US 2418525 A
Description (OCR text may contain errors)
Patented Apr. 8, 1947 OFFICE MANIiFACTURE OF WATER-RESISTANT UN- LE ORG RIALS AND PRODUCT ANIC FIBROUS MATE- Frederick' F. Pollak, Brooklyn, N. Y.
No Drawing. Application September 29, 1942,
a Serial No. 460,179
6 Claims. (Cl. 117137) The invention relates to the manufacture of waterproof and water-resistant uninflammable textiles, fabrics, artificial silk and to impregnating substances adapted to be used in connection therewith.
The materials treated in accordance with this invention and garments made thereof cannot be ignited and do not produce a flame when subjected to combustion. They are also waterproof because the waterproofing substances employed for the impregnation of the textiles and fabrics in accordance with my invention are so strongly incorporated into the fibre and adhere thereto so intensely that they cannot be removed therefrom in spite of energetic treatment with water.
Garments made from the materials impregnated according to my invention are, therefore, particularly suited to be worn by military personnel, by firemen and people employed in installations where the danger of fire and explosions prevails.
Many suggestions have been made to impregnate fabrics with fire preventive and with waterproofing substances; however, these methods have not resulted in a successful application in spite of the fact that numerous substances are known which being individually applied to the fibres either prevent its combustion or cannot be removed therefrom by washing. Substances, however, which exert the combinative effect without rendering the impregnated textiles and fabrics hard and brittle are not known as yet.
If the requirement with regard to pliability and softness is not dominant, as for instance in stage curtains, an impregnation with silica and certain silicates will serve the purpose. However, garments impregnated with these aluminum-sulfate, ammoniumbromide, ammoniumsulfate, ammoniumphosphate, borates, boric acid, have been recommended for the manufacture of uninfiammable goods. These substances, however, are water soluble. Water insoluble orlnto the fibres by gluing; any practical work.
It has also been suggested to impregnate texvide impregnating 2 tiles and fabrics with'metastannic acid. The thus treated materials do not burn with a flame; however, they have the great disadvantage of extended glowing. The same phenomenon results from the application of heavy metal salts which due to this grave failure are and have never met with practical success.
Also certain organic components have been recdehyde condensation product has to render wood uninflammable.
However, the problem and textiles have surface than wood. The flame expansion, therefore, is much more rapid per surface unit of a fabric, whereas the impregnation capacity is small. Therefore, it is possible to protect wood against inflammation by coating the same with the above mentioned condensation products. If the wood is subjected to combustion the artificial resin has sufficient time to be converted into a voluminou carbonized coating which protects the wood. Fibers, however, are carbonized instantaneously; no time is available for a slagging action of the artificial resin; the latter, therefore, cannot be used to render textiles uninflammable or incombustible. Furthermore, a thorough impregnation with a sufficient quantity of these condensation products leads to very undesired hardening of the textiles and fabrics.
Hence, it results that the problem of the manufacture of simultaneously water resistant uninfiammable textiles and fabrics has not been solved satisfactorily as yet.
In view of the fact that the prospect of finding an appropriate inorganic impregnating substance was very remote, it is the object of the invention to provide organic impregnating compounds which render textiles and fabrics uninflammable and incbmbustible and prevent the creation of a long flame.
It is a further object of the invention to pro- 3 compounds or the aforesaid type which strongly adhere to the textiles and fabric and cannot be easily rubbed off.
It is also one of the objects of the invention to provide an impregnating substance which in addition to the above referred to properties prevents the impregnated textiles, fabrics and textiles from becoming hard, brittle and unelastic.
It is also an object of the invention to provide an impregnating substance for textiles and fabrics which prevents extended glowing.
Furthermore, the compounds which answer the requirements of my invention must be colorfree and must not attack the textiles and fabrics to which they are applied.
The last but not the least object of my invention is that the textiles and fabrics impregnated in accordance with the teachings of my invention in order to be utilized on an expanded commercial scale are resistant to treatments with weak soap and sodiumcarbonate solutions.
Hence, it results that a successful solution of the instant problem presents unexpected and severe difficulties particularly also in view of the fact that the impregnating substances in order to fully answer the instant requirements must be insoluble in ordinary organic solvents.
In the course of extensive experimentation and research Work I have found that the insoluble compounds of the amide derivates of the cyanuric acid most suitably comply with all of the aforesaid objects.
However, in order to complete the invention the difficulty of firmly securing these compounds on the textiles and fabrics had to be overcome. In this direction a satisfactory solution was established by the application of the amido compounds of the cyanuric acid as salts of phosphoric acids and particularly of the pyrophosphoric acid. This acid has the property of swelling the fibres of the textiles and particularly cotton fabrics to a remarkable degree, whereby a satisfactory loosening of the fibres is effected and their absorptive capacity for the amide compounds is greatly enhanced.
Instead of pyrophosphorlc acid metaphosphoric acid, sulphosphoric acid and oxalic acid may be advantageously used. As a most suitable substance as far as insolubility and securing capacity is concerned, a melamine pyrophosphate was established which consists of two mols melamine and one mol pyrophosphoric acid. The textiles and fabrics are preferably first impregnated with the acid and afterwards passed through a melamine bath. An insoluble very fine white precipitate is hereby formed which strongly adheres to the fibres and can only be removed by washing or similar water treatment. The herewith impregnated textiles and fabrics carbonize quickly when exposed to combustion, but they do not catch fire and do not glow afterwards.
However, and in spite of their resistance to water, the pyrophosphates of the cyanuric acid amides and particularly the melamine pyrophosphate show a certain sensitivity to the action of alkalis, salts and certain acids. It forms with salts and alkalis water soluble double salts and with certain acids soluble melamine salts. If the impregnated fabrics are contacted with solutions containing substances of the named type, the precipitate is partly dissolved and the combustibility of the materials treated in accordance with the invention is accordingly increased.
In order to avoid this inefficlency and to further improve the adherence of the precipitates in the textiles and fabrics the same are treated or coated Gil ' mentioned artificial resins are readily soluble in with an urea or thiouria condensation product 0 mixtures thereof.
These condensation products and particularl and uninflammable after being hardened by heating. For this hardening procedure an acid is required. If pure urea condensation products are used, a substance may be added which generates the acid at an elevated temperature such as dichlorhydrine. The same effect may be obtained by adding thiourea which at an elevated temperature generates a small quantity of sulfocyanic acid or by using pure thiourea formaldehyde condensation products.
Different procedures may be employed to apply solutions of these condensation products to the fibres.
The materials may first be treated with the pyrophosphates of the cyanuric acid; then the solutions of the above referred to condensation products are applied and hardened.
It is, however, preferable to combine the two treatments or to precipitate the melamine pyrophosphate in the solution of the urea or thiourea formaldehyde condensation product. The precipitate is very fine and its penetration power into the fibres is better; also its adherence to the fibre is improved and the whole process is greatly simplified.
If pure urea condensation products are used it is advisable to use solutions which result into the formation of hydrophobe resins.
The following examples serve to illustrate the invention:
Example I 76 parts by weight of thiourea are dissolved in 112.5 parts by volume of neutral formaldehyde at a temperature of 40 C. When the resulting exothermic reaction is over and no more formaldehyde smell is perceptible, 190 parts by volume of water and 30 parts by weight of melamine are added; the mixture is heated until a clear solution is obtained; the same is cooled to room temperature.
A fabric is impregnated with a 5% solution of pyrophosphoric acid and the excess of the liquid removed by wringing. The fabric is passed into the melamine solution whereupon a very fine precipitate is formed which penetrates into the fibres. The fabric is again wringed out and. heated to 120 to 140 (1., whereby the precipitate becomes insoluble. The fabric is now ready for use.
It is advisable to apply an additional coating of pure artificial resins to the treated goods in order to fully cover the surface of the same. The coating solution of the artificial resin should be less concentrated in order to avoid unnecessary hardness in the surface layers of "the treated goods.
The fact that the aqueous solutions of the above the melamine solution renders it possible to vary the combined method according to special requirements. Instead of the pure thiourea a mixture of equimolecular quantities of urea and thiourea may be employed.
Example II If a pure urea coating is to be produced the following procedure is adopted:
A well boiled cotton fabric is passed through sumes a milky appearance caused by a portion of the precipitate.
The first passage through the melamine solution may be omitted and the fabric may be directly introduced into the pyrophosphoric solution. In this case, it is advisable to leave the textile or fabric at least 30 minutes in the acid bath in order to produce an extensive swelling of the fibre.
The impregnated material may be dried and a coating film of a urea-formaldehyde resin now may be applied thereto. However, the coating may also be applied to the still moist material.
The film forming solution may be produced in the following manner:
30 parts by weight of urea are mixed with 81-87 parts by volume of a neutral 40% formaldehyde solution and boiled with the reflux condenser for minutes. Five parts by weight of boric acid dissolved in 50 parts in volume of hot water are now added and the mixture is boiled until a sample upon addition of a large quantity of water shows in the cold a distinct cloudiness; this generally happens after a boiling period of about four hours. The solution is cooled, .25 part of dichlorhydrine is added and the solution is now ready to be used for the production of sealing films on the impregnated textiles and fabrics.
For this purpose the textiles and fabrics impregnated with the melamine pyrophosphate are passed through the solution, the surplus solution is removed by wringing and the materials are dried at a temperature of 120-140 C.
The thus treated fibrous materials, textiles and fabrics are not only made uninfiammable and incombustible, but water and alkali proof and may be washed with soap and sodium carbonate. Cotton, burlap, jute, linen, artificial silk and similar fibrous materials may be equally well treated by the invention. The method is not only applicable to the finished goods, but also to thread, yarns and the like.
Example III Instead of using two baths the impregnation with the amido compound of the phosphoric acid may also be carried out on a flat machine in one bath.
For this purpose an insoluble dimelamine pyrophosphate is produced by either contacting the two components in their molecular proportions or by filtrating the fine precipitate produced in the melamine baths in accordance with Example I or II. The compound is suspended in the aqueous solution of the urea or thiourea formaldehyde condensation product also produced according to Examples I and II. The textiles are now impregnated with the suspension and dried at 120-140 0.; they have an appearance similar to those manufactured according to Examples I and H.
The coloring of the goods treated in accordance with the invention may be effected by adding dyes or coloring substances to the melamine solutions which are precipitated by the phos- 6* particularly suited, the latter being basic dyes. which are precipitated with tungsten phosphate and produce particularly bright and light resistant pigments.
The examples given above are not considered to be a limitation of the application of the methods and products of the invention because variations in percentages of the materials used, in the time and temperatures of the diflerent heatins steps, in the sequence thereof, in the mode of application and in the use of the products of reaction can be made by one skilled in the art to suit different requirements.
l. A method for rendering textiles and fabrics permanently not inflammable, water resistant and mildew proof, comprising passing the said materials through aqueous solutions containing pyrophosphoric acid and melamine, precipitating thereby on and within the fibres of the treated article finely divided melamine pyrophosphate .and insolubilizing the latter on the fiber by drytreated articlesat a temperature of about between 120 to 140 C. r
3. A method for rendering textiles and fabrics permanently not inflammable, water resistant and mildew proof comprising passing the said material first through an aqueous solution of pyrophosphoric acid, maintaining the articles in said solution to produce swelling of the fiber, thereafter passing the swelled article through an aqueous melamine solution, precipitating thereby on and within the fibre of the treated article a finely divided melamine pyrophosphate and insolubilising the latter on the fiber by drying the articles at a temperature of about between 120 to 140 C.
4. A method for rendering textiles and fabrics permanently not inflammable, water resistant and mildew proof comprising passing the said ma-- terial first through an aqueous solution of pyrophosphoric acid, maintaining the articles insaid solution to produce swelling of the fiber, thereafter passing the swelled article through an aquephoric acid. It is also possible to use colored ous melamine solution, precipitating thereby on and within the fibre of the treated article a finely divided melamine pyrophosphate, applying to the articles a coating of a substance selected of a group consisting of urea and thiourea formaldehyde condensation products and insolubilising the T melamine pyrophosphate precipitate on the fiber and the said coating by drying thetreated articles at a temperature of about between to C.
5. As a new product of manufacture a permanently not inflammable, water resistant, mildew proof fabric impregnated in situ with water insoluble melamine pyrophosphate distributed and anchored uniformly throughout the cellular structure of the fiber.
6. As a new product of manufacture a permanently not inflammable, water resistant and mildew proof fabric impregnated in situ with water mnnmcx F. POLLAK.
REFERENCES CITED The following reiferences are of record in the 10 file of this patent:
Number Number 8 UNITED s'm'ms mum's Name Date Cutler Aug. 29, 1933 DAlelio Jan. 30, 1945 Andrews July 22, 1924 FOREIGN PATENTS Country Date British Nov. 29, 1937 British Feb. 20, 1939 British June I, 1938