JP2903639B2 - Antioxidant and polymer composition containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polymer and a crosslinkable antioxidant and a polymer composition comprising the same.

[Prior Art] In order to prevent deterioration of a polymer material due to oxidation, phenol-based, amine-based, sulfur-containing, and phosphorus-containing antioxidants have been conventionally used.

Most of the amine-based antioxidants are contaminants, so their applications are limited. Recently, non-stainable phenol-based antioxidants are frequently used. Among phenolic antioxidants, hindered phenols are particularly important,
For example, n-octadecyl-3 ', 5'-di-t-butylphenylpropionate or tetrakis- [methylene-3
-(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane is a typical example.

In addition, for example, sulfur-containing antioxidants such as dilaurylthiodipropionate and 2-mercaptobenzimidazole, and phosphorus-containing antioxidants such as triphenyl phosphite and tri (nonylphenyl) phosphite are known. I have.

Usually, sulfur-containing and phosphorus-containing antioxidants are rarely used alone, and are often used in combination with phenolic antioxidants. In other words, the radical species generated in the oxidation process of the polymer material are captured by a phenolic antioxidant, and the peroxide that generates the process is decomposed by a sulfur-containing or phosphorus-containing antioxidant, thereby synergistically. A technique for increasing the antioxidant effect is used.

However, these antioxidants are generally merely used physically dispersed in the compound by a kneading operation. For this reason, the antioxidant migrates and precipitates (so-called blooming) on the product surface, especially during long-term use under high temperature conditions, and furthermore, volatilization and evaporation evaporates, and the antioxidant effect is remarkably reduced. There is the disadvantage that the appearance is significantly impaired.

In order to solve this problem, antioxidants having a carbon-carbon double bond in the molecule so as to be crosslinkable with a polymer have been developed. For example, the formula: And a reactive antioxidant having a hindered phenol group and a vinyloxy group or a hindered phenol group and a vinyl group in the same molecule ("Antioxidant Handbook", 1st edition, 3 4, Taiseisha).

JP-A-54-153896 discloses a method for producing a copolymer containing a phenolic antioxidant.

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

In this case, blooming and dissipation of the phenolic antioxidant can be prevented by using the above-mentioned reactive phenolic antioxidant in combination with a sulfur-containing or phosphorus-containing antioxidant. However, sulfur-containing or phosphorus-containing antioxidants, like the phenolic antioxidants, have problems of blooming and dissipation from the polymer composition due to long-term use at high temperatures, and thus improvements are required.

An object of the present invention is to provide an antioxidant having a sufficient antioxidant effect and having excellent blooming resistance, and a polymer composition containing the same.

[Means for Solving the Problems] The above-mentioned problems are represented by a general formula: R ₁ -S- (RS) x-R ₂ [wherein, R, R ₁ and R ₂ represent an organic group and at least 1
One is a hydrocarbon group having a vinyl group, an allyl group, an acryloyl group or a methacryloyl group, and x ≧ 0.
However, when x = 0, at least one of R ₁ and R ₂ is a hydrocarbon group having a vinyl group, an allyl group, an acryloyl group or a methacryloyl group. ] Can be solved by using an antioxidant consisting of a thioether compound represented by the following formula:

In the above formula, when x> 0, R, R ₁ and R ₂
Is an organic group having a carbon-carbon unsaturated bond when x = 0 and at least one of R ₁ and R ₂ when x = 0. Examples include vinyl, allyl, allyloxy, acryloxy, methacryloxy and the like. Further, the organic group is not limited to an aliphatic group, and 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, and blooming and dissipation of the antioxidant due to long-time use at high temperature can be solved. Furthermore, by the combined use with a phenolic antioxidant or a reactive phenolic antioxidant,
A polymer composition having high 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 may be, for example, an acid halide of thiodiethanol (HOCH ₂ CH ₂ SCH ₂ CH ₂ OH) and an unsaturated carboxylic acid, or an acid halide of an unsaturated carboxylic acid in the presence of a tertiary amine. Of tertiary amine hydrochloride by a suitable method after reacting the compound with a mixture of an acid halide and a saturated carboxylic acid in a solvent such as hexane, petroleum ether, or methyl ethyl ketone. The product can be obtained by concentration.

Examples of the acid halide of an unsaturated carboxylic acid include oleic acid chloride, undecenoyl chloride, acrylic acid chloride, methacrylic acid chloride, crotonic acid chloride and the like. Such acid halides can be used alone or as a mixture. Examples of the acid halide of the saturated carboxylic acid include acid chlorides such as palmitic acid and stearic acid, and can be appropriately selected as needed.

In the foregoing method, for example, instead of 4,4'-thiodiphenol thio diethanol _{(HO-C 6 H 4 -S} -C 6 H 4 -O
H), 1,1' thiodi (2-naphthol), the use of such thiodisalicylic acid _{[S (HO-C 6 H} 3 -COOH) 2], to obtain a thioether compound having an organic group containing an aromatic ring be able to.

Also, instead of thiodialcohol as starting material,
For example, thiodiglycolic acid (S (CH ₂ COOH) ₂ ), thiodipropionic acid (S (CH ₂ CH ₂ COOH) ₂ ), thiosuccinic acid (S (CH ₂ CH ₂ CH ₂ COOH) ₂ ), etc. The antioxidant of the present invention may be obtained by using an acid halide of thiodicarboxylic acid and reacting it with an unsaturated alcohol or a mixture of an unsaturated alcohol and a saturated alcohol.

The thioether group contained in the antioxidant of the present invention is not limited to one. Therefore, from a diol having a plurality of thioether groups in the molecule or a dicarboxylic acid having a plurality of thioether groups in the molecule, an organic group having a plurality of thioether groups in the molecule and having at least one carbon-carbon unsaturated bond May be synthesized.

The reactive antioxidant thus obtained is used in an amount of 0.1 to 20% by weight, preferably 0.2 to 10% by weight, based on the polymer material.
Is mixed with a polymer material to obtain a polymer composition. It is preferably used in combination with an appropriate amount of a phenolic antioxidant.

The type of the polymer material is not particularly limited, and polyolefins such as polyethylene, ethylene copolymer, polyvinyl chloride, and polyvinyl acetate; thermoplastic elastomers such as polyester, polyamide, polyurethane, and polystyrene; and ethylene. -Rubbers such as propylene copolymer and butyl rubber can be mentioned as examples.
Further, an appropriate amount of a compounding agent, such as a flame retardant, a filler, a lubricant, a foaming agent, a reinforcing material, and a processing stabilizer, which is usually compounded in these, may be added. Further, it is also possible to add a known sulfur-containing or phosphorus-containing antioxidant.

Mixers commonly used with the antioxidants, for example,
The polymer composition is obtained by mixing with a polymer material using an open roll mixer, a Banbury mixer, a multi-screw mixer, or the like.
After molding the obtained polymer composition, the antioxidant is crosslinked with the polymer. In this case, the antioxidant is reacted with the polymer in a known manner, for example by irradiation with ionizing radiation or a chemical crosslinking agent or 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. As the chemical crosslinking agent, a known crosslinking agent usually used for crosslinking a polymer may be used in a usual amount. For example, crosslinking agents such as organic peroxides, polyamines, sulfurs, and oximes can be used.

Alternatively, the antioxidant may be melt-mixed with the polymer material and crosslinked at the same time in the presence of an organic peroxide using a single-screw or multi-screw mixer.

[Examples] The present invention will be described more specifically by the following examples. Note that these examples do not limit the present invention.

Example 1 Distilled and purified N, N-diethylaniline (61 g), 2,2'-thiodiethanol (31 g) of methyl ethyl ketone (31 g) were placed in a 1-liter three-necked reaction vessel equipped with a stirrer, a dropping funnel and a condenser. (100 ml) solution, and a dropping funnel was charged with a solution of undecenoyl chloride (100 g) purified by distillation in methyl ethyl ketone (100 ml). The reaction vessel was cooled in a water bath, and a solution of undecenoyl chloride in methyl ethyl ketone was added dropwise with stirring. After completion of the dropwise addition, the mixture was stirred at 60 ° C. for 8 hours. After cooling to room temperature, the reaction mixture was poured into 1 water and the organic layer was separated.
Extracted times. The extracted petroleum ether layer and organic layer were combined into one, which was washed with a 5% aqueous sodium hydrogen carbonate solution and then with a saturated saline solution. After washing, filtration and concentration gave 198 g of a pale yellow oily thioether compound.

Low density polyethylene (melt index: 0.3) 100
4 parts by weight of the thioether compound obtained above and 2 parts by weight of tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane were added to The mixture was mixed with an open roll mixer at 120 ° C. to prepare a polyethylene composition. 140 ° C, 10
Using a hot press machine under the conditions of
It was formed into a 1.0 mm sheet. 15M electron beam with acceleration voltage of 1MeV
This was cross-linked by rad irradiation. The gel fraction of the sheet by xylene extraction was 53%.

The obtained sheet was left in a thermostat at 180 ° C. for 30 days (720 hours) to age, and the tensile strength at break and elongation at break were measured. The tensile strength at break and elongation at break of the sheet before aging were measured, and the following formula was used. . ] To calculate the retention.

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

Example 2 Ethylene-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content: 19%) 1
To 100 parts by weight, 10 parts by weight of the thioether compound prepared according to the procedure shown in Example 1, n-octadecyl-3 ',
2 parts by weight of 5'-di-t-butylphenylpropionate were blended and mixed with an open roll mixer at 100 ° C.
An EA composition was prepared. The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press at 130 ° C. for 10 minutes. The electron beam was irradiated at an acceleration voltage of 1 MeV for 20 Mrad to crosslink the electron beam. The gel fraction of the sheet by xylene extraction was 58%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 91%, and the retention of elongation was 86.
%Met.

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

100 parts by weight of an ethylene-vinyl acetate copolymer (EVA, melt index: 2.0, vinyl acetate content: 11%), 10 parts by weight of the above thioether compound, n-octadecyl-
5 parts by weight of 3 ′, 5′-di-t-butylphenylpropionate were blended and mixed with an open roll mixer at 120 ° C. to prepare an EVA composition. The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press at 140 ° C. for 10 minutes. The electron beam was irradiated at an acceleration voltage of 1 MeV for 20 Mrad to crosslink the electron beam. The gel fraction of the sheet by xylene extraction is 56
%Met.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 76%, and the retention of elongation was 66.
%Met.

Comparative Example 1 Low-density polyethylene (melt index: 0.3) 100
In parts by weight, tetrakis- [methylene-3- (3'5'-
[Di-t-butyl-4'-hydroxyphenyl) propionate] methane was mixed in an amount of 1 part by weight and mixed with an open roll mixer at 120 ° C to prepare a polyethylene composition. The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press at 140 ° C. for 10 minutes. Acceleration voltage 1Me
This was cross-linked by irradiating 15 Mrad of V electron beam. The gel fraction of the sheet by xylene extraction was 59%.

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

Comparative Example 2 Ethylene-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content: 19%) 1
To 100 parts by weight, 10 parts by weight of distearylthiodipropionate (S (CH ₂ CH ₂ CO ₂ C ₁₈ H ₃₇ ) ₂ ) as a thioether compound, tetrakis- [methylene-3- (3 ′, 5′-di-)
[t-butyl-4'-hydroxyphenyl) propionate] methane (2 parts by weight) was mixed and mixed with an open roll mixer at 100 ° C to prepare an EEA composition. Using a hot press at 120 ° C for 10 minutes, the thickness of the obtained composition was 1.
It was formed into a 0 mm sheet. 20Mra electron beam with acceleration voltage 1MeV
This was crosslinked by irradiation. The gel fraction of the sheet by xylene extraction was 52%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 48%, and the retention of elongation was 11%.
%Met.

Comparative Example 3 Ethylene-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content: 19%) 1
5 parts by weight of distearyl thiodipropionate and 1 part by weight of n-octadecyl-3 ', 5'-di-t-butylphenylpropionate were mixed with 00 parts by weight, and mixed with an open roll mixer at 100 ° C. An EEA composition was prepared. 120
The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press at 10 ° C. for 10 minutes. This was cross-linked by irradiating it with 20 Mrad of an electron beam having an acceleration voltage of 1 MeV. The gel fraction of the sheet by xylene extraction was 56%.

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

Comparative Example 4 Low-density polyethylene (melt index: 0.3) 100
1 part by weight of an acrylic acid ester of 3,5-di-t-butyl-4-hydroxy alcohol was mixed with
Was mixed with an open roll mixer to prepare a polyethylene composition. The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press at 140 ° C. for 10 minutes. This was cross-linked by irradiating an electron beam with an acceleration voltage of 1 MeV at 15 Mrad. The gel fraction of the sheet by xylene extraction was 47%.

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

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain an antioxidant having a small decrease in the antioxidant effect due to blooming and dissipation under high temperature and long time conditions,
By using other antioxidants, particularly phenolic antioxidants, preferably reactive phenolic antioxidants, a polymer composition having high heat resistance can be obtained.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) C09K 15/10-15/12 C08K 5/36 C08L 101/00 WPI / L (QUESTEL) EPAT (QUESTEL)

Claims (2)

(57) [Claims] 1. A compound represented by the general formula: R ₁ -S- (RS) _x -R _{2 wherein} R, R ₁ and R ₂ represent an organic group, and at least 1
One is a hydrocarbon group having a vinyl group, an allyl group, an acryloyl group or a methacryloyl group, and x ≧ 0.
However, when x = 0, at least one of R ₁ and R ₂ is a hydrocarbon group having a vinyl group, an allyl group, an acryloyl group or a methacryloyl group. ] The antioxidant which consists of a thioether compound shown by these. 2. The thioether compound according to claim 1,
A polymer composition comprising about 20% by weight of the thioether compound and a polymer.