JP2001067702A - Thermoplastic resin material for signal reader and parts for signal reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin material for a signal reader for widening a control frequency band by increasing the secondary resonance frequency of the signal reader and parts for the signal reader obtained by molding the material. SOLUTION: The thermoplastic resin material for the signal reader contains packing material of the following (1) or (2):5 to 250 pts.wt. the planar packing material (B) of >=10 in an average aspect ratio, 0 to 100 pts.wt. fibrous packing material (C) of >=15 in average aspect ratio to be added at need or 5 to 150 pts.wt. packing material (D) of <10 in average aspect ratio and 5 to 100 pts.wt. fibrous packing material (C) of >=15 in average aspect ratio per 100 wt.% thermoplastic resin (A). The molded goods thereof are (modulus of elasticity in bending)/(specific gravity)}1/2>85 (MPa1/2) and satisfy the relation (modulus of elasticity in bending)/(torsional rigidity modulus)<5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component for a signal reading device, and more particularly to a resin material for a signal reading device of a digital disk drive and a component comprising the same.
Specifically, it consists of a specific thermoplastic resin and filler, and the bending elastic modulus, specific gravity and torsional rigidity have a specific relationship,
The secondary resonance frequency increases, and the reading performance is stabilized.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable increase in the capacity and speed of information handled by a signal reading apparatus, particularly a digital disk drive. For example, the rotation speed of a disk of a CD-ROM is increased twice, and the density of recording information is increased due to the development of a DVD. For example, when reading information on a disc using laser light, the disc of the digital disc drive device may have an eccentricity, a surface runout, a vibration caused by a rotational vibration, etc., so that the focal point of the laser and the position of the information to be read on the disc are different. A reading error may occur due to relative deviation. In order to prevent this, a signal reading device has conventionally been provided with a mechanism for correcting the amount of displacement due to vibration or the like. However, in recent years, the amount of information handled by a digital disk drive has been increased, the vibration amplitude has been increased due to an increase in the speed, and the vibration frequency has been increased. It is difficult to obtain stable reading performance, and it has become necessary to provide a signal reading device with high vibration damping properties and particularly to increase the resonance frequency. As a countermeasure to increase the resonance frequency, "Introduction to Vibration Engineering" supervised by Mr. Shinji Yamada, published by Power Corporation, raises the resonance frequency by increasing ｛(flexural modulus) / (specific gravity)｝ ^1/2 Is described. Therefore, it is possible to increase the resonance frequency of the signal reader and widen the vibration control frequency by using a material having a large {(flexural modulus) / (specific gravity)} ^{1/2 as} a material for the signal reader. As is generally the case, such materials do not sufficiently raise the resonance frequency. Japanese Patent Application Laid-Open No. H11-126351 discloses a component for a signal reading device using a thermoplastic resin composition satisfying a loss coefficient × elastic modulus> 70 MPa and (elastic modulus / specific gravity) ^1/2 > 70 MPa ^1/2. However, further performance improvement is required.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a thermoplastic resin material for a signal reading device for increasing the secondary resonance frequency of the signal reading device and widening the control frequency band, and to obtain the same by molding the same. It is to provide a component for a signal reading device.

[0004]

The inventors of the present invention have conducted intensive studies on a method of further increasing the resonance frequency of the signal reader, and as a result, as a thermoplastic resin material used for the signal reader, ｛(flexural modulus) / (Specific gravity) Not only｝ ^1/2, but a material that satisfies the relationship between bending elastic modulus and torsional rigidity can raise the natural frequency of the signal reader beyond the limit that was conventionally considered to be the limit. They have found that they can do this and have completed the present invention.

That is, a first aspect of the present invention is that the molded product has {(flexural modulus) / (specific gravity)} ^1/2 > 85 (MPa ^1/2 ) and (flexural modulus) / (torsional rigidity). <5> A thermoplastic resin material for a signal reader having a relationship of <5. A second aspect of the present invention is that the thermoplastic resin material is a thermoplastic resin (A) 1
With respect to 00 parts by weight, the following filler (1) or (2):
(1) Plate-like filler (B) 5 having an average aspect ratio of 10 or more
0 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more, and (2) 5-150 parts by weight of a filler (D) having an average aspect ratio of less than 10 as required. The first thermoplastic resin material for a signal reader according to the present invention, which contains 5 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more. The third aspect of the present invention is a thermoplastic resin (A)
Is a thermoplastic resin material for a signal reader according to the first or second aspect of the present invention comprising a liquid crystalline polymer. The fourth aspect of the present invention
Is a thermoplastic resin material for a signal reader according to the second aspect of the present invention, wherein the plate-like filler (B) is glass flake and / or mica. A fifth aspect of the present invention is the thermoplastic resin material for a signal reader according to the second aspect of the present invention, wherein the filler (D) is glass beads and / or talc. In the sixth aspect of the present invention,
It is a component for a signal reading device formed by molding any one of the thermoplastic resin materials of the first to fifth aspects of the present invention. The seventh aspect of the present invention
Is a sixth signal reading device component of the present invention in which the signal reading device component is a lens holder, a bearing, a bobbin, a sliding shaft, and / or an actuator body of a digital disk drive device. According to an eighth aspect of the present invention, there is provided the component for a signal reader according to the sixth or seventh aspect of the present invention, wherein a secondary resonance frequency when the signal reader having the component for a signal reader assembled is used is 12 kHz or more.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a signal reading device 2 is described.
In order to sufficiently increase the next resonance frequency and widen the control frequency band, the material used for the signal reader is a molded product {(flexural modulus) / (specific gravity)} ^1/2 > 85 (unit: MPa)
^1/2 ) and (flexural modulus) / (torsional rigidity) <5. Materials satisfying this relationship have sufficient performance as a signal reader. ｛(Bending elastic modulus) / (specific gravity)｝ ^1/2 > 85, but if (Bending elastic modulus) / (Torsion rigidity) is 5 or more, the natural frequency rises as expected. However, the material for the signal reading device is limited by the use conditions.

As a component made of a thermoplastic resin material constituting the signal reading device, for example, a lens holder for holding an objective lens; Actuator bobbin which is the core of the coil for moving the objective lens according to the condition; Actuator body which is the body supporting each component of the optical pickup; Bearing; Sliding shaft, etc. Don't worry about these if they affect you.

The thermoplastic resin (A) constituting the thermoplastic resin material for a signal reader according to the present invention is not particularly limited, but may be a liquid crystal polymer, a polyphenylene sulfide resin, a polyester resin, a polycarbonate resin, a polystyrene resin, or the like. Polyether imide resin, polysulfone resin and polyamide imide resin are exemplified, and among them, liquid crystalline polymer is particularly preferably used.

The liquid crystalline polymer 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 was performed using a Leitz polarizing microscope and Lei
Melt sample placed on tz hot stage under nitrogen atmosphere
It can be carried out by observing at a magnification of 0. When the liquid crystalline polymer applicable to the present invention is inspected between orthogonal polarizers, polarized light is normally transmitted even when it is in a molten stationary state, and exhibits optical anisotropy. The liquid crystalline polymer used in the present invention is not particularly limited, but is preferably an aromatic polyester or an aromatic polyesteramide, and the aromatic polyester or the polyester partially containing the aromatic polyesteramide in the same molecular chain is also included. It is in.
These are dissolved in pentafluorophenol at a concentration of 0.
When dissolved at 1% by weight, at least about 2.0 dl /
g, more preferably one having a logarithmic viscosity (IV) of 2.0 to 10.0 dl / g.

The aromatic polyester or aromatic polyester amide is particularly preferably an aromatic compound having at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines and aromatic diamines. And aromatic polyester amides.

More specifically, (i) a polyester mainly composed of one or more aromatic hydroxycarboxylic acids or derivatives thereof; (ii) mainly (a) one or more aromatic hydroxycarboxylic acids or derivatives thereof; (B) an aromatic dicarboxylic acid,
One or more alicyclic dicarboxylic acids or derivatives thereof;
(C) a polyester comprising an aromatic diol, an alicyclic diol, an aliphatic diol or one or more derivatives thereof; (iii) mainly (a) one or more aromatic hydroxycarboxylic acids or one or more derivatives thereof; (B) a polyesteramide comprising one or more aromatic hydroxyamines, aromatic diamines or derivatives thereof, and (c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids or derivatives thereof; iv) mainly (a) one or more aromatic hydroxycarboxylic acids or derivatives thereof, (b) one or more aromatic hydroxyamines, aromatic diamines or derivatives thereof, and (c) aromatic dicarboxylic acids, One or more alicyclic dicarboxylic acids or their derivatives and (d) one kind of aromatic diols, alicyclic diols, aliphatic diols or their derivatives And the like. If necessary, a molecular weight modifier may be used in combination with the above components.

Preferred examples of specific compounds constituting the liquid crystalline polymer applicable to the present invention are as follows. (A) Examples of the aromatic hydroxycarboxylic acid include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, and mixtures thereof. Examples of the derivative include an alkyl ester of a carboxyl group having 1 to 10 carbon atoms, preferably a methyl ester. (B) Examples of the aromatic hydroxyamine and aromatic diamine include aromatic amines such as p-aminophenol and p-phenylenediamine. (C) The aromatic dicarboxylic acid and the alicyclic dicarboxylic acid are represented by terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and the following general formula [1] And aromatic dicarboxylic acids such as compounds. Examples of the derivative include an alkyl ester of a carboxyl group having 1 to 10 carbon atoms, preferably a methyl ester. (D) As aromatic diol, alicyclic diol and aliphatic diol, 2,6-dihydroxynaphthalene, 1,4
-Dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, the following general formula
Aromatic diols having an aromatic ring such as p-xylenol; aromatic diols having an aromatic ring such as p-xylenol; and aliphatic diols having 2 to 6 carbon atoms. Preferably, it is an aromatic diol. Examples of the derivative include an alkyl ester of a hydroxyl group having 1 to 10 carbon atoms, preferably an acetyl ester.

[0013]

Embedded image

The liquid crystalline polymer used in the present invention is preferably an aromatic polyesteramide containing p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, terephthalic acid and p-aminophenol as main constituent units. It is.

The thermoplastic resin (A) may contain a small amount of another thermoplastic resin in addition to the thermoplastic resin as a main component. When the thermoplastic resin (A) is a liquid crystalline polymer, examples of other thermoplastic resins include polyamide, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and modified products thereof. , Polysulfone, polyethersulfone, polyetherimide and the like, and mixtures thereof. In addition, other than the above-mentioned other thermoplastic resins, a small amount of a thermosetting resin, for example, one or more of a phenol resin, an epoxy resin, and a polyimide resin can also be added.

The thermoplastic resin material of the present invention is obtained by blending the following fillers (1) and (2) with the thermoplastic resin (A). (1) 5 to 250 parts by weight of a plate-like filler (B) having an average aspect ratio of 10 or more, and 0 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more, if necessary. 5) 150 parts by weight of a filler (D) having an average aspect ratio of less than 10 and 5 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more;

The above-mentioned plate-like filler (B) having an average aspect ratio of 10 or more means a plate-like filler having a planar expansion larger than its thickness, and a filler having some curvature or unevenness. Including. Among them, those having an average aspect ratio of at least 10 as indicated by the ratio between the average thickness and the average major axis are indicated. Among them, the average aspect ratio is preferably 10 to 200, and particularly preferably 10 to 100. If the average aspect ratio is smaller than this, the effect of improving the torsional rigidity as a plate-like filler is small, while if it is too large, adverse effects such as deterioration in moldability and appearance are caused. Specific examples of the plate-like filler (B) include a glass flake; a metal foil; a planar layered crystal structure such as talc, mica, and graphite; Plate-like inorganic substances; and mixtures thereof.

In the present invention, in order to further improve the mechanical properties, the plate-like filler (B) having the above aspect ratio of 10 or more is used.
Optionally, the fibrous filler (C) having an average aspect ratio of 15 or more is 0 to 100 parts by weight, preferably 5 parts by weight or more, and more preferably 100 parts by weight of the thermoplastic resin (A). 10 to 50 parts by weight can be blended.
If the amount is too large, the anisotropy of the physical properties of the material increases, and the desired physical properties cannot be obtained.

As the fibrous filler (C), glass fibers; polyacrylonitrile (PAN) -based or pitch-based carbon fibers, and mixtures thereof can be used.
Among them, glass fiber is preferable in terms of the balance between price and performance. When the fillers (B) and (C) are used in combination, if the amount is too large, the extrudability and the moldability, especially the fluidity, are deteriorated, and the mechanical strength is reduced. Is preferably 150 parts by weight or less based on 100 parts by weight of the thermoplastic resin (A).

The filler (D) has an average aspect ratio of 15
The desired physical properties can be obtained when used in combination with the fibrous filler (C) described above. Specific examples of the filler (D) having an average aspect ratio of less than 10 in the present invention include kaolin, clay, vermiculite, and talc (the aspect ratio differs from that of the talc (B) due to a difference in the production method). , Calcium silicate, aluminum silicate, feldspar powder, acid clay, limestone clay, sericite, sillimanite, bentonite, glass beads, slate powder, silicates such as silane, calcium carbonate, chalk, barium carbonate,
Carbonates such as magnesium carbonate and dolomite, barite powder, blankix, precipitated calcium sulfate, plaster of Paris, sulfates such as barium sulfate, hydroxides such as hydrated alumina, alumina, antimony oxide, magnesia, titanium oxide, zinc oxide Flower, silica, quartz sand, quartz, white carbon,
Oxides such as diatomaceous earth, sulfides such as molybdenum disulfide, particles made of materials such as metal powder, mica powder, glass powder, plate-like or strip-like materials such as metal foil, glass milled fiber, Ultra-short fibers such as PAN-based and pitch-based carbon milled fibers, whiskers such as potassium titanate, metal fibers such as brass, inorganic fibers such as alumina silica, and ore-based fibers such as wollastonite, and mixtures thereof. Is mentioned. Among them, talc is preferred in terms of the balance between price and performance.

The filler (D) is used in combination with the fibrous filler (C). In this case, if the average aspect ratio of the filler (D) exceeds 10, the effect of the combined use with the fibrous filler (C) is diminished. The compounding amount of the filler (D) is resin 1
The amount of the fibrous filler (C) is 5 to 150 parts by weight with respect to 00 parts by weight, and has an average aspect ratio of 15 or more.
It is 5 to 100 parts by weight based on 100 parts by weight of the resin. It is desirable that the total amount of both the filler (D) and the fibrous filler (C) be 150 parts by weight or less based on 100 parts by weight of the resin. When the amount of the filler (D) is more than 150 parts by weight, productivity and moldability, particularly fluidity, are deteriorated, and mechanical strength is also reduced. If the amount is less than 150 parts by weight, the desired effect is not exhibited.

These fillers (B), (C) and (D) can be used alone or in combination of two or more. These fillers may be used in combination with a known surface treating agent, or may be treated in advance. As the surface treatment agent, epoxy compounds, isocyanate compounds, titanate compounds, silane compounds and the like are generally used.

The thermoplastic resin (A) used in the present invention is separated from needle-like reinforcing materials, inorganic or organic fillers, fluororesins, metal soaps and the like within a range not to impair the object of the present invention. Molding agents, dyes, pigments, coloring agents such as carbon black, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, fluorocarbon surfactants One or more ordinary additives such as a compounding agent having a lubricating effect such as an agent can be added.

The means for compounding the raw material components for obtaining the thermoplastic resin material of the present invention is not particularly limited. Ingredients, and if necessary, each component such as reinforcing materials such as aluminum borate whiskers and inorganic fillers, mold release agents, heat stabilizers, etc. are separately supplied to the melt mixer, or these raw material components are It is also possible to use a static mixer, a mortar, a Henschel mixer, a ball mill, a ribbon blender or the like to perform premixing before supplying the premixed mixture to the melt mixer. In addition, thermoplastic resin (A) and plate-like filler (B), thermoplastic resin (A) and fibrous filler (C), thermoplastic resin (A)
And the filler (D) may be separately supplied to a melt mixer to be pelletized, and these may be combined and mixed in a pellet state to obtain a desired blending amount.

As described above, the thermoplastic resin (A) 100
(1) Plate-like filler (B) 5 having an average aspect ratio of 10 or more with respect to the weight part.
0 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more, and (2) 5-150 parts by weight of a filler (D) having an average aspect ratio of less than 10 as required. By using a thermoplastic resin material containing 5 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more, Δ (flexural modulus)
/ (Specific gravity)｝ ^1/2 > 85 (MPa1 ^{/ 2} ), and a thermoplastic resin material for a signal reader that satisfies the relationship of (flexural modulus) / (torsional rigidity) <5.

According to the present invention, the molded product has the specific {(flexural modulus) / (specific gravity)} ^1/2 > 85 (MPa ^1/2 ), and (flexural modulus) / (torsional rigidity). The present invention relates to a thermoplastic resin material for a signal reading device satisfying the relationship of <5. Therefore, this condition can also be used as a condition for providing a method for selecting a material of a resin component constituting the signal reading device. Further, the present invention extends to a signal reading device including the above-mentioned component made of a thermoplastic resin material, the component including a component affecting resonance of the signal reading device. The signal reader is a digital disk drive, especially a CD or DVD.
Digital disk drive. The components for the signal reader include a lens holder, a bearing, a bobbin, a sliding shaft, an actuator body, and a combination thereof.

[0027]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples, and modifications thereof are also included in the present invention. Measurement of resonance frequency: CD-ROM as signal reader
An optical pickup (FIG. 1) was used (note that the four corners of the lens holder 2 may be rounded). FIG.
, A white noise electric signal is input to the positioning magnetic circuit 7, the tracking coil 4, and the focusing coil 4 ', the pickup is vibrated, and the frequencies of the primary resonance point and the secondary resonance point are measured. FIG. 2 shows an example of the measurement chart. The horizontal axis of the chart is frequency (Hz), and the vertical axis is amplitude (d
B) is shown. Measurement of flexural modulus and torsional rigidity: 1.6 as a molded product
A test piece of mm × 13 mm × 130 mm (FIG. 3) was prepared by injection molding and used for measurement. The gate position for the injection of the molten resin material is at the longitudinal end of the test piece (right end in FIG. 3) in FIG. Flexural modulus is ASTM D
The measurement was performed according to 790 (see FIG. 4). The test piece shown in FIG. 3 was freely supported at both ends with a span of 25 mm, and a load was applied to an intermediate position to give a strain rate of 1.00 mm / min. As shown in FIG. 5, the torsional rigidity of the test piece was measured by attaching one end of the test piece to the load cell 11 with the test piece restraining jig and the other end to the load cell 12 with the test piece restraining jig. The measurement was carried out by mounting the load cell 11 in a direction (not constrained in the z direction) with a twist span of 100 mm and twisting the load cell 11 at a rotation speed of 60 degrees / minute. Average aspect ratio: Resin material pellets were thermally decomposed and removed by heating, and the residue was evaluated by observing the appearance of 50 fillers arbitrarily selected using a magnifying glass.

[Examples 1 to 5 and Comparative Examples 1 to 5] Ratios of fillers shown in Table 1 to polycarbonate (PC) and liquid crystalline polyester (LCP; Vectra ^™ E950i, manufactured by Polyplastics Co., Ltd.) The mixture was melt-kneaded with a twin-screw extruder and strand-cut to prepare pellets. Using the pellets, the test piece was prepared using an injection molding machine. Table 2 shows the test results.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

According to the present invention, it is possible to sufficiently increase the secondary resonance frequency when using a signal reader incorporating a part made of a thermoplastic resin material, and the reading performance is more stabilized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a signal reading device used in the present invention.

FIG. 2 is an example of a chart showing a vibration measurement example of the signal reading device used in the present invention.

FIG. 3 is a view showing a test piece used for measuring a flexural modulus and a torsional rigidity.

FIG. 4 is a diagram showing a method for measuring a flexural modulus.

FIG. 5 is a diagram showing a method for measuring a torsional rigidity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Bearing 4 Tracking coil wound on bobbin 4 Focusing coil wound on bobbin 5 Sliding shaft 6 Actuator body 7 Magnetic circuit 11 Load cell with test piece restraining jig 12 Test piece restraining jig Load cell

Claims (8)

[Claims] 1. The molded article has a relation of {(flexural modulus) / (specific gravity)} ^1/2 > 85 (MPa ^1/2 ), and (flexural modulus) / (torsional rigidity) <5. A thermoplastic resin material for signal readers that satisfies 2. The thermoplastic resin material is based on 100 parts by weight of the thermoplastic resin (A) based on the following filler (1) or (2): (1) a plate-like filler having an average aspect ratio of 10 or more ( B) 5
0 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more, and (2) 5-150 parts by weight of a filler (D) having an average aspect ratio of less than 10 as required. The thermoplastic resin material for a signal reader according to claim 1, further comprising 5 to 100 parts by weight of a fibrous filler (C) having an average aspect ratio of 15 or more. 3. The thermoplastic resin material for a signal reader according to claim 1, wherein the thermoplastic resin (A) comprises a liquid crystalline polymer. 4. The thermoplastic resin material for a signal reader according to claim 2, wherein the plate-like filler (B) is glass flake and / or mica. 5. The thermoplastic resin material for a signal reader according to claim 2, wherein the filler (D) is glass beads and / or talc. 6. A component for a signal reading device formed by molding the thermoplastic resin material according to claim 1. 7. The component for a signal reader according to claim 6, wherein the component for a signal reader is a lens holder, a bearing, a bobbin, a sliding shaft and / or an actuator body of a digital disk drive. 8. The component for a signal reader according to claim 6, wherein a secondary resonance frequency when the signal reader to which the component for the signal reader is assembled is used is 12 kHz or more.