DOPO-based hybrid flame retardants

Abstract

The invention relates to novel and improved halogen-free flame retardant compounds having the structure of Formula (I): wherein: R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1-C.sub.6 alkyl, P(O)(OR.sup.3).sub.2, P(O)OR.sup.3R.sup.4, or P(O)R.sup.3.sub.2, wherein R.sup.3 and R.sup.4 are independently C.sub.1-C.sub.4 alkyl, C.sub.6-C.sub.12 aryl, C.sub.7-C.sub.15 aralkyl or C.sub.7-C.sub.15 alkaryl; or R.sup.1 and R.sup.2 taken together form an unsaturated cyclic ring, which is optionally substituted by an alkyl group; each k is independently an integer from 1 to 2; each X is independently oxygen (O) or sulphur (S); v is 0 or 1; each Y is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene, C.sub.7-C.sub.15 alkarylene, oxygen (O), nitrogen (NR), wherein R is H or C.sub.1-C.sub.4 alkyl; n is 0, 1 or 2 with the proviso that n is 1 when Y is oxygen (O) or nitrogen (NR); each Z is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene or C.sub.7-C.sub.15 is alkarylene; m is independently 0, 1 or 2; with the proviso that when Y is oxygen (O) or nitrogen (N), m cannot be 0; each Q is independently C.sub.1-C.sub.4 alkylene; t is an integer from 1 to 2; W is oxygen (O) or sulphur (S). The compounds are particularly suited as flame retardant additives for thermoplastic polyesters.

Claims

1. A flame retardant compound having the structure of Formula I: ##STR00007## wherein: R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1-C.sub.6 alkyl, P(O)(OR.sup.3).sub.2, P(O)OR.sup.3R.sup.4, or P(O)R.sup.3.sub.2, wherein R.sup.3 and R.sup.4 are independently C.sub.1-C.sub.4 alkyl, C.sub.6-C.sub.12 aryl, C.sub.7-C.sub.15 aralkyl or C.sub.7-C.sub.15 alkaryl; or R.sup.1 and R.sup.2 taken together form an unsaturated cyclic ring, which is optionally substituted by an alkyl group; each k is independently an integer from 1 to 2; each X is independently oxygen (O) or sulphur (S); v is 0 or 1; each Y is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene, C.sub.7-C.sub.15 alkarylene, oxygen (O), nitrogen (NR), wherein R is H or C.sub.1-C.sub.4 alkyl; n is 0, 1 or 2 with the proviso that n is 1 when Y is oxygen (O) or nitrogen (NR); each Z is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene or C.sub.7-C.sub.15 alkarylene; m is independently 0, 1 or 2; with the proviso that when Y is oxygen (O) or nitrogen (N), m cannot be 0; each Q is independently C.sub.1-C.sub.4 alkylene; t is an integer from 1 to 2; W is oxygen (O) or sulphur (S).

2. A flame retardant compound according to claim 1, selected from the group consisting of: DOPO-PEPA, and DOPS-PEPA.

3. A polymeric material with improved flame resistance, comprising at least one thermoplastic polymer resin, at least one flame retardant compound according to claim 1, and optionally any conventional additives.

4. The polymeric material according to claim 3, wherein the thermoplastic polymer resin is a thermoplastic polyester resin.

5. The polymeric material according to claim 3, further comprising a nitrogen based flame retardant agent, as a second flame retardant component.

6. The polymeric material according to claim 3, in the form of granules or in moulded form.

7. The polymeric material according to claim 6, wherein the total content of the flame retardant component (I) is 14% to 30% by weight of the total weight of the composition.

8. The polymeric material according to claim 3, in the form of fibres.

9. The polymeric material according to claim 8, wherein the wherein the total content of the flame retardant component (I) is 5% to 20% by weight of the total weight of the composition.

10. The polymeric material according to claim 3, wherein the flame retardant compound is deposited as a surface layer.

11. A method of making a flame retardant compound according to claim 1, the method comprising reacting compound of Formula (A): ##STR00008## with a compound of Formula (B): ##STR00009## in the presence of a base, wherein: a) R.sup.1, R.sup.2, m, X, v, Y, n and Z are defined above, T can be hydrogen or a halogen selected from Cl, Br or I, with the proviso that when T is hydrogen both n and m are 0, and wherein Q, t, W are defined above and L is a hydroxyl (OH); or: b) R.sup.1, R.sup.2, m, X, v, Y, n and Z are defined above, T is hydroxyl (OH) and m is different than 0, and wherein Q, t, W are defined above and L is a halogen selected from Cl, Br or I.

12. A polymeric material with improved flame resistance, comprising at least one thermoplastic polymer resin, at least one flame retardant compound according to claim 2, and optionally any conventional additives.

13. The polymeric material according to claim 12, wherein the thermoplastic polymer resin is a thermoplastic polyester resin.

14. The polymeric material according to claim 12, further comprising a nitrogen based flame retardant agent, as a second flame retardant component.

15. The polymeric material according to claim 13, further comprising a nitrogen based flame retardant agent, as a second flame retardant component.

16. The polymeric material according to claim 4, further comprising a nitrogen based flame retardant agent, as a second flame retardant component.

17. The polymeric material according to claim 4, in the form of granules or in moulded form.

18. The polymeric material according to claim 17, wherein the total content of the flame retardant component (I) is 14% to 30% by weight of the total weight of the composition.

19. The polymeric material according to claim 5, in the form of granules or in moulded form.

20. The polymeric material according to claim 19, wherein the total content of the flame retardant component (I) is 14% to 30% by weight of the total weight of the composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above mentioned and other features and objects of this invention and the manner of achieving them will become more apparent and this invention itself will be better understood by reference to the following description of various embodiments of this invention taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 shows DSC curves of the Arnitel products and Arnitel 622+Example 1 (14 wt %).

DETAILED DESCRIPTION OF THE INVENTION

Examples

(3) The following examples illustrate the present invention. It is to be understood, however, that the invention as described herein and as recited in the claims is not intended to be limited by the details of the following Examples.

Example 1

Synthesis of DOPO-PEPA

(4) ##STR00005##

(5) In this example 500 g 9,10-dihydro-9-oxa-phosphaphenanthrene-10-oxide (DOPO) and 458 g pentaerythritol phosphate alcohol (PEPA) was placed in 1.5 L dichloromethane (DCM). 221 mL N-methyl imidazole (NMI) was added to the stirring suspension followed by 248 mL carbon tetrachloride (CCl.sub.4) added drop-wise, over a period of 1 h. During the addition of CCl.sub.4, the temperature was kept between 1520 C. Subsequently, the reaction mixture was refluxed for 6 h. After cooling down, the dichloromethane was distilled under vacuum and the product was precipitated out with water (2 L). After stirring for 3 hours the product was filtered as a white powder and dried at 60 C. under vacuum to a constant weight, yielding 744 g (82%) DOPO-PEPA.

(6) Melting point: m.p.=222 C. (based on DSC, heating rate=5 C. min.sup.1)

(7) Thermal stability: T.sub.5%=338 C.; T.sub.63%=700 C.

(8) Phosphorus content: 15.71 wt %

(9) .sup.1H-NMR, (ppm): 3.98-4.09 (m, 2H); 4.48 (d, =6.5 Hz,); 7.34-7.40 (m, 2H), 7.51 (t, 7.7 Hz, 1H); 7.65 (dt, J=3.8 Hz, J=7.4 Hz, 1H); 7.85-7.95 (m, 2H); 8.20-8.27 (m, 2H) 13C-NMR, (ppm): 37.48, 61.87, 75.02, 119.95, 120.65, 121.92, 124.86, 125.39, 126.03, 128.91, 130.03, 131.06, 134.41, 136.35, 148.87.

(10) .sup.31P-NMR, (ppm): 7.18; 10.96.

Example 2

Synthesis of DOPS-PEPA

(11) ##STR00006##
In this example, the suspension of 10 g 6-chloro-6H-dibenzo[c,e][1,2]oxaphosphinine (DOP-Cl) and 1.6 g S.sub.8 in 100 mL toluene was heated to reflux for 5 h. After cooling it to room temperature, 3.7 mL N-methyl imidazole (NMI) was added followed by 8.4 g pentaerythritol phosphate alcohol (PEPA). The temperature was kept between 15-20 C. during the addition. Subsequently, the reaction mixture was refluxed for 3 h. After cooling it to room temperature, the precipitated product was filtered, washed with water (2300 mL) and alcohol (2300 mL). The obtained white powder was dried at 60 C. under vacuum to a constant weight, yielding 12.3 g (70%) DOPS-PEPA.

(12) Melting point: m.p.=200 C. (based on DSC, heating rate=5 C. min.sup.1)

(13) Thermal stability: T.sub.5%=296 C.; T.sub.64.%=700 C.

(14) Phosphorus content: 15.10 wt %

(15) .sup.1H-NMR, (ppm): 3.99-4.09 (m, 2H); 4.33-4.42 (m,); 7.36-7.41 (m, 2H), 7.52 (t, =8.0 Hz, 1H); 7.63-7.67 (m, 1H); 7.85 (t, =8.0 Hz, 1H); 7.95-8.02 (m, 1H), 8.18-8.22 (m, 2H)

(16) .sup.13C-NMR, (ppm): 37.28, 61.83, 74.94, 119.96, 122.24, 124.73, 125.10, 125.58, 126.03, 128.93, 130.81, 131.02, 134.13, 134.35, 148.77.

(17) .sup.31P-NMR, (ppm): 7.27; 77.03.

Examples 3 and 4

Flame Retardant TPE-E (Arnitel 622)

(18) Melt Processing:

(19) Various Arnitel compositions were prepared on a co-rotating twin screw extruder (Haake Polylab OS, model PTW 24/40, Germany) with a screw diameter of 24 mm and a L/D ratio of 40. Dosing of the materials was performed using a gravimetric feeding system (Three Tec, Switzerland). All compositions were processed at identical screw rotational speed. The measured temperature of the melt was 230 C. for all the formulations. The composite melt was passed through a nozzle, cooled to room temperature in a water bath and cut into granules. The granules were dried at 100 C. for 12 hours in a vacuum oven. The analysed granules were conditioned at 50% relative humidity for 72 hours.

(20) The resulting compounds were as follows:

(21) Example 3: Arnitel CM622 with 18 wt % DOPO-PEPA (Example 1) (2.8 wt % P-content), m.p.=224 C.

(22) Example 4: Arnitel CM622 with 14 wt % DOPO-PEPA (Example 1) (2.2 wt % P-content), m.p.=224 C. and 4 wt % Melapur MC 50 (melamine cyanurate)

(23) Comparative Example 5: Arnitel CM622 containing no flame retardant additive (0 wt % P-content), m.p.=218 C.

(24) Comparative Example 6: Arnitel LX07000 containing a halogenated flame retardant additive (0 wt % P-content), m.p.=226 C.

(25) Comparative Example 7: Arnitel CM600 containing a nitrogen based flame retardant additive (0 wt % P-content), m.p.=216 C.

(26) ASTM D3801 UL94Vertical Burning Test

(27) The dried granules were compression moulded into 1 mm thick plates and cut to the dimensions (1255 mm long by 13.00.5 mm wide) required by the ASTM D3801 UL94Vertical Burning Test (V-0, V-1, or V-2).

(28) TABLE-US-00001 TABLE 1 UL94 Vertical burning tests Compositions Rating Comparative Example 5 No rating Comparative Example 6 V2 Comparative Example 7 V2 Example 3 V0 Example 4 V0
Differential Scanning Calorimetry (DSC)

(29) Differential scanning calorimetry measurements were carried out to evaluate the Arnitel formulations (FIG. 1). The first heating cycle (using a heating rate of 5 C. min.sup.1) was used to assess the melting point of the compounds as reported above. After cooling down with a cooling rate of 10 C. min.sup.1 the formulations were heated again at a heating rate of 10 C. min.sup.1. In the second heating cycle, only the composition of Example 3 revealed identical melting point with the pristine TPE (Comparative Example 5). The decrease of the melting temperature of a thermoplastic composition in the second heating cycle strongly suggests a deterioration of the molecular weight of the thermoplastic segment and therefore a drop in its desired mechanical and physical properties. These measurements indicate the good compatibility and no adverse effect of the additive of Example 1 on the polymer matrix. Resistance to elevated temperatures of the Arnitel compositions is important in view of their major application in the automotive industry for under the hood applications and from recyclability point of view.

Example 8

Flame Retardant PET Fibres

(30) Ready-to-spin PET granules, with a viscosity of 1.40 g cm.sup.3 were premixed with 5 wt % of the hybrid flame retardant from Example 1 and introduced in a spinneret, through a hopper, comprising a single screw extruder with a diameter of 13 mm and a length-to-diameter (L/D) ratio of 25. A monofilament spinneret was used with a diameter of 0.5 mm and a length-to-diameter (L/D) ratio of 4. The PET compositions were spun having a melt temperature of 270 C. and at a winding speed of 1650 m min.sup.1. The monofilament PET compositions obtained with a draw ration of 5.5, were having a diameter of =59 m and fibre linear densities of 36 dtex. The obtained flame retardant PET fibre (Example 8) has a corresponding P-content of 0.8 wt %, whereas Comparative Example 9 was prepared as a control example without added flame retardant.

(31) The physical properties of the fibres are listed in Table 2. Comparative Example 9 is the control sample.

(32) TABLE-US-00002 TABLE 2 Physical properties of flame retardant PET fibre Example 8 and Comparative Example 9 Tenacity Elongation P-content PET Fibre (cN/tex) (%) (wt %) UL94 Rating Example 8 44.67 (1.59) 18.34 (3.55) 0.8 V0 Comparative 46.19 (1.13) 18.63 (2.55) 0 V2 Example 9

(33) For the evaluation of the fire resistance, the PET fibres were knitted into a fabric with a density of 0.130.03 g cm.sup.2. Five samples, with a length of 10 cm, were cut out from each Example, having an average weight of 10.02 g. The 1005 mm long tightly rolled samples were subjected to vertical burning tests following the testing procedure and materials classifications as described in ASTM D3801 UL94Vertical Burning Test (V-0, V-1, or V-2) and the results are listed in Table 2.

Example 10

Flame Retardant PBT (ULTRADUR)

(34) Various Ultradur compositions were prepared on a co-rotating twin screw extruder (Haake Polylab OS, model PTW 24/40, Germany) with a screw diameter of 24 mm and a L/D ratio of 40. Dosing of the materials was performed using a gravimetric feeding system (Three Tec, Switzerland). All the compositions were processed at identical screw rotational speed. The composite melt was passed through a nozzle, cooled to room temperature in a water bath and cut into granules. The granules were dried at 80 C. for 12 hours in a vacuum oven. The analysed granules were conditioned at 50% relative humidity for 72 hours.

(35) The resulting compounds were as follows:

(36) Example 10: Ultradur with 20 wt % DOPO-PEPA (Example 1) (3.2 wt % P-content) and 4.5 wt % Melapur MC 50 (melamine cyanurate)

(37) Comparative Example 11: Ultradur containing no flame retardant additive (0 wt % P-content)

(38) ASTM D3801 UL94Vertical Burning Test

(39) The dried granules were compression moulded into 1 mm thick plates and cut to the dimensions (1255 mm long by 13.00.5 mm wide) required by the ASTM D3801 UL94Vertical Burning Test (V-0, V-1, or V-2).

(40) TABLE-US-00003 TABLE 1 UL94 Vertical burning tests Compositions Rating Comparative Example 11 No rating Example 10 V0