US3567500A - Fluoroamide-amino polymers and process for imparting oleophobic yet hydrophilic properties to fibrous materials - Google Patents

Abstract

CERTAIN LIQUID PERFLUOROALKYL ESTERS WERE REACTED WITH CERTAIN LIQUID POLYAMINES CONTAINING A PRIMARY: SECONDARY:TERTIARY AMINE RATO OF 1:2:1 TO PRODUCE NEW LIQUID POLYMERIC FLUOROMIDO-AMINO COPOUNDS. THE NEW COMPOUNDS WERE DISSOLVED IN CERTAIN SOLVENTS AND APPOLIED TO COTTON FABRICS THEREBY IMPARTING TO THE TREATED FABRICS OLEPHOBICITY WITH RETAINED HYDROPHILICITY WHICH WAS DURABLE TO REPEATED LAUNDERING.

Description

United States Patent 3,567,500 FLUOROAMIDE-AMINO POLYMERS AND PROCESS FOR HVIPARTING OLEOPHOBIC YET HYDROPHILIC PROPERTIES TO FIBROUS MATERIALS Jerry P. Moreau, New Orleans, and George L. Drake, Jr., and Wilson A. Reeves, Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Apr. 18, 1968, Ser. No. 722,211 Int. Cl. C083 1/44 U.S. Cl. 117-1395 6 Claims ABSTRACT OF THE DISCLOSURE Certain liquid perfluoroalkyl esters were reacted with certain 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 olephobicity 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.

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 oleoprobicity 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 suitably be used to impart oleophobicity and hydrophilic properties of substantially any fibrous material such as cotton, rayon, ramie, jute, wool, paper, carboard, nylon, dacron, or blends of these materials which can be treated with a liquid and dried or cured.

3,567,500 Patented Mar. 2, 1971 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 oleoprobicity 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 s lvent 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 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).

The 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 perfluorooctanoate (EPO).

The polyamines described in this invention are of the general formula:

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 primary:secondaryztertiary amine groups and a molecular weight as high as approximately 1800.

Preferred polyamines are those having molecular weights of about from 600 to 1800, where R is H and a primary:secondaryrtertiary amine group ratio of about 122:1 where Y is X+l. 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 obtained from the reaction of ethyl perfluorooctanoate and a Montrek polyaminewould theoretically consist of a recurring unit containing one secondary amide, two tertiary 'amides and one tertiary amine nitrogens, assuming 100% conversion of both the' secondary as Well as the primary amine groups. However, it would appear that perfluoro 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 the nucleophilicity of the nitrogen as well as facilitate the cleavage of the carbon-ethoxide 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 Montrek polyamine was used to have one available primary amine group for every perfluoro ester group, i.e., a perfluoro ester group for every four nitrogen groups in the recurring chain. By doing so, the mo st efiicierit reaction was obtained in that all the perfluoro 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, result= ingjjfrom the chemical reaction of EPO and Montrek 6 (Mon 6 polyamine, molecular weight approximately 600'), in' a weight ratio of approximately 1:04, is;

Because the reaction of EPO and Mon 6 consists of the formation of an aniide bond at the expense of an 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 ras well as the strong C-F stretching absorptions between 8 and 9a. The spectrum of Mon 6 is characterized by absorption at 3.04 1. and 68 When EPQ reacts with Mon 6 in a weight ratio of 120.4, the IR spectrum of the resulting polgmer shows the complete absence of the ester carbonyi and the presence of two nevi; bands at 5.83; and 6.43 attributed to amide carbonyl and --NH deformation respectively. The latter band is also an indication that secondary 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 perfgram of EPO, then the 1R spectrum (liquid film) of the resulting polymer shoavs the presence of a small amount unreacted EBO- as indicated by the ester carbonykband at '5.57,u.. For this reason a weight of approximately 0.4 gram of Mon 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 polyfluoroalkanoic 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 paddry-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 polyfluo-roalkanoic 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 weightsof the finoro 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 fluoroamide-amino polymer shows the absence of the ester carbonyl band, which appears at about 5 .57,a.

Solution concentrations of the fluoroamide-amino polymers of the instant invention which, are effective in imparting an oleophobic-hydrophilic finish to textiles and cellulosic materials range from as low asabout from 0.9% to 14%. H g

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 dry= ing 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 suflicient to fixe the polymer and evaporate the solvent on the treated material. a

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 onafter 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 fluoroami-de-amino polymer of this invention has values close to those for untreated cotton. l

It is the main advantageof the fluoroamide-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 timet hydrophiiic. This is novel in that all other fluorccarbon 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 polyfiuoro tails. This combination produces a fluoroamido-antiino 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 EPS (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 perfluoro 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.

printcloth. The sample was 2-dipped 2-nipped on a conventional padder to a wet pickup of approximately 80% and dried at 85 C. for 5 minutes of time.

Sample #1 was not cured. Sample #2 was heated at 120 C. for 5 minutes of time.

5 The polymer of the present invention is beyond the S o am le 3 was heated at 150 C. 1n 5 minutes of time.

scope of US. Pat. 3,271,430 in that the polymer of the p instant invention has at least one perfluoro group for The samples were then rinsed in running hot water for every four nitrogen atoms in the polymer backbone. The approximately 30 minutes, padded to remove excess water, polymer of the prior art has a lower ratio of perfluoro 10 then allowed to line-dry and equilibrate overnight. The group for every nitrogen atomthe most concentrated effect of curing conditions on the oleophobicity and hybeing 1:10, respectively. This is important because a drophobicity of the EPO-Mon 6 finish is shown in Table I.

Table I Oil Rating Percent Fabric Cure add- Spray After Alter Samples conditions on rating Original laundering extraction 1 No cure 5.4 110 110 100 2 120 0J5 5.0 o 110 110 100 3 150 o./ 5. 4 0 120 120 90 and equilibration.

4 Two and a half hours in Soxhlet apparatus with tetraehloroethylene, followed by a hot water-rinse, padding to remove excesswater, then (line drying and) equilibration.

higher concentration of perfluoro groups to nitrogens is 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 perfluoro groups is much more soluble in water.

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

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.

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 :3M Co., Technical Bulletin on 3M Brand Textile Chemicals, 1962.

Spray Rating (SR): AATCC Standard Test Method 22- EXAMPLE 1 To 0.75 g. Montrek 6 (Mon 6 polyethylenimine, molecular weight approximately 600) was added 1.50 g. of ethyl perfluorooctanoate (EPO) at room temperature, whereby a mild exothermic reaction took place very rapidly upon thorough mixing. Approximately minutes after mixing a slightly yellow, viscous liquid polymer was formed which had an infrared (IR) spectrum (liquid film) showing two bands at 5.83,:1. and 6.4 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 6. The IR spectrum of the polymer also showed the absence of the ester carbonyl band at 5.57;. indicating that EPO was completely reacted. The fiuoroamide-amino polymer was dissolved in 27.75 grams of Dowanol EE (monoethyl ether of ethylene glycol) and the solution used to treat three 7 g. samples of desized, scoured, and bleached cotton EXAMPLE 2 Three solutions of ethyl perfluorooctanoate andMontrek 6 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 describer 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 of time. The effect of various molecular weight Montrek polyamines on the oleophobicity and hydrophobicity of the EPO-Mon finish is shown in Table II.

To 1.60 g. of Montrek 6 was added 2.00 g. of ethyl perfluorobutyrate and mixed thoroughly. After sufficient 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 add-on, spray rating, and oil rating were 5.3, O, 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.

TABLE III Oil Rating Percent Spray After After Solvents add-on rating Original laundering l extraction CCl 1. 9 100 100 90 Dowanol EE 3. 2 0 100 110 90 1 10 home launderings.

EXAMPLE Ethyl perfiuorooctanoate (12.40 g.) and Montrek 6 (4.69 g.) were allowed to react by mixing thoroughly. After 15 minutes, a viscous liquid fiuoroamide-amino polymer was obtained having an IR spectrum as described in Example 1. The fluoroamide-amino polymer was dissolved in 106.64 g. of Dowanol EE to give a solution based on the weight of ester. A portion of this solution was shaken with an equal weight of solvent to give a 5% 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 10% 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.

TABLE V.DEPOSITION OF SOIL ON FLUOROCARBON FINISHES DURING HOME LAUNDERING Wt. Degree 0 R percent of soiling,

Treatment add-on percent SR Before After A 4. 1 44. 4 100 100 100 2. 2 44.9 100 100 100 B 3. 4 27. 2 100 100 100 1. 5 27. 4 100 100 90 C 2. 5 33.5 100 120 100 1. 0 34. 2 100 120 90 EPO,Mon 6 4. 5 18.9 0 100 90 2. 1 12. 1 0 100 80 Control- 3. 6 0 0 0 l Twenty 6"x6 untreated controls soiled with 10% carbon black in mineral oil by padding through a 1% C01 solution.

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

3 Commercial fluorocarbon treatment at different add-ens.

TABLE IV 5 Oil Rating Concentration Concentration of of polymer, fluoroester, Percent Percent Percent Spray After After percent percent addon N F rating Original extraction Laundering l 5 home laundcrings.

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;. and 6.50;, which were not present in the IR spectrum of an untreated cotton sample run by the same technique. A 5% perfluorooctanoate2% Montrek 6 polyamine solution was found to be optimum concentration with respect to add-on, hand, 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 Cotton printcloth samples were treated with commercial fluorocarbon emulsions known for imparting hydrophobic as well as oleophobic properties. The samples were treated in accordance with the respective companies literature. The effect of soil redeposition on the oleophobic, hydrophilic EPO-Mon 6 finish was compared with the eifect of soil redeposition on these commercial fluorocarbon finishes and an untreated control, by washing samples (3 x 4"), together with 20 (6" x 6") oily soiled untreated controls in a tumble-type domestic washer. 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 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 fluoramide to amine group ratio.

(2) A method of preparing a liquid fluoroamideamino polymer comprising recurring units represented by the formula in which said polymer contains an oleophobic long chain perfluoroalkyl group and hydrophilicNH 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,u., attributed to amide carbonyl and -NHgroup deformation, respectively,

(3) A proces for imparting oleophobicity to cellulosic textiles while retaining hydrophilic 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 soilds 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 fluoramide-amino polymer of claim 2. in a solvent selected from the group consisting of monoethyl ether of ethylene glycol, diethyl ether of ethylene glycol, acetone, ethanol, and N,N-diemethylformamide, 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. A process for imparting oleophobicity to cellulosic textiles while retaining hydrophilic properties of the textile, whereby the treated textiles are made resistant to oily wetting but not resistant to oily soils and stain but allows for easier cleanability and less soil redeposition during laundering, comprising impregnating the cellulosic textile with about from 0.875% to 14% by weight of a fluoroamide-amino polymer having recurring units of the structure said polymer having a fluorine to nitrogen weight ratio of about 5.1 and being characterized by infrared absorption bands at 5. 83 and 6.43,u., in a solvent selected from the group consisting of monoethyl ether of ethylene glycol, diethyl ether of ethylene glycol, acetone, ethanol, and N,N-dirnethylformamide, 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 drying the wet impregnated textile for about from 4 to 10 minutes, at about from to 0, without the need of higher curing temperatures.

2. The process of claim 1 wherein the solvent is monoethyl ether of ethylene glycol.

3. The process of claim '1 wherein the solvent is diethyl ether of ethylene glycol.

4. The process of claim 1 wherein the solvent is acetone.

5. The process of claim 1 wherein the solvent is ethanol.

6. The process of claim 1 wherein the solvent is N,N- dimethylformamide.

References Cited UNITED STATES PATENTS 3,198,754 8/1965 Ahlbrecht et al. 117139.5X 3,392,046 7/1968 Marder l17143 3,420,697 1/1969 Sweeney et al. 117-121 MURRAY KATZ, Primary Examiner T. G. DAVIS, Assistant Examiner US. Cl. X.R.