Flame retardant compositions with low formaldehyde content

Abstract

The instant invention relates to a composition useful as a precursor for imparting flame-retardant properties to textile articles, comprising a condensate of: (a) a tetrakis (hydroxyorgano) phosphonium sulfate THPS; (b) urea, or alternatively thiourea; (c) optionally, and preferably, an aliphatic hydroxyl-reactive compound, such an amine wherein said composition has a very low free formaldehyde content, namely of less than 0.1%.

Claims

1. A polymer precursor composition comprising a condensate of compounds comprising: (a) a tetrakis (hydroxyorgano) phosphonium sulfate in water having a pH in a range from 5.0 to 5.7; (b) urea or thiourea; and (c) an aliphatic hydroxyl-reactive compound having from 12 to 18 carbon atoms, wherein the molar ratio of (a)/((b)+(c)) is in a range from 1.5:1 to 4:1, and wherein said polymer precursor composition has a free formaldehyde content of less than 0.1% by weight, based on the total weight of the composition; and wherein the condensate is produced at a reaction temperature of less than 100 C.

2. The polymer precursor composition of claim 1, wherein the pH of (a) is in a range from 5.0 to 5.5.

3. The polymer precursor composition of claim 1, wherein the molar ratio of (a)/((b)+(c)) is in a range from 2:1 to 4:1.

4. The polymer precursor composition of claim 1 wherein said tetrakis (hydroxyorgano) phosphonium sulfate is tetrakis (hydromethyl) phosphonium sulfate.

5. The polymer precursor composition of claim 4 wherein said aliphatic hydroxyl-reactive compound (c) is an amine compound.

6. The polymer precursor composition of claim 1 wherein said aliphatic hydroxyl-reactive compound (c) is an amine compound.

7. The polymer precursor composition of claim 6 wherein the aliphatic hydroxyl-amine compound is one or more member selected from the group consisting of: n-dodecylamine; n-tridecylamine; and n-tetradecylamine.

8. The polymer precursor composition of claim 1 wherein the aliphatic hydroxyl-amine compound is one or more member selected from the group consisting of: n-dodecylamine; n-tridecylamine; and n-tetradecylamine.

9. The polymer precursor composition according to claim 1, wherein the condensate is produced at a reaction temperature of 80-85 C.

10. A process of preparing a polymer precursor composition having a free formaldehyde content of less than 0.1% by weight, based on the total weight of the composition form a condensate of: a. a tetrakis (hydroxyorgano) phosphonium sulfate; and b. a urea or thiourea; c. an aliphatic hydroxyl-reactive compound having from 12 to 18 carbon atoms, said process comprising the following successive steps: (2.1.) placing the compound (a) in water and adjusting the pH to a range from 5.0 to 5.7; (2.2) mixing the compound (c) and the mixture obtained in said step (2.1); (2.3) allowing the mixture obtained in said step (2.2) to react at a temperature lower than 90 C. to 115 C.; (2.4) mixing the compound (b) and the reaction product obtained in said step (2.3); (2.5) allowing the mixture obtained in said step (2.4) to react at a temperature of less than 100 C., and for a period of time from 0.5 hour to 4 hours, wherein the molar ratio of (a)/((b)+(c)) is in a range of 1.5:1 to 4:1.

11. The process of claim 10 wherein said aliphatic hydroxyl-reactive compound (c) is an amine compound.

12. The process of claim 11 wherein the aliphatic hydroxyl-amine compound is one or more member selected from the group consisting of: n-dodecylamine; n-tridecylamine; and n-tetradecylamine.

13. The process of claim 12 wherein said tetrakis (hydroxyorgano) phosphonium sulfate is tetrakis (hydromethyl) phosphonium sulfate.

14. The process according to claim 13 wherein the pH of the mixture of compound (a) in water is adjusted to a range of 5.0 to 5.5.

Description

EXAMPLE 1

1A. THPS-Urea Condensate

(1) A THPS-urea condensate according to the first variant of the invention (phosphonium:urea ratio of 2:1) has been prepared as followed:

(2) 2400 g tetrakis(hydroxymethyl)phosphonium sulfate solution (75% w/w THPS, 4.43 moles) was treated with 12 g of 50% w/w sodium hydroxide solution to give a mixture with a pH of 5.6. The mixture was heated in an oil-jacketed reactor to 40 C. and 266 g urea (4.43 moles) added in three portions over 15 minutes.

(3) The reaction mixture was then heated to 80-85 C., held at that temperature for 1.5 hours to complete the reaction, and then cooled. The pH of the cooled product was 4.7 and further additions of 20 g 50% w/w sodium hydroxide solution and 70 g water were made as final adjustments.

(4) The final product was analysed as follows.

(5) TABLE-US-00001 Assay (as THPS) 64.9% w/w pH 5.4 SG at 20 C. 1.375

(6) Measurement of free formaldehyde in the THPS starting material and the final reaction product gave the following results.

(7) TABLE-US-00002 Initial THPS 0.09% w/w HCHO THPS-urea condensate 0.07% w/w HCHO

(8) The THPS-urea condensate as obtained in this example displays significantly reduced odour during application to textile.

Effect of the Reaction Temperature

(9) In order to illustrate the effect of the temperature of the reaction between compounds (a) and (b) in the instant invention, the above example has been reproduced, with the same conditions, except that the reaction mixture was then heated to 100 C. instead of 80-85 C., and held at 100-104 C. for 1.5 hours to complete the reaction. In these conditions, a final content of HCHO greater than 0.1% was obtained in the THPS-urea condensate (more precisely: 0.15% w/w HCHO even when starting from a THPS having an initial content of 0.09% w/w HCHO).

1B. THPC-Urea Condensate

(10) For seek of comparison, a THPC-urea (with the same phosphonium:urea ratio of 2:1 as in Example 1 B) has been prepared as followed:

(11) 900 g tetrakis(hydroxymethyl)phosphonium chloride (82% w/w THPC, 3.87 moles) was treated with 58.1 g 25% w/w sodium hydroxide solution to give a mixture with a pH of 5.37.

(12) A portion of this was set aside and the remaining 915.5 g (containing 860 g THPC, 3.70 moles) was charged to an oil-jacketed reactor and heated to 45-50 C.

(13) 110 g urea (1.83 moles) was added in three equal portions and the reaction mixture heated to approximately 85 C. and held at that temperature for 1 hour. The product was then cooled and adjusted with a further 17.4 g 25% w/w sodium hydroxide solution and 55.7 g water.

(14) Measurement of free formaldehyde in the THPC starting material, the THPC after the initial pH adjustment and the final reaction product gave the following results.

(15) TABLE-US-00003 THPC 0.05% w/w HCHO THPC, pH 5.37 0.33% w/w HCHO THPS-urea condensate 0.12% w/w HCHO

EXAMPLE 2

THPS-Amine-Urea Condensates

(16) The examples of EP 0 709 518, that make use of THPC, have been reproduced and the free formaldehyde content has been measured. This content is systematically of more than 0.3%

(17) On the contrary, a THPS-amine-urea condensate prepared in similar conditions systematically lead to a free formaldehyde of less than 0.1%, especially when temperature is controlled: urea and a C18 amine as used in EP 0 709 518 were added to THPS instead of THPC (with a molar ratio THPS:urea:amine of 2.5:0.95:0.05addition at 45 C.), and then heated at 80 C. The final free formaldehyde was of less than 0.09%.

(18) The content of free formaldehyde has been found even lower if the amine is added first: in the same conditions, by adding first the amine at 45 C. to the THPS, reacting at 104 C., then cooling at 45 C. and adding the C18 amine and heating at 85 C. for 90 minutes, the final free formaldehyde was of less than 0.06%.

(19) More precisely, a THPS-amine-urea condensate with a formaldehyde content of 0.04% wt/wt was obtained as follows: 1200 g tetrakis(hydroxymethyl)phosphonium sulfate solution (75% w/w THPS, 2.22 moles) was charged to an oil-jacketed reactor and heated to 60 C. 12.4 g tetradecylamine (0.058 moles) was added and the mixture heated to 100-105 C. and held at that temperature for 75 minutes. The resulting reaction mixture was then cooled to 43 C. and 88.7 g urea (1.48 moles) was added in three portions over 20 minutes. The reaction mixture was re-heated to 80-85 C. and held at that temperature for 1.5 hours. After cooling an addition of 80 g water was made as a final adjustment.

(20) The final product was analysed as follows.

(21) TABLE-US-00004 Assay (as THPS) 64.7% w/w pH 4.1 SG at 20 C. 1.355

(22) Measurement of free formaldehyde in the THPS starting material and the final reaction product gave the following results.

(23) TABLE-US-00005 THPS 0.05% w/w HCHO 780JD134 0.04% w/w HCHO

(24) The THPS-amine-urea condensates as obtained in this example furthermore display significantly reduced odour during application to textile.

Effect of the Reaction Temperature

(25) The above example has been reproduced by reacting the urea at a higher temperature (more than 100 C. instead of less than 85%), which leads to a HCOH content of 0.28%: 1200 g tetrakis(hydroxymethyl)phosphonium sulfate solution (75% w/w, 2.22 moles) was treated with 12 g 24% w/w sodium hydroxide solution to give a mixture with a pH of 5.6. The mixture was heated to 40 C. in an oil-jacketed reactor and 88.7 g urea (1.48 moles) was added in three portions over about 15 minutes, followed by 12.4 tetradecylamine (0.058 moles). The mixture was heated to 100 C. and maintained at 100-104 C. for 3 hours. After cooling, the final solution strength was adjusted by the addition of 65 g water. The final product analysed as follows.

(26) TABLE-US-00006 Assay (as THPS) 66.1% w/w pH 3.5 S.G. at 20 C. 1.359 Measurement of free formaldehyde in the THPS starting material and the final reaction product gave the following results.

(27) TABLE-US-00007 THPS 0.06% w/w 780JD078 0.28% w/w