JP2794867B2 - 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 Shiba 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 explain 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).

Japanese Patent Application No. 1-238132 discloses a reactive antioxidant comprising a phenolic compound. JP-A-54-153896 discloses a method for producing a copolymer containing a phenolic reactive aging inhibitor.

[Problems to be Solved by the Invention] Reactive antioxidants exhibit a feature that they are excellent in extraction resistance and do not cause blooming only after reacting with a polymer. Therefore, simply kneading the reactive antioxidant does not improve the extraction resistance, and the reactive antioxidant is added to the polymer by heating or irradiating with a chemical crosslinking agent. It is necessary to react with. However, if the time from molding or extruding the composition in which the reactive antioxidant is kneaded to reacting the reactive antioxidant is long, the reactive antioxidant blooms during that time. Occurs. Further, the reactive antioxidant has a disadvantage that the antioxidant function is inferior to the non-reactive antioxidant.

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

[Means for Solving the Problems] The above-mentioned problem is solved by preparing a polydiene having an acid anhydride in a molecule by the formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number from 0 to 3. Can be solved by using a reactive antioxidant obtained by reacting an alcohol compound represented by the following formula:

Examples of polydienes include polybutadiene, polypentadiene, and polyhexadiene. The polydiene is not particularly limited as long as it has an acid anhydride in the molecule. Particularly, maleated polybutadiene to which maleic anhydride is added is preferable.

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 polybutadiene having an acid anhydride in the molecule has the formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number from 0 to 3. Is reacted with an alcohol compound represented by the formula: [In the formula, R ₁ , R ₂ and l are as defined above, R is an alkyl group, and n and m are natural numbers. ] The reactive antioxidant shown by these is obtained. The reaction can be performed by a method known per se and generally used, and does not require a special device or the like.

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. The type of the polymer material is not particularly limited, and may be any polymer that can react with the reactive antioxidant. Representative examples include polyolefins, polyester elastomers,
Examples thereof include polyolefin elastomers, polyurethanes, and ethylene propylene rubbers. 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 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, crosslinking agents such as organic peroxides, polyamines, sulfurs, and oximes may be used.

[Function] In the phenolic antioxidant, the one having an antioxidant function is a hydroxyl group bonded to a benzene ring, and the antioxidant effect is exerted by the radical generated by the oxidation being supplemented and stabilized. Also in the reactive antioxidant of the present invention, a hydroxyl group bonded to a benzene ring has an antioxidant function. On the other hand, the reactive antioxidant of the present invention has a feature that it does not easily bloom even if it does not react with a polymer by irradiation or a chemical crosslinking agent with respect to the extraction resistance and the blooming resistance. This is considered to be because the polydiene moiety having a high molecular weight is physically well entangled with the polymer. Therefore, when the reactive antioxidant of the present invention is used, the blooming of the antioxidant can be significantly reduced between the time when the polymer composition is molded and the time when the reactive antioxidant is reacted. it can.

In addition, 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) 140 g of 3,5-di-t-butyl-4-hydroxybenzyl alcohol, 140 g of maleated polybutadiene (number average molecular weight: 1000) and 0.3 g of p-toluenesulfonic acid were placed in a reaction vessel. The reaction was carried out at 80 ° C. for 2 hours. The obtained reaction product was converted into a toluene solution and reprecipitated with methanol to obtain 30 g of a reactive antioxidant A.

(B) According to the procedure shown in (a) above, 3,5-di-t
-Butyl-4-hydroxyphenethyl alcohol 140 g,
280 g of maleated polybutadiene (number average molecular weight: 2000)
Then, 0.3 g of p-toluenesulfonic acid was reacted at 80 ° C. for 2 hours to obtain 42 g of a reactive antioxidant B.

Example 1 Low-density polyethylene (melt index: 1.5) 100
5 parts by weight of the previously obtained reactive antioxidant A was blended with 5 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 electron beam irradiation amount was 12 Mrad. The following test was performed using the obtained sample.

Example 2 Ethylene-vinyl acetate copolymer (EVA, vinyl acetate: 15
% By weight, melt index: 0.7) 100 parts by weight of reactive antioxidant B was mixed with 5 parts by weight, and the mixture was roll-kneaded at 120 ° C.
A VA formulation was prepared. The obtained mixture was pressed under the conditions of 130 ° C. × 10 minutes to produce a sheet having a thickness of 1 mm. Acceleration voltage 1
This formulation was crosslinked using a MeV Bande-Graft electron beam accelerator. The amount of electron beam irradiation was 24 Mrad. The following test was performed using the obtained sample.

Example 3 Ethylene-ethyl acrylate copolymer (EEA, ethyl acrylate: 20% by weight, melt index: 2.0) 100
3 parts by weight of a reactive antioxidant A and 2 parts by weight of dicumyl peroxide as a cross-linking agent were blended into 1 part by weight, and the mixture was roll-kneaded at 120 ° C. to prepare an EEA blend. The EEA formulation was crosslinked using a press at 160 ° C. for 30 minutes. The following test was performed using the obtained sample.

Example 4 A polyethylene compound was prepared by repeating Example 1 except that 3 parts by weight of the reactive antioxidant A was used, and the compound obtained by electron beam irradiation was crosslinked. The amount of electron beam irradiation was 24 Mrad. The following test was performed using the obtained sample.

Example 5 Reactive antioxidant B3 was added to 100 parts by weight of low-density polyethylene.
Parts by weight and 1 part by weight of dicumyl peroxide as a cross-linking agent were blended and roll-kneaded at 120 ° C. to prepare a polyethylene blend. The polyethylene blend was crosslinked using a press at 160 ° C. for 30 minutes. The following test was performed using the obtained sample.

Comparative Examples 1 to 4 As comparative examples, N-phenyl-N '-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine (trade name: Nocrack G-1, manufactured by Ouchi Shinko Chemical Co., Ltd.) Reactive antioxidants), (3,5-di-t-
Butyl-4-hydroxybenzyl) acrylate and n-octadecyl-3- (4'-hydroxy-3 ', 5'
-Di-t-butylphenyl) propionate (trade name:
Irganox 1076, Ciba-Geigy)
Each composition was prepared by roll milling according to the compounding amounts shown in Table 1. In Comparative Examples 1, 2 and 4, electron beam irradiation was performed according to the procedure shown in Example 1 to crosslink the obtained compound (electron beam irradiation amount: 12 to 24 Mrad). Also,
In Comparative Example 3, the obtained compound was crosslinked using a press at 160 ° C. for 30 minutes. The following test was carried out using the sample thus obtained.

Test 1. Aging test In order to evaluate the effect of the antioxidant containing 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.

3. Measurement of extraction rate In order to evaluate the extraction resistance of the antioxidant, the extraction rate was measured using acetone. The obtained sample was extracted with acetone for 8 hours using a Soxhlet extractor. The weight of the sample before and after extraction was measured, and the extraction rate was calculated from the following equation.

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, does not cause bloom, and is excellent in extraction resistance.

[Effect of the Invention] Since the reactive antioxidant synthesized from a polydiene and an alcohol compound according to the present invention has a high molecular weight by itself, it has excellent bloom resistance without being reacted by a method such as irradiation or chemical crosslinking. Has extraction resistance. For this reason, bloom does not occur for a long period of time from the production of the molded article to the reaction of the reactive antioxidant. In addition, since the polydiene in the molecule has a plurality of double bonds, the amount of electron beam irradiation required for the reaction can be reduced, and chemical crosslinking can be performed under mild conditions.

In general, a reactive antioxidant is inferior to an ordinary antioxidant in antioxidant effect, but the reactive antioxidant of the present invention has an effect equivalent to that of an ordinary antioxidant. Further, the reactive antioxidant of the present invention has an advantage that it is phenol-based antioxidant and therefore has no pollution and therefore has a wide variety of uses such as being able to be used for blending of a colored substance and a light-colored substance.

──────────────────────────────────────────────────続 き Continued on the front page (72) Noriko Matoba 3-10-4 Nishi-Nagasu Higashidori, Amagasaki City, Hyogo Prefecture Inside Nard Research Institute, Inc. (56) References 58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 5/18 C08F 8/14 C08L 101/00 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A polydiene having an acid anhydride in a molecule is represented by the formula: [Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, l
Represents a number from 0 to 3. ] The reactive antioxidant obtained by reacting the alcohol compound shown by these. 2. The reactive antioxidant according to claim 1, wherein said alcohol compound is a 3,5-di-t-butyl-4-hydroxyphenyl alcohol compound. 3. The reactive antioxidant of claim 1 in an amount of 0.1 to 2
A polymer composition comprising 0% by weight, wherein the reactive antioxidant is crosslinked with a polymer.