JP2008033100A - Toner supply roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner supply roller which has small compression set even in a high temperature and high humidity environment, has a low hysteresis loss rate and stable electric resistance even in a low temperature and low humidity environment, achieves satisfactory and uniform supply and scraping of toner to suppress an increase in toner consumption, and can provide an image with reduced density unevenness. <P>SOLUTION: The toner supply roller 1 has a surface layer 3 comprising polyurethane foam obtained using a polyol, a polyisocyanate and an ionic conductivity imparting agent. The polyol contains a polyether polyol in an amount of ≥50 parts by mass based on 100 parts by mass of the total polyol, wherein the polyether polyol has a total degree of unsaturation of ≤0.050 meq/g and a mass average molecular weight of 4,500-8,000. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner supply roller used in a developing device of an image forming apparatus.

  Image forming apparatuses such as copying apparatuses, image recording apparatuses, printers, and facsimile machines are provided with a developing device that develops an electrostatic latent image formed on a latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric. It is done. In the developing device, for example, a developing container for storing a predetermined toner (developer) and an opening of the developing container are closed, a part is exposed, and the exposed part is arranged to face the latent image carrier. A developer carrier such as a developing roller that supplies toner to the latent image carrier is provided. Provided on the surface of the developing roller are a toner supply roller that supplies toner in the developing container, a blade that forms a thin film of toner by removing excess toner on the developing roller, and the like.

  The toner supply roller used in such a developing device is required to have low hardness, that is, flexibility in order to supply toner to the surface of the developing roller and scrape unnecessary parts at the same time to supply a certain amount of toner. Is done. For this reason, what has the surface layer which consists of foaming elastic bodies, such as a polyurethane foam, is used. Further, when image formation is performed on the toner supply roller after a standby state for a long time, the deformed portion in contact with the developer carrying member in the standby state is recovered immediately, so that no compression set is generated. In addition, sufficient recoverability is required. However, in a high-temperature and high-humidity environment such as a temperature of 40 ° C. and a relative humidity of 95%, there is a case where the recovery becomes worse due to compression set. In a low-temperature and low-humidity environment such as a temperature of 15 ° C. and a relative humidity of 10%, the hysteresis loss rate may increase and the recovery from distortion due to the developer carrying member may be reduced. There is a problem in that the toner supply to the developer carrying member and the scraping are nonuniform in the portion where such compression set has occurred, causing image defects such as density unevenness in the formed image.

  A polyether polyol having a total degree of unsaturation of 0.050 meq / g or less and a mass average molecular weight of 4500 or more and 8000 or less as a surface layer of a toner supply roller having low hardness and low compression set even under high temperature and high humidity. The polyurethane foam used has been reported. (Patent Document 1). In such a toner supply roller using a polyether polyol having a low degree of unsaturation and a high molecular weight, the occurrence of compression set can be reduced, and the hysteresis loss rate is reduced. Therefore, it has sufficient recoverability against the compressive force at the contact portion with the developer carrying member, the toner supply and scraping to the developer carrying member are uniform, the toner supply property is improved, and the lightness and shade are improved. A clear and excellent image quality can be obtained. However, since the toner supply performance is improved and the image density is increased, density unevenness is likely to be noticeable, and toner consumption may be increased.

On the other hand, as a method for obtaining a conductive polyurethane foam member having stable fine cells and good appearance, a method using a specific foam stabilizer and an electrolyte has been reported (Patent Document 2). Further, as a method for obtaining a semiconductive charging member capable of obtaining stable electrical resistance, a method using perchlorate as an ionic conductivity imparting agent has been reported (Patent Document 3). Such an ion conductivity-imparting agent is excellent in dispersibility and can reduce the resistance of the toner supply roller with a small amount, but there may be a problem with image performance in the toner supply roller. For example, depending on the polyol used, good hardness at low hardness and recovery from compression set deteriorate, the hysteresis loss rate cannot be reduced, and compression set at the contact portion with the developed image carrier This may cause image defects such as density unevenness.
JP 2004-037630 A JP 2002-363237 A Japanese Patent Laid-Open No. 2001-9958

  An object of the present invention is to provide a toner supply roller having a small compression set even under high temperature and high humidity, a low hysteresis loss rate even under low temperature and low humidity, and a stable electric resistance value. It is another object of the present invention to provide a toner supply roller that can perform toner supply and scraping well and uniformly, suppress an increase in toner consumption, and obtain an image with reduced density unevenness. .

  The present invention relates to a toner supply roller having a surface layer made of a polyurethane foam, wherein the polyurethane foam is obtained using a polyol, a polyisocyanate, and an ionic conductivity imparting agent, and the polyol is a polyether polyol and the total polyol 100 The present invention relates to a toner supply roller comprising 50 parts by mass or more with respect to parts by mass, wherein the polyether polyol has a total unsaturation value of 0.050 meq / g or less and a mass average molecular weight of 4500 or more and 8000 or less.

  The toner supply roller of the present invention has a small compression set even under high temperature and high humidity, and has a low hysteresis loss rate and a stable electric resistance value even under low temperature and low humidity. Therefore, the toner can be supplied and scraped well and uniformly, the increase in toner consumption can be suppressed, and an image with reduced density unevenness can be obtained. .

  The toner supply roller of the present invention is a toner supply roller having a surface layer formed of a polyurethane foam, wherein the polyurethane foam is obtained using a polyol, a polyisocyanate, and an ionic conductivity imparting agent, and the polyol is The ether polyol is contained in an amount of 50 parts by mass or more based on 100 parts by mass of the total polyol, the polyether polyol has a total degree of unsaturation of 0.050 meq / g or less, and a mass average molecular weight of 4500 or more and 8000 or less. To do.

  The polyurethane foam forming the surface layer of the toner supply roller of the present invention has low hardness and flexibility, and has a function of supplying toner to a developer carrier such as a developing roller and scraping off an unnecessary amount. Such a polyurethane foam is obtained using a polyol, a polyisocyanate, and an ionic conductivity imparting agent, and is formed using a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries as necessary.

[Polyol]
The polyol used for forming the polyurethane foam contains 50 parts by mass or more of polyether polyol with respect to 100 parts by mass of the total polyol.

  As such a polyether polyol, the total degree of unsaturation is 0.050 meq / g or less, preferably 0.035 meq / g or less. In general, polyether polyols contain unreacted monomers (hereinafter referred to as monools) such as alkoxides and polyhydric alcohols as raw materials in a mass ranging from several percent to several tens percent. It is known that the total degree of unsaturation varies depending on the monool content. That is, the smaller the total unsaturation value, the lower the monool content. When the total unsaturation degree of the polyether polyol is 0.050 meq / g or less, the monool contained is small, and in the reaction with the polyisocyanate, a network structure is uniformly formed, and the compression set under high temperature and high humidity is reduced. Occurrence can be suppressed.

  Here, as the total degree of unsaturation, a value measured by a method according to JIS K-1557 can be employed.

  Furthermore, a polyether polyol having a low monool content can reduce the addition ratio (isocyanate index) of polyisocyanate and efficiently form a network structure. The reason for this is that in polyether polyols with a low monool content, the production amount of the reaction product of monool and polyisocyanate that prevents the formation of a network structure can be reduced.

  Further, the polyether polyol preferably has an isocyanate index of 60 or more and 120 or less, and more preferably 70 or more and 100 or less. If the isocyanate index is 60 or more, resinization can be facilitated and moldability can be improved, and if it is 120 or less, a low-hardness polyurethane foam can be obtained.

  Here, the isocyanate index is represented by an equivalent ratio of NCO groups to active hydrogen groups (NCO group equivalent / active hydrogen group equivalent) × 100 in the reaction with isocyanate.

  Furthermore, the polyether polyol has a mass average molecular weight of 4500 or more and 8000 or less. If the mass average molecular weight is 4500 or more, the hysteresis loss rate of the polyurethane foam can be kept low and the hardness can be lowered without the physical properties changing rapidly under low temperature and low humidity. When the mass average molecular weight is 8000 or less, it is possible to suppress high viscosity, easy handling, uniform mixing with polyisocyanate, and easy casting. And the polyurethane foam which has a suitable physical property in any use environment from low temperature low humidity to high temperature high humidity can be obtained.

  Furthermore, the polyether polyol preferably has a hydroxyl value of 20 mgKOH / g or more and 50 mgKOH / g or less and an average functional group number of 2.5 or more and 4.0 or less. When the hydroxyl value is 20 mgKOH / g or more, or when the average number of functional groups is 2.5 or more, the occurrence of compression set in the toner supply roller under high temperature and high humidity can be suppressed. If the hydroxyl value is 50 mg KOH / g or less, or if the average number of functional groups is 4.0 or less, the toner supply roller has a low hardness, and the toner is satisfactorily supplied to the developer carrying member and scraped off. be able to. The hydroxyl value is more preferably 20 mgKOH / g or more and 40 mgKOH / g or less.

  Here, the measured value by the measuring method according to JIS K-1557 can be employ | adopted for a hydroxyl value.

  Examples of such polyether polyols include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide and propylene oxide. Further, polyether polyol obtained by ring-opening polymerization of tetrahydrofuran or the like, polycondensation product of polyhydric alcohol, or the like can be used. These can be used alone or in combination of two or more.

  Content of the said polyether polyol is 50 mass parts or more with respect to 100 mass parts of all the polyols. By containing 50 parts by mass or more of the polyether polyol, it is possible to obtain a soft and highly elastic polyurethane foam having excellent moisture resistance and heat resistance and excellent durability. Furthermore, it is preferable to use a polyether polyether polyol containing 5 mol% or more of ethylene oxide because the moldability can be improved.

  These polyether polyols can also be used as prepolymers previously polymerized with polyisocyanates.

  In addition to the polyether polyol, examples of the polyol used in the polyurethane foam include polyether polyols, polyester polyols, polyol polymers, and the like other than those used in the production of flexible polyurethane foam.

[Polyisocyanate]
The polyisocyanate used for forming the polyurethane foam is not particularly limited as long as it has a plurality of isocyanate groups, but preferably contains toluylene diisocyanate. Furthermore, it is preferable to use either a mixture of toluylene diisocyanate, polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate or both. Polyurethane foams formed using these polyisocyanates have low hardness and good moldability, and can suppress the occurrence of compression set even in a toner supply roller in a high temperature and high humidity environment. A prepolymer having an isocyanate group at the terminal obtained by reacting an isocyanate with one or more known active hydrogen compounds and a polyol can also be used as the polyisocyanate.

[Ion conductivity imparting agent]
The ion conductivity-imparting agent used for forming the polyurethane foam generates ionic species by cation solvating by cation solvating with ether oxygen of the polyether polyol. By using an ionic conductivity imparting agent, it is possible to obtain a polyurethane foam in which there is little variation in the position of the electric resistance, little voltage dependence of the electric resistance, and little fluctuation in resistance to environmental changes. Examples of the ion conductivity-imparting agent include tetraethylammonium, tetrabutylammonium, lauryltrimethylammonium, dodecyltrimethylammonium, stearyltrimethylammonium, octadecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified aliphatic dimethylethylammonium. Ammonium salts such as perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkyl sulfate, carboxylate, sulfonate; lithium, sodium, calcium , Alkali metal or alkaline earth metal perchlorate such as magnesium, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfo , And the like salts. These can be used alone or in combination of two or more. Among these, alkali metal perchlorates such as lithium perchlorate are particularly preferable because they have good compatibility with polyols and can be easily and uniformly dispersed. In addition, it is preferable to use an alkali metal perchlorate such as lithium perchlorate in a polymer containing polyalkylene glycol as a main component. Such an ionic conductivity imparting agent can easily disperse perchlorate even in a high-viscosity polyether polyol having a mass average molecular weight of 4500 or more, and also delays the reaction, thereby The effect of improving the openability of the cell can also be obtained. Specific examples include PEL-20A and PEL-100 (trade names) marketed by Nippon Carlit Co., Ltd.

The amount of the ionic conductivity imparting agent used is preferably an amount that imparts a moderate resistance of 1 × 10 ⁴ Ω to 1 × 10 ¹⁰ Ω to the polyurethane foam, more preferably 1 × 10 ⁵ Ω to 1 × 10. It is the amount that gives resistance of ⁸ Ω or less. Specifically, it is preferable to contain 0.01 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol. If the content of the ionic conductivity imparting agent is 0.01 parts by mass or more, the electric resistance in the above range can be obtained, the frictional charging of the toner can be optimized, and the image density in the image forming apparatus is uniform. Can be improved. On the other hand, when it is 10 parts by mass or less, the reaction between the polyol and the polyisocyanate is not inhibited, and the increase in the hysteresis loss rate and the decrease in the durability of the polyurethane foam to be produced can be suppressed.

  A filler-based conductive material such as carbon black, metal powder, and metal oxide powder can be appropriately added as necessary within the range not impairing the function of the polyurethane foam together with such an ion conductivity imparting agent.

[catalyst]
Examples of the catalyst used for the reaction between the polyol and the polyisocyanate include an amine catalyst, an organometallic catalyst, and an acid salt catalyst having an effect of delaying the initial reaction of the amine catalyst or the organometallic catalyst. Can do. Specific examples of the amine catalyst include triethylenediamine, bis (dimethylaminoethyl) ether, N, N, N ′, N′-tetramethylhexanediamine, and 1,8-diazabicyclo (5,4,0) undecene- 7,1,5-diazabicyclo (4,3,0) nonene-5, 1,2-dimethylimidazole, N-ethylmorpholine, N-methylmorpholine and the like can be mentioned. Specific examples of organometallic catalysts include tin octylate, tin oleate, dibutyltin dilaurate, dibutyltin diacetate, tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetrakis (2-ethylhexyloxy) Titanium etc. can be mentioned. Specifically, carboxylate, formate, octylate, borate, etc. can be used as the acid salt catalyst. These can be used alone or in combination of two or more.

[Foaming agent]
In forming the polyurethane foam, a foaming agent can be used as necessary. As a foaming agent, water is particularly preferable because it reacts with polyisocyanate to generate carbon dioxide gas. Specifically, the amount of the blowing agent used is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.1 parts by mass or less and 5 parts by mass or more with respect to 100 parts by mass of the total polyol. is there. As other blowing agents, chlorofluorocarbons (such as HFC-134A) and hydrocarbons (such as cyclopentane) developed for the purpose of protecting the global environment can be used, and these can be used in combination with water.

[Foam stabilizer]
For the formation of the polyurethane foam, a foam stabilizer can be used as necessary. Examples of the foam stabilizer include water-soluble polyether siloxane from polydimethylsiloxane and ethylene oxide (EO) / propylene oxide (PO) copolymer, sodium salt of sulfonated ricinoleic acid, and polysiloxane / polyoxyalkylene copolymer. And the like. Among these foam stabilizers, water-soluble polyether siloxane from polydimethylsiloxane and EO / PO copolymer is preferred. The amount used is preferably 0.1 parts by mass or less and 3 parts by mass or more with respect to 100 parts by mass of the total polyol.

[Other auxiliaries]
For the formation of the polyurethane foam, a crosslinking agent, a flame retardant, a colorant, an ultraviolet absorber, an anti-aging agent, an antioxidant, and the like can be used as long as they do not impair the function of the polyurethane foam. Known crosslinking agents such as triethanolamine and diethanolamine can be used.

[Polyurethane foam (surface layer)]
In the surface layer made of the polyurethane foam, density is preferably no greater than 0.05 g / cm ³ or more 0.20 g / cm ^3, more preferably 0.07 g / cm ³ or more 0.15 g / cm ³ or less is there. Such density can be obtained by adjusting the amount of foaming agent and foam stabilizer used in the polyurethane foam, and by adjusting the degree when physical foaming is used.

  As the density, a value obtained by the measurement method described in the examples can be adopted.

  As thickness of a polyurethane foam, 1 mm or more and 20 mm or less can be mentioned, for example, 2 mm or more and 10 mm or less can be mentioned as a preferable range. By having such a thickness, excellent toner transportability can be obtained.

[Toner supply roller]
In the toner supply roller of the present invention, the hardness is preferably 50 g or more and 300 g or less, more preferably 100 g or more and 250 g or less at a temperature of 15 ° C. or more and 32.5 ° C. or less and a relative humidity of 10% or more and 80% or less. . When the hardness of the toner supply roller is within this range, toner can be supplied satisfactorily. The hysteresis loss rate and compression set rate of the toner supply roller are preferably 20% or less at a temperature of 15 ° C. to 32.5 ° C. and a relative humidity of 10% to 80%. If the hysteresis loss rate and the compression set rate are 20% or less, the occurrence of compression set can be suppressed at the contact portion with the developer carrying member, and a good image can be obtained in the image forming apparatus. it can.

  As the hardness, hysteresis loss rate, and compression set rate, measured values obtained by the measurement methods described in Examples described later can be adopted.

  Specific examples of the toner supply roller include those shown in FIG. 1 (a) front view and FIG. 1 (b) side view. A toner supply roller 1 shown in FIG. 1 includes a cored bar 2 and a surface layer 3 made of polyurethane foam on the cored bar 2.

  The cored bar 2 may be made of iron or aluminum having a columnar shape or a cylindrical shape. The outer diameter of the cored bar can be set to 2 mm or more and 10 mm or less, for example.

  As the toner supply roller, a functional layer such as an elastic layer may be appropriately provided between the cored bar and the surface layer, and an adhesive layer made of an adhesive for bonding them together may be provided.

[Toner supply roller manufacturing method]
An example of the method for producing the polyurethane foam is as follows. First, after the above-mentioned polyol, polyisocyanate, ion conductivity imparting agent and, if necessary, foam stabilizer, catalyst, foaming agent such as water, and other auxiliary agents are mixed homogeneously, the mixture is cast or It is molded into a predetermined shape such as a plate shape or a cylindrical shape, and freely foamed. Thereafter, heating, reaction curing of polyol and polyisocyanate, and a method of molding a polyurethane foam can be exemplified.

  There are no particular restrictions on the temperature and time for mixing the raw materials. For example, the mixing temperature is 10 ° C. or higher and 90 ° C. or lower, preferably 20 ° C. or higher and 60 ° C. or lower, and the mixing time is 1 second to 10 seconds. For example, about 3 seconds to 5 minutes can be mentioned.

  Moreover, there is no restriction | limiting in particular about the foaming method, Any methods, such as the method of using a foaming agent and the method of mixing bubbles by mechanical stirring, can be used. The expansion ratio can be determined as appropriate.

  As a method for joining the polyurethane foam and the core metal, when the polyurethane foam layer is produced by casting, a method of using a core metal coated with an adhesive in advance can be used. Moreover, the method of winding and adhering the polyurethane foam which shape | molded the mixture in the predetermined shape around the core metal which apply | coated the adhesive agent can be mentioned. A material such as a hot melt sheet can be used as the adhesive.

  Polyurethane foam joined around the core metal may be molded into a predetermined size by polishing treatment.

  Of the above-described manufacturing methods, the method for casting the toner supply roller is preferably a casting method. Specifically, first, a metal core is placed in a mold such as a pipe-shaped mold or a split mold, preferably a pipe-shaped mold, and the above raw material mixture is injected to cause a foaming reaction. Thereafter, it is cured to obtain a toner supply roller.

  The toner supply roller of the present invention thus obtained has low hardness and moderate flexibility, excellent physical property stability regardless of the use environment, and can uniformly supply and scrape the toner. An increase in toner consumption can be suppressed, and an image with reduced density unevenness can be obtained.

The toner supply roller of the present invention will be specifically described below, but the technical scope of the present invention is not limited to these.
[Examples 1-4, Comparative Examples 1-4]
The raw materials were mixed at a blending ratio shown in Table 1 using a mixer (stirrer tornado: manufactured by ASONE) at a liquid temperature of 23 ° C. for 5 seconds. A metal shaft having a diameter of 5 mm and a length of 290 mm was placed in a pipe mold having an inner diameter of 16 mm, and the obtained mixture was injected. It was heated and cured in an oven at 60 ° C. for 30 minutes to produce a polyurethane foam having a thickness of 5.5 mm. Thereafter, the mold was removed to obtain a toner supply roller.

  About the obtained toner supply roller, the density of the polyurethane foam, the hardness of the toner supply roller, the hysteresis loss rate, and the electric resistance value were measured by the following methods. The results are shown in Table 1. Table 1 shows the total unsaturation degree, hydroxyl value, and isocyanate index of the polyether polyol measured by the following method.

[Hydroxyl value]
It was measured by the method described in JIS K-1557.

[Total unsaturation]
It was measured by the method described in JIS K-1557.

[Hysteresis loss rate]
The hysteresis loss rate of the toner supply roller was measured using a jig 4 having a plate-like pressing surface having a length of 50 mm and a width of 10 m (thickness of 10 mm) shown in FIG. 1 according to JIS K 6400 method. The toner supply roller 1 is supported by the core metal 2 at both ends thereof, and the surface layer 3 is pressed by the jig 4 at a speed of 10 mm / min to be deformed by 2 mm, and then the jig is moved at a speed of 10 mm / min. The load and the roller deformation amount curve when it was opened were determined. The hysteresis loss rate was obtained from the area ratio between when the 2 mm deformation was pressed and when it was opened. The numerical values shown in Table 1 are values obtained as an average obtained by measuring three locations in the axial direction and measuring four locations at 90 ° in the circumferential direction at a position in each axial direction, for a total of 12 locations. Measurement is performed at a temperature of 23 ° C., a relative humidity of 53% (hereinafter referred to as N / N environment), a temperature of 15 ° C., a relative humidity of 10% (hereinafter referred to as L / L environment), a temperature of 32.5 ° C., and a relative humidity of 85% ( (Hereinafter referred to as “H / H environment”).

[hardness]
The hardness of the toner supply roller is obtained from the area ratio between the time of 1 mm deformation pressing and the time of release based on the load and deformation amount curve when the deformation due to pressing of the surface layer by the jig 4 is 1 mm in the measurement of the hysteresis loss rate. It was. The numerical values shown in Table 1 are based on the average value obtained from the measured values at a plurality of locations, similarly to the measurement of the hysteresis loss rate, and the measurement under the same environment. The hardness thus determined indicates that the surface layer 3 made of polyurethane foam is harder as the value increases.

[Compression set]
The compression set of the toner supply roller was measured using a metal cylinder 5 having a diameter of 16 mm as shown in FIG. 2 (a) front view and (b) side view. The toner supply roller 1 is supported by the core metal 2 at both ends thereof, and the surface layer 3 having a thickness t ₀ is brought into contact with the cylinder 5 and compressed by 1.5 mm, at a temperature of 40 ° C. and a humidity of 95%. The surface layer thickness t ₁ was measured after standing for a period of time and 30 minutes after removal and release. The compression set was determined from the following equation. The numerical values shown in Table 1 are average values of measured values compressed at three locations in the circumferential direction. The degree of restoration of the toner supply roller can be known from the compression set.

Compression set Cs (%) = {(t ₀ −t ₁ ) /1.5} × 100
t ₀ : thickness of the surface layer before the test at the compression position t ₁ : thickness of the surface layer at the compressed position 30 minutes after compression release [density]
The volume V of the urethane foam was calculated, the mass M of the urethane foam was measured, and the density was determined from M / V.

[Electric resistance value]
The electrical resistance value of the toner supply roller is the same as that used in the measurement of compression set. The metal cylinder 5 is pressed in a state in which the cylinder 5 is pressed at both ends with a load of 500 g to enter the surface layer 3 by 1 mm. Measurement was performed by applying 2000 V between the cylinder and the core of the toner supply roller. The measurement was performed in the same environment as the measurement of the hysteresis loss rate.

[Evaluation]
The toner supply roller was evaluated from the above characteristics according to the following criteria.
○: Hardness is 50 to 300 g, hysteresis loss rate is 20% or less, compression set rate is 20% or less, and electrical resistance value is 1 × 10 ⁴ Ω or more and 1 × 10 ¹⁰ Ω or less, regardless of measurement environment. If you are outside

The numerical value in a table | surface represents a mass part.
1) Mitsui Chemicals Polyurethane Co., Ltd .: polyether polyol; mass average molecular weight 7000, hydroxyl value 24 mg KOH / g, total unsaturation 0.025 meq / g
2) Mitsui Chemicals Polyurethane Co., Ltd .: polyether polyol; mass average molecular weight 5000, hydroxyl value 34 mg KOH / g, total unsaturation 0.020 meq / g
3) Mitsui Chemicals Polyurethane Co., Ltd. product: polyether polyol; mass average molecular weight 3100, hydroxyl value 54 mg KOH / g, total unsaturation 0.028 meq / g
4) Mitsui Chemicals Polyurethane Co., Ltd .: polyether polyol; mass average molecular weight 7200, hydroxyl value 23 mg KOH / g, total unsaturation 0.090 meq / g
5) Mitsui Chemicals Polyurethane Co., Ltd .: polyether polyol; mass average molecular weight 3,500, hydroxyl value 55 mg KOH / g, total unsaturation 0.045 meq / g
6) Nippon Carlit Co., Ltd .: ion conductivity imparting agent; mass average molecular weight 1300, hydroxyl value 88 mg KOH / g, containing 10% by mass of lithium perchlorate 7) Toray Dow Corning Co., Ltd .: Silicone foam stabilizer 8 ) Tosoh Co., Ltd .: Tertiary amine catalyst 9) Sankyo Air Products Co., Ltd .: Tertiary amine catalyst 10) Mitsui Chemicals Polyurethanes Co., Ltd .: Polyisocyanate blend (monomeric and polymeric MDI mixture 50 mass) %, TDI 50 mass%), NCO% = 40
11) Number of NCO groups / number of active hydrogen groups × 100.

In Examples 1 to 4, the wet heat compression set rate is 5 to 15%, the hardness is 148 to 254 g, the hysteresis loss rate is 5 to 16%, and the electric resistance value is 1 × 10 ⁶ to 8 × 10 ^{7 in} any measurement environment. Ω. On the other hand, in Comparative Example 1, the wet heat compression set is as good as 5%, but in the L / L environment, the hysteresis loss rate is as large as 42%. In Comparative Examples 2 and 3, the wet heat compression set is 20%. The electrical resistance value was so high that it could not be measured in the L / L environment in Comparative Example 4.

  From the results, it can be seen that the toner supply roller of the present invention has low hardness, little change in physical properties (resistance, hardness, hysteresis loss rate) even under low temperature and low humidity, and is excellent in moisture heat compression set resistance.

It is (a) front view and (b) side view which show an example of the toner supply roller of this invention, and is explanatory drawing of the measuring method of a hysteresis loss rate and hardness. FIG. 4A is a front view illustrating an example of a toner supply roller of the present invention, and FIG. 5B is a side view illustrating a method for measuring compression set.

Explanation of symbols

1 Toner supply roller 2 Core 3 Surface layer 4 Jig 5 Metal cylinder

Claims (5)

  In a toner supply roller having a surface layer made of polyurethane foam, the polyurethane foam is obtained using a polyol, a polyisocyanate, and an ionic conductivity imparting agent, and the polyol is a polyether polyol with respect to 100 parts by mass of the total polyol. A toner supply roller, wherein the polyether polyol has a total unsaturation value of 0.050 meq / g or less and a mass average molecular weight of 4500 or more and 8000 or less.   The toner supply roller according to claim 1, wherein the polyether polyol has a hydroxyl value of 20 mgKOH / g or more and 50 mgKOH / g or less, or an average functional group number of 2.5 or more and 4.0 or less.   The ion conductivity imparting agent is an alkali metal perchlorate, and is contained in a range of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyol. The toner supply roller described. Polyurethane foam, density of 0.05 g / cm ³ or more 0.20 g / cm ³ toner supply roller according to any one of claims 1 to 3, characterized in that less. 5. The toner supply roller according to claim 1, wherein the toner supply roller has a hardness of 50 g or more and 300 g or less, a hysteresis loss rate of 20% or less, and a compression set rate of 20% or less.

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