JP2009086087A - Endless belt for electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality endless belt for an electrophotographic apparatus having uniform mechanical and electric characteristics and also superior in rigidity, bending durability, and ductility. <P>SOLUTION: A base layer 1 of the endless belt for the electrophotographic apparatus is formed of a sea-island structure which includes a polyamideimide resin or a polyimide resin as a sea phase and non-silicone rubber particles as an island phase and which is made by applying a coating film of a dispersion liquid containing the non-silicone rubber particles dispersed in a polyamideimide resin solution or a precursor solution of polyimide resin. The ratio of the universal hardness of the sea phase and the island phase in the sea-island structure measured by a universal hardness tester is set by sea phase/island phase ≥10.0. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless belt for an electrophotographic apparatus, and more particularly, to an electrophotographic apparatus employing an electrophotographic technique such as a full color LBP (laser beam printer) or a full color PPC (plain paper copier). The present invention relates to an endless belt for electrophotographic equipment used for a transfer conveyance belt or the like.

  In general, endless belts (seamless belts) are widely used for electrophotographic equipment employing electrophotographic technology such as full color LBP and full color PPC for applications such as toner image transfer, paper transfer conveyance, and photoreceptor substrate. Yes. As such an endless belt, for example, a material obtained by blending a conductive resin black with a fluorine-based resin such as PVDF (polyvinylidene fluoride) into a cylindrical film is used.

  However, the conventional endless belt has a problem that the electric resistance value tends to vary in the belt, a problem that the belt is stretched over time when it is repeatedly used under tension, and further, the mechanical properties of the belt. Since the durability is insufficient, there is a problem that cracks and cracks are likely to occur over time.

Therefore, in order to improve these problems, for example, a semi-structured substrate having a sea-island structure in which a thermoplastic resin is used as a matrix (sea phase) and conductive rubber particles are used as domains (island phase). Among electroconductive belts (see Patent Document 1) and thermoplastic resins, in particular, an endless belt for an electrophotographic apparatus using a sea-island structure member having acrylic resin as a matrix and rubber particles as a domain (Patent Document 2). Have been proposed). In addition, as an endless belt with excellent rigidity and excellent bending durability and toughness, it has a sea-island structure in which a sea phase composed of polyamideimide resin or polyimide resin and an island phase composed of a polysiloxane compound are combined. One having a base layer (see Patent Document 3) has been proposed.
JP 2001-254022 A JP 2005-164673 A JP 2006-243146 A

  However, in Patent Documents 1 and 2, although the electrical properties of the obtained base layer (base material layer) are somewhat improved compared to the conventional ones, the rubber particles are uniformly dispersed in the thermoplastic resin as a matrix. However, there is a problem that electric characteristics still tend to vary. In both cases, the base layer is formed by melt molding such as extrusion molding, inflation molding, injection molding, etc., so there is a limit to surface smoothness and thickness uniformity, and by forming a weld line, that part However, there is a problem that differences in physical properties and electrical characteristics are likely to occur.

  On the other hand, Patent Document 3 discloses a method for obtaining a base layer by preparing a material for forming a sea-island structure as a solution and spray-coating the material on a mold. For example, there is a great expectation that a very excellent island phase uniform dispersion can be realized and problems associated with melt molding can be avoided.

  However, as a result of examining the method described in Patent Document 3 in detail, it has been found that there is still room for improvement in the particle size control and uniform dispersibility of the island phase.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-quality endless belt for electrophotographic equipment that has uniform mechanical characteristics and electrical characteristics and is excellent in rigidity, bending durability and toughness. And

  In order to achieve the above object, an endless belt for electrophotographic equipment of the present invention is an endless belt for electrophotographic equipment consisting of a single layer consisting of only a base layer or a plurality of layers including a base layer, wherein the base layer comprises a polyamideimide A dispersion obtained by dispersing non-silicone rubber particles in a resin solution or a polyimide resin precursor solution is formed into a coating film, and the polyamide-imide resin or polyimide resin is a sea phase and the non-silicone rubber particles are island phases. The ratio of the universal hardness (hereinafter simply referred to as “hardness”) measured by a universal hardness meter between the sea phase and the island phase in the sea-island structure is the sea-island structure. The phase / island phase ≧ 10.0 is set.

  That is, the present inventors obtain an endless belt for an electrophotographic apparatus having uniform mechanical properties and electrical properties and excellent rigidity, bending durability and toughness. We have earnestly studied the base layer (base layer) of the sea-island structure. As a result, a polyamideimide resin solution or a polyimide resin precursor solution containing a dispersion solution containing non-silicone rubber particles dispersed therein is formed into a coating film. A sea-island structure having particles as island phases, wherein the ratio of the hardness of the sea phase to the island phase in the sea-island structure measured by a universal hardness tester is: sea phase / island phase ≧ 10.0 As a result, the inventors have found that the intended purpose can be achieved, and have reached the present invention.

  Thus, the endless belt for electrophotographic equipment of the present invention has a base layer formed of a sea-island structure obtained by coating, and in particular, a sea phase made of a polyamide-imide resin or a polyimide resin. The island phase composed of non-silicone rubber particles is dispersed therein, and the hardness ratio between the sea phase and the island phase is set to a specific ratio. Therefore, according to this configuration, the island phase composed of the non-silicone rubber particles is very uniformly dispersed, thereby improving the excellent stress relaxation effect and bending durability and toughness (bench durability, etc.). Effects. As a result, it is possible to achieve both high durability and high rigidity of the endless belt for electrophotographic equipment, and the physical properties can be obtained very stably.

  Among the endless belts for electrophotographic equipment according to the present invention, in particular, the island phase is composed of acrylic acid-modified vulcanized rubber or carboxy-modified acrylonitrile-butadiene rubber. And the balance between the improvement effect of bending durability and toughness (bench durability, etc.) by the sea phase is extremely good.

  Similarly, in particular, the average particle size of the island phase in the sea-island structure is set within a range of 0.1 to 10 μm, and further, the sea phase and the island in the sea-island structure. The ratio of the phase to the island phase / (island phase + sea phase) = 0.1 to 30% by volume is also used for the stress relaxation effect by the island phase and the bending durability by the sea phase, respectively. The balance with the improvement effect of property and toughness (bench durability etc.) is very good.

  Next, an embodiment of the present invention will be described.

  The endless belt for electrophotographic equipment of the present invention (hereinafter abbreviated as “endless belt”) is composed of a belt material having a two-layer structure in which a surface layer 2 is directly formed on the outer peripheral surface of a base layer 1 as shown in FIG. ing. As shown schematically in FIG. 2, the base layer 1 is a so-called sea-layer in which island phases 4 composed of domain components (dispersed phases) are dispersed in a sea phase 3 composed of matrix components (continuous phases). It is formed by an island structure.

  Polyamideimide resin or polyimide resin is used as a matrix component constituting the sea phase 3. Among these, the polyamideimide resin (hereinafter referred to as “PAI resin”) is not particularly limited, and examples thereof include aliphatic PAI resins and aromatic PAI resins. Of these, aromatic PAI resins are preferably used because they are excellent in film mechanical properties.

  Examples of such PAI resins include those having a repeating structure represented by the following general formula (1) (that is, a molecular structure formed by a combination of a benzene ring, an imide group, and an amide group).

  The PAI resin is composed of, for example, an acid component such as trimellitic acid, its anhydride or acid chloride, and a diamine or diisocyanate such as N, N'-dimethylacetamide or N-methyl-2-pyrrolidone (NMP). It can manufacture by stirring in a polar solvent, heating to predetermined temperature (usually about 60-200 degreeC).

  Examples of the acid component used in the production of the PAI resin include trimellitic acid and its anhydride or acid chloride, benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid), and biphenyltetracarboxylic acid. Acid, biphenylsulfone tetracarboxylic acid, benzophenone tetracarboxylic acid, biphenyl ether tetracarboxylic acid, tetracarboxylic acid such as ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, oxalic acid, adipic acid, malonic acid, Aliphatic dicarboxylic acids such as sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), 1,4-cyclohexanedicarbo Acid, 1,3-cyclohexanedicarboxylic acid, 4,4'-dicyclohexylmethane dicarboxylic acid, dimer acid, and other alicyclic dicarboxylic acids, terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, naphthalenedicarboxylic acid, etc. Aromatic dicarboxylic acids can be mentioned. These may be used alone or in combination of two or more. Among these, trimellitic anhydride is preferably used in terms of reactivity, heat resistance, solubility, and the like.

  Examples of the diamine or diisocyanate used in the production of the PAI resin include aliphatic diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine, and diisocyanates thereof, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, Alicyclic diamines such as isophorone diamine, 4,4'-dicyclohexylmethane diamine, and diisocyanates thereof, m-phenylene diamine, p-phenylene diamine, 4,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl ether, 4 , 4'-diaminodiphenylsulfone, benzidine, o-tolidine, 2,4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine and the like and their diisocyanates Sulfonate, and the like. These may be used alone or in combination of two or more. Among these, 4,4'-diaminodiphenylmethane and its diisocyanate, 2,4-tolylenediamine and its diisocyanate, o-tolidine and its diisocyanate, isophoronediamine, from the viewpoints of heat resistance, mechanical properties, solubility, etc. And its diisocyanate are preferably used.

  The number average molecular weight (Mn) of the PAI resin is preferably in the range of 5,000 to 100,000, particularly preferably in the range of 10,000 to 50,000. The number average molecular weight (Mn) can be measured by a gel permeation chromatograph (GPC) method.

  Next, similarly, as a polyimide resin (hereinafter referred to as “PI resin”) that can be used as a matrix component constituting the sea phase 3, a repeating structure represented by the following general formula (2) (that is, a benzene ring) The molecular structure is not particularly limited as long as it has a molecular structure based on a combination of an imide group and an imide group.

  In the general formula (2), examples of the divalent organic group represented by R include aliphatic diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine, 1,4-cyclohexanediamine, and 1,3-cyclohexane. Alicyclic diamines such as diamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4 Examples thereof include diamine residues such as aromatic diamines such as' -diaminodiphenylsulfone, benzidine, o-tolidine, 2,4-tolylenediamine, 2,6-tolylenediamine, and xylylenediamine.

  The PI resin is classified into a thermoplastic PI resin and a thermosetting PI resin depending on the type of R (divalent organic group) in the repeating structure represented by the general formula (2). A thermosetting PI resin is preferably used because it is rigid and has excellent mechanical properties.

  The PI resin is, for example, an acid dianhydride and a diamine in a polar solvent such as N, N′-dimethylacetamide or N-methyl-2-pyrrolidone (NMP) at a low temperature (about 25). It is possible to obtain a polyimide precursor such as wholly aromatic polyamic acid by carrying out a polycondensation reaction with stirring at a temperature of not higher than [° C.] and then imidize it.

  Examples of the acid dianhydride include pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPTA), oxydiphthalic dianhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA). , Benzenetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, and the like. These may be used alone or in combination of two or more. In addition, as said diamine, the thing similar to what was illustrated by the description regarding the above-mentioned PAI resin is used.

  On the other hand, as the domain component constituting the island phase 4, non-silicone rubber particles are used. The non-silicone rubber particles are not particularly limited as long as they are particles made of rubber other than silicone rubber, but the hardness of the rubber component constituting the rubber particles and the resin constituting the sea phase 3 are not limited. The hardness ratio of the components must be set so that the sea phase / island phase ≧ 10.0. That is, if the difference between the hardness of the sea phase 3 and the hardness of the island phase 4 is smaller than the above ratio, even if the island phase 4 is evenly dispersed, the stress relaxation effect by the island phase 4 and the bending durability / toughness This is because the improvement effect is not sufficiently exhibited.

  Examples of the material of the rubber component include diene rubbers such as natural rubber (NR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and hydrogenated products thereof, ethylene- Propylene rubber (EPDM, EPM), butyl rubber (IIR), isobutylene-aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer, brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl- IIR), bromide of isobutylene-paramethylstyrene copolymer (BIMS), chloroprene rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), polysulfide rubber, fluororubber, etc. Or these acrylics Modified product, maleic acid-modified products, carboxy-modified products and the like. These may be used alone or in combination of two or more. Of these, acrylic acid-modified vulcanized rubber, carboxy-modified NBR rubber, and the like are particularly preferably used.

  In addition, the said base layer 1 (refer FIG. 1) can be made to contain a conductive filler, a phosphorus containing polyester-type resin, etc. as an arbitrary component. In addition to these components, an organic solvent such as N, N-dimethylformaldehyde (DMF), toluene, and acetone, and a normal filler such as calcium carbonate can be contained as necessary.

The conductive filler is not particularly limited. For example, conductive powder such as carbon black and graphite, metal powder such as aluminum powder and stainless powder, conductive zinc oxide (c-ZnO), and conductive titanium oxide. Conductive metal oxides such as (c-TiO ₂ ), conductive iron oxide (c-Fe ₃ O ₄ ), and conductive tin oxide (c-SnO ₂ ), quaternary ammonium salts, phosphate esters, sulfonates Ionic conductive agents such as aliphatic polyhydric alcohols and aliphatic alcohol sulfate salts. These may be used alone or in combination of two or more.

  In addition, the phosphorus-containing polyester resin preferably has a phosphorus content in the range of 3 to 15% by weight of the entire phosphorus-containing polyester resin, particularly preferably in the range of 5 to 10% by weight. It is what is inside. It is preferable for the phosphorus content to be in such a range because flame retardancy is improved.

  Next, the material (surface layer material) used for forming the surface layer 2 is not particularly limited, and examples thereof include silicone resins, fluorine resins, urethane resins, acrylic resins, polyamide resins, and the like. These may be used alone or in combination of two or more. Among these, in consideration of workability, a liquid or solvent-soluble type is preferably used. In addition, for the purpose of preventing dirt, improving the strength of the coating film, or improving the adhesion, a modified resin material may be used, for example, a modified acrylic resin. The modified acrylic resin is not particularly limited as long as it is based on the molecular structure of the acrylic resin and is modified with other resins or resin components. Among them, silicone-modified acrylic resins are preferably used. .

  Examples of the silicone-modified acrylic resin include a silicone graft acrylic resin. The silicone graft acrylic resin is not particularly limited as long as the silicone resin is graft polymerized with the acrylic resin (main chain). Specific examples of this silicone graft acrylic resin include Saimak US-350 manufactured by Toagosei Co., Ltd.

  In the surface layer material described above, the resin material is subjected to resin crosslinking using a resin crosslinking agent such as isocyanate resin, amino resin, phenol resin, xylene resin, photosensitive monomer or polymer. An ultraviolet curable material mixed with a polymerization initiator may be used.

  The endless belt shown in FIG. 1 can be manufactured using these materials as follows, for example. In this example, a PAI resin is used as a matrix component constituting the sea phase 3 of the base layer 1.

[Preparation of material solution for base layer-when PAI resin is used]
First, a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube is prepared, and a predetermined amount of an acid component such as trimellitic anhydride and a diisocyanate such as diphenylmethane diisocyanate (MDI) is mixed. A polar solvent such as is charged and heated to a predetermined temperature (preferably 130 to 150 ° C.) over a predetermined time (preferably 1 to 3 hours) with stirring in a nitrogen stream. Next, after reacting at a predetermined temperature (preferably 130 to 150 ° C.) for a predetermined time (preferably about 3 to 5 hours), the reaction is stopped to prepare a PAI resin solution. Next, a predetermined amount of non-silicone rubber particles are added to the PAI resin solution and mixed by blade stirring at room temperature (usually about 25 ° C.). Subsequently, carbon black or the like is appropriately blended in this solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer material.

[Formation of base layer 1]
And after spray-coating the said base layer material on the surface of a metal mold | die (cylindrical base | substrate), this coating film is predetermined temperature (preferably 150-300 degreeC) for predetermined time (preferably 3-6 hours). ) By drying, the base layer 1 (see FIG. 1) is formed on the outer peripheral surface of the mold. As shown in FIG. 2, the obtained base layer 1 is formed by a sea-island structure in which island phases 4 made of non-silicone rubber particles are uniformly dispersed in a sea phase 3 made of PAI resin. Has been.

[Preparation of surface layer material solution]
On the other hand, a surface layer material solution is prepared by appropriately blending a surface layer material with, for example, a modified acrylic resin and an organic solvent such as DMF, toluene, and acetone and mixing them with a stirring blade. However, since it is preferable to use different types of organic solvents for the adjacent layer forming material, the organic solvent used for the surface layer material and the organic solvent used for the base layer material are different from each other. It is preferable to use different types.

[Formation of surface layer 2]
Then, the surface layer 2 (see FIG. 1) is formed by coating the surface layer material solution on the surface of the base layer 1 formed on the outer peripheral surface of the cylindrical base by the dipping method and drying it under predetermined conditions.

[Demolding]
Then, air is blown between the base layer 1 on which the surface layer 2 is laminated and the cylindrical substrate to peel off the laminate of the base layer 1 and the surface layer 2 from the cylindrical substrate. An endless belt having a two-layer structure of 1 and surface layer 2 is obtained.

  The endless belt thus obtained has a base layer obtained by forming a coating, and a sea phase in which island phases composed of non-silicone rubber particles are dispersed in a sea phase composed of polyamideimide resin or polyimide resin. It is formed by an island structure, and the hardness ratio between the sea phase and the island phase is set to a specific ratio. Therefore, according to this configuration, the island phase composed of the non-silicone rubber particles is very uniformly dispersed as compared with that obtained by melt molding or the like, thereby providing an excellent stress relaxation effect and bending durability. Effect of improving the property and toughness (bench durability, etc.). As a result, it is possible to achieve both high durability and high rigidity of the endless belt for electrophotographic equipment, and the physical properties are very stable.

  In the above production method, when a PI resin is used as a matrix component constituting the sea layer 3 (see FIG. 2), a base layer material solution can be prepared, for example, as follows. The other steps are the same as in the above production method.

[Preparation of material solution for base layer-when PI resin is used]
First, a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube was prepared, and acid dianhydride such as pyromellitic dianhydride (PMDA) and 4,4′-diaminodiphenyl ether (ODA). A predetermined amount of a diamine such as NMP is added, a polar solvent such as NMP is added, and the mixture is allowed to react at a temperature below room temperature (usually about 25 ° C.) for a predetermined time (usually about 3 hours) with stirring in a nitrogen stream. Then, the reaction is stopped to prepare a polyamic acid solution that is a precursor of PI. In this case, if the reaction is performed at a temperature exceeding normal temperature, imidization proceeds and a tendency to become insoluble in a polar solvent such as NMP is observed. Therefore, the reaction is preferably performed at a temperature equal to or lower than normal temperature. Next, a predetermined amount of non-silicone rubber particles is added to the polyamic acid solution and mixed by blade stirring at room temperature (usually about 25 ° C.). Subsequently, carbon black or the like is appropriately blended in this solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer material.

  Further, in the above production method, the coating of the base layer material solution for forming the base layer 1 may be a method of coating the solution in a film form, such as dip pink and centrifugal molding, in addition to the spray coating described above. Although not particularly limited, it is preferable to employ the vertical spiral spray coating described in Japanese Patent No. 3855896. That is, when spray coating is performed by this method, as shown in FIG. 3A, the cylindrical base 10 that can rotate in the circumferential direction and the axial direction of the cylindrical base 10 at a position close to the outer peripheral surface thereof. And a nozzle 11 that can move along Then, the cylindrical substrate 10 is rotated in the circumferential direction in a vertical state, and in this state, the base layer material 12 is discharged from the nozzle 11 toward the outer peripheral surface of the cylindrical substrate 10 in the axial direction. As shown in FIG. 3B, a coating film that covers the outer peripheral surface of the cylindrical substrate 10 can be obtained by spirally applying to the outer peripheral surface of the cylindrical substrate 10.

  According to this method, when the base layer 1 of the present invention is formed, the uniform dispersion of the non-silicone rubber particles in the base layer material is not impaired. Therefore, in combination with the characteristic configuration of the base layer of the present invention, An endless belt with excellent mechanical and electrical properties can be obtained.

  In the present invention, the average particle size of the island phase 4 of the base layer 1 is preferably in the range of 0.1 to 10 μm, particularly preferably in the range of 0.5 to 5 μm. That is, when the average particle size of the island phase 4 is less than 0.1 μm, there are too few stress relaxation sites, so that the strength increasing effect tends to be poor, and conversely, the average particle size of the island phase 4 exceeds 10 μm. This is because the rigidity (tensile modulus) tends to decrease.

  The method for measuring the average particle diameter of the island phase 4 is not particularly limited. For example, each island phase 4 is observed with a scanning electron microscope (SEM), a scanning probe microscope (SPM), or the like. It can be calculated by measuring the diameter and determining the average value of the particle diameters.

  In the present invention, the ratio between the sea phase 3 and the island phase 4 of the base layer 1 is preferably set to be island phase / (island phase + sea phase) = 0.1 to 30% by volume, particularly preferably. Is in the range of 0.5 to 10% by volume. That is, if the ratio of the island phase 4 is less than the above range, the stress relaxation site due to the island phase 4 is too small, and thus the strength increasing effect tends to be poor. It is because the tendency for the rigidity of the base layer 1 to fall will be seen when more than the range of this.

  In addition, as a method for obtaining the ratio between the sea phase 3 and the island phase 4 on a volume basis, for example, a method of binarizing the constituent parts of the sea phase 3 and the island phase 4 using a microscope is given. be able to.

  In the above production method, the method for forming the surface layer 2 is not limited to the dipping method, and an appropriate method such as spray coating or centrifugal molding can be selected as in the method for forming the base layer 1. .

  And although the thickness of each layer of the endless belt of this invention is set suitably according to the use of a belt, the thickness of the base layer 1 is in the range of 30-300 micrometers normally, Preferably it is the range of 50-200 micrometers. Is within. The thickness of the surface layer 2 is preferably in the range of 0.1 to 10 μm, particularly preferably in the range of 0.5 to 5 μm.

  The endless belt of the present invention preferably has an inner peripheral length of 90 to 1500 mm and a width of about 100 to 500 mm. That is, if the size is set within the above range, the size is suitable for use in an electrophotographic copying machine or the like.

  The endless belt of the present invention is not limited to the two-layer structure in which the surface layer 2 is directly formed on the outer peripheral surface of the base layer 1 as shown in FIG. For example, a single-layer structure consisting of only the base layer 1, a three-layer structure in which a thermoplastic resin layer or a rubber elastic layer is interposed between the base layer 1 and the surface layer 2, and a thermoplastic resin between the base layer 1 and the surface layer 2 A four-layer structure in which both a layer and a rubber elastic layer are interposed may be used. However, even in these cases, the base layer 1 must be formed of the aforementioned sea-island structure.

  The material for the thermoplastic resin layer that can be interposed between the base layer 1 and the surface layer 2 is not particularly limited, but may be a solvent such as methyl ethyl ketone (MEK), toluene, or the like, together with the thermoplastic resin. Is used. In addition, the conductive filler as described above may be blended in the thermoplastic resin layer material.

  The thermoplastic resin is not particularly limited, and examples thereof include polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and ethylene-tetrafluoroethylene copolymer (ETFE). Fluorine resin, polyethylene resin, polystyrene resin, acrylic resin, polycarbonate (PC) resin, polyamide resin, ethylene-vinyl acetate copolymer (EVA) resin, ethylene-ethyl acrylate copolymer ( EEA) resin and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use a fluorine-based resin such as PVDF from the viewpoint of excellent flame retardancy.

  Furthermore, the rubber elastic layer material that can be interposed between the base layer 1 and the surface layer 2 includes a rubber material and a vulcanizing agent, and a vulcanization accelerator, a solvent, a processing aid, and an aging as necessary. An inhibitor or the like is used. Note that the conductive elastic filler as described above may be blended in the rubber elastic layer material.

  The rubber material is not particularly limited, and chlorinated polyethylene rubber (CPE), chloroprene rubber (CR) and the like are used from the viewpoint of flame retardancy. Among these, the optimum material is selected according to the electrical characteristics, elasticity, and durability required for the endless belt for electrophotographic equipment.

  The endless belt of the present invention is suitably used for applications such as toner image transfer, paper transfer conveyance, and photoreceptor substrate in an electrophotographic apparatus employing electrophotographic technology such as full color LBP and full color PPC. However, the present invention is not limited to this. For example, it can be used for a transfer belt of a monochrome electrophotographic copying machine which is not full color.

  Next, examples of the present invention will be described together with comparative examples. The present invention is not limited to the following examples.

First, prior to Examples and Comparative Examples, the following materials were prepared.
<PAI resin material>
・ Trimellitic anhydride (TMA)
Mn: 192.12
・ Diphenylmethane diisocyanate (MDI)
Millionate MT (Mn: 250.26) manufactured by Nippon Polyurethane

<PI resin material>
・ Pyromellitic dianhydride (PMDA)
Daicel Chemical Industries, Ltd. (Mn: 218)
・ 4,4'-diaminodiphenyl ether (ODA)
Wakayama Seika Kogyo Co., Ltd. (Mn: 200.2)

<Non-silicone rubber particles>
・ Acrylic acid-modified vulcanized rubber 1
Average particle size: 1.0 μm China Petrochemical Co., Ltd., Narpow VP-301 classification product, acrylic acid modified vulcanized rubber 2
Average particle diameter: 0.1 μm, China Petrochemical Co., Ltd., Narpow VP-301 classification product, acrylic acid modified vulcanized rubber 3
Average particle size: 10.0 μm, China Petrochemical Co., Ltd., Narpow VP-301 classification product, acrylic acid modified vulcanized rubber 4
Average particle size: 1.0 μm, the acrylic acid-modified vulcanized rubber 1 was cured (deteriorated) by heating at 300 ° C. for 20 hours.
・ Acrylic acid-modified vulcanized rubber 5
Average particle size: 1.0 μm, the acrylic acid-modified vulcanized rubber 1 is heated (350 ° C. × 20 hours) and cured (deteriorated).
Carboxy-modified NBR rubber Average particle size: 1.0 μm, classified by Narpow VP-502, manufactured by China Petrochemical Co., Ltd. Carboxylated SBR rubber Average particle size: 1.0 μm, classified by Narpow VP-201, manufactured by China Petrochemical Co., Ltd.

<Conductive filler>
・ Carbon Black Show Black Ca220, Show Black N220

[Example 1]
(1) Preparation of base layer material solution In a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube, 38 parts by weight of trimellitic anhydride (TMA) (hereinafter abbreviated as “part”) and MDI50 And 200 parts of NMP solvent were added, the temperature was raised to 130 ° C. over 1 hour with stirring in a nitrogen stream, and the reaction was stopped at 130 ° C. for about 5 hours, and then the reaction was stopped, and the PAI-NMP solution ( Solid content concentration: 26% by weight) was prepared. Next, 3 parts of acrylic acid-modified vulcanized rubber 1 was added to 100 parts of this PAI-NMP solution, and mixed at room temperature (25 ° C.) with blade stirring. Subsequently, 10 parts of carbon black was added to this solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer material solution.

(2) Production of endless belt A mold (cylindrical substrate) was prepared, and the surface was coated with the above by the method of spiral spray coating shown in FIGS. 3 (a) and 3 (b) (see Japanese Patent No. 3855896). The base material solution was spray coated. And after heating up from normal temperature to 250 degreeC over 2 hours, it heat-processed at 250 degreeC for 1 hour. Next, by blowing air between the base layer and the cylindrical base body, the cylindrical base body was extracted, and an endless belt having a single layer structure consisting of only the base layer (thickness: 80 μm) was produced. The hardness of the PAI resin constituting the sea phase in the obtained base layer is 123, and the hardness of the acrylic acid-modified vulcanized rubber 1 also constituting the island phase is 1.4, and the hardness ratio (sea phase / island phase) ) Is 90.

[Examples 2 to 9]
The types and material compositions of the non-silicone rubber particles were changed as shown in Tables 1 and 2 below. Otherwise, a base layer material solution was prepared in the same manner as in Example 1, and the resulting base layer material solution was used to form only the base layer (thickness: 80 μm) in the same manner as in Example 1. An endless belt having a single layer structure was produced. In the base layer, those using acrylic acid-modified vulcanized rubbers 2 and 3 have the same hardness as that of acrylic acid-modified vulcanized rubber 1, and the hardness ratio of the sea phase / island phase is as follows. Same as Example 1. On the other hand, since the hardness of the carboxy-modified NBR rubber is 1.8 and the hardness of the carboxylated SBR rubber is 2.0, the hardness ratio of the sea phase / island phase in Examples 2 and 3 is 70 and 60, respectively. It is.

Example 10
(1) Preparation of base layer material solution In a reaction vessel equipped with a stirrer, nitrogen introduction tube, thermometer, and cooling tube, 44 parts of pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) ) 40 parts and 200 parts of NMP solvent were charged, and after stirring for 3 hours at a temperature not higher than room temperature (25 ° C.) with stirring in a nitrogen stream, the precursor was stopped by stopping the reaction. A polyamic acid-NMP solution (solid content concentration: 26% by weight) was prepared. Next, 0.1 part of dimethyl silicone oil was added to this polyamic acid-NMP solution and mixed by blade stirring at room temperature. Subsequently, 10 parts of carbon black was added to this solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer material solution.

(2) Production of endless belt A mold (cylindrical substrate) was prepared, and the surface was coated with the above by the method of spiral spray coating shown in FIGS. 3 (a) and 3 (b) (see Japanese Patent No. 3855896). The base material solution was spray coated. And after heating up from normal temperature to 300 degreeC over 2 hours, it heat-processed at 300 degreeC for 1 hour. Next, by blowing air between the base layer and the cylindrical base body, the cylindrical base body was extracted, and an endless belt having a single layer structure consisting of only the base layer (thickness: 80 μm) was produced. In the base layer, the hardness of the PI resin constituting the sea phase is 160, the hardness of the acrylic acid-modified vulcanized rubber 1 also constituting the island phase is 1.4, and the hardness ratio (sea phase / island phase) is , 110.

[Examples 11 to 14]
The material composition was changed as shown in Table 3 below. Otherwise, a base layer material solution was prepared in the same manner as in Example 10 above, and the resulting base layer material solution was used to form only the base layer (thickness: 80 μm) in the same manner as in Example 10 above. An endless belt having a single layer structure was produced.

Example 15
In preparing the base layer material solution, the acrylic acid-modified vulcanized rubber 4 was used as rubber particles. Other than that was carried out similarly to Example 1, and produced the endless belt of the single layer structure which consists only of base layers (thickness: 80 micrometers). The hardness of the acrylic acid-modified vulcanized rubber 4 constituting the island phase of this base layer was 12, and the hardness ratio of the sea phase / island phase was 10.

Example 16
(1) Preparation of base layer material solution A base layer material solution was prepared in the same manner as in Example 1.

(2) Preparation of material solution for surface layer 100 parts of silicone graft acrylic resin (Saimak US-350, manufactured by Toagosei Co., Ltd.) and 500 parts of toluene solvent were mixed and mixed with a stirring blade to obtain a material solution for surface layer. Prepared.

(3) Production of endless belt A mold (cylindrical substrate) was prepared, and a base layer was formed on the surface in the same manner as in Example 1. Then, the surface layer material solution was dipped on the surface. Coating. Then, after drying, the air is blown between the base layer and the cylindrical base body to extract the cylindrical base body, and the surface layer (thickness: 1 μm) is formed on the surface of the base layer (thickness: 80 μm). An endless belt having a structure was produced.

Example 17
The spray coating method was not a vertical spiral spray coating, but a general spray coating in which coating was performed with the rotation axis of a mold (cylindrical substrate) in the horizontal direction. Other than that was carried out similarly to Example 1, and produced the endless belt of the single layer structure which consists only of base layers (thickness: 80 micrometers).

[Comparative Example 1]
In the preparation of the base layer material solution, the acrylic acid-modified vulcanized rubber 5 was used as non-silicone rubber particles. Other than that was carried out similarly to Example 1, and produced the endless belt of the single layer structure which consists only of base layers (thickness: 80 micrometers). The hardness of the acrylic acid-modified vulcanized rubber 5 constituting the island phase of the base layer is 15, and the hardness ratio of the sea phase / island phase is 8.

[Comparative Examples 2 and 3]
The material composition was changed as shown in Table 5 below. Otherwise, a base layer material solution was prepared in the same manner as in Example 1, and the resulting base layer material solution was used to form a single layer consisting of only the base layer (thickness: 80 μm) in the same manner as in Example 1. An endless belt having a structure was produced.

[Comparative Example 4]
In preparing the base layer material solution, dimethyl silicone oil shown in Table 5 below was used in place of the non-silicone rubber particles. Other than that was carried out similarly to Example 1, and produced the endless belt of the single layer structure which consists only of base layers (thickness: 80 micrometers).

  The properties shown below of the endless belt sea-island structures of Examples and Comparative Examples thus obtained were measured by the following methods and evaluated according to the following criteria. These results are also shown in Tables 1 to 5 below.

[Hardness ratio of sea phase / island phase]
The hardness of the resin or rubber alone constituting each phase was measured with a universal hardness meter, and the hardness ratio was calculated.

[Ratio of island phase / (island phase + sea phase) (volume%)]
The components of the sea and island phases were binarized using a microscope.

[Average particle size of island phase]
About the sea-island structure of the base layer of the endless belt, the average particle diameter of the island phase was measured using SEM (manufactured by Hitachi High-Technologies Corporation, S-3000N).

[Tensile modulus, fracture strain]
In accordance with JIS K7127, the tensile modulus and breaking strain were measured. The tensile speed was 10 ± 2.0 mm per minute.

[Number of MIT (flexibility)]
Each endless belt was cut into a strip of 15 mm x 150 mm, and subjected to an MIT test using a MIT fatigue resistance tester (Folding Endurancester MIT-D, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in a laboratory environment (25 ° C x 45% RH). And the number of MIT was measured. The test conditions were a load of 1.0 kg with a spring interposed, a repetition rate of 175 cycles / min, and a swing angle of 135 ° (both left and right). The number of MITs serves as an index for evaluation of bending resistance, and the greater the number of MITs, the better the bending resistance.

[Bench durability test]
Two metal rollers having a diameter of 13 mm were prepared, and one metal roller was fixed on the table in a state where an endless belt (width 150 mm) was stretched between the two metal rollers. Next, the other metal roller not fixed to the table is placed at the end of the table, and 2 kg of weight is suspended from each end of the metal roller (total load 4 kg), and the laboratory environment (25 ° C x 40% RH), the endless belt was driven to rotate. Then, the cumulative number of revolutions until a crack was confirmed on the endless belt was measured.

  From the above results, in all the examples, the polyamide imide resin or the polyimide resin is the sea phase 3, the non-silicone rubber particles are the island phase 4, and the hardness ratio (sea phase / island phase) of both is 10.0. Since the base layer 1 having the special configuration described above is formed by coating, the special island phase 4 is uniformly dispersed and has excellent quality. However, the base layer 1 formed by horizontal spiral spray coating (Product of Example 17) is slightly inferior to the one formed by vertical spiral spiral eve spray coating.

  On the other hand, since the hardness ratio between the sea phase 3 and the island phase 4 is out of the scope of the present invention, the comparative example 1 product has a small stress relaxation effect and the like, compared with the conventional product, for example, the comparative example 4 product. The quality is not excellent. Further, in Comparative Example 2, the base layer 1 is formed only from the PAI resin and does not form a sea-island structure, and the bending resistance and bench durability are inferior to those of the Example 1 product. In the product, the base layer 1 is formed only from the PI resin and does not form the sea-island structure, and the bench durability is inferior to the product of Example 10. Furthermore, although the comparative example 4 goods are what formed the base layer 1 by coating like the example goods, since the structure of a sea-island structure differs, the quality is inferior compared with an example goods. .

  The endless belt for an electrophotographic apparatus of the present invention is suitable for an intermediate transfer belt, a paper transfer conveyance belt, etc. in an electrophotographic apparatus employing an electrophotographic technology such as a full color LBP (laser beam printer) or a full color PPC (plain paper copier). Used for.

It is a fragmentary sectional view which shows an example of the endless belt for electrophotographic apparatuses of this invention. It is typical explanatory drawing of the sea-island structure which comprises the base layer of this invention. (A), (b) is explanatory drawing of spray coating suitable for forming the base layer of this invention.

Explanation of symbols

1 base layer 2 surface layer

Claims (4)

  Endless belt for electrophotographic equipment consisting of a single layer consisting of only a base layer or a plurality of layers including a base layer, wherein the base layer contains non-silicone rubber particles dispersed in a polyamideimide resin solution or a polyimide resin precursor solution The dispersion is formed into a coating film, and is formed of a sea-island structure having a polyamide-imide resin or a polyimide resin as a sea phase and the non-silicone rubber particles as an island phase. An endless belt for electrophotographic equipment, characterized in that the ratio of the universal hardness measured by a universal hardness meter between the sea phase and the island phase is set to sea phase / island phase ≧ 10.0.   The endless belt for an electrophotographic apparatus according to claim 1, wherein the island phase is composed of acrylic acid-modified vulcanized rubber or carboxy-modified acrylonitrile-butadiene rubber.   The endless belt for an electrophotographic apparatus according to claim 1 or 2, wherein an average particle size of the island phase in the sea-island structure is set within a range of 0.1 to 10 µm.   The ratio of the sea phase to the island phase in the sea-island structure is set to be island phase / (island phase + sea phase) = 0.1 to 30% by volume. The endless belt for electrophotographic equipment according to one item.

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