WO2012169279A1 - Resin composition, resin composition for optical pickup, and molded body for optical pickup - Google Patents

Abstract

Provided are: a resin composition which has excellent dimensional stability, moldability (in particular, thin-wall moldability), mechanical strength, adhesiveness and heat dissipation performance; a resin composition for optical pickup; and a molded body for optical pickup, which is obtained by molding the resin composition and is reduced in burr formation and optical axis shift, while having excellent weld strength. The resin composition is characterized by specifically containing 100 parts by mass of a resin composition that is composed of 60-96% by mass of (A) a liquid polymer and 40-4% by mass of (B) a polyarylene sulfide and 30-60 parts by mass of (C) graphite. The resin composition may contain 30-50 parts by mass of (D) a non-fibrous inorganic filler and 20-50 parts by mass of (E) a fibrous inorganic filler, if necessary.

Description

Resin composition, resin composition for optical pickup, and molded article for optical pickup

The present invention relates to a resin composition, a resin composition for optical pickup, and a molded article for optical pickup formed by molding the resin composition.

Conventionally, optical pickups such as CD, DVD, and Blu-Ray have been manufactured by metal die casting such as aluminum die casting and zinc die casting. However, in recent years, with the increasing needs for reducing the cost and weight of products, the use of optical pickups as a resin has begun to be studied, and materials are gradually being replaced from metals to resins. Therefore, resin materials for optical pickups have dimensional accuracy, dimensional stability, moldability (fluidity), mechanical strength, rigidity, and environmental resistance during (injection) molding, depending on the function of each optical component. Characteristics such as (heat resistance, moisture resistance, chemical resistance, etc.), heat dissipation, and flame retardancy are required.
Further, in recent years, when the recording density and speeding up of CD, DVD, etc. are increased, among these characteristics, the optical axis shift of the optical system with respect to dimensional stability, in particular, environmental (temperature, humidity, etc.) changes is reduced. However, it has been strictly demanded. On the other hand, with the aim of reducing the weight of the optical pickup and space-saving, a part of the housing is thinned, and with the spread of notebook personal computers, the slim optical pickup is being made resin.
Conventionally, a resin composition containing polyphenylene sulfide (PPS) has often been used as a resin material for an optical pickup (see, for example, Patent Document 1). In addition, a liquid crystal polymer (LCP) resin composition may be used mainly for improving moldability and low burr, and a plate is used to reduce anisotropy in the LCP resin composition. A resin composition improved by adding a filler in a shape is also known (see Patent Document 2).

Japanese Patent Laid-Open No. 2001-294751 JP-A 63-146959

However, PPS resin compositions for optical pickups that have been used in the past have not been able to improve the above characteristics, particularly dimensional stability, moldability (fluidity), mechanical strength, heat dissipation, etc. in a well-balanced manner. In particular, it is difficult to apply to thin products such as optical pickup parts of slim type (molded product height (maximum thickness) about 5 mm) and ultra slim type (molded product height (maximum thickness) of about 3 mm). It was.
On the other hand, the LCP resin composition is superior to the PPS resin composition in terms of moldability and low burr, but due to its low adhesiveness, the fixing accuracy of the optical component is not sufficiently exhibited, or the anisotropy of the material characteristics Therefore, there is a problem that the optical characteristics are not sufficiently developed because the molded product is deformed, and it can be applied only to extremely limited uses such as a lens holder.
Then, the subject of this invention is a resin composition excellent in dimensional stability, moldability (especially thin moldability), mechanical strength, adhesiveness, and heat dissipation, the resin composition for optical pick-ups, and this resin composition. An object of the present invention is to provide a molded article for an optical pickup which is molded and has low burr properties, optical axis deviation is suppressed, and excellent weld strength.

As a result of intensive studies on the above problems, the present inventors have found that if the resin composition contains a liquid crystal polymer (LCP), polyarylene sulfide and graphite, good characteristics for optical pickup, that is, dimensional stability, It is excellent in moldability (particularly thin-wall moldability), mechanical strength, adhesiveness and heat dissipation, and if it is a molded article for optical pickups formed by molding the resin composition, it has low burr and optical axis misalignment. Has been found to be suppressed and the weld strength is excellent, and the present invention has been completed.

That is, the present invention relates to the following [1] to [5].
[1] It comprises 100 parts by mass of (A) a liquid crystal polymer 60 to 96% by mass and (B) a polyarylene sulfide 40 to 4% by mass, and (C) graphite 30 to 60 parts by mass. A resin composition.
[2] The resin composition according to [1], which is used for an optical pickup.
[3] The resin composition according to [1] or [2], further comprising (D) 30 to 50 parts by mass of a non-fibrous inorganic filler.
[4] The resin composition according to any one of [1] to [3], further comprising (E) 20 to 50 parts by mass of a fibrous inorganic filler.
[5] A molded article for an optical pickup obtained by molding the resin composition according to any one of [1] to [4].

According to the present invention, a resin composition and an optical pickup resin composition that are excellent in dimensional stability, moldability (particularly thin-wall moldability), mechanical strength, adhesiveness, and heat dissipation, and low burr properties, optical axis It is possible to provide a molded article for an optical pickup that is suppressed in deviation and excellent in weld strength. By using the resin composition, it is possible to provide an optical pickup of a slim type (a molded product height (maximum thickness) of about 5 mm) or an ultra slim type (a molded product height (maximum thickness) of about 3 mm). .

It is a photograph which shows the external appearance of the optical pick-up housing model type | mold with a thickness of 2.0 mm used in the Example and the comparative example. It is a photograph which supplements description of the evaluation method of the weld strength of an optical pick-up housing model type in an Example and a comparative example.

[Resin composition]
The resin composition of the present invention comprises (A) 60 to 96% by mass of a liquid crystal polymer and (B) 100 parts by mass of a resin composition comprising 40 to 4% by mass of polyarylene sulfide, and (C) 30 to 60 parts by mass of graphite. It is a resin composition characterized by containing.
First, each component of the resin composition of this invention is demonstrated in detail below.

((A) Liquid Crystal Polymer (LCP))
The liquid crystal polymer exhibits a liquid crystal-like property in which a linear chain of molecules is regularly arranged in a molten state, and is usually an aromatic polyester-based resin, and is also referred to as a liquid crystal polyester. As the liquid crystal polymer, a thermotropic liquid crystal polymer (thermotropic liquid crystal polyester) is preferably used. As the liquid crystal polymer, those that form an anisotropic melt at a temperature of 400 ° C. or lower are preferably used.
The liquid crystal polymer includes (1) a structural unit derived from an aromatic hydroxycarboxylic acid [hereinafter sometimes referred to as a structural unit (1)], (2) a structural unit derived from an aromatic dicarboxylic acid [hereinafter referred to as a structural unit ( 2)], and (3) at least one of structural units derived from an aromatic diol [hereinafter sometimes referred to as structural unit (3)]. When the liquid crystal polymer has the structural unit (2), it also has the structural unit (1) and / or (3). When the liquid crystal polymer has the structural unit (3), the structural unit (1) and / or (2) Also have.

　これらの構造単位は、芳香族環上にアルキル基、ハロゲン原子、アリール基等の置換基を有していてもよい。アルキル基としては、メチル基、エチル基、各種プロピル基（「各種」は、直鎖状及びあらゆる分岐鎖状を含むことを示し、以下同様である。）、各種ブチル基、各種ペンチル基などが挙げられ、炭素数１～５のアルキル基が好ましく、炭素数１～３のアルキル基がより好ましく、メチル基がさらに好ましい。ハロゲン原子としては、例えば、フッ素原子、塩素原子、臭素原子、ヨウ素原子などが挙げられる。アリール基としては、フェニル基、ナフチル基、ビフェニレン基などが挙げられ、環形成炭素数６～２０のアリール基が好ましく、環形成炭素数６～１２のアリール基がより好ましく、フェニル基がさらに好ましい。
　液晶ポリマー中には、（１）芳香族ヒドロキシカルボン酸に由来する構造単位を１つだけ有していてもよいし、２つ以上を有していてもよい。 Examples of the structural unit derived from the (1) aromatic hydroxycarboxylic acid include structural units represented by the following formulae.

These structural units may have a substituent such as an alkyl group, a halogen atom, or an aryl group on the aromatic ring. Examples of the alkyl group include a methyl group, an ethyl group, various propyl groups (“various” indicates linear and all branched chains, the same shall apply hereinafter), various butyl groups, various pentyl groups, and the like. An alkyl group having 1 to 5 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is more preferable. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the aryl group include a phenyl group, a naphthyl group, and a biphenylene group. An aryl group having 6 to 20 ring carbon atoms is preferable, an aryl group having 6 to 12 ring carbon atoms is more preferable, and a phenyl group is more preferable. .
The liquid crystal polymer may have (1) only one structural unit derived from aromatic hydroxycarboxylic acid, or may have two or more.

　これらの構造単位は、芳香族環上にアルキル基、ハロゲン原子、アリール基等の置換基を有していてもよい。該アルキル基、ハロゲン原子、アリール基としては、前記同様のものが例示でき、好ましいものも同じである。液晶ポリマー中には、（２）芳香族ジカルボン酸に由来する構造単位を１つだけ有していてもよいし、２つ以上を有していてもよい。 Examples of the structural unit derived from the aromatic dicarboxylic acid (2) include structural units represented by the following formulas.

These structural units may have a substituent such as an alkyl group, a halogen atom, or an aryl group on the aromatic ring. Examples of the alkyl group, halogen atom and aryl group are the same as those described above, and preferred ones are also the same. The liquid crystal polymer may have only one structural unit derived from (2) an aromatic dicarboxylic acid, or may have two or more.

　これらの構造単位は、芳香族環上にアルキル基、ハロゲン原子、アリール基等の置換基を有していてもよい。該アルキル基、ハロゲン原子、アリール基としては、前記同様のものが例示でき、好ましいものも同じである。液晶ポリマー中には、（３）芳香族ジオールに由来する構造単位を１つだけ有していてもよいし、２つ以上を有していてもよい。 Examples of the structural unit derived from the (3) aromatic diol include structural units represented by the following formulae.

These structural units may have a substituent such as an alkyl group, a halogen atom, or an aryl group on the aromatic ring. Examples of the alkyl group, halogen atom and aryl group are the same as those described above, and preferred ones are also the same. The liquid crystal polymer may have only one structural unit derived from (3) an aromatic diol, or may have two or more.

From the viewpoint of the heat resistance of the liquid crystal polymer and the resin composition, in order to increase the flow start temperature of the liquid crystal polymer, it is preferable to improve the linearity of the molecular chain. It preferably has no substituent.

(A) As a component, it is more preferable that it has (1) the structural unit derived from aromatic hydroxycarboxylic acid, (1) Two or more structural units derived from aromatic hydroxycarboxylic acid It is more preferable that it has, and it is particularly preferable that it has the following two structural units derived from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Further, the proportion of the structural unit derived from p-hydroxybenzoic acid and the structural unit derived from 6-hydroxy-2-naphthoic acid is from the viewpoint of the heat resistance and mechanical strength of the liquid crystal polymer and the resin composition. The ratio is preferably 1:99 to 99: 1, more preferably 10:90 to 99: 1, still more preferably 30:70 to 99: 1, and 55:45 to 95: 5 is particularly preferred.

(Method for producing liquid crystal polymer)
There is no restriction | limiting in particular in the manufacturing method of liquid crystal polymer (liquid crystal polyester), It can manufacture by a well-known method. For example, an acylated product is obtained by acylating a phenolic hydroxyl group possessed by an aromatic diol or aromatic hydroxycarboxylic acid with a fatty acid anhydride such as acetic anhydride, and the resulting acylated product has an aromatic group and an aromatic group. A liquid crystal polymer can be produced by polymerizing the carboxyl group of the acylated product of dicarboxylic acid or aromatic hydroxycarboxylic acid so as to cause transesterification.
Moreover, the liquid crystal polymer (liquid crystal polyester) is marketed, and a commercial item may be used.

（式中、Ｒ¹は、炭素数１～５のアルキル基、炭素数１～５のアルコキシ基、フェニル基、カルボキシル基、カルボン酸金属塩基、アミノ基、ニトロ基、ハロゲン原子を表す。ｍは０～４の整数を表す。）
　Ｒ¹が表す炭素数１～５のアルキル基としては、メチル基、エチル基、各種プロピル基、各種ブチル基、各種ペンチル基が挙げられる。炭素数１～５のアルコキシ基としては、メトキシ基、エトキシ基、各種プロポキシ基、各種ブトキシ基、各種ペンチルオキシ基が挙げられる。カルボン酸金属塩基の金属塩としては、例えば、ナトリウム塩、カリウム塩等のアルカリ金属塩が挙げられる。ハロゲン原子としては、例えばフッ素原子、塩素原子、臭素原子、ヨウ素原子などが挙げられる。
　ｍは、好ましくは０又は１であり、より好ましくは０である。 ((B) polyarylene sulfide)
Component (B) is a structural formula — [Ar—S] — (wherein Ar represents an arylene group having 6 to 12 ring carbon atoms) from the viewpoint of heat resistance and mechanical properties of polyarylene sulfide and the resin composition. The polymer containing 70 mol% or more (more preferably 90 mol% or more) of the repeating unit represented by formula (I) is preferred, and the repeating unit represented by the following structural formula (I) is 70 mol% or more (more preferably). 90 mol% or more) is more preferable, and polyphenylene sulfide (PPS) is more preferable.

(Wherein R ¹ represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a carboxyl group, a carboxylate metal base, an amino group, a nitro group, or a halogen atom. Represents an integer of 0 to 4.)
Examples of the alkyl group having 1 to 5 carbon atoms represented by R ¹ include a methyl group, an ethyl group, various propyl groups, various butyl groups, and various pentyl groups. Examples of the alkoxy group having 1 to 5 carbon atoms include methoxy group, ethoxy group, various propoxy groups, various butoxy groups, and various pentyloxy groups. Examples of the metal salt of the carboxylic acid metal base include alkali metal salts such as sodium salt and potassium salt. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
m is preferably 0 or 1, more preferably 0.

（式中、Ｒ¹及びｍは、前記定義の通りであり、好ましいものも同じである。） The repeating unit represented by the structural formula (I) is preferably a repeating unit represented by the following structural formula (I ′).

(In the formula, R ¹ and m are as defined above, and preferred ones are also the same.)

Polyarylene sulfide is generally linear according to its production method, and has a molecular structure that does not have a branched or crosslinked structure (linear type), and has a structure that has a branched or crosslinked structure by a thermal crosslinking method (crosslinked type). The semi-linear type (semi-crosslinked type) is known, but any type of the type is effective in the present invention. In addition, a branched or cross-linked polyarylene sulfide obtained by polymerization using a small amount of monomers having three or more functional groups can also be effectively used as the monomer.
Among these, the polyarylene sulfide is preferably a linear type or a semi-linear type, and more preferably a semi-linear type, from the viewpoint of mechanical strength and the like.

The polyarylene sulfide may contain structural units other than the repeating units represented by the structural formula —Ar—S— (wherein Ar represents an arylene group having 6 to 12 ring carbon atoms). For example, a structural unit derived from p, p'-diphenylene ketone sulfide, a structural unit derived from p, p'-diphenylenesulfone sulfide, a structural unit derived from p, p'-biphenylene sulfide, p, p'- Structural units derived from diphenylene ether sulfide, structural units derived from p, p′-diphenylenemethylene sulfide, structural units derived from p, p′-diphenylenecumenyl sulfide, structural units derived from naphthyl sulfide, etc. Can be mentioned.
Furthermore, the polyarylene sulfide may be a mixture of two or more polyarylene sulfides.

The polyarylene sulfide is prepared by, for example, using a dihalogenated aromatic compound (for example, p-dichlorobenzene) and a sulfur source (for example, sodium sulfide) in an organic polar solvent (for example, N-methylpyrrolidone) and the like (for example, an alkali of a carboxylic acid). It can be produced by reacting in the presence of a metal salt, water or the like. Polyarylene sulfide is commercially available, and a commercially available product may be used.
The polyarylene sulfide used in the present invention has a melt viscosity at a resin temperature of 300 ° C. and a shear rate of 1200 sec ⁻¹ , preferably 5 to 500 Pa · s, more preferably 5 to 200 Pa · s, more preferably 5 to 100 Pa · s, More preferably, it is 5 to 50 Pa · s. If this melt viscosity is 500 Pa · s or less, the fluidity at the time of molding is not lowered and the dimensional accuracy of the molded body is not deteriorated, and the optical axis shift of the optical pickup can be suppressed. Further, when the melt viscosity is 5 Pa · s or more, the mechanical strength is practically preferable.

In the resin composition of the present invention, the blending amount of component (B) is 4 to 40% by mass, preferably 4 to 35% by mass, more preferably based on the total amount of component (A) and component (B). Is 10 to 35% by mass, more preferably 20 to 35% by mass, and particularly preferably 20 to 30% by mass. If it exceeds 40% by mass, the mechanical strength and weld strength will be reduced, and the low burr property may be significantly reduced to contaminate the optical system of the optical pickup. If it is less than 4% by mass, the dimensional stability will be increased. The optical axis shift increases and the adhesiveness decreases, and in any case, it is difficult to use the optical pickup.

((C) graphite)
As the graphite, natural graphite can be used without particular limitation. For example, earth graphite and scale graphite may be used, or spheroidized graphite and exfoliated graphite may be used. It is also possible to use artificial graphite obtained by molding and firing petroleum coke or the like and further graphitizing at ultra-high temperature. From the viewpoint of production cost, it is preferable to use natural graphite. Among natural graphites, scaly graphite is preferable from the viewpoint of moldability and heat dissipation of the resin composition.
The average particle diameter (50% cumulative diameter) of graphite is not particularly limited, but from the viewpoint of the mechanical strength of the resin composition, it is preferably about 20 to 180 μm, more preferably 20 to 150 μm, more preferably 20 to The thickness is 100 μm, more preferably 20 to 60 μm, particularly preferably 40 to 60 μm. In addition, the average particle diameter of graphite can be measured by a laser diffraction scattering method according to JIS R1629.

In the resin composition of the present invention, the blending amount of the component (C) is 30 to 60 parts by mass, preferably 40 to 60 parts by mass with respect to 100 parts by mass in total of the component (A) and the component (B). More preferably, it is 40 to 50 parts by mass. If it is less than 30 parts by mass, the heat dissipation is not sufficient, and the heat dissipation necessary for maintaining the performance of the optical pickup is insufficient. On the other hand, when it exceeds 60 parts by mass, the moldability is lowered, and the mechanical strength and the weld strength are remarkably lowered.

((D) non-fibrous inorganic filler)
The resin composition of the present invention may further contain (D) a non-fibrous inorganic filler in addition to the above components.
Non-fibrous inorganic fillers include, for example, clay minerals (silicates) such as sericite, kaolin, mica, clay, bentonite, talc, alumina silicate; silicon oxide; alumina, magnesium oxide, zirconium oxide, titanium oxide, iron oxide Metal oxides such as; carbonates of alkaline earth metals such as calcium carbonate, magnesium carbonate, dolomite; sulfates of alkaline earth metals such as calcium sulfate and barium sulfate; glass beads, ceramic beads, boron nitride, silicon carbide, Examples thereof include calcium phosphate and silica. Among these, clay mineral (silicate) is preferable, and talc is more preferable.
The non-fibrous inorganic filler may be pretreated with a silane or titanate coupling agent to increase mechanical strength.
A non-fibrous inorganic filler may be used individually by 1 type, and may use 2 or more types together.
When the resin composition of the present invention contains the component (D), the content of the component (D) is preferably 20 to 60 masses with respect to a total of 100 parts by mass of the components (A) and (B). Part, more preferably 30 to 50 parts by weight, still more preferably 40 to 50 parts by weight. If it is 20 parts by mass or more, the dimensional stability is good, and if it is 60 parts by mass or less, the moldability is good, and the mechanical strength and the weld strength are good.

((E) Fibrous inorganic filler)
The resin composition of the present invention may further contain (E) a fibrous inorganic filler in addition to the above components.
Examples of the fibrous inorganic filler include glass fibers, carbon fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, metal fibers, whiskers such as potassium titanate whisker, zinc oxide whisker, and calcium carbonate whisker. And fillers, wollastonite and asbestos. Among these, glass fiber is preferable.
The fibrous inorganic filler may be pretreated with a silane or titanate coupling agent to increase mechanical strength.
Examples of the shape of the fibrous inorganic filler include a cloth shape, a mat shape, a focused cut (chopped strand) shape, a short fiber, and a filament shape, and a convergent cut shape is preferable. In the case of focused cutting, the average fiber diameter is preferably 5 to 20 μm (more preferably 8 to 15 μm), and the average fiber length is preferably 1 to 5 mm (more preferably 2 to 4 mm).
A fibrous inorganic filler may be used individually by 1 type, and may use 2 or more types together.
When the resin composition of the present invention contains the component (E), the content of the component (E) is preferably 15 to 60 masses with respect to a total of 100 parts by mass of the components (A) and (B). Part, more preferably 20 to 50 parts by weight, still more preferably 30 to 45 parts by weight. If it is 15 parts by mass or more, the mechanical strength is good and the impact resistance strength when the optical pickup is dropped is good. Moreover, if it is 60 mass parts or less, anisotropy will not arise in a material characteristic and weld strength will become favorable.

(Other ingredients)
Unless the effects of the present invention are significantly impaired, the resin composition of the present invention is an antioxidant such as hindered phenol, hydroquinone and phosphite, and an ultraviolet absorber such as a heat stabilizer, resorcinol, salicylate, benzotriazole and benzophenone. In addition, various additives such as an antistatic agent, a flame retardant, a nucleating agent, and a pigment may be contained.

(Resin composition preparation method and molding method)
The method for preparing the resin composition of the present invention is not particularly limited. For example, after each component is uniformly mixed with a mixer such as a tumbler mixer or a Henschel mixer, it is preferably 250 to 250 with a single screw extruder or twin screw extruder. The resin composition of the present invention can be obtained by melt-kneading at 380 ° C. (more preferably 280 to 350 ° C.). Furthermore, it can be molded by a normal molding method such as injection molding, extrusion molding, solvent molding, press molding, thermoforming, or the like.

(Physical properties and characteristics of a molded product obtained by molding a resin composition)
The molded body formed by molding the resin composition of the present invention has a breaking load immediately after bonding measured by the method described in the examples of 3 kgf or more, and preferably 3.3 to 3.6 kgf. Excellent in properties. Further, the fracture load after the heat shock test after bonding is 3 kgf or more, and preferably 3.7 to 4.1 kgf, which is excellent in adhesiveness.
The thermal conductivity measured by the method described in the examples is 6 W / m · K or more, approximately 6.2 to 7.8 W / m · K, and has excellent heat dissipation. The spiral flow length measured by the method described in the examples is 200 to 270 mm, more specifically 230 to 260 mm, and the moldability is excellent. The tensile strength measured by the method described in Examples is 70 MPa or more, approximately 70 to 92 MPa, and is excellent in mechanical strength. Similarly, the bending strength is 120 MPa or more, and is approximately 123 to 140 MPa, which is excellent in mechanical strength. Similarly, the Izod impact strength is 5 kJ / m ² or more, approximately 5.2 to 9.3 kJ / m ² , and is excellent in impact resistance.
The linear expansion coefficient is measured according to the method described in example, MD direction is approximately ^{0.7 × 10 -5 /K~1.2×10 -5 / K} , TD direction roughly 1.0 × a 10 ^-5 /K~1.7×10 ^-5 / K, excellent dimensional stability.
Further, the molded article for optical pickup of the present invention has a low burr property, and the optical axis deviation measured by the method described in Examples is within 2.5 minutes, and preferably 0.9 to 2.3. Minutes, more preferably 0.9 to 1.6 minutes, and the optical axis deviation is small. The weld strength measured by the method described in the examples is 10 kgf or more, and is approximately 11.8 to 15.3 kgf, and the weld strength is excellent.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

<Examples 1 to 6, Comparative Examples 1 to 4>
After each component was uniformly mixed using a Henschel mixer at each compounding amount (unit: part by mass) shown in Table 1, this extruder was used using a twin screw extruder “TEM35” (manufactured by Toshiba Machine Co., Ltd.). The cylinder temperature was set to 320 ° C. and melt-kneaded to produce pellets.
Using the obtained pellets, adhesion, heat dissipation (thermal conductivity), moldability (fluidity), tensile strength, bending strength, Izod impact strength and dimensional stability (linear expansion coefficient) are as follows. Measured and evaluated. Furthermore, characteristics as an optical pickup, that is, burr properties, optical axis misalignment, and weld strength were measured and evaluated.

(1. Adhesiveness)
A flat plate of 80 × 80 × 3.2 mm was formed with a 50T injection molding machine manufactured by Nippon Steel Works, and used as a sample. A hole of φ5 mm was made in the flat plate, and an aluminum plate of 10 × 10 × 2 mm was fixed with an adhesive “8813” (manufactured by Kyoritsu Chemical Industry Co., Ltd.) so as to close the hole from one side. Adhesive locations were four corners of the aluminum plate, and 5 mg of the adhesive was used at each location. After the adhesive was cured, the maximum load (unit: kgf) when the aluminum plate was pushed out from the opening side of the hole was measured using a force gauge.
The above adhesion test was conducted for both the initial state immediately after bonding and the state after 100 cycles of the heat shock test at −40 ° C. (30 minutes) to 85 ° C. (30 minutes).
It can be said that the adhesiveness is good when the breaking load is 3 kgf or more.
(2. Heat dissipation)
A flat plate of 80 × 80 × 3.2 mm was formed by a 50T injection molding machine manufactured by Nippon Steel Co., Ltd. and used as a sample, and the thermal conductivity was measured by the hot disk method, and used as a heat dissipation index. Specifically, UNITHERM ^™ 2021 (manufactured by ANTER) was used, and the thermal conductivity at 23 ° C. was measured. It shows that it is excellent in heat dissipation, so that heat conductivity is high.
(3. Formability (fluidity))
Spiral flow length: 30-ton injection molding machine (manufactured by Toshiba Machine Co., Ltd.) using a spiral flow mold with a thickness of 1 mm under conditions of a resin temperature of 320 ° C., a mold temperature of 135 ° C., and an injection pressure of 100 MPa. A 1 mm test piece was prepared, and the spiral flow length at that time was measured. The spiral flow length was used as an index of moldability (fluidity). When the spiral flow length is 200 to 270 mm, the moldability (fluidity) is good.
(4. Tensile strength)
Tensile strength was measured according to ASTM D638.
(5. Bending strength)
The bending strength was measured according to ASTM D790.
(6. Izod impact strength)
Izod impact strength was measured according to ASTM D256.
(7. Dimensional stability (linear expansion coefficient))
The linear expansion coefficient was measured in accordance with ASTM E831, and used as an index of dimensional stability.

[8. Evaluation of each characteristic in optical pickup housing]
The pellets were injection molded with an optical pickup housing model mold, and the following tests were performed with the main shaft and the sub shaft fixed by the shaft. The optical pickup housing model used for the test has the outer shape shown in FIG.
(8.1. Burriness)
The abutting pin hole of φ2.8 mm in the optical pickup housing model was observed with an optical microscope, the presence or absence of burrs was visually judged, and the degree of low burr was evaluated according to the following evaluation criteria.
A: There is no burr at all.
○: Although burr was recognized, it was very small and it was not necessary to remove the burr.
X: The burr is large and needs to be removed.
(8.2. Optical axis misalignment)
Use an autocollimator to adjust the tilt of the return light with a reference sample made of quartz glass to 0 minutes, then install a reflect mirror on the optical pickup housing, and fix the main and secondary axes with the shaft. The optical axis inclination of the reflected return light was measured.
Next, a cylindrical oven with a diameter of 20 cm, a mechanism that irradiates laser light perpendicularly to the center of the oven, and a laser autocollimator “MTS-2” that measures the reflection angle of the reflected light of the laser (Nissho Electronics Corporation) Was measured as follows. First, a half mirror was set at a predetermined position on the optical pickup housing model. Next, the optical pickup housing model was fixed in the oven so that the half mirror surface was horizontal, and the reflection angle was measured by irradiating with laser light at room temperature (23 ° C.). Subsequently, the oven was kept at 80 ° C. for 60 minutes, and then the laser beam was irradiated again to measure the reflection angle. The difference between the reflection angle at 80 ° C. and the reflection angle at room temperature (23 ° C.) was defined as the deviation of the optical axis (unit: minutes). The resolution of the non-contact angle measuring mechanism is 0.02 minutes.
The optical axis shift is preferably within 2.5 minutes.
(8.3. Weld strength)
As shown in FIG. 2, only one (right side) of the main shaft portion of the optical pickup housing model type and the sub shaft portion are passed through a shaft fixed to a metal jig, the main shaft portion is moved upward, and the sub shaft portion. Was installed vertically. A load (unit: kgf) at which the right main shaft portion through the shaft was broken was determined by applying a load with a force gauge to the main shaft portion not passing through the shaft.
It is preferable that the breaking load is 10 kgf or more because the weld strength of the main shaft portion is high.

(Explanation of notes in Table 1)
* 1: Liquid crystal polymer “A-2500”, liquid crystal polyester composed of a structural unit derived from p-hydroxybenzoic acid and a structural unit derived from 6-hydroxy-2-naphthoic acid, manufactured by Ueno Pharmaceutical Co., Ltd. * 2: Polyphenylene sulfide “H1G”, semi-linear PPS, melt viscosity at 300 ° C. and 1200 / s, 10 to 20 PaS, manufactured by DIC Corporation * 3: Scalar graphite “CB-150”, average particle size 50 μm, manufactured by Nippon Graphite Industries Co., Ltd. * 4 : “MS-K”, manufactured by Nippon Talc Co., Ltd. * 5: “CS 03 JA FT 591”, chopped strand (convergence cut) type, average fiber diameter 10 μm, average fiber length 3 mm, manufactured by Owens Corning

From Table 1, the resin composition of the present invention is excellent in dimensional stability, moldability (particularly thin moldability), mechanical strength, adhesiveness and heat dissipation, and when used as a molded article for an optical pickup, It can be seen that the burrs are low, the optical axis deviation is suppressed, and the weld strength is excellent.
On the other hand, when the component (B) is not contained (Comparative Example 1), the adhesiveness of the resin composition is lowered, and there is a problem that the optical axis deviation is large when the molded article for optical pickup is used. I understand. When the content ratio of the component (A) and the component (B) was inappropriate (Comparative Example 2), many burrs were observed when the molded article for optical pickup was used, and the weld strength was further reduced. When the content of the component (C) is small (Comparative Example 3), in the case of a molded article for optical pickup, the optical axis shift is large, while when the content of the component (C) is large (Comparative Example 4), The weld strength was low when the initial adhesiveness was poor and the molded article for optical pickup was used.

The resin composition of the present invention is excellent in dimensional stability, moldability (particularly thin moldability), mechanical strength, adhesiveness and heat dissipation, and a molded body using the resin composition has low burr properties. Since the optical axis deviation is suppressed and the weld strength is excellent, it is useful for optical pickups such as CDs and DVDs. The optical pickup molded body includes a holding container, an optical pickup base, and the like. Especially when the optical pickup base is applied to the optical pickup base, the optical axis even when the optical pickup device using the base is placed at a high temperature exceeding 70 ° C. The effect of suppressing the deviation is remarkable. Therefore, it is useful to use the molded product of the resin composition of the present invention as a large recording capacity and writable optical pickup parts such as CD-R, CD-RW, and DVD-RAM, particularly as an optical pickup base. It is.

Claims (5)

A resin comprising 100 parts by weight of a resin composition comprising (A) 60 to 96% by weight of a liquid crystal polymer and (B) 40 to 4% by weight of polyarylene sulfide, and (C) 30 to 60 parts by weight of graphite. Composition. The resin composition according to claim 1, which is used for an optical pickup. The resin composition according to claim 1 or 2, further comprising (D) 30 to 50 parts by mass of a non-fibrous inorganic filler. The resin composition according to any one of claims 1 to 3, further comprising (E) 20 to 50 parts by mass of a fibrous inorganic filler. A molded article for an optical pickup formed by molding the resin composition according to any one of claims 1 to 4.

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