JP4746859B2 - OA roller molding die and OA roller molding method - Google Patents

Description

  The present invention relates to a mold used for molding an OA roller used for a charging roller, a developing roller, a transfer roller, a toner supply roller, a cleaning roller, a paper feed roller, and the like in an image forming apparatus such as a dry electrophotographic apparatus, and molding of the roller. Regarding the method.

In recent years, with the advancement of electrophotographic technology, image forming apparatuses such as dry electrophotographic apparatuses have components made of polymer materials for charging, developing, transferring, toner supplying, cleaning, and paper feeding. Specifically, it is used in the form of an elastic roller such as a charging roller, a developing roller, a transfer roller, a toner supply roller, a cleaning roller, and a paper feed roller.
As the material of these OA rollers, a polymer elastomer or foam such as rubber or polyurethane is usually used, and it is required to have a low hardness and not contaminate an image forming body or a transfer material.

  However, in order to reduce the hardness of rubber and polyurethane elastomers, it is necessary to blend plasticizers such as dioctyl phthalate and oils such as aroma oils, and satisfy the requirement not to contaminate image forming bodies. Have difficulty.

  Therefore, in recent years, foams in which ethylene-propylene-diene rubber (EPDM) or silicone rubber is foamed with a foaming agent such as 4,4′-oxybis (benzenesulfonylhydrazide), or polyurethane is foamed with water or chlorofluorocarbon. It is advantageous to use foams foamed with an agent, in particular polyurethane foams are recommended.

  As a method of manufacturing a roller using this polyurethane foam, for example, a foam-forming material containing a polyol component, a polyisocyanate component, a physical foaming agent, and optionally a conductivity imparting agent, a urethane reaction catalyst, etc. Known is a method of injecting into a mold having a shape and foaming and curing, or by allowing a block to be freely foamed and then heat-curing, cutting out from the block to a predetermined dimension, and attaching a shaft.

Among these methods, a method using a cylindrical mold is frequently used because it does not necessarily require a polishing treatment after demolding.
As a method for producing a polyurethane foam roller using this cylindrical mold, for example, Patent Document 1 describes a basic process. That is, as shown in FIG. 1, first, one end side opening of a metal cylindrical mold 1 is closed with a cap 2, and then the shaft 3 is arranged at the center, and then the other opening of the mold 1. Fit the cap 4 to the. Thereafter, as shown in FIG. 1A, the foam-forming material 5 is injected from an injection portion (not shown) provided in the cap 2.

  Subsequently, as shown in FIG.1 (b), it is made to foam by heating to a temperature range of 15-80 degreeC normally, Preferably it is 20-65 degreeC. The foam expansion of the foam-forming material 5 is further advanced, and the inside of the mold 1 is filled with the foam 6 as shown in FIG. Thereafter, in a pressure holding state in which the inside of the mold 1 is sealed, curing is performed at a temperature of about 70 to 120 ° C., for example, and the polyurethane foam roller 7 shown in FIG. 1D is obtained.

Here, a coating layer made of a fluororesin or the like is provided on the entire inner peripheral surface of the mold 1, or a known silicone-based or fluorine-based release agent is applied to the entire surface to A device for making it easy to extract a product roll has been made (see Patent Document 1).
JP 2002-113727 A

By the way, in the foam expansion and the subsequent curing process, it is necessary to securely seal the inside of the mold 1 and maintain it at a predetermined pressure, so that the cap 4 is firmly fitted into the opening of the mold 1. It is important to be airtight. For this purpose, the cap 4 is usually attached by being strongly pushed into the inside of the opening of the mold 1. Accordingly, there is a problem in that this portion is worn early as a result of strong friction between the inner peripheral surface of the mold 1 on the both end opening side and the cap. When the portion is worn, a gap is generated between the cap and the airtightness in the mold cannot be maintained, and foam molding may be hindered.

Further, as described above, a coating layer made of a fluororesin or the like is usually provided on the entire inner periphery of the mold 1, but such a coating layer has a mold release property and a foam surface property. Because it is intended to improve the quality of the coating layer, it may easily wear out and lead to peeling of the coating layer. From this peeling point, the peeling of the coating layer progresses into the mold, and the coating layer is originally required. Even in the foaming region of the mold, a serious situation where the coating layer peeled off was simulated.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a mold that eliminates the problem of wear on the inner peripheral surface of both ends of the mold, and proposes a method for stably forming an OA roller using the mold. And

As a result of intensive research to achieve the above object, the inventors limited to the inner peripheral portion in contact with the cap to be pushed into the mold, and formed a coating having excellent abrasion resistance different from the foamed region. By doing so, it was found that the influence of wear by the cap can be eliminated.
The present invention has been completed based on such findings.

That is, the gist of the present invention is as follows.
(1) Around the shaft previously placed in the mold by injecting a foam-forming material into the mold in which the caps are inserted into the openings at both ends of the cylindrical mold and the inside is sealed, and foam-cured. The mold used when forming the OA roller by forming a foam layer on the inner surface of the mold, and the ten-point average roughness of the surface in the cap insertion area where the cap contacts each other There has wear resistant coating is 3 or more and 5 or less, and the bubble-generating region sandwiched between both the cap insertion region, ten-point average roughness of the surface have a releasing film is 10 or more, resistance to A mold for forming an OA roller , wherein the boundary between the wearable film and the releasable film is between the bottom surface of the cap inserted into the mold and the end of the use area of the OA roller.

( 2 ) A foam-forming material is injected into a mold in which a cap is inserted into each end opening of a cylindrical mold and the inside is sealed, and foam hardening is performed. A method for forming an OA roller, wherein the mold described in the above (1 ) is used in forming an OA roller by forming a foam layer around it.

According to the present invention, since the wear-resistant film is formed only in the cap insertion area where wear resistance is required in the mold, the durability of the mold is significantly improved without hindering the function of the foaming area. I was able to.

Next, the metal mold | die of this invention is demonstrated in detail with reference to drawings.
As previously shown in FIG. 1, in the mold 1, caps 2 and 4 are fitted into openings on one end side and the other end side, respectively, so that the inside of the mold is hermetically sealed.
Here, as shown in FIG. 2, the inner peripheral surface of the mold 1 is sandwiched between the cap insertion region Rc that comes into contact with the caps 2 and 4 inserted from the opening, and the one and the other cap insertion region Rc. The foamed region Rb, which is responsible for the roll forming, is divided into three regions, and an abrasion-resistant coating 8a is formed on the inner peripheral surface of the mold 1 corresponding to the cap insertion region Rc, while corresponding to the foamed region Rb. It is important to form the releasable coating 8b on the inner peripheral surface of the mold 1 to be performed.

That is, the wear resistant coating 8a provided corresponding to the cap insertion region Rc exerts a high wear resistance in the fitting between the cap 2, or 4, more preferably those excellent in stain resistance, the front surface A ten-point average roughness (Rz) of 3 or more and 5 or less , for example, a coating having a contact angle (wetability) of 80 ° or more and a thickness of 5 μm or less is suitable.
By finishing small roughness of the film surface, to reduce the occurrence of pinholes of the film, dirt accumulation is reduced, and to disperse the stress of pressing by the cap, keeping the coating initial performance be able to.

These wear-resistant coatings 8a can be formed from the end of the mold to the cap insertion region Rc by a method such as a dipping method.

On the other hand, the releasable coating 8b is provided in the foaming region Rb for foaming and curing the foam-forming material to form the foam, thereby improving the surface properties of the foam, and forming the roll after molding. It helps to improve the releasability when removing from 1. In other words, releasing film 8b is a ten-point average roughness of the front surface (Rz): A 10 or more of those, for example, the contact angle (wettability): 80 ° or more and thickness: 10 to 50 [mu] m coating Is preferred.
Surface Texture result capable of removing the skin layer of the roll surface by a larger, it can be avoided that the contact area of the roll and the film will stick to the mold decreases.

  Specifically, a film made of a fluororesin having a surface roughness Rz of 15 or more by mixing PTFE powder in the fluororesin is advantageously suitable.

Further, the boundary between the wear-resistant coating 8a and the releasable coating 8b may be between the bottom surface 2a or 4a of the cap 2 or 4 inserted into the mold and the end of the use area of the OA roller. Here, the use area end of the OA roller is a portion that remains as a product without being removed by post-processing, and the other (outside) is a portion that is removed by post-processing.

Next, a method for forming a roll using the above mold will be described in detail.
That is, as shown in FIG. 1, the opening on one end side of the mold 1 is first closed with the cap 2, the shaft 3 is disposed at the center, and then the cap 4 is placed on the other opening of the mold 1. Fit together. When the caps 2 and 4 are attached, the wear-resistant coating 8a is provided corresponding to the cap insertion region Rc, so that early wear near the opening on the inner peripheral surface of the mold 1 can be prevented. Furthermore, the reason that the surface roughness of the abrasion-resistant film 8a is small with respect to releasing film 8b, because the wear of the cap 2 and 4 is also suppressed, it is possible to promote the reuse of the cap 2 and 4 Become. Thereafter, as shown in FIG. 1A, the polyurethane foam-forming material 5 is injected from an injection portion (not shown) provided in the cap 2.

  Subsequently, as shown in FIG.1 (b), it is made to foam by heating to a temperature range of 15-80 degreeC normally, Preferably it is 20-65 degreeC. Further, the expansion of the foam forming material 5 is advanced to fill the inside of the mold 1 with the foam 6. Thereafter, curing is performed at a temperature of about 70 to 120 ° C., for example.

  After the molding, the cap 4 is removed and the foamed product is taken out from the mold 1. Here, since the releasable coating 8b is provided corresponding to the foaming region Rb, the molded product can be easily taken out. Thereafter, the desired foam roller 7 shown in FIG. 1 (d) is obtained by cutting to a desired dimension as required.

  In the OA roller molding method of the present invention, as the foam-forming material, a material containing a polyol component, a polyisocyanate component, a foaming agent and optionally used conductivity imparting agent, catalyst, foam stabilizer, etc. is used. Is done. In the polyurethane foam-forming material, the polyol component and the polyisocyanate component may be contained in the form of a prepolymer obtained by reacting them.

  There is no restriction | limiting in particular as a polyol component used for manufacture of a polyol or a prepolymer, Polyether polyol, polyester polyol, hydrophobic polyol, etc. can be mentioned. Here, as the polyether polyol, polyols such as polyols obtained by addition polymerization of ethylene oxide or propylene oxide to glycerin or the like, polytetramethylene glycol, ethylene glycol, propanediol, butanediol and the like are preferably used. Polyester polyols include condensed polyester polyols obtained by condensation of dicarboxylic acids with diols and triols, lactone polyester polyols obtained by ring-opening polymerization of lactones based on diols and triols, and polyether polyols with lactone ends. A polyol such as an ester-modified polyol modified with an ester is preferably used. As the hydrophobic polyol, polyisoprene polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, or the like is used. These polyol components may be used alone or in combination of two or more.

  On the other hand, polyisocyanate components used for the production of polyisocyanates or prepolymers include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate; Diisocyanate; polyisocyanates having no unsaturated bond such as hexamethylene diisocyanate, and their modified products by isocyanurate, carbodiimide, glycol, and the like. These polyisocyanate components may be used singly or in combination of two or more.

  As the foaming agent, a physical foaming agent generally having a boiling point in the range of 20 to 60 ° C. is preferably used in consideration of ease of handling in the manufacturing process, easiness of vaporization and foaming. When this foaming agent is used as a raw material for polyurethane foam, the foaming agent alone has a low viscosity, and it is difficult to obtain a stable flow rate with a foaming machine. It is advantageous. Examples of such foaming agents include n-pentane, isopentane, cyclopentane, methylene chloride, Freon 134a (1,1,1,2-tetrafluoroethane), Freon 245fa (1,1,1,3,3- Pentafluoropropane), Freon 365mfc (1,1,1,3,3-pentafluorobutane), Freon 356, Freon 141b (1,1-dichloro-1-fluoroethane), Freon 142b (1-chloro-1, 1-difluoroethane), Freon 22 (chlorodifluoromethane), water and the like. These may be used alone or in combination of two or more.

  Next, in the foam-forming material of the present invention, examples of the conductivity imparting agent used as desired include carbon black and ionic conductive agents. Examples of carbon black include gas black such as electrified black, ketjen black, and acetylene black, oil furnace black including ink black, thermal black, channel black, and lamp black. Examples of ionic conductive agents include dodecyltrimethylammonium such as tetraethylammonium, tetrabutylammonium, and lauryltrimethylammonium, octadecyltrimethylammonium such as stearyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified aliphatic dimethylethylammonium. Ammonium salts such as chlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkyl sulfate, carboxylate, sulfonate; lithium, sodium, calcium, Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfo of alkali metal or alkaline earth metal such as magnesium Such as salts, and the like.

  These conductivity-imparting agents may be used singly or in combination of two or more. Further, the blending amount is not particularly limited and is appropriately selected depending on various situations. Usually, it is 0.1 to 40 parts by weight, preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the polymer material It is blended at a ratio of Moreover, filler-type conductive agents, such as a metal powder and a metal oxide powder, can be added with said carbon black and an ionic conductive agent. Further, in the polyurethane foam-forming material, the catalyst used as desired includes, for example, organometallic catalysts such as dibutyltin dilaurate, dibutyltin diacetate, stannous octoate, dibutyltin marker butylide, dibutyltin thiocarboxylate, dibutyltin dimaleate. Neat, dioctyltin marker butyl, dioctyltin thiocarboxylate, phenylmercury, silver propionate, tin octenoate, amine-catalyzed triethylamine, N, N, N'N'-tetramethylethylenediamine, triethylenediamine, N-methylmorpholine , Dimethylaminoethanol, bis (2-dimethylaminoethyl) ether, 1,8-diazabicyclo (5,4,0) -undecene-7, and the like are preferably used. These catalysts may be used alone or in combination of two or more.

Furthermore, examples of the foam stabilizer used in the foam-forming material as desired include polyether silicone oil, nonionic surfactants, ionic surfactants, and the like. A combination of the above may also be used.
In the OA roller manufacturing method of the present invention, the foam-forming material is foam-cured in a cylindrical mold to manufacture a roller having a shaft and a polyurethane foam layer provided on the outer periphery thereof.

  A polyurethane foam roller was produced by the procedure shown in FIG. 1 using a polyurethane foam-forming material prepared according to the following. That is, after opening the one end side opening of the stainless steel cylindrical mold 1 having an inner diameter of 18 mm and a length of 250 mm with the cap 2, the iron shaft 3 having a diameter of 6 mm and a length of 260 mm is arranged at the center, and then the mold The cap 4 was fitted into the other opening of 1. In addition, the coating film by the specification shown in Table 1 was provided in the inner peripheral surface of the metal mold | die 1, and it used for shaping | molding.

And the following polyurethane foam forming material 5 was inject | poured from the injection | pouring part provided in the cap 2. As shown in FIG. The foam-forming material immediately started to expand and expanded, and the mold was filled with the foam in about 90 seconds at a temperature of about 25 ° C. Thereafter, curing was performed at 90 ° C. for 20 minutes, and then the cap 4 was removed from the mold 1 and the foam roller was taken out of the mold.
・ Polyether polyol having an average molecular weight of 5000 and 3 functional groups: 70 parts by mass ・ Styrene graft type polymer polyol: 30 parts by mass ・ Triethylenediamine: 0.3 part by mass ・ N-methylmorpholine: 0.2 part by mass 1.5 parts by mass of water, 1.5 parts by mass of a silicone foam stabilizer, and an isocyanate having a ratio of TDI-80 / polymeric MDI of 50/50: index 105

  The workability at the time of taking out the forming roll from the mold 1 through the above manufacturing process was evaluated. Furthermore, while evaluating the surface property of the obtained forming roll, durability evaluation was performed about the cap insertion area | region of the metal mold | die 1 by the frequency | count that the urethane sticking which is a film lifetime expresses. The results are also shown in Table 1.

It is process drawing explaining the manufacturing method of the OA roller of this invention. It is a figure which shows the structure of the metal mold | die used by this invention.

1 Mold 2 Cap 3 Shaft 4 Cap 5 Foam Forming Material 6 Foam 7 Foam Roller 8a Abrasion Resistant Coating 8b Releasable Coating Rc Cap Insertion Area Rb Foaming Area

Claims (2)

A foam is formed around a shaft previously placed in the mold by injecting a foam-forming material into a mold in which a cap is inserted into each end opening of the cylindrical mold and the inside is sealed, and foam-cured. The mold used when forming an OA roller by forming a layer, and the ten-point average roughness of the surface is 3 or more in the cap insertion region where the cap contacts each other on the inner peripheral surface of the mold and 5 have a wear resistant coating is less, and the bubble-generating region sandwiched between both the cap insertion region, ten-point average roughness of the surface have a releasing film is 10 or more,
An OA roller molding die characterized in that a boundary between the wear-resistant coating and the release coating is between a bottom surface of a cap inserted into the die and an end of a use area of the OA roller. A foam-forming material is injected into a mold in which a cap is inserted into each opening at both ends of a cylindrical mold and the inside is sealed, foamed and cured, and then foamed around a shaft previously placed in the mold. A method for forming an OA roller, wherein the mold according to claim 1 is used in forming an OA roller by forming a body layer.

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