JP2006023650A - Belt for electrophotographic equipment - Google Patents

Abstract

【Task】
In an environment of normal temperature, temperature 32 ° C., and humidity 80%, it is possible to prevent the occurrence of elongation and curling, and the toner image is less likely to be overlaid, and a highly durable image can be formed. An electrophotographic belt is provided.
[Solution]
Polyurea obtained by reacting a modified polyamine having a carbonate bond part and a methylene chain part in the main chain and having an amino group at the terminal, an aromatic amine compound and a bifunctional and trifunctional aliphatic isocyanate A belt for an electrophotographic apparatus, having a layer made of the above and formed in a thin cylindrical shape.
[Selection figure] None

Description

The present invention relates to a belt for an electrophotographic apparatus.

Conventionally, as an intermediate transfer belt or transfer / conveying belt for an electrophotographic apparatus, a resin film such as a polyimide resin film or a polycarbonate resin film is generally used. However, since a belt using such a resin film has a relatively hard surface, it has a problem with the image quality obtained, and it has been required to give a certain degree of elasticity to the belt surface. .

A belt for an electrophotographic apparatus in which an elastic layer is laminated on a film core has been proposed as one that improves the image quality by imparting elasticity to the belt surface. However, since it was necessary to form an adhesive layer between the film core and the elastic layer, the process was complicated, and the difference in shrinkage between the laminated structures of different materials was large. Has problems such as the occurrence of For this reason, in recent years, a belt for an electrophotographic apparatus has been proposed in which an elastic layer of low-hardness polyurethane is provided on a polyurethane core layer.

Patent Document 1 discloses an elastic layer having a JIS A hardness of 30 to 95 degrees obtained by curing liquid thermosetting polyurethane and a core having a JIS D hardness of 75 to 90 degrees obtained by curing liquid thermosetting polyurethane or thermosetting polyurea. An electrophotographic belt having a two-layer structure with a body layer is disclosed.

Patent Document 2 discloses at least a two-layer structure including a core layer and an elastic layer made of polyurethane formed from a polyol, a low molecular weight aromatic amine, and an aliphatic isocyanate having a bifunctional group and a trifunctional group. A belt for an electrophotographic apparatus is disclosed.

Patent Document 3 discloses a core composed of a polyurethane formed by a reaction between a polyol compound, a low-molecular aromatic amine compound having a chlorine group and two or more amino groups on the same aromatic ring, and a bifunctional and trifunctional aliphatic isocyanate. An electrophotographic belt having a body layer and an elastic layer made of polyurethane obtained by a reaction between a polyol compound having an average functional group number of 2 to 3 and an isocyanate compound is disclosed.

In these electrophotographic belts disclosed in Patent Documents 1 to 3, the core layer and the elastic layer are both made of polyurethane, and the second layer of the viscous liquid is injected while the first layer is semi-cured by centrifugal molding. Since it can be integrated without providing an adhesive layer between the core layer and the elastic layer, and is made of the same type of elastic body, it does not have the problem of warping the belt It is. Further, a belt having excellent thickness uniformity can be obtained by centrifugal molding.

However, since the core layer is made of polyurethane, for example, in a high-humidity environment at a temperature of 32 ° C. and a humidity of 80%, the belt itself is easily stretched and curled. When forming a color image from the above, there is a problem that color misregistration due to elongation generated in the belt is likely to occur.

Patent Document 4 discloses a conductive member for an electrophotographic apparatus having at least one base material made of polyurethane in which a specific polyether polyol having high hydrophobicity is a polyol component, but is made of polyurethane. For this reason, a problem similar to the problem described above occurs.

On the other hand, Patent Document 1 also describes the use of polyurea for the core layer. This polyurea has a large tensile elastic modulus and a small elongation, but has a high hydrophilicity because it has an ether group. For example, in an environment of a temperature of 32 ° C. and a humidity of 80%, the belt is absorbed by water absorption. There is a problem that stretch and curl occur.

JP 2001-34078 A JP 2001-142311 A JP 2001-356612 A JP 2002-148949 A

In view of the above situation, the present invention can prevent the occurrence of elongation and curling in an environment of normal temperature, a temperature of 32 ° C., and a humidity of 80%. An object of the present invention is to provide a highly durable belt for an electrophotographic apparatus that can be formed.

The present invention comprises reacting a modified polyamine having a carbonate bond part and a methylene chain part in the main chain and having an amino group at the terminal, an aromatic amine compound, and a bifunctional and trifunctional aliphatic isocyanate. An electrophotographic belt having an obtained polyurea layer and formed into a thin cylindrical shape. The “methylene chain portion” here is a portion represented by — (CH ₂ ) _n —, and has the same meaning as the hydrocarbon chain portion.

The methylene chain part is derived from nonanediol and methyloctanediol, and the terminal amino group is preferably an amino group of di-p-aminobenzoate.
The aromatic amine compound is preferably 4-chloro-3,5-diaminobenzoic acid isobutyl ester.

The bifunctional aliphatic isocyanate is preferably norbornene diisocyanate, and the trifunctional aliphatic isocyanate is preferably an isocyanurate-modified product of hexamethylene diisocyanate.

The belt for an electrophotographic apparatus further comprises a laminated structure having an elastic layer, and the elastic layer preferably contains a polyurethane resin.
The electrophotographic belt is preferably an intermediate transfer belt or a transfer conveyance belt.
Hereinafter, the present invention will be described in detail.

The belt for an electrophotographic apparatus of the present invention has a modified polyamine having a carbonate bond part and a methylene chain part in the main chain and an amino group at the terminal, an aromatic amine compound, and a bifunctional and trifunctional aliphatic isocyanate. And a layer made of polyurea obtained by reacting with each other and formed into a thin cylindrical shape.

The polyurea is obtained by a reaction between a terminal amine component and a polyisocyanate component. A urea bond formed by the reaction between an amino group and an isocyanate group has higher molecular aggregation energy and excellent mechanical properties than a urethane bond formed from a reaction between a hydroxyl group and an isocyanate group. Moreover, such a urea bond is more hydrophobic than a urethane bond. Therefore, for example, when the electrophotographic apparatus belt is used in an environment such as a temperature of 32 ° C. and a humidity of 80%, it is possible to prevent the belt from being stretched or curled due to water absorption.

Further, in such an environment, when the belt is used as an intermediate transfer belt of an electrophotographic apparatus, it is possible to prevent elongation and curling, so that a color image is formed after the toner is twisted. In this case, it is possible to prevent color misregistration caused by elongation or curling.

As the active hydrogen-containing component forming the polyurea, a modified polyamine having a carbonate bond portion and a methylene chain portion in the main chain and having an amino group at the terminal is used. As a result, urea bonds are formed, and excellent mechanical properties and hydrophobicity can be imparted to polyurea.

When a polyamine compound having an ether bond or an ester bond in the main chain is used, the hydrophilicity is increased, and the hygroscopicity is increased in an environment of a temperature of 32 ° C. and a humidity of 80%, so that elongation tends to occur. Moreover, when using the polyamine which has an olefin bond, there exists a tendency for mechanical strength to deteriorate. On the other hand, since the polyamine which has a carbonate bond is used in this invention, generation | occurrence | production of the malfunction by such moisture absorption can be prevented.

In the modified polyamine having a carbonate bond part and a methylene chain part in the main chain and having an amino group at the terminal, the methylene chain part preferably contains a methylene chain derived from a diol having 5 to 12 carbon atoms. By having the carbonate bond separated by 5 to 12 carbon atoms, it can be made more hydrophobic than the ester bond, and the influence of moisture absorption can be removed. If it is less than 5, the carbonate bond will increase too much and it will be brittle and easily cracked. If it exceeds 12, the carbonate bond is too far away, and physical properties and hydrophobicity may not be sufficiently exhibited. More preferably, it is 8-9.

Examples of the methylene chain portion having 8 to 9 carbon atoms include those derived from nonanediol and methyloctanediol. These may be used alone or in combination of two or more.

The methylene chain portion having 8 to 9 carbon atoms preferably has a side chain. That is, it is preferable to use a methylene chain having 8 carbon atoms rather than a straight chain having 9 carbon atoms. By having a side chain, the crystallinity at low temperature can be reduced and the molecular mobility of polyurea can be secured, so that the belt of the electrophotographic apparatus can be made less likely to be curled.

In the modified polyamine having a methylene chain part having 8 to 9 carbon atoms and a carbonate bond part in the main chain and having an amino group at both ends, the content of the methylene chain part having 8 to 9 carbon atoms is 30 to 90. It is preferable that it is mass%. If it is less than 30% by mass, curling tends to occur. If it exceeds 90% by mass, it may crystallize at a low temperature and molecular mobility may not be ensured. Preferably, it is 35-85 mass%.

The methylene chain portion having 8 to 9 carbon atoms is preferably formed by reacting nonanediol and methyloctanediol with carbonate carboxylic acid at a constant ratio. By using nonanediol and methyloctanediol in a fixed ratio to form a modified polyamine, hydrophobization and low-temperature molecular mobility are imparted, so that the water absorption elongation and wrinkles at rest can be reduced.

It is preferable that the modified polyamine has a di-p-aminobenzoate amino group at the terminal because of its high reactivity.
The number average molecular weight of the modified polyamine is preferably 1000 to 2000. If it is less than 1000, it becomes too hard and there is a possibility that it will not be stretched and will be easily cracked. If it exceeds 2000, it may be too soft to secure the necessary tensile elastic modulus as the core of the belt. More preferably, it is 1000-1800.

An aromatic amine compound is used as a curing agent component that forms the polyurea.
As the aromatic amine compound, a urea bond having a cohesive force stronger than that of urethane can be introduced at a crosslinking point, etc. As a result, the soft segment and the hard segment are phase-separated to further clarify the sea-island structure. It is preferable to use an aromatic diamine because the mobility of the segment can be ensured. When the aromatic diamine is used, a more rigid hard segment can be formed.

Examples of the aromatic diamine include 4-chloro-3,5-diaminobenzoic acid isobutyl ester, 3,3′-dichloro-4,4′-diaminodiphenylmethane, dimethylthiotoluenediamine, diethyltoluenediamine, 4,4 ′. -Diamino-3,3'-diethyl-5,5'-diphenylmethane, 2,2 ', 3,3'-tetrachloro-4,4'-diaminodiphenylmethane, trimethylenebis-4-aminobenzoate, etc. Can do. These may be used alone or in combination of two or more.

Among the above aromatic diamines, an aromatic amine compound having a chlorine group and two amino groups in one aromatic ring is particularly preferable. Thereby, reactivity and rigidity can be improved more. When there is no chlorine group, the reaction between the isocyanate group and the amino group is fast, and not only the pot life but also the reaction difference with the polyol component forming the soft segment component is large, and the pot life is fast but the demolding property is inferior. There is a risk that this will occur. Further, in the case of an amine compound having a structure with two aromatic rings, the belt itself becomes too hard due to a rigid aromatic ring, which may result in poor flex resistance.

As the aromatic amine compound having a chlorine group and two amino groups on one aromatic ring, 4-chloro-3,5-diaminobenzoic acid isobutyl ester is preferable. Examples of commercially available products include Vitec 1604 (manufactured by Sumika Bayer Urethane Co., Ltd.), CDAB (YSS Two Co., Ltd.), and the like.

The aromatic amine compound preferably has a number average molecular weight of 200 to 1,000 because a hard segment having an aromatic ring can be formed.

In the formation of the polyurea, the molar ratio between the NH ₂ group amount (mole) of the modified polyamine and the NH ₂ group amount (mole) of the aromatic amine compound is preferably 1: 3 to 1:10. . If the amount of the modified polyamine is too large, the elastic modulus is lowered and elongation tends to occur. If there are too many aromatic amine compounds, it will be easy to crack.

As a component for forming the polyurea, a bifunctional aliphatic isocyanate and a trifunctional aliphatic isocyanate are mixed and used. Thereby, an isocyanate group can be adjusted between 2-3, and the balance of chain extension and bridge | crosslinking can be taken. Also, in terms of pot life, aliphatic isocyanates react slower than aromatic isocyanates and are suitable for molding polyurea. Furthermore, in consideration of bending resistance, curl resistance, and tension stability, the urea bond is more effective than the urethane bond in terms of the cohesive force of the hard segment.

Examples of the bifunctional aliphatic isocyanate include hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated dicyclohexylmethane diisocyanate (MDI), dimer acid diisocyanate, lysine diisocyanate, and norbornene diisocyanate. Of these, isophorone diisocyanate and norbornene diisocyanate are particularly preferable from the viewpoints of hygiene, reactivity, and hard segment aggregation. These may be used alone or in combination of two or more. As a commercial item of the said bifunctional aliphatic isocyanate, Cosmonate NBDI (made by Mitsui Takeda Chemical Company), Death Module I (made by Sumika Bayer Urethane Co., Ltd.), etc. can be mentioned, for example.

Examples of the trifunctional aliphatic isocyanate include, for example, hexamethylene diisocyanate and isophorone diisocyanate isocyanurate, biuret, and adduct modification. From the viewpoint of heat resistance, isocyanurate is preferred. Among these, a modified product of hexamethylene diisocyanate is particularly preferable from the viewpoint of viscosity, compatibility with bifunctional aliphatic isocyanate, and the like. Here, the modified product of hexamethylene diisocyanate refers to one in which one isocyanate group is nurate-modified, burette-modified, prepolymer-modified, or the like. As a commercial item of the said trifunctional aliphatic isocyanate, Sumidur N3300, Sumidur N3200, Desmodur TP LS 2010/1 (above, Sumika Bayer Urethane Co., Ltd. product) etc. can be mentioned. These may be used alone or in combination of two or more.

By adding not only the above-mentioned bifunctional aliphatic isocyanate but also the above trifunctional aliphatic isocyanate, an appropriate crosslinking point is formed in the structure of polyurea, and the bending resistance, curl, and tension of the belt are increased. Balance can be taken.

The blending ratio (mass ratio) of the bifunctional aliphatic isocyanate and the trifunctional aliphatic isocyanate is preferably 50:50 to 80:20. If the amount of trifunctional aliphatic isocyanate is too small, the number of crosslinking points is too small and the elongation may increase. When there are too many trifunctional aliphatic isocyanates, there exists a possibility that a crosslinking density may increase, the cohesion force of a heart segment may fall, and elongation may be worsened. More preferably, it is 60: 40-70: 30.

The amount of the aliphatic isocyanate is determined by the total amount of the modified polyamine and the aromatic amine compound. In this case, the ratio (mass ratio) between the modified polyamine and the aromatic amine compound is preferably 70:30 to 20:80. Thereby, it is possible to achieve both the high elastic modulus required for the core layer, crack resistance and bending fatigue resistance. If the amount of the aromatic amine compound is too large, the belt is easily cracked. If the amount is too small, the high elastic modulus may not be secured. More preferably, it is 50: 50-35: 75.

In the formation of the polyurea, an amine catalyst such as triethylenediamine or a tin catalyst such as dibutyltin dilaurate may be used to adjust the reactivity.

The belt for an electrophotographic apparatus usually contains a conductive filler. Since the voltage is controlled in transferring the toner image, peeling the paper, and the like, the belt itself is provided with conductivity. However, the term “conductivity” as used herein is a level also called semiconductivity having an electric resistance of 10 ³ to 10 ¹⁰ Ω · cm. Examples of the conductive filler include carbon black.

As a method for dispersing conductive filler in polyurea, for example, a conductive filler such as carbon black is kneaded with a modified polyamine with three rolls and dispersed uniformly, and dispersed together with reaction hardening. Contain.

In many cases, the belt for an electrophotographic apparatus has a laminated structure having a core layer and an elastic layer. In this case, the above-described polyurea layer is used as a core layer of the belt, and the elastic layer is formed of low-hardness polyurethane.

In the belt for an electrophotographic apparatus having the core layer and the elastic layer, the core layer is preferably as thin as possible in order to maintain the tension as the belt and to stably run the belt, for example, the thickness of the core layer The thickness is 0.05 to 0.3 mm. If it is thinner than 0.05 mm, the strength is insufficient and the durability may be inferior. More preferably, it is 0.08-0.25 mm.

When the elastic layer is polyurethane, the JIS-A hardness is preferably 30 to 80 degrees. If it is lower than 30 degrees, there is a possibility that the elastic layer is tacked or the toner retainability is too good and the transfer efficiency is lowered. If it exceeds 80 degrees, the ability to follow the unevenness of the paper will be reduced, and a sharp image may not be obtained. In order to make the elastic surface layer have a JIS-A hardness of 30 to 80 degrees, the kind of polyol component or isocyanate component is changed, or the molar ratio of [NCO] / [OH] is adjusted.

Moreover, the thickness of the elastic layer is usually 0.05 to 1.0 mm. If the thickness is less than 0.05 mm, the effect of the elastic layer may not be sufficiently exhibited. If it exceeds 1.0 mm, the belt becomes too thick and color misalignment tends to occur. More preferably, it is 0.1-0.9 mm.

The belt for an electrophotographic apparatus having the core layer and the elastic layer can be formed by centrifugal molding in the order of the elastic layer and then the core layer. That is, after pouring the raw material liquid constituting the elastic layer into a centrifugal molding machine, applying a centrifugal force to heat reaction, and making it semi-cured to such an extent that the fluidity becomes poor, the raw material liquid constituting the core layer is It can be produced by pouring on (inside) the elastic layer and heat-curing the elastic layer and the core layer together. Since the core layer raw material liquid is poured in a state where the elastic layer is semi-cured, only by heat curing together, the interface between both layers is integrated, there is no delamination, and the bending resistance is good, in the circumferential direction A seamless belt that is continuous and continuous can be obtained. Further, the resin constituting the elastic layer and the core layer does not have a large difference in shrinkage rate, and the obtained belt does not warp or bend.

The belt for an electrophotographic apparatus can be suitably used as an intermediate transfer belt and a transfer conveyance belt with little elongation, high accuracy, and little meandering.

In the belt for an electrophotographic apparatus having the core layer and the elastic layer, a surface layer may be further formed outside the elastic layer. The surface layer can be formed, for example, by coating using a fluorine-based paint or the like, and can improve the releasability from the toner and the cleaning property.

The electrophotographic apparatus belt of the present invention (FIGS. 1, 2, and 3), the electrophotographic apparatus using the belt as an intermediate transfer belt (FIG. 4), and the electrophotographic apparatus using the transfer conveyance belt (FIG. 5). ) Will be described with reference to the drawings.

1, 2 and 3 are perspective views of the belt 1 for an electrophotographic apparatus of the present invention. 1 is a single-layer belt, FIG. 2 is a two-layer belt having an elastic layer 3 outside the core layer 2, and FIG. 3 is a three-layer belt having a surface layer 4 outside the elastic layer 3. It is a belt of construction.

FIG. 4 is a side view of the periphery of the photoreceptor 11 of the electrophotographic apparatus using the electrophotographic apparatus belt of the present invention as the intermediate transfer belt 16. The photoconductor 11 is uniformly charged by a charging unit, and exposed by a laser beam or reflected light in an exposure unit to form an electrostatic latent image. The photoreceptor 11 rotates in the direction of the arrow, contacts the first developing roller (developing unit 14), and the yellow component is developed. The photoconductor 11 moves without contacting the second to fourth developing rollers, and contacts the intermediate transfer belt 16. The intermediate transfer belt 16 is stretched around the pulleys 12 and 13 and moves in the direction of the arrow, and the yellow image on the photoconductor 11 is transferred to the intermediate transfer belt 16. The photoreceptor 11 is neutralized by removing the remaining yellow toner with a cleaning blade.

Similarly to the above, the charging → exposure → developing unit and the photosensitive member 11 rotate and contact only the magenta color developing roller, and a magenta toner image is formed on the photosensitive member 11 and moves to the transfer unit as it is. The toner image is transferred to the intermediate transfer belt 16 and superimposed on the yellow image.

Similarly, a cyan toner image is formed on the photoreceptor 11 and is superimposed on the intermediate transfer belt 16. Finally, a black toner image is formed on the photoconductor 11 and is superimposed on the intermediate transfer belt 16 to form a color image on the intermediate transfer belt 16. The color image on the intermediate transfer belt 16 is transferred onto a sheet member, for example, paper, supplied between the roller 15 and the pulley 13 and fixed by a fixing device. The intermediate transfer belt 16 transfers the color image onto the paper, and then the remaining toner is removed by the cleaning blade.

FIG. 5 is a side view of the periphery of the photoreceptor 11 of the electrophotographic apparatus using the electrophotographic apparatus belt of the present invention as the transfer / conveying belt 16 '. Similar to FIG. 4, the photoconductor 11 rotates and moves with the charging unit, the exposure unit, and the development unit 14 to form and carry a black toner image, and comes into contact with the paper sent on the transfer conveyance belt 16 ′. Then, the toner image is transferred onto a sheet of paper, and is transferred to the fixing unit by the transfer / conveying belt 16 'as it is to be fixed. The transfer conveyance belt 16 ′ is stretched around the pulleys 12 and 13 and moves in the direction of the arrow. As in FIG. 4, the photoconductor 11 is discharged by removing the toner remaining with the cleaning blade.

4 and 5, the intermediate transfer belt and the transfer conveyance belt are rested or stored for a long time while being wound around a small-diameter roller pulley having an outer diameter of 10 to 20 mm. Be seen.

The belt for an electrophotographic apparatus of the present invention has a modified polyamine having a carbonate bond part and a methylene chain part in the main chain and an amino group at the terminal, an aromatic amine compound, and a bifunctional and trifunctional aliphatic isocyanate. And a layer made of polyurea obtained by reacting with each other and formed into a thin cylindrical shape. For this reason, in a high temperature and high humidity environment such as a temperature of 32 ° C. and a humidity of 80%, it is possible to reduce the occurrence of curling due to water absorption due to stretching of the belt or rotation of the apparatus. In particular, as a modified polyamine, by providing methylene chain portions derived from nonanediol and methyloctanediol in the main chain, the carbonate bond portions can be arranged at appropriate intervals, and the above-described effects are more exhibited.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail, this invention is not limited only to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Example 1
A modified polyamine (number average molecular weight 1000, having a methylene chain part derived from nonanediol and methyloctanediol preliminarily kneaded with conductive carbon 1% and a carbonate bond, and having an amino group of di-p-aminobenzoate at the terminal. 1,9-nonanediol / methyloctanediol mass ratio 65/35, “PCD1000”, manufactured by Ihara Chemical Industry Co., Ltd.) 60.3 parts, 4-chloro-3,5-diaminoben as a low molecular weight aromatic amine component 50 parts of zoic acid isobutyl ester (“Vitec 1604”, manufactured by Sumika Bayer Urethane Co., Ltd.) was added, dissolved at 120 ° C., and dehydrated at 100 ° C. for 12 hours. To this amine component, 0.4 part of Ucat1102 (manufactured by Sun Apro) was added as a catalyst.

Hexamethylene diisocyanate modified trifunctional nurate ("Sumijour N3300", manufactured by Sumika Bayer Urethane Co., Ltd.) as the isocyanate, and norbornene diisocyanate ("Cosmonate NBDI", manufactured by Mitsui Takeda) as the bifunctional aliphatic isocyanate These isocyanates were mixed at a 30:70 mass ratio (average functional group number f = 2.13).

64.9 parts of this mixed isocyanate is added to the amine component obtained above so that the [active hydrogen] / [NCO] ratio is 1.05, and the mixture is stirred and mixed with an agitator, and preheated to 120 ° C. Pour into a cylindrical mold with an inner diameter of 180 mm and a width of 350 mm of a centrifugal molding machine rotating at 500 rpm, drop to 500 rpm after 10 minutes at 2500 rpm, cure for 20 minutes at a mold temperature of 125 ° C., and after mold at 110 ° C. for 12 hours. A belt having a thickness of 0.2 mm made of a polyurea resin single layer was obtained by curing.

Example 2
In Example 1, a polyurea resin monolayer was used in the same manner as in Example 1 except that norbornene diisocyanate was hexamethylene diisocyanate as a bifunctional aliphatic isocyanate and mixed so that the average number of functional groups was 2.13. I got a belt.

Example 3
1% of conductive carbon was kneaded in advance with Nippon Poly 4032 (manufactured by Nippon Polyurethane Industry Co., Ltd., hydroxyl value = 60 KOHmg / g), a polyester polyol having an average functional group number of 2.3, and dehydrated at 100 ° C. for 12 hours. A mixture obtained by adding 9.77 parts of “Coronate T-65” manufactured by Nippon Polyurethane Industry Co., Ltd. as a curing agent to 100 parts by mass of this mixed solution is stirred, poured into a centrifugal mold, and reacted at a mold temperature of 110 ° C. for 15 minutes. In a cured state, the core layer is centrifugally molded in the same manner as in Example 1, and a core layer made of 0.2 mm-thick polyurea and an elastic layer made of 0.3 mm-thick polyurethane are laminated and integrated A two-layer belt was obtained.

Comparative Example 1
In Example 1, in place of the modified polyamine, a polyol having a methylene chain part derived from nonanediol and methyloctanediol in the main chain and a carbonate bond part and having a hydroxyl group at the terminal (hydroxyl value = 114.8 KOHmg / g, A single-layer belt was obtained by centrifugal molding in the same manner as in Example 1 except that 50 parts of nonanediol / methyloctanediol mass ratio 65/35, “Kurapol C-1065N” (manufactured by Kuraray Co., Ltd.) was used.

Comparative Example 2
In Example 1, in place of the modified polyamine, a polyol having a methylene chain part derived from nonanediol and methyloctanediol in the main chain and a carbonate bond part and having a hydroxyl group at the terminal (hydroxyl value = 114.8 KOHmg / g, Nonanediol / methyloctanediol mass ratio 65/35, “Kurapol C-1065N” manufactured by Kuraray Co., Ltd.) was used, norbornene diisocyanate, which is a bifunctional isocyanate, was hexamethylene diisocyanate, and the average number of functional groups was 2.13. A belt was obtained in the same manner as in Example 1 except that mixing was performed.

Comparative Example 3
In Example 1, instead of the modified polyamine, a belt was obtained in the same manner as in Example 1 except that 52.1 parts of a polyol composed of polyester consisting of methylpentanediol and sebacic acid and having a hydroxyl group at the terminal was used. It was.

Comparative Example 4
After the elastic layer was formed into a semi-cured state by centrifugal molding in the same manner as in Example 3, the core layer was centrifugally molded by the blending of Comparative Example 1, and a core layer composed of 0.2 mm-thickness urea-bonded polyurethane and 0 A two-layer belt in which elastic layers made of polyurethane having a thickness of 3 mm were laminated and integrated was obtained.

Comparative Example 5
In Example 1, except that norbornene diisocyanate, which is a bifunctional aliphatic isocyanate, is diphenylmethane diisocyanate, which is a bifunctional aromatic isocyanate, the average number of functional groups is 2.13. An attempt was made to obtain a belt, but gelation occurred 30 seconds after mixing, and molding was impossible.

〔Evaluation methods〕
Using sample belts obtained by cutting the thin cylindrical belts obtained in the above Examples and Comparative Examples into a width of 30 mm, elongation and curling were evaluated by the following methods, and the results are shown in Tables 1 and 2. The evaluation was performed in an environment with a temperature of 23 ° C. and a humidity of 55% and an environment with a temperature of 32 ° C. and a humidity of 80%.

(Evaluation of elongation)
As shown in the measuring apparatus of FIG. 6, the sample belt 41 (length 550 mm × width 30 mm) is wound around two pulleys (an outer diameter of 20 mm), which are a fixed pulley 46 and a slide pulley 47, and the weight 42 (1 kg) is used to wrap the belt. Was given tension. The elongation when the tension was applied by the weight (initial elongation) and the elongation after being allowed to stand for 24 hours while being tensioned by the weight were measured with the dial gauge 43. The measured value of elongation after 24 hours—the measured value of initial elongation (mm) was obtained by calculation, and the results are shown in Tables 1 and 2.

(Evaluation of rolls)
As shown in FIG. 7, it is attached to the apparatus shown in FIG. 6, tensioned by the weight 42, left for 24 hours, then removed from the belt, cut into a length of about 100 mm around the portion of the belt held around the pulley. The top height t was measured with a height gauge. The measured apex height (mm) is shown in Tables 1 and 2 as a curl.

From Tables 1 and 2, the conventional polyurethane belt (Comparative Example 3) obtained by using an ester-based polyol as the active hydrogen-containing compound has particularly large curl at high temperature and high humidity, and has a carbonate bond to the main chain of the polyol. In the belts (Comparative Examples 1, 2, and 4) provided with a part and a methylene chain part, the improvement is recognized as compared with Comparative Example 3. It is clear that the belt of the example using a polyamine having a carbonate bond part and a methylene chain part in the main chain instead of the polyol is sufficiently improved in elongation and curl compared to the belt of the comparative example. became. Further, the belts obtained in the examples were excellent in moldability.

The belt for an electrophotographic apparatus of the present invention can be suitably used as, for example, an intermediate transfer belt or a transfer conveyance belt.

It is an example of the perspective view of the belt 1 for electrophotographic apparatuses of this invention. It is an example of the perspective view of the belt 1 for electrophotographic apparatuses of this invention. It is an example of the perspective view of the belt 1 for electrophotographic apparatuses of this invention. 1 is an example of a side view of the periphery of a photoreceptor 11 of an electrophotographic apparatus using the belt for an electrophotographic apparatus of the present invention as an intermediate transfer belt 16. FIG. 2 is an example of a side view of the periphery of a photoreceptor 11 of an electrophotographic apparatus using the electrophotographic apparatus belt of the present invention as a transfer conveyance belt 16 ′. It is the schematic of the apparatus used for generation | occurrence | production of an elongation and a curl. It is the schematic of the measuring apparatus of the vertex height which is a curl.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic belt 2 Core layer 3 Elastic layer 4 Surface layer 11 Photoreceptors 12, 13 Pulley 14 Developing section 15 Transfer roller 16 Intermediate transfer belt 16 'Transfer conveyance belt 41 Belt 42 Weight 43 Dial gauge 44 Surface plate 45 Height gauge 46 Fixed pulley 47 Slide pulley 48 Slide bearing

Claims (6)

Polyurea obtained by reacting a modified polyamine having a carbonate bond part and a methylene chain part in the main chain and having an amino group at the terminal, an aromatic amine compound and a bifunctional and trifunctional aliphatic isocyanate A belt for an electrophotographic apparatus, characterized in that it is formed into a thin cylindrical shape. The belt for an electrophotographic apparatus according to claim 1, wherein the methylene chain portion is derived from nonanediol and methyloctanediol, and the terminal amino group is an amino group of di-p-aminobenzoate. The belt for an electrophotographic apparatus according to claim 1, wherein the aromatic amine compound is 4-chloro-3,5-diaminobenzoic acid isobutyl ester. 4. The belt for an electrophotographic apparatus according to claim 1, wherein the bifunctional aliphatic isocyanate is norbornene diisocyanate, and the trifunctional aliphatic isocyanate is an isocyanurate modified product of hexamethylene diisocyanate. Furthermore, it is composed of a laminated structure having an elastic layer,
The electrophotographic belt according to claim 1, wherein the elastic layer contains a polyurethane resin. 6. The electrophotographic apparatus belt according to claim 1, wherein the electrophotographic apparatus belt is an intermediate transfer belt or a transfer conveyance belt.

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