CN116472306A - Process for preparing an elastomeric composition and tyre comprising same - Google Patents

Process for preparing an elastomeric composition and tyre comprising same Download PDF

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Publication number
CN116472306A
CN116472306A CN202180077940.9A CN202180077940A CN116472306A CN 116472306 A CN116472306 A CN 116472306A CN 202180077940 A CN202180077940 A CN 202180077940A CN 116472306 A CN116472306 A CN 116472306A
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Prior art keywords
silica
functionalized
elastomeric
elastomeric composition
tyre
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CN202180077940.9A
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Chinese (zh)
Inventor
S·吉安内利
A·罗塞利
F·贝翁
P·奎因扎尼
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Pirelli Tyre SpA
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Pirelli Tyre SpA
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C1/0016—Compositions of the tread
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C1/0041—Compositions of the carcass layers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
    • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C2001/0033—Compositions of the sidewall inserts, e.g. for runflat
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/002—Physical properties
    • C08K2201/006—Additives being defined by their surface area
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/28—Compounds of silicon
    • C09C1/30—Silicic acid
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/28—Compounds of silicon
    • C09C1/30—Silicic acid
    • C09C1/3081—Treatment with organo-silicon compounds

Abstract

The present invention relates to a process for the preparation of a vulcanizable elastomeric composition, a vulcanizable elastomeric composition obtainable by such process, a structural element of a tire comprising a vulcanized elastomeric material obtained by vulcanizing such vulcanizable elastomeric composition, and a tire comprising such structural element, wherein the process comprises: a mixing step (i) wherein at least one elastomeric polymer is mixed with one or more additives other than a vulcanizing agent to form a non-vulcanizable elastomeric composition; a mixing step (ii) in which the unvulcanizable elastomer composition obtained in the mixing step (i) is mixed with a vulcanizing agent, characterized in that the mixing step (i) comprises: -a first mixing step (ia) in which the at least one elastomeric polymer is mixed with a non-functionalized white reinforcing filler and a coupling agent to form a first elastomeric composition, and a second mixing step (ib) in which the first elastomeric composition is mixed with functionalized silica to form the non-vulcanizable elastomeric composition.

Description

Process for preparing an elastomeric composition and tyre comprising same
Technical Field
The present invention relates to a process for the preparation of vulcanizable elastomeric compositions, in particular vulcanizable elastomeric compositions comprising a combination of non-functionalized silica and functionalized silica. In a further aspect, the present invention also relates to a vulcanizable elastomeric composition comprising a combination of non-functionalized silica and functionalized silica, and to a tire for vehicle wheels comprising at least one structural element made of a crosslinked elastomeric material obtained by vulcanization of a vulcanizable elastomeric composition comprising a combination of non-functionalized silica and functionalized silica, said tire having improved tire properties, in particular rolling resistance, a balance between grip and mechanical properties under all conditions.
Prior Art
Tire manufacturers need to make products with improved wet grip characteristics, low rolling resistance (resulting in lower fuel consumption), and good abrasion and tear resistance at all temperatures.
Among the many solutions proposed, the most commonly employed solutions to meet this need include the replacement of the carbon black normally used as reinforcing filler, in whole or in part, with a white reinforcing filler (typically silica) in the formulation of the tire tread.
In addition to providing excellent reinforcement, silica imparts excellent wet grip and is widely used in tires for both passenger vehicles and motorcycles in summer, winter and all-weather applications.
For such uses, silica having different characteristics is commercially available or can be prepared according to known methods. Typically, highly dispersible commercial silica is used in elastomeric materials for tire treads, typically having a high surface area (BET).
However, although the use of these commercially available silicas results in lower hysteresis and thus lower rolling resistance, this also means a reduction in mechanical properties, in particular in tear resistance, essentially due to the poor affinity of these fillers compared to the elastomeric polymers normally used for the production of tires.
In order for the elastomeric material of the tire tread to have the desired properties, it is therefore important that the silica is uniformly distributed in the elastomeric composition and that it remains so uniformly distributed over time that agglomerates are avoided as much as possible.
The distribution and dispersion of silica in an elastomeric composition depends on both their chemical nature and the mechanical energy used to mix them. In particular, the more similar they are in chemical nature, i.e. the more compatible they are, and the greater the mechanical stresses applied, the better the distribution and dispersion is achieved.
In general, in rubber compounds, coupling agents (also known as compatibilizers) are used to improve the dispersion and compatibilization between silica or inorganic fillers having surface hydroxyl groups and rubber.
The most commonly used coupling agents are polysulfide silane coupling agents, such as bis (3-triethoxysilyl-propyl) tetrasulfide TESPT and bis (3-triethoxysilyl-propyl) disulfide TESPD.
These agents have silane heads that are capable of reacting with the surface hydroxyl groups of the filler and polysulfide units that decompose upon heating to produce mercapto groups that are capable of reacting with the elastomer, but do not always have the best results.
It is in fact known that the thermal decomposition of these polysulfide systems is difficult to control, since it may already take place at low temperatures long before the vulcanization step (see for example the book "Silane Coupling, compounding Precipitated Silica in Elastomers", hewitt, cicllo, william Andrew Publishing,2007, chapter 3, paragraph 3.17). Furthermore, the radical species thus produced have a high reactivity and poor selectivity, resulting in the formation of a mixture of monosulfides and disulfides.
In order to uniformly distribute these polysulfide coupling agents, the internal temperature in the mixer must be carefully controlled to avoid reaction with the elastomer before satisfactory distribution of the silica and the coupling agent itself occurs.
To overcome these drawbacks, the use of functionalized silica, which includes in their structure functional groups capable of reacting with the elastomer, has been proposed.
Some examples of functionalized silica are described in the following patents:
U.S.6184408 in the name of Dow Corning, which describes silica modified with silylating agents such as organosilanes, organosiloxanes and organodisilazanes, substituted with hydrocarbyl groups having mercapto, disulfide or polysulfide functionalities;
U.S. 76887107 in the name of PPG, which describes silicas modified with silylating agents such as bis (alkoxysilylalkyl) polysulfides;
U.S.7569107 in the name of PPG, which describes silica modified with a silylating agent, such as an organosilane functionalized with sulfide, polysulfide or mercapto groups on hydrocarbon residues, in the presence of an anionic, nonionic or amphoteric surfactant;
U.S.9688784 in the name of PPG, which describes silica modified with a silylating agent in the presence of a polymer and an anionic, nonionic or amphoteric surfactant;
U.S.8846806 in the name of PPG, which describes silica modified with a silylating agent such as mercaptosilane in the presence of anionic, nonionic or amphoteric surfactants; and
U.S.2016326374 in the name of Evonik, which describes silica modified with a hydrosilylation agent, such as a sulfur-containing silane.
While the solutions proposed in the art have brought about improvements, the tyre industry has shown a continued interest in finding new solutions suitable for obtaining optimal properties in terms of mechanical properties and hysteresis, while maintaining good stability, processability and cure kinetics of the elastomeric compositions.
Disclosure of Invention
The applicant has studied to further improve the distribution and dispersion of silica in the production of elastomeric compositions for tyre treads, with the aim of obtaining good hysteresis values at all temperatures, i.e. good grip values under both dry and wet conditions, without compromising the rolling resistance and without affecting the mechanical properties of the vulcanised product (i.e. the crosslinked elastomeric material).
Surprisingly, the applicant has found that by using two different types of white reinforcing fillers, in particular at least one non-functionalized white reinforcing filler and at least one functionalized silica, added in two different steps of the process for the preparation of the vulcanizable elastomeric composition, the desired results can be obtained.
In particular, during the experiments, the applicant observed that the complete replacement of the white reinforcing filler with functionalized silica in the conventional process of addition and mixing with elastomeric polymers resulted in obtaining too fast vulcanization kinetics and in insufficient hardness values and static moduli to meet the set aims.
At the same time, the applicant has observed that, although the partial replacement of the white reinforcing filler with functionalized silica achieves an improvement in performance with respect to lower rolling resistance with the same other requirements, it presents problems of processability and of the formation of tears and irregularities during the extrusion of the sheet of elastomeric composition.
The applicant has continued the experiment, with the result that it has surprisingly been observed that the addition of two types of white reinforcing filler, in particular non-functionalized silica and functionalized silica, at different times and mixed with the elastomeric polymer, allows to solve the processability problems, while obtaining an elastomeric composition with better static and dynamic mechanical characteristics, and with hysteresis values predicting good behaviour of the tyre under all temperatures and conditions of use (dry and wet).
Accordingly, a first aspect of the present invention is a process for preparing a vulcanizable elastomeric composition, the process comprising:
A mixing step (i) in which at least one elastomeric polymer is mixed with one or more additives other than a vulcanizing agent to form a non-vulcanizable elastomeric composition,
a mixing step (i i) in which the unvulcanizable elastomer composition obtained in the mixing step (i) is mixed with a vulcanizing agent,
characterized in that the mixing step (i) comprises:
-a first mixing step (ia) in which the at least one elastomeric polymer is mixed with a non-functionalized white reinforcing filler and a coupling agent to form a first elastomeric composition, and
a second mixing step (ib) wherein the first elastomer composition is mixed with a functionalized silica to form the non-vulcanizable elastomer composition.
In a second aspect, the invention consists of a vulcanizable elastomeric composition comprising, for 100phr of elastomeric polymer:
(a) 100phr of at least one diene elastomeric polymer;
(b) From 10phr to 90phr, preferably from 30phr to 70phr, of at least one non-functionalized white reinforcing filler; and
(c) From 5phr to 40phr, preferably from 10phr to 30phr, of at least one functionalized silica.
In a third aspect, the invention relates to a structural element of a tyre for vehicle wheels comprising a vulcanizable elastomeric composition according to the second aspect of the invention.
According to a fourth aspect, the invention consists of a tyre comprising at least one structural element comprising a crosslinked elastomeric material obtained by crosslinking the vulcanizable elastomeric composition according to the second aspect of the invention.
Definition of the definition
For the purposes of this specification and the claims that follow, the term "phr" (parts per hundred parts of rubber) refers to parts by weight of a given component in an elastomeric composition relative to 100 parts by weight of diene elastomeric polymer (vulcanizable polymer). All percentages are expressed as weight percentages unless otherwise indicated.
In the present description and claims, the term "elastomeric polymer" or "rubber" or "elastomer" means a vulcanizable natural or synthetic polymer which, after vulcanization, can be repeatedly stretched to at least twice its original length at room temperature and, after removal of the tensile load, is substantially immediately forcibly restored to about its original length (according to the definition of ASTM D1566-11 standard terminology in connection with rubber).
The term "diene elastomeric polymer" means an elastomeric polymer derived from the polymerization of one or more monomers, at least one of which is a conjugated diene.
In the present description and in the claims, the term "non-vulcanizable elastomeric composition" refers to a product obtained by mixing at least one elastomeric polymer with at least one additive (excluding vulcanizing agents) commonly used in the preparation of tire compounds and possibly heating. The unvulcanized elastomeric composition is made "vulcanizable" by the presence of a vulcanizing agent and possibly other additives of the vulcanization package in the composition itself.
In the present description and in the claims, the term "crosslinked elastomeric material" means a material obtained by vulcanization of a vulcanizable elastomeric composition.
In the present description and in the claims, the term "green" is generally used to denote a material, compound, composition, structural element or tyre which has not yet been vulcanized.
In the present description and in the claims, the term "reinforcing filler" means a reinforcing material generally used in the art to improve the mechanical properties of tire rubber.
The term "vulcanization" refers to a crosslinking reaction in the elastomeric composition induced, for example, by a sulfur-based vulcanizing agent.
The term "vulcanizing agent" means a product capable of converting an elastomeric composition into an elastic and resistant material due to the formation of a three-dimensional network of intermolecular and intramolecular bonds.
The term "cure package" refers to a group of curing agents and one or more curing additives selected from curing activators, accelerators and/or retarders.
Detailed Description
In at least one of the above aspects, the invention may exhibit one or more of the preferred features described below.
Diene elastomer polymers (a)
According to a preferred embodiment, said at least one diene elastomeric polymer (a) may be chosen, for example, from the group of diene elastomeric polymers commonly used in sulfur-crosslinkable elastomeric compositions particularly suitable for the production of tires, i.e. elastomeric polymers or elastomeric copolymers having unsaturated chains, having a glass transition temperature (Tg) generally lower than about 20 ℃, preferably ranging from about 0 ℃ to about-110 ℃.
Preferably, the diene elastomeric polymer has a weight average molecular weight higher than 80.000g/mol.
These polymers or copolymers may be of natural origin or may be obtained by solution, emulsion or gas phase polymerization of one or more conjugated dienes optionally mixed with at least one comonomer selected from monovinylarenes and/or polar comonomers in an amount of not more than 60% by weight.
Conjugated dienes generally contain from 4 to 12, preferably from 4 to 8 carbon atoms and may be selected from, for example: 1, 3-butadiene, isoprene, 2, 3-dimethyl-1, 3-butadiene, 1, 3-pentadiene, 1, 3-hexadiene, 3-butyl-1, 3-octadiene, 2-phenyl-1, 3-butadiene and mixtures thereof. 1, 3-butadiene and isoprene are particularly preferred.
Monovinylarenes which may optionally be used as comonomers generally contain from 8 to 20, preferably from 8 to 12, carbon atoms and may be selected, for example, from: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or aralkyl derivatives of styrene, such as alpha-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolylstyrene, 4- (4-phenylbutyl) styrene and mixtures thereof. Styrene is particularly preferred.
The polar comonomer which may optionally be used may be selected, for example, from: vinyl pyridine, vinyl quinoline, acrylic acid and alkyl acrylates, nitriles or mixtures thereof, such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and mixtures thereof.
Preferably, the diene elastomeric polymers useful in the present invention can be chosen, for example, from: cis-1, 4-polyisoprene (natural or synthetic, preferably natural rubber), 3, 4-polyisoprene, polybutadiene (particularly polybutadiene having a high 1, 4-cis content), isoprene/isobutylene copolymers, 1, 3-butadiene/acrylonitrile copolymers, styrene/1, 3-butadiene copolymers, styrene/isoprene/1, 3-butadiene copolymers, styrene/1, 3-butadiene/acrylonitrile copolymers, and mixtures thereof.
Advantageously, the diene elastomeric polymers used in the present invention may be functionalized.
The functional groups may be incorporated into the elastomeric polymer by methods known in the art, for example by copolymerization with at least one corresponding functionalized monomer containing at least one ethylene unsaturation during the production of the elastomeric polymer; or by subsequent modification of the elastomeric polymer by grafting at least one functionalized monomer in the presence of a free radical initiator (e.g., an organic peroxide).
Alternatively, functionalization may be introduced by reaction with a suitable terminator or coupling agent. In particular, diene elastomeric polymers obtained by anionic polymerization in the presence of an organometallic initiator, in particular an organolithium initiator, can be functionalized by reacting the residual organometallic groups derived from the initiator with suitable terminators or coupling agents such as amines, amides, imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes, aryloxysilanes, alkylthiols, alkyldithiolsilanes, carboxyalkylthiols, carboxyalkylthiolsilanes and thioglycols.
Useful examples of terminators or coupling agents are known in the art and are described, for example, in patents EP2408626, EP2271682, EP3049447A1, EP2283046A1, EP2895515A1, WO2015/086039A1 and WO2017/211876 A1.
Preferably, the at least one functionalized elastomeric polymer is obtained from polybutadiene (in particular polybutadiene having a high 1, 4-cis content), styrene/1, 3-butadiene copolymers, styrene/isoprene/1, 3-butadiene copolymers, styrene/1, 3-butadiene/acrylonitrile copolymers and mixtures thereof. Advantageously, said at least one functionalized elastomeric polymer (b) is obtained from a styrene/1, 3-butadiene copolymer.
Useful examples of functionalized diene elastomeric polymers are functionalized styrene butadiene copolymers Sprintan manufactured and distributed by Trinseo, PA, USA TM SLR 3402 and Sprintan TM SLR 4602。
Non-functionalized white reinforcing filler (b)
The non-functionalized white reinforcing filler (b) may be any conventional white reinforcing filler.
The non-functionalized white reinforcing filler is preferably selected from conventional silica and silicates in the form of fibers, flakes or particles, such as bentonite, nontronite, beidellite, volkonskoite, hectorite, saponite, sauconite, vermiculite, sericite, sepiolite, palygorskite (also known as attapulgite), montmorillonite, halloysite, and the like, which may be modified and/or derivatized by acid treatment, and mixtures thereof, more preferably, which is silica. Examples of silica are fumed silica, precipitated amorphous silica, wet silica (hydrated silicic acid) or mixtures thereof.
Preferably, the non-functionalized white reinforcing filler (b) has a specific surface area (BET) of at least 30m 2 /g, more preferably at least 50m 2 /g, even more preferably at least 80m 2 /g。
Preferably, the non-functionalized white reinforcing filler (b) has a specific surface area (BET) of less than 400m 2 /g, more preferably less than or equal to 250m 2 /g, even more preferably less than or equal to 220m 2 /g。
Advantageously, the non-functionalized white reinforcing filler (b) has a specific surface area (BET) of about 50m 2 /g to about 350m 2 /g, more preferably about 70m 2 /g to about 240m 2 /g, even more preferably about 90m 2 /g to about 190m 2 /g。
The elastomeric composition according to the invention comprises said non-functionalized white reinforcing filler (b) in an amount of from 10phr to 90phr, preferably from 30phr to 70 phr.
Examples of suitable commercial silicas are PPG Industries Chemicals BV (Pittsburgh, pa.) under the trade name Hi-roomEvonik is under the trade name->Or Rhodia under the trade name->Products are sold, for example, as precipitated silica Rhodia Zeosil MP1165 (BET surface area 160m 2 /g)、7000 (BET specific surface area 160m 2 /g) and Zeosil 1115MP (BET specific surface area 95-120m 2 /g)。
Coupling agent
The white reinforcing filler is incorporated into the elastomeric composition along with a coupling or compatibilizer that is capable of interacting with the silica and bonding it to the elastomeric polymer during vulcanization. Coupling agents which are preferably used are those based on silanes, in particular aminosilanes and mercaptosilanes.
Preferred aminosilanes are represented by the following formula (I):
(R) 3 Si-C n H 2n -[X-C m H 2m ] p -Y (I)
wherein the method comprises the steps of
R groups are identical or different from each other and are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, provided that at least one R group is an alkoxy group;
n and m, equal to or different from each other, are integers from 1 to 6, inclusive;
p is an integer from 0 to 5, inclusive;
x is an-NH-group, and
y is-NH 2 Or a NHR 'group where R' is an alkyl or cycloalkyl group of 1 to 6 carbon atoms. Preferred mercaptosilanes are represented by the following formula (I I):
(R) 3 Si-C n H 2n -X(I I)
wherein the method comprises the steps of
X is mercapto (-SH) or- (S) m C n H 2n -S i-(R) 3
R groups are identical or different from each other and are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, provided that at least one R group is an alkoxy group; and
n and m, equal to or different from each other, are integers from 1 to 6, inclusive.
Aminosilanes of the formula (I) which can be used according to the invention are 2-aminoethyl-trimethoxysilane, 2-aminoethyl-triethoxysilane, 2-aminoethyl-tripropoxysilane, 2-aminoethyl-tributoxysilane, 3-aminopropyl-trimethoxysilane, 3-aminopropyl-triethoxysilane (APTES), 3-aminopropyl-methyldiethoxysilane, 3-aminopropyl-methyldimethoxysilane, 3-aminopropyl-diisopropylethoxysilane, 3-aminopropyl tris- (methoxyethoxyethoxy) silane, 3-aminopropyl-diisopropylethoxysilane, 3- (2-aminomethylamino) propyl-triethoxysilane, 3- (2- (2-aminoethylamino) ethylamino) propyl-trimethoxysilane, 4-aminobutyl-triethoxysilane, 4-aminobutyl dimethoxy-methoxysilane, 4-aminobutyl-triethoxysilane, N- (2-aminoethyl) aminomethyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane (also known as N- [3- (trimethoxysilyl) propyl ] Ethylenediamine (EDTMS) ] N- (2-aminoethyl) -3-aminopropyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyl-tris (2-ethylethoxy) silane, N- (2-aminoethyl) -3-aminopropyl-methyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-methyldiethoxysilane, N- (2-aminoethyl) -3-aminoisobutyl-methyldimethoxysilane, N- (6-aminohexyl) -3-aminopropyl-trimethoxysilane, N- (6-aminohexyl) -3-aminopropyl-triethoxysilane, N-2- (vinylbenzylamino) -ethyl-3-aminopropyl-trimethoxysilane, N-cyclohexyl (aminomethyl) methyldiethoxysilane, N-cyclohexyl (aminomethyl) triethoxysilane, N-cyclohexyl (aminomethyl) trimethoxysilane, N-cyclohexyl-3-aminopropyl-trimethoxysilane, N- (N-butyl) -3-aminopropyl-triethoxysilane, N- (N-butyl) -aminomethyl-triethoxysilane, N, N-diethylaminopropyl-trimethoxysilane, N-dimethylaminopropyl-trimethoxysilane, N-diethylaminomethyl-triethoxysilane.
The mercaptosilane represented by formula (I) useful in the present invention is bis [3- (trimethoxysilyl) propyl ] -tetrasulfane (TESPT), bis [3- (triethoxysilyl) propyl ] -disulfane (TESPD), bis [2- (trimethoxysilyl) ethyl ] -tetrasulfane, bis [2- (triethoxysilyl) ethyl ] -trisulfane, bis [3- (trimethoxysilyl) propyl ] -disulfane, (1-mercaptomethyl) triethoxysilane, (2-mercaptoethyl) triethoxysilane, (3-mercaptopropyl) methyldiethoxysilane, (3-mercaptopropyl) methyldimethoxysilane, (3-mercaptopropyl) trimethoxysilane, 3-octanoylthio-1-propyltriethoxysilane and (2-mercaptoethyl) tripropoxysilane.
Preferred compounds represented by formulas (I) and (II) are (I) aminosilanes selected from the group consisting of (3-aminopropyl) triethoxysilane (APTES), (3-aminopropyl) trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane [ also known as N- [3- (trimethoxysilyl) propyl ] Ethylenediamine (EDTMS) ] and N- (2-aminoethyl) -3-aminopropyl triethoxysilane, and (II) mercaptosilanes selected from the group consisting of bis [3- (trimethoxysilyl) propyl ] -tetrasulfane (TESPT), bis [3- (triethoxysilyl) propyl ] -disulfane (TESPD) and (3-mercaptopropyl) trimethoxysilane.
Functionalized silica (c)
The functionalized silica (c) may advantageously comprise a silanized silica.
The silanized silica useful for the purposes of the present invention comprises a sulfur content equal to or greater than 0.1%, preferably equal to or greater than 0.25%. The sulfur content of the silylated silica is preferably from 0.5 to 4.0%, more preferably from 0.45 to 2.0%, inclusive.
The silanized silica useful for the purposes of the present invention comprises a carbon content equal to or greater than 0.5%, preferably equal to or greater than 1.0%. The carbon content of the silanized silica is preferably from 1.0 to 10.0%, more preferably from 2.0 to 8.0%, inclusive.
The pH of the silanized silica useful for the purposes of the present invention is from 5 to 8, preferably from 6 to 7.5.
The carbon and sulfur content in the silylated silica was determined by elemental analysis using elemental analyzer Macro Cube Analyzer manufactured by Elementar. The process comprises converting species C and S to CO by high temperature combustion (typically above 1000 ℃ C.) 2 And SO 2 Adsorption and desorption from the purge and trap column, followed by measurement with a thermal conductivity detector. The pH was measured according to ISO 787-9 method.
Preferably, the specific surface area (BET) of the silanized silica is at least 30m 2 /g, more preferably at least 40m 2 /g, even more preferably at least 60m 2 /g。
Preferably, the specific surface area (BET) of the silanized silica is less than 300m 2 /g, more preferably less than or equal to 240m 2 /g, even more preferably less than or equal to 200m 2 /g。
Advantageously, the specific surface area (BET) of the silanized silica is about 60m 2 /g to about 260m 2 /g, more preferably about 80m 2 /g to about 220m 2 /g, even more preferably about 90m 2 /g to about 180m 2 /g。
The silanized silica useful for the purposes of the present invention is a silica prepared by reacting a silica (e.g., fumed silica, precipitated amorphous silica, wet silica (hydrated silicic acid), anhydrous silica (anhydrous silicic acid), or mixtures thereof) or a metal silicate (e.g., aluminum silicate, sodium silicate, potassium silicate, lithium silicate, or mixtures thereof) with at least one silanizing agent.
In general, the silanized silica is more hydrophobic than the starting non-silanized silica.
Preferably, the silanized silica is prepared in the presence of a surfactant.
Silylating agents, surfactants and silylated silicas suitable for the purposes of the present invention are described, for example, in patents US6184408, US7687107, US7569107, US9688784, US8846806 and US2016326374, which are incorporated herein by reference.
The elastomeric composition according to the invention comprises said silanized silica in an amount of from 5phr to 40phr, preferably from 10phr to 30 phr.
A commercial example of a silanized silica useful for the purposes of the present invention is Agi lon 400 silica from PPG Indus tr ies Chemicals BV (Pittsburgh, pa.).
For some applications, the vulcanizable elastomeric composition may include at least 1phr, more preferably at least 2phr, and more preferably at least 3 or 4phr of carbon black.
The carbon black may be selected from those of standard grades for tires, or have a surface area of not less than 20m 2 /g, more preferably greater than 50m 2 /g (measured according to ASTM D6556-16 standard).
Commercial examples of carbon black are N375 or N234 sold by Birla Group (india) or Cabot Corporation.
Vulcanizing bag
The vulcanizing agent (F) is preferably selected from sulfur, or sulfur-containing molecules (sulfur donors), such as caprolactam disulfide (CLD), bis (trialkoxysilyl) propyl ] polysulfide, dithiophosphate, phosphoryl polysulfide (SDT), and mixtures thereof.
Preferably, the vulcanizing agent is sulfur, which is preferably selected from the group consisting of soluble sulfur (crystalline sulfur), insoluble sulfur (polymeric sulfur), (iii) oil dispersed sulfur, and mixtures thereof.
Commercial examples of suitable sulfiding agents are 65% Sulfur known under the trade name Rhenogran (Lanxess), 67% Sulfur known under the trade name Crystex OT33 (Eastman), 95% Sulfur known under the trade name Solvay SchwefelkC, diamond-shaped crystalline Sulfur known under the trade name Sulfur (1% oil and 0.3% silica) (Zolfinducria).
The vulcanizing agents may be present in the vulcanizable elastomeric composition in a total amount of generally from 0.1 to 15phr, preferably from 0.5 to 10phr, even more preferably from 1 to 7 phr.
The vulcanizable elastomeric composition may comprise a mixture of one or more vulcanizing agents as defined above.
The vulcanizing agent is preferably used together with auxiliary agents known to those skilled in the art, such as vulcanization activators, accelerators and/or retarders. The group of vulcanization activators, accelerators and/or retarders together with the vulcanizing agent constitute a so-called "vulcanization package".
Particularly effective vulcanization activators are zinc compounds, in particular ZnO, znCO 3 Zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, such as zinc stearate, which are preferably formed in situ in the elastomeric composition from ZnO and fatty acids, and BiO, pbO, pb 3 O 4 、PbO 2 Or a mixture thereof. Commercial examples are the dispersant FS-200 fatty acid zinc salt of Wuhan Jinghe, palmera B1810 stearic acid of Klk Oleo, or U.S. Zinc grade 203 Zinc oxide.
The vulcanization accelerator is preferably selected from the group consisting of dithiocarbamates, guanidine, thiourea, thiazole, sulfenamides, thiurams, amines, xanthates and mixtures thereof.
Preferably, the accelerator is selected from the group consisting of N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and mixtures thereof.
A commercial example of a suitable accelerator is N-cyclohexyl-2-benzothiazole-sulfenamide sold by Lanxess(CBS)。
The vulcanization accelerators may be present in the vulcanizable elastomeric composition in a total amount generally ranging from 0.05phr to 10phr, preferably from 0.1phr to 5 phr.
The vulcanizable elastomeric composition may comprise a mixture of one or more vulcanization accelerators as defined above.
The vulcanization retarder may be selected from, for example, urea, phthalic anhydride, N-nitrosodiphenylamine, N-Cyclohexylthiophthalimide (CTP), and mixtures thereof.
A commercial example of a suitable retarder is Lanxess' N-cyclohexylthio-phthalimide Vulkalant G.
The retarder may be present in the vulcanizable elastomeric composition in an amount typically ranging from 0.05phr to 2 phr.
The vulcanizable elastomeric composition may comprise a mixture of one or more vulcanization retarders as defined above.
Other additives
The vulcanizable elastomeric composition may include other commonly used additives selected based on the particular application for which the elastomeric composition is designed, such as antioxidants, anti-aging agents, plasticizers, adhesives, antiozonants (particularly p-phenylenediamine), waxes, modified resins, fibers (e.g Pulp) or mixtures thereof.
The antioxidant may be selected from the group consisting of phenylenediamine, diphenylamine, dihydroquinoline, phenol, benzimidazole, hydroquinone and derivatives thereof, optionally as a mixture.
The antioxidant is preferably selected from the group consisting of N-isopropyl-N '-phenyl-p-phenylenediamine (IPPD), N- (1, 3-dimethyl-butyl) -N' -phenyl-p-phenylenediamine (6 PPD), N '-bis- (1, 4-dimethyl-pentyl) -p-phenylenediamine (77 PD), N' -bis- (1-ethyl-3-methyl-pentyl) -p-phenylenediamine (DOPD), N '-bis- (1, 4-dimethyl-pentyl) -p-phenylenediamine, N' -diphenyl-p-phenylenediamine (DPPD), N, N '-xylyl-p-phenylenediamine (DTPD), N' -di-beta-naphthyl-p-phenylenediamine (DNPD), N '-bis (1-methylheptyl) -p-phenylenediamine, N' -di-sec-butyl-p-phenylenediamine (44 PD), N-phenyl-N-cyclohexyl-p-phenylenediamine, N-phenyl-N '-1-methylheptyl-p-phenylenediamine, and the like, and mixtures thereof, preferably N- (1, 3-dimethyl-butyl) -N' -phenyl-p-phenylenediamine (6-PPD).
Commercial examples of suitable antioxidants are Solut ia/Eas tman 6PPD and Lanxes sTMQ 2, 4-trimethyl-1, 2-dihydroquinoline-HS/LG。
Antioxidants may be present in the vulcanizable elastomeric composition in a total amount generally ranging from 0phr to 20phr, preferably from 0.5phr to 10 phr.
The wax may be, for example, a petroleum wax or a mixture of paraffin waxes.
Commercial examples of suitable waxes are N-paraffin mixtures of Repsol and Rhein Chemie654 microcrystalline wax and RIOWAX BM-01 wax of Ser SpA.
The wax may be present in the vulcanizable elastomeric composition in a total amount generally ranging from 0phr to 20phr, preferably from 0.5phr to 5 phr.
To further improve processability, the vulcanizable elastomeric composition may be mixed with at least one plasticizer, typically selected from mineral oils, vegetable oils, synthetic oils, polymers having low molecular weight and mixtures thereof, such as aromatic oils, naphthenic oils, phthalates, soybean oil and mixtures thereof. A commercial example of a plasticizer is Nynas4700 naphthenic oil.
The amount of plasticizer is generally from 0phr to 70phr, preferably from 5phr to 30phr.
The vulcanizable elastomer composition described above is prepared according to the preparation method of the present invention, which comprises:
a mixing step (i) in which at least one elastomeric polymer is mixed with one or more additives other than a vulcanizing agent to form a non-vulcanizable elastomeric composition,
a mixing step (i i) in which the unvulcanizable elastomer composition obtained in the mixing step (i) is mixed with a vulcanizing agent,
Characterized in that the mixing step (i) comprises:
-a first mixing step (ia) in which the at least one elastomeric polymer is mixed with a non-functionalized white reinforcing filler and a coupling agent to form a first elastomeric composition, and
-a second mixing step (ib) wherein the first elastomeric composition is mixed with a functionalized silica to form the non-vulcanizable elastomeric composition.
The term "mixing step (i)" or "non-productive step" refers to a step of the process for preparing a vulcanizable elastomeric composition in which one or more additives, in addition to the vulcanizing agent fed in the mixing step (i i), can be introduced by mixing and possibly heating.
The term "mixing step (i i)" or "productive step" means the next step in the process of preparing the vulcanizable elastomeric composition in which the vulcanizing agent and possibly other additives of the vulcanization package are introduced into the elastomeric composition obtained from mixing step (i) and incorporated by mixing at a controlled temperature below the vulcanization temperature, typically at a temperature below 120 ℃, to provide the vulcanizable elastomeric composition.
Can be used, for example, with a cylindrical mixer or with a tangential rotor ) Or has interpenetrating rotors) Internal mixers of the type (A), or in Ko-Kneader TM (i.e.)>) Or mixing step (i) and [ ] in a co-rotating or counter-rotating twin screw continuous mixeri i)。
In the first mixing step (ia), the one or more elastomeric polymers, the one or more non-functionalized white reinforcing fillers and the one or more coupling agents are charged into a mixer and mixed at a temperature preferably comprised between 100 and 150 ℃, the rotation speed of the mixer preferably being comprised between 10 and 60 revolutions per minute, for a time preferably comprised between 4 and 8 minutes.
In the second mixing step (ib), the functionalized silica or silicas are added to a mixer and mixed at a temperature preferably ranging from 100 ℃ to 150 ℃, the rotation speed of the mixer preferably ranging from 10 to 60 revolutions per minute, for a time preferably ranging from 2 to 6 minutes.
Preferably, the above-mentioned other additives, such as antioxidants, anti-aging agents, plasticizers, binders, antiozonants (in particular p-phenylenediamine), waxes, modified resins, fibers (for examplePaste) or mixtures thereof. The order of addition of the other additives is not particularly limited, and they may be added during step (ia), during step (ib) or in part in step (ia) and in part in step (ib). Similarly, each additive may be added in step (ia), in step (ib) or partly in step (ia) and partly in step (ib). As non-limiting examples, it is preferred to add plasticizers, waxes, resins in step (ia), while antioxidants, anti-aging agents and antiozonants are preferably added during step (ib). Typically, in step (i) also vulcanization activators are added, which will perform their function later in the mixing step (i i) of the added vulcanizing agent.
In the mixing step (i i), a cure package consisting of one or more curing agents and one or more curing accelerators and/or retarders as described above is added to the mixer. The mixing step (i i) is carried out at a temperature below the vulcanization temperature, typically at a temperature below 100 ℃, wherein the rotational speed of the mixer is preferably between 30 and 60 revolutions per minute, for a time preferably between 1 and 2 minutes.
Thereafter, the vulcanizable elastomeric composition is incorporated into one or more structural elements of the tire and vulcanized in accordance with known techniques.
Another aspect of the invention is represented by a structural element of a tyre for vehicle wheels comprising or preferably consisting of an elastomeric composition according to the invention, preferably selected from crown, underlayer and sidewall inserts.
The tire structural element may comprise or preferably may consist of the non-vulcanized elastomeric composition according to the invention (green structural element) or the vulcanized elastomeric composition according to the invention.
Another aspect of the invention is a tyre for vehicle wheels comprising at least one structural element of the tyre according to the invention.
The tyre for vehicle wheels according to the invention may comprise at least one tyre structural element consisting of an unvulcanized elastomeric composition according to the invention (green tyre) or of a vulcanized elastomeric composition according to the invention (vulcanized tyre).
In a preferred embodiment, a tire for a vehicle according to the present invention comprises at least:
a carcass structure having opposite side edges associated with respective bead structures;
a pair of sidewalls, each possibly comprising a sidewall insert applied to a side surface of the carcass structure in an axially external position, respectively;
optionally, a belt structure applied in a radially external position with respect to said carcass structure;
a crown applied in a radially external position with respect to said carcass structure or said belt structure, if present,
optionally, a layer of elastomeric material, also called underlayer,
wherein at least one structural element, preferably the crown and/or sidewall insert, comprises or preferably consists of the elastomeric composition according to the invention.
In one embodiment, the tire according to the present invention is a tire for an automobile.
In one embodiment, the tire according to the invention is a tire for a motorcycle, wherein at least one structural element comprises or preferably consists of the elastomeric composition according to the invention.
In a preferred embodiment, the tyre according to the invention is a tyre for motorcycle wheels, preferably for sport or racing motorcycles.
The tire according to the invention may be a tire for two-, three-or four-wheeled vehicles.
The tire according to the invention can be used in summer or winter or for all seasons.
In one embodiment, the tire according to the present invention is a tire for a bicycle wheel.
A tyre for bicycle wheels generally comprises a carcass structure turned around a pair of bead cores at the beads and a crown arranged in a radially external position with respect to the carcass structure. Preferably, at least the crown and/or the rubber layer comprises an elastomeric composition according to the invention.
The tyre according to the invention may be manufactured according to a method comprising the steps of:
-forming one or more structural elements of the green tyre on at least one forming drum;
-shaping, moulding and vulcanising the tyre;
wherein forming one or more green tire structural elements comprises:
-manufacturing at least one green structural element comprising the vulcanizable elastomeric composition of the invention.
Drawings
The description is given hereinafter with reference to the accompanying drawings, which are provided for illustrative and therefore non-limiting purposes only, wherein:
figure 1 shows a half-cross section of a tyre for motor vehicle wheels according to a first embodiment of the present invention,
Figure 2 shows the reference elastomer composition R prepared as described in example 2, respectively 2 And the present inventionMing I 3 At the end of step 1a of (c), a photograph of the extruded rubber sheet,
FIG. 3 shows comparative elastomer compositions R prepared as described in example 2, respectively 2 And the invention I 3 At the end of step 1b of (a), a photograph of the extruded rubber sheet.
The present description relates by way of example to a tyre for motor vehicle wheels. The applicant believes that the invention may also be applied to tires for different vehicles such as heavy vehicles, motorcycles, bicycles and the like.
In fig. 1, "a" represents an axial direction, and "x" represents a radial direction. For simplicity, fig. 1 shows only a portion of the tyre, the remaining portion not shown being identical and symmetrically arranged with respect to the radial direction "x".
With reference to fig. 1, a tyre 100 for vehicle wheels comprises at least one carcass structure of elastomeric material, comprising at least one carcass layer 101, said carcass layer 101 having respective opposite end flaps engaged with respective annular anchoring structures 102, known as bead cores, possibly associated with a bead filler 104 of elastomeric material. The tyre region comprising the bead cores 102 and the bead filler 104 forms a reinforced annular structure 103, the so-called bead, which is used to anchor the tyre to a respective mounting rim (not shown).
The carcass structure is generally of the radial type, i.e. the reinforcing elements of at least one carcass layer 101 lie in planes comprising the rotation axis of the tyre and substantially perpendicular to the equatorial plane of the tyre. The reinforcing elements are generally composed of textile cords, for example rayon, nylon, polyester (for example polyethylene naphthalate, PEN). Each reinforcing annular structure is associated with the carcass structure by folding back opposite lateral edges of at least one carcass layer 101 around an annular anchoring structure 102, so as to form a so-called carcass flap 101a as shown in fig. 1.
In one embodiment, the coupling between the carcass structure and the reinforcing annular structure may be provided by a second carcass layer (not shown in fig. 1) applied in an axially external position with respect to the first carcass layer.
A wear strip 105 of elastomeric material is disposed at an outer location of each reinforcing annular structure 103. Preferably, each wear strip 105 is disposed at least at an axially outer location of the reinforcing annular structure 103, extending at least between the sidewall 108 and a radially lower portion of the reinforcing annular structure 103.
Preferably, the wear strips 105 are arranged to surround the reinforcing annular structure 103 along axially inner and outer and radially lower regions of the reinforcing annular structure 103 so as to be interposed between the reinforcing annular structure 103 and the rim when the tyre 100 is mounted to the rim.
Associated with the carcass structure 106 of elastomeric material is a belt structure 106, said belt structure 106 comprising one or more belt layers 106a, 106b, said one or more belt layers 106a, 106b being radially superposed with respect to each other and with respect to the carcass layer, typically with metallic reinforcing cords. Such reinforcing cords may have a cross orientation with respect to the circumferential extension direction of the tire 100. The "circumferential" direction refers to a direction that generally faces the direction of rotation of the tire.
At least one zero degree reinforcing layer 106c, commonly referred to as a "0 ° band", may be applied to the belt layers 106a, 106b at a radially outermost position, typically comprising a plurality of reinforcing cords, typically textile cords, oriented in a substantially circumferential direction so as to form an angle of a few degrees (e.g., an angle of about 0 ° to 6 °) with respect to the equatorial plane of the tire, and coated with an elastomeric material.
A crown 109 of elastomeric material is applied in a radially external position to the belt structure 106.
Furthermore, respective sidewalls 108 of elastomeric material are further applied in axially external positions on the side surfaces of the carcass structure, each sidewall 108 extending from one of the side edges of the tread 109 at a respective reinforcing annular structure 103.
In a radially external position, the crown 109 has a rolling surface 109a intended to be in contact with the ground. Circumferential grooves connected by transverse notches (not shown in fig. 1) to define a plurality of blocks of various shapes and sizes distributed over the rolling surface 109a are generally formed on this surface 109a, which is represented in fig. 1 as smooth for simplicity.
An underlayer 111 of elastomeric material is arranged between the belt structure 106 and the crown 109.
A strip 110 of elastomeric material (commonly referred to as "micro-sidewalls") may optionally be provided in the connection zone between the sidewalls 108 and the crown 109, the micro-sidewalls being generally obtained by coextrusion with the crown 109 and allowing to improve the mechanical interaction between the crown 109 and the sidewalls 108. Preferably, the ends of the sidewalls 108 directly cover the lateral edges of the crown 109.
In the case of tubeless tyres, a layer 112 of elastomeric material, commonly referred to as "liner", can also be provided in a radially internal position with respect to the carcass layer 101, which provides the necessary impermeability to the inflation air of the tyre.
Sidewall inserts (not shown) may extend radially between the lateral edges of the crown 109 and the bead structures 103, for example between the carcass layer 101 and the liner 112, in an axially inner or outer position with respect to the carcass layer 101.
The rigidity of the tire sidewall 108 may be improved by providing the bead structure 103 with a reinforcing layer 120 commonly referred to as an "outer flipper" or additional strip insert. The outer retainer wrap 120 generally includes a plurality of textile cords incorporated within an elastomeric material layer.
The outer flipper 120 is a reinforcing layer wound around the respective bead core 102 and bead filler 104 so as to at least partially surround them, said reinforcing layer being arranged between at least one carcass layer 101 and bead structure 103. Typically, an outer flipper is in contact with the at least one carcass layer 101 and the bead structure 103.
The bead structure 103 of the tire may comprise a further protective layer, commonly referred to as the term "chafer" 121 or protective strip, and having the function of increasing the rigidity and integrity of the bead structure 103.
Chafer 121 typically includes a plurality of cords incorporated within an elastomeric material layer. Such cords are generally made of textile material (for example aramid or rayon) or metallic material (for example steel cords).
The elastomeric composition according to the invention can advantageously be used to manufacture elastomeric materials incorporated in one or more structural elements of a tyre selected from the group consisting of crown, tread underlayer, sidewall inserts, and generally any structural element in which silica is used as reinforcing element, preferably elastomeric materials incorporated in the tread, even when two radially superposed layers (called "cap and base" tread) are made, having radially external portions ("caps") and radially internal portions ("bases") containing different amounts of silica.
The use of the elastomeric composition according to the invention to manufacture the elastomeric material of the structural element described above allows to obtain a tyre with lower rolling resistance and therefore lower development of heat and fuel consumption, while obtaining good mechanical resistance of the tyre surface and good operability during its use.
The building of the tyre 100 as described above can be carried out by assembling the respective semifinished products onto a forming drum (not shown) by at least one assembling device.
At least a portion of the structural elements for forming the carcass structure of the tire may be built and/or assembled on a forming drum. More specifically, the forming drum is intended to receive the possible liner first, then the carcass structure and the wear strips. Thereafter, a device, not shown, coaxially engages one of the annular anchoring structures surrounding each end flap, positions the outer sleeve comprising the belt structure and the crown in a coaxially centred position around the cylindrical carcass sleeve, and shapes the carcass sleeve according to a substantially annular conformation by radial expansion of the carcass structure so as to apply it against the radially inner surface of the outer sleeve.
After construction of the green tyre, a moulding and vulcanisation treatment is generally carried out in order to determine the structural stability of the tyre by cross-linking the elastomeric composition, as well as to impart the desired tread pattern on the crown and any distinctive graphic symbols on the sidewalls.
According to an embodiment not shown, the tyre may be a tyre for heavy transportation vehicle wheels, such as trucks, buses, trailers, vans, and is generally used for vehicles where the tyre is subjected to high loads. Preferably, such a tire is adapted to be mounted on a rim having a diameter equal to or greater than 17.5 inches for a directional wheel or trailer wheel.
According to an embodiment not shown, the tyre may be a tyre for motorcycle wheels, which is generally a tyre having a straight portion characterized by a high tread camber.
According to an embodiment not shown, the tyre may be a tyre for bicycle wheels.
The following description of some preparation examples and comparative examples according to the present invention is given for the purpose of illustrating and not limiting the scope of the present invention.
Experimental part
Analysis method
MDR rheology analysis(according to ISO 6502): a model Alpha Technologies MDR2000 rheometer was used. At 170 ℃, oscillation frequency of 1.66Hz (100 oscillations/min), oscillation amplitude of ± 0.5 °, a 20 minute test was performed, measuring the minimum torque value (ML), the maximum torque (MH), the time required to increase the torque by two units (TS 2) and the time required to reach different percentages (30%, 60% and 90%) of the maximum torque value (MH).
Properties of the vulcanized Material
The elastomeric material prepared in the previous examples was vulcanized to give samples, which were subjected to analytical characterization and evaluation of dynamic mechanical properties. Unless otherwise indicated, in the mold, vulcanization is carried out in a hydraulic press at 170 ℃ and at a pressure higher than 3.5MPa for about 10 minutes.
IRHD hardnessAccording to ISO 48:2007 standard, measured on crosslinked elastomeric compositions at 23 ℃.
Static modulus: according to ISO 37:2011, static mechanical properties were measured at 23 ℃. In particular, tensile stress, load, elongation and energy to break (CR, AR and respectively) at various elongation levels (100% and 300%, denominated in the sequences CA1 and CA 3) were measured on annular samples of the vulcanized elastomer compositionER)。
Dynamic modulus: dynamic mechanical properties were measured in compression and extension operations using an Instron dynamic device in the following manner. A sample of the vulcanized elastomeric cylindrical composition (height=25 mm; diameter=18 mm) was preloaded under compression to 25% longitudinal deformation relative to the initial length and maintained at a predetermined temperature (10 ℃, 23 ℃ or 70 ℃) during testing, subjected to a dynamic sinusoidal voltage with an amplitude of ±3.5% relative to the preloaded length at a frequency of 10 Hz.
Dynamic mechanical properties are expressed in terms of dynamic elastic modulus (E') and Tan delta (loss factor). The Tan delta value is calculated as the ratio between the viscous dynamic modulus (E ") and the dynamic elastic modulus (E').
Example 1
The elastomeric materials listed in table 1 below (amounts of the various components expressed in phr) were prepared as follows.
In step (1 a), the elastomer component, the white reinforcing filler and the silane are mixed in an internal mixer (model Pomini PL 1, 6) for about 6 minutes up to about 135 ℃. In step (1 b), the zinc-based component and other additives are added and mixing is continued for about 4 minutes up to about 135 ℃. Finally, in step (2), sulfur and accelerator (TBBS) are added, mixed for a further 2 minutes up to about 95℃and the elastomeric composition is then discharged.
TABLE 1
(1) SIR20 of ANEKA BUMI PRATAMA, SED
(2) Functionalized styrene butadiene copolymer-microstructure with 21% styrene and 62.5% vinyl groups on butadiene fraction-sprint an TM SLR 4602-Trinseo
(3) Tris (2-ethylhexyl phosphate) higher-HANGZHOU QIANYANG TECHNOLOGY
(4)7000 (BET specific surface area 160m 2 /g)-Evonik
(5) Agilon 400 of PPG Industries Chemicals BV (Pittsburgh, pa.)
(6) JINGZHOU JIANGHAN FINE bis [3- (triethoxysilyl) propyl ] -disulfane (TESPD) JH-S69 of CHEM
(7) Wuhan Jinghe dispersant FS-200 fatty acid salt
(8) Zinc grade 203 zinc oxide
(9) RIOWAX BM-01 of Ser SpA
(10)IMPERA P1504-EASTMAN
(11) Palmera B1810 stearic acid of KLK OLEO
(12) Carbon black grade ASTM N234-BIRLA
(13) Lanxess TMQ 2, 4-trimethyl-1, 2-dihydroquinoline-HS/LG
(14) Antioxidant 6PPD of SENNICS CO
(15) N-cyclohexyl-2-benzothiazolyl-sulfenamides(CBS)-Lanxess。
(16) Sulphur of Zolfinduria (1% oil and 0.3% silica)
The elastomeric compositions prepared as above were evaluated for their behaviour in vulcanization (170 ℃ C., 10 minutes) according to the method described above, followed by an evaluation of their behaviour in terms of static and dynamic mechanical properties. Table 2 below shows the rheological, mechanical, dynamic and static characteristics of the compositions of table 1.
All values relative to reference R 1 Normalized to 100.
TABLE 2
Elastomer composition C 1 Relative to a reference composition R 1 Showing a significant decrease in the break energy, indicating poor tear resistance and too fast cure kinetics.
Furthermore, elastomer composition C compared with an improvement in Tan delta value at 10℃which predicts good behaviour in humid environments 1 Shows a significant decrease in E' at 23℃and an increase in Tan delta at 70℃which predicts a greater rolling resistance.
Elastomer composition I of the invention 1 And I 2 Showing and referencing R 1 Consistent values, with an improvement in Tan delta value at 10 ℃, thus predicting good behavior in wet state, with the same Tan delta value at 70 ℃ and E' at 23 ℃.
Example 2
The elastomeric materials listed in Table 3 below (amounts of the various components expressed in phr) were prepared as follows.
Regarding the compound R 2 The elastomer component, silane, white reinforcing filler (represented by non-functionalized silica and functionalized silica) and other additives were mixed in step (1 a) in an internal mixer with an interpenetrating rotor (intermeix model VIC 275X) for about 6 minutes up to about 135 ℃. In step (1 b), the zinc-based component and other protectant are added and mixing is continued for about 4 minutes up to about 125 ℃.
In size I 3 In the preparation of (2), only non-functionalized silica is added in step (1 a), whereas functionalized silica is added in step (1 b).
The resulting elastomer composition was discharged into an internal tangential rotor mixer (banbury type) to perform step (2), wherein sulfur and accelerator (TBBS) were added and mixed for 2 minutes up to about 95 ℃. After completion, the elastomer composition is discharged.
TABLE 3 Table 3
(1) SIR20 of ANEKA BUMI PRATAMA, SED
(2) Functionalized styrene butadiene copolymer-microstructure with 21% styrene and 62.5% vinyl groups on butadiene fraction-sprint an TM SLR 4602-Trinseo
(3) Tris (2-ethylhexyl phosphate) higher-HANGZHOU QIANYANG TECHNOLOGY
(4)7000 (BET specific surface area 160m 2 /g)-Evonik
(5) Agilon 400 of PPG Industries Chemicals BV (Pittsburgh, pa.)
(6) JINGZHOU JIANGHAN FINE bis [3- (triethoxysilyl) propyl ] -disulfane (TESPD) JH-S69 of CHEM
(7) Wuhan Jinghe dispersant FS-200 fatty acid salt
(8) Zinc grade 203 zinc oxide
(9) RIOWAX BM-01 of Ser SpA
(10)IMPERA P1504-EASTMAN
(11) Palmera B1810 stearic acid of KLK OLEO
(12) Carbon black grade ASTM N234-BIRLA
(13) Lanxess TMQ 2, 4-trimethyl-1, 2-dihydroquinoline-HS/LG
(14) Antioxidant 6PPD of SENNICS Co
(15) N-cyclohexyl-2-benzothiazolyl-sulfenamides(CBS)-Lanxess。
(16) Sulphur of Zolfinduria (1% oil and 0.3% silica)
The elastomeric compositions prepared as above were evaluated for their behaviour in vulcanization (170 ℃ C., 10 minutes) according to the method described above, followed by an evaluation of their behaviour in terms of static and dynamic mechanical properties. Table 4 below shows the rheological, mechanical, dynamic and static characteristics of the compositions of table 3.
Relative to each otherAt reference R 2 Values were normalized to 100.
TABLE 4 Table 4
The images of FIG. 2 show the elastomer composition R respectively 2 And the invention I 3 Extruded rubber sheet at the end of step 1 a. Elastomer composition R 2 Clearly showing the torn areas and irregularities caused by the high level of reactivity caused by the simultaneous addition of reinforcing filler and coupling agent. On the other hand, the elastomer composition I of the present invention 3 Showing a smooth surface without cracks.
The images of FIG. 3 show the elastomer composition R respectively 2 And the invention I 3 Extruded rubber sheet at the end of step 1 b. The same considerations as described above apply to these compositions. Elastomer composition R 2 Shows tearing and irregularities, whereas the composition I of the present invention 3 Is smooth and crack-free.
Confirm improved processability, composition I 3 Showing a significant improvement in the processability index, particularly in step 1 a.
Processability was evaluated by measuring the stress relaxation rate (slope [ Mu/s ]) at the end of the viscosity test using a Mooney viscometer according to ISO 289-4 standard. The lower the absolute value of the speed, the worse the workability.
Composition I of the invention 3 Exhibit further significant improvements in cure kinetics and energy to break values consistent with the reference composition, thereby predicting R relative to the reference composition 2 Has excellent tear resistance, wherein Tan delta values at 10 ℃ and 70 ℃ and E' at 23 ℃ are compared with a reference composition R 2 And consistent.
Thus, the applicant has surprisingly observed that, in order to improve the elastomeric composition R 2 The improvement introduced in the preparation process, which is accompanied by the processability, makes it possible to further improve the properties of the resulting compounds.

Claims (20)

1. A method of preparing a vulcanizable elastomeric composition, the method comprising:
a mixing step (i) in which at least one elastomeric polymer is mixed with one or more additives other than a vulcanizing agent to form a non-vulcanizable elastomeric composition,
a mixing step (ii) in which the unvulcanizable elastomeric composition obtained in the mixing step (i) is mixed with a vulcanizing agent,
characterized in that the mixing step (i) comprises:
-a first mixing step (ia) in which the at least one elastomeric polymer is mixed with a non-functionalized white reinforcing filler and a coupling agent to form a first elastomeric composition, and
a second mixing step (ib) wherein the first elastomer composition is mixed with a functionalized silica to form the non-vulcanizable elastomer composition.
2. The method of claim 1, wherein the elastomeric polymer is selected from the group consisting of natural or synthetic cis-1, 4-polyisoprene, 3, 4-polyisoprene, polybutadiene, isoprene/isobutylene copolymers, 1, 3-butadiene/acrylonitrile copolymers, styrene/1, 3-butadiene copolymers, styrene/isoprene/1, 3-butadiene copolymers, styrene/1, 3-butadiene/acrylonitrile copolymers, and mixtures thereof.
3. The method of claim 1, wherein the elastomeric polymer is selected from the group consisting of natural or synthetic cis-1, 4-polyisoprene, polybutadiene, styrene/1, 3-butadiene copolymers, and mixtures thereof.
4. The method of claim 1, wherein the non-functionalized white reinforcing filler has a specific surface area (BET) of about 50m 2 /g to about 350m 2 /g, more preferably about 70m 2 /g to about 240m 2 /g, even more preferably about 90m 2 /g to about 190m 2 /g。
5. The method of claim 1, wherein the non-functionalized white reinforcing filler is selected from the group consisting of fumed silica, precipitated amorphous silica, wet silica (hydrated silicic acid), and mixtures thereof.
6. The method of claim 1, wherein the functionalized silica has a specific surface area (BET) of about 60m 2 /g to about 260m 2 /g, more preferably about 80m 2 /g to about 220m 2 /g, even more preferably about 90m 2 /g to about 180m 2 /g。
7. The method of claim 1, wherein the functionalized silica is selected from the group consisting of sulfur-silanized silica prepared by reacting silica, metal silicate, and mixtures thereof with at least one sulfur-silanizing reagent.
8. The method of claim 7, wherein the silica is selected from the group consisting of fumed silica, precipitated amorphous silica, wet silica (hydrated silicic acid), anhydrous silica (anhydrous silicic acid), and mixtures thereof.
9. The method of claim 7, wherein the metal silicate is selected from the group consisting of aluminum silicate, sodium silicate, potassium silicate, lithium silicate, and mixtures thereof.
10. The process of claim 7, wherein the sulfur-silanized silica comprises a sulfur content of from 0.5% to 4.0%, more preferably from 0.45% to 2.0%, inclusive.
11. The method of claim 7, wherein the sulfur-silanized silica comprises a carbon content of from 1.0% to 10.0%, more preferably from 2.0% to 8.0%, inclusive.
12. The process according to claim 7, wherein the sulphur silanized silica has a pH of from 5 to 8, preferably from 6 to 7.5.
13. The method of claim 1, wherein the coupling agent is selected from the group consisting of aminosilanes, sulfur silanes, and mixtures thereof.
14. A vulcanizable elastomeric composition comprising, per 100phr of elastomeric polymer:
(a) 100phr of at least one diene elastomeric polymer;
(b) From 10phr to 90phr, preferably from 30phr to 70phr, of at least one non-functionalized white reinforcing filler; and
(c) From 5phr to 40phr, preferably from 10phr to 30phr, of at least one functionalized silica.
15. The vulcanizable elastomeric composition according to claim 14, wherein the at least one diene elastomeric polymer is a diene elastomeric polymer as defined in any one of claims 2 and 3.
16. The vulcanizable elastomeric composition according to claim 14, wherein the at least one non-functionalized white reinforcing filler is a non-functionalized white reinforcing filler as defined in any one of claims 4 and 5.
17. The vulcanizable elastomeric composition according to claim 14, wherein the at least one functionalized silica is a functionalized silica as defined in any one of claims 6 to 12.
18. A structural element of a tyre for vehicle wheels comprising a vulcanizable elastomeric composition according to any one of claims 14 to 17.
19. Tyre for vehicle wheels comprising at least one structural element according to claim 18.
20. Tyre for vehicle wheels according to claim 19, wherein said tyre comprises:
a carcass structure having opposite side edges associated with respective bead structures;
a pair of sidewalls, each possibly comprising a sidewall insert applied to a side surface of the carcass structure in an axially external position, respectively;
optionally, a belt structure applied in a radially external position with respect to said carcass structure;
a crown applied in a radially external position with respect to said carcass structure or said belt structure, if present,
optionally, a layer of elastomeric material, also called underlayer,
wherein the at least one structural element is selected from the group consisting of a crown, a rubber covering of the at least one carcass layer, and a sidewall insert.
CN202180077940.9A 2020-11-27 2021-11-25 Process for preparing an elastomeric composition and tyre comprising same Pending CN116472306A (en)

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US6433065B1 (en) * 2000-10-13 2002-08-13 Bridgestone Corporation Silica-reinforced rubber compounded with mercaptosilanes and alkyl alkoxysilanes
DE10132943A1 (en) * 2001-07-06 2003-01-23 Degussa Silane-modified oxidic or silicate filler, process for its production and its use
DE10218350A1 (en) * 2002-04-25 2003-11-20 Degussa Silane-modified oxidic or silicate filler, process for its production and its use
US7285584B2 (en) * 2005-12-16 2007-10-23 The Goodyear Tire & Rubber Company Tire with component comprised of rubber composition containing hydrophobated, pre-silanized silica
US9550893B2 (en) * 2014-08-25 2017-01-24 The Goodyear Tire & Rubber Company Rubber prepared with pre-treated precipitated silica and tire with component
EP3350260B1 (en) * 2015-09-18 2020-07-08 Pirelli Tyre S.p.A. Winter tyres
IT201600108121A1 (en) * 2016-10-26 2018-04-26 Pirelli New reinforcing materials, elastomeric compositions and tires for vehicle wheels that include them
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