KR980009354A - Process for preparing organosilane polysulfane mixtures and rubber blends containing such mixtures - Google Patents

Abstract

The present invention relates to organosilanepolysulfane mixtures of formula (1) and rubber blends prepared using such mixtures, in particular to tire treads.

(One)

In the above formula (1), R is linear or branched alkyl of 1 to 8 carbon atoms, in particular 1 to 3 carbon atoms, x is an integer of 1 to 8, z is 0 to 6 (where z = 0 organosilane poly The sum of the sulfonate ratio and the ratio of organosilanepolysulfane with z = 1 is 80% by weight or more, provided that the ratio of the compound with z = 0 is less than 80% and the ratio of organosilanepolysulfane with z being an integer of 2 to 6 Does not exceed 20% by weight of silver in the mixture.)

[Brief Description of Drawings]

1 shows the minimum torque values of the formulations according to Example 1. FIG.

2 shows the scouring behavior at all compounding temperatures of Si 266 mode Si 69,

3 shows the curing time at all blending temperatures of Si 266 mode Si 69,

4 shows the processing behavior at all compounding temperatures of Si 266 mode Si 69,

5 shows the injection rates at all compounding temperatures of Si 266 mode Si 69,

Description

Process for preparing organosilane polysulfane mixtures and rubber blends containing such mixtures

The present invention relates to organosilanepolysulfane mixtures having elevated disulfane ratios and to methods for preparing rubber blends containing such blends.

With increased awareness of the environment, savings in fuel consumption and reduction of pollutant emissions have become increasingly important in recent years (see Auto 91/92, Verband der Artomobilindustrie e.V., Frankfurt and ADAC-Motorwelt 11791, 50 (1991)). The goal of tire manufacturers is to develop tires that exhibit very low rolling resistance with excellent wetting slip resistance and good abrasion resistance.

Several documents and patents propose reducing fuel consumption by reducing tire rolling resistance. The mentioned proposals include reducing the carbon black content in the formulation and using special carbon blacks (see US Pat. No. 4,866,131 and US Pat. No. 4,894,420). However, none of these proposed solutions satisfies the balance between other important tire features such as wet skid and abrasion resistance and the desired low rolling resistance. When carbon black in the rubber compound is largely substituted with silica, it has almost reduced rolling resistance compared to standard tires only when high active silica gel filler is used in combination with organosilane bis (triethoxysilylpropyl) tetrasulfane. At the same time, tire manufacturing has been advanced while maintaining or further improving the other two tire features described above. (See, e.g., European Patent No. 0,501,227, US Patent No. 5,227,425; G. Agostini, J. Berg, Th. Materne New Compound Technology, October 1994, Akron, Ohio, USA; S. Wolff, U. Gorl, MJ Wang, W. Wolff: Silica based on tread compounds-background & perfomance, paper presented at TYRE TECH '93, October 1993, Basel, Swizerland and Ph. Cochet, LB Barriquand: Precipitated silica in tire tread, paper presented at ACS Meeting of the Rubber Division, October 1995, Cleveland, Ohio, USA).

S at the 1986 ACS conference in New York. Wolff (S. Wolff: The influence of fillers on rolling resistance, presented at the 129th meeting of the Rubber Division, American Chemical Society, April 811, 1986, New York) is emulsifier styrene / butadiene rubber (E-SBR) TESPT is incorporated into both passenger car treads based on carbon steel and truck tire treads based on natural rubber to significantly reduce the rolling resistance when compared to standard formulations filled with carbon black, while maintaining significant wet sliding resistance using silica. Reported.

In addition, these systems are often blended with other polymerizers (especially butadiene) to produce special styrene / butadiene polymers and novel silica grades prepared using a solution polymerization process (see EP 0 447 066 A1). Literature reference: All three features are optimized by using polymer blends that are particularly suitable for this application (European Patent No. 0 620 250 A1) and sometimes with 3 to 4 different starting polymers (see Literature 5). GW Marwede, UG Eisele, AJM Sumner: paper presented to the ACS Meeting of the Rubber Division, October 1995, Cleveland, Ohio, USA and U. LeMaitre: Tire Rolling resistance, AFCEP / DKG Meeting, 1993, Mulhouse, France).

All documents and patents state that it is necessary to replace high proportions or total amounts of carbon black fillers commonly used with highly active silica to achieve lower rolling resistance while maintaining or improving wet slip and wear resistance. (See S. wolff: The influence of fillers on rolling resistance, presented at the 129th meeting of the Rubber Division, American Chemical Society, April 811, 1986, New York and U. LeMaire: Tire rolling resistance, AFCEP / DKG Meeting , 1993, Mulhouse, France). However, this substitution can only achieve the purpose when organosilanebis (triethoxysilylpropyl) tetrasulfane (TESTP) is used as a "coupling agent" between silica and polymer.

The properties achieved by using organosilanes in rubber formulations depend on two independent reactions (see S. Wolff: The role of rubber-to-silica bonds in reinforcement, presented at the First Franco-German Rubber). Symposium, November 14-16, 1985, Obernai, France and S. Wolff: Silanes in tire compounding after ten years-review, Third Annual Meeting & Conference on Tire Science & Technology, The Tire Society, March 28-29, 1984, Akron , Ohio, USA). First, during the preparation of the formulation, preferably during the first compounding step, the silane of silica is reacted with the trialkoxysilyl group of the silane having the alcohol removed at an elevated temperature (hydrophobic or reforming reaction). Termination reactions are critically important for subsequent properties. As with all chemical reactions, this reaction proceeds more rapidly at elevated temperatures, and rubber compounders requiring short compounding times are suitable for the highest possible blending temperatures. However, this high compounding temperature is limited by the fact that the second so-called rubber-reactive group of TESPT consists of a group in which the longer chains (S ₅ -S ₈ ) average the tetrasulfane group, which has a significant analogy (see literature). S. Wolff: Silanes in tire compounding after ten years-review, Third Annual Meeting & Conference on Tire Science & Technology, The Tire Society, March 28-29, 1984, Akron, Ohio, USA).

Such rubber reactive groups are generally believed to appear as so-called filler / rubber bonds and determine the technical rubber properties for the finished product (eg tire). This reaction, which is required during vulcanization, is affected by the thermal flexibility of the tetrasulfane group and the higher sulfane units. In practical practice, however, if the reaction occurs during the preparation of the unvulcanized formulation, but only during the regular reaction of the filler and silane, the reaction causes serious problems.

When sulfur is removed in the long chain tongue plate unit, it is incorporated into the polymer chain. This results in "scoring" and also hardens the sheet dan blend, which may cause the unvulcanized blend to no longer react. Scorching is measured by determining the viscosity of the formulation. European Patent A1-0 732 362, which is not published first, describes the use of organosilanedisulfide in rubber formulations. However, these sulfur blends must be very pure or have a disulfide content of at least 80%.

It is an object of the present invention to provide organosilanepolysulfane mixtures which do not result in scouring at elevated temperatures which may occur during the preparation of vulcanized rubber formulations, ie vulcanizable rubber formulations which do not yet contain sulfur or accelerators required for vulcanization. To provide.

The present invention provides a polysulfane mixture to achieve this object, which includes an organo silanepolysulfane mixture of formula (1).

In the above formula (1), R is a linear or branched chain alkali having 1 to 8 carbon atoms, in particular 1 to 3 carbon atoms, x is an integer of 1 to 8, z is 0 to 6 (where z = 0 organosilane The sum of the ratio of polysulfane and the ratio of organosilanepolysulfane with z = 1 is 80% by weight or more, provided that the ratio of the compound with z = 0 is less than 80% and the ratio of organosilanepolysulfane with z being an integer of 2 to 6 Does not exceed 20% by weight of silver in the mixture).

Do not exceed 20% by weight ratio is a feature that is referred to as 20% by weight or less and is characterized by nature. Polysulfane fractions with z = 7 or z = 8 are generally not found in the mixtures according to the invention. Exceptionally they are present in amounts of less than 1%, for example as impurities, which do not affect any use of the mixtures according to the invention.

Of course, the sum of the components should always be 100%, with care in the formulation with z = 7: 8, as the case may be.

Mixtures in which the organosilanepolysulfane ratio has the following values are particularly suitable mixtures.

z = 0 greater than about 58% to less than 80% z = 1 greater than about 32%, where the sum of these combinations is greater than or equal to 80% z = 2 to less than or equal to 20%, in particular less than about 11%.

According to the invention, the mixtures are used for the production of vulcanizable rubber blends, in particular tires. The polymers used in such formulations may or may not be oil weighted, for example natural rubbers, butadiene rubbers, isoprene rubbers, butadiene / styrene rubbers prepared using natural and synthetic elastomers or solution polymerization processes or emulsion polymerization processes as polymers alone. Natural elastomers and synthetic elastomers, in particular blended with other rubbers such as SBR. The term mixture on the other hand means that the formulation can be prepared from pure polysulfanes of formula 1 (wherein x is other polysulfanes with x = 0, as defined in claim 1, if x is not zero).

On the other hand, however, it can mean that the formulation can be prepared by using a manufacturing process suitable for obtaining the mixture according to the invention or by adding another polysulfane.

According to the invention, the mixtures are mainly used in tire tread formulations with elevated silica content, as described, for example, in EP-A-0 447 066 and EP-A-0620 250.

According to the present invention, rubber formulations prepared using the mixture are generally vulcanized with sulfur and / or sulfur donors and accelerators (vulcanization aids), where the amount of sulfur is generally 0.1 to 4 phr.

In addition to practically customary additives such as polymers and activators, sulfates and processing aids, the rubber blend optionally contains carbon black and natural, light colored fillers in an amount of 10 to 200 parts, in particular 25 to 80 parts per 100 parts of polymer. . These fillers are characterized by a BET surface area of 1 to 700 m ² / g, in particular 100 to 250 m ² / g and a DBP value of 150 to 300 ml / 100 g.

Suitable embodiments are powders as well as low-dusting forms such as pellets and microbeads. According to the invention, the amount of the mixture here is from 0.5 to 30 parts with respect to 100 parts of filler. Preferably, for example in the case of generally using 100 to 250 m ² / g of silica, in applications such as tire tread blends with elevated silica content, the mixture is prepared according to the invention from 4 to 10 parts with respect to 100 parts of filler. Use in quantity.

According to the invention, the mixture is incorporated into the compound in situ or in the improved embodiment first with carbon black. It is also possible to develop silica, for example used as filler, as described in German Patent No. 19609619.7.

Particular attention is paid to the preparation of high silica in combination with organosilane. A suitable method is described in EP 0 447 066A1, where the use of TESPT should ensure that the temperature does not exceed 160 ° C. during the formulation in the process so as to avoid the aforementioned scoping. However, when using the combinations according to the invention, in order to avoid such disturbing effects, temperatures of 160 to 200 ° C., in particular 175 to 190 ° C., are possible. A higher blender temperature can thus be selected to facilitate the reaction of silica with silane, ie reduce the blending time and / or the number of blending steps. Therefore, the mixing conditions can be selected very freely. According to the invention, the mixture uses substantially any rubber product. They are particularly suitable for use as high silica fillers (containing more than 40 parts of SiO2 per 100 parts of rubber), especially tire tread blends, which generally increase the amount of silane to improve the required properties.

Like the preparation method thereof, the rubber compound mentioned is provided by the present invention.

Processes for the preparation of rubber blends which are sulfurized and / or sulfur donors and accelerators and contain one or more of natural rubber or synthetic rubber, light colored oxide (silicate) fillers, optional carbon black and additional ingredients, include rubber components, The mixture, the silicate filler and any of the present carbon blacks according to claims 1, 2 and 3, optionally together with a plasticizer, a volcanizing agent and an activator, in a kneader (optionally a Banbury internal mixer), at a single stage at 160-200 ° C. Or kneading in multiple stages for 3 to 15 minutes, then adding the vulcanization aid at 60-120 ° C., preferably 80-110 ° C., at 60-120 ° C. for an additional 2-10 minutes in a Banbury internal mixer or roll mill. The compounding is then continued and the processed rubber compound is rolled into sheets or strips.

The present invention also relates to the use of organosilanepolysulfane mixtures, wherein the sulfane chain distribution is selected from temperatures between 160 and 200 ° C., in particular between 175 and 190 ° C., and no scouring of any unignited formulations occurs.

Indeed, such scorching is evaluated from unvulcanized sheet properties, with the occurrence of scorching becoming more coarse and brittle and often incapable of processing with a roll mill. Scorching in the laboratory is confirmed by measuring the viscosity of the formulation and determining the minimum torque value of the unvulcanized compound by rheometer testing. The guide value for any increase in viscosity compared to compositions formulated at lower temperatures (= more than 10 Mooney units, in particular more than 10 Mooney units) is a scouring indicator of the formulation. Can be set.

Test Standards Used in Examples

300% Modulus MPa DIN 53 504

Shore A Hardness-DIN 53 505

DIN Wear ㎣ DIN 53 516

MTS DIN 53 513

Mooney viscosity DIN 53 523/53 524

The following chemicals are used in the practical examples.

Si 69 bis (triethoxysilylpropyl)-

Tetrasulfane (Degussa AG)

Buna VLS 5025 1 HM styrene / butadiene rubber for solution polymerization

Manufactured Using (Bayer AG)

Buna CB 11S Polybutadiene Rubber (Bayer AG)

Naphtolen ZD Aromatic Plasticizer (Chemetal)

Vulkanox 4020 Phenylenediamine Decolorization

Sulfating agent (Baye AG) (6PPD)

Protective Agent G 35 Ozone Protective Wax Fuller

Vulkcit D diphenylguanidine (Bayer AG)

Insoluble Sheet CZ Benzothiazyl-2-cyclohexylsulfenamide

(Bayer AG)

Precipitated Silica with Ultrasil VN 3 GR BET Surface Area 175㎡ / g

(Degussa AG)

Si 266 bis (triethoxysilylpropyl) disulfane

Si 266 mod

Example 1

Determination of Sulfur Chain Distribution of Different Organosilane Polysulfane Mixtures

Determination by HPSC for the following compositions

Example 2

Scorching Decision Using Flowmeter Curve at 180 ° C

All mixtures from Example 1 are incorporated into the rubber formulation according to Example 3 using the blend composition for steps 1 and 2 at about 140 ° C., ie without the vulcanization system. The minimum torque value of this uncalcified compound is determined by a rheometer at 180 ° C. Increasing the torque value indicates the scouring behavior (see Figure 1).

Example 3

Comparison of Rheological Data and Unvulcanized Compounds Between Si 69 and Disulfane Mixtures in Passenger Car Wheel Formulations

(Si 266 mode: 57.7% S2, 31.4% S3, 8.3% S4, 2.3% S5, 0.2% S6)

Formulation Instruction

Step 1

Rotor Speed: 70rpm

Flow: 80 ℃

Step 2

Rotor Speed: 60rpm

Flow: 80 ℃

Step 3

Rotor Speed: 60rpm

Flow: 80 ℃

Formulation instructions

Step 1

Rotor Speed: 95rpm

Flow: 80 ℃

Step 2

Rotor Speed: 60rpm

Flow: 80 ℃

Step 3

Rotor Speed: 30rpm

Flow: 50 ℃

Formulation Instruction

Step 1

Rotor Speed: 115rpm

Flow: 95 ℃

Step 2

Rotor Speed: 60rpm

Flow: 80 ℃

Step 3

Rotor Speed: 30rpm

Flow: 50 ℃

The temperature of the output was raised to 180 ° C. in Si 266 mode without the risk of scorching, and the vulcanized rubber data obtained in this way was compared with the results of Si 69 at the output temperature of 140 ° C.

The Si 266 mode is distinguished in particular by the good tan δ value at 0 ° C. and improves tire wet slip characteristics.

FIG. 2 shows that the Si 266 mode exhibits significantly improved scorching behavior at all blending temperatures, FIG. 3 shows that the Si 266 mode exhibits significantly improved vulcanization time compared to the Si 266 mode, and FIG. Even at the compounding temperature indicated, the Si 266 mode shows no scorching at all, indicating that it has a significantly improved processing behavior, and FIG. 5 shows that all of Si 266 is reliably advantageous at the implantation rate.

The present invention provides an organosilane polysulfane mixture in which no scouring at elevated temperatures occurs during the preparation of an unvulcanized rubber blend, ie a flammable rubber blend that does not contain the sulfur or promoter required for vulcanization.

Claims (8)

Organosilane Polysulfane Mixture of Formula 1. In the above formula (1), R is a linear or branched alkali of 1 to 8 carbon atoms, in particular 1 to 3 carbon atoms, x is an integer of 1 to 8, z is 0 to 6, where z is an integer of 2 to 6 The proportion of polysulfanes does not exceed the proportion of 20% by weight in the mixture, and the proportion of polysulfanes where z is zero is less than 80% by weight). The sum of the organosilane polysulfane ratio of z to 0 and the organosilane polysulfane ratio is 80% by weight or more, provided that the ratio of the compound whose z is 0 is 80% or less and z is 2 to 2. Wherein the proportion of organosilanepolysulfane, an integer of 6, does not exceed 20% by weight in the mixture. The composition of claim 2, wherein the ratio of the organosilanepolysulfane in which z is 0 is less than about 58 to 80%, and the ratio of the organosilanepolysulfane in which z is 1 is greater than 0 to about 32% (wherein The sum of these compounds is at least 80%), a mixture characterized in that the proportion of organosilanepolysulfanes with z of 2 to 6 is no more than 20%. The rubber component (s), the mixture according to any one of claims 1 to 3, the silicate filler and the carbon black present at random are optionally kneaded together with a plasticizer, an antioxidant and an activator (optionally a Banbury internal mixer). ], The mixture is kneaded for 3 to 15 minutes in a single or multi-stage at 160 to 200 ° C., and then the vulcanizing aid is added at 60 to 120 ° C. in a Banbury internal mixer or roll mill, and further 2 to 10 at 60 to 120 ° C. Continue blending for minutes, followed by rolling the processed gum blend into sheets or strips to cure with sulfur and / or sulfur donors and accelerators and to natural rubber or synthetic rubber, light colored oxides (silicates) A method of making a rubber blend containing one or more fillers, optional carbon black and additional ingredients. The light colored oxide filler used is a natural filler (clay, siliceous choke) and / or precipitated silica or silicate, the amount of which is 10 to 200 parts, preferably 25 to 100 parts of the polymer. 80 parts. The filler according to claim 4 or 5, wherein the filler has a BET surface area (ISO 5794 / 1D) of 1 to 700 m ² / g, wherein the precipitated silica and silicate still have a DBP value (ASTM D 2414) of 150 to 300 ml / 100 g. Is used. The oxide filler according to claim 4, wherein an oxide filler mixed with and / or pretreated with the organosilanepolysulfane mixture described in claim 1 is used and the amount of the mixture according to claim 1 is used. 0.5 to 30 parts per mole. A tread formulation for a tire with an elevated proportion of silica, characterized by containing 4 to 10 parts of the mixture according to any one of claims 1 to 3 with respect to 100 parts of filler. ※ Note: The disclosure is based on the initial application.