Description:FIELD OF INVENTION

[0001.] The present invention provides paper barrier material constituted by direct AlOx metallization on a coated paper followed by protective layer coating or AlOx metallization on release coated polyester film followed by adhesive lamination of paper to facilitate transfer of AlOx layer on paper substrate. The present invention provides a suitable base film for further coating by water based barrier coating and finally, a heat sealable coating. The AlOx layer is sandwiched between heat seal layer and polymeric gas barrier layer. The moisture barrier layer consists of styrene-butadiene layer. The polymeric gas barrier layer consists of polyvinyl alcohol (PVOH). The acrylic layer consists of mixtures of many acrylates that provides high moister barrier properties.
BACKGROUND OF INVENTION

[0002.] As brands of all sizes set increasingly aggressive towards sustainability goals, many are exploring eliminating single use plastics in their packaging. Paper packaging can be recycled. Paper as a material can also more readily utilize recycled content in its mix, easily made with 100% recycled content and high level of post-consumer waste, the ease of recyclability and ability to contain high level of recycled content make paper a highly circular material. In spite of recyclability, paper has many drawbacks, the major one is barrier properties. And the paper lacks strength to hold bigger quantity of packed material as its bursting strength is poor. The present invention relates to paper packaging with high moisture (MVTR) and oxygen barrier (OTR) characteristics. It is also desirable for such products that the product should be printable as well as sealable.

[0003.] High barrier packaging material find particular applications in food industry. For example, bags, pouches or cups for storing food products for human or animal consumption. A high barrier packaging material is defined as providing very low transmission rates for water vapor or oxygen gas at both standard and tropical conditions.

[0004.] Packages with low water vapor and oxygen transmission rates are linked to extended life of food stored therein.
[0005.] In order to satisfy above requirements, PVDC resin in the form of aqueous coating was found to be successful. Examples of prior art PVDC coated paper are illustrated in US patent no.2,392,972 which discloses craft paper having a layer of a vinylidene chloride copolymer applied over an intermediate coating of a vinyl chloride vinyl acetate copolymer for good adhesion. However, it has been found that conventional water based PVDC coating on Paperboard cracks when paperboard bends during converting operation, PVDC layer crack results in damage of the barrier properties. Thus, there is a need to provide packaging material with good barrier properties to withstand the converting operation.
[0006.] Traditionally, other method for adding gas barrier properties to a paper packaging material has been to extrusion laminate or attach a gas barrier layer like aluminium foil or aluminium deposited film like PET/BOPP or polyvinyl alcohol/ethylene vinyl alcohol coated film or a film deposited with silicon oxide, aluminium oxide etc. The presence of Aluminium foil or aluminium metallized layer may aggravate the issue of repulpability/recyclability of the paper. The presence of Aluminium oxide layer not only provides barrier properties along with no metal look appearance but also improves the repulpability percentage.
[0007.] Other paper packaging materials to which gas barrier property has been added, include coating of gas barrier layer constituted by a water soluble polymer and an inorganic layer like compound to impart oxygen as well as moisture barrier properties, thus, gas barrier layer may be moisture sensitive therefore this layer may be covered with PE through extrusion coating or water based sealant layer coating on the gas barrier layer. This way, the gas barrier layer will be sandwiched and will be protected from moisture.
[0008.] US Patent No. 6,788,379 describes a plasma oxide coating process via enhanced chemical vapor deposition on different polymer sheets. The resultant oxide coated sheets demonstrated significantly reduced transmission rate for moisture vapor and oxygen gas. The process of aluminum oxide (AlOx) or silicon oxide (SiOx) coating of BOPP/Polyester Film via roll to roll web vacuum deposition provides a transparent thin coating layer aluminum oxide or silicon oxide on the substrate that gives the packaging material high moisture and oxygen barrier properties as well as transparency.

OBJECT OF THE INVENTION
[0009.] The paper barrier material by the present invention is constituted by direct AlOx metallization on a coated paper followed by protective layer coating or AlOx metallization on release coated polyester film followed by adhesive lamination of paper to facilitate transfer of AlOx layer on Paper substrate.

SUMMARY OF THE INVENTION
[0010.] The invention relates to a paper barrier packaging material comprising a plurality of coating layers disposed on a paper base material and the coating material consists of
[0011.] For direct metallized paper, a moisture barrier layer, a gas barrier layer followed by an AlOx layer protected by a heat seal layer.
[0012.] For transfer metallized layer, an adhesive layer, a gas barrier layer, an AlOx layer protected by an acrylic layer and a release layer. After transfer metallization on Paper, heat seal lacquer is coated on release layer.
[0013.] AlOx layer not only provides barrier properties like OTR and MVTR but also improves the repulpability of the paper and because of the AlOx layer, paper looks like natural paper with high gloss.
[0014.] For direct metallized paper, AlOx layer is sandwiched between heat seal layer and polymeric gas barrier layer. This way AlOx layer is protected from outside abrasion.
[0015.] For transferred metallized layer, AlOx layer is sandwiched between a gas barrier layer and an acrylic layer and thus protected from outside abrasion.
[0016.] The barrier layer along with AlOx layer is responsible for improvement in barrier properties and the heat seal layer is responsible for sealing with itself.
[0017.] In one embodiment the present invention relates to a paper barrier packaging material comprising a plurality of coating layers applied on the substrate (paper base material) wherein the coating material consists of :
a. 1A) For Direct metallized paper
[0018.] Coating to fill up the pores & smoothening of the pores of the paper
[0019.] moisture barrier layer;
[0020.] polymeric gas barrier layer;
[0021.] AlOx layer coating on gas barrier layer
[0022.] Heat seal layer

a. 1B) For transfer metallized paper
[0023.] Release coating
[0024.] Acrylic coating
[0025.] AlOx metallization
[0026.] Polymeric gas barrier layer
[0027.] Adhesive lamination
[0028.] Heat seal layer coating
[0029.] wherein, in the case of direct metallized paper, pore filing coating is applied on the substrate followed by polymeric gas barrier layer; subjecting the substrate to AlOx metallized and maturing for a week , the said AlOx layer is sandwiched between heat seal layer and polymeric gas barrier layer, wherein, in the case of transfer metallized paper, release coating and acrylic coating is applied on the polyester film followed by AlOx metallization, subjecting the AlOx metallized layer maturation for a week, the said AlOx layer is overcoated by a barrier layer, the barrier coated polyester film is laminated to paper using adhesive and cured for atleast 24 hrs, after curing, the Polyester film is separated, the coated paper is again coated with heat seal layer.
[0030.] In another embodiment a paper barrier packaging material wherein said substrate is paper base material. The paper barrier packaging material wherein the first coating of kaolin and sodium polyacrylate is applied on the substrate to fill up the pores.
[0031.] In yet another embodiment a paper barrier packaging material wherein said kaolin has an aspect ratio 80-100 and 0.25%. sodium polyacrylate is mixed in water and vigorously stirred at high speed stirrer for 15 minutes. This kaolin dispersion is mixed with styrene-butadiene latex to prepare a lacquer to fill up the pores. A paper barrier packaging material wherein second coating of smoothening layer which comprises a barrier layer is applied to improve the smoothness as well as barrier of the paper.
[0032.] In still another embodiment a paper barrier packaging material wherein said lacquer is obtained from 10% solution of PVOH (polyvinyl alcohol) in water.
[0033.] In another embodiment a paper barrier packaging material wherein AlOx is metallized on the gas barrier layer. The AlOx metallized paper is coated with heat sealable layer. The lacquer is obtained from EAA based lacquer.
[0034.] In still another embodiment a paper barrier packaging material wherein polyester film is coated with a release lacquer, wherein release lacquered film is acrylic coated on the coated side.

[0035.] In another embodiment a paper barrier packaging material, wherein AlOx metallization is done on acrylic coating side followed by a protective coating of barrier layer.
[0036.] In still another embodiment a paper barrier packaging material, wherein a separate sheet of paper coated with an adhesive is laminated with the AlOx metallized Polyester film and cured for one day. The said laminate is separated wherein the polyester film is released for reuse and the AlOx is transferred on the paper to produce the finished product as transfer AlOx metallized paper wherein said separated paper layer is coated with heat seal lacquer. The heat seal lacquer is coated on release layer.
[0037.] In yet another embodiment a paper barrier packaging material wherein the said release layer comprises 10% solution of cellulose acetate butyrate (CAB) in alcohol and water mixer in 50:50 ratio.
[0038.] In still another embodiment a paper barrier packaging material wherein the said AlOx layer is sandwiched between heat seal layer and polymeric gas barrier layer. The moisture barrier layer consists of styrene-butadiene layer. The polymeric gas barrier layer consists of polyvinyl alcohol (PVOH). The acrylic layer consists of mixtures of many acrylates. The adhesive layer consists of polyurethane adhesive and isocyanate crosslinker and the release layer consists of cellulose acetate butyrate and cellulose acetate propionate.
BRIEF DESCRIPTION OF THE DRAWINGS

[0039.] Fig.1 illustrates direct AlOx metallization after varnishing of paper
[0040.] Fig. 2 illustrates transfer AlOx metallization followed by a protective coating of barrier layer
[0041.] Fig. 3 illustrates AlOx metallization process in AlOx metallizer

DETAILED DESCRIPTION OF THE INVENTION

[0042.] In one embodiment the present invention relates to a paper barrier packaging material
comprising a substrate, first layer, second layer, AlOx metallized layer and protective layer in the direct metallized paper;

[0043.] In another embodiment the present invention relates to polyester film, release lacquer, acrylic, AlOx metallized layer, protective barrier layer, adhesive in transfer metallized paper; wherein, in direct metallized paper, first coating comprises of Kaolin with particle size 9 mic and aspect ratio 80-100 is taken and mixed with 0.25% of sodium polyacrylate in water, This is in combination with styrene butadiene latex; second layer comprises of PVOH (Poly vinyl alcohol) or cellulose derivative; and in transfer metallized paper, the polyester film is coated with release coating, acrylic coating followed by AlOx metallization. The substrate is paper base material wherein the first coating comprises of kaolin and sodium polyacrylate in combination with styrene butadiene latex. The pore filling coating solution is prepared by mixing 80- 100% kaolin and 0.25% sodium polyacrylate with water and vigorously stirred at high speed stirrer for 15 minutes followed by mixing with styrene butadiene latex.
[0044.] The second coating layer comprises of 10% PVOH (polyvinyl alcohol) in water and the protective layer comprises of ethylene acrylic acid. The transfer metallization paper comprises of polyester film coated with a release lacquer. The said release layer comprises 10% solution of cellulose acetate butyrate (CAB) in alcohol and water in the ratio 50:50.
[0045.] In another embodiment the process for the preparation of paper barrier packaging material, wherein the process of preparation of AlOx metallized paper by direct metallization comprises the steps of coating of substrate with first coating layer, coating of the above substrate with second coating layer, carrying out the AlOx metallization on the surface of the above obtained substrate, coating the AlOx metallized surface with protective coating. The compound used for filling up the pores and improving MVTR are of styrene butadiene, styrene acrylic, ethylene vinyl acetate, wax emulsion, butadiene-methyl methacrylate, vinyl acetate-butyl acrylate copolymer, maleic acid copolymer. The first layer used for filling up the pores and improving MVTR is styrene butadiene along with fillers kaolin, calcium carbonate, TiO2, clay, mica, talc, barium sulfate, calcium sulfate, zinc oxide, silicate, colloidal silica or other organic pigments.
[0046.] The dispersing agent is sodium polyacrylate. The thickness of first coating layer is 8- 10g/sqm. The second coating layer can be a gas barrier layer. The second coating layer contains polymers such as PVOH, EVOH, casein, soybean protein or other protein, oxidized starch, cationic starch, hydroxyl ethyl etherified starch, CMC, hydroxyl methyl/ethyl cellulose, poly vinyl pyrrolidone, sodium alginate. The PVOH or

cellulose derivative are used as the second coating layer. The second coating layer can be 3-5g/sqm. the thickness of AlOx metallization is 8- 20 nm. The protective layer is heat sealable layer.
[0047.] The heat sealable (protective) layer is formed from ethylene acrylic acid (EAA), Ethylene vinyl acetate(EVA), Acrylic copolymer, PVDC copolymer, Poly butyl succinate, aliphatic Polyester, PHA, PLA, wax, starch, PGA and/or sealants such as Ecoflex or Ecovio which is a compostable polyester by BASF.
[0048.] A process for the preparation of paper barrier packaging material, wherein the process of preparation of AlOx metallized paper by transfer metallization comprises the steps of coating polyester film is coated with release lacquer, coating the release lacquered side of the film with acrylic, carryout the AlOx metallization on acrylic coated side, coating the protective barrier layer, coating a separate sheet of paper with adhesive, laminate the adhesive coated paper with AlOx metallized polyester film, separating the polyester film from the paper after curing time to get the AlOx metallized paper, coating of heat seal layer on coated paper which has been delaminated from polyester film.
[0049.] The release coating on polyester film is done using cellulose acetate propionate(CAP), cellulose acetate butyrate(CAB) in water. The thickness of the coating can be 0.4- 0.5 g/sqm.
[0050.] The acrylic can be Poly methyl methacrylate, styrene-methyl methacrylate, isobornyl acrylate/methacrylate, butyl methacrylate-methylmethacrylate, poly tert-butyl acrylate, Poly butylacrylate-methyl methacrylate, polymethyl methacrylate-butyl acrylate-methacrylic acid terpolymer. The coating of acrylic layer should be preferably 1.0 to 1.1 g/sqm.. The gas barrier layer coating can be 1-5 g/sqm. The thickness of the barrier coating should be preferably 1-3g/sqm.
[0051.] AlOx metallization of paper can take place using one of the two procedures. They are transfer metallization or direct metallization.
Direct metallized Paper
[0052.] The paper will be coated first to fill up the pores of the paper and at the same time, to reduce the moisture vapor transmission rate
[0053.] The second coat will be given to improve the smoothness of the paper and this coating will also improve the oxygen barrier of paper.
[0054.] On the sufficiently improved surface, AlOx metallization is carried out as in Fig. 1.

[0055.] Alox metallized side was again coated with a protective coating. The protective coating can be a heat sealable coating.
Transfer metallization process
[0056.] Polyester film is coated with a release lacquer.
[0057.] The release lacquered film is acrylic coated on the coated side.
[0058.] Alox metallization is done on acrylic coating side followed by a protective coating of barrier layer as in Fig. 2.
[0059.] A separate sheet of paper is coated with an adhesive.
[0060.] Adhesive coated paper is laminated with the barrier layer coated AlOx metallized polyester film.
[0061.] After a curing time of one day, the laminate is separated, during which process, the polyester film is released for reuse again and the AlOx is transferred on the paper to produce the finished product as transfer AlOx metallized paper.
[0062.] The transfer metallized paper is again coated with heat seal layer for sealing with itself.
[0063.] The purpose of the present invention is to provide a suitable base film for further coating by water based barrier coating and finally, a heat sealable coating. The present invention is an improvement over the existing aluminum metal transferred paper due to no metal look appearance and at the same time, achieving good barrier properties.
Process for directly metallized paper
[0064.] In order to fill up the pores and improving MVTR, styrene butadiene, styrene acrylic, ethylene vinyl acetate, wax emulsion, butadiene-methyl methacrylate, vinyl acetate-butyl acrylate copolymer, maleic acid copolymer etc. are suitable. Among them, styrene butadiene synthetic adhesive is preferred.
[0065.] Styrene butadiene copolymer may also contain fillers like kaolin, calcium carbonate, TiO2, clay, mica, talc, barium sulfate, calcium sulfate, zinc oxide, silicate, colloidal silica or other organic pigments. etc. sodium polyacrylate can be added as dispersing agent.
[0066.] This layer coating GSM can be up to 20 gsm but the preferable coating GSM can be 8-10 g/sqm
[0067.] The second coating layer can be gas barrier layer as well as it smoothens the surface. The gas barrier layer is water soluble and may contain following polymers i.e, PVOH, EVOH, casein, soybean protein or other protein, oxidized starch, cationic starch,

hydroxyl ethyl etherified starch, CMC, hydroxyl methyl/ethyl cellulose, poly vinyl pyrrolidone, sodium alginate etc. Among them, PVOH or cellulose derivative are preferred.
[0068.] This layer coating GSM can be up to 20 gsm but the preferable coating GSM can be 3-5 g/sqm.
[0069.] The heat seal layer is coated on release layer of coated paper. The heat sealable layer is formed from ethylene acrylic acid (EAA), Ethylene vinyl acetate (EVA), Acrylic copolymer, PVDC copolymer, Polybutyl succinate, aliphatic Polyester, PHA, PLA, wax, starch, PGA and/or sealants such as Ecoflex or Ecovio which is a compostable polyester by BASF and the deposition of heat seal layer is 3-4 g/sq.m.
AlOx metallization
[0070.] Alox coated film/paper are produced when the aluminum is evaporated from a crucible tank as vapor, The oxygen gas is injected through a gas bar uniformly to produce aluminum oxide which deposits on film. The condensate on film/paper forms a very thin “glass layer” that is 8-20 nm according to the application. The AlOx coating can be applied on Paper, PET, Nylon and BOPP Film as in Fig. 3.
[0071.] Alox layer requires to be protected by a protective layer since AlOx layer is very brittle in nature. The protective layer can be heat sealable layer.
[0072.] The term “paper” refers to any paper substitute such as Kraft Paper, Coated paper, magazine or photographic paper or other cellulosic pulp based paper which are commercially available.
[0073.] The term “sealant” is used to refer to a sealant layer or heat seal layer which may be formed from ethylene acrylic acid (EAA), Ethylene vinyl acetate(EVA), Acrylic copolymer, PVDC copolymer, Polybutyl succinate, aliphatic Polyester, PHA, PLA, wax, starch, PGA and/or commercially available sealants such as Ecoflex or Ecovio which is a compostable polyester by BASF.
[0074.] The application for sealant layer is either through water based coating or extrusion coating method. This layer coating GSM can be up to 8-10 gsm if it is extrusion coating but for water based coating, the preferable coating GSM can be 2-4 g/sqm.
Process for transfer metallization of paper
[0075.] In the transfer metallization process, Polyester film is coated with release coating,

[0076.] The release coating on Polyester film is done by using cellulose acetate propionate (CAP), cellulose acetate butyrate(CAB) etc in water based coating.
[0077.] This layer coating GSM can be up to 1.0 gsm but the preferable coating GSM can be 0.4-0.5 g/sqm
[0078.] The release coated layer is coated with acrylics. The most suitable acrylic will have a Tg of about 80oC to 110o
[0079.] The acrylic can be Poly methyl methacrylate, styrene-methyl methacrylate, isobornyl acrylate/methacrylate, butyl methacrylate-methylmethacrylate, poly tert-butyl acrylate, Poly butylacrylate-methyl methacrylate, polymethyl methacrylate-butyl acrylate-methacrylic acid terpolymer etc
[0080.] This layer coating GSM can be up to 2.0 gsm but the preferable coating GSM can be 1.0-1.1 g/sqm
[0081.] The acrylic coated film is AlOx metallized and over coated with barrier layer. The barrier coating GSM can be up to 3 gsm. Preferably, it should be between 1-2 g/sqm.
[0082.] The polyester film coated with release layer, Acrylic layer, metallized layer and barrier coat layer is transferred on paper by lamination process using laminating adhesive which is two component adhesive using polyester polyol and toluene diisocyanate (TDI) in the composition of 10:1. The adhesive GSM should be preferably 3-4 g/sq.m. After the lamination process, the adhesive is allowed to cure for one day and then polyester film is delaminated. The delaminated polyester film is reusable.
[0083.] The coated paper becomes transfer metallized. In order to coat this paper with barrier layer, the coated paper requires to be primer coated. The primer can be Polyethylene imine, Polyurethane primer etc. After primer coating, Barrier coating is applied.
[0084.] The gas barrier layer is water soluble and This barrier layer may consist of barrier coating as described above. This layer coating GSM can be up to 5 gsm but the preferable coating GSM can be 1-1.5 g/sqm.
[0085.] After the gas barrier layer, heat sealable layer is top coated using the sealant layer as described above either for extrusion coating or water soluble layer.

EXAMPLES
[0086.] The invention is now illustrated by examples representative of direct metallization and transfer metallization process, wherein, all parts, proportions and percentage are by weight unless otherwise indicated.

Test Method :
[0087.] Thickness: Thickness were measured by micrometer.
[0088.] Coating GSM : The coated sample weight is taken after and before coating removal by solvent. For a given area of the sample, coat weight is determined. This coat weight can be calculated for unit square meter of area.
[0089.] Tape transfer test : The tape transfer test is application of tape on AlOx metallized surface. The 98-100% coating should be removable during peeling of the Tape.
[0090.] Surface Energy: The surface energy (dynes/cm) was measured by using dyne solution which is a mixture of formamide and Ethyl cellusolve.
[0091.] Surface Gloss : The surface gloss was measured at 45o angle by using BYK gardener gloss meter.
[0092.] Oxygen permeability (gas barrier property): oxygen permeability was measured using the OX-TRAN 2/21 manufactured by MOCON under a condition of 23oC and 0% RH(dry).
[0093.] Water Vapor permeability (water vapor barrier property): water vapor permeability was measured using a moisture permeability measuring machine (Permatran, MOCON) at a temperature of 38oC and 90% RH.
Examples for directly metallized paper:
Example-1:
[0094.] Pore filling coating: Kaolin with particle size 9 mic and aspect ratio 80-100 is taken and mixed with sodium polyacrylate in water. The concentration of polyacrylate is 0.25%. The 50% solid component is vigorously stirred using high speed stirrer for 15 mins.

[0095.] The styrene-butadiene latex (Apcotex PC-200 produced by Apcotex india Ltd) is taken in equal quantity so that total concentration becomes 50%. This laquer is coated using blade coater on Paper substrate (80 gsm). The total coating gsm is 10 gsm .

[0096.] Barrier coating : 10% solution of Kuraray POVAL 15-99 was made in water for barrier coating. This lacquer is coated on the styrene butadiene coating using gravure roller. The coating GSM was 1.5. The above coated roll is AlOx metallized and matured for a week. The AlOx coated paper is coated with EAA based heat seal lacquer (chemipearl S-300) using gravure coating process for 3 gsm coating.

Example-2:
[0097.] Pore filling coating: Kaolin with particle size 9 mic and aspect ratio 80-100 is taken and mixed with sodium polyacrylate in water. The concentration of polyacrylate is 0.25%. The 50% solid component is vigorously stirred using high speed stirrer for 15 mins.

[0098.] The styrene-butadiene latex(Apcotex PC-200 produced by Apcotex india Ltd) is taken in equal quantity so that total concentration becomes 50%. This laquer is coated using blade coater on Paper substrate(80 gsm). The total coating gsm is 10 gsm .

[0099.] Barrier coating : 10% solution of Kuraray POVAL 15-99 was made in water for barrier coating. This lacquer is coated on the styrene butadiene coating using gravure roller. The coating GSM was 2.1

[0100.] The above coated roll is AlOx metallized and matured for a week. The AlOx coated paper is coated with heat seal lacquer using gravure coating process for 3 gsm coating.

Examples for transfer metallized paper:
Example 3:
[0101.] Release Coating : A 10% solution of cellulose acetate butyrate (CAB) is prepared using alcohol and water mixer in 50:50 ratio. The solution is coated on a 12 mic Polyester film using gravure roller to a coating GSM of 0.5+ 1.
[0102.] Acrylic Topcoat coating : Acrylic formulations was prepared as given below and coated on the release coating by using gravure process, The total coating gsm is 1.5-1.7.

[0103.] Neocryl B-890 ; 4 parts
[0104.] Neocryl B811 : 10 parts
[0105.] Neocryl B 723 : 6 parts
[0106.] n-propyl Acetate : 75 parts
[0107.] MEK :25 parts
[0108.] AlOx metallization: Alox metallization is done on acrylic coating layer.
[0109.] Barrier coating on AlOx metallized layer: 10% solution of PVOH is coated on AlOx layer using gravure process. The coating GSM is 1.2.
[0110.] Lamination on Paper : The barrier coated film is laminated with paper using two pack PU adhesive using normal lamination procedure for paper. The laminating adhesive gsm is 3.5. Polyester film is separated from the laminate and this polyester film is reusable several times for similar applications.
[0111.] Heat seal coating : The laminated paper on the release coating side is coated with heat seal lacquer using gravure coating process for 3.2 gsm coating.

Example 4:
[0112.] Release Coating : A 10% solution of cellulose acetate butyrate (CAB) is prepared using alcohol and water mixer in 50:50 ratio. The solution is coated on a 12 mic Polyester film using gravure roller to a coating GSM of 0.5+ 0.1.
[0113.] Acrylic Topcoat coating : Acrylic Polymer recipe as used in Ex.3 was used for coating on release coated layer by using gravure process, The total coating gsm is 1.5-1.7.
[0114.] AlOx metallization: AlOx metallization is done on acrylic coating layer.
[0115.] Barrier coating on AlOx metallized layer: 10% solution of PVOH is coated on AlOx layer using gravure process. The coating GSM is 1.5.
[0116.] Lamination on Paper : The barrier coated film is laminated with paper using two pack PU adhesive using normal lamination procedure for paper. The laminating adhesive gsm is 3.5. Polyester film is separated from the laminate and this polyester film is reusable several times for similar applications.
[0117.] Heat seal coating : The laminated paper on the release coating side is coated with heat seal lacquer using gravure coating process for 3.1 gsm coating.

1. Table.1
b. Direct metallized Paper
Ex Paper GSM Pore filling coating GSM Barrier layer coating GSM Heat seal layer coating GSM OTR MVTR Seal Strength
(g/25mm)
1. 80 10 1.5 3.0 1.8 5.9 >450
2. 80 10 2.1 3.2 0.9 6.5 >450

Table.2
Transfer metallized Paper
Ex Paper GSM Release coating GSM Acrylic top coat GSM Barrier layer coating GSM Heat seal layer coating GSM OTR MVTR Seal Strength
(g/25mm)
3. 60 0.5 1.1 1.2 3.2 5.5 2.5 >400
4. 60 0.5 1.1 1.5 3.1 3.0 2.1 >400

From Table 1 and 2, it can be concluded that
[0118.] The coated paper as per the invention described above can replace plastic film in many applications where weight of the packed product is manageable by paper based packaging.
[0119.] The coated paper is recyclable and repulpable.
[0120.] The coated paper is also biodegradable.

, Claims:We claim:
1. A paper barrier packaging material comprising a substrate, first layer, second layer, AlOx metallized layer and protective layer in the direct metallized paper;
wherein, in direct metallized paper, first coating comprises of Kaolin with particle size 9 mic and aspect ratio 80-100 is taken and mixed with 0.25% of sodium polyacrylate in water followed by mixing with styrene butadiene latex; second layer comprises of PVOH (Poly vinyl alcohol) or cellulose derivative; and
- in transfer metallized paper, the polyester film is coated with release coating, acrylic coating followed by AlOx metallization.
2. The paper barrier packaging material as claimed in claim 1 wherein said substrate is paper base material.
3. The paper barrier packaging material as claimed in claim 1 wherein the first coating comprises of kaolin and sodium polyacrylate which is subsequently mixed with styrene butadiene latex.
4. The paper barrier packaging material as claimed in claim 1 wherein the pore filling coating solution is prepared by mixing 80- 100% kaolin and 0.25% sodium polyacrylate with water and vigorously stirred at high speed stirrer for 15 minutes. The dispersed kaolin is finally mixed with styrene butadiene latex.
5. The paper barrier packaging material as claimed in claim 4 wherein first coating layer comprises of styrene-butadiene latex with kaolin dispersion.
6. The paper barrier packaging material as claimed in claim 5 wherein the second coating layer comprises of 10% PVOH (polyvinyl alcohol) in water.
7. The paper barrier packaging material as claimed in claim 1 wherein protective layer comprises of ethylene acrylic acid.
8. The paper barrier packaging material as claimed in claim 1 wherein transfer metallization paper comprises of polyester film coated with a release lacquer.
9. The paper barrier packaging material as claimed in claim 8 wherein the said release layer comprises 10% solution of cellulose acetate butyrate (CAB) in alcohol and water in the ratio 50:50.
10. A process for the preparation of paper barrier packaging material, wherein the process of preparation of AlOx metallized paper by direct metallization comprises the steps of:

- Coating of substrate with first coating layer,
- Coating of the above substrate with second coating layer
- Carrying out the AlOx metallization on the surface of the above obtained substrate,
- Coating the AlOx metallized surface with protective coating.
11. The process as claimed in claim 10 wherein the compound used for filling up the pores and improving MVTR are of styrene butadiene, styrene acrylic, ethylene vinyl acetate, wax emulsion, butadiene-methyl methacrylate, vinyl acetate-butyl acrylate copolymer, maleic acid copolymer.
12. The process as claimed in claim 11 wherein first layer used for filling up the pores and improving MVTR is styrene butadiene along with fillers kaolin, calcium carbonate, TiO2, clay, mica, talc, barium sulfate, calcium sulfate, zinc oxide, silicate, colloidal silica or other organic pigments.
13. The process as claimed in claim 12 wherein the dispersing agent is sodium polyacrylate.
14. The process as claimed in claim 13 wherein the thickness of first coating layer can be 8- 10g/sqm.
15. The process as claimed in claim 10 wherein the second coating layer can be a gas barrier layer.
16. The process as claimed in claim 15, wherein the second coating layer contains polymers such as PVOH, EVOH, casein, soybean protein or other protein, oxidized starch, cationic starch, hydroxyl ethyl etherified starch, CMC, hydroxyl methyl/ethyl cellulose, poly vinyl pyrrolidone, sodium alginate.
17. The process as claimed in claim 16 wherein the PVOH or cellulose derivative are used as the second coating layer.
18. The process as claimed in claim 17, wherein the second coating layer can be 3-5 g/sqm.
19. The process as claimed in claim 10 wherein the thickness of AlOx metallization is 8- 20 nm.
20. The process as claimed in claim 10 wherein the protective layer can be heat sealable layer.
21. The process as claimed in claim 20 wherein the heat sealable (protective) layer is formed from ethylene acrylic acid (EAA), Ethylene vinyl acetate (EVA), Acrylic copolymer, PVDC copolymer, Polybutyl succinate, aliphatic Polyester, PHA, PLA,

wax, starch, PGA and/or sealants such as Ecoflex or Ecovio which is a compostable polyester by BASF.
22. A process for the preparation of paper barrier packaging material, wherein the process of preparation of AlOx metallized paper by transfer metallization comprises the steps of:
- coating polyester film is coated with release lacquer,
- coating the release lacquered side of the film with acrylic,
- carryout the AlOx metallization on acrylic coated side,
- coating the protective barrier layer
- coating a separate sheet of paper with adhesive
- laminate the adhesive coated paper with AlOx metallized polyester film,
- separate the polyester film from the paper after curing time to get the AlOx metallized paper.
- coating of heat seal layer on coated paper which has been delaminated from polyester film.
23. The process as claimed in claim 22, wherein release coating on polyester film is done using cellulose acetate propionate(CAP), cellulose acetate butyrate(CAB) in water.
24. The process as claimed in claim 23 wherein the deposition of the coating can be 0.4- 0.5 g/sqm.
25. The process as claimed in claim 22 wherein the acrylic can be Poly methyl methacrylate, styrene-methyl methacrylate, isobornyl acrylate/methacrylate, butyl methacrylate-methylmethacrylate, poly tert-butyl acrylate, Poly butylacrylate-methyl methacrylate, polymethyl methacrylate-butyl acrylate-methacrylic acid terpolymer.
26. The process as claimed in claim 25 wherein the coating of acrylic layer is 1.0 to 1.1 g/sqm..
27. The process as claimed in claim 22 wherein the deposition of the barrier coating is 1-3 g/sqm.
28. The process as claimed in claim 22 wherein the thickness of AlOx metallization is 8- 20 nm.
29. The process as claimed in claim 22 wherein the adhesive coating GSM on paper preferably is 3-4.
30. The process as claimed in claim 22 wherein the heat seal layer is coated on release layer of coated paper.

31. The process as claimed in claim 30 wherein the heat sealable layer is formed from ethylene acrylic acid (EAA), Ethylene vinyl acetate (EVA), Acrylic copolymer, PVDC copolymer, Polybutyl succinate, aliphatic Polyester, PHA, PLA, wax, starch, PGA and/or sealants such as Ecoflex or Ecovio which is a compostable polyester by BASF
32. The process as claimed in claim 30 wherein the deposition of heat seal layer is 3-4 g/sq.m