JP2010072220A - Endless belt for electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt for an electrophotographic apparatus which has sufficient glossiness, uniformizes the glossiness of the surface of the belt, and is excellent in mechanical strength and transfer ability. <P>SOLUTION: The endless belt for the electrophotographic apparatus is made of a surface layer material in which a base layer 1 contains denatured polyamidoimide resin using (A) to (C) described bellow and a surface layer 2 contains (D) to (F) and satisfies the characteristics (α) and (β) described below. (A) An aromatic isocyanate compound. (B) An anhydride of aromatic polycarboxylic acid. (C) A carboxylic acid with polymer at both terminals. (D) At least two types of acrylic resin. (E) At least one selected from a group consisting of fluorinated carbon resin, denatured acrylic resin, and silicone resin. (F) A carbon black. (α) The weight ratio of (D) to (E) is (D)/(E)=80/20 to 97/3. (β) The sum of the products of the glass transition points of acrylic resins (D) and the proportion of the contents of the corresponding acrylic resins (D) to the total of the (D) and (E) is from 2,500-5,000. <P>COPYRIGHT: (C)2010,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, in an electrophotographic apparatus employing electrophotographic technology such as full-color LBP and full-color PPC, an endless belt (seamless belt) such as an intermediate transfer belt is used for applications such as toner image transfer, paper transfer conveyance, and photoreceptor substrate. ) Is frequently used. In particular, an intermediate transfer belt that requires high image quality is required to have improved functions such as film thickness uniformity from the viewpoint of dimensional accuracy, surface-side surface resistance from the viewpoint of electrical characteristics, and glossiness from the viewpoint of surface characteristics.

  Conventionally, as an endless belt, one having a single layer structure obtained by centrifugally molding a material containing a conductive agent (carbon black or the like) in polyimide resin or polyamideimide resin is used from the viewpoint of film thickness accuracy and physical properties. It has been. However, in the single layer structure, for example, the volume resistance and the surface resistance cannot be individually controlled. In general, the electrical characteristics are controlled by the amount of conductive agent, but in the case of a single layer structure, the volume resistance and the surface resistance are linked while maintaining a certain relationship, and the surface resistance on the front and back of the belt is approximately the same. Expresses resistance. In the case of a single layer structure, the relationship of electrical characteristics can be slightly changed by changing the type of conductive agent, additives, and the like. Moreover, since the manufacturing method of the belt having the single layer structure is centrifugal molding, the mold surface becomes the toner transfer surface. Since the toner transfer surface is a mold surface at the time of molding, it is difficult to control the coefficient of friction, and the conductive agent is unevenly distributed on the surface side of the belt due to centrifugal force. There are many conductive paths and transfer dust tends to occur. The intermediate transfer belt has a surface resistance characteristic on the back side of the belt through which an electric current for securing a transfer electric field in the primary transfer area is passed, a surface resistance characteristic on the belt surface that eliminates transfer dust and leaves no residual charge, and a residual charge. Individual characteristics, such as volume resistance characteristics that do not leave a gap, are necessary, but it is practically difficult to realize all these required characteristics with a single-layer structure. The actual situation is adjusting with peripheral parts.

Therefore, it has been proposed to provide a surface layer with a high resistance on the surface of the base layer (base layer), but the glossiness is lowered and the sensitivity for detecting the presence or absence of toner is lowered. To solve such a problem, an endless belt having a surface layer after rubbing the surface of the base layer has been proposed (Patent Document 1).
JP 2004-251978 A

  However, since the thing of the said patent document 1 requires a rubbing process, there exists a difficulty that the number of processes increases. In recent years, in order to improve image quality and speed, it is required to improve the required properties such as film thickness uniformity, surface-side surface resistance, and glossiness, and particularly to improve glossiness. The thing of the said patent document 1 has room for improvement in these points.

  In addition, when an endless belt is used as an intermediate transfer belt or the like incorporated in an electrophotographic apparatus, if the belt itself is inferior in mechanical strength, the belt is cracked and cannot function as an electrophotographic apparatus. . Furthermore, when a belt is mounted in an electrophotographic apparatus and toner is transferred, the toner density on the belt is read by reflection of an optical sensor. At that time, a number of sensors are arranged in the belt axis direction, and the belt itself is read. Since the density correction is performed in comparison with the glossiness of the belt, if the glossiness on the belt surface is not uniform, there is a problem in that reading is abnormal and the image quality is affected.

  In this way, there is no endless belt for electrophotographic equipment that has sufficient glossiness, can achieve uniform glossiness on the belt surface, and has excellent mechanical strength (bending durability) and toner transferability. However, there is a long-awaited appearance of an endless belt for electrophotographic equipment that meets all of these requirements.

  The present invention has been made in view of such circumstances, has sufficient glossiness, can achieve uniform glossiness on the belt surface, and is excellent in mechanical strength (bending durability) and toner transferability. Another object of the present invention is to provide an endless belt for electrophotographic equipment.

In order to achieve the above object, the endless belt for electrophotographic equipment of the present invention is an endless belt for electrophotographic equipment in which a surface layer is formed on the outer peripheral surface of the base layer, and the base layer comprises the following (A) to (A) to While containing the modified polyamideimide resin using (C), the surface layer is made of a surface layer material containing the following (D) to (F), and has the following characteristics (α) and (β): It is configured to satisfy.
(A) An aromatic isocyanate compound.
(B) An aromatic polycarboxylic acid anhydride.
(C) Carboxylic acid both terminal polymer.
(D) At least two kinds of acrylic resins.
(E) At least one selected from the group consisting of a fluororesin, a modified acrylic resin, and a silicone resin.
(F) Carbon black.
(Α) The mixing ratio of (D) and (E) is in a weight ratio of (D) / (E) = 80/20 to 97/3.
(Β) The sum of the products of the glass transition point of each acrylic resin (D) and the content of each acrylic resin (D) in the total amount of (D) and (E) is 2500 to 5000. Is set in the range.

  In other words, the inventors of the present invention are endless for electrophotographic apparatus having sufficient glossiness, uniform glossiness on the belt surface, excellent mechanical strength (bending durability) and toner transferability. In order to obtain a belt, I did intensive research. Then, research on an endless belt for an electrophotographic apparatus in which a surface layer is formed on the outer peripheral surface of a base layer containing a modified polyamideimide resin has been continued with a focus on surface layer materials. As a result, it contains at least two kinds of acrylic resins (D component), at least one selected from the group consisting of fluororesin, modified acrylic resin and silicone resin (E component), and carbon black (F component). It is a material for the surface layer, and while setting the weight ratio of the D component high, the sum of the products of the glass transition point of each acrylic resin (D component) and the content ratio of each acrylic resin (D component), It has been found that when the range of 2500 to 5000 is set, the intended purpose can be achieved, and the present invention has been achieved. That is, as the base polymer of the surface layer material, at least two kinds of acrylic resins (D component) are used, and by setting this weight ratio high, compatibility and dispersibility with carbon black (F component) are improved. Thus, the glossiness of the surface layer is improved and the glossiness on the belt surface can be made uniform. And the sum of the product (Tg × W) of the glass transition point Tg (° C.) of each acrylic resin (D component) and the content ratio W (wt%) of each acrylic resin (D component) is 2500 to 5000. By setting in this range, the flexibility of the surface layer is optimized, and both mechanical strength (bending durability) and toner transferability (toner transfer efficiency) can be achieved. In addition, toner transferability is further improved by using at least one (component E) selected from the group consisting of the fluororesin, the modified acrylic resin, and the silicone resin.

  Thus, the endless belt for an electrophotographic apparatus of the present invention uses at least two kinds of acrylic resins (D component) as the base polymer of the surface layer material, and by setting this weight ratio high, carbon black ( The compatibility and dispersibility with the component (F) are improved, the glossiness of the surface layer is improved, the glossiness on the belt surface can be made uniform, and a good image can be obtained. And the sum of the product (Tg × W) of the glass transition point Tg (° C.) of each acrylic resin (D component) and the content ratio W (wt%) of each acrylic resin (D component) is 2500 to 5000. By setting in this range, the flexibility of the surface layer is optimized, and both mechanical strength (bending durability) and toner transferability (toner transfer efficiency) can be achieved. Further, by using at least one (component E) selected from the group consisting of the fluororesin, modified acrylic resin and silicone resin, the toner transferability is further improved. In addition, a modified polyamideimide resin obtained by copolymerizing an aromatic isocyanate compound (component A), an aromatic polyvalent carboxylic acid anhydride (component B), and a carboxylic acid terminal polymer (component C) is used. Since the base layer is formed, the above-mentioned carboxylic acid both terminal polymers (C component) can play a soft segment role and can give flexibility to the polyamide-imide resin. Therefore, the endless belt for electrophotographic equipment of the present invention has a large elongation at break and is excellent in durability.

  Further, when the carbon black is a carbon black having a polymer grafted or coated on the surface, more excellent effects can be obtained in terms of glossiness and uniformity of glossiness on the belt surface.

  Moreover, when the said surface layer consists of material for surface layers containing a crosslinking agent, the crosslinking density of a coating film will go up and bending resistance, abrasion resistance, etc. will improve further.

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

  For example, as shown in FIG. 1, the endless belt for an electrophotographic apparatus of the present invention is configured by directly forming a surface layer 2 on the outer peripheral surface of a base layer 1.

In the present invention, the base layer 1 contains a modified polyamideimide resin using the following (A) to (C), and the surface layer contains the following (D) to (F). It is made of a material and satisfies the following characteristics (α) and (β), and these are the greatest characteristics.
(A) An aromatic isocyanate compound.
(B) An aromatic polycarboxylic acid anhydride.
(C) Carboxylic acid both terminal polymer.
(D) At least two kinds of acrylic resins.
(E) At least one selected from the group consisting of a fluororesin, a modified acrylic resin, and a silicone resin.
(F) Carbon black.
(Α) The mixing ratio of (D) and (E) is in a weight ratio of (D) / (E) = 80/20 to 97/3.
(Β) The sum of the products of the glass transition point of each acrylic resin (D) and the content of each acrylic resin (D) in the total amount of (D) and (E) is 2500 to 5000. Is set in the range.

  The modified polyamideimide (PAI) resin used as a material for forming the base layer 1 (base layer material) is composed of an aromatic isocyanate compound (component A) and an aromatic polyvalent carboxylic acid anhydride (component B). It can be obtained by copolymerizing a carboxylic acid both terminal polymer (component C). When the base layer 1 is formed using the base layer material containing the modified polyamideimide resin as a main component, the carboxylic acid both-end polymer (component C) plays a soft segment role and imparts flexibility to the polyamideimide resin. Therefore, the endless belt for electrophotographic equipment using this has a large elongation at break and is excellent in durability.

  As the aromatic isocyanate compound (component A), a compound having an aromatic ring in the molecular structure is used. For example, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), tolidine diisocyanate (TODI), xylylene diisocyanate. (XDI), lysine diisocyanate (LDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PPDI), tetramethylxylene diisocyanate (TMXDI) and the like. These may be used alone or in combination of two or more. Among these, MDI and TODI are preferably used in terms of reactivity, cost, and solubility.

  The aromatic polyvalent carboxylic acid anhydride (component B) used together with the aromatic isocyanate compound (component A) has an aromatic ring in the molecular structure, and the aromatic isocyanate compound ( Those that undergo a condensation reaction with component A) are preferred, and examples thereof include aromatic polyvalent carboxylic acid anhydride (B1) and aromatic polyvalent carboxylic acid dianhydride (B2). These may be used alone or in combination of two or more. In the present invention, the aromatic polyvalent carboxylic acid may be used together with the aromatic polyvalent carboxylic acid anhydride (component B).

  Examples of the aromatic polycarboxylic anhydride (B1) include trimellitic anhydride (trimellitic anhydride), naphthalene-1,2,4-tricarboxylic anhydride, and the like. These may be used alone or in combination of two or more. Among these, trimellitic anhydride (trimellitic anhydride) is preferably used in terms of reactivity, cost, solubility, and the like.

  Examples of the aromatic polycarboxylic dianhydride (B2) include benzene-1,2,4,5-tetracarboxylic dianhydride (pyromellitic dianhydride), benzophenone-3, 3 ', 4,4'-tetracarboxylic dianhydride, diphenyl ether-3,3', 4,4'-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride , Biphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, biphenyl-2,2', 3,3'-tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetra Carboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5 8-tetracarboxylic dianhydride, , 8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8 -Tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8- Tetracarboxylic dianhydride, phenanthrene-1,3,9,10-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) ) Methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4- Dicarboxyphenyl) ethane dianhydride 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,3-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone Anhydrides, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylene glycol bis (anhydro trimellitate), propylene glycol bis (anhydro trimellitate) and the like can be mentioned. These may be used alone or in combination of two or more. Among these, ethylene glycol bis (anhydrotrimellitate) is preferably used in terms of reactivity, cost, solubility, and the like.

  As the aromatic polycarboxylic anhydride (B component) in the present invention, the aromatic polycarboxylic anhydride (B1) and the aromatic polycarboxylic dianhydride (B2) are used. It is preferable to use both in combination, and when both are used in combination, the ratio of imide groups in the modified PAI resin increases, so that the water absorption decreases and the bending of the endless belt can be improved.

  The molar mixing ratio between the aromatic polycarboxylic anhydride (B1) and the aromatic polycarboxylic dianhydride (B2) is preferably in the range of B1 / B2 = 90 / 10-50 / 50. Particularly preferably, B1 / B2 = 80/20 to 60/40. It is preferable to use B1 / B2 in such a ratio because the bending resistance of the endless belt is hardly deteriorated and bending wrinkles can be improved.

  Next, as the carboxylic acid both-end polymer (C component) used together with the A component and the B component, those having one carboxylic acid at each end of the polymer are preferable. Examples thereof include terminal hydrogenated polybutadiene, carboxylic acid both-end polyester, and carboxylic acid both-end polyamide. These may be used alone or in combination of two or more.

  Examples of the carboxylic acid used for introducing the carboxylic acid at both ends of the polymer include aliphatic carboxylic acids and aromatic carboxylic acids. These may be used alone or in combination of two or more.

  Examples of the aliphatic carboxylic acid include adipic acid, sebacic acid, suberic acid, oxalic acid, succinic acid, corkic acid, azelaic acid, dodecanedicarboxylic acid, undecanedicarboxylic acid, maleic acid, fumaric acid, itaconic acid and the like. It is done. Examples of the aromatic carboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, and nitrophthalic acid.

  The said carboxylic acid both terminal polymer (C component) can be obtained by introduce | transducing the above carboxylic acid into the both terminal of polymers, such as polybutadiene, hydrogenated polybutadiene, polyester, polyamide, for example.

  Among the carboxylic acid both-end polymers (component C), the carboxylic acid both-end polyester can be produced, for example, as follows. That is, in a reaction vessel equipped with a heating device, a stirring device, a reflux device, a water separator, a distillation column and a thermometer, a dicarboxylic acid such as adipic acid or sebacic acid, methylpentanediol, nonanediol, methyloctanediol, etc. A diol is charged, and the temperature is raised to a predetermined temperature (for example, 220 ° C.) over a predetermined time (for example, 1 hour). Furthermore, after continuing the polycondensation reaction at a predetermined temperature (for example, 220 ° C.), the desired carboxylic acid-terminated polyester can be obtained by cooling to a predetermined temperature (for example, room temperature).

  In addition, the polyester having both ends of the carboxylic acid includes, for example, an ester polyol having two or more hydroxyl groups in a molecular structure in a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube, and phthalic anhydride. A dibasic acid anhydride and an organic solvent such as an NMP solvent are charged, and the temperature is raised to a predetermined temperature (for example, 130 ° C.) over a predetermined time (for example, 1 hour) while stirring under a nitrogen stream. It can also be produced by reacting at a temperature (for example, 130 ° C.) for a predetermined time (for example, about 3 hours) and then cooling to a predetermined temperature (for example, room temperature).

  In addition, carboxylic acid both terminal polymer (C component), such as carboxylic acid both terminal polybutadiene, can also be suitably produced according to the manufacturing method of the said carboxylic acid both terminal polyester.

  The acid value of the carboxylic acid both-end polymer (component C) thus obtained is preferably in the range of 15 to 150 mgKOH / g, particularly preferably in the range of 45 to 110 mgKOH / g.

  Moreover, the number average molecular weight (Mn) of the said carboxylic acid both terminal polymer (C component) has the preferable range of 750-7500, Most preferably, the number average molecular weight (Mn) is the range of 1000-2500.

  The content ratio of the structural unit derived from the carboxylic acid both terminal polymer (component C) is preferably in the range of 5 to 30% by weight, particularly preferably 15 to 25% by weight of the whole modified polyamideimide resin. It is a range. That is, if the amount is too small, the durability tends to be deteriorated. On the other hand, if the amount is too large, the creep rate tends to deteriorate.

  Here, the total number of moles of isocyanate groups (a) of the aromatic isocyanate compound (component A) and the total number of moles of anhydrides and carboxyl groups of the aromatic polyvalent carboxylic acid anhydride (component B) The molar mixing ratio of the number (b) and the total number of moles (c) of the carboxyl groups of the carboxylic acid both terminal polymer (component C) to the total number of moles [(b) + (c)] is (a) / [(B) + (c)] = 90/100 to 130/100 is preferable, and (a) / [(b) + (c)] = 100/100 to 120/100 is particularly preferable. . That is, when the value of (a) / [(b) + (c)] is out of the above upper limit or lower limit, it becomes difficult to increase the molecular weight of the PAI resin, and the durability tends to deteriorate. Because.

  The modified PAI resin obtained by copolymerizing the A component, the B component, and the C component can be prepared, for example, as follows. That is, a reaction vessel equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a cooling tube was prepared, and the aromatic isocyanate compound (component A) and an anhydride of an aromatic polyvalent carboxylic acid such as trimellitic anhydride ( B component) and a carboxylic acid terminal polymer (C component) such as a carboxylic acid terminal polyester are blended in a predetermined amount, and N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N , N-dimethylacetamide (DMAC), γ-butyrolactone and other polar solvents are charged and stirred for a predetermined time (preferably 1 to 3 hours) under a nitrogen stream with a predetermined temperature (preferably 130 to 150 ° C.) The temperature rises to Next, the modified PAI resin can be prepared by reacting at a predetermined temperature (preferably 130 to 150 ° C.) for a predetermined time (preferably about 3 to 5 hours) and then stopping the reaction.

  The modified PAI resin preferably has a number average molecular weight (Mn) in the range of 5,000 to 100,000, particularly preferably Mn in the range of 10,000 to 50,000. In other words, if the Mn of the PAI resin is too small, the tear strength is lowered and the durability is deteriorated. Conversely, if the Mn of the PAI resin is too large, the solution viscosity becomes high and the workability tends to deteriorate. is there. The number average molecular weight (Mn) can be measured by a gel permeation chromatograph (GPC) method.

  In addition, as a material (base layer material) used for the formation of the base layer 1, a conductive filler, a flame retardant, an organic solvent (DMF, DMAC, toluene, acetone, NMP, etc.), a filler ( Calcium carbonate, etc.), a leveling agent (release agent) and the like can be appropriately contained as necessary.

Examples of the conductive filler include conductive powders such as carbon black and graphite, metal powders such as aluminum powder and stainless steel powder, conductive zinc oxide (c-ZnO), and conductive titanium oxide (c-TiO ₂ ). , Conductive metal oxides such as conductive iron oxide (c-Fe ₃ O ₄ ) and conductive tin oxide (c-SnO ₂ ), quaternary ammonium salts, phosphate esters, sulfonates, aliphatic polyvalent Examples thereof include ionic conductive agents such as alcohol and aliphatic alcohol sulfate salts. These may be used alone or in combination of two or more.

  Moreover, as said flame retardant, phosphorus containing resin (phosphorus containing polyester resin etc.) etc. are mention | raise | lifted, for example. These may be used alone or in combination of two or more.

  For the base layer material, for example, a PAI resin, a conductive filler, an organic solvent, and a filler are appropriately blended as necessary and mixed with a stirring blade, and then a ring mill, a ball mill, a sand mill or the like is used. And then dispersed.

  Next, the material (surface layer material) used for forming the surface layer 2 is at least one selected from the group consisting of at least two kinds of acrylic resins (component D), a fluororesin, a modified acrylic resin, and a silicone resin. (E component) and carbon black (F component) are used. In the present invention, the acrylic resin (D component) and the modified acrylic resin (E component) represent different components.

  The acrylic resin (D component) is preferably excellent in compatibility with carbon black (F component). The acrylic monomer (monomer) that is the structural unit of the acrylic resin (component D) includes not only acrylic acid and derivatives thereof, but also methacrylic acid and derivatives thereof, and copolymers obtained by polymerizing them. Etc. Examples of such acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, propyl acrylate, n-butyl acrylate, and acrylic acid. Isobutyl, sec-butyl acrylate, tert-butyl acrylate, 2,2-dimethylpropyl acrylate, cyclohexyl acrylate, 2-tert-butylphenyl acrylate, 2-naphthyl acrylate, phenyl acrylate, acrylic acid 4 -Methoxyphenyl, 2-methoxycarbonylphenyl acrylate, 2-ethoxycarbonylphenyl acrylate, 2-chlorophenyl acrylate, 4-chlorophenyl acrylate, benzyl acrylate, 2-cyanobenzyl acrylate, acrylic acid 4 Cyanophenyl, p-tolyl acrylate, isononyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-cyanoethyl acrylate, 3-oxabutyl acrylate, methacrylic acid, methacryl Methyl acid, ethyl methacrylate, octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, methacrylic acid 2 , 2-dimethylpropyl, cyclohexyl methacrylate, 2-tert-butylphenyl methacrylate, 2-naphthyl methacrylate, phenyl methacrylate, 4-methoxyphenyl methacrylate, 2-methoxycarbonylphenyl tacrylate, 2-ethoxycarbonylphenyl methacrylate, 2-chlorophenyl methacrylate, 4-chlorophenyl methacrylate, benzyl methacrylate, 2-cyanobenzyl methacrylate, 4-cyanophenyl methacrylate, p-methacrylate Tolyl, isononyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-cyanoethyl methacrylate, 3-oxabutyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, acrylamide, Butylacrylamide, N, N-dimethylacrylamide, piperidylacrylamide, methacrylamide, 4-carboxyphenylmethacrylamide, 4-methoxy Ruboxyphenyl methacrylamide, methyl chloroacrylate, ethyl-α-chloroacrylate, propyl-α-chloroacrylate, isopropyl-α-chloroacrylate, methyl-α-fluoroacrylate, butyl-α-butoxycarbonyl methacrylate, butyl-α- Examples thereof include radically polymerizable monomers such as cyanoacrylate, methyl-α-phenyl acrylate, isobornyl acrylate, isobornyl methacrylate, diethylaminoethyl methacrylate and the like.

  Specific examples of the acrylic resin (component D) include polymethyl methacrylate, polyethyl methacrylate, poly (n-butyl methacrylate), poly (isobutyl methacrylate), poly (n-butyl acrylate), poly (isobutyl acrylate) and the like. . In the present invention, it is necessary to use at least two types of acrylic resins, and there may be three or more types. Two types are preferable from the viewpoints of material mixing and productivity.

  In the present invention, the product of the glass transition point Tg of each acrylic resin (D) and the content W of each acrylic resin (D) in the total amount of the above (D) and (E) (Tg × The sum of W) is set in the range of 2500 to 5000 [characteristic (β)], and preferably in the range of 2750 to 4050. That is, if the sum of the products (Tg × W) is too small, the toner transferability (toner transfer efficiency) deteriorates. Conversely, if the sum of the products (Tg × W) is too large, the mechanical strength ( This is because the bending durability is deteriorated and the glossiness and uniformity of the belt surface are deteriorated.

The characteristic (β) will be specifically described in the case of using two kinds of acrylic resins, that is, an acrylic resin (D1) and an acrylic resin (D2). That is, the glass transition point Tg ₁ of the acrylic resin (D1) is 90 ° C., the content ratio W ₁ is 21% by weight, the glass transition point Tg ₂ of the acrylic resin (D2) is 18 ° C., and the content ratio W ₂ is If it is 70% by weight, Tg ₁ × W ₁ + Tg ₂ × W ₂ = (90 × 21) + (18 × 70) = 3150 is the sum of the products corresponding to the characteristic (β).

  The acrylic resin (component D) preferably has a glass transition point (Tg) in the range of −20 to 110 ° C., particularly preferably in the range of 0 to 100 ° C., from the viewpoints of bending resistance and releasability. That is, if Tg is too low, the releasability is deteriorated, and conversely, if Tg is too high, surface cracks tend to occur. The glass transition point can be obtained by DSC measurement.

  The acrylic resin (component D) preferably has a number average molecular weight (Mn) in the range of 10,000 to 1,200,000, particularly preferably in terms of smoothness, flex resistance, wear resistance, and the like. It is in the range of 20,000 to 1,000,000. That is, if Mn is too low, the surface is easily cracked and more easily worn. Conversely, if Mn is too high, smoothness tends to deteriorate.

  The present invention is characterized in that at least one (E component) selected from the group consisting of a fluororesin, a modified acrylic resin and a silicone resin is used together with the at least two types of acrylic resins (D component).

  Examples of the fluororesin (E component) include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-tetrafluoroethylene copolymer [P (VDF-TFE)], and polyvinylidene fluoride-tetrafluoropropylene copolymer [P (VDF-HFP)], tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTEF), tetrafluoroethylene-hexafluoropropylene Examples thereof include a copolymer (FEP). These may be used alone or in combination of two or more.

  The modified acrylic resin (E component) is different from the acrylic resin (D component), and refers to a resin modified with another resin or resin component based on the molecular structure of the acrylic resin. Examples of the modified acrylic resin (E component) include silicone graft acrylic resins and fluorine graft acrylic resins. These may be used alone or in combination of two or more.

  Examples of the silicone resin (component E) include dimethyl silicone resin, methylphenyl silicone resin, methyl hydrogen silicone resin, alkyl-modified silicone resin, polyether-modified silicone resin, amino-modified silicone resin, epoxy-modified silicone resin, carboxyl Examples thereof include modified silicone resins and alcohol-modified silicone resins. These may be used alone or in combination of two or more.

  In the present invention, the mixing ratio of the at least two kinds of acrylic resins (D component) and at least one (E component) selected from the group consisting of a fluororesin, a modified acrylic resin and a silicone resin is a weight ratio. , D component (total amount of each acrylic resin) / E component (total amount of fluororesin, modified acrylic resin or silicone resin) = 80/20 to 97/3, preferably D component / E component = 85 / 15 to 91/9. That is, if the weight ratio of the D component is too small (the weight ratio of the E component is too large), the compatibility and dispersibility with the carbon black (F component) deteriorates, improving glossiness and making the glossiness uniform. In other words, the mechanical strength (flexibility) deteriorates, and conversely, if the weight ratio of the D component is too large (the weight ratio of the E component is too small), toner transferability (toner transfer efficiency) ) Will get worse.

  Next, the carbon black (F component) used together with the D component and the E component means carbon black in a broad sense, and includes all things manufactured by the furnace method and the impact method. Specifically, , Furnace black, lamp black (direct combustion black), thermal black (inactive black), acetylene black, hard black, soft black, channel black (active black), roller black, disc black, granular black, dense black, pellets Black etc. are raised. These may be used alone or in combination of two or more.

  Among the above carbon blacks (F component), carbon black having a polymer grafted on its surface (hereinafter abbreviated as “polymer graft carbon”) or carbon black having a polymer coated on its surface (hereinafter “polymer coating”). (Abbreviated as “carbon”).

  The above polymer-grafted carbon has a structure in which a polymer having a reactive group that reacts with a functional group such as a carboxyl group, a hydroxyl group, or a carbonyl group present on the surface of carbon black is grafted (added or bonded). It is.

  The carbon black before polymer grafting, which is a raw material for the polymer graft carbon, is preferably one having a functional group such as a carboxyl group or a hydroxyl group on the surface of the carbon black, but considering the reaction efficiency with the polymer, the pH is It is preferable to use 5 or less carbon black. That is, if the pH of the carbon black is too high, it becomes difficult for the target polymer to be grafted on the surface of the carbon black, so that the dispersibility is not improved, aggregated particles remain, and a rough surface layer is formed. At the same time, the controllability of the electrical resistance is low, and the problem that the control becomes difficult is likely to occur.

  The polymer grafted on the surface of the carbon black is preferably a polymer having a reactive group capable of binding to the functional group on the surface of the carbon black. Examples of the polymer include acrylic, polymethacrylic, styrene-acrylic, polyurethane, polyether, polyester, polyamide, polyimide, and epoxy. These may be used alone or in combination of two or more. Such a grafted polymer on the surface of carbon black can also be formed by adding and bonding a monomer that gives such polymer to a functional group on the surface of carbon black and then polymerizing it from that point. In the present invention, polymer-grafted carbon formed by polymerization of such monomers can be used as well.

  In such a polymer graft carbon in which a predetermined polymer is grafted on the carbon black surface, the graft ratio of the polymer is appropriately determined so as to obtain the intended action and effect. In order to achieve the object of the invention advantageously, the ratio of the grafted polymer and carbon black is preferably in the range of 0.2 to 1.0 by weight. That is, when the weight ratio is less than 0.2, the active carbon black surface cannot be sufficiently covered with the polymer, and the effect of improving the dispersibility of the carbon black is hardly realized. On the contrary, if the weight ratio exceeds 1.0, the amount of polymer is too large, and the characteristics of the polymer appear on the surface layer. This is because it is difficult to develop the conductivity.

  The polymer graft carbon can be obtained, for example, by the method described in JP-A-9-59331 and JP-A-9-272706. That is, in general, such a grafting reaction is carried out in a dispersion medium (solvent) appropriately selected according to the type of polymer. Specifically, water, methyl alcohol, ethyl alcohol or the like is used as the dispersion medium. , Ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, cellosolves and the like are used in an appropriate amount depending on the type of the reaction apparatus.

  In addition, the grafting reaction is performed by charging carbon black, a polymer, and a dispersion medium (solvent) into a predetermined reaction apparatus, and dispersing and mixing under heating. As the reaction apparatus at that time, For example, a kneader such as a two-roll, a three-roll, or a kneader, or a dispersing machine such as a ball mill or a bead mill is used, and a heating device is attached to the kneader so that the temperature can be controlled. In the grafting reaction using such a reaction apparatus, the reaction temperature is usually about 50 to 200 ° C., preferably 70 to 150 ° C., and the treatment (reaction) time is usually 1 to 10 hours, Preferably it is the range for 1 to 5 hours.

  Next, the polymer-coated carbon is obtained by coating the surface of carbon black with a polymer. An additive such as a high molecular weight dispersant may be attached to the surface. Here, the adhesion is made when the additive adsorbs on the surface of the polymer-coated carbon. This will be described in detail below.

  As the carbon black, carbon black having a large number of surface functional groups (hydroxyl group, carboxyl group, carbonyl group, etc.) is preferable in consideration of a coating treatment using a polymer.

  And the average primary particle diameter of the said carbon black has the preferable range of 10-300 nm, Most preferably, it is 15-100 nm. That is, if it is not within the above range, the dispersibility and conductivity may be lowered.

Moreover, the specific surface area of the carbon black is usually preferably in the range of 10 to 500 m ² / g, particularly preferably 50 to 300 m ² / g. The specific surface area is a value measured by the BET method. That is, it is a value calculated by the multipoint method using the BET equation after measuring the nitrogen adsorption amount of carbon black by the low temperature nitrogen adsorption method.

  Further, the volatile content of the carbon black is preferably 1.0% or more, particularly preferably 1.0 to 10%. That is, if it shows such a volatile matter, it will contain a certain amount or more of carbon black functional groups (-OH, = CO, -COOH, etc.), and these functional groups will act on the polymer and carbon. This is because it helps cover the black surface.

  The DBP absorption amount of the carbon black is preferably in the range of 40 to 250 ml / 100 g, particularly preferably 45 to 200 ml / 100 g. That is, if it is not within the above range, the viscosity of the electrophotographic material is increased, and workability at the time of application may be deteriorated. The DBP absorption is a value measured according to JIS K6221 (Method A).

  Next, examples of the polymer covering the carbon black include polysiloxane, polyacrylic, polymethacrylic, styrene-acrylic, polyurethane, polyether, polyester, polyamide, polyimide, and epoxy. Etc. can be used. Of these, polyfunctional epoxy resins are preferred. Here, the polyfunctional epoxy resin refers to an epoxy resin in which the total number of epoxy groups in one molecule is 2 or more. Examples of such polyfunctional epoxy resins include glycidyl amine type epoxy resins, triphenyl glycidyl methane type epoxy resins, tetraphenyl glycidyl methane type epoxy resins, aminophenol type epoxy resins, diamide diphenyl methane type epoxy resins, and phenol novolac type epoxy resins. Examples thereof include resins, orthocresol type epoxy resins, bisphenol A novolac type epoxy resins, glycidyl ether type epoxy resins and the like. The coating polymer is used together with various curing agents, curing accelerators, and organic solvents according to a conventional method. And a coating polymer may use 2 or more types of polymers together in arbitrary ratios.

  And the use rate of a coating polymer has the preferable range of 5-40 weight% of the total amount of the said carbon black and coating polymer, Most preferably, it is 5-20 weight%. That is, if it is less than 5% by weight, there is a possibility that only dispersibility and dispersion stability equivalent to that of untreated carbon black may be obtained. Conversely, if it exceeds 40% by weight, it is combined with carbon black coated with a polymer. This is because the physical properties such as toner properties, toner releasability, and low friction properties may be impaired.

  Furthermore, you may mix | blend appropriate additives, such as a high molecular weight dispersing agent, with the said polymer covering carbon. Examples of the high molecular weight dispersant include a dispersant having a weight average molecular weight of 1,000 to 50,000, and examples thereof include various dispersants that are usually used for carbon black. Specific examples include polyester-based dispersants, polyurethane-based dispersants, polyacrylate-based dispersants, and the like, and these are used alone or in combination of two or more.

  The blending ratio of the high molecular weight dispersant is preferably set in the range of 0.1 to 40% by weight, particularly preferably 5 to 30% by weight, based on the total amount of the polymer-coated carbon and the high molecular weight dispersant. It is. That is, if the amount is too small, it will not work effectively as a dispersant, while if it is too large, the physical properties may deteriorate, or bleeding out may occur over time.

  In the case of the above polymer-coated carbon, for example, epoxy resin coating, it can be produced as follows. That is, first, an aqueous slurry of carbon black prepared in advance is charged into a container with a screw type stirrer, and an epoxy resin solution is added little by little under predetermined stirring conditions. As a result, the carbon black dispersed in water moves to the epoxy resin solution side. Then, after passing through the draining step, vacuum drying is performed to remove water and the like, thereby obtaining particulate epoxy resin-coated carbon black. Next, the epoxy resin-coated carbon black and an additive such as a high molecular weight dispersant are blended at a predetermined ratio and dispersed using, for example, a disperser such as a bead mill. As a result, the additive adheres to the surface of the epoxy resin-coated carbon black, and as a result, the epoxy resin-coated carbon black treated with the additive is obtained.

  The blending amount of the carbon black (F component) is preferably in the range of 5 to 100 parts, particularly preferably 10 to 80 parts with respect to 100 parts by weight (hereinafter abbreviated as “parts”) of the D component and E component. Part range. That is, if the F component is too small, the expression of electrical conductivity will be insufficient. Conversely, if the F component is too large, the carbon will be highly filled, leading to a higher hardness of the coating film, and the cracking of the coating film. Because there is a fear.

  In addition to the components D to F, the surface layer material may be appropriately mixed with a crosslinking agent, a resin crosslinking agent such as an amino resin, a phenol resin, or a xylene resin, a leveling agent, an organic solvent, or the like.

  Examples of the crosslinking agent include isocyanate compounds.

  Examples of the isocyanate compound include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, isophorone diisocyanate (IPDI), crude MDI, and the like.

  The amount of the crosslinking agent is preferably in the range of 1 to 100 parts, particularly preferably in the range of 5 to 50 parts, with respect to 100 parts in total of the D component and E component. That is, if the amount of the crosslinking agent is too small, the wearability is inferior and leads to a decrease in gloss. Conversely, if the amount of the crosslinking agent is too large, the hardness of the coating film is increased and the coating film may be cracked. .

  The surface layer material can be prepared, for example, by appropriately blending the D component, the E component, the F component, an organic solvent, and the like and mixing them with a stirring blade. In order to form each layer with high accuracy, it is preferable to use different types of organic solvents as materials for forming adjacent layers. That is, it is preferable to use different types of organic solvents used for the surface layer material and organic solvents used for the base layer material.

  Examples of the organic solvent include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), n-butanol, xylene, N, N-dimethylformamide (DMF), toluene, acetone and the like. Used together.

  The endless belt for electrophotographic equipment of the present invention can be produced, for example, as follows. That is, first, a mold (cylindrical substrate) is prepared, and the base layer material is spray-coated on the surface, thereby forming the base layer 1 on the surface of the mold. Next, after the surface layer material is coated on the surface of the base layer 1 by the dipping method, by blowing air between the base layer 1 and the cylindrical base body, the cylindrical base body is extracted, and the surface of the base layer 1 is An endless belt (seamless belt) for an electrophotographic apparatus having a two-layer structure in which the surface layer 2 is formed can be produced.

  In addition, the manufacturing method of the base layer 1 and the surface layer 2 of the endless belt for an electrophotographic apparatus of the present invention is not limited to the above manufacturing method, and can be manufactured by an extrusion molding method, an inflation method, a blow molding method, or the like. is there.

  The endless belt for electrophotographic equipment of the present invention preferably has a glossiness of 80 or more, particularly preferably 90 or more. That is, when the glossiness is too small, as described above, the variation in reading of the toner density sensor tends to increase.

  In the present invention, the glossiness means “mirror glossiness” described in JIS Z 8741-1997. The glossiness can be measured using, for example, a handy gloss meter PG-1M manufactured by Nippon Denshoku.

The endless belt for electrophotographic equipment of the present invention preferably has a surface resistivity (ρS ₁ ) of the belt surface of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω / □, particularly preferably 1 × 10 ¹⁰ to 1 × 10. The range is ¹⁴ Ω / □. In other words, if the surface resistivity (ρS ₁ ) of the belt surface is too low, the pressure resistance tends to be inferior. Conversely, if the surface resistivity (ρS ₁ ) of the belt surface is too high, charge decay is slow and toner transfer occurs. This is because there is a tendency that no charge remains and an afterimage appears. In the endless belt for electrophotographic equipment of the present invention, the surface resistivity (ρS ₂ ) on the back surface of the belt is preferably in the range of 1 × 10 ⁶ to 1 × 10 ¹² Ω / □, particularly preferably 1 × 10 ⁸ to 1. The range is × 10 ¹² Ω / □.

Here, the surface resistivity (ρS ₁ ) of the belt surface means the surface resistivity of the outermost peripheral surface of the endless belt for electrophotographic equipment, and the surface resistivity (ρS ₂ ) of the back surface of the belt means electrophotographic equipment. The surface resistivity of the innermost circumferential surface of the endless belt.

  The endless belt for electrophotographic equipment of the present invention preferably has a surface resistivity difference of 0.2 to 2.0 digits represented by the following formula (1), particularly preferably 0. It is in the range of 4 to 2.0 digits. That is, if the surface resistivity difference is too small, the charge tends to flow outside the transfer area, transfer dust is generated, and conversely if the surface resistivity difference is too large, the charge decay rate on the belt surface is slow, This is because there is a tendency to cause an afterimage phenomenon.

  The thickness of the base layer 1 of the endless belt for electrophotographic equipment of the present invention is preferably in the range of 30 to 300 μm, particularly preferably in the range of 50 to 200 μm. The thickness of the surface layer 2 is preferably in the range of 1 to 10 μm, particularly preferably in the range of 1 to 5 μm. That is, when the surface layer 2 is too thin, the pressure resistance tends to be inferior, and conversely, when the surface layer 2 is too thick, electric charge remains and an afterimage (ghost) tends to occur or the flexibility tends to be inferior. It is. The endless belt for electrophotographic equipment of the present invention preferably has an inner peripheral length of 500 to 2500 mm and a width of about 150 to 600 mm. That is, when the size is set within the above range, the size is suitable for use in an electrophotographic copying machine or the like.

  The film thicknesses of the base layer 1 and the surface layer 2 can be measured using, for example, a scanning electron microscope, a micrometer, or the like.

  The endless belt for electrophotographic equipment of the present invention is suitable for use in electrophotographic equipment employing electrophotographic technology such as full-color LBP and full-color PPC, such as toner image transfer, paper transfer conveyance, and photoreceptor substrate. 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 will be described together with comparative examples. However, the present invention is not limited to these examples.

[Example 1]
(Preparation of base layer material)
In a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a thermometer, and a cooling tube, 22 parts of MDI (A component) (manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MT, Mn: 250.06) and TODI (A component) (Japan) Soda Co., Ltd., TODI / R203, Mn: 264.29) 29 parts, aromatic polycarboxylic acid anhydride (component B) trimellitic anhydride (Mn: 192.12) 36 parts, and carboxylic acid Both ends polybutadiene (C component) (Nippon Soda Co., Ltd., C-1000, acid value: 52 mg KOH / g, Mn: 2158) 20 parts and NMP solvent 250 parts were charged and stirred for 1 hour under nitrogen flow. The temperature was raised to 130 ° C., and the reaction was allowed to proceed at 130 ° C. for about 5 hours. Then, the reaction was stopped to prepare a PAI-NMP solution (solid content concentration: 26% by weight). Next, 4 parts of carbon black (Show Black Ca220, Showa Cabot Co., Ltd., Showa Black N220) was blended with the PAI-NMP solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer material. The viscosity of the base layer material was adjusted to 15000 mPa · s (measured value of a B-type viscometer).

(Preparation of surface layer material)
The materials shown in Table 1 described later were blended in the proportions shown in the table, kneaded, and then mixed with a stirring blade to prepare a surface layer material. The viscosity of the surface layer material was adjusted to 10 mPa · s (measured value of B-type viscometer).

(Production of endless belt)
A mold (cylindrical substrate) was prepared, and the base layer material was spray-coated on this surface to form a base layer on the surface of the mold. Next, after the surface layer material is coated on the surface of the base layer by dipping, the cylindrical base is removed by blowing air between the base layer and the cylindrical base, and the surface of the base layer (thickness: 80 μm) In addition, an endless belt (seamless belt) having a two-layer structure in which a surface layer (thickness: 3 μm) was formed was produced.

[Examples 2 to 10, Comparative Examples 1 to 8]
A surface layer material was prepared in the same manner as in Example 1 except that the composition of the surface layer material was changed as shown in Tables 1 to 3 below. Then, an endless belt having a two-layer structure in which a surface layer was formed on the surface of the base layer was produced according to Example 1 except that this surface layer material was used.

  The materials shown in Tables 1 to 3 are as follows.

[Acrylic resin A (component D)]
Polymethyl methacrylate (PMMA) (Mitsubishi Rayon Co., Ltd., Dialnal BR-75, Tg: 90 ° C., Mn: 85,000)
[Acrylic resin B (component D)]
Polymethyl methacrylate (PMMA) (Negami Kogyo Co., Ltd., Paracron W-197C DR, Tg: 18 ° C., Mn: 400,000)
[Acrylic resin C (component D)]
Polymethyl methacrylate (PMMA) (manufactured by Negami Kogyo Co., Ltd., Paracron AW-4500H, Tg: −8 ° C., Mn: 320,000)

[Fluororesin (E component)]
Polyvinylidene fluoride-tetrafluoropropylene copolymer [P (VDF-HFP)] (manufactured by Arkema, Kyner 2821)
[Modified acrylic resin (E component)]
Silicone graft acrylic resin (Saimak US-350, manufactured by Toagosei Co., Ltd.)
[Silicone resin (E component)]
Dimethyl silicone oil (Toray Dow Corning Silicone, SH-200)

[Carbon black A (F component)
Furnace Black (manufactured by Cabot Japan, Show Black N220)

[Carbon black B (component F) (polymer graft carbon)]
231 parts of carbon black (type: LFF, average particle size: 24 nm, DBP absorption: 57 ml / 100 g, pH: 3) are charged with 69 parts of styrene-acrylic polymer and 700 parts of methyl isobutyl ketone as a dispersion medium, The resulting mixture was uniformly dispersed and mixed and treated at 110 ° C. for 3 hours to advance the grafting reaction to obtain a polymer-grafted carbon (grafting rate: 0.3%).

[Carbon black C (component F) (polymer-coated carbon)]
Carbon black having an average primary particle diameter of 24 nm, a specific surface area of 134 m ² / g, a pH value of 3.0, and a DBP absorption of 65 ml / 100 g is prepared, and this carbon black and pure water are mixed at 6,000 rpm for 30 minutes with a homomixer. A slurry was prepared by processing. On the other hand, an aminophenol type epoxy resin (manufactured by Yuka Shell Epoxy, Epicoat 630) was dissolved in toluene to prepare an epoxy resin solution. Then, the slurry is transferred to a container with a screw-type stirrer, and the stirring condition of about 1,000 rpm is such that the aminophenol type epoxy resin becomes a ratio of 10% by weight of the total amount of carbon black and aminophenol type epoxy resin. The epoxy resin solution was added in small portions. After about 15 minutes, all the carbon black dispersed in water moved to the toluene side and became large-sized particles. And after draining with a 60 mesh wire net, it dried at 70 degreeC with the vacuum dryer for 7 hours, and removed water and toluene. Thus, particulate epoxy resin-coated carbon black was obtained. Furthermore, with respect to the epoxy resin-coated carbon black, the blending ratio of the high molecular weight dispersant (manufactured by Zeneca, Solsperse S24000GR) is a ratio of 18% by weight of the total amount of the epoxy resin coated carbon black and the high molecular weight dispersant. By mixing with a bead mill, the epoxy resin-coated carbon black was treated with a dispersant to obtain an epoxy resin-coated carbon black (polymer-coated carbon).

[Isocyanate (crosslinking agent)]
HDI (Nippon Polyurethane, Coronate HX)

  Using the endless belts of Examples and Comparative Examples obtained as described above, each characteristic was evaluated according to the following criteria. These results are also shown in Tables 1 to 3 above. In addition, the product of the mixing ratio (D / E) of D component and E component, the glass transition point Tg of each acrylic resin (D component), and the content ratio W (weight%) of each acrylic resin (D component). The sum of (Tg × W) is also shown.

[Glossiness]
The glossiness of the surface layer was measured using a handy gloss meter PG-1M manufactured by Nippon Denshoku. The glossiness is preferably 80 or more.

[Glossiness variation]
The variation in glossiness in each endless belt was evaluated. That is, a total of 12 endless belts, 3 in the axial direction and 4 in the circumferential direction, were measured using a handy gloss meter PG-1M manufactured by Nippon Denshoku Co., Ltd. The difference between the maximum value and the minimum value was evaluated as the glossiness variation. The variation in glossiness is preferably less than 20.

[Toner transfer]
The endless belt was printed by being incorporated into a copying machine (manufactured by Ricoh Co., Ltd., IMAGIO MPC2500). Evaluation was evaluated as “◯” when there was no transfer defect in the image and “X” when there was a transfer defect.

[Mechanical durability (flexibility)]
According to JIS P8115, using folding endurance setter MIT-D (manufactured by Toyo Seiki Co., Ltd.), the number of MITs of the endless belt was measured under a load of 9.8N. The number of MITs is an index for evaluating mechanical durability (flexibility), and the greater the number of MITs, the better the mechanical durability. In the evaluation, a case where the number of MITs was 15000 times or more was evaluated as ◯, and a case where the number of MITs was less than 15000 times was evaluated as x.

  From the results shown in Tables 1 to 3, all the products of Examples have sufficient glossiness, can achieve uniform glossiness on the belt surface, mechanical strength (bending durability), and toner transferability. It was excellent.

  On the other hand, Comparative Examples 1, 4 and 5 were inferior in toner transferability because the sum of products (Tg × W) was less than 2500. In Comparative Examples 2, 6, and 7, the acrylic resin content ratio was small, so the glossiness was small and the variation in glossiness was large. The product of Comparative Example 3 had a small acrylic resin content ratio, and the sum of products (Tg × W) exceeded 5,000, resulting in large variations in glossiness and poor mechanical durability. The product of Comparative Example 8 was inferior in toner transferability due to the large content ratio of acrylic resin.

  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.

Explanation of symbols

1 base layer 2 surface layer

Claims (3)

An endless belt for an electrophotographic apparatus in which a surface layer is formed on the outer peripheral surface of the base layer, wherein the base layer contains a modified polyamideimide resin using the following (A) to (C), and the surface layer is An endless belt for an electrophotographic apparatus, comprising a material for a surface layer containing the following (D) to (F) and satisfying the following characteristics (α) and (β).
(A) An aromatic isocyanate compound.
(B) An aromatic polycarboxylic acid anhydride.
(C) Carboxylic acid both terminal polymer.
(D) At least two kinds of acrylic resins.
(E) At least one selected from the group consisting of a fluororesin, a modified acrylic resin, and a silicone resin.
(F) Carbon black.
(Α) The mixing ratio of (D) and (E) is in a weight ratio of (D) / (E) = 80/20 to 97/3.
(Β) The sum of the products of the glass transition point of each acrylic resin (D) and the content of each acrylic resin (D) in the total amount of (D) and (E) is 2500 to 5000. Is set in the range.   The endless belt for an electrophotographic apparatus according to claim 1, wherein the carbon black (F) is a carbon black having a polymer grafted or coated on the surface thereof.   The endless belt for an electrophotographic apparatus according to claim 1 or 2, wherein the surface layer is made of a surface layer material containing a crosslinking agent.

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