JP4556658B2 - Modified polymer and polymer composition containing the same - Google Patents

Description

  The present invention relates to a modified polymer and a polymer composition containing the modified polymer, and more specifically, a modified polymer introduced by reacting a blocked nitroxide radical compound at the living anion end of a conjugated diene and / or aromatic vinyl compound homopolymer or copolymer. In addition, the present invention relates to a polymer composition containing the same and a pneumatic tire using the same.

  Compounds having nitroxide radicals such as tetramethylpiperidinyloxy (TEMPO) compounds, which are free radicals stable at room temperature in the presence of oxygen, can quickly trap terminal radicals of rubber molecular chains generated by shearing. Are known. From this point of view, when a polymer in which a TEMPO derivative is introduced at the molecular end is kneaded with another polymer in a kneader, nitroxide radicals such as TEMPO trap the terminal radicals of other polymer molecular chains generated by shearing. Patent Document 1 proposes that a block polymer or a graft polymer is formed to improve mechanical strength such as wear resistance. However, for example, when living anion polymerization of a hydrocarbon monomer using butyllithium as a polymerization initiator and attempting to introduce a nitroxide radical at the end of the living anion, a compound having a functional group capable of reacting with carbanion and a nitroxide radical is end-modified. When used as an agent, the carbanion reacts with both the nitroxide radical and the functional group, thereby causing a side reaction that produces a molecular weight approximately twice that of the initial polymer. Therefore, since the desired amount of terminal nitroxide radicals cannot be obtained, the polymer properties are improved, but it is not satisfactory.

  On the other hand, it is known that an alkoxyamine derived from a nitroxide radical is dissociated by heat to generate a nitroxide radical, and research on living radical polymerization using this property has been widely conducted. Various compounds derived from nitroxide radicals to alkoxyamines have been reported (see Non-Patent Document 1).

JP 2003-128726 A Radical polymerization handbook, pages 4 to 375, 1999, issued by NTS

  Accordingly, the object of the present invention is to overcome the above-mentioned problems of the prior art and modify the conjugated diene and / or aromatic vinyl compound homopolymer or copolymer by reacting the living anion terminal with a nitroxide radical generating compound. Accordingly, an object of the present invention is to provide a modified polymer capable of improving physical properties such as wear resistance.

  According to the present invention, a homopolymer or copolymer of a conjugated diolefin and / or an aromatic vinyl compound, which has the formula (I):

(In the formula, R represents at least one of a C, O, N, S, P, C _{1 to} C ₃₀ alkylene group and a C _{6 to} C ₃₀ aryl group or a single bond, and R ^{1 to} R ^3. Although an alkyl group or an aryl group of C ₆ -C ₃₀ hydrogen or C ₁ -C ₃ are each independently at least one of R ¹ to R ³ is an aryl group of C ₆ -C _30, A represents a functional group capable of reacting with a carbon anion)
A modified polymer in which an alkoxyamine compound represented by the above formula is reacted-bonded is provided.

  According to the invention, the alkoxyamine compound is of the formula (II):

(In the formula, R ^{1 to} R ³ each independently represent hydrogen, a C _{1 to} C ₃₀ alkyl group, or a C _{6 to} C ₃₀ aryl group, and at least one of R ^{1 to} R ³ represents C ₆ to C ^3. C ₃₀ aryl group)
The modified polymer of Claim 1 which is an alkoxyamine compound represented by these is provided.

  According to the present invention, the alkoxyamine of the above formula (I) or (II) in which a compound having a nitroxide radical such as TEMPO is blocked at the end of the living anion of a single polymer or copolymer of a conjugated diolefin and / or an aromatic vinyl compound Since the compound can be bound without side reaction, the terminal modification rate is improved, and the abrasion resistance of the rubber composition can be improved by kneading with other rubber.

  According to the present invention, for example, as shown below, styrene and butadiene are subjected to living anion polymerization in, for example, cyclohexane at 50 ° C., and the resulting SBR having a living anion terminal is reacted with the alkoxyamine compound of formula (II). Then, the blocked nitroxide radical is bound to the terminal of SBR. Thus, by using a TEMPO derivative in which a nitroxide radical is blocked by derivatizing a nitroxide radical into an alkoxyamine, side reactions during terminal modification can be suppressed, and the blocked nitroxide radical is heated by the end of the molecular chain. Since nitroxide radicals can be generated, the block / graft polymer is generated by capturing radicals at the molecular ends of other polymers generated by shearing or the like. In this way, by introducing a terminal modification of the polymer with the blocked TEMPO derivative, the introduction rate of the alkoxyamine to the molecular terminal is improved, and by kneading the modified polymer with another rubber, the abrasion resistance of the rubber is improved. improves.

  Examples of the conjugated diolefin used in the present invention include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-cyclohexadiene, and the like. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 4-tert-butylstyrene, Divinylbenzene, tert-butoxystyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, vinylpyridine, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminomethylstyrene, N, N-dimethylamino Or the like can be mentioned methylstyrene. These are n-butyllithium, sec-butyllithium, t-butyllithium, 1,4-dilithiobutadiene, phenyllithium, stilbenelithium, lithium naphthalene, sodium naphthalene, potassium naphthalene by a conventional method in the form of single or arbitrary mixture It can polymerize using initiators, such as.

  By reacting the compound of the above formula (I) or (II) with the living terminal of the living anion polymerized conjugated diene and / or aromatic vinyl compound homopolymer or copolymer, the alkoxyamine compound is easily bonded to the living terminal. Terminal-modified polymers can be obtained, and these alkoxyamine compounds differ from compounds having nitroxide radicals in the case of using a compound having a functional group capable of reacting with carbanion and a nitroxide radical as a terminal modifier. Side reaction (a carbanion reacts with both a nitroxide radical and a functional group to produce a polymer having a molecular weight twice as large as that of the initial polymer), and the living anion terminal of the formula (I) or (II) is efficiently formed. A compound is introduced.

  The functional group A capable of reacting with the carbon anion in the compound of the formula (I) is typically a glycidyl group having an oxirane group as in the formula (II), but other oxirane groups, thiirane groups, and isocyanate groups. , Isothiocyanate group, halogen, carbonyl group, imino group, vinyl group and the like can be used.

  There is no particular limitation on the method of reacting the compound of the formula (I) or (II) with the living anion terminal of the homopolymer or copolymer of the conjugated diene and / or aromatic vinyl compound, and the polymer in the living state has the formula (I). Alternatively, the compound (II) is dissolved in an appropriate organic solvent (for example, benzene, toluene, cyclohexane, n-hexane, diethyl ether, THF, etc.) and added under appropriate reaction conditions (for example, a temperature of −80 ° C. to 100 ° C. For 5 to 300 minutes), the desired modified polymer can be obtained. The amount of the compound of formula (I) or (II) is not particularly limited, but is preferably 0.0001 to 30 parts by weight per 100 parts by weight of a single polymer or copolymer, and 0.001 to 20 parts by weight. More preferably.

  In accordance with the present invention, a modified polymer having a compound of formula (I) selectively attached to the living end can be mixed with other fillers and other compounding agents to form a polymer composition, and other polymers such as Natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer Rubber, styrene-isoprene-butadiene terpolymer rubber, ethylene-butene copolymer rubber, ethylene-propylene-butene terpolymer rubber, isobutylene-paramethylstyrene copolymer rubber, brominated isobutylene-paramethyl Styrene copolymer rubber, chloroprene rubber, fluoro rubber, Kurirugomu, silicone rubber, epichlorohydrin rubber, various polyolefins, various polyethylene, various polypropylene may be a polymer composition obtained by mixing such with polystyrene. The terminal-modified modified polymer of the present invention in such a polymer composition is thermally dissociated by kneading or the like at a temperature of, for example, 100 to 250 ° C. to generate nitroxide radicals at the ends, while molecular chains of other polymers are generated by shearing or the like. The radicals generated above can be trapped to produce graft and / or block copolymers.

  In addition to the above-mentioned essential components, the polymer composition according to the present invention includes other reinforcing agents (fillers) such as carbon black and silica, vulcanization or crosslinking agents, vulcanization or crosslinking accelerators, various oils, and anti-aging. Various additives that are generally blended for tires such as additives and plasticizers, and other general rubbers can be blended, and such additives are kneaded and vulcanized by a general method to obtain a composition. Can be used to vulcanize or crosslink. As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used. Further, the rubber composition of the present invention is a tire, belt, hose, anti-vibration rubber, roller, sheet, lining, rubberized cloth, sealing material, gloves, anti-fouling material, various medical treatments, physics and chemistry in the same manner as conventional rubber compositions. It can be used for articles, civil engineering and construction supplies, the ocean, automobiles, railways, OA, aircraft, rubber products for packaging, and the like, and can be particularly suitably used for the production of pneumatic tires.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

The reagents used in the synthesis examples, examples and comparative examples are shown below.
Cyclohexane, styrene: those manufactured by Kanto Chemical Co., Ltd. were dehydrated with molecular sieves 4A and used after bubbling with nitrogen.
Butadiene: A 99.3% pure product manufactured by Shin Nippon Petrochemical Co., Ltd. was used after dehydration with Molecular Sieves 4A.
n-Butyllithium: n-hexane solution 1.6 mol / L manufactured by Kanto Chemical Co., Inc. was used.
1,1,4,4-tetramethylethylenediamine (TMEDA): dehydrated with molecular sieves 4A and used after bubbling with nitrogen.
Toluene: A product manufactured by Kanto Chemical Co., Ltd. was refluxed for about a week in the presence of sodium, and after confirming the dark purple color of benzophenone ketyl, which is an indicator of dehydration, was distilled and used.

OH-TEMPO: LA7RD manufactured by Asahi Denka Kogyo Co., Ltd. was used as it was.
Epichlorohydrin: Kanto Chemical Co., Ltd. product was used as it was.
Tetrabutylammonium hydrogen sulfate: Acros Co., Ltd. product was used as it was.
(1-Bromoethyl) benzene: Aldrich product was used as it was.
Bromodiphenylmethane: Aldrich product was used as is.
Copper (powder): The product of Kanto Chemical Co., Ltd. was used as it was.
Copper triflate (II): Across Co., Ltd. product was used as it was.
4,4′-t-butyl-2,2′-bipyridine: Aldrich product was used as it was.
Benzene: A product manufactured by Kanto Chemical Co., Ltd. was dehydrated with Molecular Sieves 4A and used after bubbling with nitrogen.

Synthesis example
Synthesis of ethylbenzene block type OH-TEMPO (1) 0.759 g (4.40 mmol) of OH-TEMPO, 0.244 g (3.84 mmol) of copper powder, 0.0138 g (0.0382 mmol) of copper triflate and 4,4 ′ 0.0393 g (0.146 mmol) of -t-butyl-2,2′-bipyridine was placed in a two-necked round bottom flask, and the atmosphere in the flask was replaced with nitrogen. Thereto were added 0.676 g (3.65 mmol) of (1-bromoethyl) benzene and 7.01 mL of benzene, and the mixture was stirred at 75 ° C. for 5.5 hours under a nitrogen atmosphere. The reaction system was concentrated under reduced pressure, the solvent was removed to some extent, and then purified by silica gel column chromatography (silica C-200, 60 g, normal hexane / ethyl acetate = 3/1) to obtain a white solid (compound (1)) ( 0.785 g, 63.9%).

Synthesis of diphenylmethane block type OH-TEMPO (2) 7.05 g (0.0409 mol) of OH-TEMPO , 2.23 g (0.0350 mol) of copper powder, 0.124 g (0.343 mmol) of copper triflate, 4,4′- 0.375 g (1.40 mmol) of t-butyl-2,2′-bipyridine and 8.88 g (0.0341 mmol) of bromodiphenylmethane were placed in a two-necked round bottom flask, and the atmosphere in the flask was replaced with nitrogen. Benzene (100 mL) was added thereto, and the mixture was stirred at 75 ° C. for 23 hours under a nitrogen atmosphere. The reaction system was concentrated under reduced pressure to remove some solvent, and then purified by silica gel column chromatography (silica C-200, 200 g, normal hexane / ethyl acetate = 3/1) to obtain a white solid (compound (2)) ( 1.16 g, 10.0%).

Synthesis of ethylbenzene block type glycidyl-TEMPO (3) Toluene (50 mL) in a nitrogen-substituted two-necked flask, 5.03 g (0.0180 mol) of the compound (1) synthesized above and 0.469 g (0.533 mmol) of tin tetrachloride ) And heated and stirred at 70 ° C. To this, 2.01 g (0.0217 mol) of epichlorohydrin was added dropwise and stirred at 85 ° C. Also after 18 hours and 28 hours, 0.524 g (0.600 mmol) and 0.524 g (0.600 mmol) of tin tetrachloride were added again, and the mixture was further stirred for 13 hours. The mixture was cooled to 55 ° C., 2.60 g of 48% aqueous sodium hydroxide solution was added, and the mixture was stirred at 70 ° C. for 24 hours. The reaction system was separated, and the lower layer was extracted with toluene (200 mL × 3 times). The organic layers were combined, washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (silica C-200, 200 g, normal hexane / ethyl acetate = 6/1) to obtain pale yellow syrup-like compound (3) (0.935 g, 15.5). %).

Synthesis of diphenylmethane block type glycidyl-TEMPO (4) To 1.18 mL of 50.0 wt% aqueous sodium hydroxide solution, 5.43 g (0.0587 mol) of epichlorohydrin and 0.135 g of tetrabutylammonium hydrogen sulfate (0. 439 mmol) was added and stirred. At 0 ° C., (2) 1.00 g (2.96 mmol) was gradually added. The mixture was stirred at room temperature for 24 hours, and the reaction solution was poured into ice water. The aqueous layer was extracted with diethyl ether (20 mL × 4 times), and the organic layer was washed with water (20 mL × 3 times) and then dried over magnesium sulfate. After filtration and concentration under reduced pressure, the residue was purified by silica gel column chromatography (silica C-200, 50 g, normal hexane / ethyl acetate = 3/1) to give syrupy compound (4) (1.17 g, 100%). Obtained.

Example 1
An autoclave reactor with an internal volume of 10 L purged with nitrogen was charged with 2266 g of cyclohexane, 84.6 g (0.812 mol) of styrene and 319.8 g (5.912 mol) of butadiene, and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 1.742 mL (2.770 mmol) of n-butyllithium was added. After the polymerization conversion rate reached 100%, 3.414 g (1.569 mmol) of a 15.4 wt% toluene solution of the compound (3) synthesized above was added and stirred for 1.5 hours. Subsequently, 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the removed polymer solution, and the solvent was removed by concentration under reduced pressure. The polymer was coagulated and washed in methanol, and then dried to obtain a solid polymer (SBR-A).

Example 2
Into an autoclave reactor with an internal volume of 10 L purged with nitrogen, 2267 g of cyclohexane, 81.9 g (0.786 mol) of styrene and 319.8 g (5.912 mol) of butadiene were charged, and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 1.732 mL (2.753 mmol) of n-butyllithium was added. After the polymerization conversion reached 100%, 5.313 g (2.028 mmol) of a 15.1 wt% toluene solution of the compound (4) synthesized above was added and stirred for 1.5 hours. Subsequently, 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the removed polymer solution, and the solvent was removed by concentration under reduced pressure. The polymer was coagulated and washed in methanol, and then dried to obtain a solid polymer (SBR-B).

Comparative Example 1
A nitrogen-substituted autoclave reactor having an internal volume of 10 L was charged with 3137 g of cyclohexane, 114.7 g (1.101 mol) of styrene and 438.9 g (8.114 mol) of butadiene, and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 3.486 mL (5.507 mmol) of n-butyllithium was added. After the polymerization conversion reached 100%, 3.607 g (2.576 mmol) of a 16.3% wt toluene solution of 4-TEMPO-glycidyl ether was added and stirred for 1.5 hours. Subsequently, 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the removed polymer solution, and the solvent was removed by concentration under reduced pressure. The polymer was coagulated and washed in methanol, and then dried to obtain a solid polymer (SBR-C).

Comparative Example 2
An autoclave reactor with an internal volume of 10 L purged with nitrogen was charged with 4530 g of cyclohexane, 165.6 g (1.590 mol) of styrene and 634.4 g (11.73 mol) of butadiene, and stirring was started. After the temperature of the contents in the reaction vessel was 50 ° C., 3.392 mL (5.393 mmol) of n-butyllithium was added. After the polymerization conversion rate reached 100%, 0.5 mL of methanol was added and stirred for 30 minutes. A small amount of an anti-aging agent (Irganox 1520 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the removed polymer solution, and the solvent was removed by concentration under reduced pressure. The polymer was coagulated and washed in methanol, and then dried to obtain a solid polymer (SBR-D).

Measurement of introduction rate (modification rate) The SBR obtained in Examples 1 and 2 was heated in an oven, dissolved in benzene, ESR measurement was performed, and the introduction rate (modification rate) was calculated from the concentration of nitroxide radicals. did. The SBR-C obtained in Comparative Example 1 was measured by dissolving it in benzene as it was.

Physical property evaluation In the formulation (parts by weight) shown in Table II, only the polymer component was kneaded for 10 minutes in a 0.6 liter closed mixer heated to 150 ° C., and then the components other than the vulcanization accelerator and sulfur in Table II were removed. Was kneaded for 5 minutes with a 0.6 liter closed mixer. The obtained master batch, the vulcanization accelerator and sulfur shown in Table II were kneaded with an 8-inch oven roll to obtain a rubber composition. This composition was press vulcanized at 160 ° C. for 20 minutes in a disk-shaped mold having a thickness of 5 mm and a diameter of 49 mm to obtain a test sample. The wear resistance of the obtained test sample was evaluated by the following method. The results are shown in Table II.

Abrasion resistance: Measured in accordance with JIS K6264 using a Lambourn abrasion tester under the conditions of a load of 15 N and a slip ratio of 50%. The obtained results were displayed as an index with the value of [(Abrasion amount of Comparative Example 4) × 100] / (Abrasion amount of sample) being 100. The larger this value, the better the wear resistance.

  The modified polymer according to the present invention induces nitroxide radicals to alkoxyamines and blocks the nitroxide radicals to attach to the living anion ends of conjugated diolefin and / or aromatic vinyl compound homopolymers or copolymers, so that side reactions can occur. Since nitroxide radicals can be introduced and terminally modified at the end of the polymer without being generated, the wear resistance of other rubbers can be improved. For example, as a tread (cap, under, side) of a pneumatic tire Useful.

Claims (6)

A single polymer or copolymer of a conjugated diolefin and / or an aromatic vinyl compound, which has a formula (I):

(In the formula, R represents at least one of a C, O, N, S, P, C _{1 to} C ₃₀ alkylene group and a C _{6 to} C ₃₀ aryl group or a single bond, and R ^{1 to} R ^3. Although an alkyl group or an aryl group of C ₆ -C ₃₀ hydrogen or C ₁ -C ₃ are each independently at least one of R ¹ to R ³ is an aryl group of C ₆ -C _30, A represents a functional group capable of reacting with a carbon anion)
A modified polymer in which an alkoxyamine compound represented by The alkoxyamine compound is represented by the formula (II):

(In the formula, R ^{1 to} R ³ each independently represent hydrogen, a C _{1 to} C ₃₀ alkyl group, or a C _{6 to} C ₃₀ aryl group, and at least one of R ^{1 to} R ³ represents C ₆ to C ^3. C ₃₀ aryl group)
The modified polymer according to claim 1, which is an alkoxyamine compound represented by the formula:   A polymer composition comprising the modified polymer according to claim 1.   The polymer composition according to claim 3, which is obtained by mechanically kneading the modified polymer according to claim 1 or 2 and a polymer different from the modified polymer.   The polymer composition according to claim 3 or 4, wherein the glass transition temperature (Tg) is -100 ° C to 10 ° C, and sulfur crosslinking is possible.   A pneumatic tire using the polymer composition according to claim 3.