Flame retardant propylene composition

Abstract

The invention relates to a flame retardant polypropylene composition comprising (A) a polypropylene-based polymer, (B) a first flame retardant in an amount of 15 to 40 wt % of the total composition, wherein the first flame retardant is in the form of particles comprising ammonium polyphosphate and at least one phosphate selected from the group consisting of melamine phosphate, melamine polyphosphate, melamine pyrophosphate, piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate, 2-methylpiperazine monophosphate, tricresyl phosphate, alkyl phosphates, haloalkyl phosphates, tetraphenyl pyrophosphate, poly(2-hydroxy propylene spirocyclic pentaerythritol bisphosphate) and poly(2,2-dimethylpropylene spirocyclic pentaerythritol bisphosphonate) and (C) a second flame retardant in an amount of 0.1 to 15 wt % of the total composition, wherein the second flame retardant comprises an aromatic phosphate ester.

Claims

1. A flame retardant polypropylene composition comprising (A) a polypropylene-based polymer, (B) a first flame retardant in an amount of 15 to 40 wt % based on a total weight of the flame retardant polypropylene composition, wherein the first flame retardant is in the form of particles comprising, based on a total weight of the first flame retardant: 5-15 wt % ammonium polyphosphate, 50-80 wt % melamine phosphate, 10-25 wt % piperazine phosphate, and 1-10 wt % zinc oxide, and (C) a second flame retardant in an amount of 0.1 to 15 wt % based on a total weight of the flame retardant polypropylene composition, wherein the second flame retardant comprises an aromatic phosphate ester.

2. The composition according to claim 1, wherein the polypropylene-based polymer is a propylene homopolymer or a propylene-α-olefin copolymer consist of at least 70 wt % of propylene and up to 30 wt % of α-olefin based on the total weight of the copolymer, wherein the α-olefin is selected from the group of α-olefins having 2 or 4-10 carbon atoms.

3. The composition according to claim 1, wherein the polypropylene-based polymer is a heterophasic propylene copolymer consisting of (a) a propylene-based matrix, wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene-α-olefin copolymer consisting of at least 70 wt % of propylene and at most 30 wt % of α-olefin, based on the total weight of the propylene-based matrix, and wherein the propylene-based matrix is present in an amount of 60 to 95 wt % based on the total heterophasic propylene copolymer, and (b) a dispersed ethylene-α-olefin copolymer, wherein the dispersed ethylene-α-olefin copolymer is present in an amount of 40 to 5 wt % based on the total heterophasic propylene copolymer, and wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-α-olefin copolymer in the heterophasic propylene copolymer is 100 wt %.

4. The composition of claim 1, wherein the first flame retardant has a normal particle size distribution (D50) of at least 8 microns as determined by Mastersizer 2000 available from Malvern.

5. The composition of claim 1, wherein the amount of phosphate in the first flame retardant is 40-75 wt % as measured after treating with nitric acid using ICP-OES spectrometer (iCAP 6300 Duo available from Thermo Fisher).

6. The composition of claim 1, wherein the aromatic phosphate ester is selected from the group consisting of resorcinol bis(diphenyl phosphate); tetraphenyl resorcinol bis(diphenylphosphate); bisphenol A bis(diphenyl phosphate); bisphenol A diphosphate; resorcinol bis(di-2,6-xylyl phosphate), phosphoric acid, mixed esters with [1,1′-biphenyl]-4-4′-diol and phenol; Phosphorictrichloride, polymer with 1,3-benzenediol, phenylester; 1,3-phenylene-tetrakis(2,6-dimethylphenyl)diphosphate; isopropenylphenyl diphenyl phosphate; 4-phenylphenolformaldehyde phenylphosphonate; tris(2,6-xylyl) phosphate; Resorcinol bis(di-2,6-xylyl phosphate); bisphenol S bis(diphenyl phosphate); resorcinol bisphenol A phenyl phosphates.

7. The composition of claim 1, wherein the composition further comprises a fluorine resin with a surface modification.

8. An article comprising the composition of claim 1.

9. The article according to claim 8, wherein the article is selected from the group consisting of caps and closures, batteries, pails, containers, external and internal parts in appliances, circuit breaker cover, drain pan in refrigerator, deflection coil of TV, stadium seats, automotive exterior parts, automotive interior parts, or automotive parts under the bonnet.

10. The composition of claim 7, wherein the fluorine resin is polytetrafluoroethylene and the surface modification is styrene-acrylonitrile copolymer.

11. The composition of claim 3, wherein the α-olefin in the propylene-α-olefin copolymer is selected from the group of α-olefins having 2 or 4 to 10 carbon atoms.

12. The composition of claim 11, wherein the α-olefin in the ethylene-α-olefin copolymer is selected from the group of α-olefins having 3 to 8 carbon atoms.

13. The composition of claim 1, wherein the polypropylene-based polymer is a propylene homopolymer.

14. The composition of claim 1, wherein the aromatic phosphate ester comprises Bisphenol A bis(diphenyl phosphate).

15. A process for the preparation of the composition according to claim 1, comprising melt mixing (A), (B), and (C) and optional components.

Description

EXAMPLES

(1) Materials as shown in Table 1 were used in the experiments.

(2) TABLE-US-00001 TABLE 1 Description Polypropylene 1 PP Homopolymer, MFI 47 g/10 min Flame retardant 50-60% piperazine pyrophosphate, 35-45% phosphoric 1A acid compound, and 3-6% zinc oxide Flame retardant 10-15% Ammonium polyphosphate, 60-70% Melamine 1B phosphate, 15-20% phosphoric acid compound (not melamine phosphate), and 3-8% zinc oxide.) Flame retardant Bisphenol A bis(diphenyl phosphate) 2 Anti-drip agent Teflon (PTFE) encapsulated by Styrene-Ancrylonitrile copolymer Polypropylene 2 heterophasic propylene copolymer comprising a matrix phase of a propylene homopolymer and a dispersed phase of propylene-ethylene copolymer having MFI of 30 g/10 min, Dispersed phase (RC): 19.1 wt %, Ethylene in dispersed phase (RCC2): 47.2 wt %, Ethylene in heterophasic propylene copolymer (T2): 9 wt % Polypropylene 3 heterophasic propylene copolymer comprising a matrix phase of a propylene homopolymer and a dispersed phase of propylene-ethylene copolymer having MFI of 3 g/10 min, Dispersed phase (RC): 21.1 wt %, Ethylene in dispersed phase (RCC2): 52.1 wt %, Ethylene in heterophasic propylene copolymer (T2): 11 wt %

(3) Polypropylene was pre-mixed with other additives and the mixture was extruded using a twin-screw extruder to obtain pellets. The pellets were dried at 100° C. for 3 h and injection molded using FANUC injection molding machine (S-2000i) to prepare test specimens.

(4) The MFI of the composition was measured according to ISO1133 (2.16 kg/230° C.).

(5) The flame retardancy was measured according to the UL94 test standard at a sample thickness of 3 mm, 1.5 mm and 0.8 mm. The samples were conditioned at 23° C. and 50% relative humidity for 48 hours prior to testing or at 70° C. and 50% relative humidity for 168 hours. The sample bars were burnt at the gated end for Vx evaluation.

(6) Charpy impact strength was measured according to ISO 179 at 23° C. by Toyoseiki Digital Impact DG-UB equipped with a pendulum of 2 J (test geometry: 80*10*4 mm).

(7) The flexural modulus was measured according to ISO 178 (parallel; test geometry: 80*10*4 mm).

(8) Results are summarized in Tables 2 and 3.

(9) TABLE-US-00002 TABLE 2 Unit #1 #4 #9 #17 #18 #19 #20 #21 Polypropylene wt % 76.9 76.6 76.6 79.6 78.6 77.6 76.6 74.6 1 Flame wt % 23 23 retardant 1A Flame wt % 23 20 20 20 20 20 retardant 1B Flame wt % 1 2 3 5 retardant 2 T-SAN wt % 0.3 0.3 0.3 0.3 0.3 0.3 0.3 antioxidant 1 wt % 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 antioxidant 2 wt % 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 MFI g/10 min 24.42 17.27 28.62 30.71 30.76 26.66 26.91 26.69 FR (3 mm) V0 V0 V0 V0 V0 V0 V0 V0 23° C., 48 h FR (3 mm) V0 V0 V0 V0 V0 V0 V0 V0 70° C., 168 h FR (1.5 mm) V2 V0 V0 V2 V0 V0 V0 V0 23° C., 48 h FR (1.5 mm) V2 V0 V0 V2 V1 V0 V0 V0 70° C., 168 h FR (0.8 mm) F F V1 V0 V0 23° C., 48 h FR (0.8 mm) F F V0 V0 V0 70° C., 168 h Charpy kJ/m2 1.27 1.22 1.27 1.28 1.75 1.31 1.54 1.37 impact Flex modulus Mpa 2275.53 2355.44 2073.46 2036 2010 2028 1950 1912

(10) In Table 2, the propylene-based polymer is a propylene homopolymer.

(11) From the comparison of #4 and #9, it can be understood that the use of the FR 1B results in a much higher MFI compared to when the FR 1A is used, which leads to a better processability. The use of FR 1B also results in a lower flexural modulus compared to when FR 1A is used.

(12) From the comparison of #17-#21, it can be understood that the use of FR 2 in combination with FR 1B results in a better flame retardancy. A higher amount of FR 2 results in a better flame retardancy. When the amount of FR 2 is too high, the flexural modulus decreases.

(13) TABLE-US-00003 TABLE 3 Unit #27 #28 #32 Polypropylene 2 wt % 73 72 73 Polypropylene 3 wt % 6.63 5.63 6.63 Flame retardant wt % 20 20 18 1B Flame retardant wt % 2 2 2 T-SAN wt % 0.25 0.25 0.25 antioxidant 1 wt % 0.06 0.06 0.06 antioxidant 2 wt % 0.06 0.06 0.06 MFR g/10 min 16.8 19.1 17 FR (3 mm) V0 V0 V0 23° C., 48 h FR (3 mm) V0 V0 V0 70° C., 168 h FR (1.5 mm) V1 V0 V1 23° C., 48 h FR (1.5 mm) V1 V1 V1 70° C., 168 h Charpy impact kJ/m2 3.1 2.88 4 Flex modulus Mpa 1708 1662 1574

(14) In Table 3, the propylene-based polymer is a mixture of two types of heterophasic propylene copolymer.

(15) From the comparison of #27 and #28, it can be understood that the use of FR 2 in combination with FR 1B results in a better flame retardancy.

(16) From the comparison of #27 and #32, 2% it can be understood that replacing part of FR1B with the same amount of FR2 can maintain the flame retardancy while improving the impact strength.