JP3151461B2 - Diene polymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conjugated diene or a polymer comprising the diene and a monovinyl aromatic compound, a specific phenolic stabilizer and a specific sulfur-containing phenolic stabilizer, which are subjected to high temperature or shearing. The present invention relates to a diene-based polymer composition which is excellent in heat stability at the time and is particularly suitable for resin modification, automobile tires, industrial products, and the like, in which generation of gel and discoloration are extremely small.

[0002]

2. Description of the Related Art Hitherto, diene polymers have been widely used for resin modification, automobile tires and various industrial products. However, such diene polymer in order to further improve the properties (such as tensile strength and impact resilience), has a large molecular weight, thus a Mooney viscosity _{(ML 1 + 4, 100 ℃} : less, and a Mooney viscosity (Abbreviation) is high, and rubber production plants and processing plants have problems such as generation of gel and discoloration during shearing or processing operations at high temperatures.

In order to solve these problems, phenol stabilizers, phosphorus stabilizers, sulfur stabilizers and the like are used alone or in combination as stabilizers for preventing gelation. Phenolic stabilizers, particularly 2,6-di-tert-butyl-4-methylphenol (hereinafter abbreviated as BHT), are most often used.

[0004]

However, although BHT has thermal stability for a short period of time, the low sublimation temperature reduces the residual ratio in rubber, and the thermal stabilizing effect is reduced. There are problems such as yellowing of the rubber due to the quantification reaction, and improvement thereof is demanded. Further, the phosphorus-based stabilizer has a problem in that it reacts with water to generate phosphoric acid, corrodes metals and the like, generates rust, and has contamination. Most of the sulfur-based stabilizers have a problem of odor, and particularly at high temperatures, the problems of odor and coloring property become large.

[0005] A diene-based polymer composition containing a large amount of such a stabilizer in order to increase its thermal stabilizing effect is:
It is not preferable because vulcanization characteristics and crosslinking characteristics are deteriorated, and tensile strength and rebound resilience of the molded product are lowered. It has been difficult to prevent gel formation and coloring at high temperatures and during heat shearing without lowering the desirable properties of such diene polymers.

[0006]

Means for Solving the Problems The present inventors have attempted to solve the problems such as coloring and gel formation at high temperatures and heat shear without impairing the properties of such diene polymers. As a result of diligent studies on polymers and various stabilizers, diene polymers and specific phenolic compounds,
And a polymer composition comprising a specific sulfur-containing phenolic compound has an extremely excellent effect of suppressing gel generation and coloring at high temperatures and heat shearing, and the composition is easily vulcanized and cross-linked. Yes, they found that the molded product had good tensile strength and rebound resilience, etc., and completed the present invention.

Namely, the present invention; (a) consisting of at least one conjugated diene or conjugated diene and at least one monovinyl aromatic compound, heavy
A combined 100 parts by weight, (b) the general formula [b-I], [b-II];

Embedded image (Wherein, R ₁ is a tert-butyl group, a tert-amyl group or a cyclohexyl group, and R ₃ and R _{4 each} have 1 carbon atom.
To 18 of an alkyl le _{group, R 2, R 5, R} 6, R 7,
R _8, at least one is 0.05 to 2.0 parts by weight of the phenolic stabilizer represented by a hydrogen atom or an alkyl group having 1 to 18 carbon atoms), and

(C) a general formula [cI];

Embedded image (Wherein, R _9, R ₁₁ represents _{-CH 2 -S-R 13, R} 13
Represents an alkyl group having 20 or less carbon atoms, R ₁₀ represents a hydrogen atom or an alkyl group having 15 or less carbon atoms, R ₁₂ is the number of carbon atoms
A diene polymer composition comprising at least one of 0.01 to 0.5 parts by weight of a sulfur-containing phenolic compound represented by the following formula: However, they have been found to have particularly excellent high-temperature heat stability and shear heat insulation stability.

Hereinafter, the present invention will be described in detail. The diene polymer used in the present invention is, for example, in an inert hydrocarbon solvent such as n-hexane or cyclohexane, in the presence of a Lewis base such as tetrahydrofuran or N, N, N ', N'-tetramethylethylenediamine, or In the absence of at least one conjugated diene, such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-heptadiene or the like, or At least one monovinyl aromatic compound, such as styrene, α-methylstyrene,
1-vinylnaphthalene or the like, an organic lithium compound having one or more lithium atoms in a molecule, for example, n-butyllithium or sec-butyllithium, or
A diene polymer obtained by (co) polymerizing a polyfunctional organolithium catalyst or the like as described in JP-A-136603 or JP-A-57-40513 as a polymerization initiator; A branched polymer treated with an agent or a coupling agent, or an unbranched polymer or a mixture thereof is used, and the microstructure distribution of a monovinyl aromatic compound or a 1,2-vinyl bond is random, It may be in the form of a block, a random block, or a repeating unit thereof, or may be one that changes gradually along the molecular chain.

The Mooney viscosity of the polymer used in the present invention is not particularly limited. For example, it is preferably about 20 to 180 for use in automobile tires and industrial goods. Can be used. In addition, the content of monovinyl aromatic compound, 1,
Although there is no particular limitation on the amount of 2-vinyl bond,
Determined according to the application. For example, in tire applications where rubber elasticity is required, the monovinyl aromatic compound is 70%.
% By weight or less, particularly preferably 40% by weight or less, and for resin applications, the amount of 1,2-vinyl bond is preferably about 20% by weight or less. The diene polymer composition of the present invention comprises a natural rubber or other synthetic rubber of 80%.
Although it may be contained in an amount of less than 10% by weight, if it is contained in an amount of 80% by weight or more, various thermal stability characteristics of the present invention are deteriorated.

The compound represented by the general formula [bI] of the phenolic stabilizer used in the present invention includes, for example, 2
-(2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, 2- (2-hydroxy-3,5-di-tert-butylbenzyl) -4 , 6-di-tert
-Butylphenyl acrylate, 2,2′-ethylidene-4,6-di-tert-butylphenol- (4 ′,
6'-di-tert-butylphenyl acrylate),
2-tert-amyl-6- [1- (3,5-di-te
rt-amyl-2-hydroxyphenyl) ethyl] -4
-Tert-amylphenyl acrylate and the like.

The compound represented by the general formula [b-II] includes, for example, 3,9-bis- {2- [3- (3-te
rt-butyl-4-hydroxy-5-methylphenyl)
Propionyloxy] -1,1-dimethylethyl {2
4,8,10-tetraoxaspiro [5,5] undecane and the like.

The general formulas [b-I] and [b-I
The phenolic stabilizer represented by the formula (I) can be used alone or in combination of two or more. The preferred content is 0.05 to 5.0 parts by weight based on 100 parts by weight of the diene polymer. If the amount is less than 0.05 part by weight, the effect of improving the thermal stability at high temperature or during shearing becomes small, and if the amount is more than 5.0 parts by weight, the vulcanization and crosslinking times become longer, and the tensile strength and the Rebound resilience deteriorates.

The sulfur-containing phenolic compound represented by the general formula [CI] used in the present invention includes, for example,
2,4-bis (n-octylthiomethyl) -6-methylphenol, 2,4-bis (2 ′, 3′-di-hydroxypropylthiomethyl) -3,6-di-methylphenol, 2,4 -Bis (2'-acetyloxyethylthiomethyl) -3,6-di-methylphenol, 2,4-bis (2'-hydroxyethylthiomethyl) -6-methylphenol, 2,4-bis (tert- Octylthiomethyl) -6-methylphenol.

The sulfur-containing phenolic compounds used in the present invention may be used alone or in combination of two or more. The preferred content is 0.01 to 0.5 parts by weight based on 100 parts by weight of the diene polymer. Department. When the content of the sulfur-containing phenolic compound is less than 0.01 part by weight, the effect of improving the thermal stability at high temperatures or during heat shearing decreases, and when it exceeds 0.5 parts by weight, the thermal stability during shearing decreases. Although good, it is not preferable because the polymer composition is significantly colored and odor is generated. At the same time, vulcanization and cross-linking properties deteriorate, and the tensile strength and rebound resilience of the molded product decrease, which is not preferable.

The diene polymer composition of the present invention comprises at least one other sulfur stabilizer,
You may mix 0.05-1.0 weight part with respect to 0 weight part. Examples of the sulfur-based stabilizer include pentaerythritol-tetrakis- (β-lauryl-thio-propionate), dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate,
Distearyl-3,3'-thiodipropionate and the like are listed. Such a sulfur-based stabilizer can effectively improve the color tone and the thermal stability of the composition by adding an appropriate amount.

The method for preparing the diene-based polymer composition of the present invention is not particularly limited. For example, a phenol-based stabilizer or a phosphorus-based stabilizer may be prepared while the diene-based polymer is dissolved in an organic solvent. At least one desired amount and at least one desired amount of the specific sulfur-containing phenolic compound and, if necessary, the sulfur-based stabilizer are blended in a preferred order or simultaneously, and then known methods, for example, steam stripping The solvent may be removed by a method, a hot roll, or the like, or may be directly blended with the dried product and mixed by a known method, for example, a roll, a Banbury, an extruder, or the like. Alternatively, it is also possible to mix simultaneously when adding and mixing other compounding agents, and in short, it can be prepared by any known compounding method.

[0018]

Hereinafter, the present invention will be described with reference to Examples.
These examples do not limit the invention. In addition, the measurement of various characteristics was implemented by the following methods. Mooney viscosity was measured at 100 ° C. and 2 rpm using an L rotor according to the method of JIS-K6300. The 1,2-vinyl bond amount in the butadiene portion of the diene polymer was measured with a Perkin Elmer 1710 infrared spectrophotometer and calculated by the Hampton method. The bound styrene was calculated from the absorption based on the phenyl group at 262 nm by the ultraviolet absorption spectrum method. The high-temperature thermal stability is as follows: a stabilizer prepared polymer composition sheet having a length and width of 5 cm and a thickness of 0.5 cm is placed in an oven heated to 180 ° C.
Test time: 0.5 hours, 1 hour, 2 hours, 3 hours, the degree of coloring of each sheet was examined. The degree of coloring was ranked as follows. No discoloration (white) = 0, pale yellow = 1, pale yellow = 2,
Yellow = 3, brown yellow = 4, brown = 5, brown = 6, dark brown = 7.

The thermal stability during shearing was measured using a Labo Plastomill LPM-2500-200 manufactured by Toyo Seiki Co., Ltd. using a mixer B-75 at a test temperature (cylinder temperature) of 100.
At 55 ° C. and 10 rpm of rotor rotation.
After charging for 100 minutes, the pressure was immediately increased to 100 rpm, the torque value gradually decreased, and then the gelation started and the torque began to increase. The lowest point of the torque value at this time was measured as the gelation start time. FIG. 1 shows a lab plast mill kneading test chart. The vulcanization time of the unvulcanized blend of the polymer composition is J
Test temperature 160 using SR type Curastometer II
At 90 ° C., the time at which 90% (T ₉₀ ) of the maximum vulcanized torque (T ₁₀₀ ) based on the minimum torque (T ₀ ) during unvulcanization was measured. The unvulcanized compound sample used for the tensile test and the rebound resilience test is 160 ° C.-200 kg / cm ²
Vulcanized for 20 minutes. The tensile strength of the vulcanized product was measured on the above sample according to the method of JIS-K6301. The rebound resilience was measured on the above sample at a test temperature of 70 ° C. using a Lupke rebound resilience tester.

Reference Example <Production of Diene Polymer> The diene polymer used in the present invention was prepared by the following method. 40 kg of dried cyclohexane, 120 g of tetrahydrofuran and 4.8 k of 1,3-butadiene were placed in a 100 L stainless steel autoclave purged with nitrogen.
g and 1.2 kg of a styrene monomer were charged and heated to 43 ° C. with stirring, and then 62 mmol of n-butyllithium was added to carry out polymerization. After 23 minutes the reaction temperature is 97 ° C
After 4 minutes, 5.5 mmol of tin tetrachloride was added and reacted for 10 minutes. Separately, the polymerization was carried out under the same conditions as above except that the amount of n-butyllithium was 53 mmol, and a non-coupling-diene-based polymer without addition of tin tetrachloride was also prepared. Active lithium was decomposed by adding methyl alcohol to each polymer solution. Table 1 shows the measurement results of the thus obtained diene polymer such as Mooney viscosity, total bound styrene content, and 1,2-vinyl bonded content.

[0021]

[Table 1]

(Examples 1 to 5 and Comparative Examples 1 to 5) The samples for the thermal stability test were prepared by adding the phenolic stabilizers to the diene polymer solution obtained in the reference example by the methods shown in Table 2. And a sulfur-containing phenolic compound, and then the solvent was removed with a hot roll to obtain a diene polymer composition. The thermal stability at high temperature was compared by an oven thermal stability test. Table 3 shows the results. Shear insulation stability was also tested by Labo Plastmill. Table 4 shows the results. The physical property test of the polymer composition was performed using a small pressure kneader (Moriyama Seisakusho, double arm kneader, model D-0.5-3) with a cylinder temperature of 10 according to the formulation shown in Table 5.
The mixture was kneaded and compounded at 0 ° C. for 10 minutes, and the vulcanization time (T ₉₀ ) of the obtained unvulcanized compound and the tensile strength and rebound resilience of the vulcanized molded product were measured. Table 6 shows the results.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

[Table 6]

The results of the heat oven coloring test shown in Table 3 show that Examples 1 to 5 of the present invention have a good coloring degree and a good gelling time in Table 4 and are good, and the physical properties of the blends in Table 6 are excellent. ing. On the other hand, Comparative Examples 1, 2, and 5 have good coloring properties, but in Table 4, Comparative Examples 2 and 5 are not preferable because of rapid gelation. As shown in Table 6, the physical properties of Comparative Example 1 were significantly deteriorated. From the above results, it can be seen that the diene polymer composition of the present invention has excellent high-temperature heat stability and shear heat insulation stability, and has good physical properties.

[0029]

The diene polymer composition of the present invention is extremely excellent in thermal stability at high temperature or heat shear, very good at preventing gel formation and resistance to discoloration, and has good impact resistance. It is suitable as a rubber for modifying resins such as polystyrene. In addition, it has good vulcanization and cross-linking behavior during processing and molding, and has good tensile strength and rebound resilience of molded products, and is suitable for, for example, tire applications, industrial products, and akimono applications, and has great industrial significance.

[Brief description of the drawings]

FIG. 1 is a graph showing a laboplastomill kneading test chart for a diene polymer composition sample of the present invention.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-289857 (JP, A) JP-A 1-284539 (JP, A) JP-A-62-114955 (JP, A) JP-A-3- 31334 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 9/00-9/10 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (1) 100 parts by weight of at least one conjugated diene or a polymer comprising the conjugated diene and at least one monovinyl aromatic compound ; and (b) the following general formulas [b-I] and [b- II]; (Wherein, R ₁ is a tert-butyl group, a tert-amyl group or a cyclohexyl group, and R ₃ and R _{4 each} have 1 carbon atom.
To 18 of an alkyl le _{group, R 2, R 5, R} 6, R 7,
R ₈ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms), at least one of the phenolic stabilizers represented by 0.05 to 2.0 parts by weight, and (c) a general formula [c-I] ## STR2 ## (Wherein, R _9, R ₁₁ represents _{-CH 2 -S-R 13, R} 13
Represents an alkyl group having 20 or less carbon atoms, R ₁₀ represents a hydrogen atom or an alkyl group having 15 or less carbon atoms, R ₁₂ Mother carbon
At least one of the sulfur-containing phenolic compounds represented by the following formula (15 ).
A diene-based polymer composition comprising: