JPH0316981B2 - - Google Patents

Description

[Detailed description of the invention]

(Subject and Field of the Invention) The present invention relates to improving adhesion to rolls and adhesion when calcium carbonate is used in the manufacturing process of polyvinyl chloride resin tiles containing asbestos. (Background Art) Polyvinyl chloride resin tiles are made by kneading and rolling a composition into a sheet. When the compound kneaded in the sheet-forming step is molded by rolling, etc., it is difficult to form the kneaded material into a sheet unless the kneaded material adheres to the surface of the conveyor or roll. Also,
Molding is difficult if there is only adhesion to the surface of the roll, and the kneaded material itself must be viscous and cohesive. In this type of resin tile that does not use asbestos, there is no need to use a binder because the kneaded material is sticky and cohesive during the molding process using rolls or the like. However, asbestos-containing resin tiles have inhibited caking and have little cohesiveness.
Binder such as petroleum resin or natural resin is used together. However, binders generally lead to high costs and have many problems with their chemical molecular structure in terms of thermal stability. It is best not to use it for as long as possible. In addition, as mentioned above, asbestos, which is added to tiles to give them flame retardancy and reinforcing properties, impairs workability during the molding process, and also poses an occupational health problem due to the generation of dust. Because asbestos has become a serious problem, we want to use as little as possible as much as possible. In addition to the above-mentioned problems in the manufacturing process, calcium carbonate has traditionally been used as a filler, regardless of whether or not asbestos is used, in order to reduce costs. Calcium carbonate exists naturally in large quantities as rocks and is inexpensive, and is widely used as a base and filler in various industrial products such as fillers for rubber products, printing inks, various adhesives, various paints, and paper fillers. Active research is being conducted on it, and it is also used in large quantities in tiles. If used as a bulking agent, heavy calcium carbonate may be used, as shown in the specification of JP-A-57-139134. Heavy calcium carbonate is produced at low cost by physically crushing and classifying natural limestone, but with current crushing and classifying technology, particles ranging in size from 0.01 μm to 10-20 μm are mixed, resulting in a poor particle size distribution. It has a wide, gentle slope and a large specific surface area, and it has been subjected to heat denaturation for many years on earth, so it is inert and has a tack that can be used as a paint, although it is not strong enough to be used as a paint. It does not have sufficient physical properties to prevent it from being hidden. In addition, heavy materials are chemically very inert and difficult to undergo surface treatment for activation. Precipitated calcium carbonate is used for activation. This is made by adding water to CaO, which is made by firing natural limestone at high temperatures, and then
It is made by chemically precipitating CaCO ₃ by reacting CO ₂ instead of (OH) ₂ , and has a crystal shape with a narrow particle size distribution and uniform particle size, so it is different from heavy calcium carbonate. Different and often activated. This precipitated calcium carbonate is used as a filler for tiles, but this is because it imparts white-white photoselectivity, and although it has been activated, it is also used in combination with asbestos. Unable to exhibit sufficient caking properties. In this way, in the past, calcium carbonate was used simply as a filler in asbestos-based tiles, and therefore ground calcium carbonate was used, whereas in tiles that did not use asbestos, precipitated calcium carbonate was used as a white photoselector. There is. Later, in the process of trial and error research, it was discovered that using surface-treated precipitated calcium carbonate had an adverse effect on the workability of asbestos molding during the kneading and molding process of manufacturing asbestos tiles. It has been found that the improved properties are more than compensated for. (Objective and Structure of the Invention) The present invention provides a method for manufacturing polyvinyl chloride resin tiles using asbestos by imparting caking properties and, therefore, sufficient adhesion and cohesiveness to improve workability. The purpose of this is to provide a method for producing polyvinyl chloride resin tiles that can be improved, and in a method for producing polyvinyl chloride resin tiles in which a polyvinyl chloride resin composition containing asbestos is rolled to form a sheet. It is characterized by containing precipitated calcium carbonate that has undergone surface treatment. (Example) A polyvinyl chloride resin tile using asbestos according to the present invention is treated with vinyl chloride resin, asbestos, filler, plasticizer, stabilizer, coloring agent, calcium carbonate as an extender, and surface treatment. After heating and kneading the strained precipitated calcium carbonate with a Banbury mixer, etc., it is poured into a mixing roll made up of two rotating bodies that rotate in opposite directions and have an appropriate gap between them. Form into a thick ring. After completing the forming process using rolls, cut the annular band wrapped around the rotating body in one place, send it in a linear manner, apply it to a calendar roll to thin it, form it into a sheet, cool it, and cut it into a predetermined size. It is a tile product. Precipitated calcium carbonate produced by the above-mentioned production method is
The particle size can be made uniform, and therefore, the particle size can be adjusted to a desired value. The preferred particle size is 0.01 to 2.0 μm, more preferably 0.03 to 0.2 μm. For example, precipitated calcium carbonate with a primary particle diameter of 0.07 μm has some interparticle aggregation, but as far as the primary particles are concerned, it is easy to adjust most of the particles to around 0.07 μm. In this case, the specific surface area (measured by BET method) can be increased to about 50 to 60 m ² /g, which is more than 10 times that of heavy calcium carbonate. When the average particle size exceeds 0.2 μm, it becomes difficult to obtain the desired caking properties even if treated with various surface treatment agents at a cost-effective throughput comparable to the conventional method of adding caking agent in flake form. . This is because the specific surface area is small. However, it has excellent thermal stability. On the other hand, when the particle size is 0.01 μm or less, the interparticle bonds are strong and form aggregates using the current production method, resulting in poor dispersibility, making it difficult for calcium carbonate to form a good dispersion in the polymer. Conventionally well-known surface treatment agents such as resin acids, fatty acids, fatty acid esters, petroleum resins, coumaron resins, ABS, and paraffin are used, and one or more of them can be applied according to the design specifications. Ru. When performing surface treatment on precipitated calcium carbonate in a slurry state, it is preferable to make it soluble as a metal salt or form an emulsion using an emulsifier, but it is preferable to dry-treat the powder directly. There is also. During the process of kneading and forming using Banbury mixer, mixing rolls, and calendar rolls, the temperature is 80℃.
It is carried out at a high temperature of ~180℃. Therefore, binders such as petroleum resins and natural resins, which have many unstable double bonds, are susceptible to thermal deformation such as oxidation under high-temperature conditions, as shown in the specification of Japanese Patent Publication No. 12533/1973. It is better not to use these binders because they tend to have an adverse effect on coloring properties, etc., but it is a matter of degree and does not mean that they should not be used at all. (Function) The reason why surface treatment of precipitated calcium carbonate significantly improves caking properties is considered as follows. Precipitated calcium carbonate originally has a small particle size and can be prepared as a crystalline form with a small particle size, so it has a large active surface area. The surface treatment agent is adsorbed as a thin layer on these large surface area particles,
It is easily dispersed in polymers and acts as a carrier, similar to conventional binders. In addition, since it exists as a thin layer of organic calcium salt on the particle surface and has strong chemical bonds, it is less susceptible to denaturation in a dispersed state. In addition, since it is compatible with calcium carbonate, which is originally used as a filler, it is well dispersed and has good caking properties and is also highly flexible. (Specific examples) Example 1 Carbon dioxide gas with a CO ₂ concentration of 25% is introduced at a rate of 15000/h into 1 kg of calcium hydroxide slurry with a Ca(OH) ₂ concentration of 15% adjusted to 15°C to produce carbonic acid. to become A soluble resin acid salt is added to the resulting precipitated calcium carbonate slurry in an amount of 5% by weight of the resin acid solid content based on the calcium carbonate solid content, and the mixture is stirred. This slurry is dehydrated, dried, and pulverized to obtain surface-treated calcium carbonate having an average particle size of 0.1 μm. Example 2 Carbon dioxide gas with a CO ₂ concentration of 25% is introduced at a rate of 1000/h into 1000 g of calcium hydroxide slurry with a Ca(OH) ₂ concentration of 25% adjusted to 40° C. for carbonation. Thereafter, in the same manner as in Example 1, the surface was treated with a resinate, dehydrated, dried, and crushed to obtain a surface-treated calcium carbonate having an average length of 4 μm. Example 3 The same conditions as in Example 1 were used except that 3% by weight of H ₂ SO ₄ was added to the solid content of Ca(OH) ₂ in the calcium hydroxide slurry, and the average particle size was 0.005μ.
A surface-treated calcium carbonate of m was obtained. Comparative Example 1 Limestone was crushed and classified to produce heavy calcium carbonate having an average particle size of 1.0 μm, and this was dry-treated with resin acid in an amount of 5% by weight based on the weight of the heavy calcium carbonate using a Henschel mixer. The amount of heavy calcium carbonate in one batch of Henschel mixer is
It is 100Kg.

【table】

[Table] Method for producing polyvinyl chloride sheets Knead the formulations in the above table for 5 minutes in a Banbury mixer at 150 to 180°C, then mix with a mixing roll (one
After kneading for 5 minutes at a temperature of 110 to 140°C (others being 70 to 80°C), a sheet with a thickness of 2 mm is formed using a calender roll at 80°C. Test item (i) Roll tackiness: The better is the adhesion of the compound to the roll (wrapability) during kneading with a mixing roll. (ii) Cohesiveness: The shorter the time it takes for the compound to be uniformly kneaded, the better. (iii) Thermal stability: The less discoloration there is when heating the tile sheet in a gear oven at 180°C for 50 minutes, the better. Test results

[Table] From the comparison of Formulation 1 and Formulation 2, it can be seen that if the treated calcium carbonate of Example 1 is used, physical properties equivalent to or higher than those of conventional binders can be obtained at a lower cost. From the comparison between formulation 2 and formulations 3 and 4, the particle size is
It can be seen that when the thickness is less than 0.01 μm or more than 2.0 μm, the desired physical properties are slightly degraded. It can be seen from Blends 5 and 6 that even if the plasticizer and asbestos are reduced, if surface-treated calcium carbonate is used, physical properties better than those of conventional blends can be obtained. Also, combination 7
It can be seen that surface treatment of heavy calcium carbonate, which has a low viscosity, with a resin acid has no effect. (Effects) It has the following excellent physical properties in terms of caking, thermal stability, and plasticity. (1) The product has excellent adhesion to roll conveyors, etc., excellent workability, smooth molding, and good dispersion, so the product has excellent flexibility. In addition, since it has good caking properties and is well organized, the time for kneading and mixing is shortened, and the process time is shortened. It is possible to omit the use of a high-cost binder, resulting in cost reduction. Because it is highly flexible and durable, the amount of asbestos can be reduced.
In this respect, costs are particularly reduced. (2) Since the surface treatment agent becomes a calcium salt and strongly binds to the surface of the calcium carbonate colloid particles, it has excellent thermal stability and can prevent thermal denaturation during the process, as well as excellent weather resistance and durability. Excellent. Due to this heat-resistant modification, along with the thickening property mentioned in (1) above, there is no need to use conventional binders, and the weight is 1/4 to 1/5 of the amount of binders conventionally used. nothing. (3) Plasticity of DOP, DHP, etc. can be significantly reduced. Because of its excellent plasticity, the amount of asbestos used can be reduced, which in turn reduces dust production and improves working conditions.

Claims (1)

[Claims] 1. A method for manufacturing polyvinyl chloride resin tiles in which a polyvinyl chloride resin composition containing asbestos is rolled to form a sheet, wherein the composition contains precipitated calcium carbonate that has undergone surface treatment. A method for manufacturing a polyvinyl chloride resin tile, which is characterized in that it is left to stand. 2 The primary particle size of precipitated calcium carbonate is 0.01μ
The manufacturing method according to claim 1, wherein the thickness is from m to 2.0 μm. 3. As a surface treatment agent, resin acid, fatty acid, fatty acid ester, petroleum resin, coumaron resin, ABS resin,
The manufacturing method according to claim 1 or 2, wherein one or more types of paraffin are used.