TECHNICAL FIELD The invention relates to laminates for making packages such as sachets and tubes.

BACKGROUND AND RELATED ART Collapsible tubes and pouches are commonly used for packing home and personal care products, especially toothpastes and cosmetic creams. Collapsible tubes are generally made of laminates. Pouches, on the other hand, can be made from monolayer films as well as laminates. Films or laminates are porous and many home and personal care products contain fragrance or flavour. The porous nature causes gradual loss in flavour and fragrance. On the other hand, the shelf life of many home and personal care products is about two years. Therefore, it is desired that such products are packaged in materials that can minimise this loss. This may be minimised by using packaging material with high barrier.

EVOH (Ethylene vinyl alcohol) is often co-extruded with polyolefins to improve barrier. Use of EVOH reduces loss of flavour and fragrance. Aluminium foil is also used widely to improve barrier property, particularly of lamitubes (tubes made from laminated films). Films containing Aluminium foil are often called Aluminium based laminates. The thickness of Aluminium foil in conventional lamitubes is usually 5 to 12 μιτι. Most metalized films are made of polyolefins, especially polyethylene, e.g. High Density Polyethylene (HDPE). However, Aluminium based laminates generally cannot be easily recycled. Higher amount of Aluminium foil makes recycling difficult. Therefore foil based lamitubes have higher environmental impact.

Recent advances in technology have provided an alternative to Aluminium based laminates in which a thin layer of a metal or a metal oxide is deposited on polyolefin films by vacuum metallisation. In this process, a film, generally polyethylene film is first coated with a primer such as aqueous poly vinyl alcohol (PVOH). This forms a base coat over which the thin layer is deposited. EP0680823 A1 (Showa Denwo KK and Showa Highpolymer, 1995) discloses a multilayered laminate having a plastic substrate on which a thin film of a metal or a metal oxide is formed. A layer of polyvinyl alcohol copolymer emulsion or a resin emulsion or a saponified resin of olefin-vinyl acetate copolymer or a polyamide resin or polyvinyl alcohol resin is formed on the film of metal or metal oxide.

WO2001/053077 A1 (Mobil Oil Corporation) discloses multilayer metallised polyolefin film structures having improved barrier properties and reduced water vapour transmission and oxygen transmission properties. The polyolefin substrate has a metal layer and an aqueous primer coating of polyvinylidene chloride, polyvinyl alcohol or acrylic resin.

Normally, aqueous primer coatings of polyvinylidene chloride, polyvinyl alcohol or acrylic resin affect transparency of overcoated metallised layers, presumably due to conditions employed in dryers. Sometimes the film becomes hazy. Further, polyvinylidene chloride generates toxic gases like dioxin when films are

incinerated. On the other hand, Oxygen barrier afforded by acrylic coatings is often inadequate. Aqueous PVOH coatings provide good Oxygen barrier under dry conditions and up to relative humidity of 50%. However, when the relative humidity increases, for example greater than 70 %, the Oxygen barrier and water vapour barrier drops significantly. It is believed that higher water vapour affects the Oxygen barrier because PVOH is water-soluble. Further, at higher relative humidity, PVOH has lower heat resistance and the adhesion may be affected. We have determined that some or all of the problems of prior art multilayered laminates may be solved when the laminate has a polyolefin film which has a coating of a metal or a metal oxide over or underneath a coating of sol-gel polyvinyl alcohol. This also allows for comparatively thinner coatings of polyvinyl alcohol and the metal or the metal oxide. The laminates are easier to recycle and have much lower environmental impact. It is believed that at lower levels, polyvinyl alcohol behaves as a contaminant and may be mixed easily with bulk of the plastic laminate when the film is recycled. Surprisingly, the laminates also very low water vapour transmission rate and Oxygen transmission rate. SUMMARY OF THE INVENTION

According to a first aspect disclosed is a multilayered laminate having a polyolefin film having a coating of a metal or a metal oxide over or underneath a coating of sol-gel polyvinyl alcohol.

According to a second aspect disclosed is a process of making a multilayered laminate comprising, in any sequence, the steps of:

(i) coating sol-gel polyvinyl alcohol on a polyolefin film; and,

(ii) coating a metal or a metal oxide on the film,

wherein the coating of the metal or the metal oxide is applied over the coating of the sol-gel polyvinyl alcohol or vice-versa.

According to a third aspect disclosed is a package made of a multilayered laminate of the first aspect. According to a fourth aspect disclosed is use of a multilayered laminate of the first aspect for making a package

The term "comprising" is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word "about".

It should be noted that in specifying any range of concentration or amount, any particular upper concentration can be associated with any particular lower concentration or amount.

For better understanding of the invention; reference should be made to the following detailed description of preferred embodiments.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect disclosed is a multilayered laminate having a polyolefin film having a coating of a metal or a metal oxide over or underneath a coating of sol-gel polyvinyl alcohol.

It is preferred that the coating of the metal or the metal oxide is over the coating of sol-gel polyvinyl alcohol. Thickness of preferred laminates is 100 to 400 μιτι. Polyolefin film Suitable polyolefins include homopolymers of alpha-olefin, copolymers of two or more kinds of alpha-olefin, or copolymers of alpha-olefin and other compounds which are compolymerisable with the alpha-olefin. Examples of the alpha-olefin include ethylene, propylene, 1 -butene, 1 -hexene, 4-methyl-1 -pentene, 1 -octene, 1 -decene, 1 -dodecene, 1 -tetradecene, 1 -hexadecene, 1 -octadecene, 1 -eicosene and the like having 2 to 20 Carbon atoms. Examples of other compounds include those having a multiple unsaturated bonds such as a conjugated diene or a non- conjugated diene. One or two or more kinds of these compounds may be contained in the polyolefin film. When the polyolefin film contains these other compounds, their amount may be from about 1 to 99 mol%.

Preferred polyolefins include a low-, medium- or high-density polyethylene, a linear low-density polyethylene, a polypropylene, an ethylene-propylene

copolymer, a propylene-butene-1 copolymer, an ethylene-butene-1 copolymer, an ionically crosslinked olefin copolymer (ionomer), and blends thereof.

Particularly preferred polyolefins include low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a medium density polyethylene (MDPE) or a high density polyethylene (HDPE). The term LDPE means an ethylene-containing polymer having density of about 0. 926 g/cm ³ or lower and melt index (Ml) of about 7 g/10 min. LDPE is readily available, e. g., PE 1017 (Ml=7; d=0.917) from Chevron, San Francisco,

California, SLP 9045 (Ml=7.5; d=0.908) from Exxon, Houston, Texas, and ZCE 200 (Ml=3; d=0.918) from Mobil Chemical Corporation, Fairfax, Virginia. The term LLDPE means a copolymer of ethylene and a minor amount of an olefin containing 4 to 10 carbon atoms, having density of from about 0.910 to about 0.926 g/cm ³ and Ml from 0.5 to about 10 g/10 min. LLDPE is readily available, e.g., DOWLEX ^® 2045.03 (Ml=1 .1 ; d=0.920) from Dow Chemical Company, Midland, Michigan.

The term MDPE means an ethylene-containing polymer having density from about 0.926 to about 0.940 g/cm ³ . MDPE is readily available, e. g., DOWLEX ^® 2027A from The Dow Chemical Company, and Nova 74B and Nova 14G from Nova Corporation, Sarnia, Ontario, Canada.

The term HDPE means an ethylene-containing polymer having density of 0.940 g/cm ³ or higher. One particularly suitable HDPE is M621 1 (d=0.958 g/cm ³ ) sold by Equistar. Another particularly suitable HDPE is sold as HD 7845.30 (d=0.958 g/cm ³ ) by Exxon. Other suitable HDPE resins include, for example, BDM 94-25 (d=0.961 g/cm ³ ) and 6573 XHC (d=0.959 g/cm ³ ) which are both available from Fina Oil and Chemical Co., Dallas, Texas and Sclair 19C (d=0.951 g/cm ³ ) and 19F (d=0.961 g/cm ³ ) which are both available from Nova Corporation

Sarnia, Ontario, Canada.

The melt index of preferred HDPE is 0.2 to 10 g/10 minutes, more preferably 0.5 to 2 g/10 minutes. Melt index is generally understood to be inversely related to viscosity and decreases as molecular weight increases. A particularly preferred type of HDPE is s-HDPE. This is commercially available, for example as Exxon HTA ^® 108. Without wishing to be bound by theory, it is believed that s-HDPE further reduces water vapour transmission rate. This grade also enables easier processing with little compromise on stiffness, presumably because of lack of polypropylene. It is believed that this is possible because s- HDPE has higher melt flow index and higher density. Conventional HDPE is generally made by solution process technology, whereas s- HDPE is generally made by dual-reactor solution process technology. Its melt index is about 1 .13 g/10 minutes and density is about 0.967 g/cm ³ .

The polyolefin film may preferably be biaxially oriented before metallization.

Biaxial orientation is employed to evenly distribute the strength of the film in the longitudinal or machine direction (MD) and in the lateral or transverse direction (TD). Biaxially oriented films tend to be stiffer and stronger, and also exhibit much better resistance to flexing and folding forces leading to greater utility in packaging applications.

Further, the polyolefin resin may be suitably modified by including unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, (endo-cis- bicyclo [2,2,1]hepto-5-en-2,3-dicarboxylic acid) or derivatives thereof such as acid halide, acid amide, acid imide, acid anhydride or ester. Preferred examples include maleyl chloride, maleimide, maleic anhydride, citraconic anhydride, dimethyl maleate, glycidyl maleate, methyl aceylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methaceylate, glycidyl acrylate, glycidyl methacrylate, monoethyl ester maleate, diethyl ester maleate,

monomethyl ester fumarate, dimethyl ester fumarate, monobutyl ester itaconate, dibutyl ester itaconate, amide acrylate, amide methacrylate, monoamide maleate, diamide maleate, N-monoethylamide maleate, Ν,Ν-dimethylamide maleate, N- monobutylamide maleate, Ν,Ν-dibutylamide maleate, monoamide fumarate, diamide fumarate, Ν,Ν-diethylamide fumarate, N-monobutylamide fumarate N,N- dibutylamide fumarate, which may be contained in a single kind or in two or more kinds. The modified monomers may form 0.0001 to 3% by weight in the modified polyolefin film. The modified polyolefin should have molecular weight large enough to form a film and its melt flow rate should preferably be from 0.01 to 50 g/10 minutes and particularly from 0.1 to 50 g/10 minutes. In a preferred embodiment of the multilayered laminate, the polyolefin film includes plurality of co-extruded layers of polyethylene. Such co-extrusion can be cast (through a slot die) or blown co-extrusion.

Further preferably, one or more of the plurality of co-extruded layers is made of a polyolefin selected from HDPE (high density polyethylene), LDPE (low density polyethylene), MDPE (medium density polyethylene), LLDPE (lilnear low density polyethylene) or Polypropylene. In a highly preferred embodiment, the film has three co-extruded layers. In such a construction, the film has one layer of HDPE and two layers of other polyolefins. In this case, it is preferred that co-extrusion ratio of polyolefin: HDPE polyolefin is from 1 :2:1 to 1 :4:1 , more preferably 1 :3:1 to 1 :3.6:1 .

Thickness of the polyolefin film is from 20 to 150 μιτι, preferably 50 to 100 μιτι. Coating of sol-gel polyvinyl alcohol

It is preferred that coating weight of the sol gel polyvinyl alcohol is 0.05 to 0.5 g/m ² . Any suitable means of coating may be used. It is believed that at such low levels of coating thickness, polyvinyl alcohol acts as a contaminant and therefore the film becomes amenable to easier recycling. After applying this coating, it may subsequently be dried by hot air, radiant heat or by any other convenient means. The sol-gel PVOH may include hydrolyzed organosilicate, organosiloxane or a silane coupling agent. The PVOH may include a blend of at least two PVOH resins having different degrees of hydrolysis.

The first component of the PVOH blend may have a high degree of hydrolysis of at least about 98%, i.e., about 98% of the acetate groups of the poly (vinyl acetate) have been replaced with alcohol (OH) groups. The second component may have a lower degree of hydrolysis of at least about 80% to 90%. The blend preferably includes a ratio of about 1 :2 to about 20:1 , more preferably from about 2:1 to about 5.1 and most preferably from about 2.5:1 to 3.5:1 .

Without wishing to be bound by theory it is believed that the coating of sol-gel polyvinyl alcohol further improves barrier property, smoothens the film surface, provides good bonding and significantly reduces Oxygen transmission rate and water vapour transmission rate. It also helps in filling up voids after metallization.

Coating of metal or metal oxide

It is preferred that thickness of the coating of metal or metal oxide is 100 to 800 Angstroms. In further preferred films, it is from 350 to 450 Angstroms.

A preferred metal is Aluminium. Metallic coatings are preferred when an opaque or shiny package is desired, e.g. an opaque collapsible tube for toothpastes.

When a metal oxide is coated, it is preferred that the metal oxide is Aluminium oxide or Silicon oxide, more preferably Aluminium oxide. Coating of oxides result in transparent films and such films are used to pack gels, such as gel toothpastes.

It is preferred that the coating is deposited by vapour-deposition. This method is well-known in the art. The adhesion of the top coat may be tested in accordance with ASTM D 3359, but without cross-hatching, by sticking on and rapidly removing an adhesive tape (TESAFILM ^® TP 104). Vacuum deposition includes the batch-cycle method and the continuous system method. Before applying any coating, the surface of the polyolefin film may be treated to increase its surface energy. This may be done by any of several known and conventional techniques.

Further, in applications where even greater adherence between the coatings is desired, an intermediate primer layer can be used to increase the adherence of the first coating to the polyolefin film. Such primer materials are well known in the art and include, for example, epoxy, urethane and polyethylene imine (PEI) materials. The primers provide an overall adhesively active surface for thorough and secure bonding with the subsequently applied coatings and primers can be applied by conventional solution coating means, for example, by mating roller application.

The polyolefin film may include suitable additives, for example stabilizers, neutralizers, lubricants or antioxidants. In principle, additives used for polyolefins, such as polyethylene or polypropylene, are also suitable for cycloolefin polymer films. Examples of UV stabilizers which can be used are absorbers, such as hydroxyphenylbenzotriazoles, hydroxybenzophenones, formamidine or

benzylidenecamphor; quenchers, such as cinnamic esters or nickel chelates; free- radical scavengers, such as sterically hindered phenols, hydroperoxide

scavengers, such as nickel or zinc complexes of sulfur-containing compounds, or light stabilizers and mixtures thereof. Examples of suitable lubricants include fatty acids and esters, amides and salts thereof; silicones or waxes, such as

polypropylene or polyethylene waxes. Examples of antioxidants which can be added are free-radical scavengers, such as substituted phenols and aromatic amines, and/or peroxide scavengers, such as phosphites, phosphates and thio compounds.

Two-layered and three-layered laminates

In a preferred embodiment, the polyolefin film is laminated to a second film by dry lamination or extrusion lamination.

The second film is made of polyolefin, polyethylene terepthalate or nylon, more preferably polyolefin. Laminates with nylon or PET are less preferred as they may be difficult to recycle. It is preferred that the second film has plurality of co- extruded layers.

In a highly preferred embodiment, the second film includes a masterbatch. Masterbatch is a concentrated mixture of pigments or additives encapsulated during a heat process into a carrier resin which is then cooled and cut into a granular shape. Masterbatch allows the processor to colour raw polymers economically during plastics manufacturing process. Masterbatches are used to insert colours and impart special properties to plastic products. A masterbatch contains polymers, additives and colorants specifically formulated together to provide either a general or specific function. The masterbatch may be selected from one or more of color masterbatch, white masterbatch, black masterbatch, filler masterbatch, additive masterbatch or a special effect masterbatch. Some functional masterbatches include UV masterbatch, antifog agents, antiblock agents and antistatic agents.

In another preferred embodiment, the laminate has co-extensive top, middle and bottom films, wherein the polyolefin film is the middle film. In this embodiment, it is preferred that each of the top and bottom films is made of polyolefin, polyethylene terepthalate or nylon, more preferably polyolefin. As in the case of films in the two- layered laminate; it is preferred that the top and bottom film is made of plurality of co-extruded layers of polyolefin. In such cases, it is preferred that the top or the bottom film comprises master batch. If desired, the outermost film can be manufactured by cast extrusion (where it is a single stratum) or co-extrusion (where it consists of a plurality of strata) which is later laminated to the other layers of the film, which preferably are co-extruded. To promote bonding between films, the inner surface of one film may be appropriately treated, for example by corona discharge, or by applying one or more primers, before lamination. If desired, the treated, inner surface can be printed with artwork prior to lamination. If it is desired that any of the films should provide further barrier to gas, particularly Oxygen, it can be made by a cast or blown co-extrusion method. Process

In accordance with a second aspect disclosed is a process of making a multilayered laminate comprising, in any sequence, the steps of:

(i) coating sol-gel polyvinyl alcohol on a polyolefin film; and,

(ii) coating a metal or a metal oxide on the film,

wherein the coating of the metal or the metal oxide is applied over the coating of the sol-gel polyvinyl alcohol or vice-versa.

Package and Use

The film may be used as such for any suitable packaging application, including to make sachets or to make squeezable lamitubes. Pouches may be made by any known means such as by form-fill-seal process. When the intended application is to make pouches; the innermost material should be sealable, preferably by heat sealing. However, it is preferred that the film is used to make laminates, which in turn are used to make, preferably, squeezable tubes. Several processes of making lamitubes are well known in the art.

When the intended application is to make squeezable tubes, the outer and inner films should be capable of being lap-sealed (also called side seam), preferably by application of heat, so that the sides may be sealed off after a product has been filled. In such cases, the innermost film should also bond with itself, so that the bottom of the tube may be closed after a product has been filled.

The invention will now be described with the help of non-limiting exemplary embodiments. EXAMPLES

Structures of some preferred and comparative multilayered laminates are described in table 1 .

Table-1

Example Structure of the multilayered laminate (outermost to

innermost, left to right)

1 LLDPE 1 15 m/adhesive/metalized co-extruded LLDPE 50 μιτι film coated with Aluminium over a coating of sol-gel PVOH/adhesive /LLDPE 50 μηη

2 LLDPE 105 μηη/adhesive/metalized co-extruded LLDPE 50 μιτι coated with Aluminium over a coating of sol-gel PVOH /extruded PE10 μηη/LLDPE 50 μηη

3 LLDPE 100 μηη/extruded PE 10 μιτι /metalized co-extruded

LLDPE 50 μιτι coated with Aluminium over a coating of sol- gel PVOH/extruded PE 10 μηη/LLDPE 50 μηη

4 Co-ex LLDPE 1 15 μηη/adhesive/nnetalized co-extruded

LLDPE 50 μιτι coated with Aluminium oxide over a coating of sol-gel PVOH/adhesive /LLDPE 50 μηη

5 LLDPE 105 μηη/adhesive /co-extruded LLDPE 50 μηη

coated with Aluminium oxide over a coating of sol-gel PVOH /extruded PE 10 μηη /LLDPE 50 μηη

6 LLDPE 100 μηη /extruded PE 10 μηη/LLDPE 50 μηη coated with Silicon oxide over a coating of sol-gel PVOH /extruded PE 10 μηη /LLDPE 50 μηη

7 LLDPE 50 μιτι coated with Aluminium oxide over a coating of sol-gel PVOH /extruded PE 10 μηη /LLDPE 100 μηη /extruded PE 10 μηη /LLDPE 50 μηη

Comparative m-MDPE 105 μηη /adhesive/LLDPE 50 μηη coated with Example -1 Aluminium over a coating of acrylic resin/m-LLDPE 50

μιτι/extruded PE 10 μηη/ηη-MDPE 50 μιτι

Comparative m-MDPE 105 μηη/adhesive/LLDPE 50 μηη coated with Example-2 Aluminium over a coating of aqueous polyvinyl alcohol/m- LLDPE (50 μηη /extruded PE 10 μηη/m-MDPE 50 μm

Comparative m-MDPE 105 pm/adhesive/ LLDPE 50 μm coated with Example-3 Aluminium /extruded PE 10 μηη/ηη-MDPE 50 μιτι General process for preparation of multilavered laminates

One side of the co-extruded polyolefin film was treated with corona discharge on which, a coating of sol-gel polyvinyl alcohol (or other resin as described) was applied using a gravure coater. In the case of sol-gel poly vinyl alcohol, the coating weight was 0.1 g/m ² and temperature of the dryer was maintained around 1 10 °C. Thereafter, the coating of metal or metal oxide was applied by vacuum metallisation method over the coating of polyvinyl alcohol. The pressure in the coating zone was maintained around 6 X10 ^"3 mbar and pressure in the winding zone was maintained around 10 ^"2 mbar whereas the film speed was maintained around 400 m/minute,

Test methods The Oxygen transmission rate and water vapour transmission rate of the preferred and comparative laminates were measured. The methods of analysis are described in table-2.

Table-2

Oxygen transmission rate (OTR) measured at 23 °C and 90 % relative humidity (RH) using OX-TRAN ^® from MOCON

Water vapor transmission rate (WvTR) Measured at 40 °C and 90 % RH

using PERMATRAN ^® from MOCON The results are shown in table 3.

Table-3

The data in table 3 indicates that the Oxygen transmission rate and Water vapour transmission rate of the preferred multilayered laminates (Examples 1 to 7) were significantly lower that that of Comparative examples 1 , 2 and 3.

It will be appreciated that the examples provide a multilayered laminate having significantly lower Oxygen transmission rate (OTR) as well as water vapour transmission rate (WvTR).

Although the invention has been described with reference to specific

embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.