RUBBER COMPOSITION AND ORGANOSILICON COMPOUND

Abstract

A rubber composition which contains (A) an organosilicon compound represented by formula (1) and gives a cured object satisfying desired fuel (or power)-saving tire properties.

##STR00001##

(R.sup.1 represents an alkyl or aryl group, R.sup.2 represents an alkyl or aryl group, e, f, and g each indicate a number larger than 0 and satisfy g/(e+f+g)<0.05, and m is an integer of 1-3.)

Claims

1. A rubber composition comprising (A) an organosilicon compound having the formula (1): ##STR00006## wherein R.sup.1 is each independently a C.sub.1-C.sub.10 alkyl group or C.sub.6-C.sub.10 aryl group, R.sup.2 is each independently a C.sub.1-C.sub.10 alkyl group or C.sub.6-C.sub.10 aryl group, e, f, and g are each independently a number of more than 0, g/(e+f+g) is a number of less than 0.05, and m is an integer of 1 to 3, with the proviso that the arrangement of individual repeat units is arbitrary.

2. The rubber composition of claim 1 wherein the organosilicon compound (A) has a number average molecular weight of up to 100,000.

3. The rubber composition of claim 1 wherein in the organosilicon compound, (f+g)/(e+f+g) is a number of up to 0.6.

4. The rubber composition of claim 1, further comprising (B) a diene rubber and (C) a filler.

5. The rubber composition of claim 4 wherein the filler (C) is silica.

6. A tire obtained by molding the rubber composition of claim 1.

7. An organosilicon compound having the formula (1): ##STR00007## wherein R.sup.1 is each independently a C.sub.1-C.sub.10 alkyl group or C.sub.6-C.sub.10 aryl group, R.sup.2 is each independently a C.sub.1-C.sub.10 alkyl group or C.sub.6-C.sub.10 aryl group, e, f, and g are each independently a number of more than 0, g/(e+f+g) is a number of less than 0.05, (f+g)/(e+f+g) is a number of up to 0.6, and m is an integer of 1 to 3, with the proviso that the arrangement of individual repeat units is arbitrary.

Description

EXAMPLES

[0065] Examples and Comparative Examples are given below for further illustrating the invention although the invention is not limited thereto.

[0066] All parts are by weight (pbw). The molecular weight is a number average molecular weight (Mn) as measured versus polystyrene standards by gel permeation chromatography (GPC). The viscosity is measured at 25° C. by a rotational viscometer.

Preparation of Organosilane Compounds

Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-3

Example 1-1

[0067] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of Ricon 130 (having formula (2) wherein (f+g)/(e+f+g)=0.28, Mn=2,500, by Cray Valley), 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxitne complex, and 0.31 g (0.52×10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 135 g (0.80 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0068] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 2,500 mPa.Math.s and a Mn of 2,800.

[0069] From the Mn and .sup.1H-NMR. spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=33, f=11, and g=2. Also, g/(e+f+g)=0.04 and (f+g)/(e+f+g)=0.28.

Example 1-2

[0070] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of Ricon 130, 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52/10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 68 g (0.40 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0071] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 2,700 mPa.Math.s and a Mn of 2,700.

[0072] From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=33, f=12, and g=1. Also, g/(e+f+g)=0.02 and (f+g)/(e+f+g)=0.28.

Example 1-3

[0073] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of Ricon 131 (having formula (2) wherein (f+g)/(e+f+g)=0.28, Mn=4,500, by Cray Valley), 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52>(10.sup.−2mol) of acetic acid. At an internal temperature of 75-85° C., 75 g (0.44 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0074] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 8,500 mPa.Math.s and a Mn of 4,800.

[0075] From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=60, f=21, and g=2. Also, g/(e+f+g)=0.02 and (f+g)/(e+f+g)=0.28.

Example 1-4

[0076] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of Ricon 131, 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52×10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 38 g (0.22 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0077] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 8,800 mPa.Math.s and a Mn of 4,700.

[0078] From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=60, f=22, and g=1. Also, g/(e+f+g)=0.01 and (f+g)/(e+f+g)=0.28.

Comparative Example 1-1

[0079] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of B-1000 (having formula (2) wherein (f+g)/(e+f+g)=0.9, Mn=1,100, by Nippon Soda Co., Ltd.), 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52×10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 125 g (0.64 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0080] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a. viscosity of 9,600 mPa.Math.s and a Mn of 1,200.

[0081] From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=2, f=17.2, and g=0.8. Also, g/(e+f+g)=0.04 and (f+g)/(e+f+g)=0.9.

Comparative Example 1-2

[0082] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of Ricon 130, 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52×10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 203 g (1.20 mol) of triethoxysilane was added dropwise over 2 hours to .sup.-the mixture, which was stirred at 80° C. for a further 1 hour.

[0083] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 2,600 mPa.Math.s and a Mn of 3,000.

[0084] From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=33, f=10, and g=3. Also, g/(e+f+g)=0.06 and (f+g)/(e+f+g)=0.28.

Comparative Example 1-3

[0085] A 2-L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 1,000 g of B-1000, 200 g of toluene, an amount (0.52×10.sup.−4 mol of platinum atom) of toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and 0.31 g (0.52×10.sup.−2 mol) of acetic acid. At an internal temperature of 75-85° C., 270 g (1.6 mol) of triethoxysilane was added dropwise over 2 hours to the mixture, which was stirred at 80° C. for a further 1 hour.

[0086] At the end of stirring, the reaction mixture was concentrated under reduced pressure and filtered, obtaining a brown transparent liquid having a viscosity of 9,100 mPa.Math.s and a Mn of 1,400. From the Mn and .sup.1H-NMR spectrum, the product was an organosilicon compound of the average structure having formula (1) wherein e=2, f=16, and g=2. Also, g/(e+f+g)=0.10 and (f+g)/(e+f+g)=0.9.

[2] Preparation of Rubber Compositions

Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-3

[0087] On a 4-L internal mixer (MIXTRON by Kobelco), SBR and BR shown in Tables 1 and 2 were kneaded for 30 seconds.

[0088] Next, oil component, carbon black, silica, sulfide silane, the organosilicon compounds of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-3. stearic acid, antioxidant, and wax were added to the mix. The internal temperature was raised to 150° C., after which the mix was held at 150° C. for 2 minutes and discharged. This was followed to by stretching on a roll mill. The resulting rubber was kneaded again on the internal mixer (MIXTRON by Kobelco) until the internal temperature reached 140° C., discharged, and stretched on a roll mill.

[0089] Rubber compositions were obtained by adding zinc oxide, vulcanization accelerator and sulfur shown in Tables 1 and 2 to the rubber and kneading them. The rubber compositions were press molded at 150° C. for 15 to 40 minutes into vulcanized rubber sheets (2 mm thick).

[0090] The rubber compositions of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-3 were measured for physical properties in unvulcanized and vulcanized states by the following tests. The results are also shown in Tables 1 and 2.

[Unvulcanized Physical Properties]

(1) Mooney Viscosity

[0091] According to HS K6300, measurement was made under conditions: temperature 100° C., preheating 1 minute, and measurement 4 minutes. The measurement result was expressed as an index based on 100 for Comparative Example 2-1. A lower index corresponds to a lower Mooney viscosity and indicates better workability.

[Vulcanized Physical Properties]

(2) Dynamic Viscoelasticity (Strain Dispersion)

[0092] Using a viscoelasticity meter (Metravib), a storage elasticity at strain 0.5%, E′ (0.5%) and a storage elasticity at strain 3.0%, E′ (3.0%) were measured under conditions: temperature 25° C. and frequency 55 Hz. A value of [E′ (0.5%)−E′ (3.0%)] was computed. The test specimen was a sheet of 0.2 cm thick and 0.5 cm wide, the clamp span was 2 cm, and the initial load was 1 N.

[0093] The value of [E′ (0.5%)−E′ (3.0%)] was expressed as an index based on 100 for to Comparative Example 2-1. A lower index indicates better dispersion of silica.

(3) Dynamic Viscoelasticity (Temperature Dispersion)

[0094] Using a viscoelasticity meter (Metravib), measurement was made under conditions: tensile dynamic strain 1% and frequency 55 Hz. The test specimen was a sheet of 0.2 cm thick and 0.5 cm wide, the clamp span was 2 cm, and the initial load was 1 N.

[0095] The values of tanδ (0° C.) and tanδ (60° C.) were expressed as an index based on 100 for Comparative Example 2-1. A greater index of tanδ (0° C.) indicates a better wet grip. A lower index of tanδ (60° C.) indicates better rolling resistance.

(4) Wear Resistance

[0096] Using a FPS tester (Ueshima Seisa.kusho Co., Ltd.), the test was carried out under conditions: sample speed 200 m/min, load 20 N, road temperature 30° C., and slip rate 5%.

[0097] The measurement result was expressed as an index based on 100 for Comparative Example 2-1. A greater index indicates a smaller abrasion and hence, better wear resistance.

TABLE-US-00001 TABLE 1 Formulation (pbw) Example 2-1 Example 2-2 Example 2-3 Example 2-4 Example 2-5 Example 2-6 (B) SBR 80 80 80 80 80 80 (B) BR 20 20 20 20 20 20 Oil 30 30 30 30 30 30 Carbon black 5 5 5 5 5 5 (C) Silica 75 75 75 75 75 75 (D) Sulfide silane 6 6 6 6 6 6 (A) Example 1-1 4 2 — — — — Organosilicon Example 1-2 — — 2 — — — compound Example 1-3 — — — 2 — — Example 1-4 — — — — 2 — Comparative — — — — — 2 Example 1-1 Stearic acid 2 2 2 2 2 2 Antioxidant 2 2 2 2 2 2 Wax 1 1 1 1 1 1 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 Vulcanization accelerator (a) 1 1 1 1 1 1 Vulcanization accelerator (b) 0.3 0.3 0.3 0.3 0.3 0.3 Vulcanization accelerator (c) 1.5 1.5 1.5 1.5 1.5 1.5 Sulfur 2 2 2 2 2 2 [Unvulanized physical properties] Mooney viscosity 85 90 92 92 94 96 [Vulcanized physical properties] Strain dispersion [E′ (0.5%) − E′ (3.0%)] 90 90 85 85 86 94 Dynamic viscoelasticity tanδ (0° C.) 110 110 111 111 110 103 Dynamic viscoelasticity tanδ (60° C.) 90 91 84 87 84 95 Wear resistance 109 108 115 112 115 105

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Example Example Example Formulation (pbw) 2-1 2-2 2-3 (B) SBR 80 80 80 (B) BR 20 20 20 Oil 30 30 30 Carbon black 5 5 5 (C) Silica 75 75 75 (D) Sulfide silane 6 6 6 (A) Comparative Example 1-2 — 2 — Organosilcon compound Comparative Example 1-3 — — 2 Stearic acid 2 2 2 Antioxidant 2 2 1 Wax 1 1 1 Zinc oxide 2.5 2.5 2.5 Vulcanization accelerator (a) 1 1 1 Vulcanization accelerator (b) 0.3 0.3 0.3 Vulcanization accelerator (c) 1.5 1.5 1.5 Sulfur 2 2 2 [Unvulcanized physical properties] Money viscosity 100 90 96 [Vulcanized physical properties] Strain dispersion[E′ (0.5%) − E′ (3.0%)] 100 105 105 Dynamic viscoelasticity tanδ (0° C.) 100 101 100 Dynamic viscoelasticity tanδ (60° C.) 100 98 98 Wear resistance 100 100 100 SBR: SLR-4602 (Trinseo S.A.) BR: BR-01 (JSR Corp.) Oil: AC-12 (Idemitsu Kosan Co., Ltd.) Carbon black: Seast 3 (Tokai Carbon Co., Ltd.) Silica: Nipsil AQ (Tosoh Silica Co., Ltd.) Sulfide silane: KBE-846 (Shin-Etsu Chemical Co., Ltd.) Stearic acid: industrial stearic acid (Kao Corp.) Antioxidant: Nocrac 6C (Ouchi Shinko Chemical Industry Co., Ltd.) Wax: Ozoace 0355 (Nippon Seiro Co., Ltd.) Zinc oxide: Zinc white #3 (Mitsui Mining & Smelting Co., Lid.) Vulcanization accelerator (a): Nocceler D (Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (b): Nocceler DM-P (Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (c): Nocceler CZ-G (Ouchi Shinko Chemical Industry Co., Ltd.) Sulfur: 5% oil-treated sulfur (Hosoi Chemical Industry Co., Ltd.)

[0098] As shown in Tables 1 and 2, the vulcanized rubber compositions of Examples 2-1 to 2-6 have lower values of strain dispersion [E′ (0.5%)−E′ (3.0%)] than the vulcanized. rubber compositions of Comparative Examples 2-1 to 2-3, indicating better dispersion of silica; higher values of dynamic viscoelasticity tanδ (0° C.). indicating better wet grip; lower values of dynamic viscoelasticity tanδ (60° C.), indicating a smaller hysteresis loss, less heat generation, and better wear resistance.