JPH027349B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to gasket materials. The purpose is to create a gasket that does not contain asbestos, which is conventionally used as a material for gasket materials, which completely eliminates sanitary problems, and which is of a higher quality than conventional gaskets that contain asbestos. The object of the present invention is to provide a new and useful gasket material. Conventionally, asbestos has been used as a material for gaskets as it has good suitability for gaskets, but in recent years it has been found that asbestos has hygienic problems, and its use has come to be restricted. Therefore, from the above viewpoint, various proposals have been made to obtain gasket materials that do not contain asbestos.
At present, no high-quality gasket material suitable for asbestos-containing gaskets has yet been developed. For example, Japanese Patent Application Laid-Open No. 55-58281 discloses an invention called "Gasket Material and Method for Producing the Same", which uses 50 to 75% monoclinic mica and 2 to 20% by weight. This is a flexible sheet-like gasket whose composition is cellulose fiber, but when the present inventors examined it based on examples, it was found that its quality was poor in mechanical strength and liquid resistance such as water and oil resistance. It was found that the sealing properties were quite poor. The present inventor discovered that the aspect ratio of powder plays an important role in sealing performance, and based on this finding, a high-quality gasket material that does not contain asbestos and is equivalent to or better than conventional gaskets using asbestos was obtained. As a result of extensive research, it was discovered that the aspect ratio of mica, flake diameter, and other inorganic powders play important roles in gasket suitability, and the present invention was achieved. That is, 70 to 99 parts by weight of a mixed powder consisting of mica with an aspect ratio of 40 or more and a flake diameter of 10 to 300μ and another inorganic powder with a particle diameter of 0.5 to 50μ, and 30 to 1 part by weight of a fibrous material. 5 to 30 parts by weight of the binder is added to 100 parts by weight of the mixture, and the mixing ratio of the mica and other inorganic powder is 20:80 by weight.
This led to the invention of a gasket material characterized by a ratio in the range of ~80:20. The greatest feature of the present invention is that inorganic powder other than mica is blended at a fairly high rate, and that the aspect ratio of mica and the shape of its flakes are limited to a predetermined range. These structures greatly differentiate this product from conventional products, and as a result, it is a gasket material of extremely high quality. In the present invention, mica having an aspect ratio (flake diameter/flake thickness) of 40 or more is a flaky mineral of the muscovite, phlogovite, and szorite series. If the aspect ratio of mica is less than 40, the compression and recovery characteristics characteristic of mica will deteriorate, and the mica will exhibit behavior similar to other powders, which is undesirable. In other words, as long as mica is used, an aspect ratio of 40 or higher is required. Furthermore, if mica has an aspect ratio of 40 or more, the purpose of the present invention can be achieved.
In particular, mica flakes with a diameter in the range of 10 to 300μ will give preferable results. In other words, gasket suitability is also affected by the mica flake diameter.If the flake diameter is small (less than 10μ), mica will be difficult to arrange in a layer and it will be difficult to obtain a good result, while if the flake diameter is large (over 300μ), it will be difficult to obtain a good result. This weakens the bonding force between the mica and the sheet surface, making it more likely that the mica will fall off the sheet surface and cause problems with mechanical strength. Furthermore, since mica can be peeled off without limit, even if the upper and lower limits of the flake diameter can be determined as described above, the lower limit of the thickness cannot be determined in practice, and therefore the upper limit of the aspect ratio cannot be determined. cannot be determined. For example, if the maximum flake diameter is 300μ,
The thickness of mica varies by about two orders of magnitude, so it is 5μ.
For a thickness of 0.05μ, the aspect ratio is 60, but for a thickness of 0.05μ, the aspect ratio is 6000, making it meaningless to set an upper limit. However, since the aspect ratio is limited to 40 or more and the flake diameter is limited to 10 to 300μ, it is clear what kind of dimension mica is appropriate, and if the thickness is extremely small, Since the lower limit of the flake diameter is determined, unsuitable flakes are excluded even if the aspect ratio is 40 or more, so there is no inconvenience at all due to the lack of an upper limit of the aspect ratio. Next, the gasket material of the present invention uses a mixed powder of the above-mentioned mica and other inorganic powder as one of the main materials, but other inorganic powders include clay, barium sulfate, and calcium carbonate. , talc, triiron tetroxide, graphite, titanium, calcium silicate, calcium sulfate, silica, etc., and in particular, one or more selected from the group of clay, barium sulfate, calcium carbonate, talc, and triiron tetroxide are used. This will give you good results. The size of other inorganic powders is determined by their particle diameter.
It needs to be less than 100μ, and if it exceeds 100μ, it will not be possible to obtain a synergistic effect with mica. What is the synergistic effect of this mica and other inorganic powders?
This is the most important point in the present invention, and means that the mixture of mica and other inorganic powders exhibits performance that cannot be observed with mica or other inorganic powders alone. In other words, mica alone has good recovery properties but poor liquid resistance and mechanical strength, and other inorganic powders alone have good compression resistance but poor recovery and liquid resistance. By using a mixture of these two, the liquid resistance, which was poor when used alone, is improved, and both compressibility and resiliency are better than when used alone, and the mechanical strength is also considerably improved. It is. In other words, if mica is used alone, even if the aspect ratio is 40 or more,
It is not possible to obtain an excellent gasket material as in the invention disclosed in the publication, and an excellent gasket material can only be obtained by blending other inorganic powders having a particle size of 100 μm or less. In order for the other inorganic powder to best exhibit the above synergistic effect, it is particularly preferable that the particle size is 50 μm or less. The lower limit of the particle size of other inorganic powders is 0.5μ, which is considered to be the practical minimum particle size of commercially available inorganic powders.
Although it is possible to use a particle size smaller than that, taking into account the difficulty in obtaining and economic efficiency, the particle size of other inorganic powders is preferably in the range of 0.5 to 50μ. In addition, in order to obtain the above synergistic effect, the mixing ratio of the mica and other inorganic powder should be 20:80 to 80 by weight.
A range of 80:20 is desirable. That is, the mica content is 20-80% in the mixed powder.
It is desirable that the mica content is 20%.
If it is less than 80% or more than 80%, the mutual disadvantages of mica and other inorganic powders are canceled out, and the synergistic effect of enhancing the properties of both becomes difficult to be exhibited. The particularly preferable range for this mixing ratio is 40:60.
~60:40. Next, in the present invention, a fibrous material is mixed into the above-mentioned mixed powder of mica and other inorganic powder. Examples of the fibrous material include pulp made of vegetable fibers, polyolefin artificial fibers such as polyester, phenol, acrylic, polyamide, rayon, polyolefin, and vinyl.
Examples include inorganic fibers such as ceramic fibers, rock wool, carbon fibers, potassium titanate fibers, metal fibers, and flame-resistant fibers. In particular, paper making suitability in wet paper making method, heat resistance,
Regarding water resistance, pulp made of vegetable fibers, aromatic polyamide synthetic pulp, polyester fibers, phenol fibers, carbon fibers, and potassium titanate fibers are preferred. The mixing ratio of this fibrous material and the mixed powder is 30 to 99 parts by weight of the mixed powder to 30 to 99 parts by weight of the mixed powder.
It is required to be in the range of 1 part by weight. In other words, the blending ratio of the fibrous material in these mixtures is limited to 1 to 30%.If the blending ratio of the fibrous material is less than 1%, it becomes difficult to obtain the reinforcing effect of the fibers; If it exceeds 30%, the liquid resistance of the gasket material deteriorates. In addition, liquid resistance in the present invention refers to water resistance and oil resistance, and is measured by the weight increase rate after being immersed in these liquids for a certain period of time, and the smaller the weight increase rate is, the better the liquid resistance is. . Next, the gasket material of the present invention is obtained by blending a binder with the mixture of the above-mentioned mixed powder and fibrous material and forming this into a sheet-like material. Acrylonitrile-
1 selected from the group of butadiene-based, styrene-butadiene-based, and acrylic acid ester-based organic polymers
It is desirable that the species be larger than the species. Note that this binder is not limited to those mentioned above, and depending on the purpose, for example, fluoro rubber,
Other organic polymers such as silicone rubber may also be used. The blending amount of this binder is 5 to 100 parts by weight of the mixture of mica and other inorganic powders and fibrous materials.
30 parts by weight is required. In other words, the blended amount of this binder is the above mixture.
If the amount is less than 5 parts by weight per 100 parts by weight, the mechanical strength will decrease, and compression recovery properties and liquid resistance will also deteriorate; on the other hand, if this amount exceeds 30 parts by weight, the mechanical strength will decrease. Although the liquid resistance is improved, the stress relaxation rate increases and the material becomes extremely susceptible to "sagging." The gasket material of the present invention consists of the main materials and their blending ratios as described above, but it goes without saying that other auxiliary materials may be added as necessary. Examples of the auxiliary materials include vulcanizing agents such as sulfur, vulcanization accelerators such as thiurams, dithiocarbamates, and thiazoles, vulcanization accelerators such as zinc oxide,
Examples include dispersants and activators. The gasket material of the present invention may be manufactured by any conventional method known as a method for manufacturing beater sheets or joint sheets. For example, when manufacturing using the beater sheet method, which is a wet method, first a predetermined amount of fibrous material is dispersed in water using a hydra pulper or a beater, and then a predetermined amount of mica and other inorganic powders are added and dispersed uniformly. After that, a predetermined proportion of binder and other auxiliary materials are added as necessary, and then a fixing agent is added as necessary to ensure that the binder is sufficiently deposited in the above mixture. The material is guided to the Chest below and, if necessary, uses a coagulant to maintain uniform dispersion while being guided to the paper making section where it is made into sheets. The material is then introduced into a drying section for drying, and if necessary, introduced into heating rolls and heated and compressed to obtain the gasket material of the present invention. In addition, when producing the material of the present invention by the joint sheet method, which is a dry method, first a predetermined amount of fibrous material is dispersed with a stirrer such as a cotton opener, and then a predetermined amount of mica and other inorganic materials are dispersed into the material. A clay-like raw material is created by mixing the powders, then adding a binder dissolved in a solvent and other auxiliary materials as needed. The gasket material of the present invention can be obtained by introducing this raw material to heating rolls and heating and compressing it. As explained above in detail, the gasket material of the present invention is obtained by blending a mixed powder of mica and other inorganic powder, a fibrous material, and a binder as main raw materials in a predetermined ratio. It is a sheet-like material, and its greatest characteristics are that the aspect ratio of mica is 40 or more, and that other inorganic powders with a particle size of 100μ or less are blended with mica.
By blending this mica with other inorganic powders, superior performance that cannot be observed with mica or other inorganic powders alone is expressed, and the shortcomings of both disappear and the properties of both are mutually enhanced. It is an extremely useful material that exhibits excellent gasket properties such as compression resilience, liquid resistance, and mechanical strength, and has the same or higher quality than conventional asbestos-containing gaskets. It can be called a material. Furthermore, since the gasket material of the present invention does not contain any asbestos, there is no hygienic problem at all, and as mentioned above, it has a quality equal to or higher than that of asbestos-containing gaskets, so it is judged that it can completely replace it. It is something. EXAMPLES Hereinafter, examples of the present invention will be given and comparative examples will be shown to further embody the present invention, but the present invention is not limited to the following examples. Example 1 Blend composition Parts by weight Mica with mixed powder aspect ratio...70, flake diameter...280μ 42.5 Clay with particle size…0.5μ 42.5 Fibrous material NBKP (softwood pulp; bleached sulfate pulp made from softwood...following) The same applies to the examples)
10 Phenol fiber (fibrous phenol-formalin resin...the same applies to the following examples) (2 denier, 2 mm length) 5 Binder acrylonitrile-butadiene rubber (produced by aqueous phase radical emulsion polymerization of acrylonitrile and butadiene, particle size approximately 0.2~ Solid content 40 at 1.05μ
~50% latex; commonly known as
NBR latex...The same applies to the following examples)
15 Example 2 Compound composition Parts by weight Mixed powder Same mica as in Example 1 45 Same clay as in Example 1 45 Fibrous material NBKP 10 Binder Acrylonitrile-butadiene rubber 20 Other additives Sulfur 0.3 Vulcanization accelerator (carbon disulfide) Derivatives of xanthate salts...the same applies to the following examples)
0.2 Zinc oxide 1.0 Example 3 Composition Part by weight Mica with mixed powder aspect ratio...50, flake diameter...15μ 64 Same clay as in Example 1 21 Fibrous material NBKP 10 Phenol fiber (2 denier, 2 mm length) 5 Binder Acrylonitrile -Butadiene rubber 10 Example 4 Compound composition Parts by weight Mica same as mixed powder Example 3 36 Particle size...5μ calcium carbonate 54 Fibrous material NBKP 10 Binder Acrylonitrile-butadiene rubber 15 Other additives Sulfur 0.23 Vulcanization accelerator 0.15 Zinc oxide 0.75 Example 5 Mixing composition Parts by weight Mica same as mixed powder Example 1 20 Barium sulfate with particle size...0.8 μ 60 Fibrous material Synthetic pulp of aromatic polyamide 20 Binder Acrylic ester rubber 15 Comparative example 1 ( Example without blending mica) Blend composition Same clay as in Example 1 in parts by weight 90 NBKP 10 Acrylonitrile-butadiene rubber 15 Sulfur 0.23 Vulcanization accelerator 0.15 Zinc oxide 0.75 Comparative example 2 (With no blending of other inorganic powders, mica (Example when the shape is inappropriate) Blending composition Mica with aspect ratio by weight of 20 and particle size of 1μ 90 NBKP 10 Acrylonitrile-butadiene rubber 15 Sulfur 0.23 Vulcanization accelerator 0.15 Zinc oxide 0.75 Comparative example 3 (Shape of mica is appropriate, but no other inorganic powder is blended) Blend composition Weight part Same as Example 1 Mica 90 NBKP 10 Acrylonitrile-butadiene rubber 15 Sulfur 0.23 Vulcanization accelerator 0.15 Zinc oxide 0.75 Comparative example 4 (Example using asbestos, which is conventionally considered to be the best) Blending composition Weight parts Asbestos 90 NBKP 10 Acrylonitrile-butadiene rubber 15 Sulfur 0.23 Vulcanization accelerator 0.15 Zinc oxide 0.75 Above, Examples 1 to 5, and Comparative Examples 1 to 4 were prepared, and gasket materials were prototyped using the beater sheet manufacturing method. The results of measuring these physical properties are shown in the table below.

【table】

[Table] The compression ratio and restoration ratio were measured in accordance with JIS standard R-3453. In addition, water resistance and oil resistance indicate liquid resistance, and water resistance is expressed as the weight change rate after immersion in distilled water at a temperature of 100°C for 22 hours, and oil resistance is ASTM No.
It is expressed as the weight change rate after immersion in No. 3 oil at a temperature of 150°C for 5 hours. In both cases, lower values indicate better liquid resistance. From the table of physical property data above, the following can be determined. In Comparative Example 1, which did not use mica, the water resistance was extremely poor and the compressibility was too low. In Comparative Example 2, the restoration rate is poor and the compression rate is too high. Furthermore, although the shape of mica is appropriate, in Comparative Example 3 where no other inorganic powder is mixed, in addition to the same drawbacks as Comparative Example 2, mica falls off and the density decreases.
Moreover, the strength is also small. However, in Example 2, which has a formulation that is considered to be a combination of Comparative Examples 1 and 3, the drawbacks of Comparative Examples 1 and 3 are eliminated, the strength is increased, and it shows an appropriate compression ratio and a large recovery rate, and is water resistant. - Oil resistance has also been greatly improved. In other words, when appropriately shaped mica and other inorganic powders are mixed and used, a wonderful synergistic effect is obtained in which all the physical properties necessary for gasket suitability are improved. Similarly, other examples within the scope of the present invention also showed very excellent physical property data, and had extremely excellent gasket suitability equivalent to or better than that using asbestos shown in Comparative Example 4. -ing

Claims (1)

[Claims] 1. The aspect ratio is 40 or more and the flake diameter is 10.
70 to 99 parts by weight of a mixed powder consisting of ~300μ mica and other inorganic powder with a particle size of 0.5 to 50μ, and 30 parts by weight of fibrous material
5 to 30 parts by weight of the binder is blended to 100 parts by weight of the mixture with ~1 part by weight, and the mixing ratio of the mica and other inorganic powder is 20:80 to 80:20 by weight.
A gasket material characterized in that it is in the range of. 2. The gasket material according to claim 1, wherein the other inorganic powder is one or more selected from the group of clay, barium sulfate, calcium carbonate, talc, and triiron tetroxide. 3 Claims in which the fibrous material is one or more types selected from the group consisting of pulp made of vegetable fibers, aromatic polyamide synthetic pulp, polyester fibers, phenol fibers, carbon fibers, and potassium titanate fibers Gasket material according to item 1 or 2. 4. The gasket according to claim 1, 2, or 3, wherein the binder is one or more selected from the group of acrylonitrile-butadiene-based, styrene-butadiene-based, and acrylic acid ester-based organic polymers. material.