JPS63301259A - Resin composition for slidable mechanical part - Google Patents

Abstract

PURPOSE:To obtain the title composition which is light and excellent in dimensional accuracy and heat resistance and enables mass production of slidable mechanical parts which need not be afterfinished, by mixing a thermoplastic resin with a whisker and a heat-resistant fiber each having an average fiber diameter and tensile range each in a specified range and a powdery solid lubricant. CONSTITUTION:35-80wt.% thermoplastic resin (A) (e.g., polybutylene terephthalate) which has preferably a heat distortion temperature of the obtained resin molding of >=150 deg.C (under a load of 18.6kgf/cm<2>) is mixed with 10-50pts. wt. whisker (B) of an average fiber diameter <=5mu and a tensile modulus >=10,000 kgf/mm<2> (e.g., potassium titanate whisker), 7-30pts.wt. heat-resistant fiber (C) (e.g., silicone carbide fiber) of an average fiber diameter <=30mu and a tensile modulus >=6,500kgf/mm<2> (e.g., silicone carbide fiber) and 3-25pts.wt. powdery solid lubricant (D) such as high-density PE or MoS2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resin composition for mechanical parts having sliding properties. More specifically, the present invention provides mechanical parts for transportation machines such as automobiles and aircraft, electrical and communication equipment, and precision machinery, with high dimensional accuracy, rigidity close to that of metal, and frictional sliding between metal and resin parts or between resin parts. The present invention relates to a resin composition as a material suitable for use in areas subject to vibration.

Conventional Technology and Problems Theretofore, many metal parts have been replaced with resin parts for reasons of more efficient manufacturing and weight reduction, but even now there remain many parts that are difficult to replace. The reasons for this are that resin parts have inferior rigidity and heat resistance compared to metal parts, are difficult to injection mold with high dimensional accuracy, and have greater wear during sliding than oil-lubricated metal parts. Examples include:

Means for Solving the Problems The object of the present invention is to be able to be manufactured by injection molding, which is a method with excellent mass productivity, to be lightweight and highly rigid, to have good dimensional accuracy, and to have excellent heat resistance, and to be free from lubricating oil. The present invention provides a resin composition for mechanical parts that can be operated under reduced conditions.

That is, the present invention includes (1) 35 to 80 parts by weight of thermoplastic resin, (2) average fiber diameter of 5 μm or less, and tensile modulus of 10,000 kc+f/
Whiskers of mm2 or more 10 to 50 parts by weight, (3) Average fiber diameter 30 μm or less, tensile modulus 6500
The present invention relates to a resin composition for mechanical parts, which contains 7 to 30 parts by weight of heat-resistant fibers of kgf/mm2 or more, and (4) 3 to 25 parts by weight of a powdered solid lubricant.

The thermoplastic resin used in the present invention has a heat deformation temperature of the resulting resin composition (18, 6! J
A wide variety of conventionally known materials can be used as long as they have a temperature of 150'C or higher (under a load of f/cm2). Such thermoplastic resins include, for example, polyethylene terephthalate, polybutylene terephthalate, fully aromatic polyesters (such as liquid crystal polymers such as U polymer and Vectra,
(econol, etc.), nylon-6, nylon-6,6, nylon-4,6, nylon-MXD6, borosulfone, polyallylsulfone, polyethersulfone, polyphenylene sulfide, polyetheretherkene, poly Examples include etherketone, polyetherimide, polyamideimide, polyimide, etc., and these may be used alone or in combination of two or more. If the thermoplastic resin is such that the heat distortion temperature of the resulting resin composition is less than 150°C when composite reinforcement is performed by adding a predetermined amount of whiskers and heat-resistant fibers, the heat resistance of the resulting resin composition is This is undesirable because it becomes insufficient, making it unsuitable for mechanical parts installed in, for example, the engine room of an automobile or other locations close to a heat source.

The whiskers used in the present invention have an average fiber diameter of 5 μm or less and a tensile modulus of 10,000 kc+f/mm2JJ. Examples of such whiskers include potassium titanate whiskers, silicon carbide whiskers, carbon graphite whiskers, silicon nitride whiskers, and α-alumina whiskers. In the present invention, these whiskers may be used singly or in a mixture of two or more. By blending the above whiskers, it is possible to improve the dimensional accuracy of mechanical parts, strengthen the gaps between the heat-resistant fibers used as component (C), and evenly distribute the heat-resistant fibers in the resulting resin composition. can be filled. If the whisker used has an average fiber diameter of more than 5 μm, it is not preferable because the surface smoothness required for the sliding surfaces of mechanical parts will deteriorate. Further, if the whisker used has a tensile modulus of less than 100100 O0/mm2, it is difficult to expect the resin composition to have a rigidity close to that of metal due to the addition of the whisker, which is not preferable. In the present invention, it is particularly preferable to use potassium titanate whiskers or silicon carbide whiskers having an average fiber diameter of 1 μm or less.

The heat-resistant fiber used in the present invention has an average fiber diameter of 30 μm.
m or less, and the tensile modulus is 6500 kgf/mm2 or more. As such heat-resistant fibers, a wide variety of conventionally known fibers can be used as long as they are fibrous materials with long-term heat resistance of 150'C or higher, such as carbon fibers, alumina fibers,
Examples include zirconia fibers, silicon carbide fibers, silica fibers, glass fibers, and aramid fibers. In the present invention, these heat-resistant fibers may be used singly or in a mixture of two or more. The reason why the average fiber diameter is 30 μm or less is because
This is because if the average fiber diameter exceeds 30 μm, it becomes difficult to suppress the surface roughness required for the accuracy of the sliding surfaces of mechanical parts to 10 seconds or less even if the above-mentioned whiskers are used together. In the present invention, heat-resistant fibers having an average fiber diameter of 15 μm or less, particularly carbon fibers and para-aramid l! Preferably, fibers are used. Also, the tensile modulus is 6500 kof/mn+2
Based on the above, the bending elastic modulus of the resin composition for mechanical parts of the present invention is at least 500 kgf/mm2 as a metal substitute.
This is because it is necessary to ensure a tensile modulus of 20,000 kgf/mm or more (Dfulmi tmN,
Silicon carbide fibers and carbon fibers are suitable, and PAN-based high-strength or high-modulus carbon fibers are particularly suitable. In addition, these heat-resistant fibers have a fiber length of 0.5 to 5.
It is desirable to use the fiber as a cut fiber of mm in terms of production of pellets and injection moldability.

Examples of the powdery solid lubricant used in the present invention include polytetrafluoroethylene, high-density polyethylene (including ultra-high molecular weight polyethylene), wholly aromatic polyamide,
Fully aromatic polyester, granular phenol and its graphitized product, graphite, molybdenum disulfide, tungsten disulfide, W
Examples include S e 2 , MO32 , MO8e2 , boron nitride, and the like. In the present invention, these powdered solid lubricants are used alone or in a mixture of two or more. By blending such a powdered solid lubricant, it is possible to significantly improve the friction and wear resistance of mechanical parts molded from the resulting resin composition for mechanical parts. In the present invention, the average particle diameter is 100
It is particularly preferable to use a powdered solid lubricant having a particle size of 0.2 mm or less. If a powdered solid lubricant with an average particle size exceeding 100 μm is used, it is not preferable because the surface smoothness of mechanical parts molded from the resulting resin composition for mechanical parts tends to be poor.

In the present invention, it is important to mix the various components mentioned above in the proportions shown below.

That is, the thermoplastic resin is the composition 100 of the present invention @ Tsunebe (
35 to 80 parts, preferably 40 to 70 parts (hereinafter simply referred to as "parts").

If the amount of the thermoplastic resin blended is less than 35 parts, this is not preferable because problems arise in the injection moldability of the resulting resin composition and the material of the injection molded mechanical parts tends to become brittle. On the other hand, the blending amount of thermoplastic resin is 8
If it exceeds 0 parts, the flexural modulus of the resulting resin composition will be 5 parts.
00 kgf/mm2, which is not preferable.

The above whiskers may be present in 10 to 100 parts of the composition of the present invention.
The amount is preferably 50 parts, preferably 15 to 30 parts.

If the amount of whiskers added is less than 10 parts, it is not preferable because the effects based on the addition of whiskers (especially improvements in surface smoothness and dimensional accuracy) become difficult to achieve. Furthermore, when the blending amount of whiskers exceeds 50 parts, on the other hand, the blending amounts of thermoplastic resin, heat-resistant fiber, and powdery solid lubricant become relatively small, and as a result, the desired effect of the present invention is not exhibited. This is not desirable as it makes it difficult to be exposed.

The above-mentioned heat-resistant fibers are contained in 7 to 3 parts per 100 parts of the composition of the present invention.
0 parts, preferably 10 to 25 parts. If the amount of heat-resistant fibers added is less than 7 parts, it is not preferable because the effect (especially improvement in impact resistance) based on the addition of heat-resistant fibers becomes difficult to achieve. Furthermore, if the amount of heat-resistant fibers exceeds 30 parts, it becomes difficult to suppress the surface roughness required for the accuracy of the sliding surfaces of mechanical parts to 10 seconds or less, which is not preferable.

The powdered solid lubricant is preferably blended in an amount of 3 to 25 parts, preferably 5 to 15 parts, per 100 parts of the composition of the present invention. When the blend i of powdered solid lubricant is less than 3 parts,
This is not preferable because it becomes difficult to achieve the effects (in particular, improvement in sliding properties) due to the addition of the powdered solid lubricant. On the other hand, if the amount of solid lubricant exceeds 25 parts, the strength of the mechanical parts tends to decrease significantly, which is not preferable.

In the resin composition of the present invention, the whiskers or a part of the heat-resistant fibers may be treated with an inorganic filler such as talc, mica, or silica, or the surface may be To increase hardness, it is also possible to replace metal whiskers such as chromium and nickel, and metal powders such as brass and zinc.In some cases, carbon black,
Of course, it is also possible to incorporate colorants such as inorganic or organic pigments, heat stabilizers, and the like.

The resin composition of the present invention is manufactured, for example, by the method shown below. For example, the thermoplastic resin, whiskers, heat-resistant fibers, and powdered solid lubricant are weighed in predetermined amounts, mixed uniformly with a blender such as a tumbler mixer, mixed with a melt kneader such as an extruder, and then pelletized. It is common to manufacture

The specific gravity of the resin composition of the present invention is usually within the range of 1.3 to 2.0, but when high specific gravity alumina whiskers, zirconia fibers, metal whiskers, or metal powders are used together, the specific gravity is up to 2.9. It is possible up to

Example Examples are given below to further clarify the present invention.

Examples 1 to 4 and Comparative Examples 1 to 2 Each component was mixed in a blender in the proportions (weight items) shown in Table 1 below, and after melting and mixing using a 45 mm extruder at a cylinder temperature of 240'C. , pelletized with a cutter. The obtained pellets were heated to a cylinder temperature of 240'C1.
Mold temperature 70°C1 Injection pressure (primary pressure>650kgf
/cm2, holding pressure (secondary pressure) 300 kgf/cm2, ASTM test pieces and precious wood type thrust friction wear pieces were injection molded, and then left in a constant temperature and humidity room at 20°C and 150% RH for 24 hours, and the following physical properties were obtained. We evaluated the following. The results are shown in Table 2 below.

Specific gravity: ASTM D792, measured using an Izot impact piece.

Flexural modulus: ASTM D790. Thickness 6.4mm,
Width: 12.7 mm, test speed: 5 mm, 7 minutes.

Heat deformation temperature 2: Measured using ASTM D648 and the same test piece as above at a load of 18.6 kgf/cm2.

Sliding properties: Precious wood type friction and wear tester (EFM-I[1-E
N, manufactured by Toyo Baldwin Co., Ltd.], mating material: AQ-505
2 (Surface roughness, Ra=0.07μn, Rz=0.57μ
m), measurement load: 10kgf/cm2, circumferential speed: 30
cm/sec, mileage: 10km.

Izotsu impact value: ASTM D256, width 6, 6m
m (1/4 inch), thickness 12.7mm V notch post-processing.

Surface roughness 2 The sliding surface of the above Suzuki type thrust wear piece was measured with a surface roughness meter [Surfcom 304B, manufactured by Tokyo Seimitsu Co., Ltd.] to 2.5.
The length was measured in mm and expressed as the maximum height Rmax.

In Table 1, the various components used are as follows.

<Thermoplastic resin> A-1: PBT resin (PBT CL7000, manufactured by Yojinsha) <Whisker> B-1: Potassium titanate [Teismo D102 (average fiber diameter 0.3 μm, tensile modulus 28000 kgf/mm"), Big W (tJ company'N
:] B-2: Alumina whisker (Safil (average fiber diameter 3 μm, tensile modulus 49200 kqf/mm2),
Manufactured by ICI] <Heat-resistant fiber> C-1 Niglass fiber (FES-03-1208P (average fiber diameter 10/im, tensile modulus 7700 kgf/mm2, fiber length 3 mm) manufactured by Fuji Fiberglass) C-2; Silicone carbide fiber [Nicalon (average fiber diameter 12 μm, tensile modulus 20000 kof/mm2, fiber length 3 mm), manufactured by Nippon Carbon Co., Ltd.] C-3: Aramid fiber: Kevlar-49 (average fiber diameter 12
μm, tensile modulus of elasticity 13300 kgf/mm2, fiber length 3 mm>, manufactured by Toshi DuPont Co., Ltd.] <Powdered solid lubricant> D-ni HOPE (Hisex 5000 (average particle size 30 μm, average molecular weight 70,000), Mitsui Petrochemical manufactured by Asahi Fluoropolymer Co., Ltd.] D-2: PTFE (Fluon L150J (average particle size 9 μm), manufactured by Asahi Fluoropolymer Co., Ltd.) D-32 MO82
(Moly powder B (average particle size 5.0 μm), manufactured by Nippon Graphite Industries Co., Ltd.) <Filler> E-1: Brass powder The following is clear from Tables 1 and 2.

That is, in Comparative Example 1 in which no heat-resistant fibers were blended, the wear resistance (specific wear amount was large) and impact resistance were insufficient. Comparative Example 2, which does not contain whiskers, has the disadvantage that a smooth surface of 10 seconds or less cannot be obtained as seen in the surface roughness, and that the sliding properties are greater than the mating material (AQ-5052).

On the other hand, in Examples 1 to 4 in which whiskers and heat-resistant fibers were blended together, the flexural modulus was 500 kgf/m.
m2 or more, heat deformation temperature 150'C or more, sliding characteristics are kinetic friction coefficient 0.25 or less, wear resistance is good with small specific wear of both the material itself and the mating material, and impact resistance is also better than that of heat-resistant fibers. It has been improved due to the combined effect. Therefore, it can be seen that the resin compositions of Examples 1 to 4 are extremely suitable as resin compositions for mechanical parts having 1 behavior.

Examples 5 to 9 Examples 1 to 4 above except for the formulation shown in Table 3 below.
A resin composition (pellet) is created in the same manner as AST
M test pieces and thrust wear pieces were injection molded and evaluated in the same way. The results are shown in Table 4.

The various components in Table 3 are as follows.

Thermoplastic resin> A-2: Nylon-6,6 [Manilaru A127, IC
Manufactured by Company I] A-3: Polysulfone [Needel Polysulfone P-17
00, manufactured by Union Carbide Company] A-4: Polyphenylene sulfide (Rydon R-6, manufactured by Phillips Vetroleum Company) A-5: Polyether ether ketone [
Pictrex PEEK450G11CI manufactured by A-6
: Polyetherimide [Ultem #1010, manufactured by GE Corporation] <Whisker> B-3: SiC whisker [TOKAMAX (average fiber diameter 0.5 μm, tensile modulus 41000k (If/mm2), Higashi 215 manufactured by Carhon Co., Ltd.) Heat-resistant fiber> C-4: Carbon fiber (Besphite HTA-C6-NR (
Average fiber diameter 7 μm, tensile modulus 24000 kgf/mm2, fiber length 6 mm), manufactured by Toho Rayon Co., Ltd.) <Powdered solid lubricant> D-4: UHMPE (Hisex Million fine powder (average particle size 50 μm, average molecular weight) 3 million), manufactured by Mitsui Petrochemical Industries, Ltd.] D-5: Fully aromatic polyamide (polyphenylene isophthalamide resin powder (average particle size 86 μm), manufactured by Yojinsha) D-6: Graphite (ACP-1000 (average particle size 6 μm) ,
(fixed carbon 99.5%), manufactured by Nippon Graphite Industries Co., Ltd.] Effects of the Invention According to the present invention, it is lightweight, has high rigidity, has good dimensional accuracy, has excellent heat resistance, and can be operated with less lubricating oil. A resin composition for mechanical parts is provided. Furthermore, by using the resin composition of the present invention, mechanical parts having desired performance can be manufactured by injection molding, a method with excellent mass productivity, without the need for post-processing. The mechanical parts obtained in this way do not rust, and the material itself has good sliding properties and does not damage the mating material, so it has good durability, and can therefore be used as a substitute for metal parts. .

(that's all)

Claims (1)

[Claims] [1] (1) 35 to 80 parts by weight of thermoplastic resin, (2) 10 to 5 whiskers having an average fiber diameter of 5 μm or less and a tensile modulus of 10,000 kgf/mm^2 or more
0 parts by weight, (3) Average fiber diameter 30 μm or less, tensile modulus 6500k
A resin composition for mechanical parts, comprising 7 to 30 parts by weight of heat-resistant fibers having a gf/mm^2 or more, and (4) 3 to 25 parts by weight of a powdered solid lubricant.