JP2002128957A - Antioxidant and rubber composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antioxidant which inhibits its migration to the surface of an article when incorporated into an organic polymer such as a rubber and a resin to manufacture the article. SOLUTION: The antioxidant is obtained by bonding a group having an anti-aging action, e.g. a residue of an amine based or phenol based antioxidant for rubbers to silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antioxidant useful for imparting weather resistance, heat aging resistance and ozone resistance to a product comprising an organic polymer such as rubber or resin, and an organic polymer composition containing the same. More specifically, when the organic polymer composition is commercialized, the antioxidant migrates to the surface of the product or other members with the passage of time to impair the commercial value of the product or reduce the antiaging ability. And an organic polymer composition containing the same.

[0002]

2. Description of the Related Art Various anti-aging agents have been used in organic polymers such as rubbers and resins in order to secure weather resistance, heat aging resistance and ozone resistance. However, it is known that these anti-aging agents themselves migrate to the surface of the organic polymer product or other members with the passage of time, impairing the appearance of the product, or reducing the anti-aging ability. . In order to solve such a problem, a method of binding an antioxidant to an organic polymer (for example, VP Kirpichev et al., Vys
okomol Soed., Ser A, 11, 2293 (1969), SMEgbase,
Development in Polymerstabilization, 1, 131 (197
6), Minoura, Yamamoto, Sakako, Japan Rubber Association, 53,625
(1980)), a polymerizable antioxidant (for example, see JP-A-48-22529), an antioxidant having a rubber-reactive functional group (for example, Rubber Chem. Technol, 5).
0, 650 (1977)). However, since these anti-aging agents are not compatible with organic polymers such as rubber and resin used, there is a problem that desired anti-aging performance is not exhibited, and since the concentration of the anti-aging agent is low, many anti-aging agents are present. There is a problem in that an agent-binding polymer must be added, and these adversely affect physical properties.

[0003]

As described above, various anti-aging agents are used in rubber and resin products for their weather resistance and ozone resistance. There has been a problem that the material migrates to the product surface or another member with the passage of time, and the appearance of the product is impaired, and the ability to prevent aging is reduced. Accordingly, an object of the present invention is to develop an anti-aging agent which does not migrate into a product of an organic polymer when incorporated into an organic polymer such as rubber or resin.

[0004]

According to the present invention, there is provided an antioxidant comprising silica having a group having an antioxidant action bonded thereto.

[0005]

According to the present invention, an antioxidant, particularly an antioxidant, is bonded to silica and used as an antioxidant, whereby the antioxidant moves in the product organic polymer matrix. I found out that I could not.

Since the antioxidant according to the present invention is obtained by bonding a group having an antioxidant action to silica, the antioxidant remains in the product in a state of being bonded to the silica without moving in the product, and the desired aging Has a preventive action. The group having such an antioxidant effect is not particularly limited, and may be any conventionally known group (portion) which is compounded in an organic polymer and has an aging resistance effect.

Preferred examples of the antioxidant according to the present invention having an antioxidant action include, for example, residues of amine or phenolic antioxidants for rubber.

A typical example of the amine-based antioxidant residue is
Formula (I):

[0009]

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A typical structure of the antioxidant of the present invention for producing silica having this structure is represented by the following formula (II).

[0011]

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In the formula (II), R independently represents 1 to 1 carbon atoms.
An alkyl group of 18 (for example, methyl group, ethyl group, propyl group, butyl group, octyl group, octadecyl group) or an alkoxy group having 1 to 6 carbon atoms (for example, methoxy group, ethoxy group, propoxy group, butoxy group). , R is at least one of the aforementioned alkoxy groups. As a specific method of bonding a group having an antioxidant effect to silica,
For example, using an alkoxysilyl group-containing antioxidant represented by the formula (II), the compound is bonded to an existing silica surface, or the formula (II) is singly or hydrolyzed and condensed with another alkoxysilyl group-containing compound. In order to bond a group having more antioxidant action, the latter method is more preferable, and the compound containing an alkoxysilyl group is preferably the following formula (III).

The anti-aging agent according to the present invention has the formula (I)
I) and the following formula (III):

[0014]

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[R in the formula (II) is as defined above, and in the formula (III), R ¹ is independently a carbon atom having 1 to 1 carbon atoms.
8 alkyl groups (for example, methyl group, ethyl group, propyl group, butyl group, octyl group, octadecyl group) and C1-C6 alkoxy groups (for example, methoxy group, ethoxy group, propoxy group, butoxy group). , R ¹ of 50
% Or more, preferably 70% or more is an alkoxy group.]
Can be obtained by co-hydrolyzing and condensing the compound of formula (I).

The antioxidant of the present invention contains at least 3% by weight, preferably 5 to 50% by weight, of a residue of the structure of the formula (I). If the amount is too small, it is necessary to incorporate a large amount of silica in order to obtain a sufficient anti-aging effect, which may cause deterioration in physical properties. Also, synthetically, 50% by weight is considered to be a practical limit.

In the organic polymer composition according to the present invention, the aforementioned antioxidant of the present invention is preferably 0.5% by weight or more, more preferably 1% by weight or more, based on the total weight of the organic polymer.
20% by weight is blended. If the amount is too small, a sufficient anti-aging effect may not be obtained, which is not preferable. Conversely, if the amount is too large, the anti-aging effect does not change, and it is economically disadvantageous.

In the present invention, the diene rubber compounded in the rubber composition includes, for example, any diene rubber which can be used as a raw material rubber for tires. NR), polyisoprene rubber (IR), various polybutadiene rubbers (B
R), various styrene-butadiene copolymer rubbers (SB
R) and the like. It can be used alone or as any blend.

In the rubber composition according to the present invention, in addition to the above essential components, reinforcing agents (fillers) such as carbon black and silica, vulcanizing or crosslinking agents, vulcanizing or crosslinking accelerators, various oils, aging Inhibitors, plasticizers, and, if necessary, various additives commonly used for tires such as a silane coupling agent that reacts with a diene rubber, and other general rubbers can be compounded. The blend can be kneaded and vulcanized in a conventional manner into a composition and used to vulcanize or crosslink. The compounding amounts of these additives can also be conventional general compounding amounts as long as they do not contradict the object of the present invention.

[0020]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Sample Preparation In the formulation shown in Table I, the components other than the vulcanization accelerator and sulfur were kneaded in a 1.8-liter closed mixer for 3 to 5 minutes and released when the temperature reached 165 ± 5 ° C. To obtain a master batch. 8 vulcanization accelerators and sulfur
The mixture was kneaded with an inch open roll to obtain a rubber composition.
The obtained rubber composition was press-vulcanized at 160 ° C. for 20 minutes in a mold of 15 × 15 × 0.2 cm to prepare a target test piece (rubber sheet), and its physical properties were evaluated. The results are shown in Table I.

Example 1 (Synthesis of antiaging agent 1) 46.1 g of N-phenyl-p-phenylenediamine and γ
62.1 g of glycidoxypropyltrimethoxysilane
Was reacted at 65 ° C. for 5 hours in a solvent of 108 g of methanol to obtain a silane compound having a structure of the following formula (IV).

[0023]

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Next, ¹ H NMR analysis of this compound confirmed that the epoxy group had completely disappeared. FIG. 1 shows ¹ H NMR after the methanol was distilled off.

Example 2 (Synthesis of antioxidant 2) 150 g of water was added to 90 g of the silane compound (50% by weight methanol solution) obtained in Example 1 and 45 g of methylsilicate MS51 (manufactured by Mitsubishi Chemical), and the mixture was added at room temperature. The mixture was stirred for 24 hours to obtain 72 g (84% methoxy group hydrolysis rate) of light purple silica powder. The structure (V) of this silica powder is estimated as follows.

[0026]

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Example 3 30 g of the silane compound (50% by weight methanol solution) obtained in Example 1 was mixed with 100 g of silica (Nipsil AQ, manufactured by Nippon Silica) and treated at 100 ° C. for 24 hours. The obtained silica is washed with methanol and dried, and silica 1
23 g were obtained. The N-phenyl-p-phenylenediamine residue content of this silica was 6% by weight.

[0028] Adjust the rubber composition having a compounding composition shown in Comparative Examples 1-2 and Examples 4-5 Evaluation heat aging characteristics table I, pressurized硫直and after 100 ° C., 100% after 96 hours accelerated aging test
The modulus was measured in accordance with JIS K6251. A sample having a retention rate exceeding 150% was determined to be defective, and a sample having a retention rate of 140% or less was determined to be good.

Observation of Surface Condition A rubber composition having the compounding composition shown in Table I was prepared, and the appearance immediately after vulcanization and one month after vulcanization were visually evaluated. ×: anti-aging agent bleeds and changes to brown △: cracks mixed ○: normal (no change in black)

[0030]

[Table 1]

Footnotes to Table I ^{* 1} NR: Natural rubber (RSS # 1) ^{* 2} Carbon black: N339 (Tokai Carbon, Seast KH) ^{* 3} Stearic acid: Industrial stearic acid ^{* 4} Zinc white: Zinc white 3 ^{* 5} Wax: Sunnock (Ouchi Shinko Chemical) ^{* 6} Antioxidant: Noxeller 6C (Ouchi Shinko Chemical) ^{* 7} Antioxidant 1: silica of Example 2 ^{* 8} Antioxidant 2: silica of Example 3 ^{* 9} Sulfur: 5% oil-extended sulfur ^{* 10} Vulcanization accelerator: CZ (N-cyclohexyl-2-benzothiazolylsulfenamide)

[0032]

As described above, by binding an anti-aging agent to silica, it is possible to effectively prevent the anti-aging agent from migrating to the surface of an organic polymer such as rubber. It shows the same performance as the agent.

[Brief description of the drawings]

FIG. 1 shows ¹ HNMR of a silane compound synthesized in Example 1.
It is a spectrum.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 83/06 C08L 83/06 C09K 15/32 C09K 15/32 BF term (Reference) 4H025 AA68 4H049 VN01 VP01 VQ35 VR24 VU19 4J002 AC011 AC031 AC061 AC081 CP092 DJ016 EX076 FB146 FD010 FD036 FD140 4J035 AA02 AA03 BA03 BA13 CA061 CA19N CA191 FB01 LB20

Claims (10)

[Claims] 1. An antioxidant comprising silica having a group having an antioxidant action bonded thereto. 2. The antioxidant according to claim 1, wherein the group having an antioxidant action is a residue of an amine or phenolic antioxidant for rubber. 3. The antioxidant according to claim 2, wherein the residue of the amine antioxidant is a residue of an aromatic amine antioxidant. 4. The residue of the aromatic amine-based antioxidant has the formula (I): The antioxidant according to claim 3, which is a group represented by the formula: 5. A compound of the formula (II): (In the formula, R is independently an alkyl group having 1 to 18 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
Are alkoxy groups). 6. An anti-aging agent obtained by binding an anti-aging agent of the formula (II) to silica. 7. Formulas (II) and (III): (In the formula, R is independently an alkyl group having 1 to 18 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
One is an alkoxy group, and R ¹ is independently C 1-18
Which is an alkyl group or an alkoxy group having 1 to 6 carbon atoms, wherein 50% or more of R ¹ is an alkoxy group). Co-hydrolyzing and condensing a compound. 8. The anti-aging agent according to claim 3, comprising at least 3% by weight of a residue having the structure of the formula (I). 9. An organic polymer composition comprising an organic polymer and the antioxidant according to claim 1. 10. The organic polymer composition according to claim 9, wherein the organic polymer is a diene rubber.