JPH0444825A - Preparation of rubber-plastic composite cylindrical body - Google Patents

Abstract

PURPOSE:To make simultaneous extrusion molding and vulcanization possible by a method wherein a rubber and a plastic are simultaneously extrusion-molded in a long land die in such a way that the outer periphery of a plastic cylindrical body is covered concentrically with an unvulcanized rubber and this molded body is forwarded while it is brought into contact with an inner wall provided with a lubricating agent and the rubber which is the outer layer of the molded body is vulcanized in a heating and vulcanization zone. CONSTITUTION:Extrusion is performed in a long land die 4 by means of an inner layer extruder 1, an outer layer extruder 2 and a co-extrusion head 3 in such a way that the outer periphery of a plastic cylindrical body is covered concentrically with a vulcanizable rubber. This composite cylindrical body is forwarded while it is brought into contact with the inner wall of the heating and vulcanization zone 5 of the long land die 4 through an extremely thin film of an lubricating agent fed by means of a lubricating agent-feeding apparatus 7. The heating and vulcanization zone of the long land die is usually heated at a vulcanization temp. of 150-200 deg.C by energizing a direct electric current. The rubber on the outer layer of the composite cylindrical body is vulcanized by this heat while it is forwarded in the zone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used, for example, for platen tools such as impact-type plinks, feeding tools for office automation equipment, and the like. The present invention relates to a method for manufacturing a rubber/plastic composite cylinder in which the outer periphery of a plastic cylinder is coated with vulcanized rubber.

(Conventional technology) As a platen tool for impact flea printers and typewriters, a rubber/plastic composite tool is used in which vulcanized rubber or thermoplastic elastomer is added to the outer periphery of a roll of plastic with high mechanical strength such as polyamide or polyoxymethylene. The inventor of the present application has separately proposed a method for reducing noise during printing.

When the elastomer covering the outer periphery of the plastic rule is made of thermoplastic elastomer.

It is possible to use an integral type in which the plastic seal and the elastomer coating on its outer periphery are co-extruded, but if the elastomer coating is made of vulcanized rubber, which has superior printing durability, high temperature heating during vulcanization of the Gore A coating is necessary. Because of this, the plastic is melted and softened to form a solid shape.
1. Co-extrusion molding of the kotaro roll and the rubber coating around its outer periphery,
Until now, the only option was to manufacture the plastic ball and the vulcanized rubber tube separately, and then press-fit the plastic ball into the vulcanized rubber tube and assemble it.

(Problem to be Solved by the Invention) In the future, demand for rubber and plastic composite cylinders in which the outer periphery of a plastic cylinder is coated with vulcanized rubber will increase in the above-mentioned braten tools and paper feeders for OA equipment. However, because plastic cylinders are deformed by high-temperature heating during rubber vulcanization, until now it has not been possible to effectively manufacture such rubber and plastic composite cylinders by co-extrusion and vulcanization. I couldn't do it.

From these points of view, the present invention provides an efficient manufacturing method that enables simultaneous extrusion molding and vulcanization of rubber and plastic composite cylinders, as well as rubber and plastic composite cylinders with excellent roundness and straightness. This paper proposes a manufacturing method that enables production.

(Measures for solving HIM) The production of the rubber/plastic composite cylindrical body of the present invention is carried out by placing the rubber and plastic in a long land die so that the outer periphery of the plastic cylindrical body is coated with unvulcanized rubber concentrically. The molded product is co-extruded into a four-grand die while being brought into contact with the lubricated inner wall of the long-land die, and the rubber of the outer layer of the molded product is vulcanized in the heated vulcanization zone of the die. It is characterized by:

The manufacturing method of the present invention will be explained in detail! ! FIG. 1 is an explanatory diagram illustrating a manufacturing apparatus for implementing the manufacturing method of the present invention, in which 1 is an inner layer extruder for extruding back plastic, 2 is an outer layer extruder for extruding unvulcanized rubber, and 3 1 is a coextrusion head that simultaneously extrudes plastic and rubber produced by extruders 1 and 2 so that the outer periphery of a cylindrical plastic body is coated with rubber concentrically. Such an extruder and coextrusion head are well known and are used in, for example, simultaneous extrusion molding of two-layer coatings of electric wires, and the present invention also uses such five known extruders and coextrusion heads. be able to. Reference numeral 4 denotes a long land die having a constant inner diameter, and includes a heating vulcanization zone 5 and a cooling zone 6, which are thermally insulated from each other. 7 is a lubricant supply device installed at the entrance of the long land die, which supplies lubricant in an amount sufficient to form an extremely thin film of lubricant on the inner wall of the long land die. A thin layer of lubricant H is formed at the interface between the composite cylinder and the outer surface of the composite cylinder extruded from the coextrusion head. 8 indicates the rubber and plastic composite cylindrical body 10 exiting from the outlet of the cooling zone 6 of the long land die 4 as indicated by arrow A.
This device is a rotating caterpillar device that can rotate in the direction of arrow B so as to slowly rotate the composite cylindrical body traveling in the Langland die in the circumferential direction at a constant speed. It is preferable that there be. 9 is a sizing cutting machine that cuts the rubber/plastic composite cylindrical body to a certain length.

As described above, the composite material is extruded from the inner layer extruder 1, the outer layer extruder 2, and the coextrusion head 31C into the ground die 4 so that the outer periphery of the plastic cylinder is coated with vulcanizable rubber concentrically. The cylindrical body advances while passing over the inner wall of the heated vulcanization seam 75 of the long land die 4 through an extremely thin film of lubricant supplied by the lubricant supply device 7. Examples of the lubricant that can be used include poly-1-thyl synthetic oil (for example, Nissan Uniloop, manufactured by NOF@), silicone oil (for example, dimethyl silicone oil, manufactured by Toshiba Silicon ■), and the like.

The heating vulcanization zone of the long land die is heated to a vulcanization temperature of usually 150 to 200°C by applying direct current electricity, etc.
This heat heats up the rubber of the outer layer of the composite cylinder as it travels through the zone.

Since the rubber/plastic composite cylinder is heated and vulcanized while being restrained by a long land die, it will not be deformed even by high-temperature heating during vulcanization, as described later, and the composite cylinder will have a thin lubricant film. Because it is in contact with the inner wall of the heating vulcanization zone of the long land die, the heat transfer efficiency is good.The length of the heating vulcanization zone is usually set to 1 to 10 m, and the composite cylinder moves within the long land. The speed depends on the vulcanization speed of the rubber, the heating temperature of the heating vulcanization zone, and the length of 8I.
It can be selected as appropriate depending on C.

The composite cylinder with the outer rubber layer vulcanized enters the cooling zone of the long land die and is cooled.

The cooling zone may be air-cooled or water-cooled as appropriate; - The rubber-plastic composite leaving the ground die is taken up by a caterpillar machine; in a more preferred embodiment 11 of the invention, the rubber-plastic composite is taken up by a caterpillar machine in the direction of arrow B of the rotary caterpillar machine. (FIG. 1) causes the composite cylinder to rotate in its circumferential direction during one run of the grand die. The rotational speed is selected to be such that the beam rotates at least once per length of product cut to size, usually 2 to 5 times, in the fugland die.

This rotation further improves the roundness and straightness of the rubber/plastic composite cylinder.

FIGS. 2 and 3 are perspective views showing the end portion of the composite cylindrical body manufactured as described above with the steps peeled off. 11 is a plastic cylindrical body, and 12 is a vulcanized rubber coating on the outer periphery thereof.

When the cylindrical body 11 is a tubular cylindrical body having a hollow part 13 in the center as shown in FIG. Then, the rubber is vulcanized, cut to size, and the six bodies are pulled out.

The plastic constituting the cylindrical body may be any plastic that can be extruded, and may include polyethylene and its copolymer resin, crosslinked polyethylene (in this case, it is crosslinked in the heat vulcanization zone of the render land die), polybupylene, polystyrene. General-purpose plastics such as vinyl chloride and copolymer resins thereof, vinyl chloride and copolymer resins thereof can be used, but in the case of the platen rolls described above, polyamides, polyoxymethylene, modified polyphenylene resins, etc., which have high mechanical strength, can be used. Suid.

So-called engineering plastics such as polycarbonate, polyethylene terephthalate, polyethylene terephthalate, and polyphenylene sulfide are preferred.These plastics can be used alone or mixed with other plastics or rubber as modifiers, or reinforced with glass fiber or the like. Fill with agent and use.

The vulcanized rubber used to cover the outer periphery of the plastic cylinder may include natural rubber, imprene rubber, butadiene rubber, styrene-butadiene rubber, coolprene rubber, etc. alone or in combination with other rubbers or plastics.
IoJiR material is used.

(Function) In the present invention, plastic and rubber are simultaneously extruded into a long land die so that the outer periphery of a plastic cylindrical body is coated with rubber concentrically, and the extruded molded body is coated with lubricant from the long land die. The outer rubber coating layer of the composite cylindrical body is vulcanized in the heat vulcanization zone of the long gland die while being in contact with the inner wall C, so that the rubber-plastic composite cylindrical body is It is in a state of being restrained by a long land die. In order to deform in such a restrained state, it is necessary to push away the surrounding molten plastic or rubber and move the surrounding plastic to another location in the restraint space, so restraint 9 Deformation is unlikely to occur in the middle. Moreover, in the heating and vulcanization zone, the viscosity of the rubber rapidly increases due to gelation, making it difficult to flow, thereby further promoting the confined space effect. According to the invention, therefore:
Not only does the co-extruded rubber and plastic composite cylindrical body not deform when the rubber is vulcanized, but the molding and vulcanization are completed while being restrained by the inner wall of the long land die, so the resulting rubber , the plastic ivy composite has excellent roundness and straightness.

Furthermore, since lubricant is supplied to the inner wall of the long land die, the molded composite cylindrical body moves smoothly inside the long land die, and the surface of the outer rubber coating layer does not seize.

Furthermore, in the present invention, when the rubber and plastic mating cylindrical body is rotated gently (at a constant speed) in the round direction during one grand die, the roundness of the composite cylindrical body is improved by this rotation. The straightness is further improved, and a rubber-plastic composite cylindrical body having a high degree of roundness and straightness is obtained.

(11) Using the manufacturing equipment as explained in Fig. 1, rubber,
Plastic composite cylinders were coextruded and vulcanized using the materials shown in Table IF. In Examples 3 and 4, the opening caterpillar device was rotated to rotate the composite cylindrical body in its circumferential direction in the Fugland die. The inner diameter of the a grand die is 31. Qm, ρ The length of the heating vulcanization zone of the ground die is 15m, and the length of the cooling zone is lo
It was w. The heating and vulcanization zone was heated by direct current flow. The cooling zone was Daisha water cooled. - S* and viscosity of the lubricant supplied to the inner wall of the ground die (20℃
), the heating temperature of the heating and vulcanization zone, the extrusion speed of the composite cylinder O (-the execution speed during the Fugland die), the circumferential rotational speed of the composite cylinder, the dimensions of the obtained composite cylinder (plastic cylinder The outer diameter of the rubber-coated layer, the outer diameter of the rubber-covered layer), the roundness and straightness of the product cut to a length of 50 mm were as shown in the decline 1F, respectively.

To measure circularity, the diameters of any cross section in all directions are measured using a laser beam outer diameter measurement wj, and the difference between the maximum and minimum values is defined as circularity.

Straightness was measured by placing a 320-length beam on two v-boot stalls with a span of 300 m, and using a laser beam displacement measuring machine to measure the position of the top of the center of the span when rotating. Measure the NR high value - lowest value l and get true 1
degree.

(Effects of the Invention) As described above, according to the present invention, a composite cylinder having a vulcanized rubber coating on the outer periphery of a plastic cylinder can be integrally formed by coextrusion molding and vulcanization B]*! This makes it possible to streamline the production of rubber and plastic composite cylindrical bodies. Moreover,
II composite cylinder is the above-mentioned 1! As is clear from the koji examples, it has a degree of roundness and straightness. The aforementioned platen roll precept is OAI! In applications such as dexterity assembly tools, roundness and straightness are very important qualities.The first rubber-plastic composite cylinder obtained by the present invention can be obtained by co-extrusion molding, Since they are integrally molded by vulcanization, the anchoring effect of the upward movement of the plus-f ivy cylinder and the vulcanized rubber covering layer creates a strong bond between the two, allowing the two layers to separate and peel (7 times apart).

Furthermore, according to the manufacturing method of the present invention, compared to the conventional case where a plastic cylindrical body and a vulcanized rubber tube body are manufactured separately and then press-fitted together, the equipment becomes simpler and equipment costs are reduced.
Another advantage is that the installation space for equipment can be reduced.

[Brief explanation of the drawing]

Figure 11!1 is an explanatory diagram illustrating the manufacturing equipment for carrying out the manufacturing method of the present invention, and Figures 2 and 3 show the rubber and plastic composite cylindrical body obtained according to the present invention with its end section stripped in steps. It is a perspective view of a part of thing. 1: Inner layer extruder, 2: Outer layer extruder, 3: Coextrusion head,
4: - ground die, 5: heat vulcanization zone, 6: cooling zone, 711 lubricant supply device, 8: take-up caterpillar device, 9: sizing cutting machine, 10: Rubber, plastic composite cylinder patented by Mitsubishi Electric Cable Industry Co., Ltd.

Claims (2)

[Claims] (1) Rubber and plastic are coextruded into a long land die so that the outer periphery of the plastic cylinder is coated with unvulcanized rubber concentrically, and the molded body is placed on the lubricated inner wall of the long land die. A method for producing a rubber/plastic composite cylindrical body, characterized in that the outer layer of the rubber of the molded body is heated and vulcanized in a heat vulcanization zone of the die by advancing through a long land die while making contact with the molded body. (2) A method for manufacturing a rubber/plastic composite cylindrical body, which comprises rotating the molded body progressing through a long land die in the circumferential direction of the manufacturing method according to claim (1).