JPS59127712A - Method for preparing composition of sliding material - Google Patents

Abstract

PURPOSE:To obtain a composition for sliding material that can be injection, compression or transfer molded, by mixing uniformly a heat-resistant resin and organic fibers having a melting point higher than that of said resin under pressure and heating by using a pressurized type kneader. CONSTITUTION:When at least a heat-resistant resin and organic fibers having an average length of 1-10mm. and a melting point higher than that of said heat- resistant resin are mixed, a pressurized type kneader is used to mix them uniformly under pressure and heating. If the average length of the fibers is 1mm. or less, less reinforcing effect is observed, which if the average length of the fiberss 10mm. or more, they would, during the kneading cling fast to the blades of the kneader or become continuously entwined so that they interfere with the kneading operation or become difficult to take out the kneaded material. The high meling point organic fibers that can be used are aromatic polyamide fibers that can be obtained synthetically by the condensation of an aromatic diamine with an aromatic dicarboxylic acid or its derivative, and in particular polyparaphenylene terephthalamide fibers are preferred in view of heat resistance and reinforcing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for uniformly mixing a sliding material composition.

In recent, cutting-edge industrial fields, existing diaphragms are no longer sufficient, and new, high-performance functional materials are being sought. So-
1. Polymers with excellent thermal properties have been used in electronic devices in recent years as one of the materials that meet the advanced demands of industry.

Copy machines, microwave ovens, automobiles, industrial equipment, aircraft.

It is attracting attention and being adopted in fields such as nuclear equipment. 4
Thermal polymers are often used for applications that require severe usage conditions, such as high temperature and high speed sliding.

Recently, it has come to be used in applications that were once thought to be in the realm of metals and ceramics.

Polymers used for these applications generally include various fillers,
Combined with reinforcing materials, it is used as a functional composite material that meets required performance. Since various fillers are usually in powder form, it is easy to mix them uniformly with the resin, but it is extremely difficult to mix them uniformly when using fibers as reinforcing fillers. Even if you try to mix the powder and fibers as they are, the fibers will become entangled with each other and collect in the form of threads, making it impossible to mix the entire mixture uniformly.

Methods such as pre-impregnating cloth with resin and laminating the impregnated cloth, or molding resin-impregnated strands by filament winding cannot be applied to other molding methods such as injection, compression, and transfer. The same is true for resin-impregnated chopped fibers for screw-in die pump type. Furthermore, injection.

Raw materials mixed with powdered fibers used for compression and transfer molding methods have the disadvantage that uniform dispersion is impossible.

In the present invention, by blending a thermal polymer, a high-melting-point organic short fiber, and other fillers, we can inject and compress products with complex shapes that cannot be molded by lamination methods.

It is intended to be molded by a transfer method, and the purpose is to provide a molding raw material of good quality in which fibers and fillers are uniformly dispersed. This object of the present invention is achieved by the following configuration.

When mixing jL with at least a heat exchanger resin and an organic fiber having an average fiber length of 1 to 10 mm and a melting point higher than the above-mentioned heat suppressing resin, use a pressure kneader and uniformly mix under pressure and heat. A method for preparing a characterized sliding composition.

A pressure kneader is a device that has a mechanism in which a kneader mixing tank containing stirring blades is held down by a plunger using pneumatic or hydraulic pressure, and when raw materials are put into the kneader,
The raw material above the stirring blade is pressed down by the plunger and easily gets caught in the stirring blade. The pressure applied to the mixing tank by the plunger is preferably about 02 to 3 kg/cm2, and the pressure applied to the mixing tank is preferably about 0.2 to 3 kg/cm2.

It is preferable to change it appropriately depending on the blending ratio. Suitable conditions are that the stirring blade is rotated at a relatively low speed of 10 to 6 Orpm and kneaded for about 10 to 60 minutes. The kneader is heated to melt the polymer, but frictional heat is generated during kneading.
Since the internal temperature rises above the heating temperature, does heating the kneader melt the polymer? ;'7'L degree or less may be sufficient.

Next, as an auxiliary means for the preparation of the present invention, before kneading the raw materials with a pressure kneader, polymer powder and organic short fibers with an i7': + melting point are premixed using a 9-revolution mixer or a blender. is preferable. Of course, homogeneous mixing cannot be expected at this mixing stage, but the effect of premixing is recognized, and the premixed raw materials can be kneaded smoothly with a pressure kneader, and the mixed state becomes more uniform. After kneading with a pressure kneader, the mixed raw material is taken out from the kneader as a large lump, and it cannot be used for molding in 1-1.Therefore, the lump of the mixed raw material after cooling is crushed by a crusher. The advantages of the blending method of the present invention are that a four-heat polymer composition in which organic short fibers with a high melting point are homogeneously blended is obtained, and the blending method is simple. In addition to not requiring a complicated process and reducing costs, the bulk of the granular material after crushing is small, making it easy to feed the raw material to a molding machine, and obtaining a raw material suitable as a raw stone for molding.

The average length of the fibers used in the present invention is limited to 1 to 10 mm, but the reason for this is that when the average length is less than 1 mm, the reinforcing effect is not very noticeable. The fibers get entangled with the stirring blades of the kneader and are continuously connected, which hinders kneading and makes it difficult to take out the kneaded raw material. What is the high melting point organic fiber used in the present invention?

Aromatic polyamide fibers synthesized by condensation of aromatic diamines and aromatic dicarboxylic acids (or their derivatives), and polyparaphenylene terephthalamide fibers (e.g., DuPont's K e V ], a r■) are particularly heat-resistant. It is good in terms of strength and reinforcing effect.

Also included are cellulose fibers such as natural water pulp, cotton, and rayon.

Heat-resistant polymers include hardening type resins such as phenolic resin, epoxy resin, unsaturated polyester, and polyimide, as well as polyether sulfone, polysulfone, polyphenylene sulfide, polyether ether ketone,
Aromatic polyester.

It is a thermoplastic type resin such as polyimide.

The present invention will be explained below based on examples.

Examples 1 to 4 and Comparative Example 1 In Examples 1 and 3.4, Du
Kevlar 29 pulp (average fiber length: 2 mm) manufactured by Pont was used, and in Example 2, chopped fiber with a length of 6 plates was used. Example 1 as a thermosetting polyimide. 4 and Comparative Example 1, Rhone P
Kerimid■1000 powder manufactured by Oulenc.

In Example 2, polyimide powders synthesized using trimellitic anhydride, 4,4'-diaminodiphenylmethane, and nadic anhydride as raw materials were used. The method for preparing each raw material is as follows.

In Examples 1 and 2, the polyimide powder was 80% by weight.

Put 2Q of pulp or 6-plate chopped fiber into a dry blender and blend for a few minutes.
Rotate the blender to premix. In Example 4, polyimide is 60 weight, pulp is 20 weight, and graphite is 20 weight. In Example 4, polyimide is 60 weight,
Preliminary mixing was carried out for several minutes using a V-blender at a blending ratio of Parf'20iX jet and PTFE20 by weight. Next, in Example 1, 3.4, this premixed raw material was mixed with 8-0
℃, in Example 2, pressurized Nigni heated in advance to 180℃ was added, and a plunger was used to inject 1 to 1.5 J.
The stirring blade is rotated under pressure of /c+n2. The rotation speed was 30 rpm. When it starts rotating, frictional heat causes
The internal temperature of the polyimide becomes molten and kneaded. In this case, if the internal temperature rises too much, curing of the polymer will proceed, so it is necessary to control the internal temperature of the kneader so that it is equal to or higher than the melting temperature of the polymer, and the temperature within this range does not rise significantly. Kneading is carried out using a pressure kneader for about 20 minutes, and the kneaded raw materials are taken out from the kneader.

After cooling, put the lumps of all raw materials in a crusher to 10 nun
I crushed it coarsely with a ox to a certain size. In this case, if the material is crushed too finely, the fibers will be severely cut during the crushing process, and the bulk factor of the crushed raw material will increase.

10m4' as it becomes difficult to handle as a molding raw material.
.

coarse crushing is suitable. In addition, in Comparative Example 1, d: Kev1
ar■ Polyimide powder was used for the IT molding without adding short fibers or fillers and omitting the blending. Compression molding was performed using each of the raw materials prepared in this manner. Example 1
, 3.4 and Comparative Example 1, the temperature was 260°C and the pressure was 3D.
The mold was molded by heating the inner blade of the mold for 15 minutes under the condition of D kg/an2, and the cured product was taken out.

This cured product was further treated with Bost Guar treatment at 200° C. for 2 days, and then its physical properties were examined.

The molding conditions of Example 2 were a temperature of 290°C and a pressure of J00
Molded in a mold for 40 minutes under the condition of kg/an・2.

Once the cured product is removed from the mold, heat it at 260C for 2 hours.
Bost cured for 1 day.

Figures 1 and 2 show the cross sections of the molded products of Examples 1 and 2.
The results were examined using a scanning electron microscope and magnified 200 times.
This shows that the r■ pulp and chopped short fibers are uniformly dispersed.

In addition, the flexural strength 9 elastic modulus of the molded product of each example,
Friction/Abrasion 8 Indicates machinability and bulk factor of blended raw materials. Generally, when resin powder and fiber are mixed, the bulk factor increases significantly.

Although it is difficult to fill the mold into a mold during molding, it is clear that the raw material prepared by the method of the present invention has no difference in bulk coefficient and kneading compared to the resin powder alone, and is easy to handle as a molding raw material. Molded products made from raw materials prepared by the method of the present invention have excellent mechanical strength.

In particular, it is clear that the combination of K e V lar ■ short fibers and graphite or PTFE has excellent sliding properties (2) and machinability.

Comparative Examples 2 to 4 Regarding the mixing method of polyimide powder and K e v ], a, r■ short fibers, Comparative Example 2 used a ■ blender, Comparative Example 6 used a ribbon blender, and Comparative Example 4 used a super mixer. and both ingredients on a dry basis.

Conduct a mixing test by changing the blending ratio and mixing conditions/ζ.

In Comparative Examples 2 and 3, the fibers &[l were agglomerated into a ball of thread.

Uniform mixing is not possible and a homogeneous molded product cannot be obtained.

Furthermore, the mixture has the disadvantage of being extremely bulky and difficult to mold. In Comparative Example 4, the raw material 151 inserted into the container is not mixed entirely, but only locally around one rotor.

[Brief explanation of the drawing]

FIGS. 1 and 2 are micrographs of cross-sections of molded products mixed by the method according to the invention. FIG. 1 is based on the first embodiment, and FIG. 2 is based on the second embodiment. Patent applicant Toshi Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) At least a heat-resistant resin and an average fiber length of 1 to 10
A pressure kneader is used when mixing organic fibers having a melting point higher than that of the heat-resistant resin in mm. A method for preparing a sliding material composition characterized by uniformly mixing the composition under pressure and heat.