JPH02273643A - Phenol-based compound and stabilizer for butadiene-based polymercontaining the same compound as active ingredient - Google Patents

Abstract

NEW MATERIAL:2,4-Di-tert.-amyl-6-[1-di-tert.-amyl-2-hydroxyphenyl]ethyl methacrylate. EXAMPLE:An active ingredient of stabilizer used for butadiene-based polymer. The compound expressed by the chemical structure has an excellent gelatinization- preventing performance as well as coloring-preventing performance under high temperature and oxyacidic conditions, has high solubility to hydrocarbon-based organic solvent and is also stable to heat deterioration resistance in molding process by injection molding or extrusion molding, etc. The compound prevents the occurrence of fish eye gel in film forming process or the occurrence of micro gel causing a lowering of gloss in injection molding process and thus capable of providing a product free from coloring and having high qualities. PREPARATION:2,2-Ethylidenebis(4,6-di-tert.-aminophenol) is subjected to esterification reaction with methacrylic acid or derivative thereof such as methacrylic acid chloride or methacrylic anhydride in a solvent such as n-heptane in the presence of a base such as triethylamine and phosphorus oxychloride to provide the compound expressed by the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a new phenolic compound and a stabilizer for butadiene polymers containing the same as an active ingredient.

<Prior art> Butadiene-based polymers such as solution-polymerized polybutadiene rubber (BR), solution-polymerized styrene-butadiene copolymer rubber (SBR), and styrene-butadiene block copolymer (SBS) are usually treated with Ziegler as a catalyst. It is produced by anionic polymerization in a hydrocarbon solvent using a catalyst or an organolithium compound. Conventionally, the polymerization solvent was removed from the polymer solution after the polymerization reaction was completed using a steam stripping method, but from the perspective of energy conservation, a direct solvent drying method has recently been proposed that can theoretically minimize the amount of steam used. has been done.

However, since this method is usually processed at a high temperature of about 150 to 200°C, which is much higher than the boiling point of the polymerization solvent, there are problems such as gel formation during processing and coloring of the polymer after high-temperature processing. . Therefore, it has been desired to improve heat resistance and coloring resistance, especially in an oxygen-free environment such as in the butadiene polymer production process.

In addition, extrusion molding and injection molding such as SBS, or BR
In extrusion molding and injection molding of high-impact polystyrene modified with SBR or SBS, fish eye gel is generated due to lack of heat resistance as the processing process becomes higher and faster. ,
As a result, problems arise in that the physical properties of the film are significantly deteriorated and the film becomes discolored. Therefore, a solution to these problems has been strongly desired.

It is well known that various phenol-based, phosphorus-based, sulfur-based, and other antioxidants are added during the production and processing steps of butadiene-based polymers. For example, 2,6-di-t-butyl-4-methylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), n-octadecyl 3-(3,5-di to one phthyl-4
-hydroxyphenyl)propionate, triethylene glycol bisC3-(3-t-butyl-
4-hydroxy-5-methylphenyl)propionate], pentaerythrityltetrakis (3-(3゜5-di-t
-butyl-4-hydroxyphenyl)propionate]
, 1.3.5-)limethyl-2,4,6-)lis(3,5
- Use a phenolic antioxidant such as -di-t-butyl-4-hydroxybenzyl)benzene alone, or combine these phenolic antioxidants with tris(nonylphenyl) phosphite or distearylpentaerythritol diphosphite. or in combination with phosphorus-based antioxidants such as dilaurylthiodipropionate, simiristylthiodipropionate, distearylthiodipropionate, pentaerythrityltetrakis (3 - lauryl thiopropionate) and other sulfur-based antioxidants are known.

However, these methods suffer from thermal degradation (gelation), especially in the absence of oxygen, during high-temperature treatment to separate the polymer from the polymer solution during the production of butadiene-based polymers, or during high-temperature processing of butadiene-based polymers. For,
cannot exert sufficient effect.

Furthermore, a phenolic compound represented by the general formula (1) is known as a stabilizer for butadiene polymers.

For example, U.S. Patent No. 4.525.514 states that in the above general formula (1), R3 is hydrogen and R2 has 1 carbon number.
-4 alkyl groups, R3 is a t-butyl group, and in particular 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl), in which R2 is a methyl group, are disclosed. )-4-methylphenylacrylate is
It is described that it is effective as a stabilizer for butadiene-based polymers. This stabilizer is used to prevent thermal deterioration (gelation) during high-temperature treatment to separate the polymer from the polymer solution during the production of butadiene-based polymers, or during high-temperature processing of butadiene-based polymers, especially in the absence of oxygen. However, it has become clear that the color of the separated polymer is insufficient for practical use.

Furthermore, JP-A-63-146947 discloses that in the general formula (I), R1 is an alkyl group having 1 to 4 carbon atoms;
A group in which 2 is a quaternary carbon bond (e.g., t-butyl group) or a phenyl group, and a compound in which R3 is a t-butyl group can be used to prevent thermal deterioration (gelation) and coloring of butadiene-based polymers in the absence of oxygen. It has been disclosed that it is effective.

On the other hand, U.S. Patent No. 4.365.032 discloses a color-resistant antioxidant that prevents coloring of various synthetic resins due to oxidative deterioration in the presence of oxygen.
A monoester compound of 2,2'-alkylidene bis(4,6-di-alkyl-substituted phenol) containing an acrylate represented by the following is proposed. In the same specification, R1 in the general formula (1) is hydrogen or has 1 to 1 carbon atoms.
0 alkyl group, and R2 and R5 are each defined as an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms, or a methyl-substituted cycloalkyl group having 5 to 6 carbon atoms.

However, this patent specifies that thermal deterioration (gelation) occurs particularly in the absence of oxygen during high-temperature treatment to separate the polymer from a polymer solution during the production of butadiene-based polymers, or during high-temperature processing of butadiene-based polymers.
There is no mention of preventing staining or staining. In addition, the compounds specifically disclosed in the same specification are:
It was not sufficiently effective in preventing thermal deterioration and discoloration, particularly in the absence of oxygen, during the production process and high-temperature processing of butadiene-based polymers.

Furthermore, JP-A No. 62-223248 describes that polyethylene is stabilized by using the phenol compound represented by the general formula (I) in combination with another phenol compound and/or a phosphorus compound. has been done.

The publication only describes the stabilization of polyethylene, but the stabilization of butadiene-based polymers, especially the thermal deterioration (gelation) of butadiene-based polymers in the absence of oxygen.
It does not teach anything about preventing staining or discoloration.

Furthermore, when a stabilizer is added during the production of a butadiene-based polymer, the stabilizer is usually dissolved in a hydrocarbon-based organic solvent used as a polymerization solvent, and then added to the polymer solution after the polymerization reaction is completed. Therefore, it is desirable that such stabilizers have high solubility in hydrocarbon-based organic solvents.If the solubility is low, for example, pipes are likely to be clogged due to slurry formation of the stabilizer solution, and in order to avoid this, a large amount of Problems arise such as the need for investment. However, among the conventionally known stabilizers, compounds that are particularly effective in preventing thermal deterioration (gelation) and discoloration in the absence of oxygen at high temperatures during the production and processing of butadiene polymers are hydrocarbon-based organic stabilizers. The solubility in solvents was not very high.

<Problems to be Solved by the Invention> The purpose of the present invention is to solve the following problems when performing high temperature treatment to separate a polymer from a polymer solution during the production of butadiene-based polymers.
Another object of the present invention is to provide a compound that is effective in preventing thermal deterioration (gelation) and coloring, particularly in the absence of oxygen, when processing butadiene-based polymers at high temperatures.

Another object of the present invention is to provide a compound that also has excellent solubility in hydrocarbon organic solvents used in the production of butadiene polymers.

Yet another object of the invention is to stabilize butadiene-based polymers using such compounds.

<Means for solving the problem> As a result of research, it was found that a phenolic compound with a specific structure satisfies the above objectives, that is, because such a compound has excellent solubility in hydrocarbon organic solvents, it is used during the production of butadiene polymer. We discovered that butadiene-based polymers that can be easily added and that contain such compounds are stable against thermal deterioration (gelation) and coloration in the absence of oxygen during high-temperature treatment or processing during manufacturing. The present invention has now been completed.

That is, the present invention provides a phenolic compound represented by formula (n) and a stabilizer for butadiene polymers containing this phenolic compound as an active ingredient. The present invention also provides a method for stabilizing a butadiene polymer using this phenolic compound, and a butadiene polymer composition containing this compound.

The phenolic compound represented by the formula (n) of the present invention is conceptually close to the phenolic compound group represented by the general formula (1) described in the prior literature, but specifically This was completely unknown. According to the present invention, it has been found that a compound having a specified substituent, that is, a compound represented by formula (II), has particularly excellent properties compared to known compounds.

Regarding the substituent R1 of the phenolic compound group represented by the general formula (I), from the viewpoint of gelation prevention performance of the butadiene polymer at high temperatures, the smaller the number of carbon atoms in the alkyl group, the better it is, and the most preferable is a methyl group. . Also, R2 is
In order to prevent coloring of the butadiene-based polymer, a group represented by -C(CHs)z-R' containing quaternary carbon is preferable, and a t-butyl group, a t-amyl group, or a t-octyl group is particularly preferable. R3 is -C (C
H, ), -R' groups are preferred, and t-butyl or t-amyl groups are particularly preferred. Therefore, the phenol compound of the present invention represented by formula (II) is effective in satisfying the gelation prevention performance and coloration prevention performance of the butadiene polymer at high temperatures.

Furthermore, a noteworthy feature of the phenolic compound (It) of the present invention is that its solubility in hydrocarbon organic solvents is significantly higher than that of known similar compounds.

Therefore, this phenolic compound (n) has excellent anti-gelation and anti-coloration properties of butadiene-based polymers at high temperatures and in the absence of oxygen, and also has high solubility in hydrocarbon organic solvents, which is an unprecedented property. be effective.

The phenolic compound (II) of the present invention is composed of 2゜2'-ethylidenebis(4,6-di-t-amylphenol) and an acid derivative such as methacrylic acid or chlorinated methacrylic acid methacrylic acid ru-tacrylic anhydride. (See, for example, U.S. Pat. Nos. 4.525.514, 4.562.281 and 4.365.032).

When the phenolic compound (II) of the present invention is used as a stabilizer for butadiene-based polymers, the applicable butadiene-based polymers include solution-polymerized polybutadiene rubber (BR), solution-polymerized styrene-butadiene copolymer rubber (SBR), styrene-butadiene block copolymer (
SBS), BR or high-impact polystyrene (Hl-PS) modified with SBR or SBS, etc., and these butadiene-based polymers may be used alone or in combination with other polymers. .

The amount of the phenol compound incorporated into the butadiene polymer is preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1 part by weight per 100 parts by weight of the butadiene polymer. Here, the amount of phenolic compound is 0.0
If it is less than 5 parts by weight, the desired effect will not be sufficient, and if it is less than 2 parts by weight,
Even if the amount exceeds the weight part, it tends to be economically disadvantageous because commensurate effects cannot be obtained.

When the phenolic compound of the present invention is added to a butadiene polymer, this compound is dissolved in a hydrocarbon organic solvent used as a polymerization solvent for the butadiene polymer, and this is added to the butadiene polymer after the anionic polymerization reaction. A method of adding it to the polymer polymerization reaction solution can be applied. Furthermore, the phenolic compound of the present invention may be triblended with the polymer to be added during processing such as extrusion molding or injection molding.

According to the present invention, by incorporating the above-mentioned phenolic compound as a stabilizer into the butadiene polymer,
A butadiene-based polymer composition with excellent properties is obtained, but if necessary, other phenolic compounds and other additives such as ultraviolet absorbers, light stabilizers, antioxidants, metal deactivators, Metal soaps, nucleating agents, lubricants, antistatic agents, flame retardants, pigments, fillers, etc. may be added.

Specific examples of these additives include the following.

Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl 3-(3,5-di-butyl-4-methylphenol),
-hydroxyphenyl)propionate, triethylene glycol bis(3-(3-t-butyl-
4-hydroxy-5-methylphenyl)propionate], pentaerythrityltetrakis (3-(3゜5-di-t
-butyl-4-hydroxyphenyl)propionate]
, 1.3.5-)dimethyl-2,4,6-tris(3,5-)
-di-t-butyl-4-hydroxybenzyl)benzene and the like.

Examples of the ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(3-t -butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5 -di-t-amyl-2-hydroxyphenyl)benzotriazole, 2,4-di-t-butylphenyl 3.5-di-t-butyl-4-hydroxybenzoate, (2,2'-thiobis(4- t-octylphenol)
))/n-butylamine Ni salt and the like.

Examples of hindered amine light stabilizers include 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2 ,2,6,6-bentamethyl-4-piperidyl) 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n=butylmalonate, 4-(3-(3,5-di- t-Butyl-4-hydroxyphenyl)propionyloxy]-1-(2-(3-
(3,5-di-t-butyl-4-hydroxyphenyl)
propionyloxy)ethyl) -2,2,6,6-'
Tetramethylpiperidine, dimethylsuccinate and 4-hydroxy-1-(2-
hydroxyethyl)-2,2゜6.6-tetramethyl-
Polycondensate with 4-piperidine, poly([:6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-)riazine-2,4-diyl)((2,2 , 6,6-tetramethyl-4-piperidyl)imino]hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl)imino), poly([6-morpholino-1,3,5- Triazine
2,4-diyl)((2,2,6゜6-tetramethyl-
4-piperidyl)imino]hexamethylene ((2,2,
6,6-tetramethyl-4-piperidyl)imino]),
2-Methyl-2-(2,2,6,6-tetramethyl-4
-piperidyl)amino-N-(2,2,6,6-tetramethyl-4-piperidyl)propionamide and the like.

Examples of sulfur-based antioxidants include dilauryl thiodipropionate, simiristyl thiodipropionate, distearyl thiodipropionate, pentaerythrityltetrakis (3-dodecylthiopropionate), 3.9-bis (2-dodecylthioethyl)-2,4,8
, 10-tetraoxaspiro[5,5]undecane and the like.

Examples of phosphorus antioxidants include disterial pentaerythritol diphosphite, tris(2,4-di-t-butylphenyl) phosphite, and tris(2-t-butyl-4-methylphenyl) phosphite. , bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-
t-butylphenyl) 4,4'-biphenylene diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)
Examples include pentaerythritol diphosphite.

The stabilizer for butadiene-based polymers containing the phenolic compound represented by formula (n) as an active ingredient of the present invention may be this compound alone, or may be a stabilizer that affects the physical properties of the butadiene-based polymer. It may be mixed with a carrier without any carrier, or it may be mixed with one or more of the various additives mentioned above. Of course, a solution of a hydrocarbon organic solvent as described above may also be used.

<Examples> Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. In the following examples, the compounds AO-,
1-A○-4 represent the following, respectively.

AO-1: 2-t-butyl-6-(3=t-butyl-2
-Hydroxy-5-methylbenzyl)-4-methylphenylacrylate AO-2:2,4-di-t-butyl-6-[1(3,5
-di-t-butyl-2-hydroxyphenyl)ethyl]phenylacrylate AO-3: 2,6-di-t-butyl-4-methylphenol AO-4: n-octadecyl 3-(3,5-di-t −
Butyl-4-hydroxyphenyl)propionate Example 1 21 with thermometer, stirrer, cooling tube and dropping funnel
In a Yotsuro flask, add 2,2' ethylidene bis(4,6-
di-t-amylphenol) 494.8g (1,0
mol), methacrylic acid 86.1 g (1.0 mol), n-
400g hebutane and 212.5g triethylamine
(2.1 mol) was charged, and after purging the inside of the container with nitrogen, 107.3 g (0.7 mol) of phosphorus oxychloride was added dropwise without stirring. After the dropwise addition was completed, the mixture was kept warm at 80°C for 1 hour, then 500g of water was added, and the mixture was washed with water and separated at 60°C.

After washing the oil layer with water and separating the liquid, the washing liquid was repeated until the washing liquid became almost neutral, and then the oil layer was cooled to 5° C. with stirring to precipitate crystals. Stirring was further continued at the same temperature to sufficiently precipitate crystals, and then the crystals were filtered off, washed with cold n-heptane, and dried under reduced pressure. 268.6 g of -di-t-amyl-6-[:1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl methacrylate (IF) was obtained.

Elemental analysis value measurement value (calculated value) C: 81.14% (81.09%) H: 1
0.43% (10,39%) Mass spectrometry value (FD-M
S) M/Z 562 (M=) Example 2 The solubility of the phenolic compound (■) of the present invention and similar known compounds AO-1 and AO-2 in hydrocarbon solvents was investigated. As the hydrocarbon solvent, n-hexane and cyclohexane were used.

The results are shown in Table-1.

Table 1 Solubility at 20°C (g/100g solvent) Example 3 Polymerization of 1,3-butadiene was carried out at 60 to 65°C in n-hexane under a nitrogen atmosphere using n-butyllithium as a catalyst. . Isopropyl alcohol is used as a polymerization terminator, and after completion of polymerization, 2,4-di-t-amyl-6-[
A solution of 1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl methacrylate (■) in n-hexane was added, and then under a nitrogen atmosphere, the
n-hexane was removed by flash evaporation at
A polybutadiene rubber composition (BR) was obtained. Table-2 shows
2,4-di-t-amyl-6-CI-(3,5-di-t
-amyl-2-hydroxyphenyl)ethyl] phenyl methacrylate (■) was added to polybutadiene 10
It is expressed in parts by weight relative to 0 parts by weight.

The obtained polybutadiene rubber composition was subjected to a kneading test under the following conditions in a nitrogen stream using Labo Plastomill (manufactured by Toyo Seiki, Model 40-100). Then, the effect of preventing gelation that occurs during kneading was evaluated by the torque behavior accompanying gelation, and the results are shown in Table 2. The gelation prevention effect is indicated by the time to torque peak (gelation time), and the longer the time, the better the gelation prevention effect.

[Laboplastomill test conditions]

(1) Mixer - R-60 type (2
) Measuring torque range 0 to 500 kg-cm (3)
Preparation amount 30g (4) N2
Flow rate 1j! /m1n (5) Test temperature: 180°C (6) Number of revolutions: After preheating for 3 minutes at 10 rpm, 5 Q rpm In addition, the degree of coloration after high temperature treatment when obtaining polybutadiene rubber was determined with the naked eye and expressed using the following symbols. -2.

○: No coloration △: Colored pale yellow X: Colored yellow Comparative Example 1 2,4-di-t-amyl-6-C in Example 3 above
Compounds AO-1 to AO-4 were used instead of I-(3,5-di-t-amyl-2-t)'roxyphenyl)ethyl]phenyl methacrylate (■), and the other operations were as in Example 3. Experiments were conducted in the same manner as above, and the anti-gelation effect and degree of coloration of each test compound were evaluated.

Table 2 shows the amount of each test compound added and the test results.

The unit of the amount added is parts by weight based on 100 parts by weight of polybutadiene.

Example 4 Under a nitrogen atmosphere, 0.8 parts by weight of n-butyllithium was added to a cyclohexane solution containing 20 parts by weight of 1,3-butadiene, and after polymerization at 70°C for 1 hour, styrene 2
0 parts by weight, 15 parts by weight of 1.3-butadiene, 4 parts by weight of styrene
5 parts by weight were added and polymerization was carried out at 70° C. for 1 hour. After completion of polymerization, 2,4-di-t-amyl-6-
A cyclohexane solution of C1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl methacrylate (■) was added, and the cyclohexane was removed by heating under a nitrogen atmosphere to obtain B with a butadiene content of 35% by weight. -A-
A block copolymer composition having a BA structure was obtained. Table-3 shows
The amount of the test compound added was expressed in parts by weight based on 100 parts by weight of the block copolymer.

The obtained block copolymer composition was subjected to a filament drop extrusion test under the following conditions using a Laboplasto Mill extruder, and the gel content of the filament thus obtained was measured and evaluated as toluene insoluble matter. The gel content is 1 for filamentous samples.
g was accurately weighed, immersed in 200ml of toluene, stirred for 24 hours, filtered through a 200ml wire mesh, dried the residue, measured the weight, and calculated from the weight before and after the test. The results are shown in Table-3.

〔Test conditions〕

(1) Testing machine body Labo Plastomill type 40-100 (
Toyo Seiki! (2) Extruder D2 0-2 5 type (
(manufactured by Toyo Seiki) (3) Strand die diameter 0.5 Stop φ (
4) Cylinder temperature 230-260℃
(5) Number of rotations: 3 rpm (6) Falling distance: 93 cm In addition, the degree of coloration of the filamentous sample obtained by processing the styrene-butadiene block copolymer composition at high temperature in this way was determined with the naked eye and expressed using the following symbols. -3.

O: No coloring Δ: Pale yellow coloring X: Yellow coloring Comparative Example 2 2,4-di-t-amyl-6 in Example 4 above
- [1-(3,5-di-t-amyl-
An experiment was conducted in the same manner as in Example 4 except that 13 compounds AO-1 to AO-4 were used instead of 2-hydroxyphenyl)ethyl]phenylmethacrylate (II), and the gel of each test compound was The prevention effect and degree of coloration were evaluated.

Table 3 shows the amount of each test compound added and the test results. The unit of the amount added is parts by weight based on 100 parts by weight of the block copolymer.

<Effects of the Invention> When the phenolic compound specified in the present invention is blended into a butadiene-based polymer, it is highly effective in preventing gelation and coloring of the polymer due to thermal deterioration, particularly in the absence of oxygen. Therefore, even when the polymer is separated from the polymer solution at high temperature after the polymerization reaction is completed, a product without gel formation or coloration can be stably obtained.

In addition, butadiene-based polymers containing such phenolic compounds are stable against thermal deterioration during processing processes such as injection molding and extrusion molding, and are, for example, prevented from forming fish eye gel during film forming processes, or during injection molding. It is possible to prevent the formation of microgels that cause a decrease in gloss and transparency during the molding process, and to obtain high-quality products without coloring.

Furthermore, since the phenol compound of the present invention has very high solubility in hydrocarbon organic solvents, it can be easily added to the butadiene polymer solution after the polymerization reaction in the form of a solution in which the phenol compound is dissolved in a solvent. can do.

Therefore, the workability in this case is very good, and the process can be carried out without modifying conventional manufacturing equipment.

Claims (7)

[Claims] (1) Formula ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ A phenolic compound represented by. (2) A stabilizer for butadiene-based polymers containing the phenolic compound according to claim 1 as an active ingredient. (3) A method for stabilizing a butadiene-based polymer, which comprises incorporating the phenol-based compound according to claim 1 into the butadiene-based polymer. (4) A butadiene polymer composition comprising a butadiene polymer containing the phenol compound according to claim 1. (5) The butadiene-based polymer composition according to claim 4, wherein the butadiene-based polymer is a solution-polymerized polybutadiene rubber, a solution-polymerized styrene-butadiene copolymer rubber, or a styrene-butadiene block copolymer. (6) The butadiene polymer composition according to claim 4 or 5, which contains 0.05 to 2 parts by weight of the phenol compound per 100 parts by weight of the butadiene polymer. (7) The butadiene polymer composition according to claim 6, which contains 0.1 to 1 part by weight of the phenol compound per 100 parts by weight of the butadiene polymer.