JP2969705B2 - 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] To prevent deterioration of a polymer material due to oxidation, amine-based, phenol-based, sulfur-containing, and phosphorus-containing antioxidants have been conventionally used.

Most of amine-based antioxidants are contaminants, so their applications are limited. Recently, non-stainable phenol-based antioxidants are often used. Among phenolic antioxidants, hindered phenols are particularly important. For example, n-octadecyl-3 ', 5'-di-t-butylphenylpropionate and 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-mercaptobenzimitazole, and phosphorus-containing antioxidants such as triphenyl phosphite and trinonylphenyl phosphite are known. I have.

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 supplemented with a phenolic antioxidant, and the peroxide generated in the process is decomposed with a sulfur-containing or phosphorus-containing antioxidant, thereby synergistically. A technique for increasing the antioxidant effect is used.

However, these antioxidants are generally used merely by physically dispersing them in a compound by a kneading operation, and therefore, they are oxidized especially during prolonged use under high temperature conditions. There is a drawback that the inhibitor migrates and precipitates (so-called blooming) on the product surface, and furthermore, volatilizes and evaporates to significantly reduce the antioxidant effect.

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: Or the formula: And a reactive antioxidant having a hindered phenol group and an acrylic group or a hindered phenol group and a vinyl group in the same molecule ("Antioxidant Handbook", 1st edition, 3 to 3). 4, Taiseisha).

JP-A-54-153896 discloses a method for producing a copolymer containing a phenolic reactive aging inhibitor.

[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 the following formula: [Wherein, R ₁ , R ₂ and R ₃ represent an organic group, and at least 1
One is a group having a carbon-carbon unsaturated bond. ] Can be solved by using an antioxidant consisting of a phosphorus compound represented by the following formula:

In the above formula, at least one of R ₁ , R ₂ and R ₃ is a group having a carbon-carbon unsaturated bond, and examples thereof include an allyloxy group, an acryloxy group, a methacryloxy group, and a vinyl group. . By introducing such a group into the molecule, crosslinking with the polymer becomes possible, and blooming and dissipation of the antioxidant can be significantly reduced. Other organic groups include those having 1 to 18 carbon atoms.
Are preferred.

The antioxidant of the present invention can be obtained, for example, in a solvent such as hexane or petroleum ether, in the presence of a tertiary amine, by adding phosphorus trihydrochloride to an unsaturated alcohol or a mixture of an unsaturated alcohol and a saturated alcohol, or an unsaturated alcohol. After reacting with a mixture of an alcohol and a phenol derivative to separate the tertiary amine hydrochloride by an appropriate method, the obtained reaction product can be obtained by concentration.

As the unsaturated alcohol, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, allyl alcohol, trimethylolpropane dimethacrylate, pentaerythritol triacrylate, glycerin monoallyl ether,
Cinnamyl alcohol and the like can be mentioned as examples.

Examples of the saturated alcohol include n-octanol, n-nonanol, dodecanol, ethylene glycols, and benzyl alcohol. Examples of the phenol derivative include phenol and monononylphenol. These compounds are appropriately selected as needed, and used alone or as a mixture.

The reactive antioxidant thus obtained is blended with the polymer material in an amount of 0.1 to 20% by weight, preferably 0.5 to 10% by weight, based on the 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, and thermoplastic elastomers such as olefin, polyester, polyamide, polyurethane, and polystyrene are used. And rubbers such as ethylene-propylene copolymer and butyl rubber. In addition, compounding agents usually compounded in these,
For example, an appropriate amount of a processing stabilizer, a lubricant, a filler, a reinforcing agent, a flame retardant, a foaming agent and the like may be blended. 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 to 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 a range of 1 to 5 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 (44.7 g), hydroxyethyl acrylate (7.2 g), and a 1-liter three-necked reaction vessel equipped with a stirrer, a dropping funnel, and a condenser.
Monononylphenol (14.7g) petroleum ether (100m
l) The solution was introduced, and a solution of distilled and purified phosphorus trichloride (13.7 g) in petroleum ether (50 ml) was placed in the dropping funnel. The reaction vessel was cooled in a cold water bath, and a petroleum ether solution of phosphorus trichloride was dropped into the reaction vessel with stirring. After completion of the dropwise addition, the mixture was refluxed at 50 ° C. for 1 hour with stirring. After cooling to room temperature, the resulting N, N-diethylaniline hydrochloride in suspension was filtered off and washed with petroleum ether. The washing solution and the filtration were combined into one, and this was concentrated to obtain a phosphorus compound (52 g).

Low density polyethylene (melt index: 0.3) 100
3 parts by weight of the phosphorus compound previously obtained was added to 3 parts by weight of tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4').
-Hydroxyphenyl) propionate] methane (1 part by weight) was mixed 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. An electron beam with a processing voltage of 1 MeV was irradiated at 15 Mrad to crosslink. The gel fraction of the sheet by xylene extraction was 55%.

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 92%, and the retention of elongation was 76%.

Example 2 Ethylene-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content: 19%) 1
To 00 parts by weight, 4 parts by weight of the phosphorus compound prepared according to the procedure shown in Example 1, n-octadecyl-3 ', 5'-di-
1 part by weight of t-butylphenylpropionate is blended,
The EEA composition was prepared by mixing with an open roll mixer at 100 ° C. Used in a heat press at 120 ° C for 10 minutes,
The obtained composition was formed into a sheet having a thickness of 1.0 mm. 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 62%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 92%, and the retention of elongation was 81.
%Met.

Example 3 According to the procedure described in Example 1, a mixture of hydroxyethyl acrylate and n-dodecyl alcohol having a molar ratio of 1: 2 was reacted with phosphorus trichloride to obtain a phosphorus compound (yield: 81%). .

To 100 parts by weight of an ethylene-vinyl acetate copolymer (EVA, melt index: 2.0, vinyl acetate content: 11%), 2 parts by weight of the above phosphorus compound, n-octadecyl-3 ', 5'-di-t-butylphenylpropionate 0.5 parts by weight of onate 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 120 ° 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 in xylene extraction was 50%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 88%, and the retention of elongation was 68.
%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%) 100
4 parts by weight of diphenyldecyl phosphite as a phosphorus compound and tetrakis [methylene-3- (3 ′, 5 ′)
-Di-t-butyl-4'hydroxyphenyl) propionate] methane (1 part by weight) was mixed with an open roll mixer at 100 ° C to prepare an EEA composition. 120 ℃,
The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press device under the conditions of 10 minutes. An electron beam with an acceleration voltage of 1 MeV
This was crosslinked by irradiation with 0 Mrad. The gel fraction of the sheet by xylene extraction was 48%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 63%, and the retention of elongation was 16%.
%Met.

Comparative Example 3 Ethylene-ethyl acrylate copolymer (EEA, melt index: 0.7, ethyl acrylate content: 19%) 100
2 parts by weight of dilauryl thiodipropionate,
One part by weight of n-octadecyl-3 ', 5'-di-t-butylphenylpropionate was blended and mixed with an open roll mixer at 100 ° C to prepare an EEA composition. 120 ℃,
The obtained composition was formed into a sheet having a thickness of 1.0 mm using a hot press device under the conditions of 10 minutes. An electron beam with an acceleration voltage of 1 MeV
This was crosslinked by irradiation with 0 Mrad. The gel fraction of the sheet by xylene extraction was 43%.

As a result of performing an aging test according to the procedure shown in Example 1, the retention of tensile strength after aging was 27%, and the retention of elongation was 5%.
%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.

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Claims (2)

(57) [Claims] 1. An antioxidant comprising a mixture of phosphorus compounds obtained by reacting phosphorus trichloride with a mixture of an unsaturated alcohol and a saturated alcohol or a mixture of an unsaturated alcohol and a phenol derivative. 2. A mixture of the phosphorus compound according to claim 1 in an amount of 0.1%.
A polymer composition comprising about 20% by weight of a mixture of the phosphorus compound and a polymer.