Vulcanizing apparatus and method for vulcanizing and molding tires and method for treating film for tire vulcanizing apparatus

Abstract

A method for treating a film for a device for vulcanizing and molding tires includes: preparing a film (18) that includes an outer surface (20) and an inner surface (21) opposite the outer surface (20); applying at least one inner protective layer (27) on the inner surface (21). The inner protective layer (27) is configured to facilitate sliding between multiple portions in mutual contact of the inner surface (21) of the film (18) and / or between a portion of the inner surface (21) of the film (18) and an element of the vulcanizing device (1) and / or to prevent direct contact with the fluid inside the film (18).

Description

Technical Field

[0001] The present invention relates to a vulcanization apparatus and method for vulcanizing and molding tires, and a method for treating a film used in a tire vulcanization apparatus. The present invention also relates to a film for a tire vulcanization apparatus for vulcanizing and molding tires and a method for extending the working life of the film for a tire vulcanization apparatus.

[0002] The present invention belongs to the field of methods and apparatuses for producing tires for wheels.

[0003] A tire for a wheel generally includes a carcass structure that includes at least one carcass ply having end flaps that engage a corresponding anchoring annular structure. At a radially outer position relative to the carcass structure, a belt structure is connected, which includes one or more belt plies that are radially superimposed relative to each other and relative to the carcass ply, having a cross orientation and / or having a fabric or metal reinforcing cord oriented substantially parallel to the circumferential extension direction of the tire. At a radially outer position relative to the belt structure, a crown is applied, which is also made of an elastomeric material like the other semi-finished products that make up the tire. At least the assembly of the belt structure and the crown forms the crown structure of the tire. Each sidewall made of an elastomeric material is also applied on the lateral surface of the carcass structure, each extending from one of the lateral edges of the crown to the corresponding anchoring annular structure to the bead. In a "tubeless" type of tire, the interior of the carcass ply is covered with an elastomeric material layer preferably having a butyl base, which is commonly referred to as a "liner", having optimal airtightness characteristics and extending from one bead to the other bead.

[0004] The tire production cycle provides a construction process in which various structural components of the tire itself are manufactured and / or assembled on one or more drums. The constructed green tire is transferred to a molding and vulcanization production line, in which the molding and vulcanization process is initiated, which is adapted to define the structure of the tire according to the desired geometry and tread design. Background Art

[0005] The document WO2010 / 016073 under the same applicant discloses a method and apparatus for molding and vulcanizing tires, in which it is set to introduce a green tire into a vulcanization mold. The mold includes a first side plate and a second side plate, an outer cut molding cavity having a ring with a circumferential segment, and an expandable chamber defined by a film located in the molding cavity. The film is fixed to a central telescopic body and expands during the molding and vulcanization process so that it first abuts against the radially inner surface of the green tire, thereby extruding the surface from the outside while heating is applied. At the end of the process, the film is deflated before the vulcanized tire is removed.

[0006] The document WO2015 / 166411 under the same applicant discloses a method for producing a tire for a wheel, in which an outer surface of an expandable chamber for a tire molding and vulcanization device is covered with a crosslinkable polysiloxane composition to facilitate separation of the surface of the expandable chamber from the radially inner surface of the vulcanized tire.

[0007] The document KR20180084278 discloses a method for vulcanizing a tire, in which a release and lubricating substance is applied between the tire and the inflatable membrane of a vulcanizer to facilitate separation of such inflatable membrane from the radially inner surface of the tire at the end of the vulcanization process. Summary of the Invention

[0008] Despite the use of a release agent placed on the outer surface of the membrane, the applicant has observed that in some cases the membrane itself breaks down / deteriorates, such that the membrane has to be frequently replaced to prevent such breakdown / deterioration and to ensure correct vulcanization and quality of the tires produced.

[0009] Therefore, the applicant feels the need to improve the methods and devices for vulcanizing and molding tires.

[0010] The applicant particularly feels the need to reduce the deterioration of the performance of the membrane and to increase the service life of the membrane, in order to reduce the frequency of replacing the membrane in the device, i.e., to increase the number of vulcanization cycles per membrane.

[0011] In this context, the applicant has observed that at the end of each vulcanization process, in order to be able to remove the vulcanized tire and to be able to introduce the green tire to be vulcanized into the vulcanization mold, the pressure in the chamber delimited by the membrane is set lower than the external pressure such that the membrane collapses and is flattened, first reducing its radial bulk. The inner surface of the membrane adheres to the hot components constituting the vulcanization device, such as the above-mentioned central telescopic body, and / or comes into contact with each other. During such collapse and / or subsequent expansion, the applicant has observed that the above-mentioned surfaces slide on each other and / or on the above-mentioned hot components of the vulcanization device.

[0012] The applicant has also observed that such sliding leads to premature wear of the membrane.

[0013] The applicant has also observed that the heated and pressurized fluid can react with the material of the membrane and cause corrosion / wear to it, the fluid being injected into the membrane to expand the membrane and adhere it to the tire during the vulcanization process and the fluid containing chemical reagents and / or dirt particles.

[0014] The applicant has found that the above-mentioned sliding and / or the action of the fluid cause rapid deterioration of the performance of the membrane and / or its rupture.

[0015] The applicant has also found that it is possible to prevent the contact of the hot fluid, and possibly chemical-physical reagents, with the material constituting the membrane through the inner surface of the protective membrane, and / or to promote sliding between multiple parts of its inner surface and / or between its inner surface and the heating elements constituting the vulcanization device, especially during the above-mentioned collapsing and flattening steps, reducing friction and thus increasing the service life of the membrane.

[0016] According to a first aspect, the present invention relates to a method for treating a membrane for a tire vulcanization and molding device.

[0017] Preferably, the device includes a vulcanization mold that defines a vulcanization and molding cavity inside, and the shape of the vulcanization and molding cavity corresponds to the external shape to be imparted to the tire once molded and vulcanized.

[0018] Preferably, the device includes equipment that is operatively associated with the vulcanization and molding cavity and is configured to supply heat to the tire accommodated in the vulcanization and molding cavity to vulcanize the tire.

[0019] Preferably, the device includes a membrane disposed in the vulcanization and molding cavity.

[0020] Preferably, the membrane is movable at least between a contracted configuration and an expanded configuration.

[0021] Preferably, in the contracted configuration, the outer surface of the membrane is spaced apart from the radial inner surface of the tire, and multiple parts of the inner surface of the membrane opposite the outer surface are in contact with each other and / or in contact with the elements of the device.

[0022] Preferably, in the expanded configuration, the outer surface of the membrane engages and presses against the radial inner surface of the tire.

[0023] Preferably, a membrane is prepared that includes an outer surface and an inner surface opposite the outer surface.

[0024] Preferably, at least one inner protective layer is applied on the inner surface.

[0025] The applicant believes that the at least one inner protective layer promotes sliding between multiple parts of the inner surface of the membrane in contact with each other and / or between multiple parts of the inner surface of the membrane and the elements of the device and / or prevents direct contact with the fluid inside the membrane.

[0026] According to a second aspect, the present invention relates to a membrane for a vulcanization device for vulcanizing and molding tires.

[0027] Preferably, an outer surface is provided that is configured to engage the radial inner surface of the tire enclosed in the vulcanization and molding cavity of the vulcanization mold during the vulcanization and molding steps of the tire.

[0028] Preferably, an inner surface is provided that is opposite the outer surface and defines an expandable chamber.

[0029] Preferably, at least one inner protective layer is provided on the inner surface.

[0030] Preferably, the film is movable at least between a shrunk configuration and an expanded configuration under use conditions, wherein in the shrunk configuration, multiple portions of the inner surface of the film contact each other and / or contact elements of the device, and wherein in the expanded configuration, the outer surface of the film engages and presses against the radially inner surface of the tire during the molding and vulcanization steps.

[0031] According to a third aspect, the present invention relates to a device for vulcanizing and molding a tire.

[0032] Preferably, a vulcanization mold is provided that internally defines a vulcanization and molding cavity, the shape of the vulcanization and molding cavity corresponding to the external shape to be imparted to the tire once molded and vulcanized.

[0033] Preferably, a device is provided that is operatively associated with the vulcanization and molding cavity and configured to supply heat to the tire received in the vulcanization and molding cavity to vulcanize the tire.

[0034] Preferably, a film according to the second aspect is provided.

[0035] According to a fourth aspect, the present invention relates to a method for vulcanizing and molding a tire.

[0036] Preferably, the setting is to place the green tire in the vulcanization and molding cavity of a vulcanization mold belonging to a vulcanization device, wherein the shape of the vulcanization and molding cavity corresponds to the external shape to be imparted to the tire once molded and vulcanized.

[0037] Preferably, the setting is to inflate the film disposed in the vulcanization and molding cavity until the outer surface of the film engages and presses against the radially inner surface of the tire.

[0038] Preferably, the setting is to supply heat to the tire in the vulcanization and molding cavity to vulcanize the tire.

[0039] Preferably, the setting is to shrink the film so that it is spaced apart from the radially inner surface of the tire and until multiple portions of the inner surface of the film opposite the outer surface contact each other and / or contact elements of the device.

[0040] Preferably, the setting is to remove the tire from the vulcanization and molding cavity.

[0041] Preferably, at least one inner protective layer is applied on the inner surface of the film.

[0042] According to a fifth aspect, the present invention relates to a method for extending the working life of a film for a vulcanization device according to the third aspect.

[0043] Preferably, the setting is to promote sliding and / or prevent direct contact with the fluid inside the membrane between multiple parts in mutual contact on the inner surface of the membrane and / or between multiple parts of the inner surface of the membrane and the elements of the device by applying at least one inner protective layer on the inner surface of the membrane.

[0044] The applicant believes that the present invention allows reducing the wear of the membrane of the device for vulcanizing and molding tires, slowing down its deterioration and thus extending the effective working life of each single membrane.

[0045] In particular, the applicant believes that compared to using a membrane lacking an inner protective layer / multiple inner protective layers, the present invention allows increasing the number of tires that can be vulcanized and molded by each single membrane.

[0046] The applicant believes that due to the fact of reducing the number of membranes used and due to the fact that there are fewer necessary machine downtimes and less man-hours are required to replace worn-out membranes, the present invention can reduce the costs and time with respect to the molding and vulcanization processes.

[0047] The applicant believes that the present invention also allows improving the reliability of the device as well as the molding and vulcanization processes and reducing the possibility of manufacturing defective tires (to be discarded), because the membrane is less subject to wear and / or breakage.

[0048] The present invention, in at least one of the above aspects, may have one or more of the following preferred features described below.

[0049] Preferably, the membrane comprises or is arranged for applying at least two mutually superposed inner protective layers.

[0050] Preferably, the membrane comprises or is arranged for applying at least three mutually superposed inner protective layers.

[0051] Preferably, the membrane comprises or is arranged for applying four mutually superposed inner protective layers.

[0052] Preferably, the at least one inner protective layer is applied on the entire inner surface or covers the entire inner surface.

[0053] Preferably, it is arranged to cover the entire inner surface with the at least one inner protective layer.

[0054] Preferably, the thickness of the at least one inner protective layer is greater than or equal to 0.02 mm, more preferably greater than or equal to 0.025 mm.

[0055] Preferably, the thickness of the at least one inner protective layer is less than or equal to 0.10 mm, more preferably less than or equal to 0.04 mm.

[0056] Preferably, the thickness of each inner protective layer is greater than or equal to 0.02 mm and less than or equal to 0.10 mm.

[0057] Preferably, the thickness of each inner protective layer is greater than or equal to 0.025 mm and less than or equal to 0.04 mm.

[0058] Preferably, the at least one inner protective layer adheres to the film and moves and deforms therewith.

[0059] Preferably, the at least one inner protective layer is flexible.

[0060] Preferably, the at least one inner protective layer is elastic.

[0061] Preferably, the at least one inner protective layer is anti-adhesive, meaning that a part thereof remains unconnected to another part (when multiple parts of the inner surface of the film come into contact with each other) or unconnected to the elements of the device.

[0062] Preferably, the at least one inner protective layer is anti-wear, meaning that a part thereof tends to slide on another part (when multiple parts of the inner surface of the film come into contact with each other) or on the elements of the device.

[0063] Preferably, the at least one inner protective layer comprises polysiloxane.

[0064] Preferably, the at least one inner protective layer contains substantially crosslinked polysiloxane.

[0065] Preferably, applying the at least one inner protective layer comprises: preparing a substantially crosslinkable composition.

[0066] Preferably, applying the at least one inner protective layer comprises:

[0067] a) covering the inner surface with the substantially crosslinkable composition;

[0068] b) crosslinking the substantially crosslinkable composition on the inner surface.

[0069] Preferably, applying the at least one inner protective layer comprises:

[0070] c) repeating operations a) and b) at least once (for a total of two protective layers).

[0071] More preferably, applying the at least one inner protective layer comprises repeating operations a) and b) at least twice (for a total of three protective layers).

[0072] Even more preferably, applying the at least one inner protective layer comprises repeating operations a) and b) at least three times (for a total of four protective layers).

[0073] Preferably, the at least one inner protective layer is applied before the film is installed on a device for vulcanizing and molding tires.

[0074] Preferably, the substantially crosslinkable composition is a polysiloxane.

[0075] Preferably, the substantially crosslinkable composition comprises: at least one reactive polysiloxane oil, at least one crosslinking agent configured to react with the reactive polysiloxane oil.

[0076] Preferably, operation a) comprises: applying the substantially crosslinkable composition onto the inner surface by means of a sponge or a brush.

[0077] Preferably, operation a) comprises: spraying the substantially crosslinkable composition onto the inner surface.

[0078] Preferably, during the application process, the substantially crosslinkable composition is in liquid or semi-solid form or is substantially gaseous.

[0079] Preferably, operation a) comprises: applying an amount of the substantially crosslinkable composition that is greater than or equal to 5 g, more preferably greater than or equal to 10 g.

[0080] Preferably, operation a) comprises: applying an amount of the substantially crosslinkable composition that is less than or equal to 30 g, more preferably less than or equal to 20 g.

[0081] Preferably, operation a) comprises: applying an amount of the substantially crosslinkable composition that is greater than or equal to 5 g and less than or equal to 30 g

[0082] Preferably, operation a) comprises: applying an amount of the substantially crosslinkable composition that is greater than or equal to 10 g and less than or equal to 20 g.

[0083] Preferably, operation b) comprises: heating the film, more preferably in an oven or a furnace.

[0084] Preferably, the film is placed in an oven at a temperature greater than or equal to 140 °C, more preferably higher than or equal to 160 °C.

[0085] Preferably, the film is placed in an oven at a temperature less than or equal to 180 °C, more preferably less than or equal to 170 °C.

[0086] Preferably, the film is placed in an oven at a temperature greater than or equal to 140 °C and less than or equal to 180 °C.

[0087] Preferably, the film is placed in an oven at a temperature greater than or equal to 160 °C and less than or equal to 170 °C.

[0088] Preferably, the film is placed in the oven for a heating time of greater than or equal to 50 minutes, more preferably greater than or equal to 60 minutes.

[0089] Preferably, the film is placed in the oven for a heating time of less than or equal to 70 minutes, more preferably less than or equal to 65 minutes.

[0090] Preferably, the film is placed in an oven for a heating time of greater than or equal to 50 minutes and less than or equal to 70 minutes.

[0091] Preferably, the film is placed in an oven for a heating time of greater than or equal to 60 minutes and less than or equal to 65 minutes.

[0092] Preferably, a device is provided for removing the film from the oven and allowing it to cool.

[0093] Preferably, the film is cooled at room temperature.

[0094] Preferably, the film is cooled for a cooling time of greater than or equal to 2 hours, more preferably greater than or equal to 3 hours.

[0095] Preferably, the film is cooled for a cooling time of less than or equal to 4.5 hours, more preferably less than or equal to 4 hours.

[0096] Preferably, the film is allowed to cool for a cooling time of greater than or equal to 2 hours and less than or equal to 4.5 hours.

[0097] Preferably, the film is allowed to cool for a cooling time of greater than or equal to 3 hours and less than or equal to 4 hours.

[0098] Preferably, the film includes at least one outer protective layer applied to the outer surface to facilitate separation of the film from the radially inner surface of the vulcanized and molded tire.

[0099] Preferably, a device is provided for applying at least one outer protective layer to the outer surface of the film.

[0100] Preferably, the at least one inner protective layer and the at least one outer protective layer are made of the same substance / material.

[0101] Preferably, a device is provided for applying the same substantially crosslinkable composition to the inner surface and the outer surface.

[0102] Preferably, a device is provided for applying the outer protective layer in substantially the same manner as the inner protective layer is applied.

[0103] Preferably, a device is provided for applying the outer protective layer at least partially simultaneously with the inner protective layer.

[0104] Preferably provided for:

[0105] d) covering the inner surface and the outer surface with the substantially crosslinkable composition;

[0106] e) crosslinking the substantially crosslinkable composition on the inner surface and the outer surface.

[0107] Preferably provided for:

[0108] f) Repeat steps d) and e) at least once.

[0109] Preferably, arrangements are made for repeating operations d) and e) at least twice.

[0110] Preferably, arrangements are made for repeating operations d) and e) at least three times.

[0111] Preferably, the membrane is flexible and more preferably elastic.

[0112] Preferably, the film comprises at least one crosslinkable rubber selected from natural or synthetic rubbers, more preferably a blend with a butyl rubber base.

[0113] Preferably, the thickness of the film is greater than or equal to 3 mm, more preferably greater than or equal to 4 mm.

[0114] Preferably, the thickness of the membrane is less than or equal to 6 mm, more preferably less than or equal to 5 mm.

[0115] Preferably, the thickness of the film is greater than or equal to 3 mm and less than or equal to 6 mm.

[0116] Preferably, the thickness of the film is greater than or equal to 4 mm and less than or equal to 5 mm.

[0117] Preferably, in the rest configuration, ie when it is not under load, the membrane has a tubular shape or a substantially tubular shape or a substantially toroidal shape and resembles the shape of a tyre.

[0118] Preferably, the membrane has a circumferential edge and anchorage appendages anchored or anchorable to a device component.

[0119] Preferably, at least in the expanded or inflated configuration, the membrane has a substantially annular shape replicating the radially inner shape of the tyre.

[0120] Preferably, at least in the collapsed configuration, the membrane is gathered towards a central axis of the device and is at least partially in contact with an element of said device.

[0121] Preferably, at least in the collapsed configuration, a portion of the membrane close to its axisymmetric plane is gathered towards the central axis of the device and is at least partially in contact with an element of said device.

[0122] Preferably, in the rest configuration, the pressure inside the inflatable chamber is equal to the external pressure, and more preferably, the membrane has a barrel shape.

[0123] Preferably, one component of the device comprises an anchoring area for an anchoring attachment of the membrane; wherein said anchoring area is located at the portion of the device configured to receive a tire bead, at least when the vulcanization mould is closed.

[0124] Preferably, the vulcanization mold includes a lower part and an upper part, which can be joined to each other in an axisymmetric plane and are configured to internally delimit a vulcanization and molding cavity.

[0125] Preferably, the vulcanization mold includes a working surface arranged to operate on the bead and sidewall of the green tire to be vulcanized and a circumferential surface arranged to bear against the crown of the green tire to be vulcanized.

[0126] Preferably, the vulcanization mold includes a pair of axially opposed half-shells.

[0127] Preferably, each half-shell includes a working surface arranged to operate on the bead and sidewall of the green tire to be vulcanized.

[0128] Preferably, the vulcanization mold includes a plurality of circumferential segments, where the circumferential segments are adjacent to each other and define a circumferential surface that is arranged to bear against the crown of the green tire to be vulcanized.

[0129] Preferably, a component of the device includes a central rod connected to a pair of spaced-apart flanges; where each flange bears an anchoring area for an anchoring attachment for the membrane.

[0130] Preferably, at least in the contracted configuration, a portion of the membrane near its axisymmetric plane is at least partially in contact with the central rod.

[0131] Preferably, inflating the membrane includes: introducing a hot and pressurized fluid into the inflatable chamber.

[0132] Preferably, the (relative) pressure of the fluid and / or gas for vulcanizing the tire in the inflatable chamber is greater than or equal to 0.15 bar, more preferably greater than or equal to 0.2 bar.

[0133] Preferably, the (relative) pressure of the fluid and / or gas for vulcanizing the tire in the inflatable chamber is less than or equal to 30 bar, more preferably less than or equal to 25 bar.

[0134] Preferably, the (relative) pressure of the fluid and / or gas for vulcanizing the tire in the inflatable chamber is greater than or equal to 0.15 bar and less than or equal to 30 bar.

[0135] Preferably, the (relative) pressure of the fluid and / or gas for vulcanizing the tire in the inflatable chamber is greater than or equal to 0.2 bar and less than or equal to 25 bar.

[0136] Preferably, the device includes a generator and / or tank of hot and pressurized fluid operatively connected to the inflatable chamber.

[0137] Preferably, the hot and pressurized fluid is a gas, more preferably nitrogen.

[0138] Preferably, the hot and pressurized fluid is steam.

[0139] Preferably, causing the film to contract includes: withdrawing hot fluid and possibly air until the pressure in the expandable chamber is reduced such that it drops below the pressure outside the expandable chamber.

[0140] Preferably, the apparatus includes a vacuum pump that is operatively connected or connectable to the expandable chamber to reduce the pressure in the expandable chamber such that it drops below the pressure outside the expandable chamber.

[0141] Preferably, the film of the apparatus is set to be replaced after vulcanizing and molding a number of tires greater than or equal to 300, preferably greater than or equal to 350.

[0142] Preferably, the film of the apparatus is set to be replaced after vulcanizing and molding a number of tires less than or equal to 600, preferably less than or equal to 500.

[0143] Preferably, the film of the apparatus is set to be replaced after vulcanizing and molding a number of tires greater than or equal to 300 and less than or equal to 600.

[0144] Preferably, the film of the apparatus is set to be replaced after vulcanizing and molding a number of tires greater than or equal to 350 and less than or equal to 500.

[0145] Further features and advantages will become clearer from the following detailed description of the preferred but non-exclusive embodiments of the film for tire vulcanization and molding vulcanization apparatus and the method of treating the film for tire vulcanization apparatus according to the present invention. Description of the Drawings

[0146] This description will be elaborated below with reference to the drawings, which are provided only as non-limiting examples, wherein:

[0147] - Figure 1 Shows a part of the vulcanization apparatus for tire vulcanization and molding in a diametrical section at the initial step of the tire vulcanization and molding method;

[0148] - Figure 2 、 3 、4 and 5 schematically show the vulcanization apparatus at corresponding operating steps;

[0149] - Figure 6 Shows the film for the vulcanization apparatus in an undeformed configuration during the processing operation;

[0150] - Figure 7 Shows Figure 6 an enlarged half-section of the film;

[0151] - Figure 8 Shows a further operation for treating Figure 6 the film;

[0152] -Figure 9 , 10 and 11 show the corresponding enlarged portions of the Figure 6 membrane.

[0153] - Figure 12 is a radial half - section view of a tire for a vehicle wheel. DETAILED DESCRIPTION OF THE INVENTION

[0155] Figure 1 shows a part of a vulcanizing device for vulcanizing and molding the tire 2.

[0156] The tire 2 is shown in Figure 12 and basically includes a carcass structure 3 having one / two carcass plies 4a / 4a, 4b. An impermeable elastomeric material or so - called liner 5 is applied inside the carcass plies 4a / 4a, 4b. Two anchoring annular structures 6, each including a so - called bead core 6a carrying an elastomeric filler 6b in a radially outer position, engage with the corresponding end flaps of the carcass plies 4a / 4a, 4b. The anchoring annular structures 6 are integrated in the vicinity of the region usually identified by the name "bead" 7, where there is usually a joint between the tire 2 and the corresponding mounting rim. A belt structure 8 including, for example, belt plies 8a, 8b is circumferentially applied around the carcass plies 4a / 4a, 4b, and a crown 9 is circumferentially superposed on the belt structure 8. The belt structure 8 may be associated with so - called "under - belt inserts" 10, each insert being located between one of the axially opposite end edges of the carcass plies 4a / 4a, 4b and the belt ply structure 8. Two sidewalls 11 extending respectively from the corresponding beads 7 to the corresponding lateral edges of the crown 9 are applied in laterally opposite positions on the carcass plies 4a / 4a, 4b. The portion of each sidewall 11 close to the lateral edge of the crown 9 is called the shoulder of the tire 2. The tire 2 has an axisymmetric plane "M" equidistant from each bead 7 and perpendicular to its axis of rotation "X - X".

[0157] As Figures 1-5 can be seen, the vulcanizing device 1 for vulcanizing and molding the tire 2 includes a vulcanizing mold, which includes a lower part 12 and an upper part 13 interconnected at an axially symmetric plane P. Each of the lower part 12 and the upper part 13 includes a corresponding half - shell 14. The two half - shells 14 are axially opposite. Each half - shell 14 includes a working surface 15 arranged to operate on the bead 7 and the sidewall 11 of the green tire 2. The lower part 12 and the upper part 13 can move axially between a first position where they are spaced apart from each other and a second position where they are adjacent to each other.

[0158] The vulcanization mold includes a plurality of circumferential segments 16 all arranged around the central axis "Y-Y" of the device 1. The circumferential segments 16 are movable between a first position and a second position, in the first position they are circumferentially spaced apart from each other and further from the central axis "Y-Y", and in the second position they are circumferentially adjacent to each other and closer to the central axis "Y-Y". The mutually adjacent circumferential segments 16 define a circumferential surface 17 which is arranged to operate against the crown of the green tire 2 to be vulcanized.

[0159] When the circumferential segments 16 are in the second position and the lower part 12 and the upper part 13 are joined to each other at the axial symmetry plane P, the working surface 15 and the circumferential surface 17 define a vulcanization and molding chamber configured to receive the green tire 2 and having a shape corresponding to the external shape to be imparted to the tire 2 once molded and vulcanized.

[0160] A flexible and elastic membrane 18, for example, made of a blend having a butyl rubber base, is mounted on the device 1. The membrane 18 has an average thickness of, for example, 4.5 mm. When at rest, i.e., not under load, for example simply resting against a surface, the membrane 18 has a shape similar to that of a tire, i.e., a circumferential outer part, and thus has its own central axis "Z-Z". The membrane 18 has a pair of radially inner circumferential edges 19 provided with anchoring attachments which are arranged for anchoring to a component of the device 1. The membrane 18 has an outer surface 20 and an inner surface 21 opposite the outer surface 20. The inner surface 21 mainly points towards its central axis "Z-Z". The outer surface 20 mainly points radially and outwards with respect to its central axis "Z-Z".

[0161] To anchor the membrane 18 to a component of the device 1, the said component of the device 1 includes a central rod 23 which is connected to first and second flanges 24, 25 which are spaced apart from each other and coaxial with the central rod 23. The central rod 23 extends upwards from the half-shell 14 of the lower part 12 and along the central axis "Y-Y" of the device 1. The first flange 24 is located on the half-shell 14 of the lower part 12. The second flange 25 is carried by the upper end of the central rod 23. Each of the said first and second flanges 24, 25 has a circumferential anchoring area or seat which is configured to receive one of the radially inner circumferential edges 19 of the membrane 18. The rod 23 is movable between a raised position and a lowered position.

[0162] When the membrane 18 is mounted on a component of the device 1 and its circumferential edge 19 engages in the circumferential anchoring seat, which is located around the central rod 23 and is radially internal with respect to the circumferential segments 16. In addition, the membrane 18 defines an expandable chamber 26 internally.

[0163] A device known per se, not shown, is configured to move the above-mentioned components of the device 1 between the indicated positions.

[0164] The apparatus 1 further includes a generator and / or a tank for hot and pressurized fluid (up to 30 bar), which is not shown due to its known type and is operatively connected to the expandable chamber 26 to inflate the membrane 18. Such fluid can be, for example, nitrogen or water vapor.

[0165] The apparatus 1 further includes a vacuum pump, which is not shown due to its known type and is operatively connected or connectable to the expandable chamber 26 to reduce the pressure inside the expandable chamber to be lower than the pressure outside the expandable chamber and to collapse / contract the membrane 18. The apparatus 1 further includes an apparatus that is operatively associated with the vulcanization and molding cavity and is arranged to supply heat to the tire 2 accommodated in the vulcanization and molding cavity also through a hot fluid to vulcanize the tire 2.

[0166] The membrane 18 can move between a contracted configuration and an expanded configuration, wherein in the contracted configuration, multiple portions of the inner surface 21 of the membrane 18 contact each other and / or contact the central rod 23, and wherein in the expanded configuration, the outer surface 20 of the membrane 18 contacts and presses against the radially inner surface of the tire 2 during the molding and vulcanization steps.

[0167] The inner protective layer 27, as Figure 7 、 9 shown in 10 and 11, is present on the inner surface 21 of the membrane 18 and is configured to facilitate sliding between multiple portions in the mutual contact of the inner surface 21 of the membrane 18 and / or between multiple portions of the inner surface 21 of the membrane 18 and elements or components constituting the apparatus 1 and to prevent direct contact with the hot fluid introduced into the expandable chamber 26.

[0168] The membrane 18 can also be configured with an outer protective layer applied to the outer surface 20 to facilitate the separation of the membrane 18 itself from the radially inner surface of the molded and vulcanized tire 2. Since the outer protective layer itself is known, it is not shown in the drawings.

[0169] In the non-limiting embodiment described herein, once the membrane 18 made of butyl rubber is constructed, the inner protective layer 27 and possibly the outer protective layer are applied before installing the membrane 18 onto the components constituting the apparatus 1.

[0170] For this purpose and according to the method for treating the membrane for the tire molding and vulcanization apparatus of the present invention, a substantially crosslinkable polysiloxane composition is prepared and this composition is spread or sprayed onto the inner surface 21 and possibly also onto the outer surface 20 by means of a sponge or a brush so as to completely cover it / them and in a uniform manner (as Figure 6 schematically shown in). During application, the substantially crosslinkable composition can be in liquid form or semi-solid form or substantially gaseous.

[0171] For example, the substantially crosslinkable polysiloxane composition comprises at least one reactive polysiloxane oil and at least one crosslinking agent configured to react with the reactive polysiloxane oil. For example, the substantially crosslinkable polysiloxane composition is of the type described in the above-mentioned document WO 2015 / 166411, which is incorporated herein by reference.

[0172] The amount of the substantially crosslinkable polysiloxane composition applied on the inner surface 21 depends on the size of the tire 2. For example, the amount includes between about 5 g and about 30 g.

[0173] Once the composition has been applied, any excess product and / or liquid is removed and the film 18 is placed in an oven 100 or furnace ( Figure 8 ) for a sufficient time to crosslink the above-mentioned composition. For example, the film 18 is maintained at a temperature between about 140 °C and about 180 °C for a heating time between about 50 minutes and about 70 minutes.

[0174] Once the residence time in the oven 100 has ended, the film 18 is removed and cooled at room temperature in an inflated and clean place for a cooling time of about 2 hours to about 4.5 hours. At the end of the process just described, the film 18 has a single inner protective layer 27, as Figure 9 shown. The inner protective layer 27 adheres to the film 18 and follows its movement and deformation, i.e., it is flexible and preferably also elastic, substantially similar to the butyl rubber of the film 18. The thickness "s" of the inner protective layer 27 is, for example, between about 0.025 mm and about 0.10 mm.

[0175] The inner protective layer 27 is anti-adhesive, meaning that a part of it is not connected to another part (when multiple parts of the inner surface 21 of the film 18 come into contact with each other) or not connected to the elements constituting the device 1. The inner protective layer 27 is anti-wear, meaning that a part of it tends to slide on another part (when multiple parts of the inner surface 21 of the film come into contact with each other) or slide on the elements constituting the device 1.

[0176] According to the method for extending the working life of the film for a tire vulcanization and molding device according to the present invention, therefore, by applying at least one inner protective layer 27 on the inner surface 21 of the said film 18, it is provided to facilitate sliding between multiple parts in the mutual contact of the inner surface of the film 18 and / or between multiple parts of the inner surface of the film 18 and the elements constituting the device 1 and / or to prevent direct contact with the fluid inside the film 18.

[0177] There may also be more than one inner protective layer 27 and possibly more than one outer protective layer. According to an embodiment variant, it is provided to apply two ( Figure 10 )、 three ( Figure 11) or even four mutually superimposed inner protective layers 27. The total thickness "s" of the superimposed inner protective layers 27 (from one to four) is, for example, comprised between about 0.02 mm and about 0.4 mm. In such an embodiment variant, in order to produce each inner protective layer 27, the above-described operations (application, crosslinking in an oven and cooling) can be repeated several times.

[0178] In the above embodiment, the same substantially cross-linkable composition is applied on the inner surface 21 and on the outer surface 20. The outer protective layer can be applied using the same application mode as the inner protective layer 27 or using a different mode. For example, provision is made for applying the outer protective layer before, after, or simultaneously with the inner protective layer. Once the composition is applied to both the inner surface 21 and the outer surface 20, the film 18 is placed in an oven 100 and then allowed to cool to achieve simultaneous cross-linking of both the inner protective layer 27 and the outer protective layer.

[0179] Once the membrane 18 is mounted on the parts constituting the device 1 , the device 1 is ready to start the process of vulcanizing and molding the tires 2 that is part of the present invention, ie for molding and vulcanizing tires 2 batch by batch.

[0180] refer to Figures 1-5 , when the lower part 12 and the upper part 13 are in their first spaced-apart positions, the circumferential segments 16 are in a first position in which they are circumferentially spaced-apart from each other and further from the central axis "YY", and the rod 23 is in a raised position ( Figure 2 ), the vacuum pump maintains the pressure inside the expandable chamber 26 lower than the pressure outside said expandable chamber 26. In this way, the membrane 18 remains in a contracted configuration and a portion of it close to its axial symmetry plane is grouped / crushed against the rod 23. The inner surface 21 of the membrane 18, more precisely the portions of the inner protective layer 27, are therefore in contact with each other and / or with the elements constituting the device 1, in particular with the rod 23 and with the first and second flanges 24, 25. The green tire 2 is located between the circumferential segments 16 and against the half-shell 14 of the lower part 12, so that the second flange 25, the rod 23 and the membrane 18 pass through the central opening of the tire 2 delimited by the bead 7. In this configuration, the outer surface 20 of the membrane 18 is spaced apart from the radially inner surface of the green tire 2, i.e. from the liner 5.

[0181] After positioning the green tire 2, the rod 23 and the second flange 25 are brought into the lowered position ( Figure 3 ), at which point the membrane 18 is further grouped / flattened and portions of the inner protective layer 27 are slid over each other, over the rod 23 and over the first and second flanges 24 , 25 .

[0182] At this point, the curing mold is closed, bringing the lower portion 12 and the upper portion 13 into a second position in which they are adjacent to each other, and radially contracting the circumferential segments 16 until they are brought into their second position in which they are circumferentially adjacent to each other and closer to the central axis "YY". When the curing mold is closed, the anchoring areas or seats are positioned at portions of the curing mold configured to receive the beads 7 of the tire 2. A hot and pressurized fluid is introduced into the expandable chamber 26 to inflate the membrane 18 and bring it into an expanded configuration in which the outer surface 20 engages and presses the radially inner surface ( Figure 4 ). In such an expanded or inflated configuration, the membrane 18 has a substantially annular shape that replicates the radially inner shape of the tire 2. Then, heat is given to the tire 2 placed in the vulcanization and molding cavity to vulcanize the tire 2.

[0183] After the necessary time has passed, the vulcanization mold is opened and the membrane 18 is retracted again to separate it from the radially inner surface of the tire 2. For this purpose, the hot fluid is extracted and the pressure in the expandable chamber 26 is made lower than the external pressure. The molded and vulcanized tire 2 is removed from the vulcanization mold and another green tire 2 can be loaded into the vulcanization mold.

[0184] When the device 1 is stopped and in the static configuration, the vulcanization mold is open, the rod 23 is in the raised position and the pressure inside the expandable chamber 26 is equal to the external pressure, ie equal to the atmospheric pressure. The membrane 18 presents a cylindrical configuration ( Figure 5 ).

[0185] Comparison test

[0186] From the tests presented herein it was determined that the presence of one or more inner protective layers 27 allows many molding and vulcanization steps to be performed before the membrane 18 is replaced due to wear or damage, even 300% more cycles than when a membrane 18 lacking the aforementioned inner protective layer 27 is used.

[0187] In the following Table 1 the results of comparative tests carried out on devices A, B, C and D are reported. Device A was equipped with a membrane 18 without any inner protective layer 27. Devices B, C and D were equipped with a membrane with an inner protective layer 27.

[0188] Each inner protective layer 27 includes at least one reactive polysiloxane oil and at least one cross-linking agent configured to react with the reactive polysiloxane oil.

[0189] The number of molding and vulcanization cycles (equal to the number of vulcanized and molded tires) is the number of times the film is significantly worn and / or the film is significantly broken. For films lacking an inner protective layer, the number is normalized to 100.

[0190] Table 1

[0191]

[0192] As can be observed, the number of molding and vulcanization cycles of apparatuses B, C, and D equipped with the membrane 18 with the inner protective layer 27, i.e., the number of vulcanized and molded tires, is much greater than the vulcanization and molding cycle number of apparatus A, even given the same outer protective layer.

[0193] The results of further comparative tests between the membrane with a single inner protective layer 27 according to the present invention and the membrane with three inner protective layers 27 according to the present invention are reported in Tables 2 and 3 below. Also in these tables, the number of molding and vulcanization cycles (equal to the number of vulcanized and molded tires) is the number of times the membrane is significantly worn and / or the membrane is significantly ruptured. In this case, the number for the membrane lacking the inner protective layer is also normalized to 100.

[0194] Table 2

[0195]

[0196]

[0197] Table 3

[0198] Test serial number Normalized number of molding and vulcanization cycles (%) Number of inner protective layers applied 1 100 - 2 279 3 3 248 3 4 474 3 5 302 3 6 171 3 7 348 3 8 403 3 9 313 3 10 366 3 11 393 3

[0199] It can be observed that, on average, the membrane with three inner protective layers has higher performance than the membrane with a single inner protective layer. The applicant believes that if applied multiple times, the substantially crosslinkable composition adheres better to the inner surface and covers it in a more uniform manner.

[0200] Regarding the membrane 18 used in the above tests, a substantially crosslinkable polysiloxane composition was applied on 100% of their outer surfaces 1100 (Chem- Corp.). This membrane 18 has a diameter of 540 mm and is obtained by injection molding and crosslinking of butyl rubber and phenolic resin and has a non-smooth outer surface to improve air leakage during the tire vulcanization process.

[0201] Before covering, impurities were removed from the membrane and the membrane was prepared for the deposition of the composition by using a hydrocarbon solvent. The covering was applied with a sponge and approximately 20 g of the composition was applied to each covering.

[0202] After each covering, each membrane was placed at room temperature for approximately 30 minutes and then put into an oven at 160 °C for 1 h to obtain the crosslinking of the polysiloxane membrane and cooled to room temperature (approx. 25 °C) by allowing it to air dry for at least 4 hours. The treatment of the membrane including covering with the substantially crosslinkable polysiloxane composition and its crosslinking was carried out one to four times.

Claims

1. A method for treating a film for a vulcanization device (1) for vulcanizing and molding tires, wherein the device (1) comprises: a vulcanization mold that defines a vulcanization and molding cavity therein, the shape of the vulcanization and molding cavity corresponding to the external shape to be imparted to a tire (2) once molded and vulcanized; a device operatively associated with the vulcanization and molding cavity and configured to impart heat to the tire (2) received in the vulcanization and molding cavity to vulcanize the tire (2); a film (18) disposed in the vulcanization and molding cavity; wherein the film (18) is movable at least between a contracted configuration and an expanded configuration; wherein in the contracted configuration, the outer surface (20) of the film (18) is spaced apart from the radial inner surface (5) of the tire (2) and wherein multiple portions of the inner surface (21) of the film (18), opposite the outer surface (20), are in contact with each other and / or in contact with elements of the device (1); wherein in the expanded configuration, the outer surface (20) of the film (18) engages and presses against the radial inner surface (5) of the tire (2); wherein the method comprises: preparing a film (18) comprising an outer surface (20) and an inner surface (21) opposite the outer surface (20); applying at least two inner protective layers (27) on the inner surface (21); wherein applying the at least two inner protective layers (27) comprises by preparing a crosslinkable composition, wherein the crosslinkable composition is a polysiloxane composition and comprises at least one reactive polysiloxane oil, at least one crosslinking agent configured to react with the reactive polysiloxane oil and: a) covering the inner surface (21) with the crosslinkable composition; b) crosslinking the crosslinkable composition on the inner surface (21); c) repeating operations a) and b) at least once; thereby applying at least two mutually superposed inner protective layers (27).

2. The method according to claim 1, comprising: covering the entire inner surface (21) with the at least two mutually superposed inner protective layers (27).

3. The method according to claim 1, wherein operations a) and b) are repeated at least twice.

4. The method according to claim 1, wherein operations a) and b) are repeated at least three times.

5. The method according to any one of claims 1 to 4, wherein operation a) comprises: applying the crosslinkable composition on the inner surface (21) by means of a sponge or a brush; or spraying the crosslinkable composition on the inner surface (21).

6. The method according to any one of claims 1 to 4, wherein operation a) comprises: applying an amount of the crosslinkable composition between 5 g and 30 g.

7. The method according to any one of claims 1 to 4, wherein operation b) comprises: heating the film (18) in an oven (100).

8. The method according to claim 7, wherein the film (18) is placed in an oven at a temperature between 140 °C and 180 °C for a heating time between 50 minutes and 70 minutes.

9. The method according to claim 7, comprises: removing the film (18) from the oven (100) and allowing it to cool at room temperature for a cooling time between 2 hours and 4.5 hours.

10. The method according to claim 8, comprising: removing the film (18) from the oven (100) and allowing it to cool at room temperature for a cooling time between 2 hours and 4.5 hours.

11. A method for vulcanizing and molding a tire, comprising: placing a green tire in a vulcanization and molding cavity of a vulcanization mold belonging to a vulcanization device (1), wherein the shape of the vulcanization and molding cavity corresponds to the external shape to be imparted to the tire (2) once molded and vulcanized; inflating the film (18) disposed in the vulcanization and molding cavity until the outer surface (20) of the film (18) engages and presses against the radially inner surface (5) of the tire (2); applying heat to the tire (2) in the vulcanization and molding cavity to vulcanize the tire (2); contracting the film (18) so as to space it apart from the radially inner surface (5) of the tire and until multiple portions of the inner surface (21) of the film (18) opposite the outer surface (20) contact each other and / or contact elements of the device (1); removing the tire from the vulcanization and molding cavity; wherein at least two mutually superimposed inner protective layers (27) are applied to the inner surface (21) of the film (18); wherein applying the at least two inner protective layers (27) includes by preparing a crosslinkable composition, wherein the crosslinkable composition is a polysiloxane composition and contains at least one reactive polysiloxane oil, at least one crosslinking agent configured to react with the reactive polysiloxane oil, and: a) covering the inner surface (21) with the crosslinkable composition; b) crosslinking the crosslinkable composition on the inner surface (21); c) repeating operations a) and b) at least once; thereby applying the at least two mutually superimposed inner protective layers (27).

12. The method according to claim 11, wherein the at least two mutually superimposed inner protective layers (27) are applied over the entire inner surface (21).

13. The method according to claim 11, wherein the thickness of the at least two mutually superimposed inner protective layers (27) is greater than 0.02 mm.

14. The method according to claim 12, wherein the thickness of the at least two mutually superimposed inner protective layers (27) is greater than 0.02 mm.

15. The method according to any one of claims 11 to 14, wherein the thickness of the at least two mutually superimposed inner protective layers (27) is less than 0.1 mm.

16. The method according to any one of claims 11 to 14, wherein the at least two mutually superimposed inner protective layers (27) are elastic.

17. A film for a vulcanization device (1) for vulcanizing and molding a tire, comprising: an outer surface (20) configured to engage the radially inner surface (5) of the tire (2), and in the steps of vulcanizing and molding the tire (2), the tire (2) is enclosed in a vulcanization and molding cavity of a vulcanization mold; an inner surface (21) opposite the outer surface (20) and defining an expandable chamber (26); The membrane (18) is movable at least between a contracted configuration and an expanded configuration under use conditions, wherein in the contracted configuration, multiple portions of the inner surface (21) of the membrane (18) contact each other and / or contact elements of the device (1), and wherein in the expanded configuration, the outer surface (20) of the membrane (18) engages and presses against the radially inner surface (5) of the tyre (2) during the vulcanization and moulding steps; wherein the membrane comprises at least two inner protective layers (27) that are superposed and applied on the inner surface (21); wherein applying the at least two inner protective layers (27) comprises by preparing a crosslinkable composition, wherein the crosslinkable composition is a polysiloxane composition and comprises at least one reactive polysiloxane oil, at least one crosslinking agent configured to react with the reactive polysiloxane oil, and: a) covering the inner surface (21) with the crosslinkable composition; b) crosslinking the crosslinkable composition on the inner surface (21); c) repeating operations a) and b) at least once; thereby applying the at least two inner protective layers (27).

18. The membrane according to claim 17, wherein the at least two superposed inner protective layers (27) are applied over the entire inner surface (21).

19. The membrane according to claim 17, wherein the thickness of the at least two superposed inner protective layers (27) is greater than 0.02 mm.

20. The membrane according to claim 18, wherein the thickness of the at least two superposed inner protective layers (27) is greater than 0.02 mm.

21. The membrane according to any one of claims 17 to 20, wherein the thickness of the at least two superposed inner protective layers (27) is less than 0.10 mm.

22. The membrane according to any one of claims 17 to 20, wherein the at least two superposed inner protective layers (27) are elastic.

23. The membrane according to any one of claims 17 to 20, comprising at least one outer protective layer applied on the outer surface (20) to facilitate separation of the membrane (18) from the radially inner surface (5) of the vulcanized and moulded tyre (2); wherein the at least two inner protective layers (27) and the at least one outer protective layer are made of the same material.

24. A vulcanization device (1) for vulcanizing and moulding a tyre comprising: a vulcanization mould that defines a vulcanization and moulding cavity internally, the shape of the vulcanization and moulding cavity corresponding to the external shape to be imparted to the tyre (2) once moulded and vulcanized; a device that is operatively associated with the vulcanization and moulding cavity and is configured to supply heat to the tyre (2) received in the vulcanization and moulding cavity to vulcanize the tyre (2); a membrane (18) according to any one of claims 17 to 23.

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