RU2800092C2 - Tire for vehicle wheels - Google Patents

Abstract

FIELD: tires.

SUBSTANCE: present invention relates to a tire comprising: a carcass structure including at least a carcass ply having opposing side edges associated with respective bead structures; a tread band applied in a radially outward position relative to the frame structure; a pair of sidewalls applied on the sides on opposite sides relative to the frame structure; and at least one painted decorative element having a thickness of 200 to 800 mcm and applied to at least one side of said pair of sidewalls. Moreover, said pair of sidewalls contains an elastomeric composition containing (i) at least one diene elastomeric polymer and (ii) an ozone protection system. Wherein said at least one decorative element is made of a cross-linked elastomeric composition containing: (i) 100 weight parts of an elastomeric polymer containing from 30 to 70 weight parts of natural and/or synthetic isoprene rubber and from 30 to 70 weight parts of rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber, styrene-butadiene rubber and mixtures thereof, (ii) from 5 to 120 weight parts of at least one reinforcing filler, (iii) optionally at least 0.5 weight parts of at least one colouring agent; and (iv) an optional non-staining ozone protection system. At the same time, said at least one decorative element is directly applied unvulcanised or partially vulcanized to said at least one sidewall of said pair of green tire sidewalls and subjected to co-vulcanization with the green tire. The invention also relates to a method for manufacturing the above tire.

EFFECT: ensuring good resistance to abrasion and impacts during tire use, as well as ensuring reduction of cracking and discoloration and/or discoloration of the sidewall.

23 cl, 4 dwg, 6 tbl, 4 ex

Description

Technical field

The present invention relates to a tire for vehicle wheels including at least one colored decorative element on at least one tire sidewall.

In particular, the present invention relates to a tire for vehicle wheels obtained by bringing a layer of a green or partially cured elastomeric composition into contact with the sidewall of a green tire and covulcanizing said layer with the green tyre.

State of the art

Tires for vehicle wheels incorporating one or more white or colored decorative elements arranged on the sidewall of the tire itself are known in the art. The sidewall of the tire may have isolated white or colored decorative elements (such as letters, numbers, stripes or logos) or may be completely covered with a white or variously colored layer.

Typically, such decorative elements can be made by coating one sidewall of a green tire with a layer of vulcanizable polymeric material containing colored or white pigments, and then covulcanizing during the manufacturing process of the finished tire.

Tires having a painted outer surface and made using this method of manufacture are described, for example, in US 5474645, US 2007/256771, US 2004/103974, US 2016/032151, EP 2522496 and EP 0249918, which describe a tire comprising a vulcanized rubber surface with a painted ny coating having an elastomeric base.

Alternatively, a colored outer surface is produced by applying paint or a layer of adhesive crosslinkable polymeric material containing colored or white pigments to one side of a vulcanized tire and subsequently activating the crosslinking. Tires having a painted outer surface made using this manufacturing method are described, for example, in US 5300164, US 6030676, US 6080465, US 8834974.

In some cases, such as GB 945978, EP 2522496 A2, EP 249918 A2, WO 2013/093896, US 5474645 and US 5591513, it has been proposed to use a barrier layer between the outer surface of the tire and the painted coating, this barrier layer generally containing halogenated rubbers such as poly chloroprene and chlorobutyl rubbers.

Alternatively, in accordance with the description of the inventions, for example, in publications US 8037916, US 7387144 and US 20170361663, after vulcanization, colored labels, such as, for example, stripes, inscriptions, logos, decals, barcodes and the like, consisting of one or more colored layers, and an adhesive layer for applying to the sidewall, can be applied to the sidewalls of tires for vehicles.

The essence of the invention

According to the Applicant's teachings, tires incorporating the colored decorative elements (including also including white elements) described above may suffer from some drawbacks.

For example, as Applicant has pointed out, colored compositions can have discoloration problems due to the migration to the visible surface of staining agents, typically represented by (i) antioxidants or aromatic amine anti-ozone agents, and (ii) waxes or other polymeric static protectants commonly found in elastomeric compositions, in particular corresponding compositions used in the manufacture of tires, even in the presence of barrier layers that cannot prevent the above. migration.

In addition, there have been difficulties in obtaining good adhesion between the colored compositions and the surface of the vulcanized tire being coated, both in the case of covulcanization due to the different polymer composition, in particular when using barrier layers based on halogenated rubbers, and in the case of crosslinking due to reduced bond strength, as well as in the case of adhesive labels due to repeated cyclic deformation of the sidewall of the tire and temperature changes that occur during use of the tire.

In addition, for the case that the side of the tire comes into contact with the curb, pavement or other abrasive surfaces during use, the decorative elements easily tend to be scratched and damaged, and similar phenomena may occur during car washing due to the combined action of water and detergents together with abrasive agents (brushes and/or sponges).

As has also been observed by the Applicant, the application of adhesive labels has the effect of making the tire manufacturing steps more complicated due to the use of special tire sidewall labeling stations, preceded by tire sidewall cleaning operations and adaptation of the operation to the tire size, and the consequent decrease in productivity and increase in costs.

As the Applicant has now established, it is possible to overcome the disadvantages described above by manufacturing a tire comprising a pair of sidewalls and at least one colored decorative element having a thickness equal to or greater than 200 μm (micrometers) and directly applied by covulcanization to at least one side of said pair of sidewalls, said pair of sidewalls comprising an elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii ) an ozone protection system, and said at least one decorative element is made from a crosslinkable elastomeric composition containing (i) 100 hours/hundred hours of rubber of an elastomeric polymer containing from 30 to 70 hours/hundred hours of natural rubber and/or synthetic isoprene rubber and from 30 to 70 hours/hundred hours of rubber rubber, choose one of the group consisting of butyl rubber, halobutyl rubber, butadiene rubber, styrene-butadiene rubber and mixtures thereof, (ii) from 5 to 120 hours/hundred hours of rubber, at least one reinforcing filler, (iii) optionally at least 0.5 hours/hundred hours of rubber, at least one coloring agent and (iv) optionally a non-staining ozone protection system.

Applicant has found that the sidewall elastomeric composition and the trim elastomeric composition were fully compatible with each other, and the covulcanization allowed for excellent adhesion between the trim and the sidewall, which overcomes the prior art adhesion and release problems.

In addition, according to the observations of the applicant, the thickness of the decorative element and the mass coloring the elastomeric composition gave the element itself good resistance to abrasion and impact, from which it inevitably suffers under the conditions of use of the tire itself, and at the same time prevented the removal of color, which is easily achievable in the case of applying paints and / or thin layers of pigments on the surface of the sidewall.

Advantageously, as also found by the Applicant, the use of a crosslinkable composition containing a non-staining ozone protection system for the purpose of producing a sidewall has made it possible to avoid or at least reduce discoloration and/or discolouration of the sidewall, but above all of the decorative element applied to it.

Also according to Applicant's observations, a green or partially vulcanized decorative element could easily be brought into contact with the sidewall of a green tire during the molding and vulcanization process and subsequently covulcanized with the tire in conventional tire vulcanizing molds, thus avoiding the additional post-vulcanization processing required to apply the decorative elements to finished tires.

Also, according to the Applicant's observations, during the experiments, the decorative element could also be imprinted using a thin layer of rubber-based printing inks, which in turn could be covulcanized during the molding and vulcanization process and exemplify good abrasion and impact resistance during tire use.

Additional advantages that have become apparent to the Applicant are the rubbery behavior of the decorative element, which makes it possible to resist the deformations experienced after the manufacture of the tire and, in particular, during its inflation and subsequent use under a vehicle, the absence of significant defects during the application of the elastomeric composition of the decorative element on the sidewall of the tire, the absence of significant aging phenomena (i.e., cracking, discoloration or other surface defects) due to exposure to air, ozone and / or high temperatures and chemical resistance, which makes it easy to clean and restore the original color in case of pollution resulting from the use of the tire (for example, in relation to grease residues, dirt or other materials).

Therefore, the first aspect of the present invention relates to a tire comprising:

- a carcass structure, including at least a carcass layer having opposite side edges associated with respective side structures;

- a tread band applied in a radially outward position to said carcass structure;

- a pair of sidewalls applied on the sides on opposite sides with respect to the said frame structure; And

- at least one colored decorative element having a thickness equal to or greater than 200 µm and applied to at least one side of said pair of sidewalls,

wherein said pair of sidewalls comprises an elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii) an ozone protection system, and

said at least one decorative element is made from a crosslinkable elastomeric composition containing:

(i) 100 parts/hundred parts of rubber of an elastomeric polymer containing from 30 to 70 parts/hundred parts of rubber of natural and/or synthetic isoprene rubber and from 30 to 70 parts/hundred of rubber of rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber , styrene-butadiene rubber and mixtures thereof,

(ii) from 5 to 120 hours/hundred hours of rubber, at least one reinforcing filler,

(iii) optionally, at least 0.5 h/hundred hours of rubber, at least one coloring agent and

(iv) optionally a non-staining ozone protection system,

wherein said at least one decorative element is directly applied uncured or partially cured to said at least one sidewall of said pair of green tire sidewalls and subjected to covulcanization by the jointly mentioned green tire.

Preferably, said sidewall pair comprises an elastomeric composition comprising at least one diene elastomeric polymer and a non-staining ozone protection system.

According to yet another aspect, the present invention relates to a colored decorative element comprising at least one layer of a crosslinkable elastomeric composition arranged on a plastic carrier, said elastomeric composition comprising:

(i) 100 parts/hundred parts of rubber of an elastomeric polymer containing from 30 to 70 parts/hundred parts of rubber of natural and/or synthetic isoprene rubber and from 30 to 70 parts/hundred of rubber of rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber , styrene-butadiene rubber and mixtures thereof,

(ii) from 5 to 120 hours/hundred hours of rubber, at least one reinforcing filler,

(iii) optionally, at least 0.5 h/hundred hours of rubber, at least one coloring agent and

(iv) optionally a non-staining ozone protection system.

In accordance with another aspect, the present invention relates to a method for manufacturing a tire, including:

green tire assembly,

introducing the green tire into the tire curing machine,

depositing at least one layer of a crosslinkable elastomeric composition on a plastic carrier,

optionally partial prevulcanization of said at least one layer and profiling of said at least one layer to remove part of it,

applying said at least one layer on the side wall of the mold of said vulcanizing device in accordance with the green tire sidewall,

closing said tire curing apparatus by bringing said at least one layer into contact with said side wall and

covulcanizing said green tire and said layer.

Detailed description of the invention

For the purposes of the present specification and the following claims, unless otherwise indicated, all numbers expressing quantities, amounts, percentage levels, and the like, are to be interpreted as being modified in all instances by the term "approximately". In addition, all ranges include any combination of the highs and lows described, and include any range in between, which may or may not be specifically listed herein.

By "rubber", "elastomeric polymer", or "elastomer" is meant a natural or synthetic polymer which, after vulcanization, can be repeatedly stretched at room temperature to at least twice its original length, and which, upon removal of the tensile load, substantially immediately returns under force to approximately its original length (as defined in the terminology of the ASTM D1566-11 Standard relating to rubber).

The term "non-staining ozone protection system" means an ozone protection system substantially free of staining agents, typically antioxidants, anti-ozone agents, and optionally free of waxes and/or other static polymeric protectants.

The amounts of the various components of the elastomeric composition are generally given in parts/hundred parts of rubber, with the term "parts/hundred parts of rubber" meaning parts of the component when calculated for every hundred parts of rubber minus any extender oils.

For the purposes of this specification and for the following appended claims, the expression "substantially free" indicates the absence or amount between 0 phr. rubber and 0.1 phr./hundred rubber.

For the purposes of this specification and the following appended claims, "directly applied" means the application of one element, such as a decorative layer, to another element, such as a tire sidewall, without any intervening layer or element intervening therebetween.

In accordance with one preferred embodiment, the elastomeric composition used for the manufacture of the tire sidewall contains, based on 100 hours/hundred hours of rubber of the said elastomeric composition:

(a ₁ ) at least one polyisoprene rubber in an amount greater than or equal to 20 hours/hundred hours of rubber, preferably in the range from 30 hours/hundred hours of rubber to 90 hours/hundred hours of rubber, and

(a ₂ ) at least one diene elastomeric polymer other than polyisoprene rubber (a ₁ ), in an amount less than or equal to 80 hours/hundred hours of rubber, preferably in the range from 10 hours/hundred hours of rubber to 70 hours/hundred hours of rubber.

According to one preferred embodiment, the polyisoprene rubber (a ₁ ) can be selected from natural and/or synthetic polyisoprene rubber, preferably natural or synthetic cis-1,4-polyisoprene rubber, synthetic 3,4-polyisoprene rubber, more preferably natural cis-1,4-polyisoprene rubber (natural rubber). Preferably, said natural rubber in the above crosslinkable elastomeric composition is present in an amount ranging from 30 hours/hundred hours of rubber to 60 hours/hundred hours of rubber, more preferably from 30 hours/hundred hours of rubber to 50 hours/hundred hours of rubber.

In accordance with one preferred embodiment, the diene elastomeric polymer (a ₂ ) other than the polyisoprene rubber (a ₁ ) may be selected from suitable materials commonly used in sulfur crosslinkable elastomeric compositions that are particularly well suited for use in the manufacture of tires, or from elastomeric polymers or copolymers comprising an unsaturated chain and having a glass transition temperature (T _g ) generally less than 20°C, preferably in the range from 0°C to - 110°C. These polymers or copolymers may be of natural origin or may be obtained by carrying out solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated diolefins, optionally mixed with at least one comonomer selected from polar monovinylarenes and / or comonomers, in an amount not exceeding 60% (wt.).

Conjugated diolefins generally contain 4 to 12, preferably 4 to 8, carbon atoms and may be selected, for example, from the group consisting of: 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene or mixtures thereof . Especially preferred is 1,3-butadiene.

Monovinylarenes, which may optionally be used as comonomers, generally contain 8 to 20, preferably 8 to 12, carbon atoms and may, for example, be selected from: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl styrene derivatives such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolylstyrene, 4-(4-phenylbutyl)styrene, or mixtures thereof. Styrene is particularly preferred.

Polar comonomers, which may optionally be used, may be selected, for example, from among: vinylpyridine, vinylquinoline, esters of acrylic acid and alkylacrylic acids, nitriles or mixtures thereof, such as, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile or mixtures thereof.

Preferably, the diene elastomeric polymer (a ₂ ) may be selected, for example, from: polybutadiene (particularly polybutadiene having a high level of 1,4-cis units), optionally halogenated isoprene/isobutene copolymers, 1,3-butadiene/acrylonitrile copolymers, styrene/1,3-butadiene (SBR) copolymers, styrene/isopre copolymers on/1,3-butadiene, styrene/1,3-butadiene/acrylonitrile copolymers or mixtures thereof. Particularly preferred are polybutadiene (particularly polybutadiene having a high 1,4-cis content, typically greater than 90%, and a low vinyl content, typically less than 5%), or mixtures thereof. Preferably, said polybutadiene in the aforementioned crosslinkable elastomeric composition is present in an amount ranging from 40 hours/hundred hours of rubber to 70 hours/hundred hours of rubber, more preferably from 50 hours/hundred hours of rubber to 70 hours/hundred hours of rubber.

The aforementioned crosslinkable elastomeric composition may optionally contain at least one elastomeric polymer of one or more monoolefins together with an olefin comonomer or derivatives thereof. The mono-olefins may be selected from: ethylene and α-olefins generally containing from 3 to 12 carbon atoms, such as, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof. Preferred are the following: copolymers selected from copolymers of ethylene and an α-olefin, optionally together with a diene; isobutene homopolymers or copolymers thereof, together with small amounts of a diene, which are optionally at least partially halogenated. The optionally present diene generally contains from 4 to 20 carbon atoms and is preferably selected from among: 1,3-butadiene, isoprene, chloroprene, neoprene, 1,4-hexadiene, 1,4-cyclohexadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, vinyl norbornene, or mixtures thereof. Among them, the following are especially preferred: ethylene/propylene copolymers (EPR) or ethylene/propylene/diene copolymers (EPDM); polyisobutene; butyl rubber; halobutyl rubbers, in particular chlorobutyl or bromobutyl rubbers; or mixtures thereof.

The aforementioned crosslinkable elastomeric composition may optionally comprise at least one polyisoprene rubber (a ₁ ) and/or at least one diene elastomeric polymer (a ₂ ) functionalized by reaction with suitable chain termination agents or coupling agents. 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 reaction between residual organometallic groups derived from the initiator and suitable chain termination agents or coupling agents such as, for example, imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes or aryloxysilanes (see, for example, EP 451604 or US 4742124 and 4550142).

Advantageously, at least one reinforcing filler may be added to the aforementioned crosslinkable elastomeric composition, generally in an amount ranging from 0 phr/hundred rubber to 120 phr/hundred rubber, preferably from 20 phr/hundred rubber to 90 phr/hundred rubber. The reinforcing filler may be selected from suitable materials widely used for crosslinked industrial products, in particular for tires, such as carbon black, silica, alumina, aluminosilicates, calcium carbonate, kaolin or mixtures thereof. Particularly preferred are carbon black, silica and mixtures thereof.

According to one preferred embodiment, said carbon black reinforcing filler may be selected from suitable materials which have a specific surface area of at least 20 m ² /g (as defined in terms of SPCA - Statistical Surface Area - in accordance with ISO 18852:2005).

The silica that can be used in the present invention can generally be fumed silica, or preferably precipitated silica, having a BET specific surface area (measured according to ISO 5794/1) in the range of 50 ^m2 /g to 500 ^m2 /g, preferably 70 ^m2 /g to 200 ^m2 /g.

In the presence of a reinforcing filler containing silica, the crosslinkable elastomeric composition may advantageously contain a silane coupling agent capable of reacting with the silica and bonding it to the elastomeric polymer during cure.

The coupling agents that are preferably used are the corresponding silane-based compounds, which can be described, for example, using the following structural formula (I):

(R ₂ ) ₃ Si-C _t H _2t -X, (I)

in which the R ₂ groups, which may be identical or different from each other, are selected from among: alkyl, alkoxy or aryloxy groups or halogen atoms, provided that at least one of the R ₂ groups is an alkoxy or aryloxy group; t is an integer in the range between 1 and 6, inclusive; X is a group selected from among: nitroso, marcapto, amino, epoxide, vinyl, imide, chlorine, -(S) _u C _t H _2t -Si-(R ₂ ) ₃ or -S-COR ₂ in which u and t are integers in the range between 1 and 6 with the inclusion of boundary values, and the R ₂ groups correspond to the above definition of the invention.

Among the coupling agents, bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide are particularly preferred. Said coupling agents may be used as such or as suitable blends with an inert filler (such as carbon black) so as to facilitate their incorporation into the crosslinkable elastomeric composition.

In accordance with one preferred embodiment, said silane coupling agent in the elastomeric composition is present in an amount in the range between 0.01 hours/hundred hours of rubber and about 10 hours/hundred hours of rubber, preferably between about 0.5 hours/hundred hours of rubber and about 5 hours/hundred hours of rubber.

According to one preferred embodiment, the non-staining ozone protection system is substantially free of aromatic amine antioxidants and/or anti-ozone agents such as, for example, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (DMBPPD), N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD) or N-(1,3-dimethylbutyl)-N'-phenylphenylenediamine (6PP D).

Preferably, in particular when used in elastomeric compositions in the absence of white reinforcing fillers, the non-staining ozone protection system is also substantially free of (i) waxes, such as petroleum wax, and/or (ii) other static polymeric protection, such as, for example, in the case of polyethylene glycol and (meth)acrylic copolymers.

Advantageously, the non-staining ozone protection system essentially consists of at least one phenolic antioxidant equal to or greater than 3 parts/hundred parts rubber, preferably equal to or greater than 4 parts/hundred parts rubber, and/or at least one cyclic acetal or enol ether antioxidant equal to or greater than 1 part/hundred parts rubber ka, preferably equal to or greater than 2 hours/hundred hours of rubber.

Suitable examples of useful phenolic antioxidants are pentaerythrityltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] sold by BASF under the designation IRGANOX 1010; 2,2-thiodiethylenebis[(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)] sold by BASF under the designation IRGANOX 1035; octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate sold by BASF under the designation IRGANOX 1076; isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate sold by BASF under the designation IRGANOX 1135; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene sold by BASF under the designation IRGANOX 1330; 4,6-bis(dodecylthiomethyl)-o-cresol sold by BASF under the designation IRGANOX 1726; 4,6-bis(octylthiomethyl)-o-cresol sold by BASF under the designation IRGANOX 1520; triethylene glycol bis[(3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate)] sold by BASF under the designation IRGANOX 245; 1,6-hexanediolbis[(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)] sold by BASF under the designation IRGANOX 259; 4-{[4,6-bis(octylsulfanyl)-1,3,5-triazin-2-yl]amino}-2,6-di-tert-butylphenol sold by BASF under the trade name IRGANOX 565.

Preferably, said phenolic antioxidant is selected from the group consisting of 4,6-bis(octylthiomethyl)-o-cresol sold by BASF under the trade name IRGANOX 1520 and 4-{[4,6-bis(octylsulfanyl)-1,3,5-triazin-2-yl]amino}-2,6-di-tert-butylphenol sold by BASF under the trade name IRGAN OX 565.

Suitable examples of cyclic acetal or enol ether antioxidants are 3,9-di-3-cyclohexen-1-yl-2,4,6,10-tetraoxaspiro[5.5]undecane sold by Lanxess under the trade name Vulkazon AFS/LG and cyclohexen-3-ylidenemethylbenzyl ether sold by Lanxess under the trade name Vulkaz on ADF.

The decorative element according to the present invention is made from a crosslinkable elastomeric composition containing (i) 100 phr/hundred rubber of an elastomeric polymer containing from 30 to 70 phr/hundred rubber of natural and/or synthetic isoprene rubber and from 30 to 70 phr/hundred rubber of a rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber, styrene-butadiene rubber and mixtures thereof, (ii) from 5 to 120 hours/hundred hours of rubber, at least one reinforcing filler, (iii) optionally at least 0.5 hours/hundred hours of rubber, at least one coloring agent and (iv) optionally non-staining en ozone protection system.

In one embodiment according to the invention, the decorative element is made from a crosslinkable elastomeric composition containing 100 phr/hundred rubber of an elastomeric polymer consisting of 30 to 70 phr/hundred rubber of natural and/or synthetic isoprene rubber and from 30 to 70 phr/hundred rubber of a rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber, styrene-butadiene rubber and mixtures thereof.

The decorative element has a thickness equal to or greater than 200 μm (micrometers), preferably equal to or greater than 250 μm, even more preferably equal to or greater than 300 μm.

Preferably, the decorative element has a thickness equal to or less than 800 microns, more preferably equal to or less than 600 microns, even more preferably equal to or less than 500 microns.

In accordance with one preferred aspect of the present invention, the decorative element is made from a crosslinkable elastomeric composition containing 100 parts/hundred parts rubber of an elastomeric polymer containing from 30 to 70 parts/hundred parts of natural and/or synthetic isoprene rubber and from 30 to 70 parts/100 parts of butyl or halobutyl rubber, or from 30 to 70 hours/one hundred hours of butadiene or styrene-butadiene rubber or from 30 to 70 hours/one hundred hours of rubber mixtures thereof.

Preferably, said natural and/or synthetic isoprene rubber in the crosslinkable elastomeric composition is present in an amount ranging from 40 hours/hundred hours of rubber to 60 hours/hundred hours of rubber, more preferably in an amount of approximately 50 hours/hundred hours of rubber.

Advantageously, said crosslinkable elastomeric composition contains butyl or halobutyl rubber in an amount ranging from 40 hours/hundred hours of rubber to 60 hours/hundred hours of rubber, more preferably in an amount of approximately 50 hours/hundred hours of rubber.

Preferably, said crosslinkable elastomeric composition contains butadiene and/or styrene-butadiene rubber in an amount ranging from 40 hours/hundred hours of rubber to 60 hours/hundred hours of rubber, more preferably in an amount of approximately 50 hours/hundred hours of rubber.

Alternatively, said crosslinkable elastomeric composition contains from 40 hours/hundred hours of rubber to 60 hours/hundred hours of rubber, more preferably about 50 hours/hundred hours of rubber, a mixture of butyl or halobutyl rubber and butadiene and/or styrene-butadiene rubber. Butyl rubber is a rubber obtained by the cationic polymerization of isobutylene together with isoprene at percentage levels of the latter in the range of 2-7%.

Halogenated butyl rubber is a halogenated butyl rubber. The halogen atom is present after post-treatment of butyl rubber by reacting chlorine or bromine with butyl rubber according to methods known in the art. As is known in the state of the art, butyl rubber is a copolymer containing about 95.5-99.5% (mole) isobutylene and 0.5-4.5% (mole) isoprene. Halobutyl rubber includes chlorobutyl rubber, bromobutyl rubber, or mixtures thereof. Butadiene rubber is a synthetic rubber obtained from the polymerization of 1,3-butadiene.

Styrene-butadiene rubber is a copolymer of styrene and 1,3-butadiene. The amount of styrene (ratio between the mass of styrene units and the mass of total monomer units) in the styrene-butadiene rubber is not particularly limited, but it is preferably equal to or greater than 5% (mass), more preferably equal to or greater than 10% (mass), in particular, equal to or greater than 15% (mass). In addition, the amount of styrene is preferably equal to or less than 50% (wt.), more preferably equal to or less than 45% (wt.), in particular, equal to or less than 30% (wt.). The level of vinyl linkages for butadiene monomer units contained in the styrene-butadiene rubber is preferably equal to or greater than 30% (wt.), more preferably equal to or greater than 35% (wt.), in particular, equal to or greater than 40% (wt.). In addition, the level of vinyl bonds is preferably equal to or less than 90% (mass.), more preferably equal to or less than 80% (mass.), in particular, equal to or less than 70% (mass.).

The decorative element is made from a crosslinkable elastomeric composition containing 100 hours/hundred hours of rubber of an elastomeric polymer, from 5 to 120 hours/hundred hours of rubber, preferably from 30 to 120 hours/hundred hours of rubber, more preferably from 60 to 120 hours/hundred hours of rubber, at least one reinforcing filler.

The reinforcing filler may be selected from suitable reinforcing fillers commonly used for crosslinked industrial products, in particular for tires, such as carbon black, silica, titanium dioxide, alumina, aluminosilicates, calcium carbonate, kaolin, talc, chalk, or mixtures thereof.

For the production of white and/or colored decorative elements, light reinforcing fillers are preferred. Generally, the light reinforcing filler may be selected from: silica, alumina, titanium dioxide, aluminosilicates, bentonite, calcium carbonate, kaolin, talc, barite (barium sulfate), chalk, or mixtures thereof. Particularly preferred light reinforcing fillers are silica, titanium dioxide, kaolin, barium sulfate and mixtures thereof.

In particular, the light reinforcing filler may contain up to 60 hours/hundred hours of silicon dioxide rubber, up to 40 hours/hundred hours of kaolin rubber and up to 60 hours/hundred hours of titanium dioxide rubber. When silica is present, it is preferably present in an amount in the range between 1 and 60 hours/hundred hours of rubber, more preferably between 5 and 50 hours/hundred hours of rubber. For the case where kaolin is present, it is preferably present in an amount in the range between 1 and 40 hours/hundred hours of rubber, more preferably between 5 and 35 hours/hundred hours of rubber. In the case of the presence of titanium dioxide, it is preferably present in an amount in the range between 1 and 60 hours/hundred hours of rubber, more preferably between 5 and 50 hours/hundred hours of rubber.

In particular, titanium dioxide can be used both as a reinforcing filler and as a coloring agent to give a rich and/or white color.

To impart other properties to the elastomeric composition of the decorative element, dark reinforcing fillers, usually carbon black, can be added to said composition, as long as the color of the filler does not adversely modify or change the desired color of the colored composition. The presence of carbon black at a very low level of percentage, i.e., at the level of a few parts/hundred parts of rubber, such as, for example, in the range of 1-5 parts/hundred parts of rubber, makes it possible to obtain a color characterized by a darker appearance, in particular when using red, blue and green pigments.

Dark reinforcing fillers, typically carbon black, are preferred for making black decorative elements that function as a protective barrier and print carrier when using rubber-based ink layers capable of being covulcanized with the decorative element during the molding and curing process. Rubber based printing inks are known in the state of the art and usually contain a dye or pigment dispersed in a polymer base containing natural and/or synthetic rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, halobutyl rubber and mixtures thereof. The rubber-based printing inks can be printed using printing techniques known in the art, such as, for example, screen printing, digital printing, flexographic printing, and/or pad printing.

The rubber-based ink layer has a thickness equal to or greater than 5 μm (micrometers), preferably equal to or greater than 10 μm, even more preferably equal to or greater than 15 μm.

Preferably, the rubber-based ink layer has a thickness equal to or less than 50 µm, even more preferably equal to or less than 40 µm, even more preferably equal to or less than 30 µm.

One example describes the composition of a yellow printing ink (on a dry weight basis) which is used after dissolving in an organic solvent (a mixture of aromatic hydrocarbons):

Ingredient hours / one hundred hours of rubber NR (or IR) 50 Styrene butadiene rubber thirty BR 20 TiO ₂ 50 _BaSO4 50 ZnO 5 Stearic acid 2 Plasticizer / compatibilizer 5 Non-staining antioxidant 3 Thiazole Accelerator 2 ultra accelerator 4 organic pigment 20

Styrene butadiene rubber: SBR 1502=ESBR without oil filling (23.5% styrene)

BR: Neocis BR40 from Versalis

Plasticizer / compatibilizer: wax, paraffin oil

Ultra Accelerator: Rhenogran ZBEC 70: zinc dibenzyldithiocarbamate (70%) from Rheinchemie

Thiazole accelerator: Rhenogran MBTS 80 from Rheinchemie

Non-Staining Antioxidant: LOWINOX CPL: Reaction product between tert-butyl-p-cresol and dicyclopentadiene from Addivant

Organic Pigment: SUDAPERM YELLOW 2923 from SUDARSHAN

The example describes an elastomeric layer composition on which a layer of rubber ink can be deposited to form a two-layer decorative element.

Ingredient hours / one hundred hours of rubber NR (or IR) 70 Styrene butadiene rubber thirty carbon black 10 Talc 50 Stearic acid 2 Zn oxide 3 Non-staining antioxidant 1.5 Wax 1 Secondary accelerator 2.5 primary accelerator 1 Sulfur donor 4

Styrene butadiene rubber: SBR 1502=ESBR without oil filling (23.5% styrene)

Carbon black: N550 from Columbian Trecate

Non-Staining Antioxidant: LOWINOX CPL: Reaction product between tert-butyl-p-cresol and dicyclopentadiene from Addivant

Talc: Mistron Vapor by IMERYS

Primary accelerator: Huathai CBS

Secondary accelerator: Rhenogran MBTS 80, supplied by REINCHEMIE

Sulfur donor: Rhenogran CLD80, supplied by Rheinchemie

Optionally, the decorative element is made from a crosslinkable elastomeric composition containing, per 100 hours/hundred hours of rubber of the elastomeric polymer, at least 0.5 hours/hundred hours of rubber, at least one coloring agent, preferably at least 1 hour/hundred hours of rubber, even more preferably at least 5 hours/hundred hours of rubber.

Preferably, the decorative element is made from a crosslinkable elastomeric composition containing, per 100 hours/hundred hours of rubber of the elastomeric polymer, an amount less than or equal to 100 hours/hundred hours of rubber, at least one coloring agent, more preferably less than or equal to 80 hours/hundred hours of rubber, even more preferably less than or equal to 60 hours/hundred hours of rubber, for example, in the range between 10 and 50 hours/hundred hours of rubber.

According to one preferred embodiment, said coloring agent can be selected from among: titanium dioxide, zinc oxide, iron oxides, metals such as powdered aluminum or copper, metal pastes such as aluminum pastes, pigments containing organic components, pigments containing inorganic components, pigments containing fluorescent components, UV absorbing pigments, pigments containing mineral components, amorphous oxides. glass, polyacrylates, metal flakes, reflective pigments or mixtures thereof.

The choice of coloring agent and its amount varies depending on the choice of color and the intensity of color imparted to the surface to be coated.

Examples of coloring agents that can be used in accordance with the present invention and are commercially available are Offset® FM/4500 (aluminum paste) from Schlenk or Hostaperm Blue® BT-617-D (blue pigment), Hostaperm Green GG 01 (green pigment), Hostaperm Orange PR (orange pigment), Hostaperm Red E2B 70 (red pigment), Hostaperm Yellow H3G (yellow pigment) from Clariant.

The decorative element can be made in the form of an imprint using rubber-based printing inks on an elastomeric mixture element, for example, black, or it can be made in the form of a layer of rubber-based printing ink deposited on a layer of elastomeric mixture and subjected to subsequent die-cutting, or made from an elastomeric composition dyed in mass.

The decorative element is made on or articulated with the following: a carrier, preferably made of a plastic material, for example, made of polyethylene terephthalate or polyamide, in accordance with the above description of the invention while the colored area or layer is in contact with the carrier.

The decorative and carrier assembly may be applied to the sidewall of a green tire and co-cured with the tire, or it may be applied to the sidewall of a finished tire and subsequently cured.

Advantageously, the decorative element and carrier assembly is applied to the green tire sidewall and cured with the tire.

The elastomeric compositions described above (both the corresponding decorative element composition and the corresponding compositions of the sidewall and other tire components) can be cured according to known techniques, in particular using sulfur-based curing systems widely used for elastomeric polymers. For this purpose, the elastomer composition after one or more stages of thermomechanical processing includes a sulfur-based vulcanizer together with vulcanization accelerators. In the final processing step, the temperature is generally maintained at less than 120° C. so as to avoid any undesirable premature crosslinking phenomena.

The most advantageously used vulcanizer is sulfur or sulfur-containing molecules (sulfur donors) together with accelerators and activators known to those skilled in the art.

Activators which are particularly effective are zinc-based compounds, and in particular ZnO, ZnCO ₃ , zinc salts of saturated or unsaturated fatty acids containing from 8 to 18 carbon atoms, such as, for example, zinc stearate, which are preferably formed "in situ" in the elastomeric composition starting from ZnO and a fatty acid, as well as Bi ₂ O ₃ , PbO, Pb ₃ O ₄ , PbO ₂ or mixtures thereof.

Accelerators that are widely used may be selected from dithiocarbamates, guanidine, thiourea, thiazoles, sulfonamides, thiurams, amines, xanthates, or mixtures thereof.

The elastomeric compositions used may include other broadly selectable additives based on the particular application for which each composition is intended. For example, the following additives may be added to said elastomeric compositions: antioxidants, antioxidants, plasticizers, adhesives, antiozone builders, resins, fibers (aramid or natural) or mixtures thereof.

Preferably, the elastomeric compositions used for the decorative element comprise a non-staining ozone protection system substantially free of aromatic amine-based antioxidants and/or anti-ozone agents such as, for example, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (DMBPPD), N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD) or N-(1,3-dimethylbutyl)- N'-phenylphenylenediamine (6PPD). Preferably, in particular when used in elastomeric compositions in the absence of white reinforcing fillers, the non-staining ozone protection system is also substantially free of (i) waxes such as petroleum wax and/or (ii) other static polymeric protection such as, for example, polyethylene glycol and (meth)acrylic copolymers.

Advantageously, the non-staining ozone protection system, optionally used for the decoration, essentially consists of at least one phenolic antioxidant equal to or greater than 3 parts/hundred parts rubber, preferably equal to or greater than 4 parts/hundred parts rubber, optionally in combination with at least one cyclic acetal or enol ether antioxidant equal to or greater than m 1 h/hundred hours of rubber, preferably equal to or greater than 2 h/hundred hours of rubber, in accordance with the description of the invention in international patent application No. PCT/IB2018/051388.

Suitable examples of phenolic antioxidants that can be used are the same as the corresponding antioxidants described above with reference to the sidewall elastomeric composition.

The elastomeric compositions used to make the sidewall and trim do not contain or contain less than 0.1 phr/100 phr of antioxidants, anti-ozone agents, waxes, and other polymeric static protectants, which are present in the elastomeric compositions used in the manufacture of other tire components and are present in staining agents. However, greater than 0.1 parts/hundred parts rubber amounts of such staining agents may be present in the sidewall and more rarely in the decorative element of the tire of the present invention due to partial migration of such staining agents from the tire's internals.

Below in this document, the present invention will now be described with reference to the accompanying drawings, presented for illustrative purposes only and therefore non-limiting purposes. On the drawings:

Fig. 1 is a half cross section illustrating a tire for motor vehicle wheels according to one embodiment of the present invention;

Fig. 2 is a photograph of a tire according to one embodiment of the present invention at the end of the dynamic ozone test of Example 2;

Fig. 3 is a photograph of a tire according to one embodiment of the present invention at the end of the fatigue test of Example 3;

Fig. 4 is a comparative photograph of a tire according to one embodiment of the present invention at the end of the rolling resistance test of the wheel of Example 4 before and after cleaning.

Detailed description of embodiments of the invention

Fig. 1 illustrates a tire 100 including a sidewall 108 on which there is a colored decorative element 120 (in the sense that it is also white as colored) made in accordance with the present invention.

On FIG. 1, the decorative element 120 may cover only part of the sidewall 108 of the tire, such as in the case where the decorative element 120 includes patterns, letters, logos, marks, decals applied to the sidewall of the tire, or it can cover almost the entire sidewall 108, such as in the case where the said decorative element 120 includes a layer arranged, in whole or in part, along the circular section of the sidewall 108.

On FIG. 1 "a" indicates the axial direction and "r" indicates the radial direction.

As for FIG. 1, a tire 100 for vehicle wheels includes at least one carcass structure including at least one carcass ply 101 having respectively opposing end rim bands engaged with respective annular locking structures 102, referred to as bead cores, optionally associated with a filler cord in bead 104. Tire area including bead core 102 and on An additional bead cord 104 forms a reinforcing annular structure 103, a so-called bead, for fixing the tire to a suitable mounting rim, not illustrated.

The carcass structure is typically of the radial type, that is, the mutually parallel reinforcing elements of at least one carcass ply 101 are arranged in planes including the tire's axis of rotation and substantially perpendicular to the equatorial plane of the tire.

Alternatively, tires (not illustrated) are provided with diagonal carcass structures.

In such tires, the carcass structure may include at least first and second carcass plies laminated in the radial direction, each of which is made of an elastomeric material and includes a plurality of mutually reinforcing elements arranged parallel to each other.

The carcass layers are layered in the radial direction so that the reinforcing elements of one layer would be inclined with respect to the reinforcing elements of the carcass layer layered in the radial direction and to the equatorial plane.

In the carcass ply(s) (both in radial and bias carcass tyres), the reinforcing elements can be composed of metal and/or textile cords, e.g. steel for the case of metal cords, or viscose, lyocell, nylon, polyester [e.g. polyethylene naphthalate (PEN)] for the case of textile cords. Each reinforcing annular structure is connected to the carcass structure by folding back the opposite side edges of at least one carcass layer 101 around the annular fixing structure 102 so as to form so-called carcass rim bands 101a, as illustrated in FIG. 1.

In one embodiment, the articulation between the carcass structure and the reinforcing annular structure can be provided using a second carcass ply (not illustrated in FIG. 1) superimposed at an axially outward position with respect to the first carcass ply.

In an outward position, an anti-abrasive tape 105 is arranged for each reinforcing ring structure 103. Preferably, each anti-abrasive tape 105 is arranged at least axially outward with respect to the reinforcing ring structure 103, extending at least between the sidewall 108 and a portion that is radially inferior to the reinforcing ring structure 103.

Advantageously, the anti-abrasion tape 105 is preferably made using the same elastomeric composition as the corresponding composition used to make the sidewalls 108 of the present invention, i.e., a crosslinkable elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii) a non-staining ozone protection system.

Preferably, the anti-abrasive tape 105 is configured to wrap around the reinforcing annular structure 103 along the axially inner and outer and radially lower regions of the reinforcing annular structure 103 so as to be sandwiched between the latter and the wheel rim when the tire 100 is mounted on the rim.

In radial tires, the carcass structure is associated with a belt structure 106 including one or more belt plies 106a, 106b arranged in radial overlap with each other and with respect to the carcass ply, and typically comprising metal reinforcing cords. Such reinforcing cords may be oriented in a cross direction with respect to the circumferential direction of tire 100. By "circumferential" direction is meant a direction generally oriented in accordance with the direction of rotation of the tire.

At a radially outermost position with respect to the breaker plies 106a, 106b, at least one zero degree reinforcing layer, commonly known as a "0° breaker", which generally includes a plurality of reinforcing cords, typically textile cords, oriented in a substantially circumferential direction, thus forming an angle of several degrees (such as an angle in the range between approximately 0° and 6°) with respect to the equato rial plane of the tire and coated with an elastomeric material.

In a radially outer position with respect to the belt structure 106, a tread band 109 of an elastomeric mixture is applied.

In some embodiments (eg, in the case of tires for motorcycle or scooter wheels), the belt structure may be omitted.

In a radially outward position, the tread band 109 has a rolling surface 109a designed to engage the ground. On this surface 109a, which for the sake of simplicity in FIG. 1 is smooth, generally circumferential grooves are made which are connected by transverse cuts (not illustrated in FIG. 1) so as to define a plurality of blocks of different profiles and sizes distributed on the rolling surface 109a.

Between the belt structure 106 and the tread band 109, an undertread layer 111 is arranged.

In the case of tubeless tyres, a rubber layer 112, generally known as a "sealing layer", can also be provided in a radially inward position with respect to the carcass ply 101, which imparts the necessary airtightness to the tire's inflation air.

In addition, respective sidewalls 108 made from a crosslinkable elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii) a non-staining ozone protection system are further applied to the side surfaces of the carcass structure, each extending from one of the side edges of the tread 109 onto a respective reinforcing annular structure 103.

In the area of connection between the sidewalls 108 and the tread band 109, a tape consisting of an elastomeric material 110 and commonly known as a "mini-sidewall" may optionally be provided, this mini-sidewall being generally co-extruded together with the tread band 109 and making it possible to improve the mechanical interaction between the tread band 109 and the sidewalls 108. Preferably, the end portion of the sidewall 1 08 directly covers the side edge of the tread band 109.

Preferably, when mini-sidewall 110 is present, it is made like a sidewall from a crosslinkable elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii) a non-staining ozone protection system.

On the outer surface of at least one of the two sidewalls 108 (as illustrated in Fig. 1) at least one decorative element 120 made in accordance with the present invention is applied by covulcanization.

Assembly of the tire 100 according to the present invention may be carried out in accordance with techniques and apparatuses known in the art, said assembly including making a green tire, making a green decorative element, molding, curing a green tire and a green decorative element.

Application of the green or partially cured decorative element can take place on the green tire (in which case the curing of the decorative element 120 will be simultaneous with the curing of the tire 100) or on the finished tire (in which case the curing of the green decorative element will follow the curing of the green tire).

For the purposes of the present invention, the application of the green or partially cured decorative element takes place on the green tire.

In particular, the assembly of tires 100, which correspond to the above description of the invention, can be carried out by confectioning the respective semi-finished products on a forming drum, not illustrated, using at least one confectioner.

At least a portion of the components for forming the carcass structure of the tire may be assembled and/or shaped on the forming drum. More specifically, the shaping drum is designed to receive first a possible sealing layer, then a carcass structure. Subsequently, devices not illustrated implement coaxial engagement for one of the annular locking structures around each of the end rim bands, and subsequently position the sidewalls and the anti-abrasive tape.

After that, in a coaxially centered position around the cylindrical frame shell, an outer shell can be located, including a belt structure and a tread band, which can profile the frame shell in accordance with the toroidal configuration while radially expanding the frame structure in such a way as to stimulate its deposition on the radially inner surface of the outer shell.

Once the green tire is assembled, a molding and curing treatment is generally performed to determine the structural stabilization of the tire by crosslinking the elastomer compounds, as well as the desired tread pattern on the tread band and any distinctive sidewall graphics.

The molding and curing treatment is carried out in a curing apparatus known in the state of the art and comprising a toroidal carrier designed to adhere to a tire being processed, a curing mold designed to receive a toroidal carrier, pressing tools for pressing the outer surface of the tire against the walls of a mold cavity, including sidewalls designed to form sidewall surfaces, and a crown of sectors designed to form a tread surface; and heating means for transferring heat to the tire closed between the mold cavity and the toroidal carrier. Decorative element 120 may be located directly on the molding drum prior to sidewall assembly, it may be positioned on the green tire prior to molding and curing, or it may be positioned on the side of the curing apparatus and brought into contact with the green tire sidewall during curing.

Advantageously, decorative element 120 articulated with the carrier layer is positioned on the side of the curing apparatus and brought into contact with the green tire sidewall during curing.

According to Applicant's observations, the application of the decorative element 120 during the molding and vulcanization process inside the vulcanizing apparatus provides the possibility of simplifying the application operations, but, above all, facilitating obtaining the correct position of the decorative element 120 on the surface of the sidewall 108 of the tire 100 in order to avoid extrusion and / or deviations, which are the result of application to the unvulcanized sidewall or to the forming drum.

In particular, in accordance with one aspect of the present invention, the decorative element 120 is obtained in the form of a layer by depositing the elastomeric composition of the present invention on a plastic carrier consisting of polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamide, polyimide, perfluorinated polymers such as polytetrafluoroethylene (PTFE), and polyurethanes (PU). ).

The plastic carrier provides the necessary carrier for the elastomeric composition layer during the subsequent processing steps. The plastic carrier is selected on the basis of its thermal resistance properties, in particular at curing temperatures generally between 150°C and 180°C.

The plastic carrier is preferably made from polyethylene terephthalate (PET) or polyamides such as, for example, Nylon 6 or Nylon 66 products, in a thickness between 10 and 150 micrometers (μm), preferably between 20 and 75 micrometers (μm).

The layer thus formed can be applied directly to the sidewall of the mold or optionally subjected to partial prevulcanization.

Prevulcanization is carried out for a period of at least 1 hour, preferably at least 2 hours, at a temperature equal to or less than 100°C, preferably less than 90°C, more preferably less than 80°C, but equal to or greater than 40°C, preferably greater than 50°C, more preferably greater than 60°C.

Partial prevulcanization imparts sufficient consistency to the layer to be profiled when part of it is removed if the decorative element 120 consists of a plurality of letters, numbers, or any graphic indicia, discrete or having a significant extent, such as, for example, a manufacturer's brand and/or product name and/or annular bands. The removal of portions of the layer to form the above words can be carried out using methods known in the state of the art, such as, for example, laser ablation or mechanical removal.

In the case where the decorative element 120 consists of a more or less wide continuous layer covering a portion or the entire surface of the sidewall, the layer articulated with the carrier can be directly applied to the side wall of the mold, although in this case it can also be subjected to prevulcanization treatment.

The partial pre-vulcanization of the layer also allows a thin layer of rubber-based printing inks to be printed on the surface of the layer itself to form the decorative element 120.

This layer, together with the plastic carrier, is placed on the side wall of the mold with the exposed surface of the elastomeric composition facing the inside of the vulcanizing apparatus, on the sidewall of the green tire and sticking the plastic carrier to the surface of the side wall of the mold.

After that, the vulcanizing apparatus is closed and the vulcanization method is started, which consists in bringing the temperature inside the apparatus to a value in the range between 150°C and 180°C for a period of time in the range between 10 seconds and 40 minutes while pressing the outer surface of the tire against the walls of the mold cavity, during which the layer of the elastomeric composition of the decorative element and the sidewall of the green tire are covulcanized, which realizes mutual adhesion between the surfaces facing ny to each other.

Some of the tests carried out on tires made in accordance with the invention are described below.

EXAMPLE 1

Getting a tire

The tires used were Pirelli P ZERO ^TM 245/35ZR21 (96Y) front (tire 1) and Pirelli P ZERO ^TM 285/30ZR21 (100Y) rear (tire 2).

The tires used were manufactured according to the method of the present invention and included sidewalls made using the composition described in Table 1 and decorative elements consisting of two continuous strips approximately one third of the circumference of the sidewall, arranged symmetrically to one another, with the inscription "PIRELLI" and the inscription "P ZERO", having a thickness of 300 microns (micrometers) and made using the compositions described in Table 2.

The values in tables 1 and 2 are expressed in hours/hundred hours of rubber.

Table 1

Component Quantity natural rubber 40 Butadiene rubber 60 Carbon black 660 50 tackifying resin 2 Stearic acid 2 zinc oxide 2.85 Non-staining antioxidant 8 Moderator 0.1 primary accelerator 0.8 Sulfur 2 Butadiene rubber : Neocis BR40, Versalis carbon black : N660, Columbian tackifying resin : Quintone A100, Zeon Corporation Non-staining antioxidant : Irganox 1520L, 4,6-bis[(octylthio)methyl]-o-cresol, BASF Moderator : N-cyclohexylthiophthalimide primary accelerator : CBS, N-cyclohexyl-2-benzothiazylsulfenamide, Huathai

table 2

Component Composition A Composition B natural rubber 50 65 Bromobutyl rubber 50 - Styrene butadiene rubber - 35 Silica 40 20 Silane Si69 3 6 Titanium dioxide 10 20 Talc 15 thirty plasticizer 10 10 Antioxidant 1 3 3 Antioxidant 2 2 tackifying resin 3 orange pigment 10 10 Stearic acid 2 2 zinc oxide 5 3 primary accelerator 2 1 Thiazole Accelerator 3 Sulfur 0.6 - Sulfur donor 1.5 -

Styrene butadiene rubber: SBR 1502=ESBR without oil filling (23.5% styrene)

Plasticizer: wax, paraffin oil

Silica: Zeosil 185 GR from Solvay

Primary accelerator: cyclohexylbenzothiazolesulfenamide Huathai CBS

Thiazole accelerator: Rhenogran MBTS 80 from Rheinchemie

Antioxidant 1: IRGANOX 1520 L from BASF

Antioxidant 2: 3,9-di-(3-cyclohexenyl)-2,4,8,10-tetraoxaspiro(5.5)undecane Vulkazon AFS/LG from Lanxess

Sulfur donor: poly-tert-butylphenol disulfide and stearic acid Vultac TB710 from ARKEMA

Tires incorporating decorative elements made from composition A are referred to as 1A and 2A, while tires incorporating decorative elements made from composition B are referred to as 1B and 2B.

EXAMPLE 2

Tire dynamic ozone test

A dynamic ozone test was performed on tires inflated to 2.6 bar and subjected to (controlled) stress at a constant vertical load of 50% of the tire load index and a constant speed of 120 km/h, with 3 g/m ³ ozone directly applied to the sidewall with the nozzle at a distance of 7 cm.

The test was carried out using an Indoor machine with a 1.7 meter running wheel in a temperature controlled conditioned environment between 28°C and 30°C.

The whole test lasted 200 hours. At the end of the test, the covers were examined to check for defects on the decorative elements (separations, cracks, discolouration) and the results are summarized in the following Table 3.

Table 3

Tire disconnections Cracking Color change 1A No No No 1B No No No 2A No No No 2B No No No

On FIG. 2 illustrates a photograph of the tire at the end of the test. All tested tires successfully passed the test without any appreciable damage to the decorative elements.

EXAMPLE 3

Tire durability test

The endurance test consists of a high speed performance test and a fatigue test.

SPEED TEST

The high speed performance test was performed on tires inflated to 3.6 bar. The test is carried out using an Indoor machine with a road wheel having a diameter of 1.7 meters, at a camber angle of 2°, in a conditioned temperature controlled environment of 27.5°C ± 2.5°C.

During the test, the tires were stressed with a constant vertical load of 575 kg (tire 1) or 650 kg (tire 2) at speeds varying over time in the range of 240 to 320 km/h.

The entire test lasted 2 hours and 20 minutes. At the end of the test, the covers were examined to check for defects on the decorative elements (separations, cracks, discolouration) and the results are summarized in the following Table 4.

Table 4

Tire disconnections Cracking Color change 1A No No No 1B No No No 2A No No No 2B No No No

All tested tires successfully passed the test without any appreciable damage to the decorative elements.

FATIGUE TEST

The fatigue test was carried out on tires inflated to a (controlled) pressure of 3 bar and subjected to stress at a constant vertical load of 160% of the tire load index and a constant speed of 120 km/h.

The test was carried out using an Indoor machine with a 1.7 meter running wheel in a temperature controlled conditioned environment of 27.5°C±2.5°C. The test included tire check stops every 12 hours and continued until the pavement broke (at the end of the breaker).

At the end of the test, the covers were examined to check for defects on the decorative elements (separations, cracks, discolouration) and the results are summarized in the following Table 5.

Table 5

Tire disconnections Cracking Color change 1A No No No 1B No No No 2A No No No 2B No No No

On FIG. 3 illustrates a photograph of the tire at the end of the test. All tested tires successfully passed the test without any appreciable damage to the decorative elements.

EXAMPLE 4

Road durability test

In view of the good results obtained and illustrated in Example 3, the tests were carried out with the grip of the tire on the road.

The test took place on a private track at an average speed of approximately 200 km/h for a total of approximately 150 km. The test was carried out using a Maserati Ghibli fitted with 1A and 2A tires inflated to 2.5 bar.

The test made it possible to evaluate the systems under very high mechanical stress conditions (load, speed and cornering), which resulted in an increase in the final temperature of the sidewall up to approximately 60°C (outside ambient temperature 28°C).

At the end of the test, the covers were examined to check for defects on the decorative elements (separations, cracks, discolouration) and the results are summarized in the following Table 6.

Table 6

Tire disconnections Cracking Color change 1A No No No 2A No No No

All tested tires successfully passed the test without any appreciable damage to the decorative elements.

The trims at the end of the test had dirty black streaks as a result of the tires running over the curbs, but a heptane solvent cleaning treatment returned the trims back to their original appearance with no signs of change or discoloration. On FIG. 4 illustrates the mapping for a tire before and after a cleaning operation.

Claims (41)

1. Tire containing: a frame structure including at least a frame layer having opposite side edges associated with respective side structures; - tread bracelet applied in a radially external position relative to the frame structure; - a pair of sidewalls applied on the sides on opposite sides relative to the frame structure; And - at least one painted decorative element, having a thickness of 200 µm to 800 µm, and applied to at least one side of said pair of sidewalls, wherein said pair of sidewalls comprises an elastomeric composition comprising (i) at least one diene elastomeric polymer and (ii) an ozone protection system, wherein said at least one decorative element is made of a crosslinkable elastomeric composition containing: (i) 100 wt. parts of an elastomeric polymer containing from 30 to 70 wt. parts of natural and/or synthetic isoprene rubber and from 30 to 70 wt. parts of rubber selected from the group consisting of butyl rubber, halobutyl rubber, butadiene rubber, styrene-butadiene rubber and mixtures thereof, (ii) from 5 to 120 wt. parts of at least one reinforcing filler, (iii) optionally at least 0.5 wt. parts of at least one coloring agent and (iv) an optional non-staining ozone protection system, wherein said at least one decorative element is directly applied green or partially cured to said at least one sidewall of said pair of green tire sidewalls and co-vulcanized with the green tire. 2. The tire of claim 1, wherein said pair of sidewalls comprises an elastomeric composition comprising at least one diene elastomeric polymer and a non-staining ozone protection system. 3. Tire according to claim 1 or 2, wherein the non-staining ozone protection system is substantially free of antioxidants and/or aromatic amine anti-ozone agents. 4. The tire according to claim 3, wherein the aromatic amine antioxidants and/or anti-ozone agents are selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (DMBPPD), N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD) or N-(1,3-dimethylbutyl)-N'-phenylphenylenediamine (6PPD). 5. Tire according to any one of paragraphs. 2-4, wherein the non-staining ozone protection system is substantially free of (i) waxes and/or (ii) other polymeric static protection agents. 6. Tire according to any one of paragraphs. 2-5, in which the non-staining ozone protection system essentially consists of at least one phenolic antioxidant in an amount equal to or greater than 3 wt. parts, preferably equal to or greater than 4 wt. parts, and/or at least one antioxidant based on cyclic acetal or enol simple ether in an amount equal to or greater than 1 wt. part, preferably equal to or greater than 2 wt. parts. 7. Tire according to any one of paragraphs. 2-6, in which the colored decorative element is made of a crosslinkable elastomeric composition containing 100 wt. parts of an elastomeric polymer containing from 40 wt. parts up to 60 wt. parts, more preferably in an amount of approximately 50 wt. parts, natural and/or synthetic isoprene rubber. 8. Tire according to any one of paragraphs. 2-6, in which the colored decorative element is made of a crosslinkable elastomeric composition containing 100 wt. parts of an elastomeric polymer containing from 40 wt. parts up to 60 wt. parts, more preferably in an amount of approximately 50 wt. parts, butyl and/or halobutyl rubber. 9. Tire according to any one of paragraphs. 1-7, in which the colored decorative element is made from a crosslinkable elastomeric composition containing 100 wt. parts of an elastomeric polymer containing from 40 wt. parts up to 60 wt. parts, more preferably in an amount of approximately 50 wt. parts, butadiene and/or styrene-butadiene rubber. 10. Tire according to any one of paragraphs. 1-7, in which the colored decorative element is made from a crosslinkable elastomeric composition containing 100 wt. parts of an elastomeric polymer containing from 40 wt. parts up to 60 wt. parts, more preferably in an amount of approximately 50 wt. parts, a mixture of butyl or halobutyl rubber and butadiene and/or styrene-butadiene rubber. 11. Tire according to any one of paragraphs. 2-10, in which the colored decorative element is made of a crosslinkable elastomeric composition containing 100 wt. parts of the elastomeric polymer, from 5 to 120 wt. parts of at least one light reinforcing filler. 12. The tire of claim 11 wherein said at least one light reinforcing filler is selected from the group consisting of silica, alumina, titanium dioxide, aluminosilicates, bentonite, calcium carbonate, kaolin, talc, gypsum, barium sulfate, or mixtures thereof. 13. The tire according to claim 11 or 12, in which the colored decorative element is made of a crosslinkable elastomeric composition containing 100 wt. parts of an elastomeric polymer, an amount less than or equal to 100 wt. parts of at least one coloring agent. 14. Tire according to any one of paragraphs. 11-13, in which the colored decorative element is made of a crosslinkable elastomeric composition containing 100 wt. parts of the elastomeric polymer, from 1 to 5 wt. parts of carbon black. 15. Tire according to any one of paragraphs. 1-10, in which the colored decorative element is made from a crosslinkable elastomeric composition containing 100 wt. parts of the elastomeric polymer, from 5 to 120 wt. parts of at least one dark reinforcing filler. 16. The tire of claim 15 wherein the dark reinforcing filler is carbon black. 17. The tire according to claim 15 or 16, wherein the colored decorative element is formed with at least one layer of rubber-based printing ink. 18. The tire of claim 17, wherein the rubber-based ink layer has a thickness equal to or greater than 5 microns, preferably equal to or greater than 10 microns, even more preferably equal to or greater than 15 microns. 19. The tire according to claim 17 or 18, wherein the rubber-based ink layer has a thickness equal to or less than 50 microns, preferably equal to or less than 40 microns, more preferably equal to or less than 30 microns. 20. Tire according to any one of paragraphs. 17-19, in which the rubber-based ink contains a dye or pigment dispersed in a polymer base containing rubber selected from the group consisting of natural and/or synthetic rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, halobutyl rubber, and mixtures thereof. 21. Tire according to any one of paragraphs. 1-20, in which the decorative element has a thickness equal to or greater than 250 microns, preferably equal to or greater than 300 microns. 22. Tire according to any one of paragraphs. 1-21, in which the decorative element has a thickness equal to or less than 600 microns, preferably equal to or less than 500 microns. 23. A method for manufacturing a tire according to claim 1, in which: carry out the assembly of green tires, introducing the green tire into the tire curing apparatus, carrying out the deposition of at least one layer of a crosslinkable elastomeric composition on a plastic carrier, optionally, partial pre-vulcanization of said at least one layer is carried out and profiling of said at least one layer is carried out to remove part of it, applying said at least one layer to the side wall of the mold of the vulcanizing device in accordance with the sidewall of the green tire, closing the tire curing apparatus upon bringing said at least one layer into contact with said side wall, and jointly vulcanizing the green tire and said layer.