RU2413625C1 - Tire, metal cord and method of its protection - Google Patents

Abstract

FIELD: transport. ^ SUBSTANCE: invention relates to automotive industry. Proposed tire comprises, at least, one structural element including, at least, one metal cord that comprises multiple single metal wires twisted together. Every signal metal wire is coated with, at least, one layer of first metal coat. Metal cord is coated by, at least, one layer of second metal coat. Note here that one layer of second metal cord features nominal thickness exceeding or equal to 30 nm, preferably making 50 nm to 120 nm, more preferably making 70 nm to 100 nm. ^ EFFECT: higher corrosion resistance and better adhesion with rubber material. ^ 30 cl, 3 dwg

Description

Technical field

This invention relates to a tire, in particular to a tire for heavy vehicles, comprising at least one structural element including at least one metal cord containing a plurality of metal wires twisted together, each metal the wire is coated with at least one layer of the first metal coating, the metal cord being coated with at least one layer of the second metal coating.

In addition, the present invention also relates to an industrial rubberized article including at least one metal cord containing a plurality of metal wires twisted together, each metal wire being coated with at least one layer of a first metal coating, the metal cord is coated with at least one layer of a second metal coating.

In addition, the present invention also relates to a metal cord containing a plurality of metal wires twisted together, each metal wire being coated with at least one layer of a first metal coating, the metal cord being coated with at least one layer of a second metal coating , as well as to a method of manufacturing a metal cord.

For the purposes of the present invention, the expression “heavy-duty vehicle” means vehicles of categories M2-M3, N2-N3 and O2-O4 according to the consolidated resolution of the United Nations Economic Commission for Europe on the construction of vehicles (RE3), Appendix 7 “Classification and definition of vehicles with mechanical drive and trailers ”, for example, such as a lorry, tractor units with a trailer, trucks, buses, large vans and other similar vehicles.

State of the art

Hardening of industrial rubber products, such as tires, for example, by means of metal wires or metal cords (metal cords containing a plurality of metal wires twisted together), preferably steel wires or steel cords, is well known in the art.

Typically, metal wires are provided with a metal coating layer to perform the dual function of imparting appropriate corrosion resistance to said metal wires, as well as metal cords containing metal wires, and to ensure good adhesion of said metal wires, as well as metal cords containing said metal wires, to be crosslinked rubber material.

In addition, the presence of said metal coating layer on said metal wires also serves other purposes, for example, such as providing ease of drawing of said metal wires so as to obtain metal wires having a predetermined diameter and / or a predetermined mechanical resistance.

A number of coating methods are known in the art which make it possible to deposit said metal coating layer. For example, it is well known how to apply a metal coating layer of brass (a copper-zinc alloy) or zinc on steel wires or how to perform additional processing of these coated metal wires to obtain desired finished products. In addition, it is known how the drawing of such coated metal wires and the twisting of these metal wires together to produce metal cords as end products is known.

The application of such a metal coating layer with predetermined properties, for example, such as the thickness and / or composition of the metal coating layer, onto said metal wires can preferably be performed to obtain intermediate products with metal coating layers having the desired properties disclosed above.

However, as disclosed, for example, in US Pat. No. 5,219,668, which is reported below, it is known that the properties of said metal coating layer (e.g., a brass coating layer) can change substantially during the intermediate treatments to which metal wires can be subjected. coated, for example, during drawing or twisting operations, as a result of which the properties of the final products thus obtained (for example, metal cord) are not always satisfactory, in particular with respect to corrosion ion resistance and adhesion to crosslinked rubber material in which they are usually embedded.

For example, in the case of tires in metal cords, corrosion may begin due to moisture in the residual air that may remain inside the metal cords embedded in the crosslinked rubber material, or due to direct contact with water or moisture in the event of the destruction of said crosslinked rubber material that may occur during use of the tire and the result of which is the exposure of these metal cords to the environment.

In the art, attempts have been made to overcome the above disadvantages.

For example, US Patent No. 4,978,586 relates to a steel base with a metal coating layer for strengthening vulcanizable elastomers. The base is provided with a first coating layer and a second coating layer covering at least a portion of the first coating layer, and wherein a bonding layer comprising at least one non-metallic component is present between the layers of the first and second coating. The second coating layer contains, for example, cobalt, which can be applied by plasma spraying. It is claimed that the presence of the aforementioned bonding layer guarantees long-term adhesive adhesion between the first and second layers, as well as an increase in corrosion resistance, ductility, and wear resistance.

US patent No. 5219668 relates to a method for processing an elongated coated base, including:

performing an elongated base coated with a layer of the first coating;

giving an elongated base the shape of the first predetermined product;

cathodic deposition of a second coating layer onto said coated base by using an inert gas to spray to produce a second predetermined article, wherein said first coating layer is substantially thicker than said second coating layer.

The elongated base to be treated may be made of metal, in particular steel, and may have a brass or zinc coating. The specified elongated base may be a wire, strip, cord, etc. Preferably, said second coating layer has a thickness of 5 nm to 20 nm. It is argued that the above method provides the ability to quickly and efficiently produce end products with a coating or a covering surface with a given composition.

SUMMARY OF THE INVENTION

It has been observed that metal cords obtained as disclosed above, in particular metal cords having a second coating layer with a thickness equal to or less than 20 nm, may exhibit some disadvantages.

In particular, the applicant noted that the methods disclosed above may not provide the possibility of producing twisted metal cords having a metal coating layer with sufficient thickness, so as to ensure substantially no uncovered zones along the longitudinal deployment direction of said metal cords.

The expression "uncovered zones" refers to zones in which the actual thickness of the layer of metal coating is very small or this layer is even absent. The presence of these uncovered zones can adversely affect both the adhesion to the crosslinked rubber material and the corrosion resistance of said twisted metal cords, especially in the case of twisted metal cords that can be used in tire manufacturing.

In addition, it was noted that the presence of these uncovered areas also adversely affects the adhesion between the structural members of the tire, including these twisted metal cords. In particular, the applicant noted that the breaker edges or the edges of the carcass ply may be disconnected, in particular under conditions of high loads and stresses, which causes a negative impact on the tire service life.

In addition, it was noted that the presence of these uncovered areas negatively affects the ability to retread the tire tread, which is especially important in the case of tires for heavy vehicles.

The applicant turned to the solution of the problem of creating twisted metal cords coated with at least one layer of metal coating, demonstrating essentially the absence of uncovered zones.

It has now been found that metallic twisted cords coated with at least one metal coating layer having a nominal thickness greater than or equal to 30 nm exhibit substantially no uncovered zones.

For the purposes of the present invention, the expression "nominal thickness" corresponds to a macroscopic thickness that can be measured by subjecting the samples of metal cords coated with a metal coating layer to samples by etching, wherein said tests provide the ability to remove said metal coating layer and obtain an average thickness of said metal layer coatings along the longitudinal direction of deployment of metal cords.

The actual thickness of the coating layer of the twisted metal cord locally may differ significantly from the nominal (i.e. average) thickness of the same coating layer along the longitudinal deployment direction of the twisted metal cord. In the worst cases, a small nominal thickness of the coating layer may correspond to the absence of coating (i.e. an uncovered area) in some areas of the twisted metal cord when it is deployed in the longitudinal direction.

A “thick” coating layer should be applied to twisted metal cords to ensure that there are substantially no uncovered areas.

It has also been found that twisted metal cords coated with at least one metal coating layer having a nominal thickness greater than or equal to 30 nm exhibit improved adhesion to crosslinked rubber material in which they are embedded, in particular after aging in salt fog, as well as increased corrosion resistance.

It was also found that these twisted metal cords are particularly suitable in the manufacture of tires, more precisely, tires for heavy vehicles.

In accordance with a first aspect, the present invention relates to a tire comprising at least one structural member including at least one metal cord comprising a plurality of elementary metal wires twisted together, each elementary metal wire being coated, at least one layer of the first metal coating, wherein said metal cord is coated with at least one layer of a second metal coating, wherein said at least one with th second metallic coating has a nominal thickness of greater than or equal to 30 nm, preferably of from 50 nm to 120 nm, more preferably from 70 nm to 100 nm.

The nominal thickness can be measured in accordance with method BISFA - 95 (method E11 / 1) (1995). Further details regarding these measurements will be given in the following examples. It should be understood that in the case when the specified at least one layer of the second metal coating is made of metals or metal alloys other than copper, zinc or brass, the nitric acid solution described in this standard should be replaced by another solution, which allows the dissolution of various other metals or metal alloys. Specific examples of such another solution will be given in the following example.

The presence of the specified at least one layer of the second coating having a nominal thickness greater than or equal to 30 nm, allows to obtain a metal cord, characterized essentially by the absence of uncovered zones along the entire length of its deployment in the longitudinal direction.

For the purposes of the present invention, the expression “substantially no uncovered areas” means that even if present, said uncovered areas are present when their percentage is less than 1% or equal to 1%, preferably less than 0.5% or equal to 0, 5%, along any portion of the entire deployment length of the metal cord in the longitudinal direction.

For the purposes of the present invention, the expression "uncovered zones" corresponds to a zone having an actual thickness (i.e., microscopic thickness) of less than 20 nm or equal to 20 nm.

These uncovered areas can be determined by analysis using a scanning electron microscope (SEM) connected to a non-dispersive energy, X-ray diffraction analyzer (EDAX). Further details regarding this analysis will be given in the following examples.

In accordance with one embodiment, the tire comprises:

a frame structure comprising at least one layer of the frame having a substantially toroidal shape and having opposite side edges interacting with respective right and left side structures, wherein each side structure contains at least one bead core and, according to at least one side filler;

a belt structure superimposed in a radial direction from the outside with respect to said frame structure;

a tread band radially superimposed on said belt structure;

two sidewalls, laterally superimposed on opposite sides with respect to said frame structure;

at least one reinforcing layer wound around said bead core and bead filler so as to at least partially encompass them.

In accordance with one preferred embodiment, said at least one structural element is a belt structure.

Typically, said belt structure comprises:

the first layer of the breaker, located radially outside with respect to the specified frame structure, provided with reinforcing cords parallel to each other and inclined relative to the equatorial plane of the specified tire;

a second belt layer radially superimposed on said first belt layer and provided with reinforcing cords parallel to each other and inclined relative to the equatorial plane of said tire in a direction opposite to the direction of inclination of the reinforcing cords of the first belt layer;

at least one reinforcing layer radially superimposed on said second belt layer, wherein said reinforcing layer includes reinforcing elements oriented substantially in a circumferential direction.

According to one preferred embodiment, said at least one structural element is said first belt layer and / or said second belt layer, and / or said at least one reinforcing layer radially superimposed on said second breaker layer.

The belt structure may further comprise a third belt layer radially superimposed on said at least one reinforcing layer provided with reinforcing elements parallel to each other and inclined relative to the equatorial plane of said tire.

According to a further preferred embodiment, said at least one structural element is said third breaker layer.

According to a further preferred embodiment, said at least one structural element is said frame structure.

According to a further preferred embodiment, said at least one structural element is said at least one reinforcing layer wound around said bead core and bead filler so as to at least partially encompass them.

In accordance with a further aspect, the present invention also relates to an industrial rubberized article comprising at least one metal cord comprising a plurality of elementary metal wires twisted together, each elementary metal wire being coated with at least one layer of the first a metal coating, wherein said reinforcing metal cord is coated with at least one layer of a second metal coating, wherein said at least one the in layer of the second metal coating has a nominal thickness greater than or equal to 30 nm, preferably component from 50 nm to 120 nm, more preferably component from 70 nm to 100 nm.

According to a further aspect, the present invention also relates to a metal cord comprising a plurality of elementary metal wires twisted together, wherein each elementary metal wire is coated with at least one layer of a first metal coating, wherein said reinforcing metal cord is coated with at least , with one layer of the second metal coating, wherein said at least one layer of the second metal coating has a nominal thickness exceeding 50 nm, preferably between 80 nm and 120 nm.

For the purposes of the present invention, the term “plurality” should be interpreted as meaning “at least two”.

For the purposes of the present invention, unless otherwise indicated, all numbers expressing quantities, amounts, percentages, etc., should be understood as given in all cases with the term “approximately”. In addition, all ranges include any combination of maximum and minimum disclosed points and include any intermediate ranges that may or may not be specifically listed here.

The present invention, in at least one of the aforementioned aspects, may have one or more of the preferred features described hereinafter.

According to one preferred embodiment, said at least one layer of the second metal coating comprises a metal or a metal alloy, usually a double (two-component) or triple (three-component) metal alloy.

Preferably, said metal may be selected, for example, from: copper, zinc, manganese, cobalt, tin, molybdenum, iron, nickel, aluminum, titanium, tantalum, niobium, zirconium, chromium or their alloys, for example, such as brass (zinc-copper alloy ), zinc-cobalt alloy, zinc-manganese alloy, zinc-tin alloy, copper-tin alloy, chromium-nickel alloy, nickel-zinc alloy, copper-manganese alloy, copper-zinc-manganese alloy, zinc-cobalt-molybdenum alloy, zinc-iron-molybdenum alloy, copper-zinc-tin . More preferably, said metal is brass, or copper, or a zinc-manganese alloy, even more preferably, said metal is brass.

According to one preferred embodiment, said at least one layer of the second metal coating is made of brass having a copper content of from 60 weight percent to 75 weight percent, preferably from 62 weight percent to 70 weight percent, and a zinc content of 25 weight percent percent to 40 weight percent, preferably from 30 weight percent to 38 weight percent.

According to a further preferred embodiment, said at least one layer of the second metal coating is made of a zinc-manganese alloy having a zinc content of from 90 weight percent to 99 weight percent, preferably from 95 weight percent to 98 weight percent, and a manganese content of from 1 weight percent up to 10 weight percent, preferably from 2 weight percent to 5 weight percent.

According to a further preferred embodiment, said at least one layer of the second metal coating is made of a nickel-chromium alloy having a nickel content of from 80 weight percent to 90 weight percent, preferably from 82 weight percent to 88 weight percent, and a chromium content of 10 weight percent up to 20 weight percent, preferably from 12 weight percent to 18 weight percent.

According to one preferred embodiment, said elementary metal wires have a diameter (d) of 0.10 mm to 0.50 mm, preferably 0.12 mm to 0.40 mm.

According to one preferred embodiment, said elementary metal wires are made of steel. Typically, the fracture resistance (tear) of standard steel of normal strength is in the range from 2600 N / mm ² (or 2600 MPa - megaPascals) to 3200 N / mm ² , the fracture resistance of high-strength steel is in the range from 3000 N / mm ² to 3600 N / mm ² , the fracture resistance of ultra-high-strength steel is in the range from 3300 N / mm ² to 3900 N / mm ² , the fracture resistance of ultra-high-strength steel is in the range from 3600 N / mm ² to 4200 N / mm ² . The indicated values of fracture resistance depend, in particular, on the amount of carbon contained in the steel. Preferably, the high-strength, ultra-high-strength and ultra-high-strength elementary metal wires disclosed above are made of steel having a very high carbon content (typically in excess of 0.7%).

According to one preferred embodiment, said at least one layer of the first metal coating has a nominal thickness of 50 nm to 350 nm, preferably 70 nm to 250 nm.

According to one preferred embodiment, said at least one layer of the first metal coating comprises a metal or a metal alloy, usually a two-component or three-component metal alloy. The specified metal or a two-component or three-component metal alloy may be selected from those that were disclosed above for the specified at least one layer of the second metal coating.

According to one preferred embodiment, said at least one layer of the first metal coating is made of brass, copper or zinc, even more preferably it is made of brass.

According to one preferred embodiment, said at least one layer of the first metal coating is made of brass having a copper content of from 60 weight percent to 72 weight percent, more preferably from 62 weight percent to 67 weight percent, and a zinc content of 28 weight percent to 40 weight percent, preferably from 33 weight percent to 38 weight percent.

According to a further preferred embodiment, said at least one layer of the first metal coating is made of a two-component copper-tin alloy having a copper content of from 85 weight percent to 95 weight percent, preferably from 88 weight percent to 90 weight percent, and a tin content of 5 weight percent to 15 weight percent, preferably from 10 weight percent to 12 weight percent, or from a two-component zinc-manganese alloy having a zinc content from 90 weight percent to 98 weight percent, preferably from 95 weight percent to 97 weight percent and a manganese content of from 2 weight percent to 10 weight percent, preferably from 3 weight percent to 5 weight percent.

According to a further preferred embodiment, said at least one layer of the first metal coating is made of a three-component copper-zinc manganese alloy having a copper content of from 60 weight percent to 67 weight percent, preferably from 62 weight percent to 65 weight percent, zinc content from 30 weight percent up to 35 weight percent, preferably from 32 weight percent to 34 weight percent, and a manganese content from 2.5 weight percent to 5 weight percent, etc dpochtitelno from 3 weight percent to 4.5 weight percent; or from a three-component zinc-cobalt-molybdenum alloy having a zinc content of from 95 weight percent to 99 weight percent, preferably from 97 weight percent to 98 weight percent, cobalt content from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent up to 1.5 weight percent, and the molybdenum content is from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent to 1.5 weight percent; or from a three-component zinc-iron-molybdenum alloy having a zinc content of from 95 weight percent to 99 weight percent, preferably from 97 weight percent to 98 weight percent, an iron content of from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent up to 1.5 weight percent, and the molybdenum content is from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent to 1.5 weight percent; or from a three-component zinc-nickel-molybdenum alloy having a zinc content of from 95 weight percent to 99 weight percent, preferably from 97 weight percent to 98 weight percent, nickel content from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent up to 1.5 weight percent, and the molybdenum content is from 0.5 weight percent to 2.5 weight percent, preferably from 0.6 weight percent to 1.5 weight percent.

According to one preferred embodiment, said at least one layer of the first metal coating and said at least one layer of the second metal coating are made of the same metal or metal alloy.

Alternatively, said at least one layer of the first metal coating and said at least one layer of the second metal coating are made of different metals or metal alloys.

In accordance with one preferred embodiment, said metal cord has an n × d structure, where n is the number of elementary metal wires forming the cord and d is the diameter of each elementary metal wire. Preferably n is in the range from 2 to 5, more preferably from 2 to 4.

Preferred structures of metal cords, for example, are: 2 × 0.20 (i.e., two elementary metal wires twisted together, each elementary metal wire having a diameter of 0.20 mm), 3 × 0.20, 4 × 0, 20, 5 × 0.20, 6 × 0.20, 2 + 1 × 0.20 (i.e., one strand of two metal wires and one strand of one metal wire, while these two strands are twisted together, each elementary metal wire has a diameter of 0.20 mm), 2 + 2 × 0.20, 3 + 2 × 0.20, 1 + 4 × 0.20, 1 + 18 × 0.20, 3 + 9 + 15 × 0.20, 3/6 × 0.20 (i.e. three elementary metal rovoloki twisted in one direction, and six elementary metal wires, twisted in the opposite direction, with each elementary metal wire has a diameter of 0.20 mm).

In accordance with one preferred embodiment, said metal cord has a pitch of 2.5 mm to 25 mm, more preferably 6 mm to 18 mm.

In accordance with a further aspect, the present invention relates to a method for manufacturing a metal cord, comprising the steps of:

(a) twisting, preferably by twisting, a plurality of elementary metal wires so as to obtain a metal cord, wherein each elementary metal wire is coated with at least one layer of a first metal coating;

(b) depositing at least one layer of the second metal coating on the metal cord obtained in step (a) by plasma deposition technology so as to obtain a metal cord coated with at least one layer of the second metal coating, wherein the specified at least one layer of the second metal coating has a nominal thickness exceeding 50 nm, preferably component from 80 nm to 120 nm.

In accordance with one preferred embodiment, said method of manufacturing a metal cord further includes a step (c) of treating the surface of the metal cord obtained in step (a).

In accordance with a further embodiment, the present invention relates to a method for manufacturing a reinforced rubber product, comprising the steps of:

(a) twisting, preferably by twisting, a plurality of elementary metal wires so as to obtain a metal cord, wherein each elementary metal wire is coated with at least one layer of a first metal coating;

(b) depositing at least one layer of the second metal coating on the metal cord obtained in step (a) by plasma deposition technology so as to obtain a metal cord coated with at least one layer of the second metal coating;

(c) optionally, treating the surface of the metal cord obtained in step (a);

(d) embedding at least one coated metal cord obtained in step (b) into a crosslinkable elastomeric material so as to obtain a reinforced rubber product.

Preferably, the embedment step (d) may be performed by calendering or by extrusion.

Preferably, said method for manufacturing a reinforced rubber product further includes a step (e) of stitching the reinforced rubber product obtained in step (d).

For the purposes of the present invention, the term “plasma deposition technology” is used to denote any deposition technology that uses plasma to activate the evaporation of the metal to be deposited (for example, both by spraying and by evaporation by means of an electric arc), as a carrier for the metal to be deposited (for example, as in a plasma jet), or for the dissociation of process gases (for example, as in plasma-chemical vapor deposition) in a vacuum deposition (deposition) chamber.

Preferably, steps (a) of twisting, deposition (b) and optionally treating (c) the surface are performed in a substantially continuous manner.

For the purposes of the present invention, the term “substantially continuous” is used to indicate the absence of intermediate storage of semi-finished products between the various operations of the cord manufacturing process in order to ensure continuous production of coated metal cord of arbitrary length on the same production line.

The specified at least one layer of the first metal coating can be formed on these elementary metal wires by methods known in the art.

For example, said at least one layer of the first metal coating can be formed by electrochemical deposition techniques, such as those disclosed, for example, in European patent applications EP 669409, EP 694631 or EP 949356.

Alternatively, said at least one layer of the first metal coating may be formed by plasma deposition techniques, such as disclosure, for example, in international applications WO 2004/057053, WO 2005/095668, WO 2005/095078 or WO 2006/002673.

More preferably, if said at least one layer of the first metal coating is formed on said elementary metal wires, preferably steel wires, by a method comprising the steps of:

electrodeposition in at least one electrolytic bath; and

hoods in such a way as to obtain a given diameter and a given mechanical resistance of a coated metal wire.

If required, heat treatment and etching in an acidic solution can be performed.

Said twisting (a) may be performed by known twisting systems, for example, such as a double twisting system or a placement system.

Preferably, said deposition (b) can be performed by plasma deposition technology, which can be selected from the group consisting of: sputtering (in particular magnetron sputtering), arc evaporation, plasma jet, plasma-chemical vapor deposition.

Preferably, deposition step (b) is performed by magnetron sputtering. In this case, the regulation of the composition of the specified at least one layer of the second metal coating, consisting of an alloy, is preferably improved and simplified, since to obtain an alloy having a given composition, it is sufficient to use a cathode made of an alloy with such a composition, or, alternatively, at least two cathodes, of which each cathode is made of a metal component of an alloy or of a metal alloy to be deposited on a metal cord.

The specified magnetron sputtering can be performed by means of a magnetron sputtering device containing at least one vacuum deposition chamber, at least two cathodes, at least two pulleys, designed to allow metal cord to pass through the vacuum deposition chamber many times to obtain a layer of a second metal coating having a predetermined thickness of at least two power supply elements.

Said vacuum deposition chamber is usually provided with a vacuum pump (preferably a diffusion pump or a turbomolecular pump) suitable for generating a predetermined pressure within it. Furthermore, said vacuum deposition chamber is provided with devices for supplying a carrier gas, preferably argon.

Preferably, a metal cord, which behaves like an anode, is fed into a vacuum chamber, in particular in an area adjacent to the cathode or formed between the cathodes, so that metal layers can be deposited on said metal cord.

Preferably, the metal cord is coated in said vacuum deposition chamber operating at a given pressure, said pressure being preferably from 10 ⁻³ mbar to 10 ⁻¹ mbar, more preferably from 10 ⁻³ mbar to 5 × 10 ⁻³ mbar.

Sputtering essentially consists of an ion bombardment of the cathode, usually with an energy of 100 eV - 1000 eV and a current of 0.1 A to 10 A, by carrier gas ions produced by an electric field created by supplying power between cathode (s) and anode. More precisely, the carrier gas ions are accelerated towards the cathode (s), essentially causing a series of collisions, the result of which is the emission of cathode atoms directed towards the anode, i.e. to the metal cord, towards which free electrons are also accelerated. Free electrons through collisions provide ionization of additional atoms of the carrier gas, as a result of which the process repeats and self-maintains until a sufficient amount of energy is supplied.

The use of magnetic sputtering makes it possible to increase the deposition rate due to the effect of a magnetic field on electrically charged particles and, in particular, due to the confining effect of electrons near the cathode (s) and increase in plasma density.

For the purposes of the present invention, if magnetron sputtering technology is contemplated, the term “cathode” or (“magnetron”) is used to mean a kit including a coating material (which is a target and preferably has a plate shape) and a plurality of magnets which are located behind the coating material and which create a magnetic trap for charged particles (e.g. argon ions) in front of the coating material. In addition, since the spraying process causes the material to form a coating to heat up, as a rule, the cathode additionally contains a cooling system, usually in the form of multiple channels for the passage of refrigerant.

Alternatively, the magnetron sputtering device comprises a first vacuum deposition chamber and a second vacuum deposition chamber, which are arranged in series, with each of these vacuum deposition chambers being under a first predetermined pressure.

In this case, a device designed to perform magnetron sputtering in a second vacuum deposition chamber can be put into standby mode. Thus, there is no need to interrupt the production process to replace the source of the metal to be deposited on the metal cord, for example a metal cathode during the deposition process. Such replacement of a metal source intended to form said at least one layer of a second metal coating, which should be performed when the metal source is completely used up or when another metal is to be deposited, can preferably be performed in the first of two vacuum deposition chambers , while the second of the two chambers of vacuum deposition is switched to the operating mode, as a result of which shutdowns during production are avoided and provide an increase in productivity and the method of the invention.

In addition to the possibility of replacing the source of metal to be deposited on the metal cord without interrupting the production process similar to that described above, a similar embodiment of the method according to the invention allows to obtain another metal cord essentially simultaneously by switching both chambers to the operating mode and setting another deposition mode or by providing the presence of metal sources having different compositions in two chambers of vacuum deposition, in both of which a working mode is installed m

Preferably, step (c) of treating the surface of the metal cord obtained in step (a) can be performed by subjecting the metal cord to ion etching. To this end, the metal cord is moved through at least one pre-chamber operating at a second predetermined pressure that is lower than said first predetermined pressure, wherein said at least one pre-chamber is located in front of said at least one vacuum deposition chamber along the process.

Preferably, said second predetermined pressure is from 10 ⁻⁵ mbar to 10 ⁻³ mbar, more preferably from 10 ⁻⁴ mbar to 5 × 10 ⁻³ mbar.

By providing the corresponding above-mentioned preferred values of voltage, current and gas pressure, a deposition rate of a metal component in the range of 100 nm / min to 1000 nm / min is preferably achieved depending on the distance between the cathode and anode and on the shape of the cathode. It has been found that the distance between the cathode and the anode, which is in the range of several cm to several tens of cm and depends on the size and shape of the cathode, is particularly preferred in terms of deposition efficiency.

Preferably, said at least one pre-chamber contains the same gas that is used as a carrier gas in at least one vacuum deposition chamber, which makes it possible to use the same type of gas supply as for at least at least one pre-chamber, and for at least one vacuum deposition chamber. More preferably, the aforementioned chemically inert gas is argon.

Alternatively, deposition (b) can be performed by an electric arc technique, which essentially consists of ionic or electronic bombardment of a metal to be deposited, typically at an energy of about 100 eV.

Alternatively, deposition (b) can be performed by using a plasma jet technology essentially consisting of feeding a plasma stream from a finely divided metal powder to be deposited, preferably having a particle size of 0.1 μm. Powders accelerated and heated by plasma until the melting point of the metal is reached are sent to the metal cord to be coated, resulting in a coating consisting of many layers of metal particles deposited on top of each other.

Alternatively, deposition (b) can be performed by plasma-chemical vapor deposition. Such a technology essentially consists of plasma dissociation of the source gases (precursor gases) in a vacuum chamber (for example, at a pressure of 0.15 mbar - 15 mbar). Preferably, the feed gases contain organometallic compounds, for example, such as (hexafluoroacetylacetonate) -copper (trimethylvinylsilane), (hexafluoropentadionate) copper- (vinyltrimethoxysilane), diethylzinc and diphenylzinc, which preferably have low decomposition temperatures of about 25-80 ° C.

Further details regarding these plasma deposition technologies can be found, for example, in international patent applications WO 2004/057053, WO 2005/095668, WO 2005/095078 or WO 2006/002673 mentioned above.

Brief Description of the Drawings

Signs and advantages of the present invention will become apparent through the following detailed description of some exemplary embodiments thereof, presented only as non-limiting examples, that is, a description that relates to the attached drawings, in which:

1 is a sectional view of a portion of a tire in accordance with one embodiment of the present invention;

figure 2 is a schematic view of a device for magnetron sputtering in accordance with one embodiment of the present invention and

3 is a schematic view of a coated metal cord in accordance with one embodiment of the present invention.

Detailed Description of Preferred Embodiments

For simplicity, FIG. 1 shows only a portion of the tire, with the remaining portion that is not represented is identical and symmetrically located with respect to the equatorial plane (x-x) of the tire.

The tire (100) contains at least one layer (101) of the carcass, the opposite side edges of which interact (connected) with the corresponding side structures containing at least one bead core (108) and at least one filler (107) side. The connection between the carcass ply (101) and the bead core (108) is achieved here by folding the opposite side edges of the carcass ply (101) around the bead core (108) so as to form a so-called inversion (101a) of the carcass edges, as shown in FIG. .

Alternatively, the conventional bead core (108) may be replaced by at least one annular insert formed of rubber coated wires arranged in concentric turns (not shown in FIG. 1) (see, for example, European patent application EP 928680, EP 928702 or EP 1137549). In this case, the carcass ply (101) is not bent around said annular inserts, and the connection is provided by a second carcass ply (not shown in FIG. 1) superimposed externally on the first.

The carcass ply (101) typically comprises a plurality of reinforcing elements arranged parallel to each other and at least partially coated with a layer of crosslinked elastomeric material. These reinforcing elements are usually formed from metal cords, which can be made in accordance with the present invention, or from textile fibers, for example from cellulose hydrate, nylon or polyethylene terephthalate.

The carcass ply (101) is typically a radial-type ply, that is, it includes reinforcing elements arranged in a substantially perpendicular direction with respect to the circumferential direction. The bead core (108) is closed in the bead (111) formed along the inner circumferential peripheral edge of the tire (100), by which the tire interacts with the rim (not shown in FIG. 1) forming part of the vehicle wheel. The space bounded by each roll-up (101a) of the frame comprises a bead filler (107), usually made of cross-linked, elastomeric material.

The anti-abrasive strip (109) is usually placed axially outwardly relative to the curl (101a) of the frame edges.

A reinforcing layer (110), known as a “wing tape”, is typically wound around the bead core (108) and the tire filler cord (107) so as to provide at least partial coverage of them. A wing tape consists of a plurality of reinforcing elements that are embedded in a layer of crosslinked elastomeric material. These reinforcing elements are usually made of steel cords, which can be made in accordance with the present invention, or from textile fibers, for example from cellulose hydrate, nylon or polyethylene terephthalate.

The belt structure (105) is superimposed along the circumferential periphery of the carcass ply (101) in a radial direction externally above it. In the specific embodiment shown in FIG. 1, the belt structure (105) comprises two layer (105a) and (105b) of belt, which are superimposed in the radial direction and which include many reinforcing elements, usually metal cords which can be made in accordance with the present invention, wherein said reinforcing elements are parallel to each other in each layer and intersect with reinforcing elements in an adjacent layer, while they are inclined preferably symmetrically of the equatorial plane (x-x) of the tire at an angle of 10 ° to 40 °, preferably 12 ° to 30 °, and covered subjected crosslinkable elastomeric material.

In addition, the belt structure (105) comprises a lateral reinforcement strip (105d), commonly known as a “zero-slope reinforcement strip”, radially superimposed on the second belt layer (105b). Said reinforcing strip (105d) typically includes a plurality of reinforcing elements, typically metal cords, which can be made in accordance with the present invention and which have an elongation at break of 3% to 10%, preferably 3.5% up to 7%, while these reinforcing elements are oriented essentially in the direction along the circumference, forming an angle of several (small) degrees (i.e. 0 °), relative to the equatorial plane (xx) of the tire, and covered with stitched s, elastomeric material. Alternatively, instead of two lateral reinforcing strips, a continuous reinforcing layer (not shown in FIG. 1) may be provided, typically including a plurality of reinforcing elements of the same type as disclosed above, which extends along the axial direction of deployment of said belt structure.

In addition, the breaker structure (105) comprises a third breaker layer (105c) radially superimposed on the second breaker layer (105b) provided with reinforcing elements, typically metal cords, which can be made in accordance with the present invention, this reinforcing elements are parallel to each other, inclined relative to the equatorial plane (xx) of the tire at an angle from 10 ° to 70 °, preferably from 12 ° to 40 °, and covered with crosslinked, elastomeric material. The specified third layer (105 s) of the breaker serves as a protective layer that protects against stones or gravel, which can be caught in the grooves (106b) of the tread and which can cause damage to the layers (105a) and (105b) of the breaker and even the layer (101) frame.

The insert or reinforcing band (104) is located in the support area, that is, the area in which the lateral edges of the tread band (106) are connected to the sidewall (103). Typically, the insert (104) is located between the layer (101) of the frame, the belt structure (105), the tread band (106) and the sidewall (103).

Upon closer examination, it should be noted that the insert (104) contains a part (104a) that is axially inner, located between the belt structure (105) and the tread band (106) and tapers towards the equatorial plane (xx) of the tire, and a portion (104b) that is axially outer is located between the carcass ply (101) and the corresponding sidewall (103) and tapers toward the tire axis of rotation.

An additional insert (112) made of crosslinked elastomeric material is located between the carcass ply (101) and the insert (104).

A tread band (106), the side edges of which are connected to the sidewall (103), is superimposed radially outwardly along the circumference with respect to the belt structure (105). Outside, the tread band (106) has a rolling surface (106a) intended to come into contact with the ground. Circumferential peripheral grooves (106b), which are connected by transverse grooves (not shown in FIG. 1) so as to form a tread pattern that contains many blocks of different shapes and sizes distributed over the rolling surface (106a), are usually made on this surface (106a) )

The sidewall (103) is superimposed externally on the carcass ply (101), and this sidewall extends axially from the outside essentially from the bead (111) to the tread band (106).

In the case of tubeless tires, a rubber layer (102), generally known as a sealing layer, which provides the necessary impermeability to air that is inflated into the tire, can also be provided internally with respect to the carcass ply (101).

As described above, the reinforcing elements of the tire (100) can be manufactured in accordance with the present invention. Accordingly, said reinforcing elements are metal cords, preferably steel cords containing a plurality of elementary metal wires, preferably steel wires twisted together, each elementary metal wire being coated with a layer of a first metal, preferably brass, coating, said metal cord being coated with a layer of a second metal, preferably brass, coating.

As described above, the tire (100) is particularly suitable for heavy vehicles.

Figure 2 shows a schematic view of a magnetron sputtering device.

The magnetron sputtering device (1) contains a first pre-chamber (5), a vacuum deposition chamber (4), two cathodes (3; 3a), a second pre-chamber (5a), two pulleys (6), two elements (9; 9a) for feeding nutrition.

Said vacuum deposition chamber is usually provided with a vacuum pump and with carrier gas supply devices (not shown in FIG. 2).

A metal cord (2) (which “behaves” like an anode), preferably made of steel, is unwound from the feed bobbin (7), it is moved to the first chamber (5) containing argon (for example, under a pressure of 10 ^-4 mbar ) and subsequently into a vacuum deposition chamber (4) containing argon (for example, under a pressure of 2 × 10 ^-3 mbar).

As shown in figure 2, the cathodes (3; 3a) are located on opposite sides relative to the direction of movement of the metal cord (2). Upon closer examination, it should be noted that the first cathode (3) is provided above the metal cord, and the second cathode (3a) is provided below the metal cord (2), while the first and second cathodes (3; 3a) are parallel to each other and are transversal relative to the direction of movement of the metal cord (2).

Alternatively, more than two cathodes may be used, wherein said cathodes will be distributed in the longitudinal direction along the direction of movement of the metal cord inside the vacuum deposition chamber (not shown in FIG. 2).

Alternatively, a cathode located higher with respect to the direction of movement of the metal cord and made of the first metal component, and a cathode located lower with respect to the direction of movement of the metal cord and made of the same first metal component, are installed inside the vacuum deposition chamber along the direction of movement of the metal cords alternately and separately with respect to pairs of cathodes made of a second metal component, so that alternating and separate with ou of the first metal component and second metal component may be deposited on the metal cord (not shown in Figure 2).

In the case where the specified at least one layer of the second metal coating consists of a three-component alloy, the pairs of cathodes made of the third metal component are arranged alternately and separately relative to these first and second cathodes, so that alternating and separate layers from the first, the second and third metal components are deposited on a metal cord (not shown in figure 2).

For the purposes of the present invention, the term “metal component” is used to mean a single metal element or a combination of various metal elements (ie, a metal alloy).

The metal cord (2) passes through the vacuum deposition chamber (4) a predetermined number of times, so that the central deposition path preferably improves without noticeably increasing both the length of the vacuum chamber and the number of cathodes that are necessary to ensure that the metal cord (2) a predetermined layer thickness of the second metal coating will be provided while maintaining a high speed of movement of the metal cord (2), for example, a component of the order of 50-150 m / min, preferably from 80 m / min to 120 m / min.

As shown in FIG. 2, a similar deposition path is obtained by moving the metal cord (2) in accordance with the length direction back and forth to cover it a predetermined number of times by means of two pulleys (6) so as to increase the residence time of the metal cord (2) ) in the deposition zone until the specified thickness of the specified at least one layer of the second metal coating is reached.

Power (for example, 12 kW) was supplied to the cathodes (3; 3a) by means of the corresponding elements (9; 9a) for supplying power.

Alternatively, in rectangular shape, the cathodes can be made in the form of round plates, while ensuring the passage of the metal cord through these plates (not shown in FIG. 2).

Alternatively, the cathodes are made in the form of tubes, while ensuring the passage of the metal cord through these tubes (not shown in figure 2).

The coated metal cord (2a) is discharged, leaving the vacuum deposition chamber (4), into a second pre-chamber (5a) containing argon (for example, under a pressure of 10 ^-1 mbar), and winded onto a take-up reel (8).

FIG. 3 shows a schematic view of a coated metal cord in accordance with one embodiment of the present invention.

In particular, FIG. 3 shows a metal cord (1) (presented for linearity, i.e., untwisted for simplicity), coated with a first metal coating layer having a nominal thickness of 0.2 μm, and a second metal coating layer having a nominal thickness of 60 nm .

The metal cord sections (1) indicated by the reference numeral (4) show that in the case of the second metal coating layer (3) having a nominal thickness of less than 30 nm, there may be uncoated zones.

Despite the fact that the present invention has been illustrated, in particular with respect to tires, metal cords in accordance with the present invention can also be used for the manufacture of other reinforced elastomeric industrial products, for example, such as pipes, pipes for high pressure fluids, drive belts or conveyor belts, driving belts or hoses.

The present invention will be further illustrated below by means of a number of illustrative embodiments, which are given solely for demonstration purposes and without any limitation of the present invention.

Example 1

A steel wire (normal strength steel; carbon content: 0.7%) having a diameter of 1.14 mm was coated with a brass coating layer as follows.

First copper layer, alkaline plating bath:

copper pyrophosphate: 100 g / l;

potassium pyrophosphate trihydrate: 400 g / l;

pH value: 8.7, adjusted by pyrophosphoric acid;

cathode current density (copper anodes): 10 A / dm ² ;

bath temperature: 50 ± 5 ° C.

Second layer of copper, acidic plating bath:

copper sulfate: 215 g / l;

sulfuric acid: 60 g / l;

pH value: <1;

cathode current density (copper anodes): 35 A / dm ² ;

bath temperature: 40 ° C.

Third layer of zinc, acidic plating bath:

zinc sulfate heptahydrate: 370 g / l;

sodium sulfate: 30 g / l;

pH value: 3;

cathode current density (zinc anodes): 35 A / dm ² ;

bath temperature: 25 ± 5 ° C.

The coated steel wire thus obtained was heat treated at 440 ° C. for 15 s to allow diffusion of zinc into copper to form a brass alloy. Subsequently, the coated steel wire was etched in phosphoric acid and then washed with water.

Then, a steel wire coated with a 1.5 μm thick brass coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing), using dies made of tungsten carbide until they were obtained a steel wire having a final diameter of 0.20 mm and a brass coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness was determined according to the BISFA-95 method (method E11 / 1) (1995).

For this, three different samples 2 cm long were randomly taken along the entire length of the coated steel wire in the longitudinal direction.

Each sample was placed in a beaker, washed with diethyl ether and subsequently placed in an oven with a temperature of 105 ° C for 30 minutes before drying.

Provided the ability to cool the beaker at room temperature (23 ° C) in a desiccator. Subsequently, each part was weighed, again placed in a beaker and treated with 65% nitric acid solution (65% nitric acid in water) for 30 s until the brass dissolved.

The resulting solution was transferred to a volumetric flask, each part was washed again once with a 65% solution of nitric acid (the content of nitric acid in water was 65%) and washed four times with demineralized water; each washing agent was transferred to the same volumetric flask. Then the volumetric flask was filled with demineralized water.

The solution thus obtained was analyzed by atomic absorption spectroscopy (AAS) using a Perkin Elmer AAnalyst 200 atomic absorption spectrophotometer.

The concentration (in parts per million) of copper and zinc was calculated using computer software, and the nominal thickness of the wire coating layer (WCT) was calculated by the following formula:

(WCT) (μm): d × 0.235 × brass mass (g / kg),

Where:

- d is the diameter of the coated steel wire;

- 0.235 is a constant;

- mass of brass = [(the number of parts Cu per million + the number of parts Zn per million) × 0.2] / W, where W is the mass of the sample of coated steel wire in grams.

Steel cord of steel of normal strength with a construction of 1 + 18 × 0.20 (that is, one strand of one metal wire and one strand of eighteen metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.20 mm ) was obtained by twisting coated steel wires obtained as described above.

The resulting steel cord was subjected to ion etching by feeding it in a substantially continuous manner to a first chamber containing argon under a pressure of 10 ^-4 mbar.

Subsequently, the steel cord was transferred in a substantially continuous manner to a magnetron sputtering apparatus containing a vacuum deposition chamber containing argon as a carrier gas at a pressure of 2 × 10 ⁻³ mbar, including two plate rectangular cathodes (45 × 7 × 1 cm) made of brass, alternately located on opposite sides of the steel cord. The distance between each of these cathodes and a steel cord (i.e., an anode) was 29 mm.

The steel cord was fed in a substantially continuous manner to a similar vacuum deposition chamber at a speed of 100 m / min and 40 passage of the steel cord was provided along its path within the vacuum deposition chamber. Power with a power of 12 kW was supplied to the brass cathodes. Subsequently, a coated steel cord was allowed to pass through a second pre-chamber containing argon under a pressure of 10 ^-1 mbar.

At the end of the deposition operation, a second brass coating layer was obtained (with a copper content of 63 weight percent; zinc content of 37% by weight) having a nominal thickness of 90 nm.

The specified nominal thickness was determined according to the BISFA-95 method (method E11 / 1) (1995).

For this, three different samples 2 cm long were randomly taken along the entire length in the longitudinal direction of the coated steel cord made of normal strength steel.

Each sample was untwisted, placed in a beaker, washed with diethyl ether and subsequently placed in an oven with a temperature of 105 ° C for 30 minutes before drying.

Provided the ability to cool the beaker at room temperature (23 ° C) in a desiccator. Subsequently, each part was weighed, again placed in a beaker and treated with 65% nitric acid solution (65% nitric acid in water) for 30 s until the brass dissolved.

The resulting solution was transferred to a volumetric flask, each part was washed again once with a 65% solution of nitric acid (the content of nitric acid in water was 65%) and washed four times with demineralized water; each washing agent was transferred to the same volumetric flask. Then the volumetric flask was filled with demineralized water.

The solution thus obtained was analyzed by atomic absorption spectroscopy (AAS) using a Perkin Elmer AAnalyst 200 atomic absorption spectrophotometer.

The concentration (in parts per million) of copper and zinc was calculated using computer software, and the nominal thickness of the cord coating layer (CCT) was calculated by the following formula:

(CCT) (μm): [d × 0.235 × brass mass (g / kg)] - (WCT),

Where:

- d is the diameter of the coated steel cord;

- 0.235 is a constant;

- brass mass = [(number of parts Cu per million + number of parts Zn per million) × 0.2] / W, where W is the mass of the coated steel cord sample in grams;

- WCT (thickness of coated steel wire) - calculated as described above.

Example 2

A steel wire (normal strength steel; carbon content: 0.7%) having a diameter of 1.14 mm was coated with a brass coating layer as follows.

First copper layer, alkaline plating bath:

copper pyrophosphate: 100 g / l;

potassium pyrophosphate trihydrate: 400 g / l;

pH value: 8.7, adjusted by pyrophosphoric acid;

cathode current density (copper anodes): 10 A / dm ² ;

bath temperature: 50 ± 5 ° C.

Second layer of copper, acidic plating bath:

copper sulfate: 215 g / l;

sulfuric acid: 60 g / l;

pH value: <1;

cathode current density (copper anodes): 35 A / dm ² ;

bath temperature: 40 ° C.

Third layer of zinc, acidic plating bath:

zinc sulfate heptahydrate: 370 g / l;

sodium sulfate: 30 g / l;

pH value: 3;

cathode current density (zinc anodes): 35 A / dm ² ;

bath temperature: 25 ± 5 ° C.

The coated steel wire thus obtained was heat treated at 440 ° C. for 15 s to allow diffusion of zinc into copper to form a brass alloy. Subsequently, the coated steel wire was etched in phosphoric acid and then washed with water.

Then, a steel wire coated with a 1.5 μm thick brass coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing), using dies made of tungsten carbide until they were obtained a steel wire having a final diameter of 0.20 mm and a brass coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Steel cord of steel of normal strength with a construction of 1 + 18 × 0.20 (that is, one strand of one metal wire and one strand of eighteen metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.20 mm ) was obtained by twisting coated steel wires obtained as described above.

The resulting steel cord was subjected to ion etching by feeding it in a substantially continuous manner to a first chamber containing argon under a pressure of 10 ^-4 mbar.

Subsequently, the steel cord was transferred in a substantially continuous manner to a magnetron sputtering apparatus containing a vacuum deposition chamber containing argon as a carrier gas at a pressure of 2 × 10 ⁻³ mbar, including two plate rectangular cathodes (45 × 7 × 1 cm) made of zinc-manganese alloy, alternately located on opposite sides of the steel cord. The distance between each of these cathodes and a steel cord (i.e., an anode) was 29 mm.

The steel cord was fed in a substantially continuous manner to a similar vacuum deposition chamber at a speed of 100 m / min and 40 passage of the steel cord was provided along its path within the vacuum deposition chamber. Power with a power of 12 kW was supplied to the cathodes of zinc-manganese alloy. Subsequently, a coated steel cord was allowed to pass through a second pre-chamber containing argon under a pressure of 10 ^-1 mbar.

At the end of the deposition operation, a second coating layer of a zinc-manganese alloy was obtained (with a zinc content of 98 weight percent; a manganese content of 2 weight percent) having a nominal thickness of 90 nm.

The indicated nominal thickness (CCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in Example 1. The only solution made was the solution used. For this purpose, instead of a solution of nitric acid, a solution of ammonia: hydrogen peroxide (1: 1) was used.

Example 3

A steel wire (high strength steel; carbon content: 0.8%) having a diameter of 1.0 mm was coated with a copper coating layer as follows.

First copper layer, alkaline plating bath:

copper pyrophosphate: 100 g / l;

potassium pyrophosphate trihydrate: 400 g / l;

pH value: 8.7, adjusted by pyrophosphoric acid;

cathode current density (copper anodes): 10 A / dm ² ;

bath temperature: 50 ± 5 ° C.

Second layer of copper, acidic plating bath:

copper sulfate: 215 g / l;

sulfuric acid: 60 g / l;

pH value: <1;

cathode current density (copper anodes): 35 A / dm ² ;

bath temperature: 40 ° C.

The steel wire coated with a 1.5 micron thick copper coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing) using dies made of tungsten carbide until a steel wire was obtained a wire having a final diameter of 0.20 mm and a copper coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Steel cord made of high-strength steel with a construction of 1 + 18 × 0.175 (that is, one strand of one metal wire and one strand of eighteen metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.175 mm) was obtained by twisting coated steel wires obtained as disclosed above.

The resulting steel cord was subjected to ion etching by feeding it in a substantially continuous manner to a first chamber containing argon under a pressure of 10 ^-4 mbar.

Subsequently, the steel cord was transferred in a substantially continuous manner to a magnetron sputtering apparatus containing a vacuum deposition chamber containing argon as a carrier gas at a pressure of 2 × 10 ⁻³ mbar, including two plate rectangular cathodes (45 × 7 × 1 cm) made of brass, alternately located on opposite sides of the steel cord. The distance between each of these cathodes and a steel cord (i.e., an anode) was 29 mm.

The steel cord was fed in a substantially continuous manner to a similar vacuum deposition chamber at a speed of 100 m / min and 40 passage of the steel cord was provided along its path within the vacuum chamber. Power with a power of 12 kW was supplied to the brass cathodes. Subsequently, a coated steel cord was allowed to pass through a second pre-chamber containing argon under a pressure of 10 ^-1 mbar.

At the end of the deposition operation, a second brass coating layer was obtained (with a copper content of 63 weight percent; zinc content of 37 weight percent) having a nominal thickness of 90 nm.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 4

A steel wire (normal strength steel; carbon content: 0.7%) having a diameter of 1.14 mm was coated with a zinc coating layer as follows.

Zinc layer, acid plated bath:

zinc sulfate heptahydrate: 370 g / l;

sodium sulfate: 30 g / l;

pH value: 3;

cathode current density (zinc anodes): 35 A / dm ² ;

bath temperature: 25 ± 5 ° C.

The steel wire coated with a 1.5 μm thick zinc coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing) using dies made from tungsten carbide until a steel wire was obtained having a final diameter of 0.20 mm and a zinc coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Steel cord of steel of normal strength with a construction of 3 + 9 + 15 × 0.20 (i.e. one strand of three metal wires, one strand of nine metal wires and one strand of fifteen metal wires, with the three strands twisted together, each elemental metal wire has a diameter of 0.20 mm) was obtained by twisting coated steel wires obtained as described above.

The resulting steel cord was subjected to ion etching by feeding it in a substantially continuous manner to a first chamber containing argon under a pressure of 10 ^-4 mbar.

Subsequently, the steel cord was transferred in a substantially continuous manner to a magnetron sputtering apparatus containing a vacuum deposition chamber containing argon as a carrier gas at a pressure of 2 × 10 ⁻³ mbar, including two plate rectangular cathodes (45 × 7 × 1 cm) made of copper, alternately located on opposite sides of the steel cord. The distance between each of these cathodes and a steel cord (i.e., an anode) was 29 mm.

The steel cord was fed in a substantially continuous manner to a similar vacuum deposition chamber at a speed of 100 m / min and 40 passage of the steel cord was provided along its path within the vacuum chamber. Power with a power of 12 kW was supplied to the copper cathodes. Subsequently, a coated steel cord was allowed to pass through a second pre-chamber containing argon under a pressure of 10 ^-1 mbar.

At the end of the deposition operation, a second copper coating layer was obtained having a nominal thickness of 90 nm.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 5

A steel wire (normal strength steel; carbon content: 0.7%) having a diameter of 1.14 mm was coated with a zinc coating layer as follows.

Zinc layer, acid plated bath:

zinc sulfate heptahydrate: 370 g / l;

sodium sulfate: 30 g / l;

pH value: 3;

cathode current density (zinc anodes): 35 A / dm ² ;

bath temperature: 25 ± 5 ° C.

The steel wire coated with a 1.5 μm thick zinc coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing) by means of dies made of tungsten carbide until steel was obtained a wire having a final diameter of 0.20 mm and a zinc coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Steel cord of steel of normal strength with a construction of 3 + 9 + 15 × 0.20 (i.e. one strand of three metal wires, one strand of nine metal wires and one strand of fifteen metal wires, with the three strands twisted together, each elemental metal wire has a diameter of 0.20 mm) was obtained by twisting coated steel wires obtained as described above.

The resulting steel cord was subjected to ion etching by feeding it in a substantially continuous manner to a first chamber containing argon under a pressure of 10 ^-4 mbar.

Subsequently, the steel cord was transferred in a substantially continuous manner to a magnetron sputtering apparatus containing a vacuum deposition chamber containing argon as a carrier gas at a pressure of 2 × 10 ⁻³ mbar, including two plate rectangular cathodes (45 × 7 × 1 cm) made of brass, alternately located on opposite sides of the steel cord. The distance between each of these cathodes and a steel cord (i.e., an anode) was 29 mm.

The steel cord was fed in a substantially continuous manner to a similar vacuum deposition chamber at a speed of 100 m / min and 40 passage of the steel cord was provided along its path within the vacuum chamber. Power with a power of 12 kW was supplied to the brass cathodes. Subsequently, a coated steel cord was allowed to pass through a second pre-chamber containing argon under a pressure of 10 ^-1 mbar.

At the end of the deposition operation, a second brass coating layer was obtained (with a copper content of 63 weight percent; zinc content of 37 weight percent) having a nominal thickness of 90 nm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Example 6

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ), coated with a layer of brass coating having a nominal thickness of 30 nm, was obtained by performing operations similar to those disclosed in the above example 1.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 7 (comparative)

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ) coated with a brass coating layer having a nominal thickness of 5 nm was obtained by performing operations similar to those disclosed in the above example 1.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 8 (comparative)

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ), coated with a brass coating layer having a nominal thickness of 10 nm, was obtained by performing operations similar to those disclosed in the above example 1.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 9 (comparative)

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ), coated with a brass coating layer having a nominal thickness of 20 nm, was obtained by performing operations similar to those described in the above example 1.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 10

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ) coated with a brass coating layer having a nominal thickness of 60 nm was obtained by performing operations similar to those disclosed in Example 1 above.

The specified nominal thickness (CCT) was determined according to method BISFA - 95 (method E11 / 1) (1995), as shown in example 1.

Example 11 (comparative)

A steel wire (normal strength steel; carbon content: 0.7%) having a diameter of 1.14 mm was coated with a brass coating layer as follows.

First copper layer, alkaline plating bath:

copper pyrophosphate: 100 g / l;

potassium pyrophosphate trihydrate: 400 g / l;

pH value: 8.7, adjusted by pyrophosphoric acid;

cathode current density (copper anodes): 10 A / dm ² ;

bath temperature: 50 ± 5 ° C.

Second layer of copper, acidic plating bath:

copper sulfate: 215 g / l;

sulfuric acid: 60 g / l;

pH value: <1;

cathode current density (copper anodes): 35 A / dm ² ;

bath temperature: 40 ° C.

Third layer of zinc, acidic plating bath:

zinc sulfate heptahydrate: 370 g / l;

sodium sulfate: 30 g / l;

pH value: 3;

cathode current density (zinc anodes): 35 A / dm ² ;

bath temperature: 25 ± 5 ° C.

The coated steel wire thus obtained was heat treated at 440 ° C. for 15 s to allow diffusion of zinc into copper to form a brass alloy. Subsequently, the coated steel wire was etched in phosphoric acid and then washed with water.

Then, a steel wire coated with a 1.5 μm thick brass coating was drawn in a bath containing lubricating oil (emulsion in water at 10 weight percent sizing), using dies made of tungsten carbide until they were obtained a steel wire having a final diameter of 0.20 mm and a brass coating layer having a nominal thickness of 0.2 μm.

The specified nominal thickness (WCT) was determined according to method BISFA-95 (method E11 / 1) (1995), as shown in example 1.

Steel cord of steel of normal strength with a construction of 1 + 18 × 0.20 (that is, one strand of one metal wire and one strand of eighteen metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.20 mm ) was obtained by twisting coated steel wires obtained as described above. Thus, the steel cord thus obtained is devoid of a second metal coating layer.

Example 12 (comparative)

Steel cord of steel of normal strength with a construction of 3 + 2 × 0.30 (i.e. one strand of three metal wires and one strand of two metal wires, while these two strands are twisted together, each elementary metal wire has a diameter of 0.30 mm ) was obtained by performing operations similar to those described in the above Example 11. Thus, the steel cord thus obtained is devoid of a second metal coating layer.

Steel cords of steel of normal strength, similar to those disclosed in the above examples 1-5 (according to the invention) and in example 11 (comparative), were subjected to the following analysis.

Adhesive bonding with crosslinked elastomeric material

Adhesive bonding with crosslinked, elastomeric material was measured on test samples of crosslinked, elastomeric material on a cord of normal strength steel, obtained, as described above, in accordance with ASTM D2229-04 (ASTM - American Society of Testing Materials - American Society for Testing Materials), which measures the force required to pull a cord from a cylinder from a crosslinked elastomeric material.

The “pull force" was measured in Newtons (N) by using an electronic dynamometer. Values were measured both on freshly prepared, crosslinked test specimens and on test specimens after hardening during aging for eight days at a temperature of 65 ° C and a relative humidity (R.H.) of 90%. The “pull” force value of 100 was assigned to the “pull” force measured for the cord obtained in accordance with Example 11 (comparative).

The composition of the elastomeric material from which the crosslinked elastomeric material was formed was as described in Table 1 below, with the proportions being given in weight percent.

TABLE 1 natural rubber one hundred Zno 8 bivalent cobalt 0.2 soot fifty silica 10 resorcinol 3 hexamethoxymethylenemelamine 2,4 dicyclohexylbenzothiazolosulfenamide 1,1 sulfur four trimercaptotriazine 0.5

The data obtained were shown in table 2.

Corrosion resistance

The test samples of steel cord of normal strength were immersed in a 5% aqueous solution of sodium chloride (NaCl) at 25 ° C, and the time (in minutes) for rust formation was measured. The data obtained were shown in table 2.

Uncovered areas (%) of the second metal coating layer

Three different samples from each cord of steel of normal strength with a length of 2 cm were randomly taken along the entire length of the deployment cord of steel of normal strength in the longitudinal direction.

These parts were analyzed by scanning electron microscopy (SEM) using a Philips XL 30 scanning electron microscope, to which the Tracor Northern system was attached, which uses a beryllium filter detector mounted on the lower stage in combination with EDAX analysis (non-dispersive energy, X-ray diffraction analyzer). Spectra were recorded for 30 s at 15 keV.

Each sample was subjected to the above analysis at 400 different points located along the length of its deployment in the longitudinal direction at a distance of 1 cm from each other, and the percentage (in%) of the uncovered zones of the cord of normal strength steel was determined by calculating the percentage of places dots) having an iron content exceeding 95% for each sample. The data obtained were shown in table 2.

TABLE 2 Example The pulling force before aging (indicator) The pulling force after aging (indicator) Corrosion Resistance (min) Uncovered Zones (%) one one hundred one hundred 150 0 2 90 one hundred 210 0 3 one hundred one hundred 90 0 four one hundred one hundred 500 0 5 one hundred one hundred 500 0 eleven (*) one hundred 80 90 3.79 (*): comparative.

In addition, in order to compare the cords of normal strength steel having a second brass coating layer with different nominal thickness, obtained as described in examples 7-9 (comparative), were subjected to the analysis described above to calculate the proportion (in%) uncovered zones. The data obtained were shown in table 3.

TABLE 3 Example Uncovered Zones (%) 7 (*) 2.9 8 (*) 2.1 9 (*) 1,1 6 0 (*): comparative.

In addition, the steel cord of normal strength, made with a coating and obtained as described in the above examples 1, 6 and 10 (in accordance with the invention) and example 12 (comparative), were subjected to the following analysis.

Salt spray coating

To this end, test specimens of steel cord of normal strength, coated and embedded in crosslinked, elastomeric material, the composition of which is given in Table 1 above, were subjected to salt fog in a salt fog chamber operating under the following conditions:

- exposure duration: 0, 8, 12 and 24 days;

- brine: 2.5% aqueous solution of sodium chloride (NaCl);

- fog density: 1.5 cm ³ / h on an area of 80 cm ² ;

- temperature inside the chamber: 40 ° C;

- relative humidity (R.H.) inside the chamber: 100%.

After aging, the test samples were processed by removing the crosslinked elastomeric material, and the percentage (%) of the coating was determined as a percentage: the data obtained were shown in table 4.

TABLE 4 Example Coverage (%) (0 days) Coverage (%) (8 days) Coverage (%) (12 days) Coverage (%) (24 days) one one hundred 95 80 65 6 one hundred 95 95 75 10 one hundred one hundred 95 75 12 (*) one hundred 90 75 60 (*): comparative.

Claims (30)

1. A tire containing at least one structural element comprising at least one metal cord containing a plurality of elementary metal wires twisted together, wherein each elementary metal wire is coated with at least one layer of the first a metal coating, wherein the metal cord is coated with at least one layer of the second metal coating, wherein at least one layer of the second metal coating has a nominal thickness greater than or equal to 30 nm. 2. The tire according to claim 1, in which at least one layer of the second metal coating has a nominal thickness of from 50 to 120 nm. 3. The tire according to claim 2, in which at least one layer of the second metal coating has a nominal thickness of from 70 to 100 nm. 4. The tire according to claim 1, containing:
a frame structure comprising at least one layer of the frame having a substantially toroidal shape and having opposite side edges interacting with respective right and left side structures, wherein each side structure contains at least one bead core and at least one side filler;
a belt structure superimposed in a radial direction from the outside with respect to the frame structure;
a tread band radially superimposed on the belt structure;
two sidewalls imposed laterally on opposite sides relative to the frame structure;
at least one reinforcing layer wound around the bead core and bead filler so as to at least partially cover them,
wherein at least one structural element is a belt structure. 5. The tire according to claim 4, in which the belt structure comprises:
the first layer of the breaker, located radially outside with respect to the carcass structure, provided with reinforcing cords parallel to each other and inclined relative to the equatorial plane of the tire;
a second belt layer radially superimposed on the first belt layer and provided with reinforcing cords parallel to each other and inclined relative to the equatorial plane of the tire in a direction opposite to the direction of inclination of the reinforcing cords of the first belt layer;
at least one reinforcing layer radially superimposed on the second breaker layer, wherein the reinforcing layer includes reinforcing elements oriented substantially in the circumferential direction;
wherein at least one structural element is a first layer of a breaker. 6. The tire according to claim 5, in which at least one structural element is a second layer of the breaker. 7. The tire according to claim 5 or 6, in which at least one structural element is at least one reinforcing layer radially superimposed on the second belt layer. 8. The tire according to claim 5, in which the belt structure further comprises a third belt layer, radially superimposed on at least one reinforcing layer provided with reinforcing elements parallel to each other and inclined relative to the equatorial plane of the tire, at least one structural element is a third layer of the breaker. 9. The tire of claim 8, in which at least one structural element is a third layer of the breaker. 10. The tire according to claim 4, in which at least one structural element is a frame structure. 11. The tire according to claim 4, in which at least one structural element is at least one reinforcing layer wound around the bead core and bead filler so as to at least partially cover them. 12. The tire according to claim 1, in which at least one layer of the second metal coating contains a metal or metal alloy. 13. The tire of claim 12, wherein the metal is selected from: copper, zinc, manganese, cobalt, tin, molybdenum, iron, nickel, aluminum, titanium, tantalum, niobium, zirconium, chromium, or alloys thereof. 14. The tire according to item 13, in which the metal is brass (zinc-copper alloy). 15. The tire according to item 13, in which the metal is copper. 16. The tire according to item 13, in which the metal is a zinc-manganese alloy. 17. The tire according to claim 1, in which the elementary metal wires have a diameter (d) from 0.10 to 0.50 mm 18. The tire according to claim 1, in which the elementary metal wires are made of steel. 19. The tire according to claim 1, in which at least one layer of the first metal coating has a nominal thickness of from 50 to 350 nm. 20. The tire according to claim 1, in which at least one layer of the first metal coating contains a metal or metal alloy. 21. The tire according to claim 18, wherein the at least one layer of the first metal coating is made of brass, copper or zinc. 22. The tire according to item 21, in which at least one layer of the first metal coating is made of brass. 23. A metal cord comprising a plurality of elementary metal wires twisted together, wherein each elementary metal wire is coated with at least one layer of a first metal coating, wherein the reinforcing metal cord is coated with at least one layer of a second metal coating, at least one layer of the second metal coating has a nominal thickness exceeding 50 nm. 24. The metal cord according to item 23, in which at least one layer of the second metal coating has a nominal thickness of from 80 to 120 nm. 25. The metal cord according to item 23 or 24, in which at least one layer of the second metal coating is formed in accordance with any one of paragraphs.11-16. 26. The metal cord according to item 23, in which at least one elementary metal wire is formed in accordance with paragraph 17 or 18. 27. The metal cord according to item 23, in which at least one layer of the first metal coating is formed in accordance with any one of claims 19-22. 28. A method of manufacturing a metal cord, comprising the steps of:
(a) twisting a plurality of elementary metal wires so as to obtain a metal cord, wherein each elementary metal wire is coated with at least one layer of a first metal coating;
(b) depositing at least one layer of the second metal coating on the metal cord obtained in step (a) by plasma deposition technology so as to obtain a metal cord coated with at least one layer of the second metal coating, wherein at least one layer of the second metal coating has a nominal thickness exceeding 50 nm. 29. The method according to p. 28, further comprising a step (c) processing the surface of the metal cord obtained in step (a). 30. A method of manufacturing a reinforced rubber product, comprising the steps of:
(a) twisting a plurality of elementary metal wires so as to obtain a metal cord, wherein each elementary metal wire is coated with at least one layer of a first metal coating;
(b) depositing at least one layer of the second metal coating on the metal cord obtained in step (a) by plasma deposition technology so as to obtain a metal cord coated with at least one layer of the second metal coating;
(c) optionally, treating the surface of the metal cord obtained in step (a);
(d) embedding at least one coated metal cord obtained in step (b) into a crosslinkable elastomeric material so as to obtain a reinforced rubber product.

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