DE1469351C3 - Process for strengthening nonwovens - Google Patents

Description

The reaction products containing isocyanate groups can be prepared in a manner known per se take place by the at least two hydroxyl groups bearing compounds with one on the Hydroxyl content calculated stoichiometric excess reacts on polyisocyanates at elevated temperatures.

The treatment of the nonwovens with the liquors which can be considered according to the invention is carried out according to the known consolidation methods:

The binder is applied, for example, in the form of an aqueous liquor or a foam from this liquor. The proportion of the binder in the total weight of the aqueous liquor can of course vary within wide limits. It is generally from about 5 to 70 ° / _(), and is advantageously from about 25 to 50 ° / ₀ by weight of the aqueous liquor. The ratio of the two binders a) and b) to one another can likewise vary widely and is, for example, for the ratio a: b in the range from L: 4 to 4: 1.

After the impregnation, the excess liquor or foam is squeezed off (the squeezing effect is, for example, 5 to 100 ° / ₀ binder uptake) and the fleece is fed to a dryer. In addition, the liquors mentioned can be used to strengthen the surface of the fleece by spraying, patting or knife-coating on the thickened liquor or a binder foam. A post-drying heat treatment as is customary

is required when consolidating nonwovens with the addition of the known crosslinkable binders, can be omitted in the present case.

According to the method according to the invention, nonwovens made from a wide variety of fibers can be made more natural or of synthetic origin, for example from cotton, regenerated cellulose, cellulose esters, wool, regenerated proteins, polyacrylonitrile, polyamides, polyurethanes, polyesters, polyolefins, polyvinyl chloride, Polyvinyl alcohol and polycarbonates solidify into nonwovens.

The mechanical properties of the obtained nonwovens are very good, the handle varies depending on the Composition of the binder liquor from soft to hard. The serviceability of the nonwovens becomes not influenced by wet or dry cleaning.

The term "fleece" here refers to loose fibers to understand existing single or multi-layer pile, in which the fibers in preferred directions or else are also arranged without preferred directions; this also includes single or multi-layer piles that are pre-consolidated or needled, as well as nonwovens that have already been sewn with the help of sewing or stitchbonding technology have experienced a certain cohesion. If desired, the nonwovens can also be made with other flat structures z. B., be connected to fabrics, knitted fabrics or foams.

It is already known to use aqueous dispersions, the styrene-butadiene copolymers, for consolidating nonwovens and reaction products having isocyanate groups and consisting of at least two hydroxyl group-bearing compounds ■ and polyisocyanates are made. In front the nonwovens consolidated in this way, the nonwovens consolidated according to the invention are characterized by a higher tear strength.

The subject of an older patent (German patent specification 1265113) is already a method for Refinement of textile materials, especially fabrics, by treatment with aqueous liquors also used according to the invention. The consolidation of nonwovens is not the subject of this older patent, because unconsolidated nonwovens cannot be regarded as textile material in the usual sense will.

In an older German application (cf. German Offenlegungsschrift 1 594 279) there is already a binder for the manufacture of nonwoven fiber-based materials on the basis of aqueous Carboxyl group-containing dispersions have been proposed which, in addition to carboxyl groups containing polymers containing blocked polyfunctional isocyanates. The in the present In contrast to this, the binders proposed in the invention do not contain any blocked polyfunctional ones Isocyanates, but rather isocyanate group-containing reaction products of polyhydroxyl compounds and polyisocyanates.

In the following examples, if nothing otherwise stated, parts by parts by weight.

B e i s ρ i e 1 1

A fiber fleece made of copper oxide ammonia cellulose is treated with an aqueous liquor containing 400 g of a 40% strength aqueous dispersion of a copolymer of 10 parts of butadiene, 10 parts of styrene, 5 parts of acrylamide and 75 parts of butyl acrylate and 600 g of the emulsion described below Contains isocyanate prepolymer. After impregnation, the fleece is squeezed off to a liquor content of around 120%. It is then dried at 80 to 110 ° C. The fleece obtained has a pleasantly soft handle and a tear strength of 52 kg / cm ² at 19% elongation.

The above-mentioned emulsion of the isocyanate prepolymer was prepared as follows:

3000 g of a polypropylene glycol having a molecular weight of about 2000, an OH number of 55.5 and an acid number <0.5, are 535 g Hexamethylene diisocyanate at 110 ° C for 2 hours and then at 130 to 140 ° C for another IV2 hours heated. From 300 g of the reaction product obtained, its content of free isocyanate groups 3.9 percent by weight is then added together with 100 g of ethyl acetate and 600 g of water of 5 g of lauryl sulfate prepares an emulsion.

Example 2

A fiber fleece made of copper oxide ammonia cellulose is treated with an aqueous liquor which contains 400 g per liter of a 40% strength aqueous dispersion of a copolymer of 95 parts of ethyl acrylate and 5 parts of acrylamide and 600 g of the emulsion described in Example 1. The consolidation takes place in the same way as in Example 1. The nonwoven obtained has a relatively soft handle when it is in good condition and a tear strength of 50 kg / cm ² at 22% elongation at break.

E xample 1 3

In the procedure of Example 1, the following can also be used with the same or a similar result Use binder components:

a) aqueous polymer dispersions from:

I. 85 parts of butyl acrylate, 10 parts of butadiene
5 parts of methacrylamide
Solid content: 42%

II. 80 parts of butyl acrylate, 15 parts of acrylonitrile

5 parts of acrylamide
Solid content: 40%

III. 25 parts of butyl acrylate, 48 parts of vinylidene chloride

20 parts of styrene

6 parts of acrylamide
1 part acrylic acid

Solid content: 38%

IV. 60 parts of butyl acrylate and 35 parts of styrene

5 parts of acrylamide
Solid content: 40%

V. 15 parts of acrylonitrile
78 parts of butadiene

4 parts of methacrylic acid
3 parts of acrylamide

Solid content: 38%

VI. 95 parts of ethyl acrylate

5 parts of acrylamide
Solid content: 40%

b) Isocyanate prepolymers made from: (OHZ = OH number. SZ = acid number)

«) Branched polypropylene glycol (OHN 56; molecular weight 3000) and an isomer mixture of 65% toluene diisocyanate (2.4) and 35% toluene diisocyanate (2.6), NCO content of the prepolymer 4.07%;

/ S) linear polypropylene glycol (OHN 108.5; molecular weight about 1000) and hexamethylene diisocyanate, xo NCO content of the prepolymer 5.6%;

γ) linear polyester, produced from adipic acid and diethylene glycol (OHN 42.3; SZ 1.7) and hexamethylene diisocyanate, NCO content of the prepolymer 3.7%;

δ) linear, polyethylene oxide (OHZ 132; molecular weight 850) and ^ hexamethylene diisocyanate, NCO content of the prepolymer 7.2%.

The following table shows the results on different types of nonwoven:

Substance [g /
a I solid]
b Substrate Result 1200 "200 polyamide soft, firm fleece, good elasticity II 250 «100 Polyacrylonitrile soft, not very elastic fleece with medium strength III 300 / 3100 Copper oxide ammonium
niak cellulose hard, inelastic fleece with good strength and
low elongation IV 400 γ 100 polyamide relatively hard, inelastic fleece with extremely good
Tear resistance and excellent wet strength V 150 "300 polyester soft, very elastic fleece with medium strength VI 200 «150 Copper oxide ammonium
niak cellulose relatively hard, inelastic fleece with especially
dry grip IV 350 δ 150 jute inelastic fleece of low elongation and
excellent tear resistance II 250 yl50 Polyethylene tere-
phthalate Vojuminous, soft fleece with medium strength

Claims (2)

Patent claims: 1. Process for consolidating nonwovens by treating the nonwovens with an aqueous liquor, the a) polymers or copolymers produced from vinyl or divinyl monomers and b) reaction products containing isocyanate groups contains at least two hydroxyl-bearing compounds and polyisocyanates, characterized in that as a) Polymers or copolymers produced from vinyl or divinyl monomers with groups capable of reacting with isocyanates and b) isocyanate group-containing reaction products of at least two hydroxyl groups containing compounds with a molecular weight of 500 to 3000 and polyisocyanates be used. 2. The method according to claim 1, characterized in that that the binders a) and b) are used in a ratio of 1: 4 to 4: 1. Ethyl ether, styrene, divinylbenzene, butadiene, isoprene, chloroprene: also those copolymers that are available are when you use N-methylolacrylamide, N-methylol methacrylamide or by reacting them with at least one further functional group containing alcohols prepared derivatives with other olefinically unsaturated compounds polymerized, e.g. B. according to the method of French patent 1,328,255. ίο To the at least two hydroxyl groups bearing Compounds with a molecular weight of 500 to 3000, which are to be used according to the invention Reaction products b) are based, include, for example, polyethylene glycols, polypropylene glycols, Polybutylene glycols or polyhexylene glycols, also the polyesters, which are made from aliphatic dicarboxylic acids, such as succinic acid, adipic acid, sebacic acid or maleic acid, and polyalcohols such as ethylene glycol, Diethylene glycol, propylene glycol, butanediol or neopentyl glycol are available. Are preferred those compounds whose molecular weight is in the range from 800 to 2200 and whose OH number has a value from 30 to 250. The polyisocyanates used for the preparation of the reaction products b) are preferably aliphatic and cycloaliphatic diisocyanates into consideration. Examples include tetramethylene diisocyanate, Hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 2,4- and 2,6-hexahydrotolylene diisocyanate. Suitable are also Also aromatic diisocyanates such as p-phenylene diisocyanate and 2,4- or 2,6-tolylene diisocyanate. and triisocyanates, such as the reaction obtainable from 3 moles of hexamethylene diisocyanate and 1 mole of water product of the formula The invention relates to a method for consolidating nonwovens by treating the Nonwovens with an aqueous liquor, the a) polymers produced from vinyl or divinyl monomers or copolymers and b) isocyanate group-containing reaction products of at least contains two hydroxyl group-bearing compounds and polyisocyanates, characterized in that that as a) of vinyl or divinyl polymers or copolymers prepared with the r ₀ reaction with isocyanates groups capable and b) isocyanate group-containing reaction products of at least two hydroxyl groups containing compounds with a molecular weight of 500 to 3000 and polyisocyanates will. The polymers and copolymers produced from vinyl or divinyl monomers and having groups capable of reacting with isocyanates include, for example, those polymers or copolymers derived from acrylic or methacrylic acid or from their esters capable of reacting with isocyanate groups, e.g. B. the Hydroxyaikylestern, or amides are available, optionally by copolymerization with other olefinically unsaturated compounds such as ethylene, propylene, vinyl chloride, vinyl acetate, vinyl ether, z. B. Vinyl OCN- (CH ₂₎ ,, - N [CONH (CHa) _n -NCO]. ₂