DE202011110368U1 - rubber preparations - Google Patents

Abstract

Rubber preparations containing at least one rubber, triacetin and at least one filler from the series cellulose and / or cellulose derivative.

Description

The present invention relates to novel rubber formulations containing cellulose and / or cellulose derivatives and triacetin, their use for the preparation of rubber vulcanizates and the rubber vulcanizates prepared therefrom and to a new additive for rubber.

20 to 25 percent of the fuel consumption of a car results from the rolling resistance of tires, with trucks it is even around 30 percent. These values have led the EU Commission to oblige the automotive industry to use low-rolling resistance tires by regulation. For new cars, the obligation comes into force in 2011. However, the much larger part of the market is made up of tires that are used to replace old and worn-out tires. From 2012 these will need to be labeled in terms of fuel efficiency, wet grip and rolling noise. Similar to the system already known from household appliances, classes from A (best performance) to G (worst performance) should bring more transparency to the consumer and serve as a decision-making aid in the purchase of new tires.

At least since the European Union has been concerned with the limit values for car-body carbon dioxide emissions, car manufacturers are looking for economic opportunities to reach the target of no more than 130 g / km of CO ₂ emissions. Significant importance is given to low rolling resistance tires. They perform less deformation work during unwinding and therefore lower fuel consumption. The tighter the tire tread adheres to the road, the greater the energy loss due to friction and deformation. It follows that the rubber compound for the tire tread must not be too soft.

In order to reduce the rolling resistance but not at the expense of other important properties, the requirements for wet grip and rolling noise are also set at the same time. A first hint for the assessment of wet skid behavior and rolling resistance is the loss factor tanδ. At 0 ° C this should be as high as possible (good wet skid resistance), as low as possible at 60 to 70 ° C (reduction of rolling resistance).

Thus, there is a great need for improved rubber formulations which, when used in tire manufacturing, result in products having improved properties such as lower rolling resistance and rolling noise and better wet grip.

It is known to add reinforcing fillers to the rubber compositions in order to improve said properties. Reinforcing fillers may be carbon black, silica, cellulose and phyllosilicates.

The term reinforcement of elastomeric materials is generally understood as meaning the extension of the service life, the improvement of the mechanical properties, such as strength, abrasion or rolling resistance, but also the improvement of the dynamic properties due to the interaction between polymer matrix and filler.

While these reinforcing fillers can often improve product properties, they often have a negative impact on the processability of the rubber composition. For this reason, it is customary to add to the rubber mixture in addition to the reinforcing fillers also auxiliaries which are intended to improve the processability of the rubber mixture. For example, this fatty acid esters, fatty acid salts or plasticizer oils are used, which should improve the flowability of the rubber mixture. Although the abovementioned additives have the advantage that they lower the flowability of the rubber mixture (low Mooney viscosity), but at the same time increase or reduce the stress values at greater elongation (eg 100% to 300%) that it reduces the hardness of the Reduce vulcanizates, so that the reinforcing effect of the filler suffers loss. Too low a hardness or stiffness of the vulcanizate, however, can in turn adversely affect the product properties. Thus, a too low hardness of Vulkanisates results in unsatisfactory driving behavior of a car tire produced therefrom, especially in curves. Although an increase in the dosage of reinforcing filler leads to an increase in the hardness of the vulcanizate, but at the same time also to a higher mixing viscosity, which in turn proves to be detrimental to the processability of the vulcanizate. The same applies to a reduction of the plasticizer oil.

In the production of vulcanizates for automobile tire treads, the use of silica has proven to be a filler. Here, the silica contributes to a good combination of properties of rolling resistance, wet skid resistance and abrasion.

In order to achieve the desired combination of properties, it is important to disperse the silica well in the rubber preparation and to couple it optimally to the rubber matrix during vulcanization. It is known from the prior art that the rubber mixture contains sulfur-containing organic silanes (cf. DE-A 24 47 614 )) or certain polysulfidic silanes (cf. EP-A1 0 0670 347 and US-A-4,709,065 ) as reinforcing additives. However, the polysulfidic silanes require relatively large amounts of these expensive additives to achieve acceptable processability.

Out EP-A 1728821 is already known, short fibers, z. B. cellulose fibers of 0.1-12 mm in length as a filler in a NBR rubber. In order to allow a better dispersibility of the fibers, various plasticizers with a molecular weight> 400 g / mol were used.

In the EP-A 2072574 there is described a sulfur crosslinked rubber composition containing a chemically modified, e.g. As acetylated, microfibrile cellulose contains. This vulcanized rubber composition can be used to make tires. From the EP-A 2072574 It can be seen that addition of 1-50 parts by weight of acetylated cellulose to the rubber gave a 6% higher tan δ value. The expert understands by a deterioration of rolling resistance. Thus, those skilled in the art will understand from this document that cellulose and its derivatives, as fillers in rubber compounds, in the tires made therefrom, lead to a deterioration in rolling resistance.

It is generally known that rubber formulations may contain plasticizers. They interact with the rubber and lead to a higher mobility of the chain segments and possibly to the dissolution of crystalline areas. They cause the tension value, the hardness decrease and the elasticity and cold resistance increase. There are mineral oil softeners such as paraffinic, napthenic and aromatic as well as synthetic plasticizers which can be classified into aliphatic and aromatic esters, polyesters, phosphates, ethers and thioethers. Representatives of the ester plasticizers are u. a. Phthalic acid esters, aliphatic esters, phosphoric esters, adipic esters, trimilitates, citric esters, glycol esters.

The use of triacetin as a softening agent for cellulose acetate is in GB 317443 described.

The object of the present invention was to provide improved filler-containing rubber formulations which have good processing properties and which furthermore lead to vulcanizates and tire treads produced therefrom which have a reduced rolling resistance.

New rubber formulations containing cellulose and / or cellulose derivatives as filler and triacetin as plasticizer have been found.

Surprisingly, the new rubber formulations have longer scorch times in combination with shorter vulcanization times and are thus characterized by improved processability without adversely affecting the properties of rubber vulcanizates produced therefrom, such as hardness, elongation at break, tensile strength, abrasion. Surprisingly, the vulcanizates produced from the new rubber formulations also have an improved surface quality, which is manifested, for example, by an improved rolling resistance of the automobile tire treads produced therefrom.

In addition to expanding the range of technical applications, economic and ecological aspects are increasingly playing an important role. Not only rising commodity prices, but also the increased sensitivity of modern society to environmental issues in the production, use and disposal of materials, are motivating the industry to push forward with resource-saving production methods and bring environmentally friendly and consumer-friendly products to market ,

Against this background, a further advantage of the rubber preparations according to the invention is the fact that their ingredients cellulose and triacetin can be obtained from renewable raw materials. Triacetin is made from vegetable glycerine; Cellulose derived from vegetable fibers.

The present invention relates to rubber formulations containing at least one rubber, triacetin and at least one filler from the series cellulose and / or cellulose derivative.

In the technical literature, the ratio of the remaining constituents to the rubber component is usually stated in the relative quantity phr "parts per hundred parts rubber" in rubber formulations. This quantity is also to be used here below.

The rubber preparation according to the invention generally contains 0.1 to 100 phr of at least one cellulose and / or cellulose derivative, preferably 0.2 to 50 phr, more preferably 0.3 to 30 phr.

The rubber preparation according to the invention generally contains from 0.1 to 80 phr of triacetin, preferably from 0.2 to 60 phr and more preferably from 0.5 to 45 phr, in particular from 5 to 30 phr.

rubber

NR:

Naturkautschuk

SBR:

Styrol/Butadienkautschuk

BR:

Polybutadienkautschuk

IR:

Polyisopren

SIBR:

Styrol/Isopren-Kautschuk

NBR:

Nitrilkautschuk

IIR:

Butylkautschuk (Isobuten/Isopren-Kautschuk)

HNBR:

Hydrierter Nitrilkautschuk

SNBR:

Styrol/Butadien/Acrylnitril-Kautschuk

CR:

Polychloropren

XSBR:

carboxylierter Styrol/Butadien-Kautschuk

XNBR:

carboxylierter Butadien/Acrylnitril-Kautschuk

ENR:

epoxydierter Naturkautschuk

ESBR:

epoxydierter StyrolButadien-Kautschuk

und Mischungen davon.The rubber composition according to the invention comprises at least one rubber. Preference is given to those rubbers based on dienes, such as, in particular, double bond-containing rubbers which contain virtually no gel fraction and which are suitable for use in accordance with the invention DIN / ISO 1629 be referred to as R rubbers. These rubbers have double bonds in the main chain. Preferred rubber components are, for example, those based on

NO:

natural rubber

SBR:

Styrene / butadiene rubber

BR:

polybutadiene rubber

IR:

polyisoprene

SIBR:

Styrene / isoprene rubber

NBR:

nitrile rubber

IIR:

Butyl rubber (isobutene / isoprene rubber)

HNBR:

Hydrogenated nitrile rubber

SNBR:

Styrene / butadiene / acrylonitrile rubber

CR:

polychloroprene

XSBR:

carboxylated styrene / butadiene rubber

XNBR:

carboxylated butadiene / acrylonitrile rubber

ENR:

epoxidized natural rubber

ESBR:

epoxidized styrene-butadiene rubber

and mixtures thereof.

According to the invention, double-bond-containing rubbers also include those which after DIN / ISO 1629 M rubbers are and in addition to the saturated main chain have double bonds in side chains. This includes z. B. EPDM.

Preferred rubbers according to the invention are: NR, BR, SBR, IIR and EPDM.

Particularly preferred are NR, BR and styrene / diolefins and mixtures of these rubbers.

Styrene / diolefin (especially butadiene) rubbers are understood to mean both solution SBR rubbers in short: L-SBR and emulsion SBR rubbers, abbreviated to E-SBR. L-SBR is understood to mean rubbery polymers which are prepared in a solution process based on vinylaromatic compounds and conjugated dienes. Suitable vinylaromatic monomers are styrene, o-, m- and p-methylstyrene, industrial methylstyrene mixtures, p-tert-butylstyrene, p Methoxystyrene, vinylnaphthalene, divinylbenzene, trivinylbenzene and divinylnaphthalene. Preference is given to styrene. The content of copolymerized vinyl aromatic is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. Suitable diolefins are 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 1-phenyl-1,3-butadiene and 1,3-hexadiene. Preference is given to 1,3-butadiene and isoprene. The content of polymerized dienes is generally 50 to 95 wt .-%, preferably 60 to 90 wt .-%. The content of vinyl groups in the copolymerized diene is generally 10 to 90%, the content of 1,4-trans-double bonds is 20 to 80% and the content of 1,4-cis-double bonds is complementary to the sum of vinyl groups and 1, 4-trans-double bonds. The vinyl content of the L-SBR is preferably> 20%.

Usually, the polymerized monomers and the different diene configurations are randomly distributed in the polymer. Also rubbers with a block-like structure, which as Integral rubber are to fall under the definition of L-SBR (A). By L-SBR is meant both linear and branched or end-group modified rubbers.

The solution polymerized vinyl aromatic / diolefin rubbers advantageously have Mooney values between 20 and 150 Mooney units, preferably 30 to 100 Mooney units.

In particular, the high molecular weight E-SBR types having Mooney values> 80 ME may contain oils in amounts of 30 to 100 parts by weight based on 100 parts by weight of rubber. The oil-free L-SBR rubbers have glass transition temperatures of -80 ° to + 20 ° C, determined by differential thermal analysis (DSC).

E-SBR is understood to mean rubbery polymers which are prepared in an emulsion process based on vinylaromatic compounds, conjugated dienes and optionally other monomers. Vinyl aromatics are styrene, p-methylstyrene and alpha-methylstyrene. Dienes are especially butadiene and isoprene. Further monomers are in particular acrylonitrile. The contents of vinyl aromatics are between 10 and 60 wt .-%. The glass transition temperature is between -50 and + 20 ° C (determined by DSC) and the Mooney values between 20 and 150 Mooney units. In particular, the high molecular weight E-SBR types having Mooney values> 80 ME may contain oils in amounts of 30 to 100 parts by weight based on 100 parts by weight of rubber. The oil-free L-SBR rubbers have glass transition temperatures of -80 ° to + 20 ° C, determined by differential thermal analysis (DSC).

Polybutadiene (BR) in particular comprises two different polybutadiene type classes. The first class has a 1,4-cis content of at least 90% and is produced with the help of Ziegler / Natta catalysts based on transition metals. Preferably, catalyst systems based on Ti, Ni, Co and Nd are used. The glass transition temperature of this polybutadiene is preferably <-90 ° C. (determined by means of DSC).

The second polybutadiene type class is made with Li catalysts and has vinyl contents of 10% to 80%. The glass transition temperatures of these polybutadiene rubbers are in the range of -90 to + 20 ° C (determined by DSC).

According to the invention, preference is given to rubbers selected from the group consisting of: styrene / butadiene rubbers and polybutadiene, these rubbers also being able to be drawn with mineral oils.

Cellulose and cellulose derivatives

The rubber preparation according to the invention contains at least one cellulose and / or one cellulose derivative. Commercially available, fibrous or powder / pastille-shaped cellulose (CAS No .: 9004-34-6) is preferably used as the cellulose. As cellulose derivatives are in particular the following reaction products of cellulose
Phenyl isocyanate, n-butyric anhydrides, acetic anhydride, butyl isocyanate, stearyl chloride, stearyl isocyanate, butyric acid chloride in question. Preference is given to cellulose derivatives obtained by esterification of cellulose with carboxylic acids such. As acetic acid are available. Particularly preferred cellulose derivative is cellulose acetate (CAS No .: 9004-35-7). The cellulose can be used alone or in any desired mixture with the cellulose derivatives mentioned. It is preferred to use cellulose acetate alone.

triacetin

The rubber composition according to the invention contains at least one triacetin. Triacetin is also known under the name glycerol triacetate or 1,2,3-propanetriol triacetate (CAS No .: 102-76-1, commercial product of the company. Lanxess Germany GmbH).

additives

The rubber composition according to the invention may optionally contain further additives. As such, for example, conventional fillers, crosslinking systems, sulfur-based vulcanization accelerators, plasticizers, processing agents, aging, UV, and antiozonants and other additives such as tackifier resins, pigments, dyes, blowing agents, adhesives and adhesion promoters, reversion inhibitors in question.

The amount of additives used can vary widely in the rubber preparation according to the invention. In general, the rubber preparation of the invention contains from 0.1 to 100 phr, preferably from 0.1 to 95 phr and more preferably from 0.1 to 90 phr of one or more additives.

fillers

There are several ways to classify fillers. Suitably, the classification according to the interaction with the rubber in reinforcing (active) and inactive fillers.

Inactive fillers:

Carbon black which may be used according to the invention is in particular "carbon" or "carbon black", which is preferably of the gas black, furnace black, lamp black and thermal type black process and according to the new ASTM nomenclature ( ASTM D 1765 and D 2516) as N 110, N 115, N 121, N 125, N 212, N 220, N 231, N 234, N 242, N 293, N 299, S 315, N 326, N 330, N 332, N 339, N 343, N 347, N 351, N 375, N 472, N 539, N 550, N 582, N 630, N 642, N 650, N 660, N 683, N 754, N 762, N 765 , N 772, N 774, N 787, N 907, N 908 N 990, N 991 S 3, etc. can be designated. The carbon blacks used according to the invention preferably have BET surface areas of between 5 and 200 m ² / g.

Carbon black can be added to the rubber preparation according to the invention in amounts of 0 to 120 phr, preferably 1 to 100 phr, particularly preferably 5 to 80 phr.

If the rubber composition according to the invention comprises carbon black, the total amount of hydroxyl-containing oxidic filler and carbon black is preferably from 20 to 160 phr, preferably from 25 to 140 phr.

• – synthetische Silikate, wie Aluminiumsilikat, Erdalkalisilikat, wie Magnesiumsilikat oder Calciumsilikat mit BET-Oberflächen von 20–400 m²/g und Primärteilchendurchmessern von 5–400 nm
• – natürliche Silikate, wie Kaolin und andere natürlich vorkommende Kieselsäuren,
• – Metalloxide, wie Zinkoxid, Calciumoxid, Magnesiumoxid, Aluminiumoxid,
• – Metallcarbonate, wie Calciumcarbonat, Magnesiumcarbonat, Zinkcarbonat,
• – Metallsulfate, wie Calciumsulfat, Bariumsulfat,
• – Metallhydroxide, wie Aluminiumhydroxid und Magnesiumhydroxid,
• – Glasfasern und Glasfaserprodukte (Latten, Stränge oder Mikroglaskugeln)

Other fillers that may be used include:

• Synthetic silicates, such as aluminum silicate, alkaline earth silicate, such as magnesium silicate or calcium silicate with BET surface areas of 20-400 m ² / g and primary particle diameters of 5-400 nm
• Natural silicates such as kaolin and other naturally occurring silicas,
• Metal oxides, such as zinc oxide, calcium oxide, magnesium oxide, aluminum oxide,
• Metal carbonates, such as calcium carbonate, magnesium carbonate, zinc carbonate,
• Metal sulphates, such as calcium sulphate, barium sulphate,
• Metal hydroxides, such as aluminum hydroxide and magnesium hydroxide,
• - glass fibers and glass fiber products (slats, strands or glass microbeads)

Active fillers:

The rubber preparation according to the invention preferably contains at least one further filler from the series of hydroxyl-containing oxidic fillers. The hydroxyl-containing oxidic filler used is preferably a silicon-containing oxidic hydroxyl-containing filler, such as, in particular, silica. Such, in particular hydrophilic silicic acids carry hydroxyl groups, in particular on the surface.

Silica or "silica" is used in particular as fumed silica or as precipitated silica, wherein according to the invention, the precipitated silica is preferred. The precipitated silicas have a specific surface area of 5 to 1000 m2 / g determined by BET, preferably a specific surface area of 20 to 400 m2 / g. They are obtained by treatment of water glass with inorganic acids, preferably sulfuric acid is used. If appropriate, the silicic acids can also be present as mixed oxides with other metal oxides, such as Al, Mg, Ca, Ba, Zn, Zr, Ti oxides.

According to the invention, preference is given to using silicic acids having specific surface areas of 5 to 1000 m 2 / g, more preferably 20 to 400 m 2 / g, in each case determined by BET.

In general, the rubber preparation according to the invention contains from 5 to 100 phr of at least one hydroxyl-containing oxidic filler, preferably from 30 to 100 phr and in particular from 50 to 90 phr, the hydroxyl-containing oxidic filler advantageously comprising at least 30%, preferably at least 50% of the filler fraction on the total amount of fillers used.

The surface of the silica can also be modified by silanes. Such a chemical reaction can be carried out with all fillers having silanol groups on the surface. Silanol groups react relatively easily with silanes to form organic siloxanes. The modification of the OH groups with silanes (mono- and bifunctional organic silanes) improves the interaction with nonpolar rubbers.

Silanes for surface modification of silicic acids

The rubber composition according to the invention may contain one or more monofunctional and bifunctional organic silanes. As silanes are preferably sulfur-containing organosilicon compounds in question. Particularly preferred are sulfur-containing organosilicon compounds which preferably contain one or more alkoxysilyl groups, preferably one or more trialkoxysilyl groups.

Very particularly preferred sulfur-containing organosilicon compounds are bis (tri-ethoxysilyl-propylpolysulfan); Such products are available, for example, commercially under the name Silan Si 75 and as Silan Si 69 (CAS No .: 40372-72-3) from Degussa.

The sulfur-containing organosilicon compounds may be added to the rubber preparation according to the invention in an amount of from 0.1 phr to 14 phr, preferably from 0.2 to 12.

In the event that the rubber preparation according to the invention contains a hydroxyl-containing oxidic filler, it is advantageous to add at least one silane which ensures the attachment of the hydroxyl-containing oxidic filler to the rubber matrix. These silanes are also referred to as reinforcing additives. Suitable silanes are, in particular, those from the series of sulfur-containing organosilicon compounds. Examples which may be mentioned bifunctional organosilanes with crosslinking active groups (vinyl or thio groups). The rubber composition according to the invention preferably contains as reinforcing additive for hydroxyl-containing oxidic fillers at least one bis (triethoxysilylpropyl) tetrasulfide or bis (triethoxysilylpropyl) disulfide,

networking system

The rubber composition of the invention may contain one or more crosslinking systems. As such, sulfur or sulfur donors such as dithiomorpholine (DTDM) or 2- (4-morpholinodithio) benzothiazole (MBSS) are particularly suitable. Sulfur and sulfur donors can be used in amounts of, for example, 0.1 to 15 phr, preferably 0.1 to 10 phr. The crosslinking systems can be used alone or in combination with vulcanization accelerators.

vulcanization accelerators

Examples of suitable vulcanization accelerators are e.g. As mercaptobenzothiazoles, sulfenamides, guanidines, thiuram disulfides, dithiocarbamates, thioureas, thiocarbonates and dithiophosphates etc.

The vulcanization accelerators can be used in amounts of 0.1 to 15 phr, preferably 0.1 to 10 phr.

The rubber preparations produced according to the invention preferably contain at least one vulcanization accelerator. It is also possible to use a plurality of accelerators, if appropriate in combination with customary activators.

reversion

The rubber formulations according to the invention may contain one or more anti-reversion agents, such as, for example, 1,6-bis (N, N-dibenzylthiocarbamoyldithio) hexane (CAS No .: 151900-44-6), 1,3-bis ((3-methyl) 2,5-dioxopyrrol-1-yl) methyl) benzene (CAS No. 119462-56-5) or hexamethylene-1,6-bis (thiosulfate), disodium salt, dihydrate (CAS No .: 5719-73- 3) included. Particularly preferred is 1,6-bis (N, N-dibenzyl-thiocarbamoyldithio) hexane to call. The said anti-reversion agents can be used individually or in any mixture with each other; preferably 0.1 to 20 phr based on the rubber.

Anti-aging agents

Against the action of heat and oxygen, it may be advantageous to add one or more anti-aging agents to the rubber preparation according to the invention. Suitable z. Example, phenolic antioxidants such as alkylated phenols, styrenated phenol, hindered phenols such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol (BHT), 2,6-di-tert Butyl-4-ethylphenol, sterically hindered phenols containing ester groups, thioether-containing sterically hindered phenols, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) (BPH) and sterically hindered thiobisphenols.

If discoloration of the rubber is of no importance, it is also possible to use aminic anti-aging agents, e.g. B. mixtures of diaryl-p-phenylenediamines (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-naphthylamine (PBN), preferably those based on phenylenediamine. Examples of phenylenediamines are N-isopropyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N'-phenyl- p-phenylenediamine (7PPD), N, N'-bis-1,4- (1,4-dimethylpentyl) -p-phenylenediamine (77PD).

Other anti-aging agents include phosphites such as tris (nonylphenyl) phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl 2-mercaptobenzimidazole (MMBI), zinc methylmercaptobenzimidazole ( ZMMBI). The phosphites are generally used in combination with phenolic anti-aging agents. TMQ, MBI and MMBI are mainly used for NBR grades that are vulcanized peroxide. The said anti-aging agents can be added to the rubber mixture according to the invention in customary amounts, for example from 0.1 to 5 phr.

antioxidants

The ozone resistance of the rubber preparation according to the invention can be improved by antioxidants known to the person skilled in the art, for example N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N'-phenyl-p- Phenylenediamine (7PPD), N, N'-bis-1,4- (1,4-dimethylpentyl) -p-phenylenediamine (77PD), enol ether or cyclic acetals. The antioxidants can be added to the rubber mixture according to the invention in customary amounts of, for example, 0.1 to 5 phr.

softener

The rubber composition of the invention may contain conventional plasticizers such as mineral oil and / or synthetic esters such as phthalic acid esters, adipic acid esters, phosphoric acid esters, citric acid esters, benzoic acid esters, trimilitates or esters of acetic acid. The usual amount used here is 0.11 to 80 phr, preferably 0.2 to 60 phr, more preferably 0.5 to 45 phr.

processing aids

The rubber composition of the invention may further contain conventional processing aids. Such processing aids are said to act between the rubber particles and counteract frictional forces in mixing, plasticizing and molding. As a processing aid, the rubber mixture according to the invention may contain all customary for the processing of plastics lubricant in the usual amounts for these additives.

Other additives

Optionally, further additives of the rubber preparation according to the invention may be added, such as flame retardants, blowing agents, antistatics, biocides, mineral oil, tackifiers, blowing agents, dyes, pigments, waxes, resins, extenders, organic acids, vulcanization retarders, vulcanization activators, such as zinc oxide, stearic acid, and zinc stearate, metal oxides and other filler activators such as triethanolamine, trimethylolpropane, polyethylene glycol, hexanetriol, aliphatic trialkoxysilanes or others known in the rubber industry. The usual amounts are here at 1 to 50 phr.

plastics

The rubber composition of the invention may also contain other plastics which act, for example, as polymeric processing aids or impact modifiers. These plastics are selected from the group consisting of the homo- and copolymers based on ethylene, Propylene, butadiene, styrene, vinyl acetate, vinyl chloride, glycidyl acrylate, glycidyl methacrylate, acrylates and methacrylates with alcohol components of branched or unbranched C1 to C10 alcohols. Particularly noteworthy are polyacrylates having identical or different alcohol radicals from the group of C4 to C8 alcohols, in particular butanol, hexanol, octanol and 2-ethylhexanol, polymethyl methacrylate, methyl methacrylate-butyl acrylate copolymers, methyl methacrylate-butyl methacrylate copolymers, ethylene Vinyl acetate copolymers, chlorinated polyethylene, ethylene-propylene copolymers, ethylene-propylene-diene copolymers.

There may be several additives in any combination.

Preference is given to rubber formulations comprising at least one rubber,
0.2 to 50 phr of cellulose and / or cellulose acetate, 0.2 to 60 phr of triacetin and 0 to 10 phr of at least one sulfur / accelerator system and 0 to 95 phr of at least one other additive.

Particularly preferred are rubber formulations containing at least one rubber from the series of synthetic rubbers, 0.3 to 30 phr of cellulose and / or 0.3 to 30 phr of cellulose acetate, and 0.5 to 45 phr of triacetin, 0 to 10 phr of at least one Sulfur / accelerator system from the series of sulfur / sulfenamide systems and 50 to 90 phr of at least one hydroxyl-containing oxidic filler and 0.2 to 12 phr of at least one silane from the series of sulfur-containing organosilicon compounds.

Particular preference is given to rubber formulations containing at least one rubber from the series of styrene-butadiene rubber and polybutadiene, from 0.3 to 30 phr of cellulose and / or from 0.3 to 30 phr of cellulose acetate and from 0.5 to 45 phr of triacetin, from 0 to 10 Phr on at least one sulfur / accelerator system from the series of sulfur / sulfenamide systems, 50 to 90 phr of silica having a BET specific surface area of 5 to 1000 m ² / g and 0.2 to 12 phr of at least one reinforcing additive from the Bis (triethoxysilylpropyl) tetrasulfide and bis (triethoxysilylpropyl) disulfide series.

The rubber preparation according to the invention can be prepared in a manner known per se by mixing, for example, the individual constituents and optionally further additives with one another. The mixing is usually carried out in a batch mixing process (on internal mixers and rolling mills) at a temperature of, for example, 80 to 150 ° C.

In this case, cellulose and / or cellulose derivative and triacetin of the rubber component can be added either individually or as a mixture in any mixing ratio and in any mixing stage of the mixing process.

From the rubber preparations according to the invention can then, in a conventional manner, after addition of conventional vulcanization, in a mixing apparatus at temperatures of for example 150-200 ° C, preferably 130-180 ° C and optionally under pressure of 1 to 100 bar, prepared rubber vulcanizates become.

Another object of the invention is the use of a mixture containing at least one cellulose and / or cellulose derivative and triacetin as an additive for rubber.

The mixtures to be used according to the invention contain at least one cellulose and / or cellulose derivative. The cellulose used is fibrous cellulose (description of pure cellulose (CAS No. 9004-34-6).) Suitable cellulose derivatives are, in particular, the following reaction products of cellulose with phenyl isocyanate, n-butyric anhydride, acetic anhydride, butyl isocyanate, stearyl chloride, stearyl isocyanate or butyric acid chloride ,

Preference is given to cellulose derivatives obtained by esterification of cellulose with carboxylic acids such. As acetic acid are available. Particularly preferred cellulose derivative is cellulose acetate (CAS No .: 9004-35-7). The cellulose can be used alone or in any desired mixture with the cellulose derivatives mentioned.

The mixture to be used according to the invention preferably contains cellulose acetate and triacetin.

The mixture to be used according to the invention generally contains from 99 parts by weight to 1 part by weight of at least one cellulose and / or cellulose derivative and from 1 to 99 parts by weight of triacetin. Preferably, the mixture to be used according to the invention contains 60 to 2 parts by weight of at least one cellulose and / or cellulose derivative and 40 to 98 parts by weight of triacetin, very particularly preferably 50 to 3 parts by weight of cellulose and / or cellulose derivative and 50 to 97 parts by weight of triacetin, most preferably 40 to 4 parts by weight of cellulose and / or cellulose derivative and 60 to 96 parts by weight of triacetin.

The mixture to be used according to the invention is suitable as an additive for rubber. In this case, the above-mentioned as general and preferred rubbers and mixtures thereof come into question. The use of the mixture to be used according to the invention as a rubber additive makes it possible to improve the processability of the rubber preparation. In particular, the scorching times of the rubber preparation are lengthened while the vulcanization times are shortened, without the properties of rubber vulcanizates produced therefrom, such as hardness, elongation at break, tensile strength, abrasion being adversely affected.

The present invention thus also provides a process for the preparation of rubber vulcanizates which comprises reacting at least one cellulose and / or cellulose derivative and triacetin and at least one rubber in the amounts generally or preferred for these components, optionally in the presence of one or more additives such as further fillers, anti-reversion agents, anti-aging agents, antioxidants, plasticizers and processing aids at temperatures of 80 to 150 ° C in a mixing apparatus, such as a mixer, a roller and / or extruder, mixed in a multi-stage mixing process, and in the presence at least one crosslinking system and / or vulcanization accelerator at a temperature of 150 ° C to 250 ° C, preferably 130 to 180 ° C, optionally vulcanized under pressure from 1 to 100 bar.

Another object of the present invention is further a process for the preparation of filled rubber vulcanizates, which is characterized in that at least one rubber, at least one cellulose and / or cellulose derivative and triacetin, at least one hydroxyl-containing oxide filler and at least one mono- or bifunctional organic silane, in each case in the amounts generally or preferably specified for these components, if appropriate in the presence of one or more additives such as, for example, further fillers, anti-reversion agents, anti-aging agents, antioxidants, plasticizers and processing aids at temperatures of 80 to 150 ° C. in a mixing apparatus, for example, a mixer, a roller and / or extruder, mixed in a multi-stage mixing process, and in the presence of at least one crosslinking system and / or vulcanization accelerator at a temperature of 150 ° C to 250 ° C, b evorzugt 130 to 180 ° C, optionally vulcanized under pressure of 1 to 100 bar.

A sulfur crosslinking with the above-mentioned crosslinking systems is preferred in the preparation of the rubber vulcanizates according to the invention.

The addition of the present invention to be used rubber additive and the addition of optionally further additives is preferably carried out in the first part of the mixing process at melt temperatures of 100-200 ° C, but it can also later at lower temperatures (20-100 ° C) z. B. together with sulfur crosslinker and / or accelerator. In this case, the additive according to the invention can be added directly as a mixture of the components cellulose and / or cellulose derivative and triacetin or in the form of the individual components.

The crosslinker and / or the vulcanization accelerator are expediently not added in a mixing step at elevated temperatures, as is carried out for activating the hydroxyl-containing oxidic filler (eg silica) by means of the sulfur-containing organosilicon compounds, since this leads to premature scorching of the mixture would lead. Crosslinkers and / or vulcanization accelerators are therefore preferably incorporated after addition of the sulfur-containing organosilicon compounds at temperatures of preferably below 100 ° C.

The preparation of the rubber vulcanizates according to the invention can be carried out, for example, in the following mixing stages:

1st mixing stage:

• • Rubber (eg mixture of SBR and BR) is placed in an internal mixer and mixed for about 30 seconds
• If necessary, addition of hydroxyl-containing oxidic filler and silane for surface modification (eg addition of two-thirds silica, two-thirds silane, mixing for about 60 seconds and further addition of one-third silicic acid, one-third silane, mixing for ca. 60 seconds)
• • Add cellulose acetate / triacetin mixture and if necessary add soot, oil, anti-aging agents, zinc oxide and ozone protection waxes, mix for about 60 seconds.

This mixing process can be carried out at temperatures of 20 to 200 ° C, preferably in the range of 150 ° C.

2nd mixing stage:

After completion of the first mixing step, the mixing piece is picked up by a downstream rolling mill and formed into a plate, strip or pellets and stored for 24 hours at room temperature.

Processing temperatures are below 60 ° C.

3rd mixing stage:

In the third mixing stage Nachzwicken at 140 to 170 ° C, preferably at 150 ° C, for example, in a kneader / internal mixer.

4th mixing stage:

Addition of additives such as vulcanization accelerators and / or sulfur crosslinkers, preferably on a roll at low temperatures (<80 ° C).

Suitable aggregates for the preparation of mixtures are known per se and include, for example, rollers, internal mixers or mixing extruders.

Another object of the present invention is the use of a rubber composition according to the invention for the preparation of rubber vulcanizates, in particular of filled rubber vulcanizates, and rubber moldings, in particular of tires and tire components.

Another object of the present invention are rubber vulcanizates and rubber moldings, which can be prepared from the rubber compositions of the invention in a known manner by a vulcanization process.

The rubber vulcanizates produced are suitable for the production of various tire components, in particular for tire treads, sub-races, carcasses, sidewalls, reinforced sidewalls for run-flat tires, apex mixtures etc. as well as for the production of technical rubber articles such as damping elements, roller coverings, conveyor belt linings, belts, spinning cops, gaskets, golf ball cores , Shoe soles, etc. Particularly suitable are the mixtures for the production of tire treads, sub-races, carcasses and Apexmischungen. Tires or tire parts also include, for example, running surfaces of summer, winter and all-season tires as well as running surfaces of car and truck tires.

examples

In the following, the present invention will be illustrated by examples without, however, limiting them thereto.

• 1) Buna^® VSL 5025-1 der Lanxess Deutschland GmbH
• 2) Buna^® CB 24 der Lanxess Deutschland GmbH
• 3) Vulkasil S der Lanxess Deutschland GmbH
• 4) Tudalen 1849-1
• 5) Zinkweiss Rotsiegel der Firma Grillo Zinkoxid GmbH
• 6) Edenor C 18 98-100 der Firma Cognis Deutschland GmbH
• 7) 2,2,4-Trimethyl-1,2-dihydrochinolin, polymerisiert (Vulkanox^® HS/LG der Lanxess Deutschland GmbH)
• 8) N-1,3-Dimethylbutyl-N'-phenyl-p-phenylendiamin (Vulkanox^® 4020/LG der Lanxess Deutschland GmbH)
• 9) Antilux^® 654 der RheinChemie GmbH
• 10) Bis(triethoxysilylpropyl)polysulfid (Si 69 der Degussa Hüls AG)
• 11) Corax N 339 der Degussa Hüls AG
• 12) Löslicher Schwefel (Mahlschwefel 90/95° Chancel^® der Firma Solvay Barium Strontium)
• 13) N-Cyclohexyl-2-benzthiazylsulfenamid (Vulkacit^® CZ der Lanxess Deutschland GmbH)
• 14) Diphenylguanidin (Vulkacit^® D/C der Lanxess Deutschland GmbH)
• 15) Celluloseacetate (CAS-Nr.: 9004-35-7) 4 Gewichtsprozent der Firma Eastman und 96 Gewichtsprozent Triacetin (CAS-Nr.: 102-76-1) der Lanxess Deutschland GmbH

Components of the rubber preparations according to the invention:

• 1) Buna ^® VSL 5025-1 Lanxess Germany GmbH
• 2) ^Buna® CB 24 from Lanxess Deutschland GmbH
• 3) Vulkasil S of Lanxess Germany GmbH
• 4) Tudals 1849-1
• 5) zinc white red seal of the company Grillo zinc oxide GmbH
• 6) Edenor C 18 98-100 of the company Cognis Germany GmbH
• 7) 2,2,4-trimethyl-1,2-dihydroquinoline, polymerized (Vulkanox.RTM ^® HS / LG Lanxess Germany GmbH)
• 8) N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (Vulkanox ^® 4020 / LG Lanxess GmbH Germany)
• 9) Antilux ^® 654 from Rhein Chemie GmbH
• 10) bis (triethoxysilylpropyl) polysulfide (Si 69 from Degussa Hüls AG)
• 11) Corax N 339 of Degussa Hüls AG
• 12) soluble sulfur (ground sulfur 90/95 ° chancel ^® from Solvay barium strontium)
• 13) N-cyclohexyl-2-benzthiazylsulfenamid (Vulkacit ^® CZ Lanxess Germany GmbH)
• 14) diphenylguanidine (Vulkacit ^® D / C Lanxess Germany GmbH)
• 15) Cellulose acetates (CAS No .: 9004-35-7) 4% by weight of Eastman and 96% by weight of triacetin (CAS No .: 102-76-1) from Lanxess Deutschland GmbH

Preparation of the rubber vulcanizates according to the invention

Vulcanizates were prepared from the rubber formulations listed in Table 1 for Examples 1 and 2 and for the Reference Example. For this purpose, the respective constituents of Examples 1 and 2 and of the Reference Example were mixed in each case in a multi-stage mixing process, as described below, and the mixtures were then vulcanized at 170 ° C.

1st mixing stage:

• • BUNA ^® CB 24 and Buna ^® VSL 5025-1 was presented in an internal mixer and mixed for about 30 seconds
• • Add two-thirds of VULKASIL ^® S, two-thirds of SI ^® 69 for about 60 seconds
• • Add one third of VULKASIL ^® S, one third of SI ^® 69, and TUDALEN ^® 1849-1, mix for about 60 seconds

Adding CORAX ^® N 339, EDENOR ^® C 18 98-100, cellulose acetate / triacetin mixture ^® VULKANOX 4020 / LG, VULKANOX ^® HS / LG, zinc white and Rotsiegel Antilux ^® 654, mix for about 60 seconds

This mixing process was carried out at a temperature of 150 ° C.

2nd mixing stage:

After completion of the first mixing step, the mixing piece was picked up by a downstream mill and formed into a plate and stored for 24 hours at room temperature.

Processing temperatures are below 60 ° C.

3rd mixing stage:

In the third mixing stage, a Nachzwicken at 150 ° C in a kneader.

4th mixing stage:

Add the additives MAHLSCHWEFEL 90/95 CHANCEL, VULKACIT ^® CZ / C, VULKACIT ^® D / C on a roller at temperatures below 80 ° C.

The rubber preparations and vulcanizates prepared were subjected to the technical tests given below. The determined values are also to be taken from Table 1.

Tests of rubber preparations and vulcanizates:

Mooney viscosity measurement:

The viscosity can be determined directly from the force that rubbers (and rubber compounds) oppose to their processing. With the Mooney shear disk viscometer, a fluted disk is enclosed with sample substance at the top and bottom and moved in a heated chamber at about two revolutions per minute. The force required for this purpose is measured as torque and corresponds the respective viscosity. The sample is usually preheated to 100 ° C for one minute; The measurement takes another 4 minutes, keeping the temperature constant.

The viscosity is given together with the respective test conditions, for example ML (1 + 4) 100 ° C. (Mooney viscosity, large rotor, preheating time and test time in minutes, test temperature).

The viscosities of the rubber formulations listed in Table 1 are measured by means of a Mooney shear disk viscometer.

Furthermore, with the same test, the "scorch" behavior of a mixture can be measured. The chosen temperature in this patent is 130 ° C. The rotor will run until the torque value has increased to 5 Mooney units relative to the minimum value after passing through a minimum (t5). The larger the value (here unit seconds), the slower the scorching takes place (here high scorch values).

Rheometer (Vulkameter) vulcanization time 170 ° C / t95:

The vulcanization process at the MDR (moving rheometer) and its analytical data are reproduced on a Monsanto rheometer MDR 2000 ASTM D5289-95 measured. The results of this test are summarized in Table 2.

At the cure time, the time is measured at which 95% of the rubber is crosslinked. The chosen temperature was 170 ° C.

Determination of Hardness (Shore A):

To determine the hardness of the rubber mixture according to the invention, 6 mm thick rolled skins were prepared from the rubber mixture according to formulations of Table 1. Test specimens with a diameter of 35 mm, whose Shore hardness A values were determined by means of a digital Shore hardness tester (Zwick GmbH & Co. KG, Ulm), were cut from the rolled skins.

Tensile test:

The tensile test is used directly to determine the load limits of an elastomer. The elongation at break is related to the initial length and corresponds to the elongation at break. Furthermore, the force on reaching certain levels of strain, usually 50, 100, 200 and 300% determined and expressed as a voltage value (tensile strength at the specified elongation of 300% or 300 module).

The test results are listed in Table 1.

Dyn. Damping:

Dynamic test methods are used to characterize the deformation behavior of elastomers under periodically changed loads. An externally applied strain alters the conformation of the polymer chain.

In this measurement, the loss factor tan delta is determined indirectly via the ratio between loss modulus G "and storage modulus G '. Table 1 reference example 1 Example 2 phr phr phr BUNA CB 24 30 30 30 BUNA VSL 5025-1 96 96 96 CORAX N 339 6.4 6.4 6.4 VULKASIL S 80 80 80 TUDALS 1849-1 8th 8th 0 EDENOR C 18 98-100 1 1 1 VULKANOX 4020 / LG 1 1 1 VULKANOX HS / LG 1 1 1 ZINKWEISS ROTSIEGEL 2.5 2.5 2.5 ANTILUX 654 1.5 1.5 1.5 SI 69 6.4 6.4 6.4 GROOM 90/95 CHANCEL 1.5 1.5 1.5 VULKACIT CZ / C 1.5 1.5 1.5 VULKACIT D / C 2 2 2 Cellulose acetate / triacetin - 10 20 Mooney Viscosity (ML 1 + 4) DIN 53523 [ME] 91 66 66 Acc. to scorch time ASTM D (MS-t5) 5289-95 sec 1085 1582 1468 Vulcanization time (t95%) DIN 53529 sec 1213 1091 940 hardness DIN 53505 [Shore A] 70 70 69 Module 300 DIN 53504 MPa 16 14 12 elongation DIN 53504 % 338 377 388 tensile strenght DIN 53504 MPa 18 19 16 abrasion DIN 53516 DIN 53516 mm ³ 85 89 94 tan δ (0 ° C) - Indication for wet skid resistance 0.458 0.416 0,399 tan δ (60 ° C) - Indication for rolling resistance 0,147 0,142 0.123

As the results of Example 1 show, the tanδ value at 60 ° C. (indication for the rolling resistance) is reduced by adding 10 phr of the additive cellulose acetate / triacetin according to the invention based on the rubber. At the same time, the flowability (Mooney viscosity) is lowered. In addition, the scorching time and the elongation at break are increased and the vulcanization time is reduced while the wet skid resistance remains constant (> 0.380). If, as in Example 2, dispensed to the amount of plasticizer (TUDALEN 1849-1), but the amount used cellulose acetate / triacetin further increased to 20 phr based on the rubber, it is surprisingly found that the rolling resistance and thus the tanδ value could be significantly reduced without deteriorating the other mechanical properties such as elongation at break, tensile strength and hardness. Also in Example 2, the scorching time and thus the product safety could be increased and the Ausculkanisationszeit be shortened.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2447614 A [0010]
• EP 00670347 A1 [0010]
• US 4709065 A [0010]
• EP 1728821A [0011]
• EP 2072574A [0012, 0012]
• GB 317443 [0014]

Cited non-patent literature

• DIN / ISO 1629 [0024]
• DIN / ISO 1629 [0025]
• ASTM D 1765 [0041]
• ASTM D5289-95 [0109]
• DIN 53523 [0115]
• ASTM D (MS-t5) 5289-95 [0115]
• DIN 53529 [0115]
• DIN 53505 [0115]
• DIN 53504 [0115]
• DIN 53504 [0115]
• DIN 53504 [0115]
• DIN 53516 DIN 53516 [0115]

Claims (13)

Rubber preparations containing at least one rubber, triacetin and at least one filler from the series cellulose and / or cellulose derivative. A rubber composition according to claim 1, characterized in that it contains 0.1 to 100 phr of at least one cellulose and / or cellulose derivative and 0.1 to 80 phr of triacetin. A rubber composition according to claims 1 and 2, characterized in that it contains at least one rubber selected from the group of styrene / butadiene rubbers and polybutadiene rubbers. Rubber composition according to at least one of claims 1 to 3, characterized in that it contains cellulose acetate as cellulose derivative. Rubber composition according to at least one of claims 1 to 4, characterized in that it contains at least one further filler from the series of hydroxyl-containing oxidic fillers. Rubber composition according to at least one of claims 1 to 5, characterized in that it contains silica as a further filler with a BET specific surface area of 5 to 1000 m ² / g. A rubber preparation according to at least one of claims 1 to 6, characterized in that it comprises at least one rubber from the series of synthetic rubbers, 0.3 to 30 phr of cellulose and / or 0.3 to 30 phr of cellulose acetate, 0.5 to 45 phr Triacetin, 0 to 10 phr on at least one sulfur / accelerator system from the series of sulfur / sulfenamide systems, 50 to 90 phr of at least one hydroxyl-containing oxidic filler and 0.2 to 12 phr of at least one silane from the series containing sulfur contains organosilicon compounds. A rubber composition according to at least one of claims 1 to 7, characterized in that it comprises at least one rubber from the series of styrene-butadiene rubbers and polybutadiene rubbers, 0.3 to 30 phr of cellulose and / or 0.3 to 30 phr Cellulose acetate and 0.5 to 45 phr triacetin, 0 to 10 phr on at least one sulfur / accelerator system from the series of sulfur / sulfenamide systems, 50 to 90 phr silica with a BET specific surface area of 5 to 1000 m2 / g and 0.2 to 12 phr of at least one silane from the series bis (triethoxysilylpropyl) tetrasulfide and bis (triethoxysilylpropyl) disulfide. Rubber vulcanizates and rubber moldings obtainable by vulcanization of a rubber preparation according to one of claims 1 to 8. Tire and tire components selected from tire treads, sub-leads, carcasses, sidewalls, reinforced sidewalls for run-flat tires, apex blends containing rubber vulcanizates according to claim 9. Technical rubber articles, such as damping elements, roller coverings, coverings of conveyor belts, belts, spinning cops, seals containing rubber vulcanizates according to claim 9. Golfballkerne containing rubber vulcanizates according to claim 9. Shoe soles containing rubber vulcanizates according to claim 9.