JP2794904B2 - 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] Various antioxidants have conventionally been used to prevent thermal deterioration of plastics. As such an antioxidant, for example, 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).

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).

Further, Japanese Patent Application No. 2-1311 discloses a reactive antioxidant comprising a phenolic compound.

[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 problem is solved by applying rosin or modified rosin or a component thereof to a compound represented by the formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number of 1 to 3. Can be solved by using a reactive antioxidant obtained by reacting an alcohol compound represented by the following formula:

Rosin is a residue obtained by steam distillation of turpentine (so-called pine wood) secreted from the bark of coniferous trees (mainly pine) or extracted from its roots. Rosin includes gum rosin, wood rosin, tall oil rosin and the like, and any of these can be used.
Rosin is a mixture of various carboxylic acids, the main components of which are abietic acid, neoabietic acid, parastolic acid, dehydroabietic acid, dihydroabietic acid,
Dextropimaric acid, isodexropimaric acid, levopimaric acid or the like can be used alone or as a mixture of these as a raw material of the reactive antioxidant of the present invention.

Further, a modified rosin obtained by hydrogenating, disproportionating, or polymerizing rosin can also be used.

Alkyl groups R ₁ and R ₂ in the alcohol compound are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl group and the like, preferably a t-butyl group, and a t-butyl group. An alcohol compound having a hydroxyl group on both sides, for example, 3,5-di-t-
Compounds having a butyl-4-hydroxyphenyl group are preferred. Examples of such alcohol compounds include 3,5
-Di-t-butyl-4-hydroxybenzyl alcohol and 3,5-di-t-butyl-4-hydroxyphenethyl alcohol.

The reaction between rosin and an alcohol compound is known per se and can be performed by a commonly used method, and does not require a special device or the like. By mixing and heating rosin and an alcohol compound, an esterification reaction occurs, and a desired reactive antioxidant is obtained. For example, when using abietic acid as a raw material, the formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number of 1 to 3. When reacting an alcohol compound represented by the formula: [Wherein, R ₁ , R ₂ and 1 are as defined above. ] The reactive antioxidant shown by these is obtained.

Also change the carboxylic acid part of rosin to chloride,
The reactive antioxidant may be obtained by reacting with the alcohol compound.

The reactive antioxidant thus obtained is added in an amount of 0.1 to 20% by weight, preferably 0.3 to 10% by weight, based on the polymer material to obtain a polymer composition. The type of the polymer material is not particularly limited, and may be any polymer as long as it can react with the reactive antioxidant. Representative examples include polyolefin, polyester elastomer, polyolefin elastomer, polyurethane, ethylene propylene rubber, and the like. Further, such a polymer composition may contain an appropriate amount of a compounding agent which is 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 performed by commonly used methods and devices known per se. Radiation dose is 0.1-100Mrad (1-1000KGy), preferably 1-5
0 Mrad (1 to 500 KGy). As the chemical crosslinking agent, a known crosslinking agent usually used for crosslinking a polymer may be used. For example, crosslinking agents such as organic peroxides, polyamines, sulfurs, and oximes may be used.

[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 not had sufficient antioxidant effects, but the present invention introduces a substance having a bulky molecular structure, rosin, into a phenolic compound to provide a reaction having sufficient antioxidant effects. It has been found that it becomes a soluble antioxidant. It is presumed that a bulky substance having a large molecular weight, such as rosin, has a greater chance of capturing radicals that cause deterioration and thus has an improved antioxidant effect.

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. After that, it is further excellent in extraction resistance 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) To a reaction vessel were added 72 g of 3,5-di-t-butyl-4-hydroxybenzyl alcohol and 50 g of Chinese rosin (acid value: 170) containing abietic acid as a main component. , No catalyst, no solvent and reacted at 180 ° C for 24 hours, reactive antioxidant A110g
I got

(B) 50 g of Chinese rosin was dissolved in toluene, and 60 g of thionyl chloride was added dropwise at 80 ° C. to obtain rosin acid chloride.

Next, 10 g of 3,5-di-t-butyl-4-hydroxybenzyl alcohol was dissolved in toluene, 20 g of rosin acid chloride was added dropwise at 50 ° C., and the mixture was reacted at the same temperature for 30 minutes. After completion of the reaction, the mixture was washed with a 5% aqueous HCl solution and deionized water, and toluene was distilled off under reduced pressure to obtain 20 g of a reactive antioxidant B.

Example 1 Low-density polyethylene (melt index: 1.5) 100
3 parts by weight of the reactive antioxidant A obtained above were blended into parts 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. × 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 1 part 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.

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.

[Effect of the Invention] According to the present invention, a reactive antioxidant synthesized using rosin or modified rosin exhibits an extremely excellent antioxidant effect as compared with a conventional reactive antioxidant. 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 3-10-4 Nishi-Nagasu Higashidori, Amagasaki-shi, Hyogo Inside Nard Research Institute Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 15/06 -15/08 C08K 5/10-5/107 C08L 93/04 C08L 101/00 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] [1] A rosin or a modified rosin or a component thereof has a formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number of 1 to 3. ] The reactive antioxidant obtained by reacting the alcohol compound shown by these. 2. The reactive antioxidant according to claim 1, wherein the alcohol compound is 3,5-di-t-butyl-4-hydroxyphenyl alcohol. 3. The reactive antioxidant according to claim 1 or 2.
A polymer composition obtained by crosslinking 0.1 to 20% by weight of a polymer.