JP4507073B2 - Seamless belt - Google Patents

Description

  The present invention relates to a seamless belt, that is, a so-called seamless belt, which is used in a device that requires high feed accuracy, such as a printing machine, a printer, and a conveyance device.

A conveyor belt that requires high feeding accuracy is not a rubber, but a metal belt or a belt made of a polymer film with low stretchability. In particular, in printing presses, printers, and the like, belts formed by seamlessly dispersing a conductive filler or the like in a polymer film have been used. As a material for the polymer film, a seamless belt using a film made of polyethylene terephthalate, for example, vinylidene fluoride, ethylene / tetrafluoroethylene copolymer, polycarbonate, or the like has been proposed. There has also been proposed a seamless belt made of a film having a volume resistivity of 1 to 10 ¹³ Ω · cm by blending a conductive material with a polyimide film. (See Patent Documents 1 to 4)
JP-A-5-77252 Japanese Patent Laid-Open No. 5-200904 JP-A-5-345368 JP-A-6-95521

In addition, a method has been proposed in which electrical characteristics and mechanical characteristics are improved by forming a plurality of layers in a polyimide film seamless belt and individually adjusting the electrical characteristics of each layer. Furthermore, in order to increase the strength, a method of reinforcing with a high-strength fiber such as polybenzobisoxazole fiber has also been proposed (see Patent Documents 5 to 7).
JP 7-156287 A JP 2002-156835 A JP 2001-32178 A

However, the conventionally proposed seamless belt cannot completely prevent misalignment due to expansion and contraction of the seamless belt itself, and in particular, color misregistration occurs in a printing press and printer, and intended color reproduction cannot be performed well. Cases often occurred. In addition, when used as a fixing belt, there is a problem that the seamless belt is stretched and the color shift is promoted during fixing.
In addition, seamless belts are often used in multiple layers, or if necessary, with a functional filler blended, but in that case, due to the effect of the filler, mechanical properties are significantly reduced, warped, Problems such as tarmi have also been pointed out. In addition, it has been pointed out that the mechanical and electrical characteristics of the seamless belt change with long-term use, and the image gradually becomes distorted by repeated use. Further, when a reinforcing material such as a fiber is used in combination, the flatness is lowered and it may not be used for image formation.

  An object of this invention is to provide the seamless belt which is excellent in heat resistance and feeding accuracy, and has few characteristic deterioration by repeated use.

In order to achieve the above object, the present inventors have conducted intensive research on factors that improve feeding accuracy and repeated durability, and as a result, have a specific linear expansion coefficient and tensile modulus as a heat-resistant polymer film constituting a seamless belt. It has been found that the above problem can be solved by making the weight loss within a specific range more preferably within a predetermined temperature range.
That is, the present invention is (1) a seamless belt made of a heat-resistant polymer film having a linear expansion coefficient of −5 ppm / ° C. or more and 20 ppm / ° C. or less and a tensile elastic modulus of 5 GPa or more. In a preferred embodiment, (2) the heat-resistant polymer film was held at 170 ° C. for 10 minutes in an inert gas atmosphere, then heated to 450 ° C. at 20 ° C./min, and further held at 450 ° C. for 30 minutes. In this case, the seamless belt is a heat-resistant polymer film having a weight reduction amount of 5% by weight or less after the temperature is raised from 170 ° C. until it is held at 450 ° C. for 30 minutes. A preferred embodiment is the seamless belt (3) wherein the heat-resistant polymer film is made of a polymer having an imide bond in the main chain. A particularly preferred embodiment is (4) a polyimide benzoxazole obtained by reacting an aromatic diamine having a benzoxazole structure with a polymer having an imide bond in the main chain and an aromatic tetracarboxylic acid anhydride. It is a seamless belt. In a more preferred aspect, (5) the seamless belt is characterized in that the heat-resistant polymer film contains a conductive substance.

  The seamless belt of the present invention is composed of a heat-resistant polymer film having a high tensile elastic modulus and a small linear expansion coefficient, so that the dimensional change rate of the seamless belt itself is small, the feeding accuracy is high, and the dimensional change of the seamless belt is caused. The stress on the seamless belt itself and the stress on the seamless belt drive system are reduced, resulting in high durability. Furthermore, since it consists of a heat-resistant polymer film with a small weight loss at high temperatures, the stress caused by temperature changes is small, and as a result, it is excellent in stability and durability even when used repeatedly at high temperatures.

The heat-resistant polymer film constituting the seamless belt of the present invention is a film made of a polymer having a glass transition temperature of 170 ° C. or higher, specifically, wholly aromatic polyester, wholly aromatic polyamide, polyimide, polyamideimide. , Polyetherimide, polyesterimide, polybenzoxazole, polybenzimidazole, polybenzothiazole, polyimide benzoxazole, polyether ketone, and the like. In the present invention, a heat resistant polymer film having a linear expansion coefficient of −5 ppm / ° C. to 20 ppm / ° C. and a tensile modulus of 5 GPa or more can be selected and used from such heat resistant polymer films.
The heat-resistant polymer film preferably used is a film made of a polymer having an imide bond in the main chain, and specifically, for example, a film made of polyimide, polyamideimide, polyimide benzoxazole, and particularly a polyimide benzoxazole film. Is preferred.

The heat-resistant polymer film made of a polymer having an imide bond in the main chain will be further described.
In the present invention, a polymer having an imide bond in the main chain can be obtained by reacting an aromatic diamine with an aromatic tetracarboxylic acid anhydride or an aromatic tricarboxylic acid anhydride. In the aforementioned reaction, first, a diamine and a carboxylic acid anhydride are subjected to a ring-opening polyaddition reaction in a solvent to obtain a polyamic acid solution, and then the polyamic acid solution is cast on a drum, A tubular heat-resistant polymer film having an imide bond in the main chain is obtained by drying to obtain a tubular film of a polyimide precursor, followed by dehydration condensation (imidization).

The following can be illustrated as diamines used in this invention. For example, 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3 -Aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3 , 3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diaminodiphenyl ether, 3,4′-diamino Diphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,3′-di Minodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3 , 3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4 -(4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1 -Bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bi [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [ -(4-Aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5- Dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,4-bis (3-aminophenoxy) benzene 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) ) Phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-amino) Phenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) benzoyl] Benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy ) Benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4 -(3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4 -(3-aminophenoxy) phenyl] sulfoxide, 4,4'-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4 , 4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, Bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) pheno Ci-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6) -Trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [ 4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophene 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 4,4′-diamino-5,5′-dibiphenoxybenzophenone, 3,47-diamino-4,5′-dibiphenoxybenzophenone, 3, 3'-diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino-4) -Phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino- 4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis ( 4-amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile and one of the hydrogen atoms on the aromatic ring of the aromatic diamine Part or all of them are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, alkyl groups or alkoxyl groups And an aromatic diamine substituted with a C 1-3 halogenated alkyl group or alkoxyl group in which some or all of the hydrogen atoms are substituted with a halogen atom.

  In the present invention, diamines having a benzoxazole structure described below are preferably used in an amount of 50 mol% or more of the total diamine. Such diamines may be used alone or in combination of two or more. Specific examples of the aromatic diamine having a benzoxazole structure used in the present invention include the following.

  Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.

  The tetracarboxylic acid anhydrides used in the present invention are aromatic tetracarboxylic acid anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

  These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are 50 mol% or less of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1 -(2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ', 4'-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane -2,3,5,6-tetracarboxylic dianhydride, Cyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid A dianhydride etc. are mentioned. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  Examples of the aromatic tricarboxylic acid anhydride used in the present invention include trimellitic acid anhydride.

  The solvent used when polymerizing diamines and tetracarboxylic acid anhydrides to obtain a polyamic acid is not particularly limited as long as it dissolves both the raw material monomer and the polyamic acid to be produced. Solvents are preferred, for example, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric Amides, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like can be mentioned. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the weight of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by weight, The amount is preferably 10 to 30% by weight.

  Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for minutes to 30 hours. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The weight of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). And from the stability point of liquid feeding, Preferably it is 10-2000 Pa.s, More preferably, it is 100-1000 Pa.s.

  Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.

  It is also a preferred embodiment to add fine particles that become a lubricant to improve the handleability of a seamless belt or a heat-resistant polymer film before or during polymerization. As the fine particles, organic or inorganic heat-resistant fine particles having a particle diameter of 0.03 to 3.0 μm can be used, and preferably metal oxides such as silica, alumina and titanium oxide, or calcium phosphate and dicalcium phosphate. Insoluble inorganic salts such as calcium pyrophosphate can be used.

  In the present invention, a ring-closing catalyst can be added to the polyamic acid solution in order to perform the imidization reaction efficiently. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.1-8 mol.

  In the present invention, a dehydrating agent can be added to the polyamic acid solution in order to efficiently perform the imidization reaction. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is not particularly limited, but is preferably 0.1 to 4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.

  In the present invention, the polyimide precursor solution thus obtained is coated and dried on the outside or inside of a cylindrical or seamless belt-like support, and preferably subjected to a dehydration ring-closing reaction by heat treatment to form an imide bond. A tubular heat-resistant polymer film is obtained.

  The seamless belt of the present invention comprises a heat-resistant polymer film having a tensile elastic modulus of 5 GPa or more in the circumferential direction (hereinafter referred to as MD direction) and the width direction (hereinafter referred to as TD direction). When the tensile modulus is less than this range, the dimensional stability of the seamless belt is not sufficient. In order to set the tensile modulus to 5 GPa or more, a method using 20 mol% or more, preferably 40 mol% or more of the biphenyltetracarboxylic acid component in the total acid component, or 30 mol% of the diamine component having a benzoxazole structure in the total diamine component. As mentioned above, the method of using preferably 50 mol% or more can be illustrated. Alternatively, a tensile modulus of 5 GPa or more can be obtained by stretching the polyimide precursor film to increase the degree of orientation. In the present invention, not limited to these, it can be applied to all heat-resistant polymer films having a tensile elastic modulus of 5 GPa or more.

The seamless belt of the present invention has a high heat resistance having a linear expansion coefficient of −5 to 20 ppm / ° C., preferably −3 to 18 ppm / ° C., more preferably −2 to 14 ppm / ° C., and more preferably −1 to 9 ppm / ° C. Made of molecular film. Here, the linear expansion coefficient is an average value between room temperature and 300 ° C. When the linear expansion coefficient is less than this range, the feeding accuracy is lowered and the durability of the seamless belt is lowered. Due to friction during traveling or temperature rise due to heat generated from a power source or the like, the dimensions of the seamless belt change, and high-precision feeding becomes difficult. The problem here is not the amount of elongation due to the temperature of the belt itself, but mainly due to fluctuations in the amount of feed caused by slippage between the belt and the seamless belt due to its subtle expansion and contraction. On the other hand, when the seamless belt contracts, the tension applied to the seamless belt increases, and the belt itself and the surrounding mechanical parts are affected by the stress applied to the seamless belt itself and the stress applied to the feeding mechanism because the film has a high tensile elastic modulus. The lifespan of the product will be shortened.
In order to bring the coefficient of linear expansion of the heat-resistant polymer film into the above range, a method in which the constituent component having an ether bond in all components of the heat-resistant polymer film is 30 mol% or less, preferably 20 mol% or less, or A method using 30 mol% or more, preferably 50 mol% or more of a diamine component having a benzoxazole structure in all diamine components can be exemplified. By setting the component of the heat resistant polymer film as such a composition, the linear expansion coefficient can be reduced in the in-plane direction of the heat resistant polymer film constituting the seamless belt.

  The thickness of the seamless belt in the present invention is 1 μm to 1000 μm, preferably 3 to 700 μm, more preferably 10 to 500 μm, still more preferably 25 to 200 μm. When the thickness is too thin, the strength is weakened, and when it is thick, the flexibility is lowered. The thickness of the seamless belt can be controlled by the coating amount of the polyimide precursor solution.

A method for producing a seamless belt will be described by taking as an example the case where the heat-resistant polymer film is a polyimide film.
As a method for producing a seamless belt made of a polyimide film, a method in which a polyimide precursor solution is immersed in an outer peripheral surface of a cylindrical mold, a method in which the polyimide precursor solution is applied to an inner peripheral surface, a method in which centrifugation is performed, or a casting mold is filled. There is a method of expanding into a tubular shape by a method such as a method to form, bellow shape after drying the development layer, converting the polyamic acid to imide by heat treatment and recovering from the mold . In the production of the seamless belt, an appropriate treatment such as mold release treatment or defoaming treatment can be performed.

  In the present invention, a seamless belt made of a multilayer heat-resistant polymer film obtained by repeating the coating and drying step of the polyimide precursor solution may be used. Here, each layer can be assigned a function by blending a conductive filler or the like. It is also possible to provide a specific function by coating different components on the inside or outside of the seamless belt after the formation of the seamless belt.

  In the production of the seamless belt, the conditions for obtaining the polyimide precursor film by drying the polyamic acid applied to the cylindrical support are not particularly limited, and the temperature is exemplified by 70 to 150 ° C, preferably 80 to 120 ° C. The drying time is exemplified by 5 to 180 minutes, preferably 10 to 120 minutes, more preferably 30 to 90 minutes. A conventionally known drying apparatus that satisfies such conditions can be applied, and examples thereof include hot air, hot nitrogen, far infrared rays, and high frequency induction heating.

  In the seamless belt of the present invention, the heat-resistant polymer film constituting the seamless belt is held at 170 ° C. for 10 minutes in an inert gas atmosphere, then heated to 450 ° C. at 20 ° C./min, and further at 450 ° C. It is preferable that the weight reduction amount after the temperature is raised from 170 ° C. and held for 30 minutes at 450 ° C. when held for 30 minutes is 5% by weight or less. Such weight loss is preferably 3% by weight or less, more preferably 1.5% by weight or less, still more preferably 0.8% by weight or less, and even more preferably 0.5% by weight or less. It is preferable.

  When the heat-resistant polymer film is heated, moisture that has been absorbed first is released. Such moisture is almost completely released by holding at 170 ° C. for 10 minutes. Therefore, it can be considered that the subsequent weight loss is caused by other causes. In the present invention, it is considered that the main causes of the weight loss after the temperature rise from 170 ° C. until the holding at 450 ° C. for 30 minutes is completed are the low-molecular components having high boiling points remaining and moisture generated by the dehydration ring-closing reaction. . Even if the weight decreases due to any of these causes, if the weight decreases in such a temperature range, the durability of the seamless belt is greatly affected. In other words, the reduction of volatile components changes the secondary structure of the heat-resistant polymer film that forms the seamless belt, and also leads to shrinkage of the entire seamless belt, causing stress in the seamless belt and mechanical fatigue, which is a problem. It is.

  As a method for setting the weight reduction amount of the heat-resistant polymer film within the above range, for example, drying and dehydration ring-closing reaction in the forming process of a seamless belt are performed under control to increase drying efficiency and dehydration ring-closing reaction. It can be realized by increasing the rate. More specifically, heat treatment at a temperature of 300 ° C. or higher for 8 minutes or longer, more preferably 15 minutes or longer, and even more preferably 30 minutes or longer, or 400 ° C. or higher for 3 minutes or longer, preferably 5 minutes or longer, still more. Can be realized by performing a heat treatment for 9 minutes or more, or a heat treatment at 440 ° C. or more for 2 minutes or more, preferably 4 minutes or more, more preferably 7 minutes or more.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, each characteristic value in an Example was measured with the following method.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.

2. Thickness The thickness was measured using a micrometer (Finereuf, Millitron 1245D).
3. Tensile modulus, tensile breaking strength, and breaking elongation A seamless belt of a heat-resistant polymer film to be measured is a strip of 100 mm × 10 mm in the circumferential direction (hereinafter referred to as MD direction) and the width direction (hereinafter referred to as TD direction). The test piece was cut into pieces. Using a tensile tester (manufactured by Shimadzu Corp., Autograph (R) AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus, tensile strength, and rupture in each of the MD and TD directions. The elongation was measured.

4). Linear expansion coefficient (CTE)
Under the following conditions, the stretch rate in the MD direction and TD direction of the seamless belt of the heat-resistant polymer film to be measured was measured. The stretch ratio / temperature was measured at intervals of 30 ° C. to 15 ° C., this measurement was performed up to 300 ° C., and the average value of all measured values was calculated as CTE. The meanings of the MD direction and the TD direction are the same as in the measurement of “3.”
Device name: TMA4000S manufactured by MAC Science
Sample length; 20mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

5). Melting point, glass transition temperature Differential scanning calorimetry (DSC) was performed under the following conditions, and a melting point (melting peak temperature Tpm) and a glass transition point (Tmg) were determined according to JIS K7121.
Device name: DSC3100S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample weight; 4mg
Temperature rising start temperature: 30 ° C
Temperature rising end temperature: 600 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

6). Thermal decomposition temperature The sample to be measured was sufficiently dried, and thermobalance measurement (TGA) was performed under the following conditions. The temperature at which the weight of the sample decreased by 5% was regarded as the thermal decomposition temperature.
Device name: TG-DTA2000S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample weight: 10mg
Temperature rising start temperature: 30 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

7. Weight loss at 170-450 ° C.
Use the same equipment as the pyrolysis temperature,
From room temperature to 170 ° C. in argon at 20 ° C./min. The temperature was raised at 170 ° C. for 10 minutes, and then until 450 ° C., 20 ° C./min. Temperature rise at 450 ° C. for 30 minutes The change in weight was recorded under the above conditions, and after the temperature was raised from 170 ° C., the amount of weight reduction until the end of holding at 450 ° C. for 30 minutes was determined. The reference weight is the weight after holding at 170 ° C. for 10 minutes.

8). Evaluation as fixing belt The fixing machine of the laser printer LBP-350 manufactured by Canon was removed, the fixing belt was replaced with the seamless belt obtained in the example, reassembled, and then a continuous printing test of A4 paper was performed. The presence or absence of a paper jam and the fixing state of the image were observed.
9. Evaluation as a conveyor belt The obtained seamless belt can be replaced with an intermediate transfer belt, and the remaining belt can be adjusted with a dancer roll, and the bias voltage can be controlled separately. A continuous printing test of 5000 full-color images was carried out by incorporating it as a recording sheet conveying belt also serving as an intermediate transfer of a color printer CLW3310. The transfer state, color tone, and image color shift of the obtained printed matter were observed.

Example 1
<Polymerization of polyamic acid>
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 500 parts by weight of 5-amino-2- (p-aminophenyl) benzoxazole was charged. Next, 5000 parts by weight of N-methyl-2-pyrrolidone was added and completely dissolved, and then 485 parts by weight of pyromellitic dianhydride was added and stirred at a reaction temperature of 25 ° C. for 48 hours. A polyamic acid solution was obtained. The obtained solution had a ηsp / C of 3.8 dl / g.

<Manufacture of seamless belts>
The polyamic acid solution obtained on the inner surface of a cylinder having an inner diameter of 30 mm and a length of 230 mm was applied to a thickness of 500 μm with a dispenser and then rotated at 2500 rpm for 10 minutes to obtain a uniform coating film. Next, while rotating at 500 rpm, hot air of 120 ° C. was applied from the outside of the mold for 15 minutes, heated at 200 ° C. for 60 minutes, and then heated to 380 ° C. at a temperature increase rate of 5 ° C./min. After treating for a minute, it returned to room temperature, peeled from the metal mold | die, and obtained the target seamless belt. Table 1 shows the characteristics of the obtained seamless belt.

<Evaluation as fixing belt>
The fixing machine of the laser printer LBP-350 manufactured by Canon was removed, the fixing belt was replaced with the seamless belt obtained in Example 1, and the assembly was reassembled. Next, a continuous printing test of 5000 A4 sheets was performed. There was no paper jam and the image was in a good fixing state.

(Comparative Example 1)
A polyamic acid solution was obtained by dissolving 545 parts by weight of pyromellitic anhydride and 500 parts by weight of 4,4′-diaminodiphenyl ether in 5,000 parts by weight of dimethylacetamide and reacting in the same manner while maintaining the temperature at 20 ° C. or lower. Ηsp / C of the obtained polyamic acid solution was 2.0 dl / g. Thereafter, the same operation as in Example 1 was performed to obtain a seamless belt. Table 1 shows the characteristics of the obtained seamless belt.
Using the obtained seamless belt, evaluation as a fixing belt was performed in the same manner as in Example 1. As a result of the continuous printing test, a paper jam occurred when 2100 sheets were reached, and the test was interrupted. When the fixing machine was disassembled, it was found that wrinkles were generated on the seamless belt, and as a result, the paper was kinked and conveyed, causing the paper jam.

(Example 2)
Into 1000 g of N-methyl-2-pyrrolidone (also referred to as NMP), 40 g of dried carbon black (Mitsubishi Chemical Co., MA-100, particle size 22 nm) was charged and mixed in a ball mill for 6 hours at room temperature. A dispersion uniformly dispersed in NMP was obtained.
On the other hand, the same operation as in Example 1 was performed to obtain the same amount of polyamic acid solution. The obtained polyamic acid solution and an NMP dispersion of carbon black were mixed to obtain a polyamic acid solution containing carbon black.

  A polyamic acid solution containing carbon black obtained on the inner surface of a cylinder having an inner diameter of 400 mm and a length of 500 mm was applied with a dispenser to a thickness of 500 μm, and then rotated at 1500 rpm for 10 minutes to obtain a uniform coating film. Next, while rotating at 250 rpm, hot air of 120 ° C. was applied from the outside of the mold for 30 minutes, and then heated at 200 ° C. for 60 minutes, and then the temperature was increased to 380 ° C. at a temperature increase rate of 5 ° C./minute. After treating for a minute, the temperature was returned to room temperature, peeled off from the mold, and a seamless belt containing carbon black was obtained.

<Evaluation as a conveyor belt>
The obtained seamless belt was incorporated into a test machine in which a color printer CLW3310 manufactured by Fuji Xerox Co., Ltd. was modified as a recording sheet conveying belt also used as an intermediate transfer, and a continuous printing test for 5000 full-color images was performed. The obtained printed matter had a good color tone, and there was no printing failure, unclear image, or color shift.

(Comparative Example 2)
Using the polyamic acid solution obtained in Comparative Example 1, the same procedure as in Example 2 was followed to obtain a carbon black-containing seamless belt. Table 1 shows the characteristics of the obtained seamless belt. Using the obtained seamless belt, a continuous printing test as a conveying belt was conducted in the same manner as in Example 2. As a result, the color shift started to be noticeable from around 1000 sheets, and the situation was not improved until the 5000th sheet. After the test, the transfer unit was disassembled. Scratches were conspicuous on the inside of the seamless belt, and it was interpreted that the color misregistration occurred due to poor feeding due to slippage of the seamless belt during the test.

(Example 3)
Using the polyamic acid solution obtained in Example 1, the polyamic acid solution obtained on the inner surface of a cylinder having an inner diameter of 30 mm and a length of 230 mm was applied to a thickness of 500 μm with a dispenser, and then rotated at 2500 rpm for 10 minutes to obtain a uniform coated surface. Got. Next, while rotating at 500 rpm, hot air of 120 ° C. was applied from the outside of the mold for 15 minutes, heated at 220 ° C. for 60 minutes, returned to room temperature, and peeled from the mold to obtain a seamless belt. Table 1 shows the characteristics of the obtained seamless belt.
Evaluation was made as a fixing seamless belt in the same manner as in Example 1. As a result of the continuous printing test, there was no paper jam up to 4000 sheets, and the image was in a well-fixed state, but wrinkles started to be noticeable on the output paper from the time when it exceeded 4000 sheets, and partly The fixed image was disturbed. When the fixing machine was disassembled after the test was completed, a part of the seamless belt was distorted as contracted.

  The seamless belt of the present invention is composed of a heat-resistant polymer film having a high tensile elastic modulus and a low linear expansion coefficient. The stress on the seamless belt itself and the stress on the seamless belt drive system are reduced, resulting in high durability. In addition, because it is made of a heat-resistant polymer film that has a small weight loss at high temperature, the stress caused by temperature changes is small, and as a result, it is excellent in stability and durability even when used repeatedly at high temperatures, so high feeding accuracy Can be used for printing machines, printers, transport devices, etc. It is particularly useful as a transfer belt for a color printer.

Claims (3)

A seamless belt comprising a heat-resistant polymer film having a linear expansion coefficient of −5 ppm / ° C. to 20 ppm / ° C. and a tensile modulus of 5 GPa or more, wherein the heat- resistant polymer has an aromatic diamine having a benzoxazole structure; A seamless belt, which is a polyimide benzoxazole obtained by reacting with an aromatic tetracarboxylic acid anhydride .   The heat resistant polymer film was held at 170 ° C. for 10 minutes under an inert gas atmosphere, then heated to 450 ° C. at a rate of 20 ° C./min, and further increased from 170 ° C. when held at 450 ° C. for 30 minutes. The seamless belt according to claim 1, which is a heat-resistant polymer film having a weight reduction amount of 5% by weight or less until the end of holding at 450 ° C for 30 minutes.   The seamless belt according to claim 1, wherein the heat-resistant polymer film contains a conductive substance.