Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
  • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/042—Coating with two or more layers, where at least one layer of a composition contains a polymer binder
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/044—Forming conductive coatings; Forming coatings having anti-static properties
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/048—Forming gas barrier coatings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/052—Forming heat-sealable coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
  • B32B2307/31—Heat sealable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
  • B32B2307/518—Oriented bi-axially
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2329/00—Polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals
  • B32B2329/04—Polyvinylalcohol
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/10—Homopolymers or copolymers of propene
  • C08J2323/12—Polypropene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2429/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
  • C08J2429/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2429/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2433/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
  • C08J2433/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
  • C08J2433/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical

Definitions

• This invention relates to a multi-layer film structure comprising an oriented polypropylene core layer, a poly(vinyl alcohol) (PVOH) layer, and an acrylic coating.
• Oriented plastic film, specifically biaxially oriented polypropylene film is widely used for packaging products, particularly foods. No single unmodified polymeric film, however, has the gas and moisture barrier characteristics needed for packaging.
• polymeric film having better gas barrier properties.
• the film is then metallized to provide the film with better moisture barrier properties.
• EVOH ethylene vinyl alcohol copolymer
• a polymeric film having a PVOH skin layer is described in European Patent Application 461,772 A2.
• the moisture barrier properties of the PVOH layer are improved by
• acrylic coatings do not adhere well to certain polyolefin film surfaces, e.g. , polypropylene, even when the latter have been subjected to well known pre- treatment operations such as treatment by corona discharge, flame, or oxidizing chemicals. Accordingly, it has often been found necessary to apply a thin intermediate primer layer to the surface of the polyolefin base film before applying heat sealable topcoats. Moreover, the acrylic coatings themselves are not especially effective as oxygen and aroma barriers.
• the present invention relates to a multilayer heat sealable film comprising: (a) an oriented polypropylene film substrate layer; (b) a heat sealable acrylic polymeric coating, and
• the resulting film exhibits excellent oxygen barrier, as well as enhanced sealability evidenced by reduced minimum seal temperature compared to such or similar films lacking the PVOH component.
• minimum seal temperatures can be no greater than 99*C, preferably, no greater than 96*C.
• the minimum seal temperature is the temperature required to achieve a 100 gm/in seal.
• the present invention is particularly suited to providing films having an ultimate seal strength (USS) which is the highest seal strength attainable under practical heat sealing conditions. For the purpose of comparison, a sealing temperature of 270*F is used.
• USS ultimate seal strength
• the present invention can be used to obtain films having a USS of greater than 200 g/in, preferably greater than 300 g/in, or even greater than 400 g/in.
• the film further comprises a suitable primer between the polypropylene film substrate layer and said poly(vinyl alcohol) layer.
• the film may further comprise a suitable primer between the poly(vinyl alcohol) layer and the heat sealable acrylic polymeric coating.
• the present invention relates to a method for preparing an acrylic coated multilayer film which comprises i) providing an oriented polypropylene film core layer; ii) coating said oriented polypropylene film core layer with PVOH on at least one side of said core layer to provide a PVOH coated oriented polypropylene film; and iii) coating the product of ii) with acrylic on said side coated with PVOH.
• the method can further comprise applying a suitable primer to said polypropylene film core layer prior to step ii) and applying a suitable primer to said PVOH coating prior to step iii) .
• the polypropylene film substrate layer used in the present invention can comprise homopolymer polypropylene or ethylene propylene copolymer containing predominantly propylene.
• a preferred embodiment of said polypropylene film substrate comprises a layer of homopolymer polypropylene and a layer of the copolymer.
• the melt flow rate of the polyolefin layer must not be so low that it is too stiff and thus unorientable.
• propylene ethylene copolymers it is preferred that the melt flow rate be from 2.5 to 6.0 grams per 10 minutes at 230°C and a load of 2,160 grams.
• polypropylene it is preferred that the melt flow rate be from 2.5 to 4.5. In this range, orientation of the copolymer or the polypropylene results in the best properties.
• the extruded polypropylene film can be biaxially oriented.
• Biaxially oriented film can be stretched 3.5 to 7.0 times, preferably 4 to 6 times, in the machine direction (MD) , and 5 to 15 times, preferably 6 to 12 times, in the transverse direction (TD) .
• the overall orientation (MD X TD) can range from about 25 to 60. After orientation, the edges of the film can be trimmed and the film wound onto a core.
• PVOH is of a suitable grade which can be applied to the oriented polypropylene film substrate through a solution coating process, as described in European Patent Application No. 461,772 or U.S. Pat. No. 5,192,620, incorporated herein by reference.
• Poly(vinyl alcohol) is typically produced by hydrolyzing poly(vinyl acetate) . Specifically, the hydrolysis reaction replaces the acetate groups with alcohol groups. The more acetate groups that are replaced, the greater the hydrolysis of the PVOH. It is believed that the presence of more alcohol groups (i.e., greater hydrolysis) provides better barrier properties.
• PVOH poly(vinyl alcohol) may be produced with various viscosities and various degrees of hydrolysis. Viscosity is typically a function of the molecular weight of the PVOH molecule.
• a solution of PVOH in which the individual molecules are relatively large tends to have a higher viscosity than a solution of PVOH in which the individual molecules are relatively small (i.e., a low molecular weight PVOH). It is believed Van der Waals forces develop between the larger-sized molecules because such molecules tend to align themselves with one another, thus increasing the viscosity of the PVOH.
• a poly(vinyl alcohol) such as Elvanol 71-30 (produced by DuPont) is typically referred to as a medium viscosity, fully hydrolyzed PVOH. Specifically, the degree of hydrolysis of a fully hydrolyzed PVOH is about 98%.
• the viscosity of a medium viscosity grade PVOH such as Elvanol 71-30 is about 30 cps at 4% solution and 20'C.
• PVOH polyvinyl alcohol
• Elvanol 75-15 also produced by DuPont
• the degree of hydrolysis is about 98% and the viscosity is about 13 cps at 4% solution and 20"C.
• Still another commonly available PVOH is Elvanol 90-50 (also produced by DuPont) , which is a low viscosity super hydrolyzed PVOH.
• the degree of hydrolysis in a super hydrolyzed PVOH is about 99.5%.
• the viscosity of a low viscosity grade PVOH such as Elvanol 90-50 is about 13 cps at 4% solution and 20*C.
• Another commercial source of extrudable PVOH is Vinex resin manufactured by Air Products and Chemicals, Inc.
• coating processes include a reverse direct gravure process and a smooth rod process.
• the gravure process typically produces a higher level of foam than the smooth rod process.
• the tensoactive agent reduces the degree of foaming, while simultaneously lowering the surface energy of the coating solution.
• the combination of reduced foaming and lower surface energy provides improved processing characteristics which result in a barrier exhibiting reduced transmission of oxygen, particularly at high relative humidities.
• the coating solution of the present invention preferably includes approximately 200 to 500 ppm of 1-octanol and, more preferably, about 250 ppm of 1-octanol.
• the coating solution preferably includes from 5 to 50 ppm of 1-octanol. This lower level of tensoactive agent provides improved processing characteristics and reduces the likelihood that the subsequently-formed oxygen barrier will suffer any negative impacts from the inclusion of such agent in the solution.
• the solution which is preferably aqueous, is prepared by adding the poly(vinyl alcohol) to cold water, which is thereafter heated to a temperature sufficient to dissolve the PVOH.
• the water and dissolved PVOH are then cooled.
• the cross-linking agent i.e., the glyoxal
• an effective amount of the tensoactive agent is added to the solution. It is this resultant solution that is then coated on the polymeric substrate.
• the aqueous solution includes from 4% to 14% by weight of solid and, preferably, from 5% to 10% by weight of solid.
• This solid content is made up from 70% to 95% by weight of poly(vinyl alcohol), from 5% to 30% by weight of cross-linking agent and from 5 ppm to 0.5% by weight of octanol.
• the film is rolled through a drying oven.
• a typical drying oven is approximately 60 feet long and adapted to heat the film to approximately 130*C.
• the film is rolled through the oven at speeds of about 1000 feet per minute.
• the water in the applied coating is driven off which, in turn, increases the concentration of the solid content.
• the cross-linking process is initiated. This cross-linking process occurs rapidly and completely throughout the PVOH layer such that the film is substantially 100% cross-linked by the time such film leaves the drying oven.
• the heat sealable acrylic polymeric coating can, for example, be derived from any of the terpolymeric compositions disclosed in U.S. Pat. No. 3,753,769, the contents of which are incorporated herein by reference.
• These coating compositions contain as a film forming component a resin consisting essentially of an interpolymer of (a) from 2 to 15, and preferably from 2.5 to 6, parts by weight of an alpha-beta monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, and mixtures thereof, and (b) from 85 to 98, and preferably from 94 to 97.5, parts by weight of neutral monomer esters, said neutral monomer esters preferably comprising (1) methyl acrylate or ethyl acrylate and (2) methyl methacrylate.
• interpolymer compositions are further characterized as preferably comprising from 30 to 55 percent by weight of methyl methacrylate when said alkyl acrylate is methyl acrylate, and from 52.5 percent to 69 percent by weight of methylmethacrylate when said alkyl acrylate is ethyl acrylate.
• Such coating compositions can be applied to the films herein in a variety of ways including in the form of ammoniacal solutions. Similarly useful are copolymeric coating compositions prepared exclusively from the foregoing neutral monomer esters. These coating compositions are advantageously applied to the film laminates in the form of emulsions.
• An adhesive tie layer can be used to enhance adhesion between the PVOH layer and the polypropylene film substrate layer when such layers are incompatible in their natural state.
• the adhesive layer when used can be any of a number of proprietary materials such as described in U.S. Pat. No. 4,561,920.
• Suitable adhesives include CXA-3036 (TM) (an ethylene-vinyl acetate copolymer available from DuPont) , a high density polyethylene based adhesive, e.g., Bynel 4003 (TM) available from DuPont, the Admer (TM) adhesives from the Mitsui Petrochemical Company, e.g., NF500A (TM) and NF 550A (TM) , and the Plexar (TM) family from USI Chemicals, e.g., a maleic anhydride grafted LDPE, Quantum Plexar 201 (TM) .
• Suitable maleic anhydride modified polyolefins include maleic anhydride modified polypropylene homopolymer or copolymer which are especially suitable for use as adhesive tie layer in the present invention. Such materials result from the reaction between maleic anhydride and the thermal degradation product of polypropylene or polypropylene copolymer. Examples of this material are disclosed in U.S. Pat. No. 3,480,580, the contents of which are incorporated herein by reference in its entirety. Particular attention is directed to Examples 3, 4, and 6 of this patent.
• a commercially available maleic anhydride modified polypropylene is Epolene E-43(TM), from Eastman Kodak Company of Rochester, NY.
• the adhesive tie layer can be dispensed with by including an adhesion promoter in the polyolefin layers as described in U.S. Pat. No. 4,650,721, which is incorporated herein by reference. That patent discloses polyolefin layers (polypropylene) which contain a maleic anhydride modified olefin polymer. PVOH coating is preferably applied over an appropriate primer interface to assure adequate bonding to the base substrate. A second bonding primer layer can also be applied onto the PVOH layer to provide adequate bonding for the acrylic layer. Typical primers for such purpose include an aqueous polyethyleneimine solution.
• Polyethyleneimine primer is commercially available and is generally applied as a 0.1%-0.6% by weight polyethyleneimine solution in water or organic solvent.
• the use of PEI as a primer or adhesive for polymeric coatings to films substrates is well known to the art, as disclosed in U.S. Pat. No. 3,230,135, incorporated herein by reference.
• Epoxy polymers and polyurethanes are also useful as primers. Such primer compositions are disclosed in U.S. Pat. NOS. 4,447,494, 4,681,803, and 3,023,125, which patents are incorporated herein by reference.
• the PVOH layer preferably after priming, is coated with the acrylic polymeric coating by conventional techniques as noted above. Such coating can be carried out either before or after, preferably after, the PVOH layer is combined with the polyolefin core layer.
• the present invention relates to a method of making a biaxially oriented composite barrier film having two or more layers which can be conducted in a continuous manner.
• a polypropylene sheet is formed by extrusion. As the sheet exits the die, it is immediately cooled by use of a cooling drum or a water bath to a temperature of about 40 to 50*C. Immediately after cooling, the sheet can be fed into an apparatus for MD orientation of the plastic material. Any such apparatus can be used in the present invention. In one embodiment, the composite sheet is fed into a set of differential speed heated rollers to stretch the sheet in the longitudinal direction to a degree ranging from greater than 1:1 and less than 2:1, preferably about 1.2:1 to 1.5:1, say, e.g., 1.3:1.
• the sheet can be fed to a tenter frame where it is stretched in the transverse direction to a degree of greater than 5:1, preferably from 5:1 to 12:1, e.g., 8:1 to 9:1.
• MD orientation is generally conducted by preheating the film at 130"C to 145*C, stretching in the same temperature range, and annealing at about 115*C to 125'C.
• Preheating for TD orientation is advantageously done at 160 ⁇ C to 175 ⁇ C, stretching at 145 ⁇ C to 160"C, and annealing at 155°C to 165 ⁇ C.
• the oriented polypropylene sheet is thereafter primed with a suitable epoxy or PEI primer and then solution coated with PVOH barrier layer to provide a PVOH layer of 0.015 to 0.035 mil.
• the PVOH coating of the sheet is thereafter primed to provide suitable bonding between PVOH and acrylic heat seal layer which is thereafter applied by the above-described process.
• the sheet can optionally be subjected to treatment in the known manner, e.g., corona discharge treatment or flame treatment, to improve its surface characteristics, e.g., printability.
• treatment in the known manner, e.g., corona discharge treatment or flame treatment, to improve its surface characteristics, e.g., printability.
• the multilayer heat sealable film of the invention can have an overall thickness ranging from 0.50 to 2.0 mil.
• the films of this invention are suitable in a variety of applications in which moisture and gas barrier properties are desired.
• the films are particularly useful in food packaging.
• the invention is illustrated by the following non- limiting examples in which all parts are by weight unless otherwise specified.
• Sample 1 was produced.
• a solution of Elvanol 71-30, Parez 613 (a methylated melamine formaldehyde) and ammonium chloride was coated onto a polymeric substrate of biaxially oriented polypropylene approximately .75 mils thick.
• the solution contained 6% by weight of solid.
• the solid contained approximately 83% by weight of PVOH, approximately 15% by weight of methylated melamine formaldehyde and approximately 2% by weight of ammonium chloride.
• the substrate was treated with a poly(ethyleneimine) primer prior to application of the coating.
• the coating was applied to the polypropylene substrate using a smooth rod process.
• the coated substrate was rolled through a dying oven about 60 feet in length at about 800 feet per minute, heating the film to 130'C and initiating cross- linking.
• the film was then measured for oxygen transmission at 0% relative humidity, minimum seal temperature, and ultimate seal strength. As can be seen from the results set out in the Table below, seal properties were unacceptable.
• a polymeric substrate of biaxially oriented polypropylene 0.75 mils thick was coated with an acrylic coating solution prepared in accordance with Example l of U.S. Pat. No. 3,753,769, which is incorporated herein by reference in its entirety.
• the substrate was treated with a poly(ethyleneimine) primer prior to application and drying of the coating.
• the film was then measured for oxygen transmission at 0% relative humidity, minimum seal temperature, and ultimate seal strength. As can be seen from the results set out in the Table below, oxygen transmission properties were unacceptable.
• the solution contained 8% by weight of solid.
• the solid contained approximately 85% by weight of PVOH, approximately 15% by weight of cross-linking agent and 250 ppm of 1-octanol.
• Low temperature seal coating composition was prepared by adding to an aqueous solution or fine dispersion of 25 wt.% of an ammonium salt of a copolymer of 80 wt.% of ethylene and 20 wt.% of acrylic acid, sold by Michelman as Primacor 4983, varying amounts of sodium hydroxide (NaOH) , poly(oxymethylene) sorbitan monooleate anti-static agent (A-S) , sold as Glycosperse 0-20, microcrystalline wax having an average size of about 0.12 to 0.2 micron (MWX) sold by Michelman as 41540, and melamine-formaldehyde cross-linking agent (M-F) sold as Cymel 385.
• aqueous solution or fine dispersion 25 wt.% of an ammonium salt of a copolymer of 80 wt.% of ethylene and 20 wt.% of acrylic acid, sold by Michelman as Primacor 4983, varying amounts of sodium hydroxide (NaOH
• talc talc
• Sample 4 was produced by the procedure set out in Example 3 except that the low temperature seal coating was substituted by the acrylic coating of Example 2. The characteristics of the film were thereafter measured and the results are set out in the Table below.
• Sample 5 was produced.
• a solution of Elvanol 71-30, Parez 613 (a methylated melamine formaldehyde) and ammonium chloride was coated onto a polymeric substrate of biaxially oriented polypropylene approximately .75 mils thick.
• the solution contained 6% by weight of solid.
• the solid contained approximately 83% by weight of PVOH, approximately 15% by weight of methylated melamine formaldehyde and approximately 2% by weight of ammonium chloride.
• the substrate was treated with a poly(ethyleneimine) primer prior to application of the coating.
• the coating was applied to the polypropylene substrate using a smooth rod coating process.
• the low temperature seal coating set out in Example 3 was applied to the PVOH layer.
• the resulting product contained 10% cross-linked PVOH.
• the characteristics of the film were thereafter measured and the results are set out in the Table below.
• Example 5 except that the low temperature seal coating was substituted by the acrylic coating of Example 2. The characteristics of the film were thereafter measured and the results are set out in the Table below.
• Sample 7 was produced by the procedure set out in Example 6 except that the PVOH coating was primed with an epoxy primer prior to coating with the acrylic coating. The characteristics of the film were thereafter measured and the results are set out in the Table below.
• Sample 8 was produced by the procedure set out in Example 6 except that the PVOH coating was primed with a polyethyleneimine (PEI) primer prior to coating with the acrylic coating. The characteristics of the film were thereafter measured and the results are set out in the Table below.
• PEI polyethyleneimine

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• 1995
  • 1995-12-04 EP EP95941511A patent/EP0794861A4/de not_active Withdrawn
  • 1995-12-04 AU AU42911/96A patent/AU692026B2/en not_active Ceased
  • 1995-12-04 WO PCT/US1995/015659 patent/WO1996016799A1/en not_active Application Discontinuation
  • 1995-12-04 CA CA002203915A patent/CA2203915A1/en not_active Abandoned
  • 1995-12-04 JP JP8519104A patent/JPH10510487A/ja active Pending

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