JPH0791441B2 - Phenolic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a resol-type phenol resin composition used as a molding material.

[Prior art]

Resole-type phenolic resins are widely used for electrical parts and other purposes because they do not generate ammonia during curing. Generally, a resol type phenol resin can be roughly classified into a methylol type and a dimethylene ether type depending on a functional group bonded to a phenol nucleus.

Methylol type phenolic resin has low activation energy for curing reaction, and the reaction proceeds even at relatively low temperature.
It has drawbacks such as producing a large amount of condensed water during curing, and when applied to a phenol resin molding material, it has poor thermal stability in the cylinder of the molding material, and easily causes mold clouding. There's a problem.

On the other hand, the dimethylene ether type phenolic resin is superior in heat stability and molding stability to the methylol type phenolic resin, but is inferior in curability.

For this reason, a method of promoting curing by using hexamethylenetetramine as a curing accelerator (Japanese Patent Publication No.
22069), but it has a drawback that generation of ammonia cannot be avoided.

[Problems to be Solved by the Invention]

The present inventor has eagerly studied to solve such a defect and obtain a dimethylene ether type resole resin molding material having excellent curability, and as a result, the curing is promoted by adding an organic peroxide. That is, the present invention has been completed.

[Means for Solving the Problems]

The present invention is a phenol resin composition comprising a resol-type phenol resin containing a large amount of dimethylene ether bonds and an organic peroxide as a curing accelerator.

The phenolic resin used in the present invention is a resol type phenolic resin in which the proportion of dimethylene ether bonds in bound formaldehyde is 35 mol% or more.

Such a phenol resin has a molar ratio of formaldehyde to phenol (F / P) of 1.0 to 3.0, and as a catalyst, (a) a salt of a Group 2 element or a transition element with an organic monocarboxylic acid such as formic acid or acetic acid, and (B) A compound obtained by reacting a salt of a Group 2 element or transition element with an inorganic acid such as boric acid, hydrochloric acid or nitric acid and then dehydrating it to a solid, usually having a number average molecular weight of 700 to 1400 and a melting point. 60 to 80 ° C.

If the proportion of dimethylene ether bonds is 35% or less, the proportion of methylol bonds becomes large and the thermal stability becomes poor, which is not preferable.

As the phenol resin, it is possible to replace 50% by weight or less of the above dimethylene ether type resole with a resol type phenol resin other than the above, and this case is also included in the present invention. However, the dimethylene ether type resole preferably has a proportion of simethylene ether bonds of 40% by weight or more.

The organic peroxide used in the present invention is dicumyl peroxide, t-butyl perpenzoate, t-butyl hydroperoxide and the like. The addition amount of these organic peroxides is not limited, but is preferably 0.2 to 2.0 parts by weight with respect to 100 parts by weight of the phenol resin. If it is less than 0.2 parts by weight, the effect is not sufficient, and if it exceeds 2.0 parts by weight, the effect tends not to increase so much.

Further, the present invention is preferably used in combination with a known curing aid. As such a curing aid, calcium hydroxide or magnesium hydroxide can be used. The blending amount is preferably 2 to 7 parts by weight with respect to the phenol resin. If the amount is 2 parts by weight or less, the effect is small, and if the amount is 7 parts by weight or more, curing is too fast to obtain a good cured product.

Further, fillers, pigments, lubricants and the like can be added as other additives. As the filler, wood powder, calcium carbonate, glass fiber, asbestos or the like can be used alone or in combination.

〔Example〕

Next, a method for producing a resin and a phenol resin composition according to the present invention will be described in Examples and Comparative Examples.

Production Example of Phenolic Resin 1 mol of phenol and 1.5 mol of paraformaldehyde are blended, and barium acetate and zinc nitrate as catalysts are present at 0.9 and 0.35% by weight with respect to phenol, respectively, and at 120 ° C for 4 hours.
After reacting while removing water for 1 hour,
I took it out for a while and took it out. The obtained phenol resin was a solid resol-type phenol resin having 43% of dimethylene ether group, and had a number average molecular weight of 750 and a melting point of 70 ° C.

Examples 1, 2 and 3 100 parts by weight of the above-mentioned resol resin, 60 parts by weight of wood flour, 25 parts by weight of calcium carbonate, 4 parts by weight of calcium hydroxide as a curing aid, 4 parts by weight of lubricant and pigment, and diquat as an organic peroxide. 0.2 parts of mill peroxide (Example 1), 1 part (Example 2) and 0.2 parts of t-butyl perbenzoate (Example 3) were blended, kneaded with a hot roll, cooled and pulverized to obtain a molding material. .

Comparative Example A phenol resin molding material was obtained in the same manner as in Example without adding an organic peroxide.

Using the molding materials obtained in Examples and Comparative Examples, a disc test piece having a diameter of 50 mm and a thickness of 3 mm was prepared at a mold temperature of 175 ° C. and a molding pressure of 80 kg / cm ² , and the curing degree was measured by a Barcol hardness tester ( No.935)
It was measured by. The results are shown in the table below.

[Effects of the Invention] As is clear from the above examples, since the phenol resin composition of the present invention contains an organic peroxide in a resol-type phenol resin having many dimethylene ether bonds, The curing speed can be sufficiently increased while making the most of the features of the resole resin.

Claims (1)

[Claims] 1. A phenol resin composition comprising a resol-type phenol resin having a dimethylene ether bond content of 35 mol% or more in all-bonded formaldehyde and an organic peroxide.