JP2023024836A - Conductive belt, image forming device with the same, and method of manufacturing conductive belt - Google Patents

Abstract

To provide a belt for an image forming device in which a base material layer exhibits semi-conductivity in a medium resistance region (1×105 to 1×108 Ω/sq), a variation in surface resistivity is small, and a surface layer exhibits insulating properties.SOLUTION: A conductive belt includes: a base material layer made of a composition containing polyethylene resin, polyamide resin and conductive agent; an adhesive layer made of a composition containing epoxy group-containing polyethylene resin; and a surface layer made of a composition containing acid-modified ethylene-tetrafluoroethylene copolymer.SELECTED DRAWING: None

Description

The present invention relates to a conductive belt used in an image forming apparatus using an inkjet system or an electrophotographic system.

In the past, image forming devices such as electrophotographic and inkjet printers, copiers, and facsimiles have used rollers to transport paper. Therefore, a method is adopted in which the paper is reliably held and conveyed by a belt. Specifically, (1) a method in which a belt having suction holes is used to vacuum-suck a paper sheet onto the belt, and (2) a belt consisting of a conductive base layer and an insulating surface layer is used. A method is known in which a sheet is conveyed by attracting the sheet to the belt using an electrostatic attraction force generated by applying a voltage to the belt.

Of these, (1) the method of sucking the paper onto the belt under reduced pressure requires a decompression chamber and a decompression device for decompressing the decompression chamber, as described in Patent Documents 1 and 2. Since the space between the driving belt and the decompression chamber must always be maintained in a sealed state, the structure of the image forming apparatus becomes complicated. On the other hand, (2) the method using the electrostatic attraction force is convenient because the attraction force can be controlled only by adjusting the applied voltage if there is a member for applying a voltage to the belt and a power source.

As a belt (paper conveying belt) for sucking and conveying a recording medium such as paper using electrostatic adsorption force, Patent Document 3 discloses that both the inner layer and the outer layer are made of polyimide resin, and the inner layer has a volume resistivity of 1. A paper transport belt is described having a thickness of 1×10 ⁸ to 1×10 ¹⁴ Ω·cm and a volume resistivity of the outer layer of 1×10 ¹⁴ to 1×10 ¹⁶ Ω·cm. However, the paper conveying belt described in Patent Document 3 uses centrifugal molding (spraying a solution of polyamic acid for the inner layer or the outer layer on the surface or back of the mold, volatilizing the solvent at high temperature, and then applying imide at high temperature in the absence of oxygen). In the case of two layers, this process must be repeated twice), which makes the manufacturing process very complicated.

Further, in Patent Document 4, an ink-jet printer having an inner layer made of a conductive polyimide resin having a surface resistivity of 1×10 ⁴ to 1×10 ⁹ Ω/□ and an outer layer made of an ethylene-tetrafluoroethylene copolymer (ETFE) A paper transport belt is described. This paper conveying belt also requires a step of forming an inner layer by centrifugal molding, covering the inner layer with preformed tubular ETFE, and melting and adhering it, so the manufacturing process is very complicated.

On the other hand, some inks used in inkjet printers, which are capable of printing at high speed, use organic solvents. There is a problem that the portion swells and unevenness occurs on the belt surface. In view of such solvent resistance, it is desired to use a fluororesin for the surface layer, but the fluororesin has poor adhesiveness. Some of them have a surface resistivity of less than 1×10 ¹⁴ Ω/□, and there is also a problem that the attraction force becomes weak.

JP 2019-131389 A JP 2019-127364 A JP 2008-94605 A JP 2011-73804 A

In view of this situation, in order to produce a multi-layered conductive belt by coextrusion, a polyamide resin and a conductive agent are contained, and the surface resistivity is 1×10 ⁵ to 1×10 ⁸ Ω/□. A prototype of a conductive belt having a substrate layer and a surface layer containing an acid-modified ethylene-tetrafluoroethylene copolymer was produced.
The present ^invention has been ^made in view of such problems. To provide a conductive belt which is small, has an insulating surface layer, and does not warp when absorbing moisture.

According to the invention,
(1) A substrate layer made of a composition containing a polyethylene resin, a polyamide resin, and a conductive agent, an adhesive layer made of a composition containing an epoxy group-containing polyethylene resin, and an acid-modified ethylene-tetrafluoroethylene A conductive belt comprising a surface layer made of a composition containing a copolymer;
(2) The conductive belt according to (1), wherein the composition for forming the base layer further contains a compatibilizer;
(3) The conductive belt according to (1) or (2), wherein the epoxy group-containing polyethylene resin is an ethylene-glycidyl methacrylate copolymer;
(4) The conductive belt according to any one of (1) to (3), wherein the conductive agent is an electronically conductive material;
(5) The conductive belt according to (4), wherein the electronically conductive material is carbon black;
(6) The surface resistivity of the substrate layer side at a temperature of 23° C. and a relative humidity of 50% RH is 1×10 ⁵ Ω/□ or more and 1×10 ⁸ Ω/□ or less (1) The conductive belt according to any one of (5);
(7) Any one of (1) to (6), wherein the surface resistivity of the surface layer side at a temperature of 23° C. and a relative humidity of 50% RH is 1×10 ¹³ Ω/□ or more. a conductive belt of;
(8) The conductive belt according to any one of (1) to (7), which is for an image forming apparatus;
(9) A conductive belt characterized in that the conductive belt according to any one of (1) to (8) is for an inkjet image forming apparatus;
(10) An image forming apparatus comprising the conductive belt according to any one of (1) to (9);
(11) In the method for producing a conductive belt according to any one of (1) to (9), a composition for forming a base layer containing a polyethylene resin, a polyamide resin, and a conductive agent; The composition for forming an adhesive layer containing the contained polyethylene resin and the composition for forming the surface layer containing the acid-modified ethylene-tetrafluoroethylene copolymer are supplied to separate extruders, and the substrate layer is extruded from an annular die. A method for producing a conductive belt, characterized by co-extrusion so that the inner layer and the adhesive layer are the intermediate layer, and the surface layer is the outer layer;
is provided.

The conductive belt of the present invention comprises a base layer made of a composition containing a polyethylene resin, a polyamide resin, and a conductive agent, an adhesive layer made of a composition containing an epoxy group-containing polyethylene resin, and an acid-modified It is laminated with a surface layer made of a composition containing an ethylene- ^{tetrafluoroethylene} copolymer. ), and the surface resistivity of the substrate layer side (the side on which the surface layer is not formed) is in the range of 1×10 ⁵ to 1×10 ⁸ Ω/□ (medium resistance region). . When such a belt is used as a paper transport belt, since the surface layer has excellent insulating properties, the adsorption force of the recording medium (paper) is strong, and the recording medium can be reliably transported.
Further, the conductive belt of the present invention is less likely to warp even under high humidity, and can be suitably used as a paper conveying belt. The conductive belt of the present invention can be manufactured at a lower cost than conventional multi-layered belts using polyimide resin. The conductive belt of the present invention does not swell on the belt surface even when solvent-type ink adheres to it, so it can be suitably used particularly as a paper transport belt for an ink jet system.

[Base layer]
It is essential that the substrate layer of the present invention is made of a composition containing a polyethylene-based resin, a polyamide-based resin, and a conductive agent. If necessary, other resins may be blended as long as the characteristics are not impaired.

The polyethylene-based resin used in the present invention is a polymer composed of ethylene, and includes copolymers having polyethylene as a partial structure. Polyethylene resins include, for example, high density polyethylene (density: 0.942 to 0.96), medium density polyethylene (density: 0.93 to 0.942), low density polyethylene (density: 0.91 to 0.93 ), ultra-low density polyethylene (density: less than 0.91), linear low-density polyethylene, etc. Examples of copolymers having polyethylene as a partial structure include copolymers of ethylene and vinyl acetate. Some ethylene-vinyl acetate copolymers (referred to as EVA) and the like are included.

Further, the conductive belt for an image forming apparatus, which is one of the applications of the conductive belt of the present invention, is used by being stretched between rolls under a certain tension. Since it is left in a stretched state between rolls, it tends to bend. Then, when the printer or the like is started, there is a problem that the bent portion becomes convex. If a film made of thermoplastic resin is left in the same shape for a long time, it will inevitably develop a tendency to bend. Tension is applied, and the convexity of the bent portion is relaxed. For this reason, it is preferable that the tensile modulus of the polyethylene-based resin is 1100 MPa or less.
Further, in recent years, with the speeding up of printers and the like, if the tensile elastic modulus of the conductive belt for an image forming apparatus is less than 400 MPa, the belt stretches during driving, which is not preferable. As mentioned above, there are various types of polyethylene-based resins. Low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene have a tensile modulus of about 200 to 300 MPa. A combination of polyethylene and low density polyethylene, linear low density polyethylene, ultra-low density polyethylene or the like can be used to adjust the tensile modulus.

A polyamide-based resin is a thermoplastic resin having a sufficient molecular weight obtained by polycondensation of diamine and dicarboxylic acid, polycondensation of α,ω-aminocarboxylic acid, ring-opening polymerization of lactams, or the like. Examples of polyamide resins include nylon 6, nylon 4, nylon 6,6, nylon 11, nylon 12, nylon 6,10, nylon 6,12, nylon 6/6,6, nylon 6/6, 6/12. , nylon 6,MXD (MXD represents an m-xylylenediamine component), nylon 6,6T (T represents a terephthalic acid component), nylon 6,6I (I represents an isophthalic acid component), and the like. Among these, polyamide resins with low water absorption are preferred, and polyamide resins with low water absorption are excellent in the dispersibility of carbon black and in the stability of electrical resistance in high-humidity environments. The water absorption of the polyamide resin is preferably 1.5% or less, more preferably 1.0% or less. Polyamide resins with a water absorption of 1.5% or less include nylon 11, nylon 12, nylon 6,10, nylon 6,12, etc. Polyamide resins with a water absorption of 1.0% or less include nylon 11 , and nylon 12. These polyamides may be used alone or in combination of two or more.

In order to uniformly disperse the polyamide-based resin in the polyethylene-based resin, the composition forming the substrate layer of the present invention may contain a compatibilizer. The compatibilizer is preferably a modified polyethylene resin containing epoxy groups, carboxyl groups or acid anhydride groups. By using modified polyethylene having an epoxy group, a carboxyl group, or an anhydride group that is reactive with the amino group that is the terminal group of the polyamide resin as a compatibilizer, a sea island in which the polyamide resin is finely dispersed in the polyethylene resin matrix. form a structure. Since the carbon black and the ion-conductive material, which are conductive agents, are unevenly distributed in the polyamide-based resin, which has a higher affinity, the conductive agent can be uniformly dispersed in the polyethylene resin matrix.

The compatibilizer is, for example, an ethylene-methyl acrylate-maleic anhydride terpolymer, an ethylene-ethyl acrylate-maleic anhydride terpolymer, or an ethylene-butyl acrylate-maleic anhydride terpolymer. , an ethylene-glycidyl methacrylate copolymer, an ethylene-methyl acrylate-glycidyl methacrylate terpolymer, and the like, which may contain structural units derived from other monomers. Other monomers include, for example, α-olefins such as propylene and butene, styrene, vinyl acetate, (meth)acrylate, (meth)acrylonitrile, and the like. Other monomers can be used singly or in combination of two or more. The content of other monomers is 0 to 15 mol %, preferably 0 to 10 mol %, more preferably 0 to 5 mol %. The number average molecular weight of the compatibilizer is preferably 3000 or more. If the compatibilizer has a number average molecular weight of less than 3,000, unreacted compatibilizer may bleed out to the substrate layer surface (bleeding phenomenon). This bleeding phenomenon causes contamination of paper and other parts in a conductive belt for an image forming apparatus.

Moreover, the tensile modulus of the substrate layer is preferably 500 MPa or more, more preferably 700 MPa or more. In order to increase the tensile modulus of the belt, it is possible to increase the content of high-density polyethylene in the polyethylene-based resin described above, or to add reinforcing materials such as flat fillers and whiskers. The thickness of the substrate layer is preferably 30-300 μm, more preferably 40-200 μm, so as to satisfy the above performance. If the thickness is less than 30 μm, it is difficult to obtain a stable electrostatic adsorption force of the belt, and if the thickness exceeds 300 μm, flexibility deteriorates.

In the conductive belt of the present invention, the surface resistivity of the base layer can be adjusted by blending a conductive agent in the base layer. The surface resistivity of the base material layer is preferably 1×10 ⁵ to 1×10 ¹² Ω/□, particularly 1×10 ⁵ to 1×10 ⁸ Ω/□, which is a medium resistance region. preferable. Conductive agents include electronically conductive materials and ionically conductive materials. In addition, when the substrate layer requires a lower resistance region (for example, 1×10 ⁵ to 1×10 ⁶ Ω/□) among the medium resistance regions, it is possible to lower the electrical resistance with a small amount of addition. It is preferred to use electronically conductive materials.

Examples of electron conductive materials include carbon-based materials such as carbon black, graphite, and carbon nanotubes; conductive polymers such as polyaniline, polythiophene, and polyacetylene; aluminum/zinc oxides, antimony/tin oxides, and indium/tin oxides. conductive inorganic particles such as inorganic particles surface-treated with carbon black or the like. Examples of carbon black include conductive carbon black such as furnace black, channel black, ketjen black, and acetylene black. In particular, a small amount of carbon black having an average particle size of 50 nm or less can reduce electrical resistance. It is preferable because it can be done. In addition, from the viewpoint of developing the structural structure of carbon black and forming a conductive path, the DBP (Dibutyl phthalate) oil absorption is preferably 100 to 500 ml/100 g, preferably 100 to 300 ml/100 g, and 150 to 250 ml/100 g. is more preferable. Carbon black having a BET surface area in the range of 30 to 1500 m ² /g is preferred from the viewpoint of conductivity. Further, in the present invention, the surface is treated with grafted carbon black in which a polymer having one or more functional groups selected from carboxyl group, hydroxyl group, epoxy group, amino group and oxazoline group is grafted, or with a low molecular weight compound. Carbon black can also be used.

The amount of the electronic conductive material is preferably 5 parts by weight to 25 parts by weight, more preferably 8 parts by weight to 20 parts by weight, with respect to 100 parts by weight of the total amount of the polyethylene resin and the polyamide resin. is more preferred. If the amount of the conductive agent is less than 5 parts by weight, it may not be possible to obtain a composition exhibiting the desired semi-conductivity. If it exceeds 25 parts by weight, the melt viscosity increases and melt extrusion becomes difficult. There is a tendency.

Examples of the ion conductive material include polyether ester amide, polyether ester, polyether amide, polyethylene oxide, polyethylene oxide copolymer, partially crosslinked polyethylene oxide copolymer, ion electrolyte, and the like. , or two or more types can be used in combination. As the ion electrolyte, alkali metal thiocyanates, phosphates, sulfates, halogen-containing oxates, and tetraalkylammonium salts can be used singly or in combination. Among these, lithium perchlorate, sodium perchlorate, potassium perchlorate, lithium thiocyanate, sodium thiocyanate, and potassium thiocyanate are preferred.

When an ion conductive material is used as the conductive agent, the blending amount of the conductive agent is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the total amount of the polyethylene resin and the polyamide resin. The blending amount is preferably 1 to 30 parts by weight, preferably 2 to 25 parts by weight, more preferably 15 to 25 parts by weight. If the amount of the ion-conductive material is less than 1 part by weight, a composition exhibiting the desired conductivity cannot be obtained. I don't like it.

Additives may be blended into the resin composition used for the base layer of the present invention, if necessary, as long as the properties are not impaired. Examples of additives include antioxidants, heat stabilizers, organic fillers and inorganic fillers, antiblocking agents, plasticizers, lubricants, processing aids, and the like. These resins and additives can be used in appropriate amounts depending on the purpose.

The composition ratio of each component of the composition forming the substrate layer of the present invention is not particularly limited. : preferably contained in a ratio of 30% to 8% by weight. The ratio of the polyamide-based resin to 100% by weight of the total amount of the polyethylene-based resin and the polyamide-based resin is more preferably 10-25% by weight, and even more preferably 12-20% by weight. By setting the blending ratio of the polyethylene resin and the polyamide resin within the above range, a sea-island structure in which the polyamide resin is finely dispersed in the polyethylene resin matrix is obtained. Shows uniformity of resistance. If the polyamide-based resin is less than 8% by weight, the distance between the islands in the sea-island structure increases, which may deteriorate the uniformity of the electrical resistance.

The blending amount of the compatibilizer is preferably 0.3 to 5.0 parts by weight, preferably 0.5 to 2 parts by weight, with respect to 100 parts by weight of the total amount of the polyethylene resin and the polyamide resin. .0 parts by weight is more preferred. By setting the amount of the compatibilizing agent within the above range, a sea-island structure in which the polyamide-based resin is finely dispersed in the polyethylene-based resin matrix is obtained. Shows uniformity of resistance. If the amount of the compatibilizing agent is less than 0.3 parts by weight, the size of the islands in the sea-island structure becomes large, making it difficult to obtain stable electrical resistance in the medium resistance region and possibly reducing the elongation at break of the film. There is On the other hand, if the compounding amount of the compatibilizing agent exceeds 5 parts by weight, the size of the islands in the sea-island structure may become too small, and the compounding amount of the conductive agent required to obtain the electrical resistance in the medium resistance region may be too small. If it is molded into a belt shape, the variation in electric resistance in the TD direction becomes large, which is not preferable. For these reasons, the size of the islands in the sea-island structure in the composition forming the substrate layer is preferably 0.5 to 5.0 μm, more preferably 0.8 to 3.0 μm.

[Adhesion layer]
The adhesive layer of the present invention must be made of a composition containing an epoxy group-containing polyethylene resin. The composition consists of only an epoxy group-containing polyethylene-based resin, or may contain other resins and additives as necessary within a range that does not impair its properties. When a conductive belt composed of a base layer containing a polyethylene resin, a polyamide resin, and a conductive material and a surface layer containing an acid-modified ethylene-tetrafluoroethylene resin is produced by a coextrusion method, the interlayer adhesion strength is increased. Weak and peels off easily. The adhesive layer of the present invention is a layer necessary for bonding the substrate layer and the surface layer, and the presence of the adhesive layer allows the functional groups of the surface layer, such as carboxyl groups, to react with the epoxy groups of the adhesive layer. By doing so, the surface layer and the adhesive layer can be firmly adhered. Examples of epoxy group-containing polyethylene resins include ethylene-glycidyl methacrylate copolymers, ethylene-glycidyl methacrylate-ethyl acrylate terpolymers, and ethylene-glycidyl methacrylate-vinyl acetate terpolymers. be done.

Also, the thickness of the adhesive layer is preferably 2 to 80 μm, more preferably 5 to 50 μm, so as to satisfy the above performance. In the co-extrusion method, if the thickness of the specific layer (adhesive layer) is less than 2 μm, there is a risk that there will be a portion where the specific layer does not exist. and the total thickness of the surface layer) becomes thicker, and the electrostatic attraction force decreases.

[Surface layer]
It is essential that the surface layer of the present invention consists of a composition containing an acid-modified ethylene-tetrafluoroethylene copolymer. The composition may be composed of only the acid-modified ethylene-tetrafluoroethylene copolymer, or may contain other resins and additives as necessary within a range that does not impair the properties of the composition. The acid-modified ethylene-tetrafluoroethylene copolymer is a copolymer containing at least polymerized units based on ethylene, polymerized units based on tetrafluoroethylene, and polymerized units having an acid structure.
Polymerized units having an acid structure include unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride and citraconic anhydride, and unsaturated carboxylic acids such as undecylenic acid, acrylic acid, methacrylic acid and maleic acid. . The content of polymerized units having an acid structure is preferably 0.01 to 10 mol%, more preferably 0.1 to 5 mol%, relative to the total polymerized units in the acid-modified ethylene-tetrafluoroethylene copolymer. .

A surface layer made of a composition containing an acid-modified ethylene-tetrafluoroethylene copolymer and a substrate layer made of a composition containing a polyethylene-based resin, a polyamide-based resin, and a conductive agent are formed into two layers by a coextrusion method. Although the adhesiveness is poor even when extruded with , the interlaminar adhesive strength between the surface layer and the substrate layer is increased by disposing it on the adhesive layer made of the composition containing the epoxy group-containing polyethylene resin.
Further, the surface resistivity of the surface layer side of the conductive belt of the present invention is preferably 1×10 ¹³ Ω/□ or more, more preferably 1×10 ¹⁴ Ω/□ or more. Ethylene copolymers and acid-modified ethylene-tetrafluoroethylene copolymers are preferable because they have a surface resistivity of 1×10 ¹⁴ Ω/□ or more and are excellent in insulating properties. Further, it was found that the surface layer used in the present invention does not swell even if the solvent ink adheres to the surface of the conductive belt because the surface layer used in the present invention uses a fluororesin.

[Manufacturing method of image forming apparatus belt]
The method for producing the composition for forming the substrate layer of the present invention is not particularly limited, but for example, a polyethylene resin, a polyamide resin, a conductive agent, and optional additives are blended and dry-blended. After that, a method of melt-kneading, a method of melt-kneading a polyethylene resin and a conductive agent in advance to prepare a masterbatch, and a method of melt-kneading a polyamide-based resin and an additive to be used as necessary, and the like can be mentioned.

Apparatuses for melt-kneading include various known kneaders such as batch-type kneaders, kneaders, co-kneaders, Banbury mixers, roll mills, and single-screw or twin-screw extruders. Among these, single-screw extruders and twin-screw extruders are preferably used from the viewpoint of excellent kneading ability and productivity.

The temperature at the time of melt kneading can be appropriately selected depending on the type of polyethylene resin or polyamide resin used, the melt viscosity, etc., but it is usually in the range of 150 to 300 ° C., and from the viewpoint of preventing deterioration of the resin, preferably 170 ~280°C.

The conductive belt of the present invention can be produced by an extrusion molding method, a centrifugal molding method, a dipping method, or the like. Extrusion molding, particularly extrusion molding using an annular die, is preferred because it yields a seamless belt. As an extrusion molding method using an annular die, for example, three extruders and an annular die communicating with the extruder are arranged below the extruder. It is possible to use an extrusion molding apparatus provided with a mandrel for cooling and solidifying a molten resin to be extruded onto the outer periphery of the resin. The composition forming the base layer, the resin forming the adhesive layer, and the resin forming the surface layer are supplied to respective extruders, co-extruded into a tubular shape from one annular die, and extruded along the outer circumference of the mandrel. A tube-shaped compact can be obtained by cooling and solidifying them together. Then, a belt can be obtained by cutting the obtained tubular molded body into a desired width. These descriptions are for three layers, but when four or more layers are used, an extruder and a die corresponding to the number of layers may be prepared.

The conductive belt of the present invention can be suitably used as parts for an image forming apparatus such as an intermediate transfer belt, a transfer/transport belt, and a paper transport belt. In particular, the conductive belt of the present invention does not swell even when solvent ink adheres to the belt surface, so that it can be suitably used as a paper transport belt for an ink jet method using solvent ink.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Methods for measuring physical properties in Examples are as follows.
(1) Melt Viscosity Melt viscosity was measured using a Koka flow tester manufactured by Shimadzu Corporation equipped with a die having a hole of length 10 mm×diameter 1 mm.
(2) Surface resistivity The surface resistivity is measured using Hiresta UX (MCP-HT800, manufactured by Dia Instruments) equipped with a URS probe (load 2 kg) (applied voltage 10 V for the base layer, applied voltage 1000V).
Further, the uniformity (variation) of the surface resistivity was determined by the following formula.
Uniformity of surface resistivity [digit] = log10 (maximum value of surface resistivity / minimum value of surface resistivity)
(3) Interlayer adhesion between the base layer and the surface layer In the belts obtained in each example and comparative example, it was confirmed whether the base layer and the surface layer were adhered, and based on the following evaluation criteria. evaluated.
◯: The substrate layer and the surface layer are strongly bonded (via the adhesive layer).
x: The base material layer and the surface layer are adhered, but can be separated by hand or easily separated between the layers.
(4) Solvent ink resistance After dripping solvent ink (high-boiling petroleum-based solvent with a boiling point of 100°C or higher) onto the surface layer of the belt obtained in each example and comparative example, and leaving it at 60°C for 24 hours. After wiping off the solvent ink, the surface was observed and evaluated according to the following evaluation criteria.
◯: The film surface did not swell and was not deformed.
Δ: The film surface was slightly swollen and slightly deformed.
x: The film surface swelled and was clearly deformed.
(5) Warpage of Belt Edge After leaving the belt obtained in each Example/Comparative Example under high temperature and high humidity (30° C.×70% RH) for 1 day, observe the warpage of the belt edge. It was evaluated based on the evaluation criteria.
◯: No warp occurred at the belt edge.
x: The edge of the belt warped toward the surface layer.

The following materials were used as raw materials.
<Thermoplastic resin (A)>
・ High-density polyethylene resin (A-1) [melting point: 132 ° C., melt viscosity: 9240 poise (measurement temperature 200 ° C., load 100 kg]
・ Low density polyethylene resin (A-2) [melting point: 111 ° C., melt viscosity: 2300 poise (measurement temperature 200 ° C., load 100 kg]
· Polyamide resin (A-3) [melting point: 178 ° C., melt viscosity: 5000 poise (measurement temperature 200 ° C., load 100 kg]
Compatibilizer (A-4) [Ethylene-ethyl acrylate-maleic anhydride terpolymer (blending ratio; ethylene: ethyl acrylate: maleic anhydride = 92: 5: 3, melting point: 107 ° C., melt viscosity : 830 poise (measurement temperature 200°C, load 100 kg)]
- Acid-modified ethylene-tetrafluoroethylene copolymer (A-5) [melting point: 190°C, melt viscosity: 6750 poise (measurement temperature: 220°C, load: 100 kg)]
・Polyvinylidene fluoride (A-6) [melting point: 168°C, melt viscosity: 4500 poise (measurement temperature: 200°C, load: 100 kg)]
- Ethylene-glycidyl methacrylate copolymer (A-7) (blending ratio: ethylene: glycidyl methacrylate = 88:12)
- Ethylene-glycidyl methacrylate copolymer (A-8) (blending ratio: ethylene: glycidyl methacrylate = 92:8)
<Conductive agent (B)>
・Carbon black (B-1) [DBP oil absorption: 190ml/100g, BET surface area: 70m2/g]

[Base material layer]
A polyethylene resin, a polyamide resin, a conductive agent, and a compatibilizer were melt-kneaded using a twin-screw kneading extruder with a screw diameter of 38 Φ mm so that the compounding ratio shown in Table 1 was obtained. Resin compositions for base material layers of Examples 1 to 6 were obtained.

[Example/Comparative example]
Using a device equipped with a three-layer annular die at the tip of three extruders with a cylinder diameter of 50 mm, the resin composition that forms the base layer shown in Table 1 in the inner layer extruder is adhered to the intermediate layer extruder. The resins constituting the layers are supplied to the extruder for the surface layer, and the resins forming the surface layer are each supplied to the extruder for the surface layer. A seamless belt having a circumference of 800 mm and a width of 350 mm was obtained.
Table 1 also shows the evaluation results of the conductive belts produced in Examples and Comparative Examples.

As shown in Table 1, a substrate layer made of a resin composition containing a polyethylene resin, a polyamide resin, and a conductive agent, an adhesive layer made of an epoxy group-containing polyethylene resin, and an acid-modified ethylene-tetrafluoro Examples 1 and 2, which are conductive belts having a surface layer made of an ethylene copolymer, have a surface resistivity of 1×10 ⁶ to 1×10 ⁷ Ω/□ on the substrate layer side. The uniformity (less than one digit) of surface resistivity on the substrate layer side was also excellent. The surface resistivity on the surface layer side also showed a value of 1×10 ¹⁴ Ω/□ or more, indicating excellent insulation. Further, the interlayer adhesiveness was good, the solvent ink resistance of the surface layer was good, and the edge of the belt did not warp even when left under high temperature and high humidity conditions.
On the other hand, the two-layer conductive belt has a substrate layer made of a resin composition containing a polyethylene resin, a polyamide resin, and a conductive agent, and a surface layer made of an acid-modified ethylene-tetrafluoroethylene copolymer. In Comparative Example 1, the adhesiveness between the base layer and the surface layer was poor and the layers were easily separated. Comparative Example 2, which is a two-layer conductive belt composed of a base layer made of a polyamide resin and a conductive agent, and a surface layer made of an acid-modified ethylene-tetrafluoroethylene copolymer, has a base layer. is a polyamide resin, warping occurs at the ends of the belt, making it unsuitable for use as a belt.

In Comparative Examples 3 and 4, in which the surface layer was made of polyamide resin or polyethylene resin, the uniformity of the surface resistivity of the substrate layer was excellent. Swelling was observed when left standing, and it was particularly unsuitable as a paper transport belt for an ink jet system using solvent ink. On the other hand, in Comparative Example 5 in which polyvinylidene fluoride was used as the surface layer, the solvent ink resistance of the surface layer was good, but the base layer made of the resin composition containing the polyethylene resin, the polyamide resin, and the conductive agent was not compatible with the base layer. The adhesion was poor and the layers were easily peeled off, and the surface resistivity of the surface layer was in the range of 1×10 ¹³ to 1×10 ¹⁴ Ω/□, indicating poor insulation. Further, a base layer made of a resin composition containing a polyethylene resin, a polyamide resin, and a conductive agent, an adhesive layer made of a polyamide resin, and a surface layer made of an acid-modified ethylene-tetrafluoroethylene copolymer. Comparative Example 6, which is a conductive belt with, exhibits adhesion with an acid-modified ethylene-tetrafluoroethylene copolymer, and the polyamide resin A-3 contained in the base material layer is used as an adhesive layer. However, the interlayer adhesion was poor.

Claims (11)

A substrate layer made of a composition containing a polyethylene resin, a polyamide resin, and a conductive agent, an adhesive layer made of a composition containing an epoxy group-containing polyethylene resin, and an acid-modified ethylene-tetrafluoroethylene copolymer. A conductive belt comprising a surface layer made of a composition containing 2. The conductive belt according to claim 1, wherein the composition for forming the base layer further contains a compatibilizer. 3. The conductive belt according to claim 1, wherein said epoxy group-containing polyethylene resin is an ethylene-glycidyl methacrylate copolymer. 4. The conductive belt according to any one of claims 1 to 3, wherein said conductive agent is an electronically conductive material. 5. The conductive belt of claim 4, wherein said electronically conductive material is carbon black. The surface resistivity of the substrate layer side at a temperature of 23° C. and a relative humidity of 50% RH is 1×10 ⁵ Ω/□ or more and 1×10 ⁸ Ω/□ or less. A conductive belt according to any one of the above. The conductive belt according to any one of claims 1 to 6, wherein the surface resistivity of the surface layer side at a temperature of 23°C and a relative humidity of 50% RH is 1×10 ¹³ Ω/□ or more. 8. A conductive belt according to claim 1, which is for an image forming apparatus. 9. A conductive belt according to any one of claims 1 to 8, wherein the conductive belt is for an ink jet image forming apparatus. An image forming apparatus comprising the conductive belt according to claim 1 . 10. The method for producing a conductive belt according to any one of claims 1 to 9, wherein a composition for forming a base material layer containing a polyethylene resin, a polyamide resin, and a conductive agent, and an epoxy group-containing polyethylene resin are combined. An adhesive layer forming composition containing an acid-modified ethylene-tetrafluoroethylene copolymer and a surface layer forming composition containing A method for producing a conductive belt, comprising co-extrusion so that an intermediate layer and a surface layer are formed as outer layers.