US2426300A - Method and composition for waterproofing - Google Patents

Description

Patented Aug. 26, 1947 ME'rnon AND oomosmon FOR warnaraoorme Sidney M. Edelsteln, Elizabeth, 11.].

No Drawing. Application April 3,1944, Serial No. 529,402

This one batch water repellent ordinarily consists essentially of a wax such as paramn, an emulsifying agent such as glue or gelatin, a small proportion of some soluble aluminum salt, and

water in which the wax is emulsified and the other materials dissolved. Typical .proportions are'20 part of the wax, 2 to 3 parts of glue or gelatin, 5 parts of aluminum acetate or formate, and water to make 100 parts, the whole composition being slightly acid and usually at a pH of about 4.5 to 5.5.

When this water repellent composition is mixed with a cellulose ether solution in aqueous sodium hydroxide, the form in which the ether 15 ordinarily applied to fabric, the ether solution sets to a gel.

I have now discovered, however, that an approximately equally alkaline solution of a cellulosic material in sodium zincate may be mixed with the one batch water repellent without the formation of a gel. Furthermore I have found that, even though the emulsion constituting the one batch water repellent is coagulated, as it sometimes is on being mixed with my solution of cellulose, the coagulated material when applied with the cellulose-zincate solution is entirely satphase.

isfactory and effective in making a fabric or the like water repellent, sometimes referred to herein as waterproof or waterproofing.

Briefly stated, my invention comprises the herein described product and the method of making it.' More particularly, the invention comprises the method of and the product resulting from forming an intimate mixture of a water repellent wax with a solution of a cellulosic material in aqueous sodium zineate 'ofthekind described, coagulating the wax and cellulosic material upon fabric or the like, and washing and drying the product. In the preferred embodiment, the invention comprises the additional-step or applying to the treated and washed product a dilute solution of aluminum salt, before the product is given the final drying.

In this latter embodiment, I avoid the need of drying the product at any time between the first application of the coating solution and-the V 1 Claims. (01.111-166) aluminum compound after the acid precipitation has been eifected and the excess acid largely removed. Thus I avoid removal of the aluminum compound by acid. The product so made is ordinarily subjected to the usual finishing operations including tentering and drying.

The zincate solution-used herein and the solution of cellulose in it may be made as described in my Patent No. 2,322,427, issued June 22, 1943, and entitled Cellulose product, or as described in my pending applications Serial No. 483,817, filed April 20, 1943, entitled Solubilized cellulose and method of making, and Serial No. 514,163, filed December 13, 1943, and entitled Cellulose ether composition and method of making. The cellulosic material used may be wood pulp, cotton, alkali stable cellulose ether, or any other of the cellulosic materials described in the said patent or applications. The zincate solution used contains an excess of sodium hydroxide over that required theoretically to convert the zinc to zincate.

The wax used is suitably paraffin wax. It must have a melting point above 100 F. Advantageously it contains a certain proportion of added petrolatum for the purpose of plasticizing or lowering the melting point of the wax. As an alternative it may contain a volatile, water insoluble solvent, as, for example, naphtha, toluol, or ethyl acetate, to lower the melting point and decrease the viscosity of the wax in the liquid Other-waxes that may be used are carnauba, candelilla, and any of the common alkali stable waterproofing waxes, either alone or mixed. When the wax used has a melting point above the boiling point of water, special benefits are obtained when the wax, after application to the fabric, is subjected to a temperature at least terproofing salts.

equal to its melting point, as in a drier or on hot rolls; this causes melting of the wax and its proper distribution in the film applied to the fabric.

In place of the aluminum salts referred to above which coact with the wax in improving and waterproofing there may be used other aluminum salts, as, for example, aluminum propionate, or zinc or zirconium salts of formic or acetic acid, the zinc or zirconium being used in amount equivalent chemically to the aluminum replaced.

Also there may be used the higher fatty acid salts of these metals or other conventional wa- In general, a waterproofing metal salt is ordinarily required even when wax is used. The salt may be-omitted, howeverrwhen 3 a high degree of water repellency is not desired or when the wax substituted is high melting.

Glue and gelatin are particularly satisfactory as emulsifying agents in my composition. They are sufficiently effective to cause the desired emulsification or dispersion of the wax. At the same time, they do not cause much wetting back in the finished product. In other words, their wetting properties are sufficiently strong for proper emulsification of the wax and yet are so weak that they are overcome in the treated fabric by the water repellency of the wax present.

In place of the glue or gelatin there may be employed other emulsifying agents that are commonly used in one batch water repellents. Casein and locust bean gum may be used.

These emulsifying agents promote the formation of emulsions in which the wax is'the dispersed phase and water the external or continuous phase. This condition is important in the present invention to insure the ready mixing of the wax emulsion with the zincate solution of cellulose.

The several ingredients may be mixed in various orders. I have found it desirable to make the cellulose solution in sodium zincate in accordance with my said patent and then to stir in thoroughly a previously made water repellent composition.

- In the use of this composition, the fabric or other article to be waterproofed is immersed in the composition and the thus treated product is subjected to treatment to cause precipitation of the cellulose and the water repellent. The wax and cellulose are thus deposited in intimate admixture and at the same time on the fabric. Particles of wax are isolated and proper distribution made permanent by the surrounding cellulose. The result is a thorough bonding and very fine distribution of the water repellent on the fabric, by and in the film of cellulose. After drying this film in turn is strong and firmly adherent to the fabric. The wax being largely within the cellulose does not interfere with the secureness of bonding of the surface portions of the cellulose to the textile. Furthermore, the wax is concentrated in a relatively thin surface layer or film where it is most effective in causing the shedding of water by the product when finished.

After the wax and cellulose are thus deposited on the article to be treated, the article is washed and preferably treated with a weak alkali, such as soda or ammonia, to remove acid which ordinarily constitutes the means for causing precipitation of the cellulose.

If desired soluble aluminum salt such as any one of those conventionally used in one bath water repellent compositions, particularly aluminum acetate or formate, is supplied to the washed article, say in the form of a final rinse including about 0.5 to 4 parts and ordinarily about 1 part of the aluminum salt on the dry basis for 100 parts of the rinse.

After the final rinsing, the article is dried. If the wax used is one that doe not melt at the drying temperature, then the article is subjected to hot rolling at a sufiiciently elevated temperature to melt the particle of Wax selected, say at a temperature of to F. above the melting point of the wax composition. This hot rolling ordinarily is not required. It is recommended only for use in finishing fabric including 'such high melting wax as carnauba or the like.

Articles made as described are water repellent and retain the water repellency after repeated '4 laundering. At the same time, they have an exterior surface of cellulose and have the various dyeing and finishing properties characteristic of cellulose fabrics.

While the invention has been described in connection with the waterproofin of fabrics, it is to be understood that other articles may be substituted and treated in the manner described for fabrics. Thus, there may be used paper, cardboard, or wood as the base article to be Waterproofed. The article to be waterproofed may be a textile material, as fiber, thread, or fabric of cotton, ramie, linen, rayon, or even wool or silk. Wool or silk if used requires quick immersion and prompt removal of the alkalinity, as by acid, directly after the immersion. In this way there is avoided solution of the protein in the alkali of the zincate solution.

Instead of acid as the method of coagulating the cellulose dissolved originally in the sodium zincate solution, there may be used any one of the cellulose precipitating agents or treatments described in my said patent. Sulfuric, hydrochloric, and acetic acid solutions of about 5 to 10% concentration are, however, especially suitable.

The soluble aluminum salt when used with the wax serves to improve not only the original emulsiflcation in the water repellent but also the waterproofing effect obtained in the finished fabric. When this salt is so used, then special care is taken to avoid the dissolving out of an objectionably large part of the salt by the acid during precipitation and subsequent washing of the cellulose upon the fabric. Thus, the presence of aluminum acetate, formate or the like during the acid treating step requires that the acid used to cause precipitation be either quite dilute or in contact for only a very short time with the fabric and adhering film of the cellulose and water repellent composition. Thus, in place of acid concentrations of around 5% or so, I may reduce the concentration of the acid to 1 to 3% and suitably about 2% when much soluble aluminum salt is present during the precipitation stage.

The invention will be further illustrated by description in connection with the following specific examples of the practice of it.

Example 1 A marquisette mosquito netting fabric which has been previously boiled out and dried is padded through a zincate solution of cellulose and waterproofing as follows:

15 parts of common one bath wax and aluminum salt water repellent are mixed with 15 parts .of water either by boiling up, by the use of hot water, or at room temperature. This emulsion is then added to parts of the cellulose zincate solution made as described in my said patent. The fabric is padded through this solution, soured in 5% sulfuric acid, rinsed thoroughly, passed through ammonia as antacid, and then dried. The fabric is then sufficiently Water repellent for most purposes in addition to having the usual desirable properties given to it by the cellulose solution.

Example 2 Same as Example 1, but any conventional alkali stable pigment or mildew proofing agent is incorporated, either alone or together, in the cellulose and zincate solution.

Example 3 Same as Examples 1 and 2 but, after the ammonia rinse, the goods are passed through a bath containing approximately 2% of aluminum formate or aluminum acetate, generally slightly on the acid side with an excess of acid, as, for example, at a pH of about 4.5 to Band suitably about 5. The aluminum salt added after the acid treatment remains largely in the fabric and improves the waterproofing.

Example 4 Same as Example 2 except that, after padding on the mixture of the cellulose and water repellent, the fabric is dried to coagulate the cellulose and then either soured in acid or washed to remove excess caustic.

Example 5 Same as Example 4'except that an aluminum acetate or formate bath is applied at the end, before final drying, allas described in claim 3.

Example 6 A spun rayon fabric is treated with a cellulose zincate solution made up as follows: parts of a parafii-n wax and soap emulsion are added to 30 parts of water, to make a good dispersion solution.

This mixture is then added to 60 parts of the cellulose zincate solution. After passage through this solution, the fabric is immediately souredin' 5% sulfuric acid, rinsed thoroughly, neutralized to remove excess acid and then passed through a bath containin a half percent aluminum acetate or formate as described above. Rinsing to remove excess alkali may precede the aluminum salt treatment if desired. The fabric is then very water repellent.

Example 7 temperature of curing isreplaced by treatment of the fabric after normal drying with a hot calender so as to melt the wax. This fabric is then water repellent and resists decrease of water.

repellency on continued laundering.

Example 8 Same as 7 with the exception that the goods are passed through an aluminum salt bath as described above in connection with Example 3. The aluminum salt solution may be applied either as the last rinse on the continuous cellulose treatment machine or after preliminary drying and before final drying. The aluminum salt enhances the water repellency of the fabric.

. Example 9 The same as Examples 1 to 8 except that the wax is dissolved initially in a liquid solvent. In

this case, elevated temperature drying or calendering is not necessary even though the wax alone is high melting.

It will be understood also that it is intended to cover all changes andmodifications of the example of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope oi the invention.

What I claim is:

1. A water repellent coating composition comprising a cellulosic material dissolved in an aqueous solution of sodium zincate containing an excess of sodium hydroxide and a waterproofing Wax of melting point above F. dispersed as the discontinuous phase in the cellulose and zincate solution, the composition because of the characteristics described undergoing precipitation of on acidification at a temperature below the melting point of the wax.

3. A waterproofing and coating composition for textiles and the like comprising cellulosic material dissolved in an aqueous solution of sodium zincate containing an excess of sodium hydroxide and emulsified therein, as the discontinuous phase, water repellent wax, a water soluble emulsifying agent, a soluble aluminum salt, and water, the composition because of the characteristics described undergoing precipitation of the cellulosic material and wax on acidification. 4. A waterproofing and coating composition for textiles and the like comprising cellulose dissolved in an aqueous solution of sodium zincate containing an excess of sodium hydroxide and emulsified therein, as the discontinuous phase, waterproofing wax of melting point above 100 F., a water soluble protein emulsifier, and asoluble aluminum salt, the composition because ,of the characteristics described undergoing precipitation of the cellulose and wax on acidification.

5. The method of waterproofing and coating an I article which comprises applying to the article the composition described in claim 2, acidifying the applied composition, to cause precipitation of the wax and cellulosic material, washing with a dilute aqueous solution of a soluble aluminum salt, and drying the washed product.

6. The method of waterproofing and coating an article which comprises applying to the article the composition described in claim 1, acidifying the applied composition to precipitate the cellulosic material neutralizing the acidity applying to the neutralized product a dilute aqueous solution of a soluble aluminum salt 01' a weak acid, and drying the resulting material.

'7. A composition as described in claim 1, the cellulosic material used being an alkali stable celulose ether.

SIDNEY M. EDELSTEIN.

REFERENCES CITED The following references are of record in the Katz Dec; 25, 1917