Mica coated with metal oxide as a flame retardant

Abstract

The invention relates to the use of mica coated with at least one metal oxide as flame retardant, and also thermoplastic molding compositions provided therewith.

Claims

1. A thermoplastic molding composition comprising: a) from 30 to 90% by weight of at least one thermoplastic polymer as component A, wherein component A is at least one polyamide and/or polyester, b) from 0.5 to 10% by weight of at least one mica coated with a metal oxide as component B, wherein the metal oxide coated on the at least one mica increases fire resistance of the thermoplastic molding composition as a flame retardant is present in an amount from 5 to 80% by weight relative to the mica and comprises (i) at least one of ZnO and V.sub.2O.sub.5, and (ii) not more than 20% by weight, based on the total amount of mica in the coating, of further metal oxides other than ZnO or V.sub.2O.sub.5, c) from 2 to 25% by weight of at least one flame retardant different from component B as component C, d) from 0 to 35% by weight of at least one functional polymer different from component A as component D, e) from 1 to 60% by weight of glass fibers as component E, and f) from 0 to 10% by weight of further auxiliaries as component F, wherein: the total amount of the components A to E is 100% by weight.

2. The thermoplastic molding composition according to claim 1, wherein component C is a phosphinic acid salt, a halogen-comprising flame retardant, phosphorus, a melamine compound, or a mixture of two or more thereof.

3. The thermoplastic molding composition according to claim 1, wherein component C is selected from the group consisting of c1) aluminum diethylphosphinate and/or aluminum hypophosphite, c2) aluminum diethylphosphinate and/or aluminum phosphite in combination with at least one melamine compound, c3) red phosphorus, and c4) polypentabromobenzyl acrylate.

4. The thermoplastic molding composition according to claim 1, wherein component D is present in an amount of 0.1 to 35% by weight and is poly(2,6-dimethyl-1,4-phenylene oxide).

5. The thermoplastic molding composition according to claim 1, wherein the coating is free from metal oxides other than ZnO or V.sub.2O.sub.5.

6. The thermoplastic molding composition according to claim 1, wherein the metal oxide coated on the at least one mica comprises: (i) ZnO, and (ii) not more than 10% by weight, based on the total amount of mica in the coating, of further metal oxides other than ZnO or V.sub.2O.sub.5.

7. The thermoplastic molding composition according to claim 1, wherein: the metal oxide coated on the at least one mica comprises: (i) V.sub.2O.sub.5, and (ii) not more than 10% by weight, based on the total amount of mica in the coating, of further metal oxides other than ZnO or V.sub.2O.sub.5.

8. The thermoplastic molding composition according to claim 1, wherein the at least one thermoplastic polymer as component A is polybutylene terephthalate.

9. The thermoplastic molding composition according to claim 1, wherein the at least one thermoplastic polymer as component A is at least one polyimide.

10. The thermoplastic molding composition according to claim 1, wherein the thermoplastic molding composition comprises from 30 to 70% by weight of the at least one thermoplastic polymer as component A.

11. The thermoplastic molding composition according to claim 10, wherein the metal oxide coated on the at least one mica comprises V.sub.2O.sub.5.

12. The thermoplastic molding composition according to claim 1, wherein: the metal oxide coated on the at least one mica comprises: (i) V.sub.2O.sub.5, and (ii) not more than 10% by weight, based on the total amount of mica in the coating, of further metal oxides other than ZnO or V.sub.2O.sub.5; and the at least one thermoplastic polymer as component A is at least one polyamide.

13. The thermoplastic molding composition according to claim 1, wherein the metal oxide coated on the at least one mica in component B is present in an amount from 20 to 50% by weight relative to the mica.

14. The thermoplastic molding composition according to claim 1, wherein: component A is present in an amount from 30 to 70% by weight; component B is present in an amount from 0.5 to 5% by weight; component C is present in an amount from 2 to 25% 5 to 20% by weight; and component E is present in an amount from 5 to 50% by weight.

15. The thermoplastic molding composition according to claim 1, wherein: component A is present in an amount from 50 to 65% by weight; component B is present in an amount from 0.5 to 2% by weight; component C is present in an amount from 5 to 20% 8 to 20% by weight; and component E is present in an amount from 10 to 40% by weight.

16. A process for producing thermoplastic molding compositions according to claim 1 by mixing the constituents.

17. A molding, fiber, or film comprising a thermoplastic molding composition according to claim 1.

18. A process for producing moldings, fibers, or films comprising melting, extruding, and subsequent shaping of a thermoplastic molding composition according to claim 1.

Description

EXAMPLES

(1) Starting Materials

(2) TABLE-US-00006 A PA66 VZ 120 cm.sup.3/g, Ultramid ®A24, from BASF SE Polyamide 6 VZ 150 cm.sup.3/g, Ultramid ®B27, from BASF SE Polybutylene terephthalate VZ 130 cm.sup.3/g, Ultradur ®B4500, from BASF SE D Glass fibers OCF DS 1110 Glass fibers PPG 3786 C0 Diethylphosphinate salt of aluminum e.g. Exolit © OP 1230 Clariant AG (DEPAL) C1 Red phosphorus masterbatch, 52% P Masteret ® from Italmatch Chemicals C2 Polypentabromobenzyl acrylate FR1025 (ICL Industries) C3 Melamine polyphosphate (MPP) Melapur ® M200, BASF Switzerland D1 Poly(2,6-dimethyl-1,4-phenylene oxide) Sigma Aldrich B Mica-ZnO Production as per trial A B1 Zinc oxide Emsure ® from Merck KgaA B2 Mica-V2O5 Production as per trial B B3 Zinc oxide Bayoxid ®Z aktiv from Bayer AG F Calcium stearate Ceasit AV N,N′-Hexamethylenebis[3-(3,5-di-t- Irganox ®1098 from BASF SE butyl-4-hydroxyphenyl)propionamide Untreated mica BASF SE

(3) Processing:

(4) The processing of the molding compositions was carried out as indicated using a DSM Xplore 15 microcompounder. The extruder was operated at a temperature of 260-280° C. The rotational speed of the twin screws was 80 rpm. The residence time of the polymers after charging of the extruder was 3 min. To produce moldings, the polymer melt was transferred by means of a heated melt vessel into the injection-molding machine Xplore Micro-Injection Molding Machine 10 cc and immediately injected into the mold. A tool temperature of 60° C. was employed. Injection molding was carried out in three stages of 16 bar for 5 s, 16 bar for 5 s and 16 bar for 4 s. Shoulder bars in accordance with ISO527-2/1BA/2 were produced in three stages of 14 bar for 5 s, 14 bar for 5 s and 14 bar for 4 s.

(5) As an alternative, the individual components were for this purpose mixed in a twin-screw extruder (ZSK 18 or ZSK 25) at a throughput of 20 kg/h and about 260° C. (PBT, PA6) or 280° C. (PA66) with a flat temperature profile, discharged as extrudate, cooled until pelletizable and pelletized. The test specimens for the studies indicated in the tables were injection-molded on an Arburg 420 injection-molding machine at a melt temperature of about 260-280° C. and a tool temperature of about 80° C.

(6) The constitutions of the molding compositions and the results of the measurements are shown in the tables.

(7) Testing:

(8) The mechanical properties were determined in accordance with ISO 527-2/1A/5 and the Charpy impact toughness (unnotched) was determined in accordance with ISO 179-2/1eU.

(9) The flame resistance of the molding compositions was determined firstly by the method UL94-V (Underwriters Laboratories Inc. Standard of Safety, “Test for Flammability of Plastic Materials for Parts in Devices and Appliances”, p. 14 to p. 18 Northbrook 1998). In the case of the formulations produced using the DSM Xplore 15 microcompounder, an abbreviated method was employed. Two test bars were in each case tested according to the procedure prescribed for the UL94V test. The sum of the burning times is reported as average of the times for the two test specimens. The corresponding examples are marked.

(10) The determination of the flue gas density, heat liberation and residue after combustion was carried out in accordance with ISO 5660-1: 2002. All plates had a thickness of 4 mm. Testing was carried out using a heating radiator power of 50 kW m.sup.−2.

(11) Trial a

(12) Production of Mica Having a Zinc Oxide Coating

(13) 69 g of an aqueous paste comprising 50 g of mica (G1, G2 or G3) were dissolved in 930 ml of water. 40 g of potassium carbonate were added to this suspension. The suspension was heated to 60° C. L1 was then introduced over a period of 8 hours in such an amount that the mass ratios indicated in the table below were established. Here, the pH was kept constant at pH=10 by means of potassium carbonate solution. After the addition was complete, the suspension was cooled and the solid was separated from the mother liquor by filtration. The solid was washed with deionized water until the conductivity had dropped below 200 μS. The filter cake was firstly dried at 110° C. in a convection oven and calcined in a porcelain dish at temperatures in the range from 800° C. to 1000° C. in a muffle furnace for 1 hour.

(14) As an alternative, the material can be produced as follows:

(15) 110 g of an aqueous paste comprising 80 g of mica (G1, G2 or G3) were dissolved in 930 ml of water. 50 g of potassium carbonate were added to this suspension. The suspension was heated to 60° C. L2 was then added over a period of 8 hours in such an amount that the mass ratios indicated in the table below were established. Here, the pH was kept constant at a pH in the range from 9.5 to 10.5 by means of potassium carbonate solution. After the addition was complete, the suspension was cooled and the solid was separated from the mother liquor by filtration. The solid was washed with deionized water until the conductivity had dropped below 200 μS. The filter cake was firstly dried at 110° C. in a convection oven and calcined in a porcelain dish at temperatures in the range from 800° C. to 1000° C. in a muffle furnace for 1 hour. L1: 150 g of Zn(NO3)2*6H2O were dissolved in 700 ml and the solution was made up to 1000 ml with water. L2: 240 g of Zn(NO3)2*6H2O were dissolved in 700 ml and the solution was made up to 1000 ml with water.

(16) Mica: G1: Natural mica having a particle size d50 determined by light scattering (Malvern 3000) d50=31.9 μm. G2: Natural mica having a particle size d50 determined by light scattering (Malvern 3000) d50=17.1 μm. G3: Natural mica having a particle size d50 determined by light scattering (Malvern 3000) d50=9.89 um.

(17) TABLE-US-00007 Calcination Mass ratio of ZnO in % temperature Product ZnO/mica (g/g) by weight Mica (° C.) Mica ZnO 1 33 g ZnO/100 g mica 25 G1 800 Mica ZnO 2 52 g ZnO/80 g mica 40 G1 1000 Mica ZnO 3 52 g ZnO/80 g mica 40 G2 1000 Mica ZnO 4 52 g ZnO/80 g mica 40 G3 1000 Mica ZnO 5 33 g ZnO/100 g mica 25 G3 800 MICA ZnO 6 33 g ZnO/100 g mica 25 G3 800 MICA ZnO 7 50 g ZnO/100 g Mica 33 G3 1000

(18) Heat Treatment:

(19) Metal oxide layers produced by wet precipitation typically have numerous hydroxyl groups and/or carbonate groups. To improve the stability, the condensation in the production process was preferably carried out to complete conversion, so that water was no longer released during later processing of the materials, for instance during extrusion of polymers at high temperatures. Completion of the conversion in the condensation of the oxide layers was generally brought about by drying in hot air.

(20) Production of Mica Having a Vanadium Oxide Coating

(21) 75 g of mica were introduced into 450 ml of water, and 400 ml of 5% nitric acid were added. 27.28 g of vanadium(IV) sulfate hydrate were added to this suspension and a temperature of 80° C. was set. Neutralization was carried out by addition of 5% NaOH at a rate of 100 ml/h. After the addition was complete, the suspension was cooled and the solid was separated from the mother liquor by filtration. The solid was washed with at least 500 ml of deionized water and subsequently washed with ethanol. The filter cake was firstly dried at 110° C. in a convection oven and calcined in a porcelain dish at temperatures in the range from 500° C. to 800° C. in a muffle furnace for 1 hour.

Example 1

(22) TABLE-US-00008 TABLE 1 Extrusion by means of ZSK18. Sample Comp1 2 3 4 Comp5 Comp6 Comp7 Ultramid 65 60.15 64.15 60.15 64.15 60.15 61 A24 DS1110 25 25 25 25 25 25 25 (PA GF) DEPAL C0 10 10 10 10 10 10 10 Melapur 0 4 0 4 0 4 4 M200 C3 Mica ZnO 1 0 0.85 0 0 0 0 0 Mica ZnO 2 0 0 0.85 0.85 0 0 0 Zinc oxide 0 0 0 0 0.85 0.85 0 B1

(23) The use of small amounts of zinc oxide/mica significantly improves the flame resistance. No improvement can be achieved by means of standard ZnO.

(24) TABLE-US-00009 TABLE 2 Testing in accordance with UL94 to 0.8 mm. Sample Comp1 2 3 4 Comp5 Comp6 Comp7 Classi- V-2 V-0 V-1 V-0 V-2 V-2 V-2 fication Total 135 38 115 42 121 83 56 burning time [s] Absorbent yes no no no yes yes yes cotton at the bottom ignites

(25) Samples Comp1 and Comp5-Comp7 display significant dripping and ignition of the absorbent cotton at the bottom. Samples 2, 3 and 4 comprising the specially prepared zinc oxide/mica show significantly less dripping due to carbonization and in each case V1 or even V0 behavior. The trial clearly shows that the form in which the zinc oxide is added is important.

Example 2

(26) TABLE-US-00010 TABLE 3 Extrusion by means of ZSK25. Sample Comp1 2 Ultramid A27 60.4 60.2 OCF DS1110-10N (PA GF) 26 26 Red phosphorus masterbatch C1 12 12 Zinc oxide B3 0.7 0 Calcium stearate (Ceasit AV) 0.55 0.55 Irganox 1098 0.35 0.35 Mica ZnO 3 0.9

(27) Zinc oxide/mica displays better flame resistance than the previous formulation. The actual amount of zinc oxide is lower in the case of the coated mica flakes than in the comparative example.

(28) TABLE-US-00011 TABLE 4 Testing in accordance with UL94 to 0.8 mm. Sample Comp1 2 Classification V-1 V-0 Total burning time [s] 51 35 Absorbent cotton at the bottom ignites no no Burning of the holder no no

(29) TABLE-US-00012 TABLE 5 Testing in accordance with ISO 5660-1. A heating radiator power of 50 kW m.sup.−2 was used. Sample Comp1 2 Ignition time [s] 42 ± 1 44 ± 1 Total quantity of heat liberated 133 ± 6  115 ± 2  [MJ m.sup.−2] MARHE [kW m.sup.−2] 104 ± 3  96 ± 3 Flue gas density [m.sup.2] 27 ± 3 26 ± 2 Mass of residue [%] 37 ± 1 40 ± 1

Example 3

(30) TABLE-US-00013 TABLE 5 Extrusion by means of ZSK18. Sample Comp1 3 Comp4 Ultramid A24 65.0 64.0 64.0 DS1110 (PA GF) 25.0 25.0 25.0 Red phosphorus masterbatch C1 10.0 10.0 10.0 MICA ZnO 4 0.0 1.0 0.0 Zinc oxide B1 0.0 0.0 1.0

(31) Here, a reduced amount of red phosphorus was used. The control sample having this amount of phosphorus did not achieve any classification. Use of mica/ZnO enables a V-1 classification to be achieved.

(32) TABLE-US-00014 TABLE 6 Testing in accordance with UL94 to 1.6 mm. Sample Comp1 3 Comp4 Classification V- V-1 V-2 Total burning time [s] 75 39 161 Absorbent cotton at the bottom ignites yes no yes Burning of the holder yes no no

Example 4

(33) TABLE-US-00015 TABLE 7 Extrusion by means of ZSK18. Sample Comp1 2 3 4 5 Comp6 Ultramid B27 57.0 56.0 56.0 56.0 56.0 56.0 DS1110 (PA GF) 25.0 25.0 25.0 25.0 25.0 25.0 DEPAL C0 12.0 12.0 12.0 12.0 12.0 12.0 Melapur M200 C3 6.0 6.0 6.0 6.0 6.0 6.0 MICA ZnO 5 0.0 1.0 0.0 0.0 0.0 0.0 MICA ZnO 4 0.0 0.0 1.0 0.0 0.0 0.0 MICA ZnO 6 0.0 0.0 0.0 1.0 0.0 0.0 MICA ZnO 7 0.0 0.0 0.0 0.0 1.0 0.0 Zinc oxide B1 0.0 0.0 0.0 0.0 0.0 1.0

(34) The use of small amounts of zinc oxide/mica significantly improves the flame resistance of PA6. Only a small improvement can be achieved by means of standard ZnO. Various types of mica-ZnO fulfill the purpose.

(35) TABLE-US-00016 TABLE 8 Testing in accordance with UL94 to 0.8 mm. Sample Comp1 2 3 4 5 Comp6 Classification V-2 V-0 V-0 V-0 V-0 V-1 Total burning time [s] 35 28 39 34 31 54 Absorbent cotton at the yes no no no no no bottom ignites

Example 5

(36) TABLE-US-00017 TABLE 9 Extrusion by means of DSM miniextruder Sample Comp1 2 3 Comp4 5 6 Comp7 Comp8 Comp9 Ultradur 64.5 64.5 62.5 63.0 62.0 61.0 61.0 63.5 62.5 B4500 Glass fibers 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 DEPAL C0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 MPP 2.5 2.5 2.5 4.0 4.0 4.0 4.0 2.5 2.5 Mica + V2O5, 0.0 0.0 0.0 0.0 1.0 2.0 0.0 0.0 0.0 500° C. Mica + V2O5, 0.0 1.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 800° C. Mica 0.0 0.0 0.0 0.0 0.0 0.0 2.0 1.0 2.0 untreated

(37) The use of small amounts of vanadium oxide/mica significantly improves the flame resistance of PBT comprising a phosphorous-comprising flame retardant.

(38) TABLE-US-00018 TABLE 10 Testing according to the method of UL94 to 1.6 mm. Only 2 burning bars were tested in each case. Sample Comp1 2 3 Comp4 5 6 Comp7 Comp8 Comp9 Classification V2 V1 V1 V2 V1 V0 V- V- V2 Total burning 21 29 26 31 22 6 66 >30 25 time t1 + t2 [s] Absorbent yes no no yes no no no yes yes cotton at the bottom ignites

Example 6

(39) TABLE-US-00019 TABLE 11 Extrusion by means of DSM miniextruder Sample 1 2 Comp3 Comp4 Comp5 Ultradur B4500 52.10 51.10 53.10 52.10 51.10 Glass fibers PPG3786 25.00 25.00 25.00 25.00 25.00 (PBT standard) Poly(2,6-dimethyl-1,4- 5.00 5.00 5.00 5.00 5.00 phenylene oxide) Brominated acrylate 16.90 16.90 16.90 16.90 16.90 FR1025 Vanadium oxide-MICA 1.00 2.00 0.00 0.00 0.00 (800° C.) GM0948-0136 Mica untreated 0.00 0.00 0.00 1.00 2.00

(40) The use of small amounts of vanadium oxide/mica significantly improves the flame resistance of PBT comprising a halogenated flame retardant.

(41) TABLE-US-00020 TABLE 12 Testing according to the method of UL94 to 1.6 mm. Only 2 burning bars were tested in each case. Sample 1 2 Comp3 Comp4 Comp5 Classification V0 V0 V2 V1 V1 Total burning time 9 5 21 12 17 t1 + t2 [s] Absorbent cotton at the bottom no no yes no no ignites