JP7240721B2 - Ozone resistant anti-aging agent - Google Patents

Description

The present invention relates to an ozone-resistant antiaging agent. More specifically, it relates to an anti-ozonant anti-aging agent that does not affect vulcanization speed, has good dispersibility in rubber products, is non-staining, and can impart sufficient ozone resistance to rubber products. .

In general, diene-based rubbers have double bonds in their main chains, so they react with ozone in the atmosphere even under normal operating conditions such as normal temperature and normal pressure. Therefore, rubber products containing diene rubbers have the problem that ozone cracks occur over time, impairing their performance.

In order to suppress such problems, it is common to add anti-aging agents to rubber products. Anti-aging agents that are often used include amine-based anti-aging agents such as IPPD and 6PPD.

However, when this amine-based anti-aging agent is irradiated with light, it is strongly colored under the influence of light. Therefore, in most cases, amine-based anti-aging agents cannot be used in light-colored rubber products that do not contain carbon black because they impair the color. Moreover, even with rubber products containing carbon black, the color of the rubber product often migrates to objects that come into contact with the rubber product, causing problems. Therefore, non-staining rubber products have been proposed.

Here, two methods are conventionally known as methods for improving non-staining property and ozone resistance (making it difficult for ozone cracks to occur).

The first technique is to blend rubber wax. By adding rubber wax, after vulcanization, the rubber wax blooms from the inside of the rubber product to form a wax layer on the surface of the rubber product. This wax layer physically blocks contact between the rubber product and ozone, making it difficult for ozone cracks to occur.

However, this wax for rubber does not follow the elongation of rubber products, and there is a problem that the wax layer is easily broken when the rubber product is elongated, and cracks form at the broken sites.

A second method is to use a non-staining anti-aging agent such as a phenol-based or thiourea-based anti-aging agent. Among non-staining anti-aging agents, compounds having a cyclohexene skeleton are known to be non-staining and capable of imparting a certain level of ozone resistance (see, for example, Cited Documents 1 and 2).

JP-A-50-19545 JP-A-55-30737

However, the compound described in Patent Document 1 has a large effect on the vulcanization rate and tends to increase the vulcanization rate. If the vulcanization rate is increased in this way, when using a polymer that easily scorches (premature vulcanization) such as chloroprene rubber, the elasticity increases and the workability decreases, which is undesirable. In addition, the compound described in Patent Document 2 has a melting point of around 100° C. (high melting point), so in the case of rubber (such as chloroprene rubber) to which heat is not applied much, it may not be completely dissolved and may cause poor dispersion. I don't like it.

For these reasons, we have developed an anti-aging agent that does not affect the vulcanization speed, has good dispersibility in rubber products, is non-staining, and can impart sufficient ozone resistance to rubber products. was coveted.

The present invention has been made in view of such problems of the prior art. The anti-ozone anti-aging agent of the present invention does not affect vulcanization speed, has good dispersibility in rubber products, is non-staining, and can impart sufficient ozone resistance to rubber products. It is.

According to the present invention, the following ozone-resistant antioxidant is provided.

[1] A non-staining anti-ozonant antioxidant containing a compound represented by the following general formula (1).

（一般式（１）中、ａは、それぞれ独立に、水素またはメチル基であり、Ｒは、直鎖または分岐の炭素数１～５のアルキレン基である。）

(In general formula (1), each a is independently hydrogen or a methyl group, and R is a linear or branched alkylene group having 1 to 5 carbon atoms.)

[2] The ozone-resistant antioxidant according to [1] above, which further contains a wax.

[3] The above [2], wherein the ratio of the wax to the compound represented by the general formula (1) (wax/compound represented by the general formula (1)) is from 0.1 to 5.0. 3. The ozone resistant anti-aging agent described in .

[4] The ozone resistance according to the above [1] to [3], further comprising a support, and including a plurality of granules in which the compound represented by the general formula (1) is supported on the support. anti-aging agent.

[5] Contains the ozone-resistant antioxidant according to [1] to [4] and a rubber component, and the amount of the ozone-resistant antioxidant is based on 100 parts by mass of the rubber component and 0.3 to 15 parts by mass, a rubber composition.

[6] The rubber composition according to [5], wherein the rubber component is chloroprene.

The anti-ozonant anti-aging agent of the present invention does not affect the vulcanization speed, has good dispersibility because the compound represented by the general formula (1) is a liquid, and is non-staining and rubber-resistant. This has the effect of imparting sufficient ozone resistance to the product.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments for carrying out the present invention will be described below, but the present invention is not limited to the following embodiments. In other words, it is understood that any modifications, improvements, etc., made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention also belong to the scope of the present invention. should.

(1) Ozone-resistant antioxidant:
The ozone-resistant antioxidant of the present invention is a non-staining agent containing the compound represented by the general formula (1). Such an anti-ozone anti-aging agent does not affect the vulcanization speed, and since the compound represented by the general formula (1) is a liquid, it has good dispersibility. Sufficient ozone resistance can be imparted to the product.

(1-1) Compound represented by general formula (1):
The compound represented by the general formula (1) has two or more cyclohexenes in the molecule (where a is hydrogen or a methyl group) and has a skeleton via an ester bond. The compound represented by the general formula (1) can prevent occurrence of ozone cracks in the rubber component. Specifically, ozone cracks in rubber components are caused by oxidation of double bonds in rubber components. Oxidation cracking of the rubber component can be prevented by oxidizing the compound represented by the general formula (1) instead of oxidizing the double bond portion. Therefore, sufficient ozone resistance can be imparted to the rubber product.

Furthermore, the compound represented by the general formula (1) is a colorless substance, and since it is colorless, it can exhibit non-staining properties. In addition, the term "staining property" as used herein means discoloration of the rubber product itself and discoloration of objects in contact with the rubber product over time.

Furthermore, since the compound represented by the general formula (1) is a liquid, there is no risk of poor dispersion when mixed with the rubber component. That is, when it is a solid, it may remain in the rubber component without being dissolved, resulting in poor dispersion. When such poor dispersion occurs, the appearance of the rubber product is poor, and the anti-aging effect is not sufficiently exhibited.

Furthermore, the compound represented by general formula (1) does not contain functional groups or elements that affect the vulcanization reaction system in terms of its structural formula. Therefore, it does not affect the vulcanization speed of the unvulcanized rubber composition (rubber composition of the present invention) Also, the vulcanization rate in the unvulcanized rubber composition does not become too fast).

All a's in the general formula (1) may be the same. In addition, all of a may be different, or a part thereof may be different.

R in the general formula (1) is a linear or branched alkylene group having 1 to 5 carbon atoms, preferably an alkylene group having 1 or 2 carbon atoms.

(1-2) Wax (WAX):
The ozone-resistant antioxidant of the present invention preferably further contains wax in addition to the compound represented by formula (1). By containing this wax, one of the compound represented by general formula (1) and the wax promotes the bloom of the other, resulting in an overall increase in the amount of bloom. Therefore, the ozone resistance effect is synergistically improved. For example, natural rubber is a rubber component that is prone to aging due to ozone. It has an anti-aging effect.

As used herein, "wax" specifically means wax for rubber.

Examples of such waxes include conventionally known waxes for rubber, such as paraffin waxes, microcrystalline waxes, and mixtures thereof.

In the ozone-resistant antioxidant of the present invention, the ratio of wax to the compound represented by general formula (1) (formula: wax/compound represented by general formula (1)) is 0.1 to It is preferably 5.0, more preferably 0.2 to 3.0, and particularly preferably 0.25 to 2.5. By setting the content in such a range, the ozone resistance can be improved even for rubber products whose main raw material is a rubber component, such as natural rubber, which tends to cause aging due to ozone.

(1-3) Carrier:
The ozone-resistant antioxidant of the present invention may contain a support. When the support is contained in this way, the ozone-resistant anti-aging agent contains a plurality of granules in which the compound represented by the general formula (1) is supported on the support. Such an anti-ozonant anti-aging agent has improved handleability. Specifically, when the antiozonant is a liquid, the liquid is not only more troublesome to handle than a solid, but also reduces the accuracy of the amount to be added ( Specifically, due to adhesion to a weighing container or the like, there is a risk that the amount will be less than the amount that should be added. Moreover, when mixing with other raw materials, there is a possibility that sufficient mixing cannot be achieved in a short time. In addition, "particulate matter" means granular matter, and there is no particular limitation on its size (particle diameter), and it can be simply referred to as "fine particles (including powder)". For example, particles (including powder) of several millimeters or less (that is, about 5 mm or less).

As the carrier, conventionally known carriers can be appropriately employed, and examples thereof include silica, carbon black, calcium carbonate, talc, clay and the like.

(1-4) Other components:
The ozone-resistant antioxidant of the present invention may further contain other compounds in addition to the compound represented by the general formula (1) and the wax.

Conventionally known additives can be appropriately selected as other compounds. Examples of conventionally known additives include vulcanization accelerators, processing aids, and the like.

The ozone-resistant antioxidant of the present invention may contain other components as described above, and as long as the effect of the present invention is exhibited, the amount of the compound represented by the general formula (1) is is not particularly limited, but the compounding amount of the compound represented by general formula (1) can be about 20 to 80% by mass in the ozone-resistant antiaging agent of the present invention.

In the present invention, the compound represented by general formula (1) itself can be used as the ozone-resistant antiaging agent of the present invention. The ozone-resistant anti-aging agent of the present invention may contain a wax or a carrier.

(1-4) Method for producing the ozone-resistant antioxidant of the present invention:
In the method for producing the ozone-resistant antiaging agent of the present invention, compound A can be obtained by, for example, the Tishchenko reaction in which two equivalents of an aldehyde compound form an ester compound. More specifically, the aldehyde compound is stirred in the presence of a Lewis acid catalyst such as Al(OR) ₃ . By doing so, a compound having an ester skeleton such as compound A described in Synthesis Example 1 can be synthesized. As a post-treatment, the catalyst can be deactivated and removed, followed by liquid separation treatment, concentration and distillation under reduced pressure.

(2) Rubber composition of the present invention:
The rubber composition of the present invention contains the ozone-resistant anti-aging agent of the present invention and a rubber component, and the amount of the ozone-resistant anti-aging agent of the present invention is , 0.3 to 15 parts by mass.

According to such a rubber composition, it is possible to produce a rubber product that exhibits sufficient ozone resistance while being non-staining. If the blending amount is less than the lower limit, the ozone resistance may be deteriorated. If it exceeds the upper limit, there is a risk that the mechanical properties (breaking strength, breaking elongation, etc.) of the rubber product may deteriorate.

The rubber component is, for example, a main raw material for rubber products such as colored tires and colored rubber mats.

The rubber component is not particularly limited, but examples include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, butyl rubber, and ethylene-propylene copolymer. rubber, ethylene-propylene-diene copolymer rubber, hydrogenated acrylonitrile-butadiene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, epichlorohydrin rubber, silicone rubber, urethane rubber, polysulfide rubber, fluororubber, and the like. . Among these, chloroprene is particularly effective. In addition, these rubber components may be used individually by 1 type, or may be used in mixture of 2 or more types.

The rubber composition of the present invention may further contain other additives in addition to the anti-ozone anti-aging agent and rubber component of the present invention. Examples of other additives include vulcanizing agents, vulcanization accelerators, fillers, plasticizers, and the like.

The rubber composition of the present invention can be press-vulcanized into a vulcanized rubber (rubber product). Examples of rubber products include colored tires and colored rubber mats. Thus, it can be used for rubber products in which color is particularly important. The rubber composition of the present invention is not limited to press vulcanization, and other vulcanization methods may be employed.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

(Synthesis example 1)
15.0 g of toluene and 5.0 g (0.024 mol) of aluminum isopropoxide are placed in a 200 ml four-neck glass flask equipped with a stirrer, thermometer and dropping funnel, and stirred to dissolve the aluminum isopropoxide. to obtain a lysate. After that, 115.0 g (1.046 mol) of 3-cyclohexene-1-carboxaldehyde was added dropwise to this solution over 2 hours while paying attention to heat generation. The temperature of the solution during dropping was 25-45°C. After the dropwise addition was completed, the internal temperature was adjusted to 45° C. and the mixture was stirred for 1 hour.

Then, 5 ml of 1 mol/L hydrochloric acid and 20 ml of water were added, stirred for 30 minutes, and then filtered. After the filtrate was neutralized by adding 10% aqueous sodium hydroxide solution, 100 ml of ethyl acetate was added for extraction, and the mixture was concentrated under reduced pressure to remove ethyl acetate to obtain a crude product. The obtained crude product is heated to 118.0° C. under a pressure condition of 200 Pa to remove side reactants, and (3-cyclohexenyl)methyl 3-cyclohexene-1-carboxylate (the following formula (A) 84.4 g (0.383 mol) of a compound represented by (hereinafter referred to as "compound A") was obtained.The purity of the obtained compound A was analyzed by GC (gas chromatography), and the purity was 95.1%. of purity.

(Synthesis example 2)
Synthesis Example except that 8.1 g (58.7 mmol) of 3,4-dimethyl-3-cyclohexene-1-carboxaldehyde was added dropwise to the solution instead of 3-cyclohexene-1-carboxaldehyde in Synthesis Example 1. (3,4-dimethyl-3-cyclohexenyl)methyl 3,4-dimethyl-3-cyclohexene-1-carboxylate (a compound represented by the following formula (B) (hereinafter , referred to as "compound B") was obtained, and 5.7 g (20.7 mmol) of this compound B was analyzed by gas chromatography to find that the purity was 94.6%.

(Examples 1 and 2, Comparative Examples 1 to 3)
(1) Preparation of rubber composition:
100 parts by mass of chloroprene rubber (mercaptan-modified: manufactured by Denka) was added to two rolls with a diameter of 24 cm and masticated for 3 minutes. 20 parts by mass of magnesium oxide (manufactured by Kanto Chemical Co., Ltd.), 1 part by mass of stearic acid (manufactured by Kao Corporation), and 10 parts by mass of naphthenic oil (manufactured by Idemitsu Kosan Co., Ltd.) are added, and chloroprene rubber is added. The mixture was kneaded for a total of 50 minutes to obtain an A kneaded masterbatch.

0.5 parts by mass of Sancellar 22-C (manufactured by Sanshin Kagaku Kogyo Co., Ltd.) and 5 parts of zinc oxide (manufactured by Kanto Kagaku Co., Ltd.) are added to this A kneaded masterbatch with two rolls with a diameter of 24 cm, and further kneaded. A B kneaded masterbatch was obtained.

Various compounds (compounds A, B, E, 6PPD) shown in Table 1 were added to the obtained B-kneaded masterbatch with two rolls to obtain a mixture. Thereafter, this mixture was further kneaded to obtain an unvulcanized rubber composition (rubber composition).

(2) Preparation of vulcanized rubber:
The obtained unvulcanized rubber composition was press vulcanized to obtain a vulcanized rubber sheet having a thickness of 2.0 mm.

(3) Evaluation of rubber composition:
(static ozone test)
The test was conducted according to JIS K 6259. A test piece was obtained by punching out the vulcanized rubber sheet with a No. 1 dumbbell. After attaching this test piece to a jig (prescribed jig of JIS K 6259), it was stretched so that the distance between the marked lines of 4 cm was 30%, and it was left in a constant temperature bath at 20 ° C. for 24 hours. placed. After that, the test piece was exposed to ozone of 80 pphm concentration at 40° C., and was taken out and observed every 24 hours from the start, and this was repeated for a total of 240 hours (observation was performed 10 times). Tables 1 to 5 show the elapsed time when the initial crack was observed. Here, the "initial crack" is an ozone crack that can be visually recognized with a magnifying glass of 10x by adopting a method according to "1" in the criteria "1 to 5" used for judging the size of cracks in JIS K 6259. indicates that at least one was confirmed.

(Color difference test)
The obtained vulcanized rubber sheet was divided into three equal parts to prepare a test piece, and the test piece (vulcanized rubber sheet) was measured using an L ^* a ^* b ^* display system color difference measuring instrument (manufactured by Konica Minolta). Color was measured. After measurement, these test pieces were placed outdoors in sunlight and left for 24 hours. After that, the color of the test piece was measured again with the color difference measuring instrument, and the amount of change in color before and after being left for 24 hours was calculated. Similarly, the amount of change in color after being left outdoors in sunlight for 120 hours was also calculated.

Table 1 shows the results of the static ozone test and the color difference test. In Table 1, "Compound E" is a thiourea-based non-staining antioxidant (a compound represented by the following formula (E)), and "6PPD" is a staining antioxidant (specifically is trade name "Ozonon 6C" manufactured by Seiko Chemical Co., Ltd.: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine).

In Examples 1 and 2, like the thiourea-based compound part E, it did not affect the color change of the test piece (vulcanized rubber sheet), and furthermore, it had a resistance equivalent to 6PPD, which is a staining anti-aging agent. It turns out that it has ozone property. The thiourea-based compound E is a conventionally known non-staining antioxidant.

(Examples 3-9, Comparative Examples 4-10)
(1) Preparation of rubber composition:
100 parts by mass of chloroprene rubber (mercaptan-modified: manufactured by Denka Co., Ltd.), which is a rubber component, 4 parts by mass of magnesium oxide (manufactured by Kanto Chemical Co., Ltd.), 1 part by mass of stearic acid (manufactured by Kao Corporation), SRF carbon black (manufactured by Asahi Carbon Co., Ltd.) 50 parts by mass, 5 parts by mass of naphthenic oil (manufactured by Idemitsu Kosan Co., Ltd.), and 1 part by mass of Amide HT (manufactured by Mitsubishi Chemical Co., Ltd.) were kneaded for 3.5 minutes in a 1.7 L Banbury mixer to obtain a kneaded product.

To the resulting kneaded product, 1.2 parts by mass of Suncellar 22-C (manufactured by Sanshin Chemical Industry Co., Ltd.), 0.3 parts of Suncellar TT (manufactured by Sanshin Chemical Industry Co., Ltd.), and 5 parts of zinc oxide (manufactured by Kanto Chemical Industry Co., Ltd.) were added by two rolls with a diameter of 24 cm, and further kneaded to obtain a masterbatch.

Various compounds shown in Table 2 and WAX1 shown in Table 2 were added to the obtained masterbatch using two rolls to obtain a rubber mixture. things).

(2) Preparation of vulcanized rubber:
The obtained unvulcanized rubber composition was press vulcanized to obtain a vulcanized rubber sheet having a thickness of 2.0 mm.

(3) Evaluation of rubber composition:
(static ozone test)
The test was conducted according to JIS K 6259. A test piece was obtained by punching out the vulcanized rubber sheet with a No. 1 dumbbell. After attaching this test piece to a jig (prescribed jig of JIS K 6259), it was stretched so that the distance between the marked lines of 4 cm was 30%, and it was left in a constant temperature bath at 20 ° C. for 24 hours. placed. After that, the test piece is exposed to ozone of 80 pphm concentration at 40° C., and is taken out and observed every 24 hours from the start, and this is repeated for a total of 552 hours (23 observations were made).

(Mooney scorch test)
Using the unvulcanized rubber composition produced as described above, a test was carried out according to JIS K 6300.

In Table 2, the value of ML1+4 indicates the torque 4 minutes after the rotor started rotating after setting the test piece in a dedicated measuring device and preheating for 1 minute. Vm indicates the minimum torque, t5 indicates the time (minutes) when the 5-point torque rises from Vm, and t10 and t35 are the same as t5. That is, t10 indicates the time (minutes) for the 10-point torque to rise from Vm, and t35 indicates the time (minutes) for the 35-point torque to rise from Vm. tΔ30 indicates the value of t35-t5. Then, the value of t5 and the value of tΔ30 were each compared with the case where no anti-ozonant anti-aging agent (Compounds A to G, WAX) was added (Comparative Example 4) to determine whether or not there was an effect on the vulcanization speed. It was judged. As a result, if the difference between the values is 1 or more (formula: value of Comparative Example 4 - value of each example/comparative example is 1 or more), the effect on the vulcanization speed is "Yes", and this " Those that did not correspond to "yes" were set to "no".

(dispersibility)
Visually observe the surface of the vulcanized rubber sheet, and if the dispersion is good (the surface of the vulcanized rubber sheet is smooth and no unevenness caused by remaining grains can be confirmed), it is evaluated as "OK". Those with poor dispersion (when irregularities caused by particles remaining on the surface of the vulcanized rubber sheet were confirmed) were judged as "NG".

Table 2 shows the results of the various tests in Examples 3-9 and Comparative Examples 4-10. Compound G of Comparative Example 9 and WAX1 of Comparative Example 10 are solid at room temperature, and the melting point (° C.) is shown. For "WAX1", "Suntite C (manufactured by Seiko Kagaku Co., Ltd.)" was used.

Compounds C to G used in various examples and comparative examples are compounds represented by formulas (C) to (G) shown below. Compound A is compound A synthesized in Synthesis Example 1, and compound B is compound B synthesized in Synthesis Example 2.

As shown in Table 2, from the results of Examples 3 to 9 and Comparative Example 4 (that is, when Examples 3 to 9 were evaluated based on Comparative Example 4), compounds A and B (represented by general formula (1) It shows that the addition of an anti-ozonant anti-aging agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent containing the anti-oxidizing agent (a compound that is used in the rubber products) has no effect on the vulcanization speed and the dispersibility is good. Furthermore, as can be seen from Table 1 above, it can be said that when the anti-ozonant anti-aging agents containing compounds A and B are used, they are non-staining.

From the results of Examples 6 and 9 and Comparative Examples 4 and 6, it was found that those having two or more cyclohexene skeletons and having a structure in which those skeletons are interposed by an ester bond have a good ozone resistance effect. I understand. Comparative Example 5 has two cyclohexene skeletons, but does not have a structure in which these skeletons are interposed by an ester bond (no ester bond). In Comparative Example 6, the structure has a cyclohexene skeleton and an ester bond, but does not have two or more cyclohexene skeletons (that is, does not have a structure in which two or more cyclohexene skeletons are interposed by an ester bond).

In Comparative Example 7, a compound having a thiourea skeleton was used. Although the number and size of cracks were smaller than those in Comparative Example 4, initialization cracks were observed 24 hours after the start of evaluation. In addition, the effect on the vulcanization speed was also large.

Comparative Example 8 corresponds to the compound described in Patent Document 1. In Comparative Example 8, there was no difference in the results of the static ozone test, but the t5 (minute) value and tΔ30 (minute) value were lower than those of Comparative Example 4 (when no anti-aging agent was added). , and had a large effect on the vulcanization speed.

Comparative Example 9 corresponds to the compound described in Patent Document 2. In this Comparative Example 9, no difference was observed in the results of the static ozone test. It was found that when used as an anti-aging agent in chloroprene that was not dispersed, it caused poor dispersion.

Comparative Example 10 shows the results of adding WAX1 as an antioxidant. In Comparative Example 10, although the number and size of cracks were smaller than those in Comparative Example 4, initialization cracks were observed 24 hours after the start of the static ozone test.

(Examples 10-19, Comparative Examples 11-13)
(1) Preparation of mixture:
For the "mixture" shown in Table 3, various substances shown in Table 3 are weighed in an aluminum container at each mass ratio, heated to about 70 ° C. where each WAX 2 and 3 dissolves, stirred so that it becomes uniform, and then The mixture obtained by standing to cool is shown.

(2) Production of carrier (plurality of granules):
(2-1) In the case of a support containing no WAX (Examples 15 to 17):
The WAX-free "support" shown in Table 4 is obtained by weighing various substances (support, compound represented by general formula (1)) shown in Table 4 into an aluminum container at each mass ratio, and uniformizing. A support (plurality of granules) obtained by stirring is shown.

(2-2) Support containing WAX (Examples 18 and 19)
For the "support" containing WAX3 shown in Table 4, various substances shown in Table 4 (compound (compound A) represented by general formula (1), WAX3) were weighed into an aluminum container at each mass ratio, and WAX3 It is heated to about 70° C. at which the is dissolved, stirred until uniform, then silica (support) is added, and the support obtained by stirring is shown.

In Table 4, Comparative Example 11 and Example 10 are the same examples as Comparative Example 11 and Example 10 shown in Table 3, and are shown for reference.

(3) Preparation of rubber composition:
A masterbatch was produced in the same manner as in Example 3 and the like. After that, various substances (Compound A, WAX 2, 3) shown in Tables 3 and 4, and the mixture or the carrier were added to the obtained masterbatch with two rolls to obtain a rubber mixture. Thereafter, this rubber mixture was further kneaded to obtain an unvulcanized rubber composition (rubber composition).

(4) Preparation of vulcanized rubber:
The obtained unvulcanized rubber composition was press vulcanized to obtain a vulcanized rubber sheet having a thickness of 2.0 mm.

(5) Evaluation of rubber composition:
(static ozone test)
The obtained vulcanized rubber sheet was punched out with a No. 1 dumbbell and used as a test piece. A static ozone test was performed according to JIS K 6259. In Examples 10 to 19 and Comparative Examples 11 to 13 (Tables 3 and 4), the ozone concentration was 250 pphm, the temperature was 40 ° C., the elongation rate was 40%, and the total time was 264 hours. The conditions were the same as in Example 3 and the like.

Table 3 shows the results of the ozone test in Examples 10-14 and Comparative Examples 11-13. Also, as "WAX2", "Suntite R (manufactured by Seiko Kagaku Co., Ltd.)" was used, and as "WAX3", "Suntite S (manufactured by Seiko Kagaku Co., Ltd.)" was used. Both "WAX2" and "WAX3" correspond to mixtures of paraffin wax and microcrystalline wax (mixed waxes (WAX2 and WAX3 have different mixing ratios)).

The breakdown of the amount added in Example 11 is 2.0 parts by mass of compound A and 0.5 parts by mass of WAX2 (that is, the ratio of WAX2/compound A = 0.25). The breakdown is 2.0 parts by mass of compound A and 1.0 part by mass of WAX2 (ratio of WAX2/compound A = 0.5). Parts by mass, WAX2 is 2.5 parts by mass (ratio of WAX2/compound A = 2.5), and the breakdown of the amount added in Example 14 is 2.0 parts by mass of compound A and 1.0 part by mass of WAX3. part (ratio of WAX3/compound A=0.5).

Therefore, from these results, it was confirmed that the combined use of both (WAX and compound A) can further improve the ozone resistance. Further, from the results of Examples 12 and 14, similar effects were confirmed even when different kinds of WAX (WAX 2, 3) were used. Expression was confirmed not to be restricted to a particular WAX.

Table 4 shows the results of the ozone test in Examples 10 to 19 and Comparative Example 11. In Table 4, "VN-3 (manufactured by Tosoh Silica Co., Ltd.)" is used for silica, and "Silver-W (manufactured by Shiraishi Calcium Co., Ltd.)" is used for calcium carbonate (denoted as "Ca carbonate" in Table 4). was used, and "SRF carbon black (manufactured by Asahi Carbon Co., Ltd.)" was used as carbon black (denoted as "carbon. B." in Table 4).

The breakdown of the amount added in Examples 15 to 17 was 2.0 parts by mass for compound A and 1.0 part by mass for the carrier (silica, calcium carbonate, carbon black). From these results, it was confirmed that the performance of ozone resistance does not change even if the compound A is carried on various carriers. Further, as can be seen from the results of Examples 18 and 19, a third component such as WAX3 (a component other than the compound represented by the general formula (1)) was further supported, and the total number of parts of the supported material was reduced to rubber. It was confirmed that there is no problem in the performance of ozone resistance (sufficient performance is exhibited) even when the amount is about 15 parts by mass with respect to 100 parts by mass of the component.

(Examples 20-29, Comparative Examples 14-18)
(1) Preparation of rubber composition:
100 parts by mass of natural rubber (RSS No. 1), 5 parts by mass of zinc oxide (manufactured by Kanto Chemical Co., Ltd.), 3 parts by mass of stearic acid (manufactured by Kao Corporation), 50 parts by mass of FEF carbon black (manufactured by Asahi Carbon Co., Ltd.), naphthene as rubber components 10 parts by mass of oil (manufactured by Idemitsu Kosan Co., Ltd.) was kneaded for 3.5 minutes with a 1.7 L Banbury mixer to obtain a kneaded product.

To the resulting kneaded product, 1.3 parts by mass of Suncellar CM (manufactured by Sanshin Chemical Industry Co., Ltd.) and 2 parts by mass of powdered sulfur (manufactured by Hosokawa Chemical Industry Co., Ltd.) were added using two rolls with a diameter of 24 cm, and further kneaded. Went and got a masterbatch.

Various compounds shown in Table 5 were added to the obtained masterbatch using two rolls to obtain a mixture, and the mixture was further kneaded to obtain an unvulcanized rubber composition.

(2) Preparation of vulcanized rubber:
The obtained unvulcanized rubber composition was press vulcanized to obtain a vulcanized rubber sheet having a thickness of 2.0 mm.

(3) Evaluation of rubber composition:
(static ozone test)
The obtained vulcanized rubber sheet was punched out with a No. 1 dumbbell and used as a test piece. A static ozone test was carried out in accordance with JIS K 6259 to measure the elapsed time when initial cracks occurred. Table 5 shows the measurement results.

The static ozone test was performed under two different conditions. The first condition is 5% elongation between the gauge lines, 40° C., and 20 pphm of ozone concentration, and the second condition is 20% elongation between the gauge lines, 40° C., and 50 pphm of ozone concentration. The results obtained under the first condition are shown in the upper part of Table 5, and the results obtained under the second condition are shown in the lower part of Table 5.

From the results in Table 5, it can be seen that the combined use of both compound A and WAX synergistically imparts ozone resistance, rather than the use of compound A alone or WAX alone.

As shown in Table 5, the anti-ozone anti-aging agent of the present invention containing compound A, which is the compound represented by general formula (1), is not limited to chloroprene (chloroprene rubber), but other rubber components (natural rubber). It can be seen that effects such as imparting sufficient ozone resistance to rubber products can be exhibited even for (synthetic rubber). In particular, it is found that the combined use of WAX in addition to the compound represented by formula (1) synergistically improves the ozone resistance effect.

From the above, the anti-ozonant anti-aging agent of the present invention does not affect the vulcanization speed, has good dispersibility in rubber products, is non-staining, and provides rubber products with sufficient ozone resistance. I know it can be given.

The ozone-resistant anti-aging agent of the present invention can be employed as an ozone-resistant anti-aging agent blended in a rubber composition which is a material for producing rubber products such as color tires.

Claims (6)

A non-staining anti-ozonant antioxidant containing a compound represented by the following general formula (1).

(In general formula (1), each a is independently hydrogen or a methyl group, and R is a linear or branched alkylene group having 1 to 5 carbon atoms.) The anti-ozonant antiaging agent according to claim 1, further comprising a wax. 3. The resistance according to claim 2, wherein the ratio of the wax to the compound represented by the general formula (1) (wax/compound represented by the general formula (1)) is 0.1 to 5.0. Ozone antioxidant. 4. The ozone resistance according to any one of claims 1 to 3, further comprising a carrier, and comprising a plurality of granules in which the compound represented by the general formula (1) is carried on the carrier. Anti-aging agent. Containing the ozone-resistant anti-aging agent according to any one of claims 1 to 4 and a rubber component,
The rubber composition, wherein the amount of the ozone-resistant anti-aging agent compounded is 0.3 to 15 parts by mass with respect to 100 parts by mass of the rubber component. 6. The rubber composition according to claim 5, wherein said rubber component is chloroprene.