JP2013108008A - Liquid crystalline polyester composition, molded article, and optical pick-up lens holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded article having high specific modulus and a loss coefficient, an optical pick-up lens holder using the molded article, and a liquid crystalline polyester composition for producing the molded article.SOLUTION: There is provided the liquid crystalline polyester composition containing 10-25 pts.mass of a fibrous filler which satisfies the items: (a) more than 6.5 of Mohs hardness; and (b) 100 or more of an aspect ratio, based on 100 pts.mass of the liquid crystalline polyester, and a hollow filler. There are also provided the molded article formed by the liquid crystalline polyester composition, and the optical pick-up lens holder having a bobbin formed of the molded article.

Description

  The present invention relates to a liquid crystal polyester composition, a molded body using the liquid crystal polyester composition, and an optical pickup lens holder using the molded body.

  The optical pickup member is desired to be reduced in weight, and conventionally, attempts have been made to replace the constituent metal with a resin. In particular, a liquid crystal polyester composition blended with glass fiber is adopted as an optical pickup member because it is excellent in mechanical properties, moldability, dimensional accuracy, heat resistance and vibration damping properties among resin materials.

  However, with the recent increase in the capacity and speed of information handled by digital disk drive devices, the demand for vibration suppression has become more severe. As a countermeasure, the secondary resonance frequency is shifted to the high frequency side and the gain width is increased in the optical pickup member, that is, the rigidity of the optical pickup member is increased (resonance frequency is specific elastic modulus (elastic modulus is specific gravity). However, it is clear that conventional liquid crystal polyester compositions cannot sufficiently meet this requirement.

  So far, as a liquid crystal polyester composition suitable for an optical pickup member, a resin composition comprising liquid crystal polyester and aluminum borate whisker has been disclosed (for example, see Patent Document 1). Moreover, the resin composition which consists of liquid crystal polyester, glass fiber, and a spherical hollow body is disclosed for the purpose of weight reduction (for example, refer patent document 2).

Japanese Patent Laid-Open No. 11-80517 JP 2004-143270 A

  However, the molded article using the liquid crystal polyester composition disclosed in Patent Document 1 has a problem that the specific modulus cannot be sufficiently increased because of its large specific gravity. Moreover, since the molded object using the liquid crystal polyester composition currently disclosed by patent document 2 has a low elastic modulus, there existed a problem that a specific elastic modulus could not be made high. Thus, these molded products have insufficient specific rigidity, and it has been strongly desired to increase the specific elastic modulus.

  In addition, the molded body using the liquid crystal polyester composition disclosed in Patent Documents 1 and 2 has a problem that vibration damping performance is still insufficient because of a small loss coefficient. Since the reciprocal of the loss coefficient is proportional to the number of vibrations during vibration, the smaller the reciprocal of the loss coefficient (that is, the greater the loss coefficient), the faster the vibration is settled and the better the damping performance.

  The present invention has been made in view of the above circumstances, and has a molded article having a high specific modulus and a large loss coefficient, an optical pickup lens holder using the molded article, and a liquid crystal for producing the molded article. It is an object to provide a polyester composition.

To solve the above problem,
The present invention provides a liquid crystal polyester composition comprising 10 to 25 parts by mass of a fibrous filler that satisfies the following requirements (a) and (b) and 100 parts by mass of a liquid crystal polyester: To do.
(A) Mohs hardness is greater than 6.5.
(B) The aspect ratio is 100 or more.
In the liquid crystal polyester composition of the present invention, the hollow filler is preferably contained in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.
In the liquid crystal polyester composition of the present invention, the liquid crystal polyester preferably has a flow start temperature of 360 ° C. or higher.
In the liquid crystal polyester composition of the present invention, the volume average particle size of the hollow filler is preferably 10 to 40 μm.

Moreover, this invention provides the molded object formed by shape | molding the liquid-crystal polyester composition of the said invention.
The present invention also provides an optical pickup lens holder comprising a bobbin made of the molded article of the present invention.

  According to the present invention, it is possible to provide a molded article having a high specific modulus and a large loss coefficient, an optical pickup lens holder using the molded article, and a liquid crystal polyester composition for producing the molded article.

It is the schematic which illustrates one Embodiment of the optical pick-up lens holder which concerns on this invention.

<Liquid crystal polyester composition>
The liquid crystalline polyester composition according to the present invention is a fibrous filler that satisfies the following requirements (a) and (b) with respect to 100 parts by mass of the liquid crystalline polyester (hereinafter sometimes simply referred to as “fibrous filler”) 10. It contains ˜25 parts by mass and a hollow filler.
(A) Mohs hardness is greater than 6.5.
(B) The aspect ratio is 100 or more.
Such a molded article has excellent specific rigidity due to its high specific modulus, and excellent vibration damping due to its large loss coefficient.

  The liquid crystalline polyester is a liquid crystalline polyester that exhibits liquid crystallinity in a molten state, and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

As a typical example of liquid crystal polyester,
(I) An aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine are polymerized (polycondensed). thing,
(II) a polymer obtained by polymerizing plural kinds of aromatic hydroxycarboxylic acids,
(III) A polymer obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine and an aromatic diamine,
(IV) What polymerizes polyester, such as a polyethylene terephthalate, and aromatic hydroxycarboxylic acid is mentioned. Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine, and the aromatic diamine are each independently replaced with a part or all of the polymerizable derivative. Also good.

Examples of polymerizable derivatives of a compound having a carboxyl group such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxyl Examples include those obtained by converting a group into a haloformyl group (acid halide), and those obtained by converting a carboxyl group into an acyloxycarbonyl group (acid anhydride).
Examples of polymerizable derivatives of hydroxyl group-containing compounds such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines include those obtained by acylating hydroxyl groups and converting them to acyloxyl groups (acylated products) ).
Examples of polymerizable derivatives of amino group-containing compounds such as aromatic hydroxyamines and aromatic diamines include those obtained by acylating an amino group and converting it to an acylamino group (acylated product).

  The liquid crystalline polyester preferably has a repeating unit represented by the following general formula (1) (hereinafter sometimes referred to as “repeating unit (1)”). The repeating unit (1) and the following general formula (2) ) (Hereinafter sometimes referred to as “repeat unit (2)”) and a repeat unit represented by the following general formula (3) (hereinafter referred to as “repeat unit (3)”). More preferably).

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
(3) ^-X-Ar 3 -Y-
(In the formula, Ar ¹ is a phenylene group, a naphthylene group or a biphenylylene group; Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4): Yes; X and Y are each independently an oxygen atom or imino group; one or more hydrogen atoms in Ar ¹ , Ar ² and Ar ³ are each independently substituted with a halogen atom, an alkyl group or an aryl group May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(In the formula, Ar ⁴ and Ar ⁵ are each independently a phenylene group or a naphthylene group; Z is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)

As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned.
Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, An n-heptyl group, a 2-ethylhexyl group, an n-octyl group, an n-nonyl group, and an n-decyl group may be mentioned, and the number of carbon atoms is preferably 1-10.
Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the carbon number thereof is 6 to 20. Is preferred.
When the hydrogen atom is substituted with these groups, the number is preferably 2 or less independently for each of the groups represented by Ar ¹ , Ar ² or Ar ^3. More preferably.

  However, as will be described later, the flow start temperature of the liquid crystal polyester is preferably 360 ° C. or higher, and in order to obtain a liquid crystal polyester having such a flow start temperature, it is desirable that these substituents are not present.

  Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and preferably have 1 to 10 carbon atoms.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As repeating unit (1), Ar ¹ is a 1,4-phenylene group (repeating unit derived from p-hydroxybenzoic acid), and Ar ¹ is a 2,6-naphthylene group (6-hydroxy). Preferred is a repeating unit derived from 2-naphthoic acid.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a 1,4-phenylene group (repeating unit derived from terephthalic acid), Ar ² is a 1,3-phenylene group (repeating unit derived from isophthalic acid) ), Ar ² is a 2,6-naphthylene group (repeating unit derived from 2,6-naphthalenedicarboxylic acid), and Ar ² is a diphenyl ether-4,4′-diyl group (diphenyl) Preferred is a repeating unit derived from ether-4,4′-dicarboxylic acid).

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), Ar ³ is a 1,4-phenylene group (a repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is a 4,4′-biphenylylene group. (Repeating unit derived from 4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl or 4,4′-diaminobiphenyl) is preferred.

The content of the repeating unit (1) is the total amount of all repeating units constituting the liquid crystal polyester (the substance of each repeating unit is obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula weight of each repeating unit). The equivalent amount (mole) is obtained, and the total value thereof) is preferably 30 mol% or more, more preferably 30 to 80 mol%, still more preferably 40 to 70 mol%, particularly preferably 45 to 65. Mol%.
The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 15 to 30 mol%, based on the total amount of all repeating units constituting the liquid crystal polyester. Most preferably, it is 17.5-27.5 mol%.
The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 15 to 30 mol%, based on the total amount of all repeating units constituting the liquid crystal polyester. Most preferably, it is 17.5-27.5 mol%.
The higher the content of the repeating unit (1), the easier it is to improve the melt flowability, heat resistance, strength and rigidity of the liquid crystalline polyester. However, if the content is too large, the melting temperature and melt viscosity tend to increase, and the temperature required for molding. Tends to be high.

  The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol). The ratio is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and still more preferably 0.98 / 1 to 1 / 0.98.

  In addition, liquid crystalline polyester may have 2 or more types of repeating units (1)-(3) each independently. The liquid crystal polyester may have a repeating unit other than the repeating units (1) to (3), and the content thereof is preferably 10 with respect to the total amount of all repeating units constituting the liquid crystal polyester. The mol% or less, more preferably 5 mol% or less.

  The liquid crystal polyester preferably has, as the repeating unit (3), X and Y each having an oxygen atom, that is, a repeating unit derived from a predetermined aromatic diol. As the repeating unit (3), More preferably, X and Y each have only an oxygen atom. By doing in this way, liquid crystalline polyester tends to become low in melt viscosity.

  The liquid crystal polyester increases the flow start temperature by selecting a combination of the repeating units (1) to (3) so as to improve the linearity of the molecular chain. That is, a liquid crystal polyester having a flow start temperature of 360 ° C. or higher can be produced.

  The liquid crystal polyester is preferably produced by melt polymerization of raw material monomers corresponding to the repeating units constituting the liquid crystal polyester and solid-phase polymerization of the obtained polymer (prepolymer). Thereby, high molecular weight liquid crystal polyester having high heat resistance, strength and rigidity can be produced with good operability. Melt polymerization may be carried out in the presence of a catalyst. Examples of the catalyst in this case include metals such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide. Compounds, nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine, 1-methylimidazole and the like can be mentioned, and nitrogen-containing heterocyclic compounds are preferably used.

  The liquid crystal polyester has a flow initiation temperature of preferably 360 ° C. or higher, more preferably 360 ° C. to 410 ° C., and still more preferably 370 ° C. to 400 ° C. When the flow start temperature is in such a range, the heat resistance of the liquid crystal polyester itself is more sufficiently expressed, and the molded product obtained using the liquid crystal polyester composition has extremely good solder resistance, and is more practically molded. It is possible to obtain a shaped body at temperature.

The flow start temperature is also called flow temperature or flow temperature, and the temperature is raised at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ) using a capillary rheometer while liquid crystal polyester is used. Is a temperature showing a viscosity of 4800 Pa · s (48000 poise) when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, and is a measure of the molecular weight of the liquid crystalline polyester (Naide Koide, “ “Liquid Crystal Polymer—Synthesis / Molding / Application—”, CMC Co., Ltd., June 5, 1987, p. 95).

The fibrous filler is necessary for increasing the rigidity and improving the vibration damping property of the molded product obtained using the liquid crystal polyester composition, and examples thereof include alumina fiber, zirconia fiber, basalt fiber, and the like. Basalt fiber is particularly preferred in terms of rate and loss factor.
A fibrous filler may be used individually by 1 type, and may use 2 or more types together.

The fibrous filler has a Mohs hardness of greater than 6.5, preferably 7.0 or greater. When the Mohs hardness is 6.5 or less, the resulting molded article has low rigidity and cannot be highly rigid. The Mohs hardness is an empirical measure for determining the hardness of a mineral by comparing it with 10 reference minerals. The standard minerals are soft (Mohs hardness 1) to hard (Mohs hardness 10) in order of talc, gypsum, calcite, fluorite, apatite, orthofeldsite, quartz, yellow jade, steel balls, and diamonds. Rub the reference mineral with the sample material and measure the hardness with and without scratches. For example, if fluorite is not scratched and apatite is scratched, the Mohs hardness is 4.5 (meaning between 4 and 5).
Preferred fibrous fillers include alumina fibers having a Mohs hardness of 8.0, zirconia fibers having a Mohs hardness of 8.0, and basalt fibers having a Mohs hardness of 7.0.

  The fibrous filler (b) has an aspect ratio (value obtained by dividing the fiber length by the diameter) of 100 or more, preferably 150 or more. When the aspect ratio is equal to or higher than the lower limit, the loss factor of the obtained molded body is increased, and vibration damping is improved.

  Content of the said fibrous filler in a liquid crystalline polyester composition is 10-25 mass parts with respect to 100 mass parts of liquid crystalline polyester, Preferably it is 15-25 mass parts. By setting it in such a range, the obtained molded article is more excellent in vibration damping properties, and particularly when basalt fiber is used as the fibrous filler, the loss factor of the molded article is 0.045 or more. Excellent vibration characteristics.

  The hollow filler is necessary for reducing the weight of the molded product obtained using the liquid crystal polyester resin composition. With such weight reduction, for example, an optical pickup lens holder described later was manufactured using the liquid crystal polyester composition. Sometimes, it becomes possible to improve the focusing sensitivity of the optical pickup lens holder.

  Examples of the hollow filler include shirasu balloons, glass balloons, ceramic balloons, organic resin balloons, fullerenes, and the like. Among these, glass balloons are preferable because they are easily available and are not easily damaged.

  The volume average particle diameter of the hollow filler is preferably 10 to 40 μm, more preferably 15 to 40 μm, and still more preferably 20 to 40 μm. When the volume average particle diameter of the hollow filler is too large, the strength of the hollow filler tends to be low, and the hollow filler itself is easily damaged. On the other hand, if the volume average particle size of the hollow filler is too small, the surface area becomes large, so that moisture absorption is likely to occur, and hydrolysis of the liquid crystal polyester may be promoted during granulation of the liquid crystal polyester composition. In the present specification, the “volume average particle diameter” is obtained by measurement by a laser diffraction method.

The strength of the hollow filler is preferably 9800 N / cm ² or more, more preferably 9800 to 17600 N / cm ² , and still more preferably 11800 to 17600 N / cm ² .
The strength of the hollow filler is determined, for example, by measurement by a hydrostatic pressure collapse method in accordance with ASTM (American Society for Testing and Materials) D3102.

  The content of the hollow filler in the liquid crystal polyester composition is preferably 5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. By being the lower limit value or more, the molded product obtained using the liquid crystal polyester composition has a lower specific gravity (weight reduction), and by being the upper limit value or less, the molded product has a higher specific modulus. And the loss factor becomes larger.

The liquid crystal polyester composition according to the present invention may contain other components in addition to the liquid crystal polyester, the fibrous filler, and the hollow filler as long as the effects of the present invention are not hindered.
Examples of the other components include resins other than liquid crystal polyester, fillers other than the fibrous filler and hollow filler, additives, and the like.
The other components may be used alone or in combination of two or more.

  Examples of resins other than the liquid crystal polyester include polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and modified products thereof, thermoplastic resin such as polysulfone, polyethersulfone, and polyetherimide; phenol resin, Thermosetting resins such as epoxy resins and polyimide resins are listed.

  Examples of fillers other than the fibrous filler and hollow filler include talc, mica (mica), glass flakes, montmorillonite, smectite, graphite, boron nitride, molybdenum disulfide and other plate-like inorganic fillers; glass beads, Examples include spherical inorganic fillers such as silica beads.

  Examples of the additives include mold release improvers such as fluororesins and metal soaps; colorants such as dyes and pigments; antioxidants; thermal stabilizers; ultraviolet absorbers; antistatic agents; Examples thereof include those known in the art, such as additives having an external lubricant effect such as fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants.

  The total content of the liquid crystal polyester, fibrous filler and hollow filler in the liquid crystal polyester composition is preferably 80% by mass or more, and more preferably 90% by mass or more. By setting it to the lower limit value or more, the molded body described later has a higher specific modulus and a larger loss factor.

  The liquid crystal polyester composition can be produced by mixing the liquid crystal polyester, which is a blending component, a fibrous filler, a hollow filler, and other components as necessary, by a known method. As a mixing method at this time, for example, each compounding component is separately supplied to the melt mixer and mixed, and all the compounding components are premixed using a mortar, Henschel mixer, ball mill, ribbon blender, etc. Then, a method of supplying the premixed mixture to a melt mixer and mixing it may be mentioned.

  In order to surely prevent breakage of the hollow filler, the liquid crystal polyester composition is, for example, first sufficiently melt-mixed the liquid crystal polyester and the fibrous filler in a melt mixer, and when the melt viscosity of the mixture is the lowest. Further, it is preferable to manufacture by further mixing a hollow filler. Therefore, for example, when an extrusion melt kneader is used during production, liquid crystal polyester and fibrous filler are supplied from the upstream side, and hollow filler is supplied from the downstream side of this supply unit to melt and knead. Is preferred.

<Molded body>
The molded body according to the present invention is characterized in that the liquid crystal polyester composition is molded. Such a molded body has a high specific elastic modulus and a large loss coefficient because of the use of the liquid crystal polyester composition, so that it has excellent specific rigidity and vibration damping properties. For example, it is suitable as a bobbin for an optical pickup lens holder. is there.

  The liquid crystal polyester composition may be molded by a known method. However, when a molded body having a thin portion or a complicated shape such as a bobbin for an optical pickup lens holder described later is manufactured, the manufacturing is easy. From the viewpoint, the injection molding method is preferable.

  In the injection molding method, the molding temperature is preferably 10 to 80 ° C. higher than the flow start temperature on the basis of the flow start temperature of the liquid crystalline polyester. By setting it as such a range, a liquid crystalline polyester composition expresses the outstanding melt fluidity, and can manufacture the molded object which has a thin part or a complicated shape with a better moldability. For example, with respect to optical pickup lens holders, demands for weight reduction and cost reduction are increasing year by year, and the shape tends to become thinner and more complex. On the other hand, when the liquid crystal polyester composition is used, for example, an optical pickup lens holder having a thin portion with a thickness of 0.1 to 1.5 mm can be easily manufactured. Furthermore, when manufacturing an optical pickup lens holder having a relatively short flow length, even a thin portion having a thickness of 0.05 to 0.15 mm can be manufactured with good dimensional accuracy. And the molded object manufactured in this way is excellent also in the rigidity etc. which are represented by the bending elastic modulus (MD direction), without impairing the outstanding heat resistance of liquid crystalline polyester. In the present specification, “MD direction” means the flow direction of the molded body.

The molded body according to the present invention may have, for example, a low specific gravity in which the specific gravity determined in accordance with ASTM D792 (Method A) is in the range of 1.25 to 1.50.
Further, the molded body according to the present invention includes the liquid crystalline polyester composition including a fibrous filler that contributes to high rigidity and vibration damping at a specific ratio and a hollow filler that contributes to low specific gravity. Since it is used, the specific modulus is excellent when the specific elastic modulus is high, and the vibration damping property is excellent when the loss factor is large.

<Optical pickup lens holder>
An optical pickup lens holder according to the present invention includes a bobbin made of the molded body. Such an optical pickup lens holder is excellent in laser beam reading performance because the bobbin is made of the molded body having excellent specific rigidity and vibration damping properties. Moreover, even if it has a thin part or a complicated shape, it can be manufactured with good moldability. Such an optical pickup lens holder can be manufactured by the same method as the conventional optical pickup lens holder except that the liquid crystal polyester composition is used.

FIG. 1 is a schematic view illustrating an embodiment of an optical pickup lens holder according to the present invention.
The optical pickup lens holder 1 shown here includes a block-shaped bobbin 2. The bobbin 2 is formed of a molded body using the liquid crystal polyester composition, and can have a practical low specific gravity as described above. The bobbin 2 is provided with a light conducting hole 3 having a circular cross section penetrating in the vertical direction, so that laser light can be conducted through the bobbin 2 when reading and writing to the optical disc 7 such as a Blu-ray disc. Yes. A lens 5 is installed in the opening on the upper side of the photoconductive hole 3 (the side facing the optical disc 7). Further, a conductive wire 6 is wound around the bobbin 2 in a coil shape so as to surround the photoconductive hole 3 so as to form a magnetic field (magnetic field).

  Here, an example in which one optical conduction hole is provided per bobbin is shown as the optical pickup lens holder, but the optical pickup lens holder according to the present invention is not limited to this, and the bobbin 1 Two or more photoconductive holes may be provided per unit.

  So far, the example using the molded body as the bobbin of the optical pickup lens holder has been described. However, the molded body can also be used as a member other than the bobbin, for example, a base frame, an actuator body, or the like.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples. The flow starting temperature of the liquid crystal polyester, the aspect ratio of the fibrous filler, and the volume average particle size of the hollow filler were measured by the following methods.

(Measurement of flow start temperature of liquid crystal polyester)
Using a flow tester (“CFT-500 type” manufactured by Shimadzu Corporation), about 2 g of liquid crystalline polyester was filled into a cylinder equipped with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg / cm Under the load of ² ), while raising the temperature at a rate of 4 ° C./min, the liquid crystalline polyester was melted and extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 poise) was measured.

(Measurement of aspect ratio of fibrous filler)
Take a scanning electron microscope (SEM) photograph (magnification 1000 to 5000 times) of the fibrous filler, measure the length of the short side of 30 fibrous fillers from this photograph, calculate the average value of these, The average fiber diameter was used. Similarly, the length of the long side of 30 fibrous fillers was measured from this photograph, and the average value of these was calculated as the average fiber length. And the value of average fiber length / average fiber diameter was computed, and it was set as the aspect ratio.

(Measurement of volume average particle diameter of hollow filler)
The volume average particle diameter of the hollow filler used in the following Examples and Comparative Examples was measured using a laser diffraction particle size distribution measuring device “Mastersizer 2000” manufactured by Sysmex Corporation, and it was 27 μm.

<Manufacture of liquid crystal polyester>
[Production Example 1]
In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, 830.7 g (5.0 mol) of p-hydroxybenzoic acid and 394.6 g (2.375 mol) of terephthalic acid , 20.8 g (0.125 mol) of isophthalic acid, 465.5 g (2.5 mol) of 4,4′-dihydroxybiphenyl and 1153 g (11.0 mol) of acetic anhydride are stirred and stirred under a nitrogen gas stream. The temperature was raised from room temperature to 150 ° C. over 15 minutes and refluxed at 150 ° C. for 3 hours.
Subsequently, while distilling off the by-product acetic acid and unreacted acetic anhydride to be distilled off, the temperature was raised from 150 ° C. to 320 ° C. over 2 hours and 50 minutes, and maintained at 320 ° C. for 1 hour. The contents were removed and cooled to room temperature. And the obtained solid substance was grind | pulverized with the grinder, and the powdery prepolymer was obtained. The flow initiation temperature of this prepolymer was 251 ° C.
Next, this prepolymer was heated from room temperature to 250 ° C. over 1 hour in a nitrogen gas atmosphere, heated from 250 ° C. to 325 ° C. over 5 hours, and held at 325 ° C. for 3 hours, After solid phase polymerization, the mixture was cooled to obtain a powdered liquid crystal polyester. The liquid crystal polyester had a flow start temperature of 380 ° C.

<Production of Liquid Crystalline Polyester Composition and Molded Body>
[Example 1]
(Production of liquid crystal polyester composition)
Based on 100 parts by mass of the liquid crystalline polyester obtained above, basalt fiber “BS13” (average fiber diameter 13 μm, average fiber length 3 mm, aspect ratio 231, Mohs hardness 7.0) 18 manufactured by Basalt Technology as a fibrous filler 18 0.8 parts by mass and 6.3 parts by mass of “Glass Bubbles S60HS” (strength 12300 N / cm ² , volume average particle size 27 μm, volume hollow ratio 76%) manufactured by Sumitomo 3M as a hollow filler, Using a twin screw extruder ("PCM-30" manufactured by Ikekai Tekko Co., Ltd.) and a water-sealed vacuum pump "SW-25" manufactured by Shinko Seiki Co., Ltd., the cylinder temperature was set to 390 ° C and deaerated with a vacuum vent. While granulating, a pellet-like liquid crystal polyester composition was obtained.

(Manufacture of molded products)
Using the injection molding machine “PS40E1ASE” manufactured by Nissei Plastic Industrial Co., Ltd., the liquid crystal polyester composition obtained above was molded according to JIS K7113 (1) under molding conditions of a cylinder temperature of 400 ° C., a mold temperature of 130 ° C., and an injection speed of 60%. / 2) A dumbbell specimen (thickness 0.5 mm) was molded.

<Measurement of physical properties of molded article>
(Measurement of loss factor)
A 5 mm × 32 mm strip test piece was cut out from the molded body obtained above. Then, this test piece is attached to an accelerator “512-D” manufactured by Emic so that the center is supported, and the loss coefficient at the frequency of the primary resonance point at a temperature of 23 ° C. in accordance with JIS G0602. Measured by the method. The results are shown in Table 1.

(Measurement of specific gravity)
About the molded object obtained above, specific gravity was measured based on ASTM D792 (method A). The results are shown in Table 1.

(Calculation of specific modulus (MD direction))
The molded body obtained above was measured for a flexural modulus (MPa) in accordance with ASTM D790, and the specific modulus (MPa) was calculated by dividing the flexural modulus by the specific gravity. The results are shown in Table 1.

<Production of liquid crystal polyester composition and molded body, and measurement of physical properties of molded body>
[Comparative Example 1]
As a fibrous filler, instead of 18.8 parts by weight of basalt fiber “BS13” manufactured by Basalt Technology, “Arborex Y” manufactured by Shikoku Kasei Kogyo Co., Ltd. (average fiber diameter 0.8 μm, average fiber length 20 μm, aspect ratio 25) , Mohs hardness 7.0) Except for using 18.8 parts by mass, a liquid crystal polyester composition and a molded product were produced in the same manner as in Example 1, and the physical properties of the molded product were measured. The results are shown in Table 1.

[Comparative Example 2]
As a fibrous filler, in place of 18.8 parts by mass of Basalt fiber “BS13” manufactured by Basalt Technology, glass fiber “CS03JAPX-1” manufactured by Owens Corning Manufacturing Co., Ltd. (average fiber diameter 10 μm, average fiber length 3 mm, aspect ratio) A liquid crystal polyester composition and a molded body were produced in the same manner as in Example 1 except that 18.8 parts by mass of the ratio 300 and the Mohs hardness 6.0) were used, and the physical properties of the molded body were measured. The results are shown in Table 1.

[Comparative Example 3]
The amount of basalt fiber “BS13” is 8.8 parts by mass instead of 18.8 parts by mass, and the amount of “Glass Bubbles S60HS” is 15.0 parts by mass instead of 6.3 parts by mass. A liquid crystal polyester composition and a molded product were produced in the same manner as in Example 1 except that the physical properties of the molded product were measured. The results are shown in Table 1.

In addition, each abbreviation in Table 1 means the following, respectively.
(1) Liquid crystalline polyester LCP1: Liquid crystalline polyester obtained in Production Example 1 (2) Fibrous filler BS13: Basalt fiber “BS13” manufactured by Basalt Technology (average fiber diameter 13 μm, average fiber length 3 mm, aspect ratio 231, Mohs Hardness 7.0)
ABY: “Arbolex Y” manufactured by Shikoku Kasei Kogyo Co., Ltd. (average fiber diameter 0.8 μm, average fiber length 20 μm, aspect ratio 25, Mohs hardness 7.0)
CS03JAPX-1: Glass fiber “CS03JAPX-1” manufactured by Owens Corning Manufacturing Co., Ltd. (average fiber diameter 10 μm, average fiber length 3 mm, aspect ratio 300, Mohs hardness 6.0)
(3) Hollow filler S60HS: “Glass Bubbles S60HS” manufactured by Sumitomo 3M Limited (strength 12300 N / cm ² , volume average particle size 27 μm, volume hollow ratio 76%)

As is clear from the above results, the molded body of Example 1 had a high specific elastic modulus and a large loss coefficient, and was suitable as a material for the bobbin constituting the optical pickup lens holder.
On the other hand, the molded article of Comparative Example 1 had a low specific elastic modulus and a small loss coefficient because the aspect ratio of the fibrous filler was small.
Further, the molded body of Comparative Example 2 had a low specific elastic modulus and a small loss coefficient due to its low Mohs hardness.
Further, the molded product of Comparative Example 3 had a low specific elastic modulus and a small loss coefficient due to a small amount (content) of fibrous filler.

  The present invention can be used for an optical pickup member that requires high specific rigidity and vibration damping.

  DESCRIPTION OF SYMBOLS 1 ... Optical pick-up lens holder, 2 ... Bobbin, 3 ... Light conduction hole, 5 ... Lens, 6 ... Conductor, 7 ... Optical disk

Claims (6)

A liquid crystal polyester composition comprising 10 to 25 parts by mass of a fibrous filler that satisfies the following requirements (a) and (b) and 100 parts by mass of a liquid crystal polyester.
(A) Mohs hardness is greater than 6.5.
(B) The aspect ratio is 100 or more.   The liquid crystal polyester composition according to claim 1, wherein the hollow filler is contained in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.   The liquid crystal polyester composition according to claim 1, wherein the liquid crystal polyester has a flow start temperature of 360 ° C. or higher.   The liquid crystalline polyester composition according to any one of claims 1 to 3, wherein the hollow filler has a volume average particle size of 10 to 40 µm.   A molded product, wherein the liquid crystal polyester composition according to any one of claims 1 to 4 is molded.   An optical pickup lens holder comprising a bobbin made of the molded body according to claim 5.

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