CS238531B1 - Colored polyethylene - Google Patents

Abstract

Light-stabilized polyethylene for injection-molded products, containing stabilizers, dyes, or other processing additives, which, in addition to the basic polymer component, contains 0.015 to 0.1 wt. % of a phenolic antioxidant having tertiary butyl groups in both ortho-positions to the hydroxyl and in the paraposition a CH2 or -CH2-CH2-C-OR group, where R is hexadecyl or octadecyl or symmetrical pentaerythrityl), 0.05 to 0.5 wt. % of a phosphite of the type P-QO-ArJ 3 where Ar is phenyl substituted in the para-4 or metaposition by a hexyl to decyl group, preferably nonyl, or a styryl group, and 0.1 - 2 ® tris (sodium aluminum silicate) sodium sulfide, or technical ultramarine, wherein the ratio of concentrations of phenolic antioxidant: phosphite: ultramarine is 1:4:4 to 1:4:12.

Description

The invention relates to colored polyethylene for injection molded products stabilized against the effects of sunlight.

Linear high-density or medium-density polyethylene, produced by fluidized bed polymerization on supported catalysts, exposed to solar radiation and elevated temperatures very rapidly sieves, losing its original good mechanical properties.

In order to prevent these undesirable effects, stabilizers are added to the powdered polymer prior to granulation to protect the polymer either at high processing temperatures or exposure to sunlight. Among the common substances used to inhibit thermo-oxidative degradation are phenols, phosphites, dialkyl sulfides, amines, thiodipropionic acid esters. Benzophenone derivatives, benzotriazole, salicylic acid and benzoic acid esters and some piperidine derivatives are also used to stabilize polyethylene against the effects of sunlight. Some pigments also have a stabilizing effect against the effects of sunlight, of which carbon black and some transition metal oxides are most important. ultramarine is used as color pigment and stabilizer.

We have now found a new combination of 3 types of stabilizers, one of which is ultramarine, which in its effect replaces the function of ultraviolet absorbers.

SUMMARY OF THE INVENTION The present invention provides colored polyethylene containing stabilizers, pigments, and optionally other processing ingredients, comprising 0.015 to 0.1% by weight of a phenolic antioxidant with tertiary butyls in both ortho-positions and with a methyl or -Ct-CH 2 COOR group in paraposition. is hexadecyl or octadecyl or symmetrically substituted pentaerythrityl, 0.03 to 0.3% by weight of triphenylphosphite, the phenyl groups of which can be substituted with 6 to 10 carbon atoms or styryl and 0.1 to 5% by weight of tris (sodium aluminum silicate) sodium sulfide

238,531, wherein the ratio of phenolic antioxidant: fostite: ultramarine concentration is 8 preferably 1: 4: 4 to 1: 4: 12 ·

High synergetic effect in inhibiting accelerated photo * oxidative degradation and natural atmospheric aging ee achieves due to different mechanism of action of these three substances ·

When monitoring the inhibitory effect of these ternary systems, it was found that the optimum effects are achieved in those phosphites which are liquid at room temperature and which have the structure P- 5 "OArJ ₃ wherein Ar is phenyl substituted in the para or meta position with an alkyl or styryl · Phenylphosphites unsubstituted or substituted at other positions, including solid phosphites, proved to be ineffective in these ternary systems · This is due not only to the structure but also to mobility of these compounds at normal temperatures ·

The second component of this ternary system is tris (sodium * mimium orthosilicate) sodium sulphide, also known as a technical product such as the inorganic pigment ultramarine. It is believed that suitably substituted phenylphosphites form with a type 3 Na Al Si O ^ silicate. ^ Additive compounds of unknown horse fat, which exhibit unexpected synergetic effects in photooxidative degradation of polyolefins · Sons also tested sodium * aluminum silicates which did not contain sulphide-bound sulphide in their molecule · These substances, however, proved to be ineffective in these systems ·

The last component of the ternary system is a suitably substituted phenol, which serves to inhibit thermeoxidative degradation, the perfect inhibition of which results in a low concentration of photosensitive centers in the polymer. Thus, the low concentration of these defective sites decreases the primary initiation rate which is suppressed by phosphite * silicate sulphide. ·

It has further been found that the synergistic effect of this ternary system is not suppressed even in more complex polymer blends to which other cell additives are added to improve processing properties or to achieve different color shades through other pigments. These additives may be softening or dispersing agents or other color pigments such as yellow, red, black, white and the like ·

In order to clarify the injection molding technology of the new invention, the following alternative production description is provided.

(a) A granulate containing one of the abovementioned phenolic antioxidants is produced from a linear polyethylene manufacturer. phosphite ultramarine, or some other color pigments and other additives. Moldings are produced on the injection molding machine from this granulate, which contains the prescribed additives in a synergetically acting concentration and relative ratio.

b) Another alternative production solution is to prepare a conventional linear polyethylene granulate with a flow index of 5 to 18 g / 10 min at 190 ° C containing phenolic antioxidants. This granulate is mixed at the processor with a granular concentrate (based on linear or branched polyethylene), which contains all three critical additive components i.e. phenol, phosphite, ultramarine in the prescribed ratio and concentration. In addition to these three synergistic ingredients, the concentrate may contain other pigments and additives. Moldings are made from a mixture of linear polyethylene and concentrate on an injection molding machine.

c) A technologically feasible method is the preparation of granulated linear polyethylene suitable for injection (i.e. IT 5 to 18 g / 10 min at 190 ° C), which is stabilized at the manufacturer with a phenolic antioxidant and phosphite in the prescribed concentration ratio. Prescribed amounts of concentrate containing ultramarine or other dyes and additives are added to this granulate at the manufacturer in order to achieve the desired shades (eg yellow-green, green, blue-green, violet).

Moldings are produced from this mixture of granulates.

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

The polymers used in the examples were high density linear polyolefins.

Type A - with a flow index of 6.1 g / 10 min - 190 ° C,

Type B - with a flow index of 17.9 g / 10 min - 190 ° C.

- 4 Stabilizing additives used: 238 531

I. tetrakis - (methylene-3- (3 *, 5 * - di-tert-butyl-4-hydroxy-phenyl propionate) methane

II · β - (3,5-di-tert-butyl-4-hydroxyphenyl) -propionic acid octadecyl ester

III. diterc.butyl p. krssol

IV. trisphenoxyphenyl 17 phosphite

V. Tris-styryl-phenyl phosphite Example 1

Type A granulate containing 0.05% stabilizer II. and 0.2% stabilizing additive IV, was mixed with 1.5% stabilizing concentrate containing 40% ultramarine. The granulate mixture was used for crates production, part of crates was pressed into foils of 0.5 mm thickness and exposed in Xenotest 450 until the original ductility was halved. This time was 2,380 h. Example 2

Type A granulate containing 0.05% stabilizing additive I.

0.2% stabilizing additive IV. and 0.6% ultramarine was used for crates. A portion of the crates were crimped onto 0.5 mm thick sheets and exposed in an Xenotest 450 until the original ductility was halved. This time was 2,380 h.

Example 3

Type A granulate containing 0.05% stabilizer II. and 0.2% stabilizing additive IV. was mixed with 1% color concentrate containing 20% tris (sodium aluminum orthosilicate) sodium trihydride, 15% yellow dye in the form of a calcium lacquer monoazopigment resulting from the coupling of 2-nitroaniline-4 sulfoacids. acetoacetanilide (PV yellow GL), 5% oxide titanium dioxide and 0.1% carbon black supported on branched polyethylene.

The mixture of granulated polyethylene and color concentrate was used to make crates, part of the crate was pressed onto a 0.5 mm thick film and exposed in the Xenotest 450 until the original ductility was halved. This time was 2,385 h.

- 5 Example 4 238 531

Type B granules, containing 0.05% stabilizing additive I and 0.2% stabilizing additive IV, were mixed with 1% color concentrate containing 20% tris (sodium aluminum silicate) sodium trisulphide, 15% yellow dye in the form of a calcium lacquer monoazopigmsntu coupling the resulting 2 - nitroaniline - 4 with a sulfonic acid ^and 8 l £? anilides, 5% titanium dioxide and 0.1% carbon black supported on the branched polyethylene · granulated mixture of polyethylene and color concentrate was used for producing containers, the crate was přslisována on a 0.5 mm thick film and exposed on the Xenotest 450 until the original ductility is halved. This exposure time was 2454 hours.

Example 5

Granule type A containing 0.05% stabilizing additive III. and 0.2% stabilizing additive V, was mixed with 1% color concentrate containing 20% tris (sodium aluminum sulphate) sodium sulfide 15% yellow dye in the form of a calcium lacquer mono-aspirin resulting from the coupling of 2-nitroaniline-4 sulfoacid with acetoacetanilide, 5% and 0.1% carbon black on a carrier that was branched polyethylene. The mixture of granulated linear polyethylene and color concentrate was used for crates production, the crates of the crates produced were pressed on a 0.5 mm photograph and irradiated in the Xsnotsst 450 until the ductility was halved. This time was 2220 h. Example 6

Linear polyethylene granules containing 0.015% stabilizing additive I. were mixed with 1% stabilizing concentrate containing 20% ultramarine 15% yellow dye in the form of a calcium lacquer monoazoplgment resulting from the coupling of 2 - nitroaniline - 4 anilide anilide, 5% titanium dioxide, 20% stabilizing additive IV . 4% stabilizer II. and 0.1% carbon black. The granulate mixture was used for crates production, part of crates was pressed into foils with a thickness of 0.5 mm and exposed in Xenotest 450 until the original ductility was halved. This exposure time was 2530 h.

Example 7

238 531

Granulate type A containing 0.05% stabilizing additive II · blended with 1.5% blue granular concentrate containing 40% tris (sodium orthosilicate) sodium sulphide as technical product (ultramarine) · Granulate mixture was used for crates production, part of crate was re-spun on a 0.5 mm thick film and exposed in Xenotest 450 until the original ductility was halved. This exposure time in this case was 455 h.

Example 8 1 <0.2% UV absorber 2 of hydroxy-4 ^, 4-octyloxybenzophenone was added and crates were molded from it. A 0.5 mm thick film was prepared in part and exposed in a Xenotest 450 to loss original ductility in half · Exposure time was 1,685 h.

Example '9

Granule type A containing 0.05% stabilizing additive II · was mixed with 1% green granular concentrate containing 20% tris (sodium aluminum silicate) sodium sulphide, 15% yellow dye in the form of a calcium lacquer monoazopigment resulting from the coupling of 2-nitroaniline - 4 - % of titanium dioxide and 0.1% carbon black · The mixture of granulates was used for crates · A part of the crate was pressed on a 0.5 mm thick film and exposed in Xenotest 450 until the original ductility was halved · Exposure time was in this case only 518 h.

Example 10

0.2% UV absorber 2 of hydroxy-4 octyloxybenzophenone was added to the granulate mixture of Example 9 and pressed / M crates were pressed. Foils of 0.5 mm thickness were prepared in part and exposed to Xenotest 450 until the original ductility was halved. The exposure time was 1,585 h.

The colored polyethylene dis of the invention is stabilized against the effects of UV radiation better than is achieved by the addition of relatively expensive UV abaorbers, which are additionally harmful to health and therefore should not be included in moldings that come into contact with foodstuffs such as fruit and vegetable crates .

Claims (1)

SUBJECT OF THE INVENTION 238 531 Colored polyethylene for injection molded products containing! stabilizers, pigments and / or other processing aids, characterized in that it contains 0.015 to 0.1% by weight of a phenolic antioxidant with β tertiary butyls in both ortho positions and with a methyl or -CHg-CHg-C-OR group in the para position where R is hexadecyl or octadecyl or symmetrically substituted pentaerythrityl, 0.05 to 0.3% by weight of triphenylphosphite whose phenyl groups may be substituted by an alkyl of β 6 to 10 carbon atoms or styrene and 0,1 to 5% by weight of tris / sodium aluminum silicate / sodium sulphide, ie ultramarine, with a phenolic antioxidant: phosphite: ultramarine concentration ratio of 1: 4: 4 to 1: 4: 12.