CS265594B1 - A method for filling hollow fibers of polyethylene terephthalate - Google Patents

Abstract

The method of filling hollow fibers made of polyethylene terephthalate with special fillers for active filter fillings, ion exchangers, biologically active surface and spatial formations, for reducing flammability, eliminating static charges and is also applicable to other synthetic fibers, especially olefinic fibers, while using the principle that the hollow fiber is processed in an aqueous or organic solution of the filler in a weight ratio of 1 part of fiber to 25 to 100 parts of solution at a temperature of 20 to 50 °C under a pressure of at least 5 kPa for more than 30 minutes, after which the pressure is equalized to the ambient pressure in a period of no less than 30 seconds.

Description

The invention relates to a method of filling hollow fibers made of polyethylene terephthalate, which uses the principle of applying vacuum to the hollow fiber in a solution of a special filler, whereby the cavities are filled by subsequent pressure equalization to the ambient pressure.

Currently, hollow synthetic fibers, which contain fillers with various specific effects in their cavities, are not yet produced in the country. The patent documentation does not list any suitable technological method for filling the cavities of synthetic fibers, especially at low temperatures, which is a condition, for example, for the application of non-thermostable biologically active substances. Known methods of preparing fibers using core-sheath technology require that the fillers be thermostable up to temperatures of up to 300 °C, regardless of the high complexity of the technology itself. Similar problems arise when adding components with specific effects directly to polymers before their spinning.

A number of methods have been proposed for the physical and chemical binding of various substances with fibers, mainly based on the use of surface microporosity.

The disadvantages of the current state are eliminated by the method of filling hollow fibers of polyethylene terephthalate with antistatic, retarding, biologically active, selectively sorbing and desorbing and other fillers for special purposes according to the invention, the essence of which lies in the fact that the hollow fiber in the form of staple or fabric containing hollow fibers is processed in an aqueous or organic solution of the filler in a weight ratio of 1 part of the fabric to 25 to 100 parts of the solutions at a temperature of 20 to 50 ° C under an absolute pressure of not more than 5 kPa for more than 30 minutes, after which the pressure is equalized to the ambient pressure in a period of not less than 30 seconds. Preferably, a hollow fiber with a length of up to 250 mm is used. The efficiency of the filler in the cavity is determined by the length of the fiber, the diameter of the cavity and the physicochemical properties, especially the chemical type of the filler, the solvent and the viscosity of the filler solution. The fiber cavity is filled temporarily or permanently over the entire cross-section, or a film is formed on the inner surface.

The advantage of the method of filling hollow fibers according to the invention is that, depending on the type of filler used, it achieves mainly long-term specific effects, which are minimally influenced by other textile treatments. The long-term effect of e.g. biologically active fillers is given by the gradual release by capillary action or by gradual desorption from the fiber cavities. The filling method is based on the use of low temperatures (up to 50 °C), which expands the possibilities of applying a number of fillers that are not thermostable. Another advantage is that filling the fiber cavities can be carried out both in the staple as a textile raw material and in the finished product - a fabric containing hollow fibers. The filler can be applied from an aqueous or organic environment. The filling technology is simple and, apart from a vacuum device, does not require any other special machinery. The method of filling hollow fibers according to the invention can also be used as a method for determining the hollowness of the fiber raw material on the principle of differential weighing before and after filling.

The principle of the method of filling hollow fibers from polyethylene terephthalate is illustrated by the following examples.

Example 1

A hollow polyethylene terephthalate fiber with a fineness of 0.67 dtex was used, which was placed in an aqueous solution of a bactericide marked with a water-soluble dye in a weight ratio of 1 part fiber to 80 parts solution. The pressure in the pressure vessel was reduced to 3 kPa within 10 minutes. The vacuum was applied for 60 minutes at room temperature. Then the pressure was equalized to ambient pressure within 60 seconds. After removal from the solution, the fiber was washed several times in water and dried in a laboratory hot-air dryer at a temperature of 60 °C. The filling of the cavities was checked microscopically in polarized light. The obtained fiber showed biological activity even after the tenth normalized washing according to DIN 54 014.

Example2

A hollow polyethylene terephthalate fiber was placed in an aqueous solution of an antistatic agent mixed with an inorganic salt, marked with a water-soluble dye, in a weight ratio of one part of fiber to 40 parts of solution. The same conditions were then used as in Example 1. The vacuum time was divided into two parts: 30 minutes of ramp-up to a temperature of 50 °C and 30 minutes of vacuum at a temperature of 50 °C. After washing and drying the fiber, the filling of the cavities was checked microscopically on sections of the fiber. The resistivity (ohm.m) of the fiber was determined and compared with the surface-treated hollow fiber, with the following results:

40% RH 60% RH surface-treated hollow fiber 1,1.10 ⁷ 5,1.10 ⁶ filled cavities 9,8.10 ⁴ 2,3.10 ⁴

RH - relative humidity

In the same way, the fiber was filled with an inorganic flame retardant. Flammability tests were performed using the maximum extinction angle (MEA) method, and the fiber showed reduced flammability at the level of self-extinguishing fibers.

Example 3

A 100% polyethylene terephthalate fiber fabric was used, with an admixture of 20 wt. % hollow fibers. The fabric was placed in an alcoholic solution of the biologically active substance in a weight ratio of 1 part fabric to 25 parts solution in a pressure vessel, where the pressure was reduced to 5 kPa. After 30 minutes, the pressure was equalized to ambient pressure. The excess organic solvent was removed from the fabric by evaporation. After drying, the fabric was subjected to biological tests. The biologically active substance was still effective in the fabric after the sixth standardized wash according to DIN 54 014.

The application of filled hollow fibers made of polyethylene terephthalate is as active filter fillings, ion exchangers, biologically active surface and spatial formations, reducing flammability, for eliminating high static charges and other special applications. The filling method according to the invention can also be used for other hollow synthetic fibers, especially olefinic fibers.

Claims (1)

Method for filling polyethylene terephthalate hollow fibers with antistatic, retarding, biologically active, selectively sorptive and desorbing and other special purpose fillers, characterized in that the staple fiber or the hollow fiber containing fabric is treated in an aqueous or organic filler solution by weight a ratio of 1 part of fabric to 25 to 100 parts of the solution at a temperature of 20 to 50 ° C at an absolute pressure of no more than 5 kPa for more than 30 minutes, after which the pressure is equilibrated to ambient pressure in less than 30 seconds.