JPS58189249A - Stabilized polyolefin resin composition - Google Patents

Abstract

PURPOSE:To provide the titled resin compsn. exhibiting very excellent stability against heat and oxidation, by blending a specified phenol compd. and a specified sulfur compd. with a polyolefin resin. CONSTITUTION:Tetrakis [methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] methane (A) and dimyristyl 3,3'-thioclipropionate (B) in a weight ratio of A:B= 1:1-15 are blended with a polyolefin resin to obtain the titled resin compsn. When the compds. A and B are previously melt-mixed in a weight ratio of A:B=1:1-15 and the mixture is blended with the polyolefin resin, the effect can be increased. Examples of the polyolefin resins are poly-alpha-olefins and copolymers thereof and polypropylene is particularly preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) The present invention relates to a polyolefin resin composition having extremely excellent stability against heat and oxidation.

Polyolefin resins have excellent physical, chemical, and electrical properties, so they can be processed into molded products, pipes, sheets, films, etc. by various methods such as blow molding, extrusion molding, injection molding, or calendering. Used in many fields. When polyolefin resins such as polyethylene and polypropylene are used alone, they deteriorate due to the effects of heat and oxygen during processing or use, and their physical properties commonly deteriorate with phenomena such as softening, embrittlement, and discoloration. This is well known. In order to prevent this phenomenon, various phenol-based, sulfur-based, phosphorus-based, and other antioxidants have been added singly or in combination during the production and processing steps of polyolefin resins.

Here are some examples of synergistic effects achieved through combined use with various phenols and sulfurs: (2) For example, tetrakis[methylene-3-(3°5-di-
t-phthyl-4-hydroxyphenyl) propionate comethane and dilauryl-3゜3'-thiodipropionate or distearyl-3,3'-thiodipropionate or pentaerythritol-tetrakis (β-dodecylthiopropionate) ), bis[3,3-bis(4
-Hydroxy-3-[-butylphenyl)butyric acid) glycol ester and dilauryl-3,3'-thiodipropionate, tris(2,6-cymethyl-4-[-butyl-
Combinations such as 3-hydroxybenzyl)in cyanurate and dilauryl-3,3'-thiodipropionate are typical and already known. Among these combinations, tetrakis[methylene-3-(3°5-
The combination of di-t-butyl-4-hydroxyphenyl)propionate comethane and distearyl-3,3'-thiodipropionate has the best performance in terms of thermal and oxidative stability, and is at the state-of-the-art level of the conventional technology. It is thought that,
Surface blemish (8) There are drawbacks such as one-sidedness, so-called whitening phenomenon, and none of these combination methods are yet fully satisfactory.

As a result of various studies to solve these problems, the present inventors have found that by blending a specific phenol compound and a specific sulfur compound into a polyolefin resin, the present inventors can overcome the conventional combination technology of antioxidants. discovered that an unexpected and surprising synergistic effect could be obtained, and even more surprisingly, the effect was significantly increased by blending a pre-melted mixture of these specific phenolic compounds and specific sulfur compounds into polyolefin resin. The present inventors have discovered that this material has extremely superior thermal stability and oxidation stability compared to the conventional technology, leading to the present invention.

That is, the present invention provides polyolefin resin with tetrakis [
Methylene-3-(3,5-di[-butyl-4-hydroxyphenyl)propionate comethane [Compound (I
)] and] cimilistyl-3,3'-thiodipropionate compound (■)] (4) in a range of fI): (ITl = 1:1 to 15 (weight ratio)). The present invention provides a stabilized polyolefin resin composition having the following properties.

In the polyolefin resin composition of the present invention, the compound (1
1 and the compound (Ill total addition I is polyolefin resin 1
It is usually 0.001 to 1 part by weight per 0.00 parts by weight,
Preferably tL< is 0.01 to 0.8 parts by weight. Furthermore, even if the combined weight amount of compound (ITI) exceeds twice that of compound (11), it is difficult to obtain commensurate effects, which is also economically disadvantageous.

In addition, the polyolefin resin composition of the present invention is basically formed by blending compound m and compound example) in a specific range, but compound (Il and compound (If)) are blended in advance within a specific range. A more preferable effect can be obtained by blending a mixture melt-mixed at 85°C to 200°C, preferably 90°C to 150°C.

(5) In the present invention, in order to blend compound (I) and compound (III) or a molten mixture of compound (I) and compound (III) into a polyolefin resin, stabilizers, pigments, fillers, etc. are generally added to the polyolefin resin. Known equipment and operating methods for mixing and blending can be applied almost as they are.

The polyolefin resin composition of the present invention may contain other additives, such as ultraviolet absorbers, light stabilizers, antioxidants, metal deactivators, metal soaps, nucleating agents, lubricants, antistatic agents, and flame release agents. , pigments and fillers.

In particular, the light resistance can be improved by adding ultraviolet absorbers, hindered amine light stabilizers, and the like. Examples of these light stabilizers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4+ n-octoxybenzophenone, 2(2-hydroxy-5-methylphenyl)benzotriazole,
(2-Hydroxy-3-t-butyl-5-methylphenyl)-5-chloro-benzotri(6) azole, 2(2-hydroxy-3,5-di[-butylphenyl)-5-chloro-benzotriazole , 2(
2-Hydroxy-3,5-di-amylphenyl)benzotriazole, (2゜2'-thiobis(4-t-octylphenolate)]-butylamine Ni salt, 2,2,6
．． 6-tetramethyl-4-piperidinylbenzoate,
Bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, 2-(3,5-di-monobutyl-4-
hydroxybenzyl) 'I n -butyl-malonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), 1-[,2-(3-(3,5-di(-butyl-4) -hydroxyphenyl)propionyloxy)
ethyl]-4-[3-(3,5-di-t-butyl-4-
hydroxyphenyl)propionyloxy]-2+ 2
Examples include t 6 t 6-titramethylbiveridine, dimethyl succinate/1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-titramethylpiperidine polycondensate, and the like.

(7) Furthermore, by adding another phosphite-based antioxidant to the composition of the present invention, its hue can be improved. These phosphite antioxidants include:
For example, distearyl pentaerythritol diphosphite, tris(2,4-se-t-butylphenyl) phosphite, tris(2-1-butyl-4-methylphenyl) phosphite, bis(2,4-di-t- butylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di[-butylphenyl)-4,4'-biphenylene diphosphite, and the like.

Polyolefin resins stabilized by the present invention include low-density polyethylene, medium-high density polyethylene, linear low-density polyethylene, polypropylene, polybutene-
Polyα-olefins such as 1, propylene-ethylene random or block copolymers, ethylene-butene-1
Poly α-olefin copolymers such as random copolymers,
Copolymers of polyα-olefins and vinyl monomers such as maleic anhydride-modified polypropylene (8) and mixtures thereof can be used, and among these, polypropylene is particularly effective.

EXAMPLES Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 After mixing the following formulation in a mixer for 5 minutes, the cylinder temperature was 230 to 240°C, the head die temperature was 250°C,
The mixture was melt-kneaded and granulated using an extruder with a rotational speed of 2 rpm. The pellets thus obtained were formed into a sheet with a thickness of 1□m using a hot press at 210°C to prepare a test piece of 4Q x 40 x 1 mm. The time until 3096 of the test piece area became brittle was measured in a gear oven at 160° C., and the thermal and oxidation stability was evaluated.

Also, surface whitening phenomenon was observed at room temperature for 2 months. The results are shown in Table 1.

(0) <Blend> Unstabilized polypropylene resin 100 parts by weight Calcium stearate 0.1 Test compound
Variables The test compounds indicated by symbols in Table 1 are the following compounds.

I-1 Tetrakis [methylene-3-(3゜5-di-t-
Butyl-4-hydroxyphenyl)propionate comethane I-2bis[3,3-bis(4-hydroxy-3-t-
butylphenyl) acetic acid] glycol ester ■-3 tris(2,6-dimethyl-4-t-phthyl
-Hydroxybenzyl) Incyanurate If-1 Simyristyl-3,3'-thiodipropionate n-2 Dilauryl-3,3'-thiodipropionate (10) If-3 Distearyl-3,3''-thio Dipropionate Also, I-1 compound and ll-1 compound at 95-100℃
The mixture was melted and mixed. The weight ratio of I-1 compound:■-1 compound is as follows.

1[-1I-1:I[-1=1:2 III-2I-1:I[-1-1:4

Claims (3)

[Claims] (1) Tetrakis[methylene-3-(3,5-di[-butyl-4-hydroxyphenyl)propionate] comethane [compound (I)] and] cimilistyl-3,3'-thiodipropionate compound in polyolefin resin A stabilized polyolefin resin composition comprising (r)J in a range of (I):(IIl=1:1 to 15 (weight ratio)). (2) The stabilized polyolefin according to claim 1, wherein Compound II) and Compound +II) are melt-mixed in advance in a range of 1 to 15 (weight ratio). Resin composition. (3) The stabilized polyolefin resin composition according to any one of claims gJ1 to 2, wherein the polyolefin resin is polypropylene.