US2524783A

US2524783A - Method of imparting durable mildew resistance to fibrous cellulose materials

Info

Publication number: US2524783A
Application number: US18724A
Authority: US
Inventors: Florence M Ford; William P Hall
Original assignee: Joseph Bancroft and Sons Co
Current assignee: Joseph Bancroft and Sons Co
Priority date: 1948-04-02
Filing date: 1948-04-02
Publication date: 1950-10-10
Anticipated expiration: 1967-10-10

Description

Patented Oct. 10, 1950 METHOD OF IMPARTIN G DURABLE DIILDEW RESISTANCE T FIBROUS CELLULOSE MATERIALS Florence M. Ford and William P. Hall, Wilmington, Del., assignors to Joseph Bancroft & Sons 00., Wilmington, Del., a corporation of Delaware No Drawing. Application April 2, 1948, Serial No. 18,724

This invention relates to the imparting of durable mildew resistance to fibrous cellulose materials.

Cellulose materials such as textile fabrics, are subject to attack by fungi, particularly in certain localities, which causes serious degradation of and alteration in the cellulose, resulting in undesirable changes in appearance and physical characteristics, primarily 'in a very marked loss in tensile strength. This phenomenon is usually referred to as mildewing and is responsible for the rapid destruction of textile fabrics in many portions of the world.

We have discovered that if acid be chemically combined with cellulose in the dry state to produce an acid-cellulose complex, the fabric or other fibrous material is not only rendered midew resistant but the finish is durable to water and will withstand weathering for long periods of time. Moreover, this result can be obtained through the use of relatively small quantities of acid so that tendering of the fabric is substantially avoided and the fabric in very large part retains its original strength. The finish also does not interfere with other finishes, such as waterproofing, which are frequently employed in the textile field. It aso does not interfere with dyeing and is very effective on dyed goods.

As illustrative of the invention, we prepare an aqueous solution of an acid, such as orthophosphoric, impregnate the fabric with said solution, preferably with a 100% solution pick-up by weight of the fabric in the dry state, after which the fabric is dried and then baked or cured at elevated temperatures, i. e., from 300 F. to 400 F. for a .period of time ranging from 30 minutes to 2-minutes, in an oven to bring about the chemical reaction between the acid and the cellulose. The drying and the baking may be performed as a single step, but it is preferable to first dry the material employing conventional drying temperatures. By proceedingin this fashion there is less likelihood of tendering of the fabric.

Similarly, to avoid tendering as much as possible, it is desirable to incorporate in the solution a nitrogen containing organic base soluble in acid solution and basic therein, as a buffering agent, such, for example, as urea, which competes with the cellulose for the acid but which does not prevent the chemical combination between the acid and the cellulose during the baking. The ratio of carbon to nitrogen in the base should not be higher than 2 to l. The reason that it is desirable to incorporate such a buffering agent is that mass action is involved and more acid must 3 Claims. (c1. 8-1162) be applied to the fabrc than is represented by the amount of base element of the acid (or the amount of acid in terms of base element of the acid) combined in the finished, washed fabric. The presence of such a buffering agent in the solution tends to avoid tendering during the drying operation. Some nitrogen may be carried into the complex by the acid, but the presence of nitrogen in the final complex is of no importance in obtaining the mildew resistance.

The mildew resistance is obtained by the replacement of hydroxyl groups in the cellulose by acid groups.

The concentration of the solution itself is not critical, as the needed amount of acid to secure the desired degree of mildew resistance may be applied to the fabric by several impregnations of a dilute solution. We prefer, however, to use a concentration which will result in the application of the desired amount of acid by a single application of the solution with solution pick-up on the weight of the fabric in the dry state, and in all of the examples hereinafter given a 100% solution pick-up by weight of the dry fabric is employed. Parts are by weight.

As illustrative of the practice of the invention, undyed cotton cloth was impregnated with the following solution:

300 parts orthophosphoric acid (75%) 600 parts urea 4100 parts water Pounds Warp strength treated fabric before burial Warp strength treated fabric after burial 121 Warp strength untreated fabric after burial (too weak to measure) 0 The strength tests were conducted on a regular Scott tester, using 1 inch x 3 inch test samples.

These results show the protective action afforded by the process with this acid, with a ratio of acid groups to pyranose units of 1 to 20 inthe 3 finished, i. e., the washed, dried fabric, or .96%

I phosphorus.

Cotton cloth was impregnated with the same solution and the same procedure was followed, with the exception that the temperature employed for curing was 300 F. and the time minutes.

The results obtained were substantially the same as those obtained in the first example.

Cotton fabric was impregnated with the same solution and the same procedure followed, with the exception that in this instance the temperature of curing was 400 F. and th time 2 minutes.

Substantially the same results were obtained as in the first example.

In the aforesaid examples, the base element of the acid, i. e., phosphorus, is present in the finished, i. e., washed and dried fabric, the ratio thereof in terms of acid to pyranose units being 1 to 20, This ratio gives very effective mildew resistance and is about as high a ratio as should be employed when using an acid substantially as strong as orthophosphoric acid.

If a less degree of mildew resistance is desired, the amount of acid may be reduced.

Thus, for example, a cotton fabric was impregnated with the following solution:

100 parts orthophosphoric acid (75 300 parts urea 41,600 parts water by weight and the same procedure was followed as before, with a curing temperature of 350 F. and a time of 8 minutes. In the washed dried fabric the ratio of phosphorus in terms of acid to pyranose units was about 1 to 600 or .0294% phosphorus. With this ratio appreciable mildew resistance was obtained but not as good as obtained in the previously mentioned examples. With orthophosphoric acid, this is about as low a ratio as should be employed.

With such ranges, the amount of orthophosphoric acid applied to the material will range from .2% to 4.5% by weight of the material in the dry state, having in mind also the particular temperature and time within the temperature time ranges given.

As to the pH of the solution, the initial pH thereof is unimportant so long as the pH on the cured cloth comes down during the curing and before washing to from 2 pH to '7 pH as determined by indicator solutions. The reaction between the acid and the cellulose occurs only under acidic conditions. Urea is a relatively weak base, i. e., change in the amount thereof has no pronounced effect on the pH of the solution. During the curing certain reactions take place which cause the pH to fall within the range above indicated. In fact the pH of the solution may even be on the alkaline side so long as the pH comes down during the curing due to the reactions occurring during the curing, The preferred pH on the cured cloth before Washing is from 3 to 6 pH as determined by indicator solutions. The urea may be used in amounts ranging from 1 mol to 10 mols of urea to 1 mol of acid, the preferred range being 1 mol to 4 mols to 1 mol of acid.

In place of the phosphoric acid, other acids may be equally well substituted, such, for example, as metaphosphoric acid, pyrophosphoric acid, ortho, metaand pyrophosphorus acids, phosphamic acid, phosphotungstic acid, sulfuric acid, sulfamic acid, phytic, and similar relatively strongly effective acids. Also weaker acids may be used, such as tartaric, lactic, maleic, malic, malonic, phthalic, citric, succlnic, pyroantimonic, dehydroxydiphenic, molybdic, tungstic, vanadic, telluric, selenic, salicyclic, fluosilicic, benzoic and nitric. In fact any soluble acid, organic or inorganic, substantially non-volatile, which will react with the cellulose to replace hydroxyl groups under the temperature and time ranges hereinbefore stated is suitable. Since there is a variation in effectiveness, this must be taken into consideration and an amount of acid should be employed which gives an effect at least substantially equivalent to that obtained in the case of orthophosphoric acid with a ratio ranging from 1 to 20 to 1 to 600 of acid to pyranose units in the finished fabric after washing and drying.

Metal salts and organic substituted salts of the acids having free acidity, for combination with the cellulose may also be employed. The excess acidity may be temporarily neutralized by means of a base volatile during curing, such, for example, as ammonium hydroxide.

In fact many substituted acids are very effective as the substituents may have anti-fungus properties which enhance the effect of the acid combined with the cellulose, being carried into the complex by the acid, When substituting these for orthophosphoric acid, the amount employed should be at least sufiicient to give equivalent effects of orthophosphoric acid when employed alone.

Many suitable organic compounds may be attached to the acids by substitution, such, for example, as phenyl, phenol, cresol, bromocresol, dihydroxyhexachlorodiphenylmethane, chlorophenyl, chlorophenol, B-naphthol, chloronaphthalene, dihydroxydichlorodiphenylmethane, alkylphenols, dichlorodiphenyltrichloromethane, naphthalene, alkylnaphthalene, thymol, chlorothymol, xylene, chloroxylene, O-phenylphenol, chloro-o-phenylphenol, toluol, chlorotoluol, anthraquinone, chloroanthraquinone, and hydroxyanthraquinone.

It will be seen that these listed compounds or groups are of a ring structure and contain one or more rings in their constitution and may, therefore, be classified as carbocyclic compounds. Chlorine, fluorine, bromine and iodine may also be introduced into said compounds, thereby increasing the mildew resistance in the substituting material.

In using the compounds just mentioned it is sometimes advantageous to attach more than one acid group to the same mildew resistant groups. For example, phenol disulfonic acid, Z-naphthol- 6,8-disulfonic acid, anthraquinone-1,5-disulphonic acid, and phenyl diphosphoric acid, may be used. In the case of the dior polysulfonic acids, polybasic properties are introduced into the compound by the use of two or more acid groups, and this, as will be further explained, is very beneficial.

The use of' monobasic acids is not practical unless the substitution leaves a. free reactive acid hydrogen to react with the cellulose and the required reactions, therefore, will take place. To illustrate, substitution in nitric acid, as, for example, nitrobenzene, will not produce a compound capable of reactingwith the cellulose as there is no free acid group available.

Quaternary ammonium compounds, especially those containing aromatic groups, and hydroxyl chloro or bromo substituted aromatic groups, have good mildew-preventing properties. These basic compounds, when substituted in the aforementioned acids, as, for example, in orthophosphoric acid, may be used with success, as, for example, lauryldimethylphenol ammonium acid phosphate, alphaalphagammagammatetramethylbutylphenoxyethoxyethyldimethylbenzyl ammonium acid phosphate and dimethyllauryl benzyl ammonium acid phosphate, the substituted phosphoric acid in these cases combining with the cellulose under the conditions of the process givelement, in the form of a salt, an oxide or hydroxide, is added to the impregnating solution. The salt of the inorganic element ma be of a Weak acid not substantially reactive with the cellulose, such as, for example, acetic or it maybe of a strong acid capable of reacting with the cellulose, such as orthophosphoric. In the latter case the acid introduced by the salt into the solution should replace a corresponding quantity of acid in the solution formula. In the former case,

the acid introduced with the salt does not react I with cellulose and the regular quantity of reactive acid must be used. In case an insoluble precipitate is formed in solution between the basic element and the acid, the method is not practical without steps being taken to solubilize the insoluble salt. With a salt such, for example, as copper phosphate, excess ammonium may be used with advantage to obtain a clear solution for impregnation.

Mildew resistant organic groups may also be introduced into the acid through an inorganic element, for example, phenylmercuric acid phosphate, and phenyl cadmium acid phosphate may be used under the conditions described above.

The acid employed which, in addition to being active enough to combine with the cellulose under the conditions of the process, should not be excessively volatile during processing, should preferably be soluble in the solution, and should not detrimentally alter the physical characteristics of the substituted mildew resistant compounds and should preferably show good durability toward water. v

The enhancing mildew resistant substance or substances may be introduced through the basic or buffering material, instead of directly through the acid. To this end, in addition to the presence in the solution of the base as such, the substituted base is added. This ordinarily is not as economical. It is to be understood that where the mildew resistant substance is introduced with the buffering material, it is nevertheless still carried to some extent into the complex by the acid.

When the mildew resistant groups are to be attached to base material, it is preferable to attach them to a strong base because the strongbase usually tends to attach itself more. readily to the acid. The su'bstituent group or groups must not be such as to alter the basic properties of the base to such an extent that its function as 9. base during the curing will be destroyed or excessively altered.

The amount of buffering base should be at least such as to secure adequate buffering of the acid. When used in the quantities giving the pH values hereinafter set forth, satisfactory results are obtained.

For the urea other organic buffering agents of the character described may be employed, such, for example, as biuret, acetamide, dicyandiamide, guanyl urea, amino-guanidine, biguanide, guanidine carbonate, oxalamidine, carbohydrazidine, and the like. Where strong bases are used they should be used in combination with weak bases, such, for example, as urea, and guanidine, for the reason that the initial pH of the solution presents no particular difficulty where a combination of strong and weak bases is employed, whereas if only strong bases are employed then it is necessary to very carefully control the pH of the solution so as to ensure its being on the acidic side during the curing. Non-metallic salts of the base may be employed. Substituted bases may be employed.

The general requirements of the buffering base are that it should be soluble, free of metal, basic toward the acid, and non-volatile under the curing conditions.

Generally speaking, the lower the temperature of curing the longer the time and vice versa. Similarly, the lower the acid concentration in the solution the higher should be the temperature and in some cases, the longer the time. The preferred temperature is from 340 F. to 375 F. and the time from 8 to 4 minutes.

In the following examples a single application of solution with roughly a solution pickup by weight on the dry material was employed, with all parts by weight.

Enample I A scoured and dyed cotton fabric was impregnated with the following mixture:

375.0 parts phosphotungstic acid 330.0 parts urea 250.0 parts water squeezed, dried, aged 15 minutes at 340 F., washed thoroughly in runningwater 180-190 R, and finally dried.

The treated fabric and a piece of untreated similar fabric were buried in the soil for 8 weeks to test the resistance to deterioration, the latter being determined by measuring the tensile strength retention of the treated fabric as compared with the fabric strength before burial and with the fabric strength of the untreated fabric after burial. The untreated sample test also serves as a guarantee that the soil contained in gredients causing cellulose deterioration.

The tensile strength tests were as follows:

, Pounds Warp strength treated fabric before buriaL- Warp strength treated fabric after buria.l 127 Warp strength untreated fabric after burial (too weak to measure) 0 tained in this example. Substantial resistance can be obtained with even a much lower ratio as will appear hereinafter.

Example II A scoured and dyed cotton fabric was padded with the following mixture:

290.0 parts telluric acid 440.0 parts urea 1000.0 parts water followed by drying, curing 30 minutes at 340 F., washing thoroughly in hot water and finally drying The treated fabric and a piece of untreated sample were buried in the soil for 8-weeks and the following tensile strength retention tests obtained.

Pounds Warp strength treated fabric before burial 119 Warp strength treated fabric after burial 51 Warp strength untreated fabric after burial Example I I I A desized, scoured, mercerized and dyed fabric was treated as in Example I, curing being done minutes at 350 F. The impregnating mixture consisted of 720.0 parts molybdic acid anhydride 1320.0 parts urea 1000.0 parts ammonium hydroxide (28%) 500.0 parts water The treated and untreated fabrics were soil buried for 8 weeks and the following tensile strength tests obtained:

Pounds Warp strength treated fabric before burial 138 Warp strength treated fabric after burial 69 Warp strength untreated fabric after burial 0 Example IV A pure cotton fabric was padded through the following mixture:

450.0 parts lactic acid 1320.0 parts urea 1000.0 parts water dried, aged 5 minutes at 340 F., washed 15 minutes in hot running water (ISO-190 F.) and flnally dried.

Treated and untreated fabrics were soil buried for 8 weeks and then tested for tensile strength. The following results were obtained:

Pounds Warp strength treated fabric before burial 135 Warp strength treated fabric after burial 98 Warp strength untreated fabric after burial- 0 Example V A pure dyed cotton fabric was treated as described in Example IV, the mixture consisting of:

74.0 parts acid phthalic anhydride 125.0 parts alcohol 132.0 parts urea Treated and untreated cloths were buried for 8 weeks and the following tensile strength tests obtained:

' Pounds Warp strength treated fabric before burial 128 Warp strength treated fabric after burial 90 Warp strength untreated fabric after burial '0 Example VI A pure dyed cotton fabric was treated as described in Example IV, the impregnating mixture consisting of:

75.0 parts tartaric acid 132.0 parts urea 100.0 parts water Treated and untreated fabrics were soil buried for 8 weeks and the following tensile strength results obtained:

Pounds Warp strength treated fabric before burial 129 Warp strength treated fabric after burial 61 Warp strength untreated fabric after burial 0 Example VII A pure dyed cotton fabric was treated as described in Example IV. The mixture had the following composition:

130.0 parts citric acid 132.0 parts urea 100.0 parts water Treated and untreated cloths were soil buried for 8 weeks and the following tensile strengths obtained:

Pounds Warp strength treated fabric before burial 126 Warp strength treated fabric after burial 76 Warp strength untreated fabric after burial 0 Example VIII Cotton fabric was treated as described in Example IV, the padding solution consisting of:

125.0 parts tungstic acid 1320 parts urea .1000 parts ammonium hydroxide 300.0 parts water A similar fabric was padded with the above mixture, dried but not aged. It was then washed 15 minutes in hot water (180-190 F.) and dried.

The two treated fabrics and an untreated fabric were subjected to the Chaetomium test as described in U. S. Quartermaster Corps Specification P. Q. D. 447A and the following tensile strength tests obtained:

- thoroughly in running water 180190 F.

This example shows the durability obtained by the aging treatment.

Example IX A scoured and dyed cotton was padded, using the following impregnating mixture:

33 parts dicyandiamide 50 parts orthophosphoric acid 750 parts water 56 parts formamide 7 parts guanidine carbonate squeezed, dried, aged 7 minutes at 330 F., washed and finally dried.

9 Treated and untreated fabrics were soil buried for 8 weeks and then tested:

. Pounds Warp strength treated fabric before burial 137 Warp strength treated fabric after burial 120 Warp strength untreated fabric after burial Example X A scoured and dyed cotton fabric was padded. using the following impregnating mixture:

15 parts phosphotungstic acid 3000 parts water 30 parts urea squeezed, dried, aged 15 minutes at 340 F., washed thoroughly in running water 180-190 F. and finally dried.

The cloth contained .17% phosphotungstic acid or 1 acid group to every 10,600 pyranose units (average of five tests).

Treated and untreated fabrics were subjected to the Chaetomium test as described in U. S. Quartermaster Corps Specification P. Q. D. 447A and the following tensile strength tests obtained:

Pounds Warp strength treated fabric before test 113 Warp strength treated fabric after test 107 Warp strength untreated fabric after test 0 Example XI A cotton fabric was treated as described in Example IV with the following mixture:

50.0 parts sulfuric acid (con.) 132.0 parts urea 350.0 parts Water A treated fabric and an untreated fabric were soil buried for 8 weeks and then tested for tensile strength.

Pounds Warp strength of treated fabric before burial 120 Warp strength of treated fabric after burial 108 Warp strength of untreated fabric after burial 0 Example XII A sample of pure hemlock wood pulp was impregnated with the following mixture:

65 parts orthophosphoric acid (75%) 132 parts urea 5200 parts water followed by drying, curing minutes at 340 F., washed well in hot water, filtered :and dried.

Samples of treated and untreated pulp were given the Chaetomium test. The untreated pulp showed heavy fungus growth while the treated pulp remained unaffected.

Example XIII A piece of pure dyed viscose rayon fabricwas impregnated with the following mixture:

66 parts orthophosphoric acid (75%) 132 parts urea 1100 parts water dried, aged 5 minutes at 340 F., washed 15 minutes in hotrunning water (180-190 F.) and finally dried.

10 .5, Treatgd and untreated fabrics wr soil buried for 8 we ks and then tested:

' Pounds Warp strength treated fabric before burial Warp strength treated fabric after burial 86 Warp strength untreated fabric after burials. 0

Example XIV A scoured, mercerized and bleached cotton fabric was impregnated with the following mixture:

280.0 parts naphtha thiophosphonic acid 330.0 parts urea 1000.0 parts water Pounds Warp strength treated fabric before burial 136 Warp strength treated fabric after burial--- 96 Warp strength untreated fabric after burial 0 Example XV A dyed cotton fabric was impregnated with the following padding mixture:

16 parts copper oxide 52 parts orthophosphoric acid (75%) 42 parts ammonium hydroxide 100 parts urea 1030 parts water dried, aged 5 minutes at 340 F., washed 15 minutes in hot running water (-190" F'.) and finally dried.

I 7 Pounds Warp strength treated fabric before test 104 Warp strength treated fabric after test 103 Warp strength untreated fabric after test 0 Example XVI A cotton fabric was impregnated with the following sizing mixture:

49 parts phenol-disulfonic acid 810 parts water 200 parts urea 82 parts guanidine carbonate dried, aged 5 minutes at 340 F., washed 15 minutes in hot running water (180-190 F.) and finally dried.

Treated and untreated fabrics were tested as described in Example XV. The following results were obtained:

Pounds Warp strength treated fabric before test 107 Warp strength treated fabricafter test 106 Warp strength untreated fabric after test 0 11 Example XVII A cotton fabric was padded with the following mixture 40.0 'parts phenyl phosphonic acid 66.0 parts urea 200.0 parts water dried, aged 10 minutes at 340 F., washed 15 minutes in hot running water (180-190 F.) and dried.

Treated and untreated fabrics were soil buried for 8 weeks and then tested:

Pounds Warp strength treated fabric before burial 135 Warp strength treated fabric after burial 121 Warp strength untreated fabric after burial- Example XVIII A cotton fabric was impregnated with the following mixture;

100.0 parts orthophosphoric acid (75%) 65.0 parts dicyandiamide 150.0 parts urea 28.0 parts phenylbiguanide 1869.0 parts water Example XIX A cotton fabric was impregnated with the following mixture:

53.0 parts orthophosphoric acid (75%) 81.0 parts urea 65.0 parts phenyl-guanidine carbonate 800.0 parts water dried, aged minutes at 340 F., washed 15 minutes in hot running water (ISO-190 F.) and finally dried.

Treated and untreated fabrics were soil buried for 8 weeks and the following results obtained:

Pounds Warp strength treated fabric before burial 139 Warp strength treated fabric after burial 88 Warp strength untreated fabric after burial 0 Example XX A cotton fabric was padded with the following mixture:

65.0 parts orthophosphoric acid (75%) 132.0 parts urea 27.0 parts chromium fluoride 5200.0 parts water dried, aged 5 minutes at 340 F.. washed 15 minutes in hot running water (180-190 F.) and final- .ly dried.

' Pounds Warp strength treated fabric before test 110 Warp strength treated fabric after test 112 Warp strength untreated fabric after te t-= .2

, 12 Example XXI Tetra-chloro-phenyl phosphoric acid was prepared by flrst reacting together tetra-chlorophenol, phosphorous oxychloride and magnesium chloride and then vacuum distilling,

A cotton fabric was padded through the following mixture:

50.0 parts of the above distillate 50.0 parts urea 150.0 parts acetic acid dried, aged 10 minutes at 330 F., washed 15 minutes in running hot water (180-190 F.) and dried.

Treated and untreated fabrics were tested as described in Example XX and the following results obtained:

Pounds Warp strength treated fabric before test 115 Warp strength treated fabric after test 115 Warp strength untreated fabric after test" 22 Example XXII A scoured and dyed cotton fabric was impregnated with the following mixture:

20 parts phenyl phosphoric ac d 25 parts phenol disulfonic acid 200 parts urea 50 parts guanidine carbonate 800 parts water dried, aged 24 minutes at 300 F., washed 15 minutes in hot running water (180-190" F.) and finally dried.

Treated and untreated fabrics were soil buried for 8 weeks and then tested:

Pounds Warp strength treated fabric before burial 102 Warp strength treated fabric after burial 90 Warp strength untreated fabric after burial 0 Example XXIII A piece of viscose rayon fabric was impregnated with the following mixture:

50 parts anhydrous monofiuorophosphoric acid 132 parts urea 3100 parts water dried, aged 5 minutes at 340 F., washed 15 minutes in hot running water (180-190 F.) and finally dried.

Treated and untreated fabrics were soil buried for 8 weeks and then tested:

Pounds Warp strength treated fabric before burial 90 Warp strength treated fabric after buria1 85 Warpstrength untreated fabric after burial 0 Example XXIV A sample of pure washed wood pulp was impregnated with the following mixture:

65.0 parts orthophosphoric acid 132.0 parts urea 27.0 parts chromium fluoride 5200.0 parts water followed by drying, curing 10 minutes at 330 F'., washed well in hot water, filtered and dried.

13 Example XXV A cotton fabric was treated as described in Example XVIII, the sizing mixture consisting of:

200 parts salicylic acid 400 parts urea 50 parts cyanoacetamlde 2000 parts water Treated and untreated fabrics were tested as described in Example XXII. The following results were obtained:

Pounds Warp strength treated fabric before test 98 Warp strength treated fabric after test 97 Warp strength untreated fabric after test"- The treated cloth gave a test for salicylic acid grouping. When the same mixture was applied and the cloth was dried and washed but not cured, the resulting fabric failed to give a test for salicylic acid, showing that no combination with the fabric is obtained in the latter case.

Example XXVI A cotton fabric was treated as described in Example XVIII, the si'lng mixture consisting of:

500 parts mon-ofiuorophosphoric acid 640 parts guanidine carbonate 1500 parts water The cloth contained 2.5% monofluorophosphoric acid, or 1 acid group to every 25 pyrancse units.

Treated and untreated fabrics were soil buried for 8 weeks and then tested:

- Pounds Warp strength treated fabric before burial 116 Warp strength treated fabric after burial 110 Warp strength untreated fabric after burial 0 Example XXVII A cotton fabric was treated as described in Example XVIII, the sizing mixture consisting of:

500 parts tetrachlorophthalic anhydride 1000 parts urea 1000 parts ammonium hydroxide solution Treated and untreated fabrics were buried for 8 weeks and then tested.

Pounds Warp strength treated fabric before burial 120 Warp strength treated fabric after burial 108 Warp strength untreated fabric after burial 0 The fabric contained 3.1% combined tetrachlorophthalic anhydride or 1 anhydride group -to 55 pyrancse units.

Example XXVIII A pure undyed cotton fabric was treated as described in Example XVIII, using:

parts monocopper phosphotungstic acid 30 parts urea 3300 part water The cloth contained 0.1 monocopperphosphotungstic 'acid, equivalent to 0.002% phosphorus or 1 acid group to every 18,520 pyranose units.

Treated and untreated fabrics were soil buried for 8 weeks and then tested.

Pounds Warp strength treated fabric before burial 145 Warp strength treated fabric after burial 118 Warp strength untreated fabric after burial- 0 Example XXIX 130 parts dicyandiamide 200 parts orthophosphoric acid (75%) 200 parts water, heat to 108 C.

300 parts urea 28 parts guanidine carbonate 40,000 parts water Padded on pure cotton herringbone twill. Dried, cured 5 minutes at 340 F., washed and dried.

Analysis showed 0.33% H3PO4 equals 0.104% P equals 185 pyrancse units to 1 HaPO4.

Mildew tests used: Metarrhizium glutinosum Duration of test: 6 days and 16 days Results: Decrease in tensile strength by meterrhizium glutinosum Tensile strength Original decrease tensile Strength 6 days 16 days Per cent Per cent untreated 119 12 67 treated 108 0 26 Example XXX 130 parts dicyandiamide 200 parts orthophosphoric acid (75%) 200 parts water, heat to 108 C.

300 parts urea 28 parts guanidine carbonate 81,000 parts water Padded on pure cotton herringbone twill, dried, cured 5 minutes at 340 F., washed and dried.

Analysis showed 0.09% HaPO4 equals .0284% P equals 600 pyrancse units to 1 H3PO4.

Mildew test used: Metarrhizium glutinosum Duration of test: 6 days and 16 days Results: Decrease in tensile strength by metarrhizium glutinosum Tensile Strength Original Decrease Tensile Strength 6 days 16 days Per cent Per cent Untreated 119 12 67 Treated 113 5 48 Example XXXI A cotton fabric was impregnated with the following sizing mixture:

100 parts orthophosphoric acid parts urea 100 parts acetamide 1500 parts water This application is a continuation in part of application Serial No. 596,592, filed May 29, 1945, now Patent Number 2,482,755.

We claim:

l. The process oi! imparting mildew resistance to fibrous cellulose material which consists in impregnating the material with an aqueous solution of phosphoric acid and urea, the amount of solids applied to the material being equal to that applied by a single application of solution with 100% solution pick-up in the weight of the material in the dry state when the solution contains from 0.2% to 4.5% acid by weight of the solution 10 with the urea present in the ratio of from 1 mol to 4 mols to 1 mol of acid, drying the material, baking the dried material at temperatures of from 400 F. to 300 F. for from 2 to 30 minutes, and washing and drying the material, the pH of the solution being such that the pH of the cured fabric before washing is from 2 pH to '7 pH as determined by indicator solutions, and the temperature and time selected being such as to introduce ture is from 340 F. to 375 F.

3. The process of claim 1 in which the pH is from 3 to 6.

- FLORENCE M. FORD.

Name I Date Ford et al. Sept. 2'7, 1949 Number

Claims

1. THE PROCESS OF IMPARTING MILDEW RESISTANCE TO FIBROUS CELLULOSE MATERIAL WHICH CONSISTS IN IMPREGNATING THE MATERIAL WITH AN AQUEOUS SOLUTION OF PHOSPHORIC ACCID AND UREA, THE AMOUNT OF SOLIDS APPLIED TO THE MATERIAL BEING EQUAL TO THAT APPLIED BY A SINGLE APPLICATION OF SOLUTION WITH 100% SOLUTION PICK-UP IN THE WEIGHT OF THE MATERIAL IN THE DRY STATE WHEN THE SOLUTION CONTAINS FROM 0.2% TO 4.5% ACID BY WEIGHT OF THE SOLUTION WITH THE UREA PRESENT IN THE RATIO OF FROM 1 MOL TO 4 MOLS TO 1 MOL OF ACID, DRYING THE MATERIAL, BAKING THE DRIED MATERIAL AT TEMPERTURES OF FROM 400*F. TO 300* F. FOR FROM 2 TO 30 MINUTES, AND WASHING AND DRYING THE MATERIAL, THE PH OF THE SOLUTION BEING SUCH THAT THE PH OF THE CURED FABRIC BEFORE WASHINGIS FROM 2 TO PH TO 7 PH AS DETERMINED BY INDICATOR SOLUTIONS, AND THE TEMPERATURE AND TIME SELECTED BEING SUCH AS TO INTRODUCE INTO THE COMPLEX A RATIO OF ACID TO PYRANOSE UNITS OF 1 TO 20 TO 1 TO 600 IN THE WASHED DRIED MATERIAL.