DESC:FIELD OF INVENTION:
The present invention in general relates to a coated/laminated polymeric fabric, that resists tearing, cracking under varying conditions of temperature and humidity even while it is under tension. More particularly, the present invention relates to a waterproof, weldable, completely recyclable coated/laminated fabric having low permeability to air and water, which is applicable for the production of lightweight structures and various applications, such as inflatable pandals, roofing shelters, pond liners, truck tarpaulins etc.

BACKGROUND & PRIOR ARTS:
Coated and laminated fabrics have wide applications across all segments like Agriculture, Construction, Clothing, Geotextiles, Home furnishings, Industrial, Medical, Transportation, Sport/ Leisure, Packaging, etc.

The coating and laminating process have become much more important and novel. Many techniques are used for coating/ laminating a fabric such as yarn coating, spread coating, dipping/ impregnating, calendaring, extrusion coating/ laminating, film to substrate bonding and combination. Coating and laminating the fabric improves the performance, durability, appearance, retention and aesthetic value of the fabric. These include waterproofness, increased abrasion, stain, flame and UV resistance, retro-reflection or fluorescence, anti-microbial materials, etc.

One such application of the coated fabric is in inflatable tents. The inflatable tents have inflatable beams, filled by air, instead of physical support beams. One such inflatable tent is disclosed in US6263617, where inflatable tubes are used to support self-erecting tent.

The current fabric used for inflatable tents are polyester or nylon fabrics coated with PVC and have a very high gsm of 850 and above. This makes the beams heavy and unwieldy. The major drawback with these coated fabrics is the disposal of waste generated after the use of coated fabrics. Recycling of coated fabric is not possible even by applying high temperature or pressure, as the polymers viz PVC used in manufacturing a fibre and coating compound are heterogenous.

Use of coated fabric has been demonstrated in WO2006/109319. WO2006/109319 describes the process for manufacturing protective covers using TPO compound coated PP fabric. The material used for coating the fabric consists of thermoplastic compounds formulated using well known base polymers and manufactured using various types of catalysts-based processes, Engage® and Chemigum®. The fabric is coated through calendaring process.

However, it suffers from several drawbacks for being used.
• The process uses calendaring which restricts the width of the fabric to approximately 1.5 – 2 metres
• The film of engage has to be thick to avoid the inherent porosity in the TPO
• It will leak when exposed to air pressure equivalent to 90cm head of water
• The product is expensive since it uses TPO which is imported.

The present invention overcomes the aforesaid drawbacks by providing a high strength, lightweight, impermeable airtight polymeric fabric with no porosity.

SUMMARY OF INVENTION:
Accordingly, the present invention discloses a coated/laminated waterproof fabric, that resists tearing, cracking under varying conditions of temperature, humidity subjected to tension.

The coated/laminated fabric comprises of plurality of polymeric layer, wherein an intermediate polymeric layer is sandwiched between a first polymeric outer layers and a second polymeric outer layer.

In an embodiment, the intermediate layer may be a homopolymer fabric. Preferably, the homopolymer fabric is a polyolefin such as polypropylene or polyethylene or other polyolefins. The first polymeric outer layer may be a Low-Density Polyethylene (LDPE) in combination with a Thermoplastic Olefin. The second polymeric outer layer may be selected from LDPE, High Density Polyethylene (HDPE), Biaxially Oriented Polypropylene (BOPP), olefin films or a combination thereof.

The fabric of the invention is prepared by a process comprising:
introducing a Fabric Roll into a Feeding System;
preheating the fabric roll from the Feeding system by a Pre-heating unit;
treating a surface of the pre-heated fabric in a Surface treatment unit;
coating the treated fabric by a hot melt coating process by passing it though a Multi-layer hot melt coating unit;
providing coating layers to the Multi-layer hot melt coating unit by a film feeder for the purpose of coating the fabric;
treating the coated fabric through a heat treatment process and calendaring process; and
printing the coated and treated fabric in a printing unit; and
finishing the printed fabric in a finish product roll unit.

Further, for preparation of other side of the laminated fabric the aforementioned are repeated by reversing the drive.

The fabric from the process described herein can be used for construction of various air and water permeability resistant structures e.g. inflatable pandals, roofing shelters, pond liners, truck tarpaulins, transport material etc.
The invention has specific advantages over the fabrics used for inflatable structures. The fabric used in present invention is an impermeable airtight fabric with no porosity, with high strength, light-weight, inexpensive, recyclable and easy to manufacture.

BRIEF DESCRIPTION OF DRAWINGS:
Fig 1 illustrates the schematic process for coated/laminated lightweight, recyclable and inflatable fabric.

The part description of reference numerals is as follows:
Reference Numeral Part description
1 Fabric Roll
2 Feeding system
3 Pre-heating
4 Surface treatment
5 Multi-layer hot melt coating
6 Film feeder
7 Heat treatment
8 Calendering
9 Printing
10 Finish Product Roll

DETAILED DESCRIPTION OF INVENTION:
Accordingly, the present invention discloses a coated/laminated fabric to be used for the production of lightweight inflatable structures.

Accordingly, the present invention discloses a laminated waterproof fabric, that resists tearing, cracking under varying conditions of temperature and humidity even while it is under tension.

The coated/laminated fabric comprises of plurality of polymeric layer, wherein an intermediate polymeric layer is sandwiched between a first polymeric outer layers and a second polymeric outer layer.
In an embodiment, the intermediate layer may be a homopolymer fabric. Preferably, the homopolymer fabric is a polyolefin such as polypropylene or polyethylene or other polyolefins. The first polymeric outer layer may be a Low-Density Polyethylene (LDPE) in combination with a Thermoplastic Olefin. The second polymeric outer layer may be selected from LDPE, High Density Polyethylene (HDPE), Biaxially Oriented Polypropylene (BOPP), olefin films or a combination thereof.

It may be noted that the fabric of the present invention may be made up of plurality of such layers, as in described in the aforementioned para. To further elaborate, the fabric may be imagined to be made of plurality of composite layers, wherein a composite layer comprises of an intermediate polymeric layer sandwiched between a first polymeric outer layers and a second polymeric outer layer.

In an optional embodiment, the first polymeric outer layer and the second polymeric outer layer may be of same material or different material.

The fabric having an intermediate polymeric layer sandwiched between a first polymeric outer layers and a second polymeric outer layer is coated/laminated using T-die extrusion process.

The laminated fabric of the present invention is an impermeable airtight and high width fabric with no porosity, high strength. Further, the laminated fabric of the present invention has ability to withstand air pressures of 0.3 kg/cm2 to 3kg/cm2, lightweight (preferably lower than 1000 gsm), inexpensive, easy to manufacture, recyclable and environment friendly.

The laminated fabric of the present invention maintains a high dimensional stability even in very low to high temperatures of -20°C to 80°C.

The fabric of the invention described herein is prepared by a process having the following sequential steps,
introducing a Fabric Roll into a Feeding System;
preheating the fabric roll from the Feeding system by a Pre-heating unit;
treating a surface of the pre-heated fabric in a Surface treatment unit;
coating the treated fabric by a hot melt coating process by passing it though a Multi-layer hot melt coating unit;
providing coating layers to the Multi-layer hot melt coating unit by a film feeder for the purpose of coating the fabric;
treating the coated fabric through a heat treatment process and calendaring process; and
printing the coated and treated fabric in a printing unit; and
finishing the printed fabric in a finish product roll unit

Further, for preparation of other side of the laminated fabric the aforementioned are repeated by reversing the drive.

The process of producing the fabric of the present invention is exemplified in Fig.1, wherein the schematic process for manufacturing coated/laminated lightweight, recyclable and inflatable fabric is described. The Fabric Roll (1) is introduced into the Feeding System (2). The fabric from the Feeding system (2) is then pre-heated by the Pre-heating unit (3). The surface of the pre-heated fabric is later treated by the Surface treatment unit (4). The treated fabric is coated by the hot melt coating process by passing it though the Multi-layer hot melt coating unit (5). The film feeder (6) provides coating layers to the Multi-layer hot melt coating unit (5) for the purpose of coating the fabric. The coated fabric is then treated through heat treatment (7) and calendaring (8) process. The coated and treated fabric is then printed and rolled by the printing unit (9) and receives finishing in finish product roll unit (10).

Further, the laminated fabric from the finish product roll unit (10) is treated/processed through all the above units (1-10) by reversing the drive for the other side.

The coated/laminated lightweight, recyclable and inflatable fabric produced from the aforesaid process can be used for construction of various air and water permeability resistant structures e.g. inflatable pandals, roofing shelters, pond liners, truck tarpaulins, transport material etc.
,CLAIMS:1. A recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric, useful for construction of air and water permeability resistant structures like inflatables, pandals, roofing shelters, pond liners and truck tarpaulins wherein,
the said fabric comprises a plurality of polymeric layers, wherein an intermediate polymeric layer is sandwiched between a first polymeric outer layer and a second polymeric outer layer.

2. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claim 1, wherein the intermediate layer is a homopolymer fabric.

3. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claim 1, wherein the homopolymer in the intermediate layer is a polyolefin such as polypropylene or polyethylene or other polyolefins

4. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claim 1, wherein first polymeric outer layer is a Low Density Polyethylene (LDPE) in combination with a thermoplastic olefin.

5. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claim 1, wherein the second polymeric outer layer is selected from LDPE, HDPE, biaxially oriented polypropylene (BOPP), olefin films or a combination thereof.

6. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 5, wherein the intermediate polymeric layer is coated/laminated using T-die extrusion process.

7. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated as claimed in claims 1 to 6, wherein the first polymeric outer layer and the second polymeric outer layer is optionally the same material or different.

8. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 7 wherein the said fabric is created to withstand air pressures of 0.3 kg/cm2 to 3 kg/cm2

9. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 8, wherein the said fabric is made lightweight lower than 1000 gsm.

10. The recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 9, wherein the said fabric is made to maintain dimensional stability in a temperature ranging from -20 deg C to +80 Deg C.

11. A process for preparing the recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 10, comprising the sequential steps,
introducing a Fabric Roll into a Feeding System;
preheating the fabric roll from the Feeding system by a Pre-heating unit;
treating a surface of the pre-heated fabric in a Surface treatment unit;
coating the treated fabric by a hot melt coating process by passing it though a Multi-layer hot melt coating unit;
providing coating layers to the Multi-layer hot melt coating unit by a film feeder for the purpose of coating the fabric;
treating the coated fabric through a heat treatment process and calendaring process;
printing the coated and treated fabric in a printing unit; and
finishing the printed fabric in a finish product rolling unit.

12. The process for producing the recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 1 to 11, wherein the process of producing the fabric is as exemplified in Fig.1, wherein as per the schematic process for manufacturing coated/ laminated lightweight, inflatable fabric is as described in claim 1, comprising the steps of
- introducing the Fabric Roll (1) into the Feeding System (2);
- preheating the fabric from Feeding system (2) by the Pre-heating unit (3);
- treating the surface of the pre-heated fabric in the Surface treatment unit (4);
- coating the treated fabric by hot melting process by passing it though the Multi-layer hot melt coating unit (5), wherein the film feeder (6) provides coating layers to the multi-layer hot melt coating unit (5)
- treating the coated fabric through heat treatment (7) and calendaring (8) process
- printing the coated and treated fabric in the printing unit (9); and
- finishing and receiving the finished product in the finish product rolling unit (10).

13. The process for preparing the recyclable, economical, impermeable, airtight, tear-resistant, crack-resistant, waterproof, weldable and lightweight, coated/ laminated fabric as claimed in claims 11 and 12, wherein the finished fabric may further be processed by reversing the drive for the other side.