JPS6153344A - Radiation-resistant polyolefin composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition resistant to the degradation with radiation, by compounding a polyolefin with a diaryl phosphate metal salt in combination with an additive such as organic phosphite compound, etc. CONSTITUTION:A polyolefin is compounded with (A) a diaryl phosphate metal salt of formula I or formula II (R1 and R2 are H or alkyl; M is metal of group I a- or IIa-; a is atomic valence of M; A is alkylidene) and (B) at least one kind of additive selected from hindered phenol antioxidant, organic phosphite compound, organic phosphonite compound and hindered amine photo- stabilizer. The component A is preferably the compound of formula I. The amount of the metal salt is 0.001-5pts.wt. per 100pts.wt. of the polyolefin.

Description

[Detailed description of the invention] The present invention relates to radiation-resistant polyolefin compositions.

Polyolefins such as polyethylene and polypropylene are
It is used in medical instruments such as syringes, tweezers, clamps, and food packaging materials, and these are often treated with radiation for the purpose of sterilization, but polyolefin deteriorates due to radiation and may cause cracks or cracks.
There were problems such as a decrease in mechanical strength and discoloration.

In order to prevent this radiation-induced deterioration, it has been proposed to use phenol-based antioxidants, organic phosphorus-containing compounds, or hindered amine-based light stabilizers, either alone or in combination with each other, but their effectiveness remains unclear. enough is enough;
Further improvements were requested.

As a result of intensive studies on this problem, the inventors of the present invention and others have found that by using a specific diarylphosphate metal salt in these systems, deterioration of polyolefins due to radiation irradiation can be significantly prevented.

That is, the present invention provides polyolefins with (1) at least one diarylphosphate metal salt represented by the following general formula (1) or (I[) and (2) a hindered phenolic antioxidant, an organic phosphorus The present invention provides a radiation-resistant polyolefin composition containing at least one selected from phytocompounds, organic phosphonite compounds, and hindered amine light stabilizers.

(In the formula, R and R2 each represent a hydrogen atom or an alkyl group, M represents a metal of Group 1a or Group Ua, and a represents M
, and A represents an alkylidene group.) The polyolefin composition of the present invention will be described in detail below.

In the compounds represented by the above general formulas (1) and (If), the alkyl groups represented by R and R2 include, for example, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tertiary-butyl, isobutyl, amyl, tertiary
Examples include 7 mil, hexyl, octyl, tertiary octyl, etc., and examples of the alkylidene group represented by A include methylidene,
Examples include ethylidene, butylidene, and impropylidene.

Examples of the metal represented by M include sodium, potassium, lithium, calcium, magnesium, barium, and the like.

Therefore, typical examples of compounds represented by the general formula (I) or (II) include the following compounds.

T:"u4fl.

Among these organic phosphate metal salt compounds, the general formula (
The compound represented by 1) is particularly preferred because of its great effect.

The amount of these organic phosphate metal salts added is 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, per 100 parts by weight of the polyolefin.

The phenolic antioxidant used in the present invention includes:
For example, 2,6-di-tert-butyl-p-cresol, 2
．． 6-diphenyl-4-octadecyloxyphenol,
Stearyl-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, distearyl-3,5-
Di-tert-butyl-4-hydroxybenzylphosphonate, thiodiethylene bis((3,5-di-tert-butyl-4
-Hydroxyphenyl)propione-)), 4.4°
-thiobis(6-tert-butyl-m-cresol), 2-
Octylthio-4,6-di(3,5-di-tert-butyl-
4-hydroxyphenoxy)-S-) riazine, 2.2
”-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-
tert-butylphenol), bis(3,5-bis(4-hydroxy-3-tert-butylphenyl)butyric acid coglycol ester, 4,4'-butylidene bis(
6-tert-butyl-m-cresol), 2.2°-ethylidenebis(4,6-di-tert-butylphenol), 2
．． 2°-ethylidene bis(4-sec-butyl-6-tert-butylphenol), 1.1.3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, bis(2-tert-butylphenol) 3-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1.3,5-tris(2,6-dimethyl-3-hydroxy-4-tert) butylbenzyl)in cyanurate, 1.3.5-)lis(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1.3.5-tris(3,5-di-tert-butyl- 4
-hydroxy1benzyl) -2,4,6-drimethylbenzene, 1,3,5-tris((3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl) isocyanurate, tetrakis[methylene- 3-
Examples include (3,5-di-tert-butyl-4-hydroxyphenyl)propionate comethane.

The amount of these phenolic antioxidants added is 0.001 to 3, preferably 0.001 to 3 parts by weight, per 100 parts by weight of the polyolefin.
005 to 1 part by weight.

Examples of the organic phosphite compound or organic phosphonite compound used in the present invention include tris(2,4-
di-tert-butylphenyl) phosphite, tris(nonylphenyl) phosphite, tris(mono- and di-mixed nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) phosphite Erythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, 1,1.3-)lis(2-methyl-4-ditridecyloxyphosphinoxy-5-tert-butylphenyl)butane, tetra(tridecyl) )・4,4″-butylidene bis(3-methyl-6=tert-butylphenol) diphosphite, hydrogenated bisphenol A polyphosphite, bis(octylphenyl)・bis[4,4″-butylidene bis(3-methyl- 6-tert-butylphenol)] ・1.6-hexanediol diphosphite,
Tetrakis(2,4-di-tert-butylphenyl)-4,
Examples include 4'-biphenylene diphosphonite.

The amount of these organic phosphites or organic phosphonite compounds added is o, based on 100 parts by weight of polyolefin.
oot~5 preferably 0.01 to 3 parts by weight.

The hindered amine light stabilizer used in the present invention is a hindered amine having a piperidine skeleton, such as 2.2.6.6-tetramethyl-4-piperidylbenzoate, bis(2,2,6,6-tetra Methyl-
4-piperidyl) sebacate, bis(1,2°2.6.
6-bentamethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-bentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-
hydroxybenzyl) malonate, tris(2,2,6
,6-tetramethyl-4-piperidyl)nitrilotriamotate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2 ,6,6-tetramethyl-4-piperidyl) di(tridecyl) -1,2
, 3,4-butanetetracarboxylate, bis(1,
2,2,6,6-bentamethyl-4-piperidyl) di(tridecyl)-1,2,3,4-butanetetracarboxylate, N-hydroxyethyl-2,2,6,6
-tetramethyl-4-hydroxypiperidine/dimethyl succinate condensate, 2-tert-octylamino-4,6-dichlorotriazine/1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino) ) hexane condensate,
1.6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/1.2-dibromoethane condensate, 2.2.4.4-tetramethyl-7-oxa-3
,20-diazadispiro(5,1,11,2)heneicosan-21-one,3.9-bis(1,1-dimethyl-2-[tris(2,2,6,6-tetramethyl-4
-piperidyloxycarbonyl)butylcarbonyloxy1ethyl]-2,4,8,10-tetraoxaspiro(5,5)undecane, 3,9-bis[1,I-dimethyl-2-tris (1,2, Examples include 2゜6.6-bentamethyl-4-piperidyloxycarbonyl)butylcarbonyloxyethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane.

The amount of these hindered amine light stabilizers added is 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, per 1 part of polyolefin 100f.

Examples of polyolefins whose radiation resistance is improved according to the present invention include low-density or high-density polyethylene,
Examples include straight-line low density polyethylene, polypropylene, polybutene, polymethylpentene, ethylene/propylene copolymer, ethylene/butene-1 copolymer, propylene/butene-1 copolymer, and mixtures thereof.

The composition of the present invention may contain metal soaps, ultraviolet absorbers, thioether antioxidants, fillers, pigments, foaming agents, antistatic agents, flame retardants, lubricants, processing aids, etc. as necessary. I can do it.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples.

Example 1 The following formulations were mixed and pelletized using an extruder at 210°C. Using this pellet, injection molding was performed at 280°C,
A test piece of 40×40×1 mm was prepared.

This test piece was irradiated with 2.5 megarads of gamma rays using a cobalt-60 radiation source.

The color difference (Hunter color difference ad) of the test piece before and after irradiation was measured. A color difference of 1.5 or less indicates almost no discoloration, a color difference of 1.5 to 3.0 indicates slight discoloration, and a color difference of 3.0 or more indicates a large degree of discoloration.

Further, the test piece after irradiation was placed in an oven at 135°C to measure heat resistance.

The results are shown in Table-1.

[Composition]

Calcium stearate 0.1 Organophosphate metal salt 0.2 Table-1 Example 2 Calcium stearate 0.11 in 100 parts by weight of Polyflopyref! A test piece was prepared in the same manner as in Example 1 by adding the Iit part and the additives shown in Table 2 below, and irradiated with 3.5 megarads of gamma rays. The heat resistance was measured.

The results are shown in Table-2.

Claims (1)

[Scope of Claims] For polyolefin, (1) at least one diaryl phosphate metal salt represented by the following general formula (I) or (II) and (2) a hindered phenolic antioxidant, an organic phosphite. A radiation-resistant polyolefin composition containing at least one selected from a compound or an organic phosphonite compound and a hindered amine light stabilizer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_1 and R_2 each represent a hydrogen atom or an alkyl group, and M is a group Ia group. or represents a Group IIa metal;
a represents the valence of M, and A represents an alkylidene group. )