Aqueous Dispersions of Fluorine-Containing Polymers

The invention relates to aqueous, solvent-free fluorinecontaining dispersions, a process for preparing them, and their use for the fluorochemical treatment of textiles such as carpets, upholsteries and others in order to confer water and oil resistance on them. Polymers having perfluoroalkyl groups are suitable substances for rendering textiles or carpets both hydrophobic and oleophobic, as described for example in EP 345 552, EP 332 141, EP 73364 and US 3,356,628. These polymers are preferably used for technical reasons in the form of aqueous and ideally solvent-free dispersions.

However, the preparation of aqueous, solvent-free dispersions by known emulsion polymerization techniques is difficult, since the perfluoroalkyl monomers are extremely water-insoluble and it is impossible to obtain stable emulsions in water. The addition of organic solvents, for example acetone, to increase the monomer solubility, as described inter alia in U.S. Pat. No. 3,403,122, produces dispersions which are usually coarsely granular and not very stable under storage. For these reasons the perfluoroalkyl monomers are sometimes polymerized in solution, before the polymer obtained is made into a dispersion. This necessarily requires a further operation compared with an emulsion polymerization and, owing to the presence of solvent in the product, has only limited suitability for use. Moreover, the subsequent dispersing of a precipitated fluoropolymer proves expensive in practice.

It has now been found that the use of amine oxide emulsifiers leads to stable aqueous dispersions whose application properties are distinctly superior to those of other systems. The dispersions obtained are notable in particular because they represent stable systems without the addition of organic solvents and in that, owing to the amine oxide emulsifier, they have an almost neutral pH.

The present invention accordingly provides aqueous, solvent-free dispersions of polymers of monomers of the formulae (1) and (2)

where R is fluorine, chlorine, hydrogen or methyl and n is from 5 to 18, preferably from 8 to 12,

where R is hydrogen or methyl and X is a group of the formula C.sub.6 H.sub.5, CO.sub.2 CH.sub.2 C.sub.6 H.sub.5, CO.sub.2 C.sub.2 H.sub.4 C.sub.6 H.sub.5, CN, CO.sub.2 CH.sub.2 C.sub.6 H.sub.4 Cl, CO.sub.2 C.sub.6 H.sub.4 -C.sub.1 -C.sub.4 -alkyl, CO.sub.2 C.sub.n H.sub.2n+1, where n is from 10 to 22, preferably from 14 to 18, CONHY, where Y is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -hydroxyalkyl, C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.4 -alkyl or CO.sub.2 -C.sub.1 -C.sub.20 -alkyl, preferably CO.sub.2 -C.sub.2 -C.sub.8 -alkyl, and one or more emulsifiers of the formula (3)

where R is C.sub.1 -C.sub.4 -alkyl or hydroxyethyl, R.sup.1 and R.sup.2 are identical or different and each is C.sub.1 -C.sub.4 -alkyl, hydrogen or fluorine, R.sup.3 is hydrogen or C.sub.1 -C.sub.4 -alkyl, x is 1, 2 or 3 and n is from 3 to 9, preferably from 5 to 7, and/or of the formula (4)

where R.sup.1 and R.sup.2 are identical or different and each is C.sub.1 -C.sub.4 -alkyl or hydrogen and R.sup.3 is C.sub.8 -C.sub.18 -alkyl, preferably C.sub.10 -C.sub.14 -alkyl.

The proportion of fluorine-free comonomer of the formula (2) in the polymers can be up to 50 percent by weight.

The emulsifiers used are preferably compounds of the formula (3) where R.sup.1 and R.sup.3 are each hydrogen, R.sup.2 is fluorine, R is C.sub.1 -C.sub.4 -alkyl or CH.sub.2 CH.sub.2 OH, n is from 3 to 9 and x is from 1 to 3, which can be present mixed with up to 30 percent by weight, based on the mixture, of a compound of the formula (3) where R.sup.1, R.sup.2 and R.sup.3 are each hydrogen, R is C.sub.1 -C.sub.4 -alkyl or CH.sub.2 CH.sub.2 OH, n is from 3 to 9 and x is from 1 to 3. Suitable emulsifiers of the formula (3) are in particular those compounds where R.sup.1 and R.sup.3 are each hydrogen, R.sup.2 is fluorine, R is methyl or ethyl, n is from 5 to 7 and x is 1 or 2, which can be present mixed with up to 30 percent by weight, based on the mixture, of a compound of the formula (3) where R.sup.1, R.sup.2 and R.sup.3 are each hydrogen, R is methyl or ethyl, n is from 5 to 7 and x is 1 or 2.

The emulsifiers of the formulae (3) and (4) can be used mixed with co-emulsifiers of the formula (5)

where n is from 4 to 16, preferably from 8 to 10, and m is from 10 to 30, preferably from 18 to 26, and/or coemulsifiers of the formula (6)

where n is from 10 to 2%, preferably from 13 to 18, and m is from 4 to 12, preferably from 7 to 9.

To achieve the technical purpose, the emulsifiers of the formulae (3) and (4) can each be used alone or mixed with one another in any desired mixing ratio. For the stability of the dispersions it is advantageous if up to 50 percent by weight of the emulsifiers of the formulae (3) and/or (4) is replaced by one or more co-emulsifiers of the formulae (5) and (6).

The total amount of emulsifier, based on the total amount of monomer, should be 5-30 percent by weight, preferably 10-15 percent by weight.

To prepare the aqueous dispersions of the present invention the preferred procedure is to admix the monomer mixture with the emulsifiers and any co-emulsifiers and add sufficient water as to produce for the dispersions a fluorine content of 10-30 percent by weight, based on the total dispersion, from the fluorine contents of the monomers and the added emulsifiers together. The mixture is in general stirred at 50.degree. C. under nitrogen for 30 minutes and then a water-soluble free radical initiator customary for an emulsion polymerization, for example azodiisobutyramidine dihydrochloride, is added as catalyst. After heating for example to 50.degree.-60.degree. C. for several hours (see Table 1) the dispersion is stirred without further heating until back at room temperature.

The aqueous dispersions of the present invention are suitable for treating textiles made of natural or synthetic fibers, in particular polyamide, polyester, polyacrylonitrile and wool or blends of these fibers. The textile material can be present in any desired form, for example as tow, loose fiber, yarn, knitted fabric or nonwoven but in particular as woven fabric. The aqueous dispersions of the present invention can be applied to the textile material in the as-prepared form. Customarily, however, they are diluted with water to a solids content of 0.1-10% by weight, preferably 1-5% by weight, before use. Application to the textile material to be treated can take the form of spraying, nip padding, slop padding, etc. The amount applied is such that 0.01-1% by weight of fluorine, preferably 0.03-0.2% by weight of fluorine, ends up on the textile material. After application, the textile material is dried at temperatures of up to about 120.degree. C. and is then subjected at temperatures of about 130.degree.-190.degree. C., preferably 140.degree.-180.degree. C., to a heat treatment which customarily takes from about 20 seconds to 5 minutes. While the amine oxides of the formulae (3) and (4) remain stable in the preparation of the aqueous dispersions of the present invention, at the temperatures of above 120.degree. C. necessary for fixing the dispersions on the textile fiber they decompose virtually quantitatively (differential thermal gravimetry), which is particularly beneficial for the oil and water repellancy. Since the decomposition products of the emulsifiers used according to the present invention are largely gaseous, they consequently do not interfere with the application through yellowing which might be caused by secondary reactions of the decomposition products.

The fluorine-containing, aqueous polymer dispersions prepared according to the present invention show excellent oil and water repellant effects in textile finishing not only in respect of washing but also in respect of drycleaning resistance. They can be used as a textile finish either alone or combined with other finishes, such as crosslinkers or softeners.

Comparative Example 22 contains as emulsifier a compound of the formula

Compared with the emulsifiers to be used according to the present invention, this compound has the disadvantage that it only fully decomposes at temperatures above 250.degree. C. Moreover, the fluorine-containing component 3 can be used only together with a melamine resin and a zinc nitrate solution. This disadvantage disappears with the dispersions prepared according to the present invention.

GM=total monomer, AAE=acrylic acid ethylperfluoroalkyl ester mixture of the approximate composition:

4-6% of C.sub.6 F.sub.13 CH.sub.2 CH.sub.2 OCOCH.dbd.CH.sub.2

48-58% of C.sub.8 F.sub.17 CH.sub.2 CH.sub.2 OCOCH.dbd.CH.sub.2

8-13% of C.sub.10 F.sub.21 CH.sub.2 CH.sub.2 OCOCH.dbd.CH.sub.2

2-4% of C.sub.12 F.sub.25 CH.sub.2 CH.sub.2 OCOCH.dbd.CH.sub.2

0.3-1.2% of C.sub.14 F.sub.29 CH.sub.2 CH.sub.2 OCOCH.dbd.CH.sub.2

MAE=methacrylic acid ethylperfluoroalkyl ester mixture 0f the approximate composition:

0-1% of C.sub.6 F.sub.13 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

0.4-1.4% of C.sub.8 F.sub.17 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

38-42% of C.sub.10 F.sub.21 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

31-36% of C.sub.12 F.sub.25 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

12-16% of C.sub.14 F.sub.29 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

2-6% of C.sub.16 F.sub.33 CH.sub.2 CH.sub.2 OCOC(CH.sub.3).dbd.CH.sub.2

BA=benzyl acrylate; ABU=acryloylbutylurethane;

NHMA=N-hydroxymethylacrylamide;

IBMA=N-hydroxymethylacrylamide isobutyl ether;

LA=lauryl acrylate; AA=acrylamide; AN=acrylonitrile;

P-Cl=para-chlorobenzyl acrylate;

AB=azodiisobutyramidine dihydrochloride;

B101=C.sub.5 F.sub.11 CHFCH.sub.2 CH.sub.2 N(CH.sub.3).sub.2 O;

N230=nonylphenol condensed with 23 EO;

X080=isotridecyl alcohol condensed with 8 EO;

DMDA=N,N-dimethyldodecylamine N-oxide;

CC=cocoalkyldimethylamine N-oxide;

HN1.dbd.C.sub.8-10 H.sub.17-21 N(CH.sub.3).sub.2 O;

HN9.dbd.C.sub.12 H.sub.25 N(CH.sub.3 (C.sub.4 H.sub.9)O;

CAT1.dbd.C.sub.n F.sub.2n+1 CH.sub.2 CH.sub.2 OCOCH.sub.2 CH.sub.2 N(C.sub.4 H.sub.9).sub.2 xHCl where n=4-12;

CAT2.dbd.C.sub.6-12 F.sub.13-25 (C.sub.2 H.sub.4 O).sub.16 H;

CAT3.dbd.C.sub.6 F.sub.13 CH.sub.2 CH.sub.2 SSO.sub.3 Na.

Application testing of the aqueous fluorine-containing polymer dispersions and comparative examples:

The dispersions of Examples 1, 2 and 18 of the present invention were tested plus for comparison the dispersions 19 to 22.

The finishing liquors were made up in such a way that their fluorine contents were constant and that a predetermined wet pickup after squeezing would produce a defined fluorine add-on on the fabrics to be treated.

The test results in Table 2 were produced with a polyamide taffeta fabric by way of example. In each case the test was carried out as follows:

The polyamide taffeta fabric to be tested was impregnated, squeezed off to a residual level of 50%, dried at 110.degree. C. and heated at 150.degree. C. for three minutes to effect condensation. The fluorine add-on on the fabrics was thus about 0.05% by weight or 0.1% by weight.

The water and oil repellancy effects measured on this polyamide taffeta fabric are summarized below in Table 2.