JP2001262126A - Joint sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an NA joint sheet high in tensile strength, low in compressibility and good in flexibility. SOLUTION: This joint sheet is obtained by charging a blend material comprising a base fiber except asbestos, rubber, filler and rubber chemicals between a hot roll and a cold roll and then laminating a sheet-like material on the hot roll side. The content of the filler 5-15 μm in particle size in the final joint sheet is >=40 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a joint sheet used as a base material of a gasket used in a wide range of fields such as petrochemical plants, various industrial machinery, automobiles, and home appliances.

[0002]

2. Description of the Related Art A joint sheet is prepared by sufficiently mixing a base fiber, a filler and a rubber chemical with a rubber swollen in a solvent (or a mixture of powdered rubber or latex and a solvent) with a Henschel mixer or the like. A forming composition (hereinafter, abbreviated as a mixed material) is prepared, and then the mixed material is mixed with a hot roll (about 150 ° C.) and a cold roll (about 20 ° C.).
℃), the solvent is evaporated and vulcanized while laminating on the hot roll side, and the sheet having a predetermined thickness is peeled off from the hot roll. Have been.

[0003] Depending on the product, the sheet-like material obtained for vulcanization may be further subjected to secondary vulcanization in an autoclave or the like. In addition, depending on the application, a small amount of a softener, a plasticizer, a water swelling agent, an oil swelling agent, or the like may be added to the mixed material in a small amount, and a pigment may be blended from the viewpoint of storage and identification.

[0004] Conventionally, asbestos joint sheets using asbestos as a base fiber have been widely used, and the unique shape of asbestos,
Utilizing its excellent heat resistance, it was punched and used as a gasket for piping and equipment for water, oil, air, steam, and the like.

[0005] The asbestos joint sheet contains about 60 to 85% by weight of an inorganic material, which is very flexible and highly fibrillated, so that the asbestos fibers are sufficiently dispersed and entangled in the joint sheet. Therefore, the sheet has high tensile strength, and is a sheet having characteristics suitable as a base material of a gasket which is flexible and has a high compressibility.

However, asbestos is a natural mineral, and there is a concern that resources may be depleted. Therefore, recently, asbestos has not been used at all, and joints using inorganic fibers and / or organic fibers other than asbestos have recently been used. Sheet (called asbestos-free joint sheet or non-asbestos joint sheet, hereinafter abbreviated as NA joint sheet)
Is used.

[0007]

The fibers used in this NA joint sheet include organic fibers such as aramid fibers which are fibrillated similarly to asbestos. Usually, it is often used in an amount of about 5 to 15% by weight due to poor steam resistance. In addition, inorganic fibers such as rock wool, carbon fiber, and glass fiber are more rigid and have a larger fiber diameter than asbestos fibers.
During mixing or plate making, the fibers are easily broken, and when the amount of fibers is increased, when a material is laminated on the hot roll side using a calender roll, a so-called trare phenomenon in which the material adheres to the cold roll surface occurs, These materials are often used in an amount of about 10 to 30% by weight, since the plate-making properties are significantly reduced. Therefore, the NA joint sheet is characterized by having a higher compounding ratio of the filler than the asbestos joint sheet, and characteristics such as tensile strength, compressibility, and flexibility often become problems as a base material of the gasket.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an NA joint sheet having good tensile strength, compressibility, and flexibility.

[0009]

In order to achieve the above-mentioned object, the present invention is directed to a method for producing a mixed material composed of a base fiber excluding asbestos, a rubber, a filler, a rubber chemical, and the like. A joint sheet obtained by putting a seed material on a hot roll side by being inserted between a roll and a cold roll, wherein the joint sheet contains a filler having a particle size of 5 to 15 μm in an amount of 40% by weight or more. The main point is that

The present inventors conducted a research experiment on the type and the particle size of the filler which greatly affected the performance of the NA joint sheet, and found that the particle size of the filler was 5 regardless of the type or shape of the filler. １５15 μm, desirably 8 to 12
It has been found that by adding a filler of μm, an NA joint sheet having good properties such as tensile strength, compressibility, flexibility and the like and excellent plate-making properties can be obtained. this is,
When the filler having a particle size of 5 to 15 μm is mixed with a base fiber, a rubber swollen in a solvent, or the like, the filler enters a gap between the fibers, and the mixed material becomes denser. It is presumed that since the bonding is sufficiently performed, the plate-making properties are good and the properties are excellent.

On the other hand, fillers having a particle size of 5 μm or less tend to agglomerate and are not sufficiently bonded to rubber, resulting in a sheet having poor tensile strength and flexibility.
The above-mentioned filler tends to cause a so-called trare phenomenon in which the material adheres to the cold roll surface during plate making, and becomes a sheet having a small tensile strength and a small compressibility in terms of characteristics.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, a mixed material obtained by mixing a composition comprising a base fiber excluding asbestos, rubber, a filler, a rubber chemical and the like with a solvent is mixed with a hot roll. It is put between a pair of rolls composed of cold rolls, laminated to a predetermined thickness on the hot roll side, and then peeled off from the hot roll to produce a joint sheet having a particle size of 5 to 5.
The content of the 15 μm filler was 50% by weight based on the total amount of the composition.

The filler used in the present invention includes kaolin clay, calcined kaolin clay, silica, silica sand, white carbon, alumina, talc, wollastonite, graphite, sericite, mica, diatomaceous earth, calcium carbonate, sodium bicarbonate, Particle size is 5 to 15 μm among fillers such as calcium hydroxide, aluminum hydroxide, barium sulfate, glass beads, magnesium oxide, and zinc oxide.
Can be used in combination such that the content thereof is 40% by weight or more.

The fibers used in the joint sheet of the present invention include aromatic polyamide fibers, polyamide fibers, polyolefin fibers, polyester fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyvinyl chloride fibers, and polyurea fibers. Fiber, polyurethane fiber, polyfluorocarbon fiber, phenol fiber,
Organic fibers such as cellulosic fibers, rock wool, carbon fibers, glass fibers, sepiolite, ceramic fibers,
Inorganic fibers such as fused quartz fibers, chemically treated high silica fibers, fused silicate alumina fibers, continuous alumina fibers, stabilized zirconia fibers, boron nitride fibers, alkali titanate fibers, whiskers, boron fibers, and metal fibers can be used. These fibers may be used alone or in combination of two or more.

The rubber material used for the joint sheet of the present invention includes acrylonitrile butadiene rubber, hydrogenated acrylonitrile butadiene rubber, acrylic rubber, ethylene propylene rubber, styrene butadiene rubber, chloroprene rubber, butadiene rubber, butyl rubber, fluorine rubber,
Silicone rubber, chlorosulfonated polyethylene, ethylene-vinyl acetate rubber, polyethylene chloride, butyl chloride rubber,
Rubbers such as epichlorohydrin rubber, nitrile isoprene rubber, natural rubber, and isoprene rubber can be used. These rubber materials can be used alone or in combination of two or more.

As rubber chemicals, vulcanizing agents such as sulfur, zinc oxide, magnesium oxide, peroxide, dinitrosobenzene, polyamine compounds, aldehydeamine compounds,
Thiuram-based compounds, dithiocarbamate-based compounds, sulfenamide-based compounds, thiazole-based compounds, guanidine-based compounds, thiourea-based compounds, xanthogens, vulcanization accelerators such as acid-based compounds, antioxidants, anti-scorch agents, Those conventionally known as rubber chemicals for forming a joint sheet, such as a plasticizer and a colorant, are widely used.

[0017]

The present invention will be described below in detail with reference to examples. Example 1 A base material, a rubber, a rubber chemical, a filler, and toluene having the composition shown in Example 1 in Table 1 were mixed at a low speed with a Henschel mixer for 20 minutes to prepare a mixed material. Then, the obtained mixed material is heated with a hot roll heated to 150 ° C.
It was put between cold rolls kept at 0 ° C., and was press-vulcanized and molded while being laminated on the hot roll side to obtain a 1.5 mm thick NA joint sheet.

Example 2 An NA joint sheet having a thickness of 1.5 mm was obtained in the same manner as in Example 1 using the materials shown in Example 2 in Table 1.

Example 3 An NA joint sheet having a thickness of 1.5 mm was obtained in the same manner as in Example 1 using the materials having the composition shown in Example 3 in Table 1.

Example 4 A 1.5 mm thick NA joint sheet was obtained in the same manner as in Example 1 by using the materials having the composition shown in Example 4 in Table 1.

Example 5 An NA joint sheet having a thickness of 1.5 mm was obtained in the same manner as in Example 1 using the materials having the composition shown in Example 5 in Table 1.

Comparative Example 1 An NA joint sheet having a thickness of 1.5 mm was obtained in the same manner as in Example 1 using the materials having the composition shown in Comparative Example 1 in Table 1.

Comparative Example 2 An NA joint sheet having a thickness of 1.5 mm was obtained in the same manner as in Example 1 using the materials having the composition shown in Comparative Example 2 in Table 1.

Table 2 shows the manufacturability, tensile strength, compressibility and flexibility of the joint sheets of Examples 1 to 5 and Comparative Examples 1 and 2. Here, the measurement of tensile strength, compressibility, and flexibility is based on JIS.
The test was performed based on the test standard of the R3453 asbestos joint sheet. As a result, from Examples 1 to 3, the particle size was 5 to 15 μm.
By adding 40 to 60% of a filler of m, a good sheet having a good balance of tensile strength, compressibility and flexibility can be obtained, and the types and combinations of the fillers are changed from those of Examples 4 and 5. It can be seen that the same characteristics can be obtained. In Comparative Example 1, a large amount of filler having a particle size of 5 μm or less was added, but there was a problem in tensile strength.
It can be seen that there are problems in plate making properties and compressibility because many fillers of 5 μm or more are used.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

As described above in detail, according to the present invention, by using a filler having a particle size of 5 to 15 μm in the NA joint sheet in an amount of 40% by weight or more, good plate-making properties and good properties can be obtained. An excellent sheet can be obtained.

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Claims (1)

[Claims] 1. A mixed material composed of a composition comprising a base fiber excluding asbestos, a rubber, a filler, a rubber chemical and the like is charged between a hot roll and a cold roll, and a sheet is laminated on the hot roll side. A filler having a particle size of 5 to 15 μm in the joint sheet.
A joint sheet containing 0% by weight or more.