JPS5817529B2 - Manufacturing method of novolak resin - Google Patents

Description

[Detailed description of the invention] This invention relates to a method for producing novolac resins.

Conventionally, phenolic resin molding materials are generally produced by reacting phenol and formaldehyde in the presence of an acidic catalyst.
The novolac resin obtained by further dehydration under reduced pressure, a curing agent such as hexamethylenetetramine, a filler, and the like were heated, kneaded, and pulverized.

However, the above-mentioned conventional molding materials had the following drawbacks.

In other words, most of the unreacted phenol that remains in the novolak resin (more than 7%) is distilled out during the vacuum dehydration process, which is wasteful from the perspective of resource conservation and requires treatment. Phenol remaining in the molding material transfers into the molded product without leaving the molding material, so when the molded product is exposed to high temperatures, it evaporates, impairing the appearance and performance of the molded product, reducing the heat resistance of the molded product, and further reducing the phenol content. Since it is hydrophilic, it also has the disadvantage of reducing the electrical insulation properties of the molded product.

Although this invention was devised primarily to solve these problems, the novolak resin obtained by implementing this invention can also be used for purposes other than the production of molding materials.

This invention aims to achieve the above object by using phenol in the form of a di-adduct of isomerized α-pinene represented by [I] below, which is a diphenol adduct of isomerized α-pinene. The gist is a method for producing a novolak resin, which is characterized by reacting formaldehyde with formaldehyde in the presence of an acidic catalyst.

The diphenol adduct of isomerized α-pinene is stable even at high temperatures, so when this adduct with α-pinene is used as a phenol source to be reacted with formaldehyde, it remains in the resin as an unreacted product. The diphenol adduct of isomerized α-pinene that remains in the resin does not distill out during the vacuum dehydration process, so there is no need to treat it. be incorporated into the system and used effectively.

Moreover, the diphenol ft1JDe of isomerized α-pinene
Since l is more hydrophobic than phenol, it does not reduce the electrical insulation properties of the molded product.

The diphenol adduct cI of isomerized α-pinene is synthesized, for example, as follows, and is available under the trade name “Silver 7” manufactured by Yasushi Oil Industries Co., Ltd.

The diphenol adduct of isomerized α-pinene may be used in a mixed form with the following compounds CM), [1II).

Formaldehyde sources such as formalin and paraform are used.

Although formaldehyde is not particularly limited to this, it is usually 10 to 1.8 mol, preferably 1.2 mol, per mol of the diphenol adduct of isomerized α-pinene.
It is used in a proportion of 71.6 moles.

As acidic catalysts, those commonly used for producing novolac resins, such as oxalic acid and hydrochloric acid, are also used in this invention.

In this case as well, it is not meant to be limited to this. For example, when oxalic acid is used, the amount of this acid is 0.002 to 1 mol per mol of the diphenol adduct of isomerized α-pinene. 0004 mol.

The method of making novolac resin using these raw materials is as follows.
As is known.

Since the present invention is configured as described above, when the novolak resin obtained by carrying out the present invention is used, for example, in the production of a molding material, a molded article with good heat resistance and high electrical insulation can be produced.

Next, an embodiment will be described together with a conventional example.

In a fourth flask, add the phenol components listed in Table 1 and 5
Take 5% formalin and oxalic acid dihydrate in the amounts listed in the same table, add a stirrer, a thermometer, and a reflux condenser, stir under heat, and bring the contents to a boil over about 30 minutes. After that, stirring was continued for 35 hours under boiling conditions, the cooler was replaced and dehydration was performed under reduced pressure for 60 minutes, and then the temperature was increased to 160°C.
The mixture was heated to a temperature of 100.degree. C. and stirred under pressure for about 30 minutes to obtain a novolac tree.

Using this resin, raw materials blended at the mixing ratios shown in Table 1 were kneaded using heated rolls according to a conventional method, and then ground to obtain a molding material.

Using the three types of molding materials obtained above, molded products were obtained by direct pressure molding according to a conventional method.

The performance of each molded product is shown in Table 2, and it can be seen that the heat resistance and electrical insulation properties of the molded products of the examples are superior to those of the conventional examples.

Claims (1)

[Scope of Claims] 1. A method for producing a novolak resin, which comprises reacting a diphenol adduct of isomerized α-pinene with formaldehyde in the presence of an acidic catalyst. 2. The method for producing a novolak resin according to claim 1, wherein formaldehyde is used in a ratio of 1.0 to 1.8 mol per mol of the diphenol adduct of isomerized α-pinene. 3. The method for producing a novolak resin according to claim 1, wherein oxalic acid is used as the acidic catalyst in a ratio of 0.002 to 0.004 mol per mol of the diphenol adduct of isomerized α-pinene.