Abstract:
The present invention relates to a multimodal polyethylene composition which can be manufactured into pipes showing improved pressure resistance comprising a high density multimodal ethylene polymer component (A) having a density of at least 930 kg/m3, and a MFR21 of not more than 15 g/10 min, wherein said composition exhibits a LAOS-NLF defined as L A O S - N L F = G 1 ′ G 3 ′ where G1′—first order Fourier Coefficient G3′—third order Fourier Coefficient of at least 1.7. Such a polyethylene composition is useful for the manufacture of pressure pipes that exhibit improved pressure resistance and creep resistance and do not undergo sagging. Further disclosed is a process for the production of a pipe using such a multimodal polyethylene composition and a pipe comprising such a multimodal polyethylene composition.
Abstract:
The present invention refers to a method for improving the storage stability and/or transport stability of polymer (A) comprising the following steps: a) providing polymer (A) selected from the group consisting of copolymers of ethylene and a C4C12 alpha olefin comonomer, copolymers of propylene and mixtures thereof containing additionally comonomer units comprising hydrolysable silane groups; b) providing a stabilizer (B) selected from the group consisting of sterically hindered phenols, alkyltri-alkoxysilanes, alkenyltrialkoxysilanes and mixtures thereof; c) mixing polymer (A) and stabilizer (B) to obtain a stabilized polymer composition (I); and d) transferring the stabilized polymer composition (I) obtained in step c) in a container comprising at least one barrier layer. In addition, the present invention relates to the use of stabilizer (B) for improving the storage stability and/or transport stability of polymer (A) stored and/or transported in a container having a barrier layer.
Abstract:
The present invention relates to a polyolefin composition with increased resistance to degradation caused by ClO2-containing water and to a pipe made of such a polyolefin composition. The present invention further relates to the use of the polyolefin composition for the production of a pipe and to the use of a combination of particular types of antioxidants for increasing the resistance of the polyolefin composition against degradation caused by contact with ClO2-containing water.
Abstract:
The present invention discloses a process for providing a cross-linked composition, the process comprising the steps of (a) providing an ethylene-α-olefin plastomer having—a density of from 850 kg/m3 to 900 kg/m3; and—an melt flow rate (ISO 1133, 2.16 kg, 190° C.) of 0.3 to 50 g/10 min; (b) grafting the ethylene-α-olefin plastomer with silane crosslinker such that the content of silane crosslinker is in the range of 0.1 to 10.0 wt.-% with respect to the grafted ethylene-α-olefin plastomer; (c) contacting said grafted ethylene-α-olefin plastomer with 2 to 8 wt.-% of a tin-free silane crosslinking catalyst with respect to the resulting mixture of grafted ethylene-α-olefin plastomer and tin-freesilane crosslinking catalyst, wherein said tin-free catalyst comprises a Brönsted acid at 23° C. and 50% relative humidity for at least 15 minutes thus forming a cross-linked composition, wherein gel content of said cross-linked composition after 15 min is at least 60%.
Abstract:
The present invention relates to silane crosslinking catalyst comprising: —75 to 85 wt.-% of an olefin acrylate interpolymer and—15 to 25 wt.-% of a hindered amine light stabilizer (HALS) having a number average molecular weight Mn of 1500 to 4000 g/mol; and—optionally up to 5 wt.-% wax, wherein the silane crosslinking catalyst is free of tin, carboxylic acid(s) and sulphonic acid(s), all weight percentages with respect to the total weight of the silane crosslinking catalyst.