JP2000218711A - Carbon fiber-containing thermoplastic resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber-containing thermoplastic resin molded product excellent in mechanical characteristics, electric characteristics and a surface state. SOLUTION: In a carbon fiber-containing thermoplastic resin molded product, a thermoplastic resin being a matrix is 70-99.5 wt.% and the total content of a carbon fiber in the molded product is 0.5-30 wt.% and the content of the carbon fiber with a length of above 1.5 mm is set to 0.1-4.7 wt.% (based on the total content of the thermoplastic resin and the carbon fiber), that of the carbon fiber with a length of 0.5-1.5 mm is set to 0.2-10.7 wt.% and that of the carbon fiber with a length of below 0.5 mm is set to 0.2-14.6 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a molded article of a thermoplastic resin containing carbon fibers. For more details,
The present invention relates to a carbon fiber-containing thermoplastic resin molded article having excellent mechanical and electrical properties.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of electronic devices, in order to prevent erroneous operation of electronic devices and to prevent influence on the human body, conductive materials such as housings used for personal computers, mobile phones, automobile parts, and the like are used. It is required to provide a function and shield the electromagnetic waves. In addition, molded articles of thermoplastic resin, which are easy to mold, are being used for IC trays used for transporting ICs. However, in order to protect ICs from static electricity, IC trays made of thermoplastic resin are used. It is required to have conductivity and to provide an antistatic function. Furthermore, metal is conventionally used for the cassette reel of the magnetic tape, the paper feed roller of the copying machine, etc.
It is being replaced with thermoplastic resin molded products that are easy to mold, and with this, it is required to provide a conductive function to thermoplastic resin cassette reels and paper feed rollers to prevent electrification. I have.

As a method for imparting a conductive function to a thermoplastic resin molded article, there is a method using a conductive resin.
Since the conductive resin used is expensive, it is not practical. For this reason, a method is generally used in which a molded article has a conductive function while using a general thermoplastic resin currently on the market. As a method of imparting a conductive function to a general thermoplastic resin molded article, there are roughly the following two methods. One is a method of forming a conductive molded product by forming a conductive film on the surface of the molded product by surface treatment such as plating or vapor deposition after molding with a thermoplastic resin. The other is to blend a conductive material in powder form such as carbon black or metal or a fibrous conductive material such as metal fiber or carbon fiber into a thermoplastic resin, and process this to form a conductive molded product. Is the way.

[0004] Among them, the former method of forming a conductive film is a two-step process of molding with a thermoplastic resin and surface treatment by plating or vapor deposition, and is inferior in manufacturing economics. There's a problem. On the other hand, the latter method of blending a conductive material with a thermoplastic resin has an advantage that processing in only one step of molding is sufficient.

When a conductive material is blended with a thermoplastic resin to provide a conductive function, a powdery conductive material or a fibrous conductive material is used. The fibrous conductive material has better conductivity. This is because conductive materials dispersed in the thermoplastic resin come into contact with each other to exhibit a conductive function, but fibrous conductive materials are more likely to interact with each other than powdery conductive materials. Based on easy contact.
Therefore, it can be understood that, even with the same fibrous conductive material, a longer conductive material can provide a higher conductive function. As described above, as the fibrous conductive material, a metal fiber or a carbon fiber can be used as described above. In order to provide an excellent conductive function, among these, a carbon fiber having excellent affinity with a resin, particularly a long fiber is preferred. Fibrous carbon fibers are most preferred.

[0006] A method of imparting a conductive function by using long fibrous carbon fibers is roughly classified into the following two methods.

(1) A method in which chopped fibers obtained by cutting rovings of carbon fibers are melt-kneaded with a thermoplastic resin to obtain thermoplastic resin pellets containing carbon fibers, which are then melted and molded again.

(2) Pultrusion method, that is, extruding a thermoplastic resin while aligning the roving of carbon fiber under tension, cutting the pellet, cutting the pellet, etc. A method of melting and molding a plastic resin pellet. Molded articles by this method
Japanese Patent Publication No. 5-28828 discloses that a carbon fiber having a length of 1.5 to 15 mm is formed in a molded product.
It is characterized in that it is present in an amount of 5 to 35 parts by weight (the amount of carbon fibers in the molded product is 4.8 to 26% by weight) based on parts by weight.

[0009]

However, in the prior art, the carbon fibers were too fine, and sufficient strength and excellent electromagnetic wave shielding properties could not be obtained. On the other hand, when the carbon fibers in the molded article are kept long or when a large amount of carbon fibers are contained, even if sufficient strength is obtained, the appearance of the molded article is inferior and can be practically used. Was not.

[0010] The object of the present invention, in view of the above situation,
An object of the present invention is to provide a molded article having excellent mechanical properties, electrical properties, and surface condition.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to obtain a molded article having the above-mentioned properties. As a result, surprisingly, the long fiber in the molded article is reduced to a certain amount or less. It has been found that a molded article having excellent mechanical properties and electrical properties, particularly excellent surface appearance, can be obtained by imparting a distribution of carbon fibers, and the present invention has been completed.

That is, according to the present invention, in a thermoplastic resin molded article containing carbon fibers, the thermoplastic resin as a matrix is 70 to 99.5 wt%, and the total content of carbon fibers contained in the molded article is 0.5%. -30% by weight, and (a)
Carbon fiber with a length exceeding 1.5 mm is 0.1 to 4.7 w
t% (based on the total amount of thermoplastic resin and carbon fiber; the same applies hereinafter), (b) 0.2 to 10.7 wt% of carbon fiber having a length of 0.5 to 1.5 mm, and (c) 0.5 mm The present invention relates to a molded article of a carbon fiber-containing thermoplastic resin, wherein the carbon fiber having a length of less than 0.2 to 14.6 wt%.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0014] The carbon fiber used in the present invention is not particularly limited in raw material, but for example, carbon fiber produced from polyacrylonitrile, pitch or the like can be used. Further, carbon fibers having a conductive metal film formed on the surface can also be used. The conductive metal film can be formed by plating or the like, and the conductive function of the obtained molded article can be improved. The carbon fiber diameter is preferably 2 to 10 μm. If it is less than 2 μm, the dispersibility in the thermoplastic resin tends to deteriorate, and
If it exceeds m, it will be easy to break during the molding process, and it will be difficult to incorporate it in a molded product at a predetermined length.

The thermoplastic resin, which is a matrix used in the present invention, is not particularly limited, and can be arbitrarily selected from those conventionally used as molding materials. For example, a styrene resin, a polyphenylene ether resin, a polyolefin resin, a polyvinyl chloride resin, a polyamide resin, a polyester resin, a polyacetal resin, a polycarbonate resin, and an acrylic resin are exemplified.

Examples of the styrene resin include a homopolymer such as styrene and α-methylstyrene, a copolymer thereof, and a copolymer with an unsaturated monomer copolymerizable therewith. Specifically, general-purpose polystyrene (GPPS), impact-resistant polystyrene (HIP)
S), heat-resistant polystyrene (for example, α-methylstyrene polymer or copolymer), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-butadiene-styrene-α-methylstyrene copolymer (α- Methylstyrene heat resistant ABS), acrylonitrile-butadiene-styrene-phenylmaleimide copolymer (phenylmaleimide heat resistant ABS), acrylonitrile-styrene copolymer (AS), acrylonitrile-chlorinated polystyrene-styrene copolymer (AC
S), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES), acrylic rubber-acrylonitrile-styrene copolymer (AAS), syndiotactic polystyrene (SPS) and the like.
Further, the styrene resin may be a polymer blend.

Polyphenylene ether resin (PPE)
For example, poly (2,6-dimethyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-)
Examples thereof include homopolymers such as (1,4-phenylene) ether, and a homopolymer modified with a styrene-based resin can also be used.

Typical polyolefin resins are homopolymers of α-olefins such as ethylene, propylene, butene-1, 3-methylbutene-1, 3-methylpentene-1, and 4-methylpentene-1. Or copolymers of these, or copolymers of these with other copolymerizable unsaturated monomers, and the like. Representative examples include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high-molecular-weight polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-octene- Polyethylenes such as metallocene-based ethylene-α-olefin copolymers such as 1 copolymer, atactic polypropylene, syndiotactic polypropylene, isotactic polypropylene or propylene-ethylene block copolymer or random copolymer and polypropylenes, Polymethylpentene-1 and the like can be mentioned.

Examples of the polyvinyl chloride resin include a vinyl chloride homopolymer and a copolymer of vinyl chloride with an unsaturated monomer copolymerizable with vinyl chloride. Specifically, vinyl chloride-acrylate copolymer, vinyl chloride-methacrylate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-
Examples thereof include a vinyl acetate copolymer and a vinyl chloride-vinylidene chloride copolymer. Further, those obtained by chlorinating these polyvinyl chloride resins to increase the chlorine content can also be used.

Examples of the polyamide resin (PA) include those obtained by ring-opening polymerization of a cyclic aliphatic lactam represented by, for example, 6-nylon or 12-nylon, 6,6-nylon, 6,10-nylon, Examples thereof include those obtained by polycondensation of an aliphatic diamine such as 12-nylon and an aliphatic dicarboxylic acid, and those obtained by copolycondensation of an aromatic diamine and an aromatic dicarboxylic acid in some cases.

Examples of the polyester resin include those obtained by polycondensing an aromatic dicarboxylic acid with an alkylene glycol such as ethylene glycol, propylene glycol or butylene glycol. As a specific example,
Examples thereof include polyethylene terephthalate (PET), polypropylene terephthalate (PPT), and polybutylene terephthalate (PBT).

As the polyacetal resin (POM),
For example, a homopolymer polyoxymethylene or a formaldehyde-ethylene oxide copolymer obtained from trioxane and ethylene oxide is exemplified.

Examples of the polycarbonate resin include 4,4'-dihydroxydiarylalkane polycarbonate. Specific examples include bisphenol A-based polycarbonate (PC), modified bisphenol A-based polycarbonate, flame-retarded bisphenol A-based polycarbonate, and the like.

Examples of the acrylic resin include methacrylate, acrylate homopolymer, copolymers thereof, and copolymers of these with other copolymerizable unsaturated monomers. . Examples of the methacrylate and acrylate monomers include methyl, ethyl, n-propyl, isopropyl and butyl esters of methacrylic acid or acrylic acid. Typically, a methacrylic resin (PMMA) is used.

These thermoplastic resins may be used alone or in combination of two or more. In addition, to these thermoplastic resins, a heat stabilizer, an ultraviolet absorber, a light stabilizer, an antioxidant, a plasticizer, a release agent, a lubricant, a flame retardant, a coloring agent (dye, pigment) and the like may be added. Is also possible. Further, in order to adjust the conductivity of the present invention, other conductive materials and the like can be used together.

It is preferable that the carbon fibers are adhered and coated with a resin compatible with the thermoplastic resin as the matrix. Here, the term “adhesive coating” means, for example, when roving is used as carbon fiber, includes coating on the surface of one or more carbon fibers, or coating on the surface of the roving, etc. It is preferable to coat them in a single layer because of good dispersibility in the thermoplastic resin as the matrix. The resin that is compatible with the thermoplastic resin that is the matrix is not particularly limited as long as it generally has an affinity with the thermoplastic resin that is the matrix. The purpose of adhesion coating with such a resin is to uniformly disperse the carbon fibers in the thermoplastic resin. That is, usually, when carbon fiber and thermoplastic resin that have not been subjected to any surface treatment are mixed, it is difficult to mix them, and it is difficult for the carbon fibers to be uniformly dispersed in the thermoplastic resin. When using a carbon fiber that has been subjected to a surface treatment that adheres and coats a compatible resin, when mixed with a thermoplastic resin, each carbon fiber is easily loosened and easily dispersed in the thermoplastic resin. Become.

As the resin compatible with the thermoplastic resin serving as the matrix, any of epoxy or urethane-based thermosetting resins and general thermoplastic resins such as styrene-based resins and polyolefin-based resins can be used. . Among these, a material which can be easily subjected to surface treatment for adhering and coating a carbon fiber is most preferable in terms of industrial implementation. In the case of a thermosetting resin, the surface treatment can be performed by applying a monomer as a surface treatment agent and then curing it. In the case of a thermoplastic resin, the method can be carried out by applying a surface treating agent such as a solution or aqueous dispersion of a solvent and then drying or applying a melt extrusion coating of the thermoplastic resin. Among them, the method of using a resin emulsion using water as a medium as a surface treatment agent or the method of melt-extruding and coating a thermoplastic resin is environmentally friendly, and a simple method because a post-treatment step such as a curing treatment is unnecessary. Is most preferred.

Specific examples of the above resin emulsion include:
Styrene-butadiene resin emulsion (SB latex), styrene-based emulsion such as acrylonitrile-styrene resin emulsion or styrene-acrylic acid resin, acrylic emulsion such as methyl methacrylate-2-ethylhexyl acrylate-butyl acrylate resin emulsion, ethylene-vinyl acetate In addition to a resin emulsion or an ethylene emulsion such as an ethylene-methacrylic acid resin emulsion, a vinyl acetate emulsion, a urethane emulsion, and the like can be given.

The resin emulsion used to adhere and coat the carbon fibers with a resin compatible with the thermoplastic resin as the matrix is preferably selected according to the type of the thermoplastic resin as the matrix. Examples thereof include, but are not limited to, a polystyrene-based resin and a modified polyphenylene ether-based resin as a matrix, a styrene-butadiene resin emulsion, and a matrix as a thermoplastic resin.
In the case of S, ABS, PMMA, PET, PC resin, acrylonitrile-styrene resin emulsion, thermoplastic resin is polyolefin resin, in case of POM, ethylene-vinyl acetate resin emulsion, matrix thermoplastic resin is polyamide resin In this case, a urethane emulsion or the like is preferable. As the emulsion, a commercially available emulsion having a solid concentration of 30 to 70% can be used as it is or after dilution.

As a method of applying an adhesive coating on a carbon fiber with a resin compatible with a thermoplastic resin as a matrix,
For example, when using a solution or emulsion of a resin compatible with the thermoplastic resin as the matrix, a spray method of spraying the solution or emulsion on carbon fiber roving, an immersion method of immersing carbon fiber in the solution or emulsion, etc. Can be adopted.

The carbon fiber may be adhered and coated with a resin compatible with the thermoplastic resin as the matrix. That is, for example, the above-described treatment with a resin emulsion or the melt extrusion coating of a thermoplastic resin may be performed a plurality of times to perform adhesion coating of a plurality of layers. Alternatively, a plurality of different layers of resin may be applied and coated, for example, after applying and coating a thermosetting resin such as an epoxy or urethane-based resin, by applying a resin emulsion, or performing a melt extrusion coating of a thermoplastic resin.

The amount of the emulsion or the like of a resin compatible with the thermoplastic resin serving as the matrix is preferably 0.5 to 50% by weight in solid content, more preferably 5 to 20% by weight in solid content. is there. If it is less than 0.5 wt%, good dispersibility is difficult to obtain, and if it exceeds 50 wt%, it is likely to be economically disadvantageous.

The molded article of the present invention can be roughly divided into the following two methods. One is a method using resin pellets containing carbon fiber, and the other is a method using a blend of carbon fiber and thermoplastic resin pellets.

In the former method, a carbon fiber roving is coated with a thermoplastic resin as a matrix, preferably by extrusion coating, and then molded using resin pellets containing cut carbon fibers. More preferably, a resin compatible with the thermoplastic resin as the matrix is attached to the carbon fiber roving in advance, dried if necessary, and further coated with the thermoplastic resin as the matrix, preferably extruded, and then cut. It is molded using resin pellets containing the carbon fibers. At this time, it is also possible to dilute a resin pellet containing carbon fibers with a thermoplastic resin pellet which is a matrix and does not contain carbon fibers, and form the resin pellet. The pellet of the thermoplastic resin as the matrix used for dilution may be the same as or different from the thermoplastic resin coated on the carbon fiber. If different, it is preferred that the thermoplastic resin coated on the carbon fiber does not delaminate and separate from the thermoplastic resin, and it is preferable to use one that is as compatible as possible.

In the latter method, a carbon fiber obtained by cutting carbon fiber roving and a thermoplastic resin as a matrix are blended to form a blend. Preferably, a resin that is compatible with the thermoplastic resin as the matrix is previously coated on the carbon fiber roving, and dried and then cut as necessary,
A thermoplastic resin pellet as a matrix is blended to form a blend. At this time, the thermoplastic resin as the matrix to be blended with the carbon fiber may be one kind or a mixture of several kinds.

The pellet length of the resin pellet cut product containing the thermoplastic resin and the carbon fiber as the matrix used in the above molding or the fiber length of the thermoplastic resin and the carbon fiber cut product (the pellet length of the cut product) Alternatively, the fiber length of the cut carbon fiber product is equivalent to the fiber length before molding) is one factor that determines the length of the carbon fiber in the molded product, and this length should be 2 to 10 mm And more preferably 3 to 7 mm. If it is less than 2 mm, the effect of imparting conductivity tends to be small, and if it exceeds 10 mm, a bridge is likely to occur in a hopper or the like at the time of molding, and the moldability tends to deteriorate.

The molding method of the molded article of the present invention is not particularly limited, but for example, extrusion molding, injection molding, blow molding and the like can be used.

The carbon fiber in the molded article of the present invention thus obtained has a total content of 0.5 to 30% by weight, preferably 0.5 to 25% by weight, more preferably 0.5 to 2% by weight.
0% by weight, and the carbon fiber having a length exceeding 1.5 mm needs to be 0.1 to 4.7% by weight.
If the total content of carbon fibers is less than 0.5 wt%, it is difficult to provide a conductive function. If the total content exceeds 30 wt%, the flowability during molding is reduced, or the surface condition is improved. There arises a problem that the product cannot be obtained. 1.
If the carbon fiber having a length exceeding 5 mm is less than 0.1 wt%, the conductive function is low. If the carbon fiber exceeds 4.7 wt%, the surface condition of the molded article is deteriorated, and the practical commercial value is reduced. At the same time, even if the carbon fiber content in the resin is the same, the conductive function decreases. That is, if the molding process is performed in a direction that leaves a long carbon fiber during molding, the direction becomes inevitable to share, and as a result, the carbon fiber hardly disperses in the thermoplastic resin, resulting in localization (carbon fiber The dispersion state of the resin becomes uneven in the resin, causing variations)
However, unevenness due to fluffing and agglomeration of carbon fibers is generated, the surface condition is deteriorated, and parts where the carbon fibers are not in contact with each other due to localization are generated, and even if the content of the carbon fibers in the resin is the same, the conductive state is maintained. Sexual function is reduced.

The major features of the present invention are as described above.
0.1 to 4.7 wt% carbon fiber with a length exceeding 5 mm
Preferably, the carbon fiber having a length exceeding 1.5 mm is 0.1 to 4.7 wt%, the carbon fiber having a length of 0.5 to 1.5 mm is 0.2 to 10.7 wt%, 0.5mm
Less than 0.2 to 14.6 wt% of the carbon fibers. The ratio of the carbon fiber having a length exceeding 1.5 mm, the carbon fiber having a length of 0.5 to 1.5 mm and the carbon fiber having a length of less than 0.5 mm is preferably 1 in weight ratio.
/0.5 to 2.5 / 0.5 to 3.0, more preferably 1 / 1.0 to 2.5 / 0.8 to 3.0. Only by providing such a distribution of carbon fibers in a molded article can a molded article be most balanced in mechanical strength, conductive function, surface condition and the like. this is,
It is considered that the subtle entanglement between the long carbon fibers and the short carbon fibers in the thermoplastic resin as the matrix exerts its effect.

There are various factors that control the length of the carbon fiber in the molded article, and the main factors include the length of the carbon fiber before molding and how to apply the shear during molding. Can be Therefore, for example, the pellet length of the resin pellet cut product or the carbon fiber cut product length,
The melt viscosity of the thermoplastic resin that is the matrix used,
Molding processing conditions (molding temperature, back pressure, screw structure, screw rotation speed, injection speed, tip nozzle shape,
The length of the carbon fiber in the molded article can be controlled by the shape and diameter of the gate).

The carbon fiber-containing thermoplastic resin molded article according to the present invention has excellent conductivity and excellent surface condition, and can be used for various applications. Specific examples are listed below.

(1) Electromagnetic wave shielding molded article By giving the molded article a conductive function, for example, a housing or an interior part of an electronic / electric device such as a personal computer, a word processor, a CD player, a headphone stereo, a mobile phone, a transceiver, a camera, etc. Alternatively, it can be used for an electromagnetic wave shielding molded product such as an interior part of a pachinko machine. The total content of carbon fibers contained in the cast used for these applications is preferably 2 to 30%.
wt%, more preferably 5 to 25 wt%, particularly preferably 10 to 20 wt%. Further, the carbon fiber having a length exceeding 1.5 mm is preferably 0.1 to 4.7 wt%,
More preferably, it is 0.5 to 4.7% by weight. Volume resistivity of the molded article is preferably 10 ^-4 ~10 ³ Ω · c
m, more preferably 10 ^-4 ~10Ω · cm, even more preferably 10 ^-4 ~1Ω · cm.

(2) Resin Resistor A molded article having a conductive function can be used as an electric resin resistor. For example, an electric resistor of a variable resistor or an electric resistor used for an electric circuit,
In particular, it can be used for high-resistance resistors. When used for these applications, the total content of carbon fibers contained in the molded product is preferably 0.5 to 5 wt%, more preferably 1.0 to 5 wt%. Further, the carbon fiber having a length exceeding 1.5 mm is preferably 0.1 to 4.7 wt%,
More preferably, it is 0.5 to 2.5 wt%. The volume resistivity of the molded product is preferably 10 ² to 10 ¹³ Ω · cm.
It is.

(3) Sliding parts having antistatic properties By imparting a conductive function and an abrasion resistance function to a molded product, for example, a cassette reel of a magnetic tape, a paper feed roller of a copying machine, and a bearing of various rotating members. And the like, it can be used for sliding parts that move with contact with other parts or members. The carbon fiber-containing thermoplastic resin molded article of the present invention has excellent abrasion resistance. In these applications, antistatic properties are required, and when used in these applications, the total content of the carbon fibers contained in the molded article is preferably 0.5 to 1
0 wt%, more preferably 1.0 to 10 wt%. The carbon fiber having a length exceeding 1.5 mm is
0.1 to 4.7 wt%, more preferably 0.5 to 4.0
wt%. Volume resistivity of the molded article is preferably 10 ⁰ ~10 ¹² Ω · cm.

(4) IC Tray A molded article having a conductive function can be used for an IC tray used for transporting ICs. In this application,
In order to protect the IC from static electricity, antistatic properties are required. When used for this purpose, the total content of carbon fibers contained in the molded product is preferably 0.5 to 5.0 watts.
t%, and more preferably 1.0 to 5.0 wt%. Further, the carbon fiber having a length exceeding 1.5 mm is preferably 0.1 to 4.7% by weight, more preferably 0.5% by weight.
~ 2.5 wt%. The surface resistance of the molded product is preferably 10 ² to 10 ¹⁰ Ω.

The molded article of the present invention can be plated on the molded article in order to further improve the conductivity of the molded article. It is also possible to perform electrostatic coating for the purpose of improving the gloss of the surface state, coloring, and the like.

[0047]

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

Apparatus used in Examples and Comparative Examples
Materials and measurement / evaluation methods are as shown below.

1. Pellet manufacturing equipment ・ Tumbler: Twin cone type manufactured by Niei Electric Co., Ltd., rotation speed 20 to 40 rpm ・ Single screw extruder: “VS-3” manufactured by Tanabe Plastics Co., Ltd.
・ Twin-screw extruder: “TEM-35B”, Toshiba Machine Co., Ltd.

2. Injection molding machine-1: Toshiba Machine Co., Ltd. "IS55EPN" Injection molding machine-2: Komatsu Ltd. "IP1050"

3. Thermoplastic resin ・ HIPS: “Styrone EXG1” manufactured by Asahi Kasei Corporation
1) ・ PMMA: “Delpet 80N” manufactured by Asahi Kasei Kogyo Co., Ltd. ・ AS: “Stylac AS78” manufactured by Asahi Kasei Kogyo Co., Ltd.
・ ABS: "Stylac ABS" manufactured by Asahi Kasei Corporation
・ ABS: Asahi Kasei Kogyo Co., Ltd. “Stylac ID3”
2F "・ PPE:“ Zylon 100Z ”manufactured by Asahi Kasei Kogyo Co., Ltd. ・ PPE:“ Zylon X983 made by Asahi Kasei Kogyo Co., Ltd. ”
0 ”• PE:“ Santetsu HD J3 ”manufactured by Asahi Kasei Corporation
・ PE: Asahi Kasei Kogyo Co., Ltd. “Santetsu HD J7”
51 ”• PP:“ J-Allomer M1700 ”manufactured by Nippon Polyolefin Co., Ltd. • POM:“ Tenac-C451 ”manufactured by Asahi Kasei Kogyo Co., Ltd.
0 ”PA:“ Leona 1300S ”manufactured by Asahi Kasei Corporation

4. Resin compatible with thermoplastic resin (carbon fiber surface treatment agent) SB emulsion: styrene-butadiene resin latex (solid content 40 wt%) AS emulsion: acrylonitrile-styrene resin latex (AN 25%, solid content 50 wt%) EVA emulsion: ethylene-vinyl acetate resin latex (vinyl acetate 20 wt%, solid content 50 wt%) Urethane emulsion: urethane resin latex (solid content 40 wt%)

5. Conductive material (carbon fiber)-Carbon fiber roving (CF-R): "HTA-12K" manufactured by Toho Rayon Co., Ltd.-Chopped fiber (C-CF): "A6000" manufactured by Mitsubishi Rayon Co., Ltd.

6. Measurement / Evaluation Method (a) Measurement of glossiness Using an injection molding machine-1, set the cylinder temperature to a molding temperature suitable for the thermoplastic resin to be used. At a mold temperature of 60 ° C. and a mirror surface plate (width 50 mm × length 9).
0 mm x thickness 2.5 mm). The surface gloss of this plate was measured using a portable gloss meter “HG-” manufactured by Suga Test Instruments Co., Ltd.
268 "at a measurement angle of 60 degrees.

(B) Measurement of Volume Specific Resistance A silver paste is applied to both sides of the plate in the longitudinal direction (the flow direction of the resin during molding), and after drying, the resistance value (R _L ) is measured with a tester. From R ₁ = _RL × _AL / L ( _AL : sectional area, L: length), volume specific resistance R ₁ (Ω · cm)
Was calculated.

(C-1) Measurement of surface resistance value (when the surface resistance value is 10 ⁷ Ω or less) A silver paste having a width of 2 mm is parallel to both ends of the plate in the length direction (the flow direction of the resin during molding). , And after drying, the resistance value (R _s ) was measured with a tester, and R ₂ = R _s ×
The surface resistance R ₂ (Ω) was calculated from Y / Z ₂ (Y: length of the applied silver paste, Z ₂ : distance between the two applied silver pastes).

(C-2) Measurement of Surface Resistance Value (When Surface Resistance Value Exceeds 10 ⁷ Ω) The above plate was used to measure 500 V with a conductivity measuring device “SME-8310” manufactured by Toa Denpa Kogyo KK And then measured after charging and discharging for 1 minute.

(D) Evaluation of dispersibility of carbon fiber Using an injection molding machine-1, molding temperature and drying were the same as above, and titanium dioxide was added to 100 parts by weight of resin to facilitate evaluation. One part by weight was added, a gray colored plate was formed, and the presence or absence of carbon fiber aggregation was visually judged. O was not generated, Δ was slightly generated, and X was generated many.

(E) Evaluation of Surface Condition The appearance of the plate whose glossiness was measured was visually evaluated. There is no problem in appearance, and those of commercial value are ○, fuzzy, those in which some uneven appearance such as unevenness due to carbon fiber agglomeration are △, poor appearance such as unevenness due to fluffing, carbon fiber agglomeration Those were marked as x.

(F) Length of Carbon Fiber in Molded Product Using an injection molding machine-1, molding temperature and drying were performed in the same manner as described above to obtain a molded product. A straight line is drawn from the gate part to the end part of the molded product, and a test piece for measurement is cut out from an intermediate length of 80%, and the test piece is placed in air for 5 minutes.
The mixture was baked at 00 to 600 ° C. for 30 minutes, and the baked product was observed with an electron microscope to measure the length and distribution of carbon fibers contained in the molded product.

(G) Measurement of flexural strength and flexural modulus Measured according to ASTM D790.

(H) Measurement of Electromagnetic Wave Shielding Effect Using an injection molding machine-2, a cylinder temperature is set to a molding temperature suitable for a thermoplastic resin to be used. According to the plate (width 100 mm x length 100 mm x thickness 2 mm)
Was molded. This plate was measured using an Anritsu Corporation network analyzer “MS4661A” in an electromagnetic dark box in a frequency range of 100 to 1000 MHz.
It was represented by an attenuation value of 500 MHz.

(I) Measurement of Dynamic Friction Coefficient and Amount of Abrasion A plate for measuring surface gloss was attached to a sample table of a reciprocating friction and abrasion tester (“AFT-15MS” manufactured by Tosoh Seimitsu Kogyo Co., Ltd.), and a mating member was placed from above. SUS3 with a diameter of 5mm
The sample table was reciprocated in a state where the precision sphere made of 04 was pressed, and the frictional force at the time of the 100th reciprocation was measured and converted into a dynamic friction coefficient. The amount of abrasion was measured by removing the plate as a sample after the reciprocating motion 1000 times, and measuring the dent of abrasion marks formed on the surface of the sample with a surface roughness meter (“Surfcom 575A-3D” manufactured by Tokyo Seimitsu Co., Ltd.). . The conditions at this time are as follows: a pressure load of 3 kg, a reciprocating distance of 20 mm, and a moving speed of 30 mm.
mm / sec.

Example 1 A carbon fiber roving (CF-R) having a diameter of 7 μm was immersed in an AS emulsion, the emulsion was squeezed so that the solid content of the emulsion adhered to 20 wt% on a dry basis, and the amount of the emulsion was adjusted and dried. . Thereafter, the ABS is extruded by a single screw extruder, and the carbon fiber roving is extrusion-coated with the ABS so that the carbon fiber concentration in the pellets is 15 wt%.
The strand was cut with a cutter so as to have a length of 5.5 mm, and a resin pellet containing carbon fibers was prepared.
At the time of this strand cutting, there was no fluffing of the carbon fiber or falling off from the pellet, and the resin pellet could be produced smoothly.

The injection molding machine-1 was set at a resin temperature of 220 ° C.
Back pressure: 20 kg / cm ² G, screw rotation speed: 100
rpm, injection speed: 80% of the equipment specifications, gate shape: set to a pin gate of 1 mmφ, and molding was performed using the resin pellets to obtain a molded product. The dispersibility of the carbon fibers in the molded article was extremely good, and 1.5% in the molded article.
The length of the carbon fibers having a length exceeding 5.5 mm (max 5.5 mm) was 3.3 wt%. The carbon fiber having a length of 0.5 to 1.5 mm is 5.0 wt%, and the carbon fiber having a length of less than 0.5 mm is 6.7 wt% (weight ratio of carbon fiber of each length: 1/1). 1.5 / 2.0).

The surface condition of this molded product is good, the surface gloss is 75%, the flexural strength is 17 kg / mm ² , and the flexural modulus is
It was 1100 kg / mm ² . In addition, as a result of electrical measurement of this molded product, the specific volume resistance was 0.5 Ω · cm.
Met.

Table 1 shows the results.

COMPARATIVE EXAMPLE 1 The carbon-containing resin pellets obtained in Example 1 were subjected to molding at a resin temperature of 270 ° C., a back pressure, a screw rotation speed, an injection speed, etc., which were extremely low. The molding was carried out under the condition that hardly applied. As for the carbon fibers in the obtained molded article, 8.2 wt% of carbon fibers having a length exceeding 1.5 mm. The surface condition was extremely bad (x) due to fluffing and irregularities due to carbon fiber aggregation, and the appearance was unusable. Further, as a result of electrical measurement of this molded product, the specific volume resistance was 5 Ω · cm.

Examples 2 to 6, Comparative Examples 2 to 4 In Examples 2, 4, 5 and Comparative Example 2, molded articles were obtained in the same manner as in Example 1 except that the carbon fiber concentration in the resin pellets was changed. Was. In Examples 3 and 6, and Comparative Example 3, molded articles were obtained in the same manner as in Example 1, except that ABS was used as the thermoplastic resin and the carbon fiber concentration in the resin pellets was changed. In Comparative Example 4, C-CF and ABS which was a thermoplastic resin were mixed by a tumbler, and the mixture was extruded by twin-screw to prepare a resin pellet.

Table 1 shows the results.

[0071]

[Table 1]

Example 7 ABS having a carbon fiber concentration of 15 wt% obtained in Example 1
Of carbon fiber-containing resin pellets and pure ABS pellets containing no carbon fiber were mixed at a ratio of 1: 2. A molded article was obtained in the same manner as in Example 1 using this blended article. The dispersibility of the carbon fibers in the obtained molded article was extremely good, and carbon fibers having a length exceeding 1.5 mm
wt%, carbon fiber having a length of 0.5 to 1.5 mm is 1.7.
wt%, a carbon fiber having a length of less than 0.5 mm is 2.1 w
t% (weight ratio of carbon fiber of each length: 1 / 1.4 / 1.8)
Met.

The surface condition of this molded product is good, the surface gloss is 90%, the bending strength is 11 kg / mm ² , and the bending elastic modulus is 1
It was 100 kg / mm ² . In addition, as a result of electrical measurement of this molded product, the specific volume resistance was 9 × 10 ² Ω · c
m.

Examples 8 to 23 Using carbon fiber roving (CF-R), Tables 2 and 3
Carbon fiber-containing resin pellets were prepared using the thermoplastic resin and the surface treatment agent shown in (1), and molding was performed using the resin pellets as a raw material. In addition, the resin temperature at the time of molding set the conditions suitable for each resin.

The results are shown in Tables 2 and 3.

[0076]

[Table 2]

[0077]

[Table 3]

Comparative Example 5 25% by weight of 6 mm long chopped fiber (C-CF) surface-treated with an epoxy-based sizing agent was used for high-density PE.
75 wt. Pellets (high density PE product with density 0.95, MFR 7 g / 10 min PE and density 0.95, MFR 1.3 g / 10 min PE blend extruded density 0.95, MFR 3.0 g / 10 min) %, And a molded article was obtained in the same manner as in Example 1. The carbon fiber having a length exceeding 1.5 mm in the molded product is 3.0 wt%, 0.5 to 1.5 mm
Was 12.8 wt%, and carbon fibers having a length of less than 0.5 mm were 9.2 wt% (weight ratio of carbon fiber of each length: 1 / 4.3 / 3.1). . The surface condition of this molded product was poor due to fluffing and unevenness due to carbon fiber aggregation, and the appearance was poor. As a result of electrical measurement of the molded product, the volume resistivity was 10 Ω · cm. Example 12 of the present invention, total carbon fiber content of 15 w
Compared to the t% molded product having a volume resistivity value of 0.3 Ω · cm, in the method of this comparative example, the carbon fiber content was low despite the total content of 25 wt%. The reason for the poor surface appearance and the poor electrical properties is that
It is presumed to be due to the difference in the length distribution of the carbon fibers.

Comparative Example 6 5.5 m long surface-treated with an epoxy sizing agent
m chopped fiber (C-CF) 0.5wt% ABS
And mixed with 99.5 wt. Of pellets, and dispersed by a twin-screw extruder to obtain pellets. A molded product was obtained from the pellet in the same manner as in Example 1. The carbon fiber having a length exceeding 1.5 mm in the molded article is 0 wt%, the carbon fiber having a length of 0.5 to 1.5 mm is 0.3 wt%, and the fiber having a length of less than 0.5 mm is 99. 7 wt%.

The dispersibility and surface condition of the carbon fiber were good, and the surface gloss was 97%. However, the volume resistivity was 10 ¹⁴ Ω · cm or more as compared with Example 5, and the carbon fiber contained carbon fiber. This is equivalent to the level of ABS resin not used.

Example 24 A carbon fiber roving (CF-R) was immersed in an AS emulsion, and the emulsion was squeezed so that the solid content of the emulsion adhered to 20 wt% on a dry basis, and the amount of the emulsion was adjusted and dried. Then, it cut continuously so that length might be set to 5.5 mm. 15 parts by weight of carbon fiber surface-treated with this AS emulsion and pure A without carbon fiber
85 parts by weight of BS pellets were mixed. Using this mixture, molding was performed in the same manner as in Example 1 to obtain a molded product. The dispersibility of the carbon fiber in the molded article is good, and the carbon fiber having a length exceeding 1.5 mm is 3.0 wt% in the molded article.
%, Carbon fiber of 0.5-1.5mm length is 4.9wt
%, Carbon fiber with a length of less than 0.5 mm is 7.1 wt%
(Weight ratio of carbon fiber of each length: 1 / 1.6 / 2.4).

The surface condition of this molded product was good, the surface gloss was 75%, the bending strength was 16 kg / mm ² , and the bending elastic modulus was 1
It was 050 kg / mm ² . Further, as a result of electrical measurement of this molded product, the volume resistivity was 0.3 Ω · cm.

Example 25 Carbon fiber roving (CF
-R) was immersed in an AS emulsion, the emulsion was squeezed so that the solid content of the emulsion adhered to 20 wt% on a dry basis, and the amount of adhesion was adjusted and dried. Then, ABS
Is extruded with a single screw extruder, ABS is extrusion-coated so that the carbon fiber concentration in the resin pellets is 15 wt%, and the strand is cut with a cutter so as to have a length of 5.5 mm, and contains carbon fibers. Resin pellets were prepared.

Using these pellets, a molded article was obtained in the same manner as in Example 1. The dispersibility of the carbon fibers in the molded article is extremely good. In the molded article, 3.5 wt% of carbon fibers having a length of more than 1.5 mm, and 5.5 wt% of carbon fibers having a length of 0.5 to 1.5 mm. 6.3 wt% of carbon fiber having a length of less than 2 wt% and less than 0.5 mm (weight ratio of carbon fiber of each length: 1/1)
1.5 / 1.8).

The surface condition of this molded product is good, the surface gloss is 76%, the bending strength is 16 kg / mm ² , and the bending elastic modulus is 1
It was 050 kg / mm ² . Further, as a result of electrical measurement of this molded product, the volume resistivity value was 0.08Ω · c
m.

Example 26 A carbon fiber roving (CF-R) was extruded and coated with PP while pulling the carbon fiber roving under tension, that is, pulling the carbon fiber roving under tension.
After passing through the step of loosening P to be coated, it was cut into pellets. In this case, the amount of PP attached (the amount of coating) is
30 wt%. Carbon fiber 5 coated with this PP
0 parts by weight and 50 parts by weight of pure PP pellets containing no carbon fiber were mixed. Using this mixture, a molded article was obtained in the same manner as in Example 1. The dispersibility of the carbon fibers in the molded article was extremely good,
3.3% by weight of carbon fiber having a length exceeding
1.5mm length carbon fiber is 5.0wt%, 0.5m
The length of the carbon fiber having a length of less than m was 6.8 wt% (weight ratio of carbon fiber of each length: 1 / 1.5 / 2.1).

The surface condition of this molded product was good, and the surface gloss was 75%. Further, as a result of electrical measurement of this molded product, the volume resistivity was 0.3 Ω · cm.

Example 27 Table 4 shows the results of measuring the electromagnetic wave shielding effect of the molded products obtained in some of the above Examples. Generally, in order to realize the effect of the electromagnetic wave shielding, the electromagnetic wave shielding effect is preferably 20 dB or more, and for that purpose, the volume resistivity value is 10 ⁻⁴ to 1 ^−4.
A molded product having a resistance of 0 ³ Ω · cm can be used.

[0089]

[Table 4]

Example 28 Table 5 shows the results of evaluating the suitability of the molded articles obtained in some of the above Examples and Comparative Examples as sliding parts. The wear amount when used as a sliding part is preferably 32 μm or less, and in order to impart antistatic properties, the volume specific resistance value is 10 ⁹ or less, preferably 10 ⁰ to 10 ⁹ Ω · cm.
It is. Even when a molded product having such a volume specific resistance value was left indoors, adhesion of dust was small.

[0091]

[Table 5]

Example 29 Table 6 shows the results of evaluating the suitability of the molded articles obtained in some of the above Examples as IC trays. Generally, an appropriate standard for an IC tray is often expressed by a surface resistance value, and the surface resistance value was measured together with the volume specific resistance value. Those having a surface resistance value of 10 ² to 10 ¹⁰ Ω showed little adhesion of dust even when left indoors.

[0093]

[Table 6]

[0094]

The thermoplastic resin molded article containing carbon fiber of the present invention has excellent mechanical properties, electrical properties and especially excellent surface condition. Examples thereof include an electromagnetic wave shielding molded article, a resin resistor, and an antistatic material. It can be used for a resin resistor, an IC tray and the like having a property.

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Claims (15)

[Claims] 1. A molded article of a thermoplastic resin containing carbon fibers, wherein the thermoplastic resin as a matrix contains 70 to 99.5.
wt%, the total content of carbon fibers contained in the molded article is 0.5 to 30 wt%, and (a) 0.1 to 4.7 wt% of carbon fibers having a length exceeding 1.5 mm ( (B) based on the total amount of thermoplastic resin and carbon fiber.
0.2 to 10 mm of carbon fiber having a length of 0.5 to 1.5 mm.
A carbon fiber-containing thermoplastic resin molded product characterized in that carbon fiber having a length of 7 wt% and (c) a length of less than 0.5 mm is 0.2 to 14.6 wt%. 2. A thermoplastic resin molded article containing carbon fibers, wherein (a) a carbon fiber having a length exceeding 1.5 mm, (b) a carbon fiber having a length of 0.5 to 1.5 mm, and (c)
The carbon fiber content according to claim 1, wherein the ratio with the carbon fiber having a length of less than 0.5 mm is 1 / 0.5 to 2.5 / 0.5 to 3.0 by weight. Thermoplastic resin molded product. 3. The carbon fiber according to claim 1, wherein the carbon fiber is coated with a resin compatible with the thermoplastic resin.
3. The molded article of a thermoplastic resin containing carbon fibers according to any one of claims 1 to 2. 4. A carbon fiber roving formed by extrusion-coating a thermoplastic resin with a thermoplastic resin, and further using a resin pellet containing carbon fibers obtained by cutting. The carbon fiber-containing thermoplastic resin molded product according to any one of the above. 5. A carbon fiber roving formed by extrusion-coating a thermoplastic resin with a thermoplastic resin, and further molded by using a blend of a resin pellet containing a carbon fiber obtained by cutting and a thermoplastic resin pellet. The carbon fiber-containing thermoplastic resin molded product according to any one of claims 1 to 3, characterized in that: 6. The carbon fiber obtained by cutting a carbon fiber roving and molded using a blend of a thermoplastic resin pellet and a carbon fiber obtained by cutting the carbon fiber roving. Carbon fiber-containing thermoplastic resin molded products. 7. The carbon fiber-containing thermoplastic resin molded article according to claim 4, wherein the carbon fiber roving is coated with a resin compatible with the thermoplastic resin. 8. The heat containing carbon fiber according to claim 7, wherein the coating of the resin compatible with the thermoplastic resin on the carbon fiber is performed by attaching an emulsion to the carbon fiber. Plastic resin molded product. 9. The method according to claim 7, wherein the coating of the resin compatible with the thermoplastic resin on the carbon fiber is performed by applying the thermoplastic resin to the carbon fiber by melt extrusion coating. 8. The molded article of the thermoplastic resin containing carbon fiber according to any one of 8). 10. The carbon fiber-containing thermoplastic resin molded article according to claim 1, wherein the carbon fiber has a conductive film formed on a surface thereof. 11. The carbon fiber-containing thermoplastic resin molded article according to claim 10, wherein the conductive film is formed by plating. 12. The electromagnetic wave shield according to claim 1, wherein the carbon fiber-containing thermoplastic resin molded product has a volume resistivity value of 10 ⁻⁴ to 10 ³ Ω · cm. Molding. 13. The molded article of the carbon fiber-containing thermoplastic resin according to any one of claims 1 to 11, wherein the volume resistivity is 10 ² to 10 ¹³ Ω · cm. . 14. A carbon fiber-containing thermoplastic resin molded product according to any one of claims 1 to 11, antistatic properties, characterized in that volume resistivity is 10 ⁰ ~10 ⁹ Ω · cm Sliding parts having 15. The carbon fiber-containing thermoplastic resin molded product according to claim 1, wherein the surface resistance value is 1%.
An IC tray characterized by having an impedance of 0 ² to 10 ¹⁰ Ω.