US3769307A

US3769307A - Fluoroamide-amino polymers and process for imparting oleophobic yet hydrophilic properties to fibrous materials

Info

Publication number: US3769307A
Authority: US
Inventors: J Moreau; G Drake; W Reeves
Original assignee: US Department of Agriculture USDA
Current assignee: US Department of Agriculture USDA
Priority date: 1968-04-18
Filing date: 1970-09-18
Publication date: 1973-10-30
Anticipated expiration: 1990-10-30
Also published as: US3567500A

Abstract

CERTAIN NEAT LIQUID PERFLUOROALKYL ESTERS WERE REACTED WITH CERTAIN NEAT L IQUID POLYAMINES CONTAINING A PRIMARY: SECONDARY:TERTIARY AMINE RATIO OF 1:2:1 TO PRODUCE NEW LIQUID POLYMERIC FLUOROAMIDO-AMINO COMPOUNDS. THE NEW COMPOUNDS WERE DISSOLVED IN CERTAIN SOLVENTS AND APPLIED TO COTTON FABRICS THEREBY IMPARTING TO THE TREATED FABRICS OLEOPHOBICITY WITH RETAINED HYDROPHILICITY WHICH WAS DURAABLE TO REPEATED LAUNDERING.

Description

United States Paten O fi 3,769,307 Patented Oct. 30, 1973 Int. Cl. C09f 7/00 US. Cl. 260-4045 2 Claims ABSTRACT OF THE DISCLOSURE Certain neat liquid perfiuoroalkyl esters were reacted with certain neat liquid polyamines containing a primary: secondaryztertiary amine ratio of 1:2:1 to produce new liquid polymeric fluoroamido-amino compounds. The new compounds were dissolved in certain solvents and applied to cotton fabrics thereby imparting to the treated fabrics oleophobicity with' retained hydrophilicity which was durable to repeated laundering.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This application is a division of Ser. No. 772,211, filed Apr. 18, 1968, now US. Pat. No. 3,567,500.

The invention described herein relates to new fluorine and nitrogen containing polymers, to a process for their production, and to processes of employing these polymers in producing durable oil and stain resistant, yet hydrophilic, properties to certain fibrous materials.

Although not limited thereto, this invention particularly provides a method for treating textiles and cellulosic materials with a fluorine-nitrogen polymer so as to obtain a durable finish having high oleophobicity yet hydrophilic properties.

Another object of this invention is to provide a durable oil and stain repellent finish with hydrophilic properties which, when applied to textiles and cellulosic materials, will be resistant to home laundering and dry cleaning without imparting adverse effects to strength, hand, odor, or color.

- Another object of this invention is to chemically incorporate a long-chain polyfluorinated alkyl group into a polyamine for treating textiles and cellulosic materials so as to make the treated material highly resistant to wetting by an oily medium but not resistant to wetting by an aqueous medium.

The novelty of this invention lies in the fact that the process provides a durable finish to textiles and cellulosic materials which is both oleophobic and hydrophilic at the same time. Therefore, the present invention is unlike other fluorocarbon treated materials which give both oil and water repellency.

As a consequence of this resistance to wetting by oily media the treated material is more resistant to staining by oily media but at the same time, because of its relative ease of wetting by an aqueous medium, the finish allows for easier cleanability and less soil redeposition in an aqueous medium.

The process of this invention can be used to impart oleophobicity and hydrophilic properties of substantially any fibrous material such as cotton, rayon, ramie, jute, wool, paper, cardboard, nylon, Dacron, or blends of these materials which can be treated with a liquid and dried or cured.

When a textile is being impregnated, it is of advantage to remove excess impregnating liquor by passing the textile through squeeze rolls prior to drying or curing the wetted textile. It is also advantageous to dry the textile at about C. to C. for a period of time of ca. 5 min.

The degree of oleophobicity imparted to a textile by these fluorine and nitrogen containing resins can be 'varied from a low degree to a very high degree by varying the polymer applied to the textile.

Other objects of the invention will be apparent from the discussion which follows. It is understood that such discussion will serve as a means of description and explanation only and therefore not serve as a means of limitation, since various changes therein may be made by those skilled in the art without departing from the scope of this invention.

By the process of the present invention a mixture of a polyfluoroalkanoic ester and a polyamine are allowed to react at room temperature either in the presence or absence of a solvent to produce a fluoroamide-amino polymer. The preferred method is to allow the reagents to react as neat liquids. The reaction is exothermic as observed by a warming of the reaction flask when the reactants are mixed in the absence of solvent. After a few minutes of reaction time, the resulting polymer may then be taken up in a solvent.

Various inert solvents may be used in forming the polymer. and/or in its application to the desired cellulosic material. Among these solvents are halogenated solvents, such as carbon tetrachloride and the like; amide solvents, such as N,N-dimethylformamide and the like; ether solvents, such as diethyl ether or the monoethyl ether of ethylene glycol and the like; and ketone solvents, such as acetone and the like, alcohol solvents, such as ethanol and the like. Emulsion systems of water or water and various other solvents may also be used to apply the polymer. Preferred solvents are the glycol ether solvents such as Dowanol EE (monoethyl ether of ethylene glycol).

'Ihe polyfluoroalkanoic esters described in this invention are of the general formula:

in which R; is of straight or branched carbon chain which is partially or completely fiuorinated, containing from about 3 to about 9 carbon atoms and R is any alkyl, aryl, or alkenyl group such as ethyl, phenyl, or propenyl. A preferred polyfluoroalkanoic ester would be ethyl perflugigoctanoate (EPO), which has a molecular weight of The polyamines described in this invention are of the general formula:

NH: X

in which R is hydrogen, methyl, ethyl or phenyl; and in which X and Y can be 1 or a plurality of such groups and wherein a number or combination of numbers of X and Y groups are within certain desired ratio limits of primaryzsecondaryztertiary amine groups and a molecular weight as high as approximately 1800.

Preferred polyamines are those having molecular weights of about 600 to 1800, where R is H, and which have a primaryzsecondary:tertiary amine group ratio of about 1:2:1. However, it should be realized that such polyamines may contain branching wherever there is an available hydrogen on the nitrogen atoms, so long as the ratio of amine groups in the recurring unit remains about 1:2: 1. Such preferred polyamines are those obtained from the polymerization of azacyclopropane or 2-methyl azacyclopropane and specifically to the polyamines commercially available by the trade name of Montrek (polyethylenimine) though not limited thereto.

Since esters of perfiuoro acids react with both primary and secondary amines to produce amides, the product ob tained from the reaction of ethyl perfluorooctanoate and a polyamine would theoretically consist of a recurring unit containing one secondary amide, two tertiary amides and one tertiary amine nitrogen, assuming 100% conversion of both the secondary as well as the primary amine groups. However, it would appear that perfiuoro alkyl esters would preferentially react with the primary amines rather than the secondary amines. This is because primary amines could possibly form a cyclic hydrogen-bonded intermediate which should increase nucleophilicity of the nitrogen as well as facilitate the cleavage of the carbonethoxide bond. Such a cyclic intermediate would not be possible with secondary amines. Also, a major contributing factor for preferential reaction with primary amines would be that the primary amines are less sterically hindered than secondary amines.

In the work of the present invention, enough polyamine was used to have one available primary amine group for every perfiuoro ester group, i.e., a perfiuoro ester group for every four nitrogen groups in the recurring chain. By doing so, the most efficient reaction was obtained in that all the perfiuoro ester was reacted in the shortest possible time and with the least amount of trouble, i.e., without the aid of catalyst or external heat. This also allows for more hydrophilic groups in the backbone of the polymer since the NH groups of the secondary amines remain unreacted. Therefore, not wishing to make the process of the present invention dependent on any specific theory, it appears that the recurring unit of the fluoroamide-amino polymer, resulting from the chemical reaction of EPO and Montrek 6 (Mon 6 polyamine, molecular weight approximately 600), in a weight ratio of approximately 1:0.4, is:

CHrCHa-N-CI-Iz-CH:NCH;CHr-N III (3H2 I I NH Because the reaction of EPO and Mon 6 consists of the formation of an amide bond at the expense of an 7 ester bond it was advantageous to follow the reaction by using infrared (IR) spectroscopy. The IR spectrum of EPO shows a strong carbonyl absorption at 5.57,a as well as the strong C=F stretching absorptions between 8 and 9 The spectrum of Mon 6 is characterized by absorption at 3.04 11. and 6.8;/.. When E'PO reacts with Mon 6 in a weight ratio of 120.4, the IR spectrum of the resulting polymer shows the complete absence of the ester carbonyl and the presence of two new bands at 5.83 and 6.43;, attributed to amide carbonyl and NH deformation respectively. The latter band is also an indication that seconadry amides are formed since tertiary amides do not exhibit this absorption. If the weight of Mon 6 used to react with one gram of EPO is decreased, i.e., to 0.3 gram per gram of EPO, then the IR spectrum (liquid film) of the resulting polymer shows the presence of a small amount unreacted EPO-as indicated by the ester carbonyl band at 5.57 t. For this reason a weight of approximately 9.4 gram of Mom 6 was found to be the minimum amount which would react with one gram of EPO at room temperature within 10 minutes. This weight ratio is calculated to be approximately a 1:1 molar ratio of primary amine group to ester. Mon 6 may also be used in slight excess (i.e., 0.5 gram per gram of EPO) if so desired, to better insure complete reaction of EPO.

After allowing a few minutes for reaction time, the reaction product of the polyfiuoroalkanoic ester and the polyamine can be dissolved in a suitable solvent and used to treat textiles, cellulosic and other fibrous materials by any of a variety of techniques, such as padding, spraying, coating, etc., and such, as those known to those skilled in the art. For cotton fabric the conventional pad-dry-cure technique is ideally suited, although any other method by which the treating solution can be deposited on the textile or cellulosic material may also be employed. A distinct advantage of this process and the preferred method is the elimination of the cure step, which saves time and avoids high temperatures which may weaken or discolor the fabric.

Although the treating solution may be prepared in other equally effective ways, the preferred method of preparation is to mix the polyfluoroalkanoic ester and enough undiluted polyamine in a determined weight ratio so as to react all of the fiuoro ester, followed by the addition of the suitable amount of solvent. The weight ratio of the reactants is determined by the respective molecular weights of the fluoro ester and the recurring unit of the polyamine. All of the fiuoro ester is considered to have reacted when an IR spectrum of the newly formed fiuoroamide-amino polymer shows the absence of the ester carbonyl band, which appears at about 5.57,a.

Solution concentrations of the fiuoroamide-amino polymers of the instant invention which are effective in imparting an oleophobic-hydrophilic finish' to textiles and cellulosic materials range from as low as about from 0.9% to 14%.

After the desired material has been impregnated with the treating solution, the fluoroamide-amino polymer is fixed on the material upon removal of the solvent by suitable means. Solvent removal may be hastened by drying at about C. in a forced-draft oven, or by any other means familiar to those skilled in the art, followed by further heating at higher curing temperatures, i.e., about 160 C. However, it is an advantage of the process of the present invention that drying at about C. for 6 minutes is sutficient to fix the polymer and evaporate the solvent on the treated material.

Cotton print fabric which has been padded with solutions of the fluoroamide-amino polymer prepared from EPO and Mon 6, then dried at 85 C. for 6 minutes retains its high oil repellency after repeated home laundering or after Soxhlet extraction with tetrachloroethylene. Simultaneously, the cotton print fabric is also made hydrophilic by this treatment, that is, gives a spray rating of less than 50, or will not sustain a drop of water for 30 seconds, without wetting the fabric.

For several of its physical properties, such as flex abrasion resistance, air permeability, moisture content and regain, stiffness, tear strength, and breaking strength, cotton printcloth treated with the fiuoroamide-amino polymer of this invention has values close to those for untreated cotton.

It is the main advantage of the fiuoroamide-amino polymers of this present invention that it imparts to cellulosic materials such as cotton fabric and other textiles, a durable finish which is highly oleophobic but at the same time hydrophilic. This is novel in that all other fluorocarbon finishes as far as we know give water repellency as well as oil repellency. The hydrophilicity imparted to the finish of the present invention is attributed mainly to the -NH- groups present in the polymer backbone and the oleophobic properties are obtained because of the long-chain polyfluoro tails. This combination produces a fiuoroamide-amino polymer which is a viscous fluid and flows even after standing six months as a concentrate. This is significant in that the polymer obtained from the reaction of EPO (or the acid chloride) with monomeric ethylenimine becomes a solid upon standing at room temperature (U.S. 3,198,754).

Presumably, the solid polymer is formed because there is a perfiuoro group for every nitrogen in the polymer backbone. This would also explain why the solid polymer does not have hydrophilic properties since it does not contain -NH- groups in the polymer backbone.

The polymer of the present invention is beyond the scope of US. Pat. 3,271,430 in that the polymer of the instant invention has at least one perfiuoro group for every four nitrogen atoms in the polymer backbone. The polymer of the prior art has a lower ratio of perfiuoro group for every nitrogen atomthe most concentrated being 1:10, respectively. This is important because a higher concentration of perfiuoro groups to nitrogens is Sample #1 was not cured. Sample was heated at 120 C. for 5 minutes. Sample #3 was heated at 150 C. for 5 minutes.

The samples were then rinsed in running hot water for approximately minutes, padded to remove excess water, then allowed to line-dry and equilibrate overnight. The eifect of curing conditions on the oleophobicity and hydrophobicity of the EPO-Mon 6 finish is shown in Table I.

I Spray rating (AATCC test 22-1964). 11 Oil rating (3M Technical Information Bulletin, 1962). 0 Five home launderings in tumble-type washing machine l'ollowed by 1 tumble drying and equilibration.

d Two and a half hours in Soxhlet apparatus with tetrachloroethylene, followed by a hot water rinse, padding to remove excess water, then (line drying and) equilibration.

needed to give the desired oil repellency to a treated fabric. The higher concentration is also needed to give durability against laundering since the polymer containing the lower concentration of perfiuoro groups is much more soluble in water.

However, it is also a disadvantage of the present invention to have too high a ratio of perfiuoro groups to nitrogen atoms, i.e., 1:1 is too high as compared to 1:4. When the ratio of perfiuoro groups to nitrogen atoms is 1:1 (US. 3,198,754), no hydrophilic -NH groups are present in the polymer backbone; therefore, textiles treated with this polymer exhibit hydrophobicity instead of hydrophilicity.

The oleophobicity of the polymer is advantageous in that it imparts to textiles and cellulosic materials a finish which is resistant to oil-staining. The hydrophilicity is advantageous in that it allows for easier soil removal and less soil redeposition on the finish in an aqueous medium.

The invention is further illustrated but not limited by the following examples, showing the best method contemplated for practicing the invention. 7

In the examples provided below the following test methods were used to demonstrate the oleophobic and hydrophilic properties of fabrics provided by this invention:

Oil Rating (OR) Test: 3 M Co., Technical Bulletin on 3 M Brank Textile Chemicals, 1962. Spray Rating (SR): AATCC Standard Test Method 22- EXAMPLE 1 To 0.75 g. (0.0013 mole) Montrek 6 (Mon 6 polyethylenimine, molecular weight approximately 600) was added 1.50 g. (0.0034 mole) of ethyl perfiuorooctanoate (EPO) at room temperature, whereby a mild exothermic reaction took place very rapidly upon thorough mixing. Approximately 10 minutes after mixing a slightly yellow, viscous liquid polymer was formed which had an infrared (IR) spectrum (liquid film) showing two bands at 5.83m and 6.43 These bands were attributed to the amide carbonyl and -NH- deformation respectively and were not present in the IR spectrum (liquid film) of EPO or Mon EXAMPLE 2 Three solutions of ethyl perfiuorooctanoate and of the following Montrek polyamines were prepared in the same manner as described in Example 1 using polyamines of various molecular weights-Montrek 6 (M.W. approx. 600); Montrek 12 (M.W. approx. 1200); Montrek 18 (M.W. approx. 1800).

Samples of cotton printcloth were treated with the three respective solutions above, in the same manner as described in Example 1, except these samples were dried at C. for 7 minutes with no curing, and after rinsing they were dried again at 80 C. for 7 minutes. The efiect of various molecular weight Montrek polyamines on the oleophobicity and hydrophobicity of the EPO-Mon finish is shown in Table 11.

2.00 g. (0.0083 mole) of ethyl perfluorobutyrate (molecular weight 242) and mixed thoroughly. After sufiicient time for reaction (approx. 15 min), the polymer was dissolved in 26.40 g. of Dowanol EE. This solution was used to treat a sample of cotton printcloth employing the procedure described in Example 2. The percent addon, spray rating, and oil rating were 5.3, 0, and 50 respectively.

EXAMPLE 4 Ethyl perfluorooctanoate and Montrek 6 were reacted as described in Example 1, except the reactants were diluted with carbon tetrachloride before mixing. After 15 minutes an infrared spectrum was taken of this solution, which showed a very small carbonyl absorption at 5.6,u, indicating unreacted ester.

Another solution was prepared as above except Dowanol EE was used instead of carbon tetrachloride. Two samples of cotton printcloth were then treated with the respective solutions as described in Example 2. The effect of dilution of materials before formation of the polymer is shown as relates to oleophobicity and hydrophilicity in the properties of the EPO-Mon 6 finish in Table III.

Ethyl perfluorooctanoate (12.40 g.; 0.028 mole) and Montrek 6 (4.96 g., 0.0082 mole) were allowed to react by mixing thoroughly. After 15 minutes, a viscous liquid fluoroamide-amino polymer was obtained having an IR spectrum as described in Example 1. The fluoroamideamino polymer was dissolved in 106.64 g. of Dowanol EE to give a 10% solution based on the weight of ester. A portion of this solution was shaken with an equal weight of solvent to give a solution, a portion of which was mixed with an equal weight of solvent to give a 2.5% solution, and so on until five solutions were obtained ranging in concentration from to 0.63%.

Five samples of cotton printcloth were treated with the respective solutions as described in Example 1, except these samples were dried again after the hot water rinse. The effect of concentration on the oleophobicity and hydrophilicity of the EPO-Mon 6 finish is shown in Table IV.

8 ing samples 3" x 4"), together with (6" x 6") oily soiled untreated controls in a tumble-type domestic weather. The treated samples were washed five times using 20 fresh soiled untreated controls with each Wash. The samples were tumble dried for minutes after the fifth wash.

A green tristimulus filter was used to obtain an average reflectance reading from 8 readings on the test samples of two thicknesses against a white background of three large filter papers. Readings were made before washing and after the fifth washing. The degree of soiling was determined from the formula Percent soiled= X 100 where R is the reflectance of the original treated sample before soiling and R is the reflectance of the soiled sample after the fifth wash. Results in Table V of this comparative evaluation are shown below. The EPO-Mon 6 finish exhibited less soil deposition with respect to add-on than any of the commercial finishes which are not hydrophilic as shown by spray ratings.

TABLE V.DEPOSITION OF SOIL ON FLUOROCARBON FINISHES DURING HOME LA'UNDERING l Twenty 6" x 6 untreated controls soiled with 10% carbon black in mineral oil by padding through a 1% 001 solution.

After 5 redeposition home launderings in a tumble-type washing machine, using 20 fresh soiled untreated controls with each laundering.

3 Commercial fluorocarbon treatment at difierent add-ens.

Except for the samples with add-on below 1%, chemical analyses of the originally treated cotton samples show a fluorine to nitrogen wt. ratio of 5.5-5.9, which is close to the calculated fluorine to nitrogen wt. ratio (5.1) for one perfluoro group for every primary amine. An IR spectrum was obtained on an EPO-Mon 6 treated cotton sample by the differential technique, in which the treated sample was run against an untreated control-both in KBr discs. Absorption bands were present at 5.88 4 and 650 which were not present in the IR spectrum of an untreated cotton sample run by the same technique. A 5% perfluorooctanoate-2% Montrek 6 polyamine solution was found to be optimum concentration with respect to add-on, band, color and durability to laundering.

A sample of the fluoroamide-amino polymer obtained from the reaction of EPO and Mon 6 in a ratio of approximately 1:0.4 remained a viscous liquid, which flowed even after standing at room temperature for over one year.

EXAMPLE 6 fluorocarbon finishes and an untreated control, by wash- 75 where R is hydrogen, alkyl, or aryl, and R, can be a straight or branched carbon chain of about 3 to 9 carbon atoms which can be partially or completely fluorinated, and where X and Y can be equal to 1 or a plurality, or X and Y can be any combination of numbers predetermined as a preferred fluoroamide to amine group ratio.

(2) A method of preparing a liquid fluoroamide-amino polymer comprising recurring units represented by the formula in which said polymer contains an oleophobic long chain perfluoroalkyl group and hydrophilic NH groups, and said polymer has a fluorine to nitrogen weight ratio of about 5.1 and the polymer is characterized by infrared absorption bands at 5.83 1. and 6.43 1., attributed to amide carbonyl and NH group deformation, respectively, and

.(3) A process for imparting oleophobicity to cellulosic textiles while retaining hydrophilc properties of the textile, whereby the treated textiles are made resistant to oily wetting but not resistant to water wetting" which makes the treated textiles resistant to oily soils and stain but allows for easier cleanability and less soil redeposition during ,laundering, comprising:

(a), Impregnating the cellulosic textile with about from 0.875% to 14% by weight of the fluoroamide-amino polymer of paragraph (2), above, in a solvent selected from the group consisting of monoethyl ether of ethylene glycol, diethyl ether of ethylene glycol, acetone, ethanol, and N,'-N-dimethylformamide, to obtain a nitrogen content of about from 0.07% to 0.80% and a fluorine content of about from 0.31% to 4.71% deposited on the textile, and

(b) Drying the wet impregnated textile for about from 4 to minutes of time, at about from 80 to 100 0., without the need of higher curing temperatures.

We claim:

1 0 1. A liquid fluoroamide-amino polymer having a molecular weight in the range of about from 1700 to 5700, with recurring units represented by the formula L Jy and infrared absorption bands at 5.83 and 6.43 attributed to amide carbonyl and NH group deformation, respectively, and wherein x is an integer from 3-10 and y is an integer selected to provide a ratio of 1:2:1 of primaryzsecondaryztertiary amino groups respectively.

References Cited UNITED STATES PATENTS 3,271,430 9/1966 Teumac 260-4045 3,200,106 8/1965 Dickson et al 260-404.5 3,428,709 2/ 1969 Kleiner 260404.5 3,475,434 10/1969 Knell 260-4045 LEWIS GO'ITS, Primary Examiner G. HOLLRAH, Assistant Examiner US. Cl. X.R. 260-561 HL