JP2008015008A - Method for manufacturing toner supply roller and toner supply roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner supply roller that has low hardness as a roller and little oozing of an unreacted polyol component on the roller surface. <P>SOLUTION: The roller is manufactured by injecting a urethane foam source material into a roller form molding die incorporating a core metal, foaming and curing the source material in the die to form an urethane foam layer on the perimeter of the core metal, coating the surface of the urethane foamed layer with an isocyanate compound by impregnation, treating the impregnated isocyanate compound by blowing hot air at a temperature of the melting point or higher of the compound, and then making the compound react with the urethane foam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner supply roller manufacturing method and a toner supply roller.

  In general, a developing unit in an electrophotographic image forming apparatus (hereinafter, also referred to as an electrophotographic apparatus) such as a copying machine or a printer includes an image forming body that holds an electrostatic latent image, and the image forming body. There is a developing roller that visualizes an electrostatic latent image as a toner image with toner held in contact with the surface. The developing roller is supplied with toner by a toner supply roller. That is, the toner is transported from the toner storage portion to the image forming body on which the electrostatic latent image is formed via the toner supply roller and the developing roller, and a toner image is formed in the developing portion.

  In order to perform good image formation in this developing mechanism, it is necessary that a thin layer of toner is uniformly formed and supported on the surface of the developing roller without unevenness. In addition to the toner holding performance of the developing roller itself, the toner The performance of the supply roller, particularly the surface performance such as cell opening on the surface, is important. That is, the toner supply roller is required to have a performance of forming a toner layer having a uniform charge and thickness on the surface of the developing roller by contacting the developing roller and performing frictional charging, toner supply, and scraping. Yes.

  Various studies have been made in the past in order to obtain a toner supply roller having a cell opening with a satisfactory surface that satisfies the above requirements. For example, a toner supply roller is generally manufactured by cutting a roll material from a foam material manufactured by slab foaming or mold foaming, passing the core through it, polishing the surface, and finishing it into a roll shape. In this manufacturing method, the surface of the urethane foam is scraped off into a cylindrical shape by polishing, and the foam mesh is used as the roller surface. However, the surface may become fuzzy and the surface properties may deteriorate due to the polishing. In addition, a polishing process is necessary, and the capital investment for that is excessive, which ultimately leads to high product costs.

  On the other hand, the core metal and urethane foam are integrally molded in a mold with the final shape of the molded product, and a special mold surface is used to control the skin opening ratio of the surface, and the surface opening ratio is 20%. As described above, a method of manufacturing a urethane foam toner supply roller having a roller hardness of 350 g or less has been proposed (for example, Patent Document 1).

  In the urethane foam toner supply roller formed in this way, the polyol component does not fully react and remains, the unreacted polyol component oozes out on the roller surface, and other key parts (developing roller, image forming body, toner, etc.) ) May be contaminated and image defects may occur. In order to eliminate the unreacted polyol component, it is known that the equivalent ratio of the polyol component and the polyisocyanate component is equivalent or the polyisocyanate component is excessive (for example, Non-Patent Document 1).

However, when the ratio of the polyisocyanate component is increased, the roller hardness is increased, the load on the toner is increased, the deterioration of the toner is promoted, and this causes the image defect.
JP-A-9-274373 Yoshio Imai, “Urethane Foam”, Kobunshi Publishing Co., Ltd., May 20, 1987, p. 41-42

  Accordingly, an object of the present invention is to provide a toner supply roller that has a low hardness as a roller and hardly exudes an unreacted polyol component on the roller surface, and a method for manufacturing the same.

  The present invention achieves the object by the following.

That is, the present invention is a method for manufacturing a toner supply roller in which a urethane foam layer is provided on a core metal, and includes at least steps (1) to (4). is there.
(1) A urethane foam raw material mainly composed of a polyol component and a polyisocyanate component is injected into a roller-shaped molding die containing a core metal, foamed and cured in the mold, and urethane foam is formed on the outer periphery of the core metal. Forming a layer;
(2) A step of applying and impregnating an isocyanate compound on the surface of the urethane foam layer formed in step (1).
(3) A step of performing hot air treatment at a temperature equal to or higher than the melting point of the isocyanate compound used in step (2). (4) A step of reacting the impregnated isocyanate compound with urethane foam to form an isocyanate-modified urethane foam layer.

  The NCO index of the urethane foam raw material is preferably 60 or more and 90 or less.

  The impregnation of the isocyanate compound on the surface of the urethane foam layer in the step (2) is preferably spraying of the isocyanate compound.

  It is preferable that the application and impregnation of the isocyanate compound on the surface of the urethane foam layer in the step (2) is a roll coat of the isocyanate compound.

  According to another aspect of the present invention, there is provided a toner supply roller manufactured by the above-described toner supply roller manufacturing method.

  According to the production method of the present invention, a toner supply roller in which the unreacted polyol component hardly leaks from the surface of the urethane foam layer can be produced inexpensively and reliably. Further, the toner supply roller manufactured by the manufacturing method is a urethane foam in which only the outermost surface is rich in polyisocyanate component, and the inside of the urethane foam layer has a low hardness because the ratio of the polyol component is low. Therefore, since the entire roller has a low hardness and hardly seeps out unreacted polyol components on the surface, the toner supply roller manufactured by the manufacturing method of the present invention is extremely excellent as a toner supply roller of an electrophotographic apparatus. Have good performance.

  Details of the present invention will be described below.

  FIG. 1 is a perspective view of an example of a toner supply roller targeted by the present invention.

  In FIG. 1, reference numeral 1 denotes a toner supply roller. The toner supply roller 1 includes a cylindrical cored bar 2 and an elastic layer (urethane foam layer) 3 made of urethane foam around the cored bar 2. .

  The core metal 2 may be the same as the material used for a conventionally known roller, and can be made of, for example, iron. In the present invention, the outer diameter of the cored bar 2 is suitably in the range of 2 mm to 10 mm.

As described above, the present invention is a manufacturing method of the toner supply roller 1 in which the urethane foam layer 3 is provided on the core metal 2, and the manufacturing method includes at least the following steps.
(1) A urethane foam raw material mainly composed of a polyol component and a polyisocyanate component is injected into a roller-shaped molding die containing a core metal, foamed and cured in the mold, and urethane foam is formed on the outer periphery of the core metal. Forming a layer;
(2) A step of applying and impregnating an isocyanate compound on the surface of the urethane foam layer formed in the step (1) with an application range as an image width in the longitudinal direction centering on at least the roller central portion.
(3) A step of performing hot air treatment at a temperature equal to or higher than the melting point of the isocyanate compound used in step (2).
(4) A step of reacting the impregnated isocyanate compound with urethane foam to form an isocyanate-modified urethane foam layer.

  The urethane foam raw material used in the present invention is not limited as long as it is composed of a polyol component and a polyisocyanate component that are used for producing a conventionally known urethane foam, and any of them can be used.

  The polyol component is appropriately selected from known materials such as polyether polyols, polyester polyols, polymer polyols and the like, which are particularly used in the production of flexible urethane foams.

  As the polyisocyanate component, any polyisocyanate that is at least bifunctional can be used. For example, 2,4- and 2,6-tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), 4,4'-diphenylmethane diisocyanate (MDI), Examples thereof include carbodiimide-modified MDI, polymethylene polyphenyl polyisocyanate component (polymeric MDI), and the like. These polyisocyanates are used alone or in combination of two or more.

  In addition, the urethane foam raw material, together with the above polyol component and polyisocyanate component, includes a crosslinking agent, a foaming agent, a urethanization catalyst, a flame retardant, a filler, a conductivity imparting agent for imparting desired conductivity, an antistatic agent, etc. Are used as appropriate.

  In the production method of the present invention, first, a urethane foam raw material mainly composed of a polyol component and a polyisocyanate component is injected into a roller-shaped molding die incorporating a cored bar, and foam-cured and cured in the mold. A roller (raw material roller) having a urethane foam layer on the core is formed by forming a urethane foam layer on the outer periphery of the core.

  Here, since it is desirable for the raw material roller to be manufactured that the urethane foam layer is sufficiently flexible, it is preferable to use the polyisocyanate component in less than an equimolar amount with respect to the polyol component. Therefore, the NCO index (100 when there is an equimolar amount of isocyanate with respect to active hydrogen) is in the range of 60 to 90, preferably in the range of 60 to 80, indicating the ratio of isocyanate to active hydrogen that reacts with isocyanate. Is desirable. If the amount of the polyisocyanate component is too small (that is, if the NCO index is too small), the amount of unreacted polyol component increases, the amount of exudation increases, and the toner and developing roller are contaminated, causing image defects. This is not preferable. On the other hand, if the ratio of the polyisocyanate component is too high, the roller hardness increases, a load is applied to the toner, and the deterioration of the toner is promoted.

  The formation of the urethane foam layer in the mold is appropriately determined depending on the composition of the urethane foam raw material, the amount of catalyst used, and the like. After completion of the foam curing, the resin is taken out of the mold and subjected to an additional curing treatment as necessary, and then subjected to the next step (2).

  As the urethane foam layer around the core metal, the length required for the image forming apparatus used in the longitudinal direction of the core metal is usually 100 mm to 300 mm, and the thickness is usually 1 mm to 20 mm, preferably Is from 2 mm to 10 mm. And here, the hardness of the urethane foam layer is desirably as low as possible, and when the roller hardness after the surface treatment with the isocyanate compound to be formed later is measured by the method described later, the hardness is in the range of 40 g to 300 g. Is preferred.

  In the step (2), an isocyanate compound is applied from the surface of the urethane foam layer of the raw material roller manufactured as described above, and the urethane foam layer is impregnated with the isocyanate compound. The application range here is preferably the image width in the longitudinal direction centered at least on the center of the roller.

  As the isocyanate compound used here, in addition to the polyisocyanate components mentioned in the urethane foam raw material, phenyl isocyanate, hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), hydrogenated xylene diisocyanate (hydrogenated XDI), etc. can be used. It is. In addition, since the application | coating impregnation to a urethane foam layer performs an isocyanate compound in a liquid state, what is liquid at normal temperature or a comparatively low melting | fusing point is preferable.

  The application and impregnation of the isocyanate compound on the urethane foam layer can be performed by brushing, roller, spraying, dipping, or the like of the liquid isocyanate compound. In view of ease of impregnation, certainty, ease of operation, ease of removal of excess isocyanate compound, (a) spraying of isocyanate compound or (b) roll coating of isocyanate compound is suitable.

  The simplest method for impregnating the urethane foam layer with the isocyanate compound is to immerse the raw material roller in the isocyanate compound bath. However, in the immersion, the isocyanate compound reaches the inside of the urethane foam layer, and the roller hardness increases. Moreover, in immersion in an isocyanate compound bath, an isocyanate compound tends to remain excessively on the surface of the urethane foam layer. The residual isocyanate compound reacts with moisture in the air to form a urea resin, and as a result, a hard urea resin layer is formed on the surface of the urethane resin, causing a loss of elasticity. Therefore, it is preferable to spray or roll coat the isocyanate compound on the surface of the urethane foam layer. The impregnation of the isocyanate compound into the urethane foam layer is performed at a temperature at which the isocyanate compound is liquid.

  The application range of the isocyanate compound is set to the image width in the longitudinal direction centering at least on the central portion of the roller. The influence of the polyol component that exudes when supplying the toner to the developing roller in contact with the toner supply roller is large. Because. From the standpoint of preventing the contamination of the polyol component that has exuded from the developing roller, it is preferable to apply and impregnate the isocyanate compound all over the surface of the urethane foam layer of the toner supply roller.

  The amount of the isocyanate compound applied to the surface of the urethane foam layer is suitably an amount that penetrates from the surface of the urethane foam layer to about 10 μm. The suitable amount of the coating amount varies depending on the isocyanate compound used, the density of the urethane foam layer, the NCO index of the urethane foam raw material, and the like.

  Thereafter, in step (3), the isocyanate compound coated and impregnated on the surface of the urethane foam layer is treated with hot air at a temperature equal to or higher than the melting point of the isocyanate compound. The hot air treatment in this process ensures that the isocyanate compound coated and impregnated on the surface of the urethane foam layer uniformly penetrates into the surface layer of the urethane foam layer and removes the excess isocyanate compound on the surface with hot air. do. Therefore, since it is desirable that the isocyanate compound is dissolved, the temperature of the hot air treatment is usually set to be equal to or higher than the melting point of the isocyanate compound. Therefore, it is preferable to use a gas such as air, nitrogen, or argon having a temperature equal to or higher than the applied isocyanate compound melting point as the hot air used here. If the temperature of the hot air treatment is too high, the isocyanate compound to be removed excessively partially reacts with the urethane foam layer and partially hardens the urethane foam layer. It is desirable that the temperature be below the maximum temperature at which no reaction occurs. The maximum temperature at which the reaction with the urethane foam layer does not occur here is the maximum temperature at which the reaction with the urethane foam layer does not proceed during hot air treatment, and the isocyanate compound and the polyol component of the urethane foam raw material are urethanated. It may be higher than the temperature to be used.

  In addition, when applying an isocyanate compound to a urethane foam layer surface by spraying in a process (2), since warm air can be sprayed on a urethane foam layer surface from a nozzle after spraying, it is a preferable method.

  Also, the hot air treatment time is not particularly limited, but even if it is too long, the takt time becomes longer and the production efficiency decreases, so it is sufficient that the isocyanate compound remaining on the urethane foam layer surface is not observed. Usually, it is about 10 seconds to 5 minutes.

  In addition, in order to more fully remove the isocyanate compound remaining on the surface of the urethane foam layer, it may be further removed with a solvent after the hot air treatment.

  After the hot air treatment, in step (4), the impregnated isocyanate compound is placed at a temperature at which the reaction proceeds in order to react with the urethane foam layer, particularly the remaining unreacted polyol component. Thereby, it is set as the isocyanate modified urethane foam layer which the surface layer was made to react on the conditions rich in isocyanate group.

  That is, the urethane foam layer has a polyol component-rich urethane foam to ensure sufficient flexibility, and the vicinity of the surface layer is rich in the polyisocyanate component, so that the polyol component exudation from the surface layer is suppressed. In the toner supply roller whose surface partial layer is an isocyanate-modified urethane foam, the roller hardness measured by the method described later is between 40 g and 300 g, preferably between 80 g and 250 g. Is desirable.

  The toner supply roller produced as described above has sufficient flexibility and suppresses the exudation of the polyol component from the surface, so that there is no contamination of the developing roller, the image forming body, the toner and the like. That is, an electrophotographic apparatus incorporating this toner supply roller is preferable because it does not cause image defects due to the exudation of the polyol component from the toner supply roller.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Reference Example 1 Production of Roller (Raw Material Roller) Having Urethane Foam Layer Polyether Polyol Component “FA-908” (trade name, manufactured by Sanyo Chemical Co., Ltd.) 100 parts by mass, diethanolamine 0.5 part by mass, silicone-based adjustment Foaming agent “L5366” (trade name, manufactured by Nihon Unicar Co., Ltd.) 1 part by mass, tertiary amine catalyst “ToyoCat-ET” (trade name, manufactured by Tosoh Corporation) 0.1 part by mass, tertiary amine catalyst “ 0.5 parts by mass of TEDA-L33 (trade name, manufactured by Tosoh Corporation) and 2 parts by mass of water (foaming agent) were mixed to obtain a mixed polyol component. 29.5 parts by mass of the polyisocyanate component “Cosmonate T80” (trade name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., NCO% = 48) and the polyisocyanate component “Cosmonate M200” (trade name, Mitsui) Chemical Polyurethane Co., Ltd., NCO% = 31) A polyisocyanate component mixture consisting of 7.4 parts by mass is mixed and stirred so as to have an NCO index of 75 to obtain a urethane foam raw material composition, and a surface of 6 mm in diameter is made of chemical nickel The raw material roller having a urethane foam layer thickness of 3 mm was manufactured by casting into a cylindrical mold containing the iron core metal and foam molding at a temperature of 60 ° C.

Example 1
The polyisocyanate mixture used in Reference Example 1 was used as an isocyanate compound, and sprayed onto the surface of the urethane foam layer of the raw material roller manufactured in Reference Example 1 (liquid temperature 25 ° C.). Next, hot air at 50 ° C. was blown from a nozzle having an opening diameter of 1 mm at 0.5 m ³ / min until the isocyanate compound did not drip from the surface. Thereafter, the raw material roller impregnated with the isocyanate compound was heated in a hot air oven at 120 ° C. for 1 hour and further allowed to stand at room temperature for 2 days to prepare a toner supply roller.

Example 2
A toner supply roller was prepared in the same manner as in Example 1 except that the isocyanate compound was applied by roll coating using a roll coater instead of spraying with a spray gun.

Comparative Example 1
The raw material roller manufactured in Reference Example 1 was used as the toner supply roller without treating the surface of the urethane foam layer with the isocyanate compound.

Comparative Example 2
A toner supply roller having a urethane foam layer formed on a cored bar was prepared in the same manner as in Reference Example 1 except that a mixed polyol component and a polyisocyanate component mixture were used so as to have an NCO index of 120.

  The toner supply roller prepared as described above was evaluated by the following methods for the bleeding of the polyol component, the roller hardness and the image unevenness. The results are shown in Table 1.

(Leaking out polyol component)
The prepared toner supply roller is brought into contact with the SUS plate with a load of 200 g and placed in an environment of 50 ° C. and 80% RH for 10 days. After that, the polyol component exuded on the SUS plate was observed for the absorbance peak based on the polyol component with a Fourier transform infrared spectrometer “Nexus 470” (trade name) manufactured by Nicorey Japan Co., Ltd. To evaluate.
○: Absorbance peak is hardly confirmed.
Δ: Absorbance peak is slight but can be confirmed.
X: Absorbance peak can be confirmed.

(Roller hardness)
The prepared toner supply roller is supported at both ends of the core metal part, and a jig (thickness 10 mm) having a plate-like pressing surface having a width of 10 mm and a length of 50 mm is pressed on the urethane foam layer at a speed of 10 mm / min. The load (g) at the time of displacement (compression) is measured, and the value is defined as the roller hardness. It shows that a urethane foam layer is so hard that the value becomes large.

(Image unevenness)
The produced toner supply roller is used as a toner supply roller of a cartridge of a laser beam printer “LBP-1310” (trade name) manufactured by Canon Inc., and a solid black image is produced. The obtained black solid image is visually observed, and the presence or absence of unevenness due to the exudation of the polyol component on the surface of the toner supply roller is evaluated according to the following criteria.
○: Unevenness is not seen in the solid black image.
Δ: Slight unevenness is observed in the black solid image, but it is within the usable range.
X: Remarkable unevenness is observed in the black solid image.

  As for the exudation of the polyol component, the peak of the infrared spectrum could not be confirmed in Examples 1 and 2, but the exudation of the polyol component was clearly observed in Comparative Example 1. That is, exudation of the unreacted polyol component was reduced by the surface treatment. Further, when Comparative Example 1 and Comparative Example 2 were compared, the peak of the polyol component was weaker in Comparative Example 2. That is, the amount of exudation was (small Example 1 / Example 2 << Comparative Example 2 <Comparative Example 1 many).

  Regarding the roller hardness, the toner supply roller of the example had a roller hardness suitable as a toner supply roller, but the roller of Comparative Example 2 has a high roller hardness and could be determined to be unsuitable as a toner supply roller.

FIG. 6 is a perspective view of an example of a toner supply roller of the present invention.

Explanation of symbols

1 Toner supply roller 2 Core metal 3 Urethane foam layer (elastic layer)

Claims (5)

A method for manufacturing a toner supply roller, wherein a urethane foam layer is provided on a metal core, comprising at least steps (1) to (4).
(1) A urethane foam material mainly composed of a polyol component and a polyisocyanate component is injected into a roller-shaped molding die containing a core metal, foamed and cured in the mold, and urethane foam is formed on the outer periphery of the core metal. Forming a layer;
(2) A step of applying and impregnating an isocyanate compound on the surface of the urethane foam layer formed in step (1).
(3) A step of performing hot air treatment at a temperature equal to or higher than the melting point of the isocyanate compound used in step (2).
(4) A step of reacting the impregnated isocyanate compound with urethane foam to form an isocyanate-modified urethane foam layer.   The method for producing a toner supply roller according to claim 1, wherein the NCO index of the urethane foam raw material is 60 or more and 90 or less.   3. The method for producing a toner supply roller according to claim 1, wherein the impregnation of the isocyanate compound on the surface of the urethane foam layer in the step (2) is spraying of the isocyanate compound.   3. The method for producing a toner supply roller according to claim 1, wherein the impregnation of the isocyanate compound on the surface of the urethane foam layer in the step (2) is a roll coat of an isocyanate compound. 4.   A toner supply roller manufactured by the method for manufacturing a toner supply roller according to claim 1.

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