CS269371B1 - Method for stabilizing polypropylene - Google Patents

Abstract

Polypropylene containing more than 1 part by weight of chloride ions and 30 parts by weight of titanium per 1 million parts by weight of polymer is stabilized with very effective ether-shielded amines based on 2,2,6,6-tetramethyl piperidine, if these amines are quaternized before or during stabilization with salicylic, cyclohexylcarboxylic or benzoic acid.

Description

The invention relates to the stabilization of polypropylene against light degradation by ether-shielded amines based on 2,2,6,6-tetramethylpiperidine, one nitrogen of which is ethereally hindered (HALS).

Haley are extremely effective light stabilizers for polyolefins. However, their effect is reduced if the polypropylene contains chloride and titanium ions.

If the polymer contains Ti and has an acidity higher than 1 _< 4 g Cl per 1 g of polymer, reactions 1 and 2 \ X + H (R) are significantly applied in HALS stabilized systems.

Ν - H (ev. B) + HCl Nf Cl (1) _ H (R) + Ti —-> H (R) .. Ti .. N ^ / ZH ^X (R) (2)

The Tfm ae decreases the true concentration of HALS and the ability to stabilize the polymer also decreases.

The high residual acidity and the titanium content of the polymer can cause disturbances in the washing of the remaining catalyst from the polymer, or the omission of this technological operation in the gas phase polymerization. Hitherto, the stabilization of a polymer containing a larger amount of titanium and chlorides has been addressed by increasing the amount of stabilizers added.

It has now been found that using kye (benzoate, salicylate cyclohexyl carboxylate 4 stearoyloxy-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) ester kye.eebac (TIN 770), polymeric products of hexamethylene-1,6-di (2,2,6,6-tetramethyl-4-piperidyl) amine with 2-tert-octylamino 4,6-dichloro-1,2,3-triazene (Chimasorb 944) and others in these contaminated polymers, the stabilizing efficiency is practically not reduced.

The present invention relates to a process for stabilizing polypropylene containing more than 1 part by weight of chloride ions and 30 parts by weight of titanium per 1 million by weight of polymer with sterically shielded amines based on 2,2,6,6-tetramethyl piperidine, The 6-tetramethyl piperidine is quaternized before or during stabilization with Alliclic acid or cyclohexylcarboxylic acid or benzoic acid.

The influence of organic acids on the stabilization system was studied in the research of stabilization mechanisms of polypropylene containing titanium ions and chlorides.

A number of 2,2,6,6-tetramethyl-4-steareyloxypiperidine salts were tested. The efficacy of acetate, propinate and stearate was low, high efficacy of p- and m-NOg, p-phenoxy, p-amino benzoic salts was accompanied by increased polymer coloration. The most effective were the benzene, salicylate and cyclohexyl carboxylate 2,2,6,6-tetramethyl-4-steoroylexes of piperidine. These three acids are also effective in other types of HALS. In their presence, reaction (2) cannot take place and the possible reaction (3) neutralizes the acidity of the polymer, for example

X, H (3) / -a \ +. H nC ⁺ (Ω ^ θθ + HCl NC Cl (3) ^x HXH

Salt formation can also occur during processing if an equimolar amount (ether-hindered) of benzoic acid, cyclohexylcarboxylic acid or sailylic acid is added to the HALS.

The other components of the stabilization system remain unchanged. Polypropylene may also contain other processing additives, lubricants, pigments, fillers.

The following examples illustrate the invention. % in the examples are by weight.

CS 269 3? 1 Bl

Procedure: SmSs of pelypropylene homopolymer-a-melt flow index 4 g / 10 min, containing

0.1 2.6 - diterc. butyl 4-methyl phenol, 0.15% calcium stearate, 0.2% HALS or soil HALS or 0.2% HALS and 0.1% acid were concentrated on a laboratory kneader

Brabender at 200 ° C for 10 minutes. At 240 DEG C., 0.5 mm thick films were then pressed from the material, which were exposed in a Xenotest 450.

Polymer characteristics: polypropylene homopolymers, flow index 4 g / 10 min 230 ° C, 21 N

Ti ppn HCl ppm

Polymer A 51

Polymer B 4714

Example 1

Preparation: 0.1 2,6-ditert. butyl 4-methyl phenol, 0.15% calcium etearate, 0.2 £ HALS

HALS ' Induction periods in only 450 (hours) Polymer A Polymer B 4-stearoyloxy-2,2,6-tetramethylpiperidine 4 700 2,000 4-steareyloxy-2,2,6-tetramethylpeperidinium benzoate 3 750 4,000 Example 2 Beceptura: 0.1 2.6 diterc. butyl 4-methyl phenol, HALS 0.15% calcium stearate, 0.2% HALS Induction period in Feodinj Xenetestu 450 Polymer A Polymer B sebacic acid bis (2,2,6,6-tetramethyl-4-piperidyl) ester (TIN 770) 4 800 2 850 TIN 770 + 0.1% benzoic acid '4 200 3,850 th most common Example 3 ' Becepture: as in Examples 1 and 2, 0.2 HALS HALS Induction period at 450 (hodiiO X Xenoteetu Polymer A. Polymer B 4-stearoyloxy-2,2,6,6-tetramethylpiperidine 4 700 2,000 4-stearoyloxy-2,2,6-tetramethylpiperidine cyclohexyl carboxylate 3 700 3 500

Example 4.

Formulation: as in Examples 1 to 3, + 0.2% HALS

HALS _____ ______ CS 269 371 Bl ____ Induction period in lenoteet 3 450 hours Polymer A Polymer B 4-etearoyloxy-2,2 6,6 tetramethylpiperidine 4 700 2,000 4-etearoyloxy piperidine ealicylate - 2,2 6,6 - tetramethyl- 3 500 3 400

OBJECT OF THE INVENTION

Claims (1)

OBJECT OF THE INVENTION Process for stabilizing polypropylene containing more than 1 part by weight of chloride ions and 30 parts by weight of titanium per 1 million by weight of atherica polymer with compressed amines based on 2,2,6,6-tetramethyl piperidine, characterized in that the derivatives 2, 2 6,6-Tetramethyl piperidine is quaternized before or during stabilization with alpha-oleic acid or cyclohexylcarboxylic acid or benzoic acid.