US 3900666 A
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United States Patent 11 1 St. Mard et al.
14 1 Aug. 19, 1975 1 FLAME RETARDANT TEXTILES BY USE OF NITROGENOUS TYPE RESIN AND ANTIMONY OXIDE  Inventors: Hubert H. St. Mard, New Orleans;
Albert S. Cooper, ,lr.; Carl Hamalainen, both of Metairie, all of La,
 Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.
22 Filed: June 4,1974
21 Appl. No.: 476,236
51 1m.c1 ..C09d 1/00 581 Field of Search 117/137, 139.5 A, 143 A, 117/161 LN  References Cited UNITED STATES PATENTS 2,299,612 10/1942 Clayton et al. 117/137 X Wagner 117/136 Wagner 117/137 X OTHER PUBLICATIONS St, Mard et a1., Colorless Weather-Resistant Finish For Outdoor Cotton Fabrics, American Dyestuff Reporter, Dec/5, 1966, TP89OA512, pp. 1046-1049.
Primary Examiner-Michael R. Lusignan Attorney, Agent, or FirmM. Howard Silverstein; Max D. Hensley 57 I ABSTRACT 14 Claims, No Drawings FLAME RETARDANT TEXTILES BY USE OF NITROGENOUS TYPE RESIN AND ANTIMONY OXIDE This invention relates to a process for imparting flame retardancy to blends of cellulosic fibers with polyester, acrylic. modacrylic and other synthetic fibers containing halogens or pretreated with halogen containing compounds.
Specifically, this invention relates to a process for imparting flame retardancy to the above fibers by treatment with a nitrogenous resin of the type used for durable press. for example dimethylol dihydroxyethylene urea (DMDHEU). propylene urea. or methylolated ureas, or treated with polymer formers, for example methylol melamine or modified methylol melamine types or mixtures thereof. More specifically, this invention relates to a process for imparting flame retardancy to the aforementioned fibers by use of the aforementioned resins and incorporating antimony oxide and/or other pigments used as supplementary flame retardants into the formulations.
DEFINITIONS AND NOTATIONS There are no definite limits to the ratio of the components of the blends of cellulosic fibers with synthetic fibers. Experimentation showed that the amount of cellulosic component can vary from about 25 to 85 percent and still result in a product with good flame retardancy.
The synthetic fabric used in illustrating the invention Consists essentially of a copolymer of acrylonitrile and vinylidene chloride. known generically as modacrylic." The modacrylic fabric isv known to possess a certain quantity of flame retardancy. As a consequence of this property the untreated fabric samples used in experimentation composed of a high ratio of modacrylic fibers are more flame retardant than fabrics composed of a correspondingly lower amount. As indicated in this specification. the objective of this invention is to render blended fabrics flame retardant.
THE PRIOR ART In the prior art it has been disclosed that flame retardancy can be achieved by the use of phosphorus type chemicals (see John V. Beninate. et al.. Textile Research 1.. Vol. 38, No. 3, pp. 267-272, March, 1968; John D. Guthrie, et al., Proceedings of the American Association of Textile Chemists and Colorists. American DyestuffRepurler, Vol. 44( pp.328332, 1955; and John V. Beninate. et al., American Dyestujf Reporter, Vol. 57(25), pp. 47-78, Dec. 22, I968). The phosphorus type chemicals have been used for imparting flame retardancy. The methods of the prior art i'mpart flame retardancy to wearing apparel and fabrics for indoor type uses.
One shortcoming of the above process is that fabrics so treated tend to lose flame retardancy when laundered with use of chlorine bleach. The treatments have never proven effective for outdoor use fabrics unless protected from actinic degradation by coatings, sunlight-screening pigments. etc.
Effective applications for outdoor-type fabrics are multi-purpose treatments based on chlorinated hydrocarbons and antimony oxide (see US. Pat. No. 2.299.612) which require high add-ons. i.e.. 35 to 70 percent. and cause fabric to be relatively impermeable to air and water vapor.
One object of this invention is to impart flame retardancy to fabrics intended for outdoor uses such as tents. tarpaulins. boat covers. etc. by treatment with a nitrog enous resin of the methylol melamine, modified methylol melamine, or urea formaldehyde tape. These resins are catalyzed by such metal salts as Zirconium acetate, zinc nitrate. magnesium chloride, etc. Besides rendering the fabrics flame retardant the process imparts to the fabrics weatherand rot-resistance (see H. H. St. Mard, et al., American Dyesruff Reporter. Dec. 5, 1966, Vol. 55. pp. 1.0464049).
Another object of this invention is to impart flame retardancy to fabrics intended as wearing apparel, indoor and industrial uses by treatment with such nitrogenous resins that impart durable press, crease resistance or wash and wear properties. Such nitrogenous resins are those used as erosslinkers such as DMDI-IEU, propylene ureas, and derivatives of ethylene ureas, urea-formaldehyde, and combinations of crosslinkers with polymer formers. These resins are catalyzed by the aforementioned metal salts and also by formic acid, tartaric acid, citric acid, ammonium chloride, magnesium chloride, etc. Besides rendering fabrics flame retardant the process imparts to fabrics durable press or wash wear properties.
In general, the present invention can best be described as a process forimparting flame retardancy to cellulosic material and/or cellulosic-synthetic blends intended for outdoor use by (a) impregnating a cellulosic material or blend thereof with a mixture containing about from 5 to 30 percent of an N-methylol resin, such as trimethylol melamine, about from 2 to 8 percent .of a metal salt catalyst, such as zirconium acetate, about from 0.1 to 0.5 percent of a wetting agent, such as the Rhom & Haas Triton W-30, which is an alkylaryl polyether alcohol; and about from I to 10 percent of a supplementary flame retardant, such as antimony oxide; (b) removing excess moisture from the impregnated material to obtain about from 40 to 100 percent wet pickup; (c) drying the impregnated material for about from 2 to 4 minutes at about 185F; and (d) curing the dried material at a temperature of about 285F for about 2-4 minutes. After curing the material can be washed or left unwashed.
It should be pointed out that although the preferred embodiments of the formulations of this invention show limits of antimony oxide to be about from I to 10 percent by weight in the formulation, experimentation indicates that values as high as about 30 percent can be used. It should further be pointed out that the higher amounts of antimony oxide produce the higher flame retardancy in the treated fabric.
The reason for not using the higher values should be obvious. The results obtained with the lower quantities have been found suitable for the manufacturing of outdoor-type fabric and sleepwear, and-further expenditures of antimony oxide would merely increase the cost of the treatments.
The following information will serve to illustrate the process of ,the invention. y i
A fabric consisting of percent cotton and 30 per cent modacrylicwas treated with the following formulationz' 68.0 grams Trimethylol melamine resin l7) 45.6 grams Zirconium acetate catalyst (5') 10.0 grams Antimony oxide (Z'M/r J Continued 0..\' grams Triton W10 (0.2; 1 275.6 grams Water 4000 grams This fabric was padded on a laboratory type padder to 5 a wet pickup of 85 percent. It was dried for 4 minutes at 185F in a gas-fired oven after which the fabric was cured in the same oven for 4 minutes at 285F. This fabric was left unwashed because it was intended for outdoor exposure. Whether or not fabric is washed after the cure step is dependent upon the end use of the product. The above formulation is a typical formulation for treating fabric for outdoor exposure.
The samples illustrated in Table I were produced using this type of typical formulation with the padding, drying, and curing times and temperatures conforming to the conditions as stated above.
TABLE I LII Fire Retardant Additive None 2.5% Sb,O
Untreated Control Fabric Blend Cot/ModAe The (mum and Modaerylie fabrics used here were knitted. "The (mum and Modacrylic fabric used here was woven,
St. Mard, Hamalainen, and Copper reported in Anu'rium Dywsmjf Reporter, Dec. 5. 1966, Vol. 55, pp. 1046-1049. that N-methylolmelamine resins confer limiting Oxygen Inde\ (1.01) is defined as the minimum volume fraction of oxygen in an atmosphere of oxygen and nitrogen which will just sustain the candlelike burning of a polymeric specimen.
1.01 n =(O )/I(O zJI A value greater than 0.260 is considered to be selfextinguishing or flame retardant.
A specific application of resins intended to impart flame-retardancy to fabrics to be used as wearing apparel and possessing durable press properties is noted in Table II.
As noted in Table 11 three different resin fomiulations were used. The formulation which was applied to fabric sample 1 contained 5 percent solids of dimethyloldihydroxyethylene urea (DMDHEU). The formulation which was applied to fabric sample 2 contained 15 percent solids of DMDHEU and the formulation which was applied to fabric sample 3 contained a mixture of resins containing 5 percent solids of DMDHEU and 10 percent solids of trimethylol melamine. In each application the resins were catalyzed by a mixture of2 percent zinc acetate and 0.5 percent zinc nitrate. The balance of the formulations in each instance contained 0.2 percent of a wetting agent such as Triton W-30 and water.
The fabric samples of Table II were treated the same as those in Table I as regards pads, dry, and cure conditions. The fabrics of Table II were given a process wash and dry step after the cure step. The fabric used was composed of a blend of 85 percent cotton and 15 percent modacrylie.
Fabric used was 85/15 Cotton Modaerylic. Catalyst used was 2% Zine Acetate and 0571- Zinc Nitrate.
appreciable rot and weather resistance to cellulosic fabric. The trimethylol melamine catalyzed with zirconium acetate was intended as a binder for the antimony oxide (a supplementary flame retardant) and at the same time conferring rot and weather resistance to the eellulosic samples. Unexpectedly, high oxygen index values were obtained using this resin treatment without the use of antimony oxide, as noted in Table I Undoubtedly, the residual ZrO of the zirconium acetate catalyst also imparts some flame retardancy to the samples. These relatively high oxygen index values were further enhanced by the same type resin treatment when antimony oxide was included in the formulation.
The burning characteristics of the samples were determined by the limiting Oxygen Index Method as measured 3 a unit such as that provided by Michigan Chemical Corporation and referred to as a Candle- Tester Smokt Densimeter lnitTDensiometer The TABLE III VIER'I'KAI. FLAMI: 'IliS'l \All'liS ()I" RIxSIN 'IRI'LA'IED (O'I'lON/bfl)I)A('RY1.l( FABRICS '/1 Standard ertical llame lest Fabric Blend Untreated 'l'rcated Samples otton/Modacr) lic ('ontrols (l-wash 50 washes 01 0 Failed 3. 3.25
TABLE Ill-Continued ofdinieihylol propylene urea .italyst was I lllk \lkk'ldlk and I 5'1 line nitrate The Standard Vertical Flame Test was used to measure flame retardancy of the fabrics of Table III. This test consists of igniting a ten inch by three inch fabric specimen in a special apparatus. The specimen is ignited in the ten inch direction and the residual char length of the burned specimen is measured. A char length of 7 inches or less is considered as passing the test.
As noted in Table III the untreated controls failed the test as each specimen burned the entire 10 inch length. The treated samples (O-wash) had char lengths of only 3.60 and 3.90 inches indicating good flame retardancy. A test for durability of flame retardancy is laundering and drying in home-type washers and dryers. The above fabrics after 50 wash and dry cycles had char lengths of 3.58 and 3.25 inches respectively. Indicating very good durability.
SUMMARY In brief. the present invention can best be described as a blended cotton and halogen-eontaining synthetic textile having flame retardancy and the process for producing said product. the process comprising:
1. impregnating a blended fabric whose composition is in the range of about from 85-15 to l585 percent by weight. respectively. of cotton and a halogencontaining synthetic textile. to about from 60 to 100 percent \vet pickup with a solution containing:
a. about from 6 to percent of a crosslinking and/or polymenl'orming N-methylol-type resin selected from the group consisting of trimethylol melamine. methylated methylol melamine. dimethylol dihydroxy ethylene urea and propylene urea;
b. about from 1 to 8 percent of an acid type catalyst selected from the group consisting ofa mixture of zinc acetate and vine nitrate. a mixture of tartaric acid and ammonium chloride, a mixture of citric acid and magnesium chloride. ammonium chloride, and zirconium acetate; and
c. about from 1 to 20 percent of antimony oxide as a flame retardant additive; and
2. drying at about 2-4 minutes at about 185"! and curing the impregnated blended fabric for about 2-4 minutes at about 285Tv We claim:
l. A process for imparting flame retardancy to a blended cotton and halogen-containing synthetic textile. the process comprising:
a. impregnating a blended fabric whose composition is in the range of about from -l5 percent to l5-fi5 percent by weight. respectively. of cotton and a hz'ilogcn-containing synthetic textile. to about from 60 to percent wet pickup with a solution containing:
I. about from 6 to 20 percent of a crosslinking and- /or polymer-forming N-methylol-type resin selected from the group consisting of trimethylol melamine, methylated methylol melamine, dimethylol dihydroxy ethylene urea and propylene urea.
2. about from 1 to 8 percent of an acid type catalyst selected from the group consisting of a mixture of zinc acetate and zinc nitrate, a mixture of tartaric acid and ammonium chloride, a mixture of citric acid and magnesium chloride, ammonium chloride. and zirconium acetate; and
3. about from 1 to 20 percent of antimony oxide as a flame retardant additive; and
b. drying at about 24 minutes at about F and curing the impregnated blended fabric for about 2-4 minutes at about 285F.
2. The process of claim I wherein the crosslinking and/or polymer-forming N-methylol-type resin is trimethylol melamine.
3. The process of claim 1 wherein the crosslinking and/or polymer-forming Nmethyloltype resin is dimethylol dihydroxy ethylen'eurea.
4. The process of claim 1 wherein the crosslinking and/or polymer-forming resin is a mixture of methylolated methylol melamine and dimethylol propylene urea.
5. The process of claim 1 wherein the catalyst is a mixture of zinc acetate and zinc nitrate.
6. The process of claim I wherein the catalyst is zinc nitrate.
7. The process of claim 1 wherein the catalyst is a mixture of tartaric acid and ammonium chloride.
8. The process of claim 1 wherein the catalyst is a mixture of citric acid and magnesium chloride.
9. The process of claim 1 wherein the catalyst is ammonium chloride.
10. The process of claim 1 wherein the catalyst is zirconium acetate.
11. The process of claim 1 wherein the catalyst is magnesium chloride.
12. The flame-resisting blended fabric produced by the process of claim 2.
13. The flame-resisting blended fabric produced by the process of claim 3.
14. The flame-resisting blended fabric produced by the process of claim 4.