JP5144975B2 - Toner supply roller - Google Patents

Description

  The present invention relates to a toner supply roller used in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, or a facsimile.

  Conventionally, in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, or a facsimile, an electrostatic latent image formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric is developed by a developing device. Thus, visualization as a toner image is performed. In such a developing device, a toner supply roller for supplying toner (developer) to a developing roller that visualizes an electrostatic latent image by applying toner to the image carrier is incorporated.

  The toner supply roller is a roller having an action of supplying toner to the developing roller by impregnating the toner in the polyurethane sponge layer and discharging the toner. It is known that when the entire opening area of the opening of the cell on the surface of the developing roller occupies 20% or more of the surface area of the skin layer of the urethane sponge layer, the toner can be excellently supplied (for example, (See Patent Document 1).

  However, when left in a low-temperature and low-humidity environment for a long period of time, the toner amount applied to the image carrier by the developing roller cannot be controlled by the layer control blade alone due to toner charge-up, etc. Defects sometimes occurred. As a solution to this problem, it is conceivable to reduce the electrical resistance (conductivity) of the toner supply roller.

  On the other hand, as a conductive roller having a polyurethane foam layer with reduced resistance, one using an ionic conductive agent is known (see, for example, Patent Document 2). A conductive roller containing an ionic conductive agent in the polyurethane foam layer has advantages such as low electrical resistance unevenness and low voltage dependency.

  However, when the electrical resistance of the polyurethane foam layer is lowered using an ionic conductive agent, it is known that the electrical resistance value changes greatly depending on the environment such as high temperature and high humidity or low temperature and low humidity. Below, it is difficult to obtain a stable electrical resistance value.

As a method for forming a polyurethane foam layer having a low environmental dependency and a low resistance, a method of forming a polyurethane foam layer using a polyurethane raw material previously blended with conductive carbon black is conventionally known. However, in this method, the viscosity of the polyurethane raw material liquid increases with an increase in the amount of conductive carbon black added, and the cells on the roller surface do not bubble smoothly when forming the polyurethane foam layer. There was a case that did not open sufficiently. That is, in order to form a good cell structure, the amount of conductive carbon black to be added must be limited. For this reason, it was practically impossible to form a conductive polyurethane foam layer having a volume resistivity of 10 ⁷ Ω · cm or less and having sufficiently open cells on the surface.

  As a method for solving this problem, a method of forming a polyurethane foam layer using a polyurethane raw material containing an alkyd resin dispersant and / or a polyester resin dispersant in addition to conductive carbon black has been proposed ( For example, see Patent Document 3.) According to this method, it is disclosed that a polyurethane foam layer having a good foamed state can be obtained even if the increase in the viscosity of the polyurethane raw material liquid is suppressed and the amount of conductive carbon black added is increased (for example, Patent Documents). 3).

  Some polyester resin-based dispersants are mainly dispersed by obtaining electrostatic repulsion by changing the surface charge of carbon black. In addition, there are those in which a compatible chain is adsorbed on the surface of carbon black and is stably dispersed mainly by using steric hindrance to increase the repulsive force between particles. Generally, the polyester resin-based dispersant blended in the raw material of the polyurethane foam layer is of a type that obtains electrostatic repulsion.

  On the other hand, as a polyester resin-based dispersant blended in inks and paints, it is a type that stably disperses by increasing the repulsive force between particles by using steric hindrance by adsorbing compatible chains on the surface of carbon black. It is well known that things are used. However, no investigation has been made on polyurethane raw materials for forming a polyurethane foam layer containing carbon black. Further, even when a polyester resin dispersant that obtains electrostatic repulsion is used, depending on the amount of conductive carbon black added, a sufficient increase in viscosity may not be obtained. In such a case, the cells on the surface of the polyurethane foam layer of the toner supply roller do not open sufficiently, or in some cases do not open at all, or the necessary expansion ratio cannot be obtained, and the toner supply roller becomes high in hardness. There was a case.

JP 09-274373 A JP 11-292948 A JP 2003-98786 A

  The present invention has been made in view of such circumstances of the prior art. The problem to be solved is to provide a low-hardness toner supply roller having a polyurethane sponge layer having a low electrical resistance, a small environmental dependence of the electrical resistance value, and an improved cell opening on the surface. It is.

  The present invention which has solved the above problems is a toner supply roller having a cored bar and a polyurethane sponge layer formed on the outer periphery of the cored bar, wherein the polyurethane sponge layer comprises a polyol component, an isocyanate component, an adsorbing group and a mass average. A toner supply roller obtained by foaming and curing a polyurethane raw material containing a polyester resin dispersant (A) having a molecular weight of 9000 or more and 50000 or less and carbon black.

  According to the present invention, it is possible to provide a toner supply roller that solves the problems of uneven density and low density.

  The toner supply roller of the present invention is a toner supply roller having a cored bar and a polyurethane sponge layer formed on the outer periphery of the cored bar. The polyurethane sponge layer is obtained by foaming and curing a polyurethane raw material containing a polyol component, an isocyanate component, an adsorbing group, a polyester resin dispersant (A) having a weight average molecular weight of 9000 to 50000, and carbon black. It is done.

  The present invention will be described below.

(Toner supply roller)
FIG. 1 is a perspective view showing a schematic configuration of an example of an embodiment of a toner supply roller of the present invention. As shown in FIG. 1, the toner supply roller 1 has a cylindrical cored bar 2 and a polyurethane sponge layer 3 formed on the outer periphery of the cored bar 2. Both end portions of the core metal 2 of the toner supply roller 1 are portions combined with a toner supply roller driving unit of an image forming apparatus or the like, and the polyurethane sponge layer 3 is not provided at these portions.

(Core metal)
As the core 2, a conventional core for a toner supply roller can be used. The cored bar 2 can be made of a metal such as iron, for example. In general, the outer diameter of the cored bar 2 is preferably 2 mm or more and 10 mm or less.

(Polyurethane sponge layer)
The polyurethane sponge layer 3 is obtained by foaming and curing a polyurethane raw material containing a polyol component, an isocyanate component, an adsorbing group, a polyester resin dispersant (A) having a weight average molecular weight of 9000 to 50,000, and carbon black, and carbon black. It is done.

  The polyurethane sponge layer 3 preferably has a cell open area ratio of 20% or more and 90% or less. When the cell opening ratio on the surface is 20% or more, the toner conveyance amount is stabilized and the toner can be supplied uniformly. Further, when the cell opening ratio is 90% or less, such a polyurethane sponge layer can be easily formed. In the present invention, the cell opening ratio is a percentage of the surface area occupied by the opened cells with respect to the total surface area of the surface of the polyurethane sponge layer.

  The cell opening ratio on the surface of the polyurethane sponge layer 3 can be adjusted by appropriately selecting the degree of polymerization of the polyol in the polyurethane raw material, the composition and viscosity of the polyurethane raw material, the type and amount of catalyst used, and the like. Further, when the polyurethane sponge layer 3 is formed using a mold such as a cylindrical mold, the polyurethane sponge layer 3 is formed so that the contact angle between the polyurethane raw material and the inner surface of the mold is within an appropriate range. The inner surface may be surface-treated or a release agent may be applied. In addition, if the cell opening rate of the polyurethane sponge layer 3 surface can be adjusted to the said range, it will not specifically limit, A suitable surface treatment method or a mold release agent can be employ | adopted.

Incidentally, polyurethane sponge layer 3 is usually preferably has a density of 0.05 g / cm ³ or more 0.40 g / cm ³ or less, with a 0.07 g / cm ³ or more 0.35 g / cm ³ or less of the density Those are more preferred. It is preferable that the polyurethane sponge layer 3 has a density in this range because the toner supply property is good.

(Polyurethane sponge layer forming method)
When the polyurethane sponge layer 3 is formed using a mold, the polyurethane raw material is injected into a mold having an inner surface of an ethylene glycol contact angle of 85 degrees or more, heated, and foam-cured. Thus, the polyurethane sponge layer 3 is preferably formed. When using a mold whose inner surface has an ethylene glycol contact angle of 85 degrees or more, due to incompatibility or surface tension action between the surface constituting at least the cavity inner surface of the mold and the polyurethane raw material, The absence of polyurethane raw material results. Usually, the non-existing portion of the polyurethane raw material is the portion closest to the inner surface of the cell mold caused by the foam hardening of the liquid polyurethane raw material, in other words, the portion corresponding to the central portion of the cell where the thickness of the skin layer is the thinnest. Arise. As a result, an opening is formed in the skin layer on the surface of the formed polyurethane sponge layer, and the cell opens to the outside through this opening. If the contact angle of ethylene glycol on the inner surface of the mold becomes smaller than 85 degrees, sufficient incompatibility or surface tension action between the inner surface of the mold and the polyurethane raw material cannot be exhibited, and the cell It is considered that unevenness occurs in the opening and it becomes difficult to obtain a sufficient opening diameter.

  If the contact angle of ethylene glycol is smaller than 85 degrees, the adhesion between the polyurethane sponge layer 3 and the inner surface of the mold becomes strong, and the toner supply roller obtained by foaming and curing in the mold is used as the mold. It may be difficult to release from the mold.

  The inner surface of the mold is not particularly limited as long as the contact angle of ethylene glycol is 85 degrees or more, and the inner surface of the mold is treated with a conventionally known release agent or surface treatment method to contact ethylene glycol. A mold can be used with an angle of 85 degrees or more.

  There is no particular limitation on the temperature and time when mixing the raw materials constituting the polyurethane raw material, but the mixing temperature is usually in the range of 10 to 70 ° C, preferably 20 to 50 ° C, and the mixing time is Usually, it is about 1 second to 10 minutes, preferably about 3 seconds to 5 minutes.

  Further, when foaming and curing, the polyurethane sponge layer 3 can be formed by foaming by a conventionally known method. There is no restriction | limiting in particular about the foaming method here, 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 may be determined as appropriate and is not particularly limited.

  The toner supply roller of the present invention may have an adhesive layer between the cored bar 2 and the polyurethane sponge layer 3 as necessary.

  There is no restriction | limiting in particular about the joining method of a metal core and a polyurethane sponge layer. For example, a core bar is previously disposed inside a mold and the above raw material mixture is cast and cured, or a polyurethane raw material is molded into a predetermined shape to become a polyurethane sponge layer in advance, A method of bonding can be used. In either method, an adhesive layer can be provided between the metal core and the polyurethane sponge layer as necessary. As a material constituting the adhesive layer, a known adhesive material such as an adhesive or a hot melt sheet can be used.

  According to the present invention as described above, a low-hardness toner supply roller having a polyurethane sponge layer with improved cell opening on the surface, which is less dependent on the environment of electrical resistance and has a low electrical resistance, is provided. It becomes possible to do.

The toner supply roller of the present invention has an electrical resistance value measured by applying a voltage of 200 V in an atmosphere of a temperature of 22 ° C. and a relative humidity of 55% and not less than 1 × 10 ⁵ Ω and less than 1 × 10 ⁸ Ω. Preferably there is. Preferably, it is 5 × 10 ⁵ Ω or more and 6 × 10 ⁷ Ω or less. When the electrical resistance value is less than 1 × 10 ⁸ Ω, even when left in a low temperature and low humidity environment for a long time, image defects such as low density due to toner charge-up and the like do not occur. This is presumably because if the electrical resistance value of the toner supply roller is less than 1 × 10 ⁸ Ω, the electrical resistance value is small, so that charge-up can be prevented and the toner amount can be controlled only by the layer regulating blade. . Further, when the electric resistance value is 1 × 10 ⁵ Ω or more, the toner supply amount is made suitable, and the load on the toner can be reduced.

  The toner supply roller of the present invention preferably has a roller hardness of 0.981 N / mm or more and 2.94 N / mm or less (100 gf / mm or more and 300 gf / mm or less). Furthermore, it is more preferable in it being 1.47 N / mm or more and 2.45 N / mm or less (150 gf / mm or more and 250 gf / mm or less). When the roller hardness is 0.981 N / mm or more (100 gf / mm), the scraping property of the residual toner on the surface of the developing roller is improved. Further, when the roller hardness is 2.94 N / mm or less (300 gf / mm or less), stress on the toner on the surface of the developing roller is reduced, and toner deterioration can be prevented.

The roller hardness of the toner supply roller of the present invention can be adjusted by, for example, the following means.
・ Adjust the isocyanate index (100 × (isocyanate equivalent / polyol equivalent)) of polyisocyanate (decrease (increase) isocyanate index to decrease (increase) hardness) ・ Use of foaming agent (eg water) Adjusting the amount (decreasing (increasing) the amount of foaming agent will increase (decrease) the hardness. However, if water is used, if the amount added is too large, the hardness may increase and not excessively added.・ When using a mold, adjust the filling rate of the polyurethane raw material injected into the mold (increasing (decreasing) the filling rate results in a high specific gravity (low specific gravity) and a hardness of To be larger (smaller))

(Carbon black)
Carbon black used in the present invention are those preferably less DBP oil absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g. DBP absorption, the use of less carbon black 300 cm ^3/100 g or more 550 cm ^3/100 g, it is possible to reduce the resistance of the polyurethane sponge layer. DBP oil absorption amount of carbon black, if it is 300 cm ^3/100 g or more, the conductive property can be easily obtained, it is possible to reduce the resistance of the polyurethane sponge layer with the addition of a small amount of carbon black, the hardness of the polyurethane sponge layer It won't be too high. Moreover, when it is set as carbon black whose DBP oil absorption is 550 cm < ³ > / 100 g or less, the increase in the viscosity of the polyurethane raw material containing carbon black is suppressed, and the effect of a dispersing agent can be improved. The carbon black used in the present invention preferably has a BET specific surface area of 1000 m ² / g or more and 1400 m ² / g or less.

  Carbon black is preferably contained in the polyurethane raw material in an amount of 1.0% by mass or more and 25.0% by mass or less, and 1.0% by mass or more and 5.0% by mass with respect to the total mass of the polyol component of the polyurethane raw material. % Or less is more preferable. When 1.0% by mass or more of carbon black is contained with respect to the total polyol component mass of the polyurethane raw material, the resistance can be sufficiently lowered. Further, when 25.0% by mass or less of carbon black is contained with respect to the total polyol component mass of the polyurethane raw material, the hardness of the toner supply roller is lowered and the toner is hardly deteriorated.

(Polyester resin dispersant (A))
The polyester resin dispersant (A) used in the present invention comprises an adsorbing group and a side chain having a weight average molecular weight of 9000 to 50000. The mass average molecular weight of the side chain of the polyester resin dispersant (A) is preferably 9000 or more and 35000 or less. More preferably, it is 9000 or more and 25000 or less. When the mass average molecular weight of the side chain of the polyester resin dispersant (A) is less than 9000, the side chain is shortened, and it may be difficult to obtain an effect of preventing aggregation due to steric hindrance. It may be difficult to maintain a stable dispersion state. If the weight average molecular weight of the side chain of the polyester resin dispersant (A) is greater than 50,000, the viscosity of the polyester resin dispersant (A) itself becomes large, making it difficult to handle or constituting a polyurethane sponge layer. It may be difficult to dissolve in the material. There are various types of adsorbing groups such as basic, acidic, and nonionic, but basic adsorbing groups are preferred for carbon black. The mass average molecular weight of the polyester resin dispersant (A) can be measured using size exclusion chromatography or the like.

  The polyester resin dispersant (A) is preferably contained in the polyurethane raw material in an amount of 0.5% by mass or more and 10.0% by mass or less, based on the total polyol component mass of the polyurethane raw material. More preferably, it is contained in an amount of 5.0% by mass or less. When the polyester resin dispersant (A) is contained in an amount of 0.5% by mass or more based on the total polyol component mass of the polyurethane raw material, an increase in the viscosity of the polyurethane raw material can be suppressed. This facilitates the molding of the polyurethane sponge layer. When the polyester resin dispersant (A) is contained in an amount of 10.0% by mass or less based on the total polyol component mass of the polyurethane raw material, the polyester resin dispersant (A) oozes out and is in contact with the toner supply roller. The developing roller is not contaminated.

  Examples of the polyester resin dispersant (A) that can be used in the present invention include SOLPERSE 71000 (manufactured by Nippon Lubrizol Co., Ltd.) and SOLPERSE 20000 (manufactured by Nippon Lubrizol Co., Ltd.).

(Polyol component)
There is no restriction | limiting in particular in the polyol component used by this invention, For example, polyether polyol, polytetramethylene ether glycol, THF-alkylene oxide copolymer polyol, polyester polyol etc. can be used conveniently. Acrylic polyol, polyolefin polyol, partially saponified product of ethylene-vinyl acetate copolymer, phosphate polyol, halogen-containing polyol, and the like can be suitably used.

  The polyol component used in the present invention is preferably a polyether polyol having a mass average molecular weight of 2500 to 7500. When the weight average molecular weight of the polyether polyol is 7500 or less, the viscosity becomes easy to handle, and mixing with other components of the polyurethane raw material and casting of the prepared polyurethane raw material into the mold are facilitated. Moreover, the hardness of the polyurethane sponge layer formed as the mass average molecular weight of polyether polyol is 2500 or more can be made low. The mass average molecular weight of the polyether polyol is more preferably 3000 or more and 6000 or less.

  Further, the polyether polyol preferably has an average functional group number of 2 or more and 4 or less. When the average number of functional groups is 2 or more, there is a tendency that compression set in a high-temperature and high-humidity environment of the produced toner supply roller is improved. Further, when the average functional group number is 4 or less, the hardness of the toner supply roller can be lowered.

(Isocyanate component)
In the present invention, the isocyanate component is not particularly limited, and general-purpose toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or crude-MDI (polymeric MDI) can be used. Further, not only polymeric MDI (modified MDI) but also a special isocyanate may be used. Examples of the special isocyanate include 1,5-naphthalene diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and p-phenylene diisocyanate. Examples of the special isocyanate include transcyclohexane-1,4-diisocyanate, xylylene diisocyanate (XDI), hydrogenated-XDI, hydrogenated-MDI, lysine diisocyanate, and triphenylmethane triisocyanate. Examples of the special isocyanate include tris (isocyanate phenyl) thiophosphate, tetramethylxylene diisocyanate, lysine ester triisocyanate, and 1,6,11-undecane triisocyanate. Further, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate and the like can be mentioned. These special isocyanates can also be suitably used.

  As the isocyanate component, an isocyanate component containing 20% or more of toluene diisocyanate (TDI) is preferable. The total amount of toluene diisocyanate, diphenylmethane diisocyanate or a derivative thereof contained in 100 parts by mass of the isocyanate component is preferably contained in an amount of 20 parts by mass or more. When the total amount is 20 parts by mass or more, the air flow rate is high, the isocyanate component has a suitable viscosity, is easily mixed with the polyol component, and the cell diameter is easily made uniform. As the isocyanate component, a prepolymer obtained by reacting with a polyol in advance may be used.

  The isocyanate index (100 × (number of NCO groups / number of active hydrogen groups)) is preferably 70 or more and 120 or less. When the isocyanate index is 70 or more, resinization is sufficient, and the moldability of the toner supply roller is improved. If the isocyanate index is 120 or less, the hardness will not be too high.

(catalyst)
In the present invention, a catalyst can be used as necessary. There is no restriction | limiting in particular in the kind of catalyst, You may use a conventionally well-known thing. For example, the following catalyst is used.

<Amine-based catalyst>
Triethylenediamine, bis (dimethylaminoethyl) ether, N, N, N ′, N′-tetramethylhexanediamine, 1,8-diazabicyclo (5,4,0) undecene-7
1,5-diazabicyclo (4,3,0) nonene-5
・ 1,2-Dimethylimidazole ・ N-Ethylmorpholine ・ N-Methylmorpholine

<Organic metal catalyst>
・ Tin octylate, tin oleate, dibutyltin dilaurate, dibutyltin diacetate,
・ Tetra-i-propoxy titanium, tetra-n-butoxy titanium, tetrakis (2-ethylhexyloxy) titanium

<Acid acid catalyst>
Acid catalyst (carboxylate, formate, octylate, borate, etc.) with reduced initial activity of the amine catalyst and organometallic catalyst

  One kind of the catalyst may be used, or two or more kinds may be used in combination.

(Foaming agent)
In the present invention, a foaming agent can be used as necessary. In particular, water is suitably used as a blowing agent because it reacts with polyisocyanate to generate carbon dioxide. In addition, chlorofluorocarbons (HFC-134A, etc.), hydrocarbons (cyclopentane, etc.) developed for the purpose of protecting the global environment, other blowing agents, and these in combination with water The gist of the invention is not impaired.

(Foam stabilizer)
In the present invention, a foam stabilizer can be used as necessary. As a foam stabilizer, the following are mentioned, for example.
・ Water-soluble polyether siloxane obtained from polydimethylsiloxane and ethylene oxide / propylene oxide copolymer ・ Sodium salt of sulfonated ricinoleic acid and mixtures of these with polysiloxane and polyoxyalkylene copolymers Among these foam stabilizers Water-soluble polyether siloxane obtained from polydimethylsiloxane and ethylene oxide / propylene oxide copolymer is preferred.

(Other auxiliaries)
In the present invention, as the auxiliary agent, an appropriate amount of a crosslinking agent, a flame retardant, a colorant, an ultraviolet absorber, an anti-aging agent, an antioxidant, a conductivity imparting agent and the like can be used as necessary. Addition of these auxiliaries as necessary does not impair the gist of the present invention.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Needless to say, the present invention is not limited by the description of the embodiments.

  The cell aperture ratio, electrical resistance, and hardness of the surface of the toner supply roller produced in this example and the comparative example were measured by the following methods.

(Cell opening ratio on the surface of the toner supply roller)
The cell opening ratio of the surface of the toner supply roller is the ratio of the area occupied by the open portion (cell) to the total surface area of the polyurethane sponge layer of the toner supply roller, and was measured as follows. That is, determine the total area S _t of the area S _o and the photographic image occupying an optical micrograph image or an electron micrograph image of polyurethane sponge layer surface of the toner supply roller of open cells was calculated by the following equation.
Cell aperture ratio = 100 × (S _o / S _t )

(Electric resistance of toner supply roller)
The both ends of the core of the toner supply roller are pressed against a stainless steel drum having an outer diameter of 30 mm so that the outer diameter of the toner supply roller is crushed by 1 mm, and a voltage of 200 V is applied between the core and the stainless steel drum. The current value was measured, and the resistance value was calculated according to Ohm's law. The electric resistance of the toner supply roller was measured in an environment of 22 ° C./55% RH (N / N).

(Toner supply roller hardness)
First, when the toner supply roller is pressed at 12 locations in total, 3 locations in the axial direction of the toner supply rollers produced in the present embodiment and the comparative example, 4 locations every 90 degrees in the circumferential direction in each axial direction. The load-deformation curve was measured. A method for measuring the load-deformation curve will be described with reference to FIG. As shown in FIG. 2, the toner supply roller 1 was supported by a core metal support 4 of a compression tester (not shown) at both ends of the core metal 2. Further, a jig having a plate-like pressing surface of 50 mm length (toner supply roller longitudinal direction) × width 10 mm × thickness 10 mm was attached to the compression tester. Next, with a compression tester, the toner supply roller was pressed at a speed of 10 mm / min to be deformed by 2 mm, and a load-deformation amount curve when the toner supply roller was pressed was measured. From the load-deformation curve obtained by the measurement at the 12 locations of the toner supply roller, the hardness was determined as follows. From each of the load-deformation amount curves measured in an environment of a temperature of 23 ° C. and a relative humidity of 53%, the load S1 (on the surface of the toner supply roller when the deformation amount Δ (mm) = 1 mm is obtained by pressing. N) was determined, the hardness (N / mm) was determined by the following formula, and the average value was defined as the hardness of the roller. The larger this value is, the harder the polyurethane sponge layer 3 is.
Hardness (N / mm) = S1 / Δ

(Image evaluation)
Each toner supply roller produced in this example and the comparative example was incorporated by modifying a cartridge for a laser beam printer (hp color Laser Jet 4600, trade name, manufactured by Hewlett-Packard Japan). This modified cartridge is installed in the above laser beam printer and left in a 10 ° C / 15% RH (L / L) environment for one week, and then image evaluation is performed in a 10 ° C / 15% RH (L / L) environment. Went. Fifty sheets were printed, the fog at that time was visually observed, and image evaluation was performed based on the following criteria from the obtained results.
○: Good image △: No problem in use ×: Defects were clearly recognized

The following materials were prepared as raw materials for forming the polyurethane sponge layers of the toner supply rollers of Examples and Comparative Examples.
(1) Carbon black and carbon ECP
(Trade name, Ketchen Black International Co., Ltd., DBP oil absorption = 360cm ³ / 100g, BET specific surface area = 800m ² / g)
・ Carbon ECP600JP
(Trade name, Ketchen Black International Co., Ltd., DBP oil absorption = 495cm ³ / 100g, BET specific surface area = 1270m ² / g)
(2) Polyester resin dispersant (A)
・ SOLSPERSE 20000
(Product name, manufactured by Nippon Lubrizol Co., Ltd., having an adsorbing group. Mass average molecular weight of side chain = 10500, no surfactant)
(3) Other polyester resin-based dispersants / Disperse Ayd No. 8 (may be expressed as DA-8)
(Product name, manufactured by Elementis Japan Co., Ltd., mass average molecular weight = 8000)
・ KS-860
(Trade name, manufactured by Enomoto Kasei Co., Ltd., containing 40% polymer polyesteramine salt (anionic surfactant), weight average molecular weight of side chain: 7000 or less)

(Examples 1-5)
Carbon black and the polyester resin dispersant (A) shown in Table 1 were used in the amounts shown in Table 1, and the following raw materials were premixed therein.
Polyether polyol 100 parts by mass (Actol EP-550N, trade name, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd., viscosity 530 mPa · s (25 ° C.), OH value 54 ± 2 mg KOH / g)
-1 part by mass of foam stabilizer (SRX274C, trade name, Toray Dow Corning, silicone foam stabilizer manufactured by Silicone Co., Ltd.)
・ Catalyst 0.1 parts by mass (TOYOCAT-ET, trade name, tertiary amine catalyst manufactured by Tosoh Corporation)
・ Catalyst 0.5 part by mass (TOYOCAT-L33, trade name, tertiary amine catalyst manufactured by Tosoh Corporation)
・ 2.0 parts by mass of foaming agent (water)

  Furthermore, isocyanate (Cosmonate TM-20, trade name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., modified MDI, NCO% = 44.5) was added to this premixed product at 25 ° C. so that the NCO index was 90. Mixing and stirring were performed to prepare a polyurethane raw material.

Further, a metal cored bar having a diameter of 5 mm was disposed in a cavity of a cylindrical mold having a cylindrical cavity having an inner diameter of 15 mm so that the center line of the cavity coincided with the center line of the cored bar. The polyurethane raw material filling rate was adjusted and injected so that the density of the formed polyurethane sponge layer was 0.10 g / cm ³ . Next, the cylindrical mold was foam-cured by heating in an oven at 60 ° C. for 30 minutes. Thereafter, the mold was removed to obtain a toner supply roller. The cell aperture ratio, electrical resistance, and hardness of the surface of the toner supply roller obtained in each example were measured by the above methods. Further, the toner supply roller obtained in each example was incorporated in the cartridge as described above, and the above-described image evaluation was performed. The results are shown in Table 1.

(Comparative Example 1)
A toner supply roller was obtained in the same manner as in Example 2 except that carbon black was not used, and the toner supply roller obtained in the same manner as in the above example was evaluated. The results are shown in Table 2.

(Comparative Example 2)
A toner supply roller was obtained in the same manner as in Example 2 except that another polyester resin dispersant DA-8 (Disperse Ayd No. 8) was used instead of the polyester resin dispersant (A). The toner supply roller obtained in the same manner was evaluated. The results are shown in Table 2.

(Comparative Example 3)
A toner supply roller was obtained in the same manner as in Example 2 except that another polyester resin dispersant KS-860 was used instead of the polyester resin dispersant (A), and the toner obtained in the same manner as in the above example. The supply roller was evaluated. The results are shown in Table 2.

(Comparative Example 4)
A toner supply roller was obtained in the same manner as in Example 5 except that the polyester resin dispersant (A) was not used, and the toner supply roller obtained in the same manner as in the above example was evaluated. The results are shown in Table 2.

(Comparative Example 5)
A toner supply roller was obtained in the same manner as in Example 2 except that the polyester dispersant (A) was not used, and the toner supply roller obtained in the same manner as in the above example was evaluated. The results are shown in Table 2.

  As shown in Table 1, it can be seen that each of the example products has low electrical resistance because it contains carbon black and the polyester resin dispersant (A). Further, since the polyester resin dispersant (A) composed of an adsorbing group and a side chain having a weight average molecular weight of 9000 or more and 50,000 or less is mixed, not only the surface cell opening property is excellent, but also the hardness of the toner supply roller is high. Since it is not hard, the image is good.

  On the other hand, as shown in Table 2, the comparative example products have insufficient surface cell opening (Comparative Example 2), high electrical resistance (Comparative Example 1), and toner supply rollers. However, there were some which could not be molded (Comparative Examples 3-5). In addition, when the surface cell opening property is insufficient (Comparative Example 2), the density unevenness of the image occurs, and when the electrical resistance is high (Comparative Example 1), the density unevenness or the density of the image is reduced. There has occurred.

FIG. 3 is a perspective view illustrating a schematic configuration of a toner supply roller of the present invention. It is a simplified diagram showing a method for measuring the hardness of the toner supply roller in the present invention.

Explanation of symbols

1 Toner supply roller 2 Core metal 3 Polyurethane sponge layer 4 Core metal support

Claims (6)

  In the toner supply roller having a cored bar and a polyurethane sponge layer formed on the outer periphery of the cored bar, the polyurethane sponge layer includes a polyol component, an isocyanate component, an adsorbing group, and a side chain having a mass average molecular weight of 9000 to 50000. A toner supply roller obtained by foaming and curing a polyurethane raw material containing a polyester resin dispersant (A) and carbon black.   The polyester-based dispersant (A) is contained in the polyurethane raw material in an amount of 0.5% by mass or more and 10.0% by mass or less based on the total polyol component mass of the polyurethane raw material. Toner supply roller. Said carbon black is a following carbon black DBP oil absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g, the polyurethane raw material, the polyurethane raw materials of the polyol component to the total mass to 1.0% by mass or more 25.0 mass The toner supply roller according to claim 1, wherein the toner supply roller is contained in an amount of not more than%.   4. The toner supply roller according to claim 1, wherein a cell opening ratio of the surface of the polyurethane sponge layer is 20% or more and 90% or less. 5. 2. An electrical resistance value measured by applying a voltage of 200 V in an atmosphere of a temperature of 22 ° C. and a relative humidity of 55% is 1 × 10 ⁵ Ω or more and less than 1 × 10 ⁸ Ω. The toner supply roller according to any one of 4.   6. The toner supply roller according to claim 1, wherein the roller hardness is 0.981 N / mm or more and 2.94 N / mm or less.

Images