EP0617662A1 - Plastic release film with textured or non-planar surface - Google Patents

Plastic release film with textured or non-planar surface

Info

Publication number
EP0617662A1
EP0617662A1 EP93901203A EP93901203A EP0617662A1 EP 0617662 A1 EP0617662 A1 EP 0617662A1 EP 93901203 A EP93901203 A EP 93901203A EP 93901203 A EP93901203 A EP 93901203A EP 0617662 A1 EP0617662 A1 EP 0617662A1
Authority
EP
European Patent Office
Prior art keywords
release
release film
ethylene
block copolymer
silicone
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.)
Withdrawn
Application number
EP93901203A
Other languages
German (de)
French (fr)
Other versions
EP0617662A4 (en
Inventor
Hachul Christopher Kim
Andrew Philip Lebel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Oil Corp
Original Assignee
Mobil Oil Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from US07/811,125 external-priority patent/US5232784A/en
Application filed by Mobil Oil Corp filed Critical Mobil Oil Corp
Publication of EP0617662A1 publication Critical patent/EP0617662A1/en
Publication of EP0617662A4 publication Critical patent/EP0617662A4/en
Withdrawn legal-status Critical Current

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
    • 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
    • B32B13/00—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material
    • B32B13/04—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material comprising such water setting substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B13/12—Layered products comprising a a layer of water-setting substance, e.g. concrete, plaster, asbestos cement, or like builders' material comprising such water setting substance 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
    • B32B27/06—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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • 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
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/40—Adhesives in the form of films or foils characterised by release liners
    • C09J7/401—Adhesives in the form of films or foils characterised by release liners characterised by the release coating composition
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/40—Adhesives in the form of films or foils characterised by release liners
    • C09J7/403—Adhesives in the form of films or foils characterised by release liners characterised by the structure of the release feature
    • 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
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/21—Anti-static
    • 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
    • B32B2519/00—Labels, badges
    • 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
    • C08J2453/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2423/00—Presence of polyolefin
    • C09J2423/006—Presence of polyolefin in the substrate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2433/00—Presence of (meth)acrylic polymer
    • C09J2433/005—Presence of (meth)acrylic polymer in the release coating
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2453/00—Presence of block copolymer
    • C09J2453/006—Presence of block copolymer in the substrate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2483/00—Presence of polysiloxane
    • C09J2483/005—Presence of polysiloxane in the release coating

Definitions

  • the present invention relates to a release film, a major utility of which is to protect and carry label stock u: 1 the label is put into use on an appropriate surface.
  • labels have been prepared with an adhesive applied to one side thereof.
  • the adhesive is a pressure sensitive adhesive
  • some means had to be provided to protect the adhesive surface in advance of applying the label to the ultimate surface to be labeled.
  • a technique has evolved over the years by which the pressure sensitive adhesive is protected by bringing the adhesive surface into contact with a release layer which has little tendency to aggressively adhere to the pressure sensitive adhesive surface.
  • a second film having a release surface is brought into contact with the pressure sensitive surface carried by the label protecting the pressure sensitive adhesive until the label is applied to its ultimate surface.
  • the pressure sensitive adhesive can be applied to the release surface and the label stock thereafter applied to the adhesive surface. On removal of the label the pressure sensitive adhesive will preferentially adhere to the label stock.
  • Release films can be manufactured separately from the label face stock.
  • the release film is manufactured by applying a commercially available release material to one side of the release film and the combination is then convolutely wound into a roll stock. Ultimately this roll stock must be unrolled and slit to a width dimension suited to a particular label dimension.
  • a pressure sensitive layer is applied over the release layer and this is mated with the underside of a sheet of label stock.
  • the label stock can have the pressure sensitive adhesive applied to it's undersurface which in turn is mated with the release label.
  • label indicia is printed onto the surface of label and, thereafter, the label is die cut so that it can be separated from the release sheet-label stock combination.
  • release film roll stock for re-dimensioning purposes, serious problems can arise.
  • the release material is applied as a coating layer on the substrate and subjected to electron beam curing and during the convoluted winding of the stock, a portion of or a fraction of the release material is transferred to the back side of the release film. Later when this release roll is unwound to receive label stock thereon, and subsequently rewound, some release material or a fraction thereof transfers to the surface of the label stock prior to the label stock receiving printed indicia.
  • This transferred release material causes imperfections to occur during the label printing process. The transferred release material interferes with printing. This leads to the need to discard the combination of material at a point when the product is almost completely ready for use or marketing.
  • This invention seeks to overcome the aforementioned difficulties.
  • the present invention provides a release film comprising an oriented thermoplastic polymeric substrate layer having a surface layer comprising an ethylene-propylene block copolymer on one side thereof and a release coating on the other side thereof. While it is not completely understood, it is believed that the ethylene-propylene block copolymer surface has a distinctive texture which causes, during unwind of a roll of said film, a reduced electrostatic potential, in comparison to a smooth surface and said surface texture permits even, unvarying transport over rollers during manufacture and use.
  • the invention provides a release film comprising an oriented thermoplastic polymeric layer having one side thereof a release coating comprising a silicone-acrylate release material, the coating including therein a quaternary ammonium salt.
  • the substrates contemplated herein can be any polymeric film substrate which can effectively carry a release coating on one side thereof and an ethylene-propylene block copolymer surface on the other side thereof.
  • Preferred substrates include, polyolefin films which are oriented and preferably biaxially oriented.
  • the substrate can be a homopolymer, copolymer or a blend thereof.
  • a preferred homopolymer is polypropylene.
  • Particularly preferred are isotatic polypropylenes containing at least 80% by weight of isotatic polypropylene.
  • This substrate layer can be homopolypropylene having a melting point range from 321° to 336°F. Commercially available materials of this description include Exxon 4612 and FINA 3371.
  • the substrate can be a single material or a combination of coextruded substrate materials.
  • polypropylenes of different melt indexes can be employed to yield excellent handling characteristics.
  • the substrate can be provided in any thickness which facilitates either human or machine handling. A preferred thickness range can be from 0.5 mils to 3 mils.
  • the substrate material can be composed of one or a plurality of layers and may be transparent or opaque.
  • the ethylene-propylene block copolymer can have an ethylene content of less than 20% by weight; for example, from 2 to 20 and preferably from 3 to 15%, and a melt flow index from 1 to 100 g/10 minutes, preferably from 3 to 50 g/10 minutes.
  • a preferred ethylene-propylene block copolymer is commercially available as Himont 8523, having a melt flow index of about 6.0 g/10 minutes.
  • the release film substrate can be formed for example by coextruding the polypropylene film of choice with the above identified ethylene-propylene block copolymer followed by biaxially orienting the combination 4.3 times in the machine direction and 8 times in the transverse direction.
  • the block copolymer coated substrate is now in condition to receive a commercial release coating on the side opposite to the ethylene-propylene block copolymer.
  • the selected release coating can be applied by any convenient technique, for example, by differential offset gravure coating. Thereafter, if the proprietary release coating needs to be cured it can be done so by any prior art technique.
  • a convenient class of release coatings is described in U.S. Patent No. 4,678,846 and 4,306,050. In essence, these release coatings are silicone polymers having acrylic functional end groups.
  • the material is applied to the opposite side of the block copolymer coated polypropylene film by differential offset gravure coating and the coating is cured by exposure to energized electrons at the rate of 2.5 Mrads in a RPC electron beam processor. It is to be understood than curing can be accomplished within the range from 1 to 5, preferably from 2 to 3 Mrads.
  • the release material of the present invention includes (meth)acrylate ester modified organopolysiloxane mixtures, comprising essentially equilibrated organopolysiloxanes with, on the average, more than 25 to fewer than 200 silicone atoms and which additionally contain 2 to 30 weight percent of organopolysiloxanes with, on the average, 2 to 25 silicone atoms and 2 to 30 weight percent of organopolysiloxanes with, on the average, 200 to 2,000 silicone atoms.
  • the organopolysiloxane fractions having more than 25 to less than 200 silicone atoms are sometimes referred to as the first fraction, those having 2 to 25 silicone atoms are referred to as the second fraction, and those having 200 to 2,000 silicone atoms are referred to as the third fraction.
  • organopolysiloxanes contained in the organpolysiloxane mixtures preferably correspond to the formula :
  • R is an alkyl radical with 1 to 4 carbon atoms, preferably, the methyl radical.
  • R may, however, also be a vinyl or phenyl radical.
  • the R radical may also represent different moieties in the molecule, so that some R radicals represent methyl radicals and the other R radicals may, for example, represent a vinyl or a phenyl radical.
  • at least 90% of the R radicals are alkyl radicals, especially methyl radicals.
  • Q is an organic radical which contains the acrylate or methacrylate ester groups.
  • the acrylate or methacrylate ester radical is linked to the silicone atom through an SiOC bridge.
  • the acrylate or methacrylate radical may moreover be derived from pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, ditrimethylolpropane triacrylate, ditrimethylolpropane trimethacrylate, ditrimethylolethane triacrylate, ditrimethylolethane trimethacrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, glycerin di(meth)acrylate, hydroxyethyl acrylate, hydroxpropyl acrylate and neopentyl glycol monoacrylate.
  • the acrylate or methacrylate ester radical may, however, also be linked through an Sic bridge with the organopolysiloxane.
  • a has a value of 1.0 to 2.2;
  • b has a value of 0.001 to 1.6.
  • the fractions of different average molecule weight contained in the inventive acrylate or methacrylate ester modified organopolysiloxane mixtures may differ in respect to the R and Q radicals and the a and b subscripts.
  • Organosilicone species in the above referenced silicone acrylate release coatings are believed to migrate from the coating to adjacent contacting surfaces. The cause of this migration may be nonfunctionalized silicone remaining in the release coating. These migratable species are not bound or fixed in the cured coating and thus will migrate to adjacent contacting surfaces. It has been found that by including a quaternary ammonium salt in the silic e acrylate material prior to applying it to the release substrate that by some reaction the migratable material is either prevented from migrating or converted to a material which has no adverse effect on label printing. What is known is that the inclusion of the quaternary ammonium salt solves this expensive problem.
  • the silicone acrylate release coating normally is applied to the substrate in a quan ⁇ y of from about 0.2-1.2 grams/1000 i .n2, preferably about 0.7 g/1000 i.n2.
  • the quaternary ammonium salt can be added to the silicone acrylate release coating material in a proportion of from 0.2-8 wt %.
  • the substrate can be from 1.8 to about 2.2 mils thick.
  • Examples of quaternary ammonium salts include the following: o Dimethylaminoethyl methacrylate dimethyl sulfate ("Madquat Q-5" by Norsolac, Inc.)
  • Trialkylalkyletherammonium salts e.g. Emerstat
  • release film in accordance with the present invention in comparison with a prior art release film is shown below.
  • the release compositions were coated onto a 2.0 mil biaxially oriented polypropylene and cured by conventional electron beam radiation technique.
  • the release coating was a silicone-acrylate identified as RC450 from Th. Goldschmidt of Essen, Germany, to which was added 2,4 and 8% by weight of trialkylalkyletherammonium salt.
  • the release force (grams/inch) was measured using a TESA4154 tape and a TLMI release force tester.
  • the film was convolutely wound and so held for a period of 1 week at 125°F. , so that the magnitude of release material transfer to the back side of the film could be measured.
  • the above data shows the outstanding decrease in the amoun * ' of transferred or migrated release material to the back side of the release film.
  • the data also shows that the quaternary ammonium salt modified silicone-acrylate release material decreased the release force to a moderate extent, thus maintaining its release effectiveness.
  • the silicone-acrylate coated release liner is then convolutely wound into a roll which is approximately from 60 to 80 inches in width.
  • the roll stock of the present invention was unrolled at speeds from 300 to 1500 feet per minute, simulating the unroll speed for purposes of slitting the roll stock to form lower dimension rolls. During this unrolling no dangerous electrostatic discharge levels were noted. In addition, the film tracked in an even, unvarying manner.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Laminated Bodies (AREA)

Abstract

Une pellicule de libération comprend une couche de substrat polymère orienté ayant une couche de surface constituée d'un copolymère en bloc d'éthylène/propylène sur l'une de ses faces et un revêtement de libération sur l'autre face. Lorsque le matériau de libération comprend une matière de libération en silicone-acrylate, il peut inclure un sel d'ammonium quaternaire.A release film includes a layer of oriented polymeric substrate having a surface layer made of an ethylene / propylene block copolymer on one side and a release coating on the other side. When the release material comprises a silicone-acrylate release material, it may include a quaternary ammonium salt.

Description

PLASTIC RELEASE FILM WITH TEXTURED OR NON-PLANAR SURFACE
The present invention relates to a release film, a major utility of which is to protect and carry label stock u: 1 the label is put into use on an appropriate surface.
For many years labels have been prepared with an adhesive applied to one side thereof. In instances where the adhesive is a pressure sensitive adhesive, some means had to be provided to protect the adhesive surface in advance of applying the label to the ultimate surface to be labeled. A technique has evolved over the years by which the pressure sensitive adhesive is protected by bringing the adhesive surface into contact with a release layer which has little tendency to aggressively adhere to the pressure sensitive adhesive surface. Thus, a second film having a release surface is brought into contact with the pressure sensitive surface carried by the label protecting the pressure sensitive adhesive until the label is applied to its ultimate surface. It is to be understood that the pressure sensitive adhesive can be applied to the release surface and the label stock thereafter applied to the adhesive surface. On removal of the label the pressure sensitive adhesive will preferentially adhere to the label stock.
Release films can be manufactured separately from the label face stock. The release film is manufactured by applying a commercially available release material to one side of the release film and the combination is then convolutely wound into a roll stock. Ultimately this roll stock must be unrolled and slit to a width dimension suited to a particular label dimension. Next a pressure sensitive layer is applied over the release layer and this is mated with the underside of a sheet of label stock. Alternatively the label stock can have the pressure sensitive adhesive applied to it's undersurface which in turn is mated with the release label. Following this, label indicia is printed onto the surface of label and, thereafter, the label is die cut so that it can be separated from the release sheet-label stock combination.
During the unwinding of release film roll stock for re-dimensioning purposes, serious problems can arise. After the release material is applied as a coating layer on the substrate and subjected to electron beam curing and during the convoluted winding of the stock, a portion of or a fraction of the release material is transferred to the back side of the release film. Later when this release roll is unwound to receive label stock thereon, and subsequently rewound, some release material or a fraction thereof transfers to the surface of the label stock prior to the label stock receiving printed indicia. This transferred release material causes imperfections to occur during the label printing process. The transferred release material interferes with printing. This leads to the need to discard the combination of material at a point when the product is almost completely ready for use or marketing.
Furthermore, as a result of rapid unwinding, a high electrostatic potential develops at the point of unroll. This electrostatic potential can achieve dangerous levels which can lead to fire, explosion, or physical injury. Another problem is that the film will not always track in an even, unvarying manner as it moves employed in the manufacture of the product.
This invention seeks to overcome the aforementioned difficulties.
In one aspect, the present invention provides a release film comprising an oriented thermoplastic polymeric substrate layer having a surface layer comprising an ethylene-propylene block copolymer on one side thereof and a release coating on the other side thereof. While it is not completely understood, it is believed that the ethylene-propylene block copolymer surface has a distinctive texture which causes, during unwind of a roll of said film, a reduced electrostatic potential, in comparison to a smooth surface and said surface texture permits even, unvarying transport over rollers during manufacture and use.
In another aspect, the invention provides a release film comprising an oriented thermoplastic polymeric layer having one side thereof a release coating comprising a silicone-acrylate release material, the coating including therein a quaternary ammonium salt.
The substrates contemplated herein can be any polymeric film substrate which can effectively carry a release coating on one side thereof and an ethylene-propylene block copolymer surface on the other side thereof. Preferred substrates include, polyolefin films which are oriented and preferably biaxially oriented. The substrate can be a homopolymer, copolymer or a blend thereof. A preferred homopolymer is polypropylene. Particularly preferred are isotatic polypropylenes containing at least 80% by weight of isotatic polypropylene. This substrate layer can be homopolypropylene having a melting point range from 321° to 336°F. Commercially available materials of this description include Exxon 4612 and FINA 3371. It is to be understood that the substrate can be a single material or a combination of coextruded substrate materials. For example, polypropylenes of different melt indexes can be employed to yield excellent handling characteristics. The substrate can be provided in any thickness which facilitates either human or machine handling. A preferred thickness range can be from 0.5 mils to 3 mils. The substrate material can be composed of one or a plurality of layers and may be transparent or opaque.
The ethylene-propylene block copolymer can have an ethylene content of less than 20% by weight; for example, from 2 to 20 and preferably from 3 to 15%, and a melt flow index from 1 to 100 g/10 minutes, preferably from 3 to 50 g/10 minutes. A preferred ethylene-propylene block copolymer is commercially available as Himont 8523, having a melt flow index of about 6.0 g/10 minutes. The release film substrate can be formed for example by coextruding the polypropylene film of choice with the above identified ethylene-propylene block copolymer followed by biaxially orienting the combination 4.3 times in the machine direction and 8 times in the transverse direction.
The block copolymer coated substrate is now in condition to receive a commercial release coating on the side opposite to the ethylene-propylene block copolymer. The selected release coating can be applied by any convenient technique, for example, by differential offset gravure coating. Thereafter, if the proprietary release coating needs to be cured it can be done so by any prior art technique. A convenient class of release coatings is described in U.S. Patent No. 4,678,846 and 4,306,050. In essence, these release coatings are silicone polymers having acrylic functional end groups. The material is applied to the opposite side of the block copolymer coated polypropylene film by differential offset gravure coating and the coating is cured by exposure to energized electrons at the rate of 2.5 Mrads in a RPC electron beam processor. It is to be understood than curing can be accomplished within the range from 1 to 5, preferably from 2 to 3 Mrads.
The release material of the present invention includes (meth)acrylate ester modified organopolysiloxane mixtures, comprising essentially equilibrated organopolysiloxanes with, on the average, more than 25 to fewer than 200 silicone atoms and which additionally contain 2 to 30 weight percent of organopolysiloxanes with, on the average, 2 to 25 silicone atoms and 2 to 30 weight percent of organopolysiloxanes with, on the average, 200 to 2,000 silicone atoms.
As used herein, the organopolysiloxane fractions having more than 25 to less than 200 silicone atoms are sometimes referred to as the first fraction, those having 2 to 25 silicone atoms are referred to as the second fraction, and those having 200 to 2,000 silicone atoms are referred to as the third fraction.
Especially preferred are those (meth) acrylate ester modified organopolysiloxane mixtures which contain, besides the essentially equilibrated organopolysiloxane with, on the average, more than 25 to fewer than 200 silicone atoms, 5 to 20 weight percent of organopolysiloxanes with, on the average, 5 to 25 silicone atoms and 5 to 20 weight percent of organopolysiloxanes with, on the average, 200 to 2,000 silicone atoms.
The organopolysiloxanes contained in the organpolysiloxane mixtures preferably correspond to the formula :
Ra-Si-Qb
°4- (a+b)
in which R is an alkyl radical with 1 to 4 carbon atoms, preferably, the methyl radical. R may, however, also be a vinyl or phenyl radical. Moreover, the R radical may also represent different moieties in the molecule, so that some R radicals represent methyl radicals and the other R radicals may, for example, represent a vinyl or a phenyl radical. Preferably, at least 90% of the R radicals are alkyl radicals, especially methyl radicals.
Q is an organic radical which contains the acrylate or methacrylate ester groups. Preferably, the acrylate or methacrylate ester radical is linked to the silicone atom through an SiOC bridge. The acrylate or methacrylate radical may moreover be derived from pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, ditrimethylolpropane triacrylate, ditrimethylolpropane trimethacrylate, ditrimethylolethane triacrylate, ditrimethylolethane trimethacrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, glycerin di(meth)acrylate, hydroxyethyl acrylate, hydroxpropyl acrylate and neopentyl glycol monoacrylate.
The acrylate or methacrylate ester radical may, however, also be linked through an Sic bridge with the organopolysiloxane. a has a value of 1.0 to 2.2; b has a value of 0.001 to 1.6. The fractions of different average molecule weight contained in the inventive acrylate or methacrylate ester modified organopolysiloxane mixtures may differ in respect to the R and Q radicals and the a and b subscripts.
Organosilicone species in the above referenced silicone acrylate release coatings are believed to migrate from the coating to adjacent contacting surfaces. The cause of this migration may be nonfunctionalized silicone remaining in the release coating. These migratable species are not bound or fixed in the cured coating and thus will migrate to adjacent contacting surfaces. It has been found that by including a quaternary ammonium salt in the silic e acrylate material prior to applying it to the release substrate that by some reaction the migratable material is either prevented from migrating or converted to a material which has no adverse effect on label printing. What is known is that the inclusion of the quaternary ammonium salt solves this expensive problem. The silicone acrylate release coating normally is applied to the substrate in a quan ~y of from about 0.2-1.2 grams/1000 i .n2, preferably about 0.7 g/1000 i.n2.
The quaternary ammonium salt can be added to the silicone acrylate release coating material in a proportion of from 0.2-8 wt %. The substrate can be from 1.8 to about 2.2 mils thick. Examples of quaternary ammonium salts include the following: o Dimethylaminoethyl methacrylate dimethyl sulfate ("Madquat Q-5" by Norsolac, Inc.)
o (3-Lauramidopropyl)trimethyl ammonium methyl sulfate ("Cyastat LS" by American Cynamid) o Stearamidopropyl-dimethy1-2-hydroxyethyl ammonium nitrate ("Cyastat SN" by American Cynamid)
o N,N-bis(2-hydroxyethyl)-N-(3-dodecycloxy-2- hydroxypropyl)methyl ammonium methyl sulfate
("Cyastat 609" by American Cynamid)
o Stearamidopropyl-dimethyl-2-hydroxyethyl ammonium dihydrogen-phosphate ("Cyastat SP" by American Cynamid)
o Trialkylalkyletherammonium salts (e.g. Emerstat
6660-A from Henkel Corp.)
Examples of the release film in accordance with the present invention in comparison with a prior art release film is shown below. The release compositions were coated onto a 2.0 mil biaxially oriented polypropylene and cured by conventional electron beam radiation technique. The release coating was a silicone-acrylate identified as RC450 from Th. Goldschmidt of Essen, Germany, to which was added 2,4 and 8% by weight of trialkylalkyletherammonium salt. The release force (grams/inch) was measured using a TESA4154 tape and a TLMI release force tester. The film was convolutely wound and so held for a period of 1 week at 125°F. , so that the magnitude of release material transfer to the back side of the film could be measured. The film was then unrolled and the rating of ink wetting was measured using a #8800 Berol magic marker. Rating 1 = high silicone migration, causing a severe ink wetting problem; rating 10 = no silicone migration , i.e., no ink wetting problem. The results are shown in the table below.
TABLE
The above data shows the outstanding decrease in the amoun*' of transferred or migrated release material to the back side of the release film. The data also shows that the quaternary ammonium salt modified silicone-acrylate release material decreased the release force to a moderate extent, thus maintaining its release effectiveness.
The silicone-acrylate coated release liner is then convolutely wound into a roll which is approximately from 60 to 80 inches in width. For test purposes the roll stock of the present invention was unrolled at speeds from 300 to 1500 feet per minute, simulating the unroll speed for purposes of slitting the roll stock to form lower dimension rolls. During this unrolling no dangerous electrostatic discharge levels were noted. In addition, the film tracked in an even, unvarying manner.

Claims

1. A release film comprising an oriented thermoplastic polymeric substrate layer having a surface layer comprising an ethylene-propylene block copolymer on one side thereof and a release coating on the other side thereof.
2. A release film according to claim 1 wherein the substrate comprises a polyolefin film and the release coating comprises a silicone-acrylate coating.
3. A release film comprising an oriented thermoplastic polymeric substrate layer having on one side thereof a release coating comprising a silicone-acrylate material, the coating including a quaternary ammonium salt therein.
4. A release film according to claim 3 wherein the quaternary ammonium salt is present in the silicone-acrylate material in an amount from 0.2 to 8% by weight.
5. A release film according to claim 3 or 4 wherein the oriented thermoplastic polymeric substrate has a surface layer comprising an ethylene-propylene block copolymer on the other side thereof.
6. A release film according to any preceding claim wherein the polyolefin substrate comprises a homopolymer, a copolymer or a blend thereof.
7. A release film according to claim 6 wherein the homopolymer is polypropylene.
8. A release film according to any preceding claim wherein the ethylene-propylene block copolymer has an ethylene content of less than 20% by weight and a melt flow index from 1 to lOOg/10 minutes.
9. A release film according to claim 8 wherein the block copolymer has an ethylene content from 3 to about 15% by weight.
10. The release film of claim 1 wherein said ethylene-propylene block copolymer surface has a distinct surface texture which causes, during unwind of a roll of said film, a development of reduced electrostatic potential in comparison to a smooth surface and a film which tracks in an unvarying manner.
11. Use in a release film to reduce development of electrostatic potential during unrolling of a surface layer comprising an ethylene propylene block copolymer.
12. Use in a release film to improve tracking of a surface layer comprising an ethylene-propylene block copolymer.
13. Use in a release coating comprising a silicone-acrylate material to prevent transfer of release material to a label surface of a quaternary ammonium salt therein.
EP19930901203 1991-12-17 1992-12-17 Plastic release film with textured or non-planar surface. Withdrawn EP0617662A4 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US80848691A 1991-12-17 1991-12-17
US808486 1991-12-17
US07/811,125 US5232784A (en) 1991-12-20 1991-12-20 Release film for label stock
US811125 1991-12-20
PCT/US1992/010959 WO1993011933A1 (en) 1991-12-17 1992-12-17 Plastic release film with textured or non-planar surface

Publications (2)

Publication Number Publication Date
EP0617662A1 true EP0617662A1 (en) 1994-10-05
EP0617662A4 EP0617662A4 (en) 1994-11-23

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EP19930901203 Withdrawn EP0617662A4 (en) 1991-12-17 1992-12-17 Plastic release film with textured or non-planar surface.

Country Status (6)

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EP (1) EP0617662A4 (en)
JP (1) JPH07502222A (en)
KR (1) KR940703749A (en)
AU (1) AU3327093A (en)
CA (1) CA2125885A1 (en)
WO (1) WO1993011933A1 (en)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69427132T2 (en) * 1993-12-09 2001-08-02 Mobil Oil Corp., Fairfax PARTITION FILMS FOR ADHESIVE LABELS
US6982107B1 (en) * 1997-09-15 2006-01-03 3M Innovative Properties Company Release liner for pressure sensitive adhesives
US5990238A (en) * 1997-09-19 1999-11-23 3M Innovative Properties Company Release coating for adhesive articles and method
US5914299A (en) * 1997-09-19 1999-06-22 Minnesota Mining And Manufacturing Company Abrasive articles including a polymeric additive
DE10246862B4 (en) * 2002-10-08 2007-07-19 Huhtamaki Forchheim Zweigniederlassung Der Huhtamaki Deutschland Gmbh & Co. Kg Use of a film composite with at least two layers
EP2085446A1 (en) * 2008-01-22 2009-08-05 tesa SE Liner and application of the same
JP5338519B2 (en) 2008-09-30 2013-11-13 Ｔｄｋ株式会社 Release film and ceramic parts sheet
US10293587B2 (en) 2013-11-06 2019-05-21 Upm Raflatac Oy Substrate for a label laminate, a label laminate and a method for manufacturing a label laminate
WO2022044052A1 (en) * 2020-08-31 2022-03-03 Pankaj Bhatt Biaxially oriented polyester release liner, adhesive backed article assembly and method of making same
CN118578736A (en) * 2024-08-05 2024-09-03 浙江巨美特种材料有限公司 Novel release film and preparation method thereof

Citations (1)

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EP0044544A1 (en) * 1980-07-22 1982-01-27 Toray Industries, Inc. Adhesive tape

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DE2948708C2 (en) * 1979-02-02 1984-06-28 Th. Goldschmidt Ag, 4300 Essen Process for the preparation of organopolysiloxanes modified with pentaerythritol triacrylic or pentaerythritol trimethacrylic acid esters
US4728571A (en) * 1985-07-19 1988-03-01 Minnesota Mining And Manufacturing Company Polysiloxane-grafted copolymer release coating sheets and adhesive tapes

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EP0044544A1 (en) * 1980-07-22 1982-01-27 Toray Industries, Inc. Adhesive tape

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Title
See also references of WO9311933A1 *

Also Published As

Publication number Publication date
EP0617662A4 (en) 1994-11-23
CA2125885A1 (en) 1993-06-24
JPH07502222A (en) 1995-03-09
KR940703749A (en) 1994-12-12
AU3327093A (en) 1993-07-19
WO1993011933A1 (en) 1993-06-24

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