JPH08197558A - Sheeting of silicone rubber sheet - Google Patents

Abstract

PURPOSE: To enable the sheeting of a silicone rubber sheet having a presentable appearance and free from improper thickness or insufficient breakdown strength and further, with a minimum incidence of poor air feed by scraping a refuse sticking to the surface of a roll which makes up a calender off the surface using a scraping fixture. CONSTITUTION: A rubber compound 27 is supplied to a clearance between a first roll 20 and a second roll 21. Next, a rolled rubber compound is further fed into a clearance between a third roll 22 and a fourth roll 23, and is applied under pressure to a PET film 29 mounted on the fourth roll 23 while the rubber compound is rolled. In addition, this laminate is peeled off the third roll 22 and formed into a sheet. In this case, a refuse sticking to the first roll 29 and the third roll 22 is scraped off these rolls using scraping fixtures 30, 31 arranged on the rolls. Thus, the clean surface of the rolls comes into contact with the rubber compound, and the scraped refuse 34, 35 drops onto receiving trays 32, 33. Thus, a sheet with a clean surface is obtained and the refuse is prevented from sticking to the roll surface again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dispensing a silicone rubber sheet, and more particularly to a method for dispensing a silicone rubber sheet using a calender whose roll surface is always clean.

[0002]

2. Description of the Related Art Calenders are widely used for processing various types of thermoplastic resins, rubbers, etc. In processing rubbers, thin threading (tailing), dispensing (sheeting),
It is used in each process such as molding (profiling), rubbing (frictioning), pressure bonding (topping), and bonding (doubling). As the structure of the calender, for example, a structure in which three or four rolls are vertically arranged (see FIGS. 1 and 2) and a structure in which four rolls are arranged in an inverted L shape (see FIG. 3) ), And a structure in which four rolls are arranged in a Z shape (see FIG. 4), and the like, and a structure according to the purpose is used.

As the rubber processed by such a calendar, there are natural rubber and synthetic rubbers such as SBR, NBR, chloroprene rubber, butyl rubber, ethylene propylene rubber, hypalon, fluororubber and silicone rubber. Among these rubbers, a silicone rubber composed of an organopolysiloxane having a unique skeleton is used in various applications because of its excellent electric insulation, weather resistance, heat resistance and cold resistance.

However, since the strength of the silicone rubber before curing (green strength) is weak, the silicone rubber sheet thinly divided by the calender stretches when peeled from the roll, so that the stretching is prevented. Then, it is pressed onto a polyethylene or polyethylene terephthalate (PET) film and peeled off from the roll (see FIG. 5).

Since the silicone rubber compound having improved thermal conductivity and electrical conductivity contains a large amount of coarse filler such as aluminum oxide powder, boron nitride powder, graphite powder and carbon black, the green strength is further lowered. . When such a compound having low green strength is rolled by a calender and formed into a sheet, the filler is separated by the applied shearing force and adheres to the surface of the calender roll. Therefore, when the sheet is rolled as it is, the adhered matter is transferred, and the appearance of the obtained sheet is remarkably inferior.

[0006] In particular, since such deposits collect in the rubber compound supply portion and the rubber bank portion and form a lump, projections are formed on the sheet or holes are formed, which causes a thickness defect and a withstand voltage defect. There was a flaw. Furthermore, in order to remove the air in the compound, it is necessary to send the rubber compound to the lower roll while rotating the rubber bank. In this case, since the roll with the adhered substance makes it difficult to rotate the rubber bank, it is not possible to sufficiently remove the air, and there is a drawback that an air defect occurs in the sheet.

[0007]

Therefore, the inventor of the present invention
As a result of diligent examination of the method of dispensing the silicone rubber sheet with a calendar in order to solve the above drawbacks,
By mechanically scraping off the deposits on the roll surface, it has been found that it is possible to obtain a silicone rubber sheet which has a good appearance, and is free from defects in thickness and withstand voltage and with little air defects. did. Therefore, it is an object of the present invention to provide a method for dispensing a silicone rubber sheet which has a good appearance, is free from defects in thickness and withstand voltage, and has low air defects.

[0008]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
In a method for dividing a silicone rubber sheet by rolling a silicone rubber compound by a calendar, the method for dividing a silicone rubber sheet is characterized in that the deposits on the surface of the roll constituting the calendar are scraped off by a scraping jig. Was done.

In the present invention, a scraping jig is arranged in the vicinity of the surface of the roll in order to scrape off the deposits on the surface of the roll constituting the calender. The jig is not particularly limited in its shape and material as long as it can come into contact with the surface of the roll and scrape off the attached matter,
From the viewpoint of not damaging the surface of the roll, it is preferable to use a material softer than the material used for the roll.

For example, when the material of the roll is cast iron, the material used for the jig should be a metal material such as aluminum, copper or brass, or a resin material such as nylon, polyurethane or tetrafluoropolyethylene. Is preferred. The position where the jig is attached is not particularly limited as long as it is a place that does not hinder the calendering process and the scraped deposits fall. Examples of the position of the jig include the position shown in FIG.

In the present invention, it is preferable to provide a tray for accumulating the deposits scraped by the jig.
The shape and material of the tray are not particularly limited as long as it can deposit the scraped deposits, but it is easy to check the surface condition of the sheet, the rubber bank condition, etc. Therefore, it is preferable to use a transparent material.

Examples of the transparent material include transparent resin materials such as polycarbonate, acrylic resin and vinyl chloride. It is preferable that the tray has a shape capable of accumulating the adhering material to some extent and preventing the adhering material received from being re-adhered to the sheet. The tray is arranged at a position where the adhered matter scraped by the jig falls, and receives the adhered matter that falls. Therefore, for example, it is arranged at the position shown in FIG.

The silicone rubber compound used in the present invention may be appropriately selected from known silicone rubber compounds composed of an organopolysiloxane, a filler and a curing agent. The degree of polymerization of the organopolysiloxane is preferably 3,000 or more, and particularly preferably 6,000 to 10,000 in terms of roll workability. The curing agent is an organic peroxide, or the organopolysiloxane is a silicon atom. When it has an alkenyl group bonded to, it is preferable to use a platinum catalyst and an organohydrogensiloxane having two or more hydrogen atoms bonded to silicon atoms. As the calender in the present invention, a known calender that roll-molds rubber into a sheet can be used.

Next, the present invention will be described in more detail with reference to the drawings. FIG. 6 is a schematic side view showing an example of the manufacturing method of the present invention. In the figure, reference numeral 20 is roll 1, 2
Reference numeral 1 is a second roll, 22 is a third roll, and 23 is a fourth roll, and these four rolls form an inverted L-shaped calender.

The rubber compound 27 is supplied between the first roll 20 and the second roll 21, and is supplied between the second roll 21 and the third roll 22 while being rolled between the rolls. At this time, the rubber bank 28 formed between the second roll 21 and the third roll 22 is degassed. Next, the rolled rubber compound is further supplied between the No. 3 roll 22 and the No. 4 roll 23, and is pressure-bonded onto the PET film 29 mounted on the No. 4 roll 23 while being rolled to make the No. 3 roll 22. Is peeled off and molded into a sheet.

In this case, the scraping jigs 30 and 31 arranged on the first roll 20 and the third roll 22 scrape off the adhering substances adhering to these rolls, and the clean roll surface hits the rubber compound while scraping. The deposits 34 and 35 that have been taken off fall into the saucers 32 and 3
Received by 3. Therefore, a sheet with a clean surface is always obtained, and reattachment of deposits is prevented. The silicone rubber sheet thus dispensed on the release film is cured by a known method such as passing through a heating furnace or once being wound and then put in a steam pot to form a sheet. .

[0017]

EFFECTS OF THE INVENTION According to the method for dispensing a silicone rubber sheet with a calendar of the present invention, a silicone rubber sheet having a good appearance, having no thickness and defective withstand voltage, and having few air defects can be obtained. Therefore, the silicone rubber sheet that has been dispensed by the dispensing method of the present invention and further cured is suitable for a sheet such as a heat dissipation sheet, an insulating sheet, a packing material, etc. having strict specifications for appearance, thickness, and electrical characteristics.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1. Methylvinylpolysiloxane 10 consisting of 99.85 mol% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units, the end of which is blocked with dimethylvinylsilyl groups and having an average weight of 8,000.
0 part by weight and 350 parts by weight of alumina (AL-43PC: trade name of Showa Denko KK) were added with a two-roll mill and kneaded to homogenize.

Obtained Silicone Rubber Compound 10
0.75 parts by weight of organic peroxide 2,4-dichlorobenzoyl peroxide was added to 0 parts by weight with a two-roll mill and kneaded well to prepare a curable silicone rubber compound. The obtained silicone rubber compound was molded into a sheet on a PET film by using the calendering device shown in FIG. 6, then cured in a heating oven at 150 ° C., and the PET film was peeled off to produce a silicone rubber sheet. . The appearance of the obtained sheet was visually inspected. As a result, the rate of pattern defects on the surface (there were deposits on the surface of the sheet) was 0.1% (1 sheet out of 1,000).

Comparative Example 2. A silicone rubber sheet was produced in exactly the same manner as in Example 1 except that the conventional calendering device shown in FIG. 5 was used instead of the calendering device used in Example 1, and the sheet of sheet was prepared in the same manner as in Example 1. When the appearance was inspected, the pattern defect rate on the surface was 5.2% (52 out of 1,000 sheets). The above results demonstrate the effectiveness of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic side view of a calendar in which three rolls are vertically arranged.

FIG. 2 is a schematic side view of a calendar in which four rolls are vertically arranged.

FIG. 3 is a schematic side view of a calendar in which four rolls are arranged in an inverted L shape.

FIG. 4 is a schematic side view of a calender in which four rolls are arranged in a Z shape.

FIG. 5 is a schematic side view of a conventional method for producing a silicone rubber sheet by a calendar.

FIG. 6 is a schematic side view of the method for producing a silicone rubber sheet of the present invention.

[Explanation of symbols]

 1 to 23 rolls 24 and 27 rubber compound 25 and 28 rubber bank 26 and 29 PET film 30 and 31 scraping jig 32 and 33 saucer 34 and 35 attached matter

Claims (2)

[Claims] 1. A method of dispensing a silicone rubber sheet, comprising rolling a silicone rubber compound with a calendar, wherein deposits on the surface of rolls constituting the calendar are scraped off by a scraping jig. Distributing method. 2. The method of dispensing a silicone rubber sheet according to claim 1, wherein the scraped deposits are deposited on a tray provided below the scraping jig.