JPH0318653B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phenolic resin molding material and a method for producing the same, and more particularly to molded products such as cylinders, rolls, pipes and other irregularly shaped products, particularly molded products with mirror-like surfaces (surface roughness of 0.15 The present invention relates to a phenolic resin molding material suitable for use in precision molded products that require a high-precision surface with a diameter of 10 μm or less and 5 or less voids with a diameter of 10 μm or more existing per 10 cm square, and a method for producing the same. Phenol resin molding materials have superior mechanical strength when heated compared to thermoplastic resin molding materials, and also have superior mechanical strength, heat resistance, and physical performance compared to other thermosetting resin molding materials. Moreover, since it is relatively inexpensive, it is used for manufacturing various molded products such as cylinders, rolls, and pipes. Such phenolic resin molding materials use wood flour, pulp, asbestos, calcium carbonate, talc, mica, etc. as fillers, and a mixture of these fillers mixed with phenolic resin,
It is formed into pellets and used as a molding material. However, in extrusion molding of such phenolic resin molding materials, since pellet-shaped molding materials are used, voids are formed between the pellets, which causes poor fusion between the pellets during the extrusion process, resulting in voids between the pellets. There is a problem in that the molded product is extruded with a mirror-like surface remaining, making it impossible to produce a molded product with a mirror-like surface. Therefore, measures have been taken to reduce the melt viscosity of the molding material in order to solve the problem of poor fusion between the pellets, but this poses the problem of making extrusion molding difficult. The present invention was invented based on the above circumstances, and provides a phenolic resin molding material for extrusion molding that is suitably used for precision molded products having a mirror-like surface, which solves the conventional problems, and a method for producing the same. The purpose is to A feature of the present invention is that it is a phenolic resin molding material in which a coating layer of phenolic resin is provided on the surface of a pellet-like mixture formed by mixing a phenolic resin with a filler. After applying a solution prepared by dissolving the resin onto the surface of the pellet-like mixture, the solvent is removed. The present invention will be explained in detail below. The pellet-like mixture in the present invention is obtained by pelletizing a sheet-like mixture obtained by kneading a phenolic resin with a filler (this is done using a roll, kneader, Banbury mixer, etc.) using a Henshil mixer or the like. The phenolic resin is a mixture of phenols such as phenol, cresol, and xylene, or phenols modified with molasses, lignin, naphthalene, and petroleum aromatic hydrocarbons, and aldehydes such as formalin and paraformaldehyde in a predetermined molar ratio. , a novolak-type phenolic resin initial condensate that is reacted under an acidic catalyst such as hydrochloric acid, sulfuric acid, or oxalic acid, and then dehydrated and boiled down to form a solid, or
A resol-type phenolic resin initial condensate is used, which is made into a solid by reacting under an alkaline catalyst such as sodium hydroxide, ammonia, or amine, and then dehydrated under reduced pressure.In the case of a novolak-type phenolic resin initial condensate, a curing agent Hexamethylenetetramine is used in combination. The blending ratio of hexamethylenetetramine is preferably 10 to 25 parts per 100 parts by weight (hereinafter referred to as parts) of the novolak type phenolic resin initial condensate. If the lower limit of this range is outside this range, the curing reaction will not be sufficient and properties such as strength will be inferior, and if it is outside of the upper limit, ammonia will be generated more during molding, causing blistering on the surface of the molded product and metal corrosion on the molded product. It becomes easier. Fillers include base materials (wood flour, pulp, asbestos, etc.), fillers (silica, talc, diatomaceous earth, etc.), plasticizers (furfural, styrene, etc.), hardening accelerators, lubricants (stearic acid, zinc stearate, etc.) , polyethylene wax, carbana wax, amide compounds of fatty acids such as ricinoleic acid, oxystearic acid, oleic acid, and lauric acid (preferably fine powders of 1μ or less), coloring agents, etc. are used as appropriate, but usually phenol is used. resin
100 parts, base material 30-150 parts, filler 2-30 parts
part, 0.5 to 2 parts of plasticizer, 1 to 10 parts of lubricant, and an appropriate amount of colorant. In addition, the phenolic resin coating layer is made of a solvent that dissolves the phenolic resin, for example, a solution in which the phenolic resin is dissolved in an alcohol such as methanol or ethanol, for example, the phenolic resin concentration is 0.2 to 1.0.
It is obtained by coating the surface of the pellet-like mixture with a solution of Kg/kg and then removing the solvent. If the concentration of the phenolic resin solution deviates from the above range at the lower limit, the thickness of the coating layer becomes thinner and the effect of eliminating poor fusion between the pellets is small; when it deviates from the upper limit, the thickness of the coating layer increases and the melting of the pellets becomes difficult. The viscosity decreases and extrusion moldability deteriorates. Further, the method for removing the solvent may be carried out under normal pressure or vacuum, but from the viewpoint of efficiency it is preferably carried out under vacuum. At this time, the temperature is preferably 80° C. or lower in order to prevent the curing reaction of the phenol resin from starting. When extrusion molding is performed using the phenolic resin molding material of the present invention, 0.5 of the above-mentioned lubricant is added to 100 parts of the pellet-shaped molding material in advance in order to prevent adhesion between the phenolic resin coating layer and the cylinder of the extruder. It can be used by sprinkling ~5 parts. Next, the present invention will be explained based on Examples together with Comparative Examples. A filler was mixed with the phenolic resin according to the formulation shown in Table 1 (roll kneading, kneading temperature 100°C) to prepare a sheet-like mixture, which was then passed through a Henshil mixer to form a pellet-like mixture. Using this pelleted mixture, a phenolic resin coating layer was formed on the surface of the pelleted mixture under the conditions shown in Table 1 to produce a phenolic resin molding material. Next, using this phenolic resin molding material, extrusion molding was performed to create a mold with an inner diameter of 25 mmφ, an outer diameter of 30 mmφ, and a length of 150 mm.
A pipe molded product of mm in diameter was obtained, and the surface characteristics and other properties of this molded product were investigated. As a result, according to the present invention, it has become possible to manufacture a precision molded product with excellent extrusion moldability and a mirror-like surface. 【table】

Claims (1)

[Scope of Claims] 1. A phenolic resin molding material, characterized in that a coating layer of phenolic resin is provided on the surface of a pellet-like mixture formed by mixing a phenolic resin with a filler. 2. A method for producing a phenolic resin molding material, which comprises applying a phenolic resin solution to the surface of a pellet-like mixture formed by mixing a filler with a phenolic resin, and then removing the solvent.