Coated core textile reinforcing element, staple fibers and product reinforced by at least one staple fiber

Abstract

The present invention relates to a core coated fabric reinforcing element comprising at least one or more fabric filaments and / or a plurality of natural fabric fibers or organic polymer fibers. The core-coated fabric reinforcement element is obtained by a process comprising a step of manufacturing the coated fabric reinforcement element, in which step the fabric reinforcement element passes through a bath of an adhesive composition, the amount of dry matter derived from the bath of the adhesive composition being between 10 dry weight% and 20 dry weight% of the fabric reinforcement element.

Description

Field of the Invention

[0001] The field of the present invention is that of core-coated fabric reinforcement elements, short fibers obtained by cutting core-coated fabric reinforcement elements, and composite materials comprising an elastomeric material and short fibers embedded in the elastomeric material. The present invention more particularly relates to such composite materials for forming reinforcement products selected from conveyor belts, transmission belts, caterpillar tracks, pneumatic tires or non-pneumatic tires. Background Art

[0002] It is known from the prior art (in particular EP1792755) that short carbon fibers coated with an aqueous binder composition based on RFL (resorcinol-formaldehyde-latex) are used to reinforce an elastomeric matrix. The coating of the fibers must be such that it prevents any agglomeration of the fibers during the binder treatment step, where agglomeration is defined as more than five individual short cut fibers sticking together along at least a part of the longitudinal axis of the fiber, and after adding the short cut fibers to the elastomeric blend in a mixer, the mixing should be sufficient to again prevent any agglomeration of the fibers in the elastomer.

[0003] It is also known from the prior art (in particular EP 1349889) a method for core-coating carbon fibers for reinforcing an elastomeric matrix, in which the fibers are twisted and then combined into a continuous reinforcement.

[0004] The disadvantages of carbon fibers are firstly their susceptibility to damage in textile processes and secondly their relatively low elongation at break. Finally, carbon fibers are relatively expensive, which limits their use in tire applications.

[0005] However, there is a desire to find new core-coated reinforcement elements with a sufficiently high elongation at break and which can be industrially produced, which ensure good reinforcement / elastomeric matrix adhesion. Summary of the Invention

[0006] The object of the present invention is to provide a core-coated fabric reinforcement element which meets this purpose.

[0007] The present invention relates to a core-coated fabric reinforcement element, the core-coated fabric reinforcement element comprising:

[0008] at least one or more organic polymer fabric filaments or natural fabric filaments and / or a plurality of organic polymer fabric fibers or natural fabric fibers;

[0009] wherein the core-coated fabric reinforcement element is obtained by a method comprising a step of manufacturing a coated fabric reinforcement element in which the fabric reinforcement element passes through a bath of a binder composition, and the amount of solids originating from the bath of the binder composition is 9.6 dry weight % to 20 dry weight % of the fabric reinforcement element.

[0010] The Applicant has noticed that the core-coated reinforcing elements obtained by the core coating method described below have an amount of solids from the bath of the binder composition that is 9.6 dry weight % to 20 dry weight % of the fabric reinforcing element, which is much higher than that of the reinforcing elements coated according to the conventional coating method. The compounds mentioned in the specification can be compounds of fossil origin or bio-based compounds. In the case of bio-based compounds, they can be partially or completely derived from biomass, or obtained from renewable raw materials derived from biomass. In the same way, the mentioned compounds can also be derived from the recycling of materials that have been used, i.e., they can be partially or completely derived from recycling processes, or obtained from raw materials that themselves are derived from recycling processes. This particularly includes filaments, fibers, polymers, plasticizers, fillers, etc.

[0011] A filament is a very long, continuous single element, usually obtained by spinning a molten material. It can be artificial or synthetic.

[0012] Preferably, each filament and / or each fiber is selected from polyester filaments and fibers, polyamide filaments and fibers, polyketone filaments and fibers, polyurethane filaments and fibers, acrylic filaments and fibers, polyolefin filaments and fibers, polyetheretherketone filaments and fibers, and combinations of these filaments and these fibers, preferably selected from polyester filaments and fibers, polyamide filaments and fibers, and combinations of these filaments and these fibers, and more preferably, the synthetic organic filaments and fibers are polyester or polyamide filaments and fibers, such as nylon PA4.6, PA56, PA6, PA6.6, or even PA6.10.

[0013] By definition, a fabric reinforcing element is a combination of these filaments and these fibers. Each reinforcing element is impregnated with a composition that ensures the cohesion between these filaments and these fibers and is capable of preventing wear of each reinforcing element.

[0014] RFL (resorcinol-formaldehyde-latex) type binder compositions can be mentioned, but binder compositions as described in WO 2015 / 118041 can also be mentioned.

[0015] Preferably, each reinforcing element can also be impregnated with a pre-binder of an aqueous composition, especially for fibers and / or filaments with poor affinity for RFL type binder compositions. This pre-bonding step is carried out upstream of the step of manufacturing the core-coated fabric reinforcing element. For example, pre-binders containing epoxy compounds and isocyanate compounds are mentioned.

[0016] The amount of the binder composition is measured by chemical erosion (either by eroding the binder composition or by eroding the fibers).

[0017] For polyamides, chemical erosion is carried out by eroding the fibers with a hot acid solution. The fibers are thus destroyed and the residue consisting of the binder composition is recovered and weighed. The weight of the binder composition is determined by correlating the weight of the residue with the weight of the dry uncoated fibers.

[0018] For other fibers (such as polyester fibers, polyketone fibers, polyurethane fibers, acrylic fibers, polyolefin fibers or polyetheretherketone fibers), chemical erosion is carried out by eroding the binder composition with an acidic oxidation solution. The binder composition, as well as the sizing and pre-binder, are destroyed.

[0019] The residue consisting of the fibers is recovered and weighed. The weight of the binder composition is determined as follows: weighing the fibers before and after eroding the binder composition and calibrating the result obtained by the amount of sizing and pre-binder deposited on the fibers.

[0020] The amount of sizing and pre-binder deposited on the fibers can be determined experimentally by eroding the raw fibers.

[0021] Advantageously, the core-coated fabric reinforcement element consists of: at least one or more organic polymer fabric filaments or natural fabric filaments and / or a plurality of organic polymer fabric fibers or natural fabric fibers; wherein the core-coated fabric reinforcement element is obtained by a method comprising the step of manufacturing a coated fabric reinforcement element in which the fabric reinforcement element passes through a bath of the binder composition, and the amount of solids from the bath of the binder composition accounts for 9.6 dry weight % to 20 dry weight % of the fabric reinforcement element.

[0022] Thus, according to this preferred embodiment, the reinforcement element consists only of one or more organic polymer fabric filaments or natural fabric filaments core-coated with the binder composition and / or a plurality of organic polymer fabric fibers or natural fabric fibers core-coated with the binder composition, without any other metal components. Consisting only of one or more organic polymer fabric filaments or natural fabric filaments and / or a plurality of organic polymer fabric fibers means that there are no metal filaments in the reinforcement element.

[0023] It will be recalled that polyester filaments and / or fibers are a group of filaments consisting of linear macromolecules formed by groups bonded to each other by ester bonds. Polyester is manufactured by polycondensation by an esterification reaction between one of the dicarboxylic acids or its derivatives and a diol. For example, polyethylene terephthalate can be manufactured by the polycondensation of terephthalic acid and ethylene glycol. Among the known polyesters, mention may be made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT) or polypropylene naphthalate (PPN).

[0024] It will be recalled that, as is well known, filaments and / or fibres of aromatic polyamides or aromatic copolyamides are a group of filaments composed of linear macromolecules formed by aromatic groups bonded to one another by amide bonds (at least 85% of the amide bonds being directly bonded to two aromatic rings), and more particularly fibres made of poly(p-phenyleneterephthalamide) (or PPTA), which has long been manufactured from an optically anisotropic spinning composition. Among aromatic polyamides or aromatic copolyamides, mention may be made of polyarylamide (or PAA, in particular the trade name Ixef from Solvay), poly(m-xylylene adipamide), polyphthalamide (or PPA, in particular the trade name Amodel from Solvay), amorphous semi-aromatic polyamide (or PA 6-3T, in particular the trade name Trogamid from Evonik), meta-aramid (or poly(m-phenyleneterephthalamide) or PAMPD-I, in particular the trade name Nomex from Du Pont de Nemours) or para-aramid (or poly(p-phenyleneterephthalamide) or PA PPD-T, in particular the trade name Kevlar from Du Pont de Nemours or the trade name Twaron from Teijin).

[0025] Aliphatic polyamide filaments and / or fibres are understood to be a group of filaments composed of linear macromolecules of a polymer or copolymer containing amide functional groups, said polymer or copolymer being free of aromatic rings and being synthesizable by polycondensation between a carboxylic acid and an amine. Among aliphatic polyamides, mention may be made of nylon PA4.6, PA6, PA6.6 or PA6.10, in particular Zytel from DuPont, Technyl from Solvay or Rilsamid from Arkema.

[0026] Advantageously, the count of the aliphatic polyamide filaments and / or fibres ranges from 7 tex to 660 tex, preferably from 50 tex to 440 tex, more preferably from 90 tex to 220 tex.

[0027] The count (or linear density) of each filament and / or fibre is determined according to standard ASTM D1423. The count is given in tex (the mass in grams of 1000 m of product - as a reminder: 0.111 tex is equal to 1 denier). The density of the reinforcing elements in the composite material is the number of reinforcing elements included in one decimetre of the composite material in a direction perpendicular to the direction in which the reinforcing elements extend parallel to one another.

[0028] In one embodiment, advantageously, the organic polymer filaments and fibers are selected from polyesters, aromatic polyamides or aromatic copolyamides, aliphatic polyamides, preferably filaments and fibers made of polyester (e.g., PET) or polyamide (e.g., nylon PA4.6, PA56, PA6, PA6.6 and PA6.10).

[0029] In another embodiment, advantageously, the natural filaments and fibers are selected from natural cellulose fibers, linen, hemp, cotton, sisal, kenaf, bamboo, jute and coir fibers.

[0030] Preferably, the amount of solids obtained from the bath of the binder composition is from 10% to 20% by dry weight of the fabric reinforcement element, more preferably from 10% to 15% by dry weight of the fabric reinforcement filler. Advantageously, the weight of the binder composition is greater than or equal to 70 g / kg of the reinforcement element.

[0031] Preferably, the weight of the binder composition is greater than or equal to 80 g / kg of the reinforcement element, preferably greater than or equal to 100 g / kg of the reinforcement element.

[0032] More preferably, when the organic polymer filaments and fibers are selected from polyesters, the weight of the binder composition is greater than or equal to 100 g / kg.

[0033] More preferably, when the organic polymer filaments and fibers are selected from nylon, preferably nylon 66, the weight of the binder composition is greater than or equal to 120 g / kg.

[0034] Advantageously, the weight of the binder composition is less than or equal to 250 g / kg of the reinforcement element, preferably less than or equal to 200 g / kg of the reinforcement element. Specifically, an excessive layer of the binder composition will degrade the properties of the fiber mixture and generally indicate an "excess" of the binder composition at the surface.

[0035] In one embodiment, the fabric reinforcement element comprises a single multifilament strand.

[0036] Preferably, in this embodiment, the fabric reinforcement element consists of a single multifilament strand.

[0037] In another embodiment, each fabric reinforcement element comprises a plurality of multifilament strands.

[0038] Advantageously, the binder composition is based on at least one phenolic resin, the phenolic resin being based at least on:

[0039] - aldehyde;

[0040] - polyphenol having one or more aromatic rings, it being understood that:

[0041] In the case of a single aromatic ring, the aromatic ring bears two or three hydroxyl functional groups which are meta to each other, and the remainder of the aromatic ring is unsubstituted;

[0042] In the case of multiple aromatic rings, where at least two aromatic rings each bear two or three hydroxyl functional groups which are meta to each other, it should be understood that the two ortho positions of at least one of these hydroxyl functional groups are unsubstituted.

[0043] "Meta to each other" is intended to mean that the hydroxyl functional groups are carried by carbons of the aromatic ring which are separated from each other by a single other carbon of the aromatic ring.

[0044] "The ortho position of the functional group" is intended to mean the position occupied by the carbon of the aromatic ring which is adjacent to the carbon of the aromatic ring bearing the functional group.

[0045] "Members" of a ring are intended to mean the constituent atoms of the ring skeleton. Thus, for example, a benzene ring contains six members, each member being composed of a carbon atom. In another example, a furan ring contains five members, four members each being composed of a carbon atom, and the remaining member being composed of an oxygen atom.

[0046] "CHO" represents an aldehyde functional group.

[0047] "CH2OH" represents a hydroxymethyl functional group.

[0048] "Aromatic polyphenol" means an aromatic compound containing at least one benzene ring bearing more than one hydroxyl functional group.

[0049] "Resin-based" should be understood to mean that the resin contains a mixture and / or reaction product of the various basic components for the resin as defined above, and the resin is based only on the components of the composition.

[0050] Very preferably, the binder composition is aqueous. The term "aqueous" is understood to mean that the water content of the binder composition is greater than or equal to 50% by weight. Using water as a solvent makes the binder composition easy to use under industrial conditions at low cost.

[0051] aldehyde compound

[0052] The basic component of the binder composition is a compound containing at least one aldehyde.

[0053] According to the present invention, the binder composition is based on at least one (i.e., one or more) aldehyde.

[0054] In one embodiment, the aldehyde is formaldehyde.

[0055] In another embodiment, the aldehyde is an aromatic aldehyde bearing at least one aldehyde functional group.

[0056] Advantageously, in this embodiment, the aromatic aldehyde bears at least two aldehyde functional groups.

[0057] Preferably, the aromatic ring of the aromatic aldehyde is a benzene ring.

[0058] More preferably, the aromatic aldehyde is selected from 1,2-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,4-benzenedicarboxaldehyde, 2-hydroxybenzene-1,3,5-tricarboxaldehyde, and mixtures of these compounds, preferably 1,4-benzenedicarboxaldehyde.

[0059] polyphenol compound

[0060] Another essential component of the binder composition is a polyphenol containing one or more aromatic rings. The aromatic polyphenol contains at least one aromatic ring having at least two hydroxyl functional groups located meta to each other, and the two ortho positions of at least one hydroxyl functional group are unsubstituted.

[0061] According to the present invention, in one embodiment, the aromatic polyphenol can be a simple aromatic polyphenol molecule containing one or more aromatic rings, at least one (and in fact even each) of these aromatic rings having at least two hydroxyl functional groups located meta to each other, and the two ortho positions of at least one hydroxyl functional group being unsubstituted.

[0062] In a preferred embodiment, the aromatic ring of the aromatic polyphenol bears three hydroxyl functional groups located meta to each other.

[0063] Preferably, the two ortho positions of each hydroxyl functional group are unsubstituted. This is intended to mean that the two carbon atoms on either side (in the ortho positions) of the hydroxylated carbon atom (i.e., the carbon atom bearing the hydroxyl functional group) bear only hydrogen atoms.

[0064] Even more preferably, the remaining portion of the aromatic ring of the aromatic polyphenol is unsubstituted. This is intended to mean that the other carbon atoms of the remaining portion of the aromatic ring (the carbon atoms other than the carbon atoms bearing the hydroxyl functional groups) bear only hydrogen atoms.

[0065] In one embodiment, the aromatic polyphenol contains a plurality of aromatic rings, at least two of these aromatic rings each having at least two hydroxyl functional groups located meta to each other, and the two ortho positions of at least one hydroxyl functional group of at least one aromatic ring being unsubstituted.

[0066] In a preferred embodiment, at least one aromatic ring of the aromatic polyphenol bears three hydroxyl functional groups located meta to each other.

[0067] Preferably, the two ortho positions of each hydroxyl functional group of at least one aromatic ring are unsubstituted.

[0068] Even more preferably, the two ortho positions of each hydroxyl functional group of each aromatic ring are unsubstituted.

[0069] Advantageously, the aromatic ring or each aromatic ring of the aromatic polyphenol is a benzene ring.

[0070] As examples of aromatic polyphenols containing only one aromatic ring, resorcinol and phloroglucinol may be specifically mentioned, as a reminder that they have the structural formulas (IV) and (V) respectively:

[0071]

[0072] As an example, in the case where the aromatic polyphenol contains a plurality of aromatic rings, at least two of these aromatic rings are the same or different and are selected from aromatic rings having the following general formula:

[0073]

[0074] Wherein if there are a plurality of Z1 and Z2 symbols on the same aromatic ring, the Z1 and Z2 symbols are the same or different and represent atoms (e.g., carbon, sulfur or oxygen) or linking groups, which by definition are at least divalent and connect at least these two aromatic rings to the remainder of the aromatic polyphenol.

[0075] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl sulfide having the following structural formula (VII):

[0076]

[0077] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl benzophenone having the following structural formula (VIII):

[0078]

[0079] It should be noted that each of the compounds VII and VIII is an aromatic polyphenol containing two aromatic rings (Formula VI-c), and each aromatic ring bears at least two (in this case two) hydroxyl functional groups located meta to each other.

[0080] It should be noted that in the case of an aromatic polyphenol containing at least one aromatic ring according to Formula VI-b, the two ortho positions of each hydroxyl functional group of at least one aromatic ring are unsubstituted. In the case of an aromatic polyphenol containing a plurality of aromatic rings according to Formula VI-b, the two ortho positions of each hydroxyl functional group of each aromatic ring are unsubstituted.

[0081] According to one embodiment of the present invention, the aromatic polyphenol is selected from resorcinol (IV), phloroglucinol (V), 2,2',4,4'-tetrahydroxydiphenyl sulfide (VII), 2,2',4,4'-tetrahydroxydiphenyl benzophenone (VIII) and mixtures of these compounds. In a particularly advantageous embodiment, the aromatic polyphenol is phloroglucinol.

[0082] In one embodiment, the aromatic polyphenol A2 comprises a precondensed resin based on the aromatic polyphenol as described in any one of these embodiments.

[0083] The precondensed resin is advantageously based on:

[0084] · at least one aromatic polyphenol as previously defined, said aromatic polyphenol being preferably selected from resorcinol, phloroglucinol, 2,2’,4,4’-tetrahydroxydiphenyl sulfide, 2,2’,4,4’-tetrahydroxybenzophenone and mixtures thereof; and

[0085] · at least one compound capable of reacting with an aromatic polyphenol comprising at least one aldehyde functional group and / or at least one compound capable of reacting with an aromatic polyphenol comprising at least two hydroxymethyl functional groups, preferably an aromatic aldehyde comprising at least one aromatic ring bearing at least one aldehyde functional group.

[0086] The compound capable of reacting with the aromatic polyphenol may be the compound A1 as previously defined or any other aldehyde. Advantageously, the compound is selected from aromatic compounds comprising an aromatic ring bearing at least two functional groups, one of which is a hydroxymethyl functional group and the other is an aldehyde functional group or a hydroxymethyl functional group, formaldehyde, furfural, 2,5-furandialdehyde, 1,4-benzenedialdehyde, 1,3-benzenedialdehyde, 1,2-benzenedialdehyde and mixtures of these compounds. Very advantageously, when the compound capable of reacting with the aromatic polyphenol is an aromatic compound comprising an aromatic ring bearing at least two functional groups, one of which is a hydroxymethyl functional group and the other is an aldehyde functional group or a hydroxymethyl functional group, the compound is selected from 5-(hydroxymethyl)furfural, 2,5-bis(hydroxymethyl)furan and mixtures of these compounds.

[0087] Thus, in the precondensed resin based on the aromatic polyphenol, the repeating unit corresponds to the characteristics of the aromatic polyphenol defined above, except that at least one carbon atom (which is unsubstituted) of the aromatic ring is linked to another unit.

[0088] Regardless of the compound other than the aromatic polyphenol on which the precondensed resin is based, the precondensed resin does not contain free formaldehyde. This is because, even when the precondensed resin is based on the aromatic polyphenol and formaldehyde as described above, since the formaldehyde has reacted with the aromatic polyphenol, the precondensed resin does not contain free formaldehyde that may react with the compound A1 according to the present invention in subsequent steps.

[0089] As described above, the aromatic polyphenol A2 may also comprise a mixture of free aromatic polyphenol molecules and a precondensed resin based on the aromatic polyphenol. In particular, the aromatic polyphenol A2 may also comprise a mixture of phloroglucinol and a precondensed resin based on phloroglucinol.

[0090] Method for manufacturing a core-coated reinforcing element according to the present invention

[0091] An example of a method for core coating of reinforcement elements will now be described.

[0092] In this method, the reinforcement element is a PA 6.6 fabric reinforcement element, the core of which is coated with an RFL-based aqueous binder composition.

[0093] An optional step of pulling the reinforcement element is carried out to open the filaments and / or fibers constituting it, and then a step of bringing the fabric reinforcement element into contact with the binder composition in a trough is carried out. The trough is equipped with two central guides machined in the shape of domes to open the reinforcement element. Then, in another step, the reinforcement element passes through at least two other troughs, each trough containing the same binder composition, and each trough is equipped with a roller of the "miniature paint roller" type downstream. The reinforcement element passes through the roller to remove the excess binder composition. After this step, there is a step of drying the coated reinforcement element at a temperature in the range of 150 °C to 240 °C (here at 220 °C) for 27 seconds.

[0094] Short fiber according to the present invention

[0095] The invention also relates to short fibers obtained by cutting the core-coated fabric reinforcement element as described above into lengths in the range of 0.1 mm to 20 mm, preferably 0.4 mm to 10 mm.

[0096] Short fibers are understood to mean short fibers with a shortened length. They can be natural fibers or chopped filaments.

[0097] Advantageously, the diameter is in the range of 0.5 μm to 100 μm, preferably 1 μm to 30 μm.

[0098] Method for manufacturing the short fiber according to the present invention

[0099] The short fibers are obtained by cutting the core-coated fabric reinforcement element as described above.

[0100] Composite material according to the present invention

[0101] The invention also relates to an elastomeric composite material reinforced with at least one short fiber as described above, the elastomeric composite material comprising an elastomeric matrix embedded with short fibers.

[0102] The elastomeric matrix is based on an elastomeric composition comprising at least one elastomer and another component.

[0103] Preferably, the elastomeric composition comprises a diene elastomer. An elastomer or rubber of the "diene" type (the two terms being synonymous) generally means an elastomer produced at least in part (i.e., a homopolymer or copolymer) from a diene monomer (a monomer with two conjugated or non-conjugated carbon-carbon double bonds).

[0104] The elastomeric composition may comprise only one diene elastomer or a mixture of various diene elastomers, and the diene elastomer can be used in combination with any type of synthetic elastomer other than the diene elastomer, and in fact even in combination with polymers other than elastomers (such as thermoplastic polymers).

[0105] In a first embodiment preferably intended for tire applications, the elastomeric composition comprises a diene elastomer selected from polybutadiene (BR), ethylene / butadiene rubber (EBR), natural rubber (NR), synthetic polyisoprene (IR), various butadiene copolymers, various isoprene copolymers, and mixtures of these elastomers.

[0106] Such copolymers are more preferably selected from butadiene / styrene copolymers (SBR) (whether the styrene is prepared by emulsion polymerization (ESBR) or solution polymerization (SSBR)), isoprene / butadiene copolymers (BIR), isoprene / styrene copolymers (SIR), and isoprene / butadiene / styrene copolymers (SBIR).

[0107] In a second embodiment preferably intended for conveyor belts, the elastomeric composition comprises an elastomer selected from TPU (thermoplastic polyurethane), PU (polyurethane), ethylene / α-olefin elastomers, polychloroprene elastomers, and mixtures of these elastomers, and one or more other elastomers. The elastomeric composition may also comprise one or more other components.

[0108] Advantageously, the ethylene / α-olefin elastomers are selected from ethylene / propylene copolymers (EPM), ethylene / propylene / diene copolymers (EPDM), and mixtures of these copolymers.

[0109] Preferably, the elastomeric composition comprises a reinforcing filler.

[0110] When using a reinforcing filler, any type of reinforcing filler known to be capable of reinforcing an elastomeric composition useful for manufacturing tires can be used, such as organic fillers (such as carbon black), reinforcing inorganic fillers (such as silica), or blends of these two types of fillers (especially blends of carbon black and silica).

[0111] Any carbon black conventionally used in tires ("tire-grade" carbon black) is suitable as the carbon black. Reinforcing carbon blacks of the 100, 200, or 300 series (ASTM grades), for example, will be mentioned more particularly.

[0112] In the case of using carbon black and isoprene elastomers, the carbon black can, for example, already be introduced into the isoprene elastomer in the form of a masterbatch (see, for example, applications WO 97 / 36724 and WO 99 / 16600).

[0113] As an example of an organic filler in addition to carbon black, mention may be made of functionalized polyvinyl aromatic organic fillers as described in applications WO-A-2006 / 069792 and WO-A-2006 / 069793.

[0114] In the present application, by definition, the term "reinforcing inorganic filler" should be understood to mean any inorganic filler or mineral filler (regardless of its color and its origin (natural or synthetic)), which is also referred to as a "white filler", a "transparent filler" or in fact even a "non-black filler" relative to carbon black, and which is capable of reinforcing the elastomer composition alone without means other than an intermediate coupling agent, in other words, which is capable of replacing conventional tyre-grade carbon black in terms of the reinforcing effect. In a known manner, such fillers are generally characterized by the presence of hydroxyl (-OH) groups on their surface.

[0115] It is not important in what physical state the reinforcing inorganic filler is provided, whether it is in the form of a powder, microbeads, granules, beads or any other suitable densified form. Of course, "reinforcing inorganic filler" is also understood to mean a mixture of different reinforcing inorganic fillers, in particular a mixture of highly dispersible siliceous fillers and / or aluminous fillers as described, for example, hereinafter.

[0116] Mineral fillers of the siliceous type (in particular silica (SiO2)) or of the aluminous type (in particular alumina (Al2O3)) are particularly suitable as reinforcing inorganic fillers. The silica used can be any reinforcing silica known to the person skilled in the art, in particular any precipitated silica or pyrogenic silica with a BET specific surface area and a CTAB specific surface area both less than 450 m 2 / g, preferably from 30 m 2 / g to 400 m 2 / g. As highly dispersible precipitated silica ("HDS"), mention may be made, for example, of Ultrasil 7000 and Ultrasil 7005 silica from Evonik, Zeosil 1165MP, 1135MP and 1115MP silica from Rhodia, Hi-Sil EZ150G silica from PPG, Zeopol 8715, 8745 and 8755 silica from Huber or silica with a high specific surface area as described in application WO 03 / 16837.

[0117] Finally, those skilled in the art will understand that as a filler equivalent to the reinforcing inorganic filler described in this section, a reinforcing filler having another property (especially an organic property) can be used, provided that the reinforcing filler is covered with an inorganic layer (such as silica), or contains functional sites (especially hydroxyl sites) on its surface that require the use of a coupling agent to establish a bond between the filler and the elastomer.

[0118] Preferably, the content of all reinforcing fillers (carbon black and / or reinforcing inorganic fillers (such as silica)) is in the range of 5 phr to 120 phr, more preferably 5 phr to 100 phr, still more preferably 5 phr to 90 phr.

[0119] Carbon black can advantageously constitute the sole reinforcing filler or the main reinforcing filler. Of course, only one type of carbon black or a blend of multiple carbon blacks with different ASTM grades can be used. Carbon black can also be used in combination with other reinforcing fillers (especially the reinforcing inorganic fillers described above, especially silica).

[0120] When an inorganic filler (such as silica) is used in the rubber composition (used alone or in combination with carbon black), its content is in the range of 0 phr to 100 phr, preferably 0 phr to 70 phr, especially 5 phr to 70 phr, and still more preferably the ratio varies from 5 phr to 50 phr, preferably 5 phr to 40 phr.

[0121] Preferably, the elastomer composition contains various additives.

[0122] The rubber composition can also contain all or part of the standard additives commonly used in elastomer compositions intended for the manufacture of tires, such as, for example, plasticizers or extender oils (whether of aromatic or non-aromatic nature), pigments, protective agents (such as anti-ozone waxes, chemical anti-ozone agents, antioxidants), anti-fatigue agents or adhesion promoters.

[0123] Preferably, the elastomer composition contains a crosslinking system.

[0124] In a first embodiment preferably intended for tires, tracks or conveyor belts, the elastomer composition contains a vulcanization system.

[0125] The vulcanization system contains a sulfur donor, such as sulfur.

[0126] The vulcanization system preferably contains vulcanization activators, such as zinc oxide and stearic acid.

[0127] Preferably, the vulcanization system contains vulcanization accelerators and / or vulcanization retarders.

[0128] Advantageously, the composite material meets an elastomeric matrix based on an elastomeric composition comprising a crosslinking system, the crosslinking system comprising elemental sulfur in an amount ranging from 1 phr to 5 phr.

[0129] Very advantageously, the content of elemental sulfur in the crosslinking system of the elastomeric composition is greater than or equal to 1.5 phr.

[0130] The sulfur content is measured by elemental analysis using a Thermo Scientific Flash 2000 microanalyzer. The analysis includes a step of burning the sample, followed by a step of separating the formed compounds.

[0131] Approximately 1 mg of the sample is introduced into the microanalyzer and flash combustion is carried out at 1000 °C under oxygen. The formed gas is then oxidized by excess oxygen and a tungstic anhydride catalyst. Excess oxygen can be captured and nitrogen oxides can be reduced to N2 and sulfites can be reduced to sulfur dioxide SO2 by a subsequent step of reduction through copper. Water is captured, and the formed compounds N2, CO2, and SO2 are then separated on a chromatographic column and detected using a thermal conductivity detector. After calibration using a standard sample, the total sulfur is quantified by measuring the area of the SO2 peak.

[0132] Combined vulcanization accelerators, vulcanization retarders, and vulcanization activators are used in a preferred content in the range of 0.5 phr to 15 phr. The vulcanization activator is used in a preferred content in the range of 0.5 phr to 12 phr.

[0133] Suitable crosslinking systems are preferably based on sulfur and a primary vulcanization accelerator (especially a sulfenamide type accelerator). In addition to this vulcanization system are various known secondary vulcanization accelerators or vulcanization activators, such as zinc oxide, stearic acid, guanidine derivatives (especially diphenylguanidine), etc.

[0134] As (primary or secondary) accelerators, any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used, especially thiazole type accelerators and their derivatives, thiuram type, and zinc dithiocarbamate type accelerators. These accelerators are more preferably selected from 2-mercaptobenzothiazole disulfide (abbreviated as "MBTS"), N-cyclohexyl-2-benzothiazole sulfenamide (abbreviated as "CBS"), N,N-dicyclohexyl-2-benzothiazole sulfenamide (abbreviated as "DCBS"), N-(tert-butyl)-2-benzothiazole sulfenamide (abbreviated as "TBBS"), N-(tert-butyl)-2-benzothiazole sulfimide (abbreviated as "TBSI"), zinc dibenzyldithiocarbamate (abbreviated as "ZBEC"), and mixtures of these compounds. Preferably, a sulfenamide type primary accelerator is used.

[0135] In a second embodiment, preferably intended for conveyor belts, the crosslinking system is substantially sulfur-free and advantageously contains peroxides, preferably organic peroxides. Advantageously, the content of peroxides ranges from 0.5 phr to 8 phr. Advantageously, the crosslinking system contains a co-crosslinking agent, preferably sulfur or triallyl cyanurate. Advantageously, the content of the co-crosslinking agent ranges from 0.5 phr to 5 phr.

[0136] Reinforced product according to the present invention

[0137] The invention also relates to a reinforcing product comprising at least one composite material as described above. The reinforcing product according to the invention is advantageously selected from conveyor belts, conveyor belts, crawler tracks, pneumatic tires or non-pneumatic tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0138] The present invention will be more clearly understood by reading the following description, which is given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0139] - Figure 1 is a schematic view of a composite material F according to the invention;

[0140] - Figure 2 is a scanning electron micrograph of a composite material F1 according to the invention; and

[0141] - Figure 3 is an enlarged cross-sectional view of a core-coated reinforcing element 10-1 according to the invention. DETAILED DESCRIPTION

[0142] Examples of Composite Materials According to the Invention

[0143] Figure 1 Illustrated is a composite material, designated by the reference numeral F, according to the invention. The composite material F includes at least one short fiber E (in the present case, a plurality of short fibers E) embedded in a polymer matrix M.

[0144] Figure 1 The polymer matrix M and the short fibers E are illustrated in a reference system X, Y, Z, where the direction Y is the radial direction and the directions X and Z are the axial and circumferential directions. In Figure 1 the composite material F includes a plurality of short fibers E randomly arranged within the composite material and co-embedded in the polymer matrix M.

[0145] Here, the polymer matrix M is an elastomeric matrix based on an elastomeric composition.

[0146] Figure 2 Shows a scanning electron micrograph at an enlarged scale of a cross-section of a composite material F1 according to the invention having a white area of sizing on the core with short fibers E as described in Table 2 below.

[0147] Example of a core-coated reinforcing element according to the invention

[0148] Figure 3 is an enlarged cross-sectional view of the core-coated reinforcing element 10-1 according to the invention.

[0149] This reinforcing element 10-1 will be described in Table 1 below.

[0150] Of course, the present invention relates to the objects described above in the uncured state (before crosslinking) and the cured state (after crosslinking), i.e., the reinforcing products, such as drive belts, conveyor belts, crawler belts, pneumatic tires or non-pneumatic tires including them.

[0151] Comparative test

[0152] The results of the dry weight % of the various reinforcing elements and the corresponding binder compositions described below are tabulated in Table 1 below.

[0153] The control is a reinforcing element made of PA 6,6 coated by a known method of dipping PA 6,6 fibers into a bath of an RFL-based aqueous binder composition (a binder known as "RFL" (resorcinol-formaldehyde-latex)), as described, for example, in EP2006341. These RFL binders contain, in a known manner, a thermosetting phenolic resin obtained by the condensation of resorcinol and formaldehyde and a latex of one or more diene rubbers in an aqueous solution.

[0154] The reinforcing element 10-1 is a 140 tex PA 6,6 reinforcing element coated in a bath of an RFL-based aqueous binder composition by the core coating method as described above.

[0155] The reinforcing element 10-1' is a 140 tex PA 6,6 reinforcing element coated in a bath of a PT-based aqueous binder composition by the core coating method as described above, the PT binder being selected from the binder compositions described in WO2015118041, in particular a binder composition based on terephthalaldehyde and phloroglucinol.

[0156] The reinforcing elements 10-2, 10-3 and 10-2', 10-3' are described in Table 1 below.

[0157] [Table 1]

[0158]

[0159] These tests confirm that for core-coated reinforcing elements, the greater the dry weight % of the fabric reinforcing element, as Figure 3As shown, it was found that the adhesive composition penetrated into the core of the reinforcement element 10-1.

[0160] Shear measurement

[0161] Dynamic properties, particularly tan(δ)max at 100 °C, were measured on a viscosity analyzer (Metravib VA4000) according to standard ASTM D5992-96. According to standard ASTM D1349-09, the response of a vulcanized composition sample (2 mm thick, 79 mm 2 cylindrical specimen in cross-section) subjected to a simple alternating sinusoidal shear stress at a frequency of 10 Hz under standard temperature conditions (at 100 °C) was recorded. A strain amplitude sweep was performed from 0.1% to 50% (outward cycle) and then from 50% to 0.1% (return cycle). In the return cycle, the value of the loss factor, labeled tan(δ)max, was recorded.

[0162] The hysteresis performance results (tan(δ)max at 23 °C) are expressed as a percentage to the base 100 relative to the control composite C0. Results greater than 100 indicate an improvement in hysteresis performance, i.e., a reduction in hysteresis.

[0163] Tensile test

[0164] These tests were able to determine elastic stress and fracture properties. Unless otherwise stated, these tests were carried out according to the 1998 standard ASTM D412-98 (specimen C). ASTM C specimens with a thickness of 2.5 mm were used. According to the 1999 standard ASTM D1349, the force-displacement curve was carried out at a speed of 500 mm / min in the first elongation (i.e., without conditioning cycles) under normal humidity conditions (50% ± 5% relative humidity) at a temperature of 23 °C ± 2 °C. The secant modulus at 20% elongation (expressed as MSV20% and in MPa) was measured. The true secant modulus (MSV) is the ratio between the tensile stress of the specimen and the actual cross-section.

[0165] The results of the stiffness of the mixture (MSV) are expressed as a percentage to the base 100 relative to the control composite C0. Results greater than 100 indicate an even higher mixture stiffness compared to the control.

[0166] The various composites described below and the corresponding results are tabulated in Table 2 below.

[0167] Control C0 is a composition conventionally used in tire treads, based on 100 phr of natural rubber, 52 phr of carbon black of series 300, 1 phr of anti-ozone wax (Varazon 4959 from Sasol Wax), 1.5 phr of antioxidant (N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine; Santoflex 6-PPD from Flexsys), 1 phr of stearic acid (Pristene 4931 from Uniquema), 1 phr of 2,2,4-trimethyl-1,2-dihydroquinoline (PilnoxTMQ from Nocil), 1.7 phr of soluble sulfur, 1.1 phr of N-cyclohexylbenzothiazole sulfenamide (SantocureCBS from Flexsys) and 2.5 phr of industrial grade ZnO (Umicore); control C0 does not include short fibers.

[0168] Composite material C1 comprises control composition C0 and uncoated PA 6,6 short fibers.

[0169] Composite material E1 comprises control composition C0 and coated but not core-coated PA 6,6 short fibers.

[0170] Composite material C2 comprises control composition C0 and uncoated PET short fibers.

[0171] Composite material E2 comprises control composition C0 and coated but not core-coated PET short fibers.

[0172] Composite material F1 according to the invention comprises control composition C0 and core-coated PA 6,6 short fibers.

[0173] Composite material F2 according to the invention comprises control composition C0 and core-coated PET short fibers.

[0174] [Table 2]

[0175]

[0176] These tests confirm that for composite materials F1 and F2 according to the invention, very high mixture stiffness can be achieved without reducing the hysteresis performance.

[0177] The present invention is not limited to the above embodiments.

Claims

1. A core-coated fabric reinforcement element (10), characterized in that, It includes: At least one or more organic polymer fabric filaments or natural fabric filaments and / or one or more organic polymer fabric fibers or natural fabric fibers; Wherein, the fabric reinforcing element (10) coated on the core is obtained by a method including the step of manufacturing the coated fabric reinforcing element (10), in which the fabric reinforcing element passes through a bath of the adhesive composition, and the amount of solids from the bath of the adhesive composition accounts for 9.6 dry weight % to 20 dry weight % of the fabric reinforcing element.

2. The core-coated fabric reinforcement element (10) according to the preceding claim, wherein, The organic polymer filaments and fibers are selected from polyester, aromatic polyamide or copolyamide, aliphatic polyamide, preferably filaments and fibers made of polyester or polyamide, such as PET for the polyester and nylon PA4.6, PA56, PA6, PA6.6 and PA6.10 for the polyamide.

3. The core-coated fabric reinforcement element (10) according to claim 1, wherein, The natural filaments and fibers are selected from natural cellulose fibers, linen, hemp, cotton, sisal, kenaf, bamboo, jute and coir fibers.

4. The core-coated fabric reinforcement element (10) according to any one of the preceding claims, wherein, The weight of the adhesive composition is greater than or equal to 70 g / kg of the reinforcing element.

5. The core-coated fabric reinforcement element (10) according to any one of the preceding claims, wherein, The weight of the adhesive composition is greater than or equal to 80 g / kg of the reinforcing element, preferably greater than or equal to 100 g / kg of the reinforcing element.

6. The core-coated fabric reinforcement element (10) according to any one of the preceding claims, wherein, The weight of the adhesive composition is less than or equal to 250 g / kg of the reinforcing element, preferably less than or equal to 200 g / kg of the reinforcing element.

7. The core-coated fabric reinforcement element (10) according to any one of the preceding claims, wherein, The fabric reinforcing element includes a single multifilament strand.

8. The core-coated fabric reinforcement element (10) according to any one of the preceding claims, wherein, The adhesive composition is based on at least one phenolic resin, and the phenolic resin is at least based on: - Aldehyde; - Polyphenol having one or more aromatic rings, it should be understood that: In the case of a single aromatic ring, the aromatic ring is provided with two or three hydroxyl functional groups located meta to each other, and the remaining part of the aromatic ring is unsubstituted; In the case of multiple aromatic rings, at least two of the aromatic rings are each provided with two or three hydroxyl functional groups located meta to each other, it should be understood that the two ortho positions of at least one of these hydroxyl functional groups are unsubstituted.

9. The core-coated fabric reinforcement element (10) according to the preceding claim, wherein, The aldehyde is selected from 1,2-benzenedicarboxaldehyde, 1,3-benzenedicarboxaldehyde, 1,4-benzenedicarboxaldehyde, 2-hydroxybenzene-1,3,5-tricarboxaldehyde and mixtures of these compounds, preferably 1,4-benzenedicarboxaldehyde.

10. The core-coated fabric reinforcement element (10) according to claim 8 or 9, wherein, The polyphenol is phloroglucinol.

11. Short fibers (E), the short fibers (E) are obtained by cutting the fabric reinforcing element (10) coated on the core according to any one of the preceding claims into lengths in the range of 0.1 mm to 20 mm, preferably 0.4 mm to 10 mm.

12. The short fibers (E) according to the previous claim, the diameter of the short fibers (E) is in the range of 0.5 μm to 100 μm, preferably 1 μm to 30 μm.

13. An elastomeric composite material (F) reinforced with at least one short fiber (E) according to any one of claims 11 and 12, the elastomeric composite material (F) comprising an elastomeric matrix in which the short fibers (E) are embedded.

14. A reinforced product, the reinforced product includes at least one composite material (F) according to the previous claim.

15. The reinforced product according to the previous claim, the reinforced product is selected from conveyor belts, conveyor belts, crawler belts, pneumatic tires or non-pneumatic tires.

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