JP2930819B2 - Method for producing phenolic resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a novolak-type phenolic resin molding material having a small change in the appearance and dimensional change of the surface of a molded article in a humidifying treatment and having excellent filling properties in 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 of appearance (small blurring) and dimensional change (increase due to swelling) in a humid environment were large and were not suitable for applications in which the appearance and dimensional accuracy of molded products were important. For this reason, conventionally, it has been generally practiced to use a blended 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.

[0003] On the other hand, laminated board powder has been conventionally used mainly for the purpose of improving insulation resistance after humidification, and exhibits good properties in humidified appearance and dimensional stability. Otherwise, the filling properties during injection molding were not sufficient.
However, when wood flour is used, there is a drawback that small dust occurs during humidification. Furthermore, hexamethylenetetramine used as a curing agent has a large hygroscopic property, and if it remains unmelted during the kneading process when forming a molding material, it remains unmelted even in the molded product, and the appearance of the molded product in the humidification treatment It contributed to abnormalities (small burdock).

[0004]

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

[0005]

According to the present invention, a phenol resin and hexamethylenetetramine are simultaneously pulverized to a particle size of 0.2 mm or less, and this mixture is added as an organic filler to 100 parts by weight of the phenol resin. 10 to 60 parts by weight of a laminated board powder having a particle size of 0.2 mm or less obtained by pulverizing a laminated board based on vegetable fibers such as kraft paper, cotton paper and linter paper and having a resin content of 30 to 70% by weight. , and a method for producing a phenolic resin molding material, characterized in that the abrasive powder plywood was sieved to blend 10 to 60 parts by weight or less of powder particle size 0.2mm made. The phenolic resin referred to here is a novolak-type phenolic resin obtained by a reaction under an acid catalyst. In addition, as the laminated plate powder, one obtained by crushing offcuts, waste materials and cutting shoulders generated in the machining of the laminated plate, which are usually generated in the laminating plate manufacturing process from the laminating and cutting processes, is 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 resin varnish at a high temperature and a high pressure. Since it has low moisture absorption comparable to inorganic base materials such as fibers, the water resistance is remarkably improved when these laminate powders are used as a filler for a phenolic resin molding material. 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 deteriorated, which is not preferable.

On the other hand, in order to improve the filling property in injection molding, abrasive powder for plywood is used in combination. 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.
When particles of 2 mm or more are present, they cause small blurring during humidification. The mixing amount of the laminating powder and the plywood polishing powder was 10 to 10 parts by weight of the phenol resin, respectively.
The range of 60 parts by weight is suitable, and if it is outside this range, there are difficulties in molding workability, moisture resistance, dimensional stability and the like. 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.

In the present invention, in addition to the above components,
Alternatively , inorganic fillers such as calcium carbonate and clay can be used in combination. In addition, release agent, coloring agent, etc.
Novolak-type phenolic resin molding material
obtain. In the present invention, hexamethylenetetramine used as a curing agent and a phenol resin are simultaneously pulverized to a particle size of 0.1.
The main feature is that the particles are 2 mm or less. Heki
By pulverizing the samethylenetetramine together with the phenolic resin , the phenolic resin is mixed appropriately with the resin, so that secondary agglomeration can be avoided and troubles due to adhesion to the inner wall of the crusher can be prevented. At the stage before the pulverization, the phenol resin and the hexamethylenetetramine are not necessarily required to be uniformly mixed. For example, a method in which the phenol resin and the hexamethylenetetramine are simultaneously supplied to the pulverizer by a separate supply device may be used. If the particle size is larger than 0.2 mm, it remains unmelted even in the kneading step and the molding step after forming into a molding material, causing abnormal appearance (small blurring) in the humidification treatment. 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.

[0009]

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.

[0010]

[Table 1]

[0011]

[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 in the injection molding is such that a molded article having a bag-like projection having a width of 7 mm, a length of 17 mm and a depth of 15 mm is injection-molded using a Meiki Seisakusho MS-32 injection molding machine. evaluated.

[0013]

As apparent from the results shown in Table 2 according to the present invention, a phenolic resin molding material by the method of the present invention, off
Phenolic resin and hexamethylenetetramine with a particle size of 0.
It is pulverized to 2mm or less at the same time
It is manufactured by mixing layered powder and plywood polishing powder.
It 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-6-128456 (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 pulverized phenolic resin and hexamethylenetetramine simultaneously, and the particle diameter 0.2mm or less, the
Phenol resin 100 as an organic filler in the mixture
Laminate powder having a particle size of 0.2 mm or less, which is obtained by pulverizing a laminate having a resin content of 30 to 70% by weight based on vegetable fiber such as kraft paper, cotton paper, linter paper, etc. method for producing a phenolic resin molding material, characterized in that 10 to 60 parts by weight, and the abrasive powder plywood was sieved to blend 10 to 60 parts by weight or less of powder particle size 0.2mm made.