JP2014051604A - Electroconductive thermoplastic resin composition and molded article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive thermoplastic resin composition capable of being colored other than black, excellent in moldability, providing a molded article having a small warp, less dropout of a conductive filler particle from its surface and exhibiting stable conductivity, and to provide a molded article thereof.SOLUTION: An electroconductive thermoplastic resin composition is obtained by blending (A) a thermoplastic resin of 89.9 to 10 wt.%, (B) a fine carbon fiber of 0.1 to 10 wt.%, and (C) a coloring agent of 10 to 80 wt.%, and a weight ratio [(C)/(B)] of (C) the coloring agent with (B) the fine carbon fiber is 5 to 100. Conductivity is exhibited with a small amount of addition by minutely dispersing (B) the fine carbon fiber in (A) the thermoplastic resin and the electroconductive thermoplastic resin composition capable of being colored other than black can be manufactured without deteriorating conductivity by adding (C) the coloring agent.

Description

The present invention relates to a conductive thermoplastic resin composition and a molded article thereof, and particularly relates to a conductive thermoplastic resin composition and a molded article thereof suitably used in the electric and electronic field.
Specifically, the present invention relates to a conductive thermoplastic resin composition that can be used for trays used for assembling and transporting ICs (integrated circuits), magnetic heads, etc., and other resin trays in the electrical and electronic field, and molding thereof. Related to goods.

  Conventionally, a conductive thermoplastic resin composition in which a conductive filler such as carbon black is added to a thermoplastic resin is used as the conductive resin material. However, in a conductive thermoplastic resin composition containing carbon black, It is difficult to color other than black. That is, in order to impart conductivity by blending carbon black into an insulating thermoplastic resin, it is necessary to add a large amount of carbon black. However, since carbon black is black, it has conductivity and It is difficult to obtain a resin composition having a hue, saturation, and brightness other than black.

  On the other hand, many resin trays are now used in the process of manufacturing, transporting and assembling electronic devices such as magnetic heads and ICs (hereinafter sometimes simply referred to as “devices”). In order to identify and manage the color, there is an increasing demand for coloring in colors other than black. Further, in the magnetic head tray, there is a case where a black device is mounted on the tray. If the black device cannot be visually recognized on the tray, the work efficiency is remarkably lowered. For this reason, there is a need for a tray that has sufficient conductivity to suppress device destruction due to static electricity and is colored other than black, and a conductive colored resin composition used for such a tray is required. ing.

  As a material having the above characteristics, a conductive resin composition in which a thermoplastic filler is blended with a conductive filler and a pigment as a coloring component is known. For example, Patent Documents 1 and 2 describe a thermoplastic resin composition obtained by blending a metal conductive filler and a pigment with a thermoplastic resin. Patent Documents 3 to 5 describe thermoplastic resin compositions obtained by blending carbon fibers and pigments with thermoplastic resins. Patent Document 6 describes a thermoplastic resin composition obtained by blending graphite and a pigment with a thermoplastic resin. Patent Document 7 describes a thermoplastic resin composition obtained by blending an ion conductive agent and a pigment with a thermoplastic resin.

JP 2004-83614 A JP-A-9-59492 JP-A-8-73655 JP 63-12663 A JP-A-62-254040 JP-A-60-170642 Japanese Patent Laid-Open No. 2005-15609

  As a result of investigations by the present inventors, it has been found that in the resin compositions of Patent Documents 1 to 5, metal fillers and carbon fibers are easily dropped from the tray surface obtained by molding the resin composition. If the dropped metal filler or carbon fiber adheres to the surface of the device, it may cause device destruction due to a short circuit. In addition, it has been found that resin compositions containing metal fillers and carbon fibers have problems such as increased anisotropy due to their orientation and large warping of molded products. If the flatness of the device tray is poor, it may interfere with the automatic mounting of the device on the tray, or the device may fall out from between the stacked trays when cleaning the device on the tray. The problem of being out of focus occurs when inspecting with the.

In the resin composition of Patent Document 6 described above, graphite particles easily fall off from the surface of the molded product, and the falling particles not only cause device destruction due to short circuit, but also add a large amount of graphite particles to impart conductivity. Since it is necessary, the fluidity and moldability of the resin composition are significantly deteriorated.
In the resin composition of Patent Document 7 described above, the conductivity of the ionic conductive agent varies greatly depending on the use environment, so that stable conductivity cannot be obtained.

  The present invention solves the above-mentioned conventional problems, can be colored other than black, is excellent in moldability, has a small warp of the obtained molded product, has little dropout of conductive filler particles from the surface of the molded product, and It is an object of the present invention to provide a conductive thermoplastic resin composition that exhibits stable conductivity and a molded product thereof.

  As a result of intensive studies by the present inventors in order to solve the above-described problems, (B) fine carbon fibers are finely dispersed in (A) a thermoplastic resin so that the conductivity can be reduced with a smaller amount of addition than in the prior art. It came to invent the electroconductive thermoplastic resin composition which expresses and can color other than black by adding (C) coloring agent, without deteriorating electroconductivity.

  That is, the gist of the present invention is the following [1] to [9].

[1] Conductive heat formed by blending (A) thermoplastic resin 89.9 to 10% by weight, (B) fine carbon fiber 0.1 to 10% by weight, and (C) colorant 10 to 80% by weight. A conductive thermoplastic resin composition, wherein the weight ratio [(C) / (B)] of (C) a colorant and (B) fine carbon fiber is 5 to 100. .

[2] Ratio of melt flow rate [MFR (5.0 kg)] at a load of 5.0 kg to melt flow rate [MFR (2.16 kg)] at a load of 2.16 kg [MFR (5.0 kg) / The conductive thermoplastic resin composition according to [1], which has a temperature range in which MFR (2.16 kg)] is 4 to 100.

[3] (A) The thermoplastic resin is polyether ether ketone resin, polyphenylene sulfide resin, polyether imide resin, polyether sulfone resin, polysulfone resin, polyarylate resin, modified polyphenylene ether resin, polyacetal resin, polyamide resin. The conductive thermoplastic resin composition according to [1] or [2], which contains one or more selected from the group consisting of styrene resin and polyolefin resin.

[4] The conductive thermoplastic resin according to [3], wherein (A) the thermoplastic resin includes a polyether ether ketone resin having a melt flow rate of 3.0 g / 10 min or more at 380 ° C. under a load of 2.16 kg. Composition.

[5] (B) The conductive thermoplastic resin composition according to any one of [1] to [4], wherein the average fiber diameter of the fine carbon fibers is 200 nm or less.

[6] The conductive thermoplastic resin composition according to any one of [1] to [5], wherein (C) the colorant is titanium dioxide.

[7] A molded product formed by molding the conductive thermoplastic resin composition according to any one of [1] to [6].

[8] The molded product according to [7], which has a surface resistance value of 1 × 10 ² Ω or more and 1 × 10 ¹² Ω or less.

[9] The molded product according to [7] or [8], which is a tray for a hard disk magnetic head.

  According to the present invention, colors other than black can be colored, the moldability is excellent, the warp of the resulting molded product is small, the conductive filler particles are not dropped from the surface of the molded product, and stable conductivity is exhibited. An electrically conductive thermoplastic resin composition and a molded product thereof can be provided.

  For this reason, as various device trays, hue, saturation, and lightness other than black can be given to facilitate tray identification management, and the visibility of devices on the tray can be improved, and work efficiency can be improved. . In addition, it is possible to realize a tray that solves the problem of short-circuiting of the device due to the dropping of the conductive filler particles and has excellent flatness (flatness) and can hold the device stably.

1A and 1B are diagrams showing a tray sample formed in the example, in which FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view taken along line BB in FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

[Conductive thermoplastic resin composition]
The conductive thermoplastic resin composition of the present invention comprises (A) a thermoplastic resin 89.9 to 10% by weight, (B) a fine carbon fiber 0.1 to 10% by weight, and (C) a colorant 10 to 80% by weight. %, And the weight ratio [(C) / (B)] of (C) the colorant and (B) fine carbon fiber is 5 to 100. And

<(A) Thermoplastic resin>
As the thermoplastic resin (A) used in the present invention, polyether ether ketone resin, polyphenylene sulfide resin, polyether imide resin, polyether sulfone resin, polysulfone resin, polyarylate resin, modified polyphenylene ether resin, polyacetal resin Polyester resins such as polycarbonate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resins such as nylon 6 and nylon 66, styrene resins such as polystyrene and ABS, polyolefin resins such as polypropylene and polyethylene, EPR, etc. Olefin elastomers, styrene elastomers such as SEBS, polyester elastomers, polyurethane elastomers, polyamide elastomers, silicone elastomers Tomah include resin mixtures comprising at least two selected thermoplastic elastomer and from these, such as acrylic elastomer.

  (A) Polyether ether ketone resin, polyphenylene sulfide resin, polyether imide resin, polyether sulfone resin, polysulfone resin, polyarylate resin, modified polyphenylene ether resin, polyacetal resin, nylon are preferably used as the thermoplastic resin. 6. Polyamide resins such as nylon 66, styrene resins such as polystyrene and ABS, polyolefin resins such as polypropylene and polyethylene, and a resin mixture containing at least two selected from these. Further, a polyether ether ketone resin, a polyphenylene sulfide resin, a polyacetal resin, a polyamide resin such as nylon 6 and nylon 66, a crystalline resin such as a polyolefin resin such as polypropylene and polyethylene, and a resin containing at least two selected from these resins A mixture is preferable in that the moldability is not easily impaired.

  (A) The melt flow rate (MFR) of the thermoplastic resin is not limited, but the value at 2.16 kg load is usually 0.1 to 150 g / 10 min, preferably 0.5 to 100 g / 10 min, more preferably 1 to 1. 80 g / 10 min. By adjusting the melt flow rate within this range, excellent conductivity, moldability (less warpage), and colorability tend to be obtained. Here, the measurement temperature of the melt flow rate is (A) when the thermoplastic resin is a crystalline resin, (A) a temperature higher by 10 ° C. or more and 100 ° C. or less than the melting point (Tm) of the thermoplastic resin. ) When the thermoplastic resin is an amorphous resin, the temperature is higher by 50 ° C. or more and 200 ° C. or less than the glass transition temperature (Tg) of (A) the thermoplastic resin.

In particular, the polyetheretherketone resin is desirable because (C) there is little deterioration in strength due to the colorant, and in addition, it is excellent in low dust generation and chemical resistance required for the magnetic head tray.
Further, among the polyether ether ketone resins, those having a melt flow rate (MFR) of 3.0 g / 10 min or more, particularly 3.5 to 100 g / 10 min at 380 ° C. and a load of 2.16 kg are preferable. In polyether ether ketone resins having an MFR value of less than 3.0 g / 10 min, moldability tends to deteriorate, and in those exceeding 100 g / 10 min, the molecular weight is too low, resulting in a decrease in mechanical properties of the molded product, In addition, burrs tend to occur frequently in molded products.

  In the conductive thermoplastic resin composition of the present invention, the blending amount of the thermoplastic resin (A) in the resin composition is 89.9 to 10% by weight, preferably 85 to 20% by weight, more preferably 80 to 25%. % By weight. (A) When the blending amount of the thermoplastic resin exceeds the upper limit, the blending amount of (B) fine carbon fiber and (C) colorant is relatively reduced, and the intended conductivity and colorability are obtained. If it is less than the above lower limit, the moldability and mechanical properties are deteriorated, and (B) fine carbon fibers fall off due to friction with electronic parts, and wear powder may be generated to reduce cleanliness. .

<(B) Fine carbon fiber>
The fine carbon fiber (B) used in the present invention is not limited, but is preferably a fine carbon fiber having an average fiber diameter of 200 nm or less. Moreover, the manufacturing method is not limited, but it can be manufactured by, for example, a vapor phase growth method (specifically, an arc discharge method, a chemical vapor decomposition method, or the like). (B) As fine carbon fiber, for example, carbon fibrils described in JP-T-8-508534 can be used.

Carbon fibrils have a graphite outer layer deposited substantially concentrically along the columnar axis of the fibrils, and the fiber center axis is not straight but has a curved tubular form. The wall thickness (wall thickness of the tubular body) of the carbon fibril having this tubular form is usually about 3.5 to 75 nm. This usually corresponds to about 0.1 to 0.4 times the outer diameter of the carbon fibrils.
The fiber diameter of the carbon fibril depends on the production method and is almost uniform.

  In the present invention, when the average fiber diameter of the fine carbon fiber (B) is larger than 200 nm, contact between the fine carbon fibers in the resin composition becomes insufficient, and a large amount is added in order to sufficiently develop the conductivity. Tends to be required, and there is a tendency that stable conductivity is difficult to obtain. Therefore, (B) a fine carbon fiber having an average fiber diameter of preferably 200 nm or less, more preferably 100 nm or less, and further preferably 50 nm or less is used.

  On the other hand, the average fiber diameter of (B) fine carbon fibers is preferably 0.1 nm or more, particularly 0.5 nm or more, more preferably 1 nm or more, and particularly preferably 2 nm or more. If the fiber diameter is smaller than this, the production becomes difficult and the cost of the product tends to increase.

  The fine carbon fibers (B) preferably have an average length / diameter ratio (length / diameter ratio, ie, aspect ratio) of 5 or more, particularly 10 or more, and particularly 100 or more. If it is such a length / diameter ratio, it is easy to form a conductive network in the resin composition, and excellent conductivity can be expressed by adding a small amount. In addition, although the upper limit of the length / diameter ratio (aspect ratio) of (B) fine carbon fiber is not limited, it is usually 10,000 or less.

The fine carbon fiber for measuring the fiber diameter and length may be (A) before being melt-kneaded with the thermoplastic resin, or may be in a state dispersed in the resin composition or in the molded product. That is, the average fiber diameter and length of the (B) fine carbon fiber mean the state of the (B) fine carbon fiber in the conductive thermoplastic resin composition of the present invention, and the resin composition is produced. It also means (B) fine carbon fiber as a raw material.
The fiber diameter and length of the fine carbon fiber before being melt-kneaded with the resin can be measured by observing this with an electron microscope. In order to measure these values by observing fine carbon fibers dispersed in the resin composition or in the molded product, for example, the resin component of the obtained resin composition or molded product is removed with a solvent, ion sputtering, or the like. Then, it can be measured by exposing fine carbon fibers and observing with an electron microscope, or observing an ultrathin section cut out from a resin composition or a molded article. In observation with such an electron microscope, the average value of the ten actually measured values is defined as the average fiber diameter and the average length.

  A commercially available thing can be used as (B) fine carbon fiber which has the said various physical properties. For example, Hyperion Catalysis International's carbon nanotube “BN”, Nanosil's carbon nanotube “NC-7000”, Showa Denko's “VGCF-S”, C-NANO's “FloTube 9000”, Korea CNT's “C-Tube” or the like can be used.

  In the conductive thermoplastic resin composition of the present invention, the blending amount of the fine carbon fiber (B) in the resin composition is 0.1 to 10% by weight, preferably 0.15 to 7% by weight, and more preferably 0. 2 to 5% by weight. (B) If the blending amount of the fine carbon fiber is less than the lower limit value, it is difficult to ensure sufficient conductivity, and if it exceeds 10% by weight, not only the surface resistance value becomes too low, but also moldability and mechanical properties. This is not preferable because (B) the fine carbon fiber falls off due to friction with the electronic component and wear powder is generated due to friction with the electronic component, resulting in a decrease in cleanliness and an increase in cost.

  The fine carbon fiber (B) used in the present invention may be treated with various surface treatment agents and dispersants. As the treating agent in this case, for example, a coupling agent such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a nonpolar segment and a polar segment block or graft copolymer, and the like can be used. . However, when the conductive thermoplastic resin composition of the present invention is used for a magnetic head tray of a hard disk, it is desirable that the (B) fine carbon fiber is not treated with a surface treatment agent or the like.

  In the conductive thermoplastic resin composition of the present invention, (A) the fine carbon fibers blended in the thermoplastic resin are each dispersed in the resin composition, one by one of the fibers. Rather, some fibers are entangled to form aggregates. The number and size of the aggregates vary greatly depending on the raw material characteristics of the resin composition such as (A) thermoplastic resin and (B) fine carbon fiber and the kneading conditions at the time of manufacturing the resin composition. The larger the value, the lower the conductivity, while the coloring power to black becomes weaker. Thus, when (B) at least a part of the fine carbon fiber is in the form of an aggregate in the resin composition, the fine carbon fiber having a diameter larger than about 50 μm is measured in the resin composition on an area basis. A molded product obtained by adding a small amount of carbon fiber aggregates, desirably fine carbon fiber aggregates having a diameter larger than 10 μm, so that the desired electrical conductivity can be reduced. It is desirable in that it does not lower the mechanical properties of the. Here, the plane base means an arbitrary two-dimensional plane (cross section).

<(C) Colorant>
The conductive thermoplastic resin composition of the present invention can be colored freely by containing (C) a colorant. In addition, in this invention, coloring means making it colors other than black, and includes not only a chromatic color but gray.
(C) The colorant is not limited and may be any substance that can adjust the lightness, hue, and saturation of the resin composition, and examples thereof include dyes, inorganic pigments, and organic pigments. Moreover, you may use these suitably together. Among these, pigments are preferable to dyes, and at least inorganic pigments are particularly preferable.

  Examples of the organic pigment include azo pigments such as insoluble azo pigments and condensed azo pigments; selenium pigments such as anthraquinone pigments, perinone pigments, perylene pigments, and thioindigo pigments; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green Nitroso pigments such as naphthol green B and naphthol green Y; various pigments such as quinacridone pigments, dioxazine pigments, isoindolinone pigments, pyrrolopyrrole pigments, aniline black, and organic fluorescent pigments.

Examples of the organic pigment include the following pigments from the viewpoint of hue.
Red pigment: Lake Red C, Lake Red D, Pigment Red 3, Pigment Red 179, Permanent Red 4R, Permanent Carmine FB, Pyrazolone Red, Pigment Orange 13, Vulcan Orange, Brilliant Carmine 6B, Resol Red, etc.
Green pigments: cyanine green, phthalocyanine green, etc.
Yellow pigments: Pigment Yellow 110, Chromofine Yellow, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, and the like.
Blue pigment: Pigment Blue 60, phthalocyanine blue, fast sky blue, and the like.
In addition, these organic pigments may use only 1 type, or may use 2 or more types together suitably.

  Examples of inorganic pigments include natural products such as clay, barite, mica and ocher; chromates such as chrome lead, zinc yellow and barium yellow; ferrocyanides such as bitumen; sulfides such as zinc sulfide; barium sulfate and the like Sulfates of chromium; Oxides such as chromium oxide, zinc oxide (zinc white), titanium oxide (titanium white), bengara, iron black, chromium oxide; hydroxides such as aluminum hydroxide; calcium such as calcium silicate and ultramarine blue Acid salts; carbonates such as calcium carbonate and magnesium carbonate; carbons such as carbon black, pine smoke, bone black and graphite; metal powders such as aluminum powder, bronze powder and zinc dust; and calcined pigments.

Examples of the inorganic pigment include the following pigments from the viewpoint of hue.
Red pigments: Bengala, Cadmium red, Molybdenum red, Komyotan (Pentan), Venice red, etc.
Green pigment: chromium oxide, cobalt green, viridian, etc.
Yellow pigment: Resurge, yellow lead, cadmium yellow, strontium yellow, barium yellow, chromium yellow, etc.
Blue pigment: ultramarine, bitumen, cobalt blue, etc.
White pigment: described later.
In addition, these inorganic pigments may use only 1 type, or may use 2 or more types together suitably.

The (C) colorant constituting the conductive thermoplastic resin composition of the present invention preferably contains at least a white pigment, and particularly preferably contains a white inorganic pigment. (C) By using a white pigment as a colorant, it is possible to improve the visibility of a molded product even with a smaller content. This has an excellent effect that the visibility can be improved without impairing the conductivity, moldability (suppression of warpage), mechanical properties, and the like of the conductive thermoplastic resin composition.
In addition, by using a white pigment and a pigment or dye other than white in combination, it is possible to adjust not only the brightness of black to gray but also various hues, brightness, and saturation while having excellent visibility. .

  In addition, you may use what gave the surface treatment as (C) coloring agents, such as a white pigment. Examples of the surface treatment agent include metal oxides such as silica, alumina, and zinc oxide; organic substances such as silane coupling agents, titanium coupling agents, organic acids, polyols, and silicones. However, when the conductive thermoplastic resin composition of the present invention is used for a magnetic head tray of a hard disk, it is desirable to use a non-surface-treated (C) colorant such as a white pigment.

<White pigment>
Below, the white pigment which is a preferable aspect of (C) a coloring agent is explained in full detail.
As the white pigment, a known white pigment can be used, which may be an inorganic pigment or an organic pigment, but is preferably an inorganic pigment from the viewpoint of thermal stability. Specific examples include titanium oxide, zinc oxide, zinc sulfide, talc, calcium carbonate, lithopone (a mixture of barium sulfate and zinc sulfide), and lead white (basic lead carbonate). One of these may be used alone, or two or more may be used in combination. Among these, titanium oxide is preferable. Titanium oxide is suitable for the white pigment of the present invention because it has high whiteness and refractive index and thus has a large coloring power even with a small addition amount.

Examples of titanium oxide include titanium oxide (TiO), titanium dioxide (TiO ₂ ), titanium trioxide (TiO ₃ ), and any of these may be used, but titanium dioxide is preferred. Depending on the production conditions, two types of crystal forms, a rutile type and an anatase type, can be used, both of which can be used, but those having a rutile type crystal structure are usually used.

  The average primary particle diameter of the white pigment is preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.4 μm, and still more preferably 0.15 to 0.35 μm. If the particle size of the white pigment is too small, the coloring effect is not sufficient, and if it is too large, the moldability and the mechanical properties of the resulting molded product may be impaired.

  Commercially available white pigments such as titanium oxide can be used. Furthermore, a lump or a large average particle size may be appropriately pulverized and classified by sieving or the like as necessary to obtain the above average particle size.

<(C) Colorant blending amount>
In the conductive thermoplastic resin composition of the present invention, the blending amount of the colorant (C) is 10 to 80% by weight, preferably 12 to 70% by weight, and more preferably 15 to 60% by weight. When the blending amount of the colorant is less than 10% by weight, the desired color tone cannot be obtained, and when it exceeds 80% by weight, not only the mechanical properties and moldability of the resulting molded product are remarkably deteriorated, but also (C) When the colorant is a particle, the number of particles that fall off increases and the cleanliness is impaired. In addition, in the case where a plurality of colorants are used in combination as the colorant (C), the total amount thereof is meant.

<Weight ratio of (C) colorant and (B) fine carbon fiber [(C) / (B)]>
Weight ratio of (C) colorant and (B) fine carbon fiber contained in the conductive thermoplastic resin composition of the present invention [(C) / (B)] (hereinafter simply “(C) / (B)” Is 5-100, preferably 5-85, more preferably 5-70. When (C) / (B) is less than 5, since the blending amount of (C) the colorant is too small relative to the blending amount of (B) fine carbon fiber, the resin composition becomes black, and (C) / (B) Is over 100, (B) the amount of fine carbon fibers is too small to obtain sufficient conductivity, or (C) the molded product obtained because the amount of colorant is too large. Not only the mechanical properties are deteriorated and the fluidity of the resin composition is deteriorated, but the number of particles dropped from the molded product is remarkably increased.

<(D) Other ingredients>
In the present invention, if necessary, an optional additive component other than (A) a thermoplastic resin, (B) fine carbon fiber, and (C) a colorant as long as the object of the present invention is not impaired in the resin composition. Can be blended.

Examples of other components that can be blended in the conductive thermoplastic resin composition of the present invention include various carbon blacks such as furnace black and acetylene black, carbon fibers (PAN-based and pitch-based), glass fibers, silica fibers, Inorganic fibrous reinforcements such as silica / alumina fibers, potassium titanate fibers, aluminum borate fibers, organic fibrous reinforcements such as aramid fibers, polyimide fibers, fluororesin fibers, mica, glass beads, glass powder, glass balloons, etc. Inorganic fillers, mold release agents, antioxidants, heat stabilizers, light stabilizers, lubricants, UV absorbers, antifogging agents, antiblocking agents, slip agents, dispersants, antibacterial agents, fluorescent whitening agents, etc. And various additives.
However, when the conductive thermoplastic resin composition of the present invention is used in a magnetic head tray of a hard disk, it contains additives such as a mold release agent, a stabilizer, a dispersant, a heat stabilizer, and an antioxidant. It is desirable not to.

<Manufacturing method>
The conductive thermoplastic resin composition of the present invention can be produced by a usual method for producing a thermoplastic resin composition, but is preferably produced by melt kneading. For example, (A) thermoplastic resin, (B) fine carbon fiber, (C) colorant, and (D) other components are banbury mixer, roll, brabender, single screw kneading extruder, twin screw kneading extruder, kneader It can manufacture by melt-kneading by.

<Melt flow rate>
The melt flow rate (MFR) of the conductive thermoplastic resin composition of the present invention is not limited, but the value at a load of 2.16 kg is usually 0.0001 to 70 g / 10 min, preferably 0.002 to 50 g / 10 min. Preferably it is 0.005-30 g / 10min. By adjusting the melt flow rate within this range, excellent conductivity, moldability (less warpage), and colorability tend to be obtained. Here, when the conductive thermoplastic resin composition is a crystalline resin composition, the measurement temperature of the melt flow rate is a temperature that is 10 ° C. or more and 100 ° C. or less higher than the melting point (Tm) of the resin composition. When the thermoplastic resin composition is an amorphous resin composition, the temperature is set to be 50 ° C. or more and 200 ° C. or less higher than the glass transition temperature (Tg) of the resin composition.

<MFR ratio>
The conductive thermoplastic resin composition of the present invention comprises a melt flow rate [MFR (5.0 kg)] at a load of 5.0 kg and a melt flow rate [MFR (2.16 kg)] at a load of 2.16 kg. The ratio [MFR (5.0 kg) / MFR (2.16 kg)] (hereinafter simply referred to as “MFR (5.0 kg) / MFR (2.16 kg)”) is 4 to 100, particularly 4 to 80, In particular, it is preferable to have a temperature range of 4 to 50. By having a temperature range in which MFR (5.0 kg) / MFR (2.16 kg) falls within this range, excellent conductivity and colorability can be obtained.
When MFR (5.0 kg) / MFR (2.16 kg) is less than 4, there is a tendency that sufficient conductivity cannot be obtained due to a small conductive network, and when it exceeds 100, (B) the fine carbon fiber Since the blending amount is excessive, coloring other than black tends to be difficult.

  In the conductive thermoplastic resin composition of the present invention, the conductivity is increased in proportion to the increase in the number of networks due to the contact between (A) fine carbon fibers dispersed in (A) the thermoplastic resin. On the other hand, since the network between the fine carbon fibers acts like a cross-linked structure, the fluidity deteriorates when the number of networks is large.

When the value of MFR (5.0 kg) / MFR (2.16 kg) is less than the lower limit value, it means that the change in the number of networks due to the change in flow rate is small. In such a case, the number and size of fine carbon fiber aggregates increase, so the coloring power to black is weakened, and coloring to other than black is easy, but on the other hand, sufficient conductivity is obtained because the number of networks is small. There is a tendency not to be able to.
On the other hand, when the value of MFR (5.0 kg) / MFR (2.16 kg) exceeds the upper limit value, it means that the change in the number of networks due to the flow rate is large. In such a case, although conductivity is obtained, since fine carbon fibers are finely dispersed, coloring other than black tends to be difficult.

  In the present invention, the raw material characteristics such as (A) thermoplastic resin, (B) fine carbon fiber, (C) colorant, and the production conditions of the resin composition are optimized so that MFR (5.0 kg) / MFR (2. By controlling 16 kg) within the above range, it is possible to obtain a conductive thermoplastic resin composition capable of obtaining sufficient conductivity and simultaneously coloring other than black.

In addition, in this invention, the measuring method of MFR of a conductive thermoplastic resin composition is measured based on JISK7210. Measurement is performed after preheating for 5 minutes without applying a load at a predetermined temperature, after 2.16 kg or 5.0 kg load is applied 5 minutes later, and then 7 minutes after 6 minutes (1 minute after the load is applied) Measure the weight up to (after 2 minutes from the start of loading).
The temperature range for measuring the MFR may be at least the temperature at which the target thermoplastic resin composition melts or flows, and less than the temperature at which it thermally decomposes. For example, in the case of a crystalline resin, a temperature range that is 10 ° C to 100 ° C higher than the melting point (Tm), and in the case of an amorphous resin, a temperature range that is 50 ° C to 200 ° C higher than the glass transition temperature (Tg). Selected. Specifically, when (A) the thermoplastic resin is polyetheretherketone (Tm = 340 to 350 ° C.), the measurement may be performed in the range of 360 ° C. to 450 ° C.

[Molding]
The molded article of the present invention can be produced by molding the above-described conductive thermoplastic resin composition of the present invention using various melt molding methods. Specific examples of the molding method include compression molding, extrusion molding, blow molding, and injection molding. Further, secondary molding such as stretch molding and vacuum molding can be performed. Among these molding methods, the compression molding method and the injection molding method are particularly preferable molding methods.

The surface resistance value of the molded product of the present invention formed by molding the conductive thermoplastic resin composition of the present invention is 1 × 10 ² Ω to 1 × 10 ¹² Ω, particularly 1 × 10 ³ Ω to 1 × 10 ^10. The surface resistance value of the molded product of the present invention is 1 × 10 ⁴ Ω or more and 1 ×, particularly when high electrostatic properties are required, such as a hard disk drive magnetic head tray. Control within the range of 10 ⁹ Ω or less is preferable in that charging is unlikely to occur and the contact current is small.

  Such control of the surface resistance value includes (A) the type and viscosity (MFR) of the thermoplastic resin, (B) the shape and blending ratio of the fine carbon fiber, and (C) the type, particle size and blending ratio of the colorant. Alternatively, the molding conditions (resin temperature, mold temperature, molding pressure, etc.) may be adjusted as appropriate to control (B) the orientation of the fine carbon fibers and the degree of relaxation thereof.

  In general, the surface resistance value can be obtained in units of (Ω / □) by converting the resistance value by the shape factor in consideration of the current wraparound in the thickness and width direction of the measurement sample. In the case of a shaped molded article, this conversion is extremely difficult. On the other hand, in practice, the apparent resistance value including the shape is important, and it is not always necessary to use the unit (Ω / □) converted by the shape. Therefore, in this invention, it evaluates with the said surface resistance value ((omega | ohm)).

[Usage]
The conductive thermoplastic resin composition of the present invention can be formed into, for example, a molded article having various shapes such as a sheet, a film, a tube, a container, and the like by the various molding methods described above.
The molded article of the present invention is suitably used in a wide range of fields that require control of static electricity, antistatic, electromagnetic shielding, dustproof adsorption prevention, and the like. For example, it is useful as a resin tray used in the process of manufacturing, transporting, and assembling various devices such as magnetic heads and ICs, and various conductive resin molded products in other electrical and electronic fields, especially for hard disk magnetic heads. It is suitably used as a tray.

  Specific applications of the molded article of the present invention include, for example, tote bins, wafer boats, wafer carriers, wafer cassettes, IC chip trays, IC chip carriers, IC transfer tubes, IC cards, tapes, and reel packing in the electrical and electronic field. , Various cases, storage trays, storage bins, transport device parts, magnetic card reader, computer housing, modem housing, monitor housing, CR-ROM housing, connector, computer slot, HD carrier, MR head carrier, GMR head carrier, HSA carrier, HDD VCM, liquid crystal panel carrier and the like.

  In the OA equipment field, charging members such as charging rolls, charging belts, static elimination belts, transfer rolls, transfer belts, and developing rolls in image forming apparatuses such as electrophotographic copying machines and electrostatic recording apparatuses; transfer drums for recording apparatuses, bushes, Examples include paper and bill transport parts, paper feed rails, font cartridges, ink ribbon canisters, guide pins, trays, rollers, gears, sprockets, printer housings, connectors, and the like.

In the field of communication equipment, mobile phone parts, pagers, cellular horn parts, various sliding materials and the like can be mentioned.
In the automotive field, interior materials, under hoods, electronic and electrical equipment housings, gas tank caps, fuel filters, fuel line connectors, fuel line clips, fuel tanks, equipment beads, door handles, fuel lines, and other various parts are listed.
In other fields, electric wires and power cable covering materials, electric wire supports, radio wave absorbers, flooring materials, carpets, insect repellent sheets, pallets, shoe soles, tapes, brushes, blower fans, planar heating elements, polyswitches, etc. It is done.

  In particular, the conductive thermoplastic resin composition of the present invention includes a wafer, a semiconductor element (IC, LSI, etc.), an electronic component (semiconductor device, circuit component, functional component, etc.), an information recording medium (magnetic disk, optical disc, etc.), etc. It is suitable for use as a tray for transporting or storing. The shape, size, and the like of the tray can be appropriately determined according to each specific application.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist.

The blending raw materials used in the following examples and comparative examples are as follows.
(A) Thermoplastic resin (A1) PEEK resin: polyether ether ketone manufactured by Victrex Japan K.K.
Resin brand name "Victrex PEEK 90G"
(MFR: 58 g / 10 min (380 ° C., 2.16 kg))
(Melting point (Tm): 343 ° C.)
(A2) PEEK resin: polyether ether ketone manufactured by Victrex Japan
Resin brand name "Victrex PEEK 381G"
(MFR: 3.8 g / 10 min (380 ° C., 2.16 kg))
(Melting point (Tm): 343 ° C.)
(A3) PPS resin: polyphenylene sulfide resin manufactured by DIC Corporation
Product name "Toprene LC-6"
(Melting point (Tm): 280 ° C.)
(B) Fine carbon fiber: carbon nanotube manufactured by Hyperion Catalysis
(Average fiber diameter: 10 nm, average fiber length: 1.25 μm,
Length / diameter ratio: 125)
(C) Colorant: Rutile type titanium dioxide manufactured by Sakai Chemical Industry Co., Ltd. Trade name “FTR-700”
(Average primary particle size: 0.20 μm)
(D) Other conductive fillers (D1) Carbon black: Acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.
Product name “Denka Black Granular”
(D2) Carbon fiber: Product name “Tenax Milled Fiber” manufactured by Toho Tenax Co., Ltd.
(Average fiber diameter: 7 μm)

[Examples 1-7, Comparative Examples 1-13]
Conductive thermoplastic resin compositions were produced and molded with the ingredients shown in Tables 1 and 2.
Table 1 at a barrel temperature of 400 ° C. and a screw rotation speed of 240 rpm using a twin screw extruder (Ikegai Iron Works, PCM-45, L / D = 32, (L: screw length, D: screw diameter)) , 2 were melt-kneaded, cooled, and then cut to produce pellets of a thermoplastic resin composition.
The obtained pellets of the conductive thermoplastic resin composition were dried with a dehumidifying dryer at 120 ° C. for 5 hours.
A sheet sample of 100 mm × 100 mm × 2 mm thickness is shown in FIG. 1 using a 130 ton injection molding machine (SE130D manufactured by Sumitomo Heavy Industries, Ltd.) using the dried pellets of the conductive thermoplastic resin composition. Each tray sample 1 was molded. The cylinder temperature and the mold temperature are: (A) When the thermoplastic resin is PEEK resin, the cylinder temperature is 400 ° C. and the mold temperature is 160 ° C. When the thermoplastic resin is PPS resin, the cylinder temperature is 340 ° C. and the mold temperature is 120 ° C. C.

  The following evaluation was performed using the obtained pellets, sheet sample, and tray sample of the conductive thermoplastic resin composition, and the results are shown in Tables 1 and 2.

<MFR>
Based on JIS K7210, it measured using the melt indexer (made by Toyo Seiki Co., Ltd.) by the above-mentioned method.
The measurement temperature was 380 ° C. when the thermoplastic resin (A) was a PEEK resin, and 320 ° C. when the thermoplastic resin was a PPS resin. In addition, the glass transition temperature (Tg) and melting | fusing point (Tm) of a conductive thermoplastic resin composition are (A) The glass transition temperature (Tg) and melting | fusing point (Tm) of PEEK resin or PPS resin used as a thermoplastic resin. There is no big difference.

<Identity>
A slider for a hard disk magnetic head (black) was placed on the sheet sample to determine whether or not the slider could be identified by the naked eye (whether it could be visually recognized) and evaluated according to the following criteria. The slider identification test was carried out indoors at a position of 1.5 m under illumination with a fluorescent lamp.
○: Recognizable with the naked eye.
Δ: Can be identified with the naked eye when staring.
×: Cannot be identified with the naked eye.

<Moldability>
About the sheet sample, the filling degree (shape reproducibility of the injection molded product with respect to the mold shape) was visually observed, and evaluated according to the following evaluation criteria as an index of fluidity.
○: There was no unfilled part, and the resin was completely filled in the cavity.
(Triangle | delta): The unfilled part less than 10 mm produced in the terminal part.
X: An unfilled portion of 10 mm or more occurred at the end portion.

<Surface resistance value>
If the resistance value is 1 × 10 ⁴ Ω or more as a resistance value measuring device, use “HIRESTA UP” manufactured by Dia Instruments, and if the resistance value is less than 1 × 10 ⁴ Ω, “Milliohm” manufactured by Hioki Electric Co., Ltd. Using “Hitester 3540”, the surface resistance value of the sheet sample was measured.
As the “Hiresta UP probe”, a UA probe (two probe probes, distance between probes: 20 mm, probe diameter: 2 mm) was used. Applied voltage, the resistance value of 1 × 10 ⁴ Ω or more, if it is less than 1 × 10 ⁶ Ω 10V, was 100V when the resistance value is 1 × 10 ⁶ Ω or more. A conductive rubber (volume low efficiency: 5 Ω · cm) was attached to the tip of the contact pin with a conductive adhesive to stabilize the contact with the surface of the sheet sample.
Further, a clip-type lead 9287-10 was used as a probe of “Milliohm Hitester 3540”. A conductive rubber similar to the above was also attached to the tip of this probe.
The surface resistance value in the present invention does not include a shape factor such as thickness.
The lower the surface resistance value, the better the conductivity, and it is preferable to be in the range of 1 × 10 ² Ω to 1 × 10 ¹² Ω.

<Molded product warpage>
A tray sample 1 having the shape shown in FIG. 1 was placed on a flat board without unevenness. The tray sample 1 has a square shape in plan view and has a total height h = 4.4 mm having a stepped portion 1B at the outer peripheral edge of the central plate surface. The height of nine points on the central plate surface 1A of this tray sample was measured, and the difference in height between the place with the largest height and the place with the smallest height was taken as the amount of warpage.
The smaller the value of the warp amount, the smaller the unevenness on the surface of the molded product and the more flattened it is, and it is preferably 200 μm or less.

<Fine particle generation>
The tray sample 1 shown in FIG. 1 was immersed in 2 L of ultrapure water and irradiated with ultrasonic waves (38 kHz) for 3 minutes. Then, after immersing again in 2 L of ultrapure water and irradiating with ultrasonic waves (38 kHz) for 3 minutes, this water was collected, and a measuring device (manufactured by Lion Co., Ltd., liquid particle sensor: KS-58, liquid particles) The number of fine particles was counted by a sampler: KZ-30, a particle counter in liquid: KL-11).
Particulate generation amount value less shedding of particles from the smaller the surface of the molded article, indicates that excellent cleanliness is preferably 5,000 / cm ² or less.

Table 1 shows the following.
(C) In Comparative Examples 1, 2, 5, and 10 in which no colorant is blended, the molded product is black, so the discrimination is poor.
In Comparative Examples 3 and 4, since the blending amount of the colorant (C) is small ((C) / (B) is small), the distinguishability is poor. In Comparative Example 4, (B) the amount of fine carbon fiber blended is large, so the moldability and warpage are further inferior.
(B) In Comparative Examples 5, 6, and 11 in which carbon black is used in place of the fine carbon fibers, the distinguishability and moldability are poor, and the amount of warpage is large.
Comparative Examples 7 and 12 with a small amount of carbon black are good in distinguishability and moldability, but have a large surface resistance value and poor conductivity, and Comparative Example 7 has a large amount of warpage.

  (B) Comparative Examples 8, 9, and 13 using carbon fibers instead of fine carbon fibers have good discrimination and moldability, but have a large amount of warpage, a large amount of fine particles, and a cleanliness. Inferior.

On the other hand, the conductive thermoplastic resin composition of the present invention using (B) fine carbon fiber and (C) colorant in a predetermined blending ratio is excellent in distinguishability, moldability, and conductivity, and warps. The amount is small, there is little dropout of fine particles, and the cleanness is excellent.
In addition, since all the resin compositions of Examples 1 to 7 have a gray color tone, they can be colored in a desired color by further using a chromatic colorant.

  1 Tray sample

Claims (9)

(A) A thermoplastic resin composition comprising 89.9 to 10% by weight of a thermoplastic resin, (B) 0.1 to 10% by weight of fine carbon fibers, and (C) 10 to 80% by weight of a colorant. A thing,
The conductive thermoplastic resin composition, wherein the weight ratio [(C) / (B)] of (C) the colorant and (B) fine carbon fibers is 5 to 100.   Ratio [MFR (5.0 kg) / MFR (2) between melt flow rate [MFR (5.0 kg)] at a load of 5.0 kg and melt flow rate [MFR (2.16 kg)] at a load of 2.16 kg .16 kg)] has a temperature range of 4 to 100. The conductive thermoplastic resin composition according to claim 1.   (A) The thermoplastic resin is polyether ether ketone resin, polyphenylene sulfide resin, polyether imide resin, polyether sulfone resin, polysulfone resin, polyarylate resin, modified polyphenylene ether resin, polyacetal resin, polyamide resin, styrene resin The conductive thermoplastic resin composition according to claim 1 or 2, comprising one or more selected from the group consisting of a resin and a polyolefin-based resin.   The conductive thermoplastic resin composition according to claim 3, wherein (A) the thermoplastic resin contains a polyether ether ketone resin having a melt flow rate at 380 ° C. and a load of 2.16 kg of 3.0 g / 10 min or more.   (B) The conductive thermoplastic resin composition according to any one of claims 1 to 4, wherein the fine carbon fibers have an average fiber diameter of 200 nm or less.   The conductive thermoplastic resin composition according to claim 1, wherein (C) the colorant is titanium dioxide.   A molded article formed by molding the conductive thermoplastic resin composition according to any one of claims 1 to 6. The molded product according to claim 7, wherein the surface resistance value is 1 × 10 ² Ω or more and 1 × 10 ¹² Ω or less.   The molded product according to claim 7 or 8, which is a tray for a hard disk magnetic head.

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