HK1216320B - Ndbr wet masterbatch and the production process and use thereof - Google Patents

Description

NdBR wet master batch and preparation method and application thereof

The present application is a divisional application of chinese patent application No.201280058594.0 entitled "NDBR wet masterbatch" filed on day 2012, 10, 26.

Technical Field

The present invention relates to NdBR wet masterbatch for producing vulcanized rubber with improved rolling resistance, and to their production and use.

Background

Many economically interesting products are formed from elastomeric compositions by dispersing fillers in a wide variety of different synthetic elastomers, natural rubbers or elastomer mixtures. For example, carbon black is widely used as a reinforcing agent in natural rubber and other elastomers. In order to enable such mixtures to be used in particular application areas, it is common to produce so-called masterbatches, i.e. a premix of fillers, elastomers and various optional additives (for example extender oils).

It is generally understood that the properties of carbon black affect the properties of the rubber or polymer compound containing the carbon black. In tire production, it is often desirable to use tire tread compounds containing carbon black with satisfactory filler distribution and filler incorporation. The better the filler bonding of the rubber compound, the smaller the Payne effect and the smaller the energy dissipation resulting from the free flow between the polymer matrix and the filler on the tire tread produced from the rubber compound, and the smaller the rolling resistance and therefore the higher the fuel savings achievable while running.

In tire production, it is also often desirable to use tire tread compounds that incorporate carbon black having satisfactory hysteresis. The hysteresis of the rubber compound relates to the energy released upon deformation. A tire produced from a tread having a lower hysteresis value will have a reduced rolling resistance, which will result in a reduced oil consumption of the vehicle in which the tire is used.

The prior art discloses various carbon blacks of different structures. By using these different kinds of carbon blacks, carbon black master batches of different qualities suitable for use in different fields are produced. Not only does the choice of carbon black play a major role in the production of carbon black masterbatch, another important factor is the choice of elastomeric composition. For example, there are different possible elastomeric compositions available for treads or profiles, sidewalls, steel meshes and carcasses, only for the field of automobile tires.

Other areas of use include, for example, engine mounting bushings, conveyor belts, and the like.

Although a wide range of performance characteristics can be achieved using currently available materials and production techniques, there is a continuing need in the industry to develop elastomeric compositions that have improved properties and reduce the cost and complexity of current production techniques.

The production of this masterbatch involves the production of carbon black or another filler with intensive mixing with natural rubber or another elastomer, which requires long and relatively intensive mixing, with the following disadvantages: increasing energy costs, production time and similar problems arise.

It is also known that for carbon blacks having specific surface and structural characteristics, it is not possible or commercially feasible to produce economically available masterbatches using conventional mixing equipment and techniques.

An important factor in achieving good quality and consistency of the masterbatch is the good dispersion of the carbon black in the rubber compound.

It is well known that carbon blacks having higher or lower structure and specific surface area can be used to obtain the performance characteristics of elastomeric compositions. For example, carbon blacks having a higher specific surface area and a lower structure are known to improve resistance to fracture growth and stability to cutting and chipping, as well as resistance to abrasion and other qualities.

In general, the masterbatch is produced in a dry mixing technique by processing the elastomer composition with carbon black or another additive, by repeated mixing in a kneader and/or roller press with long intermediate storage times.

In addition to these dry mixing techniques, it is known that latex and carbon black slurry can be continuously supplied to a coagulation tank while being stirred. This "bulk" technology is generally used in the context of synthetic elastomers. The coagulation tank contains a coagulant, such as salt or an acidic aqueous solution (typically having a pH of 2.5 to 4). The latex and carbon black slurry were mixed in a coagulation tank and coagulated into small wet crumbs. The effluent of the chips and acid are separated from each other and the chips are then poured into a second tank having agitation means where they are washed. Then, a drying step is introduced.

This process is described in US 4,029,633. US patent 3,048,559 also describes this production process wherein an acid or salt coagulant solution is added.

Disclosure of Invention

It has now been found that a particular type of carbon black has particularly good suitability for the production of NdBR masterbatches, its processability and the vulcanizates obtained therefrom having improved properties.

It is therefore an object of the present invention to provide NdBR wet masterbatch which can be used to produce vulcanized rubber with improved properties and during the production thereof, processing steps can be reduced and thus also the production costs.

To achieve this object, an NdBR wet masterbatch is proposed which comprises a neodymium-catalyzed polybutadiene having a high proportion of neodymium-catalyzed polybutadiene>95% cis-1, 4 units and a low proportion of<1% of 1, 2-vinyl groups, having a narrow polydispersity of less than 3, having a Mooney viscosity (ML) of between 30 and 90MU₁₊₄100 ℃), has a high linearity index (ratio of solution viscosity to Mooney viscosity) between 3 and 10mPas/MU and has a Mooney relaxation after 30 seconds between 2% and 12%, the latter being prepared by solution polymerization;at least one carbon black having an iodine absorption value (ION) of between 80 and 210mg/g, as determined according to ASTM D1510-1304, and an oil absorption value (OAN) of between 75 and 150ml/100g, as determined according to ASTM D2414; and an oil. It has been found that, surprisingly, it is possible to use this carbon black type and this NdBR to produce NdBR wet masterbatch which is suitable for producing vulcanized rubber for vehicle tires having improved rolling resistance and which is at the same time produced in an economically advantageous and simple manner.

Detailed Description

Typically, carbon black is characterized based on analytical properties. The specific surface area of the carbon black is reported as the iodine uptake value (ION) and unbound iodine is determined by iodometric titration using back titration with sodium thiosulfate solution.

The Oil Absorption Number (OAN) is determined by void volume measurement, similar to test method ASTM D2414-09. For this purpose, the oil is titrated at a constant rate into a sample of dry carbon black particles in a kneader. The oil was mixed with carbon black. After filling the void volume of the carbon black particles, the surfaces of the carbon black particles are wetted and the particles adhere to each other before they are distributed into the liquid oil phase. The maximum torque describes the OAN.

Polybutadiene is used as an important component of rubber mixtures in the tire industry, where it is desirable to improve the final properties, such as reducing rolling resistance and wear. Polybutadienes having a high proportion of cis-1, 4 units have been produced on a large industrial scale for some time and are used for the production of tires and other rubber products, and for the impact modification of polystyrene.

In order to achieve high proportions of cis-1, 4 units, particularly effective catalysts based on rare earth compounds are currently being used, and these are described, for example, in EP-A10011184 and EP-B-A10007027.

It is known from the prior art that, of the group of high-cis polybutadienes, in particular neodymium-catalyzed polybutadienes have particularly advantageous properties with regard to rolling resistance, wear resistance and resilience.

It is known to the person skilled in the art that polybutadienes having a narrow polydispersity are produced using single-site catalysts defined by the structure of allyl complexes based on rare earths, as described, for example, in the polymer chemistry and physics, 2002(203/7) 1029-.

The catalyst system used plays an important role in the production of polybutadiene.

Neodymium catalysts used in industry are, for example, Ziegler/Natta systems (Ziegler/Natta systems) formed of several catalyst components. In the ziegler/natta catalyst system, the known 3-component catalyst (usually consisting of a neodymium source, a chloride source and an organoaluminum compound), which is prepared for polymerization (with or without aging), is mixed in a number of different ways under specific temperature conditions.

The polybutadienes are preferably those which are catalyzed by neodymium-containing systems. This system is a ziegler-natta catalyst based on neodymium compounds, soluble in hydrocarbons.

The neodymium compounds used are more preferably neodymium carboxylates, neodymium alkoxides or neodymium phosphonates, in particular neodymium neodecanoate, neodymium octanoate, neodymium naphthenate, neodymium 2, 2-diethylhexanoate and/or neodymium 2, 2-diethylheptanoate.

The minimum Polydispersity (PDI) is known to produce excellent properties in tire blends, such as low rolling resistance, high resilience, or low tire wear. The polydispersity is usually determined by Gel Permeation Chromatography (GPC) and corresponds to the ratio of the weight-average molar mass Mw to the number-average molar mass Mn and thus represents the width of the distribution of molar masses.

The broad distribution of the molar masses shows good processing characteristics of the rubber and rubber mixtures, which is indicated, among other things, in lower mixing viscosities, lower mixing times and lower extrusion temperatures. However, overall tire performance is adversely affected.

In contrast, a low polydispersity has a corresponding influence on the processing properties of the polybutadienes mentioned above.

Preferred are oils having a glass transition temperature (Tg) between-80 ℃ and-40 ℃ and an extractables level of less than 3% by weight extracted with DMSO according to the IP 346 method.

Preferred are hydrogenated naphthenic oils in which the sum of polycyclic aromatics is less than 10ppm and the amount of α -benzopyrene is less than 1ppm, as determined by the Grimmer test, published in Freenius, Analyticche Chemie (analytical chemistry, 1983, volume 314, p.29-36, according to the method of teaching Grimmer, Hamburg-Ahrensburg.

Furthermore, carbon black has an iodine absorption value of between 85 and 210mg/g, preferably between 95 and 210mg/g, more preferably between 100 and 160mg/g, determined according to ASTM D1510-1304, and an oil absorption value of between 75 and 150ml/100g, preferably between 80 and 140ml/g, more preferably between 85 and 120ml/g, determined according to ASTM D2414.

The unit phr (parts per hundred parts rubber by weight) used in this document is the usual unit of quantity used in the rubber industry for blend formulations. The dosage of the substances per part by weight is always based on 100 parts by weight of the total polybutadiene.

The amount of carbon black is at least 30 to 100phr of carbon black based on the total polybutadiene content.

The expression "charge" or "charge level" relates to the amount of carbon black used in the compounding of the rubber and the introduction of the carbon black. In general, rubber compounds having excellent abrasion resistance and tire tread abrasion resistance are also produced, the amount of carbon black of the present invention, ranging from about 30phr to about 100phr, may be used for 100 parts by weight of the total polybutadiene content in each case.

The oil to be used is between 0.1phr and 30phr, based on the total polybutadiene.

It is preferred to use more carbon black than oil, the difference between the phr of carbon black and the phr of oil being 70 or less.

To ensure adequate dispersion of the carbon black component in neodymium-catalyzed polybutadiene, the Masterbatch Factor (MF) is 130 or less. The master batch factor is calculated as follows:

mooney viscosity of MF-Nd catalyzed polybutadiene- [ phr of carbon black-phr of oil ]

Longer and relatively vigorous mixing can achieve better dispersion of the carbon black in the polymer (i.e., filler distribution), but this also increases the reduction in the molar mass of the polymer, which is undesirable.

It is preferred that the neodymium-catalyzed polybutadiene have the following properties:

mooney viscosity (ML)₁₊₄100 ℃) between 40 and 85MU, preferably between 44 and 65MU,

the linearity index (ratio of solution viscosity to Mooney viscosity) is between 4 and 8mPas/MU,

mooney relaxation after 30 seconds of between 4% and 8%

Polydispersity < 2.2.

A further invention is an NdBR masterbatch comprising

100phr of a neodymium-catalyzed polybutadiene,

from 50 to 70phr of carbon black,

from 3 to 10phr of an oil,

from 0.2 to 2phr of a stabilizer,

and optionally other auxiliaries.

The invention further relates to a process for producing NdBR masterbatch, which process involves a solution mixing operation.

A preferred method according to the invention comprises the steps of:

a) mixing a neodymium-catalysed polybutadiene prepared by solution polymerization with carbon black having an iodine absorption value (ION) of between 85 and 210mg/g, determined according to ASTM D1510-1304, and an oil absorption value (OAN) of between 75 and 150ml/100g, determined according to ASTM D2414, the carbon black being suspended in a liquid, preferably in water, hexane or a water/hexane mixture prior to mixing,

b) after or before or during which an oil is added,

c) adding a stabilizer and

d) optionally with the addition of further auxiliaries,

e) the liquid is then removed.

In one embodiment, the components may be mixed in any order in steps a) -c) and, if present, d).

Selecting a particular carbon black type that is pretreated reduces the mixing stage.

Typically, NdBR masterbatch is produced in 5 mixing stages, mixing stage 1 involving kneading the mixture at one specific temperature and then repeating folding in a roller press (doubleling). Thereafter, the compound is stored for an extended period, typically 24h, so that the compound can cool down. This storage is particularly important to be able to introduce the necessary mixing energy in the subsequent mixing stage. The pre-mixture is then mixed again in a kneader at a higher temperature, then folded in a roll press and rolled again. Different mixture components can be added at each stage.

The process of the invention produces this NdBR masterbatch in only 2 mixing stages, the first mixing stage involving kneading these components and then folding in a roller press with the masterbatch of the invention.

Step a) is preferably carried out until homogeneity is reached, using the neodymium-catalysed polybutadiene prepared, which is dissolved in the polymerization solvent.

It is preferred to use 10% to 35% carbon black liquid suspension in step a).

In one embodiment, a 10% to 30% carbon black liquid suspension is used for step a).

The liquid used is preferably an aliphatic hydrocarbon, which may have the same composition as the butadiene polymerization solvent, or a protic solvent such as water.

The solvent and suspension liquid are removed by a stripping process or by concentration by evaporation.

A further invention is the use of NdBR wet masterbatch for the production of rubber compounds for tires, conveyor belts and shoe soles.

Tires, conveyor belts and shoe soles comprising the NdBR wet masterbatch of the invention likewise form part of the subject matter of the invention.

The invention is further illustrated by the following examples.

Examples of the invention

The following polybutadienes were used:

1.1 Neodymium-catalyzed polybutadiene of the BUNACB 22 type from Lanxess Deutschland GmbH with the following properties:

cis-1, 4 units 97.8%;

0.5% of 1, 2-vinyl units;

the molecular weight Mn is 235 kg/mol;

polydispersity Mw/Mn of 2.1;

mooney viscosity (ML)₁₊₄100℃)＝64.9MU；

Solution viscosity (5.43% in toluene, 20 ℃) 400 mPas;

linearity index (ratio of solution viscosity to mooney viscosity) 6.2 mPas/MU;

mooney relaxation after 30 seconds was 4.8%

The following carbon blacks were used:

2.1 Carbon Black N231 from KMF Laborchemie Handels GmbH with the following properties:

iodine adsorption number (ION) of 121 mg/g;

the Oil Absorption Number (OAN) was 92ml/100 g.

Or

2.2 Carbon Black N326 from KMF Laborchemie Handels GmbH with the following properties:

iodine adsorption number (ION) of 82 mg/g;

the Oil Absorption Number (OAN) was 72ml/100 g.

Table 1: composition of master batch

Example M:

production of the masterbatch of the invention Using N231 and Buna CB22

A60L stirred tank was initially charged with 19kg of a 9.54% Nd-BR Buna CB22 technical hexane solution at a temperature of 20 ℃. 1.09kg of N231 carbon black was initially charged into a 30L stirred tank, 6kg of hexane was added, and the mixture was stirred using a bucket with a stirrer at 700 rpm. The carbon black mixture was subsequently added to the polybutadiene solution while stirring over 2 hours. Subsequently, 90.6g of TDAE oil and 18g of molten Vulkanox4020 stabilizer were added, and then the mixture was stirred for another 15 min. The solvent was removed by steam distillation in a continuous one-stage stripping column. The wet master batch was dried to constant mass in a vacuum drying oven at 60 ℃.

Comparative example M1:

masterbatch production using Buna CB22 and N326

A60L stirred tank was initially charged with 19kg of a 9.54% Nd-BR Buna CB22 technical hexane solution at a temperature of 20 ℃. 1.09kg of N326 carbon black was initially charged into a 30L stirred tank, 6kg of hexane was added, and the mixture was stirred using a bucket with a stirrer at 700 rpm. The carbon black mixture was subsequently added to the polybutadiene solution while stirring over 2 hours. Subsequently, 90.6g of TDAE oil and 18g of molten Vulkanox4020 stabilizer were added, and then the mixture was stirred for another 15 min. The solvent was removed by steam distillation in a continuous one-stage stripping column. The wet master batch was dried to constant mass in a vacuum drying oven at 60 ℃.

Production of vulcanized rubber mixtures using the masterbatches produced above

To determine any change in properties, the cured rubber mixtures were produced and tested.

Table 2: formulation of the mixture

Phr parts per hundred rubber

Corax N326 and N231 are carbon blacks from KMF Laborchemie Handels GmbH

Vivatec 500 is an oil from Hansen & Rosenthal

Zinc white, red seal grade, is zinc oxide from Grillo Zinkoxid GmbH

EDENOR C1898-100 is stearic acid from Cognis Deutschland GmbH

4020/LG andHS/LG is a stabilizer from Langshan Germany Ltd

CZ/C is a catalyst from Langshan Germany Ltd

Antilux 654 is a stabilizer from Rhein Chemie Rheinau GmbH

RHENOGLAN IS 60-75 IS sulfur from LEINO CHEMICAL LEIN CORPORATION

Example VM and comparative example VM1

Production of a cured rubber mixture using the masterbatch

Production was carried out according to the formulation in Table 2 in a 350ml Brabender at 40 rpm. After mixing for 5min, the mixture was processed using a roller press, the resulting molten sheet was cut three times on the right and left sides, and the sheet was folded three times.

Comparative example V1

Production of vulcanized rubber mixtures without the use of masterbatches

Production was carried out according to the recipe in Table 2 in a 350ml Brabender at 40 rpm. In the first stage, Buna CB22, carbon black, oil and stabilizer components were mixed. After mixing for 5min, the mixture was processed on a roller press, the resulting molten sheet was cut three times on the right and left sides, and the sheet was folded three times. The premix was stored overnight, during which time it was cooled to room temperature. In the third stage, the premix was mixed with the remaining ingredients in a Brabender at 40 rpm. After mixing for 5min, the mixture was processed using a roller press, the resulting molten sheet was cut three times on the right and left sides, and the sheet was folded three times.

Table 3: characteristics of example VM of the present invention and comparative example V1

Table 3 shows the characteristics of the example VM of the present invention and the comparative example V1. The change from comparative example V1 to inventive example VM is expressed as a percentage, where comparative example V1 has been defined as 100%. The inventive example VM had a much better filler distribution, as can be seen from the decrease in mooney viscosity; and improved rolling resistance characteristics, increased resilience from 60 ℃ and reduced loss factor tangent delta (tan d) at 60 ℃ are evident.

Claims (4)

1. Process for producing NdBR wet masterbatch, characterized in that it comprises the following steps:

a) carbon black is suspended in a liquid to form a liquid suspension of carbon black,

wherein the carbon black has an iodine absorption value of 95 to 210mg/g, as determined according to ASTM D1510-1304, and an oil absorption value of 80 to 140ml/100g, as determined according to ASTM D2414, and

wherein 10% to 30% carbon black is present in the liquid suspension of carbon black;

b) mixing a neodymium-catalyzed polybutadiene prepared by solution polymerization, a liquid suspension of the carbon black, an oil and a stabilizer,

the neodymium-catalyzed polybutadiene has a high proportion>95% cis-1, 4 units and a low proportion<1% 1, 2-vinyl content, having a narrow polydispersity as determined by gel permeation chromatography of less than 3, having a ML between 30 and 90MU₁₊₄A Mooney viscosity at 100 ℃, having a high linearity index of 3 to 10mPas/MU, which is the ratio of the solution viscosity to the Mooney viscosity, and a Mooney relaxation after 30 seconds of 2% to 12%,

wherein the oil to be used is from 0.1phr to 30phr, based on the total polybutadiene,

wherein the master batch factor MF is less than or equal to 130, and the master batch factor is calculated according to the following formula: mooney viscosity of MF-neodymium catalyzed polybutadiene- (phr of carbon black-phr of oil); and

c) the liquid is then removed by a stripping process.

2. The method according to claim 1, wherein the neodymium-catalyzed polybutadiene prepared by solution polymerization, the liquid suspension of carbon black, the oil, and the stabilizer are mixed in step b) in any order.

3. The method of claim 2, wherein step b) is performed until homogeneity is achieved.

4. The process according to claim 3, wherein the prepared neodymium-catalyzed polybutadiene is used dissolved in a polymerization solvent.