JP2930818B2 - Phenolic resin molding materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenolic resin molding material having a small change in appearance and dimensional change on the surface of a molded article in a humidifying treatment and having excellent filling properties during injection molding.

[0002]

2. Description of the Related Art A phenolic resin molding material is obtained by blending a phenolic resin, a curing agent, a coloring agent, a release agent and other additives with a plant base such as wood flour and pulp and an inorganic base as a filler. After mixing these, the mixture is kneaded into a lump or a sheet by a kneading device such as a hot roll, and after cooling, pulverized to a particle size according to the purpose of molding to form a molding material. Such a phenolic resin molding material has been widely used for a wide range of applications since ancient times.However, as a fate of the phenolic resin, a high temperature is caused by the influence of a hygroscopic substrate such as condensed water and wood powder generated during the curing reaction. Deterioration in appearance (small blurring) and dimensional change (increase due to swelling) in a humid environment were large, and were unsuitable for applications where the appearance and dimensional accuracy of molded products were important.

[0003] For this reason, conventionally, it has been generally practiced to use a compounding composition containing only an inorganic base material as a filler. Such a molding material has difficulty in moldability such as thermal stability and filling property, and its cost is high, so its use is limited and is not common. On the other hand, laminated board powder has been used mainly for the purpose of improving insulation resistance after humidification, and exhibits good properties in humidified appearance and dimensional stability. The filling property at the time was not enough. However, when wood flour is used, there is a drawback that small dust occurs during humidification.

[0003]

The present invention has been made as a result of various studies in order to solve such problems of the conventional phenolic resin molding material. An object of the present invention is to provide a phenolic resin molding material having a small change in appearance and dimensional change on the surface of a molded product and having excellent filling properties during injection molding.

[0004]

According to the present invention, there is provided a laminate comprising a vegetable fiber such as kraft paper, cotton paper and linter paper as a base material and a resin content of 30 to 70% by weight based on 100 parts by weight of a phenol resin. 10 to 60 parts by weight of a powder having a particle size of 0.2 mm or less obtained by pulverizing a board, and 10 to 60 parts by weight of a powder having a particle size of 0.2 mm or less obtained by sieving abrasive powder of plywood. Characteristic phenolic resin molding material. The phenolic resin as used herein refers to a resol-type phenolic resin obtained by reacting with a novolak-type phenolic resin obtained under a reaction with an acid catalyst and an alkali catalyst.
In addition, as the laminated board powder, one obtained by crushing offcuts, waste materials generated from laminating and cutting steps of a fixed-size plate in a manufacturing process of the laminated plate and a shoulder generated in machining of the laminated plate is usually used. These laminates are obtained by reacting a laminated material composed of a vegetable fiber base material such as kraft paper, cotton cloth, and linter paper impregnated with a resin varnish at a high temperature and a high pressure, such as calcium carbonate and glass fiber. Since these laminate powders are used as fillers for phenolic resin molding materials, they have significantly improved water resistance because they have low moisture absorption comparable to inorganic base materials. The optimum particle size of these laminate powders is 0.2 mm or less. For powdered raw materials with a particle size of 0.2 mm or more,
The miscibility with the phenol resin is poor, and the electric performance may be lowered, which is not preferable. On the other hand, abrasive powder for plywood is used together to improve the filling property in injection molding. Abrasive powder for plywood is more oil-absorbing than the above-mentioned laminated board powder. The same effect can be obtained by using wood flour in combination, but wood flour is mainly generated during processing such as cutting and grinding of wood, or obtained by sifting pulverized materials. In general, when the grain size is generally coarse and the upper limit of the coarse grain is removed by sieving with the same mesh, the plywood abrasive powder can obtain a finer grain size. This makes it easier and more economical than wood flour to be a raw material with an excellent appearance when humidified. The particle size of the abrasive powder of the plywood is desirably 0.2 mm or less as in the case of the raw material of the laminated board powder. If particles having a particle size of 0.2 mm or more are present, they may cause small blurring during humidification. The mixing amount of the laminating powder and the plywood polishing powder is preferably in the range of 10 to 60 parts by weight with respect to 100 parts by weight of the phenolic resin. Outside this range, the formability, moisture resistance, dimensional stability, etc. There is a drawback in the point. That is, if it is less than 10% by weight, the moisture resistance and dimensional stability become insufficient, and if it is more than 60% by weight, there is a problem in moldability. It is also possible to use inorganic fillers such as calcium carbonate and clay in these formulations, and to mix a curing agent, a release agent and a colorant, and knead them in a conventional manner to obtain a phenolic resin molding material. . The phenolic resin molding material obtained in this manner has a small change in appearance and dimensional change of the surface of the molded product due to the humidification treatment, and has excellent filling properties during injection molding.

[0005]

EXAMPLE A molding material was prepared according to the formulation shown in Table 1 by a usual method for producing a phenolic resin molding material. The properties of the obtained molding material were measured, and the results shown in Table 2 were obtained.

[0006]

[Table 1]

[0007]

[Table 2]

The water absorption and the molding shrinkage are measured according to JIS K
6911. As the test pieces for the dimensional change and the appearance change, test pieces having a molding shrinkage were used. The filling property at the time of injection molding is as follows: A molded product having a width of 7 mm, a length of 17 mm, and a depth of 15 mm and having a projection as a dead end is manufactured by Meiki Seisakusho MS-32.
Injection molding was performed using an injection molding machine, and evaluation was made based on the filling properties of the projections.

[0010]

As is evident from the results shown in Table 2, the phenolic resin molding material of the present invention, in which the fine particle powder and the plywood polishing powder are blended, has excellent moisture resistance (appearance and dimensional change). ) And filling properties during injection molding.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-128455 (JP, A) JP-A-61-152761 (JP, A) JP-A-59-105049 (JP, A) JP-A 55-128 106257 (JP, A) JP-A-55-42868 (JP, A) JP-A-57-8020 (JP, A) JP-A-57-78444 (JP, A) JP-A-6-49323 (JP, A) JP-A-6-93170 (JP, A) JP-A-6-80952 (JP, A) JP-A-6-41318 (JP, A) JP-A-5-212831 (JP, A) JP-A-63-146957 (JP, A) JP-A-62-295945 (JP, A) JP-A-1-268750 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 1/00-101 / 14 C08K 3/00-13/08

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein 100 parts by weight of the phenol resin is
10 to 60 parts by weight of a powder having a particle size of 0.2 mm or less obtained by pulverizing a laminate having a resin content of 30 to 70% by weight based on vegetable fibers such as kraft paper, cotton paper, linter paper, and A phenolic resin molding material comprising 10 to 60 parts by weight of a powder having a particle size of 0.2 mm or less obtained by sieving abrasive powder of plywood.