JP2005350603A - Rubber composition containing compound having organosilicon function group through urethane bond at terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber composition having excellent unvulcanized physical properties, reinforcing properties such as abrasion resistance, etc., heat aging resistance and low tanδ(60°C). <P>SOLUTION: The rubber composition comprises (A) 100 parts wt. of diene-based rubber, (B) 10-150 parts wt. of a silica-based filler and (C) 0.1-30 parts wt. of a compound that is a hydrocarbon having a main chain of straight chain or branched chain and contains organosilicon functional groups bonded through urethane bonds to at least two terminals. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition containing a compound having an organosilicon functional group via a urethane bond at a terminal, and more particularly, has excellent unvulcanized physical properties, improved reinforcing properties such as wear resistance and heat aging resistance, and The present invention relates to a rubber composition having a low tan δ (60 ° C.) (that is, low exothermic property).

  It is known that a silica filler compounded rubber composition can improve, for example, heat generation and wear resistance, compared with other filler compounded rubber compositions such as carbon black, and further a silane coupling agent is compounded. It is also known that processability is improved while improving mechanical strength (see, for example, Patent Document 1). Furthermore, Patent Document 2 describes a modified diene rubber-based rubber composition in which a functional group (for example, alkoxysilyl) is added to a double bond of a diene rubber for the same purpose as blending a silane coupling agent. Documents 3 and 4 describe rubber compositions of low molecular weight diene rubbers modified with an organosilicon compound having an alkoxy group.

JP-A-8-176345 JP 2002-114874 A Japanese Patent Laid-Open No. 2001-114938 JP 2000-344944 A

  However, bis (3-triethoxysilylpropyl) tetrasulfide, which is a silane coupling agent generally used for conventional tires disclosed in Patent Document 1, is expensive, and at the same time, a mercapto group-containing silane cup There is a problem that the effect cannot be exhibited unless the blending amount is increased as compared with the ring agent. Further, even the methods disclosed in Patent Documents 2 to 4 have a problem that properties such as work resistance are insufficient.

  Accordingly, an object of the present invention is to provide a rubber composition which is excellent in unvulcanized physical properties, has excellent reinforcing properties such as wear resistance and heat aging resistance, and has a low tan δ (60 ° C.) (that is, improved exothermic properties). There is.

  According to the present invention, (A) 100 parts by weight of a diene rubber, (B) 10 to 150 parts by weight of a silica filler, and (C) the main chain is a linear or branched hydrocarbon, and at least two There is provided a rubber composition comprising 0.1 to 30 parts by weight of a compound having an organosilicon functional group via a urethane bond at the terminal.

  A silane coupling agent is used for compounding silica into the rubber composition of the present invention. In the present invention, the low tan δ is realized while being excellent in unvulcanized characteristics and improving the reinforcing properties such as wear resistance. Unlike conventional coupling agents, it does not contain sulfur, improving scorch resistance and heat aging resistance. In addition, the introduction of alkoxysilane to the terminal utilizes the high reactivity of the isocyanate group, and a strong urethane bond can be easily introduced.

  As the diene system used as the component (A) in the present invention, any diene rubber that can be used for tires and others, for example, various natural rubbers (NR), various polyisoprene rubbers (IR), various polybutadiene rubbers. (BR), various styrene-butadiene copolymer rubbers (SBR), various acrylonitrile-butadiene copolymer rubbers, various ethylene / propylene / diene copolymers (EPDM), butyl rubber (IIR), halogenated butyl rubber, chloroprene rubber, etc. These can be used alone or as any blend.

In the present invention, the silica-based filler is added as component (B) in an amount of 10 to 150 parts by weight, preferably 20 to 80 parts by weight, per 100 parts by weight of the diene rubber (A). If the blending amount is too small, the reinforcing effect and wear resistance cannot be obtained, and this is not preferable. As the silica-based filler used in the present invention, those usually used for rubber compounding can be used, and the kind thereof is not limited. For example, in addition to dry silica and wet silica, silicon atom-containing fillers such as clay and talc can be used, and these are commercially available. Particularly for tires, silica of dry method silica and wet method silica having a BET specific surface area of 20 to 400 nm ² / g and a primary particle size of 5 to 400 nm is preferably used. Moreover, metal oxides, such as aluminum, magnesium, potassium, barium, titanium, may be included arbitrarily.

  In the present invention, as the component (C), a compound in which the main chain is a linear or branched hydrocarbon and has an organosilicon functional group at least at two ends via urethane bonds is added to 100 parts by weight of the diene rubber. 0.1 to 30 parts by weight, preferably 1 to 25 parts by weight. If the blending amount is too small, a sufficient blending effect cannot be obtained, which is not preferable. On the other hand, if the blending amount is too large, an effect commensurate with the blending amount cannot be obtained, and this is not economically advantageous.

  Said compound (C) is preferably of the formula (I):

(Wherein R ¹ , R ² and R ³ may be the same or different and at least one is an alkoxy, phenoxy or alkylaryloxy group, C ₁ -C ₁₈ alkyl group, C _1- C ₁₈ alkoxy group, C ₆ -C ₁₂ phenyl group or C ₆ -C ₁₂ phenoxy group, C ₇ -C ₁₈ arylalkyloxy group, X ¹ and X ² may be the same or different, and if necessary Represents a hydrocarbon which may contain a heteroatom, and Y represents a hydrocarbon which may contain a straight or branched heteroatom)
It is represented by

  In the compound (C) of the formula (I), the moiety Y is preferably a hydrocarbon which may contain a heteroatom having a number average molecular weight of 500 to 10,000, and more preferably 1000 to 3000. This is because if the molecular weight of Y is too small, there is a possibility that a flexible structure of the diene rubber cannot be obtained. Conversely, if it is too large, there is a risk that the reinforcing part cannot be obtained because the reaction part with silica is reduced. Because there is. The hydrocarbon is preferably a polymer containing at least one conjugated diene monomer, such as a butadiene polymer (preferably cis 1,4 bond 50 to 70%, vinyl bond 5 to 30%) or isoprene weight. Preferably, these are a polybutadiene or polyisoprene having a hydroxyl group at least at two terminals and having a number average molecular weight of 1000 to 10,000 and a silane compound having an isocyanate group and an alkoxy group under suitable reaction conditions, such as dilaurin. 0 to 700 ° C x 1 minute in the presence of a catalyst such as an organic tin catalyst typified by dibutyltin (II) acid, dibutyltin diacetate (I), a tertiary amine compound typified by lead naphthenate or triethylenediamine It can be obtained by reacting for ˜2 hours. It is also possible to use a urethane prepolymer obtained by reacting a compound having two or more isocyanate groups with polybutadiene and polyisoprene having a number average molecular weight of 1,000 to 10,000 having hydroxyl groups at two or more terminals, This can also be obtained by reacting a primary or secondary amine or a silane compound having an alkoxysilyl group having a hydroxyl group under suitable reaction conditions.

  In addition to the above-described essential components, the rubber composition according to the present invention includes other reinforcing agents (fillers) such as carbon black, vulcanization or crosslinking agents, vulcanization or crosslinking accelerators, various oils, anti-aging agents, Various additives that are generally blended for tires such as plasticizers and other general rubbers can be blended. These additives are kneaded and vulcanized by a general method to obtain a composition, and then vulcanized. Or it can be used to 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.

  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 modified polymers 1 to 3 used in this example were prepared as follows.

End-modified polymer 1 (Synthesis of both-end alkoxysilane liquid BR)
Hydroxyl-terminated liquid polybutadiene (R-45HT manufactured by Idemitsu Petrochemical Co., Ltd., number average molecular weight 2800) and 18 g of isocyanate silane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd.) are placed in a container and mixed. (Chemical conversion industry) 0.5g was added and it was made to react for 10 minutes. The disappearance of the sharp and strong absorption 2270 cm ⁻¹ peak derived from isocyanate was confirmed by IR spectrum. No unreacted material was observed.

Terminal-modified polymer 2 (Synthesis of both-end alkoxysilane liquid IR)
Modified polymer 1 in the same manner as modified polymer 1 except that 100 g of hydroxyl-terminated liquid polyisoprene (Poly ip made by Idemitsu Petrochemical, number average molecular weight 2500) and 20 g of isocyanate silane (KBE-9007 made by Shin-Etsu Chemical) were mixed in a container. 2 was prepared. The disappearance of the sharp and strong absorption 2270 cm ⁻¹ peak derived from isocyanate was confirmed by IR spectrum. No unreacted material was observed.

Modified polymer 3 (internal alkoxysilane modified liquid BR)
To a glass flask equipped with a stirrer and temperature controller, add 50 g of liquid polybutadiene rubber (polyoil Nippon Zeon Co., Ltd.) and 700 ml of toluene, and raise the temperature to 60 ° C. with stirring to completely dissolve the liquid polybutadiene rubber. It was. Next, 0.125 mol of bis (3-triethoxysilylpropyne) tetrasulfide (Si69 Degussa) dissolved in tetrahydrofuran was added, and the mixture was denatured at 60 ° C. for 2 hours. This reaction solution was precipitated with methanol, dissolved again in toluene, and reprecipitation was repeated to remove unreacted Si69, and tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4) was used as an antioxidant. '-Hydroxyphenyl) propionate] methane (Irganox 1010 made by Nippon Ciba-Gaiky Co., Ltd.) was kneaded at 1000 ppm with respect to the polybutadiene rubber and vacuum-dried at 100 ° C. for 1 hour to obtain a modified polybutadiene rubber.

Examples 1-2 and Comparative Examples 1-5
Sample preparation In the formulation shown in Table I, ingredients other than the vulcanization accelerator and sulfur were kneaded with a 1.6 liter closed mixer for 5 minutes and released when the temperature reached 155 ± 5 ° C to obtain a master batch. It was. A vulcanization accelerator and sulfur were kneaded with this master batch with an open roll to obtain a rubber composition. Using this rubber composition, unvulcanized physical properties were evaluated by the following test methods. The results are shown in Table I.

  Next, the resulting rubber composition was vulcanized in a 15 × 15 × 0.2 cm mold at 160 ° C. for 30 minutes to prepare a vulcanized rubber sheet. The physical properties of the vulcanized rubber were measured by the following test methods. It was measured. The results are shown in Table I.

Rubber property evaluation test method Mooney viscosity ML _{1 + 4} (100 ° C.): Measured according to JIS K6300. The smaller the value, the better the workability and the better.
Scorch (min): Measured according to JIS K6300. The time (minutes) for the viscosity to rise by 5 Mooney units at a temperature of 125 ° C. was measured. Larger values are less likely to burn and have better storage stability.
T95 (min): Measured according to JIS K6300. The time (minutes) required to reach 95% vulcanization at a temperature of 160 ° C. was measured and designated as T95. The smaller the value, the faster and better the vulcanization rate.
100% modulus: Measured according to JIS K6251.

  tan δ (60 ° C.): Measured at 60 ° C. using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho under conditions of an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz. The smaller this value, the lower the heat build-up and the better.

Lambourn abrasion test: Measured using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) under a load of 5 N, a slip rate of 25%, a time of 9 minutes, and room temperature conditions. Displayed. The higher this value, the better the wear resistance.

Table I footnote * 1: Nipol 1502 (Nippon Zeon SBR)
* 2: ZEOSIL 115GR (Rhodia silica)
* 3: Si69 (Degussa silane coupling agent)
* 4: R-45HT (liquid BR manufactured by Idemitsu Petrochemical, Mw: 2800)
* 5: Three types of zinc oxide (manufactured by Shodo Chemical Industry)
* 6: Bead stearic acid YR (manufactured by NOF Corporation)
* 7: SANTOFLEX 6PPD (manufactured by Flexis)
* 8: 5% oil-treated sulfur (manufactured by Karuizawa Refinery)
* 9: Noxeller CZ-G (Ouchi Shinsei Chemical)
* 10: Soxinol DG (manufactured by Sumitomo Chemical)
* 11: Epion EP303S (both terminal silyl group polyisobutylene manufactured by Kaneka Corporation)

  As described above, according to the present invention, by adding a specific modified polymer, the unvulcanized characteristics are improved and the production efficiency is improved because the vulcanization speed is high compared with the conventional silane coupling agent. The The vulcanized rubber composition exhibited low heat buildup while maintaining high reinforcement. In addition, heat aging resistance is improved as compared with sulfur-based coupling agents. Since these rubber compositions have excellent wear resistance that can be used as tire conveyor belts, hoses, high damping rubber, other industrial rubber products, etc., they can be used for tires.

Claims (9)

  (A) 100 parts by weight of a diene rubber, (B) 10 to 150 parts by weight of a silica filler, and (C) the main chain is a linear or branched hydrocarbon and has urethane bonds at least at two ends. A rubber composition comprising 0.1 to 30 parts by weight of a compound having an organosilicon functional group. The compound (C) is represented by the formula (I):

(Wherein R ¹ , R ² and R ³ may be the same or different and at least one is an alkoxy, phenoxy or alkylaryloxy group, C ₁ -C ₁₈ alkyl group, C _1- C ₁₈ alkoxy group, C ₆ -C ₁₂ phenyl group or C ₆ -C ₁₂ phenoxy group, C ₇ -C ₁₈ arylalkyloxy group, X ¹ and X ² may be the same or different, and if necessary Represents a hydrocarbon which may contain a heteroatom, and Y represents a hydrocarbon which may contain a straight or branched heteroatom)
The rubber composition according to claim 1, which contains 70% by weight or more of a silane compound represented by the formula:   The rubber composition according to claim 2, wherein the portion Y of the compound (C) of the formula (I) is a hydrocarbon which may contain a hetero atom having a number average molecular weight of 500 to 10,000.   The rubber composition according to claim 2, wherein the portion Y of the compound (C) of the formula (I) is a polymer containing at least one conjugated diene monomer.   The rubber composition according to claim 2, wherein the portion Y of the compound (C) of the formula (I) is a butadiene polymer.   The rubber composition according to claim 5, wherein the butadiene polymer contains 50 to 70% cis-1,4 bonds and 5 to 30% vinyl bonds.   The rubber composition according to claim 6, wherein the compound (C) is obtained by reacting a polybutadiene having at least two terminal hydroxyl groups and a number average molecular weight of 1,000 to 10,000 with a silane compound having an isocyanate group and an alkoxy group.   The rubber composition according to claim 2, wherein the portion Y of the compound (C) of the formula (I) is an isoprene polymer.   The compound (C) is obtained by reacting a polyisoprene having a number average molecular weight of 1,000 to 10,000 having at least two terminal hydroxyl groups and a silane compound having an isocyanate group and an alkoxy group. Rubber composition.