WO2020071495A1 - Liquid crystalline resin composition for ball bearing anti-sliding-abrasion member, and ball bearing anti-sliding-abrasion member using same - Google Patents

Abstract

Provided are: a liquid crystalline resin composition for a ball bearing anti-sliding-abrasion member, the composition being used to manufacture a ball bearing anti-sliding-abrasion member which has excellent surface whitening suppression, low warpage properties, weld strength, and low dust generation in a good balance, and whereby sliding abrasiveness of a ball bearing is reduced; and a ball bearing anti-sliding-abrasion member which uses the liquid crystalline resin composition. The liquid crystalline resin composition for a ball bearing anti-sliding-abrasion member pertaining to the present invention contains a liquid crystalline resin (A), a particulate filler (B), and a platy filler (C), the median diameter of the particulate filler (B) being 1.3-5.0 µm, the content of the particulate filler (B) being 7.5-22.5% by mass, the content of the platy filler (C) being 2.5-27.5% by mass, and the total content of the particulate filler (B) and the platy filler (C) being 22.5-37.5% by mass.

Description

Liquid crystalline resin composition for ball bearing sliding wear member and ball bearing sliding member using the same

The present invention relates to a liquid crystal resin composition for ball bearing sliding and wear resistant members and a ball bearing sliding and wear resistant member using the same.

Liquid crystalline resins represented by liquid crystalline polyester resins have excellent mechanical strength, heat resistance, chemical resistance, electrical properties, etc. in a well-balanced manner, and also have excellent dimensional stability, so they are widely used as high-performance engineering plastics. It's being used. Recently, liquid crystal resins have been used for precision equipment parts by taking advantage of these features.

部品 Examples of components using liquid crystal resin include connectors such as FPC connectors; sockets such as memory card sockets; camera module components such as lens holders; and relays. These parts are required to have excellent surface whitening suppression, low warpage, weld strength, and low dust generation, and may be used in a form in which two or more members come into dynamic contact. Therefore, it is also required that the sliding wear property (that is, the easiness of wear when two or more members are in dynamic contact) is reduced. For example, Patent Literature 1 aims to provide a molded article made of a liquid crystalline resin composition having excellent surface appearance and excellent slidability, and aims to provide a liquid crystalline resin and talc having a specific volume average particle diameter. Is disclosed in a specific ratio.

Among the above-mentioned components, in the case of a component used in a form in which a molded body made of a liquid crystalline resin composition and a ball bearing are in dynamic contact with each other, in particular, the ball bearing sliding wear property (that is, the ball bearing It is required that the wear during dynamic contact) be reduced. Note that Patent Document 2 describes a camera module component used in a form in which it is in dynamic contact with a ball bearing.

Japanese Patent No. 5087958 European Patent No. 2938063

However, according to the study of the present inventors, the conventional liquid crystalline resin composition does not sufficiently reduce the ball bearing sliding wear. The present invention has been made in order to solve the above-mentioned problems, and its object is to provide a good balance of surface whitening suppression, low warpage, weld strength, and low dust generation, and ball bearing sliding wear. It is an object of the present invention to provide a liquid crystal resin composition for a ball-bearing sliding wear member used for producing a ball-bearing sliding-wear member having reduced resistance, and a ball bearing sliding-wear member using the same.

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, it contains a liquid crystalline resin, a granular filler having a specific median diameter and a plate-like filler, and the content of each of the granular filler, the plate-like filler, and the sum of these is within a predetermined range. It has been found that the above problem can be solved by using a liquid crystal resin composition, and the present invention has been completed. More specifically, the present invention provides the following.

(1) (A) It contains a liquid crystalline resin, (B) a granular filler, and (C) a plate-like filler, and the median diameter of the (B) granular filler is 1.3 to 5.0 μm. The content of the (B) particulate filler is 7.5 to 22.5% by mass, the content of the (C) plate-like filler is 2.5 to 27.5% by mass, A liquid crystal resin composition for a ball-bearing sliding wear member, wherein the total content of the (B) granular filler and the (C) plate-like filler is 22.5 to 37.5% by mass.

{(2)} The composition according to (1), wherein the (B) granular filler is silica, and the (C) plate-like filler is talc.

(3) The composition according to (1) or (2), further comprising (D) an epoxy group-containing copolymer, wherein the content of the (D) epoxy group-containing copolymer is from 1 to 5 A composition which is% by weight.

{(4)} A ball bearing-resistant sliding wear member comprising the composition according to any one of (1) to (3).

If a ball bearing sliding wear member is manufactured using the liquid crystalline resin composition for a ball bearing sliding wear member of the present invention as a raw material, the balance between surface whitening suppression, low warpage, weld strength, and low dust generation can be achieved. It is possible to obtain a ball bearing sliding wear member that is excellent and excellent in ball bearing sliding wear resistance.

FIG. 1 is a diagram for explaining a method of evaluating the amount of sliding wear. FIG. 2A is a diagram showing a camera module type molded product used for warpage deformation evaluation, and FIG. 2B is a diagram showing measurement points in the warpage deformation evaluation. The unit of the numerical value in the figure is mm. FIG. 3 is a diagram showing a molded product used in the evaluation of weld strength. The unit of the numerical value in the figure is mm.

Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments.

<Liquid crystalline resin composition for ball bearing sliding wear member>
The liquid crystalline resin composition for a ball bearing sliding wear member of the present invention contains (A) a liquid crystalline resin, (B) a particulate filler, and (C) a plate-like filler.

[(A) Liquid crystalline resin]
The liquid crystalline resin (A) used in the present invention refers to a melt-processable polymer having a property capable of forming an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing the molten sample placed on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere. When the liquid crystalline polymer applicable to the present invention is inspected between orthogonal polarizers, polarized light is normally transmitted even when it is in a molten stationary state, and exhibits optical anisotropy.

The type of the liquid crystalline resin (A) is not particularly limited, and is preferably an aromatic polyester and / or an aromatic polyesteramide. Further, a polyester partially containing an aromatic polyester and / or an aromatic polyesteramide in the same molecular chain is also included in the range. (A) The liquid crystalline resin is preferably at least about 2.0 dl / g, more preferably 2.0 to 10.0 dl / g, when dissolved in pentafluorophenol at a concentration of 0.1% by mass at 60 ° C. Those having a logarithmic viscosity (IV) are preferably used.

The aromatic polyester or aromatic polyester amide (A) as the liquid crystalline resin applicable to the present invention is particularly preferably at least one selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. An aromatic polyester or an aromatic polyesteramide having a repeating unit derived from a certain compound as a constituent component.

More specifically,
(1) a polyester mainly composed of a repeating unit derived from one or more aromatic hydroxycarboxylic acids and derivatives thereof;
(2) a repeating unit mainly derived from (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one type of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof Or a polyester comprising a repeating unit derived from two or more kinds;
(3) Mainly (a) a repeating unit derived from one or more of aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof Or a polyester composed of (c) a repeating unit derived from at least one or more of aromatic diols, alicyclic diols, aliphatic diols, and derivatives thereof;
(4) repeating units mainly derived from (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or two aromatic hydroxyamines, aromatic diamines and derivatives thereof. A polyester amide comprising: a repeating unit derived from at least one species; and (c) a repeating unit derived from one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof;
(5) a repeating unit mainly derived from (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or two aromatic hydroxyamines, aromatic diamines and derivatives thereof. A repeating unit derived from one or more of (c) an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and a derivative thereof; and (d) an aromatic diol, an alicyclic ring. A polyester amide comprising a repeating unit derived from at least one kind or two or more kinds of aliphatic diols, aliphatic diols, and derivatives thereof. Further, a molecular weight modifier may be used in combination with the above constituents as necessary.

（Ｘ：アルキレン（Ｃ_１～Ｃ_４）、アルキリデン、－Ｏ－、－ＳＯ－、－ＳＯ_２－、－Ｓ－、及び－ＣＯ－より選ばれる基である）

（Ｙ：－（ＣＨ_２）_ｎ－（ｎ＝１～４）及び－Ｏ（ＣＨ_２）_ｎＯ－（ｎ＝１～４）より選ばれる基である。） Preferable examples of (A) a specific compound constituting the liquid crystal resin applicable to the present invention include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; 2,6-dihydroxy Aromatic diols such as naphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, a compound represented by the following general formula (I), and a compound represented by the following general formula (II) Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and compounds represented by the following general formula (III): p-aminophenol, p-aminophenol And aromatic amines such as phenylenediamine.

(X: a group selected from alkylene (C ₁ -C ₄ ), alkylidene, —O—, —SO—, —SO ₂ —, —S—, and —CO—)

(Y: a group selected from — (CH ₂ ) _n — (n = 1 to 4) and —O (CH ₂ ) _n O— (n = 1 to 4)

The liquid crystalline resin (A) used in the present invention can be prepared from the monomer compound (or a mixture of monomers) by a known method using a direct polymerization method or a transesterification method, and is usually a melt polymerization method. , A solution polymerization method, a slurry polymerization method, a solid phase polymerization method, or a combination of two or more of them, and a melt polymerization method or a combination of a melt polymerization method and a solid phase polymerization method is preferably used. The above-mentioned compounds having an ester-forming ability may be used as they are in the polymerization, or may be those obtained by modifying a precursor to a derivative having the ester-forming ability in a stage prior to the polymerization. In the polymerization, various catalysts can be used. Representative examples include potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, tris (2 (4, pentanedionato) cobalt (III) and the like, and organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine. The amount of the catalyst used is generally about 0.001 to 1% by weight, particularly preferably about 0.01 to 0.2% by weight, based on the total weight of the monomers. If necessary, the molecular weight of the polymer produced by these polymerization methods can be increased by a solid-phase polymerization method in which heating is performed under reduced pressure or in an inert gas.

The melt viscosity of (A) the liquid crystalline resin obtained by the above method is not particularly limited. Generally, those having a melt viscosity at a molding temperature of 3 Pa · s or more and 500 Pa · s or less at a shear rate of 1000 sec ⁻¹ can be used. However, a material having a very high viscosity is not preferable because the fluidity is extremely deteriorated. The liquid crystal resin (A) may be a mixture of two or more liquid crystal resins.

In the liquid crystal resin composition of the present invention, the content of the liquid crystal resin (A) is preferably 62.5 to 77.5% by mass or 61.5 to 72.5% by mass, more preferably 65 to 72.5% by mass. 75% by mass or 63.5 to 72.5% by mass. It is preferable that the content of the component (A) is within the above range in terms of fluidity, heat resistance, and the like.

[(B) Granular filler]
The component (B) is a granular filler, and the component (B) has a median diameter of 1.3 to 5.0 μm. When the median diameter is 1.3 μm or more, the weld strength of the molded body tends to increase. When the median diameter is 5.0 μm or less, the effect of suppressing the surface whitening of the molded product tends to increase. The median diameter is preferably 1.5 to 5.0 μm, and more preferably 1.5 to 4.0 μm. In this specification, the median diameter refers to a median value on a volume basis measured by a laser diffraction / scattering particle size distribution measuring method.

Examples of the particulate filler of the component (B) include silicates such as silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite; Metal oxides such as titanium oxide, zinc oxide and alumina; metal carbonates such as calcium carbonate and magnesium carbonate; metal sulfates such as calcium sulfate and barium sulfate; silicon carbide; silicon nitride; As the component (B), one type may be used alone, or two or more types may be used in combination. In the present invention, it is more preferable to use silica as the component (B) from the viewpoints of suppression of surface whitening of the molded article, low dust generation of the molded article, and weld strength of the molded article.

The content of the component (B) is 7.5 to 22.5% by mass in the liquid crystal composition of the present invention. When the content of the component (B) is 7.5% by mass or more, it is easy to obtain a molded product with reduced ball bearing sliding wear, and when it is 22.5% by mass or less, the surface whitening of the molded product is suppressed. The effect tends to be high. The preferred content of the component (B) is 10 to 20% by mass.

[(C) Plate-like filler]
The liquid crystalline resin composition according to the present invention contains a plate-like filler. The platy filler can be used alone or in combination of two or more.

に お い て In the liquid crystalline resin composition of the present invention, the content of the (C) plate-like filler is 2.5 to 27.5% by mass. When the content of the component (C) is 2.5% by mass or more, the molded product tends to have low warpage. When the content of the component (C) is 27.5% by mass or less, the effect of suppressing surface whitening of the molded article and the low dust generation property of the molded article are likely to be increased. The content of the component (C) is preferably 5 to 25% by mass.

板 Examples of the plate-like filler in the present invention include talc, mica, glass flake, various metal foils, and the like. Talc is preferred from the viewpoint of suppressing warpage of a molded article obtained from the liquid crystal resin composition without deteriorating the fluidity of the liquid crystal resin composition. The median diameter of the platy filler is not particularly limited, and a smaller one is desirable in consideration of the fluidity of the liquid crystalline resin composition. On the other hand, in order to reduce the warpage of the molded article obtained from the liquid crystalline resin composition, it is necessary to maintain a certain size. Specifically, the thickness is preferably 1 to 100 μm, more preferably 5 to 50 μm.

〔talc〕
As talc that can be used in the present invention, the total content of Fe ₂ O ₃ , Al ₂ O _3, and CaO is 2.5% by mass or less based on the total solid content of the talc, and Fe ₂ O ₃ and Al Preferably, the total content of ₂ O ₃ is more than 1.0% by mass and 2.0% by mass or less, and the content of CaO is less than 0.5% by mass. That is, talc that can be used in the present invention contains at least one of Fe ₂ O ₃ , Al ₂ O _3, and CaO, in addition to SiO ₂ and MgO, which are the main components, and each component has the above content range. May be contained.

In the talc, when the total content of Fe ₂ O ₃ , Al ₂ O _3, and CaO is 2.5% by mass or less, the moldability of the liquid crystal resin composition and the molding from the liquid crystal resin composition. The heat resistance of molded articles such as connectors is not easily deteriorated. Therefore, the total content of Fe ₂ O ₃ , Al ₂ O ₃ and CaO is preferably from 1.0% by mass to 2.0% by mass.

Of the talc, talc having a total content of Fe ₂ O ₃ and Al ₂ O ₃ of more than 1.0% by mass is easily available. In the talc, when the total content of Fe ₂ O ₃ and Al ₂ O ₃ is 2.0% by mass or less, moldability of the liquid crystalline resin composition and molding from the liquid crystalline resin composition are performed. The heat resistance of molded articles such as connectors is not easily deteriorated. Therefore, the total content of Fe ₂ O ₃ and Al ₂ O ₃ is preferably more than 1.0% by mass and 1.7% by mass or less.

In the talc, when the content of CaO is less than 0.5% by mass, the moldability of the liquid crystalline resin composition and the heat resistance of molded articles such as connectors molded from the liquid crystalline resin composition are reduced. Hard to deteriorate. Therefore, the content of CaO is preferably from 0.01% by mass to 0.4% by mass.

The talc median diameter in the present invention is preferably from 4.0 to 20.0 μm, and more preferably from 10 to 18 μm, from the viewpoint of preventing warpage of the molded article and maintaining the fluidity of the liquid crystalline resin composition. Is more preferred.

Further, the total content of the component (B) and the component (C) is 22.5 to 37.5% by mass, and preferably 25 to 35% by mass in the liquid crystalline resin composition of the present invention. . When the total content is 22.5% by mass or more, the molded product tends to have low warpage. When the total content is 37.5% by mass or less, the effect of suppressing surface whitening of the molded article and the low dust generation property of the molded article are likely to be increased.

[(D) Epoxy group-containing copolymer]
The liquid crystalline composition of the present invention may contain (D) an epoxy group-containing copolymer. (D) The epoxy group-containing copolymer can be used alone or in combination of two or more. The (D) epoxy group-containing copolymer is not particularly limited. For example, at least one selected from the group consisting of (D1) an epoxy group-containing olefin-based copolymer and (D2) an epoxy group-containing styrene-based copolymer. One type is mentioned. (D) The epoxy group-containing copolymer contributes to reducing the ball bearing sliding wear of the molded product obtained from the liquid crystalline resin composition of the present invention.

(D1) Examples of the epoxy group-containing olefin copolymer include a copolymer composed of a repeating unit derived from an α-olefin and a repeating unit derived from a glycidyl ester of an α, β-unsaturated acid. Can be

The α-olefin is not particularly limited, and includes, for example, ethylene, propylene, and butene. Among them, ethylene is preferably used. The glycidyl ester of an α, β-unsaturated acid is represented by the following general formula (IV). The glycidyl ester of an α, β-unsaturated acid is, for example, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, and particularly preferably glycidyl methacrylate.

(D1) In the epoxy group-containing olefin copolymer, the content of the repeating unit derived from α-olefin is 87 to 98% by mass, and the content of the repeating unit derived from glycidyl ester of α, β-unsaturated acid is contained. The amount is preferably from 13 to 2% by weight.

The epoxy group-containing olefin copolymer (D1) used in the present invention may be acrylonitrile, acrylic acid ester, methacrylic acid ester, α-methylstyrene, maleic anhydride as a third component in addition to the above two components within a range not to impair the present invention. A repeating unit derived from one or more olefinically unsaturated esters such as an acid may be contained in an amount of 0 to 48 parts by mass based on 100 parts by mass of the above two components.

エ ポ キ シ The epoxy group-containing olefin copolymer as the component (D1) of the present invention can be easily prepared by a usual radical polymerization method using a monomer and a radical polymerization catalyst corresponding to each component. More specifically, usually, an α-olefin and a glycidyl ester of an α, β-unsaturated acid are reacted at 500 to 4000 atm and 100 to 300 ° C. in the presence of a radical generator in the presence of an appropriate solvent or chain transfer agent. It can be produced by a method of copolymerizing under or in the absence. Further, it can also be produced by a method in which an α-olefin, a glycidyl ester of an α, β-unsaturated acid and a radical generator are mixed and melt-grafted in an extruder.

Examples of the epoxy group-containing styrene-based copolymer (D2) include a copolymer composed of a repeating unit derived from styrenes and a repeating unit derived from a glycidyl ester of an α, β-unsaturated acid. Can be The glycidyl ester of an α, β-unsaturated acid is the same as that described for the component (D1), and thus the description is omitted.

Styrenes include styrene, α-methylstyrene, brominated styrene, divinylbenzene and the like, and styrene is preferably used.

The (D2) epoxy group-containing styrenic copolymer used in the present invention is a multicomponent copolymer containing, as a third component, a repeating unit derived from one or more other vinyl monomers in addition to the above two components. There may be. Preferred as the third component are repeating units derived from one or more olefinic unsaturated esters such as acrylonitrile, acrylates, methacrylates, and maleic anhydride. An epoxy group-containing styrenic copolymer containing these repeating units in an amount of 40% by mass or less in the copolymer is preferable as the component (D2).

(D2) In the styrene-based copolymer containing an epoxy group, the content of the repeating unit derived from the glycidyl ester of α, β-unsaturated acid is 2 to 20% by mass, and the content of the repeating unit derived from styrenes is Is preferably from 80 to 98% by mass.

(D2) The epoxy group-containing styrenic copolymer can be prepared by a usual radical polymerization method using a monomer corresponding to each component and a radical polymerization catalyst. More specifically, styrenes and a glycidyl ester of an α, β-unsaturated acid are usually combined with a glycidyl ester of an α, β-unsaturated acid at 500 to 4000 atm and 100 to 300 ° C. in the presence of a suitable solvent or chain transfer agent. Alternatively, it can be produced by a method of copolymerizing in the absence. Further, it can also be produced by a method in which styrenes, a glycidyl ester of an α, β-unsaturated acid and a radical generator are mixed and melt-grafted and copolymerized in an extruder.

As the epoxy group-containing copolymer (D), the epoxy group-containing olefin copolymer (D1) is preferable in terms of heat resistance. When the component (D1) and the component (D2) are used in combination, the proportion of these components can be appropriately selected according to the required characteristics.

(D) The content of the epoxy group-containing copolymer in the liquid crystal resin composition of the present invention may be, for example, 0 to 5% by mass, and preferably 1 to 5% by mass. When the content of the component (D) is within the above range, it is easy to obtain a molded article having reduced ball bearing sliding wear without impairing the fluidity of the liquid crystalline resin composition. More preferably, the content is 1.5 to 2.5% by mass.

[(E) carbon black]
The (E) carbon black used as an optional component in the present invention is not particularly limited as long as it is a commonly available one used for coloring a resin. Usually, (E) carbon black contains a lump formed by agglomeration of primary particles, but the resin composition of the present invention is molded unless a lump of a size of 50 μm or more is remarkably contained. Many bumps (fine bumps-like projections (fine unevenness) in which carbon black is aggregated) are unlikely to be generated on the surface of the formed article. When the content of the particles having the mass particle diameter of 50 μm or more is 20 ppm or less, the effect of suppressing the raising of the surface of the molded body is likely to be increased. The preferred content is 5 ppm or less.

(E) The compounding amount of carbon black in the liquid crystal resin composition may be, for example, 0 to 5% by mass, and is preferably in the range of 0.5 to 5% by mass. When the blending amount of carbon black is 0.5% by mass or more, the jet-blackness of the obtained resin composition is hardly reduced, and the light-shielding property is less likely to be uneasy. When the blending amount of carbon black is 5% by mass or less, it is difficult to be uneconomical, and hardly occurs.
[(F) Release Agent]
The release agent (F) used as an optional component in the present invention is not particularly limited as long as it is generally available, and examples thereof include fatty acid esters, fatty acid metal salts, fatty acid amides, Examples thereof include a molecular weight polyolefin, and a fatty acid ester of pentaerythritol (for example, pentaerythritol tetrastearate) is preferable.

配合 (F) The compounding amount of the release agent in the liquid crystalline resin composition may be, for example, 0 to 3% by mass, and preferably 0.1 to 3% by mass. When the compounding amount of the release agent is 0.1% by mass or more, the releasability at the time of molding is improved, and a molded body with reduced ball bearing sliding wear is easily obtained. If the amount of the release agent is 3% by mass or less, the amount of mold deposit (that is, a substance attached to a mold during molding; hereinafter, also referred to as “MD”) tends to be reduced.

[Other ingredients]
The liquid crystalline resin composition of the present invention includes other polymers, other fillers, and generally known substances generally added to synthetic resins, that is, antioxidants and ultraviolet absorbers, as long as the effects of the present invention are not impaired. Other components such as a stabilizer such as an agent, an antistatic agent, a flame retardant, a coloring agent such as a dye or a pigment, a lubricant, a crystallization accelerator, and a crystal nucleating agent can be appropriately added according to required performance. Other components may be used alone or in combination of two or more.

Other fillers include fillers other than (B) granular fillers, (C) plate-like fillers, and (E) carbon black, and include, for example, fibrous fillers such as whiskers. However, it is preferable that the liquid crystalline resin composition of the present invention does not contain a fibrous filler from the viewpoint of the weld strength of the molded article and the like.

[Preparation Method of Liquid Crystalline Resin Composition for Ball Bearing Sliding Wear Member]
The method for preparing the liquid crystalline resin composition for a ball bearing-resistant sliding wear member of the present invention is not particularly limited. For example, the above components (A) to (C), and optionally, at least one of the above components (D) to (F) and other components are blended, and these are mixed using a single-screw or twin-screw extruder. By performing the melt-kneading process, a liquid crystal resin composition for a ball bearing resistant sliding wear member is prepared.

[Liquid crystal resin composition for ball bearing resistant sliding wear members]

The liquid crystalline resin composition of the present invention obtained as described above has a melt viscosity of preferably 90 Pa · sec or less and 80 Pa · sec or less from the viewpoint of fluidity during melting and moldability. More preferably, there is. In the present specification, as the melt viscosity, a value obtained by a measurement method in accordance with ISO 11443 under the conditions of a cylinder temperature 10 to 20 ° C. higher than the melting point of the liquid crystalline resin and a shear rate of 1000 sec ⁻¹ is adopted.

<Ball bearing sliding wear member>
A ball bearing-resistant sliding wear member is manufactured using the liquid crystalline resin composition of the present invention. ADVANTAGE OF THE INVENTION The ball bearing sliding wear member of this invention is excellent in balance of surface whitening suppression, low warpage, weld strength, and low dust generation, and ball bearing sliding wear is reduced. The ball bearing-resistant sliding wear member of the present invention can be used for parts that come into dynamic contact with the ball bearing during use. Specifically, for example, it is used in a form that comes into contact with the ball bearing dynamically. Used for camera module parts such as a lens holder.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

<Liquid crystal resin>
-Liquid crystalline polyesteramide resin After charging the following raw materials in a polymerization vessel, the temperature of the reaction system was raised to 140 ° C, and the reaction was carried out at 140 ° C for 1 hour. Thereafter, the temperature was further increased to 340 ° C. over 4.5 hours, and then reduced to 10 Torr (ie, 1330 Pa) over 15 minutes while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. Melt polymerization was performed. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from a reduced pressure to a normal pressure, and the polymer was discharged from the lower part of the polymerization vessel, and the strand was pelletized to obtain pellets. The obtained pellets were subjected to a heat treatment at 300 ° C. for 2 hours under a nitrogen stream to obtain a target polymer. The melting point of the obtained polymer was 336 ° C., and the melt viscosity at 350 ° C. was 19.0 Pa · s. The melt viscosity of the polymer was measured in the same manner as the melt viscosity measurement method described later.
(I) 4-hydroxybenzoic acid (HBA); 1380 g (60 mol%)
(II) 2-hydroxy-6-naphthoic acid (HNA); 157 g (5 mol%)
(III) terephthalic acid (TA); 484 g (17.5 mol%)
(IV) 4,4'-dihydroxybiphenyl (BP); 388 g (12.5 mol%)
(V) 4-acetoxyaminophenol (APAP); 126 g (5 mol%)
Metal catalyst (potassium acetate catalyst); 110mg
Acylating agent (acetic anhydride); 1659 g

<Materials other than liquid crystalline resin>
・ Silica 1: Admafine SO-C4 (manufactured by Admatechs Co., Ltd., silica, median diameter 1.0 μm)
・ Silica 2: Admafine SO-C5 (manufactured by Admatechs Co., Ltd., silica, median diameter 1.5 μm)
・ Silica 3: Admafine SO-C6 (manufactured by Admatechs Co., Ltd., silica, median diameter 2.0 μm)
・ Silica 4: Denka fused silica FB-5SDC (manufactured by Denki Kagaku Kogyo Co., Ltd., silica, median diameter 4.0 μm)
・ Alumina: Admafine AO-502 (manufactured by Admatechs Co., Ltd., alumina, median diameter 0.7 μm)
Glass beads: EGB731 (Potters Barotini Co., Ltd., glass beads, median diameter 20.0 μm)
・ Talc: Crown Talc PP (Matsumura Sangyo Co., Ltd., Talc, median diameter 14.6 μm)
-Potassium titanate: Tismo N-102 (manufactured by Otsuka Chemical Co., Ltd., potassium titanate fiber, average fiber diameter 0.3 to 0.6 μm, average fiber length 10 to 20 μm)
・ Wollastonite: NYGLOS 8 (manufactured by NYCO Materials, calcium silicate whisker (wollastonite), number average fiber length 136 μm, average fiber diameter 8 μm)
Epoxy group-containing olefin copolymer: Bondfast 2C (manufactured by Sumitomo Chemical Co., Ltd., ethylene-glycidyl methacrylate copolymer, glycidyl methacrylate content: 6% by mass)
・ Carbon black: VULCAN XC305 (manufactured by Cabot Japan Co., Ltd., average particle diameter: 20 nm, ratio of particles having a particle diameter of 50 μm or more is 20 ppm or less)
・ Release agent: pentaerythritol tetrastearate (manufactured by Emery Oreo Chemicals Japan KK)

<Production of liquid crystalline resin composition for ball bearing sliding wear member>
The above components were melt-kneaded at a cylinder temperature of 350 ° C. using a twin-screw extruder (TEX30α type, manufactured by Nippon Steel Works, Ltd.) at the ratios (unit: mass%) shown in Tables 1 to 4, and the ball bearings were resistant. A liquid crystalline resin composition pellet for a sliding wear member was obtained.

<Surface whitening>
The pellets of Examples and Comparative Examples were molded using a molding machine (“SE30DUZ” manufactured by Sumitomo Heavy Industries, Ltd.) under the following molding conditions, and a test piece for measurement (12.5 mm × 120 mm × 0.8 mm). ) Got. The test piece for measurement was subjected to an ultrasonic cleaner (output 300 W, frequency 45 kHz) in water (80 ml) at room temperature for 3 minutes. Thereafter, the surface of the test piece for measurement was visually observed. The whitening of the surface of the test piece for measurement was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
（(Good): No whitening was observed on the entire surface of the test piece.
－- (slightly good): slight whitening is observed near the gate and / or near the ejector pin mark.
X (poor): Clear whitening is observed in the smooth portion of the test piece.
〔Molding condition〕
Cylinder temperature: 350 ° C
Mold temperature: 80 ℃
Injection speed: 100mm / sec

<Sliding wear of ball bearings>
The pellets of Examples and Comparative Examples were molded under the following molding conditions using a molding machine (“SE100DU” manufactured by Sumitomo Heavy Industries, Ltd.) to obtain test specimens for measurement (80 mm × 80 mm × 1 mm). . As shown in FIG. 1, a load is applied to the ball 4 (diameter: 5 mm, made of SUS) at the tip of the arm 3 via the grease 2 on the test piece for measurement 1 as shown in FIG. After performing a reciprocating sliding test under the reciprocating sliding conditions, the width of the ball bearing sliding traces remaining on the test specimen for measurement 1 was measured using a stereoscopic microscope, and the ball bearing sliding abrasion was evaluated based on the following criteria. evaluated. The results are shown in Tables 1 to 4.
（(Good): The width of the ball bearing sliding trace was 540 μm or less.
X (poor): The width of the ball bearing sliding trace was more than 540 μm.
〔Molding condition〕
Cylinder temperature: 350 ° C
Mold temperature: 80 ℃
Injection speed: 33mm / sec
[Reciprocating sliding conditions]
Sliding speed: 5cm / sec
Stroke: 20mm
Load: 29.6N (3kg weight)
Number of reciprocations: 1000 times Grease: Toray Dow Corning Co., Ltd., Molycoat EM-30L

<Sledding>
The pellets of Examples and Comparative Examples were molded under the following molding conditions by using a molding machine (“SE30DUZ” manufactured by Sumitomo Heavy Industries, Ltd.), and 10.0 mm × as shown in FIG. A camera module type molded product of 10.0 mm × 1.0 mm was obtained. The obtained camera module-shaped molded product was allowed to stand on a horizontal desk, and the height of the camera module-shaped molded product was measured using a Mitutoyo Quick Vision 404PROCNC image measuring machine. At this time, the height was measured at a plurality of positions indicated by black circles in FIG. 2B, and the difference between the maximum height and the minimum height from the least square plane was defined as warpage. Warpage was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
（(Good): The warpage was 0.020 mm or less.
Δ (Somewhat good): Warpage deformation was more than 0.020 mm and 0.025 mm or less.
X (bad): The warpage was more than 0.025 mm.
〔Molding condition〕
Cylinder temperature: 350 ° C
Mold temperature: 80 ℃
Injection speed: 100mm / sec
Holding pressure: 50MPa

<Weld strength>
The pellets of Examples and Comparative Examples were injection molded under the following molding conditions, and as shown in FIG. 3, a perforated test piece 10 having a film gate 11 and a hole 12 (perforated plate 30 mm × 30 mm × 0.3 mm, hole diameter 7 mm). A 4.5 mm wide portion on the gate side and a 4.5 mm wide portion on the opposite side of the gate were cut out from the obtained perforated test piece 10 with the hole 12 interposed therebetween to obtain test pieces 13 a and 13 b for measurement. The bending strength of each of the measurement test pieces 13a and 13b was measured under the following measurement conditions, and the value obtained by dividing the bending strength of the measurement test piece 13b on the opposite side of the gate by the bending strength of the measurement test piece 13a on the gate side was used as the weld strength. As the strength retention, the weld strength was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
（(Good): The weld strength retention was 55% or more.
Δ (Somewhat good): The weld strength retention was 45% or more and less than 55%.
X (bad): the weld strength retention was less than 45%.
[Molding condition]
Forming machine; Sumitomo Heavy Industries SE30DUZ
Cylinder temperature: 350 ℃ -350 ℃ -350 ℃ -340 ℃ -330 ℃
Mold temperature; 90 ° C
Injection speed: 200mm / sec
Holding pressure: 50MPa
Packing time: 2 sec
Cooling time: 8 sec
Screw rotation speed: 150 rpm
Screw back pressure; 1MPa
[Measurement condition]
Measuring machine: Orientec Tensilon Universal Tester RTM-100
Load cell; 100kg
Span: 4.8mm
Bending speed: 2mm / min

<Number of generated dust>
The pellets of Examples and Comparative Examples were molded using a molding machine (“SE30DUZ” manufactured by Sumitomo Heavy Industries, Ltd.) under the following molding conditions to obtain a molded body of 12.5 mm × 120 mm × 0.8 mm. Was. This molded article was used as a test piece.
〔Molding condition〕
Cylinder temperature: 350 ° C
Mold temperature: 80 ℃
Injection speed: 100mm / sec
[Evaluation]
The test piece was subjected to an ultrasonic cleaner (output 300 W, frequency 45 kHz) in water (80 ml) at room temperature for 3 minutes. Thereafter, the number of particles having a particle size of 2 μm or more existing in the water was measured by a particle counter (a particle counter KL-11A (PARTICLECOUNTER) manufactured by RION Co., Ltd.) and evaluated as the number of generated dust. The results are shown in Tables 1 to 4.

As is evident from the results shown in Tables 1 to 4, the molded articles of the examples are excellent in balance with suppression of surface whitening, low warpage, weld strength, and low dust generation, and ball bearing sliding wear. Was confirmed to be reduced.

DESCRIPTION OF SYMBOLS 1 Test specimen 2 Grease 3 Arm 4 Ball 10 Perforated test specimen 11 Film gate 11
12 holes 13a, 13b Test piece for measurement

Claims (4)

(A) liquid crystalline resin,
(B) a particulate filler, and (C) a plate-like filler,
The median diameter of the (B) granular filler is 1.3 to 5.0 μm,
The content of the particulate filler (B) is 7.5 to 22.5% by mass,
The content of the (C) plate-like filler is 2.5 to 27.5% by mass,
A liquid crystal resin composition for a ball-bearing sliding wear member, wherein the total content of the (B) granular filler and the (C) plate-like filler is 22.5 to 37.5% by mass. The (B) granular filler is silica,
The composition according to claim 1, wherein the (C) platy filler is talc. The composition according to claim 1, further comprising (D) an epoxy group-containing copolymer,
A composition wherein the content of the epoxy group-containing copolymer (D) is 1 to 5% by mass. (4) A ball bearing sliding and wear resistant member comprising the composition according to any one of (1) to (3).

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