JP2006154537A - Polyurethane foam for toner supply roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polyurethane foam for toner supply rolls, which can improve toner scrapability and suppliability and can suppress the occurrence of image density difference when printing. <P>SOLUTION: The polyurethane foam for toner supply rolls is used to supply toner to a photoreceptor in a developing part of an image forming apparatus and has the average number of cells based on JIS K6400, of 50 to 80 pieces per 25 mm. It is preferable that the hardness of the foam based on JIS K6400 is 170 to 300N. Furthermore, it is preferable that the polyurethane foam has 3 to 20% heat and moisture distortion after being left at 70°C temperature and 95% humidity for 48 hours. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyurethane foam for a toner supply roll used as a material for a toner supply roll for supplying toner to a photosensitive member in a developing section in an image forming apparatus such as a printer, a facsimile machine, and a copying machine.

  Conventionally, as this type of polyurethane foam for toner supply rolls, elastic foams such as polyurethane foams and rubber sponges have been used, and among them, polyurethane foams are widely used. As the polyurethane foam, those obtained by cutting a soft slab foam into a cylindrical shape or those molded into a cylindrical shape with a molded foam are used. Such a polyurethane foam is a polyester-based polyurethane foam obtained by reacting with a polyisocyanate using a polyester polyol as a polyol, foaming and curing, and having a fine and stable cell and suitable as a toner supply roll. .

  However, since the polyester-based polyurethane foam has poor distortion performance, when it is used as a toner supply roll, it tends to have a set mark in the cartridge, and unevenness is likely to occur during printing. Further, the polyester polyurethane foam has a slow recovery property when deformed, and the toner scraping and supplying properties are poor. Furthermore, since the polyester-based polyurethane foam has high rigidity, it has a drawback of poor durability.

Therefore, a technique using a polyether-based polyurethane foam using a polyether polyol as a polyol has been proposed (see, for example, Patent Document 1 and Patent Document 2). That is, Patent Document 1 discloses a polyurethane foam obtained by reacting and foaming a foam raw material containing an isocyanate-terminated prepolymer obtained by using a polyether-based polymer polyol and polyisocyanate and water. It is described that the body is also used for a toner supply roll. Patent Document 2 includes a polyurethane foam obtained by stirring and mixing a urethane prepolymer synthesized from a polyol and a polyisocyanate and water-dispersed carbon, and a polymer polyol synthesized based on a polyether polyol is used as the polyol. A conductive elastic member is described.
Japanese translation of PCT publication No. 2003-321528 (2nd page) JP 2002-53639 A (pages 2 and 3)

  However, in the conventional polyether-based polyurethane foam, the average number of cells formed inside is specifically 112 to 183 cells / 25 mm (Example 1 to Example 4 of Patent Document 2). The number of cells is relatively large and the cells are relatively small. Therefore, the shape of the cell is likely to be uneven, and the foam tends to be hard. When such a foam is used as a toner supply roll, the scraping and supplying properties of the toner become unstable, There has been a problem that a density difference tends to occur in an image when printing.

  Accordingly, an object of the present invention is to provide a polyurethane foam for a toner supply roll that can improve the scraping and supplying properties of toner and can suppress the occurrence of a difference in image density when printed. It is to provide.

  In order to achieve the above object, the polyurethane foam for a toner supply roll according to the first aspect of the present invention is a polyurethane foam for a toner supply roll used for supplying toner to a photoconductor in a developing section of an image forming apparatus. The average number of cells of a foam based on JIS K6400 is 50-80 / 25 mm.

  A polyurethane foam for a toner supply roll according to a second aspect of the invention is characterized in that, in the invention according to the first aspect, the hardness of the foam based on JIS K6400 is 170 to 300N.

  The polyurethane foam for a toner supply roll according to a third aspect of the present invention is the invention according to the first or second aspect, wherein the wet heat strain after 48 hours at a temperature of 70 ° C. and a humidity of 95% is 3 to 20%. It is characterized by this.

According to the present invention, the following effects can be exhibited.
In the polyurethane foam for a toner supply roll according to claim 1, the average number of cells of the foam based on JIS K6400 is 50 to 80 cells / 25 mm. It becomes large and the cell shape is stabilized, and the hardness of the foam is suppressed. Accordingly, it is possible to improve the scraping and supplying properties of the toner, and to suppress the occurrence of a difference in image density when printing is performed.

  In the polyurethane foam for a toner supply roll according to the second aspect of the present invention, the hardness of the foam based on JIS K6400 is 170 to 300 N, which is a more suitable range for the toner supply roll. Therefore, in addition to the effect of the invention according to the first aspect, the scraping property of the toner can be improved.

  The polyurethane foam for a toner supply roll according to claim 3 has a wet heat strain of 3 to 20% after 48 hours at a temperature of 70 ° C. and a humidity of 95%, and a strain amount in an appropriate range as a toner supply roll. It becomes. Therefore, in addition to the effect of the invention according to claim 1 or 2, it is possible to suppress the occurrence of setting marks when the toner supply roll is set in the toner cartridge.

Hereinafter, embodiments of the present invention will be described in detail.
A polyurethane foam for a toner supply roll in the present embodiment (hereinafter also simply referred to as a foam) is used as a toner supply roll for supplying toner to a photoconductor in a developing unit of an image forming apparatus. It has such a configuration. That is, the polyurethane foam for the toner supply roll has an average cell number of 50 to 80/25 mm based on JIS K6400. By setting the number of cells in such a range, the cell shape is stabilized, the hardness of the foam is suppressed, and when the foam is used as a toner supply roll, the scraping property and supply performance of the toner are improved. In addition, it is possible to suppress the occurrence of an image density difference when printing.

  Such a polyurethane foam is obtained by reacting and foaming and curing a polyurethane foam raw material containing polyols, polyisocyanates, a foaming agent and a catalyst. In that case, the polyol which is a raw material of the polyurethane foam contains at least a polymer polyol, and the foam obtained using the raw material has a hardness of 170 to 300 N based on JIS K6400.

First, the raw material of the said polyurethane foam is demonstrated.
As the polyols, polyether polyols, polyester polyols, and the like are used. In this embodiment, it is preferable to contain a polymer polyol. The polymer polyol is a compound having a polymer chain and having a plurality of hydroxyl groups at the terminals, for example, a polyol obtained by graft copolymerization of an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate with a polyether polyol. Is used. The number average molecular weight of the polymer polyol is preferably 1000 to 7000, more preferably 2000 to 5000, and particularly preferably 2500 to 4500. When the number average molecular weight is less than 1000, the viscosity of the polyurethane foam raw material is low, and the cell shape of the resulting foam is not sufficiently stabilized. When the number average molecular weight exceeds 7000, the viscosity of the polyurethane foam raw material is low. Becomes too high and it becomes difficult to obtain cells of a desired size.

  The number of functional groups (number of hydroxyl groups) of the polymer polyol is preferably 2 to 8, more preferably 2 to 6, more preferably 2.5 to 4 from the viewpoints of reactivity with polyisocyanates, the degree of crosslinking, and the like. It is particularly preferred. The polymer polyol is dispersed in the raw material of the polyurethane foam. The average particle size of the dispersed polymer polyol is preferably 50 μm or less in order to improve the dispersibility. Since such a polymer polyol has the same composition as the toner, the charge amount of the toner is stabilized and the image can be stabilized.

  The content of the polymer polyol is preferably 20 parts by mass or more per 100 parts by mass of polyols. When the content is less than 20 parts by mass, sufficient hardness cannot be obtained in the foam, and the toner scraping performance is lowered when the toner supply roll is used.

  Other polyols are preferably polyether polyols because they are generally excellent in reactivity with polyisocyanates and do not hydrolyze like polyester polyols. Examples of the polyether polyol include polypropylene glycol, polytetramethylene glycol, polyether polyol made of a polymer obtained by addition polymerization of propylene oxide and ethylene oxide to a polyhydric alcohol, and modified products thereof. Examples of the polyhydric alcohol include glycerin and dipropylene glycol.

  Specific examples of polyether polyols include triols obtained by addition polymerization of propylene oxide to glycerin and addition polymerization of ethylene oxide, and diols obtained by addition polymerization of propylene oxide to dipropylene glycol and addition polymerization of ethylene oxide. . The polyethylene oxide unit in the polyether polyol is about 10 to 30 mol%. When the content of the polyethylene oxide unit is large, the hydrophilicity is higher than when the content is low, and the miscibility with highly polar molecules and polyisocyanates is improved, resulting in high reactivity. Become. These polyols can change the hydroxyl value by adjusting the kind of raw material components, the molecular weight, the degree of condensation, and the like.

  As polyester polyols, in addition to condensation polyester polyols obtained by reacting polycarboxylic acids such as adipic acid and phthalic acid with polyols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin, lactone polyester polyols and polycarbonate systems A polyol is used.

  The polyols preferably have a kinematic viscosity of 600 to 6000 mPa · sec at 25 ° C. When the kinematic viscosity is less than 600 mPa · sec, the viscosity of the polyurethane foam raw material becomes low, and it becomes difficult to stably obtain a foam having an appropriate cell shape as a toner supply roll. On the other hand, when the kinematic viscosity exceeds 6000 mPa · sec, the viscosity of the raw material of the polyurethane foam becomes too high, and the formation of the cells is not performed smoothly, and it becomes difficult to stabilize the cell shape.

  Next, the polyisocyanates to be reacted with the polyols are compounds having a plurality of isocyanate groups, specifically tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), and 1,5-naphthalene. Diisocyanate (NDI), triphenylmethane triisocyanate, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), modified products thereof and the like are used. The isocyanate index of the polyisocyanates may be 100 or less or more than 100, but is usually in the range of about 90 to 130. Here, the isocyanate index represents the equivalent ratio of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyol and water as a blowing agent in percentage.

The foaming agent is for foaming polyurethane resin to make polyurethane foam. For example, water, methylene chloride, pentane, cyclopentane, hexane, cyclohexane, dichloromethane, chlorofluorocarbon compounds (trichlorofluoromethane, dichlorodifluoromethane, etc.) Carbon dioxide gas or the like is used. When the foaming agent is water, the blending amount is preferably 1 to 5 parts by mass with respect to 100 parts by mass of polyols in order to make the density of the polyurethane foam 50 to 80 kg / m ³ . When the amount of water is less than 1 part by mass, the amount of foaming is small, and the density of the polyurethane foam tends to exceed 80 kg / m ³ , and when it exceeds 5 parts by mass, the temperature tends to rise during foaming and curing. Physical properties such as hardness and strain are reduced.

  The catalyst is for accelerating the urethanation reaction between polyols and polyisocyanates, and specifically, tertiary such as triethylenediamine, dimethylethanolamine, N, N ′, N′-trimethylaminoethylpiperazine, etc. Examples include amines, organometallic compounds such as tin octylate (tin octoate), acetates, alkali metal alcoholates, and the like. The compounding amount of the catalyst is about 0.05 to 0.5 parts by mass per 100 parts by mass of polyols.

  As the foam stabilizer, any of those usually blended in the raw material of the polyurethane foam can be used. For example, a nonionic composition comprising a silicone compound such as an organosiloxane-polyoxyalkylene copolymer or a silicone-grease copolymer. An anionic surfactant such as a surfactant, or a mixture thereof, sodium dodecylbenzenesulfonate and sodium lauryl sulfate, a phenolic compound, and the like are used. The blending amount of the foam stabilizer is about 0.1 to 2.0 parts by mass per 100 parts by mass of polyols. In addition to the polyurethane raw material, a crosslinking agent, a filler, a stabilizer, a colorant, a flame retardant, a plasticizer, and the like are blended as necessary.

  Then, the polyurethane foam is produced by reacting the raw material of the polyurethane foam to be foamed and cured, but the reaction at that time is complicated, and basically the following reaction is mainly performed. That is, addition polymerization reaction of polyols and polyisocyanates (urethanization reaction), foaming (foaming) reaction of polyisocyanates with water as a blowing agent, and curing of these reaction products with polyisocyanates ( (Crosslinking) reaction. When producing a polyurethane foam, a one-shot method in which a polyol and a polyisocyanate are directly reacted or a polyol and a polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group at the terminal, Any of the prepolymer methods in which polyols are reacted therewith can be employed. Polyurethane foam is foamed and cured in a mold by injecting a polyurethane foam raw material (mixed solution) into a slab foam obtained by foaming and curing at room temperature and atmospheric pressure, and in a mold. Any of the mold foams obtained in this way may be used.

  The polyurethane foam thus obtained is usually a soft polyurethane foam, has an open-cell structure, and has restorability. The average number of cells of the foam based on JIS K6400 is 50-80 / 25 mm, and preferably 55-65 / 25 mm. If the average number of cells is less than 50 cells / 25 mm, the number of cells decreases, the cells become rough, the foam becomes flexible, the toner supply amount becomes excessive when used as a toner supply roll, the toner The scraping ability of the product becomes worse. On the other hand, when the average number of cells exceeds 80 cells / 25 mm, the number of cells is large, the toner supply roll surface is clogged with toner, and when used as a toner supply roll, the toner scraping property and supply property are poor. In addition to being stable, density differences occur in the image when printed.

  Moreover, the hardness based on JIS K6400 of a polyurethane foam becomes like this. Preferably it is 170-300N, More preferably, it is 180-290N. When the hardness is less than 170 N, the foam is insufficient in hardness, and when used as a toner supply roll, the scraping property and supply property of the toner are deteriorated. On the other hand, when the hardness exceeds 300 N, the foam becomes too hard, and when used as a toner supply roll, a set mark tends to be formed in the cartridge, and a tendency to appear as a density difference of an image is exhibited.

  Further, the wet heat strain after 48 hours at a temperature of 70 ° C. and a humidity (relative humidity, RH) of 95% is preferably 3 to 20%, and more preferably 5 to 15%. If the wet heat distortion is within this range, the amount of distortion is in an appropriate range for the toner supply roll, and the occurrence of setting marks can be suppressed when the toner supply roll is set in the toner cartridge. Here, the wet heat strain (%) was compressed by 50% under conditions of a temperature of 70 ° C. and a humidity of 95%, the thickness after 48 hours was measured, and the thickness after 48 hours was subtracted from the original thickness. The thickness is divided by the original thickness and expressed as a percentage. When the wet heat strain is less than 3%, it is difficult to obtain a toner supply roll. On the other hand, when the wet heat strain exceeds 20%, the amount of strain becomes excessive and set marks are likely to occur.

  The rebound resilience of the foam based on JIS K6400 is preferably 30 to 60%, more preferably 35 to 45. By increasing the resilience of the foam, it is difficult to leave a set mark in the cartridge, the recovery is improved when compressed, and the toner scraping and supplying properties are improved. When the resilience is less than 30%, the resilience is small, and when used as a toner supply roll, the scraping property and the supply property of the toner are deteriorated. On the other hand, when the impact resilience exceeds 60%, it is difficult to obtain a good toner supply roll.

In addition, the density of the foam based on JIS K6400, the hardness of the foam, the flexibility is preferably 50~80kg / m ³ approximately from the viewpoint of distortion (Shimenetsuibitsu), 55~65kg / m ³ It is more preferable that When the density is less than 50 kg / m ³ , the foam becomes soft and the resin content decreases, and the scraping property of the toner is insufficient. When the density exceeds 80 kg / m ³ , the foam becomes hard and the resin content decreases. It tends to cause clogging due to insufficient toner supply.

Next, the image forming apparatus will be briefly described.
A charging unit is provided at a position above the photoconductor that is cylindrical and rotates in a certain direction, and charges the surface of the photoconductor to a constant potential by corona discharge. In the rotation direction of the photoreceptor, an exposure unit is provided at a position adjacent to the charging unit, and a pattern corresponding to an image or a character to be recorded in the exposure unit is irradiated with light by a laser oscillator or an LED (light emitting diode). It is configured to be formed as an electrostatic latent image. In the rotation direction of the photosensitive member, a developing unit including a toner supply roll (developing roller) and a toner cartridge is provided at a position adjacent to the exposure unit, and toner as a developer in the toner cartridge is placed on the photosensitive member by the toner supply roll. To be supplied. As the toner supply roll, the aforementioned polyurethane foam for toner supply roll is used.

  Then, the electrostatic latent image on the photoconductor is developed with the toner supplied from the toner supply roll, and is visualized by the toner image. A transfer unit including a transfer roller is provided below the photoconductor, and the recording paper is fed between the photoconductor and the transfer roller. Then, the toner image on the photoconductor is transferred to a recording sheet. A fixing unit is provided in the advancing direction of the recording paper from the transfer unit, and is configured to fix the toner image transferred onto the recording paper and complete printing. The polyurethane foam for a toner supply roll of this embodiment is suitable for a toner supply roll of a color printer in which the toner is non-magnetic.

  When producing a polyurethane foam for a toner supply roll, for example, a polyol including a polymer polyol, a polyisocyanate, water as a foaming agent, an amine catalyst and a foam stabilizer are mixed to obtain a raw material for the polyurethane foam. Prepare. At this time, the kinematic viscosity of the polyols is set to be 600 to 6000 mPa · sec at 25 ° C. And while making polyols and polyisocyanate react, it is made to foam by making polyisocyanate and water react, and a polyurethane foam is manufactured.

  The polyols include polymer polyols, and the kinematic viscosity of the polyols is set in the above-described range to increase the viscosity. In this state, the urethanization reaction, the foaming reaction, and the curing reaction are performed. For this reason, the polyurethane foam obtained has an average cell number based on JIS K6400 in the range of 50 to 80 cells / 25 mm, and when the foam is used as a toner supply roll, the distortion performance is suitable. . In addition, the hardness of the foam based on JIS K6400 is formed in the range of 170 to 300 N, and physical properties such as flexibility are suitable when the foam is used as a toner supply roll.

The effects exhibited by the above embodiment will be described collectively below.
In the polyurethane foam for toner supply roll in the present embodiment, the average number of cells of the foam based on JIS K6400 is formed in the range of 50 to 80 cells / 25 mm. Becomes larger, the cell shape is stabilized, and the hardness of the foam is suppressed. Therefore, when the foam is used as a toner supply roll, it is possible to improve the scraping property and supply property of the toner, and at the same time, it is possible to suppress the occurrence of an image density difference when printing.

  In addition, the foam based on JIS K6400 has a hardness of 170 to 300N, and is more suitable as a toner supply roll, and in particular, can improve the toner scraping property.

  Furthermore, when a heat and heat strain after 48 hours at a temperature of 70 ° C. and a humidity of 95% is formed to be 3 to 20%, a strain amount in an appropriate range is obtained as a toner supply roll, and the toner supply roll is set in a toner cartridge. In addition, the occurrence of set marks can be suppressed.

Hereinafter, the embodiment will be described more specifically with reference to examples and comparative examples, but the invention is not limited to these examples.
(Examples 1-4 and Comparative Examples 1-3)
A mixture was prepared by mixing the polyols, polyisocyanates, water as a blowing agent, catalyst and foam stabilizer shown in Table 1. This mixture is poured into a foam container having a length, width and depth of 500 mm each, foamed at normal temperature and atmospheric pressure, and then passed through a heating furnace to be heated, reacted and cured to obtain a soft slab foam. Obtained. As the polyisocyanate, tolylene diisocyanate [manufactured by Mitsui Takeda, TDI-80 (a mixture of 80% by mass of 2,4-tolylene diisocyanate and 20% by mass of 2,6-tolylene diisocyanate)] is used. The blending amount was determined so that the isocyanate index shown in 1 was obtained. Abbreviations in Table 1 are shown below.

Polyol 1: Polyether polyol, Sanyo Chemical Industries, Sannix GP-3050, hydroxyl value 56 (mgKOH / g)
Polyol 2: Acrylonitrile-styrene graft polymer polyol, manufactured by Asahi Glass Co., Ltd., Exenol 941
Polyol 3: Polyester polyol, manufactured by Nippon Polyurethane Industry Co., Ltd., Nippon Run 101
Catalyst 1: Amine catalyst, manufactured by Kao Corporation, Kaorizer No. 31
Catalyst 2: Amine catalyst, manufactured by Kao Corporation, Kaorizer No. 22
Catalyst 3: stannous octylate, manufactured by Johoku Chemical Industry Co., Ltd., MRH110
Foam stabilizer 1: Silicone surfactant, manufactured by Goldschmidt, B8110
Foam stabilizer 2: Silicone surfactant, manufactured by Goldschmidt, B8300
Kinematic viscosity of polyols: The kinematic viscosity (mPa · sec) at 25 ° C. of polyols consisting of polyol 1, polyol 2 or polyol 3 is shown.

Solid content: The solid content (part by mass) in the polymer polyol was shown.
The obtained polyurethane foam was measured for density, hardness, impact resilience, wet heat strain, and cell number according to the following measurement methods. The results are shown in Table 1.
(Measuring method)
Density (kg / m ³ ), hardness (N), impact resilience (%), and number of cells (pieces / 25 mm): Measured according to JIS K6400 (Testing method for flexible urethane foam). As described above, the wet heat strain (%) is a value calculated by compressing 50% under conditions of a temperature of 70 ° C. and a humidity of 95% and measuring the thickness after 48 hours.

  Further, the soft slab foam was sliced to a thickness of 25 mm, then cut to a length of 500 mm and a width of 250 mm and dried. A shaft supply hole (diameter 4 mm) was made in the foamed body, the shaft was inserted, and the outer periphery was polished so as to have a cylindrical shape, thereby producing a toner supply roll. The toner supply roll was assembled into a toner cartridge, and the toner scraping property, supply property, set mark, image density difference and clogging were measured visually, and evaluation was performed based on the following criteria. The results are shown in Table 1.

Scraping ability: ◯: Toner scraping was sufficient, Δ: Toner scraping was slightly uneven, X: Toner scraping was insufficient.
Supplyability: ◯: Toner supply amount was sufficient, Δ: Toner supply amount was slightly insufficient, X: Toner supply amount was insufficient.

Set mark: ◯: The set mark in the toner cartridge was not seen in the image, and it was good. Δ: The set mark was slightly seen in the image, X: The set mark was seen as a blank image.
Image density difference: ◯: No image density difference was observed, Δ: Image density difference was partially observed, x: Image density difference was observed as a whole.

  Clogging: ○: No toner clogging was observed in the toner supply roll, Δ: Toner clogging was partially observed in the toner supply roll, x: Toner clogging was much in the toner supply roll, Insufficient toner supply.

表１に示したように、実施例１〜４においては、掻き取り性、供給性、セット跡、画像濃度差及び目詰まりについて、いずれも良好な結果を示した。一方、平均セル数が５０個／２５ｍｍ未満の比較例１及び比較例２では、トナーの掻き取り性及び画像濃度差が低下する結果となった。また、平均セル数が８０個／２５ｍｍを越える比較例３では、セット跡、画像濃度差及び目詰まりについていずれも不良であり、トナーの掻き取り性及び供給性についても低い結果であった。

As shown in Table 1, in Examples 1 to 4, good results were obtained with respect to scraping property, supply property, set trace, image density difference and clogging. On the other hand, in Comparative Example 1 and Comparative Example 2 in which the average number of cells was less than 50 cells / 25 mm, the toner scraping property and the image density difference were reduced. Further, in Comparative Example 3 in which the average number of cells exceeded 80 cells / 25 mm, the set marks, the image density difference and the clogging were all poor, and the toner scraping property and the supply property were low.

In addition, this embodiment can also be changed and embodied as follows.
In place of the average cell number, the average cell diameter can be used to evaluate the possibility of use as a toner supply roll.

A polyether polyol having a high molecular weight can be used as the polyol, and the viscosity of the polyol can be increased.
In place of the wet heat strain (%), the compressibility residual strain (%) or the like can be used to evaluate the applicability for the toner supply roll.

-It can also be comprised so that a foam may become hard by making an isocyanate index high, reducing the quantity of the water as a foaming agent, or using a crosslinking agent together.
Further, the technical idea that can be grasped from the embodiment will be described below.

  (1) The foam is obtained by reacting and foaming and curing a polyurethane foam material containing a polyol, a polyisocyanate, a foaming agent and a catalyst, and the polyol contains at least a polymer polyol. The polyurethane foam for a toner supply roll according to any one of claims 1 to 3, wherein the polyurethane foam is a toner supply roll. When comprised in this way, the polyurethane foam which can exhibit the effect of the invention which concerns on any one of Claims 1-3 can be obtained easily.

  (2) The polyurethane foam for a toner supply roll according to the above technical idea (1), wherein the content of the polymer polyol is 20 parts by mass or more per 100 parts by mass of polyols. In this case, the effect of the invention according to the technical idea (1) can be enhanced.

  (3) The polyurethane foam for toner supply roll according to the above technical idea (1) or (2), wherein the solid content in the polymer polyol is 7 to 50 parts by mass per 100 parts by mass of polyols . When configured in this manner, the function of the polymer polyol can be sufficiently exhibited in addition to the effects of the invention according to the technical idea (1) or (2).

  (4) The polyurethane foam for a toner supply roll according to any one of the technical ideas (1) to (3), wherein the kinematic viscosity of the polyols is 600 to 6000 mPa · sec at 25 ° C. body. In this case, the viscosity of the polyurethane foam raw material can be increased, the cell shape of the foam can be stabilized, and the effect of the invention according to any one of the technical ideas (1) to (3) can be improved. .

  (5) The polyurethane foam for a toner supply roll according to any one of the technical ideas (1) to (4), wherein the polyol contains at least a polymer polyol and a polyether polyol. In this case, in addition to the effects of the invention according to any one of the technical ideas (1) to (4), it is possible to improve the scraping property and supply property of the toner.

Claims (3)

A polyurethane foam for a toner supply roll used to supply toner to a photoreceptor in a developing section of an image forming apparatus,
A polyurethane foam for a toner supply roll, wherein the foam based on JIS K6400 has an average cell number of 50 to 80 cells / 25 mm. The polyurethane foam for a toner supply roll according to claim 1, wherein the hardness of the foam based on JIS K6400 is 170 to 300N. 3. The polyurethane foam for toner supply roll according to claim 1, wherein a wet heat strain after 48 hours at a temperature of 70 ° C. and a humidity of 95% is 3 to 20%.