WO2020136674A1

WO2020136674A1 - Recyclable laminate

Info

Publication number: WO2020136674A1
Application number: PCT/IN2019/050944
Authority: WO
Inventors: Ashwini KUMAR SINGH; Aishwarya VANAGE; Mahuwa MASALIA
Original assignee: Huhtamaki Ppl Limited
Priority date: 2018-12-26
Filing date: 2019-12-20
Publication date: 2020-07-02

Abstract

The present invention relates to a recyclable laminate comprising a first layer and a second layer, each layer being a polyolefin layer having a thickness in the range of 12 micron to 100 microns; and an intermediate layer having thickness in the range of 10 microns to 35 microns sandwiched between the first polyolefin layer and the second polyolefin layer, the intermediate layer being a metallized polyolefin film having alcohol based polymer barrier resins therein.

Description

TITLE OF THE INVENTION

Recyclable Laminate

FIELD OF THE INVENTION

[001] The invention relates to a flexible laminate and process for production thereof, more particularly to a recyclable flexible laminate for packaging applications.

BACKGROUND OF THE INVENTION

[002] Plastics are inexpensive and durable, and as a result levels of plastic production and consumption is high. Flexible packaging material comprising plastics are also widely used due to features like product protection, shelf life enhancement, attractive look and branding, lower source usage etc. These flexible packaging commonly used comprises different combinations of polymeric/plastic films, aluminum foils, coated films wherein each layer provides a unique characteristic to the final laminate. The exponential growth in usage of flexible packaging over last few decades has meant that post-consumer collection, segregation, sorting and disposal is becoming an increasing challenge, especially in developing countries. Moreover, the chemical structure of most plastics renders them resistant to natural processes of degradation and as a result they are impossible to degrade. Pollution due to the accumulation of plastic products in the environment is adversely affecting wildlife, wildlife habitat and humans. Thus, the very nature of these laminated flexible packages that makes them extremely popular is proving to be an environmental nightmare as far as societies, governments and ecology is concerned.

[003] Efforts to thus reduce the use of plastics and to promote plastic recycling have been a primary goal for all concerned. For e.g., some supermarkets charge their customers for the plastic bags, and in some places more efficient reusable or biodegradable materials are being used in place of plastics. Some communities and businesses have put a ban on some commonly used plastic items, such as bottled water and plastic bags. Unfortunately, recycling is not easy as the flexible packages by its very nature are made up of different materials and each one of the components is chemically different requiring a different recycling approach. There are many methods for recycling and or disposal of used flexible packages. A few of the existing methods for recycling of flexible plastic packages include

Incineration - The post-consumer usage waste is burned in high temperature kilns and energy recovery is attempted. While energy recover is possible this process may give out highly polluting fumes which are an environment hazard.

Pyrolysis - Pyrolysis is a process wherein hydrocarbons in flexible plastic waste are broken down & returned to the original oil state. This is a technology still in development

& current pyrolysis plants are small scale which cannot handle the high amount of post industrial & post-consumer generated waste in packaging.

Mechanical recycling - Post consumer usage waste is fed into industrial recyclers and a secondary by-product is obtained (resin). The recyclers shred the wastage and then push through an extruder while simultaneously heating the wastage. This leads to generation of a product in the form of small granules. This product is then used in making alternate low value products. However, considering the flexible packaging comprises different combinations of polymeric/plastic films, aluminum foils, coated films etc., its recycling is highly challenging since different films have different melting points. The temperatures used are either too high or too low for the individual layers in the flexible laminate being recycled leading to resultant granules being of substantially lower quality and cannot be used economically for many secondary application.

[004] Given the situation, the flexible packaging industry as well as governments around the world, large corporations and food manufactures are all busy charting sustainable strategies and actually defining what“sustainability” means for them and what will be considered a sustainable solution.

SUMMARY OF THE INVENTION [005] In one aspect, the invention provides a recyclable laminate comprising a first layer and a second layer, each layer being a polyolefin layer having a thickness in the range of 12 micron to 100 micron; and an intermediate layer having thickness in the range of 10 microns to 35 microns sandwiched between the first polyolefin layer and the second polyolefin layer, the intermediate layer being a metallized polyolefin film having alcohol based polymer barrier resins therein.

DETAILED DESCRIPTION OF THE INVENTION

[006] The present invention is directed towards a recyclable flexible laminate for packaging which is light weight, economical, packing machine friendly, and has sufficient barrier properties.

[007] The recyclable laminate comprises a first polyolefin layer, a second polyolefin layer and an intermediate layer sandwiched between the first and second polyolefin layer. In an embodiment of the invention, each of the layer is a polyolefin layer. Accordingly, each layer of the laminate can be recycled without having to separate the individual layers, and thereby obviating the disadvantages associated with the prior-art.

[008] In an embodiment, each of the first and second layer is an oriented polyolefin layer having a thickness in the range of 12 microns to 100 microns. These oriented polyolefin films are made of homopolymer, copolymer and/or terpolymer of polypropylene film or a polyethylene film. [009] In another embodiment, the second layer is an extruded layer of polyethylene, polypropylene or polyolefin resins. These extruded layers are made of homopolymer, copolymer and/or terpolymer of polypropylene, polyethylene or polyolefin resins.

[010] The second layer can be used a sealant layer. The sealant layer is characterized by a low seal initiation temperature range and can be sealed starting from 75 ⁰ C.

[Oi l] In an embodiment the intermediate layer is a metallised polyolefin layer. The intermediate layer preferably is a metallized oriented poly propylene or polyethylene film having a thickness in the range of 10 micros to 35 microns and is sandwiched between the first and the second polyolefin layer. The intermediate layer has metal vacuum deposition coating of aluminium in the range of 125 to 400 angstroms. The intermediate layer with metal coating also has alcohol based polymer barrier resins selected from Nylon, ethyl vinyl alcohol, polyvinyl alcohol and/or cross-linked polyvinyl alcohol therein. The recyclable laminate with the metallised intermediate layer provides barrier properties to the laminate whereby the recyclable laminate has an oxygen transmission rate of less than lcc/m per day, and water-vapor transmission rate of less than 0.05 gms/m per day. Further, the recyclable laminate with the metallised intermediate layer can be recycled without having to separate the individual layers, and thereby obviating the disadvantages associated with the prior-art.

[012] Further, the recyclable laminate may comprise additional layers as per the product/packaging requirement, including, but not limited to barrier layers, print layers etc. while keeping product performance optimum. The further layers are also selected from polyolefin family, i.e. polyethylene or polypropylene. These further layers may form the outer layer or the intermediate layers as per the requirement.

[013] As discussed hereinbefore, the recyclable laminate is preferably used for packaging. To form flexible packages such as sealed packs or gusseted packs, the second layer can be used a sealant layer. The sealant layer is characterized by a low seal initiation temperature range and can be sealed from 75 - 90 ⁰ C upwards. The layer can be transparent or white opaque or metallised, and can be manufactured using a cast or blown manufacturing process. Alternatively the sealant layer can also be a direct extrusion sealant extruded on top or back side of the metal coated polyolefin layer. The extrusion coated sealant can be a combination of homopolymer / copolymer / terpolymer for wide sealing range.

[014] Further, the laminate can be a printed or unprinted laminate. If printed, the printing can be done using all kinds of known printing techniques like Gravure, offset, Flexographic, digital, combination printing techniques.

[015] The invention also relates to a process for forming a flexible laminate. The process comprises the steps of providing a vacuum deposited metal coated polyolefin film; providing a first layer and a second layer, each layer being an oriented polyolefin layer and laminating the layers such that the metal coated polyolefin layer is sandwiched between the first layer and the second layer. The lamination is carried out using lamination techniques including, but not limited to, dry lamination (solvent based, water based, solvent less), extrusion lamination, hot- melt lamination etc. to form a laminate which provides necessary barrier.

[016] Further polyolefin layers may be laminated into the recyclable laminate as per the product requirement, including, but not limited to barrier layers, print layers etc. while keeping product performance optimum. These further layers may form the outer layer or the intermediate layers as per the requirement.

[017] The metallization of the intermediate is carried out by the conventional methods including, but not limited to, vacuum metallization process.

[018] The process, as explained above is illustrative and other methods/processes of manufacturing may be used. EXAMPLE

The following example is illustrative of the invention but not limitative of the scope thereof: Table 1 illustrates a typical structure of the flexible laminate of the present invention:

[019] This laminate was tested for its barrier properties using Oxygen transmission rate (OTR) testing machines and Water vapour transmission rate (WVTR) testing machines. The results obtained were as follows:

OTR - <1 CC/M2/Day when checked @ 23Deg C, 0% Rh WVTR - <1 gms/M2/Day when checked @ 38 Deg C, 90% Rh

[020] Thus, it is clearly established that barrier properties of the laminate are sufficient for products that have the most stringent barrier requirements, for e.g. coffee powder, coffee beans, infant formula supplements, condoms, dried soup powders, milk based liquid products, milk powders. The results noted are representative of the trials done and different values may be obtained based on the different combinations of polyolefin layers. All such results are within scope of the invention.

[021] Advantageously, the present invention provides a flexible laminate characterized by the different layers of the laminate being made from materials belonging to same family (i.e. polyolefins). This enables efficient recyclability of the laminate in a mechanical recycling process and delivers high quality (same family) recycled resins which can be used for making multiple secondary items by using blow moulding, injection moulding, roto moulding etc processes.

[022] Further these laminates also result in much better quality and yield in a pyrolysis process as compared to existing non-recyclable laminates.

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

Claims

CLAIMS:

1. A recyclable laminate comprising:

a first layer and a second layer, each layer being a polyolefin layer having a thickness in the range of 12 micron to 100 microns; and

an intermediate layer having thickness in the range of 10 microns to 35 microns sandwiched between the first polyolefin layer and the second polyolefin layer, the intermediate layer being a metallized polyolefin film having alcohol based polymer barrier resins therein.

2. The recyclable laminate as claimed in claim 1, wherein the recyclable laminate has an oxygen transmission rate of less than 1 cc/m per day, and water-vapor transmission rate of less than 0.05 gms/m per day.

3. The recyclable laminate as claimed in claim 1, wherein the first layer is a mono or biaxially oriented poly propylene film or a mono or biaxially oriented polyethylene film.

4. The recyclable laminate as claimed in claim 1, wherein the second layer is a mono or biaxially oriented poly propylene film or a mono or biaxially oriented polyethylene film.

5. The recyclable laminate as claimed in claim 1, wherein the second layer is an extruded layer of polyethylene, polypropylene or polyolefin resins.

6. The recyclable laminate as claimed in claim 1, wherein the second layer has a seal initiation temperature 75 to 85°C.

7. The recyclable laminate as claimed in claim 1, wherein the first layer and the second layer is a homopolymer, copolymer and/or terpolymer of polypropylene or polyethylene.

8. The recyclable laminates as claimed in claim 1, wherein the intermediate layer is a metallized mono or biaxially oriented polypropylene or mono or biaxially oriented polyethylene film.

9. The recyclable laminates as claimed in claim 1, wherein the alcohol based polymer barrier resins are selected from Nylon, ethyl vinyl alcohol, polyvinyl alcohol and/or cross-linked polyvinyl alcohol.

10. The recyclable laminate as claimed in claim 1, wherein the intermediate layer has metal vacuum deposition coating in the range of 125 to 400 angstroms.

11. The recyclable laminate as claimed in claim 10, wherein the metal coating is aluminium.

12. The recyclable laminate as claimed in claim 1, wherein the laminate comprises further polyolefin layers as barrier layer, print layer.