JP2015054924A - Conductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive resin composition which allows a conductive film having excellent mechanical characteristics and moderate conductivity to be produced at a low cost.SOLUTION: The conductive resin composition of the present invention contains: a polyamide-imide resin obtained by reacting, in the presence of an amine-based catalyst, an acid component with a diisocyanate component which contains an isocyanate-modified polyol having a repeating unit derived from a polyester polyol containing a branched structure; and a conductive polymer.

Description

  The present invention relates to a conductive resin composition.

  Conventionally, various conductive belts or semiconductive belts used in electrophotographic image forming apparatuses such as copying machines and printing machines are often made of a material in which conductive carbon is dispersed in polyimide resin. Has been. However, a conductive belt or a semiconductive belt using a polyimide resin has a problem of high cost.

  A polyamide-imide resin is known as an alternative material for a high-cost polyimide resin. Polyamideimide resin has an advantage of low cost, but usually has a problem that mechanical properties are inferior to polyamideimide resin. Therefore, a belt using a polyamideimide resin is required to have improved mechanical properties.

JP 2009-166388 A JP 2010-139925 A

The objective of this invention is providing the conductive resin composition which can manufacture the electroconductive film which is excellent in mechanical characteristics and has moderate electroconductivity at low cost. More specifically, the desired conductivity (for example, the volume resistivity is 1 × 10 ⁸ Ω · cm to 1 × 10 ¹³ Ω ·, while including a polyamide-imide resin having a repeating unit derived from a polyester polyol containing a branched structure. An object of the present invention is to provide a conductive resin composition that can form a conductive film having a semiconductivity of cm) and excellent mechanical properties.

The conductive resin composition of the present invention is a polyamideimide obtained by reacting an acid component with a diisocyanate component containing an isocyanate-modified polyol having a repeating unit derived from a polyester polyol containing a branched structure in the presence of an amine catalyst. A resin and a conductive polymer are included.
In one embodiment, the amine-based catalyst is diazabicycloundenecene or triethylamine.
In one embodiment, the polyamideimide resin is obtained by reacting the following (A), (b1), (b2) and (b2 ′):
(A) Tricarboxylic anhydride (b1) Isocyanate-modified polyol (b2) 3,3′-dimethylbiphenyl-4,4′-diisocyanate (b2 ′) Aromatic diisocyanates other than (b2).
In one embodiment, the conductive polymer is conductive polyaniline.
According to another aspect of the present invention, a resin film is provided. This resin film is obtained by using the conductive resin composition.
According to still another aspect of the present invention, a seamless belt is provided. This seamless belt is composed of the resin film.

  The conductive resin composition of the present invention includes a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure, and the polyamideimide resin is obtained by polymerization in the presence of an amine catalyst. If such a polyamideimide resin is included, a conductive resin composition having desired conductivity can be obtained by adding a small amount of a conductive polymer. A resin film formed of such a conductive resin composition is excellent in mechanical properties (for example, folding resistance, flexibility, elastic modulus, strength, elongation). In addition, since the conductive film is based on polyamideimide resin and uses a small amount of conductive polymer, there is a merit in terms of cost.

A. Conductive resin composition The conductive resin composition of the present invention comprises a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure and a conductive polymer. Since the conductive resin composition of the present invention includes a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure, the resin film formed from the conductive resin composition has flexibility and folding resistance. Excellent.

A-1. Polyamideimide resin The polyamideimide resin can be synthesized by a diisocyanate method in which an acid component (A) and a diisocyanate component (B) are reacted in any appropriate solvent. In the present invention, an amine catalyst is used in the synthesis. The diisocyanate component (B) includes an isocyanate-modified polyol (b1) having a repeating unit derived from a polyester polyol containing a branched structure (details will be described later).

  The mixing ratio of the acid component (A) and the diisocyanate component (B) used for the synthesis of the polyamideimide resin is preferably 0.8 to 1.4 in terms of equivalent ratio (diisocyanate component / acid component), more preferably 0. 0.9 to 1.3, and more preferably 0.9 to 1.2.

  The number average molecular weight of the polyamideimide resin (a value measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve) is preferably 5,000 to 50,000, more preferably 10,000. 000 to 40,000, more preferably 15,000 to 35,000. When the number average molecular weight of the polyamideimide resin is outside the above range, film formation may be difficult, or the mechanical properties of the film obtained using the polyamideimide resin may be significantly reduced.

  The weight-average molecular weight of the polyamide-imide resin (value measured using a standard polystyrene calibration curve by gel permeation chromatography (GPC)) is preferably 5,000 to 200,000, more preferably 30, It is 000-200,000, More preferably, it is 50,000-150,000. When the weight average molecular weight of the polyamideimide resin is outside the above range, film formation may be difficult, or the mechanical properties of the film obtained using the polyamideimide resin may be significantly reduced.

A-1-1. Acid component (A)
The acid component (A) preferably contains a tricarboxylic acid anhydride. Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride and cyclohexanetricarboxylic acid anhydride. Trimellitic anhydride is preferable from the viewpoints of cost, reactivity, solubility, and the like. A tricarboxylic acid anhydride may be used independently and may be used in combination of 2 or more type.

  The acid component (A) may contain an acid component other than the tricarboxylic acid anhydride. Any appropriate acid component is used as the other acid component. For example, tetracarboxylic dianhydrides such as pyromellitic anhydride, biphenyltetracarboxylic dianhydride and oxydiphthalic anhydride; aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; alicyclic dicarboxylics such as cyclohexanedicarboxylic acid Acid; aliphatic dicarboxylic acids such as adipic acid and sebacic acid; Another acid component may be used independently and may be used in combination of 2 or more type.

  The molar ratio of the tricarboxylic acid anhydride to the acid component (A) (tricarboxylic acid anhydride / acid component) is preferably 0.5 to 1.0, more preferably 0.7 to 1.0.

A-1-2. Diisocyanate component (B)
The diisocyanate component (B) includes an isocyanate-modified polyol (b1) having a repeating unit derived from a polyester polyol containing a branched structure. If the isocyanate-modified polyol (b1) is used, a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure can be obtained. The polyamide-imide resin can form a resin film having a high tensile elastic modulus and excellent folding resistance. The isocyanate-modified polyol means a polyol having a terminal hydroxyl group modified with diisocyanate. The diisocyanate component (B) may further contain an aromatic diisocyanate (b2) and / or other diisocyanate (b3).

(Isocyanate-modified polyol (b1))
The isocyanate-modified polyol (b1) having a repeating unit derived from a polyester polyol containing a branched structure can be obtained by reacting a polyol (polyol containing a polyester polyol containing a branched structure) with a diisocyanate. The diisocyanate is preferably used in a molar equivalent of 2 times or more with respect to the polyol. Solvents used for the reaction include ketone solvents such as N-methyl-2-pyrrolidone, ester solvents, ether solvents, cellosolve solvents, aromatic hydrocarbon solvents, tetrahydrofuran, dioxane N, N-dimethylformamide. , N, N-dimethylacetamide, dimethyl sulfoxide and the like. The reaction temperature can be set to, for example, 100 ° C to 150 ° C. The reaction time can be set to 1 hour to 5 hours, for example.

  In one embodiment, it is possible to obtain a polyamide-imide resin capable of forming a film with higher elastic modulus and strength and capable of forming a film with further excellent mechanical properties. Only the polyester polyols contained are used. By using a polyester polyol containing a branched structure, it is presumed that the cohesive force between molecular chains is weakened and flexibility is imparted to the resulting polyamideimide resin. Therefore, it is considered that a polyamideimide resin capable of forming a film having further excellent mechanical properties can be obtained by using a polyester polyol having a branched structure.

  In another embodiment, in order to adjust properties other than mechanical properties of the obtained film, a polyester polyol containing a branched structure and a polyester polyol having a linear structure (not containing a branched structure) may be used in combination. When a polyester polyol having a branched structure and a polyester polyol having a linear structure are used in combination, the molar ratio between the polyester polyol having a branched structure and the polyester polyol having a linear structure (polyester polyol having a branched structure / polyester polyol having a linear structure) ) Is, for example, 9.9 / 0.1 to 5.0 / 5.0, and preferably 9.9 / 0.1 to 7.0 / 3.0.

  The polyester polyol containing a branched structure can be obtained, for example, by condensation polymerization of a dicarboxylic acid and a diol containing a branched structure, or by condensation polymerization of a dicarboxylic acid, a diol containing a branched structure, and a diol containing no branched structure. Can be. The polyester polyol having a linear structure can be obtained by condensation polymerization of a dicarboxylic acid and a diol not containing a branched structure.

  Any appropriate dicarboxylic acid can be used as the dicarboxylic acid. Examples thereof include aliphatic carboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic carboxylic acids such as terephthalic acid and isophthalic acid. Of these, adipic acid is preferred.

  Examples of the diol having a branched structure include 1,2-propylene glycol, 1,3-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, and 3-methyl-1,5-pentadiol. 2,2-dimethyl-1,3-propanediol, 2-methyl-1,8-octanediol, and the like. Of these, 3-methyl-1,5-pentadiol or 2-methyl-1,8-octanediol is preferable. Moreover, it is also preferable to use the polyester polyol obtained using neopentyl glycol. Examples of the diol not containing the branched structure include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, diethylene glycol and the like.

  Arbitrary appropriate groups are contained as group (side chain of polyester polyol) which constitutes the branched structure of polyester polyol containing the above-mentioned branched structure. For example, C1-C5 alkyl groups, such as a methyl group, etc. are mentioned. From the viewpoints of reactivity, handling properties, and cost, a polyester polyol containing an alkyl group having 1 to 5 carbon atoms as a branched structure is preferable. The polyester polyol containing the above group can be obtained, for example, by condensation polymerization of a diol containing this group and any appropriate dicarboxylic acid.

  The number average molecular weight of the polyester polyol containing the branched structure (a value measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve) can be set to any appropriate value. The number average molecular weight of the polyester polyol containing the branched structure is preferably 500 to 8,000, more preferably 1,000 to 4,000. When the number average molecular weight of the polyol is within the above range, a conductive resin composition capable of forming a resin film having excellent mechanical properties can be obtained. The number average molecular weight of the polyester polyol having a linear structure is also preferably in the above range.

  The hydroxyl value of the polyester polyol containing the branched structure is set to any appropriate value. The hydroxyl value of the polyester polyol is usually 15 mgKOH / g to 230 mgKOH / g, preferably 18 mgKOH / g to 140 mgKOH / g, more preferably 25 mgKOH / g to 115 mgKOH / g. When the hydroxyl value exceeds 230 mgKOH / g, the obtained film may not have sufficient breaking strength and breaking elongation. When the hydroxyl value is less than 15 mgKOH / g, the reactivity between the polyester polyol and the diisocyanate is lowered, and it may be difficult to obtain a desired polyamideimide resin. Further, the hydroxyl value of the polyester polyol having a linear structure is also preferably in the above range.

  The polyester polyol containing a branched structure preferably contains 50% by weight to 100% by weight of a repeating unit containing a branched structure. When the repeating unit containing a branched structure is 50% by weight to 100% by weight, the mechanical properties of the film obtained using the polyamideimide resin can be further improved.

  A commercial item may be used for the polyester polyol containing the said branched structure. Examples of commercially available polyester polyols having a branched structure include trade names “P-1010”, “P-2010”, “P-3010”, “P-4010”, “P-1020”, “P-” manufactured by Kuraray Co., Ltd. 2020 "," P-1030 "," P-2030 "," P-1050 "," P-2050 "," P-3050 "," P-4050 ", and the like. Commercially available products may also be used for the polyester polyol having a linear structure. Examples of commercially available polyester polyols that do not contain a branched structure include trade names “OD-X-102”, “OD-X-668”, and “OD-X-2068” manufactured by DIC.

  Arbitrary appropriate diisocyanate can be used as a diisocyanate made to react with the said polyol (The polyester polyol containing a branched structure, or the polyester polyol of a linear structure). For example, aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, tetramethylxylene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate And cycloaliphatic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate, and dicyclohexylmethane diisocyanate. These diisocyanates may be used alone or in combination of two or more.

  The number average molecular weight of the isocyanate-modified polyol (b1) (value measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve) is preferably 500 to 10,000, more preferably 1 , 000-9,500, more preferably 1,500-9,000. When the number average molecular weight of the isocyanate-modified polyol is less than 500, the elongation at break of the film containing the obtained polyamideimide resin may be lowered. When the number average molecular weight of the isocyanate-modified polyol exceeds 10,000, the reactivity of the diisocyanate decreases, and it tends to be difficult to increase the molecular weight of the polyamideimide resin.

  The molar ratio of the isocyanate-modified polyol (b1) to the diisocyanate component (B) (isocyanate-modified polyol (b1) / diisocyanate component (B)) is 0.005 to 0.2, more preferably 0.01 to 0. .1. When the molar ratio of the isocyanate-modified polyol to the diisocyanate component is less than 0.005, the effect of improving mechanical properties may not be sufficiently obtained. When the molar ratio of the isocyanate-modified polyol to the diisocyanate component exceeds 0.2, the properties of the polyamideimide resin may not be sufficiently exhibited.

(Aromatic diisocyanate (b2))
The diisocyanate component (B) preferably further contains an aromatic diisocyanate (b2), more preferably 3,3′-dimethylbiphenyl-4,4′-diisocyanate. If a diisocyanate component containing such an aromatic diisocyanate is used, a polyamide-imide resin capable of forming a highly elastic resin film can be synthesized. In the present specification, the aromatic diisocyanate means a diisocyanate having an aromatic group and having no polyol-derived structural unit.

  The molar ratio of the aromatic diisocyanate (b2) to the diisocyanate component (B) (aromatic diisocyanate / diisocyanate component) is preferably 0.5 to 0.995, more preferably 0.8 to 0.995. More preferably, it is 0.9-0.99.

  The molar ratio of 3,3′-dimethylbiphenyl-4,4′-diisocyanate to the aromatic diisocyanate (b2) is preferably 0.3 to 0.9, more preferably 0.5 to 0.8. is there. If the molar ratio of 3,3′-dimethylbiphenyl-4,4′-diisocyanate to aromatic diisocyanate is within the above range, a polyamideimide resin capable of forming a highly elastic resin film can be synthesized.

(Other diisocyanates (b3))
The other diisocyanate (b3) means a diisocyanate other than the isocyanate-modified polyol (b1) and the aromatic diisocyanate (b2). Examples of the other diisocyanate (b3) include aliphatic isocyanates such as hexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate, and dicyclohexylmethane diisocyanate. A diisocyanate may be used independently and may be used in combination of 2 or more type.

  Further, as the other diisocyanate (b3), an isocyanate-modified polyol other than the isocyanate-modified polyol (b1) having a repeating unit derived from the polyester polyol containing the above branched structure (that is, only a polyester polyol having a linear structure is used as the polyol). The obtained isocyanate-modified polyol) may be used.

  The molar ratio of the other diisocyanate (b3) to the diisocyanate component (B) (other diisocyanate (b3) / diisocyanate component (B)) is preferably 0.1 or less, more preferably 0.03 or less. .

A-1-3. Synthesis of Polyamideimide Resin The polyamideimide resin (polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure) is prepared by, for example, combining an acid component (A) and a diisocyanate component (B) in any appropriate solvent. It can be synthesized by reacting in the presence of an amine catalyst.

The present invention has been obtained by finding that a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure can form a resin film having excellent mechanical properties. Furthermore, the inventors of the present invention have a resin film formed from a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure, and has a desired conductivity (for example, a volume resistivity of 1 × 10 ⁸ Ω · It has been found that there is a tendency for the amount of conductive polymer required to obtain a semiconductive property of cm to 1 × 10 ¹³ Ω · cm to be large. The present invention can solve this problem.

  That is, in the present invention, by synthesizing a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure in the presence of an amine-based catalyst, the content of the conductive polymer is at least moderately conductive. A conductive resin composition that can be expressed can be obtained. If the conductive resin composition of the present invention having a low content of conductive polymer is used, it has excellent mechanical properties (for example, folding resistance, flexibility, elastic modulus, etc.) and small dimensional change due to moisture absorption. A resin film can be obtained.

  Examples of the amine catalyst include cyclic amines such as diazabicycloundenecene and diazabicyclononene; triethylamine; triethylenediamine and the like. Among them, preferred is cyclic amine or triethylamine, and more preferred is diazabicycloundenecene. If these amine catalysts are used, the effect that the content of the conductive polymer can be reduced becomes more remarkable.

  The addition amount of the amine catalyst is preferably 0.1 mol or more, more preferably 0.1 mol to 5 mol, and still more preferably 0.2 mol to 3 mol, with respect to a total of 100 mol of the diisocyanate component (B). Yes, particularly preferably 0.5 mol to 2 mol.

  Examples of the solvent used when the acid component (A) and the diisocyanate component (B) are reacted include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, and γ-butyrolactone.

  In the synthesis of the polyamideimide resin, the reaction temperature and reaction time may be set as appropriate. Reaction temperature becomes like this. Preferably it is 80 to 250 degreeC, More preferably, it is 85 to 150 degreeC, More preferably, it is 85 to 120 degreeC. For example, the reaction time can be set to 3 hours to 20 hours.

In one embodiment, a polyamidoimide resin is obtained by superposing | polymerizing using said acid component (A) and diisocyanate component (B) in the following combinations. The polyamideimide resin thus obtained has a good balance of mechanical properties and can form a resin film that is particularly excellent in folding resistance.
(A) Tricarboxylic acid anhydride (acid component)
(B1) Isocyanate-modified polyol (diisocyanate component)
(B2) 3,3′-dimethylbiphenyl-4,4′-diisocyanate (diisocyanate component)
(B2 ′) Aromatic diisocyanates other than (b2) (diisocyanate component)

A-2. Conductive polymer The conductive resin composition contains a conductive polymer.

  The content of the conductive polymer in the conductive resin composition can be set to any appropriate value as long as the effects of the present invention can be obtained according to desired electrical characteristics and mechanical characteristics. The content of the conductive polymer is preferably 5 parts by weight to 40 parts by weight, more preferably 8 parts by weight to 25 parts by weight, and particularly preferably 8 parts by weight to 100 parts by weight of the polyamideimide resin. 15 parts by weight, and most preferably 8 to 13 parts by weight. If it is such a range, the conductive resin film which has moderate electroconductivity can be obtained. The conductive resin composition of the present invention can exhibit appropriate conductivity even when the content of the conductive polymer is reduced in combination with a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure. . If the conductive resin composition of the present invention having a small content of conductive polymer is used, a resin film having excellent mechanical properties and small dimensional change due to moisture absorption can be obtained.

  Any appropriate polymer can be used as the conductive polymer. Examples of conductive polymers include polythiophene polymers, polyacetylene polymers, polyparaphenylene polymers, polyaniline polymers, polyparaphenylene vinylene polymers, polypyrrole polymers, polyphenylene polymers, and polyester polymers modified with acrylic polymers. Examples thereof include polymers.

  Preferably, a polyaniline polymer is used as the conductive polymer. The polyaniline-based polymer is a conductive polyaniline obtained by adding a dopant to polyaniline in an emeraldine base state having a reduced structural unit. Conductive polyaniline is preferred because of its excellent dispersibility in polyamideimide resin. If a conductive resin composition containing conductive polyaniline is used, a semiconductive film with uniform electrical resistance can be obtained.

  Preferably, the conductive polyaniline is obtained by adding an excess of dopant to the emeraldine-based polyaniline having a reduced structural unit in an amount that can be added to the polyaniline. Specifically, it is preferable to add more than 2 mol of dopant to 1 mol of the reduced structural unit of the polyaniline to the emeraldine-based polyaniline.

（式中、ｍは繰り返し単位中の酸化型構造単位のモル分率を示し、ｎは繰り返し単位中の還元型構造単位のモル分率を示し、ｍ＋ｎ＝１であり、ｍとｎの値は略等しい。） The polyaniline in the emeraldine base state (hereinafter also simply referred to as polyaniline) repeats a basic skeleton in which an oxidized structural unit and a reduced structural unit are present in substantially equal molar fractions as represented by the following formula (1). Have as a unit.

(In the formula, m represents the molar fraction of the oxidized structural unit in the repeating unit, n represents the molar fraction of the reduced structural unit in the repeating unit, m + n = 1, and the values of m and n are Approximately equal.)

  The method for producing the polyaniline is described in, for example, JP-A-3-28229, the description of which is incorporated herein by reference.

  Any appropriate dopant can be adopted as long as the dopant can impart conductivity by doping the polyaniline. The dopant is preferably a protonic acid. The proton acid may be an organic acid or an inorganic acid.

  The acid dissociation constant pKa value of the protonic acid is preferably 4.8 or less, more preferably 1 to 4.8. Examples of such a protonic acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, borohydrofluoric acid, phosphorous hydrofluoric acid and perchloric acid; organic acids having an acid solubility constant pKa value of 4.8 or less. Etc. When a protonic acid having a pKa value of 1 to 4.8 is used, a conductive resin composition having higher conductivity can be obtained as the pKa value is smaller, that is, the acidity is stronger. However, usually, when the pKa value is smaller than 1, the conductivity of the obtained conductive resin composition does not change beyond a certain level. Of course, if necessary, a protonic acid having a pKa value of 1 or less may be used.

  Examples of the organic acid include aliphatic organic acids such as organic carboxylic acids; aromatic organic acids such as phenols or araliphatic organic acids; alicyclic organic acids and the like. These organic acids may be monobasic acids or polybasic acids. The organic acid may have a substituent. Examples of the substituent include a sulfonic acid group, a sulfuric acid group, a hydroxyl group, a halogen group, a nitro group, a cyano group, and an amino group.

  Specific examples of the organic acid include acetic acid, butyric acid, octanoic acid, formic acid, oxalic acid, benzoic acid, picric acid, salicylic acid, 1,6-dinitro-4-chlorophenol, 2,6-dinitrophenol, 2,4 -Dinitrophenol, mandelic acid, phthalic acid, isophthalic acid, maleic acid, fumaric acid, malonic acid, tartaric acid, citric acid, lactic acid, succinic acid, α-alanine, β-alanine, glycine, glycolic acid, derivatives thereof, etc. Can be mentioned. In one embodiment, a sulfosuccinic acid derivative such as bis-2-ethylhexylsulfosuccinic acid may be preferably used from the viewpoint of handling properties when used in combination with a polyamideimide resin.

  Specific examples of the organic acid having a sulfonic acid group and / or a sulfuric acid group include amino naphthol sulfonic acid; metanilic acid; sulfanilic acid; allyl sulfonic acid; lauryl sulfuric acid; xylene sulfonic acid; chlorobenzene sulfonic acid; Acid, alkylsulfonic acid such as 1-propanesulfonic acid, benzenesulfonic acid, styrenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, butylbenzenesulfonic acid, pentylbenzenesulfonic acid, Hexylbenzenesulfonic acid, heptylbenzenesulfonic acid, octylbenzenesulfonic acid, nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid Alkyl benzene sulfonic acids such as pentadecyl benzene sulfonic acid and octadecyl benzene sulfonic acid; dialkyl benzene sulfonic acids such as diethyl benzene sulfonic acid; alkyl naphthalene sulfonic acids such as methyl naphthalene sulfonic acid, ethyl naphthalene sulfonic acid and propyl naphthalene sulfonic acid; dimethyl naphthalene sulfone Examples thereof include dialkylnaphthalenesulfonic acids such as acid and diethylnaphthalenesulfonic acid; trimethylnaphthalenesulfonic acid; triethylnaphthalenesulfonic acid; tripropylnaphthalenesulfonic acid; tributylnaphthalenesulfonic acid; camphorsulfonic acid; acrylamide-t-butylsulfonic acid and the like.

  As the organic acid, a polyfunctional organic sulfonic acid having two or more sulfonic acid groups in the molecule can also be used. Specific examples of the polyfunctional organic sulfonic acid include alkyl disulfonic acids such as ethanedisulfonic acid and propanedisulfonic acid; benzene disulfonic acid; naphthalene disulfonic acid; toluene disulfonic acid; ethylbenzene disulfonic acid, propylbenzene disulfonic acid, butylbenzene disulfonic acid. Alkylbenzene disulfonic acid such as dimethylbenzene disulfonic acid, dialkylbenzene disulfonic acid such as diethylbenzene disulfonic acid; alkyl naphthalene disulfonic acid such as methyl naphthalene disulfonic acid, ethyl naphthalene disulfonic acid, propyl naphthalene disulfonic acid; Dialkyl naphthalene sulfonic acid such as disulfonic acid, naphthalene trisulfonic acid; naphthalene tetrasulfonic acid Anthracene disulfonic acid; anthraquinone disulfonic acid; phenanthrene disulfonic acid; fluorenone disulfonic acid; carbazole disulfonic acid; diphenylmethane disulfonic acid; biphenyl disulfonic acid; terphenyl disulfonic acid; Examples include phenanthrenesulfonic acid-formalin condensate; anthracenesulfonic acid-formalin condensate; fluorenesulfonic acid-formalin condensate; carbazole sulfonic acid-formalin condensate. When the polyfunctional organic sulfonic acid has an aromatic ring, any appropriate position can be selected as the position of the sulfonic acid group in the aromatic ring.

  The organic acid may be a polymer acid. Specific examples of the polymer acid include polyvinyl sulfonic acid, polyvinyl sulfuric acid, polystyrene sulfonic acid, sulfonated styrene-butadiene copolymer, polyallyl sulfonic acid, polymethallyl sulfonic acid, poly-2-acrylamido-2-methylpropane. Examples include sulfonic acid, polyhalogenated acrylic acid, polyisoprene sulfonic acid, N-sulfoalkylated polyaniline, and nuclear sulfonated polyaniline. A fluorine-containing polymer known as naphthion (registered trademark of DuPont, USA) is also preferably used as the polymer acid.

  Among the organic acids exemplified above, an organic acid having a sulfonic acid group is preferable, more preferably dodecylbenzenesulfonic acid or camphorsulfonic acid, and still more preferably inexpensive and excellent in handleability. To dodecylbenzenesulfonic acid. If such an organic acid is used as a dopant, the effect of the present invention becomes more remarkable.

  In one embodiment, the conductive polyaniline is obtained by stirring and mixing the polyaniline and the dopant and heating the mixture. The stirring time is preferably 1 minute to 60 minutes, more preferably 2 minutes to 20 minutes, and further preferably 3 minutes to 10 minutes. The heating time is preferably 1 minute to 60 minutes, more preferably 2 minutes to 20 minutes, and even more preferably 3 minutes to 10 minutes. The heating temperature is preferably 120 ° C to 200 ° C, particularly preferably 140 ° C to 180 ° C.

  In another embodiment, the conductive polyaniline is obtained by heat-kneading the polyaniline and the dopant. It is considered that the conductive polyaniline obtained by heating and kneading is entangled in molecular chains. The conductive polyaniline obtained by heating and kneading is excellent in storage stability without being gelated even when dissolved in a polar solvent and stored for a long period of time (for example, 1 month or longer). Examples of the apparatus that can be used for the heat kneading include a closed kneading apparatus such as a Banbury mixer, a kneader, and a roll, or a batch kneading apparatus; a continuous kneading apparatus such as a single screw extruder and a twin screw extruder. .

  The kneading temperature in the heat kneading is preferably 120 ° C. to 200 ° C., particularly preferably 140 ° C. to 180 ° C. If the kneading temperature is in such a range, the molecular chains of the polyaniline are entangled, and as a result, a conductive polyaniline sufficiently doped with the dopant can be obtained, and further, it is difficult to gel in a polar solvent. It is estimated that a conductive resin composition can be obtained.

  The kneading time in the above heat kneading is preferably 1 minute to 60 minutes. When the kneading time is in such a range, it is possible to obtain a conductive polyaniline that is sufficiently doped with the protonic acid, and it is possible to obtain a conductive resin composition that hardly gels in a polar solvent.

  As described above, the addition amount of the dopant is preferably more than 2 mol with respect to 1 mol of the reduced structural unit of the polyaniline. The addition amount of the dopant is more preferably 3 mol to 6 mol with respect to 1 mol of the reduced structural unit of the polyaniline.

  Theoretically, 2 mol of dopant can be added to 1 mol of the reduced structural unit of the polyaniline. In the present invention, the conductive polyaniline can be sufficiently obtained by adding an excessive amount of dopant to the polyaniline beyond the theoretically possible amount. If a conductive resin composition sufficiently containing conductive polyaniline is used, a conductive material (for example, a conductive film) having excellent conductivity and flexibility can be obtained. On the other hand, even if the amount of dopant added is too large, the actual amount of dopant added to polyaniline does not exceed the theoretical value. When the amount of dopant added per mol of reduced structural unit of polyaniline is more than 6 mol, the conductive resin There exists a possibility that the residual dopant in a composition cannot be removed efficiently.

  By preparing as described above, most of the reduced structural unit of the polyaniline is doped (that is, most of the polyaniline is converted into conductive polyaniline). The ratio of the doped reduced structural unit is preferably 80 mol% or more, more preferably 90 mol% or more, based on the total of the doped reduced structural unit and the undoped reduced structural unit. More preferably, it is 98 mol% or more, and particularly preferably 100 mol%.

  Further, the ratio of the doped reduced structural unit is preferably 40 mol% or more, more preferably, based on the total of the oxidized structural unit and the reduced structural unit in the polyaniline (that is, before the addition of the dopant). It is 45 mol% or more, more preferably 49 mol% or more, and most preferably 50 mol%.

  It is preferable that the dopant added excessively as described above is removed by any appropriate method. If a conductive resin composition containing conductive polyaniline prepared by adding the above amount of dopant and substantially free of residual dopant is used, a resin film having both conductivity and mechanical strength is formed. can do. In the present specification, “substantially free of residual dopant” means that the content of residual dopant in the conductive resin composition is 10 parts by weight or less with respect to 100 parts by weight of conductive polyaniline. Say. The content of the dopant in the conductive resin composition is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, still more preferably 1 part by weight or less with respect to 100 parts by weight of the conductive polyaniline. is there. Most preferably, the conductive resin composition of the present invention contains no residual dopant.

  The removal of the residual dopant can be performed, for example, by adding a solvent capable of dissolving only the residual dopant to the mixture containing the conductive polyaniline and the residual dopant, washing the mixture, and then filtering. Examples of the solvent include water, methanol and the like.

  The conductive resin composition may contain any appropriate additive depending on the purpose and the like. Examples of the additive include a slidable filler, a heat conductive filler, a heat insulating filler, and an abrasion resistant filler. The additive may be added during the preparation of the conductive polyaniline, or may be added after the residual dopant removing step.

B. Resin Film The resin film of the present invention is formed using the conductive resin composition and includes the polyamideimide resin (polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure). Therefore, the resin film of the present invention has appropriate flexibility. In addition, since the resin film of the present invention exhibits conductivity with a small amount of a conductive polymer, it is excellent in other mechanical properties (for example, elastic modulus) and has a small dimensional change due to moisture absorption.

  The resin film of this invention can be obtained by apply | coating the said conductive resin composition to arbitrary appropriate base materials, producing a coating film, removing a solvent from this coating film, and heat-processing. Any appropriate method can be used as a method of applying the conductive resin composition to the substrate.

  As said base material, glass, a metal, a polymer film etc. are mentioned, for example. Moreover, the resin film for seamless belts can be produced by using a cylindrical metal mold | die as said base material. The resin film for seamless belt is prepared, for example, by supplying the conductive resin composition into a cylindrical mold to form a coating film on the inner surface of the mold, and then removing the solvent by heat treatment and drying. Is done.

  Any appropriate method is adopted as a method of forming the coating film when the resin film for the seamless belt is produced. For example, a method of supplying a coating liquid into a rotating mold and forming a uniform coating film by centrifugal force, inserting a nozzle along the inner surface of the mold, and discharging the coating liquid from the nozzle into the rotating mold. A method of applying a spiral while running a nozzle or a mold, or a method of running a traveling body (bullet shape, spherical shape) having a certain clearance between the mold after the spiral application is performed roughly After immersing the mold in the coating liquid to form a coating film on the inner surface, a method of forming a film with a cylindrical die or the like, after supplying the coating liquid to one end of the inner surface of the mold, between the mold Examples thereof include a method of traveling a traveling body (bullet shape, spherical shape) having a certain clearance.

  The temperature of the heat treatment is preferably 100 ° C to 300 ° C, more preferably 150 ° C to 250 ° C, and further preferably 150 ° C to 200 ° C. Since the conductive resin composition of the present invention containing a polyamideimide resin having a repeating unit derived from a polyester polyol containing a branched structure can be cured at a relatively low temperature, a conductive polymer obtained by dope (for example, the above conductive The dopant is difficult to desorb from (polyaniline). Therefore, if the conductive resin composition of the present invention is used, it is possible to obtain a resin film excellent in mechanical properties by suppressing adverse effects due to the dopant, specifically suppressing deterioration of the polyamideimide resin. The heat treatment time is preferably 10 minutes to 60 minutes.

  The thickness of the resin film can be set to any appropriate thickness depending on the application. Typically, it is 25 μm to 150 μm, and more preferably 50 μm to 100 μm.

  The folding resistance of the resin film according to MIT test according to JIS P8115 is preferably 3000 times or more, more preferably 3500 times or more, further preferably 4000 times or more, and particularly preferably 4000 times to 10,000. Times.

  The tensile elastic modulus at 25 ° C. of the resin film is preferably 1 GPa or more, more preferably 2 GPa or more, further preferably 2.6 GPa or more, particularly preferably 3 GPa to 20 GPa, and most preferably 3 .5 GPa to 20 GPa. A method for measuring the tensile modulus will be described later.

  The breaking strength at 25 ° C. of the resin film is preferably 50 MPa or more, more preferably 80 MPa or more, further preferably 100 MPa or more, further preferably 120 MPa or more, and particularly preferably 130 MPa or more, Most preferably, it is 130 MPa-500 MPa. A method for measuring the breaking strength will be described later.

  The elongation at break of the resin film at 25 ° C. is preferably 5% or more, more preferably 10% or more, still more preferably 20% to 60%, and particularly preferably 20% to 40%. A resin film having a break elongation in such a range is excellent in durability. The elongation at break can be measured, for example, at a tensile speed of 100 m / min using a predetermined tensile tester using a resin film punched with dumbbell No. 3 as a test piece.

  The hygroscopic expansion coefficient of the resin film is preferably 30 ppm / RH% or less, more preferably 25 ppm / RH% or less, and further preferably 22 ppm / RH% or less. A resin film having a hygroscopic expansion coefficient in such a range has a very small dimensional change due to moisture absorption, and is useful, for example, as an intermediate belt of a copying machine. The smaller the hygroscopic expansion coefficient of the resin film, the better. However, the lower limit is usually 5 ppm / RH% or more. A method for measuring the hygroscopic expansion coefficient will be described later.

The surface resistivity (ρs) of the resin film can be set to any appropriate value depending on the application. The surface resistivity (ρs) of the resin film is, for example, 1 × 10 ⁸ Ω / □ to 1 × 10 ¹³ Ω / □, preferably 1 × 10 ⁸ Ω / □ to 1 × 10 ¹² Ω / □. is there. The volume resistivity of the seamless belt is, for example, 1 × 10 ⁸ Ω · cm to 1 × 10 ¹³ Ω · cm, preferably 1 × 10 ⁸ Ω · cm to 1 × 10 ¹² Ω · cm. .

C. Seamless belt The seamless belt of the present invention includes the resin film. According to the present invention, a resin film having excellent mechanical properties can be provided. Therefore, the resin film of the present invention can be used particularly suitably for applications that require excellent mechanical properties. Therefore, the seamless belt of the present invention can be suitably used for applications requiring excellent mechanical properties such as seamless belts for printing presses and the like. The seamless belt of the present invention may include any other layer other than the resin film, depending on the application.

  Examples of the optional other layer include a thin layer of an inorganic metal oxide for imparting abrasion resistance, or a layer containing a fluororesin powder or a ceramic powder for adjusting slipperiness. Moreover, when using a seamless belt as a release belt, the release layer which consists of a fluororesin or silicone rubber etc. is mentioned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples at all.

[Example 1]
(Preparation of polyamideimide resin)
Polyester polyol containing a branched structure in a four-necked flask equipped with a mechanical stirrer with a stirring blade and a cooling tube (manufactured by Kuraray Co., Ltd., trade name: P-4010, number average molecular weight: 4000, hydroxyl value: 28.6 mgKOH / g) 117.7 g (0.03 mol) and 4,4′-diphenylmethane diisocyanate (MDI) 15.0 g (0.06 mol) were charged, and the mixture was heated and stirred at a polymerization temperature of 90 ° C. for 3 hours under a nitrogen stream. A reaction solution 1 containing a polyester polyol having a hydroxyl group modified with diisocyanate was obtained.
In the obtained reaction solution 1, 466.9 g (2.43 mol) of trimellitic anhydride, 475.7 g (1.80 mol) of 3,3′-dimethylbiphenyl-4,4′-diisocyanate (TODI) and , 62.5 g (0.65 mol) of MDI and 1535.8 g of NMP were charged, and the temperature was raised to 90 ° C. over 30 minutes. Next, 3.8 g of diazabicycloundenecene (DBU) was added as a polymerization catalyst and reacted for 5 hours while maintaining 90 ° C. Thereafter, NMP was further added so that the solid content concentration was 25% by weight, and a varnish containing a polyamideimide resin was obtained. The weight average molecular weight of the polyamideimide resin by gel permeation chromatography (solvent: N, N-dimethylformamide (DMF)) was 120,000.
(Preparation of conductive polymer solution)
1 mol of aniline, 1 mol of sodium bis-2-ethylhexyl sulfosuccinate, and 1800 ml of a mixed solvent of 1N hydrochloric acid and toluene (hydrochloric acid / toluene = 3/1) were placed in a flask while controlling at 5 ° C. while adding 1.2 mol of ammonium persulfate. Was added dropwise over 1 hour and allowed to react for 18 hours. Thereafter, the reaction solution was allowed to stand, and the aqueous phase side separated into two layers was removed. The obtained organic phase was washed with ion exchange water. Toluene was removed by reducing the pressure of this solution with an evaporator to obtain a complex of polyaniline and bis-2-ethylhexylsulfosuccinic acid (conductive polyaniline). The obtained conductive polymer and NMP were mixed and stirred at room temperature for 3 hours. The amount of the conductive polymer was 5 parts by weight with respect to 100 parts by weight of the total amount of the conductive polymer and NMP. Thereafter, the obtained solution was filtered through 800 mesh to obtain a conductive polymer solution.
(Preparation of conductive resin composition)
The varnish containing the polyamideimide resin and the conductive polymer solution were mixed so that the conductive polymer was 13 parts by weight with respect to 100 parts by weight of the polyamideimide solid content, and stirred at room temperature for 1 hour.
(Preparation of seamless belt)
The conductive resin composition was applied to the inner surface of a cylindrical mold (made of SUS) having an inner diameter of 300 mm and a length of 900 mm using a dispenser, and rotated at 1500 rpm for 10 minutes to form a coating layer having a uniform thickness. Next, as initial drying, hot air at 80 ° C. was applied for 30 minutes from the outside of the mold while rotating at 20 rpm. Next, the temperature was raised to 200 ° C., held at that temperature for 30 minutes, and then cooled to dry the coating layer to obtain a seamless belt (thickness: 80 μm).

[Comparative Example 1]
A varnish of polyamideimide resin was obtained in the same manner as in Example 1 except that the polymerization catalyst was not added and the polymerization temperature was set to 140 ° C at the time of preparation of the polyamideimide resin. The weight average molecular weight of the polyamideimide resin by gel permeation chromatography (solvent: DMF) was 89,000.
A conductive resin composition was prepared in the same manner as in Example 1 except that the varnish of polyamideimide resin thus obtained was used, and a seamless belt was obtained.

[Reference Example 1]
A varnish of polyamideimide resin was obtained in the same manner as in Example 1 except that the polymerization catalyst was not added and the polymerization temperature was set to 140 ° C at the time of preparation of the polyamideimide resin.
A conductive resin composition was prepared in the same manner as in Example 1, except that the polyamideimide resin varnish thus obtained was used and the addition amount of the conductive polymer was 13 parts by weight. I got a seamless belt.

[Evaluation]
The seamless belts obtained in Examples, Comparative Examples and Reference Examples were subjected to the following evaluation. The results are shown in Table 1.
(1) Surface resistivity Using Hiresta UP MCP-HT450 (manufactured by Mitsubishi Chemical Co., Ltd., probe: URS), the surface resistivity was measured under an applied voltage of 500 V / 10 seconds in an environment of 25 ° C./60% RH. It was measured. The measurement results are shown in Table 1 as common logarithmic values.
(2) Tensile modulus and breaking strength A film obtained by punching the obtained seamless belt with dumbbell No. 3 was used as a test piece. Using a Tensilon universal testing machine (manufactured by Toyo Baldwin), the tensile modulus and breaking strength were measured at a tensile speed of 100 m / min.
(3) Folding resistance A 15 mm × 110 mm film test piece was cut out from the obtained seamless belt. Using a tester industry folding resistance tester, the folding strength (MIT folding strength) was evaluated according to JIS-P8115 (2001) (load: 9.8 N). The number of times until the test piece broke after the start of the test was defined as the number of folding times.
(4) Hygroscopic expansion coefficient A film-like test piece of 25 mm x 4 mm was cut out from the obtained seamless belt. Using a trade name “TMA4000SA” manufactured by Bruker AXS Co., Ltd., the dimensional change with respect to the initial length was measured under the following conditions.
Measurement mode: Pull method Distance between chucks: 20 mm
Tensile load: 30g
Measurement temperature: 30 ° C
Measurement humidity: 20% → 80%

  As is clear from Example 1, the conductive resin composition of the present invention has a small amount of conductive polymer added, and if this composition is used, a seamless belt having excellent conductivity and excellent mechanical properties can be obtained. Can do. On the other hand, in a resin composition containing a polyamideimide resin obtained by polymerization without using an amine catalyst, appropriate conductivity cannot be obtained unless the addition amount of the conductive polymer is increased (Comparative Example 1). Reference Example 1). Further, in Reference Example 1 in which the amount of conductive polymer added is large, only a seamless belt having poor mechanical properties can be obtained.

  The conductive resin composition of the present invention can provide a film having excellent mechanical properties. Therefore, it can be particularly suitably used for a seamless belt represented by an intermediate transfer belt, a fixing belt, a conveying belt, etc. used in a copying machine or the like that requires excellent mechanical characteristics.

Claims (6)

A polyamideimide resin obtained by reacting an acid component with a diisocyanate component containing an isocyanate-modified polyol having a repeating unit derived from a polyester polyol containing a branched structure in the presence of an amine catalyst;
A conductive polymer,
Conductive resin composition.   The conductive resin composition according to claim 1, wherein the amine catalyst is diazabicycloundenecene or triethylamine. The conductive resin composition according to claim 1 or 2, wherein the polyamideimide resin is obtained by reacting the following (A), (b1), (b2), and (b2 '):
(A) Tricarboxylic acid anhydride (b1) Isocyanate-modified polyol (b2) 3,3′-dimethylbiphenyl-4,4′-diisocyanate (b2 ′) Aromatic diisocyanates other than (b2)   The conductive resin composition according to claim 1, wherein the conductive polymer is a conductive polyaniline.   A resin film obtained by using the conductive resin composition according to claim 1. A seamless belt comprising the resin film according to claim 5.