Resin gear

Abstract

This resin gear has a tooth part comprising a resin molded body; the resin molded body contains a fiber base material and a resin component; and the fiber base material contains an aramid fiber in which the content of para-aramid fiber is 80-100 mass%.

Description

Resin Gear

[0001] The present invention relates to a resin gear.

[0002] Resin molded articles made of a fiber substrate and a matrix resin are used in various fields due to their light weight and excellent mechanical properties. For example, resin gears formed from resin molded articles are lighter and quieter than metal gears, and are therefore used as parts for machine tools, industrial machinery, automobile engines, drive units for electric motorcycles, and the like (see, for example, Patent Document 1 below).

[0003] Japanese Patent Application Publication No. 11-227061

[0004] Meanwhile, resin gears used in automobile engines, drive units for electric motorcycles, etc., tend to have larger loads on their teeth due to gear compaction, replacement of metal gears, etc. Therefore, there is a demand for durable resin gears that can achieve a long life even in high-load durability tests.

[0005] Therefore, an object of the present invention is to provide a resin gear that is excellent in durability.

[0006] One aspect of the present invention relates to the following inventions [1] to [5].

[0007] [1] A resin gear having teeth made of a resin molded body, the resin molded body including a fiber substrate and a resin component, the fiber substrate including aramid fibers with a para-aramid fiber content of 80 to 100% by mass. [2] The resin gear according to [1], wherein the resin component is a cured product of a thermosetting resin composition impregnated into the fiber substrate, the thermosetting resin composition including (A) a bis(2-oxazoline) compound and (B) an aromatic diamine compound. [3] The resin gear according to [2], wherein the thermosetting resin composition further includes (C) an organic cyclic compound (excluding carboxylic acid compounds) having at least one polar functional group selected from the group consisting of a hydroxyl group, an amide group, and a carbonyl group, and at least one cyclic structure selected from the group consisting of an alicyclic ring and an aromatic ring. [4] The resin gear according to [3], wherein the content of the organic cyclic compound is 5 to 95 parts by mass when the total mass of the aromatic diamine compound and the organic cyclic compound is 100 parts by mass. [5] The resin gear according to [3] or [4], wherein the organic cyclic compound is 1-(2-hydroxyethyl)-2-pyrrolidone or N-(2,4,6-trichlorophenyl)maleimide.

[0008] According to the present invention, a resin gear having excellent durability can be provided.

[0009] FIG. 10 is a diagram showing the results of a motoring durability test of a resin gear.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"). The present invention is not limited to the following embodiment.

[0011] <Resin Gear> The resin gear of the present embodiment has teeth made of a resin molded body, and the resin molded body includes a fiber base material and a resin component.

[0012] [Fiber substrate] Examples of the fiber substrate include thermoplastic resin fibers such as polyphenylene sulfide, polyamide (aliphatic polyamide, aromatic polyamide), polyethylene, and polypropylene, inorganic fibers such as basalt fiber, alumina fiber, glass fiber, and carbon fiber, and metal fibers such as stainless steel fiber and aluminum fiber. The fiber substrate may contain one type of fiber alone or two or more types of fibers in combination.

[0013] In the resin gear of the present embodiment, from the viewpoint of durability, the fiber base material contains aramid fibers with a para-aramid fiber content of 80 to 100 mass %.

[0014] As the para-aramid fiber, fibers having molecular structures represented by the following formulas (1) and (2) can be used.

[0015] As the para-aramid fiber, commercially available products such as "Twaron" and "Technora" (both trade names of Teijin Limited), "Kevlar Pulp" (trade name of Toray DuPont Co., Ltd.), "Taparan" (trade name of Yantai Taiho New Materials Co., Ltd.), and "Heraklon" (trade name of Kolon Industry Co., Ltd.) can be used.

[0016] The aramid fibers may contain meta-aramid fibers (meta-aramid fibers) in addition to para-aramid fibers (para-aramid fibers).

[0017] The meta-aramid fiber may be a fiber having a molecular structure represented by the following formula (3):

[0018] As the meta-aramid fiber, commercially available products such as "Conex" (trade name, manufactured by Teijin Limited), "Nomex" (trade name, manufactured by DuPont Co., Ltd.), "Newstar" (trade name, manufactured by Yantai Taiho New Materials Co., Ltd.), and "Tametal" (trade name, manufactured by Yantai Taiho New Materials Co., Ltd.) can be used.

[0019] The content of the para-aramid fibers in the aramid fibers may be 85 to 100% by mass, or may be 85 to 90% by mass, based on the total amount of the aramid fibers, from the viewpoint of improving the tensile strength of the resin molded body and obtaining a higher level of durability.

[0020] The content of the aramid fibers in the fiber substrate may be 50 to 100 mass %, 60 to 100 mass %, or 100 mass %, based on the total mass of the fiber substrate.

[0021] From the viewpoint of availability, the fiber length of the aramid fiber may be 1 to 12 mm, 1 to 2 mm, 3 to 6 mm, or 7 to 12 mm.

[0022] The fiber diameter of the aramid fiber may be 8 to 12 μm from the viewpoints of availability and permeability of the resin into the substrate.

[0023] The fibrous substrate may contain an inorganic sliding material, such as carbon, molybdenum, molybdenum disulfide, potassium hexatitanate, potassium octatitanate, lithium potassium titanate, magnesium potassium titanate, and mica.

[0024] From the viewpoint of mechanical strength, the content of the inorganic sliding material in the resin molded body may be 10 parts by mass or less, or 5 parts by mass or less, per 100 parts by mass of the fiber base material, or the resin molded body may not contain an inorganic sliding material.

[0025] The proportion of the fiber base material in the resin molded body may be 35 to 55% by volume, 35 to 50% by volume, or 50 to 55% by volume, from the viewpoint of ensuring mechanical strength and the resin impregnation rate.

[0026] Furthermore, from the viewpoint of facilitating impregnation of the molten resin into the substrate, the content of the fiber substrate in the resin molded body may be 35 to 50 parts by mass or 40 to 50 parts by mass per 100 parts by mass of the total of the fiber substrate and the cured product of the thermosetting resin composition of this embodiment.

[0027] [Resin Component] Examples of the resin component include polyamide resin, polyaminoamide resin, epoxy resin, phenolic resin, melamine resin, urea resin, polyimide resin, polyester resin, etc. In the resin gear of the present embodiment, the resin component may be a cured product of a thermosetting resin composition impregnated into a fiber substrate.

[0028] The thermosetting resin composition may contain (A) a bis(2-oxazoline) compound (hereinafter, also referred to as "component (A)") and (B) an aromatic diamine compound (hereinafter, also referred to as "component (B)").

[0029] [Component (A)] The bis(2-oxazoline) compound can be any compound having two oxazoline skeletons in one molecule without any particular limitation. The two oxazoline skeletons may be bonded directly or via an organic group. Component (A) may be used alone or in combination of two or more.

[0030] The bis(2-oxazoline) compound may be a compound represented by the following general formula (A). [In formula (A), R １ represents a single bond, an unsubstituted or substituted alkylene group, an unsubstituted or substituted phenylene group, or an unsubstituted or substituted pyridinediyl group; R ２ and R ３ each independently represents a hydrogen atom, an alkyl group, or a phenyl group.

[0031] R １ When has a substituent, examples of the substituent include a methyl group.

[0032] Examples of component (A) include 2,2'-(1,3-phenylene)bis-2-oxazoline (hereinafter sometimes abbreviated as "PBO"), 2,2'-(1,4-phenylene)bis-2-oxazoline, 2,2'-(1,2-ethylene)bis-2-oxazoline, 2,2'-(1,4-butylene)bis-2-oxazoline, and 2,2'-(1,3-phenylene)bis-(5-methyl-2-oxazoline), (S,S)-2,6-bis(4-isopropyl-2-oxazolin-2-yl)pyridine, and (S,S)-2,2'-(dimethylmethylene)bis(4-phenyl-2-oxazoline).

[0033] Component (A) may be PBO because it is inexpensive and readily available.

[0034] The content of component (A) in the thermosetting resin composition may be 25 to 75 mass % based on the total solid content of the thermosetting resin composition. The solid content of the thermosetting resin composition means components other than the solvent (components that form a cured product).

[0035] [Component (B)] Examples of aromatic diamine compounds include 4,4'-diaminodiphenylmethane (MDA), 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), methylenebis(2-ethyl-6-methylaniline), and 4,4'-methylenebis(2-ethylaniline). Component (B) may be used alone or in combination of two or more.

[0036] The aromatic diamine compound may be an aromatic diamine compound containing a halogen atom such as a chlorine atom or a bromine atom in the molecule.

[0037] The molecular weight of the aromatic diamine compound may be 150 or more or 300 or more from the viewpoint of being less volatile, and may be 350 or less from the viewpoint of the impregnation of the thermosetting resin composition into a fiber substrate or the like and ease of use in a liquid state.

[0038] From the viewpoint of improving the mechanical strength of a resin molded product, the content of the component (B) in the thermosetting resin composition may be 0.03 to 1.0 mol, 0.03 to 0.15 mol, 0.2 to 0.8 mol, or 0.8 to 1.0 mol per 1 mol of the component (A).

[0039] [Component (C)] In order to achieve even higher levels of durability, the thermosetting resin composition may further contain, in addition to the components (A) and (B) above, (C) an organic cyclic compound (excluding carboxylic acid compounds) (hereinafter sometimes referred to as "component (C)") having at least one polar functional group selected from the group consisting of a hydroxyl group, an amide group, and a carbonyl group, and at least one cyclic structure selected from the group consisting of an alicyclic ring, a heterocyclic ring, and an aromatic ring. The carboxylic acid compound also includes an acid anhydride compound. The component (C) may be blended alone or in combination of two or more.

[0040] The component (C) may be a compound represented by the following general formulas (C1) to (C4).

[0041] [In formula (C1), R １１ represents a hydrogen atom or an acetyl group.

[0042] [In formula (C2), R ２１ represents a vinyl group or an alkyl group having a hydroxyl group.

[0043] [In formula (C3), Ar ３１ represents an unsubstituted or substituted aromatic group.

[0044] [In formula (C4), Ar ４１ represents an aromatic group having a halogen atom.

[0045] Component (C) may be a compound that satisfies one or more of the following conditions: (a) It has two or more polar functional groups selected from the group consisting of a hydroxyl group, an amide group, and a carbonyl group, and (b) It has a chloro group.

[0046] The thermosetting resin composition may contain, as component (C), at least one compound selected from the group consisting of 2-oxazolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, phthalamide, and N-(2,4,6-trichlorophenyl)maleimide, or may contain at least one compound selected from the group consisting of 1-(2-hydroxyethyl)-2-pyrrolidone and N-(2,4,6-trichlorophenyl)maleimide.

[0047] From the viewpoint of further improving the durability of the resin gear, the content of the component (C) in the thermosetting resin composition may be 0.05 to 2.0 mol, 0.05 to 0.5 mol, 0.5 to 1.0 mol, or 1.0 to 2.0 mol per 1 mol of the component (A). From the same viewpoint, the total content of the components (B) and (C) in the thermosetting resin composition may be 0.5 to 2.0 mol, 0.5 to 0.8 mol, 0.8 to 1.0 mol, or 1.0 to 2.0 mol per 1 mol of the component (A).

[0048] From the viewpoint of further improving the durability of the resin gear, the content of the component (C) in the thermosetting resin composition may be 5 to 95 parts by mass, 5 to 60 parts by mass, 5 to 30 parts by mass, 30 to 50 parts by mass, or 50 to 60 parts by mass, where the total mass of the components (B) and (C) is 100 parts by mass.

[0049] The thermosetting resin composition of the present embodiment may contain a curing accelerator, if necessary, to accelerate the curing reaction between the bis(2-oxazoline) compound and the components (B) and (C).

[0050] Examples of the curing accelerator include n-octylbromide and p-toluenesulfonic acid esters such as ethyl p-toluenesulfonate.

[0051] The content of the curing accelerator in the thermosetting resin composition may be 0.3 to 5.0 parts by mass, 0.3 to 1.0 part by mass, or 1.0 to 5.0 parts by mass, relative to 100 parts by mass of the total of the bis(2-oxazoline) compound, component (B), and component (C).

[0052] The thermosetting resin composition may contain additives such as shock absorbing materials such as rubber, organic sliding materials such as polyethylene glycol, etc. Examples of shock absorbing materials include silicone rubber, fluororubber, and nitrile rubber.

[0053] The resin molded article can be produced by impregnating a fiber substrate with the above-mentioned thermosetting resin composition, and then curing the thermosetting resin composition by heating.

[0054] In this embodiment, the fiber base material may be formed by a wet method in which paper is made in water.

[0055] The curing conditions for the thermosetting resin composition include, for example, 160° C. to 250° C. for 3 to 20 minutes.

[0056] The resin gear of this embodiment has teeth made of a resin molded body. The teeth may be formed, for example, by using a teeth-shaped mold during the curing step of the thermosetting resin composition described above, or by cutting or the like after obtaining a resin molded body of a predetermined shape by the method described above.

[0057] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0058] The following compounds were prepared as raw materials for preparing the thermosetting resin composition.

[0059] <Component (A)> PBO: 2,2'-(1,3-phenylene)-bis-2-oxazoline (manufactured by Mikuni Pharmaceutical Co., Ltd.)

[0060] <Component (B)> MDA: 4,4'-diaminodiphenylmethane (manufactured by Wanka Chemical Japan Co., Ltd.)

[0061] <Component (C)> HEPL: 1-(2-hydroxyethyl)-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) T1987: N-(2,4,6-trichlorophenyl)maleimide (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0062] <Curing accelerator> OB: n-octyl bromide (manufactured by Manac Corporation)

[0063] Example 1: PBO as component (A) and MDA as component (B) were mixed in a mass ratio of 69:31 and heated to dissolve to form a liquid. OB as a curing accelerator was blended into this liquid in a ratio of 0.9 parts by mass per 100 parts by mass of the total amount of components (A) and (B) to obtain a thermosetting resin composition.

[0064] A fiber substrate was prepared by dissociating cut fibers (fiber length 3 mm) of para-aramid fiber (manufactured by Teijin Limited, trade name Technora), cut fibers (fiber length 3 mm) of meta-aramid fiber (manufactured by Teijin Limited, trade name Conex), and para-aramid fiber pulp (manufactured by Toray DuPont Co., Ltd., trade name Kevlar) in water in a mass ratio of 85:10:5 and forming into a paper. This fiber substrate was compressed in the thickness direction in a papermaking mold so that the proportion of the fiber substrate in the resin molded body (hereinafter sometimes referred to as the "fiber substrate volume ratio") was 45 volume %, and a cylindrical reinforcing fiber assembly was obtained.

[0065] The cylindrical reinforcing fiber assembly obtained above was placed in a molding die and clamped, and the thermosetting resin composition prepared above was further injected and cured at a molding die temperature of 190° C. for 4 minutes to form a disk (resin molded product). Teeth were then formed on the molded disk by cutting, and this was made into a resin gear.

[0066] Example 2: PBO (component A), MDA (component B), and HEPL (component C) were mixed in a mass ratio of 69:25:6 and heated to dissolve to form a liquid. OB (curing accelerator) was added to this liquid in a ratio of 0.7 parts by mass per 100 parts by mass of the total of components A, B, and C to obtain a thermosetting resin composition. A resin gear was molded using this thermosetting resin composition in the same manner as in Example 1, except that the molding die temperature was set to 180°C.

[0067] Example 3: PBO (component A), MDA (component B), and T1987 (component C) were mixed in a mass ratio of 69:25:6 and heated to dissolve to form a liquid. OB (curing accelerator) was added to this liquid in an amount of 0.9 parts by mass per 100 parts by mass of the total of components A, B, and C to obtain a thermosetting resin composition. A resin gear was molded in the same manner as in Example 1, except that this thermosetting resin composition was used.

[0068] Example 4: PBO as component (A) and MDA as component (B) were mixed in a mass ratio of 73:27 and heated to dissolve to form a liquid. OB as a curing accelerator was blended into this liquid in a ratio of 0.9 parts by mass per 100 parts by mass of the total of components (A) and (B) to obtain a thermosetting resin composition. A resin gear was molded in the same manner as in Example 1, except that this thermosetting resin composition was used.

[0069] Comparative Example 1 A resin gear was molded in the same manner as in Example 1, except that cut fibers (fiber length 3 mm) of para-aramid fiber (manufactured by Teijin Limited, trade name Technora), cut fibers (fiber length 3 mm) of meta-aramid fiber (manufactured by Teijin Limited, trade name Conex), and para-aramid fiber pulp (manufactured by Toray DuPont Co., Ltd., trade name Kevlar) were used in a mass ratio of 30:65:5.

[0070] Comparative Example 2 A resin gear was molded in the same manner as in Example 1, except that cut fibers (fiber length 3 mm) of para-aramid fiber (manufactured by Teijin Limited, trade name Technora), cut fibers (fiber length 3 mm) of meta-aramid fiber (manufactured by Teijin Limited, trade name Conex), and para-aramid fiber pulp (manufactured by Toray DuPont Co., Ltd., trade name Kevlar) were used in a mass ratio of 53:42:5, and the volume fraction of the fiber base material was changed to 40% by volume.

[0071] <Motoring durability test> The resin gears obtained in the examples and comparative examples were continuously rotated under the test conditions shown below, and the time until the resin gears broke was measured. The test was also performed with the following tooth root stress. [Test conditions] Lubricant: Grease Test temperature: Room temperature Rotational speed (rpm): 250 Tooth root stress (MPa): 330-340

[0072]

[0073] FIG. 1 shows the relationship between the total number of rotations (cycles) until the resin gears of Examples 1 to 4 and Comparative Examples 1 and 2 were broken when the motoring durability test was performed, and the tooth root stress (MPa).

[0074] 1 , it was confirmed that the resin gear of Example 1, which contains aramid fibers with a para-aramid fiber content of 90% by mass as a fiber material, has higher durability not only under high load but also under low load, compared to the resin gear of Comparative Example 1, which contains aramid fibers with a para-aramid fiber content of 35% by mass. The resin gear according to the present invention can extend the durability life under both low load and high load conditions.

Claims

1. A resin gear having a tooth portion made of a resin molded body, The resin molded body includes a fiber base material and a resin component, The resin gear, wherein the fiber base material contains aramid fibers having a para-aramid fiber content of 80 to 100 mass %.

2. the resin component is a cured product of a thermosetting resin composition impregnated into the fiber substrate, 2. The resin gear according to claim 1, wherein the thermosetting resin composition contains (A) a bis(2-oxazoline) compound and (B) an aromatic diamine compound.

3. 3. The resin gear according to claim 2, wherein the thermosetting resin composition further contains (C) an organic cyclic compound (excluding carboxylic acid compounds) having at least one polar functional group selected from the group consisting of a hydroxyl group, an amide group, and a carbonyl group, and at least one cyclic structure selected from the group consisting of an alicyclic ring and an aromatic ring.

4. 4. The resin gear according to claim 3, wherein the content of the organic cyclic compound is 5 to 95 parts by mass when the total mass of the aromatic diamine compound and the organic cyclic compound is 100 parts by mass.

5. 5. The resin gear according to claim 3, wherein the organic cyclic compound is 1-(2-hydroxyethyl)-2-pyrrolidone or N-(2,4,6-trichlorophenyl)maleimide.

6. A resin gear as described in claim 1, wherein the content of the para-aramid fiber in the aramid fiber is 85 to 100 mass%.

7. A resin gear as described in claim 2, wherein the content of the (B) aromatic diamine compound in the thermosetting resin composition is 0.03 to 1.0 mole per 1 mole of the (A) bis(2-oxazoline) compound.