of methanol, then water. Add 45 yen and add top solution.
It was measured with an H meter, and the softening point was measured by the ring and ball method. Table 2

Claims (1)

[Claims] 1. When synthesizing phenolic resin by reacting phenols and formaldehyde, use at least 0.01 phosphoric acid as a catalyst per mole of phenols.
A method for producing a phenolic resin, which comprises adding boric acid in an amount 1.5 times the amount of phosphoric acid to neutralize the resin after synthesizing the resin.