JPH0363564B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for neutralizing sulfonated materials such as polyolefin fibers and powders with a base. A commonly used method for making polyolefin molded articles hydrophilic is to treat them with a sulfonating agent such as fuming sulfuric acid or sulfuric anhydride, followed by neutralization with a basic aqueous solution such as caustic soda or aqueous ammonia. It is also used industrially as a method for manufacturing containers such as gasoline tanks that are substantially impermeable to solvents and fuel, and as a method for improving the water wettability of materials. However, in the above conventional method, fibers,
Surface area per unit weight (specific surface area) like powder
In the case of particles with large particles, especially particles that are finely powdered and have secondary agglomeration, the effect of imparting hydrophilicity by sulfonation may not be sufficiently exerted. That is, the water wettability decreases during long-term use or storage. When subjected to thermal history during fiber processing, powder molding, etc., water wettability decreases and coloring becomes noticeable. As a result of research into a method for treating sulfonated polyolefin that overcomes the drawbacks of the conventional methods described above, the inventors of the present invention have found that by treating sulfonated polyolefin fibers or powder with a specific treatment solution, the method can be used for a long period of time. As a result, the present invention has been completed, which provides extremely good hydrophilic polyolefin fibers and powders that do not have a decrease in hydrophilicity and hardly undergo coloration even after being subjected to thermal history such as molding and heat treatment. That is, the present invention uses an organic solvent or/and a solubility parameter (sp value) of 10 or more.
and treating the sulfonated polyolefin fiber or powder with a treatment solution containing a base and an anionic surfactant or a nonionic surfactant with an HLB (hydrophilic/lipophilic balance) of 10 to 18 in water. This is a method for treating hydrophilized polyolefin fibers or powder. In the present invention, polyolefin refers to polymers such as polyethylene, polypropylene, polybutene, etc.
Alternatively, it is a copolymer of two or more olefins such as ethylene, propylene, butene, hexene, and vinyl chloride. In the present invention, the above-mentioned polyolefin fibers or powders that have been sulfonated by a conventional method are neutralized, and these fibers and powders are products or semi-finished products made of polyolefins that have a linear or granular shape. In addition, those having a specific surface area of 100 cm ³ /g or more, and those having a specific surface area of 300 cm ³ /g or more are more likely to exhibit the effects of the present invention. Note that the surface area is calculated by measuring the necessary size by microscopic observation and assuming that the surface is smooth. The solvent of the treatment solution to be neutralized has a solubility parameter [sp value; J.appl.Chem., 3, 71 (1953), PA
One or a mixture of two or more selected from organic solvents with a SMALL of 10 or more and water are suitable.
The optimal solvent is selected based on the type of polyolefin, the degree of sulfonation, etc., but from an economic standpoint, water or a mixed system of water and an organic solvent is preferable. With an organic solvent having an sp value of 10 or less, it is generally difficult to dissolve the base, and the effects of the present invention cannot be sufficiently obtained. Any organic solvent that has an sp value of 10 or more and that hardly reacts with dilute bases can be used. Examples include methanol, ethanol, acetone, acetonitrile, isopropanol, and the like. Bases include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hypochlorite, and lithium acetate, their weak acid salts, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide. , ammonia gas,
These include ammonia water and amines having 2 to 5 carbon atoms such as methylamine and dipropylamine. The concentration of the base may normally be 1 to 10%. As the surfactant, anionic surfactants such as higher fatty acid alkali salts and alkyl sulfates, and nonionic surfactants with an HLB of 10 to 18 such as polyethylene glycol alkyl ether are used, especially those with an HLB of 10.
-18 nonionic surfactants are preferred. The amount of surfactant added is 0.01 to 1% relative to the basic treatment agent.
That's fine. In the present invention, a treatment solution is prepared by dissolving the above base and surfactant in the above organic solvent or/and water, and to this is added polyolefin fibers or powder sulfonated in fuming sulfuric acid by a conventional method. . Next, after stirring at room temperature for about 30 minutes, the polyolefin fibers or powder are separated, washed with water, and dried to form a product. The hydrophilic polyolefin treated by the method of the present invention does not lose its hydrophilicity over a long period of time, and furthermore, even when subjected to thermal history such as molding and heat treatment, coloration hardly progresses, and the hydrophilicity remains unchanged. It does not deteriorate. The treatment liquid of the present invention can also be used as a treatment liquid for activating a sulfonated polyolefin with reduced hydrophilicity. That is, by adding this treatment liquid to a polyolefin whose hydrophilicity has decreased due to long-term continuous use, etc., and treating it at 20 to 80°C, the hydrophilicity is significantly restored. EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. Examples 1 to 5, Comparative Examples 1 to 3 300 g of polyethylene powder with an average diameter of 100 μm is added to 800 ml of fuming sulfuric acid adjusted to an SO ₃ concentration of 10%, and reacted for 20 minutes with stirring. Immediately after the reaction is completed, the powder is separated and thoroughly washed with dilute sulfuric acid and then with water to obtain sulfonated polyethylene powder. This powder is slightly yellowish brown in color. The above sulfonated polyethylene powder is treated for 30 minutes in the basic treatment liquid shown in Table 1, and thoroughly washed with water to obtain a product. This was packed into a test tube with a diameter of about 10 mm and heated from the outside in an oil bath set at 150°C to obtain a pencil-shaped sintered body. Table 1 shows the evaluation results for the degree of coloration and hydrophilicity of this sintered body. This is the result of measuring the height of the rising water column.

[Table] Examples 6 and 7 Approximately 300g of polypropylene powder with an average diameter of 300μ
The mixture was dispersed in 600 ml of perchlorethylene, 100 ml of a 5% solution of SO ₃ /perchlorethylene prepared in advance was added thereto, and the mixture was reacted for 50 minutes with stirring. After the reaction was completed, the powder was separated to obtain sulfonated polypropylene powder. The above sulfonated polypropylene powder is treated for 30 minutes in the basic treatment liquid shown in Table 2, and thoroughly washed with water to obtain a product. This was packed into a test tube with a diameter of approximately 10 mm and heated from the outside in an oil bath set at 150°C to obtain a pencil-shaped sintered body. The degree of coloration and hydrophilicity of this sintered body were evaluated in the same manner as described above, and the results are shown in Table 2.

[Table] *1 Sufficient amount to neutralize sulfonated polypropylene *2 1% amount of treatment liquid *3 HLB=10.9

Claims (1)

[Claims] 1 Sulfonated with a treatment solution containing a base and an anionic surfactant or a nonionic surfactant with an HLB of 10 to 18 in an organic solvent or/and water with a solubility parameter (sp value) of 10 or more. A method for treating polyolefin fibers or powder made hydrophilic, the method comprising treating polyolefin fibers or powder.