JP2808719B2 - Reactive antioxidant and polymer composition containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an antioxidant having a double bond crosslinkable with a polymer in a molecule, and a polymer composition containing the same.

[Prior Art] Antioxidants such as amine-based and phenol-based antioxidants have been conventionally used to prevent deterioration of polymer materials due to oxidation. Most of amine-based antioxidants are contaminants, so their applications are limited. Recently, phenol-based antioxidants have been widely used.

Examples of phenolic antioxidants include n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-
t-butylphenyl) propionate (trade name: Irganox 1076, manufactured by Ciba Geigy) or tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] Methane (trade name: Irganox 1010, manufactured by Ciba-Geigy) or the like is used.

However, these antioxidants are merely physically mixed into the formulation by a kneading operation,
Therefore, when the compound comes into contact with an organic solvent or water, the antioxidant is easily extracted, and its effect is extremely reduced. Also,
During use for a long period of time, the antioxidant precipitates on the product surface, so-called blooming occurs, which has the disadvantage that the antioxidant effect is reduced and the surroundings are contaminated.

In order to solve these problems, recently, a reactive antioxidant having a double bond capable of crosslinking with a polymer in a molecule has been used. Typical examples of such antioxidants are, for example, those of the formula: Or the formula: ("Antioxidant Handbook", 1st edition, 3-4 pages, 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] Conventionally, this kind of reactive antioxidant has a drawback that it is excellent in extraction resistance but cannot obtain a sufficient antioxidant effect. An object of the present invention is to provide a polymer composition containing an antioxidant which has a sufficient antioxidant effect and is excellent in extraction resistance and blooming resistance.

[Means for Solving the Problems] The above-mentioned problems are represented by the following formula: [Wherein, R ₁ and R ₂ are an alkyl group having 1 to 4 carbon atoms, R ₃ and R ₄ are a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₅
Is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, l is a number of 0 to 3, m is 1 to 15
And n represents a number from 0 to 15, and the sum of m + n is from 5 to 30. ] Can be solved by using a phenolic compound represented by the following formula as an antioxidant.

The phenolic compound has the formula: [Wherein, R ₁ , R ₂ and 1 are as defined above. ] Formula of the alcohol represented by the formula: [R ₃ , R ₄ and R ₅ and m and n are as defined above, and the sum of m + n is 5 to 30. And the unsaturated fatty acid chloride represented by the following formula:

In the above formula, R ₁ and R ₂ are an alkyl group having 1 to 4 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl group, etc., and preferably a t-butyl group. is there. Also, R ₃ and R ₄
May also be an alkyl group having 1 to 4 carbon atoms. In addition, R ₃
And R ₄ may be a hydrogen atom. R ₅ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

The alcohols of the formula (II) used for the preparation of the phenolic compounds according to the invention are known compounds, for example 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 3,5-dibenzyl alcohol -T-butyl-4-hydroxyphenol, 3,5-di-t-butyl-4-hydroxyphenethyl alcohol and the like.

The acid chloride represented by the formula (III) and used for preparing the phenolic compound is also a known compound. The number of carbon atoms contained in the main chain is preferably 5 or more, and if the number is less than this, a sufficient antioxidant effect cannot be obtained. Examples of such acid chlorides include oleic acid chloride, ercoyl chloride, linoleic acid chloride, linolenic acid chloride and the like.

Typical examples of the phenolic compound thus obtained are 3,5-di-t-butyl-4-hydroxybenzyl oleate, 3,5-di-t-butyl-4-hydroxybenzyl ercolate And so on.

The phenolic compound 0.1-2 obtained as described above
0% by weight, preferably 0.5 to 10% by weight is added to a polymer material as an antioxidant to obtain a polymer composition. The type of the polymer material is not particularly limited, and may be any polymer that can react with the phenolic compound. Representative examples include polyolefin, polyester elastomer, polyolefin elastomer, polyurethane, ethylene propylene rubber, and the like. Also,
Such a polymer composition may contain an appropriate amount of a compounding agent usually compounded, for example, a stabilizer, a lubricant, a filler, a reinforcing agent, a flame retardant and the like.

A known method for the polymer composition thus obtained,
For example, the reactive antioxidant is reacted with the polymer by irradiation with 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. Radiation dose is 0.1-100Mrad (1-1000KGy), preferably 1-5
It is 0Mrad (10-500KGy). As the chemical crosslinking agent, a known crosslinking agent usually used for crosslinking a polymer may be used. For example, an organic peroxide-based, polyamine-based, sulfur-based, or oxime-based crosslinking agent may be used, but an organic peroxide-based crosslinking agent is preferred.

[Action] Among phenolic antioxidants, those having an antioxidant function are hydroxyl groups bonded to a benzene ring,
A radical generated by the oxidation is captured and stabilized by the radical, thereby exhibiting an antioxidant effect. In the reactive antioxidant used in the present invention, a hydroxyl group bonded to a benzene ring has an antioxidant function, but its antioxidant effect varies greatly depending on the molecular structure. Conventional reactive antioxidants have insufficient antioxidant effects, but in the present invention, by increasing the molecular length of unsaturated fatty acids in phenolic compounds to some extent, reactive antioxidants having a sufficient antioxidant effect are obtained. It was found to be an agent.
The reason why the antioxidant effect is improved when the molecular length is increased is unknown, but an antioxidant having a long molecular length can move around the composition in a relatively wide range even when bound to a polymer. It is speculated that this may increase the chance of capturing radicals that cause deterioration.

Further, this reactive antioxidant has a double bond in the molecule, and the double bond reacts with the polymer by a known crosslinking method, for example, irradiation or a chemical crosslinking agent, so that the reactive antioxidant is bonded. Excellent extractability and blooming resistance.

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

Preparation of reactive antioxidant (a) 150 g of 3,5-di-t-butyl-4-hydroxybenzyl alcohol was introduced into a reaction vessel, and then 230 g of oleic acid chloride was introduced and heated to 60 ° C. for 1 hour. Reacted. The obtained reaction product was washed with hydrochloric acid, dehydrated with sodium sulfate, dried under reduced pressure for 30 minutes, and purified to obtain 300 g of a reactive antioxidant A.

(B) According to the procedure shown in (a) above, 3,5-di-t
28 g of -butyl-4-hydroxybenzyl alcohol and 70 g of linoleic acid chloride were reacted at 60 ° C. for 1 hour to obtain 92 g of a reactive antioxidant B.

(C) According to the procedure shown in the preceding section (a), 3,5-di-t
25 g of -butyl-4-hydroxyphenethyl alcohol and 63 g of linolenic chloride were reacted at 60 ° C. for 1 hour to obtain 80 g of a reactive antioxidant C.

Example 1 Low-density polyethylene (melt index: 1.5) 100
1 part by weight of the reactive antioxidant A obtained above was added to 1 part by weight, and the mixture was roll-kneaded at 120 ° C. to prepare a polyethylene compound. The obtained mixture was pressed under the conditions of 130 ° C. × 10 minutes to produce a sheet having a thickness of 1 mm. Bande with an acceleration voltage of 1 MeV
The polyethylene formulation was crosslinked using a graphic electron accelerator. The amount of electron beam irradiation was 25 Mrad. The following test was performed using the obtained sample.

Example 2 100 parts by weight of ethylene vinyl acetate copolymer (EVA, melt index: 0.7) were mixed with 2 parts by weight of a reactive antioxidant A and 1 part by weight of dicumyl peroxide as a cross-linking agent, and the mixture was roll-kneaded at 120 ° C. and EVA was performed. A formulation was prepared. 160
The EVA formulation was crosslinked using a press at 30 ° C. for 30 minutes. The following test was performed using the obtained sample.

Example 3 An EVA composition was prepared by repeating Example 1 except that 100 parts by weight of EVA and 2 parts by weight of the reactive antioxidant B were used, and the composition obtained by electron beam irradiation was crosslinked. The electron beam irradiation amount was 15 Mrad. The following test was performed using the obtained sample.

Example 4 An EEA formulation was prepared by repeating Example 1 except that 100 parts by weight of an ethylene acrylate copolymer (EEA, melt index: 2.0) and 2 parts by weight of a reactive antioxidant B were used and obtained by electron beam irradiation. The resulting formulation was crosslinked. The amount of electron beam irradiation was 25 Mrad. The following test was performed using the obtained sample.

Example 5 100 parts by weight of EEA was mixed with 4 parts by weight of a reactive antioxidant C and 1 part by weight of dicumyl peroxide as a crosslinking agent, and kneaded with a roll to prepare an EEA compound. The mixture was irradiated with an electron beam according to the procedure shown in Example 1 and crosslinked. The electron beam irradiation amount was 15 Mrad. The following test was performed using the obtained sample.

Comparative Examples 1-4 As comparative examples, (3,5-di-t-butyl-4-hydroxybenzyl) acrylate and n-octadecyl-
3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate (trade name: Irganox 107
6, manufactured by Ciba-Geigy Co., Ltd.), and each composition was prepared by roll kneading according to the composition chart shown in Table 1. In Comparative Examples 1, 3 and 4, the composition obtained by irradiating an electron beam according to the procedure shown in Example 1 was crosslinked (electron beam irradiation amount: 15 to 25 Mrad). In Comparative Example 2, 160 ° C.
The resulting formulation was crosslinked using a press under conditions of 30 minutes. The following test was carried out using the sample thus obtained.

Test 1. Aging test To evaluate the effect of the antioxidant contained in the sample, an aging test was performed according to JISK7212. From each sample
A JIS No. 2 test piece having a thickness of 1 mm specified in JISK7113 was used as a punching test sample. The tensile strength and elongation of the sample before aging at a tensile speed of 500 mm / min using a tensile tester and the sample after aging by heating at 160 ° C. for 168 hours using a hot oven were measured.

In Table 1, the tensile strength and elongation after aging are represented by the formula: Xa / Xo × 100 (%) [where Xa represents the tensile strength or elongation after aging, and Xo represents the tensile strength or elongation before aging. ], And the retention rate against tensile strength and elongation before aging.

2. Bloom test A Bloom test was performed to evaluate the blooming property of the polymer composition. In order to determine the presence or absence of the bloom of the antioxidant, 2 parts of carbon black was added to prepare a black sheet, which was left at room temperature for one month. The state of bloom of the antioxidant was visually evaluated.

 The results are shown in Table 1.

As can be seen from Table 1, the polymer composition obtained by crosslinking the reactive antioxidant of the present invention shows good aging resistance and does not cause bloom.

[Effects of the Invention] According to the present invention, a reactive antioxidant synthesized from an unsaturated fatty acid chloride having a main chain having a certain number of carbon atoms or more has extremely excellent oxidation as compared with a conventional reactive antioxidant. Demonstrate the effect of prevention. Furthermore, since this antioxidant has reactivity and can crosslink with a polymer, it is excellent in blooming resistance and extraction resistance. That is, since a polymer composition containing an appropriate amount of such a reactive antioxidant has excellent antioxidant effect, extraction resistance and blooming resistance, it is difficult to use a material or a material that requires long-term heat resistance. It is effective when used for materials that require extractability.

Continued on the front page (72) Inventor Noriko Matoba 2-14-16 Chibune, Nishiyodogawa-ku, Osaka-shi, Osaka Inside Nard Research Institute Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 15/08 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. The formula: [Wherein, R ₁ and R ₂ are an alkyl group having 1 to 4 carbon atoms, R ₃ and R ₄ are a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₅
Is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, l is a number of 0 to 3, m is 1 to 15
And n represents the number of 0 to 15, and the sum of m + n is 5 to 30. ] The reactive antioxidant which consists of a phenolic compound shown by these. 2. A polymer composition comprising the phenolic compound according to claim 1 as an antioxidant in an amount of 0.1 to 20% by weight, wherein the phenolic compound is crosslinked with a polymer.