JPH03115484A - Surface treating agent for joint sheet - Google Patents

Abstract

PURPOSE:To obtain the title surface treating agent which scarcely tends to spatter to pollute working environment when applied to a surface of a joint sheet, a gasket, etc., by mixing a white inorganic lubricating material, a binder, an antiseptic, and water each in a specified amount. CONSTITUTION:The title surface treating agent is obtained by mixing 1-30wt.% white inorganic lubricating material (e.g. finely divided hydrous magnesium silicate), 0.5-10wt.% binder (e.g. carboxymethylcellulose), 0-10wt.% antiseptic (e.g. sodium dehydroacetate), and 50-98.4wt.% water. When applied to a surface of a joint sheet, a gasket, etc., it scarcely tends to spatter to adhere to an operator or pollute working environment. In addition, it can effectively prevent a gasket or joint sheet from sticking to coupling flanges due to seizure.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a surface treatment agent for joint sheets, and more particularly to a surface treatment agent for joint sheets used for pipe joint flanges such as piping.

Conventionally, asbestos joint sheets have been widely used as joint sheets. This asbestos joint sheet is made by using asbestos as a base fiber, kneading it with rubber as a binder, rubber chemicals, and filler to prepare a composition for forming a joint sheet. By inserting the material between a pair of rolls consisting of a cooling roll and hot rolling, laminating the composition for forming a joint sheet on the hot roll side, and then peeling the sheet material laminated on the hot roll from the hot roll. has been manufactured.

However, in recent years, there has been a need to use joint sheets in a wide temperature range, for example when transporting high-temperature fluids in high-temperature environments. Joint sheets have been developed that are less likely to cause this.

Such joint sheets are made by laminating a metal core made of wire mesh or a thin metal plate with claws, and a joint sheet forming composition via an adhesive made of thermosetting resin or synthetic rubber. , obtained by heating and vulcanizing.

However, when these joint sheets are processed and used as gaskets by contacting them with joint flanges of pipes, etc., these gaskets seize and adhere to the joint flanges when exposed to high-temperature environments. There was a risk.

As described above, when the gasket seizes and adheres to the joint flange, it becomes difficult to replace the gasket that has suffered thermal deterioration over time with a new one. Additionally, gasket debris remains on the flange, reducing the smoothness of the flange abutting portion and reducing sealing performance.

Therefore, in order to prevent such gas get from burning or adhering to the joint flange, the surface of the gasket is treated by applying graphite, mica, etc. together with water or a solvent. This prevents the gasket from seizing and adhering to the surface.

However, if a surface treatment agent containing graphite, mica, etc. is applied to the gasket, it will scatter and be carried along with the worker, contaminating the working environment, which is undesirable from a sanitary standpoint.

Further, as described above, the use of surface treatment agents containing graphite or the like in food-related applications and fields such as food manufacturing equipment is restricted in terms of food hygiene.

Purpose of the Invention The present invention is an attempt to solve the problems associated with the prior art as described above, and the purpose of the present invention is to avoid the problem of contaminating the work environment by scattering when coating on the surface of joint sheets or gaskets, etc. One of our main objectives is to provide a surface treatment agent for joint sheets that effectively prevents the gasket or joint sheet from seizing and adhering to the joint flange, and effectively prevents the gasket or joint sheet from sticking to the joint flange.

Summary of the invention The surface treatment agent for joint sheets according to the present invention comprises (a)
Inorganic white lubricant = 1 to 30% by weight, (b) Glued: 0.5 to 30% by weight
(iii) preservative = 0.1 to 10% by weight; and (iv) water: 50 to 98.4% by weight.

However, the total content of components (a), (b), (c), and (d) must be 1. 0% by weight.

Since the surface treatment agent for joint sheets according to the present invention is composed of the above-mentioned components, it is less likely to scatter and contaminate the working environment when applied to the surface of joint sheets or gaskets, etc. Moreover, it is possible to effectively prevent the gasket or joint sheet from seizing and adhering to the joint flange.

DETAILED DESCRIPTION OF THE INVENTION The surface treatment agent for joint sheets according to the present invention will be specifically described below.

The surface treatment agent for joint sheets according to the present invention is composed of an inorganic white lubricant, a sizing agent, a preservative, and water.

As described above, the surface treatment agent for joint sheets according to the present invention contains an inorganic white lubricant as a component, but this inorganic white lubricant mainly prevents the gasket from seizing and adhering to the flange. It has the function of preventing

Such inorganic white lubricants include silicates and silicic acids such as magnesium silicate, aluminum silicate, and calcium silicate, calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, kaolin, and clay.
Examples include bentonite, sericite, zeolite, wollastonite, attapulgite, etc. Among these,
Silicates are preferably used.

These lubricants may be used alone or in combination.

The color of the above-mentioned inorganic white lubricant used in the present invention is preferably white, gray, or beige.

Moreover, the particle size of this lubricant is usually 0.1 to 6 Atm
s Preferably, the particle size is 2 μm or less, and when a lubricant having such a particle size is used as a component of a surface treatment agent, the film tends to be thin, the surface becomes smooth, and the adhesion prevention effect tends to be good. It is preferable because it is.

Furthermore, it is preferable that such an inorganic white slipping material has excellent heat resistance, and its thermal melting temperature is usually 250°C.
That's all.

The surface treatment agent for joint sheets according to the present invention contains a sizing agent.

Gluing blended with a surface treatment agent in this way involves applying a surface treatment agent to the surface of the joint sheet (gasket) that is scheduled to come into contact with the flange, and when it dries, a film is formed on the gasket surface, and the surface treatment agent It has the function of preventing the above-mentioned inorganic white lubricant inside from falling off the gasket surface.

Specific examples of such glue A include methyl cellulose, carboxymethyl cellulose, carboxymethyl starch, and the like.

These gluing methods may be used alone or in combination.

The surface treatment agent for joint sheets according to the present invention contains a preservative.

This preservative has the function of preventing corrosion such as water and gluing in the surface treatment agent, and enables long-term storage of the surface treatment agent.

Specifically, such preservatives include, for example, borax, benzoic acid, sodium benzoate, dehydroacetic acid,
Examples include sodium dehydroacetate and nitrofuran, but among these, those without toxicity are preferred, and sodium dehydroacetate is preferably used.

These preservatives may be used alone or in combination.

The surface treatment agent for joint sheets according to the present invention (100 weight 96) contains 1 to 30% of the above inorganic white lubricant.
% by weight, preferably from 2 to 10% by weight, and the sizing is 0.
Preservatives in an amount of 5-10% by weight, preferably 1-3% by weight, 0.1-10% by weight, preferably 0.2-3% by weight
and water is included in an amount of 50.0 to 98.4% by weight, preferably 70 to 90% by weight.

If the amount of the inorganic white lubricant is less than 1% by weight, the anti-sticking effect tends to decrease, and if it exceeds 30% by weight, a thin and uniformly thick coating cannot be formed and processability tends to deteriorate.

In addition, if the amount of adhesive is less than 0.5% by weight, there is a tendency that a sufficient adhesion effect cannot be obtained. Undesirable.

Furthermore, if the amount of the preservative is less than 0.1% by weight, a sufficient preservative effect will not be obtained, and if the amount exceeds 10% by weight, no further change in the preservative effect will be observed.

The surface treatment agent for joint sheets according to the present invention contains an inorganic white lubricant, a sizing agent, a preservative, and water as essential components as described above, but in addition to these components, As an optional ingredient, a surfactant may be included for imparting dispersibility.

Manufacturing method To manufacture the surface treatment agent according to the present invention comprising such various components, for example, a predetermined amount of inorganic white lubricant (), a sizing preservative, and water are placed in a container and mixed using a stirrer. By mixing in this way,
The joint sheet surface treatment agent obtained by uniformly dispersing the above components is usually stored in a container.

How to use To use the surface treatment agent for joint sheets according to the present invention, first apply or spray the surface treatment agent on the surfaces of joint sheets, gaskets, packings, etc., and then dry them. On the surface, usually 0 thickness
．． A film of about 5 to 100 μm may be formed. In this way, a coated joint sheet or the like formed by forming a coating with a surface treatment agent on the surface of the joint sheet or the like is difficult to seize on the flange surface even if it is brought into contact with the flange portion and is pressurized and heated.

Effects of the Invention The surface treatment agent for joint sheets according to the present invention is composed of a predetermined amount of specific components (14) as described above. At the same time, the surface treatment agent is less likely to scatter and attach to workers or contaminate the working environment, which is excellent in terms of hygiene.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Components and blending ratio of surface treatment agent Tap water 97.4% by weight Finely divided hydrated magnesium silicate 2% by weight Carboxymethylcellulose 0.5% by weight Sodium dehydroacetate O, 1% by weight A surface treatment agent with the above composition is applied to the surface of the joint sheet (gasket) without scattering, and dried to form a 1 μm thick coating on the surface of the joint sheet (Gaskera l-). did.

Next, this joint sheet (gasket) with membrane was attached to a joint flange, and a seizure test of the joint sheet (gasket) was conducted under the following conditions to examine the state of seizure.

The results are shown in Table 1.

Example 2 Components and blending ratio of surface treatment agent> Tap water...50.0wt96 Aluminum silicate...30.0wtffi% Carboxymethylcellulose...io, oLff196
Dehydroacetic acid...10.0% by weight In Example 1, except that the surface treatment agent was changed to the above composition,
The test was conducted in the same manner as in Example 1.

The results are shown in Table 1.

Example 3 Components and blending ratio of surface treatment agent Tap water...70.0% by weight Calcium carbonate...15.0% by weight Methylcellulose...13.0HNm% Dehydroacetic acid...2.0% by weight %A test was conducted in the same manner as in Example 1 except that the surface treatment agent was changed to the above composition.

The results are shown in Table 1.

Comparative Examples For comparison, a joint sheet (gasket) coated with water-dispersed graphite (water: graphite - 9:1 (weight ratio)) (Comparative Example 1) and an untreated joint sheet (gasket) (comparison) were prepared. Regarding Example 2), Example 1
Under the same conditions as above, the baked-in state was determined by iΔ1.

The results are shown in Table 1.

Table 1 [Test method] Joint flange n JIS IOK nominal size 40 City Gasket dimensions: Inner diameter 49 mm, outer diameter 86 Ill + I11 thickness 1. ．． 5+nm Tightening torque: 1200 kgf-cm (surface pressure approximately 400 kgf/cJ) After placing the flange with the gasket attached in an electric furnace and heat-treating the flange at the specified temperature and time,
Take it out of the furnace, disassemble the flange, and visually observe the burning state of the gasket on the flange surface.

[Determination of seizure] A: No seizure. The gasket was removed from the flange in almost its original shape.

Part B is baked on. Part of the gasket seizes on the flange,
When the gasket was removed, some of it remained on the flange.

C: Half baked. The gasket seizes to the flange and when the gasket is removed less than half of it remains on the flange.

D: All baked on. The gasket burned into the flange, and when the gasket was removed from the flange, the gasket broke, leaving most of it on the flange.

Claims (1)

[Claims] (1) (A) Inorganic white lubricant: 1 to 30% by weight, (B) Gluing material: 0.5 to 10% by weight, (C) Preservative: 0.1 to 10% by weight, and (d) Water :50 to 98.4% by weight of a surface treatment agent for joint sheets (provided that the above (a), (b), (c) and (d))
(total of 100% by weight).