Process For The Improvement Of Textiles By The Use Of Silicones And Hardening Accelerators

Abstract

Process for the improvement of fibrous materials, particularly in the finishing of textiles, by the use of silicones and hardening accelerators, which comprises treating the materials with aqueous emulsions of silicones and using as hardening accelerators an addition compound of aminoalkyltrifluorosilane and hydrofluoric acid. The fibrous materials thus treated exhibit an excellent and lasting water repellence and a high resistance to rubbing off of colors.

Description

The present invention relates to a process for the improvement of fibrous materials, for instance, for finishing textiles by means of silicones.

It is known that for finishing textiles, solutions or aqueous emulsions of dialkylpyolysiloxanes and/or of alkylhydrogenpolysiloxanes can be used, both called "silicones" hereinafter. In order to make the silicones adhere to the materials to be finished, at reduced hardening temperatures, it is necessary to use simultaneously some condensation accelerators or catalysts. It has already been suggested to use as catalysts organometallic compounds, e.g. tin, zinc or lead salts of carboxylic acids, and also inorganic compounds such as zirconyl oxide-chloride and lead nitrate together with the above-named silicones; one of the purposes of the finishing treatment is, for instance, hydrophobing or rendering water repellent.

It is moreover known to use as hardening agents water-soluble aminoalkylsilanes, e.g. gamma-aminopropyltriethoxysilane.

The above-mentioned products have however a number of shortcomings which decrease the possibility of their use. Thus the metal salts of long-chain carboxylic acids active as hardening agents are water insoluble, and it is therefore necessary to convert them into stable dispersions miscible with water before they can be used in the finishing operations. However, it is difficult to be sure that these dispersions will be truly stable and it is not impossible that instable impregnating liquors will thus result.

It is a further disadvantage that the use of metal salts as catalysts incurs a considerable decrease in resistance of the colors against rubbing off. Therefore catalysts containing the above-described metal salts cannot be used when the fibrous materials are supposed to have a high resistance to such rubbing off of colors.

As to aminoalkylsilanes, these have a slightly alkaline reaction in water; when using alkyl- or arylhydrogenpolysiloxanes as hydrophobing agents, hydrogen splitting will soon occur with decomposition of the alkyl(aryl)hydrogenpolysiloxane, and that renders impregnating liquors useless after a short time. Furthermore, aminoalkylsilanes are easily subject to gelling. Up to the present, there are no agents known to counteract the gelling.

It is the object of the present invention to provide a process which will permit to avoid the shortcomings of the methods hitherto known in the improvement, particularly the hydrophobing treatment, of fibrous materials with the use of silicones.

It is a further object to provide a process for providing on textiles a permanent hydrophobing finish.

It is yet another object to provide a finishing process for fibrous materials in cases in which high resistance to rubbing off of colors is required.

Other objects and many of the attendant advantages will be readily appreciated as the same becomes better understood by reference to the following detailed description.

It has now been found that in the process of improving the properties of fibrous materials, more particularly the finishing of textiles, the shortcomings caused by the presence of aminoalkylsilanes can be eliminated by using aminoalkylsilanes which have been treated with hydrofluoric acid. In the last-mentioned treatment, very stable addition products of aminoalkyltrifluorosilanes with hydrofluoric acid are obtained which proved to be very effective when added to known emulsions of silicones as hardening catalysts. Even gelled aminoalkylsilanes and distillation residues of aminoalkylsilanes can be used, which are otherwise not suitable for the preparation of such addition products.

The preparation of the addition products is not the subject matter of the present invention; they may be made in accordance with U.S. Pat. application Ser. No. 572,890 filed Aug. 17, 1966 by Christian Dathe, one of the coinventors of this application, and others, and entitled "Production of Amino-Organofluorosilicates," issued as U.S. Pat. No. 3,458,555 of July 29, 1969. The addition products are obtained as crystalline, water-soluble products of the general formula NR.sub.2 (CH.sub.2).sub.n SiF.sub.3.sup.. mHF, in which R stands for hydrogen, an organic group or an organic amino group, e.g. -C.sub.2 H.sub.2 NH.sub.2 or -CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NH.sub.2, n= 1 to 8, preferably 3 and 4, and m .ltoreq. the number of N atoms in the molecule, but at least 1. The compounds have considerable stability to water and they are used in combination with aqueous silicone emulsions for making fibrous materials, such as textiles, water repellent.

As already mentioned, the impregnating liquor prepared with silicone emulsions and the addition products have extraordinary stability and lead to a hydrophobing finish which is laundry-proof and resistant to chemical cleaning, while allowing the materials to maintain their complete resistance to rubbing off of colors.

The quantity of the addition product to be used as hardening accelerator or catalyst, calculated on the silicone content of the emulsion, is not critical. In general, 0.1 to 50 parts by weight, preferably 1 to 30 parts, of the addition product are used per 100 parts by weight of silicone. The quantity is partly dependent on the type of fabric, its material, its weave, and the desired finishing effect. It is advantageous to make a preliminary test to determine the desirable amount of the addition product in each individual case.

The process according to the invention is especially suitable when the silicone component consists of lower alkylhydrogenpolysiloxanes, e.g. methylhydrogenpolysiloxanes or mixtures of the same with lower dialkylpolysiloxanes, e.g. dimethylpolysiloxanes.

The catalyst according to the invention also favorably affects the stability of the impregnating liquor in the presence of products for rendering the materials crease-proof, for instance in the presence of urea-formaldehyde precondensates.

The invention will now be more fully explained in a number of examples, but it should be understood that these are given by way of illustration and not of limitation and that many changes in the details can be made without departing from the spirit of the invention.

In the following all parts are given by weight, unless stated otherwise.

EXAMPLE 1

a. Preparation of the Silicone Emulsion

To 50 parts of a solution consisting of 60 percent of a methylhydrogenpolysiloxane having a viscosity of 16 cst. (20.degree. C.) and 40 percent of test benzine, we add successively, while stirring, 1.5 parts of a nonylphenoxypolyglycol ether and 48.5 parts of water; the so obtained preliminary emulsion is homogenized in a homogenizer which permits adjustment to 150 atm. superpressure.

b. Effecting the Impregnation

A mixed fabric consisting of 67 parts of polyester fiber and 35 parts of cotton is treated with an aqueous impregnating liquor of the following composition: 30 g./l. of the silicone emulsion as described in a. and 2.5 g./l. of gamma-aminopropyltriflourosilane-hydrogenflouride, NH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.sup.. HF, made according to the above-mentioned U.S. Pat. No. 3,458,555.

The impregnating liquor does not exhibit any splitting off of hydrogen upon use of polyhydrogensiloxanes and remains stable for a period of at least 24 hours. It imparts to the fabric the following properties:

treated not treated __________________________________________________________________________ Spraying test according to "Spezitex-Hydrophob" 1 5 Crease-restoring angle .alpha.60 according to TGL 0-53 830 131.degree. 105.degree. Resistance to rubbing according to TGL 0-54 021 5 5 __________________________________________________________________________

it should be added at this point, by way of explanation, that "Spezitex" is a collective trademark registered in the German Democratic Republic, the use of which is limited by a strict adherence to a number of tests set down in a circular dated June 1964.

Briefly stated, hydrophobing tests are carried out on a 20 cm..sup.2 flat piece of textile specimen inclined at 45.degree. to the horizontal plane, which is sprayed with water from a height of 15 cm. The hydrophobing effect is indicated by the degree of adherence of the drops to the surface of the textile, and is graded as follows:

1. Drops of water running off completely;

2. Slight adherence of drops on the sprayed surface;

3. Slight wetting of the sprayed surface;

4. Noticeable wetting of larger areas;

5. Complete soaking of the sprayed specimen.

"TGL" stands for "Technische Guete und Lieferbedingungen," an official/German-language/designation for accepted specifications of the German Democratic Republic, comparable to ASTM in U.S.A.

EXAMPLE 2

a. Preparation of the Silicone Emulsion

In a high-speed stirrer Type "Ultra-Thurrax," made by the film Janke & Kunkel, Staufen, German Federal Republic:

17 parts dimethylpolysiloxane having a viscosity of 1000 cst. (20.degree. C.),

13 parts methylhydrogenpolysiloxane having a viscosity of 50 cst. (20.degree. C.),

20 parts test benzine,

3 parts of a polyoxyethylene-sorbitane ester of a fatty acid, and

47 parts water.

b. Effecting the Impregnation

A cotton fabric is finished by treating it with an impregnating liquor of the following composition:

250 g./l. of an approx. 50 percent urea-formaldehyde precondensate, 4 g./l. ammonium chloride,

2 g./l. glacial acetic acid,

50 g./l. the silicone emulsion prepared under a/ and

10 g./l. gamma-diaminoethylenepropyltrifluorosilane-hydrogenfluoride, NH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.sup.. 2HF, made according to the U.S. Pat. No. 3,458,555.

The impregnating liquor, which remains effective for at least 8 hours, imparts to the cotton fabric the following high-quality properties:

Spraying test according to "Spezitex-Hydrophob" 1 to 2 Spraying test after three washings in soap and soda 2 to3 Crease-restoring angle .alpha.60 according t o TGL 0-53 830 12 6.degree. Resistance to rubbing according to TGL 0-54 021 5

Claims

what we claim is:

1. In a process for improving fibrous materials, particularly for finishing textiles, wherein an emulsion of a finishing agent is applied to the textile substrate, the thus treated textile is then dried and finally cured to obtain the finished article, the improvement comprising impregnating said fibrous materials with a liquor containing aqueous emulsions of alkylhydrogenpolysiloxanes or a mixture thereof with dialkylpolysiloxanes, in combination with a hardening catalyst consisting of an addition compound of an aminoalkylfluorosilane and hydrofluoric acid.

2. The process as defined in claim 1, wherein the ratio of silicone content in the emulsion and the hardening catalyst is 100 parts by weight of silicone: 0.1 to 50 parts of catalyst.

3. The process as defined in claim 2, wherein said ratio is 100 parts by weight of silicone: 1 to 30 parts of catalyst.

4. The process as defined in claim 1, wherein the silicone compound in the emulsion is lower alkylhydrogenpolysiloxane and the addition product in the impregnating liquor is gamma-aminopropyltrifluorosilane-hydrogenfluoride of the formula NH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.sup.. HF.

5. The process as defined in claim 1, wherein the silicone compound in the emulsion is methylhydrogenpolysiloxane and the addition product in the impregnating liquor is gamma-aminopropyltrifluorosilane-hydrogenfluoride of the formula NH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.sup.. HF.

6. The process as defined in claim 1, wherein the silicone compound in the emulsion is lower alkylhydrogenpolysiloxane in mixture with lower dialkylpolysiloxane, the impregnating liquor also containing a urea-formaldehyde precondensate as crease-proofing agent, and the addition product consists of gamma-diaminoethylene-propyltrifluorosilane-bis-hydrogenfluoride of the formula NH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.sup.. 2HF.

7. The process as defined in claim 1, wherein the silicone compound in the emulsion is methylhydrogenpolysiloxane in mixture with dimethylpolysiloxane, the impregnating liquor also containing an urea-formaldehyde precondensate as crease-proofing agent, and the addition product consists of gamma-diaminoethylene-propyltrifluorosilane-bis-hydrogenfluoride of the formula NH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 Ch.sub.2 SiF.sub.3.sup.. 2HF.