KR20230008223A - Liquid crystalline resin composition for ball bearing sliding wear resistance and ball bearing sliding wear resistance using the same - Google Patents

Abstract

Ball bearing sliding wear resistance used to manufacture a ball bearing sliding wear resistant member that is excellent in balance in suppression of surface whitening, mechanical strength, dimensional accuracy, and low dust generation, and at the same time not only reduces ball bearing sliding wear but also maintains impact resistance A liquid crystal resin composition for a member and a wear-resistant ball bearing sliding member using the same are provided. The liquid crystalline resin composition for a wear-resistant ball bearing sliding member according to the present invention contains (A) a liquid crystalline resin, (B) a granular filler, and (C) a whisker, and the median diameter of the granular filler (B) is from 0.3 to 0.3. 5.0 μm, the content of the granular filler (B) is 7.5 to 22.5% by mass, the content of the whiskers (C) is 2.5 to 17.5% by mass, and the total of the granular filler (B) and the whiskers (C) The content is 12.5 to 32.5% by mass.

Description

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

The present invention relates to a liquid crystal resin composition for a sliding ball bearing wear-resistant member and a ball bearing sliding 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. In recent years, liquid crystalline resins have come to be used for precision equipment parts taking advantage of these characteristics.

Examples of parts in which the liquid crystalline resin is used include connectors such as FPC connectors; sockets such as memory card sockets; Components for camera modules, such as a lens holder; relay can be used. Since these parts are required to be excellent in suppression of surface whitening, mechanical strength, dimensional accuracy and low dust generation, and are also sometimes used in a form in which two or more members are brought into dynamic contact, It is also desired to reduce sliding abrasion (that is, a tendency to wear when two or more members dynamically contact each other). For example, in Patent Literature 1, an object is to provide a molded article made of a liquid crystalline resin composition having excellent surface appearance and excellent sliding properties, liquid crystalline resin and talc having a specific volume average particle diameter in a specific ratio A liquid crystal resin composition containing is disclosed.

Among the above-mentioned parts, in the case of a part used in a form in which a molded body made of a liquid crystalline resin composition and a ball bearing are in dynamic contact, in particular, the ball bearing sliding wearability (ie, the property of being easily worn when in dynamic contact with the ball bearing) This reduction is required. In addition, if the component is difficult to return to its original state when a dent or the like is formed in the molded body due to an impact, there is a concern that a defect may occur in dynamic contact between the molded body and the ball bearing. Therefore, the parts are also required to have impact resistance, that is, characteristics that easily return to their original state even if dents are generated upon impact. In addition, Patent Literature 2 describes a component for a camera module used in a form in which it is brought into contact with a ball bearing dynamically.

Japanese Patent No. 5087958 European Patent No. 2938063 Specification

However, according to the study of the present inventors, with the conventional liquid crystalline resin composition, the ball bearing sliding wear resistance is reduced, but the impact resistance is rather deteriorated. The present invention has been made to solve the above problems, and its object is to provide a well-balanced surface whitening suppression, mechanical strength, dimensional accuracy, and low dust generation property, and at the same time, not only the ball bearing sliding wear resistance is reduced, but also the impact resistance is improved. An object of the present invention is to provide a liquid crystalline resin composition for a ball bearing sliding wear resistant member used to manufacture a maintained ball bearing sliding wear resistant member and a ball bearing sliding wear resistant member using the same.

The present inventors repeated earnest research in order to solve the said subject. As a result, the liquid crystal resin contains a liquid crystalline resin, a granular filler, and a whisker, the median diameter of the granular filler is within a predetermined range, and the content of each of the granular filler, the whisker, and the sum of these is within a predetermined range. By using the composition, it was discovered that the above problems could be solved and the present invention was completed. More specifically, the present invention provides the following.

(1) contains (A) a liquid crystalline resin, (B) a granular filler, and (C) a whisker, wherein the (B) granular filler has a median diameter of 0.3 to 5.0 μm, and (B) the granular filler The content of the filler is 7.5 to 22.5% by mass, the content of the (C) whisker is 2.5 to 17.5% by mass, and the total content of the (B) granular filler and the (C) whisker is 12.5 to 32.5% by mass, A liquid crystal resin composition for anti-ball bearing sliding wear members.

(2) The composition according to (1), wherein the (B) particulate filler is at least one selected from the group consisting of silica and barium sulfate.

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

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

When a ball bearing sliding wear resistant member is prepared using the liquid crystalline resin composition for a ball bearing sliding wear resistant member of the present invention as a raw material, surface whitening inhibition, mechanical strength, dimensional accuracy, and low dust generation are well-balanced, and at the same time, the ball bearing sliding wear resistance It is possible to obtain a ball bearing sliding wear-resistant member in which not only this is reduced but also the impact resistance is maintained.

Fig. 1 (a) is a plan view showing a molded body molded to measure the depth of a dent in the embodiment, and Fig. 1 (b) is a partial longitudinal cross-sectional view showing a BB cross section in Fig. 1 (a). In addition, unless otherwise indicated, the numerical unit in the drawing is mm.
Fig. 2 (a) is a perspective view showing a C-shaped liquid crystalline resin molded body used for internal warping deformation evaluation conducted in Examples, and Fig. 2 (b) is a side view showing the C-shaped liquid crystalline resin molded body.
3 is a diagram for explaining a sliding wear amount evaluation method.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described. In addition, this invention is not limited to the following embodiment.

<Liquid crystalline resin composition for anti-ball bearing sliding wear member>

The liquid crystalline resin composition for a wear-resistant ball bearing sliding member of the present invention contains (A) a liquid crystalline resin, (B) a granular filler, and (C) a whisker.

[(A) liquid crystalline resin]

The (A) liquid crystalline resin 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, confirmation of the anisotropic molten phase can be performed by observing a molten sample placed on a Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times using a Leitz polarization microscope. When the liquid crystalline polymer applicable to the present invention is inspected between orthogonal polarizers, even in a melt-stopped state, for example, polarized light is normally transmitted and exhibits optical anisotropy.

The type of the above (A) liquid crystalline resin is not particularly limited, and is preferably an aromatic polyester and/or an aromatic polyester amide. In addition, polyesters partially containing aromatic polyesters and/or aromatic polyesteramides in the same molecular chain are also within that range. (A) The liquid crystalline resin preferably has a logarithmic viscosity of at least about 2.0 dl/g, more preferably 2.0 to 10.0 dl/g when dissolved in pentafluorophenol at 60°C at a concentration of 0.1% by mass ( I.V.) is preferably used.

Particularly preferably, the aromatic polyester or aromatic polyesteramide as (A) liquid crystalline resin applicable to the present invention contains a repeating unit derived from one or two or more aromatic hydroxycarboxylic acids and derivatives thereof. It is the aromatic polyester or aromatic polyesteramide which has as a structural component.

More specifically,

(1) polyester mainly composed of repeating units derived from one or two or more of aromatic hydroxycarboxylic acids and their derivatives;

(2) Mainly (a) a repeating unit derived from one or two or more of aromatic hydroxycarboxylic acids and their derivatives, and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives Polyester which consists of repeating units derived from 2 or more types;

(3) Mainly (a) a repeating unit derived from one or two or more of aromatic hydroxycarboxylic acids and their derivatives, and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives polyester comprising repeating units derived from two or more species, and (c) repeating units derived from at least one or two or more of aromatic diols, alicyclic diols, aliphatic diols, and their derivatives;

(4) Mainly (a) a repeating unit derived from one or two or more of aromatic hydroxycarboxylic acids and their derivatives, and (b) one or two or more of aromatic hydroxyamines, aromatic diamines, and their derivatives Polyesteramide consisting of repeating units derived from (c) aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and repeating units derived from one or two or more of their derivatives;

(5) Mainly (a) a repeating unit derived from one or two or more of aromatic hydroxycarboxylic acids and their derivatives, and (b) one or two or more of aromatic hydroxyamines, aromatic diamines, and their derivatives A repeating unit derived from (c) a repeating unit derived from one or two or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives, and (d) aromatic diols, alicyclic diols, and aliphatic diols , and repeating units derived from at least one or two or more of these derivatives. In addition, a molecular weight modifier may be used in combination with the above components as necessary.

Preferable examples of specific compounds constituting the (A) liquid crystalline resin applicable to the present invention include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcin, a compound represented by the following general formula (I), and the following general Aromatic diols, such as a compound represented by Formula (II); 1,4-phenylenedicarboxylic acid, 1,3-phenylenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and represented by the following general formula (III) Aromatic dicarboxylic acid, such as a compound which becomes; and aromatic amines such as p-aminophenol, p-phenylenediamine, and N-acetyl-p-aminophenol.

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

(Y: It is a group selected from -(CH ₂ ) _n -(n = 1 to 4) and -O(CH ₂ ) _n O-(n = 1 to 4).)

Preparation of the (A) liquid crystalline resin used in the present invention can be carried out by a known method using a direct polymerization method or a transesterification method from the above monomer compound (or mixture of monomers), usually a melt polymerization method, A solution polymerization method, a slurry polymerization method, a solid-state polymerization method, or the like, or a combination of two or more of these methods is used, and a melt polymerization method or a combination of a melt polymerization method and a solid-state polymerization method is preferably used. The compounds having ester-forming ability may be used for polymerization in their original form, or may be modified from precursors to derivatives having ester-forming ability in a previous stage of polymerization. When polymerizing these, various catalysts can be used, and typical examples are potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, tris(2,4-pentanedionate ) metal salt-based catalysts such as cobalt (III); and organic compound-based catalysts such as N-methylimidazole and 4-dimethylaminopyridine. The amount of catalyst used is generally about 0.001 to 1% by mass, particularly preferably about 0.01 to 0.2% by mass, based on the total mass of the monomers. Polymers produced by these polymerization methods can be further increased in molecular weight by solid-state polymerization by heating under reduced pressure or in an inert gas, if necessary.

The melt viscosity of the liquid crystalline resin (A) obtained by the above method is not particularly limited. In general, 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, those having excessively high viscosity themselves are undesirable because the fluidity is greatly deteriorated. Moreover, the mixture of 2 or more types of liquid crystal resins may be sufficient as said (A) liquid crystalline resin.

In the liquid crystalline resin composition of the present invention, the content of the liquid crystalline resin (A) is preferably 67.5 to 87.5% by mass or 66.5 to 82.5% by mass, more preferably 69 to 84% by mass or 67 to 80% by mass. %to be. If the content of component (A) is within the above range, it is preferable in terms of fluidity, heat resistance, and the like.

[(B) Granular Filler]

Component (B) is a granular filler, and the median diameter of component (B) is 0.3 to 5.0 μm. When the median diameter is 0.3 μm or more, the impact resistance of the molded article is easily maintained. When the median diameter is 5.0 μm or less, the surface whitening inhibitory effect of the molded article is likely to increase. The median diameter is preferably 0.5 to 5.0 μm, more preferably 0.5 to 4.0 μm. In addition, in this specification, the median diameter of component (B) refers to the volume-based median value measured by laser diffraction/scattering particle size distribution analysis. The median diameter of the component (B) in the liquid crystalline resin composition is measured by applying the above method to the remaining component (B) obtained by carbonizing the liquid crystalline resin composition by heating at 600°C for 2 hours. (B) component may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of the particulate filler of component (B) include metal oxides such as silica, quartz powder, glass beads, glass powder, potassium aluminum silicate, diatomaceous earth, iron oxide, titanium oxide, zinc oxide, and alumina; metal carbonates such as calcium carbonate and magnesium carbonate; metal sulfates such as calcium sulfate and barium sulfate; phosphates such as calcium pyrophosphate and anhydrous dibasic calcium phosphate; silicon carbide; silicon nitride; Boron nitride etc. are mentioned. In the present invention, from the viewpoint of suppression of surface whitening of molded articles and low dust generation of molded articles, it is preferable to use at least one selected from the group consisting of silica and barium sulfate as component (B), and it is preferable to use silica. more preferable

The content of component (B) is 7.5 to 22.5% by mass in the liquid crystalline composition of the present invention. When the content of the component (B) is 7.5% by mass or more, the dimensional accuracy of the molded body is easily increased, and a molded body in which sliding wear resistance of the ball bearing is reduced is easily obtained. When the content of the component (B) is 22.5% by mass or less, the effect of suppressing whitening on the surface of the molded body is easily enhanced, and the impact resistance of the molded body is easily maintained. (B) The preferable content of component is 8.5-21 mass %.

[(C) Whiskers]

The liquid crystalline resin composition according to the present invention includes whiskers. By including whiskers in the liquid crystalline resin composition according to the present invention, the mechanical strength of the molded article is easily improved and at the same time a molded article in which the ball bearing sliding wear resistance is reduced is easily obtained. In this specification, whisker refers to a mineral fiber, and more specifically refers to an acicular single crystal. Whiskers can be used individually by 1 type or in combination of 2 or more types.

(C) The average fiber length of the whiskers is preferably 5 to 200 μm, more preferably 7 to 170 μm, still more preferably 9 to 150 μm. When the average fiber length is within the above range, the mechanical strength of the molded article is more likely to be improved. Further, in the present specification, (C) as the average fiber length of whiskers, 10 stereomicroscope images of whiskers are transferred from a CCD camera to a PC, and 100 whiskers per stereomicroscope image are obtained by image processing technology using an image measuring device; That is, the average of the measured fiber length values for a total of 1000 whiskers is adopted. The average fiber length of (C) whiskers in the liquid crystalline resin composition is measured by applying the above method to the whiskers remaining after carbonizing the liquid crystalline resin composition by heating at 600°C for 2 hours.

(C) The average fiber diameter of the whiskers is preferably 0.2 to 15 μm or less, more preferably 0.25 to 10 μm. When the average fiber diameter is within the above range, the mechanical strength of the molded article is more likely to be improved. In this specification, (C) as the average fiber diameter of the whiskers, the average of the fiber diameter values obtained by observing the whiskers with a scanning electron microscope and measuring the fiber diameters of 30 whiskers is adopted. The average fiber diameter of the whiskers (C) in the liquid crystalline resin composition is measured by applying the above method to the whiskers remaining after carbonizing the liquid crystalline resin composition by heating at 600°C for 2 hours.

(C) The aspect ratio of the whiskers, that is, the average fiber length/average fiber diameter value, is preferably from the viewpoint of the mechanical strength of molded articles such as ball bearing sliding wear-resistant members made of the liquid crystalline resin composition according to the present invention. It is 8 or more, More preferably, it is 10-100, More preferably, it is 15-75.

(C) The whisker is not particularly limited, and examples thereof include potassium titanate whisker, calcium silicate whisker (wollastonite, wollastonite), calcium carbonate whisker, zinc oxide whisker, aluminum borate whisker, silicon nitride whisker, silicon trinitride whisker, and basic magnesium sulfate. whiskers, barium titanate whiskers, silicon carbide whiskers, and boron whiskers, and from the viewpoint of availability, etc., potassium titanate whiskers, calcium silicate whiskers (wollastonite), calcium carbonate whiskers, zinc oxide whiskers, aluminum borate whiskers, etc. are preferred. , potassium titanate whiskers, calcium silicate whiskers (wollastonite) and the like are more preferable.

The content of component (C) is 2.5 to 17.5% by mass in the liquid crystalline composition of the present invention. When the content of the component (C) is 2.5% by mass or more, the mechanical strength is easily improved and a molded article in which the sliding wear resistance of the ball bearing is reduced is easily obtained. (C) When the content of component is 17.5% by mass or less, the impact resistance of the molded article is easily maintained. (C) The content of component is preferably 4.5 to 14% by mass.

In addition, the content of the total of component (B) and component (C) is 12.5 to 32.5% by mass, preferably 16 to 31% by mass, in the liquid crystalline resin composition of the present invention. When the total content of the above is 12.5% by mass or more, the dimensional accuracy of the molded body is easily increased, and a molded body in which the sliding wear resistance of the ball bearing is reduced is easily obtained. If the content of the above total is 32.5% by mass or less, the effect of suppressing surface whitening of the molded article and the low dusting property of the molded article are likely to increase, and the impact resistance of the molded article is likely to be maintained.

[(D) Epoxy group-containing copolymer]

The liquid crystalline composition of the present invention may contain (D) an epoxy group-containing copolymer. (D) Epoxy group-containing copolymer can be used individually by 1 type or in combination of 2 or more types. (D) The epoxy group-containing copolymer is not particularly limited, and examples thereof include at least one selected from the group consisting of (D1) an epoxy group-containing olefin copolymer and (D2) an epoxy group-containing styrenic copolymer. . (D) The epoxy group-containing copolymer contributes to reducing the ball bearing sliding wear resistance of the molded body obtained from the liquid crystalline resin composition of the present invention.

(D1) Examples of the epoxy group-containing olefin copolymer include copolymers composed of repeating units derived from α -olefins and repeating units derived from glycidyl esters of α , β -unsaturated acids.

[alpha ]-olefin is not specifically limited, For example, ethylene, propylene, butene, etc. are mentioned, Among these, ethylene is used preferably. The glycidyl ester of α , β -unsaturated acid is represented by the following general formula (IV). Glycidyl esters of α , β -unsaturated acids include, for example, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconic acid, and the like, particularly methacrylic acid. Glycidyl esters are preferred.

(D1) In the epoxy group-containing olefin copolymer, the content of repeating units derived from α -olefins is 87 to 98% by mass, and the content of repeating units derived from glycidyl esters of α , β -unsaturated acids is 13 It is preferably ~ 2% by mass.

The (D1) epoxy group-containing olefinic copolymer used in the present invention contains acrylonitrile, acrylic acid ester, methacrylic acid ester, α -methylstyrene, anhydrous as a third component in addition to the above two components, within the scope of not impairing the present invention. You may contain 0-48 mass parts of repeating units derived from 1 type, or 2 or more types of olefin type unsaturated esters, such as maleic acid, with respect to 100 mass parts of said two components.

The epoxy group-containing olefin copolymer, which is component (D1) of the present invention, can be easily prepared by a conventional radical polymerization method using a monomer corresponding to each component and a radical polymerization catalyst. More specifically, usually, glycidyl esters of α -olefins and α , β -unsaturated acids are mixed in the presence of a radical generating agent at 500 to 4000 atmospheres at 100 to 300° C. in the presence or absence of a suitable solvent or chain transfer agent. It can be manufactured by a method of copolymerizing under It can also be produced by a method of mixing an α -olefin with an α , β -unsaturated acid glycidyl ester and a radical generating agent, followed by melt graft copolymerization in an extruder.

Examples of the epoxy group-containing styrenic copolymer (D2) include copolymers composed of repeating units derived from styrene and repeating units derived from glycidyl esters of α , β -unsaturated acids. Since the glycidyl ester of α , β -unsaturated acid is the same as that described for component (D1), the description thereof is omitted.

Examples of styrenes include styrene, α -methylstyrene, brominated styrene, and divinylbenzene, and styrene is preferably used.

The (D2) epoxy group-containing styrenic copolymer used in the present invention may be a multicomponent copolymer containing repeating units derived from one or two or more other vinyl monomers as a third component in addition to the above two components. . What is preferable as a 3rd component is a repeating unit derived from 1 type(s) or 2 or more types of olefin type unsaturated esters, such as acrylonitrile, acrylic acid ester, methacrylic acid ester, and maleic anhydride. A styrenic copolymer containing an epoxy group containing 40% by mass or less of these repeating units in the copolymer is preferable as the component (D2).

(D2) In the styrenic copolymer containing an epoxy group, the content of repeating units derived from glycidyl esters of α , β -unsaturated acids is 2 to 20% by mass, and the content of repeating units derived from styrene is 80 to 80%. It is preferably 98% by mass.

(D2) The epoxy group-containing styrenic copolymer can be prepared by a conventional radical polymerization method using a monomer corresponding to each component and a radical polymerization catalyst. More specifically, usually, glycidyl esters of styrene and α , β -unsaturated acids are mixed in the presence of a radical generating agent at 500 to 4000 atm and 100 to 300° C. in the presence or absence of a suitable solvent or chain transfer agent. It can be manufactured by a copolymerization method. It can also be produced by a method in which styrenes, a glycidyl ester of an α , β -unsaturated acid and a radical generating agent are mixed and melt graft copolymerized in an extruder.

Moreover, (D) As an epoxy group containing copolymer, (D1) epoxy group containing olefin type copolymer is preferable at a heat resistant point. When a component (D1) and a component (D2) are used together, the ratio of these components can be appropriately selected according to required properties.

(D) The content of the epoxy group-containing copolymer in the liquid crystalline resin composition of the present invention may be, for example, 0 to 5% by mass, preferably 1 to 5% by mass. When the content of component (D) is within the above range, it is easy to obtain a molded product with reduced ball bearing sliding wear resistance without impairing the fluidity of the liquid crystalline resin composition. More preferable said content is 2-4 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 generally available for use in resin coloring. Usually, (E) carbon black contains lumps formed by aggregation of primary particles, but unless significantly larger than 50 μm is included, the resin composition of the present invention It is difficult to generate many boots (fine millet-like protrusions (fine irregularities) in which carbon black is aggregated) on the surface of the molded article. When the content of the particles having a particle size of 50 μm or more of the conglomeration is 20 ppm or less, the effect of suppressing hair growth on the surface of the molded article is easily enhanced. A preferable content rate is 5 ppm or less. (E) component may be used individually by 1 type, and may be used in combination of 2 or more types.

(E) As the blending amount of carbon black, in the liquid crystalline resin composition, it may be, for example, 0 to 5% by mass, and the range of 0.5 to 5% by mass is preferable. When the compounding amount of carbon black is 0.5% by mass or more, the jet-blackness of the obtained resin composition is less likely to decrease, and uneasiness in light-shielding properties is less likely to appear. If the compounding amount of carbon black is 5% by mass or less, it is difficult to become uneconomical and also hard to generate boots.

[(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 include fatty acid esters, fatty acid metal salts, fatty acid amides, low molecular weight polyolefins, etc. , fatty acid esters of pentaerythritol (for example, pentaerythritol tetrastearate) are preferred. (F) component may be used individually by 1 type, and may be used in combination of 2 or more types.

(F) As the compounding amount of the release agent, in the liquid crystalline resin composition, it may be, for example, 0 to 3% by mass, and the range of 0.1 to 3% by mass is preferable. When the compounding amount of the release agent is 0.1% by mass or more, it is easy to obtain a molded article in which the release property at the time of molding is improved and the sliding wear resistance of the ball bearing is reduced. When the compounding amount of the mold release agent is 3% by mass or less, mold deposits (namely, deposits on molds during molding. Hereinafter referred to as "MD") are likely to be reduced.

[Other Ingredients]

In the liquid crystal resin composition of the present invention, other polymers, other fillers, known substances generally added to synthetic resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, Other components such as flame retardants, coloring agents such as dyes and pigments, lubricants, crystallization accelerators, and crystal nucleating agents may also be appropriately added according to required performance. The other components may be used singly or in combination of two or more.

Other fillers refer to fillers other than (B) granular filler, (C) whiskers, and (E) carbon black, and include, for example, granular fillers other than component (B); platy filler; (C) Fibrous fillers other than component are mentioned. Other fillers may be used alone or in combination of two or more. Examples of particulate fillers other than component (B) include particulate fillers having a median diameter of less than 0.3 μm or more than 5.0 μm. Examples of the plate-shaped filler include mica and talc. (C) As a fibrous filler other than component, glass fiber is mentioned, for example. However, from the viewpoint of the impact resistance of the molded body, etc., it is preferable that the liquid crystalline resin composition of the present invention does not contain a plate-like filler. Further, from the viewpoint of the impact resistance of the molded article and the low dusting property of the molded article, the liquid crystalline resin composition of the present invention preferably does not contain a fibrous filler other than component (C).

[Preparation Method of Liquid Crystalline Resin Composition for Ball Bearing Sliding Wear Resistance]

The method for preparing the liquid crystalline resin composition for wear-resistant ball bearing sliding members of the present invention is not particularly limited. For example, by blending at least one of the above components (A) to (C) and optionally the above (D) to (F) components and other components, and melt-kneading them using a single screw or twin screw extruder, , Preparation of a liquid crystal resin composition for a ball bearing sliding wear-resistant member is made.

[Liquid crystalline resin composition for anti-ball bearing sliding wear member]

The liquid crystalline resin composition of the present invention obtained as described above preferably has a melt viscosity of 90 Pa·sec or less, more preferably 80 Pa·sec or less, from the viewpoint of fluidity and moldability during melting. In this specification, as the melt viscosity, a value obtained by a measurement method based on ISO 11443 under conditions of a cylinder temperature 10 to 20° C. higher than the melting point of the liquid crystal resin and a shear rate of 1000 sec ^-1 is used.

<Ball bearing sliding wear resistance member>

Using the liquid crystalline resin composition of the present invention, a ball bearing sliding wear resistant member is produced. The anti-ball bearing sliding wear member of the present invention is excellent in balance in suppression of surface whitening, mechanical strength, dimensional accuracy, and low dust generation, and at the same time, not only the ball bearing sliding wear resistance is reduced, but also the impact resistance is maintained. The anti-ball bearing sliding wear member of the present invention can be used for a part that dynamically contacts a ball bearing during use, specifically, for example, a lens holder that can be used in a form that dynamically contacts a ball bearing. It can be used for parts for camera modules, etc.

Example

The present invention will be described in more detail by way of examples below, but the present invention is not limited only to these examples.

<liquid crystalline resin>

ㆍ Liquid crystalline polyesteramide resin

After putting the following raw materials into the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 1 hour. Thereafter, the temperature was further raised to 340° C. over 4.5 hours, and from there the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes to remove acetic acid, excess acetic anhydride, and other low specific contents. Melt polymerization was performed while distilling. After the stirring torque reached a predetermined value, nitrogen was introduced to a pressurized state from a reduced pressure state through normal pressure, the polymer was discharged from the bottom of the polymerization vessel, and the strands were pelletized to obtain pellets. The obtained pellets were subjected to 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. In addition, 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) 1,4-phenylenedicarboxylic acid (TA); 484 g (17.5 mol%)

(IV) 4,4'-dihydroxybiphenyl (BP); 388 g (12.5 mol%)

(V) N-acetyl-p-aminophenol (APAP); 126 g (5 mol%)

metal catalyst (potassium acetate catalyst); 110 mg

acylating agents (acetic anhydride); 1659g

<Materials other than liquid crystalline resin>

ㆍ Silica 1: Admapine SO-C2 (manufactured by Admatex Co., Ltd., silica, central diameter 0.5 μm)

ㆍ Silica 2: Admapine SO-C6 (manufactured by Admatex Co., Ltd., silica, central diameter 2.0 μm)

Silica 3: Denka Fused Silica FB-5SDC (manufactured by Denka Co., Ltd., silica, central diameter 4.0 μm)

ㆍ Mica: AB-25S (manufactured by Yamaguchi Mica Co., Ltd., mica, central diameter 25.0 ㎛)

ㆍ Talc: Crown Talc PP (manufactured by Matsumura Industrial Co., Ltd., talc, central diameter 14.6㎛)

ㆍ Potassium titanate: Tismo N-102 (manufactured by Otsuka Chemical Co., Ltd., potassium titanate whisker (potassium titanate fiber), average fiber diameter 0.3 ~ 0.6 ㎛, average fiber length 10 ~ 20 ㎛)

ㆍ Wollastonite: NYGLOS 8 (manufactured by NYCO Materials, calcium silicate whisker (wollastonite), average fiber length 136 ㎛, average fiber diameter 8 ㎛)

ㆍ Glass fiber: ECSO3T-786H (manufactured by Nippon Denki Glass Co., Ltd., chopped strand, fiber diameter 10 ㎛, length 3 mm)

ㆍ Epoxy group-containing olefin copolymer: Bondfast 2C (manufactured by Sumitomo Chemical Co., Ltd., ethylene-glycidyl methacrylate copolymer, glycidyl methacrylate content 6% by mass)

ㆍ Carbon black: VULCAN XC305 (manufactured by Cabot Japan Co., Ltd., average particle diameter 20 nm, particle diameter of 50㎛ or more is less than 20 ppm)

ㆍ Release agent: Pentaerythritol tetrastearate (manufactured by Emery Oreo Chemicals Japan Co., Ltd.)

<Production of Liquid Crystal Resin Composition for Ball Bearing Sliding Wear Resistance>

The above components were melt-kneaded at a cylinder temperature of 350° C. using a twin-screw extruder (TEX30 α type manufactured by Nippon Steel Works) at the ratios (unit: mass%) shown in Table 1, Table 2, or Table 3, and ball bearing resistance Liquid crystalline resin composition pellets for sliding wear members were obtained.

<Surface Whitening>

The pellets of Examples and Comparative Examples were molded using a molding machine (“SE30DUZ” manufactured by Sumitomo Heavy Machinery Co., Ltd.) under the following molding conditions to obtain test pieces (12.5 mm × 120 mm × 0.8 mm) for measurement. The test piece for measurement was hung in an ultrasonic cleaner (output: 300 W, frequency: 45 kHz) in room temperature water (80 mL) for 3 minutes. Then, 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. A result is shown to Tables 1-5.

○ (Good): No whitening was observed on the entire surface of the test piece.

x (defect): Obvious whitening was recognized in the smooth part of the test piece.

[Molding conditions]

Cylinder temperature: 350℃

Mold temperature: 80℃

Injection speed: 100mm/sec

<bending test>

The pellets of Examples and Comparative Examples were molded using a molding machine ("SE100DU" manufactured by Sumitomo Heavy Machinery Co., Ltd.) under the following molding conditions to obtain an ISO test piece type A. This test piece was cut out to obtain a test piece (80 mm x 10 mm x 4 mm) for measurement. Using this test piece for measurement, bending strength, bending breaking strain, and bending elastic modulus were measured based on ISO 178. Among them, the measurement results of the bending strength were evaluated according to the following criteria. A result is shown to Tables 1-3.

(circle) (good): The bending strength was 150 MPa or more.

x (poor): The bending strength was less than 150 MPa.

[Molding conditions]

Cylinder temperature: 350℃

Mold temperature: 90℃

Injection speed: 33mm/sec

<Ball bearing sliding wear resistance>

The pellets of Examples and Comparative Examples were molded using a molding machine (“SE100DU” manufactured by Sumitomo Heavy Machinery Co., Ltd.) under the following molding conditions to obtain test pieces (80 mm × 80 mm × 1 mm) for measurement. Using a light load reciprocating sliding tester, as shown in Fig. 3, a ball 4 (diameter 5 mm, made of SUS) was applied, and after performing a reciprocating sliding test under the following reciprocating sliding conditions, the width of the ball bearing sliding scar formed on the test piece 1 for measurement was measured using a stereo microscope, and the ball bearing sliding wear resistance was measured. Evaluation was made according to the following criteria. A result is shown to Tables 1-3.

○ (Good): The width of the sliding mark of the ball bearing was 540 μm or less.

× (defective): The width of the ball bearing sliding scar was greater than 540 μm.

[Molding conditions]

Cylinder temperature: 350℃

Mold temperature: 80℃

Injection speed: 33mm/sec

[Reciprocating sliding conditions]

Sliding speed: 5cm/sec

Stroke: 20mm

Load: 29.6N (3kg weight)

Number of round trips: 1000 times

Grease: Toray Dow Corning, Mollycoat EM-30L

＜Depth of dent＞

Under the following molding conditions, the liquid crystalline resin composition was injection molded (gate: pin gate, gate size: φ 0.3 mm), and molded products as shown in FIGS. 1(a) and 1(b) were obtained.

[Molding conditions]

Molding machine: Sumitomo Heavy Machinery Co., Ltd., SE30DUZ

Cylinder temperature: 350℃

Mold temperature: 90℃

Injection speed: 200mm/sec

Using a Dupont drop impact tester (Yasuda Precision Machinery Manufacturing Co., Ltd.), after dropping a weight on the upper surface of the molded body under the following conditions, the depth of the dent formed in the molded body was measured using a laser microscope. The depth of the pit was used as an indicator of the impact resistance of the molded body. A result is shown to Tables 1-3.

[Exam conditions]

Drop height: 15 mm

Fall Weight: 75g

Strike Type: Diameter 0.75 mm

<Evaluation of internal bending deformation>

Under the following molding conditions, the liquid crystalline resin composition was injection molded to obtain a U-shaped liquid crystalline resin molding (thickness: 0.5 mm) shown in Figs. 6020 was used to measure each A (gate side) and each B (half gate side) shown in Fig. 2(b). The average of each A and each B was calculated and used as an index showing the dimensional accuracy of the molded body. A result is shown to Tables 1-3.

[Molding conditions]

Forming machine: Sumitomo Heavy Machinery, SE30DUZ

Cylinder temperature: 350℃

Mold temperature: 90℃

Injection speed: 100mm/sec

<Number of dust generated>

The pellets of Examples and Comparative Examples were molded using a molding machine ("SE30DUZ" manufactured by Sumitomo Heavy Machinery Co., Ltd.) under the following molding conditions to obtain a molded body of 12.5 mm × 120 mm × 0.8 mm. This molded body was used as a test piece.

[Molding conditions]

Cylinder temperature: 350℃

Mold temperature: 80℃

Injection speed: 100 mm/sec

[evaluation]

The test piece was placed in an ultrasonic cleaner (output 300 W, frequency 45 kHz) in room temperature water (80 mL) for 3 minutes. Then, the number of particles of 2 μm or more present in the water was measured with a particle counter (manufactured by RION Co., Ltd., KL-11A (PARTICLE COUNTER), a particle counter in liquid, and the number of dust generation was evaluated according to the following criteria. Results are shown in Table 1 to shown in 3.

○ (Good): The number of dust generation was 60000/80ml or less.

× (defective): The number of dust generated was more than 60000/80 ml.

As is clear from the results shown in Tables 1 to 3, the molded articles of the examples are excellent in balance in suppression of surface whitening, mechanical strength, dimensional accuracy, and low dust generation, and at the same time, not only the ball bearing sliding wear resistance is reduced, but also the impact resistance is excellent. confirmed to be maintained.

Claims (4)

(A) a liquid crystalline resin;
(B) a granular filler, and
(C) whiskers
contains,
The median diameter of the (B) granular filler is 0.3 to 5.0 μm,
The content of the (B) granular filler is 7.5 to 22.5% by mass,
The content of the (C) whisker is 2.5 to 17.5% by mass,
The liquid crystalline resin composition for a ball bearing sliding wear resistant member, wherein the total content of the granular filler (B) and the whiskers (C) is 12.5 to 32.5% by mass. According to claim 1,
The (B) granular filler is at least one selected from the group consisting of silica and barium sulfate, a liquid crystal resin composition for a ball bearing sliding wear resistant member. According to claim 1 or 2,
Further (D) containing an epoxy group-containing copolymer,
The content of the epoxy group-containing copolymer (D) is 1 to 5% by mass, the liquid crystal resin composition for a ball bearing sliding wear resistant member. A ball bearing sliding wear resistant member comprising the liquid crystal resin composition for a ball bearing sliding wear resistant member according to any one of claims 1 to 3.

Images