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Reduction of weight of polypropylene polymers

IP.com Disclosure Number: IPCOM000012141D
Publication Date: 2003-Apr-11
Document File: 2 page(s) / 27K

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The IP.com Prior Art Database

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Reduction of weight of polypropylene polymers

WO-01/90113 A1 discloses a process for reducing the molecular weight of polypropylene, propylene copolymers or polypropylene blends in the presence of a hydroxylamine ester of the formula

� where

Ra is a monoacyl or diacyl radical; Rb and Rc are organic radicals; R1 ‑ R4 are each C1‑C6alkyl; and R5 and R6 are each, independently of one another, hydrogen, C1‑C6alkyl or C6‑C10aryl; or R5 and R6 are together oxygen. It has now been found that hydroxylamine esters of the formula above, particularly the hydroxylamine ester of the formula

are useful for reducing the molecular weight of polypropylene polymers. In the so-called vis-breaking process a mixture of the polymer and the hydroxylamine ester is heated during a fiber spinning process for preparing non-woven-fabrics, such as SB (spun-bonded) fibres, MB (melt-blown) fibres, SS, SMS, SSS, SMMS as well as combinations thereof. The controlled rheology PP (CR-PP) formed during such processing shows a narrow molecular weight distribution (NMWD) and a reduced level of volatile decomposition products (smoke). The resulting non-woven fabrics show superior properties such as improved mechanical values or enhanced barrier (wet barrier, air permeability) behaviour. In contrast to commonly used peroxides in the degradation process the hydroxylamine esters show superior degradation performance at temperatures above 230°C while avoiding peroxide related drawbacks (safety problems, uncon...