JP2015199858A - Polyamideimide resin and seamless belt using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamideimide resin which is excellent in low water absorption and solvent solubility and useful for a seamless belt for an electrophotographic apparatus or the like without impairing heat resistance (glass transition temperature) or mechanical properties (tensile strength and tear strength).SOLUTION: There is provided a polyamideimide resin containing 10 to 90 mol% of a constitutional unit represented by the following formula (1) in the polyamideimide resin. (where, Rrepresents an alkyl group having 1 to 5 carbon atoms or -SO-; Rand Rmay be the same or different and each represents hydrogen, a halogen atom, an aryl group or an alkyl group having 1 to 3 carbon atoms, provided that when Ris SO-, Rand Rare not present; and Rrepresents an aryl group which may have a substituent.)

Description

  The present invention relates to a novel polyamideimide resin and its application. In particular, polyamideimide resin is excellent in low water absorption and solvent solubility without impairing heat resistance (glass transition temperature) and mechanical properties (tensile strength, tear strength), and useful for conductive seamless belts for electrophotographic equipment. About.

Polyamideimide resins are generally widely used as coating agents for various substrates because they are generally excellent in heat resistance, chemical resistance, and solvent resistance. For example, they are used as varnishes for enameled wires and heat resistant paints. However, conventional polyamideimide resins are poor in workability such as varnish is likely to absorb moisture and solidify because it is dissolved in high boiling point amide solvents such as N-methyl-2-pyrrolidone and N, N-dimethylacetamide. In order to develop the original characteristics, it is necessary to heat at a high temperature of 250 ° C. or higher, and the use is limited because the polyamideimide resin itself is hard and brittle.

  Conventionally, polyamide-imide resins have been studied for conductive seamless belts for toner transfer and paper transport in electrophotographic copying machines and laser printers. For example, a cross-linking agent is added to make up for insufficient strength (Patent Document 1), a solvent is left to improve hard and brittle defects (Patent Document 2), and fragility and dimensional stability during moisture absorption are improved simultaneously. In order to achieve this, it has been studied to copolymerize silicone (Patent Document 3) or introduce an ionic group (Patent Document 4). However, the method of adding a crosslinking agent and introducing a crosslinked structure increases the brittleness, while the method of leaving a solvent decreases the creep characteristics against repeated loads, and when silicone is copolymerized, it is expensive and has electrical characteristics. There are problems such as variations, and the introduction of an ionic group has a problem in that, for example, the water absorption is increased, resulting in a decrease in dimensional stability during moisture absorption.

  On the other hand, when a polyamideimide resin is polymerized in an amide solvent having high hygroscopicity such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide, the polymerization solution is molded as it is by a coating method, a spray method, a dipping method, or the like. As a result, there is a problem that handling workability is poor, such as absorption of moisture in the air to change the flow characteristics or partial solidification. On the other hand, a method of polymerizing with γ-butyrolactone having a low hygroscopic property or further replacing the solvent with a low boiling point solvent has been proposed (Patent Document 5).

JP 2001-97519 A JP 2000-313071 A JP-A-2005-290019 JP 2005-255862 A Japanese Patent No. 3446845

  However, since raw materials that can be polymerized by this method are limited, the polyamide-imide resin obtained by this method has significantly reduced heat resistance (glass transition temperature), flame retardancy, and mechanical properties. It was not applicable to conductive seamless belts for laser printers.

The present invention incorporates a novel polyamideimide resin excellent in low water absorption and solvent solubility without impairing heat resistance (glass transition temperature) and mechanical properties (tensile strength, tear strength) and an antistatic agent. It is an object of the present invention to provide an electrically conductive composition and an electroconductive seamless belt of an electrophotographic copying machine and a laser printer molded using the same.

In view of the situation as described above, the present inventors diligently, researched, and studied, and as a result, introduced the specific structure into the polyamide-imide resin to overcome the above problems and arrive at the present invention.
That is, the present invention is as follows.

Polyamideimide resin containing 10 to 90 mol% of a structural unit represented by the following general formula (1).
(In the general formula (1), R ₁ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ —. R ₂ and R ₃ may be the same or different, and may be hydrogen, halogen atom, aryl group or Represents an alkyl group having 1 to 3 carbon atoms, provided that when R ₁ is —SO ₂ —, R ₄ represents an aryl group which may have a substituent.

In a polyamideimide resin, comprising a structural unit derived from trimellitic anhydride, a structural unit derived from a polycarboxylic dianhydride represented by the following general formula (2), and a structural unit derived from diisocyanate or diamine When the total of the structural units derived from the acid component is 100 mol%, the structural unit derived from the polycarboxylic dianhydride represented by the general formula (2) is preferably 10 to 90 mol%.
(In the general formula (2), R ₅ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ —. R ₆ and R ₇ may be the same or different, and may be a hydrogen atom, a halogen atom, an aryl group or Represents an alkyl group having 1 to 3 carbon atoms, provided that R ₅ is —SO ₂ —.

  The structural unit derived from diisocyanate or diamine is preferably a structural unit derived from aromatic diisocyanate or aromatic diamine.

  A conductive composition containing the polyamideimide resin and an antistatic agent.

  It is preferable that the antistatic agent is carbon black, and the compounding ratio (mass ratio [carbon black / polyamideimide resin]) of the polyamideimide resin and carbon black is 5/95 to 30/70.

  A seamless belt containing the conductive resin composition.

The present invention can provide a novel polyamide-imide resin excellent in low water absorption and solvent solubility without impairing heat resistance (glass transition temperature) and mechanical properties (tensile strength, tear strength).

In the present invention, by introducing a specific structure, a novel low water absorption and solvent solubility without deteriorating the original heat resistance (glass transition temperature) and mechanical properties (tensile strength, tear strength) of the polyamide-imide resin. It is possible to provide a polyamideimide resin and a method for producing the same, a conductive composition in which an antistatic agent is blended therewith, and a conductive seamless belt of an electrophotographic copying machine or a laser printer molded using the same. Furthermore, it is possible to provide a polyamide-imide resin which is soluble in a solvent such as γ-butyrolactone having a low hygroscopic property and useful for a seamless transfer belt of an electrophotographic copying machine or a laser printer, and a method for producing the same.

  Below, the polyamideimide resin of this invention, the manufacturing method of a polyamideimide resin, and the seamless belt using the polyamideimide resin of this invention are demonstrated.

<Polyamideimide resin>
The polyamideimide resin of the present invention is characterized by containing 10 to 90 mol% of the structural unit represented by the general formula (1) when the total structural unit in the polyamideimide resin is 100 mol%. By containing the structural unit of the general formula (1), a flexible and tough film is formed without impairing the inherent heat resistance and wear resistance of the polyamide-imide resin, and the water absorption and moisture absorption properties are reduced and flame retardant. Will improve. Furthermore, the polymerization can be performed not only with an amide solvent such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide but also with a low hygroscopic solvent such as γ-butyrolactone.

In General Formula (1), R ₁ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ — (sulfone). The alkyl group having 1 to 5 carbon atoms may be linear or branched, and the preferred carbon number is 2 or more, more preferably 3 or more, and preferably 4 or less. R ₂ and R ₃ each independently represents a hydrogen atom, a halogen atom, an aryl group, or an alkyl group having 1 to 3 carbon atoms. However, when R ₁ is sulfone, R ₂ and R ₃ are not present. The halogen atom is not particularly limited as long as it is fluorine, chlorine, bromine or iodine. When R ₂ and R ₃ are a plurality of halogen atoms, each may be one kind of halogen atom, and two or more kinds of halogen atoms It may be an atom. Industrially, it is preferably one type of halogen atom, and more preferably, both R ₂ and R ₃ are fluorine. The aryl group is not particularly limited, but a phenyl group which may have a substituent or a naphthyl group which may have a substituent is preferable, and a phenyl group is more preferable. The alkyl group having 1 to 3 carbon atoms may be linear or branched, and the preferred carbon number is 2 or more.

Preferable R ₁ is not particularly limited, and is a methylene group or sulfone, and preferable R ₂ and R ₃ are not particularly limited, but are hydrogen, a methyl group, a trifluoromethyl group, a benzyl group, or a phenyl group. A preferred embodiment obtained from R ₁ , R ₂ and R ₃ is not particularly limited, but is an isopropyl group, a hexafluoroisopropyl group, a diphenylisopropyl group, a diphenylmethylene group or an ethylene group, and more preferably an isopropyl group.

In general formula (1), R ₄ represents an aryl group which may have a substituent. The aryl group which may have a substituent is not particularly limited, but is preferably a phenyl group, a benzyl group, a tolyl group, a xylyl group or a naphthyl group, and more preferably a phenyl group.

  The structural unit represented by the general formula (1) in the polyamideimide resin of the present invention is preferably 10 mol% or more, more preferably 15 mol% or more, and more preferably 20 mol% or more. Further preferred. Moreover, it is preferable that it is 90 mol% or less, It is more preferable that it is 85 mol% or less, It is further more preferable that it is 80 mol% or less. If the amount is too small, the water absorption rate is large. If the amount is too large, the solvent solubility may be insufficient.

  It is also preferable to further contain a structural unit represented by the general formula (3). When the structural unit represented by the general formula (3) is contained, it is preferably 10 mol% or more, more preferably 15 mol% or more, and more preferably 20 mol% or more in the polyamideimide resin. Is more preferable. Moreover, it is preferable that it is 90 mol% or less, It is more preferable that it is 85 mol% or less, It is further more preferable that it is 80 mol% or less.

In general formula (3), R ₄ has the same meaning as described above.

Moreover, it is preferable to contain the structural unit derived from trimellitic anhydride, the structural unit derived from the polyhydric carboxylic dianhydride shown by the following General formula (2), and the structural unit derived from diisocyanate or diamine.
In General Formula (2), R ₅ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ — (sulfone). The alkyl group having 1 to 5 carbon atoms may be linear or branched, and the preferred carbon number is 2 or more, more preferably 3 or more, and preferably 4 or less. R ₆ and R ₇ each independently represent hydrogen, a halogen atom, an aryl group, or an alkyl group having 1 to 3 carbon atoms. However, when R ₅ is sulfone, R ₆ and R ₇ are not present. The halogen atom is not particularly limited as long as it is fluorine, chlorine, bromine or iodine. When R ₆ and R ₇ are a plurality of halogen atoms, each of them may be one type of halogen atom, or two or more types of halogens. It may be an atom. Industrially, it is preferably one type of halogen atom, and more preferably, both R ₆ and R ₇ are fluorine. The aryl group is not particularly limited, but a phenyl group which may have a substituent or a naphthyl group which may have a substituent is preferable, and a phenyl group is more preferable. The alkyl group having 1 to 3 carbon atoms may be linear or branched, and the preferred carbon number is 2 or more.

Preferable R ₅ is not particularly limited, and is a methylene group or sulfone, and preferable R ₆ and R ₇ are not particularly limited, but are hydrogen, a methyl group, a trifluoromethyl group, a benzyl group, or a phenyl group. A preferred embodiment obtained from R ₅ , R ₆ and R ₇ is not particularly limited, but is an isopropyl group, a hexafluoroisopropyl group, a diphenylisopropyl group, a diphenylmethylene group or an ethylene group, and more preferably an isopropyl group.

<Acid component of polyamideimide resin>
In the present invention, it is preferable that a part of the acid component contains a structural unit derived from trimellitic anhydride and a structural unit derived from the polyvalent carboxylic dianhydride represented by the general formula (2), more preferably It is copolymerized with the polyamide-imide resin. By introducing a structural unit derived from the polyvalent carboxylic acid dianhydride represented by the general formula (2) in an appropriate amount range, a flexible and tough film can be formed without impairing the inherent heat resistance and wear resistance of the polyamideimide resin. The water absorption and hygroscopicity are reduced and flame retardancy is improved. Furthermore, the polymerization can be performed not only with an amide solvent such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide but also with a low hygroscopic solvent such as γ-butyrolactone. The reason is that the polyvalent carboxylic acid dianhydride represented by the general formula (2) has a structure with excellent flexibility, a relatively large molecular weight, and is an acid anhydride. This is thought to be because the amount of binding decreases.

  The copolymerization amount of trimellitic anhydride is preferably 10 to 90 mol%, more preferably 15 to 85 mol%, and particularly preferably 20 to 80 mol% in the total acid component. If the copolymerization amount is less than 10 mol%, the solvent solubility may be insufficient, and conversely if it exceeds 90 mol%, the water absorption may be large.

  The copolymerization amount of the polyvalent carboxylic dianhydride represented by the general formula (2) is 10 to 90 mol% in the total acid component. Preferably it is 15-85 mol%, More preferably, it is 20-80 mol%. When this copolymerization amount is less than 10 mol%, the water absorption is large. Conversely, when it exceeds 90 mol%, the solvent solubility may be insufficient.

  The molar ratio of trimellitic anhydride and the polyvalent carboxylic dianhydride represented by the general formula (2) is preferably in the range of 20/80 to 80/20.

  Although it does not specifically limit as polyhydric carboxylic acid dianhydride shown by General formula (2), 4,4 '-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride, 4,4 specifically '-(4,4'-hexafluoroisopropylidenediphenoxy) bisphthalic dianhydride, 4,4'-(4,4'-diphenylisopropylidenediphenoxy) bisphthalic dianhydride, 4,4 '-( 4,4′-Ethylenediphenoxy) bisphthalic dianhydride, 4,4 ′-(4,4′-sulfonyldiphenoxy) bisphthalic dianhydride, and the like. Among these, low water absorption and solubility To 4,4 ′-(4,4′-isopropylidenediphenoxy) bisphthalic dianhydride (hereinafter also referred to as BISDA).

  In the present invention, in addition to trimellitic anhydride and the polyvalent carboxylic dianhydride represented by the general formula (2) as an acid component, the following polyvalent carboxylic acids or their anhydrides are impaired in the effect of the present invention. It can be used in a range that does not exist.

  Trifunctional or higher aromatic polyvalent carboxylic acids such as pyromellitic acid, ethylene glycol bis trimellitate, propylene glycol bis trimellitate, 1,4-butanediol bis trimellitate, polyethylene glycol bis trimellitate, etc. 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5, 8-naphthalenetetracarboxylic acid, 2,3,5,6-pyridinetetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 4 , 4′-oxydiphthalic acid, 1,1,1,3,3,3-hexafluoro-2- -Bis (2,3- or 3,4-dicarboxyphenyl) propane, 2,2-bis (2,3- or 3,4-dicarboxyphenyl) propane or anhydrides thereof, and the like Among them, pyromellitic acid, biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid or their anhydrides are preferable. These may be used alone or in combination.

As the aliphatic dicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecadioic acid, dodecanedioic acid, etc. have a branched structure. Include those having a hydrocarbon substituent on the dicarboxylic acid, such as 2-methylsuccinic acid.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and the like. These may be used alone or in combination.

In addition, aliphatic or alicyclic polycarboxylic acids or their anhydrides or alicyclic dicarboxylic acids can be used as other acid components within the range not impairing the effects of the present invention. For example, butane-1,2,3,4-tetracarboxylic acid, pentane-1,2,4,5-tetracarboxylic acid, cyclobutanetetracarboxylic acid, hexahydropyromellitic acid, cyclohex-1-ene-2,3 , 5,6-tetracarboxylic acid, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic acid, 1-ethylcyclohexane-1- (1,2), 3, 4-tetracarboxylic acid, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic acid, 1,3-dipropyl-1- (2,3), 3- (2,3) -tetra Carboxylic acid, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic acid, bicyclo (2.2.1) heptane-2,3,5,6-tetracarboxylic acid, 1,3-dipropylchlorohexane 1- (2,3), 3 (2,3) - tetracarboxylic acid, hexa hydro trimellitic acid or their anhydrides, cyclohexane dicarboxylic acids, such as dimer acid. These may be used alone or in combination.

In order not to impair the characteristics of the polyamideimide resin of the present invention, the copolymerization amount of the above-mentioned acid component other than trimellitic anhydride and the polyvalent carboxylic dianhydride represented by the general formula (2) 20 mol% or less is desirable and 10 mol% or less is more desirable.

<Diamine component of polyamideimide resin>
Examples of the diamine component of the polyamideimide resin of the present invention include diisocyanate or diamine. Although a diamine component is illustrated as a diisocyanate, the diamine corresponding to a diisocyanate may be sufficient.

  The diamine component of the polyamideimide resin of the present invention may be a diisocyanate or a diamine, preferably an aromatic diisocyanate or an aromatic diamine. Although illustrated as aromatic diisocyanate below, the aromatic diamine corresponding to aromatic diisocyanate may be sufficient.

  Examples of aromatic diisocyanates that can be used in the present invention include diphenylmethane-2,4′-diisocyanate, 3,2′- or 3,3′- or 4,2′- or 4,3′- or 5, 2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4 , 3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4 -Diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene -2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4 '-(2,2bis (4-phenoxyphenyl) ) Propane) Diisocyanate, 3,3'- or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3 '-Jimee Carboxymethyl biphenyl-4,4'-diisocyanate, 3,3'-diethoxy-4,4'-diisocyanate. Among these, diphenylmethane-4,4′-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 3,3′- in terms of low hygroscopicity, dimensional stability, cost and polymerizability. Dimethylbiphenyl-4,4′-diisocyanate and naphthalene-2,6-diisocyanate are preferable, and these may be used alone or in combination.

  As long as the effects of the present invention are not impaired, an aliphatic or alicyclic structure can be used as the diisocyanate component. For example, diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, etc., obtained by hydrogenating any of the components listed in the previous section.

  The logarithmic viscosity of the polyamideimide resin of the present invention is preferably 0.5 dl / g or more, more preferably 0.6 dl / g or more. Although the upper limit of the logarithmic viscosity of the polyamideimide resin is not particularly defined, it is preferably 3.0 dl / g or less in practice, and more preferably 2.5 dl / g or less from the viewpoint of workability. When the logarithmic viscosity is lower than 0.5 dl / g, for example, when a seamless belt described later is used, the belt may be deformed or broken during long-term use.

<Production method of polyamideimide resin>
Generally, the polyamideimide resin can be produced by an acid chloride method, a direct method, or a diisocyanate method, but the diisocyanate method is cheaper and industrially superior.

  Ordinary polyamide-imide resin is synthesized from an acid component and a diisocyanate or diamine component, and amide bonds and imide bonds are alternately repeated in the molecule to form a polymer. Is characterized by high strength and high strength. In order to improve the properties of the polyamide-imide resin, the ratio of amide bond to imide bond can be changed, aromaticity can be increased, or an aliphatic component can be introduced.

Below, although the diisocyanate method is demonstrated to an example about the manufacturing method of the polyamide-imide resin of this invention, this invention is not limited by this.
The polyamide-imide resin of the present invention is obtained by dissolving an acid component and an isocyanate component in a solvent, and heating and stirring at 60 ° C. to 200 ° C., preferably 80 ° C. to 150 ° C. At this time, the ratio (molar ratio) between the acid component and the isocyanate component is preferably in the range of 100: 91 to 100: 109. If it is out of this range, the molecular weight may not be sufficiently increased and the mechanical strength may be insufficient, or gelation may occur during polymerization.

  Examples of the solvent used for the polymerization of the polyamideimide resin of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, dimethylimidazolidinone, dimethyl sulfoxide, dimethylformamide, N-ethyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, cyclohexanone, cyclopentanone, tetrahydrofuran and the like can be mentioned. From the storage stability of the polymerization solution, handling workability and polymerizability, N-methyl-2-pyrrolidone or γ- Butyrolactone is preferred. Moreover, it can dilute with the solvent used for superposition | polymerization during superposition | polymerization and / or after superposition | polymerization, and / or another low boiling point solvent, and can adjust a non volatile matter concentration and solution viscosity.

  Low boiling solvents include aromatic solvents such as toluene and xylene, aliphatic solvents such as hexane, heptane and octane, alcoholic solvents such as methanol, ethanol, propyl alcohol and butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, Examples thereof include ketone solvents such as cyclopentanone and cyclohexanone, ether solvents such as diethyl ether and tetrahydrofuran, and ester solvents such as methyl acetate, ethyl acetate and butyl acetate.

  A catalyst can be used to accelerate the reaction. For example, alkali metals such as potassium fluoride, sodium fluoride, sodium methoxide, triethylamine, triethylenediamine, diethanolamine, 1,8-diazabicyclo (5,4,0) -7-undecene, 1,5-diazabicyclo (4 , 3,0) -5-Nonene and the like can be used.

<Use and formulation>
The use of the polyamideimide resin of the present invention thus obtained is not particularly limited, but the most useful use is a seamless belt for transferring toner used for electrophotographic copying machines and laser printers, and for transporting paper. It is.

  Further, in the case of a seamless belt for an electrophotographic copying machine or a laser printer, since an appropriate electrical conductivity is required, it is necessary to add an antistatic agent to the polyamideimide resin of the present invention. Antistatic agents used in the present invention include carbon blacks such as ketjen black, acetylene black and braphite, anionic, cationic, nonionic and amphoteric surfactants, electron conduction such as polythiophene, polyaniline and polyacetylene. A functional polymer or the like is used. Among these, carbon black and polyaniline are preferable because they have a low humidity dependency on conductivity and are excellent in dispersibility and solubility in polyamideimide. In the case of polyaniline, a type in which an oxidatively polymerized polyaniline derivative is doped with an organic protonic acid dopant such as an inorganic acid or dodecylbenzenesulfonic acid and can be dissolved or dispersed in an organic solvent or water is preferable.

  The amount of the antistatic agent blended in the polyamide-imide resin of the present invention varies depending on the antistatic agent, but it may be adjusted so that the surface resistance value when formed on the belt is in the range of 10E + 6 to 10E + 14Ω / □. For example, in the case of carbon black, the conductive resin composition may have a blending ratio (mass ratio [carbon black / polyamideimide resin]) of 5/95 to 30/70 of the polyamideimide resin of the present invention and carbon black. . The blending ratio (mass ratio [carbon black / polyamideimide resin]) is preferably 5/95 to 20/80.

  The method of blending the antistatic agent with the polyamideimide resin of the present invention can be carried out by using a normal disperser such as a dissolver, a three-roll mill, a sand mill, a ball mill, an attritor, a planetarium mixer, alone or in combination.

  The polyamide-imide resin of the present invention includes a colorant, a dispersant, a filler, a leveling agent, an antifoaming agent and a polyamide-imide resin other than the present invention, a polyamide resin, a polyimide resin, a polyester resin, as long as the original properties are not impaired. A polyurethane resin or the like can be blended. Furthermore, a silicone release agent, a crosslinking agent, etc. can also be mix | blended. Examples of the crosslinking agent include bifunctional or higher functional epoxy compounds, melamine compounds, and isocyanate compounds.

  A method of forming a seamless belt from a conductive composition in which an antistatic agent is blended with the polyamideimide resin of the present invention can be performed by extrusion molding, blow molding, injection molding, coating, centrifugal molding, and the like. Then, centrifugal molding capable of solution molding is preferable.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
The conductive molded articles tested in the examples and comparative examples were produced by the following method.

(Example of making conductive molded products)
Raven 780 (manufactured by Columbia Carbon Co.) was blended in the polyamideimide resin solution synthesized in the examples and comparative examples in a solid content ratio of 25%, and dispersed by passing twice through a three-roll mill. These dispersions were poured inside a cylindrical mold having a diameter of 150 mm and dried at 100 ° C. for 30 minutes and then at 220 ° C. for 5 hours while rotating at 200 revolutions / minute. A 0.1 mm seamless belt was produced.
In addition, the measured value shown in the Example is a value measured by the following method.

1. Solubility Polyamideimide resin solution was filled in a glass container, hermetically sealed, and the dissolution state when left in an atmosphere of 25 ° C. for 24 hours was judged visually.
○: Maintaining transparency ×: Opaque to solidified

2. Logarithmic viscosity 0.5 g of dried polyamideimide resin was dissolved in 100 ml of N-methyl-2-pyrrolidone and immersed in a constant temperature bath at 30 ° C. for 30 minutes or more using an Ubbelohde type viscosity tube. Calculated according to
ηinh (dl / g) = ln (t / t0)
t: passage time of polyamideimide solution, t0: passage time of N-methyl-2-pyrrolidone

3. Tensile strength, elongation The conductive molded product was measured at a tensile speed of 20 mm / min using a tensile tester manufactured by Toyo Baldwin.

4). Tear strength: index of flexibility The conductive molded article was measured according to the conditions of JIS K7128-1 (trouser tear method).

5. Water absorption: index of low water absorption About 1 g of the conductive molded product was precisely weighed (w0), immersed in water at 25 ° C. for 24 hours, then weighed again (w1) and obtained by the following formula.
Water absorption rate (%) = [(w1-w0) / w1] × 100

6). Humidity expansion coefficient: index of low water absorption Make a conductive molded product into a strip of 4 mm width, apply a load of 3 g on one end, and measure the dimensional changes at room temperature at 40% RH and 65% RH. did.

(Example 1)
Trimellitic anhydride (TMA) 0.8 mol, 4,4 '-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride (BISDA) in a four-necked flask with a condenser and a nitrogen inlet ) 0.2 mol, diphenylmethane-4,4′-diisocyanate (MDI) 0.99 mol, diazabicycloundecene (DBU) 0.005 mol with a solid content of 20% N-methyl-2 Polymerization was carried out by charging with pyrrolidone (NMP) and stirring for 3 hours while raising the temperature to 90 ° C, and further for 3 hours while raising the temperature to 120 ° C. The characteristics are shown in Table 1.

(Example 2)
A container similar to Example 1 was charged with 0.6 mol of TMA, 0.4 mol of BISDA, 0.99 mol of MDI, and 0.01 mol of potassium fluoride (KF) together with NMP so that the solid content concentration would be 20%. The polymerization was carried out by stirring for 2 hours while raising the temperature to 1 hour, stirring for 1 hour while raising the temperature to 120 ° C, and further stirring for 3 hours while raising the temperature to 180 ° C. The characteristics are shown in Table 1.

(Example 3)
In the synthesis example of the polyamideimide resin of Example 2, NMP was changed to γ-butyrolactone (GBL), and the temperature was raised to 90 ° C. for 2 hours, raised to 120 ° C. for 1 hour, and further raised to 150 ° C. The polymerization was carried out with stirring for 2 hours. The characteristics are shown in Table 1.

Example 4
A container similar to Example 1 was charged with 0.2 mol of TMA, 0.8 mol of BISDA, 1 mol of MDI and 0.01 mol of KF together with NMP so that the solid content concentration would be 20%, while raising the temperature to 90 ° C. The polymerization was continued for 2 hours with stirring at 120 ° C. for 1 hour and further with stirring at 180 ° C. for 3 hours. The characteristics are shown in Table 1.

(Example 5)
To 100 parts by mass of the polyamideimide resin solution prepared in Example 1, 400 parts by weight of carbon black (Conductex SC Ultra; made by Colombian Carbon Japan) is added to 100 parts by weight of the resin solid content, and 1 hour (25 ° C.) with a ball mill. Thorough mixing was performed to obtain a carbon black masterbatch. The same resin as that used for dispersion was added thereto, and mixed so that polyamideimide resin / carbon black = 95/5 (solid content mass ratio).
This carbon black-containing varnish was made into a seamless belt by the following procedure. A coating machine having a cylindrical cylinder whose inner peripheral surface was mirror-finished and a slit-shaped outlet having a length corresponding to the width of the cylindrical cylinder was prepared. While rotating the cylinder slowly, carbon black-containing varnish was supplied to the inner peripheral surface. After the supply of varnish is finished, the rotation speed of the cylinder is increased and the whole is made uniform, and then dried at 100 ° C. to 120 ° C. for 30 minutes. Then, the heating is stopped, and the rotation is stopped by cooling to room temperature. I got a seamless belt. The seamless belt is peeled off from the cylinder, and then a rod having an outer diameter that is about 3% smaller than the inner diameter of the belt-like material is inserted into the belt-like material. While heating, a seamless belt containing a conductive agent was obtained by heating at 200 ° C. for 40 minutes and at 250 ° C. for 120 minutes. The total thickness was about 100 microns. Table 2 shows the characteristics of this seamless belt.

(Example 6)
A seamless belt was obtained in the same manner as in Example 5 except that the polyamideimide resin / carbon black was changed to 75/25 (solid content mass ratio). Table 2 shows the characteristics of this seamless belt.

(Comparative Example 1)
In the same container used for the polymerization of Example 1, 0.05 mol of TMA, 0.95 mol of BISDA, 1.01 mol of MDI, 0.01 mol of KF together with γ-butyrolactone so that the solid content concentration becomes 20%. The polymerization was continued by stirring for 2 hours while raising the temperature to 90 ° C, 1 hour while raising the temperature to 120 ° C, and 3 hours while raising the temperature to 180 ° C. This polyamideimide resin solution began to become turbid in the middle of polymerization, and since the solubility was poor, a conductive molded product could not be produced and the characteristics could not be evaluated.

(Comparative Example 2)
In a container similar to that used for the polymerization in Example 1, 1.0 mol of TMA, 0.99 mol of MDI, and 0.005 mol of KF were charged so that the solid concentration was 20%, and the temperature was raised to 90 ° C. The polymerization was continued for 2 hours while stirring at 120 ° C. for 3 hours. The characteristics are shown in Table 1.

(Comparative Example 3)
A seamless belt was obtained in the same manner as in Example 5 using the polyamideimide resin solution obtained in Comparative Example 2. The evaluation results are shown in Table 2.

The polyamideimide resin having the specific structure shown in Examples 1 to 4 has a reduced water absorption and humidity expansion coefficient while maintaining a high glass transition temperature as compared with the polyamideimide resin of the comparative example, and tear strength. Has improved.

The seamless belt using the polyamideimide resin having a specific structure shown in Examples 5 and 6 has a reduced water absorption and humidity expansion coefficient and improved tear strength compared to the seamless belt of Comparative Example 3. Yes.

  The polyamide-imide resin solution of the present invention is excellent in low water absorption and solvent solubility without impairing the inherent heat resistance (glass transition temperature) and mechanical properties (tensile strength, tear strength) of the polyamide-imide resin. It is possible to provide a conductive composition containing an inhibitor and a conductive seamless belt of an electrophotographic copying machine or a laser printer molded using the conductive composition.

Claims (6)

Polyamideimide resin containing 10 to 90 mol% of a structural unit represented by the following general formula (1).
(In the general formula (1), R ₁ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ —. R ₂ and R ₃ may be the same or different, and may be hydrogen, halogen atom, aryl group or Represents an alkyl group having 1 to 3 carbon atoms, provided that when R ₁ is —SO ₂ —, R ₄ represents an aryl group which may have a substituent. In a polyamideimide resin, comprising a structural unit derived from trimellitic anhydride, a structural unit derived from a polycarboxylic dianhydride represented by the following general formula (2), and a structural unit derived from diisocyanate or diamine When the total of the structural units derived from the acid component is 100 mol%, the structural unit derived from the polycarboxylic dianhydride represented by the general formula (2) is 10 to 90 mol%. The polyamide-imide resin according to claim 1.
(In the general formula (2), R ₅ represents an alkyl group having 1 to 5 carbon atoms or —SO ₂ —. R ₆ and R ₇ may be the same or different, and may be a hydrogen atom, a halogen atom, an aryl group or Represents an alkyl group having 1 to 3 carbon atoms, provided that R ₅ is —SO ₂ —.   3. The polyamidoimide resin according to claim 2, wherein the structural unit derived from diisocyanate or diamine is a structural unit derived from aromatic diisocyanate or aromatic diamine.   The electroconductive composition containing the polyamideimide resin in any one of Claims 1-3, and an antistatic agent.   The antistatic agent is carbon black, and the compounding ratio (mass ratio [carbon black / polyamideimide resin]) of the polyamideimide resin and carbon black is 5/95 to 30/70. The conductive resin composition as described.   A seamless belt containing the conductive resin composition according to claim 4.