JP2006028332A - Conductive resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition which gives a molded article excellent in conductivity, showing small variation in conductivity depending on parts of the molded article or molding conditions and hardly undergoing warpage even after left under high-temperature and high-humidity conditions, and a molded article thereof. <P>SOLUTION: The conductive thermoplastic resin composition comprises 100 pts. wt. of a resin composition obtained by kneading 80-93 wt% of a rubber-reinforced thermoplastic resin (C), comprised of a graft copolymer (A) obtained by graft-copolymerizing a rubbery polymer (a) with one or more monomers (b1) copolymerizable therewith, a copolymer (B1) obtained by copolymerizing one or more monomers (b2) and a copolymer (B2) obtained by copolymerizing an acid anhydride monomer with one or more monomers (b3), with 7-20 wt% of a polyamide elastomer (D), and 5-15 pts. wt. of a carbon fiber (E). <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention is a thermoplastic resin composition that is excellent in electrical conductivity, has little variation in electrical conductivity due to the molded product part or molding conditions, and can obtain a molded product with less warping even after being left under high temperature and high humidity conditions, And a molded product thereof.

In general, thermoplastic resin compositions are widely used in the field of electric and electronic parts because they are excellent in electrical insulation. However, static electricity is likely to be stored in the molded product due to friction or the like, and contamination due to dust adhesion may be a problem. Further, in the production site of electronic devices such as semiconductors or in the transportation site, damage to components or deterioration of function due to discharge of stored static electricity may be a problem. For this reason, it has been required to impart conductivity to the thermoplastic resin composition to prevent electrification and to remove static electricity at an early stage.
Generally, as a method for imparting electrical conductivity to a thermoplastic resin, a method of blending a polymer type antistatic agent such as a polyamide elastomer including polyether ester amide is known. (For example, see Patent Document 1) However, the conductive performance imparted by this method is not sufficient depending on the application, and when a large amount of polyamide elastomer is blended in order to obtain high conductivity, the gold performance is reduced after molding. When taking out the molded product from the mold, deformation called warping is likely to occur, and in order to eliminate this, there were cases where the mold design was restricted, or the cooling cycle was extended to extend the molding cycle. .

On the other hand, a method of blending conductive fibers such as carbon fiber and metal fiber is also widely used, but this method has an advantage of excellent balance between conductivity and mechanical strength, but the obtained molded article There was a problem that the variation in conductivity depending on the measurement site was very large.
In order to solve this problem, a method of using a combination of a conductive fiber and a polymer type antistatic agent such as polyether ester amide has been proposed. (For example, see Patent Documents 2 to 6) However, in these methods, there is a case where the conductivity value varies greatly depending on the molding conditions or the measurement site of conductivity, or there is a problem in the dimensional stability of the molded product. It was. In terms of dimensional stability, there is a problem that warp is likely to occur particularly when a large molded product is obtained, and the mold design and molding cycle are restricted in order to solve this problem. Further, even if the warpage is within an allowable range immediately after molding, if the molded product is left under high temperature and high humidity conditions, warpage may occur.
JP-A-11-148072 JP 2002-234984 A JP 2002-317098 A JP 2003-3036 A JP 2003-238774 A JP 2003-313428 A

  As described above, several methods for controlling conductivity by combining a polyamide elastomer and conductive fibers have already been studied. However, it has been difficult to obtain a material that is excellent in conductivity, has little variation due to differences in molding conditions and measurement sites, and exhibits low warpage.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have used conductive fibers and polyamide elastomer in combination at a specific ratio, and specific amounts of specific functional groups as a compatibilizer for thermoplastic resins. It has been found that the above-mentioned problems can be solved by using the copolymer contained therein, and the present invention has been achieved.
That is, the present invention
[1] Graft copolymer (A) obtained by graft copolymerization of rubbery polymer (a) and one or more monomers (b1) copolymerizable therewith, and one or two types A copolymer (B1) obtained by copolymerizing the above monomer (b2), and a copolymer obtained by copolymerizing an acid anhydride monomer and one or more monomers (b3). Carbon fiber with respect to 100 parts by weight of the resin composition obtained by kneading 80 to 93% by weight of rubber-reinforced thermoplastic resin (C) comprising polymer (B2) and 7 to 20% by weight of polyamide elastomer (D) (E) a conductive thermoplastic resin composition comprising 5 to 15 parts by weight,
[2] The conductive thermoplastic resin composition as described in 1 above, wherein 0.01 to 1.0 part by weight of an acid anhydride component is contained in 100 parts by weight of the rubber-reinforced thermoplastic resin (C),
[3] A molded product formed by molding the thermoplastic resin composition according to 1 or 2 above,
It is.

  According to the present invention, it is possible to obtain a molded product that is excellent in conductivity, has a small range of variation in conductivity depending on molding conditions or measurement sites, and is excellent in low warpage.

  Examples of the rubbery polymer (a) used for the graft copolymer (A) in the present invention include polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-acrylic copolymer, and styrene-butadiene-. Conjugated diene rubbers such as styrene block copolymers, polyisoprenes, styrene-isoprene copolymers, and hydrogenated products thereof, acrylic rubbers such as ethyl acrylate and butyl acrylate, ethylene-α-olefin-polyene copolymers Examples thereof include a polymer, an ethylene-α-olefin copolymer, silicone rubber, and silicone-acrylic rubber, and these can be used alone or in combination of two or more. Particularly preferred among these are polybutadiene, polyisoprene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-acrylic copolymer, acrylic rubber, ethylene-α-olefin-polyene copolymer, ethylene. -Α-olefin copolymer, silicone rubber, silicone-acrylic rubber.

  As the monomer (b1), styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, ethylstyrene, pt-butylstyrene, vinylnaphthalene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromo Aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, alkyl acrylates having an alkyl group having 1 to 4 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and the like Substituted alkyl methacrylates, acrylic acids such as acrylic acid and methacrylic acid, N-substituted maleimide monomers such as N-phenylmaleimide and N-methylmaleimide, maleic anhydride, itaconic anhydride, citraconic anhydride, etc. Acid anhydride monomer, etc. It is. Among these, styrene, α-methylstyrene, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate are particularly preferred when considering the balance of mechanical properties, thermal properties, moldability, etc. N-phenylmaleimide.

In the present invention, the weight average particle diameter of the rubbery polymer (a) in the graft copolymer (A) is 0.1 to 0.1 from the balance of mechanical strength such as impact resistance, molding processability, and appearance of the molded product. The thickness is 1.2 μm, preferably 0.15 to 0.8 μm, more preferably 0.15 to 0.6 μm, and still more preferably 0.2 to 0.4 μm.
Moreover, the graft ratio in the graft copolymer (A) is 10 to 150% by weight, preferably 20 to 110% by weight, and more preferably 25 to 60% by weight. By setting the graft ratio within this range, a composition having excellent impact resistance and good moldability can be obtained. The graft ratio is defined as the weight ratio of the monomer graft copolymerized with the rubber polymer to the rubber polymer. In the measurement method, a polymer produced by a polymerization reaction is dissolved in acetone and separated into an acetone-soluble component and an insoluble component by a centrifuge. At this time, the component dissolved in acetone is a component that has not undergone graft reaction (non-graft component) in the copolymer that has undergone polymerization reaction, and the acetone insoluble component is a component that has undergone graft reaction to the rubber polymer and rubber polymer. (Graft component). Since the value obtained by subtracting the weight of the rubbery polymer from the weight of the acetone-insoluble component is defined as the weight of the graft component, the graft ratio can be determined from these values.

As a monomer (b2) in a copolymer (B1), the thing similar to the said monomer (b1) except an acid anhydride monomer can be used.
Examples of the acid anhydride monomer in the copolymer (B2) include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like. Among these, maleic anhydride and itaconic anhydride are preferable.
As the monomer (b3) in the copolymer (B2), those similar to the monomer (b1) except for the acid anhydride monomer can be used.
Unpreferable monomers (b1), (b2), and (b3) are monomers having a glycidyl group, hydroxyl group, or carboxyl group having a high reactivity with an acid anhydride as a functional group, such as glycidyl methacrylate. 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and the like, which are competitive reactions of the reaction between the acid anhydride monomer and the terminal amino group, terminal carboxyl group, or terminal hydroxyl group in the polyamide elastomer (D). In view of this, the compatibility performance may be reduced, so that it is preferably not substantially contained.

The graft copolymer (A), copolymer (B1), and copolymer (B2) can be produced by known methods such as emulsion polymerization, suspension polymerization, and solution polymerization.
In the rubber-reinforced thermoplastic resin (C) comprising the graft copolymer (A), the copolymer (B1), and the copolymer (B2), the content of the rubbery polymer is preferably 5 to 60% by weight, preferably It is 8 to 50% by weight, more preferably 10 to 40% by weight. When this is 5% by weight or more, the impact strength is excellent, and when it is 60% by weight or less, the moldability is excellent.
The reduced specific viscosity of the component not grafted to the rubbery polymer in the rubber-reinforced thermoplastic resin (C) is 0.1 to 1.0, preferably 0.2 to 0.8, more preferably 0.25 to 0.25. 0.75. When it is 0.1 or more, mechanical strength such as impact resistance is excellent, and when it is 1.5 or less, moldability is excellent. The reduced specific viscosity of the ungrafted component is obtained by first dissolving the rubber-reinforced thermoplastic resin in acetone, and separating it into an acetone-soluble component and an acetone-insoluble component using a centrifuge. A solution obtained by dissolving 0.50 g of acetone-soluble matter in 100 ml of 2-butanone is obtained by measuring the outflow time in a Cannon-Fenske type capillary at 30 ° C.

The content of the acid anhydride monomer in the rubber-reinforced thermoplastic resin (C) is 0.01 to 1.0% by weight, preferably 0.1 to 0.00%, based on the rubber-reinforced thermoplastic resin (C). It is 8% by weight, more preferably 0.2 to 0.7% by weight, still more preferably 0.3 to 0.7% by weight. When the content of the acid anhydride monomer is within this range, a molded product having excellent conductivity and less variation in conductivity depending on molding conditions or measurement sites can be obtained.
The polyamide elastomer (D) in the present invention is a copolymer comprising at least one selected from a polyamide component, a polyoxyalkylene glycol component, and / or an ethylene oxide adduct of bisphenols.

  There is no restriction | limiting in particular as a polyamide component, For example, ethylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,3,4 or 2,4,4-trimethylhexamethylenediamine, 1,3 or 1 , 4-bis (aminomethyl) cyclohexane, bis (p-aminocyclohexyl) methane, m-xylylenediamine, p-xylylenediamine, and other aliphatic, alicyclic, or aromatic diamines, and adipic acid and suberic acid Polyamides obtained by ring-opening polymerization of lactams such as polyamides derived from aliphatic, alicyclic and aromatic dicarboxylic acids such as sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid and isophthalic acid, caprolactam and lauryllactam, ω -Aminocap Phosphate, .omega.-aminoenanthic acid, 11-aminoundecanoic acid, polyamides derived from an amino acid such as 12-aminododecanoic acid, these copolyamide, more like a mixture of these polyamides. Among these, preferable polyamide components are nylon 6 and nylon 66.

The molecular weight of the polyamide component is not particularly limited, but those having a number average molecular weight of 500 to 10,000, more preferably 500 to 5,000 are preferably used for achieving the object of the present invention.
Examples of the polyoxyalkylene glycol include polyoxyethylene glycol, polyoxy (1,2- or 1,3-) propylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, polyoxyethylene oxide and polyoxypropylene oxide. Among these, polyoxyethylene glycol is preferred.

Examples of ethylene oxide adducts of bisphenols include bisphenol A (2,2-bis (4-hydroxyphenyl) propane), bisphenol F (bis (4hydroxyphenyl) methane), and bisphenol S (bis (4-hydroxyphenyl)). Sulfone) and ethylene oxide adducts of bisphenols such as 2,2-bis (4-hydroxyphenyl) butane. Among these, bisphenol A and ethylene oxide adducts of bisphenol S are preferred.
The molecular weight of the polyoxyalkylene glycol and the ethylene oxide adduct of bisphenols is not particularly limited, but the number average molecular weight is 200 to 20,000, preferably 300 to 10,000, more preferably 300 to 4,000. It is preferably used for achieving the purpose.

The ratio of the polyamide component in the polyamide elastomer (D) and the polyoxyalkylene glycol component and / or the ethylene oxide adduct of bisphenols is 90 to 10/10 to 90% by weight, preferably 80 to 20/20 to 80% by weight. %. When the polyoxyalkylene glycol component is 90% by weight or less, the appearance, rigidity, and impact resistance of the obtained molded product are good, and when it is 10% by weight or more, the conductivity is excellent.
The molecular weight of the polyamide elastomer (D) is not particularly limited, but the reduced specific viscosity (in m-cresol, 0.5 g / 100 ml, 25 ° C.) is 1.0 to 3.0, preferably 1.5 to 2.5. It is.

  The polyamide elastomer (D) can be produced using a known polymerization method or a known catalyst, and examples thereof include a heat melt polymerization method. Specifically, for example, after polymerizing a polyamide component, a dicarboxylic acid compound is added, both ends of the polyamide component are carboxylated, and polyoxyalkylene glycol and / or an ethylene oxide adduct of bisphenols is added and polymerized. Examples include a method for obtaining an elastomer, a method for obtaining a polyamide elastomer by batch polymerization of a predetermined amount of a polyamide-forming component and an excess of a dicarboxylic acid compound, polyoxyalkylene glycol, and / or an ethylene oxide adduct of bisphenols.

In order to further improve the conductive performance of the thermoplastic resin composition of the present invention, an alkali metal and / or alkaline earth metal salt can be added during the production of the polyamide elastomer (D). As for the addition method, the elastomer can be added all at once or before the polymerization, during the polymerization, or before the separation / recovery of the elastomer after the polymerization.
Examples of the metal salt include organic acid salts such as lithium acetate, sodium acetate, potassium acetate, lithium oxalate, sodium oxalate, potassium oxalate, lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, fluoride. Calcium, lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium bromide, sodium bromide, potassium bromide, magnesium bromide, calcium bromide, lithium iodide, sodium iodide, potassium iodide, iodine Examples thereof include halides such as magnesium iodide and calcium iodide.

  In addition, perchlorates such as lithium perchlorate, sodium perchlorate, potassium perchlorate, magnesium perchlorate, calcium perchlorate, lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, fluorosulfone Examples thereof include fluorosulfonates such as magnesium acid and calcium fluorosulfonate, and methanesulfonates such as lithium methanesulfonate, sodium methanesulfonate, potassium methanesulfonate, magnesium methanesulfonate, and calcium methanesulfonate.

  Also, lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, magnesium trifluoromethanesulfonate, calcium trifluoromethanesulfonate, lithium pentafluoroethanesulfonate, sodium pentafluoroethanesulfonate, pentafluoroethanesulfone Potassium acid, Magnesium pentafluoroethanesulfonate, Calcium pentafluoroethanesulfonate, Lithium nonafluorobutanesulfonate, Sodium nonafluorobutanesulfonate, Potassium nonafluorobutanesulfonate, Magnesium nonafluorobutanesulfonate, Nonafluorobutanesulfonic acid Calcium, lithium undecafluoropentanesulfonate, undecaful Sodium lopentanesulfonate, potassium undecafluoropentanesulfonate, magnesium undecafluoropentanesulfonate, calcium undecafluoropentanesulfonate, lithium tridecafluorohexanesulfonate, sodium tridecafluorohexanesulfonate, tridecafluorohexane Fluoroalkanesulfonates such as potassium sulfonate, magnesium tridecafluorohexanesulfonate, calcium tridecafluorohexanesulfonate, sulfates such as potassium sulfate and sodium sulfate, phosphates such as potassium phosphate and sodium phosphate, Examples include thiocyanate such as potassium thiocyanate and sodium thiocyanate.

Of these, preferred are alkali metal salts, more preferred are alkali metal halides (especially lithium chloride, sodium chloride, potassium chloride), acetates (especially potassium acetate, sodium acetate), oxalates (sodium oxalate). , Potassium oxalate), sulfate (potassium sulfate, sodium sulfate), perchlorate (especially lithium perchlorate, sodium perchlorate, potassium perchlorate), fluoroalkanesulfonate (especially lithium trifluoromethanesulfonate) , Sodium trifluoromethanesulfonate, potassium trifluoromethanesulfonate).
The content of the metal compound is 3% by weight or less, preferably 2% by weight or less of the polyamide elastomer (D). The appearance of the molded product is good at 3% by weight or less.

The content of the polyamide elastomer (D) in the resin composition obtained by kneading the rubber-reinforced thermoplastic resin (C) and the polyamide elastomer (D) of the present invention is 7 to 20% by weight, preferably 10 to 17%. % By weight, more preferably 11-16% by weight, particularly preferably 12-16% by weight. If this is in this range, it is possible to obtain a molded product that exhibits excellent conductivity, has a small range of variation in conductivity depending on molding conditions or measurement sites, and exhibits low warpage.
The carbon fiber (E) in the present invention is not particularly limited, and a known carbon fiber can be used, and examples thereof include PAN-based, pitch-based, cellulose-based, and metal-coated carbon fibers. . Among these, PAN-based carbon fibers are preferable from the balance between conductivity and mechanical strength.

The diameter of the carbon fiber (E) is 3 to 20 μm, preferably 5 to 15 μm, more preferably 5 to 10 μm in consideration of the balance between conductivity and ease of handling.
The carbon fiber (E) is treated with a surface treatment agent such as a coupling agent or a sizing agent for the purpose of improving the mechanical properties of the resin composition containing the carbon fiber or improving the conductivity. May be. Examples of such surface treatment agents include silane-based and titanate-based coupling agents, epoxy-based, urethane-based, ether-based, ester-based, amide-based, acrylic-based, and polyvinyl alcohol-based sizing agents. It can be used alone or in combination of two or more.

In the present invention, the compounding amount of the carbon fiber (E) is 5 to 15 parts by weight with respect to 100 parts by weight of the resin composition obtained by kneading the rubber-reinforced thermoplastic resin (C) and the polyamide elastomer (D). The amount is preferably 5 to 12 parts by weight, more preferably 5 to 10 parts by weight. When the amount is 5 parts by weight or more, the obtained molded product has excellent conductivity and low warpage. When the amount is 15 parts by weight or less, the moldability is good and the carbon fibers are uniformly dispersed in the molded product. Since it becomes easy, there will be few dispersion | variation in electroconductivity by a molded article site | part.
Examples of a method for producing a conductive thermoplastic resin composition pellet include a method in which resin components other than carbon fibers are supplied from a hopper of a twin screw extruder, and carbon fibers are supplied from a side feeder and melt kneaded, continuous carbon fibers There is a method of cooling and cutting after passing through a crosshead die of an extruder filled with a resin component. Among these, the former method is preferable from the viewpoint of the appearance of the molded product and the conductivity.

In the method of melt-kneading by supplying carbon fiber from the side feeder, it is necessary to sufficiently knead the rubber-reinforced thermoplastic resin and the polyamide elastomer using a compatibilizing agent, while carbon is used for the purpose of expressing high conductivity. It is necessary to maintain the fiber length. Therefore, the position of the side feeder for supplying the carbon fibers is preferably within ½ from the head end of the extruder, and the kneading by the extruder screw after the side feeder is preferably weak.
Examples of the molding method in the present invention include known methods such as injection molding, injection compression molding, blow molding, extrusion molding, vacuum molding, and compression molding. Among these, injection molding with excellent productivity is preferable.

  The number average fiber length of the carbon fibers (E) in the molded product is 0.05 to 0.70 mm, preferably 0.10 to 0.65 mm, more preferably 0.15 to 0.65 mm, still more preferably 0.00. 15 to 0.60 mm. When the thickness is 0.05 mm or more, the conductivity and the low warpage of the molded product are good, and when the thickness is 0.70 mm or less, the variation in conductivity due to the molded product portion is small. As a method for controlling the carbon fiber length in the molded product, in the kneading step, kneading temperature, carbon fiber supply position to the extruder, screw shape, L / D, etc. can be mentioned. Screw shape in machine cylinder, L / D, nozzle shape, nozzle diameter, in mold, sprue, runner, gate shape and diameter, in molding conditions, molding temperature, mold temperature, back pressure, to mold The filling speed of etc. is mentioned.

  The carbon fiber length in the molded product can be determined by the following method. The test piece cut out from the molded product is subjected to heat treatment at 475 ° C. in an electric furnace, the thermoplastic resin component is burned, and the carbon fiber is taken out. Chloroform is added thereto to sufficiently disperse the carbon fiber in the liquid, and then a few drops are dropped on the slide glass with a dropper, and the chloroform is dried. Thereafter, a photograph is taken with an optical microscope at a magnification of 10 to 15 times, and the number average fiber length is obtained from 500 or more carbon fibers.

  In the present invention, known additives depending on the purpose, for example, conductive fillers other than carbon fiber (for example, carbon black such as acetylene black and ketjen black, carbon-based filler such as nanotube carbon and graphite, copper, iron Nickel, gold, silver, titanium, aluminum, and metal fillers such as alloys based on the aforementioned metals such as stainless steel and brass, metal oxides such as zinc oxide, titanium oxide, aluminum oxide, tin oxide, and indium oxide Physical fillers, composite fillers obtained by subjecting the glass surface to the above metal plating treatment, etc.), plasticizers, lubricants (for example, higher fatty acids and their metal salts, higher fatty acid amides, etc.), thermal stabilizers, antioxidants (For example, phenol-based, phosphite-based, thiodipropionic acid ester type thioether, etc.), weathering agents (for example, , Benzotriazole, benzophenone, salicylate, cyanoacrylate, oxalic acid derivative, hindered amine, etc.), colorant, pigment, dye, flame retardant (eg brominated compound, phosphate ester, condensed phosphate ester, red) Phosphorus), flame retardant aids (eg, antimony trioxide, antimony pentoxide, etc.), antistatic agents other than polyamide elastomers (eg, quaternary ammonium salts, pyridine derivatives, aliphatic sulfonates, aromatic sulfonic acids) Salts, sulfate esters, polyhydric alcohol partial esters, alkyldiethanolamines, alkuldiethanolamides, polyalkylene glycol derivatives, betaines, imidazoline derivatives, etc.), antibacterial agents, antifungal agents, slidability improvers (for example, low molecular weight) Hydrocarbons such as polyethylene, higher alcohols, polyvalent Lucol, polyglycol, polyglycerol, higher fatty acid, higher fatty acid metal salt, fatty acid amide, ester of fatty acid and aliphatic alcohol, full of fatty acid and polyhydric alcohol, or partial ester, full of fatty acid and polyglycol, or (Partial ester, silicone type, fluororesin type, etc.) can be blended at an arbitrary ratio according to the purpose.

Hereinafter, the present invention will be specifically described with reference to examples. Moreover, the evaluation in an Example was performed in accordance with the following method.
(1) Notched Charpy impact strength Test pieces were prepared and evaluated according to ISO179.
(2) Flexural modulus Test pieces were prepared and evaluated according to ISO178.
(3) Evaluation of variation in conductivity depending on measurement site After drying conductive thermoplastic resin composition pellets at 80 ° C. for 3 hours, using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS130FB), the following Injection molding was performed under molding conditions to obtain 10 flat plates. Seven of these were adjusted for 48 hours under conditions of 23 ° C. and 50% humidity, then a tester (manufactured by Simco Japan Co., Ltd., Truestat surface resistance meter ST-3 type work surface tester, measuring voltage 15 V or less, (Measurement area: 50 mm (electrode length) × 50 mm (between electrodes)), the tester electrode is placed in a direction perpendicular to the resin flow direction during molding, and as shown in FIG. The conductivity of each part was evaluated. Among these, the average value of five sheets excluding the maximum value and the minimum value was obtained.
When the conductivity is less than 10 ⁴ Ω which is the measurement limit of the tester, a low resistivity meter (manufactured by Mitsubishi Chemical Corporation, Lorester EP MCP-T360, four-terminal four-probe probe: ASP probe) (Use of MCP-TP03P) was used to evaluate the same position.
Further, the variation in conductivity is a ratio of resistance values according to each condition (for example, (resistance value of gate part when injection molding at 240 ° C.) / (Resistance value of gate part when injection molding at 260 ° C.)). Expressed in

[Molding condition]
Screw diameter: 45mm
Cylinder temperature: 240 ° C
Mold temperature: 40 ℃
Back pressure: 9.8 MPa
Injection speed: 30%
Screw rotation speed: 100rpm
Injection time: 15 seconds Cooling time: 20 seconds Gate shape: Film gate (see Fig. 1)
Measurement position: See Fig. 2

(4) Evaluation of conductivity variation due to molding temperature Molding and evaluation were performed in the same manner as in (3) except that the cylinder temperature during molding was 260 ° C. In addition, only the gate part was measured at this time.
(5) Evaluation of warpage of molded article Three of the flat plates obtained in (3) were adjusted in a constant temperature and humidity chamber at 40 ° C. and 90% humidity for 120 hours, then taken out to room temperature and left for 1 hour. The flat plate was placed on a horizontal portion, the gate side was fixed, and the floating of the gate end portion was measured, and the average value of each flat plate was obtained.

[Reference Example 1] Production of Graft Copolymer (A) Polybutadiene rubber latex (volume average particle diameter measured by Microtrac Particle Size Analyzer “nanotrac 150” manufactured by Nikkiso Co., Ltd.) = 0.25 μm, solid content = 49 weight %) After adding 41 parts by weight of deionized water to 100 parts by weight and replacing the gas phase with nitrogen, 25 parts by weight of deionized water was added with 0.15 parts by weight of sodium formaldehyde sulfoxylate and 0.001 ferrous sulfate. An aqueous solution in which 0.04 part by weight of ethylenediaminetetraacetic acid disodium salt was dissolved was added, and the temperature was raised to 55 ° C. Subsequently, while the temperature was raised to 70 ° C. over 1.5 hours, a single unit consisting of 15 parts by weight of acrylonitrile, 35 parts by weight of styrene, 0.6 parts by weight of terleaded decyl mercaptan, and 0.09 parts by weight of cumene hydroperoxide. An aqueous solution prepared by dissolving 0.13 parts by weight of sodium formaldehyde sulfoxylate in 15 parts by weight of deionized water and a mixture of the monomers was added over 4 hours. One hour after completion of the addition, the polymerization reaction was completed while controlling the reaction vessel at 70 ° C.
After adding a silicone resin defoamer and a phenolic antioxidant emulsion to the ABS latex thus obtained, solidify by adding an aqueous aluminum sulfate solution, and after sufficient dehydration and washing with water And dried to obtain a graft copolymer (A). At this time, the graft ratio was 50% by weight, and the reduced specific viscosity (0.5 g / 100 ml, measured in 2-butanone solution at 30 ° C.) of the non-grafted component was 0.24.

[Reference Example 2] Production of copolymer (B-1) According to the method described in Example 1 of Japanese Patent No. 19605311, acrylonitrile and styrene were used as a solvent, and secondary butyl alcohol was used as a solvent, and the above mixed solution was used in a polymerization reactor. Was continuously added, and the temperature of the polymerization meter was controlled at 140 to 160 ° C. to carry out the polymerization reaction. Thereafter, unreacted monomers were removed under vacuum to obtain a solid powder of acrylonitrile-styrene copolymer. As a result of composition analysis using a Fourier transform infrared spectrophotometer (hereinafter referred to as FR-IR) (manufactured by JASCO Corporation), the composition of the copolymer was 30% by weight for acrylonitrile and 70% by weight for styrene. there were. The reduced specific viscosity (0.5 g / 100 ml, measured in a 2-butanone solution at 30 ° C.) was 0.55.

[Reference Example 3] Production of copolymer (B-2) A copolymer (B-2) was produced in the same manner as in Reference Example 2 except that the type of monomer was changed. The composition of the copolymer was 25% by weight of acrylonitrile, 65% by weight of styrene, and 10% by weight of maleic anhydride as a result of composition analysis by FT-IR. The reduced specific viscosity (0.5 g / 100 ml, measured in a 2-butanone solution at 30 ° C.) was 0.46.

[Reference Example 4] Production of copolymer (B-3) A copolymer (B-3) was produced in the same manner as in Reference Example 2 except that the type of monomer was changed. The composition of the copolymer was found to be 60% by weight methyl methacrylate, 20% by weight styrene, and 10% by weight maleic anhydride as a result of composition analysis by FT-IR. The reduced specific viscosity (0.5 g / 100 ml, measured in a 2-butanone solution at 30 ° C.) was 0.36.

[Reference Example 5] Production of copolymer (B-4) A copolymer (B-4) was produced in the same manner as in Reference Example 2 except that the type of monomer was changed. As a result of composition analysis by FT-IR, the composition of the copolymer was 63% by weight of styrene, 27% by weight of acrylonitrile, and 10% by weight of 2-hydroxyethyl acrylate. The reduced specific viscosity (0.5 g / 100 ml, measured in a 2-butanone solution at 30 ° C.) was 0.45.

[Reference Example 6] Production of polyamide elastomer (D-1) In a 3 L stainless steel separable flask, 113 parts by weight of ε-caprolactam, 15 parts by weight of adipic acid, 0.3 part by weight of a phenolic antioxidant, and 7 water Part by weight was charged, and after substitution with nitrogen, the mixture was heated and stirred at 220 ° C. under pressure and hermetically sealed for 6 hours to obtain 115 parts by weight of polyamide oligomer having an acid value of 112 having carboxyl groups at both ends. Next, 205 parts by weight of polyoxyethylene glycol having a number average molecular weight of 2,000 and 0.5 parts by weight of zirconyl acetate were added and polymerized for 4 hours under a reduced pressure of 260 ° C. and 2 mmHg or less to obtain a viscous polymer. . This polymer was taken out in a sheet form on a bat and pelletized to obtain polyamide elastomer (D-1) pellets. The reduced specific viscosity (0.5 g / 100 ml, measured in m-cresol at 25 ° C.) of this product was 1.90.

[Reference Example 7] Production of polyamide elastomer (D-2) In a 3 L stainless steel separable flask, 83.5 parts by weight of ε-caprolactam, 16.5 parts by weight of terephthalic acid, 0.3 parts by weight of phenolic antioxidant 7 parts by weight of water and 7 parts by weight of water were added, and the mixture was heated and stirred at 220 ° C. for 6 hours under pressure and hermetic sealing to obtain 96 parts by weight of polyamide oligomer having an acid value of 112 having carboxyl groups at both ends. Next, 192 parts by weight of a bisphenol A ethylene oxide adduct having a number average molecular weight of 1,800 and 0.5 parts by weight of zirconyl acetate were added, and the mixture was polymerized for 4 hours at 260 ° C. under reduced pressure of 2 mmHg or less. Obtained. This polymer was taken out in a sheet form on a bat and pelletized to obtain polyamide elastomer (D-2) pellets. The reduced specific viscosity (0.5 g / 100 ml, measured in m-cresol at 25 ° C.) of this product was 2.00.

[Example 1]
30 parts by weight of the graft copolymer (A) that has been sufficiently dried and from which water has been removed, 50 parts by weight of the copolymer (B-1), 5 parts by weight of the copolymer (B-2), polyamide elastomer (D -1) After mixing 15 parts by weight, it was put into a hopper of a twin screw extruder (Toshiba Machine Co., Ltd., TEM-48BS, L / D = 46). Resin composition of carbon fiber (E) (manufactured by Mitsubishi Rayon Co., Ltd., carbon chopped fiber TR066-CBE, average fiber diameter: 7 μm, average fiber length: 6.0 mm, yarn tensile strength: 450 MPa, yarn tensile elastic modulus: 24 GPa) 8 parts by weight with respect to 100 parts by weight of the product is melt-kneaded at a cylinder temperature of 250 ° C. while supplying from the side feeder from a position 1/3 from the die head to obtain pellets of the conductive thermoplastic resin composition. Evaluation was performed. The evaluation results are shown in Table 1. In addition, the number average carbon fiber length in the flat plate shape | molded at 240 degreeC used for electroconductivity evaluation was 0.31 mm.

[Example 2]
Graft copolymer (A) 30 parts by weight, copolymer (B-1) 50 parts by weight, copolymer (B-2) 4.5 parts by weight, polyamide elastomer (D-1) 15 parts by weight, and dodecyl Pellets were prepared and evaluated in the same manner as in Example 1 except that 0.5 part by weight of sodium benzenesulfonate was mixed. The evaluation results are shown in Table 2.

[Examples 3-7, Comparative Examples 1-8]
According to the mixing ratio of Table 1, pellets were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

Examples 1 to 7 are a combination of a specific compatibilizing agent, a specific range of polyamide elastomer, and carbon fiber, and are excellent in conductivity and low warpage, and are electrically conductive depending on the part of the molded product and molding conditions. This is an example in which variation is suppressed.
In Comparative Example 1, since no compatibilizer was used, the conductivity depending on the measurement site and molding conditions of the molded product varied, and the warp of the molded product was large. In Comparative Examples 2 and 3, since the compatibilizer species is not an acid anhydride and is inferior in compatibilizing performance, there is a large variation in conductivity depending on the measurement site of the molded product, and the warpage of the molded product is also large. In Comparative Example 4, since the content of acid anhydride is too large, there is little variation in conductivity depending on the measurement site and molding conditions of the molded product, and there is little warpage of the molded product, but the conductivity is inferior compared with Example 1. It will be a thing. In Comparative Examples 5 to 8, since the amount of polyamide elastomer or the amount of carbon fiber is outside a specific range, the warpage of the molded product or the variation in conductivity is large.

  According to the present invention, it is possible to obtain a molded product having excellent conductivity, little variation in conductivity due to molding sites or molding conditions, and less warping even after standing under high temperature and high humidity conditions.

Flat gate shape Conductivity measurement position of flat plate

Claims (3)

  Graft copolymer (A) obtained by graft copolymerization of rubbery polymer (a) and one or more monomers (b1) copolymerizable therewith, and one or more monomers A copolymer (B1) obtained by copolymerizing the monomer (b2), and a copolymer (B3) obtained by copolymerizing an acid anhydride monomer and one or more monomers (b3) ( Carbon fiber (E) with respect to 100 parts by weight of the resin composition obtained by kneading 80 to 93% by weight of the rubber-reinforced thermoplastic resin (C) comprising B2) and 7 to 20% by weight of the polyamide elastomer (D) A conductive thermoplastic resin composition comprising 5 to 15 parts by weight.   The conductive thermoplastic resin composition according to claim 1, wherein 0.01 to 1.0 parts by weight of an acid anhydride component is contained in 100 parts by weight of the rubber-reinforced thermoplastic resin (C).   A molded article formed by molding the thermoplastic resin composition according to claim 1 or 2.

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