JP2003201398A - Gear made of resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear made of a resin which excels in dimensional accuracy and long-term strength. <P>SOLUTION: The gear is obtained by molding a resin composition to be obtained by compounding 10 pts.wt. resin component comprising (A) 80-96 wt.% polyamide obtained by polymerizing a diamine containing ≥70 mol% m- xylylenediamine and a carboxylic acid containing ≥70 mol% 6-12C α,ω-aliphatic dicarboxylic acid, (B) 2-10 wt.% unsaturated organic acid-modified polyolefin, and (C) 2-10 wt.% ultra-high-molecular-weight polyethylene with (D) 40-250 pts.wt. glass fibers. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has excellent dimensional accuracy,
The present invention relates to a resin gear having excellent long-term durability of mechanical strength.

[0002]

2. Description of the Related Art Conventionally, as a molding material for a resin-made gear obtained by molding a resin, a non-reinforced resin represented by polyoxymethylene has been used for applications where relatively high strength is not required. Fiber-reinforced polyamide,
Fiber reinforced resins such as fiber reinforced polyphenylene sulfide have been used.

However, when a resin-made gear is molded with a fiber-reinforced resin, the fiber orientation differs between the gate and weld of the molding die, and due to this fiber orientation difference, the true gear of the resulting gear is obtained. There is a problem that the roundness becomes poor and a resin gear having excellent dimensional or shape accuracy cannot be obtained. In the case of fiber reinforced nylon based on nylon 6, nylon 66, nylon 46, etc.,
After molding, there is a problem that dimensional change occurs due to moisture absorption, which further deteriorates dimensional accuracy.

On the other hand, the polyamide obtained by reacting metaxylylenediamine with an aliphatic dicarboxylic acid having 6 to 12 carbon atoms has a small dimensional change due to moisture absorption. It has been reported that the molding material has excellent chemical, thermal and mechanical properties as compared with fiber reinforced nylon 6 and nylon 66 (Japanese Patent Laid-Open No. 61414/1975).

[0005]

However, Japanese Patent Laid-Open No. Sho 50-
JP-A-61449 discloses a resin obtained by molding a glass fiber reinforced resin in which glass fiber is mixed with polyamide obtained by reacting metaxylylenediamine with an aliphatic dicarboxylic acid having 6 to 12 carbon atoms. It cannot be said that the gear has sufficient long-term strength, that is, long-term durability of mechanical strength and durability as compared with resin gears obtained by molding nylon 6 or nylon 66 reinforced with glass fiber. Improvement was desired.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a resin gear having excellent dimensional accuracy and long-term strength.

[0007]

The resin gear of the present invention comprises:
(A) Polyamides 80 to 96 obtained by polymerizing a diamine containing 70 mol% or more of metaxylylenediamine and a carboxylic acid containing 70 mol% or more of an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms. 100% by weight, (B) 2 to 10% by weight of unsaturated organic acid-modified polyolefin, and (C) 2 to 10% by weight of ultrahigh molecular weight polyethylene.
It is characterized by being formed by molding a resin composition obtained by blending 40 to 250 parts by weight of glass fiber (D) with respect to parts by weight.

A polyamide obtained by polymerizing a diamine mainly containing metaxylylenediamine and a dicarboxylic acid mainly containing an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms, is added to an organic acid-modified polyolefin, ultrahigh If the resin composition is a mixture of molecular weight polyethylene and glass fibers in a predetermined ratio, a resin gear having less dimensional change due to moisture absorption than a conventional glass fiber reinforced nylon resin composition and having good long-term strength can be obtained. It can be molded.

That is, as described above, a polyamide obtained by polymerizing a diamine mainly containing metaxylylenediamine and a dicarboxylic acid mainly containing an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms has a moisture absorption property. It contributes to the dimensional stability of resin gears due to small dimensional changes. Further, although it shows good characteristics in terms of chemical, thermal and mechanical strength, it has a problem in terms of long-term strength.

By mixing ultra high molecular weight polyethylene with such a polyamide, the ultra high molecular weight polyethylene is dispersed in the polyamide in the form of islands (domains) and is also present on the surface of the resulting resin gear, and the slip agent ( It functions as a lubricant) and contributes to the improvement of the slidability and wear resistance of the resin gear.

Further, the unsaturated organic acid-modified polyolefin enhances the affinity between the polyamide and the ultra-high molecular weight polyethylene to prevent the ultra-high-molecular-weight polyethylene from falling off, and the unsaturated organic acid-modified polyolefin itself is resistant to the resin gears. It contributes to the improvement of wear resistance.

From the above, by blending polyamide with ultra-high molecular weight polyethylene and unsaturated organic acid-modified polyolefin, the slidability and wear resistance of the resin gear are increased and the long-term strength is improved. .

In the present invention, the glass fiber used as the reinforcing fiber particularly has an average residual fiber length of 80 to 1000 μm.
m is preferable, and in particular, non-circular cross-section glass fiber having a ratio of major axis to minor axis of 1.5 to 6: 1 in a cross section perpendicular to the length direction is preferable.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the resin gear according to the present invention will be described in detail below.

The component (A) polyamide used in the present invention comprises a diamine containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid containing 70 or more mol% of an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms. Obtained by polymerization.
As the diamine component, metaxylylenediamine alone or a mixture of xylylenediamine of 70 mol% or more and metaxylylenediamine of 30 mol% or less is used. As the acid component, α, ω- having 6 to 12 carbon atoms
Aliphatic dicarboxylic acids such as adipic acid, sebacic acid,
Examples thereof include suberic acid, dodecanedioic acid, and eicodioic acid. These may be used alone or as a mixture of two or more kinds. Adipic acid is preferably used as the acid component.

The polyamide as the component (A) is produced by a polycondensation reaction of these two components. It should be noted that this polyamide has a drawback that it is slow to crystallize as compared with ordinary nylon 6 and the like, so that it is used as a crystal nucleating agent in JP-A-50-61.
A small amount of talc described in Japanese Patent No. 449, JP-A-51-63.
A small amount of nylon 66 described in 860, JP-A-3-52
953 gazette, montanic acid salt, montanic acid ester or montanic acid ester salt, or average particle size 1 to
You may mix 10-micrometer talc.

As the polyamide as the component (A), a commercially available product may be used. "Renny 6002" manufactured by Mitsubishi Engineering Plastics Co., Ltd. used in Examples described later is a polyamide obtained by polycondensation reaction of metaxylylenediamine and adipic acid with nylon 66 and talc as a nucleating agent. Can be used as the component (A) of the present invention.

The unsaturated organic acid-modified polyolefin as the component (B) of the present invention is, for example, a polyolefin obtained by modifying polyethylene, polypropylene, or a derivative thereof with an unsaturated organic acid, and particularly has a density of 0.941 to 0. 965
It is preferable that the high-density polyethylene of 1 is modified with an unsaturated organic acid. Examples of the unsaturated organic acid include fumaric acid, maleic acid, nadic acid, tetrahydrophthalic acid, methacrylic acid, acrylic acid and the like, or anhydrides thereof. If the density of the high-density polyethylene is lower than this range, the slidability improving effect may not be sufficient, and if it is higher than this range, molding shrinkage may increase and dimensional accuracy may deteriorate. The concentration of the unsaturated organic acid used for modification is 0. 1 in terms of the content in the obtained unsaturated organic acid-modified polyolefin.
The modification treatment method is preferably a solution reaction in the presence of a peroxide initiator or a reaction by kneading in melt extrusion.

When the amount of the unsaturated organic acid-modified polyolefin as the component (B) in the resin component is small, the effect of compounding the unsaturated organic acid-modified polyolefin cannot be sufficiently obtained.
If the amount is large, the dimensional accuracy may be deteriorated. Therefore, the mixing ratio of the component (B) in the resin component is set to 2 to 10% by weight.

The ultrahigh molecular weight polyethylene as the component (C) of the present invention has an intrinsic viscosity of 6 to 40 dl / measured in ISO 1628-3: 1991 (in decalin solution at 135 ° C.).
g of polyethylene, preferably 10 to 30 dl / g.

When the amount of the ultra high molecular weight polyethylene as the component (C) in the resin component is small, the effect of adding the ultra high molecular weight polyethylene cannot be sufficiently obtained, and when the amount is large, the fluidity is lowered and the mixing with the polyamide is made. Since the moldability is deteriorated due to poor affinity, the blending ratio of the component (C) in the resin component is 2 to 10% by weight.

The resin component according to the present invention contains the unsaturated organic acid-modified polyolefin of the component (B) and the ultrahigh molecular weight polyethylene of the component (C) in the above blending ratio, and the balance is substantially (A). ) Component, but in the resin component, an inorganic filler such as talc, silica or mica is added to the component (A) in an amount of 0. About 5-5% by weight, (A)
Different from the component (A), a crystalline thermoplastic resin having a melting point of 10 ° C or higher, preferably 15 ° C or higher as compared with the component (A), preferably a polyamide (for example, polyamide 66) is contained in an amount of 1 to 15% by weight based on the component (A). It is good to mix it to some extent.

The blending ratio of the unsaturated organic acid-modified polyolefin of the component (B) and the ultrahigh molecular weight polyethylene of the component (C) in the resin component is such that the effects of blending these recomponents can be sufficiently obtained. , (B) unsaturated organic acid-modified polyolefin: (C) component ultrahigh molecular weight polyethylene = 1: 0.5 to 10 (weight ratio), and the total mixing ratio of these is 4 to 20. It is preferably in the weight%.

The glass fiber of the component (D) of the present invention is not particularly limited as long as it is generally used for resin reinforcement, but normally chopped strands having a length of about 3 mm are used.

In order to produce a resin gear having excellent long-term strength, the average residual fiber length in the resin gear (measuring method will be described later) is preferably 80 to 1000 μm.
It is particularly preferable that the thickness is 0 to 500 μm. If the average residual fiber length of the glass fiber is less than 80 μm, the long-term strength of the obtained gear cannot be realized, and if it exceeds 1000 μm, the dimensional accuracy of the gear is deteriorated due to the protrusion of the glass fiber on the surface of the molded product. In order to make the average residual fiber length of the gear within the above range, the area of the cross section of the glass fiber in the longitudinal direction is 7 × 10.
^It is preferably ^{−5 to} 5 × 10 ⁻⁴ mm ² .

The shape of the glass fiber of the component (D) in a cross section perpendicular to the fiber length direction may be circular, but a non-circular shape having a ratio of major axis to minor axis of about 1.5 to 6: 1, For example, a non-circular cross-sectional shape such as an ellipse, an ellipse, or a cocoon shape is preferable. With such a glass fiber having a non-circular cross section, the specific surface area becomes larger than that of the glass fiber having a circular cross section, the adhesion between the fiber and the resin is improved, the reinforcing effect is enhanced, and the long-term strength of the resulting gear is improved. Be improved.

The compounding ratio of the glass fiber as the component (D) is 40 to 2 with respect to 100 parts by weight of the resin component.
50 parts by weight. If the amount of glass fiber is less than this range, a sufficient reinforcing effect cannot be obtained, and if the amount of glass fiber is more than this range, moldability is impaired. The preferable blending amount of glass fiber is the resin component 1 described above.
It is 60 to 200 parts by weight with respect to 00 parts by weight.

The method for preparing the resin composition which is the molding material in the present invention is not particularly limited, and includes, for example, (A) to
It is possible to employ a method in which a predetermined amount of the component (D) is sufficiently mixed, this is kneaded by an extruder, extruded in a strand shape, and pelletized by a strand cutter.
In this case, the glass fiber of the component (D) is preferably supplied by a method such as side feeding from the middle of the extruder in order to secure the average residual fiber length of the gear.

The resin composition according to the present invention may contain, if necessary, a styrene resin, a polycarbonate resin,
Polyester resins such as polybutylene terephthalate and polyethylene terephthalate, nylon 46, 11, 1
Thermoplastic resins such as polyamide resins such as 2, 6, 6 / 6T and 6 / 6I, polyphenylene sulfide resins, polysulfones, polyether sulfones, polyphenylene ethers and polyether ether ketones; carbon fibers, silica fibers, silica. Inorganic fibrous reinforcing materials such as alumina fibers, potassium titanate fibers, aluminum borate fibers, stainless fibers, aluminum fibers; organic fibrous reinforcing materials such as aramid fibers, polyimide fibers, fluororesin fibers; talc, calcium carbonate, mica, glass Inorganic fillers such as beads, glass powder and glass balloons; solid lubricants such as fluororesin powder, graphite and molybdenum disulfide; plasticizers such as paraffin oil; antioxidants; heat stabilizers; light stabilizers; UV absorbers Neutralizer; Lubricant; Compatibilizer; Antifogging agent; Antiblock Ing agent; slip agents; dispersing agents; coloring agents; antibacterial agent; can be added various additives such as fluorescent whitening agent.

The method of molding the resin gear according to the present invention includes:
Examples of the method include an extrusion molding method, an injection molding method, and an injection compression molding method. Among them, the injection molding method is preferable in terms of cost.

[0031]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

The molding materials used in the following examples and comparative examples
The specifications of each component used as are as follows. (A) component Polyamide: "Renny 6002" manufactured by Mitsubishi Engineering Plastics (B) component Maleic anhydride modified high density polyethylene: Density 0.94
5 g / cm^ThreeOf high density polyethylene with maleic anhydride
Maleic anhydride concentration obtained by melt reaction in an extruder
Modified poly with 0.8% by weight and MFR 0.8g / 10min
ethylene (C) component Ultra high molecular weight polyethylene: Intrinsic viscosity 14 dl / g, density
0.94 g / cm^Three (D) ingredient Glass fiber A: "CSH3PA-870" manufactured by Nitto Boseki Co., Ltd.
S " Cocoon type cross section Cross-sectional area: 1.8 × 10^-4mm^Two Major axis: about 20 μm, minor axis: about 10 μm Ratio of major axis / minor axis: about 2 Glass fiber B: "ECS03T-28" manufactured by Nippon Electric Glass Co., Ltd.
9K " Circular cross section Cross-sectional area: 1.3 × 10^-4mm^Two Fiber diameter: 13 μm Ratio of major axis / minor axis: 1

Examples 1 to 3 and Comparative Examples 1 to 5 Components (A) to (C) shown in Table 1 were blended in advance and melt-kneaded with a twin-screw extruder. It was charged from a feeder to obtain a pellet-shaped resin composition. The kneading temperature was 260 ° C.

An injection molding machine (“All Rounder 750-210-32” manufactured by Arburg Co., Ltd. was used to form the obtained resin pellets.
(0D ″) was injection-molded from three points having a diameter of 1 mm, and the following gear for evaluation was molded at a cylinder temperature of 260 ° C., a mold temperature of 120 ° C. and a holding pressure of 40% for 3 seconds. [Evaluation gear] Gear shape: Spur gear tooth outer diameter: 42 mm Number of teeth: 40 modules Module: 1 Pressure angle: 20 ° Twist angle: 0 ° Pitch: Circle diameter Tooth width: 5 mm

The gears for evaluation thus obtained were subjected to the following characteristic evaluation test, and the results are shown in Table 1. [Gear long-term strength test] The evaluation gear is fixed to the driving side, the mating gear is fixed to the driven side, and the driven side is rotated at 200 rpm.
A load torque of 30 kg · cm was applied to the driven side, and the number of times of meshing until the evaluation gear was broken was measured. As the mating gear, the material is metal, the shape is spur gear, the number of teeth is 40,
Module 1 having a pressure angle of 20 °, a twist angle of 0 °, a pitch circle diameter, and a tooth width of 10 mm was used. [Average Remaining Fiber Length] About 1 g of a test piece was cut out from the gear for evaluation, heated in a high-frequency electric furnace at 700 ° C. for 15 minutes to be incinerated, and an optical micrograph was taken to measure 200 fibers. , And calculated the average value.

[0036]

[Table 1]

From Table 1, a polyamide obtained by polymerizing a diamine mainly containing metaxylylenediamine and a dicarboxylic acid mainly containing α, ω-aliphatic dicarboxylic acid, an unsaturated organic acid-modified polyolefin, and an ultrahigh molecular weight It is apparent that the resin gear of the present invention obtained by molding a resin composition containing polyethylene and glass fibers exhibits good long-term strength.

[0038]

As described in detail above, according to the present invention, there is provided a resin gear which is excellent in shape and dimensional accuracy and stability thereof, and which has high strength and long-term strength. The resin gear of the present invention has excellent mechanical properties and dimensional stability, and therefore, in electrical equipment, automobiles, and other general equipment,
It is extremely useful as a resin gear that requires strength, dimensional accuracy, and durability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 23:26 C08L 23:06 23:06) (72) Inventor Shoichi Ikeda Shiba 5-chome, Minato-ku, Tokyo No. 31-19 No. 19 in Yuka Electronics Co., Ltd. In-house (72) Inventor Hiroki Nakahama No. 31-19, Shiba, Minato-ku, Tokyo F-Term in No. 31 Yuka Electronics Co., Ltd. (reference) 3J030 BC01 BC08 4J002 BB033 BB202 BB212 CL031 DL006 FA046 FD016 GM00 GM04

Claims (3)

[Claims] 1. A polymer obtained by polymerizing (A) a diamine containing 70 mol% or more of metaxylylenediamine and a carboxylic acid containing 70 mol% or more of an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms. 80 to 96% by weight of polyamide, and (B) 2 to 10% by weight of unsaturated organic acid-modified polyolefin
And (C) 100 parts by weight of a resin component containing 2 to 10% by weight of ultrahigh molecular weight polyethylene, (D) 40 to 250 parts by weight of glass fiber is mixed to obtain a resin composition, and the obtained resin composition is molded. Resin gear. 2. The resin gear according to claim 1, wherein the average residual fiber length of the glass fiber (D) is 80 to 1000 μm. 3. The glass fiber (D) according to claim 1 or 2, wherein the ratio of the major axis to the minor axis in the cross section perpendicular to the longitudinal direction is 1.5 to 6: 1. Resin gear.