CS233483B1 - A method for increasing the surface hydrophilicity of polyolefin fibers and films - Google Patents

Abstract

A method of increasing the hydrophilicity of the surface of polyolefin fibers and films by modification in the mass, in which a monoester of glycerin and a carboxylic acid with a carbon number of 4 to 20 is used as a modifying additive, in an amount of 0.1 to 6.0% by weight. The effect of the monoester of glycerin is increased if the fibers or films thus modified are thermoset at a temperature of 80 to 150 °C, and also if, in addition to the monoester of glycerin, color pigments are added to the polymer in an amount of 0.1 to 15% by weight before processing.

Description

The invention relates to a method for increasing the surface hydrophilicity of polyolefin fibers and films by modification in the mass.

Polyolefins whose macromolecules do not contain functional groups capable of binding water molecules are characterized by the hydrophobicity of their surface. The water wetting angle on the surface of the polyolefins is high and ranges from 85 ° to 100 °. In addition to certain advantages, such as chemical inertness to chemicals, the self-separating properties of injection molding, polyolefins, in particular in the form of fibers and films, have a reduced wettability by liquids due to their high surface hydrophobicity, resulting in low sorption and adhesion properties. and fiber processing, the tendency to electrostatic charge and increased dirtyness.

Increasing the surface hydrophilicity of polyolefin fibers and films solves a number of inventions through chemical and physical modification. On an industrial scale, the hydrophilicity of fibers and polyolefin films is increased most often by means of close-brewing. Recently, low temperature plasma surface treatment has been used for films.

The method of increasing the surface hydrophilicity of the polyolefin fibers and films according to the invention consists in using a glycerol monoester and a carboxylic acid monoester with a carbon number of 4 to 20, in an amount of 0.1 to 6.0% by weight, as a modifying additive.

The effect of the glycerol monoester is enhanced when the fibers or foils thus modified are thermofixed at a temperature of 80 to 150 ° C and also when color pigments in an amount of 0.1 to 15% by weight are added to the polymer prior to processing. The polyolefin used is a commercial polymer suitable for preparing fibers and films.

The effect of increasing hydrophilicity is achieved despite the overall hydrophobic character of glycerides, in particular higher fatty acids. It can be explained by the orientation of the diffuse glyceride molecules in the surface layer of the fiber or film.

Advantages of the present invention include a greater increase in the surface hydrophilicity of the polyolefins than with the modifiers used hitherto, the solubility of the higher fatty acid monoglycerides in the polyolefins, and the beneficial effect of the modification on the fiber and film processing properties.

Modified polyolefins may contain light and heat stabilizers, color pigments, dispersants and other additives.

The examples below illustrate the subject matter of the invention.

Example 1

A mixture of 8 kg of polypropylene having a molecular weight of 100,000 and 2 kg of a concentrate containing 0.1 kg of stearic acid monoglyceride and 1.9 kg of polypropylene was spun in a spinner with a 33 hole spindle at 295 ° C. The fibers were discharged at 10 ° C and 1: 3. The fineness of the discharged fibers was 3.3 dtex.

In a similar manner, fibers of pure polypropylene without modification additive were prepared. Preparations were not used to prepare the fibers.

The wetting angle of the water drop on the surface of the gray fibers was 90 °, on the surface of the fibers according to the invention 70 °. The water uptake was 37% by weight for the modified fibers according to the invention and 19% by weight for the unmodified fibers. By thermofixing the fibers of the invention at 1.0 ° C in air for 1 hour, the water intake was increased to 41 wt%. Modified fibers showed better processability in the drawing process.

Example 2

Polypropylene fibers prepared as in Example 1 except that the concentrate contained 0.1 kg of oleic acid monoglyceride, 0.1 kg of red PR-144 pigment and 1.8 kg of polypropylene.

The water wetting angle on the surface of the modified fibers was 27% lower than that of the unmodified fibers. The uptake of water and aqueous solutions of the preparation of oleic acid monoester and polyoxyethylene glycol 600 by modified fibers was 38%, with unmodified 19%. The modified fibers had better processability in ducting.

Example 3

A mixture of 9.8 kg of polypropylene powder of 50,000 molecular weight and 0.2 kg of stearic acid monoglyceride is mixed on a rapid mixer and remelted under vacuum on a double-spindle kneading machine at zone temperatures of 220 ° C, 180 ° C, 170 ° C, 220 C.

Foil is extruded from the prepared granulate on an extruder. In a similar manner, a film is prepared without the addition of a monoglyceride.

The water wetting angle on the film without modification was 88 ° and with modification according to the invention 65 °. The application of a temperature of 110 ° C for 1 hour little results in a further decrease in the wetting angle on the modified film to 58 °.

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Polyethylene film prepared as in Example 3 The mixture contained 7.9 kg of polyethylene, 1.5 kg of black anthracene aadze pigment and 0.6 kg of palmitic acid monoglyceride.

The wetting angle on the film without modification additive, formed by a drop of water, was 84 ° and with a monoglyceride content of 46 ° according to the invention.

Example 5

Polypropylene fibers prepared as in Example 1 except that the concentrate contained 0.1 kg of butyric acid monoglyceride, 0.1 kg of yellow yellow pigment 95 and 1.8 kg of polypropylene.

The wetting angle of the surface of the modified fibers was 20% lower than that of the unmodified fibers. Water uptake was 45% for modified fibers and 19% for unmodified fibers. The modified fibers had better processability in drawing.

Claims (3)

Example 2 Polypropylene fibers prepared as in Example 1 except that the concentrate contained 0.1 kg oleic monoglyceride, 0.1 kg red PR-144 pigment and 1.8 kg polypropylene. The wetting angle of the surface of the modified fibers was 27% lower than unemodified. The uptake of water and aqueous solutions of the monoester of oleic acid and polyoxyethylene glycol 600 by 40 µg / l modified fibers was 38%, with unmodified 19%. The modified fibers had better workability processing. EXAMPLE 3 A mixture of 9.8 kg of 50,000 polypropylene powder and 0.2 kg of stearic acid monoglyceride is mixed on a high-speed mixer and, under vacuum, remelted on a double-strand kneader at 220 ° C, 180 ° C, 170 ° C, 220 ° C. Folios are extruded from the prepared granulate on an extruder. Folios were prepared in a similar manner without the addition of monoglyceride. The water dipping angle on the film without modifying additive was 88 ° and 65 ° with the modification of the invention. A temperature of 110 ° C over a period of 1 hour did little to reduce the wetting angle of the modified film to 58 °. Example 4 Polyethylene film prepared as in Example 3 The mixture contained 7.9 kg of polyethylene, 1.5 kg of black anthracene aadze pigment and 0.6 kg of palmitic monoglyceride. The wetting angle on the film without the modifying additive formed by the drop of water was 84 ° and the monoglyceride content of the invention was 46 °. Example 5 Polypropylene fibers prepared as in Example 1, except that the concentrate contained 0.1 kg of butyric monoglyceride, 0.1 kg of yellow 95 and 1.8 kg of polypropylene. The wetting angle of the surface of the modified fibers was 20% lower than that of the non-modified ones. The water intake of the modified fibers was 45% for the unmodified 19%. The modified fibers had better workability. SUBJECT OF THE INVENTION CLAIMS 1. A method for increasing the hydrophilicity of a surface of a polyolefin fiber and a film of adding an additive to the melt of a polyolefin prior to its treatment, characterized in that the modifying agent is a monoester of glycerin and carboxylic acid having carbon numbers of 4 to 20, in an amount of 0.1 to 6.0% by weight. 2. Process according to claim 1, characterized in that pigments in the amount of 0.1 to 15% by weight are added to the polyolefin melt. 3. Method according to claim 1, characterized in that the modified polyolefin fibers are thermosetted at 80 to 150 ° C.