JP2007079111A - Roller for image forming apparatus, method for manufacturing roller, and molding die for manufacturing roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller for an image forming apparatus which is incorporated and used in a copying machine or the like using electrophotographic or electrostatic recording technique, which stably obtains a surface suitable for the opening of a cell without requiring a troublesome step in order to maintain the surface property of a die in the manufacture of the roller on whose surface the cell is opened, by which excellent performance is obtained by making stable mold releasability compatible with the opening property of the cell, and a method for manufacturing the roller and a molding die for manufacturing the roller. <P>SOLUTION: The method for manufacturing the roller for the image forming apparatus having a core bar and one or more polyurethane foam layers formed on the core bar, includes: a step for arranging the core bar and providing a coating film constituted by hardening liquid silicone rubber inside a die used by injecting material liquid of the polyurethane foam layer; and a step for foaming and molding the material liquid of the polyurethane foam layer in the metallic die. The roller for the image forming apparatus and the molding die for manufacturing it are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention provides an image forming apparatus roller that can be suitably used for a foam roller having an open surface cell that is mounted on an image forming apparatus, such as a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. The present invention also relates to a method for manufacturing the image forming apparatus roller, and a molding die for manufacturing the image forming apparatus roller used at that time.

  In recent years, the demand for images in computers and the like that digitize images has increased, and accordingly, higher definition and higher quality images are required, and further improvements in color images and electrophotographic images are required. The use of skinless polyurethane foam has been increasing for members containing a polymer material having rubber elasticity used for these purposes in order to reduce stress on the toner and improve the quality of reproduced images. When the polyurethane foam is used for an elastic member for an image forming apparatus such as a toner supply roller, it has a low hardness and also has fine cells and requires a skinless surface uniformity. For example, the toner supply roller is for supplying toner and scraping off unnecessary portions, and the transfer roller is for conveying paper.

  As a method of manufacturing a roller that satisfies these requirements, for example, in the toner supply roller, an elastic sponge such as polyurethane foam or foamed silicone is supported on the surface of the core metal, and the outer surface of the supported sponge is processed and formed into a roller shape. Then, the surface cell of the roller is opened. In general, the roller shape processing of the sponge, that is, the outer diameter processing is performed by mechanical processing such as a polishing machine, or by melt cutting processing such as cutting with a heated nichrome wire.

  However, the toner supply roller is required to have a function of supplying toner to the developing roller in the developing device, scraping off unnecessary portions thereof, and supplying the toner uniformly onto the developing roller. The fluffing of the surface of the elastic roller obtained by the processing method according to the method destabilizes the toner conveyance amount as the toner supply roller and causes the problem of image defects. In addition, when the fluff is missing from the roller surface, the electrophotographic system It becomes a foreign matter such as clogging in other parts, which may cause image defects and failures.

  Further, in the case of processing with nichrome wire, when the density of the sponge is high, the hardness is hard, and the foamed cell diameter is small, the nichrome wire is easily deformed or cut, and the processing accuracy is likely to be lowered. On the other hand, if the processing speed is reduced so that no load is applied to the nichrome wire, the nichrome wire cannot be cut, but the productivity of the roller is lowered. Further, when the energization amount of the nichrome wire is increased and the heat generation temperature is increased, there is a problem that the allowance of the sponge becomes large, the processed surface becomes wavy and does not become smooth.

  In any of these conventional roller manufacturing methods in which surface cells are opened, various problems are inherent, manufacturing processes such as polishing and cutting are complicated, and unnecessary parts are discarded, resulting in high dimensional accuracy. There are inherent problems such as bad.

  Therefore, as a method of manufacturing a toner supply roller in which a polyurethane sponge layer has a skin layer and each cell located immediately below the skin layer is independently opened to the outside by an opening, a roll in a molding cavity is used. Concave grooves corresponding to the plurality of ridges that give the uneven surface structure are formed on the inner surface of the mold forming the outer peripheral surface, and the surface 10-point average roughness: Rz is adjusted to be 5 to 20 μm. A method of manufacturing a toner supply roller is proposed, in which a soft polyurethane sponge layer is formed using a mold provided with a coating layer of a silicone-based or fluorine-based release agent (see Patent Document 1). ).

  In addition, a method for manufacturing a toner supply roller has been proposed in which the surface of a polyurethane foam is modified by injecting a urethane material into a mold coated with a silicone oil having a reactive group on the inner peripheral surface ( Patent Document 2).

  However, in Patent Document 1, the coating layer on the inner surface of the mold is a general release agent, and migration from the mold becomes a problem, and the components are not studied at all. Furthermore, when the mold is roughened, problems such as adhesion of urethane to the mold may easily occur. In Patent Document 2, since the silicone oil having a reactive group reacts with the polyurethane foam material, it enters into the polyurethane foam material during foam molding, causes abnormal foaming, has a low viscosity, and has good fluidity. For this reason, silicone oil flows at the time of molding, and a problem that a longitudinal difference occurs in the surface cell of the roller is likely to occur. Furthermore, a large amount of silicone oil adheres to the surface of the roller for the image forming apparatus, which may contaminate other members and toner that come into contact with the roller.

  Moreover, as a main mold release agent, a non-transition type that forms a solid film by a close contact reaction with a mold release agent and a mold release mold film at the mold-release agent film interface or a mold-release agent film interface. There is a release agent. Generally, in mold molding of polyurethane foam, a transition mold release agent is used, and any of the mold release agents is transferred to the molded product, so that in some cases, roller cleaning is necessary, and the mold release is performed for each molding. It is necessary to apply the agent and clean the mold. In general, the mold release agent has a melting point, so if the mold temperature is too high, it will mix into the foam and roughen the surface. There is a problem that it falls. In addition, these mold release agents may not be familiar with the mold and may be difficult to apply evenly, resulting in poor dimensional accuracy due to partial formation of a skin layer or tearing of the foam with poor mold release properties. There was a case.

Furthermore, if molding is repeated, the surface properties of the mold deteriorate due to accumulation of release agents and polyurethane in the mold, and it becomes impossible to stably obtain the surface roughness suitable for the cell opening. In some cases, the frequency of mold cleaning and the number of times of application of the release agent may increase due to the decrease in properties.
Japanese Patent No. 3536598 JP 2002-341642 A

  An object of the present invention is to solve the above-mentioned problems, and is mainly used in the manufacture of a roller in which a cell is opened on a roller surface, which is used by being incorporated in a copying machine using electrophotography or electrostatic recording technology. Without requiring complicated steps to maintain surface properties, a surface suitable for cell opening can be stably obtained, and both stable demolding and cell opening properties can be achieved, and good performance can be obtained. An image forming apparatus roller is provided.

  Another object of the present invention is to provide a method for manufacturing the roller for an image forming apparatus and a molding die for manufacturing the roller for the image forming apparatus.

  The present inventors have conducted intensive studies to solve the above problems, and have found that the object of the present invention can be achieved by the following invention.

According to the present invention, there is provided a method for producing a roller for an image forming apparatus having a cored bar and one or more polyurethane foam layers formed on the cored bar,
A step of providing a coating film formed by curing liquid silicone rubber on the inner side of a mold used by injecting a material liquid of the polyurethane foam layer by disposing the core metal;
A step of foam-molding the material liquid of the polyurethane foam layer in the mold,
A method for manufacturing a roller for an image forming apparatus is provided.

Further, according to the present invention, there is provided a roller for an image forming apparatus having a cored bar and one or more polyurethane foam layers formed on the cored bar according to the above manufacturing method,
The density of the polyurethane foam layer 50 kg / ^{m 3} or more 200 kg / ^{m 3} or less, and which has a hardness of less than or equal to 350 g, the average opening diameter of the outside of each cell existing in the surface layer of the polyurethane foam layer is 100μm or more 800μm There is provided a roller for an image forming apparatus, characterized in that the cell open area ratio is 20% or more of the surface of the polyurethane foam layer.

Further, according to the present invention, there is provided a molding die for manufacturing a roller for an image forming apparatus, comprising: a cored bar, a mold main body for arranging the cored bar, and an auxiliary mold for fixing both ends of the cored bar.
The mold is provided with a mold for manufacturing a roller for an image forming apparatus, characterized in that a coating film formed by curing liquid silicone rubber is provided on the inside thereof.

  According to the present invention, it is mainly used in electrophotography, a copying machine using electrostatic recording technology, etc., and is complicated to maintain the surface property of the mold in the manufacture of a roller in which cells are opened on the roller surface. Since a surface suitable for cell opening can be stably obtained without requiring a process, it is possible to achieve both stable demolding after molding and cell opening on the roller surface. It has become possible to provide a roller for an image forming apparatus capable of obtaining performance, a method for manufacturing the roller for the image forming apparatus, and a molding die for manufacturing the roller for the image forming apparatus.

  Next, an embodiment of the present invention will be described.

  The present invention relates to a method for producing a roller for an image forming apparatus having a cored bar and one or more polyurethane foam layers formed on the cored bar. A method of manufacturing a roller for an image forming apparatus, comprising: a step of providing a coating film formed by curing a liquid silicone rubber inside a mold used for injection; and a step of foaming a material liquid of the polyurethane foam layer in the mold. is there.

(About silicone rubber)
Silicone rubber not only has excellent heat resistance, but also has excellent resilience as a rubber elastic body, so that dimensional stability is good, and surface releasability is good, and most materials other than silicone are easily peeled off.

  Liquid silicone rubber has excellent processability, has no dimensional stability due to the absence of by-products associated with the curing reaction, and has been subjected to addition reaction crosslinking for reasons such as stable physical properties after curing. Type silicone rubber polymer is more preferred.

  This silicone rubber polymer contains, for example, an organopolysiloxane represented by the following formula (1) and an organohydrogenpolysiloxane represented by the following formula (2), and further mixed with a catalyst and other additives as appropriate. Can be used.

  Organopolysiloxane is a base polymer of a silicone rubber raw material, and the molecular weight is not particularly limited, but is preferably 100,000 or more and 1,000,000 or less, and the average molecular weight is more preferably 400,000 or more and 700,000 or less. Furthermore, from the viewpoint of processing characteristics and characteristics of the resulting silicone rubber composition, the viscosity of the organopolysiloxane is preferably 10 Pa · s or more, more preferably 50 Pa · s or more as a lower limit, and 300 Pa · s or less as an upper limit. Is preferable, and 250 Pa · s or less is more preferable.

  The alkenyl group of the organopolysiloxane is a site that reacts with the active hydrogen of the organohydrogenpolysiloxane to form a crosslinking point, and the type thereof is not particularly limited, but for reasons such as high reactivity with active hydrogen. , At least one of a vinyl group and an allyl group is preferable, and a vinyl group is particularly preferable.

  Organohydrogenpolysiloxane functions as a crosslinking agent for addition reaction in the curing process, and the number of silicon atom-bonded hydrogen atoms in one molecule is 2 or more, and in order to perform the curing reaction optimally, Three or more polymers are preferred. There is no restriction | limiting in particular in the molecular weight of polyorganohydrogen polysiloxane, Although it contains from 1000-10000, In order to perform hardening reaction appropriately, comparatively low molecular weight 1000 or more and 5000 or less are preferable.

  Liquid silicone rubber includes additives such as crosslinking catalysts, curing reaction retarders, reinforcing fillers and extenders, conductive materials, other elastic polymers, plasticizers, other processing aids, colorants, UV absorbers, flame retardants, Oil resistance improvers, foaming agents, scorch inhibitors, tackifiers, lubricants and the like can be added as necessary. For various additives, if the problems such as the increase in viscosity of the material and the increase in hardness are in a range that can be adjusted by the cross-linking density of the polymer or the viscosity of the polymer itself, it is possible to add more from the viewpoint of cost. It is known that the amount of the additive is blended as much as possible in consideration of the cost as much as possible for the actual material.

  However, increasing the compounding amount of the above various additives will inhibit the behavior of the polymer component for developing rubber elasticity in the material by various additive molecules, and it should be included in the liquid silicone rubber. The amount of various additives that can be controlled is preferably in a range that does not impede the behavior of the polymer in the liquid silicone rubber while ensuring the reinforcement to the material.

(Contact angle)
The contact angle of the liquid silicone rubber coating film using ethylene glycol is preferably 70 degrees or more. By using the inner surface of the molding die in which the contact angle of ethylene glycol having a structure similar to that of polyether polyol in the urethane raw material is 70 degrees or more, the inner phase of the molding cavity constitutes at least the inner surface of the molding cavity. Due to the melting action or surface tension action, the polyurethane raw material is placed in the part closest to the inner surface of the cell mold generated by foam molding of the liquid polyurethane raw material, in other words, in the portion corresponding to the center of the cell where the thickness of the skin layer is the thinnest. A non-existing portion is generated, and thereby an opening is formed in the skin layer on the surface of the urethane foam layer to be formed, and the cell opens to the outside through the opening. If the contact angle of ethylene glycol on the inner surface of the mold is less than 70 degrees, the effect due to urethane incompatibility or surface tension cannot be exhibited sufficiently, unevenness of the cell opening occurs, and sufficient opening. It is hard to become a caliber. In addition, when the contact angle of ethylene glycol is smaller than 70 degrees, the adhesion of urethane foam during foaming becomes stronger, making it difficult to release the urethane foam obtained by foaming in the mold from the mold. Become.

  In other words, unlike the above-described conventional release agent used for the inner surface of the mold, the presence of the liquid silicone rubber coating film according to the present invention causes the inner surface of the mold to have oil repellency and surface tension. As a result, an opening for allowing the cell to communicate with the outside is effectively formed, the mold release property is good, it can be used at a wide range of mold temperatures, and the roller surface is not roughened. Since the release agent does not migrate, there is no contamination to other members, and the rollers need not be cleaned.

  The contact angle of ethylene glycol was measured with a contact angle meter (image processing type) CA-X manufactured by Kyowa Interface Science Co., Ltd. Specifically, as shown in FIG. 1, the contact angle θ is an angle formed between the tangent line of ethylene glycol and the sample at the contact point between ethylene glycol and the measurement sample.

  FIG. 2 is a perspective view showing an example of a roller for an image forming apparatus according to the present invention. As shown in FIG. 2, the image forming apparatus roller 3 includes a cylindrical cored bar 4 and a polyurethane foam which is a foamed elastic body provided around the cored bar 4 except for both ends of the cored bar 4. A surface layer 5 is provided.

(About density of polyurethane foam layer)
The density of the polyurethane foam layer is preferably 50 kg / ^{m 3} or more 200 kg / ^{m 3,} and more preferably still more 70 kg / ^{m 3} or more 100 kg / ^{m 3.} The density of the polyurethane foam layer was measured according to JIS K 6400 method. If the density is less than 50 kg / m ^3, it is difficult to mold as a roller, and even if possible, excessive use of water as a foaming agent results in large permanent deformation and a reduction in image quality, making it unusable. On the other hand, if it exceeds 200 kg / m ³ , there is a problem that the roller inevitably increases in hardness and promotes toner deterioration.

(About the hardness of the polyurethane foam layer)
The hardness of the polyurethane foam layer is preferably 350 g or less, more preferably 100 g or more and 300 g or less at a temperature of 15 to 32.5 ° C./relative humidity of 10 to 80% RH. When the hardness exceeds 350 g, there are problems such as promoting toner deterioration.

(About opening diameter and cell opening area ratio)
The average opening diameter to the outside of each cell existing in the surface layer part of the polyurethane foam layer is preferably 100 μm or more and 800 μm or less. More preferably, it is 200 μm or more and 700 μm or less. For example, when it is used as a toner supply roller, if it becomes smaller than 100 μm, it is difficult for the toner that has entered the cell through the opening, the hardness increases, and image defects occur, and the opening diameter is 800 μm. If the value exceeds 1, the toner supply amount decreases, causing problems such as density reduction and streak generation.

  It is preferable that the cell open area ratio occupies 20% or more of the surface of the polyurethane foam layer. More preferably, it is 50 to 90%. If it is less than 20%, the surface opening tends to be non-uniform, which is not preferable. For example, when used as a toner supply roller, the amount of toner transport becomes unstable, making it impossible to supply the toner uniformly, and further, the toner tends to clog the polyurethane foam layer, which partially increases the hardness. However, the image is likely to deteriorate.

  The type of roller for the image forming apparatus using the polyurethane foam of the present invention is not particularly limited, and examples thereof include a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. Needless to say, based on the polyurethane foam of the present invention, necessary conductivity is imparted and a necessary film is formed according to the usage form of each roller.

  The roller for an image forming apparatus of the present invention comprises a polyurethane foam, and the polyurethane foam is formed from a urethane raw material containing at least a polyol and a polyisocyanate.

  The polyurethane raw material is in the same liquid form as before, and any conventionally known reactive raw material (a blend of a polyol component and a polyisocyanate component) that foams and cures in a mold is particularly limited. It will be selected and used appropriately.

(About the polyol component)
For example, as the polyol component constituting such a liquid polyurethane raw material, any of known polyols such as polyether polyol, polyester polyol and polymer polyol, which are generally used in the production of flexible polyurethane foams, is used. obtain.

(About polyisocyanate component)
Further, as the polyisocyanate component, all known polyfunctional or higher polyisocyanates 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), carbodiimide-modified MDI, polymethylene polyphenyl isocyanate, polymeric polyisocyanate and the like can be used alone or in combination. .

  In addition, in the polyurethane raw material in which these polyol component and polyisocyanate component are blended, a crosslinking agent, a foaming agent (water, low-boiling substances, gas body, etc.), a surfactant, a catalyst, etc. Is added to form a known foamed polyurethane sponge layer structure, that is, a well-known compound that is easy to produce either an open-cell type or a closed-cell type, and is used as a reactive foam raw material. However, such raw materials include flame retardants and fillers as necessary, and conductivity imparting agents for imparting desired conductivity to the rollers, antistatic agents, and the like as in the past. To be added.

(About molds for rollers for image forming devices)
FIG. 3 is an explanatory view showing an example of a molding die for manufacturing the roller for the image forming apparatus of the present invention. The molding die for a roller for an image forming apparatus of the present invention is not particularly limited, and can be used by appropriately selecting from conventionally known materials and shapes. For example, it is made of stainless steel (SUS304) and has a vent hole (a small hole communicating with the inside and outside of the mold having a hole diameter of about 1 mm provided to prevent gas from accumulating in the mold and causing the foam to become thin). And a pipe-shaped mold having an uneven shape on the inner surface.

  The molding die of the present invention is a molding die for manufacturing a roller for an image forming apparatus having a cored bar, a mold main body in which the cored bar is disposed, and an auxiliary mold for fixing both ends of the cored bar. A molding die for manufacturing a roller for an image forming apparatus, characterized in that a coating film formed by curing liquid silicone rubber is provided on the inside.

(About silicone rubber coating film of mold)
The thickness of the coating film formed by curing the liquid silicone rubber in the mold is generally about 1 to 10 μm. This is because if the thickness of the coating film becomes too thin, the function of the coating film cannot be fully exerted, and if it becomes too thick, no further effect can be obtained, and on the contrary, the cost becomes high, and the thermal conductivity. In a mold having an uneven shape, the shape of the uneven surface structure deteriorates, which is not preferable. In addition, the liquid silicone rubber is applied to the inner surface of the mold, and then becomes a coating film whose film strength is improved by heat curing. The coating method is not particularly limited, and may be a conventional method. An example is as follows. First, liquid silicone rubber diluted to a solution with a solid content of 3-5% with a solvent is uniformly applied in a mold to about 5 μm, and heated at 100 ° C. for 20 minutes for reaction curing to form a silicone rubber coating film. can do.

  If necessary, an adhesive layer can be provided between the mold and the liquid silicone rubber. As this adhesive layer, known materials such as a primer and an adhesive can be used.

(About mold release agent)
A known release agent can be used, preferably a release agent having good wettability to the silicone rubber coating film, and a silicone resin-based or fluororesin-based mold release agent on the liquid silicone rubber coating film. An agent or the like can be appropriately selected and used. In addition, an aqueous release agent containing silicone oil, a fluorine compound, and one or more waxes is preferable from the viewpoint of the environment and surface properties.

  The film thickness of the release agent to be applied is not particularly limited as long as it does not affect the product dimensions, but the film thickness is more preferably 1 to 1000 μm.

(Method for manufacturing roller for image forming apparatus)
The method for producing the roller for an image forming apparatus of the present invention is not particularly limited, and may be a conventional method. An example is as follows. First, liquid silicone rubber was uniformly applied in a mold, and heated and cured at 100 ° C. for 20 minutes to form a silicone rubber coating film of about 5 μm. By preparing a urethane raw material by homogeneously mixing the polyol, polyisocyanate, catalyst and foam stabilizer, water, and other auxiliaries used as required, and then injecting this into a mold and heating to reaction and curing. Polyurethane foam can be formed. In addition, after foaming molding of such a polyurethane foam layer, known crushing may be appropriately performed. For example, a method of spraying compressed air or the like having a predetermined pressure is advantageously employed.

  Although there is no restriction | limiting in particular about the temperature and time at the time of mixing the said urethane raw material, Mixing temperature is 10-90 degreeC normally, Preferably it is the range of 20-60 degreeC, and mixing time is 1 second-10 minutes normally. It is preferably about 3 seconds to 5 minutes.

  Further, when heated and reaction-cured, a roller for an image forming apparatus made of polyurethane foam can be produced by foaming by a conventionally known method. The foaming method is not particularly limited, and any method such as a method using a foaming agent and a method of mixing bubbles by mechanical stirring can be used. The temperature of the mold during foaming is preferably 35 to 100 ° C, more preferably 40 to 80 ° C.

(Roller for image forming device)
The roller for an image forming apparatus of the present invention uses the polyurethane foam thus obtained, and is usually made of iron plated or stainless steel, for example, having a diameter of 4 to 6 mm and a length. Can be manufactured by coating a core metal of 200 to 400 mm with the polyurethane foam to form an elastic layer. Depending on the application, the outside may be painted with a conductive, semiconductive or insulating paint.

  The outer diameter of the image forming apparatus roller of the present invention is not particularly limited, and may have various outer diameters depending on the purpose, but generally has an outer diameter of 10 to 20 mm.

  The method for joining the core metal and the polyurethane foam is not particularly limited. However, the core metal is preliminarily disposed in the mold (molding mold), the polyurethane raw material is cast and cured, or the polyurethane foam is molded into a predetermined shape. Then, a method of adhering can be used. In either method, an adhesive layer can be provided between the cored bar and the polyurethane foam as necessary. As the adhesive layer, a known material such as an adhesive or a hot melt sheet can be used.

  The roller for an image forming apparatus is not limited to the one having the above configuration, and may further have a plurality of layers on the inner peripheral side and the outer peripheral side of the polyurethane foam layer.

  The present invention does not require a troublesome process such as a polishing process as in the prior art, and can extremely easily manufacture a roller for an image forming apparatus. It can effectively solve problems such as skin layer tearing and release material transfer to other members. It is possible to manufacture a roller for an image forming apparatus that can obtain performance.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited at all by these examples.

(Examples 1 and 2)
First, as a forming die, a pipe die is used, and a liquid silicone rubber is uniformly applied to the inner surface of a stainless steel (SUS304) die pipe corresponding to the inner surface of the die, and a silicone rubber coating film is formed to 5 μm by reaction curing. Formed.

"Urethane raw materials"
Polyol: (trade name: MF78, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass Foam stabilizer: (trade name: L-5366, manufactured by Nippon Unicar Co., Ltd.) 1 part by mass Catalyst: (trade name: TOYOCAT-ET 0.1 parts by mass (trade name: TOYOCAT-MR, manufactured by Tosoh Corporation) 0.3 parts by mass distilled water 2.0 parts by mass Polyisocyanate: (trade name: TM-50, Mitsui) Takeda Chemical Co., Ltd.)
15.2 parts by mass The above polyol component (polyol, foam stabilizer, catalyst, water, etc.) and polyisocyanate component were adjusted to a liquid temperature of 25 ° C. And after mixing both liquids and stirring for 5 seconds with a stirring blade, the amount of the material that becomes a density of 100 kg / m ³ is preliminarily attached to a predetermined position inside a core metal made of SUS304 with a diameter of 5 mm and a length of 270 mm. Poured into the mold. Next, the temperature of the mold for the image forming apparatus roller was adjusted to 60 ° C. in an electric furnace at 100 ° C., cured for 20 minutes in this mold, and taken out from the mold to produce an image forming apparatus roller having an outer diameter of 16 mm. . In order to confirm the demoldability, the molding was repeated as much as possible up to 10 times.

(Comparative Example 1)
A toner supply roller was manufactured in the same manner as in Example 1 except that a pipe mold in which a fluorine resin was uniformly applied to the inner surface of a SUS304 mold pipe and a coating film was formed to have a thickness of about 5 μm was used.

(Comparative Example 2)
Applying DEXTER's free coat 770NC as a commercially available non-migrating mold release agent based on silicone (resin) without applying liquid silicone rubber to the inner surface of the mold pipe made of SUS304, and forming a solid film by closely reacting with the mold surface A toner supply roller was manufactured in the same manner as in Example 1 except that the pipe type was used.

(Comparative Example 3)
A pipe mold in which URH-511 manufactured by Konishi Co., Ltd. was applied as a wax-based commercially available transition mold release agent without applying liquid silicone rubber to the inner surface of the SUS304 mold pipe was used. A toner supply roller was produced in the same manner as in Example 1 except that the coating was performed.

  The measured values of the contact angle of the mold inner surface treatment and the physical properties of the produced roller for the image forming apparatus were measured by the following methods, and the results are shown in Table 1.

<Density measurement>
The density of the polyurethane foam layer was measured according to JIS K 6400 method. The density of the urethane foam of the image forming apparatus roller was calculated by measuring the mass of the urethane foam of the image forming apparatus roller.

<Hardness measurement>
The roller for the image forming apparatus is supported by the cored bar portions at both ends, and the surface layer is placed on a jig having a plate-like pressing surface having a length of 50 mm (roller longitudinal direction) × width of 10 mm (thickness: 10 mm). Then, it was obtained from the load applied to the roller surface when it was deformed by 1 mm by pressing at a speed of 10 mm / min. The larger the value, the harder the surface layer made of polyurethane foam. The hardness was measured at three locations in the axial direction, 4 locations every 90 degrees in the circumferential direction in each axial direction, a total of 12 locations, and the average value was determined. The measurement environment was a temperature of 23 ° C./relative humidity of 53% RH.

<Contact angle measurement>
The measurement of the contact angle of ethylene glycol is the same as the pipe type on the test piece, and the contact angle between ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) and the test piece is measured as shown in FIG. It measured using the apparatus (Kyowa Interface Science Co., Ltd. product CA-DT type | mold). The measurement environment was a temperature of 23 ° C./relative humidity of 53% RH.

<Measurement of average opening diameter and cell opening area ratio>
And about the cell opening of the obtained roller, the surface image was taken in using the real-time scanning laser microscope, the cell opening diameter was measured, and the average value was calculated | required. In addition, binarization processing was performed by image analysis to obtain a cell opening area ratio.

Cell opening area ratio [%] = cell opening area / image range × 100
In addition, the numerical value in a table | surface is a value of the roller for image forming apparatuses of the 1st shaping | molding / 5th time.

<Evaluation of demoldability>
○ that the light releasability persists even if it is repeatedly used 10 times or more, Δ that the light releasability lasts from 5 times to less than 10 times, and the peeling becomes heavy when the number of moldings is less than 5 times Those that could not be demolded from the initial stage of molding were evaluated as x.

The polyurethane foam layers in the various image forming apparatus rollers obtained had a hardness of 180 to 220 g and a density of 100 kg / m ³ .

  Comprehensive judgment made the average opening diameter 100-800 micrometers irrespective of the frequency | count of shaping | molding, the cell opening area ratio 20% or more, and the demolding property was favorable: (circle), when it was out of the range: x.

  As a result, in the polyurethane foam image forming apparatus roller shown in this example, the polyurethane foam layer is foam-molded in a mold provided with a coating film formed by curing liquid silicone rubber on the inside. It can be seen that the feature makes it possible to obtain a roller for an image forming apparatus which can stably achieve both the mold release property and the cell opening property even when molding is repeated, and obtain good performance.

It is explanatory drawing which shows the measurement of contact angle (theta). It is a perspective view showing an example of a roller for an image forming apparatus of the present invention. It is explanatory drawing which shows an example of the shaping die for manufacture of the roller for image forming apparatuses of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ethylene glycol 2 Measurement sample 3 Roller for image forming apparatus 4 Core metal 5 Surface layer 6 Pipe mold 7 Upper piece 8 Lower piece 9 Injection hole 10 Degassing gap 11 Container 12 Liquid silicone rubber coating film

Claims (6)

A method of manufacturing a roller for an image forming apparatus having a cored bar and one or more polyurethane foam layers formed on the cored bar,
A step of providing a coating film formed by curing liquid silicone rubber on the inner side of a mold used by injecting a material liquid of the polyurethane foam layer by disposing the core metal;
A step of foam-molding the material liquid of the polyurethane foam layer in the mold,
A method of manufacturing a roller for an image forming apparatus, comprising:   The method for producing a roller for an image forming apparatus according to claim 1, wherein the liquid silicone rubber is an addition reaction cross-linking type silicone rubber polymer.   The method for producing a roller for an image forming apparatus according to claim 1, wherein the liquid silicone rubber coating film has a contact angle of 70 ° or more using ethylene glycol. A roller for an image forming apparatus having a cored bar and one or more polyurethane foam layers formed on the cored bar according to the manufacturing method according to claim 1,
The density of the polyurethane foam layer 50 kg / ^{m 3} or more 200 kg / ^{m 3} or less, and which has a hardness of less than or equal to 350 g, the average opening diameter of the outside of each cell existing in the surface layer of the polyurethane foam layer is 100μm or more 800μm A roller for an image forming apparatus, characterized in that the cell opening area ratio is 20% or more of the surface of the polyurethane foam layer.   The image forming apparatus roller according to claim 4, wherein the image forming apparatus roller is any one of a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. A molding die for manufacturing a roller for an image forming apparatus, comprising: a metal core, a metal mold main body for disposing the metal core, and an auxiliary metal mold for fixing both ends of the metal core,
A mold for manufacturing a roller for an image forming apparatus, wherein the mold is provided with a coating film formed by curing a liquid silicone rubber inside.