JPH0819256B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition, and more particularly to a resin composition useful for forming corrosion resistant pumps, joints and pipes.

[Problems to be Solved by Conventional Techniques and Inventions]

For corrosion resistant pumps, joints, pipes, etc.
Stainless steel, nickel alloy (for example, Hastelloy), titanium alloy, etc. are generally used. However, these materials have drawbacks in that the material itself is expensive, it is difficult to process, and in the metal processing, the smoothness in the finished surface is poor, the pressure loss of fluid resistance is large, and the pump efficiency is poor.
Therefore, recently, the processing cost has been reduced by injection molding or compression molding using a plastic material.
In addition, since the plastic material has a smooth surface, it has advantages such as improved pump efficiency.

However, those made of plastic materials have a remarkable decrease in strength at high temperatures, which limits the usable temperature range.

Therefore, the inventors of the present invention have conducted intensive studies to develop a plastic material that does not exhibit strength reduction even at high temperatures, has a wide operating temperature range, and has excellent corrosion resistance, mechanical strength, workability, smoothness, and the like. .

[Means for solving the problem]

As a result, they have found that the above object can be achieved by combining a specific graphite powder and a specific carbon fiber as a filler into a certain polymer or copolymer and compounding them in a specific amount. The present invention has been completed based on such findings.

That is, the present invention includes (a) a graphitization ratio of 70% or more and a particle size of 2
30 to 70 parts by weight of a filler composed of graphite powder of μ or less and carbon fiber having a graphitization ratio of 70% or more, and (b) polypropylene,
Polyvinylidene difluoride, polytetrafluoroethylene-fluoroalkoxy (PFA) and fluorinated ethylene-
At least one resin selected from propylene copolymers
A resin composition comprising 100 parts by weight is provided.

In the resin composition of the present invention, a specific graphite powder and a specific carbon fiber are used together as the filler which is the component (a). Here, the corrosion resistance of the resin composition obtained by using the graphite powder and the carbon fiber alone is improved, but the graphite powder alone has insufficient strength, while the carbon fiber alone is used, The orientation due to the flow at the time of molding causes warp twist in the molded product, which causes a problem that the shape of the product cannot be accurately maintained. In order to solve these problems, it is necessary to use graphite powder and carbon fiber together as described above. Regarding the usage ratio of both, the required characteristics of the resin composition (or molded product) to be manufactured, etc. However, it is difficult to set a unique value. However, generally, the weight ratio of graphite powder / carbon fiber is 20 / 80-80 / 20, preferably 30
It may be selected in the range of / 70 to 60/40.

The graphite powder used has a graphitization ratio of 70% or more in order to exhibit the above characteristics, and has a particle size of Stokes's measuring method, that is, a particle size of 2 μ (central particle size) or less by the Andreasen pipette method. .

The carbon fiber is required to have a graphitization ratio of 70% or more due to the requirement for chemical resistance of the obtained resin composition, but it is a fibrous material composed almost entirely of carbon element. , Carbon fibers obtained by growing single crystals. Examples of such fibers include graphite fibers produced by a vapor phase pyrolysis method. The length of the fiber is 3 to 30 mm, preferably 6 to 25 mm.

On the other hand, in the resin composition of the present invention, the resin used as the component (b) is selected from polypropylene, polyvinylidene fluoride, polytetrafluoroethylene-fluoroalkoxy (PFA) and fluorinated ethylene-propylene copolymer. One or more than one.
The polypropylene may have an isotactic structure, a syndiotactic structure, or an atactic structure, but is preferably a homopolymer or a random polymer having an ethylene content of 4% by weight or less from the viewpoint of chemical resistance. , And its weight average molecular weight is
It is preferably about 30,000 to 80,000. The polyvinylidene fluoride preferably has a weight average molecular weight of 70,000 to 250,000. There are various types of PFA, but normally, it has a structure in which several percent of perfluoroalkoxy (eg, perfluoropropoxy) is bonded to the side chain of polytetrafluoroethylene (Teflon), and its weight average molecular weight is Those of 70,000 to 250,000 are preferable. Further, the fluorinated ethylene-propylene copolymer preferably has the same weight average molecular weight, and the fluorination ratio in the ethylene-propylene copolymer is preferably about 20 to 42%.

In the resin composition of the present invention, the blending ratio of the component (a) and the component (b) is, in order to achieve the object of the present invention, 100 parts by weight of the resin which is the component (b) and the graphite which is the component (a). The total amount of powder and carbon fiber is selected from the range of 30 to 70 parts by weight.

The resin composition of the present invention has the above-mentioned components (a) and (b) as the main components, but if necessary, various additives generally used in the field of polymer processing are appropriately mixed. be able to. Examples of additives include various coupling agents for improving the adhesiveness of metal-containing inorganic substances and polymers, such as silane coupling agents, lubricants, plasticizers, colorants, antioxidants, UV absorbers, Examples include nucleating agents and stabilizers.

The components (a) and (b) as described above and various additives that are optionally used are mixed with a commonly used mixer such as a Henschel mixer, a dumpler, and a ribbon blender. As the kneading machine, a single-screw or twin-screw extruder is generally used. With such an extruder, first, pellets made of the composition of the present invention are first produced, and the pellets are compression-molded or injection-molded. The desired resin product may be formed by molding into an arbitrary shape by extrusion molding stamping molding or the like.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. The granular graphite used in Examples and Comparative Examples had a graphitization ratio of 70% or more, a particle size of 2 μm or less, and a carbon fiber graphitization ratio of 70% or more.

Example 1 5 kg of granular graphite, 5 kg of carbon fiber (chopped strand, average length: 13 mm) and homopolypropylene (MFR = 40 g / 10
Min) 28.5kg with screw diameter 40mm and cylinder length (L)
And a screw diameter (D) ratio of L / D = 28 was used to extrude at a temperature of 200 ° C. for pelletization.

Next, injection molding was performed with a die having a film gate in the shape of a flat plate of 130 × 130 mm and a thickness of 2.0 mm.

The warpage in the injection property, the ratio of M / T (M: shrinkage in the injection direction,
(T; shrinkage ratio in the direction perpendicular to the injection direction) was measured for the above-mentioned molded plate as an evaluation means, and M / T ≈ 1.08
It was found that the flow anisotropy was low.

After immersing the obtained flat plate in a 10% nitric acid solution at 80 ° C for 100 hours, the tensile strength retention ratios were compared.
%Met. Dichlorosulfuric acid / sulfuric acid mixture 30
% Aqueous solution, a retention rate of 88% was observed and high chemical resistance was observed.

On the other hand, the flexural strength at 90 ° C, which is expected to be used as a pump component, is 350 kg / cm ² , and the flexural modulus is 35000 kg / cm ² , which proves that it retains high strength even at high temperatures.

Examples 2-5 Weight ratio of granular graphite and carbon fiber (granular graphite / carbon fiber)
80/20, 70/30, 30/70, 20/80, respectively, and except that the total amount of the granular graphite and the carbon fibers was 35% by weight, a flat plate was formed in the same manner as in Example 1, Various measurements were performed.

As a result, it was found that the shrinkage ratio M / T of the injection molding was 1.2 or less as shown in Table 1, and warpage and twist were small.

Further, the chemical resistance test showed a retention rate of 80% or more, and it was proved that the chemical resistance was good.

Comparative Example 1 A flat plate was formed in the same manner as in Example 1 using granular graphite and polypropylene without using carbon fiber in Example 1, and various measurements were performed.

As a result, the injection molding shrinkage ratio M / T was 1.08, but the bending strength at 90 ° C did not reach the target of 300 kg / cm ^2, and the bending elastic modulus at 90 ° C was at the target of 30000 kg / Since it did not reach cm ² , it was unsuitable for the use of pump parts at high temperature.

Comparative Example 2 In Example 1, only carbon fiber was blended in homopolypropylene so as to be 35% by weight, and a flat plate was molded in the same manner as in Example 1 and various measurements were performed.

As a result, the injection molding shrinkage ratio M / T was 2.5, and
When I tried injection molding again with a box shape of 0x150x150, the box was twisted and could not be die-cut.

The compositions of the fillers used in the above Examples and Comparative Examples and the properties of the molded articles obtained are shown in Table 1 below.

In addition, M / T is the shrinkage ratio when molded with a flat plate mold of 130 × 130 × 2 mm film gate, and the chemical resistance test A is
The retention rate of tensile strength after immersion in 10% nitric acid at 80 ° C. for 100 hours, and the chemical resistance test B is the retention rate of tensile strength after immersion in a mixed solution of dichromic acid and sulfuric acid under the same conditions as A.

[Effects of the Invention] According to the resin composition of the present invention, in which a specific amount of a specific graphite powder and a specific amount of carbon fiber are used as a filler, the strength does not decrease at high temperature, and warpage and sink marks are caused in injection molding and stamping molding. A molded product with excellent dimensional stability and chemical resistance without twisting can be manufactured.

Therefore, the resin composition of the present invention is a corrosion resistant pump,
It can be effectively used as a molding material for joints and pipes.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 27/12 (72) Inventor Osamu Hamazoe 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko Kawasaki Plastics Research Co., Ltd. (72) Inventor Akinori Kodama 3-2 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko Co., Ltd. Kawasaki Plastics Research Co., Ltd. (56) Reference JP-A 63-12663 (JP, A) JP Sho 60-144364 (JP, A)

Claims (1)

[Claims] 1. A filler 30 to 70 parts by weight comprising (a) a graphite powder having a graphitization ratio of 70% or more and a particle size of 2 μ or less and a carbon fiber having a graphitization ratio of 70% or more, and (b) a polypropylene or a polyfluorine. A resin composition comprising 100 parts by weight of at least one resin selected from vinylidene chloride, polytetrafluoroethylene-fluoroalkoxy and a fluorinated ethylene-propylene copolymer.