JPH0431489A - Antioxidant and polymer composition containing it - Google Patents

Abstract

PURPOSE:To obtain an antioxidant having a sufficient antioxidizing effect and an excellent blooming resistance by using a specified thioether compound as constituent. CONSTITUTION:An antioxidant comprising a compound of the formula, wherein R, R1, and R2 are each an organic group, at least one of which is a group having a carbon-carbon unsaturated bond; and x>=0, provided that at least one of R1 and R2 is a group having a carbon-carbon unsaturated bond when x=0. A polymeric material is mixed with this antioxidant in an amount of 0.1-20wt.% based on the polymeric material to give a polymer composition. An appropriate amount of a phenolic antioxidant is preferably incorporated together with this antioxidant into the composition. A mixer usually in use can be employed for mixing these antioxidants with the polymeric material to give the composition. This composition is molded, and the antioxidants are then crosslinked with the polymer. They can be reacted with the polymer by, for example, irradiation with an ionizing radiation and/or using a chemical crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an antioxidant crosslinkable with a polymer and a polymer composition comprising the same.

[Prior Art] Phenol-based, amine-based, sulfur-containing, and phosphorus-containing antioxidants have been used to prevent deterioration of polymeric materials due to oxidation.

Amine-based antioxidants have limited uses because they are mostly polluting, and recently phenolic antioxidants, which are non-staining, have been widely used. Among phenolic antioxidants, hindered phenols are particularly important, such as n-octatene-3°,5'-di-t-butylphenylpropionate and tetrakis-[methylene-1
(3', 5° di-t-butyl-4-hydroquinophenyl) propionate comethane is a typical example.

In addition, for example, dilauryl diodibrobionate and 2
- Sulfur-containing antioxidants such as mercaptobenzimidazole, phosphorus-containing antioxidants such as triphenyl phosphite and tri(nonylphenyl) phosphite are known.

Sulfur-containing and phosphorus-containing antioxidants are usually rarely used alone, but are often used in combination with phenolic antioxidants. That is, by capturing the Rancal species generated during the oxidation process of polymeric materials with a phenolic antioxidant, and decomposing the peroxides generated in the process with a sulfur-containing or phosphorus-containing antioxidant, Techniques are used to synergistically enhance the antioxidant effect.

However, these antioxidants are generally used only after being physically dispersed in the formulation by a kneading operation. Therefore, during long-term use, especially under high-temperature conditions, antioxidants migrate to the product surface and precipitate (
There are drawbacks such as so-called blooming) and further volatilization and transpiration, which significantly reduces the antioxidant effect and significantly impairs the appearance of the product.

In order to solve this problem, antioxidants having carbon-carbon double bonds in their molecules so as to be crosslinkable to polymers have been developed. For example, there are known reactive antioxidants having a hindered phenol group and a vinyloxy group, or a hindered phenol group and a vinyl group in the same molecule, as shown by the formula ("Antioxidant Handbook", 1st edition). , pp. 3-4, Taiseisha).

Further, Japanese Patent Application Laid-open No. 153898/1989 discloses a method for producing a copolymer containing a phenolic antioxidant.

[Problems to be Solved by the Invention] In recent years, there has been an ever-increasing demand for polymer materials to be used at higher temperatures and for longer periods of time. As a means to meet this requirement, a method is known in which a phenolic antioxidant is used in combination with an sulfur-containing or phosphorus-containing antioxidant.

In this case, if the above-mentioned reactive phenolic antioxidant is used in combination with a sulfur-containing or phosphorus-containing antioxidant,
Blooming and dissipation of phenolic antioxidants can be prevented. However, similar to phenolic antioxidants, sulfur-containing or phosphorus-containing antioxidants also have the problem of blooming and dissipation from polymer compositions when used at high temperatures for long periods of time, and improvements are required.

The present invention aims to provide an antioxidant having a sufficient antioxidant effect and excellent blooming resistance, and a polymer composition containing the same.

[Means for Solving Problem 1] The problem described above is based on the general formula: %Formula %U, where R, R, and R1 represent an organic group, and at least one is a group having a carbon-carbon unsaturated bond. and X
≧0. However, when x=0, at least one of R1 and R2 is a group having a carbon-carbon unsaturated bond. This problem can be solved by using an antioxidant consisting of a thioether compound shown in .

In the above formula, when X>0, R, R, and R
at least one of 2, R1 and R7 if x=0
[at least] is an organic group having a carbon-carbon unsaturated bond. Examples include a vinyl group, an allyl group, an allyloxy group, an acryloxy group, and a methacryloxy group. Also, it is an aliphatic group] and is not limited to J, but may be an organic group containing an aromatic ring or the like. By introducing such a group into the molecule, crosslinking with the polymer becomes possible, which solves the problem of antioxidant blooming and dissipation caused by long-term use at high temperatures. Furthermore, by combined use with a phenolic antioxidant or a reactive phenolic antioxidant, a polymer composition having a high degree of heat resistance can be obtained. As the other organic group having no carbon-carbon unsaturated bond, for example, a saturated aliphatic group having 1 to 18 carbon atoms is preferable.

The antioxidant of the present invention can be used, for example, in the presence of a tertiary amine, such as thiogentanol (HOCHffiCH).

SCH,C)(,OH) and unsaturated carboxylic acid
Hydrochloric acid of a tertiary amine produced by reacting a compound or a mixture of an acid halide of an unsaturated carboxylic acid and an acid halide of a saturated carboxylic acid in a solvent such as hexane, petroleum ether, or methyl edyl ketone. After separating the salt by a suitable method, the reaction product obtained can be concentrated.

Examples of acid halides of unsaturated carboxylic acids include oleic acid chloride, undecenoyl chloride, acrylic acid chloride, methacrylic acid chloride, and crotonic acid chloride. Such acid halides can be used alone or in mixtures. Examples of acid halides of saturated carboxylic acids include acid chlorides such as valmitic acid and stearic acid, and can be appropriately selected as required.

In the aforementioned method, for example, 4,4'-thionephenol (HO-C) is used instead of thiogentanol.

H4S C6H50H), 1,1°-thione (2-naphthol), thione salicylic acid [S (H0CsHs
COOHoe] etc., a thioether compound having an organic group containing an aromatic ring can be obtained.

Also, instead of the starting material and 17 thiodialcohol,
For example, thiodiglycolic acid (S(CHyCOOH)z)
, thiodipropionic acid (S(CH2CH, Co o H
), ), thionsuccinic acid (S(CH2CH,CH.

The antioxidant of the present invention may also be obtained by using an acid halide of thiodicarboxylic acid such as COOH)t) and reacting it with an unsaturated alcohol or a mixture of an unsaturated alcohol and a saturated alcohol. good.

The number of thioether groups contained in the antioxidant of the present invention is not limited to one. Therefore, from a diol having multiple thioether groups in the molecule or a dicarboxylic acid having multiple nioether groups in the molecule, to an organic group having multiple thioether groups in the molecule and at least one carbon-carbon unsaturated bond. You may synthesize a thioether compound with

The reactive antioxidant thus obtained is 0.1 to 20% by weight, preferably 0.2 to 20% by weight, based on the polymer material.
A polymer composition is obtained by blending 10% by weight into a polymer material.

Preferably, it is blended in combination with an appropriate amount of a phenolic antioxidant.

The types of polymer materials are not particularly limited, and include polyolefins such as polyethylene, ethylene copolymers, polyvinyl chloride, and Bois vinyl acetate, thermoplastic elastomers such as polyesters, polyamides, polyurethanes, and polystyrenes, and ethylene. - Rubbers such as propylene copolymers and butyl rubber can be mentioned as examples. In addition, appropriate amounts of compounding agents that are commonly added to these, such as flame retardants, fillers, lubricants, foaming agents, reinforcing materials, and processing stabilizers, may be added. Furthermore, it is also possible to add known sulfur-containing or phosphorus-containing antioxidants.

The above-mentioned antioxidant is mixed with a polymeric material using a commonly used mixer, such as an open roll mixer, a Banbury mixer, or a multi-shaft mixer (5) to obtain a polymeric composition.

After shaping the resulting polymeric composition, the antioxidant is crosslinked with the polymer. In this case, the antioxidant is reacted with the polymer using known methods, such as irradiation with ionizing radiation or a chemical crosslinking agent or a combination of both. This operation can be carried out by methods and devices known per se and commonly used. The irradiation dose of ionizing radiation can be set in the range of 1 to 50 Mrad. Chemical crosslinking agents may also be used in conventional amounts of known crosslinking agents commonly used for crosslinking polymers. For example, crosslinking agents such as organic peroquinide, polyamine, sulfur, and oximes can be used.

Alternatively, the antioxidant may be melt-mixed into the polymeric material I' and simultaneously crosslinked in the presence of an organic peroxide using a single-screw or multi-screw mixer.

[Example] The present invention will be explained in more detail with reference to the following example. Note that these Examples do not limit the present invention.

Example 1 In a 1 liter three-necked reaction vessel equipped with a stirrer, a dropping funnel and a cooling tube, purified N,N diethylaniline (61 g) and 2,2'-thiodietanol (31 g) were purified by distillation.
A solution of undecenoyl chloride (100zQ) purified by distillation was introduced into the dropping funnel.
A methyl ethyl ketone (100 red) solution of g) was added.

The reaction vessel was cooled in a water bath, and a solution of undecenoyl chloride in methyl ethyl ketone was added dropwise while stirring. After the dropwise addition was completed, the mixture was stirred at 60°C for 8 hours. After cooling to room temperature, the reaction mixture was poured into 1 g of water to separate the organic layer, and the aqueous layer was extracted three times with 100 m of petroleum ether. % sodium bicarbonate aqueous solution and then saturated saline. After washing,
Filter and concentrate to obtain pale yellow oily thioether compound 19
I got 89.

Low density polyethylene (melt index 203) 10
To 1 part of 0 weight, 1 part of 4 parts of the thioether compound previously obtained, tetrakis-methylene-5 (3°, 5°-di-t-
2 parts by weight of butyl-4'-hydroxyphenyl)propionate comethane were blended and mixed in an oven roll mixer at 120°C to prepare a polyethylone composition. 1
Using a heat press machine at 40°C for 10 minutes, the resulting composition was pressed to a thickness of 1.0! It was molded into a ff notebook. This was crosslinked by irradiating 15 Mrad of electron beam with an accelerating voltage of 1 MeV. The gel fraction of the sheet by quinone extraction is 5
It was 3%.

The obtained sheet was kept in a constant temperature bath at 180°C for 30 days (72
0 hours) and allowed to age, and the tensile strength and elongation at break were measured. The tensile strength at break and elongation at break of the sheet before aging were measured, and the formula 2 Retention = Xa/XoX 100 (%) "In the formula, Xa represents the tensile strength or elongation after aging, and Xo represents the tensile strength or elongation before aging. The retention rate was calculated from this.

As a result, the tensile strength retention rate after aging was 97%, and the elongation retention rate was 62%.

Example 2 Ethyl 1 non-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content,
10 parts by weight of the thioether compound prepared according to the procedure shown in Example 1 and 1 part of 2 ml of n-occudenol-3°5°-di-t-butylphenylpropionate were added to 100 weight US (19%), and the mixture was heated in an oven roll at 100°C. An EEA composition was prepared by mixing with a mixer. 130℃,
The obtained composition was molded into a sheet having a thickness of 1.0 x m using a hot press machine under conditions of 10 minutes. Accelerating voltage IM
This was crosslinked by irradiation with an eV electron beam of 20 Mrad.

The gel fraction of the sheet after xylene extraction was 58%.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 91% and the retention rate of elongation was 8.
It was 6%.

Example 3 According to the procedure set forth in Example 1, a mixture of methacrylic acid chloride and stearic acid chloride in a molar ratio of 1:1 was reacted with thiodisalicylic acid to obtain a white ant-like thioether compound.

To 100 parts by weight of ethylene-vinyl acetate copolymer (EVA, melt index: 20, vinyl acetate content [11%)], 10 parts by weight of the above thioether compound, n~octadecyl-3',5''-di-t-butyl An EVA composition was prepared by blending 5 parts by weight of phenylpropionate and mixing in an oven roll mixer at 120°C.140°C, 1
The obtained composition was molded into a sheet having a thickness of 1 and Q zy using a hot press machine under conditions of 0 minutes. Accelerating voltage IM
This was crosslinked by irradiation with an eV electron beam of 20 Mrad.

The gel fraction of the sheet after xylene extraction was 56%.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 76%, and the retention rate of elongation was 6%.
It was 6%.

Comparative Example 1 Low density polyethylene (melt index = 03) 10
0 parts by weight, tetrakis-[methylene-5-(3',5
1 part by weight of di-t-butyl-4'-hydroxyphenyl)propionate comethane was blended and mixed in an oven roll mixer at 120°C to prepare a polyethylene composition. The obtained composition was formed into a sheet having a thickness of I and Oxw using a heat press machine at 140° C. for 10 minutes. Acceleration voltage IMeV (7) i-contact beam 15 Mrad
This was crosslinked by irradiation. The gel fraction of the sheet after xylene extraction was 59%.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 2% and the retention rate of elongation was 1%.
Met.

Comparative Example 2 Ethylene-ethyl acrylate copolymer (EEA1 melt index: 0.7, ethyl acrylate content: 1
Distearylthiodipropionate (S(CHzCHtCO
tC1sHs7)t)l 0 parts by weight, 2 parts by weight of tetrakis-[methylene-5-(3',5'-di-t-butyl-4°-hydroquinphenyl)propionate comethane were blended, and the mixture was heated at 100°C. The EEA composition was prepared by mixing in an oven roll mixer.

The obtained composition was molded into a sheet having a thickness of 1.0xx using a heat press machine at 120° C. for 10 minutes. A 20 Mrad electron beam with an accelerating voltage of IMeV was irradiated to crosslink this. The gel fraction of the sheet after xylene extraction was 52%.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 48%, and the retention rate of elongation was 1.
It was 1%.

Comparative Example 3 Ethylene-ethyl acrylate copolymer (EEA1 melt index = 0.7, ethyl acrylate included!: 1
9%) 100 parts by weight, 5 parts by weight of distearyl thiodipropionate, n-year-old tadecyl-3', 5'-di-t
- Blending 1 part by weight of butylphenylpropionate,
An EEA composition was prepared by mixing in an oven roll mixer at 00°C.

The obtained composition was molded into a sheet having a thickness of 1.0 mm using a heat press machine at 120.degree. C. for 10 minutes. This was crosslinked by irradiation with an electron beam of 20 Mrad at an accelerating voltage of I MeV. The gel fraction of sorting by xylene extraction is 5
It was 6%.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 43% and the retention rate of elongation was 6.
%Met.

Comparative example 4 Low density polyethylene (melt index 20.

3) 1 part by weight of acrylic ester of 3.5-di-t-butyl-4 hydroxyalcohol was added to 100 parts by weight and mixed in an oven roll mixer at 120°C to prepare a polyethylene composition.

The obtained composition was molded into a sheet having a thickness of 10 ytx using a heat press machine at 140° C. for 10 minutes. This was crosslinked by irradiation with an electron beam of 15 Mrad at an accelerating voltage of I MeV. The gel fraction of the sheet after xylene extraction is 47%.
Met.

As a result of carrying out an aging test according to the procedure shown in Example 1, the retention rate of tensile strength after aging was 2% and the retention rate of elongation was 1%.
Met.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain an antioxidant whose antioxidant effect is less reduced due to blooming and dissipation under high temperature and long-term conditions, and which is less likely to reduce the antioxidant effect than other antioxidants. A polymer composition having a high degree of heat resistance can be obtained by using an agent, especially a phenolic antioxidant, preferably a reactive phenolic antioxidant.

Patent applicant Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] 1. General formula: R_1-S-(R-S)x-R_2 [wherein R, R_1 and R_2 represent an organic group, and at least one has a carbon-carbon unsaturated bond group, and x≧0. However, when x=0, R_1 and R
At least one of _2 is a group having a carbon-carbon unsaturated bond. ] An antioxidant consisting of a thioether compound represented by the following. 2. The thioether compound according to claim 1 in an amount of 0.1 to 20
% by weight, wherein the thioether compound is crosslinked with a polymer.