Softening of textile materials

BACKGROUND OF INVENTION (1) Field of invention

This invention relates to the treatment of textile ma- 20 terials and, more particularly, it concerns a process for softening textile materials in a repetitious but generally discontinuous cycle which involves soiling, laundering, rinsing, soiling, etc.

The use of softening agents to improve softness or 25 “hand” of textile materials is well known. Aside from imparting softness, the treatment of textile materials with softening agents generally prevents the accumulation of static electric charges and makes the ironing of such materials easier. Only in the past two decades have ³⁰softening agents become generally known by the housewife. Prior to this time, soap residues provided the same effect of improved “hand” or softness. With the advent of synthetic detergents which effectively remove fatty residues from the textile material, this benefit disap- ³⁵peared.

Synthetic detergents are generally used in conjunction with builder materials such as alkali metal carbonates, silicates and/or phosphates. These so-called “builder materials” tend to react with the metal ions ⁴⁰present in the wash liquor, precipitating out salts which deposit on the fibers of the textile material being laundered. Deposited mineral salts weaken the laundered fabrics, particularly at those points where the fabric is exposed to friction and creasing such as at the collar and ₄cuffs. It has been found that treatment of these laundered textiles with softening agents not only soften the textiles, but also prolong their useful life.

Most of the softening agents presently used in home laundry situations are cationic surface active agents having at least one long alkyl radical usually containing from 16 to 18 carbon atoms. These softening compounds are not compatible with anionic synthetic detergents which are used in most heavy-duty detergents and, thus, are employed only during the rinse cycle. After a wash _ggcycle in which an anionic synthetic detergent is used, variable amounts of such detergent compound remain on the textile. This residual anionic detergent compound will react, during the rinse cycle, with any cationic softening additive causing precipitation and, thus, inactivation θθ of the softener. Any interaction between the detergent compound and softener makes it difficult to achieve a uniform desirable degree of softening. Additionally, this interaction can result in a degree of deposition on the .textile material which causes waterproofing and reduced _0gabsorbency.

Another disagreeable feature of cationic softening agents is that those which have adsorbed to the softened textile can interact upon subsequent laundering with an anionic synthetic detergent to become locked in place on the surface of the textile material with consequent buildup of hydrophobic material and waterproofing.

Due to yellowing associated with the use of cationic softeners and the discoloration which inherently develops in cotton fabrics on aging, it is desirable to add a brightening agent to softener formulations. These brighteners counteract the yellow hue of the fabric by giving off a blue-white fluorescence. Addition of brighteners to textile softener formulations intended for household use is common. Such brightener/softener formulations are greatly preferred by the average housewife.

The best and most commonly used brighteners, however, are inefficient when used in conjunction with cationic softeners. The reasons for this are not entirely understood, but it has been shown that the brightness conferred to cotton by a given amount of brightener when used in conjunction with a cationic softener is only onequarter to one-third as much as that given by the same amount of brightener when it is applied to the cloth from an anionic detergent formulation or from distilled water. Since brightener compounds are extremely expensive, a softener formulation which permits more efficient brightener usage is highly desirable.

Another problem encountered in using the common cotton brighteners in softener formulations is that there is an upper limit to the amount of brightener which can be incorporated into such a formulation. This severely limits the degree of brightening which can be conferred to the cloth by cationic softener formulations.

(2) Description of the prior art

The lower homologs of the softening agents which have been found to be useful in the process of the present invention are well known as synthetic detergent compounds being disclosed in the following patents: See U.S. Pat. 3,-007,784 (Nov. 7, 1961), U.S. Pat. 3,047,579 (July 3, 1962) and U.S. Pat. 3,252,979 (May 24, 1966). There is nothing in the art that indicates that the higher homologs of these detergent compounds would have softening characteristics.

SUMMARY OF INVENTION

It has been discovered that excellent results can be obtained by employing a softening process comprising the step of treating textile materials, which have been previously laundered with a synthetic detergent, with an aqueous solution consisting essentially of:

(a) from 0.001% to about 2.0% of a textile softener having the formula

Ri I R—N ---► O

R² wherein R is a straight or branched carbon chain containing 20 to 30 carbon atoms selected from the group consisting of alkyl and alkenyl groups and wherein said alkyl and alkenyl groups contain 0-2 hydroxyl substituents, 0-5 ether linkages, 0-2 chlorine atoms and 0-1 amide linkage, R¹ is an alkyl group containing from 1 to 20 carbon atoms and wherein said alkyl group contains 0-2 hydroxyl substituents, 0-5 ether linkages, 0-2 chlorine atoms and 0-1 amide linkage, and R² is an alkyl group containing 1 to 3 carbon atoms selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, 2-hydrOxyethyl and 2-hydroxypropyl, and wherein R¹ and R² can be joined to form a heterocyclic group containing 4 to 6 hydrocarbon groups, and (b) the balance being water, all percentages being by weight.

As an embodiment of the present invention, the softening agents described above can be added,, alone or in combination, in small amounts to the usual rinsing bath. Where the softening agents are so added, it is preferred that the rinse solution contain from about 0.001% -to

3,554,784 about 0.05% softening agent by weight. For best softening results, it is preferred that the rinse solution should contain from about 0.002% to about 0.01% softening agent by weight.

As another embodiment of the present invention, the softening agents described above can be used, alone or in combination, for treatment of textile materials in mill operation, as for example by “padding on.” In such processes, the fabrics are dipped into an equeous dispersion of from about 0.05% to about 2% by weight of the softening agents of this invention; preferably from about 0.2% to about 1%. As the fabric emerges from the aqueous dispersion, excess liquid is squeezed out between a pair of rolls. The fabric is then dried, whereupon the softening agent which is entrained in the wet fabric remains on the fabric.

It has been discovered that when filaments, fibers, threads, skeins, hanks, yarns, woven fabrics, etc., either synthetic as nylon, acrylics and polyesters or cellulosic such as cotton, viscose rayon, Cuprammonium rayon and cellulose acetate and like materials, are treated with aqueous solutions or dispersions containing small amounts of the softening agents of this invention, they are softened to a marked degree and in general the useful life of the material is prolonged. It has also been discovered that when non-woven fabrics and papers, e.g., tissues, napkins, and paper towels, are treated with small amounts of the softening agents of this invention that they also become softened to a marked degree.

Besides the softening properties demonstrated by the softening agents of the present invention, the agents demonstrate many advantages not obtainable with the cationic softening agents. The softening agents of the present invention do not interact with anionic detergents and are easily removed by subsequent laundering. Therefore they do not cause waterproofing or buildup of hydrophobic material on the treated textile material.

It has been discovered that formulations containing brightener compounds and the softening agents of the present invention effectively brighten fabrics whereas corresponding cationic softener formulations containing brighteners at the same level do not effectively brighten. Using the softening agents of the present invention, it has also been found that the brightening level is not limited as it is in cationic softening brightener formulations.

Softening agents of this invention which are preferably employed, alone or in combination, in the process of this invention are generically described as follows:

Ri

I

R-N ---> O wherein R is a straight or branched carbon chain containing 20 to 26 carbon atoms selected from the group consisting of alkyl and alkenyl groups and wherein said alkyl and alkenyl groups contain 0-2 hydroxyl substituents, and R¹ and R² are alkyl groups containing 1 to 3 carbon atoms selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, 2-hydroxyethyl and 2-hydroxypropyl.

Specific examples of the softening agents which can be used most effectively in the process of this invention, alone or in combination, are as follows:

Eicosyl-bis-(/3-hydroxyethyl)amine oxide Eicosyldimethylamine oxide Eicosyldiethylamine oxide

Docosyldimethylamine oxide

Docosyldiethylamine oxide

Docosyl-bis- (/3-hydroxyethyl) amine oxide Tetracosyldimethylamine oxide

Tetracosyl-bis (/3-hydroxyethyl) amine oxide Hexacosyldimethylamine oxide Hexacosyl-bis(/3-hydroxyethyl)amine oxide.

Examples of other preferred softening agents which can suitably be employed in the process of the present invention, alone or in combination are as follows: /3-hydroxyeicosyldimethylamine oxide Eicosylmethylethylamine oxide Eicosyldiethylamine oxide 2-eicosyldiethylamine oxide Heneicosyldimethylamine oxide Heneicosyldiethylamine oxide 6-docosylmethylethylamine oxide Docosyldiethylamine oxide Tricosyldimethylamine oxide Tricosyldiethylamine oxide Tetracosylmethylethylamine oxide 12-tetracosyldimethylamine oxide Tetracosyldiethylamine oxide /3-hydroxytetracosyldimethylamine oxide Pentacosyldimethylamine oxide Pentacosyldiethylamine oxide Hexacosyldiethylamine oxide.

Examples of other softening agents which are useful in the process of this invention, alone or in combination, are as follows:

/3-Methoxydocosyldimethylamine oxide /3-Chlorotricosyldimethylamine oxide Heptacosyldimethylamine oxide Heptacosyldiethylamine oxide Octacosyldimethylamine oxide Octacosylmethylethylamine oxide Octacosyl-bis- (/3-hydroxyethyl) amine oxide Octacosyldiethylamine oxide Nonacosyldimethylamine oxide Nonacosyldiethylamine oxide Triacontyldimethylamine oxide Triacontyldiethylamine oxide 3,5-dioxatetracosyldimethylamine oxide 2-hydroxy-4-oxatetracosyldimethylamine oxide N-eicosylmorpholine-N-oxide N-docosylmorpholine-N-oxide 6-stearamidohexyldimethylamine oxide /3-Behenamindoethyldimethylamine oxide Behenylglyceryl (/3-hydroxyethyl) methylamine oxide N-docosylpyrrolidine-N-oxide N-eicosylpiperidine-N-oxide N-tetracosylpyridine-N-oxide.

In the practice of the process of the present invention the textiles which are to be softened are laundered prior to being treated with the softening agents described above. A list of synthetic detergents and builders which can be used to formulate detergent compositions useful in laundering these textile materials are disclosed in U.S. Pats. 3,159,581 (Dec. 19, 1964), col. 3, line 70 to col. 5, line 60 and 3,235,506 (Feb. 15, 1966), e.g. col. 3, line 40 to col. 4, line 54.

Other types of softening agents as well as additives such as stabilizers can be used in conjunction with the softening agents employed in the process of this invention. Examples of other softeners which may be employed in combination with the softening agents of this invention appear in Chwala, “Textilhilfsmittel,” Vienna 1939, particularly pages 61 to 64, March “An Introduction to Textile Finishing,” London, 1948, particularly Chapter X, and Schwartz-Perry, “Surface Active Agents,” New York, 1949, particularly pages 435 to 437. Other softening agents which may be used in conjunction with the softening agents of the present invention are characterized as follows: Ester, ether- or amide-like condensation products containing polyalcohol, polyglycol, or polyglycerol radicals and suitable higher molecular, preferably long-chain aliphatic radicals with 12 to 18 carbon atoms, such as for instance fatty acid or fatty alcohol condensation products of the general formula R—(C₂H₄O)NH wherein R stands for the monovalent radical of an aliphatic alcohol or an aliphatic acid or amide with 12 to 18

3,554,784 carbon atoms and n for a number from 5 to 10; fatty acid sarcosides; sulfated or sulfonated long-chain aliphatic alcohols; condensation products of long-chain fatty acids with hydroxy- or amino-sulfonic acids, such as compounds of the formula

C_nH₃3CO0CH₂CH₂CH2SO₃Na

C₁₇H_:l3CONHCH₂SO₃Na or

Ci₇H₃₃CON(CH₃)CH₂CH₂SO₃Na acylated or alkylated alkyl polyamines and higher alkylolamines; and quaternary ammonium compounds such as cetylpyridinium chloride, cetyltrimethylammonium bromide and tetradecyldimethylbenzylammonium chloride, and mono- or polyester of long-chain fatty acids with mono- or polyoxyamines.

Examples of brightener compounds which may be used in conjunction with the softening agents of the present invention include those disclosed in Stensby, “Optical Brighteners in Fabric Softeners,” Soap Chem. Specialties, 41, No. 5, 85-8 (May 1965), Netherland Pat. 6,408,162 (Jah. 18, 1965), U.S. Pat. 2,950,253 (Aug. 23, 1960) and Kirk et al., “Optical Brighteners,” Encyclopedia Chem. Tech. 3, 737-50 (1964). Specific examples of brightener compounds are cotton brighteners of the bis-triazinylstilbene type such as 4,4'-bis-[4-anilino-6-di (hydroxyethyl) amino - sym - triazin-2-ylamino]-2,2'-stilbenedisulfonic acid, disodium 4,4'-bis(4-anilino-6-morpholino-symtriazin - 2 - ylamino)-2,2'-stilbenedisulfonate, disodium 4,4'-bis-(4,6 - dianilino - sym-triazin-2-ylamino)-2,2'-stilbenedisulfonate, disodium 4,4'-bis(4-anilino-6-ethylaminosym-triazin - 2 - ylamino)-2,2'-stilbenedisulfonate and disodium 4,4' - bis(4 - anilino-6-N-methylethanolaminosym-triazin-2 - ylamino)-2,2'-stilbenedisulfonate; the bisN-acylstilbene type such as bis-benzoyl-, bis-p-aminobenzoyl- and bis-dimethoxybenzoyl-derivatives of 4,4-diaminostilbene-2,2'-disulfonic acids; the stilbene-triazole type such as sodium-4-(2H-naphtho[l,2-d]triazol-2-yl)-2-stilbenesiilfonate; and the dibenzothiophenedioxide type such as 3,7 - bis(p-methoxybenzoylamido)-dibenzothiophene2,8-disulfonic acid-5,5 -dioxide.

Other brightener compounds which can be used are those which are especially suitable for brightening synthetic fibers. Examples of these brighteners include the bis-azoles such as 1,2-bis(5-methy 1-2-benzoxazolyl) ethylene, bis(5-methyl-2-benzoxazolyl)thiophene and N-hydroxyethyl - l,2-bis(benzimidazolyl)ethylene; monoazole types such as 2-(m-chlorostyryl)-naphth-[l,2-d]-oxazole and 2-styryl-benzoxazole; the pyrazoline type such as 1-psulfonamidophenyl-3-p-chlorophenyl - 2 - pyrazoline; and the coumarin type such as 4-methyl-7-dimethylaminocoumarin and 3-phenyl-7-(diamino-sym-triazinylamino) coumarin.

When the foregoing brightening agents are employed in the processes of the present invention, it has been found that good results are obtained when the brightener is present in the rinse solution in the amount of about .0001% to about 0.001% by weight of the solution and most preferably from about .0002% to about 0.005% by weight. Generally, these brightening agents are used in combination for best brightening results.

The softening agents of this invention were found .to be surprisingly more effective as softening agents than their lower homologs. The reason for this unexpected increase in softening effectiveness is not known and was -unpredictable. The following examples comparing the softening properties of the softening agents employed in the process of the present invention with the softening properties of their lower homologs will serve to illustrate the surprising effectiveness of the softening agents employed herein.

The following laboratory procedures were used in connection with the examples below.

TESTING PROCEDURES (A) Preparation of test clothes.—This method was used to prepare the fabrics used in Examples I-VIII. Commercial fabrics of the following specifications were used:

(1) Terry cloth (Style 1313 washclothes from Cannon); (2) Crash cloth (Style 1035, 18 width bolts from

Standard Textile Company); and (3) Muslin cloth (Style 400 obtained from Test Fabrics Incorporated, N.Y.).

These cloths were de-sized and washed twice with a typical heavy-duty built anionic detergent composition in a standard automatic washing machine, and then rinsed four times in water (20 parts water per 1 part of cloth). Thereafter the cloths were dried and equilibrated at 45 % relative humidity at 70° F. for two weeks before use. Pieces of cloth 5 square were cut for use in the softness testing, in determination of adsorption of softeners, and in determination of minimum levels of the compounds required for softening. Full size washcloths of the above description were used when additional testing of softness was desired. All cloths were discarded after the test results had been obtained.

(B) Adsorption studies.—Five gram swatches of cloth were exposed with moderate stirring for ten minutes to 100 ml. of an aqueous solution containing the softener at the appropriate concentration. After ten minutes the solution was separated from the fabrics by decantation and the concentration of unadsorbed softener remaining in the solution was determined by titration with a standard solution of sodium alkylbenzenesulfonate. The amount of softener adsorbed from the solution by the fabric was determined by comparing the amount of softener found in the solution after exposure to the cloth with that present in the solution initially.

(C) Determination of softener effectiveness.—One set of cloth switches was treated by exposing the swatches for ten minutes at 70° F. to an aqueous solution of a known concentration of softening agent with moderate stirring. The ratio of the cloth weight to that of the solution was 1:20. At the end of this time, the swatches were spun for six minutes in a spin cycle of a standard automatic home washer and then dried in a rotary dryer, also a household model. A second control set of test cloths of the same composition was treated by exactly the same method except that water was used in place of the softening solution. After drying, the two sets of fabrics were allowed to equilibrate for 24 hours at 45° relative humidity and 70° F. before presenting them to the panel for softness rating.

Non-expert panels of ten persons (both male and female) were employed. Each panel member was presented with four pairs of cloth swatches. The panelists were asked to handle each pair of swatches in turn and select the softer of the two cloths if a difference could be discerned. Two pairs of test swatches were comprised of the treated cloth and the control cloth presented in such a way that the treated cloth was handled first in one case and the control cloth in the other. The other two pairs of test swatches were comprised of control cloths exclusively and were designed to serve as a bench-mark for random selection between cloths of identical character. The order of presentation of pairs to the panelists was varied from person to person. Sets of fabrics comprised by four pairs of swatches were handled by no more than two persons each to avoid spurious results arising from pickup of skin oils, etc. The test swatches were coded in such a way that the panelist was unable to distinguish whether a particular cloth had been softened. Thus, after all ten panel members had handled the sets of test swatches the number of panelists expressing a preference for the treated fabric was obtained and compared to the

3,554,784 number of panelists unable to distinguish the test fabric from the control fabric.

(D) Determination of minimum level of a compound required for softening.—Once a solution-concentration level of softener had been found at which a panel could ₅distinguish unanimously between softened and unsoftened swatches the level of softener in solution in subsequent softening treatments was reduced by suitable stages until only one-half of the panelists repeatedly expressed a preference for the softened fabric as compared to the control ιθ fabric. This point was found to be surprisingly reproducible.

(E) Determination of softener level on cloth by extraction and analysis.—Known weights of air-dried softened fabric swatches were placed in a large size Soxhlet 15 extractor and extracted for 24 hours with a chloroform methanol axeotrope. After evaporation of solvent from the extract, the residue was made to known volume in a small volume of chloroform and an aliquot was added to 35 ml. of distilled water in a 100 ml. glass-stoppered ²⁰cylinder containing methylene blue indicator. After addition of 10 ml. of chloroform, analysis for the amine oxide was carried out by titration with a standard solution of alkylbenzenesulfonate to a methylene blue end point.

EXAMPLE I

Test swatches of terry cloth treated in accordance with Procedure A were exposed to solutions of known concentrations of octadecyldimethylamine oxide and docos- 30 yldimethylamine oxide, respectively, using Procedure C. The results of panel grading of the softened cloths after the standard exposure and drying techniques are shown in the table.

Compound

Solution concentra- Percent by tion, parts weight of per million solution

Octadecyldimethylamine oxide___________________

Do...................

Do___________________

Docosyldhpetliyhunine oxide___________________

Do...................

Number of panelist (out of 10)

Unable to disPrefer treated .. . fabrics tinguish

100

0.01

0.005

0. 0025

0.0037

0.0018

It can be seen from the results of these paired comparisons that nearly three times as much of the octadecyldi- ⁵⁰methylamine oxide is required to soften the cloth to a level where 7 out of 10 panelists can distinguish the softness as is the case with the docosyldimethylamine oxide. This surprising result obtains even though there is a _rr. difference in molecular structure of only 4 methylene groups. It is also seen that the docosyldimethylamine oxide has appreciable softening activity in the range below 25 parts per million where octadecyldimethylamine oxide is completely valueless. Additional softness testing studies θθ with these compounds by Procedure D showed that the minimum level of compounds required in the rinse solution to produce noticeable softness (reproducibly detectable by half the panelists) was 67 parts per million in the case of the Cl 8 amine oxide and only 29 parts per _6gmillion in the case of the C22 amine oxide. Similar results to those above can be obtained by using eicosyl-bis(|3-hydroxyethyl) amine oxide, eicosyldimethylamine oxide, eicosyldiethylamine oxide, docosyl-bis-(/3-hydroxyethyl)amine oxide, docosyldimethylamine oxide, docosyl- 79 dimethylamine oxide, tetracosyldimethylamine oxide, tetracosyl-bis-(/3-hydroxyethyl)amine oxide, hexacosyldimethylamine oxide and hexacosyl-bis-(/3-hydroxyethyl )amine oxide, n-eicosylmorpholine-N-oxide and N-docosylpyrrolidine-N-oxide. 75

EXAMPLE II

This example shows the surprising effectiveness of the C₂₂ amine oxide as compared to C₁₈ and C₁₈ amine oxides on muslin and on crash toweling, two fabrics which are much more difficult than terry cloth to render noticeably soft. In these tests, both the minimum level required to produce noticeable softening as judged by panel grading (Procedure D) and the weight percent of the amine oxide remaining on cloth as judged by the extraction experiments followed by analysis (Procedure E) were determined and are shown in the table. These results show that with these fabrics, the C₂₂ amine oxide demonstrates a surprising superiority in softening over those compounds having a tallow length (C_J6 and C₁₈) chain. The superiority is demonstrated both in the requirements for the amount of compound dissolved in the treating solution and also in the amount of compound which must be on the surface of the fibers in order to give the effect which the non-expert panelists can notice.

Muslin

Crash

Compound

Minimum solution concentration required, p.p.m.

Οι₆Η₃₃Ν(ΟΗ₃)₂Ο.285

Ci₈H27N(CH₃)₂O _156

C22H]₅N(CH₃)2O.37

Amount of compound retained, wt. percent

Minimum solution concentrationrequired, p.p.m.

Amount of compound retained, wt. percent

0.33 855 .043

0.09__________________________

0.05 92 0.11

EXAMPLE III

This example shows that the degree of softness attained by fabrics upon exposure to the amine oxides having an alkyl radical of 20 to 30 carbon atoms is fully equivalent to that produced by the best commercial softeners. This degree of softening is not normally attained with dilute solutions except by using the cationic quaternary ammonium compounds. Separate applications of the cationic compound and the amine oxide to cloth were made in the manner described in Procedure C. The treated and control fabrics were presented to panel members in the same way as described except that in this case the panel members were asked to designate the degree of difference between the test swatches on a 0 to 4 scale (0=no difference; l=the cloth indicated may be softer than the other one; 2=distinctly softer; 3=much softer; and 4=very much softer). Furthermore, to simulate as closely as possible the conditions which prevail when a softener is used in the home laundry situation, the fabrics were washed with a typical heavy-duty anionic detergent formulation, softened in the rinse and again submitted to a panel for evaluation of the softness. The results of these studies are shown in the table for an amine oxide (A— a 50—50 mixture of eicosyldimethylamine oxide and docosyldimethylamine oxide) and a typical cationic softener (B—ditallowdimethylammonium chloride).

<td rowspan="2"> Softener</td><td rowspan="2"> Level in rinse, p.p.m.</td><td rowspan="2"> Percent by weight solution</td><td colspan="2"> Number of panelists, out of ten preferring treated cloth and (in parentheses) average degree of softening notice on 0 to 4 scale</td>

<td> After softener application</td><td> After washing and reapplication of softener</td>

<td> A—Amine oxide....</td><td> 50</td><td> 0.005</td><td> 10 (2.9)</td><td> 10 (3.2)</td>

<td> B—Cationic........</td><td> 50</td><td> 0.005</td><td> 10 (2.8)</td><td> 10 (3.2)</td>

<td> A—Amine oxide....</td><td> 25</td><td> 0.0025</td><td> 10 (2.5)</td><td> 10 (2.1)</td>

<td> B—Cationic........</td><td> 25</td><td> 0.0025</td><td> 10 (2.1) .</td><td></td>

Similar results to those above can be obtained by subsitituting on a molar basis the following compounds for

3,554,784 softener (A) or cationic softener (B) which are described in Example III are shown in the following table.

the amine oxide softener in the above Example: eicosylbis-(j3 - hydroxyethyl)amine oxide, eicosyldimethylamine oxide eicosyldiethylamine oxide, docosyl - bis -(/3- hydroxyethyl) amine oxide, docosyldimethylamine oxide, docosyldiethylamine oxide, tetracosyldimethylamine oxide, ₅tetracosyl-bis-(/3-hydroxyethyl) amine oxide, hexacosyldimethylamirie oxide, hexacosyl - bis-(/3-hydroxyethyl) amine oxide, N-eicosylmorpholine-N-oxide and N-docosylpyrrolidine-N-oxide. '·

EXAMPLE IV 10

This example shows the ability of the amine oxide softener to be essentially completely removed by a single wash-in a typical heavy-duty anionic detergent formulation. This very desirable feature thus prevents the buildup 15 of the softener on the fabric with consequent waterproofing· and yellowing of the fabric due to breakdown of the quaternary ammonium compound. In this test the fabrics were softened as before (Procedures A and C), then washed in an automatic washer with anionic detergent 20 formulation one or more times. The fabrics were presented to the panel members both after application of the softener and after each subsequent wash to determine the softness impression. The Softness impression (on a 0 to 4 scale as in Example III) gave an indication of the 25 level of softener ori the fabric at each stage. The results are reported in the following table for the same amine oxide (A) and quaternary ammonium (B) softeners de' scribed in Example III.

. . Number oi panelists, out of ten preferring treated cloth and (in parentheses) average degree of softening noticed on 0 '· ’ Percent to4scale

Level by---:----------_:-----------------in weight After After After rinse, of the softener one two

Softener. / p,p.m. solution application wash washes

A—Amine oxide.... 60 0.005 10 (2.9) 3 (0.5) 0 40

B—Cationic._______ 50 0.005 10 (2.8) 10 (2.4) 8 (1.5)

B—Cationic........ 25 0.0025 10 (2.1) 10 (2.5) 8 (1.5)

It is seen that the amine oxide softener is virtually com- 45 pletely removed by one wash step whereas substantial softener remains on the fabric after two washes when the cationic softener is used, even when only half the level of cationic softener is applied. Continued washing, through 5 washes, of fabrics to which had been added the cationic 50 ' (B) at 50 parts per million failed to completely remove the cationic softener.

EXAMPLE V

This example shows that the cloths softened with the 55 amine oxide softeners having an alkyl radical of greater than 20 carbon atoms are such more absorbent than those which have been treated with the quaternary ammonium salts which are ordinarily used. In this test, the cloths were exposed to 50 parts per million of the softener com- 60 pounds in the usual way (Procedures A and C), washed in a standard anionic heavy-duty detergent formulation, then reexposed to 50 parts per million of softener in the rinse cycle. Washing and application of softener were repeated through a total of four cycles of softener applica- 65 tion. After each application of softener was made, the cloths (after drying in the usual way) were tested for rewetability by the use of a standard sinking test. In this test the cloths were carefully placed on the surface of a large container of water at a standard temperature of 70° 70 F. The time elapsed before the test fabric sank below the water surface was recorded. Control fabrics which had not been treated with softener of any kind normally required 5 to 6 seconds before sinking. The results of the sinking test on fabrics treated with either the amine oxide 75

<td rowspan="2"> Softener (50 p.p.m.)</td><td colspan="4"> Sinking time</td>

<td> First softener application, sec.</td><td> Second cycle, min.</td><td> Third cycle, sec.</td><td> Fourth cycle, min.</td>

<td> A—Amine oxide....</td><td> 5</td><td> 10</td><td> 45</td><td> 2</td>

<td> B—Cationic________</td><td> 5</td><td> &gt;20</td><td> &gt;20</td><td> &gt;20</td>

EXAMPLE VI

This example shows that the efficiency of a typical cotton brightener in a softening composition is much better when amine oxide is used as the softening compound than when a typical cationic compound is used. In this test, 50 parts per million dispersions of (A) the C_2I).₂₂dimethylamine oxide or (B) ditallow-dimethylammonium chloride which comprises 0.005% of the solution by weight, into which were incorporated 2 parts per million of a bis-triazinylstilbene type cotton brightener 4,4'-bis[4anilino-6-di(hydroxyethyl)amino - sym - triazin - 2 - ylamino] - 2,2' - stilbenedisulfonic acid which comprises 0.0002% of the solution of weight, were used to treat standard muslin test swatches. After ten minutes exposure time (as in Procedure C) followed by rinsing in distilled water and drying, the muslin test swatches were placed in a fluorimeter to determine the extent of fluorescence conferred to the fabric, the following results were obtained:

Formulation: Fluorimeter reading

p.p.m. A (amine oxide)+2 p.p.m. brightener

p.p.m. B (cationic)+2 p.p.m. brightener____33

Water+2 p.p.m. brightener_________________98

Thus, the interference with brightening by the amine oxide is very slight while the interference given by the quaternary ammonium salt is very extensive.

Results similar to the above are observed when the brightener used in the foregoing test is replaced with any of the following brighterers: 4,4'-bis(4-anilino-6-dimorpholine-sym-triazin-2-ylamino) - 2,2' - stilbenedisulfonate and disodium 4,4'-bis(4,6-dianilino - sym - triazin - 2 - ylamino) - 2,2' - stilbenedisulfonate, disodium 4,4'-bis(4anilino-6-ethylamino-sym-triazin-2-ylamino) - 2,2' - stilbenedisulfonate and disodium 4,4'-bis(4-anilino - 6 - Nmethylethanolamino - sym - triazin - 2 - ylamino)-2,2'stilbenedisulfonate; bis - benzoyl-, bis - p - aminobenzoyland bis-dimethoxybenzoyl- derivatives of 4,4' - diaminostilbene-2,2' - disulfonic acids; sodium - 4(2H - naphtho [1,2-d] triazol - 2 - yl) - 2 - stilbenesulfonate; 3,7-bis-pmethoxybenzoylamide)-dibenzothiophene - 2,8 - disulfonic acid-5,5-dioxide.

Other brightener compounds which can be used are those which are especially suitable for brightening synthetic fibers. Examples of these brighters include 1,2-bis (5 - methyl-2-benzoxazolyl)ethylene, bis(5 - methyl - 2benzoxolyl) thiophene and N - hydroxyethyl - 1,2 - bis (benzimidazolyl) ethylene, 2 - (m - chlorostyryl-naptho[ 1,2-d] oxazole and 2-styryl-benzoxazole; 1 - p - sulfonamidophenyl-3-p-chlorophenyl - 2 - pyrazoline; 4 - methyl7-dimethylaminocoumarin and 3-phenyl-7-(diamino-symtriazinylamino) coumarin.

EXAMPLE VII

Sufficient docosyldimethylamine oxide to produce a level of 50 parts per million or 0.005% by weight of solution is introduced into the final the final rinse solution of a stnadard home automatic washing machine containing a load of mixed cotton fabrics from normal family usage. After completion of the rinse cycle, that is, exposure for about 5 minutes and then spin drying, the load is dried in an automatic dryer. Upon panel grading essentially like that of Procedure C, the fabrics are judged to be much softer and more desirable than fabrics which have not been treated with the amine oxide. It is also

3,554,784 seen that fabrics such as washcloths and towels which have been treated with docosyldimethylamine oxide, while much softer than in the absence of the C₂₂ amine oxide, are nevertheless very absorbent when used in the normal way and are easily rewet in the sinking test described _rin Example V. ^J

EXAMPLE VIII

When the conditions of Example VII are repeated using a mixed family load containing fine fabrics such as nylon and polyester and using a 50-50 mixture of eicosyldi- io methylamine oxide and docosyldimethylamine oxide it is seen that the fine fabrics are rendered largely antistatic and are much more desirable when worn than are the control fine fabrics which are not given a treatment with the amine oxide compound. 15

EXAMPLE IX

This example shows the usefulness of a 50-50 mixture of eicosyldimethylamine oxide and docosyldimethylamine oxide when used in a “padding-on” process. Test swatches 20 of terry cloth treated in accordance with Procedure A are completely submerged in an aqueous dispersion containing 0.7% of the softening mixture by weight. The cloth load comprised about 2% of the aqueous bath by weight. The test cloths are exposed to the foregoing dis- 25 persion of softening agents for a period of about 15 seconds. The test cloths are then removed and passed between rubber rolls forcing out excess solution. The weight of the test cloths at this point is about 3 times their original dry weight. The test cloths are then dried in a stand- 30 ard automatic drier. Upon panel grading similar to that described in Procedure C, it is judged that the dried test cloths are much softer to the touch and fuller in appearance than in the absence of treatment with the foregoing mixture. 35

Similar results to those above can be obtained by substituting a like amount of the following compounds and mixtures thereof in, e.g., a 1:1 ratio by weight: eicosylbis-(jS-hydroxyethyl) amine oxide, eicosyldimethylamine oxide, eicosyldiethylamine oxide, tetracosyldimethylamine 40 oxide, tetracosyl-bis-(/3-hydroxyethyl)amine oxide, hexacosyldimethylamine oxide, hexacosyl-bis-(/3-hydroxyethyl) amine oxide, N - eicosylmorpholine - N - oxide and Ndocosylpyrrolidine-N-oxide.