DESC:Field of Invention
The present invention relates to a laminate and a process for preparing the laminate.

Background of the invention
Conventionally known laminates have been typically manufactured using plastics such as low-density polyethylene (LDPE) or high-density polyethylene (HDPE) on jute cloth which get naturally deteriorated over a period of time and lose its intended application function ability. This is not an eco-friendly option as plastic is non degradable and creates environmental challenges in disposal. It cannot be recycled as plastic cannot be separated from jute.

WO 2006/117801 discloses a multilayered composite packaging comprising a biodegradable substrate layer and a biodegradable film adhered to the substrate without any adhesive. The application addresses the problem of non-degradability of biodegradable materials coated with plastic. The application describes laminating a biodegradable material with a hydrophilic film of water soluble polymers such as polyvinyl alcohol polymers, polymethacrylic acid, polyurethane, gelatin, water soluble cellulose etc., or non-soluble polymers such as thermoplastic starch. The biodegradable material is selected from fibers, fabrics, pulps like cotton, jute, hemp, wood pulp, bagasse or metal foils.

US 5208286 discloses a cross-linkable ethylene-vinyl alcohol-acrylate polymer. This document describes to esterify ethylene vinyl alcohol obtained by hydrolysis of ethylene vinyl acetate with acrylic acid to form a product that can be easily crosslinked by peroxide or radiation. The polymer is used to form products such as cables, pipes, foam plastic, used in paints and to coat paper.

US 4510274 discloses a vinyl acetate-ethylene copolymer emulsion and an aqueous adhesive emulsion composition containing the copolymer emulsion. The copolymer emulsion is prepared by polymerization of vinyl acetate monomer, ethylene monomer, unsaturated acid monomer and an acrylamide monomer. The document teaches that the unsaturated acid monomer and an acrylamide monomer are essential for the adhesive properties of the copolymer.

Summary of the invention
In one aspect, the invention relates to a laminate comprising one or more of a biodegradable material, one or more of a recyclable material, wherein the biodegradable material and the recyclable material are bonded by an adhesive.

In another aspect, the invention relates to a process for preparing a laminate that comprises applying an adhesive on a recyclable material and bonding a biodegradable material with the recyclable material coated with the adhesive.

In a further aspect, the invention relates to a system for preparing a laminate that comprises a plurality of unwinders for unwinding recyclable material and biodegradable material, an application means for applying an adhesive on the recyclable material, a means for bonding the biodegradable material to the recyclable material, a set of threading path rolls, a dryer for dying the laminate, a means for cooling the dried laminate and a winder to wind the finished laminate.

In a further aspect, the invention relates to an adhesive comprising a water-based ethyl vinyl acetate dispersion having highly cross-linkable carboxylic group.

Detailed Description Of The Invention
The invention relates to a laminate comprising one or more of a biodegradable material, one or more of a recyclable material, wherein the biodegradable material and the recyclable material are bonded by an adhesive.
In one embodiment, the biodegradable material is selected from a fabric selected from jute, cotton or viscose, cloth, paper, a combination of various fabric, a combination of cloth with paper of varying specification. The adhesive is a water-based ethyl vinyl acetate (EVA) dispersion comprising highly cross-linkable carboxylic group. The adhesive comprises one-part phthalate and is free from formaldehyde, has a solid content in a range of 10-70%, viscosity in a range of 5-30 poise and a pH in a range of 4-6. The recyclable material is selected from an aluminum foil, a brass foil, a copper foil, a tin foil, a steel foil or a zinc foil.

In another embodiment, the biodegradable material is a jute fabric, the adhesive is a water-based ethyl vinyl acetate dispersion comprising of highly cross-linkable carboxylic group and the recyclable material is an aluminum foil. The aluminum foil has a thickness in a range of 6 microns to 20 microns.

The laminate is eco-friendly as it has a recyclable material instead of a plastic laminated on the biodegradable material that overcomes the challenges of disposability faced with the conventionally known laminate. The jute cloth used to form the laminate free from loose fibers. The wettability of aluminum foil is preferably about 72 dyne/cm. The adhesive for bonding the jute fabric with the aluminium foil provides an enhanced adhesion, which makes the laminate highly durable.

The invention also relates to a process for preparing a laminate comprising applying an adhesive on a recyclable material, then bonding a biodegradable material with the recyclable material coated with the adhesive.

The process further includes drying the laminate by heating at a temperature in a range of 60°C to 150°C in the presence of a propane gas, followed by cooling the laminates. The drying can be carried out by any known process, preferably, the drying is carried out in a floating type dryer preferably by using propane gas as a heating media, which is environment friendly. The drying rates are fixed in such a manner so as to provide complete drying of the adhesive and laminate.

In an embodiment, the biodegradable material is selected from a fabric selected from jute, cotton or viscose, cloth, paper, a combination of various fabric, a combination of cloth with paper of varying specification. The adhesive is a water-based ethyl vinyl acetate (EVA) dispersion comprising highly cross-linkable carboxylic group. The adhesive comprises one-part phthalate and is free from formaldehyde, has a solid content in a range of 10-70%, viscosity in a range of 5-30 poise and a pH in a range of 4-6. The recyclable material is selected from an aluminum foil, a brass foil, a copper foil, a tin foil, a steel foil or a zinc foil.

In another embodiment, the invention relates to a process for preparing a laminate wherein the biodegradable material is a jute fabric, and the recyclable material is an aluminum foil. The process comprises applying an adhesive on an aluminum foil. The adhesive is a water-based ethyl vinyl acetate (EVA) dispersion adhesive comprising highly cross-linkable carboxylic group as described above. After application of the adhesive, the aluminum foil coated with the adhesive and jute fabric are passed together through nip rolls for bonding the jute and aluminum foil together. The bonded sheet is passed through a heating tunnel under propane gas heating atmosphere. The dried laminate is passed through a chiller roll to obtain a continuously produced laminate.

The process of preparing the laminate is an eco-friendly process. The process provides a production rate of 40 m/min to 100 m/min for laminates of large size having width in a range from 700 mm to 1600 mm and length in a range from 500 m to 2000 m. The finished laminates are present in form of a roll as per the requirements with varied specifications (such as length, width, thickness, outer diameter) of both the biodegradable material and the recyclable material.

The invention also relates to a system for preparing a laminate. The system comprises a plurality of unwinders for unwinding recyclable material and biodegradable material, an application means for applying an adhesive on the recyclable material, a means for bonding the biodegradable material to the recyclable material, a set of threading path rolls, a dryer for dying the laminate, a means for cooling the dried laminate and a winder to wind the finished laminate.

In an embodiment, the system further comprises a coating means for applying a coat on the recyclable material after bonding of the biodegradable material to the recyclable material.

The invention also relates to a packaging comprising the laminate for packing food, beverage, chemical, electrical, agricultural, fertilizer, construction or industrial products. The laminate provides an ecofriendly food packaging or other packaging option depending on the intended application, wherein the inner layer of the recyclable material such as aluminum foil provides impervious, clean, bacteria resistant surface that can be easily cleaned by wiping. The aluminum foil provides strength to the laminate. The foil being light in weight reduces the weight of the laminate. The aluminum foil is anti-corrosive. The aluminum foil is recyclable instead of single-use plastic which is generally used in packaging food.

In an embodiment, the process for preparing a laminate for packaging comprises a first step of applying a water based ethyl vinyl acetate dispersion adhesive comprising highly cross-linkable carboxylic group. The adhesive is suitable for use in indirect food contact application/general purpose commercial adhesive (depending on the intended application) on a recyclable material. The recyclable material can be an aluminum foil suitable for food packaging. The second step comprises bonding a biodegradable (fabric/cloth) onto the recyclable material with the adhesive layer to form a laminate. The third step comprises drying the laminate by passing the same, through a propane gas-based heating tunnel followed by cooling of the laminate on a chiller drum and further winding into rolls. Typical drying temperature inside the tunnel ranges from 60°C to 150°C.

The invention also relates to an adhesive comprising a water-based ethyl vinyl acetate dispersion having highly cross-linkable carboxylic group. The adhesive comprises one-part phthalate and is formaldehyde free. The solid content in the adhesive is in a range of 10-70%. The viscosity of the adhesive is in a range of 5-30 poise. The pH of the adhesive is in a range of 4-6. Typically, the solid content of the adhesive is about 55% with the pH in the range of 4-6.

In an embodiment, the adhesive preferably is a food grade adhesive.

The adhesive described above is a specially modified vinyl acetate-ethylene copolymer, which provides a uniform adhesion to a wide variety of difficult to bond substrates. Maintaining the viscosity in the desired range avoids the leakage or dripping of the adhesive from the biodegradable material during lamination process. The adhesive is odorless unlike solvent based adhesives. The adhesive provides superior bonding of the biodegradable and recyclable materials, which improves the life, durability and quality of the laminates.

Examples
Example 1: Laminate of Jute fabric and Aluminum foil
A food grade 10 micron thick aluminum foil was selected and a water based ethyl vinyl acetate (EVA) dispersion food grade adhesive was applied on the aluminum foil. A jute fabric was bonded with the adhesive applied aluminum foil to form a laminate. The laminate was dried by passing through a propane gas-based heating tunnel and heating was carried out at 80°C. The dried laminate was cooled in a chiller to ambient temperature.

Example 2: Laminate of Jute fabric and Aluminum foil
14 micron thick aluminum foil was selected and a water based ethyl vinyl acetate (EVA) dispersion adhesive was applied on the aluminum foil. A jute fabric was bonded with the adhesive applied aluminum foil to form a laminate. The laminate was dried by passing through a propane gas-based heating tunnel and heating was carried out at 80°C. The dried laminate was cooled in a chiller to ambient temperature.

The laminate of Examples 1 and 2 were tested for its mechanical properties. The tensile strength of the laminate was 210 N/cm, and the elongation was about 11%.

Example 3: Laminate of Viscose cloth and Aluminum foil
6.5 micron thick aluminum foil was selected and a water based ethyl vinyl acetate (EVA) dispersion adhesive was applied on the aluminum foil. A viscose cloth was bonded with the adhesive applied aluminum foil to form a laminate. The laminate was dried by passing through a propane gas-based heating tunnel and heating was carried out at 80°C. The dried laminate was cooled in a chiller to ambient temperature.

Example 4: Laminate of high strength Kraft paper and Aluminum foil
6.5-7 micron thick aluminum foil was selected and a water based ethyl vinyl acetate (EVA) dispersion adhesive was applied on the aluminum foil. A high strength Kraft paper (80-100 GSM) of was bonded with the adhesive applied aluminum foil to form a laminate. The laminate was dried by passing through a propane gas-based heating tunnel and heating was carried out at 80°C. The dried laminate was cooled in a chiller to ambient temperature.

The laminates were tested for adhesion between the biodegradable material and the recyclable material by a peel-off test using a scotch tape. The laminates of Examples 1-4 passed the test.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to a person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.
,CLAIMS:

1. A laminate comprising,
one or more of a biodegradable material;

one or more of a recyclable material; and

wherein the biodegradable material and the recyclable material are bonded by an adhesive.

2. The laminate as claimed in claim 1, wherein
the biodegradable material is selected from a fabric selected from jute, cotton or viscose, cloth, paper, a combination of various fabric, a combination of cloth with paper;

the adhesive is a water-based ethyl vinyl acetate dispersion comprising highly cross-linkable carboxylic group; and

the recyclable material is selected from an aluminum foil, a brass foil, a copper foil, a tin foil, a steel foil or a zinc foil.

3. The laminate as claimed in claim 1 or 2, wherein the biodegradable material is a jute fabric, the adhesive is a water-based ethyl vinyl acetate dispersion comprising of highly cross-linkable carboxylic group and the recyclable material is an aluminum foil.

4. The laminate as claimed in claim 3, wherein the aluminum foil has a thickness in a range of 6 microns to 20 microns.

5. The laminate as claimed in claim 2, wherein the adhesive comprises one-part phthalate and is free from formaldehyde, has a solid content in a range of 10-70%, viscosity of 5-30 poise and a pH of 4-6.

6. A process for preparing a laminate, the process comprising the steps:
applying an adhesive on a recyclable material; and
bonding a biodegradable material with the recyclable material coated with the adhesive.

7. The process as claimed in claim 6, further comprising drying of the laminate by heating at a temperature in a range of 60°C to 150°C in the presence of propane gas, followed by cooling.

8. The process as claimed in claim 6, wherein
the biodegradable material is selected from a fabric selected from jute, cotton or viscose, cloth, paper, a combination of various fabric, a combination of cloth with paper;

the adhesive is a water-based ethyl vinyl acetate dispersion comprising highly cross-linkable carboxylic group; and

the recyclable material is selected from an aluminum foil, a brass foil, a copper foil, a tin foil, a steel foil or a zinc foil.

9. The process as claimed in claim 6, wherein the biodegradable material is a jute fabric, the adhesive is a water-based ethyl vinyl acetate dispersion comprising highly cross-linkable carboxylic group and the recyclable material is an aluminum foil.

10. A system for preparing a laminate, the system comprising,
i. a plurality of unwinders for unwinding recyclable material and biodegradable material,
ii. an application means for applying an adhesive on the recyclable material,
iii. a means for bonding the biodegradable material to the recyclable material,
iv. a set of threading path rolls,
v. a dryer for dying the laminate,
vi. a means for cooling the dried laminate, and
vii. a winder to wind the finished laminate.
11. The system as claimed in claim 10, further comprising a coating means for applying a coat on the recyclable material after bonding of the biodegradable material to the recyclable material.

12. A packaging comprising the laminate as claimed in any one of the claims 1-5 for packing food, beverage, chemical, electrical, agricultural, fertilizer, construction or industrial products.

13. An adhesive comprising a water-based ethyl vinyl acetate dispersion having highly cross-linkable carboxylic group.

14. The adhesive as claimed in claim 13, wherein the adhesive comprises one-part phthalate and is free from formaldehyde, has a solid content in a range of 10-70%, viscosity of 5-30 poise and a pH of 4-6.