JPS5911714B2 - Heat resistant asbestos sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an asbestos sheet with excellent heat resistance used as a backing material for cushion floors.

Recently, cushion floors found in cafes, hotels, kitchens, washrooms, etc. of ordinary homes are usually made of asbestos sheets with plasticizers such as dioctyl phthalate and chemical blowing agents such as azobisisobutyronitrile. It is manufactured by applying a blended polyvinyl chloride paste and heat-treating it.

This heat treatment temperature tends to increase in order to improve productivity.

Asbestos sheets are manufactured by adding latex (synthetic rubber latex, etc.) internally to improve the F aqueous property during paper making and to strengthen the strength of the resulting sheet.

However, due to the high-temperature heat treatment that cushion floor manufacturers undergo when processing polyvinyl chloride, the polymer in the asbestos sheet deteriorates due to heat, reducing the strength of the sheet and causing problems such as cracking and sheet breakage.
Thermal discoloration of asbestos sheets also causes the back side of the sheet to become brownish, reducing product inversion of the sheet.

As a countermeasure to this problem, it is possible to add a heat-resistant anti-aging agent to the internally added latex or polyvinyl chloride paste.

However, the polyvinyl chloride heat treatment temperature is 180-250℃
The effect is insufficient in the current situation where the temperature is extremely high.

In addition, increasing the amount of the heat-resistant anti-aging agent added leads to a decrease in the interlayer peel strength between the asbestos sheet and polyvinyl chloride and to an increase in cost.

Further, depending on the type of heat-resistant anti-aging agent, problems such as coloring of the asbestos sheet may occur.

One way to reduce discoloration due to thermal deterioration is to reduce the amount of internally added latex, but this reduces the strength of the asbestos sheet, making it more likely to break during the asbestos sheet manufacturing process and the polyvinyl chloride processing process. There is a problem that paper-making properties deteriorate.

As a result of our earnest efforts to improve the heat-resistant deterioration and heat-resistant discoloration of latex-added asbestos sheets, the present inventors discovered that when an asbestos sheet contains magnesium halide, its heat-resistant properties are significantly improved, and we have arrived at the present invention. .

That is, the present invention uses magnesium halide in 1-1
The object of the present invention is to provide a latex-added asbestos sheet having excellent heat resistance and containing 0% by weight.

There are no particular restrictions on the type of asbestos in the latex-added asbestos sheet, and any asbestos fiber for normal sheets may be used.

There are no particular restrictions on the type of internally added latex, including styrene-butadiene latex, which is usually used for asbestos sheets, nitrile rubber latex, acrylic ester copolymer latex, methacrylic ester-butadiene copolymer latex, Chloroprene latex,
Alternatively, any latex of a combination of two or more of these may be used.

The amount of latex used is usually 3 to 25, preferably 5 to 20 parts by dry weight per 100 parts by weight of asbestos.

Aluminum sulfate or a cationic polymer flocculant is usually used to fix latex to asbestos fibers.

The present invention is effective for asbestos sheets produced by any fixing method.

The thickness of the asbestos sheet is 0.2~2rran, 0.4~1rrr!IL.

The thickness of the vinyl chloride layer on the asbestos sheet is 0.5-2
rran, most are around 1 m.

The best way to incorporate magnesium halide into latex-added asbestos sheets is to impregnate the asbestos sheet with an aqueous solution of magnesium halide and then dry it, or to spray the aqueous solution onto the asbestos sheet to impregnate it, then dehydrate and dry it. However, paper may be made by adding and fixing an aqueous magnesium halide solution to an asbestos/latex mixed slurry in a single beater tank.

The content of magnesium halide in the latex-added asbestos sheet in the present invention is 1 to 10% by weight, preferably 3 to 8% by weight.

If it is less than 1 weight factor, the effect on heat resistance will not be sufficient.

In addition, the heat treatment conditions of recent polyvinyl chloride processing processes18
For heat discoloration and heat deterioration resistance for 2 to 3 minutes at 0 to 250°C, a weight ratio of 3 or more to the asbestos sheet is preferred.

However, if the magnesium halide content in the asbestos sheet is too high, the sheet will become hygroscopic, leading to a decrease in sheet strength and causing problems with sheet breakage during the asbestos sheet winding process or polyvinyl chloride processing process. , the magnesium halide content is 10% by weight or less based on the asbestos sheet.

The magnesium halide used in the present invention is preferably MgBr2, MgCl2, or a mixture thereof.

Magnesium halide used as a raw material usually has water of crystallization, but there is no problem in using an anhydride.

The purpose can also be achieved by using magnesium halide in combination with 50% by weight or less of zinc halide, particularly ZnBr2.

In addition, if the asbestos sheet contains additives commonly used in the production of asbestos sheets, such as heat-resistant anti-aging agents, fillers, pigments, and heat stabilizers, there will be no problem in implementing the present invention.

The features of the present invention can be summarized as follows.

(υ The latex-added asbestos sheet of the present invention has 2
It does not easily turn brown even when exposed to high temperatures of 00 to 250°C for 2.3 minutes.

(2) In addition, when this sheet was exposed to a high temperature of 200°C for 3 minutes and the breaking strength was measured at that temperature, the strength was significantly lower than that before heating (a value that can withstand practical use (approximately 3Ky/ 15 rran width or more).

(3) The sheet has high normal strength.

Next, the present invention will be explained in more detail with reference to Examples.

In the examples, heat resistance properties and normal strength were measured by the following methods.

(1) Sheet heat resistance discoloration: The heat resistance discoloration was visually judged on a 5-point scale, with 5 points being given to undiscolored sheets that were not heat treated, and 1 point being given to sheets that had completely deteriorated and turned brown.

(2) Sheet Hot Strength After maintaining the sheet under predetermined heat treatment conditions in a constant temperature bath attached to Niotogerafu, the breaking strength of a sheet with a width of 15 m was measured at a tensile speed of 50 mm/min in a high temperature atmosphere.

(3) Sheet normal strength: tensile speed 50rrrjrL
The breaking strength of a sheet with a width of 15# was measured at 1/min.

In the examples, asbestos sea) A-F fixed latex with the following formulation, and was used for papermaking and papermaking according to JIS-8209.
Manufactured by air drying.

All of the obtained asbestos sheets have a basis weight of 500? /
rrt", sheet thickness 0.7 rran, sheet density 0.
7? /crri.

Comparative Example 1 Table 2 shows the test and measurement results for the asbestos sheet of formulation A in Table 1.

This is an example of a conventional product that is not impregnated with metal salts.

Example 1 An asbestos sheet of Formulation A was immersed in an aqueous MgCl25.0 solution for 10 minutes at room temperature, dehydrated by passing it through a light (rubber roll), and dried for 30 minutes at 60°C in a hot air circulation dryer to remove metal salts. The impregnation rate was determined by the following formula and was 4.8.

The results of the tests and measurements are shown in Table 2.

Examples 2 to 7, Comparative Example 2 Asbestos sheets of formulation A were immersed in an aqueous solution of metal salts shown in Table 2, and experiments were conducted in the same manner as in Example 1, and the results are shown in Table 2.

In Example 4, an aqueous solution containing 2.5 parts each of MgCl2 and MgBr2 was used.

From the above results, it can be seen that the examples of the present invention have excellent resistance to heat discoloration and hot strength without lowering normal strength, compared to those not impregnated with metal salts.

Example 8.9 Comparative Example 3 An experiment was carried out in the same manner as in Example 1 except that MgC12 and ZnBr2 were used in combination.

Table 2 shows the experimental conditions and results.

When using ZnBr2 alone, the hot strength was 4.4 kg, which was slightly lower than the heat discoloration resistance, but curing deterioration occurred.

However, MgCl2/ZnB r2=70~50/
Even when used at a ratio of 30 to 500, the objective could be achieved.

Examples 1O~14 Instead of formulation A, asbestos sheets of formulations B-F were used in which the type of asbestos fiber and the type of internally added latex were changed, and MgB r 2 was used as the metal salt.
An experiment was conducted in the same manner as in Example 1.

Table 2 shows the experimental conditions and results.

Comparative Examples 4 to 8 Experiments were conducted in the same manner as in Example 1 using different types of metal salts, and the conditions and results of the round experiments are shown in Table 2.

It can be seen that these metal salts are ineffective, and only the magnesium halide of the present invention is specifically effective.

Example 15 An experiment was carried out in the same manner as in Example 1, except that instead of immersing the asbestos sheet in the metal salt aqueous solution, the asbestos sheet was sufficiently sprayed with the metal salt aqueous solution.

The results were almost the same as in Example 1.

Example 16 An experiment was conducted in the same manner as in Example 1, except that an asbestos sheet obtained in the same manner as Formulation A was used, except that aluminum sulfate was used as the fixing agent during production of the asbestos sheet.

The results were almost the same as in Example 1.

Example 17, Comparative Example 9 Example 1 (MgC124, 8th impregnation) and Comparative Example 1
Asbestos sheet (not impregnated with metal salts) at 240℃ x 3
When heat treated at 250° C. for 3 minutes, the heat-resistant discoloration was as follows.

Claims (1)

[Claims] 1. A latex-added asbestos sheet with excellent heat resistance, characterized by containing 1 to 10% by weight of magnesium halide.