SK154089A3 - Stabilized polypropylene and propylene copolymers - Google Patents

Description

Stabilized polypropylene and propylene copolymers

The invention relates to stabilized propylene and its copolymers with ethylene for the production of thin-walled profiles, in particular films, oriented strips and fibers.

In the processing of polypropylene, the material is subjected to short-term but intense thermal exposure and mechanical stress to the melt in the processing machine. Due to atmospheric oxygen and traces of metals, which are always present in the polymers in the form of residues of the catalytic system, this occurs. thermo-oxidative degradation of the polymer matrix. If it weren't m o t 1 o o o o o o o o o o o. and the degradation may be so significant that it will prevent its further use.

The polymer can be subjected to the processing conditions twice: during the primary processing of the powder into the granulate already in the production plant and then in the actual recovery of the product from the granulate - in our case e.g. by blowing and orienting the film or by passing the melt through a die.

In most cases, the processor recycles the manufacturing waste so that part of the material is subjected to three or more treatments.

Presently, phenolic antioxidants or combinations thereof with phosphorus (phosphite and phosphonite) compounds (GB 1526603, CS 190337, EP 184 191) are currently used to protect polypropylene from these degradation effects during processing.

production of fibers and foils from propylene include. among the most demanding in terms of processing this plastic.

The present stabilizing formulations used for this purpose show some drawbacks that cause manufacturing complications. The main phenomena are:

a) occurrence of so-called gray granules, the amount of which is related to the concentration and volatility of the phenolic component. Some granules in this case are contaminated by charred residues, which cause problems with the blowing and orientation of the film, as the material often breaks up at the point of non-homogeneity,

(b) the yellow coloring of the natural granulates, which is attributed to the metal-catalysed oxidation of the phenolic component to color products during processing.

For these reasons, there is an effort to reduce the phenolic component content of the stabilizing formulation and to exploit the synergistic effect that phenolic stabilizers exhibit in combination with phosphites and phosphonites. However, when some phosphorous-containing stabilizers are used, another undesirable phenomenon may occur:

(c) t o o r b a u s d a n d o n s s r a c o t a t s o m s t r o. These sets clog the filter screen and complicate further manufacturing operations. A deposit which shows that the catalyst catalysts and calcium stearate are hydrolyzed with organic phosphite hydrolysis products.

These disadvantages are overcome by stabilized polypropylene and its copolymers containing from 0.1 to 20% by weight of ethylene containing from 0.01 to 17% by weight of phenolic stabilizers and from 0.01 to 17% by weight of a mixture of phosphite stabilizers, based on the polymer matrix and, optionally, other processing additives. wherein the mixture of phosphite stabilizers consists of 10 to 90% by weight of phosphites readily hydrolyzable and 10 to 90% by weight of phosphites readily hydrolyzable.

Non-hydrolysable phosphite in the claims is defined as phosphite which, after 60 days of storage in a Petri dish (50 mm diameter weighed 1 g in an atmosphere of 100% relative humidity at 25 ° C), does not exhibit more than 77. hydrolysis relative to the original component Easily hydrolyzable phosphites are hydrolyzed to a higher degree under these conditions, a typical non-hydrolysable phosphite is e.g. tris (2,4-di-tert-butylphenyl) phosphite, bis (2,4-di-2,4-di) is readily hydrolyzable. -tert-butyl1 phenyl) pentaerythritol diphosphite.

I

The invention is based on exploiting the specific features of the mechanism of action of two types of phosphites. It is known (DG F'obedimski et al. Dev. Polym. Stab. 2, 125 (198 (3).) That phosphite antioxidants act multifunctionally and thus primarily through the following chemical reactions: non-radical degradation of hydroperoxides, reactions with peroxy, alkoxy radicals, binding of traces of metals and oxidation products of phenolic antioxidants, especially the last two functions are of great importance in preventing the formation of undesirable coloration

I of the polymer. An extraordinary bleaching effect is observed in the easily hydrolyzable bis (2,4-di-tert-butylphenyl) pentae diphosphite spirophosphates, which during processing gradually hydrolyzes to the corresponding phosphonate and finally to the corresponding phenol, pentaerythritol and the like. phosphonic acid.

And i

p

This mixture of products stabilizes the system (Schwetl.ic'k K '1989). ··. '

Especially phosphoric acids and their very effective synergistic folym. Deg. Stab. 22, 357

They effectively bind trace metals.

The mildly acidic environment of the fire and the fire prevents the following:

I products. Effect of hydrolytic

I is. very positive.

•• smears ·. which phenol to products on

However, phosphate antioxidants that are difficult to hydrolyze (e.g.

(2,4-di-t-butylphenol) phosphite) are also stabilizers, but do not contribute to color improvement. On the second. On the other hand, there is no formation of deposits in the use, as in the case of hydrolyzable phosphites.

The specific properties of the various phosphites in combination are utilized in the invention so that the hydrolyzable phosphite is used only in the amount necessary for bleaching, then the phosphite ratio is selected according to the processing properties requirements and the degree of hydrolyzability of the easily hydrolyzable phosphites. The processing stability of the hydrolyzable phosphite.

P o .1 y rn era. A n d e n s (i n i n h a n i n e s) of both types

The abbreviations used are as follows

N - 2,6-di-t-butyl-4-methylphenol

A2 - tetrakisimethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propinate) methane

A3 - a mixture of 2,6-dimethylamino-propylene phenol with a numerical degree of oligomerization of 15 and an unreacted alkylating agent, the active substance content expressed as a concentration of bound 2,6-dimethylphenol of 6,3%

PI-tris C4 (1-phenyl) ethylphenyl 3 phosphorus

P2-bisE (2,4-di-t-butylphenyl pentaerythritol-3-diphosphite)

P3 - trisC2,4-di-t-butylphenyl 13-phosphite

P4 - bisE2-tert-butyl-4 - («, and dimethylbenzyl)

Phosphonic acid F5- (1,1-biphenyl) -4,4-cellylbis-, tetrakis (2,4-di-t-butylphenyl) ester

Table 1

H o d e t e n d e d y d o l y s t i n th e s thi th phosphite Xhydrolysis

Fri 78

P ₂ 9 8

Pa 3

P and 91

Ps 5 phosphite-defining phospholytic acid-hydrolyzable polyhydric acid-free hydrolysable polymers at least 60 days. temperature at 100% relative humidity (phosphite charge 1g)

Example 1

Polypropylene granulate prepared from a Mosten powder isotactic homopolymer with an index of 1.5 g / 10 min, with a 0.25% Al, 0.02% Α2 »0.08% CaST stabilization system on the Japan Steel granulation line, was subjected to laboratory measurements processing stability, i. five pass through the Brabender extruder. For each extrusion, it was measured elsewhere: flow at 2300 c according to CSN 64 0861.

Furthermore, the yellowness of the original granulate was measured. whose value A to D was determined by a comparative test with a control standard (where? A means the lowest degree of yellowness, D the lowest).

The occurrence of so-called gray granules, i. granules with a markedly changed color randomly in 500 g of granulation from the granulation line were counted.

The results are shown in Table 2. It is clear from their values that the stabilization system used in Example 1 is sufficient to maintain processing stability, but does not fully satisfy the requirements for yellowness or gray granules.

Example 2

The F'P granulate with the stabilization system composition 0.02% A2, 0.03% F'2 and 0.08% CaST was prepared in the field and laboratory tested as in Example 2. The results are shown in Table 2. From the measured values it follows that the stabilization system is not sufficiently suited to ensure processing stability, but that it meets the requirements for yellowness and gray granules1.

Example 3

The granulate F'F 'containing a 0.08% P2 and 0.08% CaST stabilization system was operationally prepared and tested as in Example 1. From the results shown in Table 2 it can be seen that although the degree of yellowness achieved is excellent and gray granules the stabilization system is completely unsuitable for processing stability.

Example 4

The F'P granulate of 0.1% Al, 0.8% Ρ3, and 0.08% CaST was prepared and laboratory tested in the same manner as in the example.

1. From the results shown in Table 2, it is evident that despite the minimum occurrence of Gray Granules, the degree of yellowness is insufficient and the processing stability at the limit of serviceability. Flow index values do not guarantee reliability in the event of technological deviations in production.

Example 5

PP granules with stabilizers of 0.1% Al, 0.02% ,2, 0.06% P3 and 0.03% CaST were manufactured and laboratory tested as in Example 1.

The values in Table 2 show that the stabilization system used provides very good processing stability, causes minimal yellowness, and the presence of Gray Granules has not been detected at all in the process sample.

Example 6

The PP granulate stabilized with 0.1% Al, 0.04% P2, 0.04% P3 and 0.03% CaST was manufactured and laboratory tested as in Example 1. The values shown in Table 2 show that the stabilizing system used is able to provide all three endpoints.

Example 7

PP granulate stabilized with a 0.08% Al, 0.06% P3 and 0.02% P4 and 0.03% CaST stabilization system was prepared and tested in the laboratory in the same manner as in Example 1. The measurement results are shown in Table 2.

Based on these, it can be said that the system used provides excellent processing stability, high whiteness and suppresses the formation of gray granules. These excellent results as well as the measurement results in Examples 5a demonstrate a high degree of synergy when using a phenolic stabilizer with a combination of an easily hydrolyzable fostite.

Example 8

PP granulate stabilized with 0.1% Al, 0.1% A3, 0.1% PI and 0.08% CaST was prepared and laboratory tested as in Example 1. The measurement results are shown in Table 2. From the standpoint of processing stability, it was shown system as sufficient. However, from the yellow point of view, it is at an acceptable level and the presence of gray granules indicates that the combination of stabilizers is completely unsuitable for this use.

Example 9

Copolymer of propylene with ethylene containing 1,8% ethylene with a flow index of 4 dg / min, containing stabilizers 0,08% Al, 0,1% A3, 0,02% F'1, 0,02% PI, 0,02 % P3 and 0.08% CaST were treated in the same manner as in Example 1 »

The results of the laboratory tests are shown in Table 2.

In terms of processing stability and the presence of gray granules, the recipe appears to be good, although it shows a slightly reduced degree of whiteness.

Example 10

A propylene-ethylene copolymer containing 16% ethylene with a flow index of δ dg / min, containing 0.1% Al, 0.04% P2, 0.04% P5 and 0.08% CaST stabilizers was treated in the same manner as in Example 1 The results of the laboratory tests are shown in Table 2. In terms of processing stability and the occurrence of gray granules, the formulation appears to be good, although it shows a slightly reduced degree of whiteness.

Composition of the stabilization system at. treatment of PP containing 0.08% CaST

number of extruder passes

TV

PATENT MEASURES

Claims (1)

Stabilized polypropylene and propylene copolymers with 0.1 to 20 wt. % of ethylene containing 0.01 to 17 wt. % of phenol stabilizers and 0.01 to 17 wt. mixtures of fostite stabilizers, based on the polymer matrix, and optionally further "processing additives", characterized in that the mixture of fossil stabilizers is comprised of 10 to 90% by weight of phosphites subject to hydrolysis up to 7%, and 10 to 90% by weight, . Phosphites or phosphonites subject to hydrolysis above 7 Z.