Compositions for treating organic fabrics and a method of applying them

United States Patent Office _p ., ²>^{897 601}

Patented Sept. 24, 19S7

2,807,601

COMPOSITIONS FOR TREATING ORGANIC FABRICS AND A METHOD OF APPLYING THEM

Firth L. Dennett, Midland, Mich., assignor to Dow Corning Corporation, Midland, Mich., a corporation of Michigan

No Drawing. Application September 7,1954, Serial No. 454,613

Claims. (Cl. 260—42)

This invention relates to an improved organosilicon treatment of organic fabrics.

This application is a continuation-in-part of applicant’s copending application Serial No. 426,602, filed April 29, 1954 now abandoned, entitled, “Compositions for Treating Organic Fabrics and a Method of Applying Them.”

It is known in the art that various types of organosilicon compounds render textiles water repellent. In the past one of the methods employed is the use of hydrolyzable silanes such as methylchlorosilanes. Whereas this method gives improved water repellency, it is not satisfactory because of the acid given off during hydrolysis which interferes with the commercial use of the material. Another method known to the art is that of using alkali metal salts of organosilanols. This method produces water repellency but it requires a neutralization of the alkali. This means that an acid rinse is needed and thus adds an extra step in the treatment of the fabric.

The best previously known method of rendering fabrics water repellent has been the treatment of the fabrics with mixtures of hydrogen containing siloxanes and trimethyl end-blocked dimethylsiloxanes as is described in U. S. Patents 2,588,365 and 2,588,366. Briefly this method comprises applying a mixture of the two siloxanes to the fabric and thereafter heating the treated material until the siloxane has become set. This method has met with great commercial success because it gives a combination of excellent water-repellency, the proper hand and drape and lack of mark off needed for fabric use. This method gives excellent water repellency on practically any kind of fabric and the water repellency remains essentially unchanged after repeated dry cleanings and launderings. However, it has been found that these products described in the aforesaid patents do not prevent shrinkage of wool during laundering even though the water repellency of the wool remains good.

.Furthermore, it has been found that fabrics treated with the above materials although resistant to dry cleaning were not resistant to grease spotting, that is, spots of grease could not be removed from the fabric by merely cleaning with a solvent without leaving an unsightly spot. This spot appeared to be due to several factors such as migration of the fabric dye and the siloxane with the solvent as it spreads out from the affected area. When the solvent evaporates a permanent stain is left on the fabric.

The problem of grease spotting is quite serious with respect to upholstery fabrics such as are used on automobile seats and furniture. When a grease spot occurs on the upholstery of furniture or an automobile seat it is obviously impossible to dryclean the entire fabric. The only solution is to take a solvent-saturated cloth and attempt to remove the spot in that manner. With a large number of fabrics this inevitably leaves a permanent stain. Often times an even worse stain is produced when the fabric has been treated with the siloxane water repellents described in the aforesaid patents. The staining of fabrics under these conditions is quite a problem in the automo- tive industry since a certain number of cars will always get grease on the upholstery as they pass down the assembly line. Some of these stains are so pronounced that it is necessary to remove the car from the assembly line 5 and reupholster the seat. This, of course, is quite expensive and it would be highly desirable to have a fabric which could be cleaned by hand in a few seconds.

The applicant has found most unexpectedly that by employing hydroxylated siloxanes as one of the ingredients 10 in the siloxane water repellents hereinafter described that the spotting of fabrics described above is entirely eliminated.

It is the primary object of this invention to provide a siloxane water repellent for organic fabrics which while 15 retaining all of the beneficial properties of previously employed siloxane water repellents has the added advantages of preventing grease spotting and solvent spotting of fabrics and of substantially preventing the shrinking of wool during laundering.

This invention relates to compositions of matter composed essentially of (1) from 5 to 75% by weight of a hydrocarbon soluble polysiloxane in which there is on the average from .05 to 1 silicon bonded H atoms per silicon atom, the remainder of the valences of the silicon atoms 25 being satisfied by oxygen atoms, aliphatic hydrocarbon radicals of less than 6 carbon atoms and up to on the average .1 aryl hydrocarbon radicals per silicon atom, there being an average of from 1.6 to 2.5 inclusive total hydrocarbon radicals and hydrogen atoms per silicon atom, and 30 (2) from 25 to 95% by weight of a hydroxylated poly siloxane having a viscosity of less than 1,000,000 cs. and having an average of from 1.4 to 2 monovalent hydrocarbon radicals per silicon atom.

r In accordance with this invention these compositions 35 are applied to any organic fabric by any suitable mans and the fabric is thereafter heated until the siloxane is cured. In general, organosilicon compositions are applied to the fabric in amount so that the pick up ranges from .1 to 5% with the preferred range being from 1 to 2% by 40 weight both ranges being based on the weight of the fabric.

The compositions of this invention may be applied to the organic fabrics in any desired manner such as by dipping or spraying. The compositions can be applied either per se or in the form of solutions or emulsions. In general, for commercial operations, the emulsions are preferred since most fabric makers are not set up to handle solvent solutions. In fact one of the primary advantages _r of the composition of this invention is that they can be ^,ιυ readily emulsified.

After application of the organosilicon compositions of this invention, the fabric is heated to remove any solvent or water and to cure the siloxane. In general the preferred heating temperatures are from 100 to 475° F.

^J Heating at these temperatures for from 5 seconds to 1 hour is usually sufficient to obtain a satisfactory cure of the siloxane.

If desired curing catalysts such as zinc or iron octoate lead 2-ethylhexoate, and the like, may be employed to aid the cure of the siloxane.

Hydrogen containing siloxanes (1) which are operattive in this invention must be either liquid or hydrocarbon soluble materials. For the purpose of this invention ₆₅ at least 5 mol percent of the silicon atoms in the siloxane should contain at least one hydrogen atom attached thereto and in general there should be an average of not more than 1 hydrogen atom per silicon atom. The remaining substituent groups on the silicon atoms are any aliphatic hydrocarbon radical having less than 6 carbon atoms. Thus the siloxane may be substituted with methyl, ethyl vinyl, allyl, propyl or amyl radicals. The hydrogen atoms may be substituted on a silicon atom containing l or more of the defined hydrocarbon radicals or the hydrogen may be on a silicon atom which contains no hydrocarbon

Specific examples of siloxanes exemplary of siloxane (1) are methyl hydrogen polysiloxane, ethyl hydrogen polysiloxane; copolymers of methyl hydrogen polysiloxane and dimethylphenylsiloxane; copolymers obtained by cohydrolyzing diethyldichlorosilane, trichlorosilane, and ethyldimethylchlorosilane; copolymers obtained by cohydrolyzing silicon tetrachloride, methyldichlorosilane, dimethyldichlorosilane and triethylchlorosilane; copolymers obtained by cohydrolyzing dimethylmonochlorosilane and ethyldichlorosilane; copolymers obtained by cohydrolyzing vinylmethyldichlorosilane, methyldichlorosilane and ethylmethyldichlorosilane; copolymers obtained by cohydrolyzing monomethylmonochlorosilane, trimethylchlorosilane and methyldichlorosilane; copolymers obtained by cohydrolyzing trimethylchlorosilane, dichlorosilane and dimethyldichlorosilane; and copolymers obtained by cohydrolyzing phenylmethylmonochlorosilane and methyldichlorosilane. Preferably the siloxane (1) should be substituted with methyl radicals and hydrogen atoms.

Siloxane (2) employed in this invention must be a hydroxylated fluid. These siloxanes contain on the average from 1.4 to 2, preferably from 1.98 to 2, inclusive hydrocarbon radicals per Si atom. Preferably the radicals are aliphatic hydrocarbon radicals of less than 6 carbon atoms such as methyl, ethyl, propyl, amyl, vinyl and allyl. In those fluids having essentially 2 organic radicals per silicon atom the hydroxyl groups are presumably attached to the end Si atoms i. e.,

R.

H0[S10],H

When an appreciable amount of monoorganosilicon units

YVI1C11 all appivviavxv anwu... ...------ =--------— are present, some of the OH groups may be along the ⁰⁰chains, i. e.,

Rj Ri Rj HLOSiOSiOSibOH OH

In any case, viscosity of these fluids must be less than 1,000,000 cs. but the lower limit of the viscosity is not critical. In general the fluids contain at least .02% by weight OH groups. . . .

The composition employed in this invention is obtained by merely mixing siloxanes (1) and (2). This may be done by employing a mutual solvent, if desired. Suitable solvents include benzene, toluene and petroleum hydrocarbons. If desired, both siloxanes (1) and (2) may contain limited amounts of aromatic hydrocarbon radicals but the presence of large amounts of such radicals should be avoided since they produce inferior water repellency when present in amounts above 10 mol percent.

Siloxanes (1) and (2) may be prepared ly any of the methods known to the art. Siloxane (2) is best prepared by the method set forth in the application of J. Franklin Hyde et al., Serial Number 426,560, now Patent No. 2,779,776 filed April 29, 1954. Briefly this method comprises maintaining a siloxane in contact with certain monobasic aqueous acids in a closed system until a constant viscosity of the siloxane is obtained and thereafter washing the siloxane free of acid.

The compositions and method of this invention are applicable to any organic fabric such as, for example, nylon, cotton, wool, linen, rayon, paper, polyacrylonitrile fabrics, vinylchloride-vinylidene chloride fabrics and terephthalic acid-ethylene glycol fabrics. In all cases the fab- ⁸⁵rics have excellent water repellency, hand, drape and freedom from mark-off and grease spotting. In addition the compositions prevent wool fabrics from shrinking during laundering and are easily emulsified. The above combination of properties is not inherent to any other θ known compositions either organosilicon or organic.

The procedure employed to test the shrinkage of wool fabrics in the following examples comprises placing the fabric in water at 140° F. in a standard reversing wheel washing machine. The water was added to the machine 75

2,807,601 until it reached a level of 4 inches above the bottom of the inside cylinder. The water was maintained at 140° F. and the machine was operated for 1 hour. The fabric was then removed and centrifuged in a 20 inch diameter extractor for 5 minutes at a speed of 1750 R. P. M. and thereafter dried in a tumbler drier at a stack temperature of 130° F. for 30 minutes. The fabric was then removed from the drier, sprinkled with water, allowed, to stand for 5 minutes and pressed in a flat bed press until it was dry. The fabric was then measured to the nearest 16th of an inch in order to ascertain the shrinkage.

The term “composed esesntially of” as employed in the claims means that siloxanes (1) and (2) are the essential ingredients of the compositions of this invention. However other nonessential ingredients may be included in these compositions without departing from the scope of the present invention. For example, monoorganosiloxane resins may be added in minor amounts in order to modify the hand of the fabrics as desired or organic resins such as urea-formaldehdye, melamine-formaldehyde, vinyl acetate and acrylonitrile resins may be used in conjunction with the instant compositions in order to increase the crease resistance of the fabric, weather resistance and other specific properties.

The following, examples are illustrative only and should not be construed as limiting the invention which is properly delineated in the appended, claims.

Example 1

This example shows the superiority of the compositions of this invention over previously employed trimethyl endblocked polysiloxane fluids. Siloxane A employed below was a mixture of 90% by weight of hydroxyl: end-blocked dimethylpolysiloxane having a viscosity of 13,742 cs. and 10% by weight of a trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of about 25 cs. Siloxane B was a mixture of 90% by weight of a hydroxyl end-blocked polysiloxane fluid having a viscosity of 400,000 cs. and 10% by weight of a trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of about 25 cs. Siloxane C was a mixture of 90% by weight of trimethyl end-blocked dimethylpolysiloxane fluid having a viscosity of 12,500 cs. and 10% by weight trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of 25 cs.- Siloxane D was a mixture of 90% by weight, of a trimethyl end-blocked dimethylpolysiloxane having a viscosity of 400,000 cs. and 10% by weight of a trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of about 25 cs. Thus it can be seen that siloxanes A and B are within the scope of this invention while siloxanes C and D are not.

Each of the above siloxane mixtures contained 2% by weight of lead 2-ethylhexoate. A 2% by weight xylene solution was prepared from each of the above siloxanes and a piece of O. D. 10½ ounce wool flannel shirting was immersed in each solution for a sufficient time to give a pick up of 1.4% by weight organosiloxane. Each of the wool samples was then air dried and cured 10 minutes at 300° F. Each sample was then subjected to the laundering shown above and the shrinkage after the first and sixth laundering is given in the table below.

<td rowspan="2"> Siloxane</td><td colspan="2"> First laundering, percent shrinkage</td><td colspan="2"> Sixth laundering, total percent shrinkage</td>

<td> Warp</td><td> Fill</td><td> Warp</td><td> Fill</td>

<td> A _______________________</td><td> 2.4</td><td> 2.4</td><td> 3.8</td><td> 3.8</td>

<td> B __________________</td><td> 2.4</td><td> 2.4</td><td> 4.1</td><td> 3.8</td>

<td> 0 __________________</td><td> 8.7</td><td> 4.2</td><td> 28.6</td><td> 22. b</td>

<td> D____________________________</td><td> 4.6</td><td> 2.7</td><td> 22.6</td><td> 14.5</td>

Example 2

The siloxane employed in this example was a mixture of 40% by weight of a hydroxy end-blocked dimethyl; -..-....5 polysiloxane having a viscosity of 129 cs. and 60% by weight of trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of about 25 cs. A 2% xylene solution of the siloxane was applied to a piece of wool gabardine fabric in amount sufficient to give a pick up of 1.6% by weight siloxane. The fabric was then dried and heated 10 minutes at 300° F. and then subjected to laundering in the manner shown above. The resulting wool fabric showed a markedly reduced shrinkage as compared with the untreated cloth.

Example 3

This example shows the protection of fabric against spotting which is characteristic of the compositions of this invention. A series of hydroxy end-blocked dimethylpolysiloxane fluids having viscosities of 1700 cs., 5000 cs., 25,000 cs. and 42,00 cs. respectively were each mixed with a trimethyl end-blocked methyl hydrogen polysiloxane having a viscosity of about 25 cs. in amount such that in each case the weight ratio was 40% hydroxyl end- 20 blocked fluid and 60% methyl hydrogen fluid. An aqueous emulsion was prepared from each composition employing polyvinyl alcohol and sodium lauryl sulphates as emulsifying agents. The emulsion was diluted until the concentration of the siloxane was about 4% by weight. 25 A piece of upholstery fabric having a nylon face and a cotton back was dipped into each emulsion for a time sufficient to give a 2% by weight siloxane pick up. Each fabric was then passed through drying rolls and thereafter heated 10 minutes at 300° F. In each case a spot of as- 30 phalt cement was applied to the fabric and allowed to remain thereon for 5 minutes. In each case the spot was completely removed in about 30 seconds by swabbing the fabric with a piece of cheese cloth impregnated with a standard fabric cleaning solvent. The fabric was then 35 allowed to air dry and no trace of a spot due either to the asphalt or the solvent was observed.

The above procedure was found to be effective on upholstery fabrics composed of 100% cotton, 100% nylon, combinations of rayon and viscose, 100% viscose, combinations of nylon and wool, 100% wool, combinations of polyacrylonitrile fibers and cotton, and combinations of nylon, viscose and metallic thread. Some of the fabrics tested had rubber backing and in all cases complete removal of the grease stain was obtained without spotting. ₄₅

Example 4

The composition employed in this invention was a 2% by weight petroleum naphtha solution of a mixture of 40% by weight of a hydroxyl end-blocked dimethylpolysiloxane fluid having a viscosity of 129 cs. and 60% by weight of a trimethyl end-blocked methyl hydrogen polysiloxane fluid of 25 cs. viscosity which solution contained 2% by weight of zinc octoate based on the total weight of the siloxanes. This solution was applied to a blue nylon upholstery fabric in such a manner that the siloxane pick up was 1.6% by weight. The fabric was air dried and cured 10 minutes at 300° F. Asphalt cement was then placed on the sample and it was completely removed in about 30 seconds by swabbing the fabric with a cloth impregnated with a standard cleaning solvent. No spot remained on the fabric.

Untreated fabrics identical with those employed in Examples 3 and 4 were severely and permanently stained by asphalt cement. This was also true of identical fabrics which had been treated in an identical manner with a mixture of 40% by weight of a trimethyl end-blocked dimethylpolysiloxane fluid of 12,500 cs. viscosity and 60% by weight of a trimethyl end-blocked methylhydrogenpolysiloxane fluid of 25 cs. viscosity.

Example 5

Equivalent results are obtained when liquid copolymers of 90 mol percent MeaSiO, 9.5 mol percent HSiOa/a and ,5 mol percent CeHsMeaSiOi/a; 99.5 mol percent PrHSiO 75 and .5 mol percent MeaHSiOi/2 and .1 mol percent AmMesSiOi/s, 55 mol percent EtaSiO and 44.9 mol percent MeHSiO are each substituted for the methylhydrogen-polysiloxane in the procedure of Example 3.

Example 6

Equivalent results are obtained when hydroxyl endblocked fluids each having a viscosity of 3000 cs. and having the following compositions; diethylsiloxane, diamylsiloxane, ethylmethylsiloxane and a copolymer of 95 mol percent dimethylsiloxane and 5 mol percent diphenylsiloxane are each substituted for the hydroxyl end-blocked dimethylpolysiloxane in the procedure of Example 3.

Example 7

The procedure of Example 1 was repeated employing a mixture of (1) 90% by weight of a fluid copolymer of 70 mol percent dimethylsiloxane and 30 mol percent monomethylsiloxane, which copolymer had a viscosity of 136 cs. and contained .36 percent by weight silicon bonded OH groups and (2) 10% by weight of a trimethyl end-blocked methyl hydrogen polysiloxane of 25 cs. viscosity. The treated wool was washed as described in Example 1 and the shrinkage data are shown below.

Warp. Fill..

First laundering, percent shrinkage

5.9

3.1

Tenth laundering, total percent shrinkage

5.7 »1.4 ¹ Wool elongated after first wash.

Example 8

Example 7 was repeated except that siloxane (1) was a fluid copolymer of 43.5 mol percent dimethylsiloxane and 56.5 mol percent monomethylsiloxane having a vis40 cosity of 4,692 cs. and containing .37% by weight silicon bonded OH groups. The wool shrinkage was as follows:

First laundering, percent shrinkage

4.1

1.8

Tenth laundering, total percent shrinkage

Warp.

Fill..

13.6

8.0