JP5238335B2 - Toner supply roller and manufacturing method thereof - 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, and a facsimile, and a manufacturing method thereof.

  Conventionally, in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, and 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. Such a developing device has a built-in toner supply roller for supplying toner (developer) to a developing roller that applies toner to the image carrier and visualizes the electrostatic latent image.

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

  When the image forming apparatus is left in a low-temperature and low-humidity environment for a long period of time, the toner is charged up, and the amount of toner applied to the image carrier by the developing roller cannot be controlled by the developer amount regulating blade alone. In some cases, image defects such as these occur. In order to solve this problem, it is considered effective to reduce the resistance (conductivity) of the toner supply roller.

  As a conductive roller having such a low resistance polyurethane foam layer, one using an ionic conductive agent is known (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 resistance of the polyurethane foam layer is reduced using an ionic conductive agent, the electrical resistance value changes greatly due to environmental changes such as high temperature and high humidity and low temperature and low humidity. It is difficult to achieve high conductivity.

  As a method for forming a low-resistance polyurethane foam layer having a small environmental dependency, a method of forming a polyurethane foam layer using a polyurethane raw material previously containing conductive carbon black is known.

In general, the toner supply roller is manufactured by die molding so as to open cells on the roller surface. By the way, as the amount of conductive carbon black in the polyurethane raw material liquid increases, its viscosity increases. For this reason, when forming a polyurethane foam layer by mold molding, the cells on the roller surface often do not bubble smoothly, and if the cells on the roller surface do not open sufficiently or in extreme cases, the roller may not be molded. there were. 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 has been difficult to form a conductive polyurethane foam layer having a low resistance (for example, a volume resistivity value of 10 ⁷ Ω · cm or less) and having sufficiently open cells on the surface.

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

However, various dispersants have been studied as dispersants to be blended in inks and paints, but there are many unclear parts about polyurethane raw materials for forming a polyurethane foam layer containing carbon black. Even if an alkyd resin-based dispersant or a polyester resin-based dispersant is used, a sufficient viscosity increase inhibiting effect may not be obtained depending on the blending amount of conductive carbon black. That is, the opening of the cell on the surface of the polyurethane foam layer of the toner supply roller may be insufficient or may not be opened at all. In addition, a necessary expansion ratio may not be obtained, and the toner supply roller may become high in hardness. When the toner supply roller has a high hardness, the toner sandwiched between the developing roller and the abutting developing roller may be loaded and deteriorate.
Japanese Patent No. 3881719 JP 11-292948 A JP 2003-98786 A

  Therefore, an object of the present invention is to provide a polyurethane sponge layer having an improved surface cell opening property in which the increase in viscosity of raw materials is suppressed, the electrical resistance is low, and the environment dependency thereof is small although carbon black is added. Another object of the present invention is to provide a low-hardness toner supply roller.

  The present inventors diligently studied to solve the above-described problems, and finally reached the present invention.

That is, the present invention is a toner supply roller having a polyurethane sponge layer formed on the outer periphery of a core metal, wherein the polyurethane sponge layer is formed by foaming and curing a polyurethane raw material containing at least the following components. And a toner supply roller characterized in that the cell opening ratio of the surface of the polyurethane sponge layer is 20% or more and 90% or less.
(A) Dispersant mainly composed of ethoxylate type nonionic surfactant: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(B) Dispersant mainly composed of an acrylic resin: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(C) DBP absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g or less is carbon black: 15 parts by mass 1 part by mass or more based on the total polyol component 100 parts by weight of the polyurethane raw material.

In the present invention, the volumetric resistivity value (23 ° C./55 RH%) of the polyurethane sponge constituting the polyurethane sponge layer is 10 ^5.0 Ω · cm or more and 10 ^8.5 Ω · cm or less. Laura.

  Furthermore, the present invention is the above toner supply roller, wherein the roller hardness is 0.981 N / mm or more and 2.94 N / mm or less.

Furthermore, the present invention is a method for producing a toner supply roller having a polyurethane sponge layer formed on the outer periphery of a core metal, wherein the polyurethane raw material of the polyurethane sponge layer contains at least the following components, and at least the following steps: A method of manufacturing a toner supply roller.
(A) Dispersant mainly composed of ethoxylate type nonionic surfactant: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(B) Dispersant mainly composed of an acrylic resin: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(C) DBP absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g or less of carbon black: 15 parts by mass 1 part by mass or more based on the total polyol component 100 parts by weight of the polyurethane raw material.
(Step 1) A step of premixing the dispersant (A) with the polyol component and the carbon black (C).
(Step 2) A step of further adding the dispersant (B) to the premix obtained in Step 1 and mixing and stirring.
(Step 3) Total mixing and stirring step in which an isocyanate component is added to the premix polyol obtained in Step 2 and mixed and stirred to obtain a polyurethane raw material.
(Step 4) A step of injecting the polyurethane raw material obtained in Step 3 into a mold and foam-curing it.

  In the toner supply roller of the present invention, the conductive material is carbon black, the polyurethane raw material has a sufficiently low viscosity, good electrical resistance, a preferable surface cell opening, and low hardness. There are provided. Further, the toner supply roller can be efficiently manufactured by the manufacturing method of the present invention.

  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 in the toner supply roller of the present invention comprises a dispersant (A) mainly composed of a polyol component, an isocyanate component, an ethoxylate type nonionic surfactant, a dispersant (B) mainly composed of an acrylic resin, and It is obtained by foaming and curing a polyurethane raw material containing carbon black (C).

  The present invention will be described below.

(Toner supply roller)
A perspective view of an example of the toner supply roller of the present invention is shown in FIG.

  The toner supply roller 1 of the present invention has a cylindrical cored bar 2 and a polyurethane sponge layer 3 formed on the outer periphery of the cored bar 2. Note that the both ends of the cored bar 2 of the toner supply roller 1 are portions attached to the main body of the image forming apparatus, and thus the polyurethane sponge layer 3 is not provided.

  The polyurethane sponge layer 3 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, such a polyurethane sponge layer can be easily formed when the cell opening ratio is 90% or less. 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.

(Core metal)
As the metal core 2, a conventional metal core for a toner supply roller can be used without any trouble. 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 foam-curing a polyurethane raw material containing at least the following components together with a polyol component, an isocyanate component, a urethanization catalyst, a foaming agent and the like used in the production of the polyurethane sponge.
(A) A dispersant mainly composed of an ethoxylate type nonionic surfactant.
(B) A dispersant mainly composed of an acrylic resin.
(C) Carbon black.

  In the present invention, the dispersant (A) mainly composed of an ethoxylate type nonionic surfactant, the dispersant (B) mainly composed of an acrylic resin, and carbon black, which are major features, will be described. In the following, unless otherwise specified, the dispersant (A) mainly composed of an ethoxylate type nonionic surfactant and the dispersant (B) mainly composed of an acrylic resin are respectively referred to as “dispersant (A)”. , “Dispersant (B)”.

  These three components are essential in the present invention, and by combining these three components, an increase in the viscosity of the polyurethane raw material can be suppressed, the electrical resistance value is low, and the electrical resistance value depends on the environment. Is small, and the effect of improving the cell opening property of the surface can be obtained.

  Carbon black having a high DBP absorption amount as used in the present invention often has a complicated surface structure. Therefore, when carbon black is mixed and stirred with the polyol component, bubbles may cling to the surface of the carbon black, the dispersant (B) is difficult to coordinate, and the effect of reducing the viscosity of the raw material cannot be fully exhibited. Sometimes. In order to obtain this effect sufficiently, it is necessary to eliminate bubbles on the surface of the carbon black and to facilitate coordination of the dispersant (B).

  The dispersant (A) used together with the dispersant (B) in the present invention has a property of easily removing bubbles on the surface of the carbon black. That is, when these are used together with carbon black, the carbon black and the dispersant (B) are easily coordinated. In order to exhibit this effect more, it is preferable to first remove bubbles on the surface of the carbon black with the dispersant (A), then add the dispersant (B), and mix and stir. Thereby, the viscosity of the polyurethane raw material is reduced, the density of the urethane sponge layer 3 suitable as a toner supply roller is obtained, and the urethane sponge layer 3 having a cell opening ratio of 20% to 90% can be formed.

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

(Dispersant (A) mainly composed of ethoxylate type nonionic surfactant)
In this invention, a dispersing agent (A) is 1 mass part or more and 10 mass parts or less with respect to 100 mass parts of total polyol components in a polyurethane raw material, Preferably it is 1 mass part or more and 5 mass parts or less. When the dispersant (A) is contained in an amount of 1 part by mass or more with respect to 100 parts by mass of the total polyol component in 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. If the dispersant (A) is 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material, the dispersant (A) may exude and contaminate the developing roller in contact with the toner supply roller. Absent.

  Examples of the dispersant (A) that can be used in the present invention include NUOSPERSE FA196 (trade name), NUOSPERSE 700 (trade name) (both manufactured by Elementis Japan Co., Ltd.) and the like. .

(Dispersant mainly composed of acrylic resin (B))
In the present invention, the dispersant (B) is used in an amount of 1 part by mass to 10 parts by mass, preferably 1 part by mass to 5 parts by mass with respect to 100 parts by mass of the total polyol component in the polyurethane raw material. When the dispersant (B) is contained in an amount of 1 part by mass or more with respect to 100 parts by mass of the total polyol component in 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. If the dispersant (B) is 10 parts by mass or less with respect to 100 parts by mass of the polyol component in the polyurethane raw material, the dispersant (B) may exude and contaminate the developing roller in contact with the toner supply roller. Absent. The increase in viscosity is thought to be due to polymerization or apparent polymerization. On the other hand, it is considered that the dispersant (B) coordinates to the polymer, prevents the polymers from aggregating, suppresses the apparent polymerization, and improves the fluidity.

  Examples of the dispersant (B) that can be used in the present invention include NUOSPERSE FX9085 (trade name), NUOSPERSE FX9086 (trade name) (both manufactured by Elementis Japan Co., Ltd.) and the like. .

(Carbon black)
Carbon black used in the present invention are those DBP absorption 300 cm ^3/100 g or more 550cm of ^3/100 g or less. When carbon black having a DBP absorption in this range is used, the resistance of the polyurethane sponge layer can be reduced. If the DBP absorption of carbon black is less than 300 cm ^3/100 g, because conductivity is difficult to obtain, because it can not reduce the resistance of the polyurethane sponge layer without the addition of large amounts of carbon black, the hardness of the polyurethane sponge layer There is a risk of becoming too high. Further, DBP absorption amount of 550 cm ^3/100 g than the carbon black is extremely high structure, an uneven surface is large structures. As the DBP absorption amount of carbon black increases, the polyurethane raw material containing carbon black is vigorously thickened, and the viscosity can be easily formed even when the dispersant (A) and the dispersant (B) used in the present invention are added. It becomes difficult to reduce it to a minimum. 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.

  Moreover, in this invention, the addition amount of carbon black is 1 to 15 mass parts with respect to 100 mass parts of total polyol components in a polyurethane raw material, and it is preferable to set it as 1 to 5 mass parts. . When 1 mass part or more of carbon black is contained with respect to the polyol component total mass in the polyurethane raw material, the resistance can be sufficiently lowered. Further, when 15 parts by mass or less of carbon black is included with respect to the total mass of the polyol component in the polyurethane raw material, the hardness of the toner supply roller is sufficiently low and the toner is hardly deteriorated.

  Examples of the carbon black that can be used in the present invention include the following as commercially available products. Ketjen Black ECP (trade name), Ketjen Black ECP600JD (trade name) (both made by Ketjen Black International Co., Ltd.), etc.

The toner supply roller of the present invention contains 1 part by mass or more and 15 parts by mass or less of carbon black having a DBP absorption in the above range with respect to 100 parts by mass of the total polyol component in the polyurethane raw material. Therefore, in the toner supply roller of the present invention, the volume specific resistance value of the polyurethane sponge constituting the polyurethane sponge layer is 10 ^5.0 Ω · cm or more and 10 ^8.5 Ω · cm or less in a 23 ° C./55 RH% environment. The volume specific resistance value of the polyurethane sponge constituting the polyurethane sponge layer of the toner supply roller coincides with the “electric resistance value of the toner supply roller”, and unless otherwise specified, the “electric resistance value of the toner supply roller”. Alternatively, it is called “electric resistance value”. This electric resistance value is more preferably 5 × 10 ⁵ Ω · cm or more and 6 × 10 ⁷ Ω · cm or less. When the electrical resistance value is less than 1 × 10 ^8.5 Ω · cm, image defects such as low density due to charge-up of the toner do not occur even when left for a long time in a low temperature and low humidity environment. This is presumably because when the electrical resistance value is less than 1 × 10 ^8.5 Ω · cm, the electrical resistance value is small, so that charge-up is prevented and the toner amount can be controlled only by the layer regulating blade. The reason why the electric resistance value is set to 1 × 10 ⁵ Ω · cm or more is that when the resistance is further reduced, the number of added parts of carbon black increases, which may make molding difficult.

  In the present invention, the roller hardness is measured as described later. And in this invention, it is preferable that this roller hardness exists in the range of 0.981 N / mm or more and 2.94 N / mm or less. This is the density of the urethane sponge layer 3 suitable as a toner supply roller due to the viscosity reduction of the raw material achieved by using the dispersant (A) and the dispersant (B) at the amount of carbon black described above. Therefore, it is realized as a suitable roller hardness.

  The toner supply roller of the present invention preferably has a roller hardness of 0.981 N / mm (100 gf / mm) or more and 2.94 N / mm (300 gf / mm) or less. Furthermore, it is more preferable in it being 1.47 N / mm (150 gf / mm) or more and 2.45 N / mm (250 gf / mm) or less. When the roller hardness is 0.981 N / mm (100 gf / mm) or more, the toner remaining on the surface of the developing roller can be efficiently scraped off. Further, when the roller hardness is 2.94 N / mm (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 blending ratio of polyisocyanate, the amount of foaming agent used, and the filling rate in the mold when using a mold.

  In the present invention, the base polymer is polyurethane, and the raw material thereof will be described.

(Polyol component)
If the polyol component used by this invention is used for manufacture of the elastic roller which uses a urethane foam as an elastic layer, there will be no restriction | limiting in particular, It can use. Specifically, the following can be mentioned, for example. Polyether polyol, polytetramethylene ether glycol, THF-alkylene oxide copolymer polyol, polyester polyol, acrylic polyol, polyolefin polyol, partially saponified product of ethylene-vinyl acetate copolymer, phosphate polyol, halogen-containing polyol and the like.

  In this, the polyether polyol whose mass mean molecular weight Mw is 2500-7500 is preferable. When the polyether polyol has a Mw of 7500 or less, the viscosity is 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. In addition, when the MW of the polyether polyol is 2500 or more, the formed polyurethane sponge layer has a sufficiently low hardness, which is preferable. The Mw 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 number of functional groups is 4 or less, the hardness of the toner supply roller tends to be low.

(Isocyanate component)
In the present invention, the isocyanate component is not particularly limited. For example, not only general-purpose toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude-MDI (polymeric MDI), and modified MDI, but also special isocyanates can be used. Examples of the special isocyanate include the following. 1,5-naphthalene diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, transcyclohexane-1,4-diisocyanate, xylylene diisocyanate (XDI), hydrogenated-XDI, hydrogenated-MDI, lysine diisocyanate , Triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, tetramethylxylene diisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate, 1,8-diisocyanato-4-isocyanatomethyloctane, 1, 3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene dii Such as cyanate.

  As an isocyanate component, it is preferable that the total amount of TDI, MDI, or its derivative contained in 100 mass parts of isocyanate components is contained 20 mass parts or more. When the total amount is 20 parts by mass or more, the isocyanate component has a suitable viscosity and is easily mixed with the polyol component, and the polyurethane foam to be produced also has a uniform cell diameter and good air permeability. 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 is used as necessary. There is no restriction | limiting in particular in the kind of catalyst, You may select and use a conventionally well-known thing suitably. Examples of amine-based catalysts include the following. 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 and the like. Moreover, as an organometallic catalyst, the following can be used, for example. Tin octylate, tin oleate, dibutyltin dilaurate, dibutyltin diacetate, tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetrakis (2-ethylhexyloxy) titanium and the like. Furthermore, acid salt catalysts (carboxylates, formates, octylates, borates, etc.) with reduced initial activity of these amine-based catalysts and organometallic catalysts can also be used. One type of catalyst may be used, or two or more types may be used in combination.

(Foaming agent)
The foaming agent used in the present invention is not particularly limited, and various foaming agents can be used. In particular, water is suitable as a blowing agent because it reacts with polyisocyanate to generate carbon dioxide gas and does not cause air pollution.

(Foam stabilizer)
In the present invention, a foam stabilizer can be used as necessary. Examples of the foam stabilizer include water-soluble polyether siloxane obtained from polydimethylsiloxane and an ethylene oxide / propylene oxide copolymer, a mixture of a sodium salt of sulfonated ricinoleic acid and a polysiloxane / polyoxyalkylene copolymer, and the like. Among these foam stabilizers, water-soluble polyether siloxane obtained from polydimethylsiloxane and ethylene oxide / propylene oxide copolymer is preferable.

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

  The toner supply roller of the present invention can be manufactured by the following method.

(Premix polyol preparation)
In the method for producing a toner supply roller of the present invention, the premix polyol of the polyurethane raw material of the polyurethane sponge layer is prepared as follows. After the step of premixing the dispersant (A) with the polyol component and carbon black (C) (step 1), the step of adding the dispersant (B) to the premix obtained in step 1 and mixing and stirring (step 2) ) To obtain a premix polyol.

(Formation of polyurethane sponge layer)
The formation of the polyurethane sponge layer 2 is preferably carried out using a molding die containing a cored bar, and the inner surface of the molding die is preferably 85 degrees or more in terms of ethylene glycol contact angle. This is because when the inner surface has an ethylene glycol contact angle of 85 degrees or more, the polyurethane raw material is incompatible with the polyurethane raw material or the surface tension action of the surface constituting at least the cavity inner surface of the mold. The absence part of occurs. 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, the skin layer on the surface of the formed polyurethane sponge layer is opened, and the cells are opened to the outside.

  If the contact angle of ethylene glycol on the inner surface of the mold is smaller than 85 degrees, sufficient incompatibility or surface tension effect 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. Further, when the contact angle of ethylene glycol on the inner surface of the mold is smaller than 85 °, the adhesion between the polyurethane sponge layer 3 and the inner surface of the mold becomes strong, and the toner supplied by foaming and curing in the mold is supplied. It may be difficult to release the roller 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. For example, a mold inner surface treatment such as a mold release agent containing a conventionally known silicone component or fluororesin processing is performed. The applied mold can be used.

  The polyurethane raw material prepared in the total mixing and stirring step (step 3) in which the isocyanate component is added to the premix polyol obtained in step 2 and mixed and stirred to obtain a polyurethane raw material is injected into the mold and foam-cured. A polyurethane sponge layer is formed (step 4).

  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 10 ° C to 70 ° C, preferably 20 ° C to 50 ° C, and the mixing time is usually The time is 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.

  In the toner supply roller of the present invention, an adhesive layer may be provided between the core metal 2 and the polyurethane sponge layer 3 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.

  There is no particular limitation on the method for joining the core metal and the polyurethane sponge layer. For example, a cored bar is disposed in advance in 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, and this is a cored bar. For example, a method of adhering to can be used.

  According to the present invention, it is possible to provide a low-hardness toner supply roller having a polyurethane sponge layer having a small cell resistance on the surface, in which the electrical resistance is less dependent on the environment and the electrical resistance is reduced. It becomes.

  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 opening degree, electric resistance, and roller hardness of the surface of the toner supply roller prepared in Examples and Comparative Examples were measured by the following methods.

(Cell opening degree on the surface of the toner supply roller)
The cell opening degree 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 foam layer of the toner supply roller, and is calculated from a photo image of the roller surface such as an optical microscope or an electron microscope. did.

(Electric resistance of polyurethane foam layer)
A separately prepared sheet having a thickness of 2 mm is placed in a 23 ° C./55% RH (N / N) environment for 24 hours, and then in that environment, the applied voltage is 500 V and the volume is determined by the method described in JIS K6911. The resistivity was measured and used as the electrical resistance value of the polyurethane foam layer. Note that a high resistivity meter “HIRESTA” (trade name) manufactured by Dia Instruments Co., Ltd. was used for measurement of the volume resistivity.

(Roller hardness of toner supply roller)
The load-deformation curve when the toner supply roller is pressed at a total of 12 locations in the axial direction and 4 locations in the circumferential direction (every 90 degrees) of the toner supply rollers produced in Examples and Comparative Examples. The measurement was performed as shown in FIG. In FIG. 2, the toner supply roller 1 is supported at both ends of the core metal 2 by a core metal support 4 of a compression tester (not shown). In addition, a jig 5 having a plate-like pressing surface with a length of 50 mm (toner supply roller longitudinal direction) × width 10 mm × thickness 10 mm was attached to the compression tester. Next, using a compression tester, the jig 5 was moved at a speed of 10 mm / min in an environment of a temperature of 23 ° C. and a relative humidity of 53%, and the toner supply roller was pressed and deformed by 2 mm. From the load-deformation amount curve obtained at this time, the load S1 (N) applied to the surface of the toner supply roller when the deformation amount Δ = 1 mm is obtained by pressing, and the hardness (N / mm) is obtained by the following equation. Asked. The average value of the measured values at 12 locations was defined as the roller hardness of the toner supply roller. The larger this value is, the harder the polyurethane foam layer 3 is.
Hardness (N / mm) = S1 / Δ

(Image evaluation)
The toner supply roller produced in Examples and Comparative Examples 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 mounted on the laser beam printer and left to stand in an environment of 10 ° C./15% RH (L / L) for 1 week, and then in an environment of 10 ° C./15% RH (L / L), 50 sheets were printed. Density unevenness and shading of the image of the obtained print were visually observed, and image evaluation was performed based on the following criteria from the obtained results.
○: There is no problem in density unevenness and shading, and the image is good.
Δ: Slight density unevenness and shading are observed, but use is not hindered.
X: Density unevenness and shading are recognized and defective.

The following materials were used as raw materials for forming the polyurethane sponge layers of the toner supply rollers of Examples and Comparative Examples.
(1) Polyol component / polyether polyol “Actol EP-550N” (trade name, manufactured by Mitsui Chemicals Polyurethanes, viscosity 530 mPa · s (25 ° C.), OH value 54 ± 2 mg KOH / g).
(2) Isocyanate component / isocyanate “Cosmonate TM-20” (trade name, manufactured by Mitsui Chemicals Polyurethanes, modified MDI, NCO% = 44.5).
(3) Carbon black · ECP: carbon black "EPC" (trade name, Ketchen Black International Co., Ltd., DBP absorption amount of 360cm ³ / 100g, BET specific surface area of 800m ² / g).
· ECP600JD: carbon black "EPC600JD" (trade name, Ketchen Black International Co., Ltd., DBP absorption amount of 495cm ³ / 100g, BET specific surface area of 1270m ² / g).
(4) Dispersant / Dispersant (A): Dispersant “NUOLSPERSE FA196” mainly composed of ethoxylate type nonionic surfactant (trade name, manufactured by Elementis Japan Co., Ltd.).
-Dispersant (B): Dispersant “NUOLSPERSE FX9086” mainly composed of acrylic resin (trade name, manufactured by Elementis Japan Co., Ltd.).
(5) Foam stabilizer / silicone-based foam stabilizer “SRX274C” (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.).
(6) Catalyst / catalyst ET: Urethane catalyst “TOYOCAT-ET” (trade name, manufactured by Tosoh Corporation).
Catalyst L: Urethane catalyst “TOYOCAT-L33” (trade name, manufactured by Tosoh Corporation).

Example 1
(Premix polyol preparation)
Polyol component 100 parts by mass, foam stabilizer 1 part by mass, catalyst ET 0.1 part by mass, catalyst L 0.5 part by mass and blowing agent (water) 2.0 part by mass, carbon black ECP600JD 3 parts by mass and dispersant (A) 1 part by mass was added and mixed to obtain a premix. For the mixing, an Eirich mixer R02 type equipped with an attached pin type rotor was used. The rotor rotation speed was 1500 rpm, the pan rotation speed was 40 rpm, and the dispersion time was 5 minutes.
Next, 3 parts by mass of the dispersant (B) was added to this premix and dispersed for 10 minutes at a rotor rotation speed of 3000 rpm and a bread rotation speed of 40 rpm to obtain a premix polyol.

(Preparation of polyurethane raw materials)
An isocyanate component was added to the premix polyol obtained above at 25 ° C. so that the isocyanate index was 90, and the mixture was stirred and mixed to obtain a polyurethane raw material.

(Manufacture of toner supply roller)
An iron core metal having a diameter of 5 mm was placed in a cavity of a cylindrical mold having a cavity on a cylinder having an inner diameter of 15 mm so that the center line of the cavity coincided with the center line. The cavity surface of this mold is coated with a fluorine resin PFA, and the contact angle of ethylene glycol is 85 degrees or more. The polyurethane raw material prepared above was injected into the cavity so that the density of the formed polyurethane sponge layer was 0.10 g / cm ³ . Next, the cylindrical mold was heated for 30 minutes in an oven at 60 ° C. to be foam-cured. Thereafter, the mold was removed to obtain a toner supply roller.

  The cell opening property, electric resistance, and roller hardness of the surface of the obtained toner supply roller were measured according to the above. The obtained toner supply roller was subjected to image evaluation as described above. The obtained results are shown in Table 1.

Examples 2-5
A toner supply roller was obtained in the same manner as in Example 1 except that the carbon black, the dispersant (A) and the dispersant (B) were as shown in Table 1, and various measurements and image evaluations were performed in the same manner as in Example 1. went. The results are shown in Table 1.

Comparative Example 1
A toner supply roller was obtained in the same manner as in Example 1 except that carbon black was not used, a toner supply roller obtained in the same manner as in the previous example was obtained, and various measurements and image evaluations were performed in the same manner as in Example 1. Went to. The results are shown in Table 1.

Comparative Example 2
In Example 1, carbon black was first dispersed without using the dispersant (A), then a premix polyol was prepared using 10 parts by mass of the dispersant (B), and toner supply was performed in the same manner as in Example 1. A roller was obtained, and image evaluation of various measurements was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3
In Example 1, carbon black was dispersed using 10 parts by mass of the dispersant (A), and then dispersed without using the dispersant (B) and further dispersed for 10 minutes at a rotor rotational speed of 3000 rpm and a pan rotational speed of 40 rpm. A mixed polyol was obtained. Thereafter, an isocyanate component was added to prepare a polyurethane raw material, and an attempt was made to prepare a toner supply roller in the same manner as in Example 1. However, the thickening of the polyurethane raw material became so severe that the polyurethane raw material entered the cavity of the cylindrical mold. It was impossible to inject.

Comparative Example 4
An attempt was made to prepare a toner supply roller in the same manner as in Example 1 using the carbon black, the dispersant (A) and the dispersant (B) shown in Table 1 in the amounts shown in Table 1, but the viscosity of the polyurethane raw material was increased. However, it was impossible to inject into the cavity of the cylindrical mold.

Comparative Example 5
A toner supply roller was obtained in the same manner as in Example 1 except that carbon black, dispersant (A) and dispersant (B) were changed to the amounts shown in Table 1, and various measurements and image evaluations were performed in the same manner as in Example 1. went. The results are shown in Table 1.

  Since the toner supply rollers of Examples 1 to 5 all contain carbon black within a predetermined range, the electric resistance is sufficiently low and the roller hardness is not high. Further, since the dispersant (A) mainly composed of an ethoxylate type nonionic surfactant and the dispersant (B) mainly composed of an acrylic resin are contained, the cells on the surface are sufficiently opened. Not only is the image good.

  On the other hand, in Comparative Examples 1 to 5, the cell opening degree on the surface is insufficient (Comparative Example 2), the electric resistance is high (Comparative Examples 1 and 5), or the toner supply roller cannot be molded (Comparative Examples 3 and 4). Both were inappropriate. Further, when the surface cell opening degree is insufficient, the density unevenness of the image occurs (Comparative Example 2), and when the electrical resistance is high, the density unevenness and the density of the image become thin (Comparative Example 1, 5).

FIG. 3 is a perspective view illustrating a schematic configuration of a toner supply roller of the present invention. It is a figure for demonstrating the measuring method of the roller hardness of the toner supply roller of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toner supply roller 2 Core metal 3 Polyurethane sponge layer 4 Core metal support body 5 Pressing jig

Claims (4)

A toner supply roller having a polyurethane sponge layer formed on the outer periphery of a core metal,
The polyurethane sponge layer is formed by foaming and curing a polyurethane raw material containing at least the following components, and
The cell open area ratio of the surface of the polyurethane sponge layer is 20% or more and 90% or less.
A toner supply roller.
(A) Dispersant mainly composed of ethoxylate type nonionic surfactant: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(B) Dispersant mainly composed of an acrylic resin: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(C) DBP absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g or less is carbon black: 15 parts by mass 1 part by mass or more based on the total polyol component 100 parts by weight of the polyurethane raw material. 2. The toner supply roller according to claim 1, wherein a volume specific resistance value (23 ° C./55 RH%) of the polyurethane sponge constituting the polyurethane sponge layer is 10 ^5.0 Ω · cm or more and 10 ^8.5 Ω · cm or less. .   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. A method for producing a toner supply roller having a polyurethane sponge layer formed on the outer periphery of a core metal,
The polyurethane raw material of the polyurethane sponge layer contains at least the following components, and
A method for producing a toner supply roller, comprising at least the following steps.
(A) Dispersant mainly composed of ethoxylate type nonionic surfactant: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(B) Dispersant mainly composed of an acrylic resin: 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total polyol component in the polyurethane raw material.
(C) DBP absorption of 300 cm ^3/100 g or more 550 cm ^3/100 g or less of carbon black: 15 parts by mass 1 part by mass or more based on the total polyol component 100 parts by weight of the polyurethane raw material.
(Step 1) A step of premixing the dispersant (A) with the polyol component and the carbon black (C).
(Step 2) A step of further adding the dispersant (B) to the premix obtained in Step 1 and mixing and stirring.
(Step 3) Total mixing and stirring step in which an isocyanate component is added to the premix polyol obtained in Step 2 and mixed and stirred to obtain a polyurethane raw material.
(Step 4) A step of injecting the polyurethane raw material obtained in Step 3 into a mold and foam-curing it.

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