IT202100010424A1 - "STRUCTURE OF LAYERED FABRIC WITH ELASTOMERIC MATERIAL AND METHOD OF PRODUCTION OF THE SAME" - Google Patents

Description

PATENT FOR INDUSTRIAL INVENTION entitled:

? STRUCTURE OF LAYERED FABRIC WITH ELASTOMERIC MATERIAL AND METHOD OF PRODUCTION OF THE SAME?

DESCRIPTION

The present invention refers to a multilayer fabric structure and, more precisely, to a multilayer fabric structure covered with an elastomeric synthetic material which in turn has a deposited metallic outer layer.

The invention also refers to the method of producing this type of multilayer fabric structure.

State of the art

To date, rubberized fabrics or fabrics that include elastomeric material are widely known for various applications, which can be listed here:

- construction of tanks for water or other liquids such as fuel, chemicals, etc. typically being such tanks of various shapes and sizes depending on the specific use;

- cushions (bladders) for storing or transporting fuel;

- volumetric compensator cushions (air cells) which basically have air inside and can expand or contract depending on the circumstances;

- inflatable boats used in the nautical sector;

- inflatable camp tents.

Typically, such multilayer fabrics have a textile layer which is completely covered by an elastomeric compound that ? chosen by the manufacturer on the basis of the specific characteristics required for the intended use. Said elastomeric compounds (compounds) are normally applied to the textile insert on one or both sides through the various production stages, as follows:

a) Treatment of purging and thermosetting of the textile insert;

b) Corona treatment of the textile insert; c) Impregnation of the raw fabric with RFL treatment;

d) Coating of adhesive solutions on the fabric; e) Calendering of the cover on the fabric; f) Vulcanization in autoclave or ?rotocure?. Each of the above phases suitable for obtaining certain specific characteristics relating to the type of adhesion between fabric and compound, the thickness, and the state of the compound (ie raw or vulcanised).

The choice of polymers and the formulation of the relative compounds? aimed at coping with various environmental circumstances or project requirements. Pi? specifically, the choice of formulation pi? suitable ? given by the following variants:

- hardness/density?/plasticity?/viscosity?

- elastic modulus/elongation/deformation; - resistance to high and low temperatures; - resistance to swelling in contact with solvents or other liquids;

- behavior under static or dynamic loads; - laceration / abrasion;

- resistivity / stiffness? dielectric;

- conductivity? thermal / expansion;

- resistance to permeability? to fluids;

- fire resistant.

? known that the? activity? formulation of the compounds is extremely laborious, and the results obtained sometimes represent a compromise of characteristics/performances derived from opposing needs.

The main problem that is not ? resolvable derives from the fact that all the researched and obtained formulations always remain within the field of organic materials, which present the strengths and weaknesses of this family of materials.

In order to solve the aforementioned drawback, various solutions have been proposed, which provide for the possibility coupling the elastomeric layer with a metal layer.

An example of such a solution is described in document EP2500168A1 which provides a rubber and metal laminate product comprising NBR and metal, which two materials are bonded to each other via a phenolic resin based adhesive. According to this document, the laminate has excellent friction and wear resistance at high temperatures, and less decrease in adhesive strength after immersion in water or antifreeze solution to effectively prevent peeling caused by it.

In addition, JPH06335990A provides a rubber laminated metal plate which has excellent antifreeze resistance and is ? effectively used as a gasket material or the like. A method is disclosed for producing a gasket material, which is formed by a layer of vulcanized rubber starting from a rubber solution containing NBR, zinc peroxide, sulfur or a vulcanization accelerator. The gasket material obtained in this way has improved rubber strength and adhesive strength with the primer, and also under conditions of high impact and friction.

These proposed solutions have some drawbacks. A disadvantage ? given by the mode? with which the sheet (or layer) of metal ? applied to the elastomeric material. In fact, perfect adhesion is never guaranteed during continuous operation.

The present invention intends to solve the aforementioned disadvantages by providing a stratified fabric structure of elastomeric material which provides a fabric covered by elastomeric material to which coupled a layer of metal through PVD technology, and through which technology? It is possible to create a layer of metal of variable thickness according to particular needs.

According to the present invention the metal layer can be made integral to the layer of elastomeric material through the use of special adhesives applied to the layer of elastomeric material before the PVD treatment.

The aforesaid adhesives are chosen according to the type of elastomeric substrate of which to prepare the adhesion of the metal to be deposited before the PVD procedure.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a layered fabric structure of elastomeric material which comprises a first layer of textile fabric, at least a second layer of elastomeric material integral with said first layer of textile fabric, and a third layer of metallic material integral with said second layer of elastomeric material.

Thus, the present invention provides a layered fabric structure of elastomeric material substantially according to the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Will I come now provided a detailed description of two preferred embodiments of a layered fabric structure of elastomeric material of the present invention, given by way of non-limiting example, with reference to the accompanying figures, in which:

Figure 1 ? a schematic cross-sectional view illustrating a structure of stratified fabric of elastomeric material for use in shockproof flexible tanks for containing fuel according to the state of the art;

Figure 2 ? a schematic cross-sectional view illustrating the structure of stratified fabric of elastomeric material for use in flexible shockproof tanks for containing fuel according to a first embodiment of the present invention;

Figure 3 ? a schematic cross-sectional view illustrating the layered fabric structure of elastomeric material for use in Air Cells in contact with mineral oils and according to a second embodiment of the present invention; And

Figure 4 ? a schematic view illustrating the method for making a layered fabric structure of elastomeric material for use in Air Cells in contact with mineral oils according to the present invention.

With reference now to figure 1, it schematically illustrates in cross section the structure of a stratified fabric of elastomeric material for the construction of shockproof flexible tanks for containing fuel in racing cars or for use in the nautical or aeronautical sector and according to the state of the art.

Typically, the shockproof flexible tanks for the uses described above are fuel containers of various shapes and sizes, which are used in order to reduce the risk of the tank breaking in the event of a collision with the subsequent spillage of fuel and the possible development of fire .

For the above purpose and as illustrated in the figure, ? a multilayer structure 1 is provided for the construction of walls 2 of a fuel containment tank, the walls 2 being made of a structure of stratified fabric of elastomeric material in the raw state, which structure provides a first layer 3 of textile material preferably made nylon (or polyester, or polyamide, or Kevlar, or Zylon), and a second layer 4 of elastomeric material (typically a NBR or NBR/HNBR, CR, SBR, EPDM, ECO compound) which totally covers the first textile layer on both surfaces.

The second layer 4 in NBR totally covers the first textile layer 3 and is in the raw state when it is adhered to the aforementioned first layer 3 through a third layer 5 of RFL type impregnation adhesive solution and with the subsequent use of specific adhesives ( such as, for example, those already known under the commercial name CILBOND 22 produced by CILBOND, or CHEMOSIL or CHEMLOK produced by LORD).

Subsequently ? planned activity? of spreading or calendering of the multilayer structure, and is so? obtained a layer of rubberized fabric that pu? be wound on a reel. The coil is then conveyed to the next station for the cutting and forming process for the packaging of the tank and final vulcanization and according to the modalities? already known to the state of the art. Obviously after the? activity? packaging of the tank and vulcanization cycle in the autoclave, the material acquires the final physical characteristics.

With reference now to figure 2, a structure of stratified fabric of elastomeric material is schematically illustrated in cross section according to a first embodiment of the present invention, and for the application of the construction of shockproof flexible tanks for containing fuel in automobiles from competition.

? good here to specify that for reasons of clarity, equal parts will have equal numbers and their detailed description is omitted here since? already provided previously.

According to this first embodiment of the invention, ? initially foreseen a structure of stratified fabric 1 of elastomeric material in the modalities? above and with reference to figure 1.

The structure of rubberized fabric 1 cos? obtained is subsequently unrolled from the reel and passed through a machine for the PVD treatment (i.e. by "sputtering") and for the deposition of a metal layer 6 on a surface of the rubberized fabric 4.

Pi? precisely, ? it is necessary to point out here that the rubberized fabric 4 before passing through the PVD process of deposition of the metal layer 6 in the appropriate equipment, is subjected to a surface treatment by applying an adhesive 7 on the surface with a specific formulation (such as, for example, the adhesive called CHEMOSIL 211 produced by LORD). After the deposition of the aforementioned adhesive 7 on the surface of the rubberised fabric 4? therefore the passage in the machine for the deposition of the metal layer 6 by means of PVD technology is foreseen.

According to one aspect of the present invention, the metal layer 6, which for this embodiment is preferably chosen in Aluminum, can reach thicknesses ranging from a few thousandths of a millimeter up to a few hundredths of a millimetre.

According to another aspect of the present invention, the metal layer 6 can be deposited on a single surface or on both surfaces of the rubberized fabric 4 and according to the use.

Once the deposition of the metal is finished, the structure 1 of stratified fabric of metallized elastomeric material can be wound again on a second reel to then be conveyed to the next station for the cutting and forming process for the packaging of the tank and final vulcanization and according to the methods? already known to the state of the art.

It should be noted that the metallized surface 6 will be? applied on the internal walls 2 of the tank (i.e. those in direct contact with the fuel).

Alternatively, the metal layer 6 can be deposited on both surfaces of the layer of elastomeric material 4 thus obtaining? a structure 1 of stratified fabric of elastomeric material covered on both surfaces by a metal layer 6.

This solution also has an improved resistance to atmospheric agents, much higher than the most? performing fluorinated polymers.

? here it is necessary to point out that in the application of the structure 1 of stratified fabric of elastomeric material of the present invention dedicated to the realization of a flexible tank starting from a metallized rubberized fabric, it is necessary to highlight foreseen a packaging process of the same due to the fact that it is almost? impossible to carry out the metallization of large-sized products, as it would require machines for the PVD deposition of even larger dimensions? large and therefore very expensive, such that their cost and their management would make the metal deposition process on the finished product uneconomical.

Therefore, the best solution that presents itself and that surely is? the most valid for the creation of large-sized products with metallized rubberized fabrics, ? to carry out an activity? of packaging, through the union of previously cut panels, from the roll of fabric already? metallic and according to predefined shapes.

In this activity? ? determining the knowledge of the modalities? operational and above all the knowledge of the adhesives to be used and their correct sequence and modality? of application.

With reference now to figure 3, a second embodiment of the stratified fabric structure of elastomeric material of the present invention, applied to the production of ?cushions? for conservators (so-called Air Cells) used in oil expansion vessels for power and/or distribution transformers.

Also in this case, for illustrative clarity, equal parts will have equal numbers and their detailed description will be omitted here why? already provided previously.

? it is good to point out here that the so-called ?conservatives? they are metal containers of oil of various shapes and having the function of expansion vessels suitable for compensating the considerable volumetric variations of the cooling oil of the circuits for transforming the voltage of the electric current during the aforesaid activity. This volumetric expansion/contraction of the oil takes place through a vent opening but in the absence of contact with the air, since? the latter carries humidity? and oxygen and/or other polluting substances (acid rain, dust, etc.) which cause a strong degradation of the oil with a consequent strong reduction in the efficiency of the transformation from high to low voltage.

The so-called cushions (Air Cells) are placed between the surface of the oil and the atmosphere, and are typically made from panels of rubberized fabric joined together and of various shapes and sizes. The wall of the said cushions in contact with the oil must resist the high temperatures of the oil for long periods of time.

According to the present invention and as illustrated in figure 3, a structure 1 of stratified fabric of elastomeric material is provided for making a cushion, and in which ? a first layer 3 of textile fabric is provided which? covered on both of its surfaces by a second layer 4 of elastomeric material made integral with the first by applying a layer 5 of an impregnation solution (process already described with reference to the first embodiment of the invention).

So how? As can be understood in the figure, the surface of the cushion designed to come into contact with the surface of the oil in turn has a third layer 6 of metallic material applied by PVD process. Purpose ? first of all, the arrangement on the surface of the elastomeric layer 4 of a layer 7 of adhesive such as, for example the adhesive with formulation known as CHEMOSIL 211 (produced by LORD) and subsequently the deposition of the metal layer 6 using PVD technology (as previously described).

? it is necessary to point out here that through the present invention a structure 1 of stratified fabric of elastomeric material is provided for the realization of a cushion which allows to obtain resulting performances which would not be obtainable otherwise. Indeed, the so-called ?Air Cell? they are normally several meters long (that is, from 2 to 7 meters and more). ? it is well understandable that the dimensions of these artifacts do not allow processing with normal PVD machines, but only through activities? of packaging.

With reference now to Figure 4, verr? now provided a description of the production process of the structure 1 of stratified fabric of elastomeric material with a metallized surface according to the present invention, and referring to the use of the aforementioned stratified fabric for the production of a so-called ?Air Cell? cushion.

The process involves the following stages:

1) First, the rubberised and metallised fabric 1 is cut from the original reel to form a series of panels. The shape and size of each of the panels cut from the metallized rubberized fabric 1 depend on the shape and size of the tank to be made, since the aforementioned panels once assembled through the union of their flaps will give? origin to the tank in the raw state.

2) Then a flap 10 overlapping respective to the metallized side 6 of the panel is cleaned, removing residues of previous processes, or accumulations due to contact, such as oils, greases, oxides, dusts and anything else that could influence the attack . For this activity? ? easily usable chemical cleaning through the use of solvents, such as: MEK, MIBK, Xylol, Ethyl Alcohol.

3) Subsequently, a layer 8 of primer (such as the Chemosil 211 product) is applied to the clean area of the flap 10 as above, by means of a brush, until a uniform layer with a thickness of approximately 10? is formed. The aforementioned layer 8 of primer ? composed of a mixture of polymers, organic compounds and mineral fillers, highly compatible both with the metal layer and with nitrile-based elastomeric compounds, such as to determine with them, during the subsequent vulcanization phase, a strong chemical-physical attack.

4) Then, a layer of elastomeric solution 9 is applied by means of a brush and above the primer layer 8 to form a thickness of 15?. Solution 9? normally obtained by dissolving chips of NBR-based elastomeric compound in solvent (MEK). After drying, the solution 9 has the function of forming a bridge between the primer layer 8 and the NBR compound surface of the rubberized layer 4 of the edge 10 and which will be superimposed on the border of the adjacent metallic rubberized fabric 1. To obtain excellent levels of attack between the aforementioned panels, the solution obtained from the NBR compound is reinforced with ingredients containing phenol-formaldehyde resins.

5) Subsequently, the aforementioned elastomeric solution 9 described in the previous point is also applied to the edge 11 of the panel relating to the non-metallized rubberized fabric side. In this way the two panels can be joined according to the modalities? foreseen by the assembly sequence predetermined at the production engineering level.

6) Then, the overlapping union of the flaps 10 and 11 of a panel on a second respective side-by-side panel is performed, and such as to overlap the end part of the same and thus obtaining a tank 12 made of raw material.

7) At the end of the packaging, the tank 12 with all the assembled panels is subjected to the vulcanization cycle in an autoclave, in order to determine the stabilization of the compound, of the primer and of the solutions applied on it, thus obtaining a finished product with one side rubberised/metallic and the other only rubberised. Alternatively, can be convenient to join rubberized fabric panels with both metallized surfaces, and carried out according to what has been explained in the previous points and with reference to the preparation of the metallized surface.

A tank like this? made using the constructive solution described above, it has the mechanical characteristic of preventing the passage of oxygen from the wall towards the surface of the oil, thus avoiding degradation of the oil.

Furthermore, ? improved the resistance of the cushion wall to fabric aging caused by high temperatures.

Furthermore, the possibility is significantly reduced to almost zero of release of polluting substances for the oil and coming from the plasticizing substances of the compound which constitutes the elastomeric material of the stratified fabric structure.

? it should be pointed out here that the structure of stratified fabric of elastomeric material of the present invention also finds application to other industrial sectors or products such as: containers for both potable and non-potable water; and flexible fuel storage containers.

Furthermore, the present invention ? directed to different types of synthetic compounds (or compounds) according to the use of the multilayer structure 1, and according to the teachings of the state of the art.

Purely by way of non-limiting example, the multilayer structure 1 of the present invention can be made with one of the various types of elastomers 4, including those illustrated in the following table, and which indicate the commercial adhesives to promote adhesion between the compound layer 4 and the metal deposition layering 6.

Table 2

Obviously, for stratifications of metallic materials other than Aluminum, specific adhesives other than those indicated in the table may be provided.

The present invention has numerous advantages.

A first advantage? given by the improved resistance to aging, resistance to sunlight and cracking.

A second advantage? given by the lengthening of the useful life of a product that ? made with the present structure of stratified fabric of elastomeric material.

A third advantage? given by the improved resistance to contact with degrading agents such as chemicals, fuels, detergents and liquids in general.

A fourth advantage? given by the improved resistance to permeability? of fluids.

A fifth advantage? given by the improved conservation of the liquids contained inside the tanks made with the stratified fabric structure of the invention due to the reduction of the possible pollution of the same by the extractable components present in the mixture.

A sixth advantage? given by the improved resistance to abrasion.

A seventh advantage? given by the improved dielectric characteristics.

Claims (10)

PATENT FOR INDUSTRIAL INVENTION entitled: ? STRUCTURE OF LAYERED FABRIC WITH ELASTOMERIC MATERIAL AND METHOD OF PRODUCTION OF THE SAME? CLAIMS 1. Structure (1) of stratified fabric of elastomeric material, comprising a first layer (3) of textile material, a second layer (4) of elastomeric material, said second layer (4) totally covers said first layer (3) of textile on both surfaces, and a third layer (5) of an RFL-type impregnation adhesive solution interposed between said first layer (3) and said second layer (4), characterized in that it also comprises at least a fourth layer (6) of metallic material deposited on the surface of said second layer (4) of elastomeric material by means of a PVD process. 2. Structure (1) of stratified fabric of elastomeric material according to the preceding claim, further comprising a fifth layer (7) of adhesive solution interposed between said second layer (4) and said fourth layer (6) of metallic material. 3. Structure (1) of stratified fabric of elastomeric material according to claim 1 or 2, wherein said first layer (3) of textile material ? chosen from the group that includes the following materials: nylon, polyester, polyamide, Kevlar, Zylon. 4. Structure (1) of stratified fabric of elastomeric material according to claim 1 or 2 or 3, wherein said second layer (4) of elastomeric material ? chosen from the group that includes the following materials: compound NBR, NBR/HNBR, CR, SBR, EPDM, ECO. 5. Structure (1) of layered fabric of elastomeric material according to any one of the preceding claims, comprising two layers (6) of metallic material, each layer of metallic material (6) ? deposited on a respective surface of said layer (4) of elastomeric material, the arrangement being such that said layer (6) of metal ? deposited on both surfaces of said layer (4) of elastomeric material thus obtaining? a structure (1) of stratified fabric of elastomeric material covered on both surfaces by said metal layers (6). 6. Process for making a structure (1) of stratified fabric of elastomeric material comprising a first layer (3) of textile material, a second layer (4) of elastomeric material, said second layer (4) totally covering said first textile layer (3) on both surfaces, a third layer (5) of an RFL-type impregnation adhesive solution interposed between said first layer (3) and said second layer (4), and at least a fourth layer (6) of metallic material deposited on the surface of said second layer (4) of elastomeric material through a PVD process, the process being characterized in that it comprises the following steps: - arrangement of a first layer (3) of textile material (preferably made of nylon (or polyester, or polyamide, or Kevlar, or Zylon); - arrangement of a second layer (4) of elastomeric material (typically a NBR or NBR/HNBR, CR, SBR, EPDM, ECO compound) to cover both surfaces of said first textile layer (3), said second layer (4) of elastomeric material being in the raw state, and interposing a third layer (5) of RFL type impregnation adhesive solution between said first layer (3) and second layer (4); - execution of a calendering step of said multilayer structure (1); - treating the surface of said second layer (4) of elastomeric material by applying a layer of adhesive (7); - deposition on said layer of adhesive (7) of a layer of metallic material (6) by means of PVD technology; And - vulcanization cycle in an autoclave of said stratified fabric structure (1) until the required physical characteristics are obtained. 7. Process for manufacturing a structure (1) of stratified fabric of elastomeric material according to the preceding claim, further comprising a step of winding said structure of rubberized fabric (1) onto a reel after said calendering step and before said step of treating the surface of said layer (4) of elastomeric material by applying said layer of adhesive (7). 8. Process for manufacturing a structure (1) of stratified fabric of elastomeric material according to claim 6 or 7, further comprising a step of winding said structure of rubberized fabric (1) onto a reel following said step of deposition on said layer of adhesive (7) of a layer of metallic material (6) using PVD technology. 9. Process for manufacturing a tank (12) comprising walls (2) made using said structure (1) of stratified fabric of elastomeric material according to claims 1 to 5, the process comprising the following steps: - cutting the layered fabric structure (1) to form a series of panels; - carrying out chemical cleaning through the use of solvents of an edge (10) of a panel at the surface presenting the layer (6) of metallic material of a respective panel; - application on the clean surface of said edge (10) of a uniform primer layer (8), said primer layer (8) comprising a mixture of polymers, organic compounds and mineral fillers; - applying a homogeneous layer of elastomeric solution (9) over said primer layer (8), said solution (9) being obtained by dissolving NBR-based elastomeric compound chips in solvent and reinforced with ingredients containing phenol-formaldehyde resins; - application of said solution (9) on an edge (11) of a second panel; And - execution of overlapping union of said flaps (10,11) of a first panel on a second respective panel; - packaging of a tank (12) consisting of a series of previously assembled and joined panels and in raw material; And - carrying out a vulcanization cycle in an autoclave of said tank (12), and obtaining a finished tank (12) having a metallized surface. 10. Use of a structure (1) made of stratified fabric of elastomeric material according to the preceding claims for making the following articles: - fuel tanks; - air cells; - containers for drinking water; - containers of non-potable water; - flexible containers for storing fuel.