COMPOSITE MATERIAL AS ABRASION PROTECTION FOR VEHICLE TIRES AND METHOD FOR MANUFACTURING THE SAME

Description

[0001] The invention relates to a method for producing a vulcanizable composite material and a method based thereon for producing a vulcanized composite material or a vehicle tire, as well as a corresponding vulcanizable composite material and a vulcanized composite material or a corresponding vehicle tire that can be produced therefrom.

[0002] The subject matter of the invention is defined in the appended claims.

[0003] It is well known that vehicle tires, such as bicycle tires, incorporate textile reinforcements in various components. Other technical rubber articles, such as belts, straps, and hoses, also often incorporate reinforcements. These reinforcements are typically surrounded by at least one rubber compound, which is also referred to as a rubber lining compound or, in the vulcanized state, as a rubber lining.

[0004] One application for such composite materials, which is particularly important for certain bicycle tires, such as mountain bike tires, is as abrasion protection, i.e., as a protective material layer in the sidewall area of ​​vehicle tires or as rim protection in the area of ​​the so-called "nettle" (or "nettle"). In composite materials used as abrasion protection, the textile reinforcements, some of which are used in the form of woven fabrics, are usually located on the surface of the composite materials and are only partially surrounded by the rubber coating, so that the textile reinforcements are exposed on the surface and cover the underlying rubber materials as a protective layer.

[0005] In the prior art, the textile reinforcements are usually arranged on the surface of a cross-linkable rubber compound during the production of corresponding composite materials. During subsequent vulcanization, the rubber compound is then usually pressed outward against the textile reinforcements in the vulcanization mold, so that the textile reinforcements are partially embedded in the rubber coating in the resulting vulcanized composite material.

[0006] One common problem is that the reinforcements and the surrounding rubber coating usually have different mechanical properties, particularly different strengths. Especially under continuous mechanical and dynamic stress, such as that encountered during vehicle tire operation, sufficient adhesion between the reinforcements and the surrounding rubber coating is necessary to ensure adequate bond strength.

[0007] In the prior art, it is known to activate the reinforcements before rubberizing to ensure sufficient adhesion (so-called adhesion activation or adhesion activation), whereby so-called RFL dips (short for resorcinol formaldehyde latex) are usually used, which can be applied, for example, with a squeegee.

[0008] However, a disadvantage of this form of adhesion activation is often the strong inherent coloration of the RFL dips known from the prior art. This mostly reddish-brown color also limits the possibilities for subsequent coloring with dyes. This disadvantage is particularly serious when used for abrasion protection, since the textile reinforcements on the surface are, as intended, at least partially visible. Furthermore, this adhesion activation often masks the coloration of the textile reinforcements, even though this could be very informative for the expert, particularly for identifying the materials used based on their coloration or for detecting any manufacturer-specific markings, such as tracer threads.In order to compensate for this disadvantage and to achieve a design that is acceptable to the end customer, more complex manufacturing processes are often necessary in the state of the art, in which the textile reinforcements are only coated on the side intended for connection to the rubber coating.

[0009] With the composite materials known from the state of the art for chafing protection, it is sometimes perceived as a disadvantage that the rubber coating partially surrounding the textile reinforcements can make it significantly more difficult to check the correct positioning of the textile reinforcements and to reliably determine their condition during use in driving conditions. The latter, in particular, is often perceived as a disadvantage because the textile reinforcements of the chafing protection are subjected to heavy loads by their intended use and are therefore susceptible to wear.

[0010] JPS 60139876 A relates to a process for coloring and improving the adhesion of reinforcing materials for translucent or transparent rubber compounds for use in tires.

[0011] It was the primary object of the present invention to eliminate or at least reduce the disadvantages of the prior art described above.

[0012] It was therefore an object of the present invention to provide a process for producing vulcanizable composite materials from which, by vulcanization, high-performance vulcanized composite materials can be obtained that are particularly suitable for use as abrasion protection in vehicle tires. The process to be specified should be particularly time- and cost-efficient and preferably feasible without complex processing steps, such as one-sided adhesion activation.

[0013] It was an object of the present invention that the vulcanized composite materials should enable the textile reinforcements contained in the vulcanized composite materials to be identified and quality-tested as easily, reliably and non-destructively as possible, whereby in particular a clear differentiation from adjacent textile reinforcements should also be possible, so that in particular an assessment of the state of wear of the textile reinforcements in those areas covered by the rubber coating should also be possible.

[0014] A further objective of the present invention was to provide the vulcanized composite materials with increased flexibility in terms of color design compared to the prior art. It was particularly desirable that the base color of the textile reinforcements remain visible despite any adhesion-activating coatings, particularly to enable color-based material identification and to make manufacturer-specific tracer threads visible.

[0015] An additional object of the present invention was that the vulcanized composite materials should exhibit sufficiently high bond strength, particularly between the textile reinforcements and the rubber coating. A further object of the present invention was that the positive color properties, unlike, for example, RFL dips, should be adjustable largely independently of the conditions used during vulcanization.

[0016] It will be apparent to those skilled in the art that a supplementary object of the present invention was also to provide a method for producing a vehicle tire and a corresponding vehicle tire. A supplementary object of the present invention was that the corresponding vehicle tires should ideally contribute to driving safety.

[0017] The inventors of the present invention have now recognized that at least some of the objects stated above can be achieved if a rubber coating is used which is at least partially transparent to visible light, so that the parts of the textile reinforcements covered by the rubber coating are also visible from the outside and can be assessed, for example, with regard to possible signs of wear.

[0018] However, it has proven to be disadvantageous with this procedure that the unfavorable color properties of the RFL dips are particularly pronounced here, whereby even a merely partial adhesion activation in this fundamentally advantageous embodiment cannot prevent the unfavorable coloring of the RFL dip from being visible.

[0019] The inventors of the present invention have now recognized that the objects defined above can be achieved if a specific form of adhesion activation is used as defined in the claims.

[0020] The above-mentioned objects are thus achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following statements.

[0021] Such embodiments, which are referred to below as preferred, are combined in particularly preferred embodiments with features of other embodiments referred to as preferred. Combinations of two or more of the embodiments referred to below as particularly preferred are therefore very particularly preferred. Likewise preferred are embodiments in which a feature of an embodiment referred to as preferred to any extent is combined with one or more further features of other embodiments referred to as preferred to any extent. Features of preferred vulcanizable composite materials, vulcanized composite materials, and vehicle tires result from the features of preferred processes.

[0022] The invention relates to a method for producing a vulcanizable composite material according to claim 1, comprising the steps: a) producing or providing a textile reinforcement, b) treating the textile reinforcement with an aqueous dispersion to activate the adhesion of the textile reinforcement and to obtain an adhesion-activated textile reinforcement, and c) arranging the adhesion-activated textile reinforcement on the surface of a base material comprising a crosslinkable rubberizing mixture to obtain the vulcanizable composite material, wherein the aqueous dispersion is substantially free of free resorcinol and resorcinol precondensates, in particular resorcinol-formaldehyde precondensates, and is free of free formaldehyde and formaldehyde-releasing substances, wherein the crosslinkable rubberizing mixture can be processed by vulcanization to form a crosslinked rubberizing mixture which is at least partially transparent to visible light, at least in sections.

[0023] The process according to the invention produces vulcanizable composite materials from which, by means of vulcanization, high-performance vulcanized composite materials with excellent bond strength can be obtained, which are ideally suited as abrasion protection for vehicle tires. In the vulcanized composite materials, the specifically selected adhesion activation advantageously makes it possible to inspect the parts of the textile reinforcements covered by the rubber coating from the outside, thus enabling reliable and non-destructive quality testing, which can also be performed by laypersons.

[0024] In a synergistic way, the selected adhesion activation surprisingly does not cause any unwanted coloring, as this can advantageously be colorless or transparent. This makes it possible to recognize the original coloring of the textile reinforcements, whereby, for example, information about the materials used in the textile reinforcements and / or manufacturer's specifications, e.g. through tracer threads, remains visible. This also makes it possible to significantly increase flexibility with regard to color design, since advantageously not only the rubber coating can be colored, but coloring of the textile reinforcements is just as possible as coloring of the adhesion-activating coating. It can be seen as an advantage of the invention that the positive color properties can be maintained largely independently of the temperatures used during vulcanization.

[0025] The advantages described above also make it possible to produce a corresponding abrasion protection more efficiently, since this process does not require the adhesion activation to be carried out selectively on one side of the textile reinforcements.

[0026] Finally, one advantage of the process according to the invention is that, due to the type of adhesion activation, the textile reinforcements in the vulcanized composite materials exhibit a slight sheen, which, depending on the chosen coloring, can tend toward a metallic sheen. By using a corresponding composite material instead of a conventional abrasion protection with a largely absorbent, black rubber material, this sheen increases the tire's visibility, especially in poor visibility conditions, as, for example, a higher proportion of incident headlight light can be reflected.

[0027] The definition of the crosslinkable rubber compound based on the properties of the rubber coating produced from it by vulcanization, i.e., the crosslinked rubber compound, is consistent with industry practice and expert understanding, since such a definition is generally the only practical way to define the corresponding material for corresponding polymeric materials whose structure cannot be precisely described. Accordingly, a vulcanized composite material produced from the vulcanizable composite material comprises a crosslinked rubber compound that is at least partially transparent to visible light, at least in sections.

[0028] In the context of the present invention, the expression "at least partially transparent to visible light" means, in accordance with the expert understanding, that the crosslinked rubber coating mixture exhibits so little interaction with electromagnetic radiation of a wavelength in the visible range, or a portion of the wavelengths in the visible range, that the textile reinforcements in the vulcanizable composite material and the vulcanized composite material are visible from the outside. This means that it is not necessary for the crosslinked rubber coating mixture to exhibit no absorption at all in the visible wavelength range, since even partial absorption, for example at certain wavelengths, can be tolerated, particularly in the case of transparent colored rubber coatings.

[0029] According to the above definition, the crosslinked rubber coating mixture is at least partially transparent to visible light, at least in certain sections. This means that the vulcanizable composite material or the vulcanized composite material can also include sections in which the rubber coating is not transparent, for example, in the form of alternating regions under the textile reinforcements.

[0030] The term "essentially free of" is to be understood, in accordance with the expert understanding within the scope of the present invention, to mean that the corresponding substances may only be present in amounts that do not significantly affect the essential properties of the claimed composition. For example, the amount of these substances must not exceed trace amounts resulting from contamination. Typically, the aqueous dispersion to be used according to the invention should contain no more than 0.1% by weight (dry weight of the aqueous dispersion), based on the total weight of the aqueous dispersion, of each of the specified components, such as resorcinol, resorcinol precondensates, formaldehyde, and formaldehyde-releasing substances; i.e., 0.1% by weight is the maximum amount for each of the above components. The content of all of these components in the aqueous dispersion is preferably 0% by weight.

[0031] The term phr (parts per hundred parts of rubber by weight) used in the present invention is the standard quantity used in the rubber industry for compound formulations. The dosage of the parts by weight of the individual substances is always based on 100 parts by weight of the total mass of all rubbers present in the compound, which adds up to 100.

[0032] In principle, a method according to the invention is preferred, wherein the adhesion-activated textile reinforcement is arranged on the surface of the base material in such a way that the adhesion-activated textile reinforcement is partially surrounded by the crosslinkable rubberizing mixture.

[0033] Particularly for applications with high expected loads, a method according to the invention is preferred, wherein the textile reinforcement arranged on the surface of the base material and / or the surface of the base material are coated with a coating material, wherein the coating material comprises one or more fillers selected from the group consisting of ceramic hard materials, glasses and glass-like materials, preferably ceramic hard materials, wherein the mass fraction of fillers in the coating material is preferably 5 to 10%, based on the mass of the coating material, wherein the coating material preferably comprises binders based on at least one vulcanizable polymer, particularly preferably polyisoprene, polybutadiene, styrene-butadiene rubber or natural rubber, very particularly preferably a binder based on polyurethane.

[0034] The process according to the invention is advantageously suitable for all textile reinforcements known to those skilled in the art. However, the inventors of the present invention were able to identify features of the textile reinforcement that are particularly suitable for the process according to the invention.

[0035] A method according to the invention is preferred, wherein the textile reinforcement is at least partially dyed and / or comprises at least one tracer thread, preferably at least one tracer thread. In this embodiment, the advantages of the method according to the invention are particularly evident.

[0036] A method according to the invention is also preferred, wherein the textile reinforcement comprises a material selected from the group consisting of polyesters, polyamides, polyurethanes, glass, carbon, celluloses, polycarbonates, polyketones and combinations of these materials, preferably selected from the group consisting of polyesters, regenerated cellulose, in particular rayon, aramids, nylon and combinations of these materials, particularly preferably selected from the group consisting of nylon, wherein the textile reinforcement most particularly preferably consists of these materials. Suitable polyesters include, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene furanoate (PEF) and polyester polyacrylates, which are offered, for example, by Celanese AG under the trade name Vectran. Examples of polyamides are nylon 4,6 (PA 4.6), nylon 4,10 (PA 4.10), Nylon 6 (PA 6), Nylon 6,6 (PA 6.6 polyhexamethylene adipamide), Nylon 6,12 (PA 6.12), Nylon 10,10 (PA 10.10), and Nylon 12,12 (PA 12.12). Suitable polyamides include, for example, aromatic polyamides such as aramids, especially m-aramid, p-aramid, and blends of m-aramid and p-aramid. Suitable celluloses include, for example, regenerated celluloses (especially viscose or rayon) and cellulose esters.

[0037] A method according to the invention is also preferred, wherein the textile reinforcement comprises one or more reinforcing cords, preferably in the form of a woven fabric, each of which comprises at least one yarn. For example, the textile reinforcement material can be in the form of single- or multi-thread textile cords or in the form of flat thread structures such as ribbons based on single- or multi-thread yarns.

[0038] Against this background, a method according to the invention is preferred, wherein the textile strength member comprises one or more reinforcing cords, preferably in the form of a woven fabric, each of which comprises at least two different yarns, wherein the yarns each preferably consist of a material selected from the group consisting of polyesters, polyamides, polyurethanes, glass, carbon, celluloses, polycarbonates and polyketones.

[0039] In principle, a method according to the invention is preferred, wherein at least one of the yarns, preferably all of the yarns, in the reinforcing cords has a fineness in the range from 90 to 5000 dtex, preferably in the range from 100 to 2500 dtex or in the range from 2500 to 4500 dtex, particularly preferably in the range from 200 to 1500 dtex or in the range from 3000 to 4000 dtex.

[0040] A method according to the invention is also preferred, wherein at least one of the yarns, preferably all of the yarns, in the reinforcing cords are twisted at 100 to 600 T / m, preferably at 150 to 550 T / m, particularly preferably at 200 to 500 T / m.

[0041] In principle, a method according to the invention is also preferred, wherein the polyamide yarn has a twist factor in the range of 100 to 400, preferably in the range of 150 to 350. The twist factor α is a value known to those skilled in the art and is calculated from the twist level in T / m ("turns per meter") and the fineness in tex: α = T / m tex 1000

[0042] In principle, a method according to the invention is also preferred, wherein at least one of the reinforcing cords, preferably all of the reinforcing cords, comprises two or more yarns, wherein the yarns in the reinforcing cord are end-twisted with one another preferably at 100 to 600 T / m, particularly preferably at 150 to 550 T / m, very particularly preferably at 200 to 500 T / m.

[0043] In principle, a method according to the invention is also preferred, wherein at least one of the reinforcing cords, preferably all of the reinforcing cords, has a total fineness in the range from 180 to 10,000 dtex, preferably in the range from 200 to 7,500 dtex, particularly preferably in the range from 400 to 5,000 dtex.

[0044] It will be understood by those skilled in the art that the process according to the invention can also process multiple reinforcements and incorporate them into a corresponding vulcanizable composite material. For the vast majority of cases, such a process is even preferred. Accordingly, a process according to the invention is preferred, wherein the process is carried out for two or more textile reinforcements.

[0045] The production of vulcanizable rubber compounds which, after vulcanization, result in translucent, in particular transparent, vulcanized rubber compounds is known to the person skilled in the art in principle from the prior art, for example from DE 8234954 U1, US 6624220 B1 and US 2004 / 0044118 A1, so that the person skilled in the art can base their production on the prior art.

[0046] As described above, it is possible to make only parts of the rubber coating translucent, for example by having the crosslinkable rubber coating mixture consist of several partial rubber coating mixtures. Even if this may be preferred precisely with regard to the optical effect, in most cases, due to the simpler production, such rubber coatings are preferred that are essentially translucent in their entirety. Thus, a method according to the invention is preferred, wherein the crosslinkable rubber coating mixture comprises two or more separate partial rubber coating mixtures, wherein at least one partial rubber coating mixture can be processed by vulcanization to form a crosslinked partial rubber coating mixture that is at least partially translucent to visible light.Alternatively, a method according to the invention is preferred, wherein the crosslinkable rubberizing mixture can be processed by vulcanization to form a crosslinked rubberizing mixture which is essentially at least partially transparent to visible light in its entirety.

[0047] With regard to the relevant wavelength ranges in which the rubber coating should be translucent, a suitable range can be defined, wherein it is particularly preferred if the rubber coating essentially does not scatter diffusely, so that it is transparent. A method according to the invention is therefore preferred, wherein the crosslinkable rubber coating mixture can be processed by vulcanization to form a crosslinked rubber coating mixture which is at least partially transparent to visible light with a wavelength in the range from 380 to 780 nm, at least in sections, preferably essentially in its entirety. A method according to the invention is also preferred, wherein the crosslinkable rubber coating mixture can be processed by vulcanization to form a crosslinked rubber coating mixture which is at least partially transparent to visible light, at least in sections, preferably essentially in its entirety.

[0048] The inventors of the present invention were able to identify particularly suitable compositions for the crosslinkable rubber coating mixture.

[0049] A process according to the invention is preferred, wherein the crosslinkable rubberizing mixture comprises at least one diene rubber, wherein the diene rubber is preferably selected from the group consisting of halogenated copolymers of a C4 to C7 isoolefin and an alkylstyrene, natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber, butyl rubber, nitrile rubber (NBR), chloroprene rubber, isoprene-butadiene rubber and ethylene-propylene rubber, wherein the diene rubber is particularly preferably selected from the group consisting of brominated copolymers of isobutylene and para-methylstyrene, natural polyisoprene, synthetic polyisoprene and cis-1,4-butadiene rubber. For example, the polyisoprene (IR, NR) can be either cis-1,4-polyisoprene or 3,4-polyisoprene. However, cis-1,4-polyisoprenes with a cis-1,4 content of > 90 wt.% are preferred.For example, it is possible to obtain such a polyisoprene by stereospecific polymerization in solution with Ziegler-Natta catalysts or using finely divided lithium alkyl compounds. Furthermore, natural rubber (NR) is such a cis-1,4-polyisoprene; the cis-1,4 content in natural rubber is greater than 99 wt.%.

[0050] The polybutadiene (BR) can be, for example, cis-1,4-polybutadiene or vinylpolybutadiene (vinyl content approximately 10 to 90 wt.%). Cis-1,4-polybutadiene with a cis-1,4-content greater than 90 wt.% is preferred, which can be produced, for example, by solution polymerization in the presence of rare earth catalysts.

[0051] The styrene-butadiene copolymers (SBR) can, for example, be solution-polymerized styrene-butadiene copolymers (S-SBR) with a styrene content, based on the polymer, of approximately 10 to 45 wt.% and a vinyl content (i.e., content of 1,2-bonded butadiene, based on the total polymer) of 10 to 70 wt.%, which can be produced, for example, using lithium alkyls in organic solvents. The S-SBR can also be coupled and end-group modified. Alternatively, emulsion-polymerized styrene-butadiene copolymers (E-SBR) and mixtures of E-SBR and S-SBR can be used. The styrene content of the E-SBR is approximately 15 to 50 wt.%; for example, the products known from the prior art obtained by copolymerizing styrene and 1,3-butadiene in an aqueous emulsion can be used.

[0052] For example, the halogenated copolymer of a C4 to C7 isoolefin and an alkylstyrene can consist of an isobutylene and a methylstyrene, where the styrene unit can be ortho-, meta-, or para-alkylated. The copolymer can be halogenated with any halogen. Preference is given to using a brominated copolymer of isobutylene and para-methylstyrene. The diene rubbers used in the mixture, in particular styrene-butadiene copolymers, can also be partially or fully functionalized. The functionalization can be carried out with groups that can interact with the fillers used, in particular with fillers bearing OH groups. Functionalizations can be, for example, those with hydroxyl groups and / or epoxy groups and / or siloxane groups and / or amino groups and / or phthalocyanine groups and / or carboxyl groups and / or silane sulfide groups.

[0053] In this respect, a process according to the invention is preferred, wherein the crosslinkable rubberizing mixture comprises 25 to 100 phr, preferably 50 to 100 phr, particularly preferably 70 to 100 phr of the at least one diene rubber.

[0054] A process according to the invention is also preferred, wherein the crosslinkable rubberizing mixture comprises 15 to 50 phr of a brominated copolymer of isobutylene and para-methylstyrene and / or 25 to 85 phr of natural and / or synthetic polyisoprene and / or 15 to 50 phr of cis-1,4-butadiene rubber.

[0055] Also preferred is a process according to the invention wherein the crosslinkable rubberizing mixture comprises 10 to 90 phr, preferably 15 to 40 phr, of a filler, preferably amorphous silicon dioxide, in particular precipitated silica, wherein the crosslinkable rubberizing mixture very particularly preferably comprises a polar filler, in particular amorphous silicon dioxide, and one or more silane compounds for binding the polar fillers. The filler can be any suitable material known in the art for use as a filler or a mixture of these materials. The rubberizing mixture preferably comprises silica as a filler, which is referred to in the art as amorphous silicon dioxide. This can be the silicas customary for tire rubber mixtures.It is particularly preferred to use a finely dispersed, precipitated silica having a CTAB surface area (according to ASTM D 3765) of 30 to 350 m² / g, preferably 120 to 250 m² / g. Suitable silicas include, for example, conventional silica such as type VN3 (trade name) from Evonik, as well as highly dispersible silicas, so-called HD silicas (e.g., Ultrasil 7000 from Evonik).

[0056] For some applications, a process according to the invention is preferred, wherein the crosslinkable rubberizing mixture additionally comprises 0.1 to 10 phr of further fillers, wherein the further fillers are selected from the group consisting of aluminosilicates, chalk, starch, magnesium oxide, titanium dioxide, rubber gels, and combinations of these fillers. Alternatively, a process according to the invention is preferred, wherein the crosslinkable rubberizing mixture comprises less than 0.005 phr, preferably less than 0.001 phr, of the further fillers.

[0057] To obtain filler-containing, translucent rubber coatings, it is generally desirable to keep the content of black pigments and other colorants as low as possible. Therefore, a process according to the invention is preferred, wherein the crosslinkable rubber coating mixture comprises less than 1 phr, preferably less than 0.1 phr, particularly preferably less than 0.01 phr of black colorants, in particular black pigments, in particular carbon black, graphene, or carbon nanotubes, as filler.

[0058] Vulcanization of the crosslinkable rubber compound is usually carried out in the presence of sulfur and / or sulfur donors, whereby some sulfur donors can also act as vulcanization accelerators. Sulfur or sulfur donors are added to the rubber compound in the final mixing step in amounts customary among those skilled in the art (0.4 to 8 phr, sulfur preferably in amounts of 0.4 to 4 phr). Vulcanization can also take place in the presence of very small amounts of sulfur in combination with sulfur-donating substances. Furthermore, the rubber compound can contain vulcanization-influencing substances such as vulcanization accelerators, vulcanization retarders, and vulcanization activators in customary amounts to control the required time and / or temperature of vulcanization and to improve the vulcanization properties.The vulcanization accelerators can be selected, for example, from the following accelerator groups: thiazole accelerators such as 2-mercaptobenzothiazole, sulfenamide accelerators such as benzothiazyl-2-cyclohexylsulfenamide (CBS), guanidine accelerators such as N,N'-diphenylguanidine (DPG), dithiocarbamate accelerators such as zinc dibenzyldithiocarbamate, disulfides, and thiophosphates. These accelerators can also be used in combination, which can result in synergistic effects. Against this background, a process according to the invention is preferred, wherein the crosslinkable rubberizing mixture comprises 0.4 to 8.0 phr, preferably 0.4 to 4 phr, particularly preferably 0.5 to 2.5 phr, of sulfur, wherein the crosslinkable rubberizing mixture preferably comprises one or more further vulcanization additives selected from the group consisting of vulcanization accelerators, vulcanization retarders and vulcanization activators.

[0059] A process according to the invention is also preferred, wherein the crosslinkable rubberizing mixture comprises one or more additives selected from the group consisting of coupling agents, in particular silane coupling agents, plasticizers, anti-aging agents, activators, waxes, tackifier resins, mastication aids, and processing aids. Suitable plasticizers include all plasticizers known to the person skilled in the art, for example aromatic, naphthenic, or paraffinic mineral oil plasticizers, such as MES (mild extraction solvate) or TDAE (treated distillate aromatic extract), or rubber-to-liquid oils (RTL), gas-to-liquid oils (GTL), or biomass-to-liquid oils (BTL; as disclosed in DE 10 2008 037 714 A1), or oils based on renewable raw materials, such as rapeseed oil, terpene oils (e.g.Orange oils) or factices or plasticizer resins or liquid polymers (such as liquid BR) whose average molecular weight (determined by GPC = gel permeation chromatography, based on BS ISO 11344:2004) is between 500 and 20,000 g / mol. If liquid polymers are used as plasticizers in the rubberizing mixture, they are not included as rubber in the calculation of the composition of the polymer matrix (phr calculation). When mineral oil is used, white oils are particularly preferred. Examples of anti-aging agents include substances such as N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ). Zinc oxide, zinc carbonate, and fatty acids (e.g., stearic acid) are used as activators. An example of a mastication aid is 2,2'-dibenzamidodiphenyl disulfide (DBD).Processing aids include fatty acid salts, such as zinc soaps, and fatty acid esters and their derivatives, such as PEG carboxylic acid esters.

[0060] Particularly appealing optical effects can be achieved if the crosslinkable rubberizing mixture is colored translucent, especially colored transparent, i.e., exhibits non-uniform absorption behavior in the visible spectrum of light, which can be achieved by dyes. Therefore, a process according to the invention is preferred, wherein the crosslinkable rubberizing mixture comprises one or more dyes.

[0061] Particularly suitable as aqueous dispersions for adhesion activation are those systems which are disclosed, for example, in WO 2019 / 015792 A1 as well as EP 3702521 A1, EP 3702522 A1 and EP 3702523 A1.

[0062] In principle, a process according to the invention is preferred in which the aqueous dispersion comprises: (w1) at least one rubber latex, with the proviso that this rubber latex is not a polyisoprene rubber latex (including synthetic and natural polyisoprene rubber latex), and (w2) at least one protected isocyanate, and (w3) at least one filler and / or at least one polymer with carboxylic acid functional groups and / or at least one polyisoprene rubber (including synthetic and natural polyisoprene rubber latex) and / or at least one wax.

[0063] A suitable rubber latex is VP latex, for example. VP latex is known to those skilled in the art. "VP" stands for "vinyl pyridine," whereby known VP latexes can also comprise additional monomers. A preferred example of a VP latex is a vinyl pyridine latex, which typically comprises 15% vinyl pyridine, 15% styrene, and 70% butadiene monomers. In addition to the VP latex, the aqueous dispersion can comprise one or more additional latexes, such as a styrene-butadiene latex (SBR) and natural rubber latex (NR).

[0064] For isoprene rubber, the use of natural latex with a high ammonia content, which comes from the "Hevea Brasiliensis" tree, is preferred.

[0065] Suitable polyisocyanate compounds as components of baths / dips for textile reinforcements are generally known to those skilled in the art. The polyisocyanate compound can be blocked with another compound or present as a dimer or higher homolog, i.e., "self-blocked." Blocked polyisocyanates are obtained, for example and preferably, by blocking free isocyanates with at least one substance selected from the group consisting of phenol, thiophenol, chlorophenol, cresol, resorcinol, p-sec-butylphenol, p-tert-butylphenol, p-sec-amylphenol, p-octylphenol, p-nonylphenol, tert-butyl alcohol, diphenylamine, dimethylaniline, phthalimide, δ-valerolactam, ε-caprolactam, dialkyl malonate, acetylacetone, alkyl acetoacetate, acetoxime, methyl ethyl ketoxime, 3,5-dimethylpyrazole, cyclohexanone oxime, 3-hydroxypyridine and acidic sodium sulfite.It is preferred in the context of the present invention that the polyisocyanate compound comprises building blocks which are selected from the group consisting of tetramethylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, aromatic diisocyanates comprising 2,4- or 2,6-toluene diisocyanate, tetramethylxylene diisocyanate, p-xylene diisocyanate, 2,4'- or 4,4'-diisocyanatodiphenylmethane, 1,3- or 1,4-phenyl diisocyanate.

[0066] The polycarboxylic acid is based, for example, to an extent of 10 to 100 mol%, preferably to an extent of 30 to 100 mol%, particularly preferably to an extent of 50 to 100 mol%, very particularly preferably to an extent of 70 to 100 mol%, and especially preferably to an extent of 90 to 100 mol%, on monomers containing carboxylic acid groups. According to a particularly advantageous embodiment of the invention, the polycarboxylic acid is based to an extent of 100 mol% on monomers containing carboxylic acid groups, although further functional groups are not excluded. The polycarboxylic acid preferably has a weight-average molecular weight Mw according to GPC of 1,000 to 500,000 g / mol, preferably of 3,000 to 100,000 g / mol. The polycarboxylic acid is preferably based on acrylic acid, methacrylic acid, itaconic acid, crotonic acid, cinnamic acid, and / or maleic acid monomers. According to a preferred embodiment, the polycarboxylic acid (based on acrylic acid monomers) is an acrylic resin.

[0067] Suitable epoxy compounds as components of corresponding aqueous dispersions are generally known to those skilled in the art. Within the scope of the present invention, it is preferred that the epoxy compound is selected from the group consisting of glycidyl-based glycerol, sorbitol-based epoxy compounds, phenol-based novolak epoxy compounds, and cresol-based novolak epoxy compounds. A particularly suitable epoxy compound is, for example, a glycerol-based polyglycidyl ether, such as Denacol™ EX-313, which is described, inter alia, in DE 69722388 T2.

[0068] Possible waxes as components of corresponding aqueous dispersions are generally known to the person skilled in the art. Preferred examples are paraffinic waxes, microcrystalline waxes, synthetic waxes, and waxes from natural sources such as beeswax, which also include combinations of two or more waxes.

[0069] Water-dispersible inorganic fillers are particularly suitable as fillers for the aqueous dispersion. Amorphous silicon dioxide (especially precipitated silica) and silicates with a BET surface area (according to ISO 9277:2010) of 30 to 450 m² / g, preferably 120 to 410 m² / g, are particularly preferred.

[0070] The aqueous dispersion preferably has a pH of 5 to 11, preferably 7 to 11, which can conveniently be adjusted with a base. The base is preferably a volatile base, which or its constituents evaporate during the process. According to a particularly advantageous embodiment of the invention, the base is ammonium hydroxide, i.e., an aqueous solution of ammonia.

[0071] In light of the above, a process according to the invention is preferred, wherein the aqueous dispersion comprises: (x1) at least one rubber latex, preferably in a mass fraction of 4 to 60% based on the dry weight of the aqueous dispersion, and (x2) at least one protected isocyanate, preferably in a mass fraction of 0.1 to 10% based on the dry weight of the aqueous dispersion.

[0072] Also preferred is a process according to the invention, wherein the aqueous dispersion comprises: (y1) at least one compound containing an epoxy group, preferably in a mass fraction of up to 6% based on the dry weight of the aqueous dispersion, and / or (y2) at least one polymer having carboxylic acid functional groups, preferably in a mass fraction of up to 15% based on the dry weight of the aqueous dispersion.

[0073] Particularly preferred is a process according to the invention wherein the aqueous dispersion comprises one of the following components: (z1) at least one filler, preferably in a mass fraction of 0.02 to 20% based on the dry weight of the aqueous dispersion, preferably with the proviso that the aqueous dispersion does not comprise a polymer having carboxylic acid functional groups, or (z2) at least one polyisoprene rubber latex, preferably in a mass fraction of 1 to 20% based on the dry weight of the aqueous dispersion, preferably with the proviso that the aqueous dispersion comprises at least one rubber latex which is not a polyisoprene rubber latex, or (z3) at least one wax, preferably in a mass fraction of 0.3 to 30% based on the dry weight of the aqueous dispersion.

[0074] Among the possible aqueous dispersions for adhesion activation, three specific embodiments are, in the opinion of the inventors, particularly suitable.

[0075] On the one hand, a process according to the invention is preferred, wherein the aqueous dispersion comprises: (h1) at least one rubber latex, in a mass fraction of 4 to 50%, preferably 4.5 to 25%, based on the dry weight of the aqueous dispersion, (h2) at least one protected isocyanate, in a mass fraction of 0.1 to 4.5%, preferably 0.2 to 4%, based on the dry weight of the aqueous dispersion, (h3) at least one filler, in a mass fraction of 0.02 to 20%, preferably 0.3 to 15%, based on the dry weight of the aqueous dispersion.

[0076] Alternatively, a process according to the invention is preferred, wherein the aqueous dispersion comprises: (i1) at least one rubber latex, in a mass fraction of 4 to 50%, preferably 4.5 to 25%, based on the dry weight of the aqueous dispersion, (i2) at least one protected isocyanate, in a mass fraction of 0.1 to 10%, preferably 0.2 to 4.5%, based on the dry weight of the aqueous dispersion, (i3) at least one wax, in a mass fraction of 0.3 to 30%, preferably 0.5 to 15%, based on the dry weight of the aqueous dispersion.

[0077] Alternatively, a process according to the invention is preferred, wherein the aqueous dispersion comprises: (j1) at least one rubber latex, in a mass fraction of 4 to 40%, preferably 4.5 to 20%, based on the dry weight of the aqueous dispersion, wherein the rubber latex is not a polyisoprene rubber latex, (j2) at least one protected isocyanate, in a mass fraction of 0.1 to 10%, preferably 0.2 to 4.5%, based on the dry weight of the aqueous dispersion, (j3) at least one polyisoprene rubber latex, preferably in a mass fraction of 1 to 20%, preferably 2 to 15%, based on the dry weight of the aqueous dispersion.

[0078] By taking advantage of the advantageous lack of inherent coloration of the aqueous dispersion, the resulting adhesion promoter can be colored particularly easily. Therefore, a process according to the invention is preferred, wherein the aqueous dispersion comprises one or more pigments and / or dyes.

[0079] Even if another application method is possible, the aqueous dispersion is preferably applied as a dip, which is possible without any visual impairment due to the advantageous low inherent coloration despite the use as abrasion protection and despite the translucent rubber coating. Therefore, a method according to the invention is preferred, wherein the treatment in step b) comprises immersing the textile reinforcement in the aqueous dispersion, wherein the treatment preferably also comprises hot stretching the immersed textile reinforcement.

[0080] The vulcanizable composite materials produced by the method according to the invention can be incorporated into green vehicle tires, for example, into green bicycle tires. Therefore, a method according to the invention is also preferred, additionally comprising the step: d) producing an unvulcanized green vehicle tire, in particular an unvulcanized green bicycle tire, comprising the vulcanizable composite material.

[0081] The advantageous vulcanized composite materials or vehicle tires comprising these vulcanized composite materials can be produced by vulcanization from the unvulcanized vehicle tire blanks produced above, or in less preferred cases only from the unvulcanized composite materials. The invention therefore also relates to a method for producing a vehicle tire, in particular a bicycle tire, or a vulcanized composite material, comprising the steps of the method according to the invention for producing a vulcanizable composite material, and additionally at least one of the following steps: e) vulcanizing the vulcanizable composite material to obtain a vulcanized composite material, and / or f) vulcanizing the unvulcanized green vehicle tire to obtain a vehicle tire, wherein the vulcanization is carried out in such a way that the adhesion-activated textile reinforcement lies at least in sections on the surface of the vulcanized composite material and / or the vehicle tire, wherein the vulcanization is preferably carried out in such a way that the adhesion-activated textile reinforcement is partially surrounded by the crosslinked rubber mixture.

[0082] In this respect, a method according to the invention is preferred, wherein the vehicle tire is a bicycle tire, wherein the width of the tire casing transverse to the direction of rotation is preferably in the range from 20 to 70 mm, preferably in the range from 25 to 65 mm and / or wherein the inner diameter of the tire casing is preferably in the range from 340 to 640 mm, preferably in the range from 550 to 630 mm.

[0083] A method according to the invention is particularly preferred, wherein the vehicle tire comprises the vulcanized composite material as part of the sidewall, preferably as abrasion protection.

[0084] In light of the above explanations, it is clear to the person skilled in the art that the invention also relates to the vulcanizable composite material produced by the process according to the invention, the vulcanized composite material that can be produced therefrom and the corresponding vehicle tires, each of which results in the advantages discussed above.

[0085] According to claim 7, the invention thus also relates to a vulcanizable composite material for the production of vehicle tires, preferably produced or producible by the method according to the invention for producing a vulcanizable composite material, comprising: i) at least one textile reinforcement which is adhesively activated at least in sections, preferably substantially completely, with an aqueous dispersion, and ii) a base material comprising a crosslinkable rubber mixture, wherein the textile reinforcement is arranged on the surface of the base material, wherein the textile reinforcement is preferably partially surrounded by the crosslinkable rubberizing mixture, wherein the aqueous dispersion is substantially free of free resorcinol and resorcinol precondensates, in particular resorcinol-formaldehyde precondensates, and is free of free formaldehyde and formaldehyde-releasing substances, wherein the crosslinkable rubberizing mixture can be processed by vulcanization to form a crosslinked rubberizing mixture which is at least partially transparent to visible light, at least in sections.

[0086] Since the adhesion activation produced by means of the aqueous dispersion is a complex coating whose structure cannot inherently be described precisely, it is necessary to define the textile reinforcements used in the vulcanizable composite material according to the invention via the adhesion activation experienced.

[0087] The invention consequently also relates to a vulcanized composite material according to claim 8, in particular for use as abrasion protection in vehicle tires, produced or producible by vulcanization of the vulcanizable composite material according to the invention, preferably with the method according to the invention for producing a vulcanized composite material, comprising a crosslinked rubberizing mixture which is at least partially transparent to visible light, wherein the adhesion-activated textile reinforcement is at least partially located on the surface of the vulcanized composite material, wherein the adhesion-activated textile reinforcement is preferably partially surrounded by the crosslinked rubberizing mixture.

[0088] According to claim 9, the invention also relates to a vehicle tire, in particular a bicycle tire, comprising a vulcanized composite material according to the invention, preferably produced or producible using the method according to the invention for producing a vehicle tire. In this respect, a vehicle tire is preferred which comprises the vulcanized composite material in the region of the sidewall, preferably as the outermost layer, in particular as abrasion protection.

[0089] Also preferred is a vehicle tire, additionally comprising in the region of the vulcanized composite material one or more vulcanized rubber labels and / or a print, preferably one or more vulcanized rubber labels.

[0090] An exemplary embodiment of the method according to the invention is proposed below, which the inventors believe to be a particularly advantageous embodiment. Furthermore, a bicycle tire according to the invention produced using this exemplary method is proposed, which comprises a vulcanized composite material according to the invention as abrasion protection and which, according to the inventors' assessment, is also a particularly advantageous embodiment of a vehicle tire according to the invention, in which the advantages of the present invention are particularly evident.

[0091] Within the scope of the exemplary method, a textile reinforcement member is provided, which is a woven fabric composed of several reinforcement cords. The reinforcement cords each comprise an aramid yarn with a fineness of 420 dtex and a nylon yarn with a fineness of 470 dtex, which are end-twisted together at 320 T / m. The aramid yarn used is yellowish in color, whereas the nylon yarn has a manufacturer-specific identification marking.

[0092] The textile reinforcement is bonded to an aqueous dispersion using a dipping process and then processed by hot stretching. The aqueous dispersion contains neither free resorcinol or resorcinol precondensates nor free formaldehyde or formaldehyde-releasing substances. The aqueous dispersion used comprises a composition comprising vinyl pyridine latex in a mass fraction of 20% based on the dry weight of the aqueous dispersion, blocked hexamethylene diisocyanate in a mass fraction of 5% based on the dry weight of the aqueous dispersion, and polyisoprene rubber latex in a mass fraction of 10% based on the dry weight of the aqueous dispersion. The aqueous dispersion preferably also comprises an acrylic acid-based polycarboxylic acid and, as an epoxy compound, glycerol-based polyglycidyl ether.

[0093] The adhesion-activated reinforcement is then applied to the surface of a layered base material comprising a crosslinkable rubber compound. The crosslinkable rubber compound comprises 25 phr of a brominated copolymer of isobutylene and para-methylstyrene, 55 phr of natural polyisoprene, and 20 phr of cis-1,4-butadiene rubber. The crosslinkable rubber compound also contains 30 phr of amorphous silicon dioxide as a filler and is free of black colorants, particularly black pigments such as carbon black or graphene. As part of a standard vulcanization system, the crosslinkable rubber compound also contains 2.4 phr of sulfur, as well as other common components such as silane coupling agents and tackifier resins, which are selected so that they do not impair the transparency of the crosslinked rubber compound.After vulcanization, this crosslinkable rubber compound results in a crosslinked rubber compound which is, in its entirety, permeable to visible light with wavelengths in the range of 380 to 780 nm, so that the textile reinforcements embedded in the transparent crosslinked rubber compound can be clearly seen with the naked eye from the outside, even in the areas covered by the rubber coating.

[0094] The vulcanizable composite material produced as described above is combined with other components as part of the sidewall to form an unvulcanized green bicycle tire, wherein the vulcanizable composite material is arranged in the side region of the green bicycle tire such that the textile reinforcements are located on the outside of the surface.

[0095] An aqueous coating material is applied to the textile reinforcements on the surface, which comprises a ceramic hard material with a mass fraction of approximately 7% and a polyisoprene-based binder.

[0096] The unvulcanized bicycle tire blank is then vulcanized under standard conditions to produce a bicycle tire. The tire comprises the vulcanized composite material in the sidewall area, forming the outermost layer of the bicycle tire, so that the textile reinforcement lies on the outside surface. During vulcanization, the cross-linkable rubber compound is pressed against the textile reinforcement from below, so that in the vulcanized bicycle tire, it is partially surrounded by the cross-linked rubber compound.

Claims

1. Process for producing a vulcanizable composite material, comprising the steps of: a) producing or providing a textile strength member, b) treating the textile strength member with an aqueous dispersion for adhesive activation of the textile strength member and to obtain an adhesion-activated textile strength member, and c) arranging the adhesion-activated textile strength member on the surface of a base material comprising a crosslinkable rubberization mixture to obtain the vulcanizable composite material, wherein the aqueous dispersion - is essentially free of free resorcinol and resorcinol precondensates, especially resorcinol-formaldehyde precondensates, and is free of free formaldehyde and formaldehyde-releasing substances, and comprises - (x1) at least one rubber latex, and - (x2) at least one protected isocyanate in a proportion by mass based on the dry weight of the aqueous dispersion of 0.1% to 10%, and wherein the crosslinkable rubberization mixture is processible by vulcanization to give a crosslinked rubberization mixture which is at least partly transmissive to visible light at least in sections.

2. Process according to Claim 1, wherein the aqueous dispersion comprises the at least one rubber latex in a proportion by mass based on the dry weight of the aqueous dispersion of 4% to 60%.

3. Process according to either of Claims 1 and 2, wherein the aqueous dispersion comprises: (y1) at least one compound containing an epoxy group, preferably in a proportion by mass based on the dry weight of the aqueous dispersion of up to 6%, and / or (y2) at least one polymer having carboxylic acid-functional groups, preferably in a proportion by mass based on the dry weight of the aqueous dispersion of up to 15%.

4. Process according to any of Claims 1 to 3, wherein the aqueous dispersion comprises one of the following components: (z1) at least one filler, preferably in a proportion by mass based on the dry weight of the aqueous dispersion of 0.02% to 20%, preferably with the proviso that the aqueous dispersion does not include any polymer having carboxylic acid-functional groups, or (z2) at least one polyisoprene rubber latex, preferably in a proportion by mass based on the dry weight of the aqueous dispersion of 1% to 20%, preferably with the proviso that the aqueous dispersion includes at least one rubber latex which is not a polyisoprene rubber latex, or (z3) at least one wax, preferably in a proportion by mass based on the dry weight of the aqueous dispersion of 0.3% to 30%.

5. Process according to any of Claims 1 to 4, additionally comprising the step of: d) producing an unvulcanized vehicle tire blank comprising the vulcanizable composite material.

6. Process for producing a vehicle tire or a vulcanized composite material, comprising the steps of the process according to any of Claims 1 to 5, and additionally at least one of the steps of: e) vulcanizing the vulcanizable composite material to obtain a vulcanized composite material, and / or f) vulcanizing the unvulcanized vehicle tire blank to obtain a vehicle tire, wherein the vulcanizing is effected such that the adhesion-activated textile strength member, at least in sections, lies at the surface of the vulcanized composite material and / or of the vehicle tire, wherein the vulcanizing is preferably effected such that the adhesion-activated textile strength member is partly surrounded by the crosslinked rubberization mixture.

7. Vulcanizable composite material for the production of vehicle tires, comprising: i) at least one textile strength member that has been adhesion-activated at least in sections, preferably essentially entirely, with an aqueous dispersion, and ii) a base material comprising a crosslinkable rubberization mixture, wherein the textile strength member is disposed on the surface of the base material, wherein the textile strength member is preferably partly surrounded by the crosslinkable rubberization mixture, wherein the aqueous dispersion - is essentially free of free resorcinol and resorcinol precondensates, especially resorcinol-formaldehyde precondensates, and is free of free formaldehyde and formaldehyde-releasing substances, and comprises - (x1) at least one rubber latex, and - (x2) at least one protected isocyanate in a proportion by mass based on the dry weight of the aqueous dispersion of 0.1% to 10%, and wherein the crosslinkable rubberization mixture is processible by vulcanization to give a crosslinked rubberization mixture which is at least partly transmissive to visible light at least in sections.

8. Vulcanized composite material, especially for use as an abrasion guard in vehicle tires, produced or producible by vulcanization of the vulcanizable composite material according to Claim 7, comprising a crosslinked rubberization mixture which is at least partly transmissive to visible light, wherein the adhesion-activated textile strength member, at least in sections, lies at the surface of the vulcanized composite material, wherein the adhesion-activated textile strength member is preferably partly surrounded by the crosslinked rubberization mixture.

9. Vehicle tire comprising a vulcanized composite material according to Claim 8.