WO2013157621A1 - Masterbatch for electrically conductive resin, and electrically conductive resin - Google Patents

Abstract

The present invention pertains to a masterbatch for an electrically conductive resin. This masterbatch comprises both a thermoplastic resin exhibiting a melt flow rate (MFR) of 50 to 200 g/10min and a carbon fiber and has a carbon fiber content of 6 to 50 mass%. An electrically conductive resin obtained using the masterbatch exhibits high mechanical characteristics and high electrical conduction characteristics.

Description

Master batch for conductive resin and conductive resin

The present invention relates to a master batch for conductive resin and a conductive resin.

A resin composite material having electrical conductivity or thermal conductivity can be obtained by blending carbon fillers such as carbon black, acetylene black and ketjen black and metal fillers such as metal powder into an insulating resin molding. It is known that

In Patent Document 1, as one method of surface conductivity, it is proposed to impart surface conductivity to a molded body by kneading a conductive filler into an insulating thermoplastic resin molded body and then molding. Yes.

Patent Documents 2 to 5 disclose the use of carbon fibers as conductive fillers.

Patent Documents 6 to 7 disclose that a conductive resin composition and a general colored resin composition are manufactured via a master batch.

JP 2006-508221 A JP 2002-544308 A JP 2004-143239 A JP 2009-280825 A JP 2010-043265 A JP-A-63-113057 Japanese Patent No. 3210452

According to the method of Patent Document 1, a large amount of conductive filler is required in order to impart the necessary surface conductivity. When the addition amount is increased, the mechanical properties of the resin molded product to be produced are lowered, the strength, elongation, impact properties, etc. are lowered, and the surface appearance is deteriorated.

As described in Patent Documents 2 to 5, when carbon fiber is used, it has a low aspect ratio because of its high aspect ratio, and it is conductive with a low addition amount compared with the case where particulate filler such as carbon black is used. Is expressed. In general, when the amount of filler added is small, it is difficult to see a decrease in properties compared to the matrix resin. However, in practice, it is difficult to uniformly disperse the carbon fibers in the matrix resin, and as a result, problems such as poor dispersion and poor molding are likely to occur.

As described in Patent Documents 6 to 7, when a masterbatch is generally produced containing a filler, it is extremely fluid in order to avoid reducing physical properties such as strength of the thermoplastic resin to be diluted. Do not use high-quality resin as raw material for masterbatch.

Therefore, it has been demanded to provide a conductive resin having excellent mechanical properties and high conductive properties.

The present invention includes the following aspects.
[1] A masterbatch for a conductive resin containing a thermoplastic resin having a melt flow rate of 50 to 200 g / 10 min and carbon fiber, and having a carbon fiber content of 6% by mass to 50% by mass.
[2] The master batch for conductive resin as described in 1 above, wherein the carbon fiber is a carbon nanotube.
[3] The above 1 or 2, wherein the thermoplastic resin is at least one selected from the group consisting of ABS resin, AES resin, ASA resin, AS resin, HIPS resin, MBS resin, polyethylene, polypropylene, polycarbonate, polyphenylene ether and polyamide. The masterbatch for conductive resins as described in 2 above.
[4] A conductive resin obtained by diluting the conductive resin masterbatch according to any one of 1 to 3 with a thermoplastic resin for dilution, wherein the carbon fiber content in the conductive resin is 0. A conductive resin that is 5% by mass or more and less than 6% by mass.
[5] A method for producing a conductive resin in which the conductive resin master batch according to any one of 1 to 3 is diluted using a twin-screw extruder.
[6] A method for producing a conductive resin molded body, comprising dry blending the conductive resin masterbatch according to any one of 1 to 3 and a thermoplastic resin for dilution and injection molding.
[7] The decrease rate of Izod impact strength (ASTMD256, notched) with respect to the dilution thermoplastic resin when diluted by the method described in 5 above is 40% or less, and the surface resistance value is 15 logΩ / cm ² or less. 5. The conductive resin as described in 4 above.
[8] A decrease rate of Izod impact strength (ASTMD256, notched) with respect to the dilution thermoplastic resin when diluted by the method described in 6 is 60% or less, and a surface resistance value is 15 logΩ / cm ² or less. 5. The conductive resin as described in 4 above.
[9] A method for producing a masterbatch for a conductive resin, comprising a step of mixing carbon fibers in a thermoplastic resin having a melt flow rate of 50 to 200 g / 10 min so as to be 6% by mass to 50% by mass.
[10] The method for producing a masterbatch for a conductive resin as described in 9 above, wherein the carbon fiber is a carbon nanotube.
[11] A vehicle part formed by spraying a paint having a charge on a resin molded body obtained by molding the conductive resin as described in 4 above, to form a coating film.

According to a preferred embodiment of the present invention, it is possible to obtain a conductive resin having extremely excellent mechanical properties and high conductive properties by using a masterbatch for conductive resins containing carbon fibers.

It is a schematic diagram of the result of an Example and a comparative example. It is a comparison conceptual diagram of this invention and a prior art.

The present invention will be described in detail below.
"Thermoplastic resin"
Generally, the viscosity of a thermoplastic resin is defined by the melt flow rate (MFR). The masterbatch thermoplastic resin used in a preferred embodiment of the present invention has an MFR of 50 to 200 g / 10 min, a more preferred MFR of 70 to 190 g / 10 min, and a particularly preferred MFR of 90 to 180 g / 10 min. . When the MFR is 50 g / 10 min or more, the masterbatch and the diluted resin are kneaded well. As a result, the dispersion state of the carbon fibers in the diluted resin becomes uniform, and the mechanical properties of the resin finally produced are improved. Reduction is suppressed. Moreover, the intensity | strength required in order to shape | mold into a pellet-like masterbatch can be obtained because MFR is 200 g / 10min or less.

¡The type of thermoplastic resin used in the present invention is not particularly limited. It is more preferable from the viewpoint of dispersibility during dilution mixing that the thermoplastic resin used for the masterbatch and the thermoplastic resin for dilution are the same or have compatibility such as a close solubility parameter (SP value).

Specific examples of thermoplastic resins are:
Styrene (co) polymers such as polystyrene, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, (meth) acrylic acid ester-styrene copolymer;
Rubber reinforced resins such as ABS (acrylonitrile-butadiene-styrene) resin, AES (acrylonitrile-ethylene (EPDM) -styrene) resin, ASA (acrylonitrile-styrene-acrylate) resin, HIPS (impact polystyrene) resin;
Α-olefin (co) polymers containing at least one α-olefin having 2 to 10 carbon atoms as a monomer, such as polyethylene, polypropylene, and ethylene-propylene copolymer, and modified polymers thereof (chlorinated polyethylene, etc.), And olefin resins such as cyclic olefin copolymers;
Ethylene copolymers such as ionomers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers;
Vinyl chloride resins such as polyvinyl chloride, ethylene-vinyl chloride polymer, and polyvinylidene chloride;
An acrylic resin comprising a (co) polymer having at least one (meth) acrylic acid ester such as polymethyl methacrylate (PMMA) as a monomer;
Polyamide resins (PA) such as polyamide 6, polyamide 66, polyamide 612;
Polycarbonate (PC);
Polyester resins such as polyethylene terephthalate (PET), polybutylene phthalate (PBT), polyethylene naphthalate;
Polyacetal resin (POM);
Polyphenylene ether (PPE);
Polyarylate resin;
Fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride;
Liquid crystal polymers such as liquid crystal polyester;
Imide resins such as polyimide, polyamideimide, polyetherimide;
Ketone-based resins such as polyetherketone;
Sulfone resins such as polysulfone and polyethersulfone;
Urethane resin;
Polyvinyl acetate;
Polyethylene oxide;
Polyvinyl alcohol;
Polyvinyl ether;
Polyvinyl butyrate;
Phenoxy resin;
Photosensitive resin;
Examples include biodegradable plastics.

Of these thermoplastic resins, ABS resin, AES resin, ASA resin, AS resin, MBS resin, HIPS resin, polyethylene, polypropylene, polycarbonate (PC), polyphenylene ether (PPE), and polyamide (PA) are preferable. These can be used alone or in combination of two or more.

Further, in order to improve impact resistance, a resin obtained by adding other elastomer components to the above thermoplastic resin may be used. In general, elastomers used for improving impact resistance include olefin elastomers such as EPR and EPDM, styrene elastomers such as SBR made of a copolymer of styrene and butadiene, silicone elastomers, nitrile elastomers, and butadiene elastomers. Elastomers, urethane elastomers, polyamide elastomers, ester elastomers, fluoroelastomers, natural rubber, and modified products in which reactive sites (double bonds, carboxylic anhydride groups, etc.) are introduced into these elastomers are used Is done.

"Carbon fiber"
In a preferred embodiment of the present invention, the carbon fiber to be used is not limited, and examples thereof include pitch-based carbon fiber, PAN-based carbon fiber, carbon fiber, carbon nanofiber, and carbon nanotube. From the viewpoint of reducing the amount added, it is preferable to use carbon nanotubes. The carbon nanotube of a preferred embodiment is a tube having a cavity at the center of the fiber, and the graphene surface extends substantially parallel to the fiber axis. In the present invention, “substantially parallel” means that the inclination of the graphene layer with respect to the fiber axis is within about ± 15 degrees. The hollow portion may be continuous in the fiber longitudinal direction or may be discontinuous. In addition, single wall carbon nanotubes with a single graphene layer have high surface energy, and when dispersed in a resin, there is a tendency that the separation effect is poor and the effect of imparting conductivity tends to be small. Therefore, double-wall carbon nanotubes having two or more graphene layers and multi-wall carbon nanotubes having three or more layers are preferable, and multi-wall carbon nanotubes having three or more layers are most preferable.

Carbon fiber has a higher conductivity imparting effect when the fiber diameter is narrower. The average fiber diameter is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm, and particularly preferably 1 nm to 20 nm. From the viewpoint of dispersibility, the average fiber diameter is preferably 2 nm or more, and more preferably 4 nm or more. Therefore, when considering the dispersibility and conductivity imparting effect, the average fiber diameter is preferably 2 to 20 nm, and most preferably 4 to 20 nm.

When the inside of the carbon fiber is hollow like a carbon nanotube, the ratio (d ₀ / d) between the fiber diameter d and the cavity inner diameter d ₀ is not particularly limited, but is 0.1 to 0.9. Preferably, 0.3 to 0.9 is more preferable.

Further, the lower limit of the specific surface area by the BET method is preferably 20 m ² / g, more preferably 30 m ² / g, still more preferably 40 m ² / g, and particularly preferably 50 m ² / g. The upper limit of the specific surface area is not particularly limited, but is preferably 400 m ² / g, more preferably 350 m ² / g. More preferably, it is 300 m ² / g.

Various methods have been proposed for evaluating the surface crystal structure of carbon fibers. For example, there is a method using Raman spectroscopy. How to evaluate the ratio of the D band observed in the vicinity of G band and 1350 cm ^-1 which is observed near 1580 cm ^-1 in Raman spectroscopy (R value) is known.

The carbon fiber in a preferred embodiment of the present invention is preferably 0.1 or more, preferably 0.2 to 2.0, and most preferably 0.5 to 1.5 in the above R value. In addition, it shows that crystallinity is so low that R value is large.

The consolidation specific resistance value of the carbon fiber is preferably 1.0 × 10 ⁻² Ω · cm or less, and 1.0 × 10 ⁻³ Ω · cm to 9.9 × 10 ^{−3 at} a density of 1.0 g / cm ³ . More preferably, Ω · cm.

The fiber length of the carbon fiber is not particularly limited, but if the fiber length is too short, the conductivity imparting effect tends to be small, and if the fiber length is too long, dispersibility in the matrix resin tends to be difficult. . Accordingly, the preferred fiber length is usually 0.5 μm to 100 μm, preferably 0.5 μm to 10 μm, and more preferably 0.5 μm to 5 μm, although it depends on the thickness of the fiber.

The carbon fiber itself may be straight or may be curved and twisted. However, twisted and curved fibers are more preferable because they have excellent adhesion to the resin and have higher interfacial strength than linear fibers, so that deterioration in mechanical properties when added to a resin composite can be suppressed. . In addition, because of this twisted structure, even when dispersed in a small amount in the resin, it is a cause that the network between the fibers is not interrupted, and conductivity is not expressed in the fiber near the straight line as in the prior art It is more preferable in that conductivity is exhibited even in a low addition amount region.

In the present invention, the carbon fiber preferably forms an aggregate. In this case, the bulk density is preferably 0.03 to 0.3 g / cm ³ , more preferably 0.05 to 0.3 g / cm ³ , and particularly preferably 0.07 to 0.3 g / cm ^3. It is. When the bulk density is less than 0.03 g / cm ³ , substantially no agglomerates are formed and the fibers are easily dispersed at the stage of masterbatch production, but the fibers are broken during shearing in the secondary kneading, and thus desired. There is a case where there is no room for adjusting the conditions for obtaining the above characteristics. On the other hand, when the bulk density is 0.3 g / cm ³ or more, the degree of aggregation is extremely strong, and it may be difficult to disperse by a general kneading method.

As the bulk density measurement method, for example, JIS Z-2512 (metal powder-tap density measurement method) can be adopted.

In the present invention, the carbon fibers may form secondary aggregates. The size of the secondary aggregate is preferably 1 μm to 5 mm in the longitudinal direction, more preferably 5 μm to 3 mm, and particularly preferably 10 μm to 1 mm. If it is 5 mm or more, scattering during handling is significant, and productivity may be reduced. Moreover, if it is 1 micrometer or less, the ratio of the carbon fiber which occupies in an aggregate is very small, and it may become difficult to acquire the desired addition effect as a filler.

"Production method of carbon fiber"
The method for producing the carbon fiber is not particularly limited, but for example, a method disclosed in Japanese Patent Application Laid-Open No. 2008-174442 can be employed.

"Master batch for conductive resin"
The masterbatch can be prepared by blending and kneading the carbon fiber as described above in a thermoplastic resin for a masterbatch. The content of carbon fiber in the master batch is preferably 6% by mass or more and 50% by mass or less in the conductive resin, more preferably 7% by mass or more and 30% by mass or less, and further preferably 8% by mass or more and 25% by mass. It is as follows. However, if the concentration of the carbon fiber is increased as much as possible based on the production of a general master batch, the effect in the present invention becomes poor. On the other hand, when the addition amount exceeds 50% by mass, it becomes difficult to produce a master batch.

The content of the carbon fiber in the conductive resin after dilution of the master batch with the dilution thermoplastic resin is preferably 0.5% by mass or more and less than 6% by mass, and more preferably 0.5% by mass or more and 3% by mass or less. is there. By setting the content to 0.5% by mass or more, it is possible to form a sufficiently conductive and thermally conductive path in the resin molded body.

"Kneading method"
When kneading and dispersing the carbon fiber in the thermoplastic resin, it is preferable to carry out so as to suppress the breakage of the carbon fiber as much as possible. Specifically, the breaking rate of the carbon fiber is preferably suppressed to 20% or less, more preferably 15% or less, and particularly preferably 10% or less. The breaking rate is evaluated by comparing the aspect ratios of carbon fibers before and after mixing and kneading (for example, measured by observation with an electron microscope SEM).

Generally, when an inorganic filler is melt-kneaded into a thermoplastic resin, high shear is applied to the agglomerated filler, the filler is crushed and refined, and the filler is uniformly dispersed in the molten resin. If the shear during kneading is weak, the filler is not sufficiently dispersed in the molten resin, and a resin composite material having the expected performance and function cannot be obtained. Many kneading machines that generate a high shearing force use a stone mortar mechanism or a co-directional twin-screw extruder that introduces a kneading disk with high shear into a screw element. However, when carbon fiber is kneaded with resin, if excessively high shear is applied to the resin or carbon fiber, the carbon fiber breaks excessively, so that a resin composite material having the expected performance and function cannot be obtained. On the other hand, in the case of a single screw extruder having a weak shearing force, the breakage of the carbon fibers can be suppressed, but the dispersion of the carbon fibers is not uniform.

Therefore, in order to achieve uniform dispersion while suppressing breakage of the carbon fiber, the shear is reduced with a twin screw extruder that does not use a kneading disk, or a device that does not apply high shear such as a pressure kneader, It is desirable to knead over time or to knead using a special mixing element in a single screw extruder.

It should be noted that even in the kneading conditions when diluting the master batch with the thermoplastic resin for dilution, it is preferable to achieve uniform dispersion while suppressing breakage of the carbon fibers. For this purpose, it is possible to reduce the shear with a twin screw extruder not using a kneading disk, or to knead it with time in a high shear device such as a pressure kneader, or in a single screw extruder. It is desirable to knead using a special mixing element or dry blend with an injection molding machine.

When the conductive resin in a preferred embodiment of the present invention is diluted by a twin-screw extruder, the reduction rate of Izod impact strength (ASTMD256, notched) with respect to the thermoplastic resin for dilution is 40% or less and the surface resistance value is 15 log Ω / cm ² or less, and in the case of dilution with a dry blend, the reduction rate of Izod impact strength (ASTMD256, notched) to the thermoplastic resin for dilution is 60% or less and the surface resistance value is 15 log Ω / cm ² or less. It is. In addition, dilution with a twin-screw extruder has a smaller decrease in Izod impact strength than that with a dry blend, while dilution with a dry blend has a simpler dilution method than with a twin-screw extruder. There are advantages to both.

"Molding method"
When manufacturing a molded product from these resins, a conventionally known resin molding method can be used. Examples of the molding method include an injection molding method, a hollow molding method, an extrusion molding method, a sheet molding method, a thermoforming method, a rotational molding method, a laminate molding method, and a transfer molding method.

"Use"
The obtained conductive resin is a product that is required to have conductivity and antistatic properties as well as impact resistance, such as OA equipment, electronic equipment, conductive packaging parts, conductive sliding members, conductive thermal conductive members It can be suitably used as a molding material for antistatic packaging parts, automotive parts to which electrostatic coating is applied. In particular, in the field of electrostatic coating, from the viewpoint of cost and material properties, there is a high demand for reducing the amount of conductive filler added, and a high-strength conductive resin molded body is required. Is preferred.

The reason why the mechanical strength of the conductive resin in the present invention is extremely high is estimated as follows.
In the prior art, since the dispersibility of the filler itself is relatively good, the balance of “(A) difference in melt viscosity between master batch and diluted resin” and “(B) mechanical strength of resin for master batch” The mechanical strength of the resin after dilution is determined. FIG. 2 schematically shows the relationship between the fluidity (MFR) of the masterbatch resin, which is one index of melt viscosity, and the impact strength of the diluted resin. When a low flow resin is used as the masterbatch resin, the masterbatch resin has high mechanical strength, but the melt viscosity of the masterbatch increases as a result of filler mixing. The difference becomes large and the mixing of the resins becomes poor and the mechanical strength is lowered. On the other hand, when an ultra-high flow resin is used as the masterbatch resin, the difference in viscosity between the filler-containing masterbatch and the diluted resin is reduced, so the mixing of the resins is good, but the masterbatch resin Since the mechanical strength of the ultra-high flow resin used is low, the mechanical strength of the final resin is low. Therefore, when a general filler is used, a masterbatch resin that balances fluidity and mechanical strength is optimal.

However, when carbon fiber is used as a filler, it is estimated that a behavior different from that of a general filler occurs. When carbon fiber is used as a filler, poor mixing due to “(A) difference in melt viscosity between master batch and diluted resin”, together with poor mixing of resins, hinders dispersion of carbon fiber into diluted resin. As a result, the carbon strength of the dispersion becomes a starting point of fracture at the time of impact, resulting in a significant loss of mechanical strength. That is, it is estimated that “(A) difference in melt viscosity between master batch and diluted resin” contributes to mechanical strength more than “(B) high and low mechanical strength of masterbatch resin”.

Therefore, it is presumed that using ultra-high flow resin as a resin for masterbatch leads to an improvement in the mechanical strength of the final conductive resin, resulting in a result different from the conventional one.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples. However, the following examples are shown for illustrative purposes and are not intended to limit the present invention in any way. Absent.

(1) Components used The breakdown of the components used is as follows.
(A) ABS resin-1 (Clarastic (registered trademark) SXD-220 manufactured by Nippon A & L Co., Ltd., melt flow rate 90 g / 10 min. (220 ° C., 10 kgf load)), Izod impact strength 90 J / m (ASTM D256) )
(B) ABS resin-2 (Toyolac (registered trademark) 100-MPM-B1, manufactured by Toray Industries, Inc., melt flow rate 15 g / 10 min. (220 ° C., 10 kgf load)), Izod impact strength 210 J / m (ASTM D256)
(C) ABS resin-3 (Toyolac (registered trademark) 300 manufactured by Toray Industries, Inc., melt flow rate 10 g / 10 min. (220 ° C., 10 kgf load)), Izod impact strength 330 J / m (ASTM D256)
(220 ° C, 10kgf load))

(D) Carbon fiber-1
The carbon fiber was produced as follows. 1.81 parts by mass of iron (III) nitrate nonahydrate was added to 0.95 parts by mass of methanol and dissolved, then 0.109 parts by mass of titanium (IV) tetrabutoxide tetramer and 0.079 parts of hexaammonium heptamolybdate 0.079 A part by mass was added and dissolved to obtain a solution A. The solution A was added dropwise to 1 part by weight of intermediate alumina (Sumitomo Chemical; AKP-G015) and mixed. After mixing, vacuum drying was performed at 100 ° C. for 4 hours. After drying, the catalyst was obtained by grinding in a mortar. The catalyst contained 10 mol% Mo and 10 mol% Ti with respect to Fe, and 25 mass% Fe was supported on the intermediate alumina.

The catalyst was placed on a quartz boat, and the quartz boat was placed in a quartz reaction tube and sealed. The inside of the reaction tube was replaced with nitrogen gas, and the reactor was heated from room temperature to 690 ° C. over 60 minutes while flowing nitrogen gas. It was kept at 690 ° C. for 30 minutes while flowing nitrogen.

While maintaining the temperature at 690 ° C., the nitrogen gas was switched to a mixed gas A of nitrogen gas (100 parts by volume) and hydrogen gas (400 parts by volume), and flowed into the reactor to carry out a reduction reaction for 30 minutes. After the reduction reaction, while maintaining the temperature at 690 ° C., the mixed gas A is switched to the mixed gas B of hydrogen gas (250 parts by volume) and ethylene gas (250 parts by volume), and is allowed to flow through the reactor for 60 minutes. Reacted. The mixed gas B was switched to nitrogen gas, the inside of the reactor was replaced with nitrogen gas, and the mixture was cooled to room temperature. The reactor was opened and the quartz boat was taken out. Carbon fibers grown with the catalyst as the core were obtained. The carbon fiber has a fiber diameter of 15 nm, a specific surface area according to the BET method of 260 m ² / g, an R value of 1.1, and a consolidation specific resistance value of density 1.0 g / cm ³ is 1.2 × 10 ⁻³ Ω · cm and the bulk density were 0.08 g / cm ³ .

(2) Melt flow rate measurement method The melt flow rate was measured at a test temperature of 220 ° C. and a test load of 10 kgf in accordance with ISO1133.

(3) Surface resistance measuring method The surface resistance of the conductive resin was measured as follows. Based on JIS K6911, it measured by the double ring electrode method using the shaping | molding flat plate (100 mm x 100 mm x 3 mm thickness). As a measuring method, an applied voltage of 100 V was applied between the electrodes with a digital ultrahigh resistance meter (R8340A / 12702A, manufactured by ADC Co., Ltd.), and the resistance value after 1 minute was measured.

(4) Volume resistivity measurement method Volume resistivity was measured as follows. A test piece was cut into a strip shape (50 mm × 10 mm × 3 mm thickness) from the molded product, and a conductive tape was stretched on the cross section in the longitudinal direction, and the electrical resistance value between the cut surfaces was measured. As a measuring method, a resistance value between the both end faces was measured with a digital insulation resistance machine (MY40, manufactured by YOKOGAWA) at an applied voltage of 500 V, and a volume resistance value was calculated according to the following formula.
Volume resistance [Ω · cm] = resistance [Ω] × cross-sectional area [cm ² ] / test piece length [cm]

(5) Izod impact value measuring method For the physical property evaluation, an Izod impact test (ASTMD256, with notch) piece was prepared and evaluated. Further, the Izod impact strength reduction rate α (%) was calculated by the following formula.
α (%) = {Izod impact strength of diluted resin (J / m) −Izod impact strength of conductive resin after dilution (J / m)} / Izod impact strength of diluted resin (J / m) × 100

In this example and comparative example, the dilution resin is ABS resin (B). In Comparative Example 3, the Izod impact strength (J / m) of the diluted conductive resin was calculated by replacing the Izod impact strength (J / m) of the conductive resin after kneading.

Example 1
88% by mass of ABS resin (A) and 12% by mass of carbon fiber (D) are charged from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), kneaded, cut with a pelletizer, and pelletized. processed. The obtained master batch is added together with the dilution ABS resin (B) from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), diluted and kneaded, cut with a pelletizer, and processed into pellets did. The amount of the diluted ABS resin (B) was adjusted so that the carbon fiber content in the diluted resin was 1.5% by mass. A flat plate test piece and an Izod test piece were prepared from the obtained pellets using an injection molding machine (S-2000i100B manufactured by FUNAC), and a surface resistance value, a volume resistance value, and an Izod impact value were measured. The evaluation results are shown in Table 1. The Izod impact value was as high as 130 J / m.

Example 2
88% by mass of ABS resin (A) and 12% by mass of carbon fiber (D) are charged from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), kneaded, cut with a pelletizer, and pelletized. processed. The obtained master batch and pellets of the dilution ABS resin (B) were mixed in a polyethylene bag. The amount of the diluted ABS resin (B) was adjusted so that the carbon fiber content in the diluted resin was 1.5% by mass. A flat plate test piece and an Izod test piece are produced from the obtained pellet mixture using an injection molding machine (FUNAC S-2000i100B) (dry blend injection molding), and surface resistance value, volume resistance value, and Izod impact value are measured. did. The evaluation results are shown in Table 1. The Izod impact value was 90 J / m.

Comparative Example 1-1
88% by mass of ABS resin (B) and 12% by mass of carbon fiber (D) are added from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), kneaded, cut with a pelletizer, and pelletized. processed.
The obtained master batch is added together with the dilution ABS resin (B) from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), diluted and kneaded, cut with a pelletizer, and processed into pellets did. The amount of the diluted ABS resin (B) was adjusted so that the carbon fiber content in the diluted resin was 1.5% by mass. A flat plate test piece and an Izod test piece were prepared from the obtained pellets using an injection molding machine (S-2000i100B manufactured by FUNAC), and a surface resistance value, a volume resistance value, and an Izod impact value were measured. The evaluation results are shown in Table 2.

Comparative Example 1-2
The operation was performed in the same manner as in Comparative Example 1-1 except that the resin for producing the master batch was replaced with ABS resin (C). The evaluation results are shown in Table 2.

Comparative Example 2-1
88% by mass of ABS resin (B) and 12% by mass of carbon fiber (D) are added from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), kneaded, cut with a pelletizer, and pelletized. processed.
The obtained master batch and pellets of the dilution ABS resin (B) were mixed in a polyethylene bag. The amount of the diluted ABS resin (B) was adjusted so that the carbon fiber content in the diluted resin was 1.5% by mass. A flat plate test piece and an Izod test piece are produced from the obtained pellet mixture using an injection molding machine (S-2000i100B manufactured by FUNAC) (Dry blend injection molding), and a surface resistance value, a volume resistance value, and an Izod impact value are measured. did. The evaluation results are shown in Table 2.

Comparative Example 2-2
The operation was performed in the same manner as in Comparative Example 2-1, except that the resin for producing the master batch was replaced with ABS resin (C). The evaluation results are shown in Table 2.

Comparative Example 3
98.5% by mass of ABS resin (B) and 1.5% by mass of carbon fiber (D) are introduced from the main feed port of the same-direction twin screw extruder (KZW15TW, manufactured by Technobel Co., Ltd.), kneaded, and cut with a pelletizer. And processed into pellets. A flat plate test piece and an Izod test piece were prepared from the obtained pellets using an injection molding machine (S-2000i100B manufactured by FUNAC), and a surface resistance value, a volume resistance value, and an Izod impact value were measured. The evaluation results are shown in Table 2. The Izod impact value was as low as 70 J / m, and the surface resistance value and volume resistance value were at the same level as in Example 1.

From the above, by using carbon fiber as the conductive filler and using a resin with extremely high fluidity as the masterbatch resin, it is possible to obtain a conductive resin having high mechanical properties and high conductive properties that could not be achieved by the prior art. Can do.

Claims (11)

1. A master batch for conductive resin containing a thermoplastic resin having a melt flow rate of 50 to 200 g / 10 min and carbon fiber, and having a carbon fiber content of 6% by mass to 50% by mass.
2. The conductive resin masterbatch according to claim 1, wherein the carbon fibers are carbon nanotubes.
3. The thermoplastic resin is at least one selected from the group consisting of ABS resin, AES resin, ASA resin, AS resin, HIPS resin, MBS resin, polyethylene, polypropylene, polycarbonate, polyphenylene ether and polyamide. The masterbatch for conductive resins as described in 2.
4. A conductive resin obtained by diluting the conductive resin masterbatch according to any one of claims 1 to 3 with a dilution thermoplastic resin, wherein the carbon fiber content in the conductive resin is 0.5. A conductive resin having a mass percentage of less than 6 mass%.
5. A method for producing a conductive resin, comprising diluting the conductive resin masterbatch according to any one of claims 1 to 3 using a twin screw extruder.
6. A method for producing a conductive resin molded body, which comprises dry blending a master batch for conductive resin according to any one of claims 1 to 3 and a thermoplastic resin for dilution and injection molding.
7. The reduction rate of the Izod impact strength (ASTMD256, notched) with respect to the dilution thermoplastic resin when diluted by the method according to claim 5 is 40% or less, and the surface resistance value is 15 logΩ / cm ² or less. The conductive resin according to claim 4.
8. The reduction rate of the Izod impact strength (ASTMD256, notched) with respect to the dilution thermoplastic resin when diluted by the method according to claim 6 is 60% or less, and the surface resistance value is 15 logΩ / cm ² or less. The conductive resin according to claim 4.
9. A method for producing a masterbatch for a conductive resin, comprising a step of mixing carbon fibers in a thermoplastic resin having a melt flow rate of 50 to 200 g / 10 min so as to be 6% by mass to 50% by mass.
10. The method for producing a masterbatch for a conductive resin according to claim 9, wherein the carbon fiber is a carbon nanotube.
11. A vehicle part formed by spraying a paint having a charge on a resin molded body obtained by molding the conductive resin according to claim 4.

Images