JPH05329855A - Mold device and manufacture of foam for roller - Google Patents

Abstract

PURPOSE:To provide a manufacture of a foam for a roller, which provides an inexpensive mold device by simple structure and can manufacture easily respectively the foam having a smooth skin on the surface and also a roller having the thin diameter. CONSTITUTION:This mold device is provided with a cylindrical mold 1 having both open ends and lid molds 2, 3 fitting into both the ends of the cylindrical mold 1, through holes 4, 5 are formed in the centers of the lid molds 2, 3 and the one side through hole 4 and the other side through hole 5 are made respectively into a raw material casting hole and an insertion hole of a roller shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive material used for electrostatically controlling an object such as a toner carrying roller, a charging roller, a transfer roller and a cleaning roller in a printer for electrophotography, electrostatic recording and the like. The present invention relates to a mold device for a foam for a roller used for a roller and a method for manufacturing the foam for a roller.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic process in which toner prepared in a toner cartridge is supplied to a photosensitive member on which an electrostatic latent image is formed and transferred and fixed on a sheet is generally charged, exposed to light and developed. It consists of transfer, fixing, and static elimination mechanisms, and each mechanism uses various rollers for precise control of static electricity. In recent years, the required characteristics of the roller material have become more and more severe. In particular, the rollers used in the developing mechanism including the rollers for toner transport, the charging roller, the transfer roller, and the rollers used in the cleaning mechanism electrostatically control non-contact objects, so that the material forming the rollers is non-conductive. Narrow range of charging level (1 digit at 5 ° C to 45 ° C, for example, 1 × 10 ⁹ Ω · cm to 1 × 10 ¹⁰ Ω
・ It is required to be controlled within the range of cm. In addition, these rollers are made of a conductive elastic body for the purpose of not damaging the other party by contact with precision parts such as a photosensitive drum, or increasing the contact area of the roller for accurate grip performance. In particular, the use of foam has been studied because it can reduce the compression hardness.
However, a roller made of foam generally sets the shaft on a block-shaped foam and grinds the surface of the roller to form a shape, so that the surface of the final product becomes porous and microscopic like a charging roller. When it was necessary to control static electricity in a large area, there was a problem with the roughness of the cells of the foam exposed on the surface. In order to solve such a problem, the prior art is Japanese Patent Laid-Open No. 61-150370.
In Japanese Patent Laid-Open No. 2003-242242, a shaft is arranged at the center of a cylindrical molding die, and a mixture of a polyol, an isocyanate, a foam material and the like is injected around the shaft and then foamed to simultaneously mold a leather-like skin and an elastic foam. It has been proposed to use the technique of integral skin foam. As another solution, there are proposed a method of coating a roller having a porous surface, a method of producing a roller having a porous surface and then covering it with a tubular surface layer, and a method of covering with a shrink tube. There is.

[0003]

The structure of the conventional foam mold apparatus for the roller is complicated and expensive. Also,
It was difficult to clean the injection gate after molding, and the injection port could not be removed with a roller having a small diameter, or even if the injection port was removed, the injection resistance was high due to the narrow hole, and molding defects were likely to occur. Further, in the manufacturing method using the technique of integral skin foam, the boundary of the skin on the surface with the internal foam part is not clear, and in a roller for a printer with a small roller diameter, in order to obtain a particularly desired roller surface. In addition, the entire body was in a high-density skin state, and the effect of decreasing the hardness described above could not be expected. In addition, such integral skin foam technology injects a liquid foaming mixture into the mold to foam and form a skin at the mold temperature and mold pressure, so the sealing property of the mold with the shaft set However, there are many defective products because the production technology is difficult, and in the case of vertical foaming to prevent air entrapment, there is a density difference (altitude difference) between top and bottom. was there. In addition, the method of coating on a porous surface has the disadvantage that the surface unevenness finally remains and the desired smoothness cannot be obtained. Furthermore, in the method of covering the tube, in addition to the complexity of creating a tube having a diameter that matches the roller diameter, the cost increases due to an increase in the steps of coating and bonding, and a tubular material that does not impair the hardness of the foam. It was difficult to select the material and thickness of the.

Therefore, the present invention provides a mold apparatus which has a simple structure and is inexpensive, can easily clean an injection gate after molding, and can easily manufacture a foam for a roller having a thin film having a smooth surface. In addition, the present invention provides a method for producing a foam for a roller, which has a smooth surface and a low hardness, and a surface smooth thin film that adheres to a non-contact part in a micro area and enables electrostatic control over a long period of time. With the goal.

[0005]

In order to achieve the above object, a mold apparatus according to the present invention comprises a cylindrical mold having openings at both ends and a lid mold fitted to both ends of the cylindrical mold. A through hole is formed in the center of the lid mold, one through hole is used as a raw material injection hole, and the other through hole is used as a shaft insertion hole for the roller. Further, according to the manufacturing method of the present invention, a lid mold is fitted to both ends of a cylindrical mold having openings at both ends, and a shaft of a roller is inserted through a through hole of one lid mold so that a tip of the other mold is opened. Positioning near the mold, injecting the raw material from the through hole of the other lid mold, projecting the tip of the shaft from the through hole of the other lid mold to the outside after injecting the raw material, foaming of the raw material After molding, after removing both lid molds from the cylindrical mold, the foam molded around the shaft is extracted from the cylindrical mold together with the shaft.

[0006]

The mold apparatus of the present invention has an extremely simple structure and can be provided at a low cost, and at the same time, the shaft is inserted during molding for cleaning the injection gate after molding, that is, the through hole of the other lid mold. This makes it extremely easy. Further, even a roller having a small diameter can be easily manufactured because it serves as a raw material inlet having a shaft thickness. Further, according to the production method of the present invention, the roller foam having a smooth surface, a low hardness, a thin film having a smooth surface which enables electrostatic control over a long period of time by closely adhering to a non-contact part in a micro area. Can be easily manufactured.

[0007]

Embodiments of the present invention will be described below. In FIG. 1, a cylindrical mold 1 having openings at both ends and lid molds 2 and 3 fitted to both ends of the cylindrical mold 1 are provided, and through holes 4 and 5 are provided at the centers of the lid molds 2 and 3. One through hole 4 is formed as a raw material injection hole, and the other through hole 5 is formed as an insertion hole for the shaft 6 of the roller. The lid molds 2 and 3 have a large-diameter portion A larger than the inner diameter of the cylindrical mold 1 and a small-diameter portion B fitted to the inner diameter of the cylindrical mold 1.
Have and. The small-diameter portion B is fitted into both end openings of the cylindrical mold 1, the shaft 6 of the roller is inserted through the through hole 5 as shown in FIG. 2, and the tip of the shaft 6 is positioned near the other cover mold 2. In the state shown in FIG. 2, the nozzle 7 for injecting the raw material is inserted into the through hole 4 to inject the raw material into the cylindrical mold 1. If a certain amount of raw material is injected into the cylindrical mold 1,
The nozzle 7 is pulled out from the through hole 4, and the tip of the shaft 6 is inserted into the through hole 4 to project the tip to the outside as shown in FIG. Therefore, the through holes 4 and 5 of the lid molds 2 and 3 serve as shaft holding holes, respectively.

When the raw material is hardened in the cylindrical mold 1 in the state shown in FIG. 3, the both lid molds 2 and 3 are removed from the cylindrical mold 1 as shown in FIG. In this state, the foam 8 around the shaft 6
Thus, a skin layer is formed on the surface in contact with the cylindrical mold 1. Next, as shown in FIG. 5, the finished product is extruded from one side of the cylindrical mold 1 to remove the product. The thus molded product is shown in FIG.
A foam 8 for a roller having a shaft 6 as shown in FIG.

As a raw material to be injected, first, a mixture containing a compound containing two or more active hydrogens, a compound containing two or more isocyanate groups and a catalyst is bubbled by mechanical stirring, and the resulting foam is cylindrically shaped. Through-hole 4 in the metal mold 1
From the nozzle 7 Here, the compound containing two or more active hydrogens (polyhydroxyl compound) is a polyol used in the production of general flexible polyurethane foams and urethane elastomers, that is, polyether polyols having terminal hydroxyl groups, polyester polyols, and both. In addition to the polyether polyester polyol which is a copolymer, general polyols such as so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in the polyol can be used. Further, as the compound having two or more isocyanate groups (polyisocyanate compound), polyisocyanate which is similarly used in the production of general flexible polyurethane foams and urethane elastomers can be used.
That is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI, alicyclic polyisocyanate having 2 to 18 carbon atoms, aromatic polyisocyanate having 8 to 15 carbon atoms and these poly A mixture or modified product of isocyanate, such as a prepolymer obtained by partially reacting with a polyol, is used. These can be used in usual amounts. As the catalyst, amine-based catalysts and organometallic catalysts used in general polyurethane foam production can be used, but unfavorable thickening etc. occur within the working time until they are pressed into the mold after foaming by mechanical stirring. 1,8-diazabicyclo [5.
4.0] Undecene-7 aromatic sulfonate and the like are used as delaying catalysts, and especially 1,8-diazabicyclo [5.4.0] undecene-7 (DBU) aromatic sulfonate and organic It is recommended to use it in combination with a metal catalyst. Thus, by using both catalysts in combination, stabilization of pot life and quickness of heat curing can be achieved at the same time. In this case, when the aromatic sulfonic acid salt of DBU is used alone, it may not be possible to obtain a foam having poor heat-curing properties and good physical properties. On the other hand, when the organometallic catalyst is used alone, , Pot life may be shortened. Examples of the aromatic sulfonic acid that forms a salt with DBU include benzene sulfonic acid having a benzene nucleus such as benzene sulfonic acid, toluene sulfonic acid, and xylene sulfonic acid, and sulfone having a naphthalene skeleton such as propylnaphthalene sulfonic acid. Examples thereof include acids, and they can also be used in the form of aromatic sulfonic acid esters such as methyl toluene sulfonate. On the other hand, as the organometallic catalyst, an organotin compound is particularly preferably used. The preferred organotin compound is tin (II), a carboxylic acid.
Salts such as tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate, tin (II) laurate, etc., and tin (IV) compounds such as dibutyltin oxide, dibutyltin dioxide. , Dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dioctyltin diacetate and the like. The amount of the DBU used with the aromatic sulfonic acid and the organometallic catalyst is appropriately selected, but to 100 parts (parts by weight, the same applies hereinafter) of a compound containing two or more active hydrogens, the aromatic sulfonic acid of DBU Is 0.1
It is preferably 5 parts, particularly 0.1 to 1 part, and 0.0001 to 1 part, particularly 0.001 to 0.2, for the organometallic catalyst.
It is preferable to set it as a part. The combined ratio of the DBU aromatic sulfonate and the organometallic catalyst is 1: 100 to 500.
It is preferably set to 00: 1, particularly 1: 2 to 1000: 1. Further, if necessary, a silicone-based foam stabilizer, a flame retardant, an organic filler, an inorganic filler, a pigment, a plasticizer, and an auxiliary foaming agent such as chlorofluorocarbon or methylene chloride, which are used in ordinary polyurethane foam, can be added. ..

As the cylindrical mold 1 and the lid molds 2 and 3,
Metal materials such as iron and aluminum are preferable, and the lid molds 2 and 3 are
It can also be formed of a synthetic resin material. An air vent is preferably provided on the opposite side of the through hole 4 serving as the material injection port.

Next, a description will be given of a production example. As a compound containing two or more active hydrogens, propylene oxide and ethylene oxide are added to glycerin to give a molecular weight of 50.
100 parts of polyether polyol (ex Asenol 828, Asahi Glass Co., Ltd.), 7.5 parts of 1,4-butanediol (manufactured by Toyo Soda Co., Ltd.), and urethane-modified MDI (Sumitomo Bayern Co., Ltd.) as a compound having two or more isocyanate groups. Manufactured by Sumidur PF) 50 parts, silicon-based surfactant (manufactured by Nippon Unicar Co., SZ1618) 1.5
Part, as a catalyst 1.8-diazabicyclo [5.4.0]
0.5 parts of toluene sulfonate of undecene-7 and 0.0015 part of dibutyltin dilaurate, and 50 parts of natural graphite (high-purity graphite AOP manufactured by Nippon Graphite Co., Ltd.) having an average particle size of 2.5 μm and a fixed carbon content of 99%. MO
Foaming was carried out by a foaming and pouring machine manufactured by NDOMIX Co., and the foamed body was injected into the mold apparatus shown in FIGS. 1 and 2 from the nozzle 7 to form a cylindrical roller. Set the inner diameter of the cylindrical mold 1 to 1
6 mm, the length was 23 cm, and the shaft 6 had a diameter of 8 mm and a length of 25 cm. By press-fitting the foam into the mold device, the air in the mold device is smoothly replaced with the foam, and after filling the mold with the foam, the foam is heated at 80 ° C. × 1.
By curing in 0 minutes, an elongated cylindrical body having void-free fine cells could be molded with a smooth skin on the surface.

[0012]

As described above, the mold device of the present invention has a simple structure and can be provided at a low cost, and furthermore, a foam for a roller can be easily manufactured, and a foam having a smooth surface is formed. I got a body. Further, according to the manufacturing method of the present invention, a roller foam having a smooth skin on the surface can be easily manufactured. In addition, since the tip of the shaft is inserted when the raw material is cured, the through hole that serves as the raw material injection port also makes it easier to clean the through hole after molding. Therefore, it can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a perspective view of a mold apparatus according to the present invention before assembly.

FIG. 2 is a perspective view showing a state in which a mold device is assembled, a shaft is inserted, and a nozzle is inserted.

FIG. 3 is a perspective view showing a state in which after the raw material is injected from the nozzle into the mold apparatus, the nozzle is retracted and the tip of the shaft is inserted into the hole of the raw material injection port.

FIG. 4 is a perspective view illustrating a state where the lid mold is removed after the raw material is cured.

FIG. 5 is a perspective view showing a step of extracting a product from a cylindrical mold.

FIG. 6 is a perspective view showing a manufactured product.

[Explanation of symbols]

 1 Cylindrical mold 2,3 Lid mold 4,5 Through hole 6 Shaft 8 Foam

Claims (2)

[Claims] 1. A cylindrical mold having openings at both ends and a lid mold fitted to both ends of the cylindrical mold are provided, a through hole is formed at the center of the lid mold, and one through hole is filled with raw material. A mold device for a foam body for a roller, which has a hole, and the other through hole is a shaft insertion hole of the roller. 2. A lid mold is fitted to both ends of a cylindrical mold having openings at both ends, and a shaft of a roller is inserted through a through hole of one of the molds so that the tip is located near the other mold. Process, the process of injecting the raw material from the through hole of the other lid mold, the process of projecting the tip of the shaft from the through hole of the other lid mold to the outside after injecting the raw material, A method of manufacturing a foam for a roller, which comprises a step of removing the foam molded around the shaft from the cylindrical mold together with the shaft after removing the mold from the cylindrical mold.