Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-03-20
1999-03-09
Hoke, Veronica P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524451, C08K 334
Patent
active
058801863
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to stabilised filled polyolefins and to a method of stabilising said polyolefins and to the use of a stabiliser therefor.
Mineral fillers are frequently often added to polyolefins. Such filled polyolefins often have a poorer stability (especially stability to heat and light) than analogous polyolefins that do not contain fillers. Performance can to some extent be improved by increasing the concentration of conventional stabilisers. The addition of epoxies is also recommended (inter alia in "Stabilization of Filled Polypropylene", ANTEC'85, page 977 et seq.) to reduce the adverse action of the fillers on the thermal stability. But such addition is usually associated with reduced light stability. Hence there is still a need to enhance the stabilisation of filled polyolefins.
It is therefore the object of this invention to provide a stabilised filled polyolefin which has improved long-term stability and improved stability to weathering.
It has now been found that, in the presence of macrocyclic compounds containing specific piperidine or piperazine groups, it is possible to stabilise filled polyolefins in simple and economic manner against thermal, oxidative and actinic degradation during processing and subsequent use.
Accordingly, the invention relates to stabilised filled polyolefins comprising a filler and 0.01 to 5% by weight, based on the polymer, of at least one macrocyclic compound which contains a radical of formula ##STR2## in the macrocyclic structure or in a side-group, said macrocyclic structure consisting of at least 8 atoms, and wherein the substituents R independently of one another are methyl, ethyl or propyl, preferably methyl, or two substituents R at the same carbon atom are also together a pentamethylene radical and a is 0, 1 or 2, preferably 0.
Those macrocyclic compounds are preferred in which the macrocyclic structure contains at least 9 atoms, and those compounds are most preferred in which the macrocyclic structure contains at least 9 and at most 50 atoms.
It is preferred to use 0.1 to 2% by weight, based on the polymer, of the above macrocyclic compound.
Within the scope of this invention, fillers will be understood as meaning in particular mineral fillers. Suitable mineral fillers are typically carbonates (preferably calcium carbonates such as chalk), silicates (preferably talc, kaolin, mica, wollastonite and silica), aluminium trihydrate, carbon black and titanium dioxide. Among the preferred fillers comprising chalk, talc, kaolin, mica, wollastonite and silica, talc is very particularly preferred. A single filler as well as a blend of two or more fillers may also be used. Such a blend of fillers will typically comprise talc and carbon black or talc and titanium dioxide.
Filled polyolefines will usually contain 5-75% by weight, preferably 10-40% by weight, of filler, in each case based on the weight of the polyolefin.
By polyolefins are meant homopolymers of an .alpha.-olefin, random, alternating or block-copolymers of two or more than two (.alpha.-olefins or copolymers of an .alpha.-olefin with one or more than one unsaturated copolymerisable compound such as polyethylene (PE), low density polyethylene (LDPE), low density linear polyethylene (LDLPE) and high-density polyethylene (HDPE), and also copolymers such as ethylene-propylene (EPM) and ethylene-propylene-diene copolymers (EPDM) as well as ULDPE and MDPE; furthermore polypropylene (PP) and polypropylene blends and copolymers such as PP/EPDM and PP/PE. These polymers can be further modified by grafting. Preferred polyolefins are polyethylene, polypropylene and copolymers thereof, homo- and copolymers of polypropylene being very particularly preferred.
A macrocyclic compound containing piperidine or piperazine groups is preferably a macrocyclic compound selected from the compounds of the following formulae (III) to (VI), those compounds of formulae (IV) and (V) being particularly preferred: ##STR3## wherein L.sub.1 is the radical ##STR4## (Ia), and A.sub.1 is >CH-- or nitrogen or a substituted
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D. Davidson et al., Stabilization of Filled Polypropylene, ANTEC '85, pp. 977-981.
Klingert Bernd
Pauquet Jean-Roch
Todesco Roberto
Ciba Specialty Chemicals Corporation
Hall Luther A. R.
Hoke Veronica P.
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