Wavin B.v.

Jan U Stoffelsma

Ali Guettouche

Helmut Schroeder

Volker Koestring

A pipe of layers of thermoplastic polyolefins of the same type, however with different properties, which are connected inseparably with one another, an outer first layer and a second layer, adjoining the first layer on the inside, consisting of a material, which has not been cross-linked, the second layer approximately having the FNCT the value or the NPT value of a one-layer standard pressure pipe and the first layer having an FNCT or NPT value, which is higher by a factor of at least 3 than that of the second value. Moreover, a third layer is provided, which adjoins the second layer on the inside, also consists of material that is not cross-linked and has a PNCT, which is higher by a factor of at least 3 than that of the second layer and an NPT layer, which is higher by a factor of at least 2 than that of the second layer.

Multi-layered pipe

Coloring composition for colouring polyvinylchloride comprising at least 40% by weight of coloring pigment and at most 60% by weight of glycerolmonostearate. The composition may be added directly to extruder for extruding polyvinylchloride, the amount of glycerolmonostearate in the moulded article as obtained being restricted to at most 5%.

Method for coloring polyvinylchloride

Coloring composition for coloring thermoplastic polymers obtained by solidifying a liquid mixture of coloring pigments and an ester of phtalic acid and an alcohol. The composition contains at least 40% of pigments and at most 60% of an ester of phtalic acid and an alcohol comprising 12 to 16 carbon atoms.

Growing community of inventors

Hardenberg, Netherlands

Jan U Stoffelsma