SU374400A1 - METHOD OF OBTAINING NONWAVE MATERIALS - Google Patents

Description

one

The invention relates to methods for producing non-woven glued materials using moisture-thermoplastic polyvinyl alcohol (LAN) fibers as a binder.

Various methods for producing nonwovens are known, including the use of fibers as PVA binder. According to one of them, heat treated and heat washed PVA fibers of 7 mm length are dispersed in water and cast on the grid of a papermaking machine. After steam treatment and drying at 105 ° C, a hygroscopic nonwoven fabric is obtained. In order to increase the strength, the wet material is moistened with aqueous solutions of sulfuric acid and sodium sulfate and treated with formaldehyde gas when heated, then washed and dried.

According to another method, a canvas consisting of a mixture of viscose staple fibers with PVA fibers is sprayed with water, squeezed and dried on a filter calender at 110 ° C. To improve the properties of the obtained nonwoven materials, they are further treated with either formaldehyde in an acidic medium or impregnated with solutions or dispersions pre-condensation of aminoplasts, derivatives of acrylic acid or polyvinyl compounds, there is also a known method of obtaining boring and other cushioning materials by introducing a small amount of about the amount (8%) of water-soluble PVA fibers, followed by moistening with boiling water, drying and impregnating with a mixture containing a dispersion of acrylic and methacrylic resins, melamine formaldehyde resin precondensate, ammonium oxalate and a wetting agent.

However, the above methods are complex and multistage, require for their realization a bulky station for preparing binder solutions and do not fully utilize the unique specific properties of PVA fibers.

A method is proposed for producing nonwoven glued materials by forming a canvas from a mixture of artificial fibers with moisture-thermoplastic polyvinyl alcohol fibers, impregnating the canvas with aqueous solutions of modifying agents - dicarboxylic acid ammonium salt - followed by drying with infrared rays. This makes it possible to significantly simplify the process of producing nonwoven materials, to create durable, waterproof, elastic porous materials with a uniform point structure throughout the entire volume of the product, ensuring their high performance properties. The absence of any contamination of the working bodies of the machines leads to an increase in the equipment utilization rate and an improvement in the overall production culture. The absence of polymer liquid binders in the process makes it possible to eliminate cumbersome special chemical stations and equipment for the disposal of industrial stocks.

Example. Staple natural, artificial or synthetic fibers, as well as their mixtures in an amount of not less than 70% by weight. The whole fibrous mass with a length of 40-88 mm is mixed with 10-30% moisture-thermoplastic freshly produced PVA fibers, which are stretched in the process of forming in wet as 220–230% - and heat-treated at 180 ° C for 5 min. The formed fibrous canvas weighing 60-150 BJM is impregnated at room temperature with a 7-30% aqueous solution of the ammonium salt of maleic acid, squeezed to 2-3 times the weight and dried in a dryer with infrared gas radiators. The temperature in the dryer is controlled by the amount of gas included.

burners. When drying occurs, the material shrinks freely. To increase the density and strength of the nonwoven material, the latter may be hot-calendered at 150 ° C for s. The resulting materials with a canvas weight of 75 g /; and 2 have a tensile strength of 8–18 / sgc / 5 cm, an elongation of 17–23%; air permeability 15-21 min.

Subject invention

A method of producing nonwoven materials by forming a canvas from a mixture of natural or artificial fibers with moisture thermoplastic polyvinyl alcohol fibers, impregnating modifying agents with aqueous solutions, followed by heat treatment, characterized in that, in order to simplify the process, to obtain durable waterproof and elastic nonwoven materials ammonium salt of maleic acid.