DE1102094B - Process for the production of nonwovens - Google Patents

Description

As is known, fibrous nonwovens are produced in such a way that the fibrous nonwoven initially obtained is produced solidified with the help of a binder.

Fibers of various types can be used as the starting material. In addition to natural Fiber raw materials, rayon and acetate fibers also come from synthetic fibers based on, for example Polyamides, polyesters, polyolefins, polyvinyl chloride and also glass fibers are possible.

The fiber fleece is generally obtained on a clutter. The fiber webs produced in this way face in the longitudinal direction an orientation that gives the fiber fleece a higher strength in this direction. The fat of the fiber fleece can be varied within wide limits. Because one to produce the desired Fleece thickness usually several fleece layers are superimposed, the individual layers are here combined in alternating orientation to achieve good strength in all directions.

Another way of producing nonwovens with balanced strength is to use the to continue loosened fibers in an air stream using suitable special machines and collected on a perforated drum screen as an unoriented random fleece.

As binders for the production of fiber nonwovens, inter alia. thermoplastic products in Powder form or mainly used as dispersions. Butadiene-styrene dispersions are particularly suitable with a predominant proportion of butadiene, and also butadiene-acrylonitrile dispersions Natural rubber emulsions. These dispersions are often further additives, such as Synthetic resin solutions, vulcanization auxiliaries, vulcanization accelerators and fillers are added. The fiber webs are impregnated or sprayed with the said dispersions and then transformed into a solid nonwoven fabric on drying rollers, possibly simultaneously can achieve an embossing effect.

In addition, nonwovens made of polytetrafluoroethylene fibers can be used with dispersions of polytetrafluoroethylene, polymonochlorotrifluoroethylene or copolymers the named ethylene derivatives with unsaturated, in particular halogen-containing hydrocarbons, such as ethylene, propylene, butadiene, monochlorotrifluoroethylene, 2-chloro-l, 3-butadiene and soaked through after the water has evaporated Pressure or heat.

In addition, you already have yarns or fibers made of non-thermoplastic material with additions of fibers from high-pressure polyethylene or hydrolyzed Kopolymeri seeds of vinyl acetate and ethylene under process for production
of nonwovens

Applicant:

Chemical works Hüls Aktiengesellschaft, Marl (Kr.Recklinghausen)

Dr. Joachim Amende and Dr. Hans Friedrich,

Marl (district of Recklinghausen),
have been named as inventors

Pressure at temperatures below 200 ° C to form single fibers or yarns with a completely smooth surface that no longer protrudes fiber ends, processed.

It is also known to use water-soluble substances such as starch, glue, casein or polyvinyl alcohol, to be used as a binder in aqueous solution; but these products have the disadvantage that they are sensitive to water and lose their binding capacity when exposed to moisture.

Finally, it has already been proposed to use thermoplastic fibers as binders for nonwovens use. So far, however, these fibers have not gained any importance as binders because they are used for Appropriate processing usually only requires a low melting temperature for polymers relatively low molecular weight is given. The nonwovens obtained in this way show accordingly only low strength properties and are therefore used in the manufacture of articles where high strength with the use of small amounts of binders are required, are not suitable.

It has now been found that fiber nonwovens of excellent strength from natural, semi-finished or fully synthetic fiber raw materials as the base fiber and a binder through thermal treatment can be produced at 140 to 200 ° C if the binder used is fibers made from the so-called low-pressure process produced polyolefins, preferably polyethylene and / or polypropylene, in one Amount of 5 to 15%, based on the base fiber, used. In addition to the natural fiber raw materials, such as cotton, linen, sisal, wool and others, are semi or fully synthetic fiber raw materials such as rayon, Viscase rayon, cellulose acetate, polyamide, Polyacrylonitrile and polyester fibers, can be used as base fibers. It is particularly advantageous as a basic

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fiber use a fiber obtained by treating natural or * regenerated cellulose with acrylonitrile in the presence of alkali. The cellulose fiber is first treated with dilute sodium hydroxide solution, spun off and then afterwards. with · ^; s Acrylonitrile treated. The cyanoethylation can also take place in a single bath, the treatment being carried out in a dispersion of dilute sodium hydroxide solution in acrylonitrile; which is produced with the help of an alkali-resistant emulsifier (cf. German patent specification 753,343). '

Furthermore, a natural or regenerated cellulose can advantageously be used as the base fiber, which was produced by polymerizing acrylonitrile or other polymerizable compounds ., the fiber in an aqueous medium- with acrylonitrile, with the addition of an emulsifier in the presence of an oxy EO dationsmittels is post-addition of ^{acrylonitrile.} polymerisätionsfähige, other compounds, such as styrene ,. vinylidene chloride, or esters of acrylic or methacrylic acid, suitable ( See Chemical Week, March 16, 1957., pp. 112).

Fibers made from polyolefins produced by the so-called low-pressure process are suitable as binders. such as polyethylene, polypropylene, polybutylene, with an average molecular weight of 60,000 to 100,000, preferably from about 80,000.

In order to achieve the most even possible mixing of the base fiber with the binder, it is advisable to add the low-pressure polyolefin fiber on the card. The fleece thus obtained is For example, passed between calender rolls heated to 140 to 200 ° C and thus solidified. Ever According to the demands on the square meter weight and the strength, the nonwoven fabric can be composed of several Layers exist.

According to a particular embodiment of the method, it is possible to already have the nonwoven fabric known binders, such as solutions of rubber in benzene or aqueous solutions of Starch, glue, casein, polyvinyl alcohol or dispersions of butadiene-styrene or butadiene-acrylonitrile copolymers, in quantities of 2 to 40%, to be sprayed or soaked and then dried. This way there will be another increase the strength values achieved.

It is also advantageous to incorporate precondensates of synthetic resins into the fiber fleece, which are contained in The presence of catalysts after their condensation within the fiber also leads to solidification of the nonwoven. Synthetic resins based on are particularly suitable for this purpose of urea-formaldehyde, melamine-formaldehyde and phenol-formaldehyde and their mixtures, these Precondensates can be added to the fiber nonwoven in amounts of 10 to 15%. Through this Additives reduce the hydrophilicity of the finished fabrics.

According to the present procedure it is possible to Nonwovens using polyolefin fibers, which are produced according to the so-called low-pressure process and the polyolefin fibers obtained by the high pressure process through distinguish a significantly higher molecular weight to solidify in an advantageous manner.

The fiber nonwovens produced in this way can be subjected to the usual finishing operations, in particular - Dyeing, printing, finishing, subjected without the material structure suffering. The finished nonwovens can be used in a known manner for clothing. fabrics, -, upholstery fabrics, fabric inserts, armpit cushions, Shoe lining,, curtains, handkerchiefs, tampons and use similar articles.

example 1

Loose cotton with a fiber length of 18 to 24 mm is made with ^; an addition of 6%> polyethylene fiber produced by the low pressure process (molecular weight about 80,000) processed on a card in multiple pass to a nonwoven fabric and then passed through a calender at a temperature of 170 ° C. With a weight of 138 g per square meter, the nonwoven fabric shows a strength of 1.2 kilometers of tearing. In comparison, a cotton fleece which has been sprayed with a butadiene-styrene emulsion as a binder shows a strength of 0.3 kilometers of tearing at a weight of 236.9 g per square meter.

- ■ - -: Example 2

Loose cotton is, as indicated in Example 1, with an addition of 12 0 low-pressure polyethylene fibers (Molecular weight about 80,000) processed into a nonwoven fabric. You get a material that is a Shows a weight per square meter of 198 g and a strength of 2.1 kilometers of tear.

Example3

A nonwoven fabric produced according to Example 1 was used with a solution of 200 g per liter of a 60% butadiene-styrene dispersion containing about 74% butadiene contains in the approach of the monomers, treated, then dried and calendered at 170 ° C. The non-woven fabric With a weight per square meter of 160 g, it shows a strength of 2.2 tearing kilometers.

Example 4

A fiber nonwoven fabric produced according to Example 2 is sprayed with a solution containing 50 g of a partial etherified methylol-melamine, 40 g urea-formaldehyde precondensate as well as 10 g of zinc chloride per liter of water. Then the nonwoven fabric dried at 70 ° C and calendered at 175 ° C. The material shows at a weight of 256.0 g per Square meter has a strength of 4.4 tensile kilometers.

Example 5

Natural cellulose fibers are in a closed vessel with a 1.8% sodium hydroxide solution Treated for 20 minutes at 20 ° C. The material is then dried to a moisture content of about 100% centrifuged and cyanoethylated with acrylonitrile for 1 hour at 60 ° C. In the end there is the solution cooled and neutralized with dilute phosphoric acid solution.

The fibers pretreated in this way are re-treated with an addition of 10%, based on the base fiber Polyethylene fibers produced using the low-pressure process are processed into a non-woven fabric on the card, which is then calendered at a temperature of 160 ° C.

Example 6

Natural cellulose fibers are mixed with an aqueous solution of 3 g of iron ammonium alum per liter % Hour pretreated at 20 ° C, rinsed and then in a closed vessel for 1 hour at 70 ° C

with a 3O ^fl / o of acrylonitrile and 20 ⁰ / oLaurylpolyglykoläther, based on the fiber weight, and 5 g per liter of 30 ° / oiges hydrogen peroxide-containing liquor treated.

The fibers obtained in this way are after drying with 12 ^e / o, based on the base fiber, processed by the low-pressure process polyethylene fibers on the card to a fleece, which is then calendered at a temperature of 160 ° C.

Claims (2)

Patent claims: 1. Process for the production of fiber nonwovens from natural, semi-synthetic or fully synthetic Fiber raw materials as the base fiber and a binder through thermal treatment at 140 up to 200 ° C, characterized in that fibers are used as the binder using the so-called low-pressure process manufactured polyolefins in an amount of 5 to 15%, based on the base fiber, be used. 2. The method according to claim 1, characterized in that the fiber fleece before or after thermal treatment impregnated with known binders in the form of solutions or dispersions, then dried and / or thermally is treated. 3. The method according to claim 1, characterized in that the fiber fleece before or after thermal treatment with solutions of resin precondensates based on urea-formaldehyde, Melatin-formaldehyde or phenol-formaldehyde or mixtures thereof soaked, then is dried at a temperature of 140 to 170 ° C and / or thermally aftertreated. 4. The method according to claims 1 to 3, characterized in that a basic fiber by treating natural or regenerated cellulose with acrylonitrile in the presence of alkali obtained fiber is used. 5. The method according to claims 1 to 3, characterized in that a basic fiber by treating natural or regenerated cellulose with aqueous dispersions of acrylonitrile or other polymerizable compounds in the presence of an oxidizing agent and fiber obtained in the presence of a divalent iron salt as a catalyst is used will. Considered publications:
British Patent Nos. 716 477, 732 980, 741 224; U.S. Patent Nos. 2,615,231, 2,764,506, 2,773,781. © 109 530/510 3.61