Flame retardant polypropylene composition

Abstract

The present invention relates to a flame retardant polypropylene composition for a conduit, appliance, and/or automotive wire, comprising a flame retardant composition comprising: a) a base resin comprising a heterophasic propylene copolymer which comprises a polypropylene homo- or copolymer matrix and an ethylene propylene rubber dispersed in said matrix, and b) a metal hydroxide or hydrated compound, wherein the heterophasic propylene copolymer has a MFR.sub.2 below 0.8 g/10 min and a xylene cold soluble (XCS) fraction content between 1 and 15 wt % based on the total weight of the heterophasic propylene copolymer.

Claims

1. A flame retardant composition comprising: a) a base resin consisting of a heterophasic propylene copolymer which comprises a polypropylene homo- or copolymer matrix and an ethylene propylene rubber dispersed in said matrix, and b) a metal hydroxide, wherein the heterophasic propylene copolymer has a MFR.sub.2 below 0.8 g/10 min and a xylene cold soluble (XCS) fraction content between 1 and 15 wt % based on the total weight of the heterophasic propylene copolymer.

2. The composition of claim 1 wherein the heterophasic propylene copolymer has a total amount of ethylene between 1 and 8.5 wt % based on the total weight of the heterophasic propylene copolymer.

3. The composition of claim 1 wherein the MFR.sub.2 of the heterophasic propylene copolymer is below 0.5 g/10 min.

4. The composition according to claim 1 wherein the base resin a) and the metal hydroxide b) make up to 80 wt % of the total composition.

5. The composition according to claim 1 wherein the base resin a) is present in the composition in an amount between 30 and 52 wt % and the metal hydroxide b) in an amount from 47 to 62 wt % based on the total weight of the composition.

6. The composition according to claim 1 wherein the composition comprises 40 to 45 wt % of the heterophasic propylene copolymer and 55 to 60 wt % of the metal hydroxide based on the total weight of the composition.

7. A flame retardant composition comprising: a) a base resin comprising a heterophasic propylene copolymer which comprises a polypropylene homo- or copolymer matrix and an ethylene propylene rubber dispersed in said matrix, and b) a metal hydroxide, wherein the heterophasic propylene copolymer has a MFR.sub.2 below 0.8 g/10 min and a xylene cold soluble (XCS) fraction content between 1 and 15 wt % based on the total weight of the heterophasic propylene copolymer; wherein the base resin further comprises an ethylene copolymer having a density between 0.860 to 0.910 g/cm.sup.3.

8. The composition according to claim 7 wherein the ethylene copolymer is present in the composition in an amount between 2 to 30 wt % based on the total weight of the composition.

9. The composition according to claim 1 wherein the metal hydroxide b) comprises magnesium hydroxide.

10. A flame retardant composition comprising: a) a base resin comprising a heterophasic propylene copolymer which comprises a polypropylene homo- or copolymer matrix and an ethylene propylene rubber dispersed in said matrix, and b) a metal hydroxide, wherein the heterophasic propylene copolymer has a MFR.sub.2 below 0.8 q/10 min and a xylene cold soluble (XCS) fraction content between 1 and 15 wt % based on the total weight of the heterophasic propylene copolymer; wherein the base resin further comprises an ethylene butylacrylate (EBA) having a density between 0.860 to 0.910 g/cm.sup.3.

11. The composition according to claim 5 wherein the metal hydroxide b) comprises magnesium hydroxide.

12. The composition according to claim 7 wherein the metal hydroxide b) comprises magnesium hydroxide.

Description

2. EXAMPLES

(1) In the preparation of the inventive compositions (Ex1-Ex3) heterophasic propylene copolymers BA202E, BA212E, available from Borealis AG and PP-EPR1 are used. PP-EPR1 is prepared as follows:

(2) Catalyst Preparation

(3) First, 0.1 mol of MgCl.sub.2?3 EtOH is suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution is cooled to the temperature of ?15? C. and 300 ml of cold TiCl.sub.4 is added while maintaining the temperature at said level. Then, the temperature of the slurry is increased slowly to 20? C. At this temperature, 0.02 mol of diethylhexylphthalate (DOP) is added to the slurry. After the addition of the phthalate, the temperature is raised to 135? C. during 90 minutes and the slurry is allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 is added and the temperature is kept at 135? C. for 120 minutes. After this, the catalyst is filtered from the liquid and washed six times with 300 ml heptane at 80? C. Then, the solid catalyst component is filtered and dried. Catalyst and its preparation concept is described in general e.g. in patent publications EP 491 566, EP 591 224 and EP 586 390.

(4) Then triethylaluminium (TEAL), dicyclopentyldimethoxysilane (DCPDMS) as donor (Do), catalyst as produced above and vinylcyclohexane (VCH) is added into oil, like mineral oil, e.g. Technol 68 (kinematic viscosity at 40? C. 62-74 cSt), in amounts so that Al/Ti is 3-4 mol/mol, Al/Do is as well 3-4 mol/mol, and weight ratio of VCH/solid catalyst is 1:1.

(5) The mixture is heated to 60-65? C. and allowed to react until the content of the unreacted vinylcyclohexane in the reaction mixture is less than 1000 ppm. Catalyst concentration in the final oil-catalyst slurry is 10-20 wt %.

(6) Polymerization

(7) In PP-EPR1 the matrix is made of a propylene homopolymer which is prepared in a loop reactor and a gas phase reactor (GPR1). The obtained polymer is stabilized with conventional stabilizer and antioxidant. Further information about the propylene homopolymer constituting the matrix is shown in the table below.

(8) Subsequently, the propylene homopolymer is transferred to a second gas phase reactor (GPR2) where the elastomeric polypropylene is prepared. The obtained polymer is stabilized in a conventional twin screw extruder with conventional stabilizers, i.e. calcium stearate and phenolic antioxidant, in conventional amounts, and pelletized for further testing as given in Table 1.

(9) For the preparation of comparative compositions (CE1-CE4) polypropylenes HA507MO (propylene homopolymer), RA130E (random propylene copolymer) and heterophasic propylene copolymers BA125MO and BA204E, available from Borealis AG, are used.

(10) TABLE-US-00001 TABLE 1 HPC1 Process parameters Catalyst feed (g/h) 5.0 Ti content % 1.9 Donor feed (g/t propylene) 80 Al/Ti ratio (mol/mol) 127 Al/donor ratio (mol/mol) 5.0 Prepolymerisation Temperature (? C.) 40 Hydrogen feed (g/h) 0.5 Loop reactor Temperature (? C.) 85 Pressure (kPa) 5462 H2/C3 ratio (mol/kmol) 0.07 MFR10 (g/10 min) 1.1 Gas phase reactor 1 Temperature (? C.) 95 Pressure (kPa) 2301 H2/C3 ratio (mol/kmol) 214 MFR2 (g/10 min) 0.33 Gas phase reactor 2 Temperature (? C.) 50 Pressure (kPa) 2000 C2/C3 ratio (mol/kmol) 700 H2/C2 ratio (mol/kmol) 14

(11) The properties of all the polymers are listed in Table 2.

(12) TABLE-US-00002 TABLE 2 BA BA PP- BA BA HA507 RA 202E 212E EPR1 125MO 204E MO 130E MFR.sub.2 (g/10 min) 0.3 0.3 0.3 1.3 0.8 0.8 0.25 Density (Kg/m.sup.3) 900 900 900 905 900 908 905 XCS (wt %) 13 10 4.5 16 13 2.5 7 Total Ethylene 8.5 4.4 1.4 10 8.5 0 3.6 (wt %) Ethylene in EPR 65 45 30 60 65 (wt %) Flexural Modulus 1300 1700 2000 1200 1100 1500 800 (Mpa) Charpy notched 50/5 50/5 29/2 50/7 35/4 6/ 20/2 23? C./?23? C. (kJ/m.sup.2)

(13) The polymer compositions of all the examples are produced by compounding together the polymers listed in Table 2 with Magnifin H5HV (Mg(OH).sub.2) from Martinswerke, Germany and with Irganox 1010, Irganox 1024 and Irganox PS 802 (antioxidants).

(14) The amount in wt % of each component for both inventive and comparative examples is given in Table 3.

(15) A Buss Co-kneader type PR46B-11D/H1 is used for the compounding.

(16) TABLE-US-00003 TABLE 3 Ex 1 Ex 2 Ex 3 CE1 CE2 CE3 CE4 BA202E 41.4 BA212E 41.4 PP-EPR1 41.4 BA125MO 38.9 BA204E 41.4 HA507MO 41.4 RA130E 41.4 Magnifin H5HV 57.5 57.5 57.5 60 57.5 57.5 57.5 Irganox 1010 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Irganox 1024 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Irganox PS802 0.5 0.5 0.5 0.5 0.5 0.5 0.5

(17) Automotive wires of 0.35 mm.sup.2 (7?0.254 mm diameter single wires) are produced from the compositions on a Nokia-Maillefer extruder, 45 mm/28D, with a temperature profile of: 165-185-200-215-220 (Bride)-230(Flansch)-235 (Bypass)-250 (Head)-250? C. (Pressure die).

(18) The outer diameter of the cable is 1.28 mm and the wall thickness 0.24 mm.

(19) The melt temperature is of 220? C. and a line speed of 100 m/min. The conductor is preheated to a setting temperature of 90? C. The compound is pre-dried for 18 hours at 80? C. prior extrusion.

(20) The properties of the 0.35 mm.sup.2 cables are listed in Table 4. The tests are made according to LV112 and ISO6722 (Jan. 17, 2014).

(21) TABLE-US-00004 TABLE 4 Ex 1 Ex 2 Ex 3 CE1 CE2 CE3 CE4 Flame Pass Pass Pass Pass Fail Pass Fail retardancy Cold flexibility Pass Pass Pass Pass Pass Fail Pass 40? C. Needle abrasion Pass Pass Pass Fail Fail Pass Fail min. 200 cycles Minimum N? 200 530 985 16 135 260 49 of cycles Avarage N? 270 600 1300 19 250 530 55 of cycles Thermal Pass Pass Pass Fail Pass Pass Fail overload in wound state

(22) From Table 4 it can clearly be seen that for thin wires the required cycles of 200 strokes in the needle abrasion test is only met by the inventive compositions and the comparative composition 3, which, however, shows inferior low temperature properties. The other properties are at best for inventive examples 2 and 3.

(23) It is thereby shown that only specific types of heterophasic copolymers are suitable for automotive, conduit and appliance wires.