Patent EP-0972802-A1 (EP)
Inventor: RAETZSCH MANFRED PROF DR
IPC: C08L23/10
Filed: 1999-06-22
Abstract: Hetero-phase polyolefin alloys with a semi-interpenetrating network structure, obtained by melt-compounding propylene (co)polymer (A) with a co-continuous blend (B) made by reacting a mixture of propylene (co)polymer and elastomeric polyolefin or styrene-ethylene-butadiene terpolymer with an unsaturated, hydrolyzable organosilane Hetero-phase polyolefin alloys with a semi-interpenetrating network structure and an outstanding combination of high rigidity, low-temperature toughness and optionally a low thermal expansion coefficient, comprising 65-99.6 wt% propylene polymers and 35-0.4 wt% elastomeric polyolefins (EPO) or styrene-ethylene-butadiene (SEBS) terpolymers, optionally with 0.01-2.5 wt% stabilizers, 0.01-1 wt% processing aids, 0.1-1 wt% antistatic additives, 0.2-3 wt% pigments, 0.05-1 wt% nucleating agents and/or 2-20 wt% fire retardants and/or optionally 10-70 (preferably 20-50) wt% inorganic and/or organic fillers and/or reinforcing substances (all based on total wt. of polymers). These alloys show a gel content (GHP; wt%) given by GHP = 10-2 CB (GB + N(100 - GB)), in which CB = the concentration of the co-continuous blend (B) in the alloy (wt%), GB = the gel content of (B) (wt%) and N = the post-crosslinking factor = 0.10-0.90. The alloys are obtained by melt-compounding 60-98 wt% conventional propylene homo- or co-polymer (A) (MFI 230/2.16 = 0.1-50 g/10 min) with 40-32 wt% co-continuous blend (B), optionally in presence of 0.01-0.5 wt% silanol condensation catalyst (Si-CAT) and/or 0.01-0.5 wt% water. Blend (B) is based on conventional propylene (co)polymers with MFI in the above range, mixed with 20-90 wt% elastomeric polymer(s) comprising (B2) copolymers of 50-95 wt% ethylene (E) with 50-5 wt% propylene (P) and/or 4-18C  alpha -olefins and/or unsaturated esters such as vinyl acetate and/or 1-8C alkyl (meth)acrylates, with MFI 190/2.16 = 0.2-30 g/10 min; (B3) essentially amorphous polypropylene or propylene copolymers (PP) with less than 10 wt% crystalline (co)polymer, an enthalpy of fusion of less than 40 J/g and an MFI 230/2.16 of 0.1-40 g/10 min, derived from at least 80 mol% propylene and not more than 20 mol%  alpha -olefin(s) of formula CH2=CHR, in which R=2-8C linear or branched alkyl; (B4) non-isotactic homo-PP with a m.pt. of 145-165 degrees C, a melt viscosity of more than 200,000 g/m.s at 190 degrees C, a heat of crystallization of 4-10 cal/g and an ether-soluble content of 35-55 wt%; and/or (B5) linear SEBS 3-block copolymers containing 5-45 wt% ethylene and 15-45 wt% styrene, with an MFI 190/2.16 of 0.2-30 g/10 min. Blend (B) contains 0.1-2.0 wt% chemically-bound, unsaturated, hydrolyzable organosilane compounds (HOSi) and has a gel content of 5-60 (preferably 25-50) wt%; this blend is obtained by (1) reacting, in the melt, mixtures of 10-80 wt% conventional PP and 90-20 wt% EPO or SEBS with 0.1-5.0 wt% HOSi in presence of 0.01-1.0 wt% thermally decomposable radical formers (RADF), 0.01-1.0 wt% Si-CAT and optionally 0.01-1.0 wt% water (all based on the amount of EPO or SEBS), or (2) reacting, in the melt, mixtures of 6-66 wt% conventional PP and 94-33 wt% EPO or SEBS with 0.1-5.0 wt% HOSi in presence of 0.01-1.0 wt% RADF, with the addition of a further 5-40 wt% conventional PP, 0.01-1.0 wt% Si-CAT and optionally 0.01-1.0 wt% water, or (3) reacting EPO or SEBS with 0.1-5.0 wt% HOSi in the melt in presence of 0.01-1.0 wt% RADF, granulating and then melt-compounding a mixture of 90-20 wt% of this product and 10-80 wt% conventional PP in presence of 0.01-1.0 wt% HOSi and optionally 0.01-1.0 wt% water (based on EPO or SEBS). In these alloys, the conventional PP components (A) and (B1) may be the same or different. An Independent claim is also included for a process for the production of these polyolefin alloys, in which (a) blend (B) is obtained by reactions as above (1, 2 or 3) carried out in a continuous kneader at 120-270 (preferably 200-240) degrees C and 1-300 (preferably 1-30) bar with a residence time of 0.5-40 (preferably 1-15) minutes, using radical initiators (RADF) with a half-life of 1 minute to 48 hours at 130 degrees C, (b) the further melt-compounding in version (3) is carried out in a continuous kneader at 120-270 (preferably 200-240) degrees C and (c) the other additives and fillers etc. (see above) may be added during the production of (B) or during the subsequent production of the hetero-phase alloy.