JP2001002888A - Production of phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material which shows little variation of weight of an injection-molded item, excellent dimensions of the injection-molded item, fatigue resistance and abrasion resistance by kneading a phenolic resin (A), a glass fiber (B) and crushed woven cotton (C), cooling and crushing the mixture followed by mixing a carnauba wax (D) with the mixture. SOLUTION: The component A is a material used for molding a conventional phenolic resin and a novolak type and a resol type are each available. The number average molecular weight of the component A is preferably 600 to 1,500. The component B has a fiber diameter of not more than 15 μm and a fiber length of 0.1 to 3 mm and the compounding amount thereof is preferably 5 to 15 wt.% of the whole molded item. The component C preferably has a fiber length of 0.2 to 3.0 mm and the compounding amount thereof is preferably 3 to 10 wt.% of the whole molded item. The adding amount of the component D is preferably 0.1 to 1.0 pt.wt. to 100 pts.wt. of the sum of the materials other than the component D. The apparent viscosity of the molding material decreases by mixing the component D.

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 phenolic resin molding material having a small variation in weight of a molded article in injection molding and having excellent dimensional accuracy, fatigue strength and abrasion resistance of the molded article.

[0002]

2. Description of the Related Art Phenolic resin molding materials have an excellent balance of heat resistance, electrical properties, mechanical properties, dimensional stability, etc.
It is used in a wide range of fields, including mechanical parts for automobiles. A mechanical component of an automobile is required to have a fatigue strength because a load is repeatedly applied to the component, and a resin component and a metal component are required to have dimensional performance and wear resistance due to sliding. For this reason, a wood flour-based phenolic resin molding material containing a crushed cotton fabric material having relatively high strength and excellent wear resistance has been used for such applications. However, the fatigue strength required for recent mechanical parts has become higher and more severe, and the conventional wood-powder-based phenolic resin molding material containing a crushed cotton fabric has insufficient fatigue strength. In order to solve these problems, a glass-based phenolic resin molding material is used. However, although the fatigue strength is improved, the abrasion resistance characteristics are deteriorated, and it is difficult to put to practical use.

[0003] Further, general wood flour-based phenolic resin molding materials have a relatively high viscosity even in a plasticized state in a cylinder, and are injected into a mold under high pressure, so that cushion molding is not performed. For this reason, when the measured value has a large variation and an excessive weight is injected, the molded product has a large residual stress, and the molded product is warped in the cooling process after being taken out of the mold and burrs are increased. In addition, when the injection weight is small, the molded product may be blurred and a good product may not be obtained. Conventionally, in order to solve these problems, cushion molding may be performed by lowering the melt viscosity of the molding material, that is, increasing the fluidity and lowering the injection pressure. In this case, although the generation of burrs can be reduced, the molding cycle becomes longer, and depending on the shape of the molded product, the orientation of the fibers occurs inside the molded product due to the low viscosity, and the anisotropy occurs in the molded product, and the dimensional accuracy decreases. It is difficult to put it to practical use.

[0004]

The present invention has been made as a result of various studies to solve these problems, and it is an object of the present invention to reduce the rate of change in the weight of a molded article by injection molding and to reduce the molding rate. It is an object of the present invention to provide a method for producing a phenolic resin molding material having excellent product dimensions, fatigue strength and wear resistance.

[0005]

According to the present invention, (a) a phenolic resin, (b) glass fiber and (c) a crushed cotton fabric are melt-kneaded, cooled, pulverized, and then mixed with (d) carnauba wax. The present invention relates to a method for producing a phenolic resin molding material, characterized in that
An object of the present invention is to provide a method for producing a phenolic resin molding material having excellent fatigue strength and wear resistance.

In the present invention, the phenolic resin (a) may be any one used in ordinary phenolic resin molding materials, and can be used in both novolak type and resol type. When a novolak-type phenol resin is used, hexamethylenetetramine is usually used as a curing agent. The number average molecular weight of the phenol resin is preferably from 600 to 1500. If it is smaller than 600, the viscosity of the molding material is reduced,
If the size of the molded article is likely to be anisotropic, if it is 1500 or more, sufficient fluidity cannot be obtained, and molding failure tends to occur.

The glass fiber (b) used in the present invention is a conventionally used glass fiber and usually has a fiber diameter of 15 μm.
m and a fiber length of 0.1 mm to 3 mm are used. However, those having a fiber diameter of less than 2 μm are difficult to produce and are not generally commercially available. If it exceeds 15 μm, the frictional resistance against the metal will increase, and the metal and resin molded products will be greatly worn. If the fiber length is less than 0.1 mm, the effect of improving the fatigue strength is small. If the fiber length is more than 3 mm, the frictional resistance against the metal increases, and the metal and resin molded articles wear significantly. (B) The compounding amount of the glass fiber is preferably 5 to 15% by weight of the whole molding material. 5% by weight
If it is less than 15%, the effect of improving the fatigue strength will be small, and if it exceeds 15% by weight, the wear resistance will decrease.

The crushed cotton fabric (c) used in the present invention comprises:
Those having a fiber length of 0.2 to 3.0 mm are preferred. 0.2
If it is less than 3.0 mm, the wear resistance and fatigue strength are not improved, and
If it exceeds mm, workability in the materialization stage is difficult, and the apparent density decreases. (C) The blending amount of the crushed cotton fabric is preferably 3 to 10% by weight of the whole molding material. If it is less than 3% by weight, the fatigue strength is reduced, and if it exceeds 10% by weight, the workability at the stage of forming the molding material is reduced, and the apparent density of the obtained molding material is reduced.

The phenolic resin molding material of the present invention uses, as a base material, a resin material in which glass fiber and a crushed cotton fabric are blended. Both of these base materials have improved fatigue strength. It greatly contributes to the improvement of the fatigue strength, and the crushed cotton fabric contributes to the improvement of the wear resistance. Therefore, a phenol resin molding material having excellent fatigue strength and abrasion resistance can be obtained by mixing these base materials in appropriate amounts.

The present invention provides (d) carnauba wax,
It is characterized in that (a) a phenolic resin, (b) glass fiber and (c) a crushed cotton fabric are melt-kneaded, cooled, pulverized, and then added and mixed. The phenolic resin molding material before mixing with carnauba wax has a melt viscosity at 110 ° C. of about 1 to 5 × 10 ³ Pa · s, which is equivalent to that of a phenolic resin molding material using general wood flour as a filler. Has viscosity. 11 after carnauba wax is mixed
The melt viscosity at 0 ° C. drops to about 1 to 9 × 10 ² Pa · s. This is because the phenolic resin molding material does not have a low viscosity, but the presence of carnauba wax at the interface between the wall surface of the viscometer and the phenolic resin molding material has a slipping effect and has the effect of lowering the apparent viscosity. It is.

Accordingly, the carnauba wax reduces heat generated by shearing from the screw and the cylinder wall when the molding material is plasticized and measured in the cylinder of the injection molding machine. Then, low pressure molding becomes possible to reduce the apparent viscosity of the molding material during injection molding, and cushion molding is realized. Further, at 150 to 200 ° C., the curing of the phenolic resin molding material is not prevented. For this reason, in the mold at the time of low pressure molding, the residual stress of the molded article is small, and the melt viscosity in the mold is the same as that of a general phenol resin molding material,
Orientation is unlikely to occur. From these, burrs are less generated during molding, and the dimensional accuracy of the molded product is good. The amount of carnauba wax added is usually 0.1 to 1.0 part by weight based on 100 parts by weight of other materials in total. When the addition amount is less than 0.1 part by weight, the above-mentioned action is small, and when the addition amount is more than 1.0 part by weight, the sliding of the material is large and the plasticization measurement becomes difficult.

Further, the phenolic resin molding material of the present invention further includes organic fillers such as wood powder, pulp powder, pulverized various fabrics, pulverized phenolic resin laminates and pulverized products, talc, clay, mica, carbonic acid and the like. One or more inorganic fillers such as calcium and carbon can be used. The mixing ratio in the phenolic resin molding material of the present invention is such that the resin component is 2%.
0 to 70% by weight, and the filler is 80 to 30% by weight. Further, the phenolic resin molding material of the present invention further comprises a lubricant,
Various additives such as a coloring agent, a curing accelerator, and a flame retardant can be appropriately compounded.

The phenolic resin molding material of the present invention is prepared by mixing a resin component, a filler, and other additives, kneading them with a roll, a twin-screw kneader, cooling, pulverizing, and then mixing carnauba wax with a mixer. It can be manufactured by mixing.

[0014]

EXAMPLES The present invention will be described below with reference to examples. In the formulations, "parts" are parts by weight. The phenol resin molding material was obtained by kneading with a mixture (parts by weight) shown in Table 1 using a heating roll. Of the formulations in Table 1, carnauba wax was prepared by roll-kneading other formulations, adding and mixing after pulverization.

[0015]

[Table 1]

(Measurement method) Melt viscosity: Shimadzu flow tester (CFT, Shimadzu Corporation)
The viscosity of the molding material at 110 ° C. was measured according to −500 C). (Unit of melt viscosity Pa · s) Weight change rate: The value obtained by measuring the weight change rate (measured number n = 100) of the molded product obtained by injection molding is shown. Weight fluctuation rate = (100 standard deviations / average weight) × 10
0 (%) Fatigue strength: In the method of measuring bending strength according to JIS K 6911, the load was set to 6 kgf, and the number of times until a test piece was repeatedly applied with a load to break was shown. 4. Abrasion resistance: In a Suzuki-type abrasion evaluation, a phenolic resin molded product and a metal (S-55C) were slid, and the amount of abrasion of the metal was indicated. (Unit: mg, load: 5 kgf / cm ² , peripheral speed: 100 m
m / s, test time 1 hour) Dimensional accuracy: A disk having a diameter of 50 mm was formed, and its circularity was measured with a three-dimensional measuring device. The circularity was less than 0.1 mm, and the circularity was 0.1 mm or more. The molded products for the fatigue strength, wear resistance and dimensional accuracy tests were produced by transfer molding (175 ° C., 3 minutes).

[0017]

As is clear from the above examples, the phenolic resin molding material obtained by the production method of the present invention has a small rate of weight variation of the molded article in the injection molding, the dimensional accuracy of the molded article, and the fatigue strength. And excellent wear resistance. Therefore, it is suitable for mechanical parts such as automobiles. In addition, since the apparent viscosity in the cylinder during injection molding is low, molding can be performed by a molding machine having a screw provided with a backflow prevention ring generally used for injection molding of a thermoplastic resin molding material. Further, since molding can be performed at a low pressure, generation of burrs can be suppressed.

Claims (2)

[Claims] 1. A phenolic resin molding characterized in that (a) a phenolic resin, (b) glass fiber and (c) a crushed cotton fabric are melt-kneaded, cooled and ground, and then mixed with (d) carnauba wax. Material manufacturing method. 2. The method for producing a phenolic resin molding material according to claim 1, wherein the amount of (d) carnauba wax is 0.1 to 1.0 part by weight based on 100 parts by weight of the total amount of other materials.