JPH10130426A - Antioxidant eutectic and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antioxidant eutectic which can improve the dispersibility of an antioxidant having a high melting temp. (low volatility and highly persistent stabilization effect) into a polyolefin resin. SOLUTION: This antioxidant eutectic is prepd. by heat-mixing 20 to 80wt.% antioxidant A having a melting temp. of 140 to 250 deg.C with 80 to 20wt.% antioxidant B, contg. a long-chain alkyl group, having a melting temp. of 40 to 110 deg.C at a temp. of the melting temp. of the antioxidant A or above. The polyolefin resin compsn. is prepd. by adding and heat-kneading 0.01 to 5 pts.wt. eutectic with 100 pts.wt. polyolefin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antioxidant eutectic and a method for producing the same, and more particularly, to a high melting temperature antioxidant eutectic which has greatly improved dispersibility when blended into a polyolefin resin. And a method for producing the same, a polyolefin-based resin composition containing the eutectic, and a method for producing the same.

[0002]

2. Description of the Related Art When processing a polyolefin resin,
It is heated or kneaded, but at this time, it is oxidatively degraded by heat or oxygen. Although the oxidative deterioration proceeds automatically and continuously, in order to prevent the oxidative deterioration, an antioxidant is usually added to the polyolefin resin. Antioxidants are known as primary antioxidants, which give hydrogen to polymer radicals present in the process of autoxidation of the polymer and convert themselves into stable compounds.Phenolic antioxidants are typical. It has been known. In addition, phenolic antioxidants that give hydrogen to polymer radicals have a quinone structure, which can be converted back to the original phenolic structure or decomposed and stabilized by hydroperoxide generated during the autoxidation of the polymer. There is a so-called secondary antioxidant, and as typical examples, a sulfur-based antioxidant and a phosphorus-based antioxidant are known. When a primary antioxidant and a secondary antioxidant are simultaneously added to a polyolefin resin, the effect is said to increase synergistically. In fact, it is possible to mix two types of antioxidants simultaneously with a polyolefin resin. Many have been reported.

When a processed product of a polyolefin resin is used for a long period of time, the compounded antioxidant must be present in the resin as long as possible, and for this purpose, the antioxidant must have low volatility. Is desirable. In order to make the antioxidant low volatile, it is effective to increase the molecular weight of the antioxidant, and in recent years, the antioxidant has been actively increased in molecular weight. However, when the antioxidant has a high molecular weight, the melting point of the antioxidant generally increases, the dispersibility of the antioxidant in the polyolefin resin deteriorates, and the original effect of the antioxidant decreases, The blooming phenomenon in which the inhibitor precipitates on the resin surface occurs.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art.
An antioxidant co-melt which has low volatility and has improved dispersibility in a polyolefin resin, does not reduce the antioxidant effect and does not cause blooming, a method for producing the same, and a polyolefin containing the co-melt An object of the present invention is to provide a resin composition and a method for producing the same.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the melting temperature of an antioxidant having a high melting temperature and an antioxidant having a low melting temperature has been obtained. When the melting temperature of the antioxidant having a high melting temperature is lower than the melting temperature of the antioxidant, and it is blended with the polyolefin resin and kneaded, it is found that the dispersibility is better than that of the non-co-melted resin. Those having a long-chain alkyl group as an antioxidant have been confirmed to have good compatibility with the polyolefin-based resin and to further improve the dispersibility of the co-melted antioxidant, and have further studied and completed the present invention. .

[0006] That is, the present invention provides a melting temperature of 140 to 2
20 to 80% by weight of an antioxidant (A) at 50 ° C. and 80 to 20% by weight of an antioxidant (B) having a long-chain alkyl group and a melting temperature of 40 to 110 ° C. The melting temperature of the antioxidant (A) The above relates to the antioxidant eutectic obtained by heating and mixing. The present invention also provides an antioxidant (A) having a melting temperature of 140 to 250 ° C and an antioxidant (B) having a long chain alkyl group and having a melting temperature of 40 to 110 ° C and having a melting temperature of 40 to 110 ° C.
% By weight at a temperature equal to or higher than the melting temperature of the antioxidant (A). In addition, the present invention relates to a polyolefin resin 100
The present invention relates to a polyolefin-based resin composition obtained by blending 0.01 to 5 parts by weight of the antioxidant eutectic melt of the present invention in parts by weight and kneading with heat. Further, the present invention provides the antioxidant eutectic of the present invention in an amount of 0.0
The present invention relates to a method for producing a polyolefin-based resin composition, which comprises mixing 1 to 5 parts by weight and kneading with heat.

The melting temperature used in the present invention is 140 to 25.
Examples of the antioxidant (A) at 0 ° C. include phenolic antioxidants such as 4,4′-thiobis (3-methyl-6-tert-butylphenol) and 4,4′-methylenebis (2,4).
6-di-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,
2′-ethylidenebis (4,6-ditert-butylphenol), N, N′-hexamethylenebis (3,5-ditertbutyl-4-hydroxyhydrocinnamide), tris (3,5-dibutyl) Tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-2,4,6
-Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tris (2 -Methyl-4-hydroxy-5
-Tert-butylphenyl) butane or butyric acid 3,3-
Bis (3-tert-butyl-4-hydroxyphenyl) ethylene ester and the like, and phosphorus-based antioxidants such as 2,2-methylenebis (4,6-di-tert-phenylphenyl) octyl phosphite, bis (2,6- Di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite or 2 , 2'-ethylidenebis (4,6-di-tert-butylphenyl) fluorophosphonite, among which phenolic antioxidants are particularly preferred.

As the antioxidant (B) having a long-chain alkyl group and a melting temperature of 40 to 110 ° C. used in the present invention, those having an alkyl group having 10 to 22 carbon atoms are preferable. Are sulfur-based antioxidants, for example, phosphorus-based antioxidants such as pentaerythritol tetrakis (3-laurylthiopropionate), dilaurylthiodipropionate, distearylthiodipropionate or dimyristylthiodipropionate; For example, distearyl pentaerythritol diphosphite, and phenolic antioxidants, such as octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate or 3,5-di-tert-butyl-4-.
Examples thereof include n-hexadecyl hydroxybenzoate, and among them, a sulfur-based antioxidant is particularly preferable.

An antioxidant (A) having a melting temperature of 140 to 250 ° C. and a melting temperature of 40 to 110 having a long-chain alkyl group
The mixing ratio of both antioxidants for obtaining a eutectic with the antioxidant (B) at a temperature of ℃ is as follows:
The range in which the antioxidant effect is specifically exhibited is preferably in the range of 20 to 80% by weight of the antioxidant (A) and 80 to 20% by weight of the antioxidant (B). Here, the antioxidant (A) and the antioxidant (B) are generally used one by one, but depending on the case, a plurality of antioxidants may be used as one or both antioxidants. In addition, the eutectic melt of the present invention includes, without departing from the spirit of the present invention,
An antioxidant other than the above A and B may be further added in a small amount.

In the production of the eutectic of the present invention, the antioxidant (A) and the antioxidant (B) are weighed, and then they are placed in a container and heated at a temperature higher than the melting temperature of the antioxidant (A). After mixing, the mixture is cooled and processed into an easily usable shape such as a granule, a flake or a powder. During the heating and mixing, the container containing the antioxidant is preferably placed under an atmosphere of an inert gas such as nitrogen gas.

The polyolefin resin used in the present invention includes ethylene, propylene, butene-1, pentene-
Examples thereof include polymers mainly composed of α-olefins such as 1, hexene-1 and octene-1, and among them, ethylene-based resins and propylene-based resins are preferred.

Examples of the ethylene resin include a high-pressure low-density polyethylene, a medium-density polyethylene, a high-density polyethylene, a linear low-density ethylene-α-olefin copolymer,
Ultra low density ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, etc. are exemplified. Modified ethylene resins graft-modified with an acid or acid anhydride, a compound having an epoxy group such as glycidyl methacrylate, or an unsaturated silane compound such as vinyltrimethoxysilane are exemplified.

Examples of the propylene-based resin include, besides a propylene homopolymer, a random copolymer or a block copolymer of propylene and another α-olefin.
Modified propylene obtained by graft-modifying these propylene resins with a carboxylic acid or acid anhydride such as maleic acid or maleic anhydride, a compound having an epoxy group such as glycidyl methacrylate, or an unsaturated silane compound such as vinyltrimethoxysilane. Examples are based resins.

The compounding ratio of the eutectic melt of the present invention to the polyolefin resin is 0.01 to 5 parts by weight based on 100 parts by weight of the polyolefin resin. If the amount of the eutectic melt is less than 0.01 part by weight, the antioxidant effect is insufficient and oxidative deterioration is caused. Undesirably, if it exceeds 5 parts by weight, the saturation point is reached. This is not only because the effect is not improved, but also because the antioxidant causes a blooming phenomenon in which the antioxidant precipitates on the surface of the resin.

The polyolefin-based resin composition of the present invention obtained by blending a eutectic with a polyolefin-based resin is prepared by a usual method, that is, the polyolefin-based resin and the eutectic are weighed and charged into a hopper or the like. After mixing, heating and kneading with a roll mill, kneader, Banbury mixer, continuous mixer or extruder,
It can be produced by granulation.

Various additives and auxiliary materials can be added to the polyolefin resin composition of the present invention according to the purpose of use, as long as the properties of the present invention are not impaired.
Various additives and auxiliary materials include stabilizers, ultraviolet absorbers, light stabilizers, antistatic agents, copper damage inhibitors, crosslinking agents, crosslinking aids, foaming agents, lubricants, antiblocking agents, processability improvers, Examples include a filler, a dispersant, a neutralizing agent, an air bubble inhibitor, a colorant, and carbon black.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS It is said that the effect of synthesizing an antioxidant in a polyolefin resin is synergistically enhanced by simultaneous mixing of a so-called primary antioxidant and a secondary antioxidant. In the invention, an antioxidant having a relatively high melting temperature (melting temperature of 140 to 250 ° C.) and an antioxidant having a long chain alkyl group having a relatively low melting temperature (melting temperature of 40 to 250 ° C.)
By preparing a eutectic (110 ° C.) in advance and then blending it with the polyolefin resin, an effect exceeding the synergistic effect of the above two kinds of antioxidants appears. This is because the antioxidant co-melt obtained by co-melting two antioxidants, one of which is an antioxidant containing a long-chain alkyl group, has a relatively high melting temperature and low volatility. This is because the dispersibility in the polyolefin resin has been improved.

[0018]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

First, Table 1 shows the melting temperatures of the antioxidants used in the examples.

[Table 1]

Example 1 In a stainless steel container equipped with a stirrer, 4,4'-thiobis (3
-Methyl-6-tert-butylphenol) and 50% by weight of pentaerythritol tetrakis (3-laurylthiopropionate), and the vessel was purged three times with nitrogen gas to form a nitrogen gas atmosphere. , Heated to 170 ° C to dissolve, stirred and mixed well, then cooled,
Powder was obtained to obtain a eutectic. Melt index 2.0
g / 10 minutes, 0.4 part by weight of the eutectic obtained above was mixed with 100 parts by weight of a high-pressure low-density polyethylene having a density of 0.922 g / cm ^{3, and} the mixture was charged into a roll mill and kneaded at 120 ° C. for 15 minutes. Further, 2.0 parts by weight of dicumyl peroxide was added as a crosslinking agent, and the mixture was kneaded at 120 ° C. for 3 minutes, and then granulated to form pellets. Next, the pellet was pressure-formed at 180 ° C. for 15 minutes using a mold to obtain a 1 mm thick sheet. A test piece punched out from this sheet with a dumbbell in accordance with the tensile test of JIS C3005 is 1
Place in a 60 ° C air-circulating thermostat and heat aged, JI
The elongation measured according to the test conditions of SC3005 is 10
The time required to reach 0% was measured and was 264 hours. In addition, the above-mentioned 1 mm thick sheet is
A test piece punched out into a square having a temperature of 23 ° C. and a humidity of 50
% In a constant temperature and humidity room for 30 days, the surface of the test piece is washed with 30 g of dichloromethane, and blooming of the test piece is measured for the washed dichloromethane by analysis of an antioxidant with an infrared spectrophotometer. As a result, the concentration of the antioxidant in dichloromethane was very small.

Example 2 The antioxidant used in Example 1 was 4,4'-thiobis (3
-Methyl-6-tert-butylphenol) and 33% by weight of pentaerythritol tetrakis (3-laurylthiopropionate) were repeated, except that the procedure was the same as in Example 1. The time required for elongation after heat aging to reach 100% was 251 hours. Further, the concentration of the antioxidant in dichloromethane was very small as in Example 1.

Example 3 The antioxidant used in Example 1 was 4,4'-thiobis (3
-Methyl-6-tert-butylphenol) and 67% by weight of pentaerythritol tetrakis (3-laurylthiopropionate) were repeated, except that the procedure was the same as in Example 1. The time required for 100% elongation after heat aging was 240 hours. Further, the concentration of the antioxidant in dichloromethane was very small as in Example 1.

Comparative Example 1 In Example 1, a eutectic product of two kinds of antioxidants was prepared, but each oxidant was added to 100 parts by weight of a high-pressure low-density polyethylene without preparing the eutectic product. The same operation as in Example 1 was repeated except that 0.2 part by weight was blended.
The time required for 100% elongation after heat aging is 14
4 hours. The concentration of the antioxidant in dichloromethane was 25 times that of Example 1.

Example 4 The same operation as in Example 1 was repeated except that distearylthiodipropionate was used in place of the antioxidant pentaerythritol tetrakis (3-laurylthiopropionate) in Example 1. . Elongation after heat aging is 10
The time required to reach 0% was 221 hours. Further, the concentration of the antioxidant in dichloromethane was very small as in Example 1.

Comparative Example 2 In Example 4, a co-melt of two kinds of antioxidants was prepared, but each of the anti-oxidants was added to 100 parts by weight of a high-pressure low-density polyethylene without preparing the co-melt. The same operation as in Example 4 was repeated except that 0.2 part by weight was added.
The time required for 100% elongation after heat aging is 12
It was 0 hours. The concentration of the antioxidant in dichloromethane was 20 times that of Example 4.

Example 5 The antioxidant 4,4'-thiobis (3
-Methyl-6-tert-butylphenol) was replaced with tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the heating temperature for co-melting the two antioxidants was 195 ° C. The same operation as in Example 1 was repeated, except that it was performed. The time required for the elongation after heat aging to reach 100% was 210 hours. Further, the concentration of the antioxidant in dichloromethane was very small as in Example 1.

Comparative Example 3 In Example 5, a co-melt of two kinds of antioxidants was prepared, but each of the anti-oxidants was added to 100 parts by weight of a high-pressure low-density polyethylene without preparing the co-melt. The same operation as in Example 5 was repeated except that 0.2 part by weight was blended.
The time required for 100% elongation after heat aging is 10
6 hours. Further, the concentration of the antioxidant in dichloromethane was 27 times that of Example 5.

Comparative Example 4 The same operation as in Example 1 was repeated, except that triphenylphosphite was used in place of the antioxidant pentaerythritol tetrakis (3-laurylthiopropionate) in Example 1. The time required for the elongation after heat aging to reach 100% was 156 hours. The concentration of the antioxidant in dichloromethane was 17 times that of Example 1.

As is evident from the results of the above Examples and Comparative Examples, when a eutectic of two kinds of antioxidants was blended with a polyolefin resin, the eutectic was produced without forming a eutectic.
Compared with those obtained by directly blending various kinds of antioxidants with polyolefin-based resins, the resistance to heat aging was extremely excellent, and the blooming in the blooming test was extremely small. Further, Comparative Example 4 using an antioxidant having no long-chain alkyl group was inferior in both heat aging resistance and blooming resistance despite being blended with a polyolefin resin after preparing a eutectic. Was.

[0030]

As described in detail above, the antioxidant has been conventionally made high in molecular weight in order to lower the volatility of the antioxidant. However, such an antioxidant is used in a polyolefin resin. In the case of being blended in, there was a disadvantage that the dispersibility of the antioxidant deteriorated, whereas in the present invention, an antioxidant having a specific melting temperature range and a specific melting temperature range and having a specific molecular structure By previously forming a co-melt with an antioxidant, the above-mentioned conventional disadvantages are solved, and the eutectic exhibits excellent dispersibility when blended with a polyolefin-based resin. Therefore, the antioxidant eutectic of the present invention, when blended with a polyolefin resin, does not reduce the antioxidant effect, does not cause a blooming phenomenon in which the antioxidant precipitates on the resin surface, and has a melting temperature. Has a relatively high volatility and has a long-lasting antioxidant effect. Further, the method for producing the antioxidant eutectic of the present invention is:
It is possible to provide an antioxidant eutectic having the above-mentioned excellent effects by an easy operation. Furthermore, since the polyolefin-based resin composition of the present invention is a resin composition containing an antioxidant eutectic that exhibits the above-described excellent effects, without reducing the antioxidant effect or causing blooming. It has an extremely high stability against oxidation that the antioxidant effect lasts for a long time. Further, the method for producing a polyolefin-based resin composition of the present invention makes it possible to provide a polyolefin-based resin composition having the above-described excellent effects by an easy operation.

Claims (4)

[Claims] 1. An antioxidant (A) having a melting temperature of 140 to 250 ° C. (A) at 20 to 80% by weight and an antioxidant (B) having a long chain alkyl group having a melting temperature of 40 to 110 ° C. at 80 to 20% by weight. An antioxidant eutectic obtained by heating and mixing at a temperature equal to or higher than the melting temperature of the antioxidant (A). 2. An antioxidant (A) having a melting temperature of 140 to 250 ° C. and 20 to 80% by weight of an antioxidant (B) having a long chain alkyl group and having a melting temperature of 40 to 110 ° C. and 80 to 20% by weight. A method for producing an antioxidant eutectic, comprising heating and mixing at a melting temperature of the antioxidant (A) or higher. 3. A polyolefin resin composition obtained by mixing 0.01 to 5 parts by weight of the antioxidant eutectic compound according to claim 1 with 100 parts by weight of the polyolefin resin and kneading with heat. 4. A method for producing a polyolefin-based resin composition, which comprises mixing 0.01 to 5 parts by weight of the antioxidant eutectic compound according to claim 1 with 100 parts by weight of a polyolefin-based resin and kneading the mixture. .