JP4983370B2 - Conductive composition, method for producing the same, and seamless belt using the same - Google Patents

Description

  The present invention is a heat-resistant conductive composition useful for various electrostatic disturbance prevention materials, electromagnetic shielding materials, electrophotographic copying machines, laser printers, transfer belts for conveying toner, paper, etc., and fixing belts for fixing toners. About.

  In general, conductive resin compositions include polyethylene terephthalate, polyetherimide, polyimide, polycarbonate, polyethersulfone, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, fluoroethylene-propylene copolymer and other fluororesins. A material in which conductive carbon such as acetylene black or ketjen black or a surfactant is dispersed has been used.

  Among these, polyethylene terephthalate, polycarbonate, and fluororesin have the disadvantages that they are insufficient in heat resistance and weak against long-term mechanical stress, and polyimide is exemplified in Patent Document 1, for example, but it is difficult to disperse carbon. In addition, there is a drawback in that quality variation is large because an imidization reaction is performed at a high temperature during molding. Polyamideimide resins have also been studied for a long time, for example, as exemplified in Patent Documents 2 to 6, etc., but conventional polyamideimide resins have insufficient film strength and durability, and therefore, It was necessary to leave the solvent in the molded film.

  Patent Document 7 discloses a composition in which a polyaniline resin is blended with a polyamidoimide resin having an o-tolidine structure. However, a decrease in dimensional stability due to moisture absorption of polyaniline and a decrease in creep characteristics during moisture absorption. In addition, there were drawbacks such as a decrease in conductive tear strength associated with the decomposition of polyaniline during heat treatment at 230 ° C. or higher. Further, Patent Document 8 discloses a composition in which a polyaniline resin is blended with a polyamide resin having an alicyclic structure. However, the dimensional stability is reduced due to moisture absorption based on amide bonds and polyaniline, and the creep property during moisture absorption is reduced. As described above, there is a demand for improved durability and heat resistance during high-temperature treatment, as well as dimensional stability under high temperature and high humidity.

  In particular, the transfer belts of the above-mentioned copying machines and laser printers have improved electrostatic property stability, mechanical strength and tear strength for toner, paper adsorption, transport and transfer due to recent demands for colorization and higher speed. The decline was a problem.

JP-A-11-170284 JP 56-167151 A JP 58-85468 A Japanese Patent Laid-Open No. 10-282801 JP 2000-313071 A JP 2001-97519 A JP 2003-147199 A JP 2003-261766 A

  The present invention provides a composition having excellent heat resistance, mechanical strength, and dimensional stability, and having stable conductivity and dimensional stability with little humidity dependency, and provides an excellent antistatic agent and electromagnetic wave shielding agent. At the same time, it provides a transport belt and a fixing belt for an electrophotographic copying machine and a laser printer using the same.

  As a result of intensive studies in view of the above problems, the present inventors have finally completed the present invention. That is, this invention is the following electrically conductive composition and a seamless belt using the same.

(1) A conductive composition comprising a polyamideimide resin A having a logarithmic viscosity of 1.0 dl / g or less, a polyamideimide resin B having a logarithmic viscosity of 1.2 dl / g or more, and an antistatic agent. .

(2) One or two of a part of the acid component of the polyamideimide resin B selected from pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyltetracarboxylic anhydride, ethylene glycol bisanhydro trimellitate The conductive composition according to (1), which is a seed or more.

(3) The conductive composition according to (1) or (2), wherein the amine component (isocyanate component) of the polyamideimide resin B is a component having a naphthalene and / or o-tolidine residue.

(4) The mixing ratio (weight ratio) of the polyamideimide resin A and the polyamideimide resin B is 10/90 to 90/10, and the tensile elasticity modulus of the mixed polyamideimide resin film is 3500 MPa or more (1) to (3) The electrically conductive composition in any one of.

(5) A solution of a polyamideimide resin B having a logarithmic viscosity of 1.2 dl / g or more is mixed with a solution in which an antistatic agent is dispersed in the polyamideimide resin A having a logarithmic viscosity of 1.0 dl / g or less. A method for producing a conductive composition.

(6) A seamless belt using the conductive composition according to any one of (1) to (5).

  The conductive resin composition of the present invention is useful as an antistatic agent and electromagnetic wave shielding agent having excellent strength and heat resistance, less dimensional stability and humidity dependence, and having stable conductivity. Since it can be used as a transport belt or a fixing belt of an electrophotographic copying machine or a laser printer using this, it greatly contributes to the industry.

  The present invention is a conductive composition in which an antistatic agent is blended with a polyamideimide resin, and a seamless belt formed by molding the polyamideimide resin, which are excellent in heat resistance, mechanical properties, and dimensional stability under high temperature and high humidity.

Two or more types of polyamideimide resins having different logarithmic viscosities used in the present invention can be produced by a known method such as an acid chloride method or an isocyanate method.
The acid component used in the production of the polyamideimide resin A or B includes trimellitic acid and its anhydride, acid chloride, pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, Tetracarboxylic acids such as biphenyl ether tetracarboxylic acid, ethylene glycol bisanhydro trimellitate, propylene glycol bisan hydrotrimellitate and their anhydrides, oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecane Aliphatic dicarboxylic acids such as dicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexane Examples include alicyclic dicarboxylic acids such as sandicarboxylic acid, 4,4'-dicyclohexylmethane dicarboxylic acid and dimer acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid and naphthalenedicarboxylic acid. Among these, trimellitic anhydride is most preferable in terms of reactivity, heat resistance, solubility, etc., some of which are pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyltetracarboxylic anhydride, Those in which ethylene glycol bisanhydro trimellitate is replaced are preferred from the viewpoint of dimensional stability. When using pyromellitic acid anhydride, benzophenone tetracarboxylic acid anhydride, biphenyl tetracarboxylic acid anhydride, ethylene glycol bisanhydro trimellitate, the copolymerization amount is 5 to 70 when the acid component is 100 mol%. It is preferable that it is mol%. The lower limit is more preferably 10 mol%, and the upper limit is more preferably 60 mol%.

  Next, as the diamine (diisocyanate) used in the production of the polyamideimide resin A or B, aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine and the like, diisocyanates thereof, 1,4-cyclohexanediamine, and 1,3-cyclohexanediamine. , Cyclophoric diamines such as isophorone diamine and 4,4′-dicyclohexylmethane diamine, and diisocyanates thereof, m-phenylene diamine, p-phenylene diamine, 4,4′-diaminodiphenyl methane, 4,4′-diaminodiphenyl ether, 4 , 4′-diaminodiphenyl sulfone, benzidine, o-tolidine, 2,4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine, naphthalenediamine, and the like, and Among these diisocyanates, among them, 4,4′-diaminodiphenylmethane (diisocyanate), 2,4-tolylenediamine (diisocyanate), o-tolidine (diisocyanate) due to heat resistance, mechanical properties, solubility, etc. Naphthalenediamine (diisocyanate), isophoronediamine (diisocyanate) and the like are preferable. In particular, o-tolidine (diisocyanate) and naphthalenediamine (diisocyanate) are preferable from the viewpoint of dimensional stability and mechanical properties. These components are preferably copolymerized in an amount of 50 mol% or more, more preferably 70 mol% or more, when the total diamine component is 100 mol%.

The feature of the present invention is that two or more types of polyamideimide resins having different molecular weights are used in combination. When the molecular weight of the polyamide-imide resin is large, mechanical properties and dimensional stability are improved. However, since the solution viscosity is high, the dispersibility of the antistatic agent such as carbon is lowered, and it is difficult to obtain stable conductivity. Distributed work becomes difficult. On the other hand, when the molecular weight is small, the dispersion work becomes easy and a uniform dispersion can be obtained and stable conductivity can be easily obtained, but conversely, mechanical properties and dimensional stability are lowered.
In the case of the present invention, a stable conductivity can be obtained by dispersing an antistatic agent such as carbon using a low molecular weight polyamideimide solution and then mixing a high molecular weight polyamideimide resin to develop the desired conductivity. In addition, it is possible to provide a conductive composition having excellent dimensional stability and mechanical properties.

The low molecular weight polyamideimide resin A of the present invention has a logarithmic viscosity of 1.0 dl / g or less, preferably 0.9 dl / g or less. The lower limit is not particularly limited, but is preferably 0.3 dl / g or more in consideration of not significantly impairing mechanical properties.
If the logarithmic viscosity of the low molecular weight polyamideimide resin A exceeds 1.0 dl / g, the dispersibility of carbon and the like and the dispersibility workability are lowered, which is not preferable.

  The high molecular weight polyamideimide resin B of the present invention has a logarithmic viscosity of 1.2 dl / g or more, preferably 1.4 dl / g or more. Although there is no upper limit in particular, 2.5 dl / g or less is preferable normally from the productivity of a polyamideimide resin. When the logarithmic viscosity is 1.2 dl / g or less, mechanical strength and dimensional stability are insufficient.

  In the present invention, the mixing ratio of the low molecular weight polyamideimide resin and the high molecular weight polyamideimide resin is 10/90 to 90/10, preferably 20/80 to 80, by weight ratio of solids, although it depends on the logarithmic viscosity of each. More preferably, it is 30/70 to 60/40. When the proportion of the low molecular weight polyamideimide resin is 10% or less, it is difficult to disperse carbon or the like, and when it is 90% or more, the mechanical properties and dimensional stability of a seamless belt made from the conductive composition are lowered.

Two or more types of polyamide-imide resins used in the present invention can be obtained at 60 to 200 ° C. in polar solvents such as N, N′-dimethylacetamide, N-methyl-2-pyrrolidone, N, N′-dimethylformamide, and γ-butyrolactone. It can be produced by stirring while heating.
In this case, an organic amine compound such as triethylamine, diethylenetriamine, or diazabicycloundecene, or a metal compound such as potassium fluoride, sodium fluoride, cesium fluoride, or sodium methoxide can be used as a catalyst as necessary.

  The antistatic agent used in the present invention is not particularly limited, but carbon blacks such as ketjen black, acetylene black, graphite, anionic, cationic, nonionic and amphoteric surfactants, polythiophene, polyacetylene, polyaniline An electronically conductive polymer such as is used. Among these, carbon black and polyaniline, which are less dependent on the humidity of conductivity and are excellent in dispersibility and compatibility with polyamideimide, are preferred.

  Polyaniline can be dissolved or dispersed in an organic solvent or water obtained by doping an oxidatively polymerized polyaniline derivative with an organic protonic acid dopant such as an inorganic acid or dodecylbenzenesulfonic acid.

The amount of the antistatic agent blended in the polyamideimide resin varies depending on the antistatic agent, but is adjusted so that the surface resistance value when formed on the belt is in the range of 10 ⁶ to 10 ¹⁴ (Ω / □). In the case of carbon black, the blending amount is selected between 5 and 30%.

  The method of blending the antistatic agent with the polyamideimide resin of the present invention is preferably such that the antistatic agent is mixed with a low molecular weight polyamideimide resin solution, and a dissolver, a three-roll mill, a sand mill, a ball mill, a planetarium mixer, an attritor, etc. A high-concentration antistatic agent solution is produced by using a disperser. Thereafter, a high molecular weight polyamideimide resin solution is added to obtain a final conductive composition solution. In this case, the colorant, dispersant, inorganic filler, leveling agent, antifoaming agent, polyester, polyamide, polyimide, polyurethane, and other resins, silicone-based release agents, and crosslinks within a range that does not impair the characteristics of the heat-resistant conductive composition An agent or the like can be blended. Examples of the crosslinking agent include bifunctional or higher functional epoxy resins, melamine resins, and isocyanate compounds.

  The method of molding a belt or the like from the heat-resistant conductive composition comprising the polyamideimide resin and the antistatic agent of the present invention is performed by extrusion molding, blow molding, injection molding, coating, centrifugal molding, etc., among these, solution molding It is preferable to use a centrifugal molding method.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. In addition, the measured value in an Example is a value measured with the following method.
Logarithmic viscosity A solution prepared by dissolving 0.5 g of a polymer in 100 ml of NMP (N-methyl-2-pyrrolidone) was measured at 25 ° C. using an Ubbelohde viscosity tube.
-Surface resistance It measured in the environment of 25 degreeC, 65% RH, 10 degreeC, and 15% RH using HIGH RESISTANCE METER made from Yokogawa Hewlett Packard.
-Membrane strength A polyamideimide resin film having a measurement width of 10 mm and a measurement length of 40 mm was measured using Tensilon of Toyo Baldwin Co., Ltd. under the conditions of 25 ° C. and 65% RH under a pulling speed of 20 mm / min.
-Tear strength Measured at room temperature in accordance with JIS K7128-1 (trouser tear method).
・ Tensile strength elastic modulus Polyamideimide resin solution was applied to PET film so that the dry film thickness was about 30μm, dried at 100 ° C for 10 minutes, then peeled off from PET film, and peeled polyamideimide resin film was fixed to metal frame And it dried at 200 degreeC for 15 hours.
A strip having a width of 10 mm was made from the obtained film and obtained from the gradient of the initial stress when measured at a tensile rate of 20 mm / min using Tensilon manufactured by Toyo Baldwin.

Reference Example 1 (Synthesis of polyamideimide resin A1)
In a four-necked flask equipped with a condenser and a nitrogen gas inlet, 1.02 mol of trimellitic anhydride (hereinafter sometimes abbreviated as TMA) and diphenylmethane-4,4′-diisocyanate (hereinafter abbreviated as MDI) 1 mol is charged with N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) so that the solid content concentration is 20%, and the temperature is raised to 100 ° C. while stirring and the reaction is continued for about 1 hour. I let you. Furthermore, this reaction solution was heated to 180 ° C. and the reaction was continued for about 3 hours. While cooling, the solution was diluted with NMP so that the solid content concentration became 15%. The obtained polyamideimide resin A1 had a logarithmic viscosity of 0.75 dl / g.

Reference Example 2 (Synthesis of polyamideimide resin B1)
Using the same apparatus as in Example 1, 1.0 mol of TMA, 1.0 mol of naphthalene diisocyanate (NDI), and 0.01 mol of potassium fluoride were charged together with NMP so that the solid content concentration would be 20%, while stirring. After reacting at 100 ° C. for about 3 hours, the reaction mixture was diluted with NMP so that the solid concentration was 15%. The logarithmic viscosity of the obtained polyamideimide resin B1 was 1.52 dl / g.

Reference Example 3 (Synthesis of polyamideimide resin B2)
In a four-necked flask equipped with a condenser and a nitrogen gas inlet, 1.01 mol of TMA, 0.8 mol of o-tolidine diisocyanate (TODI), 0.2 mol of 2,4-tolylene diisocyanate (TDI), diazabicyclo Add 0.01 mol of undecene together with NMP so that the solid concentration is 20%, raise the temperature to 90 ° C. while stirring, react for about 4 hours, and then cool the solid content to 15% while cooling. Diluted with NMP. The logarithmic viscosity of the obtained polyamideimide resin B2 was 1.45 dl / g.

Reference Example 4 (Synthesis of polyamideimide resin B3)
In a four-necked flask equipped with a condenser and a nitrogen gas inlet, 0.90 mol of TMA, 0.05 mol of benzophenone tetracarboxylic acid anhydride, 0.05 mol of biphenyl tetracarboxylic acid anhydride, 1 mol of o-tolidine diisocyanate, After adding 0.01 mol of potassium halide together with N-methyl-2-pyrrolidone so that the solid content concentration becomes 20%, the temperature was raised to 90 ° C. with stirring and reacted for about 4 hours. The solution was diluted with NMP so that the concentration was 15%. The logarithmic viscosity of the obtained polyamideimide resin B3 was 1.47 dl / g.

Examples 1 to 3 (Production Examples of Conductive Molded Products-1, 2, 3)
Raven 780 (Colombian Carbon Co.) was blended with the polyamideimide resin A1 synthesized in Reference Example 1 in a solid content ratio of 50% and dispersed twice by passing through a three-roll mill to produce a master paint. This dispersion was mixed and stirred in the polyamideimide resin B1, B2 and B3 solution so that the carbon concentration was 25% in terms of solid content, and uniformly dispersed to prepare a conductive paint. These paints are poured into 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 rpm, and then detached from the mold to have a thickness of about 0.1 mm. A 1 mm seamless belt was created. As shown in Table 1, excellent conductivity and mechanical properties were exhibited, and molded articles suitable for electrophotographic copying machines and laser printer belts were obtained.

Comparative Example 1
A carbon dispersion master solution was produced using polyamideimide resin B2 instead of polyamideimide resin A1 used in Example 1, and then conductive paint obtained by mixing and stirring polyamideimide resin B2 was used. A seamless belt was produced in the same manner as in Example 1. As shown in Table 1, a molded article having poor conductivity based on poor dispersion and insufficient tear strength was obtained.

Comparative Example 2
A polyamideimide resin A1 was similarly mixed and stirred in the master carbon dispersion using the polyamideimide resin A1, and the same conductive molded article as in Example 1 was produced. The tear strength and tensile elastic modulus were low, and the molded product was insufficient as a transfer belt.

  The conductive resin composition of the present invention is useful as an antistatic agent and electromagnetic wave shielding agent having excellent strength and heat resistance, less dimensional stability and humidity dependence, and having stable conductivity. It can be used as a paper transport belt or toner transfer belt for electrophotographic copying machines and laser printers using this.

Claims (6)

  A conductive composition comprising a polyamideimide resin A having a logarithmic viscosity of 1.0 dl / g or less, a polyamideimide resin B having a logarithmic viscosity of 1.2 dl / g or more, and an antistatic agent.   A part of the acid component of the polyamideimide resin B is one or more selected from pyromellitic acid anhydride, benzophenonetetracarboxylic acid anhydride, biphenyltetracarboxylic acid anhydride, and ethylene glycol bisanhydro trimellitate. The conductive composition according to claim 1.   The conductive composition according to claim 1, wherein the amine component (isocyanate component) of the polyamideimide resin B is a component having a naphthalene and / or o-tolidine residue.   The mixing ratio (weight ratio) of the polyamideimide resin A and the polyamideimide resin B is 10/90 to 90/10, and the tensile modulus of elasticity of the mixed polyamideimide resin film is 3500 MPa or more. The electroconductive composition as described in.   Conductivity characterized in that a solution of a polyamideimide resin B having a logarithmic viscosity of 1.2 dl / g or more is mixed with a solution in which an antistatic agent is dispersed in a polyamideimide resin A having a logarithmic viscosity of 1.0 dl / g or less. Method for producing a composition. Seamless belt using a conductive composition according to any one of claims 1-4.