US 2615824 A
Description (OCR text may contain errors)
Patented Oct. 28, 1952 METHOD AND COMPOSITION FOR IMPART- ING WATER RESISTANCE 'ro TEXTILE MATERIAL Francis W. Minor, Arlington, Va., Arnold M.- Sookne, Washington, D. 0., Milton Harris, Bethesda, Md., and Gray L. Pyle, Chicago, Ill., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army No Drawing. Application February 17, 1948, Serial No. 9,008
This invention is concerned with the production of water-resistant materials. More particularly, it relates to a treatment of a normally water-nonresistant body, 6. g. a textile, with a lower-alkyl-mono-substituted dichlorosilane or dibromosilane, whereby water-resistance is coniferred upon such body.
It is known broadly to treat a glass, textile, or paper body with an organo-silicon halide in the vapor or liquid phase to make it water-repellent; see U. S. Patents No. 2,306,222, Patnode, and 2,412,470, Norton, and British Patent No. 575,675, British Thomson-Houston Company Limited.
The present invention is based on the discovery that certain lower-alkyl-monosubstituted dihalosilanes, particularly monomethyl dichlorosilane, confer greater water-resistance on water-nonresistant bodies than any organo-silicon halides heretofore used for that purpose. For instance, a textile treated with a silanecontemplated by us, will absorb considerably less water upon prolonged exposure to rain (e. g. for 1 hour) than any other organo-silicon halide of the prior art.
It is generally assumed that the organo-silicon halide, upon application to the body to be treated, hydrolyzes by reacting with atmospheric moisture and/or with water previously absorbed in the body.
E, rns ixz 11120 RZSKOHM zHX B being an organic radical, Xa halogen atom, a: ranging from 1 to 3, y from to 2, and z from 1 to 3, the sum of z+y+z in the monomer being 4 (the valence of silicon) The hydrolysis product then is assumed to condense in situ to form a thin water-resistant silicone resin deposit upon the treated body:
non-injurious even to a delicate fabric body and,
4 Claims. (01. 117-161) contributeto high water-resistance values in the finished product.
Thus it is a principal object of our invention to provide a durably water-resistant body by treating-a normally water-nonresistant bodywith a lower-alkyl-monosubstituted dihalosilane.
Another principal object of our invention is a water-resistant textile adapted for military and civilian uses when made into clothing,,tentage, etc.
A further object of our invention is a novel organo-silicon halide treatment of a normally water-nonresistant body in the presence of a substance capable of controlling the acid formed during such treatment.
Still another object ofour invention is a method for rendering textiles water-resistant, which .method can be conveniently carried out in conventional textile treatment apparatus and which is readily taught to semi-skilled or even unskilled personnel.
characteristics will not be appreciably impaired by repeated laundering or dry-cleaning.
Other objects and advantages of our invention-will appear-more fully in the following description thereof.
We have found that'superior water-resistance properties are imparted to a normally waternonresistant body by immersing it in a loweralkyl-monosubstituted dichlorosilane or dibromosilane fil H I v AlkSiChofAlkSiBrz dissolved in an inert solvent, i. e. a solvent which does not react with the silane. The alkyl substituent group may be methyl, ethyl or propyl.
Monomethyldichlorosilane (CHsSiHCh) is a substance well adapted for the purposes of our invention. Upon hydrolysis and subsequent condensation of the silane, the fabric or other body becomes water-resistant, which phenomenon is believed by us to be due to the formation of a silicone resin deposit having recurrent chloride, or liquid aliphatic or aromatic hydrocarbons, such as a petroleum solvent (e. g. Varsol, a petroleum fraction boiling at about 150 0., made by Standard Oil Company) or benzene.
The hydrochloric or hydrobromic acid formed during hydrolysis may be removed by washing.
However, we prefer to neutralize it first by means of a weakly alkaline substance such as sodium bicarbonate or an alkali metal salt of a fatty acid, e. g. sodium acetate or potassium acetate. Strong alkalies are unsuitable where used on a body liable to be attacked thereby. Beside the alkali metal salts of acetic acid, those of formic, propionic, and butyric acid are suitable to control the hydrogen halide. Surprisingly we have found further, that if the hydrolysis of the organo-sllicon halide is carried out in the presence of epoxybutene 61122011. CH CH; (3,4 epoxybutene-l) a highly water-resistant body results upon condensation of. the silane, without strength loss from acid attack; we are at present unable to account for this surprising ability of the epoxybutene of controlling the mineral acid forming during hydrolysis.
Curing of the silane upon the body, which we believe to result in the formation of a silicone resin deposit, is efiected by drying at room temperature, preferably followed by exposure to an elevated temperature. We have obtained good curing efiects in the case of textiles by exposure to 105 C. to 150 C. for 15 minutes to 2 hours. The goods are washed priorto the drying and/or heating step, in order to remove the hydrohalic acid which forms as the lay-product of the hydrolysis of the organo-silicon halide as well as the substance used for controlling the acid. The body should be clean prior to commencement of the treatment, as dirt unfavorably influences the chemistry of the reaction; thus a fabric should be thoroughly cleaned by washing or dry-cleaning prior to treatment.
Particularly favorable results are accomplished by treating a woolen fabric in accordance with our invention, as wool is an acid-resistant fiber; but cotton, paper and other bodies can be made water-resistant with our method.
In evaluating water-resistance of the bodies treated in accordance with our invention, we have utilized the dynamic absorption test described in par. 51) (1) of CCC-T-lsla Supplement, October 8, 1945, to Federal Standard Stock Catalog, section IV (part Supplement to Federal Specification for Textiles; General Specifications, Test Methods. This test measures the interfiber liquid absorption of a textile by simulating the effect of immersion in an agitated body of water, e. g. a river, and consists of tumbling a test specimen in a tumble jar filled one-third with water at 55 R. P. M. for a designated time interval (say 10, 20, 30 or 60 minutes), passing the specimen through a 60 lb. wringer twice (the first time without, and the second time between blotters), and weighing the specimen; the percentage of added-on weight of the specimen is its dynamic absorption value. Naturally, the lower the dynamic absorption value, the more waterresistant the fabric.
By subjecting an untreated sample of 18 oz. wool serge to dynamic absorption tests for various time intervals, we obtained the following results:
The following examples of water-resistance imparting treatments of samples of the same 18 oz. wool serge in accordance with our invention will illustrate various ways of practicing our invention and the advantages obtained therefrom; however, we wish to be understood that the scope of our invention is not limited by any technical details recited in such examples as, for instance, strength of silane solution, exact length of immersion, duration and temperature of ouring, etc., inasmuch as such details will be readily varied by those skilled in the art without departing from the spirit of our invention and without sacrificing any of the advantages gained thereby.
Enumgclev 1 1 part by volume of monomethyl dichlorosilane is dissolved in 30 parts by volume of carbon tetrachloride. A dry switch of serge is immersed in this solution for 2 to 4 seconds, the carbon tetrachloride is evaporated from the serge at room temperature, and the swatch 'is then treated with a .2% solution of sodium carbonate to neutralize hydrochloric acid forming as a hydrolysis by-product. The swatch is now washed twice with water to remove the product of neuinalization and any excess of sodium carbonate solution, and finally baked for two hours at to C. The resulting product showed an increasein dry weight of 1.1% over the untreated The fabric retains its water resistance even after repeated laundering:
DYNAMIC ABSORPTION VALUE PERCENT 10 Min.
23 Min. 30 Min. 60 Min.
After 5 launderings l9 24 27 Control tests substituting silanes of the prior art for waterproofing. textiles, gave the following dynamic absorption values (prior to laundering) 10 Min. 20 Min. 30 Min. 00 Min.
Methyl tricblorosi1ane. 26. 5 34 34. 5 50 Diethyl dichlorosilanan. 37. 5 47 51 58. 5 Ethyl trichlorosilane 34 S9 44 47 Example 2 The treatment of Example 1 was repeated by substituting a. solution of 1.5 part by volume of monomethyl dichlorosilane in 100 parts of carbon tetrachloride. Dynamic absorption values of the treated swatch were as follows:
10 Min. 30 Min. 60 Min.
T Dynamic absorption values obtained from a 10 Min. 20 Min. so Min. 60 Min.
25;. 9 so. i as. 2 43. 4
Example 3 A moist swatch of serge, containing 26% of water absorbed between its fibers, is briefly immersed in a solution of 1 part by volume of monomethyl dichlorosilane in 40 parts by volume of carbon tetrachloride. The solvent is evaporated in a fume hood, and the hydrochloric acid byproduct of the hydrolysis is removed by two washings in a 2% solution of sodium acetate in water, followed by a 25 minute rinse in tap water, and baking for 2 hours at 110 C. The increase in dry weight is 0.9%, and dynamic absorption values in per cent as follows:
Min. 7 20 Min. 30 Min.
The treated fabric retains its water resistance after dry-cleaning, as shown by its dynamic absorption values after 1 hour's agitation in a hydrocarbon dry-cleaning fluid:
10 Min. 20 Min. 30 Min. 60 Min.
' It is believed that best results with moistened fabric are achieved by placing it in equilibrium? with the atmosphere, 1. e. absorbing as much:
moisture as can be entirely absorbed within the fibers so that no liquid is sensibly present at the surface of the'fabric. Thus the higher the temperature and relative humidity of the atmosphere, the more Water can be held by th fabric without sweating.
Example 4 Dry swatches of serge were briefly immersed in a solution of one part by volume of monomethyl -dichlorosilane in 25 parts by volume of carbon tetrachloride. The solvent is evaporated in a fume hood, and the hydrochloric acid byproduct of the hydrolysis is removed by a minute immersion in an aqueous solution of a weak base,
as indicated in the table below. This is followed by a two hour rinse in water, a gentle squeezing out of excess water, and oven-curing for 2 hours at l05-110 C. Dynamic absorption values in per cent were as follows:
Thus, best water-resistance was accomplished by vusing sodium bicarbonate and sodium acetate solutions, followed by sodium carbonate and ammonium hydroxide. Least favorable is neutraliz ation with sodium hydroxide solution.
Example 5 Olive drab serge samples are pretreated by impregnation with a water solution of a salt of a weak acid, dried, and immersed in a solution of 1 part by volume of monomethyl dichlorosilane -in 25 parts by volume of carbon tetrachloride. I The solvent is evaporated and the (neutralized) hydrolysis byproducts removed by washing in water, and the swatches oven-dried at 105 to 110 C. for two hours. Dynamic absorption values were as follows:
Impregnating Agent B2121? Sodium carbonate (15%) 1 29 39 45 52 Sodium bicarbonate (23.5%) 1 19.5 25 29 36. 5 Sodium acetate (37%) l 16 20 22. 5 I 30 Amount of salt deposited on swatch (percent per weight of swatch); Best water resistance was achieved with the sodium acetate impregnated swatches; free hydrochloric acid was absent, as could be determined from absence of discoloration.
Example 6 DYNAMIC ABSORPTION VALUE PERCENT i0 20 so to Tune Min. Min. Min. Min.
60min .18 21 23 27 min 1e 20 20 23 l5m1n l7 18 2O 23 2 months 17 18. 5 21. 5 2o. 5
Water resistance achieved by curing at to C. for 90 minutes, and by curing at .150 C. for 15 minutes is thus substantially the same, and almost as good as obtained by curing for two hours at 105 to 110 C. in accordance with Example 4.
Example 7 to be free from hydrochloric acid and to have gained 7.2% of weight; its dynamic absorption values were:
10 Min. 20 Min. so Min. 60 Min.
Example 8- Dry swatches of serge were treated with solutions of monomethyl dichlorosilane in various sample were (corresponding values of untreated poplin'samples inparenthesis) organic solvents (see table below), the solvent 10 20 Mm 3o 60mm evaporated, the free hydrochloric acid (hydrolysis byproduct) neutralized with a sodium salt of a 27(45) 30(45) 1 31%) 34(47) weak acid, rinsed, and oven-cured at 105-110 C. ior 2:hours-. Dynamic absorption values were:
' r t I so so Swan 0 iii ft bg Min. Min. Min.
vol. of silane Skellysolye B (a petroleum fraction boiling at about 80 0., manuf. by ShelI-OilGo.) -m 20 24 26 2 Petroleum Ether (a mixture of pentones and hexanes boiling between 40 0. an 7 o.) 25 2o 22 24. 31, Acetone; 33% 26 3 59 Ethen. 33 23 so 31 45 -Varso1(a petroleum fractionmanul'.
by Standard Oil Co.) boiling at about 150 o...- 33 14.5 18.5 21 21.5 Benzene 16.5 18.0 1941 21.1 Moist Benzene. 40 16.2 17.8 18.8 218 The foregoing table shows that aliphatic and Another sample of 5 oz. poplin. was immersed for aromatic hydrocarbon solvents for the silane. reseveral minutes in a solution composed of 1.8% sult in water resistance of the treated fabric to monomethyl dichlorosilane, 2.4% -eD ybualmost the same degree as carbon tetrachloride. tone-1, and 95.8% carbon tetrachloride (see Ex- Presence of a small amount of water in the solample 7). The carbon tetrachloride solution was vent is apparently non-injurious, as shown by 30 evap d y Suspension n a fu e hood for the results accomplished with moist benzene. one hour, the sample was washed in a water The comparatively poor Water resistance with solution of sodium acetate, rinsed for 30 minutes acetone or ether as the solvent indicates the in running p Water, and cured 90 i s inferiority of organic solvents containing oxygen at 110 C. Dynamic absorption values were (corin the molecule for the purposes of water-resist- 35 espo di Va ues of untreated sample inp re ance imparting treatment in accordance with our thesis) invention.
The followin examples show the results of water-resistance treatment in accordance with. g m 20 60 our invention on fabrics other than 18 oz. serge: 4o 26 (46) 33 (48) 34 (48) 34 (48) Example 9 Various wool fabr cs were subj t d o a pr Breaking strength of the treated sample was8l% liminary dry cleaning with carbon tetrachloride of the untreated'sample. he s pl were e immer d briefly in a It will be seen from the foregoing description solution of 1 part by volume of monomethyl dithat by a water resistance imparting treatment chlorosilane in 25 parts by Volume of carbon in accordance with the present invention, woolen tetrachloride. e hy or c d fo d as textiles and other normally water-nonresistant a byproduct of the resulting hydrolysis was nonbodies are converted into superior water resisttralized with a water solution of a sodium salt 50 ant bodies. We are not able at this time to acof a weak acid, and the neutralization product count for the reason why the choice of a lowerwas rinsed out. The samples were finally cured alkyl-monosubstituted dichloro-or dibromosilane at 110 C. for about two hours. Dynamic absorpresults in waterproofing superior to results action values of the treated samples were as follows complished with fully substituted. halosilanes (corresponding dynamic absorption values of 'un- (that is, silanes wherein all four valences of the treated samples shown in parenthesis): silicon atom are satisfied by halogen and or- Fabric 10 Min. 2'0 Min. 30'Min. Min.
Wovenfelt 32 (13a) 4015 (134.5) 43.5 (137.5) 49 (13c) Tropical Worsted..- 19 (51 21. 5 (55) 23 (51) 2e (51) 32 oz. Melton .l 7015 (135) I 68.50%) 93.5 (124 m3 134 Example 10 ganic substituents) however, theresults obtained 5 oz. poplin (a cotton fabric) was impregnated by our method clearly show that such is the case. with sodium acetate (CHaCOONaBI-IzO) from an We claim: aqueous solution so as to deposit 26% of sodium 1. A method of imparting water resistance to acetate per weight of sample. The sample was a normally water-non-resistant textile material,
immersed in a solution of monomethyl dichlorosilane, the solvent was evaporated, the sample again immersed in an aqueous solution of sodium acetate, rinsed, and cured for two hours at 130 comprising immersing said material into a solution in an inert solvent of a lower-monoalkylsubstituted dihalosilaneselected. from the group consisting of monoalkyl dichlorosi-lane and mono- C. Dynamic absorption values of the treated. alkyl dibromosilaneand having not more than three carbon atoms in its alkyl substituent chain and 3,4-epoxybutene-1, in the presence of moisture, whereby said substituted dihalosilane is hydrolyzed in situ and the hydrohalic acid formed as hydrolysis by-product is neutralized in situ, and exposing said material to an elevated temperature after its removal from said solution, whereby the hydrolyzed substituted silane is condensed in situ to a water resistant deposit.
2. A composition for imparting water-resistance to a normally water-non-resistant body, comprising a, lower-alkyl-monosubstituted-silane selected from the group consisting of monoalkyl dichlorosilane and monoalkyl dibromosilane, and having not more than three carbon atoms in its alkyl substituent chain and 3,4-epoxybutene-1 in an inert solvent.
3. A composition for imparting water-resistance to a normally water-non-resistant body, comprising monomethyl dichlorosilane and 3,4- epoxybutene-l in an inert solvent.
4. A method of imparting water resistance to normally water-non-resistant textile vmaterial, comprising immersing said material into a solution in an inert solvent of lower-monoalkyl substituted dihalosilane selected from the group consisting of monoalkyl dihalosilane and monoalkyl dibromosilane and having not more than 3 carbon atoms in its alkyl substituent chain and 3,4-epoxybutene-1, in the presence of moisture, whereby said substituted dihalosilane is hydrolyzed in situ and at least part of the hydrohalic acid formed as hydrolysis by-product is neutralized in situ, removing said material and the hydrolyzed monoalkyl-substituted silane absorbed therein from said solution, expelling the solvent absorbed in said material, neutralizing the remaining portion of the hydrohalic acid by-prodnot of the hydrolysis remaining in said material with sodium acetate, and condensing the hydrolyzed substituted silane, which is absorbed by said material, in situ at an elevated temperature to a water-resistant deposit.
FRANCIS W. MINOR. ARNOLD M. SOOKNE. MILTON HARRIS. GRAY L. PYLE.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS- Number Name Date 2,306,222 Patnode Dec. 22, 1942 2,386,259 Norton Oct. 9, 1945 2,412,470 Norton Dec. 10, 1946 2,449,572 Welsh Sept. 21, 1948 2,469,625 Barry May 10, 1949 FOREIGN PATENTS Number Country Date 418,230 Great Britain Oct. 22, 1934 116,470 Australia Jan. 19, 1943 OTHER REFERENCES Bennett, Concise Chemical 8: Technical Dictionary, Chemical Publishing 00., 1947, pp. XX and 366.