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
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • 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
• • 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
  • B32B2250/00—Layers arrangement
  • B32B2250/24—All layers being polymeric
• • 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
  • B32B2255/00—Coating on the layer surface
  • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
• • 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
  • B32B2255/00—Coating on the layer surface
  • B32B2255/20—Inorganic coating
• • 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
  • B32B2255/00—Coating on the layer surface
  • B32B2255/24—Organic non-macromolecular coating
• • 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
  • B32B2270/00—Resin or rubber layer containing a blend of at least two different 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
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
  • B32B2307/306—Resistant to heat
• • 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
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/412—Transparent
• • 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
  • B32B2307/746—Slipping, anti-blocking, low friction
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]

Definitions

• the invention relates to an antifog mono or multilayer film structure, to a process for the manufacture of such structure and to packaging including such structure.
• a packaging film is heat-sealed to the lip or flange of a tray material to protect the product.
• This headspace is generally filled with a modified atmosphere to extend product shelf life. It is essential that the packaged product remain in clear view to the consumer at retail.
• an antifog agent is desirable to eliminate the undesirable visual effect caused by wet products that generate high humidity inside the package.
• PE film coated with antifog agents may produce a desired effect, but PE film is not as good packaging material as ethylene copolymers such as ethylene vinyl acetate (EVA) copolymers and ethylene methacrylate (EMA) copolymers.
• EVA ethylene vinyl acetate
• EMA ethylene methacrylate
• Such ethylene copolymers have very different chemical and physical properties from PE.
• Inventor's own tests showed that it is difficult to coat an antifog onto films made of ethylene copolymers like EVA and EMA copolymers and that a large amount of antifog agent is required to achieve antifogging effect.
• One of the problems may be due to the repeat units derived from polar monomers such as acetate or acrylate or to the polarity of sealant employed.
• the invention relates to an antifog mono or multilayer film structure comprising at least an external heat sealing layer coated with an antifog agent wherein the external heat sealing layer comprises, or is produced from, an ethylene copolymer or modified ethylene copolymer;
• the ethylene copolymer is a copolymer or terpolymer or tetrapolymer comprising repeat units derived from ethylene and about 5 to about 50 wt % of one or more polar monomers chosen from the group consisting of vinyl alkanoic acid, acrylic acid, alkyl acrylic acid and alkyl acrylate, the weight percentages being based on the total weight of the ethylene copolymer or modified ethylene copolymer.
• the invention also comprises a process for producing a mono or multilayer antifog film structure as described above, comprising dissolving an antifog agent in a solvent to produce an antifog agent solution; applying the antifog agent solution onto the external heat sealing layer to produce a coating thereon; and optionally curing the coating.
• heat sealing layer it is meant a layer which is typically sealable between 95 0 C and 21O 0 C, under pressures ranging between 20 psi and 2000 psi, preferably, between 20 psi and 100 psi, and during periods of time between 0.5 s and 4 s.
• film structure used here may be exchangeable with “laminate” or "sheet”.
• the external heat sealing layer may be peelable.
• peelable heat sealing layer it is meant a layer which is heat sealed onto a given substrate (for example a tray) and which, when peeled from such substrate under stress and speed, it splits adhesively at the seal interface or cohesively within the sealant layer, but always homogeneously, within the peel layer without substantial delamination of the layer itself and/or the substrate taking place.
• the film structure according to the present invention can comprise or be produced from an ethylene copolymer or modified ethylene copolymer or an ionomer thereof.
• An ethylene copolymer can be a copolymer or terpolymer or tetrapolymer comprising repeat units derived from ethylene and about 5 to about 50%, or about 9 to about 25%, or about 10 to about 19%, or 12 to 15%, by weight (wt %) of a polar monomer, the weight percentages being based on the total weight of the ethylene copolymer, the modified ethylene copolymer or the ionomer thereof.
• the polar monomer may contain up to about 20 carbon atoms and the alkyl group can be methyl, ethyl, butyl, isobutyl, pentyl, hexyl, or combinations of two or more thereof.
• polar monomers examples include vinyl acetic acid, vinyl acetate, vinyl propionate, acrylic acid, methacrylic acid, ethacrylic acid, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, octyl acrylate, octyl methacrylate, undecyl acrylate, undecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, 2-eth
• the acid moiety of an ethylene copolymer may be neutralized with a cation to produce an ionomer.
• An ethylene copolymer in which the repeat units derived from an acid that is not neutralized is also referred to as ethylene acid copolymer or acid polymer.
• the neutralization for example, can range from about 0.1 to about 100, or about 10 to about 90, or about 20 to about 80, or about 20 to about 40 percent, based on the total carboxylic acid content, with a metallic ion.
• the metallic ions can be monovalent, divalent, trivalent, multivalent, or combinations of two or more thereof.
• Examples include Li, Na, K, Ag, Hg, Cu, Be, Mg, Ca, Sr, Ba, Cd 1 Sn, Pb, Fe, Co, Zn, Ni, Al, Sc 1 Hf, Ti, Zr, Ce, and combinations of two or more thereof.
• a complexing agent such as stearate, oleate, salicylate, and phenolate radicals can be included, as disclosed in US 3,404,134.
• the ethylene copolymer can be a blend of one or more ethylene copolymers as described above.
• an ethylene copolymer can comprise from 1 to 30 wt % of at least one E/X/Y copolymer wherein E comprises ethylene;
• X is a monomer selected from the group consisting of EVA and EMA; and
• Y is one or more optional comonomers disclosed above;
• X is from 0 to 50 wt % of the total weight of the E/X/Y copolymer, Y is from 0 to 35 wt % of the total weight of the E/X/Y copolymer, wherein the weight percentage of X and Y cannot both be 0, and E being the remainder.
• ethylene copolymers include, but are not limited to, ethylene vinyl acetate (EVA), ethylene methyl acrylate (EMA), ethylene ethyl acrylate (EEA), ethyl acrylate (EA), ethylene butyl acrylate (EBA), ethylene isobutyl acrylate/methacrylic acid, ethylene methyl acrylate maleic anhydride, ethylene butyl acrylate glycidyl methacrylate (EBAGMA) and ethylene butyl acrylate carbon monoxide (EBACO) and butylacrylate (BA).
• EVA ethylene vinyl acetate
• EMA ethylene methyl acrylate
• EAA ethylene ethyl acrylate
• EA ethyl acrylate
• EBA ethylene butyl acrylate
• EBA ethylene isobutyl acrylate/methacrylic acid
• EBAGMA ethylene butyl acrylate glycidyl methacryl
• Such ethylene copolymers can be produced by any means known to one skilled in the art using either autoclave or tubular reactors (e.g., US 3,404,134, US 5,028,674, US 6,500,888 and US 6,518,365).
• an ethylene copolymer can be produced at high pressure and elevated temperature in a tubular reactor.
• the inherent consequences of dissimilar reaction kinetics for the respective ethylene and alkyl (meth)acrylate (e.g. methyl acrylate) comonomers is alleviated or partially compensated by the intentional introduction of the monomers along the reaction flow path within the tubular reactor.
• Such tubular reactor-produced ethylene copolymer has a greater relative degree of heterogeneity along the polymer backbone (a more blocky distribution of comonomers), reduced long chain branching, and a higher melting point than one produced at the same comonomer ratio in a high pressure stirred autoclave reactor.
• ethylene copolymers are commercially available from DuPont. Certain such ethylene copolymers available from DuPont have a melt flow index (g/10 minutes) from about 0.1 to about 10, measured according to ASTM D1238 and comprise repeat units derived from an alkyl acrylate from about 5 to about 30 wt %, the weight percentages being based on the total weight of the ethylene copolymer
• An ethylene copolymer can also include fillers or additives such as slip additive (e.g. n-oleyl palmitamide, stearamide, and benhenamide), anti block agent such as silica (diatomaceous earth or silica dioxide particles), CaCO 3 , UV stabilizer, pigment, or combinations of two or more thereof.
• slip additive e.g. n-oleyl palmitamide, stearamide, and benhenamide
• anti block agent such as silica (diatomaceous earth or silica dioxide particles), CaCO 3 , UV stabilizer, pigment, or combinations of two or more thereof.
• An ethylene copolymer can comprise, or be modified by including, from about 0.001 to about 35, or about 0.1 to about 30 wt % of at least one tackifier, the weight percentages being based on the total amount of the modified ethylene copolymer.
• the tackifier can enhance adhesion to differentiated substrates.
• tackifier also referred to as adhesive, known to one skilled in the art such as those disclosed in US 3,484,405 can be used.
• tackifiers include a variety of natural and synthetic resins and rosin materials.
• the resins can be liquid, semi-solid to solid, or solid, including complex amorphous materials generally in the form of mixtures of organic compounds having no definite melting point and no tendency to crystallize.
• Such resins may be insoluble in water and can be of vegetable or animal origin, or can be synthetic resins.
• the resins can provide substantial and improved tackiness to the composition.
• Suitable tackifiers include, but are not limited to, para-coumarone-indene resins, terpene resins, butadiene- styrene resins, polybutadiene resins, hydrocarbon resins, rosins, and combinations of two or more thereof.
• the coumarone-indene resins have a molecular weight ranging from about 500 to about 5,000.
• Examples of resins of this type that are available commercially include those materials marketed as "Picco"-25 and "Picco"-100.
• the terpene resins include styrenated terpenes and can have a molecular weight ranging from about 600 to 6,000.
• Examples of commercially available resins are marketed as "Piccolyte” S-100, as “Staybelite Ester” #10 (Eastman Chemical, Kingsport, Tennessee), which is a glycerol ester of hydrogenated rosin, and as "Wingtack” 95, which is a polyterpene resin.
• a terpene resin-based tackifier of note is derived from poly-limonene, a monomer recovered from the citrus industry, available as Piccolyte ® C115 from Pinova.
• the butadiene-styrene resins can have a molecular weight ranging from about 500 to about 5,000.
• Example of commercial product is marketed as "Buton" 100, a liquid butadiene-styrene copolymer resin having a molecular weight of about 2,500.
• the polybutadiene resins can have a molecular weight ranging from about 500 to about 5,000.
• a commercially available example is that marketed as "Buton" 150, a liquid polybutadiene resin having a molecular weight of about 2,000 to about 2,500.
• a hydrocarbon resin can be produced by catalytic polymerization of selected fractions obtained in the refining of petroleum, and can have a molecular weight ranging from about 500 to about 5,000. Examples of such resin are those marketed as “Piccopale”-100, and as “Amoco” and “Velsicol” resins. Similarly, polybutenes obtained from the polymerization of isobutylene may be included as a tackifier.
• the tackifier may also include rosin materials, low molecular weight (such as, for example, 1300) styrene hard resins such as the material marketed as "Piccolastic" A-75, disproportionated pentaerythritol esters, and copolymers of aromatic and aliphatic monomer systems of the type marketed as "Velsicol” WX-1232.
• the rosin that may be employed in the present invention may be gum, wood or tall oil rosin but preferably is tall oil rosin.
• the rosin material may be modified rosin such as dimerized rosin, hydrogenated rosin, disproportionated rosin, or esters of rosin. Esters can be prepared by esterifying the rosin with polyhydric alcohols containing from 2 to 6 alcohol groups.
• tackifier resin of note is Regalite R1125 (a hydro carbon) available from Eastman Chemical. A more comprehensive listing of tackifiers, can be found in the
• the tackifier may be either combined directly with the ethylene copolymer or other components disclosed; or pre-melt compounded into a masterbatch formulation.
• a masterbatch formulation Such technology is described in US 6,255,395 and JP 2002 173,653, entire disclosures of both are incorporated herein.
• poly-limonene may be blended with an ethylene/octane copolymer to prepare a tackifier masterbatch that can be added to the remaining components of the composition in a subsequent blending operation.
• ethylene copolymers which form the external heat sealing layer, can be further modified by mixing or blending them with polyethylene and/or polypropylene.
• Typical blends include from 5 to 50 wt % of polyethylene and/or polypropylene, the weight percentages being based on the total amount of ethylene copolymer blend.
• ethylene copolymers which form the external heat sealing layer can be further modified by mixing or blending for example, about 50 to about 90 wt % of one or more of EVA and EMA and about 5 to about 50 wt %, preferably about 5 to about 40 wt % of an ionomer, the weight percentages being based on the total weight of the ethylene copolymers.
• Such blends may further comprise about 5 to about 10 wt % of an EVA masterbatch containing an additive such as slip and anti block concentrate.
• modified ethylene copolymers can include blend of (1) EVA (75 wt %), ionomer (18 wt %), and EVA masterbatch (slip additive and anti block agent; 7 wt %) and (2) EVA (87 wt %), acid copolymer (9 wt %), and EVA masterbatch (slip additive and anti block agent; 4 wt %), the weight percentages being based on the total amount of the modified ethylene copolymers.
• EVA can contain about 4 to about 35 wt % repeat units derived from vinyl acetate, the weight percentages being based on the total amount of the EVA.
• copolymers containing slip and anti block can improve extrusion processing and ease of handling the finished film product, but these additives can contribute to the difficulty for having a functional antifog as they affect surface area making wetting out of the coating more difficult.
• the external heat sealing and/or any additional layer of the film structure according to the present invention may be produced from molten compositions disclosed herein by a number of methods known in the art (for example, cast film extrusion or blown film extrusion).
• the external heat sealing and/or any additional layer of the film structure according to the present invention can be oriented in one direction by hot-drawing in the machine direction with a tensioning device, and annealing. Such layers can also be oriented in two directions (machine direction and transverse direction) by suitable tensioning devices. Because processes for producing films are well known to one skilled in the art, the description of which is omitted herein for the interest of brevity.
• antifog agent or “antifogging agenf refers to a chemical or substance effectively keeping water from condensing on the surface of a plastic film producing undesirable water droplets or fogging or retarding the formation of fog.
• antiifogging amount is the amount that, when coated onto a film, can substantially reduce or remove fogging from the film that is exposed to water or vapor.
• the agent can reduce the surface tension of water thereby reducing the removing fog produced from water.
• the amount of the antifog agent is present in the external heat sealing layer from about 0.03 g to about 1.0 g, preferably from about 0.1 g to about 0.7 g, per square meter of the external heat sealing layer.
• the more polar is the external heat sealing layer the more antifog agent will be needed per square meter of the external heat sealing layer.
• Antifog agent can be a surfactant or a residue of the surfactant that is approved for food use such as alkanoic acids or their ammonium or metal salts, alkanols, alkoxylated compounds, quaternary ammonium salts, alkali metal alkyl sulfates, alkali metal salts of alkaryl sulfonic acids, 1 -alkyl pyridinium salts, or combinations of two or more thereof.
• a surfactant or a residue of the surfactant that is approved for food use such as alkanoic acids or their ammonium or metal salts, alkanols, alkoxylated compounds, quaternary ammonium salts, alkali metal alkyl sulfates, alkali metal salts of alkaryl sulfonic acids, 1 -alkyl pyridinium salts, or combinations of two or more thereof.
• Multilayer film structures according to the present invention can be produced by any methods known to one skilled in the art.
• a multilayer film structure can be produced by charging each of the polymers for the different layers of the structure into separate extruders and melting the component and pumping the melted component through a pipe into a feed block that layers the different flows together just prior to entering an extrusion die manifold as a single flow stream.
• a molten curtain of multiple layers exits the extrusion die and is deposited onto a moving roll which transfers the cooling multi-layer sheet material into a counter rotating moving roll through a gap or nip and then typically to a third cooling roller and subsequently through a take-off system to another nip between two rollers which pulls the sheet to a take-off system.
• polymer materials which can be used for producing additional layers (in addition to the external heat sealing layer) for the multilayer film structures of the present invention include nylon, polypropylene, polyethylene, ionomers, acid copolymers, polyethylene vinyl acetate, polyethylene terephthalate, polystyrene, polyethylene vinyl alcohol (EVOH), polyvinylidene chloride, and combinations of two or more thereof.
• one or more layers of a multilayer film structure of the present invention can have heat shrinkages of 5% to 10% more than the heat shrinkage of the external heat sealing layer disclosed above.
• Such heat shrinkable layers can comprise about 80 wt % or more of a polyester like polyethylene terephthalate and can be biaxially oriented in the range of about 5% to about 55%, or about 5 to 30%, or about 5 to 10% shrink factor.
• An adhesive can be used between two or more layers of a multilayer film structure according to the present invention.
• Any adhesive can be employed such as solvent-less laminating adhesives such as waterborne acrylic emulsions, polyurethane dispersions, elastomer (e.g., polyurethanes), and one and two part 100% solids polyurethane systems are well known to one skilled in the art.
• Solvent type adhesives can also be used such as polyether urethane (e.g., Lamal HSA/Catalyst CR-1-80 available from Rohm & Haas, Philadelphia, Pennsylvania).
• a Lamal HSA adhesive with coreactant laminating adhesive can be applied by any of the well known coating techniques, preferably a gravure station coating typically used in solution coating processes.
• Film structures according to the present invention can include a layer that is not permeable to oxygen, moisture, or both. Such barrier layer may be useful in many food packaging applications.
• the barrier layer can be made from, for example, EVOH or a vinylidene polymer such as polyvinylidine chloride copolymer (PVDC).
• the present invention refers also to a process for producing a film structure as described above.
• the antifog agent which is preferably a glycerol mono oleate
• any solvent preferably one that has a high evaporation rate or volatility under the temperature and pressure of application.
• it can have an evaporation rate of > 0.01 relative to n-butyl acetate which has an assigned value of 1 according to ASTM D3539-87.
• a solvent preferably can be dried at less than 8O 0 C.
• Solvents can include alcohols, ketones, esters, ethers, acids, hydrocarbons or derivatives thereof, and combinations of two or more thereof.
• solvents examples include methanol, ethanol, propanol, isopropanol, acetone, ethyl acetate, butyl acetate, methyl ethyl ketone, tetrahydrofuran, dioxane, octane, decane, cyclohexane, toluene, xylene, methylene chloride, methylene dichloride, ethylene dichloride, carbon tetrachloride, chloroform, perchloroethylene, white spirit, mineral spirits, naphtha, and combinations of two or more thereof.
• the solvent is an alcohol and, still more preferably, it is isopropanol.
• Dilution with a solvent can range from 0.2 to 10 wt % of antifog agent, the weight percentage being based on the total weight of the resulting solution of antifog agent.
• the antifog agent solution can be coated or applied onto an ethylene copolymer external heat sealing layer as disclosed above by any means known to one skilled in the art such as, for example, spraying, dipping, brushing, vapor depositing, printing, spin coating, transferring, flow coating, and combinations of two or more thereof.
• the antifog agent solution can be applied onto such external heat sealing layer, for example, by means of a gravure or anilox cylinder.
• a gravure or anilox cylinder For example, a quadrangular cell can be used. Other types of engraved cylinders available are pyramid and trihelicals. Gravure cylinder cell size and dilution ratios can be adjusted to apply a desired amount of antifog coating depending on the type of cylinder and of ethylene copolymer used.
• the antifog agent can be applied as a pattern or registered on the external heat sealing similar to printing methods. It may be desirable that the antifog agent is in areas on the external heat sealing where it is useful and out of the area where the external heat sealing is actually sealed. Preferred conditions include direct gravure with application cell size (110- 200 lines).
• a container can have an open end which is covered with a film structure as disclosed above, such as for example a peelable lid, and can have any shape such as boxes, blister packs, bottles, trays, cups, and other like-bottomed containers, or forms such as square, rectangular, triangular, round, trapezoid, and other shapes or forms known to one skilled in the art.
• the lid can have a thickness in the range of 12-75, preferably 12-20 micrometers.
• the container can include a product such as produce or fresh produce, meats, readily to eat meals, prepared foods, sea foods, or combinations of two or more thereof.
• the container can be made from any materials known to one skilled in the art such as foam fiber, metal, plastics, papers, or combinations of two or more thereof.
• antifog concentration percentages are by weight and are based on the total weight of the antifog solution.
• An antifog agent was added to the surface of the external heat sealing of a film structure according to the invention by topical coating using the ⁇ ravurety ⁇ irider metering method.
• Differential film structures can be fabricated using either solvent or solvent-less type adhesive systems.
• Antifog agents tested were supplied by Ciba Specialty Chemical under the trade name AtmerTM, in liquid form and could be diluted in ethanol, methanol or isopropanol to the desired concentration level.
• the antifog agents tested were AtmerTM 1440 and AtmerTM 100. AtmerTM 1440 is preferred due to overall antifog performance and being most environmentally friendly.
• Effective antifog concentrations ranged from 0.2 to 10 wt % based on the type of ethylene copolymer of which the heat sealing layer is based and on the gravure cylinder selected in the examples below.
• Antifog agent concentrations varied with different gravure cylinders or with different engraved cell sizes.
• Gravure cylinder cell size and dilution ratios could affect the amount of antifog coating applied to the heat sealing layer of the film structure.
• Typical preparations of multilayer structures having a heat sealing layer coated with an antifog agent included applying adhesive by gravure to 1 st base film e.g.
• polyester, nylon or polypropylene at a coating station as a carrier for the adhesive; continuing through a hot air dryer (1 st dryer system); combining with a 2 nd sealant film applying pressure via hot nip roll; fully laminating roll passes through 2 nd gravure station that applies diluted antifog agent directly onto sealant side of 2nd film; rolling passes through 2 nd dryer system; and onto winding station for finishing rolling.
• a single gravure and drying station process was used.
• a first substrate of 48 gauge (12 ⁇ ) polyester (PET) film known under the trade name Mylar ® supplied by DuPont Teijin Films was adhesive-laminated to a second substrate of 2.5 mil (63.5 ⁇ ) blown film coextr ⁇ ded structure.
• Two blown film structures for lamination were produced as follows: (1) 1.0 mil (25.4 ⁇ ) HDPE/0.5 mil (12.7 ⁇ ) HDPE + LDPE blend/0.5 mil (12.7 ⁇ ) Modified EVA and (2) 1.0 mil (25.4 ⁇ ) HDPE/0.5 mil (12.7 ⁇ ) HDPE + LDPE blend/0.5 mil (12.7 ⁇ ) Modified EMA.
• Two types of modified EVA were used: Appeel® 2044 (EVA A) and
• EMA A Appeel® 20D745
• EMA B Appeel® 20D808
• EMA C Appeel® 20D751
• Adcote 503A adhesive was a polyether urethane component of a two-component laminating adhesive, which required the use of a coreactant. This polyether urethane, in conjunction with coreactant F, functioned as an adhesive for bonding differentiated film materials.
• the adhesive in the coating station was replaced with a diluted solution of Atmer 1440. Diluting of 3, 5 and 7% of the Atmer 1440 antifogging agent in isopropanol to make the solution.
• the laminate was unwound and taken through the coating station using selected 110 and 200 quad engraved gravure cylinder to apply the antifog solution to the modified EVA and EMA heat sealable sides of the film. After the antifog solution was applied, the web was passed though a hot air dryer at 160 0 F (71.1 0 C) in order to remove the solvent and dry the surface. The roll was then wound up into the finished product. The same process was used applying 2 wt %, 3 wt % and 5 wt % antifog solutions to IIWsafhe t ⁇ miriatetl film structure. In all cases the film remained clear and had excellent sealability.
• the example was carried with Intra Roto Laminator/Coater, 200 Quadrangular coating cylinder by coating antifog solution onto the sealant surface of each modified EVA and EMA film at a speed of 50 ft/min (15,24 m/min) to make an antifog-coated film.
• the antifog-coated film was dried at 16O 0 F (71 0 C) by removing any residual solvent and curing the coating on the surface of the film.
• Antifog agent was Atmer 1440 topical solution (3 or 5 wt %) in isopropanol.
• Wet paper towel was placed in the bottom of a polypropylene tray, which was sealed hermetically with the antifog film leaving headspace between the wet towel and plastic lidding film.
• the lidded tray was exposed at 35°F (1.67 0 C). At time intervals (2, 4, 6, 24, 48 hours and 15 days), the appearance of the film was observed and recorded (Table 1). Appearance was rated as 1 (fogging/condensate), 2 (clear condensate-many droplets), 3 (clear/condensate-few droplets), 4 (clear/condensate-minimal droplets), 5 (clear condensate-total wetout 1drop), and 6 (no visible change/no condensate).
• Example 2 The runs shown in Example 2 were repeated with either Modified EVA or Modified EMA as base polymer film coated with antifog. The runs were carried out as disclosed above and the results are shown in Table 2 where "cell” denotes lines of quadranger gravure cylinder cells.
• Example 4 Film structures of Example 3 were bonded to various rigid substrates by heat sealing. The sealability of these structures were measured and compared to the sealability of the same structures bonded to the same substrates but including no antifog agent (control samples, characterized by a "C" before the sample number in Table 3 below). The sealability was measured according to DuPont Test Method CR-188, which corresponds to ASTM Test Method F88. The two methods differed only in the lnstron Crosshead speed which is 12 inches/min (30.48 cm/min) according to the DuPont test and in the range between 8 and 12 inches/min (between 20.32 and 30.48 cm/min) according to the ASTM test.
• test conditions were:
• antifog film structures according to the present invention may therefore facilitate transporting and moving products through the conventional chilled food distribution chains.

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• Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)

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• 2005
  • 2005-11-15 US US11/274,522 patent/US20060105126A1/en not_active Abandoned
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