CA2160581C - Coated films with good low temperature sealing properties and hot tack - Google Patents
Coated films with good low temperature sealing properties and hot tack Download PDFInfo
- Publication number
- CA2160581C CA2160581C CA002160581A CA2160581A CA2160581C CA 2160581 C CA2160581 C CA 2160581C CA 002160581 A CA002160581 A CA 002160581A CA 2160581 A CA2160581 A CA 2160581A CA 2160581 C CA2160581 C CA 2160581C
- Authority
- CA
- Canada
- Prior art keywords
- ethylene
- copolymer
- film according
- coated
- coated film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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
-
- 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
-
- 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
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
-
- 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
- C08J7/0427—Coating with only one layer of a composition containing 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
- C08J7/044—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
- C08J7/046—Forming abrasion-resistant coatings; Forming surface-hardening coatings
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
- C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
- C09D123/04—Homopolymers or copolymers of ethene
- C09D123/08—Copolymers of ethene
-
- 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
- B32B2250/242—All polymers belonging to those covered by group B32B27/32
-
- 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
- B32B2255/26—Polymeric 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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/40—Properties of the layers or laminate having particular optical properties
- B32B2307/41—Opaque
-
- 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
-
- 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
- C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
-
- 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
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/91—Product with molecular orientation
-
- 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
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
- Y10T428/259—Silicic material
-
- 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
- Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
- Y10T428/2813—Heat or solvent activated or sealable
- Y10T428/2817—Heat sealable
- Y10T428/2826—Synthetic resin or polymer
-
- 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
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31855—Of addition polymer from unsaturated monomers
- Y10T428/31909—Next to second addition polymer from unsaturated monomers
- Y10T428/31913—Monoolefin polymer
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Laminated Bodies (AREA)
- Wrappers (AREA)
- Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
Abstract
Novel coated films ate disclosed wherein a base polymer film, e.g., oriented isotactic polypropylene, is coated with a composition comprising a copolymer of about 65 to 95 wt.% ethylene and about 5 to 35.% of acrylic or methacrylic acid (an "ethylene copolymer") based on the weight of the polymer in which about 2 to 80 % of the carboxylate groups are neutralized with metal ions from Group Ia, IIa or IIb of the Periodic Table, preferably sodium ions. Preferably the coating also contains microcrystalline wax and fumed silica. The coated films exhibit good low temperature sealing properties accompanied by satisfactory hot tack and resistance of the seals to immersion in water.
Description
COATED FILMS WITH GOOD LOW TEMPERATURE
SEALING PROPERTIES AND HOT TACK
r This invention relates to novel coated films such as oriented polypropylene having good hot tack, and low blocking, together with satisfactory low temperature sealing and other properties.
Coatings comprising copolymers of ethylene and acrylic acid (EAA) have advantages over various previously used coatings, such as good low temperature sealing properties, water immersible seals, and resistance to crazing when flexed. However, when these coatings are applied to the sealable side of a base polymer film such as oriented polypropylene (OPP), it has been found in some instances that it would be desirable to have improved hot tack and blocking properties, particularly when the coated film is utilized on a relatively high speed packaging machine. Thus, any means to accomplish the foregoing improvements would be beneficial.
In accordance with the present invention, there is provided a base polymer film coated with a composition comprising a copolymer comprising 65 to 95 wt.% ethylene and 5 to 35 wt.% of acrylic or methacrylic acid (an °'ethylene copolymer") based on the weight of the polymer, wherein 2 to 80% of the carboxylate groups are neutralised with metal ions from Groups Ia, IIa, or IIb of the Periodic Table.
Suitably, the copolymer is coated directly onto the base polymer film.
It has been found that the foregoing coated film wherein the base polymer film is, for example, oriented Y
polypropylene, provides for good hot tack and blocking properties accompanied by satisfactory low temperature ' sealing and resistance of the seal to immersion in water.
~~e ethylene copolymer utilized in the compositions of this invention may be a copolymer of 65 to 95 wt.%, preferably 7~ ~0 85 wt.% of ethylene, and 5 to 35 wt.%, _ 2 _ preferably 15 to 25 wt.% of acrylic acid (AA) or methacrylic acid (MA). The copolymer may have a number average molecular weight (Mn) of, for example, 2,000 to 50,000, preferably 4,000 to 10,000.
The ethylene copolymer is often supplied as a solution v or fine dispersion of an ammonium salt of the copolymer in an ammoniacal water solution. When the copolymer is dried, ammonia is given off and the ionized and water sensitive carboxylate groups are converted to largely unionized and l0 less water sensitive free carboxyl groups. In practicing this invention, however, there is added to the solution or dispersion of the ethylene copolymer an amount of ions of at least one metal from Group Ia, IIa or IIb of the Periodic Table, preferably, sodium, potassium, lithium, calcium or zinc ions, and most preferably sodium ions, e.g., in the form of their hydroxides. The quantity of such metallic ions may be sufficient to neutralize, for example, 2 to 80%, preferably 10 to 50% of the total carboxylate groups in the copolymer. The presence of such metallic ions has been found to result in an improvement in certain properties, e.g., coefficient of friction (COF), hot tack, and blocking, without an unacceptable sacrifice of other properties, e.g., low minimum seal temperatures (MST).
When the ethylene copolymer is a copolymer of 80 wt.% of ethylene and 20 wt.% of acrylic acid and the neutralizing metal ions are sodium ions added as sodium hydroxide, then the amount of sodium hydroxide added corresponding to the foregoing percentages of carboxylate groups neutralized, is, for example, 0.33 to 8.8 phr, preferably 1.1 to 5.5 phr, where "phr" stands for parts by weight per hundred parts of the total resin, which is the same as ethylene copolymer when no other resin is present. For the purpose of determining the phr of various additives present in the coating, all the carboxylate groups of the ethylene copolymer are assumed to be in their free carboxyl (-COOH) form.
In addition to the partially neutralized ethylene copolymer, the coatings of this invention preferably contain WO 94/25270 ' ~ ~ PCTIUS94I04654 a relatively large particle size microcrystalline wax as an anti-blocking agent. The microcrystalline wax may be present in the coating in an amount of, for example, 2 to 12 phr, preferably 3 to 5 phr, wherein the wax particles have an average size in the range of, for example, 0.1 to 0.6 V
microns, preferably 0.12 to 0.30 microns.
In addition to functioning as an anti-blocking material, the microcrystalline wax when incorporated into the coatings of the present invention also functions to improve the "cold-slip" properties of the films coated therewith, i.e., the ability of a film to satisfactorily slide across surfaces at about room temperatures.
The coatings of this invention also preferably contain fumed silica for the purpose of further reducing the tack of the coating at room temperature. The fumed silica is composed of particles which are agglomerations of smaller particles and which have an average particle size of, for example, 2 to 9 microns, preferably 3 to 5 microns, and is present in the coating in an amount, for example, of 0.1 to 2.0 phr, preferably 0.2 to 0.4 phr.
Other optional additives which can be used, include particulate materials such as talc which may be present in an amount, for example, of 0 to 2 phr, cross-linking agents such as melamine formaldehyde resins which may be present in an amount, for example, of 0 to 20 phr, and anti-static agents such as poly(oxyethylene) sorbitan monooleate which may be present in an amount, for example, of 0 to 6 phr.
A particular type of thermoplastic film which can be advantageously coated with the coating compositions of this invention is molecularly oriented, isotactic polypropylene.
After extrusion of the base polypropylene film utilizing conventional extrusion techniques, the film is heated and molecularly oriented by stretching it both a longitudinal and i~
transverse direction. The resultant oriented film exhibits greatly improved tensile and stiffness properties. However, it is difficult to heat seal by conventional techniques because at the requisite sealing temperature, i.e., on the .,. _ 4 _ order of about 350°F, film disorientation and shrinkage occur which can result in the film rupturing and tearing apart. An advantage of this invention when such oriented films are subjected to surface treatment as described hereinafter and subsequently coated with the present coating compositions is that they can be sealed by temperatures sufficiently low to ' prevent shrinkage of the substrate, i.e., the oriented polypropylene film.
The foregoing description of base films containing a major proportion of polypropylene is intended to include not only films wherein the polymer is composed entirely of isotactic polypropylene homopolymer, but also coextruded multilayer films wherein the polymer of at least one layer is isotactic polypropylene homopolymer, and the polymer of one or both outer layers is a polymer, preferably an olefin polymer, having better sealability than isotactic polypropylene homopolymer. Such surface layer polymer may be, for example, a copolymer of propylene with a minor amount of one or more other 1-olefins, e.g., ethylene or ethylene and butylene or a high density polyethylene.
Other base polymer films which may be coated in accordance with this invention are those composed of polyolefins other than polypropylene, e.g., polyethylene and those composed of non-hydrocarbon polymers, e.g., polyesters such as polyethylene terephthalate (PET) and polyamides (nylons).
In general, the uncoated substrate films employed in the practice of the present invention are usually from 0.5 to 3.0 mils in thickness. Of particular interest are coextruded three layer films~wherein the polymer of the central core layer is isotactic polypropylene homopolymer having a thickness, for example, of 70 to 98~ of the total thickness ' of the film, the remainder being two thin outer layers of substantially identical thickness wherein the polymer is an ' isotactic copolymer of propylene, ethylene in an amount of, for example, 1 to 5 wt.~ of the copolymer, and optionally, butylene in an amount, for example, of 0.5 to 2 wt.~ of the 94/25270 ~ -~ PCT/US94104654 _ 5 _ copolymer. Also of substantial interest is a coextruded five layer film wherein the polymer of the central core layer is an opaque isotactic polypropylene homopolymer with voids produced by stretch orienting such layer containing spherical particles of a material higher melting than and immiscible with isotactic polypropylene homopolymer, e.g., polybutylene terephthalate, as shown, for example, in U.S. Patents Nos.
4,632,869 and 4,720,416, such core layer having a thickness, for example, of 70 to 90% the total thickness of the film;
the polymer of the layers contiguous to the central core layer is isotactic polypropylene homopolymer without voids, the thickness of such layers being substantially the same and being, for example, 2 to 10% of the total thickness of the film; and the polymer of the outer layers is a copolymer of propylene, ethylene and optionally, butylene, as described previously in connection with three layer films, each outer layer having substantially the same thickness, which is, for example, 1 to 5% of the total thickness of the film.
The coatings of this invention are particularly useful when applied to thicker films, e.g., of 1 to 2 mils, within the foregoing range, intended to be fed to a relatively high speed horizontal form fill and seal (HFFS) packaging machine operating at a speed of, for example, about 125 to 200 feet per minute (fpm). For this purpose, the percentage of carboxylate groups in the ethylene copolymer which should be neutralized, e.g., with sodium, should be in the range, for example, of 2.7 to 27%, preferably about 13.5% to prevent the film from failing in packaging operation due to low hot tack, high blocking, and high COF. When the ethylene copolymer is composed of 80 wt.% of ethylene and 20 wt.% of acrylic acid, the amount of sodium hydroxide to be added to the ethylene copolymer corresponding to the foregoing range is 0.3 to 3.0 phr, preferably 1.5 phr.
When the coated film is fed to a vertical form fill and seal (VFFS) packaging machine which operates at a somewhat lower speed than a HFFS machine, e.g., 25 to 75 fpm, the percentage of carboxylate groups in the ethylene copolymer which should be neutralized may be somewhat higher than when the film is fed to a HFFS machine, e.g., 18 to 45%, preferably about 31.5%, corresponding to an amount of sodium hydroxide added to the ethylene copolymer of 2 to 5 phr, preferably about 3.5 phr when the copolymer is composed of 80 wt.% of ethylene and 20 wt.% of acrylic acid.
To further improve the performance of the film in packaging operation, the second face of the film, i.e., other than the face coated with the composition of this invention, may be coated with a composition comprising a terpolymer of 2 to 15 wt.% of acrylic or methacrylic acid, 10 to 80 wt.% of methyl or ethyl acrylate, and l0 to 80 wt.% of methyl methyacrylate, together with colloidal silica and carnauba wax, as described in U.S. Patent No. 3,753,769. Such coating has the effect of reducing the coefficient of friction and slip and also improving the ink adhesion of that surface of the film.
Before applying the coating composition to the appropriate substrate, the surface of the substrate film can be treated to insure that the coating will be strongly adherent to the film thereby eliminating the possibility of the coating peeling or being stripped from the film. This treatment can be accomplished by employing known prior art techniques such as, for example, film chlorination, i.e., exposure of the film to gaseous chlorine, treatment with oxidizing agents such as chromic acid, hot air or steam treatment, flame treatment and the like. Although any of these techniques can be effectively employed to pretreat the film surface, a particularly desirable method of treatment is the so-called electronic treatment method which comprises exposing the film surface to a high voltage corona discharge while passing the film between a pair of spaced electrodes.
After electronic treatment of the substrate film surface, it can be coated with the coating composition of the present invention which coating will then exhibit a tendency to more strongly adhere to the treated film surface.
In applications where even greater coating-to-film WO 94!25270 ~.~ ~ PCTIUS94104654 adherence is desired, i.e., greater than that resulting from treatment of the film surface by any of the previously described methods, an intermediate primer coating can be employed. In this case, the film is first treated by one of the foregoing methods, electronic treatment being a preferred d method, to provide increased active adhesive sites thereon (thereby promoting primer adhesion) and to the thus-treated film surface there is subsequently applied a continuous coating of a primer material. Primer materials which are suitable are well known in the art and include, for example, titanates and polyethylene imine). The primer is applied to the electronically treated base film by conventional solution coating means. A particularly effective primer herein is polyethylene imine) applied as either an aqueous or organic solvent solution, e.g., of ethanol, containing about 0.5 wt.%
of the imine.
The coating composition is applied to the treated surface of the polymer film in any suitable manner such as by gravure coating, roll coating, dipping, spraying, etc. The excess aqueous solution can be removed by squeeze rolls, doctor knives, etc. The coating composition will ordinarily be applied in such an amount that there will be deposited following drying, a smooth, evenly distributed layer of from 0.02 to 0.10 mil thickness. In general, the thickness of the applied coating is such that it is sufficient to impart the desired sealability, coefficient of friction (COF), and hot slip characteristics to the substrate polymer film.
The coating once applied to the film is subsequently dried by hot air, radiant heat or by any other suitable means thereby providing a non-water soluble, clear, adherent, glossy coated film product useful, for example, as a packaging film.
The following examples further illustrate the invention.
Examples 1-33 Thirty-three coating compositions were 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 _ g _ 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. In addition, 0.4 phr of talc and 0.1 phr of fumed silica having an average particle size of 3 to 5 microns sold as Syloid*72 were also added to each composition. All the components were added as an aqueous disperson or solution except the anti-static agent which was added as a pure liquid. Water was then added to bring the final coating composition to a solids content (% SOL) of between 11 and 15 wt.%.
Each of the foregoing coating compositions was applied to one surface of coextruded, three laye~,~biaxially oriented polypropylene film samples having a total thickness of about 0.9 mil. The polymer of the core layer of each film was a polypropylene homopolymer having a high isotactic content and a melt index of about 3.0, and such core layer was about 0.856 mil in thickness. The polymer of the outer layers was an isotactic copolymer of propylene and about 3.55 wt.% of ethylene, based on the weight of the copolymer, having a melt index of about 6.8. The thickness of each of the outer layers was about 0.022 mil.
The other surface of each of the thirty-three film samples was coated with a composition comprising a terpolymer of methyl methacrylate methyl acrylate and methacrylic acid, colloidal silica, and carnauba wax, with a total solids content of about 13 wt.% as described in U.S. Patent No.
SEALING PROPERTIES AND HOT TACK
r This invention relates to novel coated films such as oriented polypropylene having good hot tack, and low blocking, together with satisfactory low temperature sealing and other properties.
Coatings comprising copolymers of ethylene and acrylic acid (EAA) have advantages over various previously used coatings, such as good low temperature sealing properties, water immersible seals, and resistance to crazing when flexed. However, when these coatings are applied to the sealable side of a base polymer film such as oriented polypropylene (OPP), it has been found in some instances that it would be desirable to have improved hot tack and blocking properties, particularly when the coated film is utilized on a relatively high speed packaging machine. Thus, any means to accomplish the foregoing improvements would be beneficial.
In accordance with the present invention, there is provided a base polymer film coated with a composition comprising a copolymer comprising 65 to 95 wt.% ethylene and 5 to 35 wt.% of acrylic or methacrylic acid (an °'ethylene copolymer") based on the weight of the polymer, wherein 2 to 80% of the carboxylate groups are neutralised with metal ions from Groups Ia, IIa, or IIb of the Periodic Table.
Suitably, the copolymer is coated directly onto the base polymer film.
It has been found that the foregoing coated film wherein the base polymer film is, for example, oriented Y
polypropylene, provides for good hot tack and blocking properties accompanied by satisfactory low temperature ' sealing and resistance of the seal to immersion in water.
~~e ethylene copolymer utilized in the compositions of this invention may be a copolymer of 65 to 95 wt.%, preferably 7~ ~0 85 wt.% of ethylene, and 5 to 35 wt.%, _ 2 _ preferably 15 to 25 wt.% of acrylic acid (AA) or methacrylic acid (MA). The copolymer may have a number average molecular weight (Mn) of, for example, 2,000 to 50,000, preferably 4,000 to 10,000.
The ethylene copolymer is often supplied as a solution v or fine dispersion of an ammonium salt of the copolymer in an ammoniacal water solution. When the copolymer is dried, ammonia is given off and the ionized and water sensitive carboxylate groups are converted to largely unionized and l0 less water sensitive free carboxyl groups. In practicing this invention, however, there is added to the solution or dispersion of the ethylene copolymer an amount of ions of at least one metal from Group Ia, IIa or IIb of the Periodic Table, preferably, sodium, potassium, lithium, calcium or zinc ions, and most preferably sodium ions, e.g., in the form of their hydroxides. The quantity of such metallic ions may be sufficient to neutralize, for example, 2 to 80%, preferably 10 to 50% of the total carboxylate groups in the copolymer. The presence of such metallic ions has been found to result in an improvement in certain properties, e.g., coefficient of friction (COF), hot tack, and blocking, without an unacceptable sacrifice of other properties, e.g., low minimum seal temperatures (MST).
When the ethylene copolymer is a copolymer of 80 wt.% of ethylene and 20 wt.% of acrylic acid and the neutralizing metal ions are sodium ions added as sodium hydroxide, then the amount of sodium hydroxide added corresponding to the foregoing percentages of carboxylate groups neutralized, is, for example, 0.33 to 8.8 phr, preferably 1.1 to 5.5 phr, where "phr" stands for parts by weight per hundred parts of the total resin, which is the same as ethylene copolymer when no other resin is present. For the purpose of determining the phr of various additives present in the coating, all the carboxylate groups of the ethylene copolymer are assumed to be in their free carboxyl (-COOH) form.
In addition to the partially neutralized ethylene copolymer, the coatings of this invention preferably contain WO 94/25270 ' ~ ~ PCTIUS94I04654 a relatively large particle size microcrystalline wax as an anti-blocking agent. The microcrystalline wax may be present in the coating in an amount of, for example, 2 to 12 phr, preferably 3 to 5 phr, wherein the wax particles have an average size in the range of, for example, 0.1 to 0.6 V
microns, preferably 0.12 to 0.30 microns.
In addition to functioning as an anti-blocking material, the microcrystalline wax when incorporated into the coatings of the present invention also functions to improve the "cold-slip" properties of the films coated therewith, i.e., the ability of a film to satisfactorily slide across surfaces at about room temperatures.
The coatings of this invention also preferably contain fumed silica for the purpose of further reducing the tack of the coating at room temperature. The fumed silica is composed of particles which are agglomerations of smaller particles and which have an average particle size of, for example, 2 to 9 microns, preferably 3 to 5 microns, and is present in the coating in an amount, for example, of 0.1 to 2.0 phr, preferably 0.2 to 0.4 phr.
Other optional additives which can be used, include particulate materials such as talc which may be present in an amount, for example, of 0 to 2 phr, cross-linking agents such as melamine formaldehyde resins which may be present in an amount, for example, of 0 to 20 phr, and anti-static agents such as poly(oxyethylene) sorbitan monooleate which may be present in an amount, for example, of 0 to 6 phr.
A particular type of thermoplastic film which can be advantageously coated with the coating compositions of this invention is molecularly oriented, isotactic polypropylene.
After extrusion of the base polypropylene film utilizing conventional extrusion techniques, the film is heated and molecularly oriented by stretching it both a longitudinal and i~
transverse direction. The resultant oriented film exhibits greatly improved tensile and stiffness properties. However, it is difficult to heat seal by conventional techniques because at the requisite sealing temperature, i.e., on the .,. _ 4 _ order of about 350°F, film disorientation and shrinkage occur which can result in the film rupturing and tearing apart. An advantage of this invention when such oriented films are subjected to surface treatment as described hereinafter and subsequently coated with the present coating compositions is that they can be sealed by temperatures sufficiently low to ' prevent shrinkage of the substrate, i.e., the oriented polypropylene film.
The foregoing description of base films containing a major proportion of polypropylene is intended to include not only films wherein the polymer is composed entirely of isotactic polypropylene homopolymer, but also coextruded multilayer films wherein the polymer of at least one layer is isotactic polypropylene homopolymer, and the polymer of one or both outer layers is a polymer, preferably an olefin polymer, having better sealability than isotactic polypropylene homopolymer. Such surface layer polymer may be, for example, a copolymer of propylene with a minor amount of one or more other 1-olefins, e.g., ethylene or ethylene and butylene or a high density polyethylene.
Other base polymer films which may be coated in accordance with this invention are those composed of polyolefins other than polypropylene, e.g., polyethylene and those composed of non-hydrocarbon polymers, e.g., polyesters such as polyethylene terephthalate (PET) and polyamides (nylons).
In general, the uncoated substrate films employed in the practice of the present invention are usually from 0.5 to 3.0 mils in thickness. Of particular interest are coextruded three layer films~wherein the polymer of the central core layer is isotactic polypropylene homopolymer having a thickness, for example, of 70 to 98~ of the total thickness ' of the film, the remainder being two thin outer layers of substantially identical thickness wherein the polymer is an ' isotactic copolymer of propylene, ethylene in an amount of, for example, 1 to 5 wt.~ of the copolymer, and optionally, butylene in an amount, for example, of 0.5 to 2 wt.~ of the 94/25270 ~ -~ PCT/US94104654 _ 5 _ copolymer. Also of substantial interest is a coextruded five layer film wherein the polymer of the central core layer is an opaque isotactic polypropylene homopolymer with voids produced by stretch orienting such layer containing spherical particles of a material higher melting than and immiscible with isotactic polypropylene homopolymer, e.g., polybutylene terephthalate, as shown, for example, in U.S. Patents Nos.
4,632,869 and 4,720,416, such core layer having a thickness, for example, of 70 to 90% the total thickness of the film;
the polymer of the layers contiguous to the central core layer is isotactic polypropylene homopolymer without voids, the thickness of such layers being substantially the same and being, for example, 2 to 10% of the total thickness of the film; and the polymer of the outer layers is a copolymer of propylene, ethylene and optionally, butylene, as described previously in connection with three layer films, each outer layer having substantially the same thickness, which is, for example, 1 to 5% of the total thickness of the film.
The coatings of this invention are particularly useful when applied to thicker films, e.g., of 1 to 2 mils, within the foregoing range, intended to be fed to a relatively high speed horizontal form fill and seal (HFFS) packaging machine operating at a speed of, for example, about 125 to 200 feet per minute (fpm). For this purpose, the percentage of carboxylate groups in the ethylene copolymer which should be neutralized, e.g., with sodium, should be in the range, for example, of 2.7 to 27%, preferably about 13.5% to prevent the film from failing in packaging operation due to low hot tack, high blocking, and high COF. When the ethylene copolymer is composed of 80 wt.% of ethylene and 20 wt.% of acrylic acid, the amount of sodium hydroxide to be added to the ethylene copolymer corresponding to the foregoing range is 0.3 to 3.0 phr, preferably 1.5 phr.
When the coated film is fed to a vertical form fill and seal (VFFS) packaging machine which operates at a somewhat lower speed than a HFFS machine, e.g., 25 to 75 fpm, the percentage of carboxylate groups in the ethylene copolymer which should be neutralized may be somewhat higher than when the film is fed to a HFFS machine, e.g., 18 to 45%, preferably about 31.5%, corresponding to an amount of sodium hydroxide added to the ethylene copolymer of 2 to 5 phr, preferably about 3.5 phr when the copolymer is composed of 80 wt.% of ethylene and 20 wt.% of acrylic acid.
To further improve the performance of the film in packaging operation, the second face of the film, i.e., other than the face coated with the composition of this invention, may be coated with a composition comprising a terpolymer of 2 to 15 wt.% of acrylic or methacrylic acid, 10 to 80 wt.% of methyl or ethyl acrylate, and l0 to 80 wt.% of methyl methyacrylate, together with colloidal silica and carnauba wax, as described in U.S. Patent No. 3,753,769. Such coating has the effect of reducing the coefficient of friction and slip and also improving the ink adhesion of that surface of the film.
Before applying the coating composition to the appropriate substrate, the surface of the substrate film can be treated to insure that the coating will be strongly adherent to the film thereby eliminating the possibility of the coating peeling or being stripped from the film. This treatment can be accomplished by employing known prior art techniques such as, for example, film chlorination, i.e., exposure of the film to gaseous chlorine, treatment with oxidizing agents such as chromic acid, hot air or steam treatment, flame treatment and the like. Although any of these techniques can be effectively employed to pretreat the film surface, a particularly desirable method of treatment is the so-called electronic treatment method which comprises exposing the film surface to a high voltage corona discharge while passing the film between a pair of spaced electrodes.
After electronic treatment of the substrate film surface, it can be coated with the coating composition of the present invention which coating will then exhibit a tendency to more strongly adhere to the treated film surface.
In applications where even greater coating-to-film WO 94!25270 ~.~ ~ PCTIUS94104654 adherence is desired, i.e., greater than that resulting from treatment of the film surface by any of the previously described methods, an intermediate primer coating can be employed. In this case, the film is first treated by one of the foregoing methods, electronic treatment being a preferred d method, to provide increased active adhesive sites thereon (thereby promoting primer adhesion) and to the thus-treated film surface there is subsequently applied a continuous coating of a primer material. Primer materials which are suitable are well known in the art and include, for example, titanates and polyethylene imine). The primer is applied to the electronically treated base film by conventional solution coating means. A particularly effective primer herein is polyethylene imine) applied as either an aqueous or organic solvent solution, e.g., of ethanol, containing about 0.5 wt.%
of the imine.
The coating composition is applied to the treated surface of the polymer film in any suitable manner such as by gravure coating, roll coating, dipping, spraying, etc. The excess aqueous solution can be removed by squeeze rolls, doctor knives, etc. The coating composition will ordinarily be applied in such an amount that there will be deposited following drying, a smooth, evenly distributed layer of from 0.02 to 0.10 mil thickness. In general, the thickness of the applied coating is such that it is sufficient to impart the desired sealability, coefficient of friction (COF), and hot slip characteristics to the substrate polymer film.
The coating once applied to the film is subsequently dried by hot air, radiant heat or by any other suitable means thereby providing a non-water soluble, clear, adherent, glossy coated film product useful, for example, as a packaging film.
The following examples further illustrate the invention.
Examples 1-33 Thirty-three coating compositions were 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 _ g _ 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. In addition, 0.4 phr of talc and 0.1 phr of fumed silica having an average particle size of 3 to 5 microns sold as Syloid*72 were also added to each composition. All the components were added as an aqueous disperson or solution except the anti-static agent which was added as a pure liquid. Water was then added to bring the final coating composition to a solids content (% SOL) of between 11 and 15 wt.%.
Each of the foregoing coating compositions was applied to one surface of coextruded, three laye~,~biaxially oriented polypropylene film samples having a total thickness of about 0.9 mil. The polymer of the core layer of each film was a polypropylene homopolymer having a high isotactic content and a melt index of about 3.0, and such core layer was about 0.856 mil in thickness. The polymer of the outer layers was an isotactic copolymer of propylene and about 3.55 wt.% of ethylene, based on the weight of the copolymer, having a melt index of about 6.8. The thickness of each of the outer layers was about 0.022 mil.
The other surface of each of the thirty-three film samples was coated with a composition comprising a terpolymer of methyl methacrylate methyl acrylate and methacrylic acid, colloidal silica, and carnauba wax, with a total solids content of about 13 wt.% as described in U.S. Patent No.
3,753,769.
The coatings were applied utilizing standard gravure coating apparatus and techniques. Before coating, the film had been treated by subjecting both surfaces thereof to electronic treatment and priming the electronically treated surfaces with a 0.5 wt.% solution of polyethylene imine) in a mixture of 85 percent water and 15 percent ethanol. The * Trade-mark WO 94/25270 ~ ~ PCTlUS94/04654 _ g _ total on the treated, primed coating oriented, film weight surface following he filmwas from about to drying of 0.5 t 0.9 gram/1,000 of film, on the in.2 surfaces coated with the composition invention , and gram/1000in.2 of this about 0.76 of film on the surfaces coate d with U.S.
the composition of Patent 9.
No.
2,753, The amounts additives in phr which were in the of varied coating compositionsas well as the ach solids content of e composition drying coating n and temperature i the of the l0 degrees F (TEMP.), re shown in Table a I.
Table I
Example NaOH A-S MWX M-F ~ SOL TEMP.
2 1.5 3 7 3 12 240 3 1.5 1 5 3 12 220 4 1.5 3 5 9 14 240 5 4.5 3 5 3 14 220 6 1.5 1 7 9 14 220 7 4.5 1 5 9 12 240 8 4.5 1 7 9 12 220 9 4.5 3 7 9 12 220 10 3.0 2 6 6 13 230 11 0.0 2 6 6 13 230 12 6.0 2 6 6 13 230 13 3.0 2 6 6 11 230 14 3.0 2 6 6 15 230 15 3.0 2 6 6 13 210 16 3.0 2 6 6 13 250 17 3.0 0 6 6 13 230 18 3.0 4 6 6 13 230 19 3.0 2 4 6 13 230 20 3.0 2 . 8 6 13 230 21 3.0 2 6 0 13 230 22 3.0 2 6 12 13 230 23 3.0 2 6 6 13 230 24 3.0 2 , 6 6 13 230 25 4.5 1 5 9 14 220 26 4.5 3 7 9 14 240 27 4.5 1 7 3 12 220 28 1.5 1 7 9 12 240 29 1.5 1 5 3 14 240 30 1.5 3 5 9 12 220 31 1.5 3 7 3 14 220 ~
The coatings were applied utilizing standard gravure coating apparatus and techniques. Before coating, the film had been treated by subjecting both surfaces thereof to electronic treatment and priming the electronically treated surfaces with a 0.5 wt.% solution of polyethylene imine) in a mixture of 85 percent water and 15 percent ethanol. The * Trade-mark WO 94/25270 ~ ~ PCTlUS94/04654 _ g _ total on the treated, primed coating oriented, film weight surface following he filmwas from about to drying of 0.5 t 0.9 gram/1,000 of film, on the in.2 surfaces coated with the composition invention , and gram/1000in.2 of this about 0.76 of film on the surfaces coate d with U.S.
the composition of Patent 9.
No.
2,753, The amounts additives in phr which were in the of varied coating compositionsas well as the ach solids content of e composition drying coating n and temperature i the of the l0 degrees F (TEMP.), re shown in Table a I.
Table I
Example NaOH A-S MWX M-F ~ SOL TEMP.
2 1.5 3 7 3 12 240 3 1.5 1 5 3 12 220 4 1.5 3 5 9 14 240 5 4.5 3 5 3 14 220 6 1.5 1 7 9 14 220 7 4.5 1 5 9 12 240 8 4.5 1 7 9 12 220 9 4.5 3 7 9 12 220 10 3.0 2 6 6 13 230 11 0.0 2 6 6 13 230 12 6.0 2 6 6 13 230 13 3.0 2 6 6 11 230 14 3.0 2 6 6 15 230 15 3.0 2 6 6 13 210 16 3.0 2 6 6 13 250 17 3.0 0 6 6 13 230 18 3.0 4 6 6 13 230 19 3.0 2 4 6 13 230 20 3.0 2 . 8 6 13 230 21 3.0 2 6 0 13 230 22 3.0 2 6 12 13 230 23 3.0 2 6 6 13 230 24 3.0 2 , 6 6 13 230 25 4.5 1 5 9 14 220 26 4.5 3 7 9 14 240 27 4.5 1 7 3 12 220 28 1.5 1 7 9 12 240 29 1.5 1 5 3 14 240 30 1.5 3 5 9 12 220 31 1.5 3 7 3 14 220 ~
32 4.5 3 5 3 12 240 33 3.0 2 6 6 13 230 The coated films of these examples were tested for various properties, the following of which with the indicated headings are shown in Table II. The non-crimp seal strengths in Tables II and III were measured with a Suter tester or tensile tester on seals made with an Askco*nine station heat sealer at 5 psi and 2 sec. dwell time at temperatures varied from 200°F to 280° F.
MST - The temperature in °F to reach 100 gm/in seal strength.
DELTA - The temperature increase to raise the seal strength from 100 to 300 gm/in, °F.
SS - The average of seal strength measured at 260, 270 and 280° F, gm/in.
COF - The coefficient of friction determined with an Imass~'slip/peel tester which has a 2~ in. x 2~ in., 200 gram sled with ASTM approved rubber on the bottom, traveling at 6 in/min. (ASTM D1894).
BL - The blocking in gm/in. after one hour at 140°F and 750 psi of the coated side of the invention to the coated side of the invention of each film, measured by peeling samples apart on a tensile tester.
HAZE - The percent haze on the seal coating determined by the Gardner hazemeter, which measures the percentage of light transmitted through a film which deviates from the incident beam as a result of forward scattering (ASTM D1003).
40 * Trade-mark ~~o~~~
s Table II
Example MST ~ DELTA SS COF BL HAZE
1 214 10 585 0.38 5.8 1.6 2 204 14 678 0.44 8.4 1.7 3 201 13 598 0.38 7.9 1.4 4 202 8 652 0.40 9.7 1.4 5 214 11 615 0.41 6.2 1.7 6 203 8 508 0.38 8.4 1.6 7 223 12 552 0.37 5.4 1.5 8 224 11 580 0.38 5.5 1.9 9 224 18 538 0.34 7.4 1.7 10 213 9 575 0.54 6.9 1.4 11 192 7 540 0.58 40.8 1.9 12 235 17 382 0.36 7.4 1.6 13 214 11 488 0.40 6.1 1.2 14 213 10 573 0.37 7.2 1.4 15 204 12 477 0.36 6.4 1.3 16 213 10 593 0.43 5.9 1.4 17 213 6 538 0.39 6.0 1.4 18 213 11 595 0.42 6.6 1.4 19 212 7 488 0.35 7.2 1.2_ 20 216 9 628 0.35 5.5 1.6 21 202 7 488 0.38 7.1 1.4 22 214 10 595 0.36 5.9 1.4 23 213 7 480 0.36 6.0 1.3 24 216 11 592 0.36 6.0 1.5 25 224 10 490 0.38 6.3 1.6 26 236 11 457 0.35 5.1 1.6 27 220 8 457 0.31 7.3 1.7 28 206 17 475 0.38 7.6 1.5 29 195 11 602 0.38 10.6 1.6 30 203 10 392 0.43 10.3 1.4 31 193 11 462 0.45 10.7 1.5 4 32 222 8 530 0.42 5.4 1.4 33 214 11 457 0.32 6.1 1.5 ~' S 0 The following additional properties with the indicated headings, are shown in Table III, wherein crimp seal strengths were measured on crimp seals made with a Wrap Ade crimp sealer at 20 psi and 3/4 sec., having a jaw WO 94/25270 ~PCT/US94/04654 configuration similar to that of a Campbell wrapper (horizontal form and fill).
HT - The hot tack of the coating as an average of values obtained at 200, 220, 240 and 260°F, gm/in., measured using ' calibrated springs which subject heat sealed samples to known forces immediately after crimp seals are made. ' CR-MST - The crimp seal temperature to obtain 100 gm/in seal strength, °F.
CRDL - The temperature increase to raise the crimp seal strength from 100 to 300 gm/in, °F.
CRIMP - The crimp seal strength average of 240, 260 and 280°F, gm/in.
SS-H20 - The average seal strength at 260, 270 and 280°F
after 24 hour water immersion at room temperature, gm/in.
D-MST - The temperature needed to obtain a 200 gm/in seal on the trailing edge of the crimp seal on the Doboy HFFS
machine running at 150 fpm.
WO 94!25270 ~ ~ PCTlUS94/04654 10 Table III
Example HT CR-MST CRDL CRIMP SS-H20 D-MST
The product and process conditions shown in Table I and the values of properties shown in Tables II and III indicate WO 94/25270 ~~ PCT/US94/04654 that the coated films of this invention have good hot tack and blocking properties accompanied by satisfactory low temperature sealing and good resistance of the seal to immersion in water. Furthermore, the improved hot tack and ' blocking obtained provide for the feeding of thicker coated films to high speed HFFT machines and somewhat lower speed VFFT machines without any tearing of the film.
v
MST - The temperature in °F to reach 100 gm/in seal strength.
DELTA - The temperature increase to raise the seal strength from 100 to 300 gm/in, °F.
SS - The average of seal strength measured at 260, 270 and 280° F, gm/in.
COF - The coefficient of friction determined with an Imass~'slip/peel tester which has a 2~ in. x 2~ in., 200 gram sled with ASTM approved rubber on the bottom, traveling at 6 in/min. (ASTM D1894).
BL - The blocking in gm/in. after one hour at 140°F and 750 psi of the coated side of the invention to the coated side of the invention of each film, measured by peeling samples apart on a tensile tester.
HAZE - The percent haze on the seal coating determined by the Gardner hazemeter, which measures the percentage of light transmitted through a film which deviates from the incident beam as a result of forward scattering (ASTM D1003).
40 * Trade-mark ~~o~~~
s Table II
Example MST ~ DELTA SS COF BL HAZE
1 214 10 585 0.38 5.8 1.6 2 204 14 678 0.44 8.4 1.7 3 201 13 598 0.38 7.9 1.4 4 202 8 652 0.40 9.7 1.4 5 214 11 615 0.41 6.2 1.7 6 203 8 508 0.38 8.4 1.6 7 223 12 552 0.37 5.4 1.5 8 224 11 580 0.38 5.5 1.9 9 224 18 538 0.34 7.4 1.7 10 213 9 575 0.54 6.9 1.4 11 192 7 540 0.58 40.8 1.9 12 235 17 382 0.36 7.4 1.6 13 214 11 488 0.40 6.1 1.2 14 213 10 573 0.37 7.2 1.4 15 204 12 477 0.36 6.4 1.3 16 213 10 593 0.43 5.9 1.4 17 213 6 538 0.39 6.0 1.4 18 213 11 595 0.42 6.6 1.4 19 212 7 488 0.35 7.2 1.2_ 20 216 9 628 0.35 5.5 1.6 21 202 7 488 0.38 7.1 1.4 22 214 10 595 0.36 5.9 1.4 23 213 7 480 0.36 6.0 1.3 24 216 11 592 0.36 6.0 1.5 25 224 10 490 0.38 6.3 1.6 26 236 11 457 0.35 5.1 1.6 27 220 8 457 0.31 7.3 1.7 28 206 17 475 0.38 7.6 1.5 29 195 11 602 0.38 10.6 1.6 30 203 10 392 0.43 10.3 1.4 31 193 11 462 0.45 10.7 1.5 4 32 222 8 530 0.42 5.4 1.4 33 214 11 457 0.32 6.1 1.5 ~' S 0 The following additional properties with the indicated headings, are shown in Table III, wherein crimp seal strengths were measured on crimp seals made with a Wrap Ade crimp sealer at 20 psi and 3/4 sec., having a jaw WO 94/25270 ~PCT/US94/04654 configuration similar to that of a Campbell wrapper (horizontal form and fill).
HT - The hot tack of the coating as an average of values obtained at 200, 220, 240 and 260°F, gm/in., measured using ' calibrated springs which subject heat sealed samples to known forces immediately after crimp seals are made. ' CR-MST - The crimp seal temperature to obtain 100 gm/in seal strength, °F.
CRDL - The temperature increase to raise the crimp seal strength from 100 to 300 gm/in, °F.
CRIMP - The crimp seal strength average of 240, 260 and 280°F, gm/in.
SS-H20 - The average seal strength at 260, 270 and 280°F
after 24 hour water immersion at room temperature, gm/in.
D-MST - The temperature needed to obtain a 200 gm/in seal on the trailing edge of the crimp seal on the Doboy HFFS
machine running at 150 fpm.
WO 94!25270 ~ ~ PCTlUS94/04654 10 Table III
Example HT CR-MST CRDL CRIMP SS-H20 D-MST
The product and process conditions shown in Table I and the values of properties shown in Tables II and III indicate WO 94/25270 ~~ PCT/US94/04654 that the coated films of this invention have good hot tack and blocking properties accompanied by satisfactory low temperature sealing and good resistance of the seal to immersion in water. Furthermore, the improved hot tack and ' blocking obtained provide for the feeding of thicker coated films to high speed HFFT machines and somewhat lower speed VFFT machines without any tearing of the film.
v
Claims (14)
1. A base polymer film coated with a composition comprising a copolymer comprising 65 to 95 wt.% ethylene and to 35 wt.% of acrylic or methacrylic acid (an "ethylene copolymer") based on the weight of the polymer, wherein 2 to 80% of the carboxylate groups are neutralized with metal ions from Groups Ia, IIa, or IIb of the Periodic Table.
2. A coated film according to claim 1 wherein the base polymer film comprises oriented isotactic polypropylene.
3. A coated film according to claim 1 or 2 wherein the base polymer film is a multilayer film in which at least one layer comprises isotactic polypropylene homopolymer and at least one outer layer comprises a polymer having better sealability than isotactic polypropylene homopolymer.
4. A coated film according to claim 3 wherein the base polymer film is a three layer film in which the central core layer comprises isotactic polypropylene homopolymer and the outer layers, which may be the same or different, comprise an isotactic copolymer of propylene and ethylene or isotactic terpolymer of propylene, ethylene and butylene.
5. A coated film according to claim 3 wherein the central core layer comprises an opaque isotatic polypropylene homopolymer containing voids.
6. A coated film according to claim 3 wherein the base polymer film is a five layer film in which the central core layer comprises an opaque isotactic polypropylene homopolymer containing voids; the layers contiguous to the central core layer, which may be the same or different, comprise isotactic polypropylene homopolymer without voids; and the outer layers, which may be the same or different comprise an isotactic copolymer of propylene and ethylene or isotactic terpolymer of propylene, ethylene and butylene.
7. A coated film according to any one of claims 1 to 6 wherein the ethylene copolymer comprises 75 to 85 wt.% of ethylene and 15 to 25 wt.% of acrylic or methacrylic acid.
8. A coated film according to any one of claims 1 to 7 wherein 10 to 50% of the carboxylate groups of the ethylene copolymer are neutralized.
9. A coated film according to claim 8 wherein the neutralisation is effected with sodium, potassium, calcium or zinc ions.
10. A coated film according to any one of claims 1 to 9 wherein the coating also comprises microcrystalline wax and fumed silica.
11. A coated film according to claim 10 wherein the microcrystalline wax is present in an amount from 2 to 12 phr and has an average particle size from 0.1 to 0.6 micron.
12. A coated film according to claim 10 or 11 wherein the fumed silica is present in an amount of from 0.1 to 2.0 phr and has an average particle size from 2 to 9 microns.
13. A composition comprising A) a copolymer comprising 65 to 95 wt.% ethylene and 5 to 35 wt.% of acrylic or methacrylic acid (an "ethylene copolymer") based on the weight of the polymer, wherein 2 to 80% of the carboxylate groups are neutralized with metal ions from Groups Ia, IIa or IIb of the Periodic Table; B) microcrystalline wax; and C) fumed silica.
14. Use of a composition according to claim 13 to coat base polymer film.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/054,991 US5419960A (en) | 1993-04-30 | 1993-04-30 | Coated films with good low temperature sealing properties an hot tack |
US08/054,991 | 1993-04-30 | ||
PCT/US1994/004654 WO1994025270A1 (en) | 1993-04-30 | 1994-04-28 | Coated films with good low temperature sealing properties and hot tack |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2160581A1 CA2160581A1 (en) | 1994-11-10 |
CA2160581C true CA2160581C (en) | 2005-06-07 |
Family
ID=21994867
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002160581A Expired - Lifetime CA2160581C (en) | 1993-04-30 | 1994-04-28 | Coated films with good low temperature sealing properties and hot tack |
Country Status (10)
Country | Link |
---|---|
US (1) | US5419960A (en) |
EP (1) | EP0696244B1 (en) |
JP (1) | JPH08509672A (en) |
KR (1) | KR960701743A (en) |
AT (1) | ATE196277T1 (en) |
AU (1) | AU682693B2 (en) |
CA (1) | CA2160581C (en) |
DE (1) | DE69425885T2 (en) |
ES (1) | ES2149876T3 (en) |
WO (1) | WO1994025270A1 (en) |
Families Citing this family (69)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE59408824D1 (en) * | 1993-01-25 | 1999-11-25 | Hoechst Trespaphan Gmbh | Biaxially oriented polypropylene multilayer film, process for its production and its use |
US5827627A (en) * | 1995-02-03 | 1998-10-27 | Mobil Oil Corporation | Receiving element for liquid toner-derived ink |
US5789123A (en) * | 1995-02-03 | 1998-08-04 | Mobil Oil Corporation | Liquid toner-derived ink printable label |
DE19514583A1 (en) * | 1995-04-20 | 1997-02-13 | Basf Ag | Polyurethane-coated packaging films |
US6013353A (en) * | 1996-05-07 | 2000-01-11 | Mobil Oil Corporation | Metallized multilayer packaging film |
US6114021A (en) * | 1996-07-16 | 2000-09-05 | E. I. Du Pont De Nemours And Company | Primed polymer films having improved adhesion characteristics and processes for making the films |
US6074731A (en) * | 1996-09-10 | 2000-06-13 | Applied Extrusion Technologies, Inc. | Biaxially oriented polypropylene films with improved cold seal receptive surfaces |
SE9701789D0 (en) * | 1997-05-14 | 1997-05-14 | Tetra Laval Holdings & Finance | Ink-coated packaging material for aseptic packaging and ways of making the packaging material |
IL121951A0 (en) * | 1997-10-12 | 1998-03-10 | Indigo Nv | Coating system for substrates |
US5958566A (en) * | 1997-10-17 | 1999-09-28 | Fina Technology, Inc. | Metal bond strength in polyolefin films |
WO1999028791A1 (en) * | 1997-12-02 | 1999-06-10 | Minnesota Mining And Manufacturing Company | Multilayer imaging medium comprising polypropylene, method of imaging said medium, and image-bearing medium |
GB9803848D0 (en) | 1998-02-25 | 1998-04-22 | Ici Ltd | Multi-layer polymer films |
US6106982A (en) * | 1998-05-11 | 2000-08-22 | Avery Dennison Corporation | Imaged receptor laminate and process for making same |
AU2020900A (en) * | 1998-12-30 | 2000-07-24 | Mobil Oil Corporation | Coated films with improved barrier properties |
AU4457200A (en) * | 1999-04-16 | 2000-11-02 | E.I. Du Pont De Nemours And Company | Coating composition containing a low mfi ethylene acrylic acid copolymer |
US6458470B1 (en) * | 1999-07-08 | 2002-10-01 | Exxonmobil Oil Corporation | High barrier multilayer film |
US6852792B1 (en) | 2000-04-13 | 2005-02-08 | E. I. Du Pont De Nemours And Company | Coating composition containing a low MFI ethylene acrylic acid copolymer |
US20020155267A1 (en) * | 2001-02-22 | 2002-10-24 | Bader Michael John | Multi-layer hermetically sealable film |
GB0111508D0 (en) * | 2001-05-11 | 2001-07-04 | Ucb Sa | Packaging film |
US6919113B2 (en) | 2001-07-18 | 2005-07-19 | Avery Dennison Corporation | Multilayered film |
US20030157354A1 (en) * | 2002-02-15 | 2003-08-21 | Van Veghel Michael W. | Transparent, coated, shrinkable, oriented polypropylene film |
US7094460B2 (en) * | 2002-05-24 | 2006-08-22 | Eastman Kodak Company | Imaging element with improved surface and stiffness |
US6716501B2 (en) * | 2002-07-18 | 2004-04-06 | Avery Dennison Corporation | Multilayered film |
US20040126507A1 (en) * | 2002-12-26 | 2004-07-01 | O'brien Jeffrey James | UV inkjet printed substrates |
US8455064B2 (en) | 2002-12-26 | 2013-06-04 | Exxonmobil Oil Corporation | UV inkjet printed substrates |
US20040180162A1 (en) * | 2003-03-14 | 2004-09-16 | Gringoire Bruno R.L. | Reduced blocking metallized film |
US6797397B1 (en) * | 2003-03-20 | 2004-09-28 | Exxonmobil Oil Corporation | Lamination structure with a starch to plastic bond |
US7279061B2 (en) * | 2003-04-09 | 2007-10-09 | Exxonmobil Oil Corporation | Process for the production of improved metallized films |
CA2518507A1 (en) * | 2003-04-10 | 2004-10-28 | Exxonmobil Oil Corporation | Process for the production of improved metallized films |
KR20060010734A (en) * | 2003-05-01 | 2006-02-02 | 애버리 데니슨 코포레이션 | Multilayered film |
US7803865B2 (en) | 2003-08-25 | 2010-09-28 | Dow Global Technologies Inc. | Aqueous dispersion, its production method, and its use |
US8946329B2 (en) | 2003-08-25 | 2015-02-03 | Dow Global Technologies Llc | Coating compositions |
US8722787B2 (en) | 2003-08-25 | 2014-05-13 | Dow Global Technologies Llc | Coating composition and articles made therefrom |
US8779053B2 (en) | 2003-08-25 | 2014-07-15 | Dow Global Technologies Llc | Coating compositions |
US9169406B2 (en) | 2003-08-25 | 2015-10-27 | Dow Global Technologies Llc | Coating compositions |
US8349929B2 (en) | 2003-08-25 | 2013-01-08 | Dow Global Technologies Llc | Coating composition and articles made therefrom |
US7763676B2 (en) | 2003-08-25 | 2010-07-27 | Dow Global Technologies Inc. | Aqueous polymer dispersions and products from those dispersions |
US8357749B2 (en) | 2003-08-25 | 2013-01-22 | Dow Global Technologies Llc | Coating composition and articles made therefrom |
US8158711B2 (en) | 2003-08-25 | 2012-04-17 | Dow Global Technologies Llc | Aqueous dispersion, its production method, and its use |
US7258930B2 (en) * | 2004-04-28 | 2007-08-21 | Cryovac, Inc. | Oxygen scavenging film with cyclic olefin copolymer |
US20060029824A1 (en) * | 2004-08-04 | 2006-02-09 | Gringoire Bruno R | Heat-sealable polymeric films |
FR2879960B1 (en) * | 2004-12-24 | 2018-01-26 | Mgi France | PRESS METHOD FOR LAMINATING SUBSTRATES OBTAINED BY DIGITAL PRINTING WITH INK IN POWDER OR LIQUID |
US20070036909A1 (en) * | 2005-08-09 | 2007-02-15 | Shifang Luo | Processes for producing oriented polymeric films provided with UV-active coatings |
US7648756B2 (en) | 2005-10-13 | 2010-01-19 | Michelman, Inc. | Coating for enhancing low temperature heat sealability and high hot tack to polymeric substrates |
US20070141366A1 (en) * | 2005-12-21 | 2007-06-21 | Janet Rivett | Multilayer film with hot tack property |
US20070243331A1 (en) * | 2006-02-17 | 2007-10-18 | Dow Global Technologies Inc. | Heat sealable compositions from aqueous dispersions |
US20070221531A1 (en) * | 2006-03-27 | 2007-09-27 | Patrick Raymond Coughlin | Packetized Colorization of Coatings |
US20070248810A1 (en) * | 2006-04-25 | 2007-10-25 | Mcgee Dennis E | Coated polymeric film |
US8129032B2 (en) | 2008-02-01 | 2012-03-06 | Exxonmobil Oil Corporation | Coating compositions, coated substrates and hermetic seals made therefrom having improved low temperature sealing and hot tack properties |
US9067391B2 (en) * | 2008-02-01 | 2015-06-30 | Pang-Chia Lu | Coated biaxially oriented film via in-line coating process |
EP2172510A1 (en) * | 2008-10-01 | 2010-04-07 | Dow Global Technologies Inc. | Barrier films and method for making and using the same |
US8241746B2 (en) * | 2009-01-28 | 2012-08-14 | Brady Worldwide, Inc. | Tissue cassette label |
US20110200817A1 (en) * | 2010-02-12 | 2011-08-18 | Michelman, Inc. | Primer coating for use on substrates |
US20130209758A1 (en) | 2010-04-12 | 2013-08-15 | Anne P. CAMPEAU | Coating for Polymeric Labels |
WO2012134695A1 (en) | 2011-03-29 | 2012-10-04 | Exxonmobil Oil Corporation | Film coatings based on polyalkylimine condensation polymers |
US20130084437A1 (en) | 2011-09-29 | 2013-04-04 | Dennis E. McGee | Film Coatings Based on Polyalkylimine Condensation Polymers |
US20130149930A1 (en) | 2011-12-12 | 2013-06-13 | E I Du Pont De Nemours And Company | Methods to form an ionomer coating on a substrate |
US20130225021A1 (en) | 2012-02-29 | 2013-08-29 | E.I. Du Pont De Nemours And Company | Highly viscous ionomer-poly(vinylalcohol) coatings |
CN104136556A (en) | 2012-02-29 | 2014-11-05 | 纳幕尔杜邦公司 | Ionomer-poly(vinylalcohol) blends and coatings |
US9085123B2 (en) | 2012-02-29 | 2015-07-21 | E I Du Pont De Nemours And Company | Ionomer-poly(vinylalcohol) coatings |
WO2013165486A1 (en) | 2012-05-01 | 2013-11-07 | Exxonmobile Oil Corporation | Epoxylated polyalkyleneimine film coatings |
EP2914430B1 (en) | 2012-11-01 | 2017-06-28 | Jindal Films Europe Virton SPRL | Coated metallized oriented polypropylene films |
BR112015015417B1 (en) | 2012-12-28 | 2021-08-17 | Dow Global Technologies Llc | COATING COMPOSITION |
CN104968736B (en) | 2012-12-28 | 2017-09-05 | 陶氏环球技术有限责任公司 | Coating composition |
US20150203704A1 (en) | 2014-01-22 | 2015-07-23 | E I Du Pont De Nemours And Company | Alkali metal-magnesium ionomer compositions |
US20150203615A1 (en) | 2014-01-22 | 2015-07-23 | E I Du Pont De Nemours And Company | Alkali metal-zinc ionomer compositions |
US20150344729A1 (en) | 2014-05-30 | 2015-12-03 | Michelman, Inc. | Heat seal coating for use on substrates |
JP6734848B2 (en) * | 2015-07-16 | 2020-08-05 | デンカ株式会社 | Polyethylene film for packaging and polyethylene film for overwrap packaging |
BR112021011621B1 (en) | 2018-12-20 | 2024-02-27 | Dow Global Technologies Llc | AQUEOUS IONOMER DISPERSION, METHOD FOR MAKING AN AQUEOUS IONOMER DISPERSION, METHOD FOR FORMING A COATED ARTICLE, AND COATED ARTICLE |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3753769A (en) * | 1966-06-29 | 1973-08-21 | Mobil Oil Corp | Coating composition and plastic articles coated therewith |
GB1243303A (en) * | 1968-05-17 | 1971-08-18 | Du Pont | Copolymer dispersions |
JPS52155687A (en) * | 1976-06-22 | 1977-12-24 | Toray Ind Inc | Modified polypropylene composite film |
JPS5659880A (en) * | 1979-10-23 | 1981-05-23 | Nippon Oil Co Ltd | Coating film-protective composition |
DE3543118A1 (en) * | 1985-12-06 | 1987-06-11 | Wolff Walsrode Ag | SEALABLE MULTILAYER FILMS |
DE3842948A1 (en) * | 1988-12-21 | 1990-06-28 | Wolff Walsrode Ag | HOT-COATABLE, GAS-DENSITY MULTILAYER FILMS |
JPH032666A (en) * | 1989-05-31 | 1991-01-09 | Fujikura Ltd | Piezoelectric acceleration sensor |
US5169728A (en) * | 1989-06-26 | 1992-12-08 | The Dow Chemical Company | Multilayered film |
JP3119858B2 (en) * | 1990-01-10 | 2000-12-25 | 住友ゴム工業株式会社 | Golf ball |
US5066543A (en) * | 1990-02-28 | 1991-11-19 | Shell Oil Company | Film, sheet and laminate capable of forming easy-open packagings |
US5232776A (en) * | 1991-08-29 | 1993-08-03 | Mobil Oil Corporation | Polymeric films with improved low coefficient of friction material coated thereon |
US5178942A (en) * | 1991-09-09 | 1993-01-12 | Mobil Oil Corporation | Multi-layer opaque film structures tailored to end-use requirements |
JPH05257233A (en) * | 1992-03-12 | 1993-10-08 | New Oji Paper Co Ltd | Supporting body for photographic sensitive paper |
-
1993
- 1993-04-30 US US08/054,991 patent/US5419960A/en not_active Expired - Lifetime
-
1994
- 1994-04-28 EP EP94915920A patent/EP0696244B1/en not_active Expired - Lifetime
- 1994-04-28 KR KR1019950704758A patent/KR960701743A/en not_active IP Right Cessation
- 1994-04-28 AU AU67762/94A patent/AU682693B2/en not_active Ceased
- 1994-04-28 DE DE69425885T patent/DE69425885T2/en not_active Expired - Lifetime
- 1994-04-28 JP JP6524528A patent/JPH08509672A/en active Pending
- 1994-04-28 AT AT94915920T patent/ATE196277T1/en active
- 1994-04-28 WO PCT/US1994/004654 patent/WO1994025270A1/en active IP Right Grant
- 1994-04-28 CA CA002160581A patent/CA2160581C/en not_active Expired - Lifetime
- 1994-04-28 ES ES94915920T patent/ES2149876T3/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
AU682693B2 (en) | 1997-10-16 |
CA2160581A1 (en) | 1994-11-10 |
WO1994025270A1 (en) | 1994-11-10 |
ATE196277T1 (en) | 2000-09-15 |
DE69425885D1 (en) | 2000-10-19 |
EP0696244B1 (en) | 2000-09-13 |
EP0696244A1 (en) | 1996-02-14 |
JPH08509672A (en) | 1996-10-15 |
ES2149876T3 (en) | 2000-11-16 |
DE69425885T2 (en) | 2001-01-11 |
US5419960A (en) | 1995-05-30 |
EP0696244A4 (en) | 1996-05-29 |
KR960701743A (en) | 1996-03-28 |
AU6776294A (en) | 1994-11-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2160581C (en) | Coated films with good low temperature sealing properties and hot tack | |
US6013353A (en) | Metallized multilayer packaging film | |
AU711250B2 (en) | Metallized multilayer packaging film | |
US4720427A (en) | Oriented multi-layer heat sealable film | |
EP0426382B1 (en) | Oriented multilayer heat sealable packaging film | |
JPH056514B2 (en) | ||
KR100578006B1 (en) | Multi-layer polymer films | |
CA2203915A1 (en) | Heat sealable multilayer film containing polyvinyl alcohol layer | |
US4565739A (en) | Oriented multi-layer heat sealable film | |
NZ277945A (en) | Biaxially oriented hdpe film having a coating comprising vinylidene chloride or acrylic acid polymer or polyvinylalcohol | |
JPH03262641A (en) | Heat-sealable packaging film having stretchable primer | |
CA1276765C (en) | Oriented multi-layer heat sealable film | |
US7291387B2 (en) | Packaging film | |
US20040180162A1 (en) | Reduced blocking metallized film | |
EP0497462A1 (en) | Multiple-layer polyolefin films | |
JPH01133731A (en) | Metallized laminated body |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request | ||
MKEX | Expiry |
Effective date: 20140428 |