阅读说明：本技术 导电性树脂组合物、其制造方法、及由其得到的成型体 (Conductive resin composition, method for producing same, and molded article obtained therefrom ) 是由 金谷浩贵 高桥庸祐 松永幸治 川边邦昭 于 2020-04-23 设计创作，主要内容包括：本发明的课题在于提供兼具高导电性和优异加工性的导电性树脂组合物。解决该课题的导电性树脂组合物包含热塑性树脂(A)、外径为100nm以下的碳纳米管(B)、和利用芳香族单体对聚烯烃蜡进行改性而得到的芳香族单体改性聚烯烃蜡(C)。相对于上述热塑性树脂(A)、上述碳纳米管(B)、及上述芳香族单体改性聚烯烃蜡(C)的合计100质量份而言,包含74.9～99.4质量份的上述热塑性树脂(A)、0.5～25质量份的上述碳纳米管(B)、0.1～10质量份的上述芳香族单体改性聚烯烃蜡(C)。(The present invention addresses the problem of providing a conductive resin composition having both high conductivity and excellent processability. The conductive resin composition comprises a thermoplastic resin (A), carbon nanotubes (B) having an outer diameter of 100nm or less, and an aromatic monomer-modified polyolefin wax (C) obtained by modifying a polyolefin wax with an aromatic monomer. The thermoplastic resin (A), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C) are contained in an amount of 74.9 to 99.4 parts by mass, 0.5 to 25 parts by mass, and 0.1 to 10 parts by mass, based on 100 parts by mass of the total of the thermoplastic resin (A), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C).)

1. An electrically conductive resin composition comprising:

a thermoplastic resin (A);

a carbon nanotube (B) having an outer diameter of 100nm or less; and

an aromatic monomer-modified polyolefin wax (C) obtained by modifying a polyolefin wax with an aromatic monomer,

the resin composition comprises 74.9 to 99.4 parts by mass of the thermoplastic resin (A), 0.5 to 25 parts by mass of the carbon nanotubes (B), and 0.1 to 10 parts by mass of the aromatic monomer-modified polyolefin wax (C), based on 100 parts by mass of the total amount of the thermoplastic resin (A), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C).

2. The conductive resin composition according to claim 1, wherein the aromatic monomer-modified polyolefin wax (C) satisfies the following requirements (i) to (iv),

(i) a number average molecular weight (Mn) in terms of polystyrene measured by Gel Permeation Chromatography (GPC) is in the range of 300 to 10000;

(ii) a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 9.0 or less as measured by Gel Permeation Chromatography (GPC);

(iii) a softening point measured in accordance with JIS K2207 is in the range of 70-170 ℃;

(iv) the density measured according to JIS K7112 is 830-1200 kg/m³Within the range of (1).

3. The conductive resin composition according to claim 1 or 2, wherein the aromatic monomer-modified polyolefin wax (C) is a compound obtained by modifying a copolymer of ethylene and at least one α -olefin selected from α -olefins having 3 to 12 carbon atoms with an aromatic monomer.

4. The conductive resin composition according to any one of claims 1 to 3, wherein the amount of the structural unit derived from the aromatic monomer in the aromatic monomer-modified polyolefin wax (C) is 5 to 95% by mass.

5. The conductive resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin (A) is at least one resin selected from the group consisting of an ethylene (co) polymer, a propylene (co) polymer, and a polycarbonate.

6. The method for producing the conductive resin composition according to any one of claims 1 to 5, comprising the steps of:

preparing a master batch containing the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C); and

and (b) melt-kneading the master batch and the thermoplastic resin (a).

7. A molded article obtained from the conductive resin composition according to any one of claims 1 to 5.

Technical Field

The present invention relates to a conductive resin composition, a method for producing the same, and a molded article obtained from the same.

Background

Thermoplastic resins are used in a wide range of fields such as automobile parts, electric and electronic parts, and structural materials because of their excellent characteristics such as mechanical strength, heat resistance, and moldability. However, since a large amount of thermoplastic resin is insulating, it is necessary to form a composite with a conductive material in order to impart conductivity. As the conductive material, metal powder, metal fiber, and carbon material are generally known. Among these, a carbon material can reduce the weight of a molded body, and various types of carbon materials have been developed. Examples of the carbon material used as the conductive material include carbon black, graphite, carbon nanotube, and the like. The compounding of these carbon materials with the thermoplastic resin is carried out by forced kneading and dispersion using a kneading machine such as an extruder and a kneader.

However, the carbon nanotubes are easily broken by forced kneading and dispersing in the case of being compounded with a thermoplastic resin. Therefore, the conductive resin composition containing carbon nanotubes often cannot obtain the desired conductivity. In addition, among carbon materials, carbon nanotubes have a particularly large specific surface area. Therefore, when the resin is compounded, a sharp increase in viscosity is likely to occur, and the amount of addition is limited. This also has a problem that it is difficult to impart sufficient conductivity to the conductive resin composition.

Among them, patent document 1 describes that carbon nanotubes are combined with propylene-olefin-copolymer wax for the purpose of improving conductivity and processability. Patent document 2 describes that an olefin wax having a low density, that is, a low melting point, obtained by copolymerization using a metallocene catalyst is combined with carbon nanotubes and a resin.

On the other hand, patent documents 3 and 4 describe that a low molecular weight polyethylene wax or an aqueous resin is applied to the surface of a carbon nanotube.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5389181

Patent document 2: japanese patent No. 5597318

Patent document 3: japanese patent No. 4787892

Patent document 4: japanese patent laid-open publication No. 2018-177586

Disclosure of Invention

Problems to be solved by the invention

In the above patent documents 1 and 2, olefin-based waxes are used as the waxes. Therefore, when a polar resin (for example, a chlorine-based resin typified by polyvinyl chloride or an acrylic resin typified by polymethyl methacrylate) is used as the thermoplastic resin, there is a problem that it is difficult for the thermoplastic resin to be compatible with the wax, and thus a sufficient effect cannot be obtained.

In addition, patent documents 3 and 4 have the following problems: the carbon nanotubes need to be coated with wax or an aqueous resin, which makes the operation complicated or increases the cost easily.

The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide a conductive resin composition having both high conductivity and excellent processability.

Means for solving the problems

The inventors of the present application have found that a conductive resin composition which achieves both conductivity and processability can be obtained by combining an aromatic monomer-modified polyolefin wax (C) with a carbon nanotube (B) having an outer diameter of 100nm or less. Namely, the present invention relates to the following [1] to [7 ].

[1] A conductive resin composition comprising a thermoplastic resin (A), carbon nanotubes (B) having an outer diameter of 100nm or less, and an aromatic monomer-modified polyolefin wax (C) obtained by modifying a polyolefin wax with an aromatic monomer, wherein the conductive resin composition comprises, based on 100 parts by mass of the total amount of the thermoplastic resin (A), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C), 74.9 to 99.4 parts by mass of the thermoplastic resin (A), 0.5 to 25 parts by mass of the carbon nanotubes (B), and 0.1 to 10 parts by mass of the aromatic monomer-modified polyolefin wax (C).

[2] The conductive resin composition according to [1], wherein the aromatic monomer-modified polyolefin wax (C) satisfies the following requirements (i) to (iv).

(i) The number average molecular weight (Mn) in terms of polystyrene measured by Gel Permeation Chromatography (GPC) is in the range of 300-10000

(ii) A ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 9.0 or less as measured by Gel Permeation Chromatography (GPC)

(iii) The softening point measured according to JIS K2207 is in the range of 70-170 DEG C

(iv) The density measured according to JIS K7112 is 830-1200 kg/m³In the range of

[3] The conductive resin composition according to [1] or [2], wherein the aromatic monomer-modified polyolefin wax (C) is a compound obtained by modifying a copolymer of ethylene and at least one α -olefin selected from α -olefins having 3 to 12 carbon atoms with an aromatic monomer.

[4] The conductive resin composition according to any one of [1] to [3], wherein the amount of the structural unit derived from the aromatic monomer in the aromatic monomer-modified polyolefin wax (C) is 5 to 95% by mass.

[5] The conductive resin composition according to any one of [1] to [4], wherein the thermoplastic resin (A) is at least one resin selected from the group consisting of an ethylene (co) polymer, a propylene (co) polymer, and a polycarbonate.

[6] The method for producing the conductive resin composition according to any one of [1] to [5], which comprises the steps of:

preparing a master batch containing the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C); and

and (b) melt-kneading the master batch and the thermoplastic resin (a).

[7] A molded article obtained from the conductive resin composition according to any one of the above [1] to [5 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a conductive resin composition having both high conductivity and excellent processability can be provided.

Drawings

FIG. 1 is a graph showing the relationship between the viscosity average molecular weight (Mv) of the aromatic monomer-modified polyolefin wax (C) used in examples 2,4 to 7 and comparative example 4 and the conductivity (volume resistivity) of the conductive resin composition.

FIG. 2 is an electron micrograph showing the state of carbon nanotubes (B) in the conductive resin compositions of examples 2,4 and 5 and comparative example 4.

Detailed Description

The present invention will be specifically described below. In the following description, unless otherwise specified, "to" indicating a numerical range means not less than and not more than.

1. Conductive resin composition

The conductive resin composition of the present invention contains a thermoplastic resin (A), carbon nanotubes (B) having an outer diameter of 100nm or less, and an aromatic monomer-modified polyolefin wax (C).

The amount of the thermoplastic resin (a) is 74.9 to 99.4 parts by mass, preferably 80 to 99 parts by mass, and more preferably 85 to 98.5 parts by mass, based on 100 parts by mass of the total of the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C) in the conductive resin composition of the present invention. In order to obtain high processability, the content of the thermoplastic resin (A) is preferably high. In the conductive resin composition particularly requiring high processability, the lower limit of the thermoplastic resin (a) is preferably 93 parts by mass, preferably 95 parts by mass, and more preferably 97 parts by mass.

On the other hand, when the total amount of the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C) in the conductive resin composition is 100 parts by mass, the amount of the carbon nanotubes (B) is 0.5 to 25 parts by mass, preferably 1 to 20 parts by mass, and more preferably 1.5 to 15 parts by mass. By containing the carbon nanotubes (B) in an amount of 0.5 parts by mass or more, the conductivity of the conductive resin composition (or the molded product thereof) becomes good. When the amount of the carbon nanotubes (B) is 25 parts by mass or less, the processability of the conductive resin composition is improved. In order to obtain high conductivity, that is, low volume resistivity, it is preferable to increase the amount of the carbon nanotubes (B). In the conductive resin composition particularly requiring high conductivity, the lower limit of the carbon nanotube (B) is 3 parts by mass, preferably 5 parts by mass, and more preferably 7 parts by mass.

The amount of the aromatic monomer-modified polyolefin wax (C) is 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, and more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the total of the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C) in the conductive resin composition. By containing the aromatic monomer-modified polyolefin wax (C) in an amount of 0.1 part by mass or more, the conductive resin composition can be easily improved in conductivity and processability. On the other hand, when the content of the aromatic monomer-modified polyolefin wax (C) is 10 parts by mass or less, the properties inherent in the thermoplastic resin (a) are not easily impaired, and the processability of the conductive resin composition is easily improved.

The conductivity of the conductive resin composition (or a molded article thereof) was evaluated by a volume resistivity measured in accordance with ASTM D257. The preferable volume resistivity of the conductive resin composition (or the molded product thereof) is appropriately selected depending on the application. For example, when the conductive resin composition of the present invention is used as a packaging material for semiconductor products such as IC trays, silicon wafer cassettes, and carrier tapes, the volume inherent property of the conductive resin compositionThe resistance value is preferably 1.0X 10⁷～1.0×10⁹Omega cm. When the conductive resin composition is used as a clean room floor material, a belt conveyor, a weak current component for OA equipment, or an electrostatic coating substrate, the volume resistivity is preferably 1.0X 10⁴～1.0×10⁶Omega cm. When the conductive resin composition is used as an electromagnetic wave shielding member for OA equipment, the volume resistivity is preferably 1.0 × 10^-1About 1.0X 10. omega. cm. The volume resistivity of the conductive resin composition is adjusted by the type and content of the carbon nanotubes (B) and the type and content of the aromatic monomer-modified polyolefin wax (C).

The conductive resin composition preferably has a flexural modulus of 100 to 400%, more preferably 100 to 300%, and still more preferably 100 to 250% as measured in accordance with JIS K7171(ISO 178) with respect to the flexural modulus of the thermoplastic resin (a) alone contained in the conductive resin composition. When the flexural modulus of the conductive resin composition is within the above range, the decrease in flexural modulus of the conductive resin composition due to the addition of the carbon nanotubes (B) is small, and the conductive resin composition can be easily applied to various applications. The flexural modulus of the conductive resin composition is adjusted by the composition of the conductive resin composition (particularly, the type of the thermoplastic resin (a), the content of the carbon nanotubes (B), and the like).

Hereinafter, components contained in the conductive resin composition, physical properties of the conductive resin composition, and the like will be described.

1-1. thermoplastic resin (A)

1-1-1 kinds of thermoplastic resin (A)

The thermoplastic resin (a) contained in the conductive resin composition can be appropriately selected depending on the use of the conductive resin composition. Representative examples of the thermoplastic resin (a) usable in the conductive resin composition include the following resins (1) to (16). The conductive resin composition may contain only 1 kind of them, or may contain 2 or more kinds.

(1) Olefin polymer

(2) Polyamide

(3) Polyester

(4) Polyacetal (PA)

(5) Styrene resin

(6) Acrylic resin

(7) Polycarbonate resin

(8) Polyphenylene ether

(9) Chlorine-based resin

(10) Vinyl acetate resin

(11) Ethylene- (meth) acrylate copolymers

(12) Ethylene- (meth) acrylic acid resins, ionomer resins thereof

(13) Vinyl alcohol resin

(14) Cellulose resin

(15) Thermoplastic elastomer

(16) Various copolymer rubbers

The thermoplastic resins (1) to (16) are specifically described below.

(1) Olefin polymer

Examples of the olefin-based polymer include: olefin homopolymers such as polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene and polymethylbutene; olefin copolymers such as ethylene- α -olefin random copolymers, propylene-ethylene random copolymers, ethylene- α -olefin-nonconjugated polyene copolymers, and 4-methyl-1-pentene- α -olefin copolymers; and so on. Among the above, the olefin-based polymer is preferably an ethylene (co) polymer or a propylene (co) polymer.

The ethylene (co) polymer is preferably an ethylene homopolymer (polyethylene) or a copolymer of ethylene and an alpha-olefin having 3 to 12 carbon atoms. Specific examples of the ethylene homopolymer include ultrahigh molecular weight polyethylene, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and the like.

On the other hand, when the ethylene (co) polymer is a copolymer of ethylene and an α -olefin having 3 to 12 carbon atoms, the amount (a) of the structural unit derived from ethylene is preferably 91.0 to 99.9 mol%, more preferably 93.0 to 99.9 mol%, still more preferably 95.0 to 99.9 mol%, and particularly preferably 95.0 to 99.0 mol%. The other partyThe amount (b) of the structural unit derived from an α -olefin having 3 or more carbon atoms is preferably 0.1 to 9.0 mol%, more preferably 0.1 to 7.0 mol%, still more preferably 0.1 to 5.0 mol%, and particularly preferably 1.0 to 5.0 mol%. Wherein (a) + (b) is 100 mol%. The content ratio of the structural units of the ethylene copolymer is determined by¹³And C-NMR spectrum was analyzed.

Examples of the α -olefin having 3 to 12 carbon atoms include linear or branched α -olefins such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, and 1-undecene. The alpha-olefin is preferably propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene. Further preferred is an alpha-olefin having 3 to 8 carbon atoms, and particularly preferred is propylene or 1-butene. When ethylene is copolymerized with propylene or 1-butene, the processability of the conductive resin composition becomes good, and the appearance, mechanical strength, and the like of the obtained molded article become good. The ethylene (co) polymer may be used alone or in combination of 2 or more.

The ethylene (co) polymer preferably has a Melt Flow Rate (MFR) of 0.01 to 500g/10 min, more preferably 0.1 to 100g/10 min, as measured according to ISO 1133 at 190 ℃ under a load of 2.16 kg. When the MFR of the ethylene (co) polymer is within the above range, the flowability at the time of molding becomes good, and a molded article having good mechanical strength can be easily obtained.

On the other hand, the propylene (co) polymer is preferably a propylene homopolymer (polypropylene) or a copolymer of propylene and ethylene or an α -olefin having 4 to 12 carbon atoms.

When the propylene (co) polymer is a copolymer of propylene and ethylene, the amount of the structural unit derived from propylene is preferably 60 to 99.5 mol%. The amount of the structural unit derived from propylene is preferably 80 to 99 mol%, more preferably 90 to 98.5 mol%, and still more preferably 95 to 98 mol%. Wherein the total of the amount of the structural unit derived from propylene and the amount of the structural unit derived from ethylene is 100 mol%. When a propylene (co) polymer having a large amount of a propylene-derived structural unit is used, the heat resistance, appearance and mechanical strength of the resulting molded article become good.

When the propylene (co) polymer is a copolymer of propylene and an α -olefin having 4 to 12 carbon atoms, examples of the α -olefin having 4 to 12 carbon atoms include linear or branched α -olefins such as 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, and 1-undecene. Among them, 1-butene is particularly preferable. The propylene/α -olefin copolymer may further contain a structural unit derived from an olefin other than those having 4 to 12 carbon atoms, and may contain a small amount, for example, 10 mol% or less of a structural unit derived from ethylene. On the other hand, when the ethylene-derived structural unit is not contained, the balance between the heat resistance and the mechanical strength of the obtained molded article tends to be particularly good. In the propylene (co) polymer, only one kind of α -olefin may be used, or two or more kinds may be used in combination.

When the propylene (co) polymer is a propylene/α -olefin copolymer, the amount (a') of the structural unit derived from propylene is preferably 60 to 90 mol%, more preferably 65 to 88 mol%, still more preferably 70 to 85 mol%, and particularly preferably 75 to 82 mol%. On the other hand, the amount (b') of the structural unit derived from an α -olefin having 4 or more carbon atoms is preferably 10 to 40 mol%, more preferably 12 to 35 mol%, still more preferably 15 to 30 mol%, and particularly preferably 18 to 25 mol%. Wherein (a ') + (b') -100 mol%.

When the composition of the propylene/α -olefin copolymer is within the above range, a molded article having excellent appearance can be obtained. The reason for this is not clear, but in the case of the above composition, the crystallization rate becomes slow, and the flow time of the conductive resin composition on the mold or in the cooling step becomes long. As a result, it is considered that the surface is easily smoothed. When the composition is within the above range, the resulting molded article has good mechanical strength and heat resistance.

The propylene- α -olefin copolymer preferably has a melting point (Tm) of 60 to 120 ℃, preferably 65 to 100 ℃, and more preferably 70 to 90 ℃ as measured by a Differential Scanning Calorimeter (DSC).

The olefin-based polymer may be an ethylene/α -olefin/nonconjugated polyene copolymer. In this case, a copolymer of ethylene and an α -olefin having 3 to 12 carbon atoms and a nonconjugated polyene is preferable, and a polymer obtained by randomly copolymerizing these is more preferable. The α -olefin is preferably an α -olefin having 3 to 12 carbon atoms, and examples thereof include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, and 1-undecene. Examples of the nonconjugated polyene include cyclic or chain nonconjugated polyenes. Examples of the cyclic nonconjugated polyene include cyclopentene, cycloheptene, norbornene, 5-ethylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, norbornadiene and methyltetrahydroindene, tetracycloundecene, and the like. Examples of the chain nonconjugated polyene include 1, 4-hexadiene, 7-methyl-1, 6-octadiene, 4-ethylene-8-methyl-1, 7-nonadiene, 4-ethylene-1, 7-undecadiene and the like. Of these, 5-ethylidene-2-norbornene, dicyclopentadiene, or 5-vinyl-2-norbornene is preferable. These cyclic or chain nonconjugated polyenes may be used alone or in combination of two or more.

Specific examples of the ethylene/α -olefin/unconjugated polyene random copolymer include ethylene/propylene/diene terpolymers (EPDM).

As the olefin-based polymer, a copolymer of propylene, α -olefin, and unconjugated polyene, a copolymer of 1-butene, α -olefin, and unconjugated polyene, or the like can be used.

Further, as the olefin-based polymer, a 4-methyl-1-pentene α -olefin copolymer may be used. Specific examples of the 4-methyl-1-pentene α -olefin copolymer include the polymers disclosed in International publication No. 2011/055803. The amount of the structural unit derived from 4-methyl-1-pentene in the 4-methyl-1-pentene/α -olefin copolymer is preferably 5 to 95 mol%, and the amount of the structural unit derived from at least one α -olefin selected from α -olefins having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is preferably 5 to 95 mol%. The 4-methyl-1-pentene/α -olefin copolymer may partially contain a non-conjugated polyene, and the amount of the structural unit derived from the non-conjugated polyene is preferably 0 to 10 mol%. The total amount thereof was 100 mol%.

The stereoregularity of the olefin polymer is not particularly limited, and when the olefin polymer is a propylene (co) polymer, it is preferable that the propylene (co) polymer substantially have a syndiotactic structure. For example, when the propylene (co) polymer has a substantially syndiotactic structure, the intermolecular entanglement molecular weight (Me) becomes smaller and the entanglement of molecules becomes larger at the same molecular weight. Therefore, the melt tension becomes large, and liquid dripping is less likely to occur. In addition, when a molded article is produced using a conductive resin composition containing a propylene (co) polymer, the molded article is likely to appropriately adhere to a mold or a roller for molding. In addition, since the crystallization rate of a propylene (co) polymer having a syndiotactic structure is slower than that of a general isotactic polypropylene (co) polymer, cooling on a mold or a roll becomes smooth, and adhesion is improved. As a result, it is estimated that the surface gloss of the molded article is improved, and the abrasion resistance, scratch resistance, impact resistance and the like are improved.

The term "propylene (co) polymer having a substantially syndiotactic structure" means that¹³The peak area corresponding to 19.5 to 20.3ppm in the C-NMR spectrum is 0.5% or more relative to the total peak area detected. When the syndiotacticity is within the above range, the crystallization rate is sufficiently reduced and the processability is very good. In addition, a propylene (co) polymer having a substantially syndiotactic structure in a propylene-derived structural unit has very good abrasion resistance and scratch resistance as compared with polyethylene, block polypropylene and isotactic polypropylene, which are general-purpose polyolefin resins. The propylene (co) polymer having a syndiotactic structure can be produced by various known production methods.

Among them, when the thermoplastic resin (a) is the above-mentioned olefin-based polymer, an unmodified olefin-based polymer is preferable from the viewpoint of retaining the shape of the carbon nanotubes (B) in the conductive resin composition and obtaining a molded article having excellent conductivity. In this case, the acid value of the olefin polymer is preferably less than 1mgKOHmg/g, and the styrene content is preferably 5% by mass or less.

On the other hand, from the viewpoint of improving the heat resistance and mechanical strength of the conductive resin composition (or a molded article thereof), the olefin-based polymer may be graft-modified with a polar compound having a double bond. When the olefin-based polymer is graft-modified, the affinity between the thermoplastic resin (a) and the carbon nanotubes (B) is improved, and a molded article having excellent heat resistance and mechanical strength is easily obtained.

The graft modification of the olefin-based polymer can be carried out by a known method. The following methods may be used: the olefin polymer is dissolved in an organic solvent, and then a polar compound having a double bond such as unsaturated carboxylic acid and a radical polymerization initiator are added to the obtained solution to react at 60 to 350 ℃ (preferably 80 to 190 ℃) for 0.5 to 15 hours (preferably 1 to 10 hours).

The organic solvent is not particularly limited as long as it is an organic solvent capable of dissolving the olefin polymer. Examples of such organic solvents include: aromatic hydrocarbon solvents such as benzene, toluene, and xylene; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane.

In addition, as another graft modification method, the following methods can be mentioned: the olefinic polymer is preferably reacted with a polar compound having a double bond such as an unsaturated carboxylic acid using an extruder or the like, preferably without using a solvent. In this case, the reaction temperature is preferably not less than the melting point of the olefin polymer, and more specifically, preferably 100 to 350 ℃. The reaction time is preferably 0.5 to 10 minutes.

In order to graft-copolymerize the polar compound having a double bond efficiently, the above graft modification is preferably carried out in the presence of a radical polymerization initiator. Examples of the radical polymerization initiator include organic peroxides, organic peroxy esters (e.g., benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2, 5-dimethyl-2, 5-di (peroxybenzoate) hex-3-yne, 1, 4-bis (t-butylperoxyisopropyl) benzene, lauroyl peroxide, t-butyl peroxyacetate, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hex-3-yne, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, t-butyl peroxybenzoate, t-butyl peroxyphenylacetate, t-butyl peroxyisobutyrate, t-butyl peroxyoctoate, t-butyl peroxypivalate, cumyl peroxypivalate, and t-butyl peroxydiethylacetate), Azo compounds (e.g., azobisisobutyronitrile, dimethyl azoisobutyrate), and the like.

Among these, dialkyl peroxides such as dicumyl peroxide, di-t-butyl peroxide, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hex-3-yne, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, and 1, 4-bis (t-butylperoxyisopropyl) benzene are preferable. The radical polymerization initiator is usually used in an amount of 0.001 to 1 part by mass per 100 parts by mass of the olefin-based polymer before modification.

The shape of the graft-modified olefin polymer is not particularly limited, and may be, for example, a particulate shape. Examples of suitable methods for obtaining a particulate graft-modified olefin polymer include the following methods: a method for producing a graft copolymer, which comprises subjecting particles, which are formed from 1 or 2 or more alpha-olefins selected from alpha-olefins having 2 to 18 carbon atoms and have a melting point of 50 ℃ or higher and less than 250 ℃, to a graft reaction with a monomer having an ethylenically unsaturated group and a polar functional group in the same molecule. The graft reaction can be carried out at a temperature not higher than the melting point (Tm) of the olefin polymer particles using the above-mentioned radical polymerization initiator. The average particle diameter of the graft-modified olefin-based polymer particles may be, for example, 0.2mm to 2.5mm, but is not limited thereto. The melting point of the olefin polymer particles used for the preparation of the particulate graft-modified olefin polymer is usually 50 ℃ or higher and less than 250 ℃, but is not limited thereto. The above-mentioned grafting reaction may also be carried out in the absence of a solvent, but is preferably carried out in the presence of an organic solvent.

(2) Polyamide

Examples of polyamides include: aliphatic polyamides such as nylon-6, nylon-66, nylon-10, nylon-11, nylon-12, nylon-46, nylon 66, nylon-610 and nylon-612; aromatic polyamides produced from aromatic dicarboxylic acids and aliphatic diamines; and so on. Among these, nylon-6 is preferable.

(3) Polyester

Examples of the polyester include aromatic polyesters such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, polycaprolactone, polyhydroxybutyrate, polyester elastomers and the like. Among these, polyethylene terephthalate is preferred.

(4) Polyacetal (PA)

Examples of the polyacetal include polyoxymethylene (polyoxymethylene), polyacetaldehyde, propionaldehyde and polybutyraldehyde. Among these, polyoxymethylene is particularly preferable.

(5) Styrene resin

The styrene-based resin may be a homopolymer of styrene (polystyrene), or a binary copolymer of styrene and acrylonitrile, methyl methacrylate, α -methylstyrene, or the like, for example, an acrylonitrile-styrene copolymer. In addition, an acrylonitrile-butadiene-styrene (ABS) resin, an acrylonitrile-acrylic rubber-styrene resin, an acrylonitrile-ethylene rubber-styrene resin, (meth) acrylate-styrene resin, or various styrene-based elastomers may be used.

The acrylonitrile-butadiene-styrene (ABS) resin preferably contains 20 to 35 mol% of a structural unit derived from acrylonitrile, 20 to 30 mol% of a structural unit derived from butadiene, and 40 to 60 mol% of a structural unit derived from styrene. The sum of these structural units is 100 mol%.

As the styrene-based elastomer, a known styrene-based elastomer having a polystyrene phase as a hard segment can also be used. Specific examples thereof include styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), and hydrogenated products thereof, styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), and the like. Among these, styrene-isobutylene-styrene triblock copolymers (SIBS) and styrene-isobutylene diblock copolymers (SIB) are preferable.

(6) Acrylic resin

Examples of the acrylic resin include polymethacrylate and polyethylmethacrylate, and among them, polymethyl methacrylate (PMMA) is preferable.

(7) Polycarbonate resin

Examples of the polycarbonate include polycarbonates obtained from bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxyphenyl) propane, 2-bis (4-hydroxyphenyl) butane and the like. Among these, a polycarbonate obtained from 2, 2-bis (4-hydroxyphenyl) propane is preferred.

The polycarbonate preferably has a Melt Flow Rate (MFR) of 2 to 30g/10 min, more preferably 5 to 20g/10 min, as measured according to ISO 1133 at 300 ℃ under a load of 2.16 kg. When the MFR of the polycarbonate is within this range, processability becomes good.

(8) Polyphenylene ether

As the polyphenylene ether, poly (2, 6-dimethyl-1, 4-phenylene ether) is preferred.

(9) Chlorine-based resin

Examples of the chlorine-based resin include polyvinyl chloride, polyvinylidene chloride, and the like. The polyvinyl chloride may be a homopolymer of vinyl chloride, or a copolymer of vinyl chloride with vinylidene chloride, acrylic acid ester, acrylonitrile, propylene, or the like. On the other hand, polyvinylidene chloride is generally a resin containing 85% or more of vinylidene chloride units, and is, for example, a copolymer of vinylidene chloride with vinyl chloride, acrylonitrile, (meth) acrylic acid ester, allyl ester, unsaturated ether, styrene, or the like. The chlorine-based resin may be a vinyl chloride-based elastomer.

(10) Vinyl acetate resin

Examples of the vinyl acetate-based resin include homopolymers of vinyl acetate (polyvinyl acetate), and copolymers of vinyl acetate with ethylene or vinyl chloride. Among these, ethylene-vinyl acetate copolymers are preferred. Further, a modified ethylene-vinyl acetate copolymer such as a saponified ethylene-vinyl acetate copolymer or a graft-modified ethylene-vinyl acetate copolymer may be used.

(11) Ethylene- (meth) acrylate copolymers

The ethylene- (meth) acrylate copolymer is preferably an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl methacrylate copolymer, or an ethylene-ethyl methacrylate copolymer.

(12) Ethylene- (meth) acrylic acid resins, ionomer resins thereof

The ethylene- (meth) acrylic acid copolymer is a copolymer of ethylene and various (meth) acrylic acids. They may also be further metallated to make metal salts (ionomers). The metal element of the metal salt is preferably at least one selected from the group consisting of K, Na, Ca and Zn. When the metal element is K, Na, Ca, or Zn, the modification is easy, and therefore, the metal element is more preferable.

(13) Vinyl alcohol resin

Examples of the vinyl alcohol resin include polyvinyl alcohol, ethylene-vinyl alcohol resin and the like, and ethylene-vinyl alcohol resin is preferable. Ethylene-vinyl alcohol resins are obtainable by hydrolysis of copolymers of ethylene and vinyl acetate. The ethylene-vinyl alcohol resin has high gas barrier properties, oil resistance and transparency of polyvinyl alcohol, and also has characteristics such as moisture resistance and melt extrusion processability of an ethylene component.

(14) Cellulose resin

Examples of the cellulose resin include acetyl cellulose. When a cellulose resin is used, the properties as a thermoplastic resin can be obtained by using a plasticizer such as dibutyl phthalate in combination.

(15) Thermoplastic elastomer

Examples of the thermoplastic elastomer include vinyl chloride-based elastomers, urethane-based elastomers, polyester-based elastomers, and the like, and among these, urethane-based elastomers are preferable.

Examples of the urethane-based elastomer include thermoplastic polyurethane materials. The thermoplastic polyurethane material has a structure formed of a soft segment made of a high-molecular polyol (polymeric diol), a chain extender constituting the hard segment, and diisocyanate.

Among them, the same material as known thermoplastic polyurethane can be used as the polymer polyol as a raw material. The high-molecular polyol includes a polyester and a polyether. Among these, polyether-based polyurethane materials are preferable because they allow synthesis of thermoplastic polyurethane materials having a high modulus of rebound elasticity and excellent low-temperature characteristics. Examples of the polyether polyol include poly-1, 4-butanediol, polypropylene glycol and the like, and poly-1, 4-butanediol is particularly preferable from the viewpoint of the modulus of elasticity for resilience and low-temperature characteristics. The average molecular weight of the polymer polyol is preferably 1000 to 5000, and more preferably 2000 to 4000, particularly for synthesizing a thermoplastic polyurethane material having high resilience elasticity.

On the other hand, as the chain extender, those conventionally used in the art relating to thermoplastic polyurethane materials can be used, and examples thereof include 1, 4-butanediol, 1, 2-ethanediol, 1, 3-butanediol, 1, 6-hexanediol, 2-dimethyl-1, 3-propanediol and the like. However, it is not limited to these. The average molecular weight of the chain extenders is preferably 20 to 15000.

The diisocyanate used in the conventional art relating to thermoplastic polyurethane materials can be used, and examples thereof include aromatic diisocyanates such as 4, 4' -diphenylmethane diisocyanate, 2, 4-tolylene diisocyanate and 2, 6-tolylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate. However, it is not limited to these. Among these, 4' -diphenylmethane diisocyanate is particularly preferable as the aromatic diisocyanate.

As the urethane elastomer composed of the above-mentioned material, commercially available products can be suitably used, and examples thereof include PANDEX T-8290, T-8295 and T8260 manufactured by DIC Bayer Polymer Ltd, and RESAMINE2593 and 2597 manufactured by Dai Denko chemical industries, Ltd.

(16) Various copolymer rubbers

The thermoplastic resin may be various rubbers other than the above-described elastomers. Examples of the various copolymer rubbers include polybutadiene rubber, polyisoprene rubber, chloroprene rubber, nitrile rubber, butyl rubber, halogenated butyl rubber, polyisobutylene rubber, natural rubber, silicone rubber, and the like. These rubbers may be used alone in 1 kind, or may be used in combination with 2 or more kinds.

Among the thermoplastic resins (1) to (16), the thermoplastic resin (a) is preferably at least one resin selected from the group consisting of (1) olefin polymers (including acid-grafted modified products thereof), (5) styrene resins, (7) polycarbonates, (9) chlorine resins, (12) ethylene-acrylic acid resins, ethylene-methacrylic acid resins, ionomer resins thereof, (15) thermoplastic elastomers, and (16) various copolymer rubbers. Further, at least one resin selected from the group consisting of olefin polymers, polystyrene, acrylonitrile-butadiene-styrene copolymer resins (ABS resins), polyvinyl chloride, and polycarbonates is more preferable, and ethylene (co) polymers such as polyethylene, propylene (co) polymers such as polypropylene, poly-1-butene, poly-4-methyl-1-pentene, polyvinyl chloride, polystyrene, acrylonitrile-butadiene-styrene copolymers, and polycarbonates obtained from 2, 2-bis (4-hydroxyphenyl) propane are still more preferable, and ethylene (co) polymers, propylene (co) polymers, or polycarbonates are particularly preferable.

When an ethylene (co) polymer or a propylene (co) polymer is used as the thermoplastic resin (a), odor, smoke generation, and the like are reduced during the molding of the conductive resin composition, and the working environment is easily improved. In addition, a good molded article with less scorch can be obtained. The ethylene (co) polymer is excellent in low-temperature characteristics and processability, and the propylene (co) polymer is excellent in heat resistance and rigidity. In addition, when polycarbonate is used, the conductive resin composition can be easily applied to various applications.

1-1-2 physical Properties of thermoplastic resin (A)

The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the thermoplastic resin (a) as measured by Gel Permeation Chromatography (GPC) is preferably 6.0 or less. The Mw/Mn is more preferably 4.0 or less, and still more preferably 3.0 or less. When the Mw/Mn is included in the above range, the low molecular weight component causing deterioration of physical properties is small, and thus the appearance, heat resistance and mechanical strength are excellent. Further, since there is little high molecular weight material which causes an increase in melt viscosity during kneading, processability is excellent. The weight average molecular weight (Mw) and the number average molecular weight (Mn) were both determined in terms of polystyrene.

The melting point (Tm) of the thermoplastic resin (A) as measured by a Differential Scanning Calorimeter (DSC) is preferably 250 ℃ or less, or no melting point is observed. When a melting point is observed, the upper limit of the melting point is more preferably 230 ℃, still more preferably 200 ℃, and particularly preferably 170 ℃. The lower limit of the melting point is preferably 50 ℃, more preferably 70 ℃, still more preferably 90 ℃, particularly preferably 130 ℃, and still more preferably 150 ℃. When the melting point is within the above range, fuming, odor, and the like are less likely to occur when the conductive resin composition is produced by melt kneading or when a molded article is produced by melt molding. Further, a molded article which is less likely to cause stickiness and has an excellent balance among heat resistance, mechanical strength, impact strength, and impact absorbability can be obtained.

The glass transition temperature (Tg) of the thermoplastic resin (A) as measured by a Differential Scanning Calorimeter (DSC) is preferably in the range of-140 ℃ to 50 ℃, more preferably-120 ℃ to 20 ℃, and still more preferably-100 ℃ to-10 ℃. When the glass transition temperature is within the above range, the obtained molded article has good balance among long-term stability, heat resistance, impact resistance and mechanical strength.

The density of the thermoplastic resin (A) is preferably 800 to 1800kg/m in accordance with ISO 1183 measured by a density gradient tube method³Within the range of (1). The lower limit of the density of the resin (A) is more preferably 810kg/m³More preferably 830kg/m³Particularly preferably 860kg/m³More preferably 900kg/m³. Further, the upper limit of the density of the resin (A) is more preferably 1300kg/m³More preferably 1290kg/m³Particularly preferably 1270kg/m³More preferably 1240kg/m³More preferably 1200kg/m³。

Thermoplastic resin (a) according to JIS K7171: the flexural modulus of elasticity measured at 94(ISO 178) is preferably 1 to 10000 MPa. When the flexural modulus is 500MPa or more, the flexural modulus is preferably 500 to 7000MPa, more preferably 700 to 5000MPa, particularly preferably 900 to 3000MPa, and further preferably 1000 to 2300 MPa. When the flexural modulus falls within the above range, the conductive resin composition is excellent in processability, and the molded article obtained therefrom is excellent in scratch resistance, heat resistance and mechanical strength. When the flexural modulus is less than 500MPa, the flexural modulus is preferably less than 300MPa, more preferably less than 100MPa, and still more preferably less than 50 MPa. When the flexural modulus is within the above range, a molded article having excellent impact absorbability, lightweight property, vibration resistance, vibration damping property, and sound insulation property can be obtained in addition to excellent flexibility. Further, a molded article having excellent design properties such as mold transferability and texture transferability and surface-gripping properties can be obtained.

1-2. carbon nanotubes (B)

The carbon nanotube may be a tubular carbon allotrope having an outer diameter (diameter) of 100nm or less. The outer diameter of the carbon nanotube (B) is more preferably 70nm or less, still more preferably 50nm or less, and particularly preferably 30nm or less. When the outer diameter of the carbon nanotube (B) is 100nm or less, the carbon nanotube (B) is likely to form a network structure in the conductive resin composition, and the conductivity is likely to be improved. On the other hand, when the outer diameter of the carbon nanotube (B) is 1nm or more, the carbon nanotube (B) tends to be easily dispersed.

The carbon nanotube (B) preferably has a fiber length of 3 to 500. mu.m, more preferably 5 to 300. mu.m, still more preferably 7 to 100. mu.m, and particularly preferably 9 to 50 μm. When the fiber length is 3 μm or more, the network structure of the carbon nanotubes (B) is easily formed sufficiently in the conductive resin composition, and the conductivity is easily made sufficient. On the other hand, when the fiber length is 500 μm or less, the dispersibility of the carbon nanotubes (B) is likely to be good. The outer diameter and fiber diameter of the carbon nanotube (B) were determined as follows: the length and outer diameter of 100 carbon nanotubes were measured by electron microscope observation (SEM), and the average value of the lengths and outer diameters was calculated.

The aspect ratio (fiber length/outer diameter) of the carbon nanotubes (B) is preferably 30 to 50000, more preferably 50 to 30000, and still more preferably 100 to 20000. When the aspect ratio of the carbon nanotube (B) is within this range, the dispersibility tends to be good.

The carbon nanotube (B) may be in a tubular shape, and may be in a needle shape, a cylindrical tubular shape, a fishbone shape (fishbone, cup-laminated type), a card shape (disk shape), a coil shape, or the like. The carbon nanotubes (B) can be formed into graphite whiskers, filamentous carbons, graphite fibers, carbon nanotubes, carbon fibrils, carbon nanofibers, and the like. Among the above, the carbon nanotube (B) is preferably cylindrical tube-shaped.

The cylindrical carbon nanotube (B) has a cylindrical structure formed by winding 1 or more layers of graphite. The cylindrical carbon nanotube (B) may be a single-layer carbon nanotube having a structure in which only 1 graphite layer is wound, or may be a multi-layer carbon nanotube in which 2 or more graphite layers are wound. In addition, these may be present in a mixture. Among them, the multilayered carbon nanotube is preferable in view of cost. The side surfaces of the carbon nanotubes may be amorphous structures other than graphite structures.

The carbon nanotube (B) may be subjected to various surface treatments, or may be a carbon nanotube derivative having a functional group such as a carboxyl group introduced to the surface thereof. Further, carbon nanotubes or the like containing an organic compound, a metal atom, fullerene, or the like may be used.

Among these, the carbon nanotube (B) preferably has a high carbon purity, and the amount of carbon in 100 mass% of the carbon nanotube (B) (hereinafter also referred to as "carbon purity") is preferably 85 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% or more. When the carbon purity is 85 mass% or more, the conductivity of the conductive resin composition is easily increased.

In the conductive resin composition, the carbon nanotubes (B) may be present in the form of secondary particles. The secondary particle shape may be a state in which carbon nanotubes as primary particles are intricately entangled, or a state in which linear carbon nanotubes are aggregated. Among these, from the viewpoint that the conductivity of the conductive resin composition is easily improved, a state in which linear carbon nanotubes are aggregated is preferable.

The carbon nanotubes (B) can be produced by a known method, for example, a laser ablation method, an arc discharge method, a thermal CVD method, a plasma CVD method, a combustion method, or the like. Among them, from the viewpoint of being able to efficiently produce high-purity carbon nanotubes without purification, a thermal CVD method using zeolite as a carrier of a catalyst and acetylene as a raw material is preferable.

The carbon nanotubes (B) may be commercially available. Examples of commercially available products include K-Nanos 100P, 100T, 200P (both manufactured by Kumho Petrochemical Co., Ltd.), FloTube9000, 9100 (both manufactured by CNano Co., Ltd.), NC7000 (manufactured by Nanocyl Co., Ltd.), and the like.

1-3 aromatic monomer modified polyolefin wax (C)

The aromatic monomer-modified polyolefin wax (C) is different from the thermoplastic resin (A).

As described above, when the carbon nanotubes (B) are merely blended in the thermoplastic resin (a) which becomes the matrix of the conductive resin composition, the dispersibility of the thermoplastic resin (a) and the carbon nanotubes (B) is poor, and the thermoplastic resin (a) and the carbon nanotubes (B) may not be uniformly kneaded. In particular, when the amount of the carbon nanotubes (B) blended with the thermoplastic resin (a) is large or the specific surface area of the carbon nanotubes (B) is large, the dispersion is often difficult due to an increase in viscosity during kneading. Therefore, when the conductive resin composition is molded, the processability is liable to be lowered or the uniformity of the molded article is liable to be insufficient. As a result, there are the following cases: insufficient acquisition of conductivity and problems in appearance of the resulting molded article; or insufficient heat resistance, mechanical strength, and flexibility (elongation).

In view of the above, it has been found from the studies of the inventors of the present application that when a thermoplastic resin (a) and carbon nanotubes (B) are kneaded, an aromatic monomer-modified polyolefin wax (C) obtained by modifying a polyolefin wax with an aromatic monomer is blended, whereby a conductive resin composition having excellent conductivity, appearance, heat resistance, mechanical strength, flexibility, and processability can be obtained.

Although the detailed mechanism is not clear, when an aromatic structure is present in the molecular chain of the aromatic monomer-modified polyolefin wax (C), the aromatic structure electrically interacts with the double bonds present in the molecule of the carbon nanotube (B), and the affinity thereof is improved. The aromatic monomer-modified polyolefin wax (C) has high affinity with various thermoplastic resins, and has good compatibility with the thermoplastic resin (a) when it is a polar resin, for example. Therefore, the carbon nanotubes (B) are easily uniformly dispersed in the thermoplastic resin (a), and friction during kneading is reduced. Further, it is presumed that the fluidity of the conductive resin composition is improved. In addition, the conductive resin composition has improved flowability, thereby improving processability and improving appearance of a molded article. Further, since the fluidity of the conductive resin composition is improved, the structure of the carbon nanotubes (B) or aggregates thereof is not easily broken, and thus sufficient conductivity is easily obtained.

1-3-1 physical Properties of aromatic monomer-modified polyolefin wax (C)

Among these, the aromatic monomer-modified polyolefin wax (C) preferably satisfies the following requirements (i) to (iv), and more preferably satisfies the requirements (v) and (vi).

(i) The aromatic monomer-modified polyolefin wax (C) preferably has a number average molecular weight (Mn) in terms of polystyrene, as measured by Gel Permeation Chromatography (GPC), in the range of 300 to 10000. The upper limit of the number average molecular weight (Mn) is more preferably 8000, still more preferably 5000, particularly preferably 4000, and still more preferably 3000. The lower limit of the number average molecular weight (Mn) is more preferably 200, still more preferably 300, particularly preferably 400, and still more preferably 500. When the number average molecular weight of the aromatic monomer-modified polyolefin wax (C) is within the above range, the dispersibility of the carbon nanotubes (B) in the conductive resin composition is improved, and the obtained molded article is excellent in conductivity, appearance and mechanical strength. In addition, the conductive resin composition has good processability.

When the polymerization temperature in the polymerization of the unmodified polyolefin wax described later is increased or the hydrogen concentration in the polymerization is increased, the number average molecular weight (Mn) of the aromatic monomer-modified polyolefin wax (C) is decreased. The amount of the catalyst used in the polymerization of the unmodified polyolefin wax may be adjusted, or may be adjusted by purification after the polymerization.

(ii) The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the aromatic monomer-modified polyolefin wax (C) as measured by Gel Permeation Chromatography (GPC) is preferably 9.0 or less. More preferably 8.0 or less, and still more preferably 7.0 or less. When Mw/Mn is included in the above range, the low molecular weight component causing a decrease in physical properties is small, and therefore, the appearance, heat resistance, mechanical strength, and the like of a molded article obtained from the conductive resin composition are good. The weight average molecular weight (Mw) is also a value in terms of polystyrene.

The Mw/Mn of the aromatic monomer-modified polyolefin wax (C) can be adjusted by the kind of catalyst used in the polymerization of the unmodified polyolefin wax, the polymerization temperature, and the like. In general, ziegler-natta catalysts and metallocene catalysts are used for polymerization of unmodified polyolefin waxes, and metallocene catalysts are preferably used in order to achieve a desired Mw/Mn. The Mw/Mn of the aromatic monomer-modified polyolefin wax (C) may be adjusted by purifying the unmodified polyolefin wax.

(iii) The aromatic monomer-modified polyolefin wax (C) preferably has a softening point, as measured in accordance with JIS K2207, in the range of 70 to 170 ℃. The upper limit of the softening point is more preferably 160 ℃, still more preferably 150 ℃, and particularly preferably 145 ℃. The lower limit is more preferably 80 ℃, still more preferably 90 ℃, particularly preferably 95 ℃, and particularly preferably 105 ℃. When the softening point is not more than the above upper limit, the processability of the conductive resin composition, and the appearance, heat resistance and mechanical strength of the molded article obtained therefrom become good. When the softening point is not lower than the above lower limit, bleeding of the aromatic monomer-modified polyolefin wax (C) in the obtained conductive resin composition is easily suppressed.

The softening point of the aromatic monomer-modified polyolefin wax (C) can be adjusted by the composition of the unmodified polyolefin wax. For example, in the case where the unmodified polyolefin wax described later is a copolymer of ethylene and an α -olefin, the softening point can be lowered by increasing the content of the α -olefin. The softening point may be adjusted by the kind of catalyst used in the preparation of the unmodified polyolefin wax, the polymerization temperature, or purification after polymerization.

(iv) The aromatic monomer-modified polyolefin wax (C) preferably has a density of 830 to 1200kg/m as measured by a density gradient tube method in accordance with JIS K7112³Within the range of (1). More preferably 860 to 1100kg/m³Further preferably 890E1000kg/m³. When the density of the aromatic monomer-modified polyolefin wax (C) is within the above range, the dispersibility of the carbon nanotubes (B) is improved, and the electrical conductivity, appearance and mechanical strength of the obtained molded article become good. In addition, the conductive resin composition has good processability.

The density of the aromatic monomer-modified polyolefin wax (C) can be adjusted by the composition of the unmodified polyolefin wax described later, the polymerization temperature at the time of polymerization, the hydrogen concentration, and the like.

(v) The aromatic monomer-modified polyolefin wax (C) preferably has a melt viscosity of 2000 mPas or less, more preferably 100 to 2000 mPas, even more preferably 200 to 1500 mPas, and even more preferably 300 to 1200 mPas, as measured at 140 ℃ in a B-type viscometer with a spindle rotation speed of 60 rpm. When the melt viscosity of the aromatic monomer-modified polyolefin wax (C) at 140 ℃ is within this range, the processability of the conductive resin composition is easily improved.

In addition, (vi) the viscosity-average molecular weight (Mv) of the aromatic monomer-modified polyolefin wax (C) obtained by measuring the intrinsic viscosity [ eta ] and substituting the intrinsic viscosity [ eta ] into the Mark-Kuhn-Houwink formula is preferably 350 to 2,000, more preferably 600 to 2,000, and still more preferably 700 to 1,800. When the viscosity average molecular weight (Mv) of the aromatic monomer-modified polyolefin wax (C) is decreased, the dispersibility of the carbon nanotubes (B) is likely to be improved, and the conductivity of the conductive resin composition is likely to be increased.

1-3-2 structure of aromatic monomer modified polyolefin wax (C) and manufacturing method thereof

The aromatic monomer-modified polyolefin wax (C) may be a compound obtained by modifying a polyolefin wax with an aromatic monomer, and is preferably an aromatic monomer-modified product of a homopolymer or a copolymer of ethylene and at least one kind selected from α -olefins having 3 to 12 carbon atoms. Particularly preferably a modified styrene copolymer of ethylene and at least one alpha-olefin selected from alpha-olefins having 3 to 12 carbon atoms.

The aromatic monomer-modified polyolefin wax (C) is obtained by modifying an unmodified propylene-based wax with an aromatic monomer (for example, styrene). First, an unmodified polyolefin wax and a method for producing the same will be described, and then, an aromatic monomer-modified polyolefin wax (C) obtained by modifying these with an aromatic monomer and a method for producing the same will be described.

(unmodified polyolefin wax)

As described above, the unmodified polyolefin wax is preferably a homopolymer or copolymer of ethylene and at least one selected from alpha-olefins having 3 to 12 carbon atoms. Examples of the α -olefin having 3 to 12 carbon atoms include propylene having 3 carbon atoms, 1-butene having 4 carbon atoms, 1-pentene having 5 carbon atoms, 1-hexene having 6 carbon atoms, 4-methyl-1-pentene, 1-octene having 8 carbon atoms, etc., and propylene, 1-butene, 1-hexene, 4-methyl-1-pentene are preferable. The unmodified polyolefin wax may be composed of 1 polymer alone, or may be a mixture of 2 or more polymers.

Hereinafter, polyethylene-based wax, polypropylene-based wax, and 4-methyl-1-pentene-based wax will be described as specific examples of the unmodified polyolefin wax, but the unmodified polyolefin wax is not limited thereto.

Polyethylene wax

When the unmodified polyolefin wax is a polyethylene wax, the polyethylene wax described in, for example, Japanese patent application laid-open No. 2009-144146 is preferable. The following description is briefly made.

The polyethylene wax may be, for example, an ethylene homopolymer or a copolymer of ethylene and an alpha-olefin having 3 to 12 carbon atoms. Specific examples of the ethylene homopolymer include high-density polyethylene wax, medium-density polyethylene wax, low-density polyethylene wax, and linear low-density polyethylene wax.

On the other hand, when the polyethylene wax is a copolymer of ethylene and an α -olefin having 3 to 12 carbon atoms, the amount (a) of the structural unit derived from ethylene is preferably 91.0 to 99.9 mol%, more preferably 93.0 to 99.9 mol%, even more preferably 95.0 to 99.9 mol%, and particularly preferably 95.0 to 99.0 mol%. On the other hand, the amount (b) of the structural unit derived from an α -olefin having 3 or more carbon atoms is preferably 0.1 to 9.0 mol%, more preferably 0.1 to 7.0 mol%, much more preferably 0.1 to 5.0 mol%, particularly preferably 1.0 to 5.0 mol%. Wherein (a) + (b) is 100 mol%. Structural unit of polyethylene waxIn a ratio of¹³And C-NMR spectrum was analyzed.

Examples of the α -olefin having 3 to 12 carbon atoms to be copolymerized with ethylene include linear or branched α -olefins such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, and 1-undecene, and propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferable, and α -olefins having 3 to 8 carbon atoms, propylene and 1-butene are particularly preferable, and propylene is more preferable. When ethylene is copolymerized with propylene and 1-butene, the aromatic monomer-modified polyolefin wax (C) tends to become hard and less sticky. Therefore, the surface properties of the molded article obtained are improved. Further, it is also preferable from the viewpoint of improving the mechanical strength and heat resistance of the obtained molded article. The reason is not clear, and the melting point can be effectively lowered by copolymerization of propylene and 1-butene in a small amount as compared with other α -olefins. Therefore, it is presumed that the crystallinity tends to be high when compared at the same melting point, which is a main cause. One kind of the α -olefin copolymerized with ethylene may be used alone, or two or more kinds may be used in combination.

The polyethylene wax is particularly suitably used when the thermoplastic resin (a) is a polyolefin resin. When these are combined, the compatibility between the thermoplastic resin (a) and the aromatic monomer-modified polyolefin wax (C) is improved, and the balance among the appearance, processability, mechanical strength, and heat resistance of the obtained molded article is improved. Further, a polyethylene wax can also be suitably used in the case where the thermoplastic resin (a) is a polycarbonate. In this case, due to the appropriate compatibility between the thermoplastic resin (a) (polycarbonate) and the polyethylene wax, the processability of the semiconductor resin composition, the releasability of the obtained molded article from the mold, the balance of mechanical strength, and the like are easily improved.

Polypropylene wax

The unmodified polyolefin wax may be a polypropylene-based wax. The polypropylene wax may be a propylene homopolymer, a copolymer of propylene and ethylene, or a copolymer of propylene and an alpha-olefin having 4 to 12 carbon atoms.

When propylene is copolymerized with ethylene, the amount of the structural unit derived from propylene is preferably 60 to 99.5 mol%. The amount of the structural unit derived from propylene is more preferably 80 to 99 mol%, still more preferably 90 to 98.5 mol%, and particularly preferably 95 to 98 mol%. When such a polypropylene-based wax is used, a molded article having an excellent balance among appearance, mechanical strength, and heat resistance can be easily obtained.

When the polypropylene-based wax is a compound obtained by copolymerizing propylene with an α -olefin having 4 to 12 carbon atoms, examples of the α -olefin having 4 to 12 carbon atoms include linear or branched α -olefins such as 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, and 1-undecene. Among these, 1-butene is particularly preferable.

When the polypropylene-based wax is a propylene/α -olefin copolymer, the amount (a') of the structural unit derived from propylene is preferably 60 to 90 mol%, more preferably 65 to 88 mol%, still more preferably 70 to 85 mol%, and particularly preferably 75 to 82 mol%. On the other hand, the amount (b') of the structural unit derived from an α -olefin having 4 or more carbon atoms is preferably 10 to 40 mol%, more preferably 12 to 35 mol%, still more preferably 15 to 30 mol%, and particularly preferably 18 to 25 mol%. Wherein (a ') + (b') -100 mol%.

Such polypropylene wax is particularly suitably used in the case where the thermoplastic resin (a) is a polypropylene-based resin. When these are combined, the compatibility between the thermoplastic resin (a) and the aromatic polymer-modified polyolefin wax (C) is improved, and the balance among the appearance, mechanical strength, and heat resistance of the obtained molded article is improved. In addition, the conductive resin composition has good processability.

4-methyl-1-pentene-based wax

As the unmodified polyolefin wax, a 4-methyl-1-pentene polymer described in Japanese patent laid-open publication No. 2015-028187, which is obtained by thermally decomposing a 4-methyl-1-pentene-. alpha. -olefin copolymer described in International publication No. 2011/055803, is preferable.

Preparation of unmodified polyolefin waxes

Unmodified polyalkenes as described aboveThe hydrocarbon wax may be obtained by directly polymerizing ethylene, propylene, 4-methyl-1-pentene, or the like, or may be obtained by preparing a (co) polymer having a high molecular weight and thermally decomposing the same. When thermal decomposition is performed, thermal decomposition is preferably performed at 300 to 450 ℃ for 5 minutes to 10 hours. In this case, unsaturated terminals are generated in the unmodified polyolefin wax. By using¹When the number of vinylene (unsaturated ends) groups per 1000 carbon atoms measured by H-NMR is 0.5 to 5, the affinity of the aromatic monomer-modified polyolefin wax (C) with the carbon nanotubes (B) is easily improved. The unmodified polyolefin wax may be purified by solvent separation based on the difference in solubility in a solvent, distillation, or the like.

On the other hand, when unmodified polyolefin wax is obtained by directly polymerizing ethylene, propylene, 4-methyl-1-pentene, or the like, the method is not limited. Various known production methods can be applied, and for example, ethylene or the like can be polymerized by using a ziegler/natta catalyst or a metallocene catalyst.

(aromatic monomer-modified polyolefin wax (C))

The aromatic monomer-modified polyolefin wax (C) is obtained by modifying the above-mentioned unmodified polyolefin wax with various aromatic monomers.

The aromatic monomer for modifying the unmodified polyolefin wax is preferably a compound having an aromatic ring and an unsaturated double bond. Specific examples thereof include styrene monomers such as styrene, α -methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, p-chlorostyrene, m-chlorostyrene and p-chlorostyrene; pyridine monomers such as 4-vinylpyridine, 2-vinylpyridine, 5-ethyl-2-vinylpyridine, 2-methyl-5-vinylpyridine and 2-isopropenylpyridine; quinoline monomers such as 2-vinylquinoline and 3-vinylisoquinoline; n-vinylcarbazole; n-vinyl pyrrolidone; and so on. Among these, styrene-based monomers are particularly preferable, and styrene is particularly preferable.

The amount of the structural unit derived from an aromatic monomer in the aromatic monomer-modified polyolefin wax (C) is preferably 5 to 95 parts by mass, more preferably 10 to 90 parts by mass, even more preferably 15 to 80 parts by mass, and particularly preferably 20 to 70 parts by mass, based on 100 parts by mass of the aromatic monomer-modified polyolefin wax (C). When the amount of the structural unit derived from an aromatic monomer in the aromatic monomer-modified polyolefin wax (C) is within the above range, the compatibility between the aromatic monomer-modified polyolefin wax (C) and the carbon nanotubes (B) is improved, and excessive interaction, which causes an increase in viscosity, is suppressed. Therefore, the processability of the conductive resin composition is improved, and the balance among the appearance, heat resistance and mechanical strength of the obtained molded article is improved. The amount of the structural unit derived from the aromatic monomer is calculated from the amount of the aromatic monomer added at the time of modification. In addition, it can also be determined by: the aromatic monomer-modified polyolefin wax (C) is extracted by Gel Permeation Chromatography (GPC) or the like, and the extracted aromatic monomer-modified polyolefin wax (C) is further analyzed by NMR or the like.

Preparation of aromatic monomer-modified polyolefin wax (C)

The method for producing the aromatic monomer-modified polyolefin wax (C), i.e., the method for modifying with an aromatic monomer, is not particularly limited. For example, the following method is possible: unmodified polyolefin wax and an aromatic monomer (for example, styrene) as raw materials are melt-kneaded in the presence of a polymerization initiator such as an organic peroxide. Further, the following method may be used: a polymerization initiator such as an organic peroxide is added to a solution obtained by dissolving an unmodified polyolefin wax and an aromatic monomer (for example, styrene) as raw materials in an organic solvent, and the mixture is melt-kneaded.

For the melt-kneading, known apparatuses such as an autoclave, a Henschel mixer (Henschel mixer), a V-blender (V-blender), a tumbler blender (tubbler blender), a ribbon blender (ribbon blender), a single-screw extruder, a multi-screw extruder, a kneader, and a banbury mixer can be used. Among these, when an apparatus having excellent batch-type melt kneading performance such as an autoclave is used, the aromatic monomer-modified polyolefin wax (C) in which the respective components are uniformly dispersed and reacted can be obtained. In addition, the batch type is preferable from the viewpoint that the retention time can be easily adjusted and the modification ratio and modification efficiency can be easily improved because a long retention time can be secured as compared with the continuous type.

The unmodified polyolefin wax may be modified with an aromatic monomer and then incorporated into a method for producing a conductive resin composition to be processed. For example, the aromatic monomer-modified polyolefin wax (C) may be processed into a powder, a sheet or a block. On the other hand, the aromatic monomer-modified polyolefin wax (C) may be dispersed or dissolved in water or an organic solvent. The method for dissolving or dispersing the aromatic monomer-modified polyolefin wax (C) in water or an organic solvent is not particularly limited. For example, the aromatic monomer-modified polyolefin wax (C) may be dissolved or dispersed by stirring. Alternatively, the mixture may be heated while stirring.

The aromatic monomer-modified polyolefin wax (C) may be dissolved or dispersed in water or an organic solvent and then precipitated to form fine particles. As a method for making the aromatic monomer-modified polyolefin wax (C) into fine particles, for example, the following methods are available. First, the solvent composition is adjusted so that the aromatic monomer-modified polyolefin wax (C) is precipitated at 60 to 100 ℃. Then, the mixture of the solvent and the aromatic monomer-modified polyolefin wax (C) is heated to dissolve or disperse the aromatic monomer-modified polyolefin wax (C) in the solvent. Then, the solution is cooled at an average cooling rate of 1 to 20 ℃/hr (preferably 2 to 10 ℃/hr) to precipitate the aromatic monomer-modified polyolefin wax (C). In addition, a poor solvent may be added later to further promote precipitation.

1-4 optional ingredients

The conductive resin composition of the present invention may contain optional components within a range not impairing the object and effect of the present invention. Examples of the optional components include flame retardants such as brominated bisphenols, brominated epoxy resins, brominated polystyrenes, brominated polycarbonates, triphenyl phosphate, phosphonic acid amides, red phosphorus, and the like; flame retardant aids such as antimony trioxide and sodium antimonate; heat stabilizers such as phosphates and phosphites; antioxidants such as hindered phenols; a heat-resistant agent; a weather resistant agent; a light stabilizer; a release agent; a flow modifier; a colorant; a lubricant; an antistatic agent; a nucleating agent; a plasticizer; a foaming agent; and so on.

The content of the optional component in the conductive resin composition is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less, based on 100 parts by mass of the total of the thermoplastic resin (a) and the carbon nanotubes (B).

2. Method for producing conductive resin composition

The conductive resin composition of the present invention can be produced by various methods. For example, the following method is possible: the thermoplastic resin (a), the carbon nanotubes (B), the aromatic monomer-modified polyolefin wax (C), and optional components may be mixed simultaneously or in any order with a tumbler (tub), a V-blender, a nauta mixer (nauta mixer), a banbury mixer, a mixing roll, a single-screw or twin-screw extruder, or the like.

In addition, the aromatic monomer-modified polyolefin wax (C) may be mixed with the thermoplastic resin (a) after being impregnated in the carbon nanotubes (B). The method for impregnating the carbon nanotubes (B) with the aromatic monomer-modified polyolefin wax (C) is not particularly limited. For example, the following methods can be mentioned: in a state where the melted aromatic monomer-modified polyolefin wax (C) is brought into contact with the carbon nanotubes (B), tension is applied to the carbon nanotubes (B) by a roller or a rod, or the carbon nanotubes (B) are repeatedly expanded and bundled, or pressure and vibration are applied to the carbon nanotubes (B). By these methods, the carbon nanotubes (B) can be impregnated with the aromatic monomer-modified polyolefin wax (C).

The impregnation method may be a method comprising: contacting the carbon nanotubes (B) with the surfaces of a plurality of heated rolls or rods, and contacting the carbon nanotubes (B) with the aromatic monomer-modified polyolefin wax (C) in a spread state; and so on. In particular, a method of impregnating the carbon nanotubes (B) with the aromatic monomer-modified polyolefin wax (C) using a drawing die, a drawing roll, a roll press, or a double belt press is preferable. In the present invention, since the aromatic monomer-modified polyolefin wax (C) is used, even if such impregnation work is performed, the aromatic monomer-modified polyolefin wax (C) is likely to be incorporated into the carbon nanotubes (B), and the work can be efficiently performed in a short time.

The conductive resin composition of the present invention can be produced through the following steps: preparing a master batch containing a thermoplastic resin (a), carbon nanotubes (B), and an aromatic monomer-modified polyolefin wax (C); and a step of melt-kneading the masterbatch, the thermoplastic resin (A), and, if necessary, the carbon nanotubes (B) or the aromatic monomer-modified polyolefin wax (C).

The master batch comprises thermoplastic resin (A), carbon nano tubes (B) and aromatic monomer modified polyolefin wax (C). In the conductive resin composition of the present invention, it may be difficult to uniformly disperse the carbon nanotubes (B) in the thermoplastic resin (a). Therefore, the thermoplastic resin (a) can be uniformly dispersed by preparing a master batch containing the thermoplastic resin (a), the carbon nanotubes (B), and the aromatic monomer-modified polyolefin wax (C), and further mixing the master batch with the thermoplastic resin (a). By preparing the master batch, the aromatic monomer-modified polyolefin wax (C) easily coats the carbon nanotubes (B), and the carbon nanotubes (B) are less likely to protrude from the surface of the conductive resin composition (and the molded article). Therefore, the surface gloss of the obtained molded article is improved, and the appearance and design of the molded article are improved. In addition, the aromatic monomer-modified polyolefin wax (C) is easily coated with the carbon nanotubes (B), and thus the mechanical strength and heat resistance are improved.

The content mass ratio of the carbon nanotubes (B) to the aromatic monomer-modified polyolefin wax (C) (carbon nanotubes (B)/aromatic monomer-modified polyolefin wax (C)) in the masterbatch is preferably 0.1 to 30, more preferably 1 to 25, and even more preferably 2 to 20. When the content mass ratio is 30 or less, the ratio of the carbon nanotubes (B) is not relatively excessively high, and therefore, the aggregated structure of the carbon nanotubes (B) is not easily broken at the time of producing the master batch. As a result, sufficient conductivity can be obtained when the conductive resin composition or the molded article is produced. When the content ratio is 0.1 or more, the ratio of the aromatic monomer-modified polyolefin wax (C) is not relatively high, and therefore the melt viscosity is not excessively low, and the masterbatch can be easily produced. Further, since the carbon nanotubes (B) do not become too small, high conductivity is easily obtained.

It is noted that the masterbatch may comprise the optional ingredients described previously. The masterbatch can be produced by mixing the respective components using a tumbler (tubbler), a V-type mixer, a nauta mixer, a banbury mixer, a mixing roll, a single-screw or twin-screw extruder, or the like.

3. Use of conductive resin composition

The conductive resin composition of the present invention is molded by, for example, injection molding, extrusion molding, compression molding, or the like, and used as a molded article. Among these molding methods, injection molding is preferable from the viewpoint of design and moldability.

The conductive resin composition of the present invention can be used for the production of molded articles for a wide range of applications from household products to industrial products. Examples of the applications include electric parts, electronic parts, automobile parts, mechanical device parts, food containers, films, sheets, fibers, and the like. More specifically, examples of the office and OA equipment include printers, personal computers, word processors, keyboards, PDAs (personal digital assistants), telephones, mobile phones, smartphones, tablet terminals, WiFi routers, facsimile machines, copiers, ECRs (electronic cash registers), calculators, electronic notepads, electronic dictionaries, cards, holders, stationery, and the like; household appliances such as washing machines, refrigerators, vacuum cleaners, microwave ovens, lighting fixtures, game machines, irons, and furnaces; AV equipment such as TVs, VTRs, video cameras, digital cameras, single-lens reflex cameras, portable audio terminals, radio cassette recorders, tape recorders, mini-discs, CD players, speakers, liquid crystal displays, and the like; electrical and electronic components such as connectors, relays, capacitors, switches, printed circuit boards, bobbins, semiconductor sealing materials, wires, cables, transformers, deflection coils, distribution boards, clocks, and communication devices.

Examples of the applications include automotive, vehicle, ship, aircraft, and building materials such as seats (fillers, fabrics), belts, roof coverings, movable roofs, armrests, door trims (door trims), rear luggage (trunk), carpets, mats, sun visors, wheel covers, tires, mattress covers, airbags, insulating materials, handles, handle tapes, wire-covering materials, electrical insulating materials, paints, coating materials, surface covering materials, flooring materials, corner walls (corner walls), decks (decks), covers, plywood, ceilings, partitions, side walls, carpets, wall paper, wall finishing materials, exterior finishing materials, interior finishing materials, roofing materials, sound insulation panels, heat insulation panels, window materials, and the like; articles for daily use and sports such as clothes, curtains, sheets, plywood, synthetic fiber boards, carpets, door mats, sheets, tubs, hoses, containers, glasses, bags, cases, goggles, skis, rackets, tents, musical instruments, and the like.

Examples of the applications include bottles for shampoos and detergents, seasoning bottles for edible oils and sauces, bottles for beverages such as mineral water and fruit juice, heat-resistant food containers such as lunch boxes and steamed egg custard bowls, tableware such as dishes and chopsticks, various other food containers, packaging films, and packaging bags.

Examples

The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

1. Preparation of the raw materials

[ thermoplastic resin (A) ]

As the thermoplastic resin (A), Ipiplon S-2000F (polycarbonate, MFR 10g/10 min, density 1200 kg/m) manufactured by Mitsubishi Engineering-Plastics Corporation was used³The flexural modulus of elasticity is 2300 MPa). These physical properties were measured under the following conditions.

＜MFR＞

Measured according to ISO 1133 at 300 ℃ under a load of 2.16 kg.

< Density >

Measured according to ISO 1183.

[ carbon nanotube (B) ]

K-Nanos 100P (bulk density 20-40 g/L, outer diameter 3-15 nm, length 10-50 μm) manufactured by Kumho Petrochemical company was used. These physical properties were measured under the following conditions.

< bulk Density >

Measured according to ASTM D1895.

< outer diameter and length >

The length and outer diameter of 100 carbon nanotubes were measured by electron microscope observation (SEM), and the average value thereof was used.

[ aromatic monomer-modified polyolefin wax (C) ]

As the aromatic monomer-modified polyolefin wax (C), waxes W1 to W5 shown in table 1 were used. The waxes W1 to W5 were produced by the production method described later. The results obtained by the following analysis are shown in table 1. In table 1 below, C2 represents ethylene and C3 represents propylene.

[ Table 1]

< composition >

The amounts of the respective structural units constituting the waxes W1 to W5 (composition ratio of ethylene to propylene) were measured under the following conditions and passed¹³And C-NMR spectrum was analyzed. The amount of styrene modification (the amount of structural units derived from styrene) is determined by the amount of charge.

·¹³Measurement conditions of C-NMR

The device comprises the following steps: model AVANCEIII cryo-500 NMR apparatus manufactured by Bruker Biospin

And (3) nuclear measurement:¹³C(125MHz)

measurement mode: monopulse proton broadband decoupling

Pulse width: 45 ° (5.00 μ sec)

Counting: 64k

Measurement range: 250ppm (-55 to 195ppm)

Repetition time: 5.5 seconds

Cumulative number of times: 128 times

And (3) determination of a solvent: ortho-dichlorobenzene/benzene-d₆(4/1 (volume ratio))

Sample concentration: 60mg/0.6mL

Measuring temperature: 120 deg.C

The window function: exponential type (exponenitial) (BF: 1.0Hz)

Chemical shift standard: delta signal 29.73ppm

< viscosity average molecular weight (Mv) >)

The viscosity average molecular weight was determined by measuring the intrinsic viscosity [ eta ] in decalin solvent at 135 ℃ using an Ubbelohde capillary viscometer and substituting the measured intrinsic viscosity [ eta ] into the Mark-Kuhn-Houwink equation.

< number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) >)

The number average molecular weight (Mn) and the weight average molecular weight (Mw) were determined by GPC measurement. The measurement was performed under the following conditions. Then, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were determined from a calibration curve using commercially available monodisperse standard polystyrene, and Mw/Mn was calculated.

The device comprises the following steps: gel permeation chromatograph Alliance GPC2000 type (manufactured by Waters corporation)

Solvent: ortho-dichlorobenzene

A chromatographic column: TSKgel GMH6-HT × 2, TSKgel GMH6-HTL column × 2 (all manufactured by Tosoh Co., Ltd.)

Flow rate: 1.0 ml/min

Sample preparation: 0.15mg/mL o-dichlorobenzene solution

Temperature: 140 deg.C

< Density >

Measured according to JIS K7112.

< softening point >

Measured according to JIS K2207.

< melt viscosity >

The melt viscosity was measured at 140 ℃ with a B-type viscometer and a spindle speed of 60 rpm.

< preparation of wax W1 >

(1) Preparation of the catalyst

In a glass autoclave having an internal volume of 1.5 liters, 25g of anhydrous magnesium chloride commercially available was suspended in 500ml of hexane. While maintaining this at 30 ℃, 92ml of ethanol was added dropwise over 1 hour with stirring, and the mixture was allowed to react for 1 hour. Then, 93ml of diethyl aluminum monochloride was added dropwise over 1 hour, and the reaction was further continued for 1 hour. Then, 90ml of titanium tetrachloride was added dropwise, and the reaction vessel was heated to 80 ℃ to react for 1 hour. The solid portion was then washed with hexane by decantation until no free titanium was detected. Then, the solid component (catalyst) was suspended in hexane, and the titanium concentration was quantified by titration, and used for the preparation of an unmodified polyolefin wax.

(2) Preparation of ethylene-propylene copolymer (unmodified polyolefin wax)

Into a 2 l stainless steel autoclave sufficiently purged with nitrogen, 930ml of hexane and 70ml of propylene were charged, and hydrogen was introduced until the internal volume became 20.0kg/cm²(gauge pressure). Then, the temperature in the system was raised to 170 ℃, and then a hexane suspension of 0.1 mmol of triethylaluminum, 0.4 mmol of ethylaluminum sesquichloride, and the catalyst obtained in the above method was introduced with ethylene under pressure so that the amount of titanium component became 0.008 mmol in terms of atom, thereby initiating polymerization.

Then, by continuously supplying ethylene alone, the total pressure was maintained at 40kg/cm²(gauge pressure), polymerization was carried out at 170 ℃ for 40 minutes. Then, a small amount of ethanol was added to the system to stop the polymerization, and unreacted ethylene and propylene were purged. The obtained polymer solution was dried overnight at 100 ℃ under reduced pressure to obtain an ethylene-propylene copolymer (unmodified polyolefin wax).

(3) Styrene modification of unmodified polyolefin waxes

200g of the unmodified polyolefin wax obtained by the above-mentioned method was charged into a glass reactor and melted at 160 ℃ under a nitrogen atmosphere. Then, 300g of styrene monomer and 30g of di-t-butyl peroxide (hereinafter, also referred to as "DTBPO") were continuously supplied to the reaction system (temperature: 160 ℃ C.) over 5 hours. Then, the reaction mixture was heated and reacted for 1 hour, and then, the molten state was maintained and degassed in a vacuum of 10mmHg for 0.5 hour to remove volatile components. The reaction was then cooled to give wax W1.

< preparation of wax W2 >

A wax W2 was obtained in the same manner as the aromatic monomer-modified polyolefin wax W1, except that the reaction time in the production of the unmodified polyolefin wax was changed.

< preparation of waxes W3-W5 >

Waxes W3 to W5 were obtained in the same manner as in the above-described aromatic monomer-modified polyolefin wax W1, except that the reaction time in the production of the unmodified polyolefin wax and the amount of the styrene monomer to be supplied in the modification of styrene were changed.

2. Preparation of electroconductive resin composition

[ example 1]

A co-rotating twin-screw extruder HK25D (manufactured by Parker:L/D41), 96.1 parts by mass of the thermoplastic resin (a), 3 parts by mass of the carbon nanotubes (B), and 0.9 part by mass of the aromatic monomer-modified polyolefin wax (C) (wax W1) were melt-kneaded, and extruded at a cylinder temperature of 280 ℃.

[ example 2]

A conductive resin composition was obtained in the same manner as in example 1, except that 93.5 parts by mass of the thermoplastic resin (a), 5 parts by mass of the carbon nanotubes (B), and 1.5 parts by mass of the aromatic monomer-modified polyolefin wax (C) (wax W1) were used.

[ example 3]

A conductive resin composition was obtained in the same manner as in example 1, except that 87 parts by mass of the thermoplastic resin (a), 10 parts by mass of the carbon nanotubes (B), and 3 parts by mass of the aromatic monomer-modified polyolefin wax (C) (wax W1) were used.

[ examples 4 to 7]

A conductive resin composition was obtained in the same manner as in example 2, except that the aromatic monomer-modified polyolefin wax (C) was changed to the one shown in table 2.

Comparative example 1

A conductive resin composition was obtained in the same manner as in example 1, except that 97 parts by mass of the thermoplastic resin (a) and 3 parts by mass of the carbon nanotubes (B) were used.

Comparative example 2

A conductive resin composition was obtained in the same manner as in example 1, except that 95 parts by mass of the thermoplastic resin (a) and 5 parts by mass of the carbon nanotubes (B) were used.

Comparative example 3

A conductive resin composition was obtained in the same manner as in example 1, except that 90 parts by mass of the thermoplastic resin (a) and 10 parts by mass of the carbon nanotubes (B) were used.

Comparative example 4

A conductive resin composition was obtained in the same manner as in example 2, except that the aromatic monomer-modified polyolefin wax (C) (wax W1) was changed to the unmodified polyolefin wax described above.

Comparative example 5

A conductive resin composition was obtained in the same manner as in example 2, except that the aromatic monomer-modified polyolefin wax (C) (wax W1) was changed to pentaerythritol stearate (hereinafter, also referred to as "PETS").

Comparative example 6

A conductive resin composition was obtained in the same manner as in example 2, except that the aromatic monomer-modified polyolefin wax (C) (wax W1) was changed to vinyl bis stearamide (hereinafter also referred to as "EBS").

3. Evaluation of conductive resin composition

The following evaluations were performed on the conductive resin compositions produced in the respective examples and comparative examples. The results are shown in Table 2. Fig. 1 is a graph showing the relationship between the molecular weight (Mv) of the aromatic monomer-modified polyolefin wax (C) of examples 2 and 4 to 7 and comparative example 4 and the conductivity (volume resistivity) of the conductive resin composition. Fig. 2 shows an electron micrograph showing the state of the carbon nanotubes (B) in the conductive resin compositions of examples 2,4, and 5 and comparative example 4.

< Torque >

In the examples and comparative examples described above, the torque at the time of pelletizing the conductive resin composition by the twin-screw extruder was measured, and the average value was calculated.

< resin pressure >

In the above examples and comparative examples, the resin pressure at the time of pelletizing the conductive resin composition by the twin-screw extruder was measured, and the average value was calculated.

< resin temperature >

In the above examples and comparative examples, the resin temperature in the vicinity of the die when the conductive resin composition was pelletized by the twin-screw extruder was measured.

< conductivity >

The pellets of the conductive resin compositions produced in the examples and comparative examples were dried at 120 ℃ for 8 hours, and then injection-molded using an injection molding Machine (NIIGATA NN100) under conditions of a cylinder temperature of 280 ℃, a screw rotation speed of 60rpm, an injection pressure of 130MPa, and a mold temperature of 90 ℃ to produce test pieces. The test piece was shaped in accordance with JIS K7194 (100X 3 mm). Then, using the test piece, the volume resistivity was measured in accordance with JIS K7194.

< tensile Strength, tensile elongation >

The pellets of the conductive resin compositions prepared in the examples and comparative examples were injection-molded in the same manner as in the conductivity test to prepare test pieces. The test piece was formed in a shape conforming to JIS K7161. Then, using an injection-molded test piece (ISO universal test piece), the tensile strength and the tensile elongation were measured under the conditions of an inter-chuck distance of 115mm and a test speed of 50 mm/min in accordance with JIS K7161.

< flexural Strength, flexural modulus of elasticity >

The pellets of the conductive resin compositions prepared in the examples and comparative examples were injection-molded in the same manner as in the conductivity test to prepare test pieces. The test piece was formed in a shape conforming to JIS K7171. The test piece (ISO universal test piece) was used to measure the bending strength and the bending elastic modulus under the conditions of a test speed of 2mm/min and a bending span of 64mm in accordance with JIS K7171.

[ Table 2]

As shown in table 2, the conductive resin compositions of examples 1 to 7 containing the aromatic monomer-modified polyolefin wax (C) were better in torque and resin temperature at the time of processing in examples 1 to 7 than the conductive resin compositions of comparative examples 1 to 3 containing no aromatic monomer-modified polyolefin wax (C). In addition, the volume resistivity is also low, and the conductivity is excellent. In addition, in examples 1 to 7, the mechanical properties were all good.

Further, it is understood that when the conductive resin compositions of examples 2 and 4 to 7 containing the aromatic monomer-modified polyolefin wax (C) (waxes W1 to W5) are compared with the conductive resin compositions of comparative examples 4 to 6 containing the unmodified polyolefin wax and the usual compatibilizer (PETS or EBS), the resin temperature rise during processing is less in examples 2 and 4 to 7. It is presumed that the structural units derived from the aromatic monomer in the aromatic monomer-modified polyolefin wax (C) (waxes W1 to W5) have high affinity with the carbon nanotubes (B), and the carbon nanotubes are well dispersed.

As shown in the graph of fig. 1, the following tendency exists: the lower the viscosity-average molecular weight (softening point) of the aromatic monomer-modified polyolefin wax (C) is, the higher the modification amount by the aromatic (styrene) is, the lower the volume resistivity value of the conductive resin composition becomes. As shown in fig. 2, the more the aromatic monomer-modified polyolefin wax (C) is modified by the aromatic group and the lower the viscosity-average molecular weight is, the better the dispersibility of the carbon nanotubes (B) in the conductive resin composition becomes, and a correlation is observed between the volume resistivity of the conductive resin composition and the dispersibility of the carbon nanotubes (B).

The present application claims the priority of Japanese patent application No. 2019-. The contents described in the specification and drawings of these applications are incorporated in the present specification.

Industrial applicability

The conductive resin composition of the present invention has both high conductivity and excellent processability. Therefore, the present invention can be applied to a wide range of uses from household goods to industrial goods.