WO2015118209A1 - Linerless labels - Google Patents

Linerless labels Download PDF

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Publication number
WO2015118209A1
WO2015118209A1 PCT/FI2014/050094 FI2014050094W WO2015118209A1 WO 2015118209 A1 WO2015118209 A1 WO 2015118209A1 FI 2014050094 W FI2014050094 W FI 2014050094W WO 2015118209 A1 WO2015118209 A1 WO 2015118209A1
Authority
WO
WIPO (PCT)
Prior art keywords
linerless label
layer
face layer
label structure
printable
Prior art date
Application number
PCT/FI2014/050094
Other languages
French (fr)
Inventor
Noel Mitchell
Jan-Erik FORSSTRÖM
Original Assignee
Upm Raflatac Oy
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
Application filed by Upm Raflatac Oy filed Critical Upm Raflatac Oy
Priority to PCT/FI2014/050094 priority Critical patent/WO2015118209A1/en
Publication of WO2015118209A1 publication Critical patent/WO2015118209A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
    • B29C55/06—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique parallel with the direction of feed
    • 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
    • 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
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • C—CHEMISTRY; METALLURGY
    • 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
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/25—Plastics; Metallised plastics based on macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/255—Polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/005—Shaping by stretching, e.g. drawing through a die; Apparatus therefor characterised by the choice of materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
    • B29K2067/003—PET, i.e. poylethylene terephthalate
    • 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
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
    • B32B2038/0028—Stretching, elongating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/516—Oriented mono-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/542—Shear strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/748—Releasability
    • 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
    • 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
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • 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
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0008—Electrical discharge treatment, e.g. corona, plasma treatment; wave energy or particle radiation
    • 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
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/14—Printing or colouring
    • B32B38/145—Printing
    • 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
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/334—Applications of adhesives in processes or use of adhesives in the form of films or foils as a label
    • 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
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
    • 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
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/304—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being heat-activatable, i.e. not tacky at temperatures inferior to 30°C
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F3/00—Labels, tag tickets, or similar identification or indication means; Seals; Postage or like stamps
    • G09F3/02—Forms or constructions
    • G09F2003/0257—Multilayer
    • G09F2003/026—Multilayer without silicon backing

Definitions

  • a printed linerless label structure is wound around itself to a roll.
  • the ratio of the 1 % secant modulus in the machine direction of the printed linerless label structure to the 1 % secant modulus in the cross direction of the linerless label structure may be between 2 and 4.
  • An elongation at break in the machine direction of the printed linerless label structure may be less than elongation at break in the cross direction of the printed linerless label structure.
  • the ratio of the elongation at break in the machine direction of the printable linerless label structure to the elongation at break in the cross direction of the printable linerless label structure may be between 0.4 and 0.9.
  • 1 % secant modulus in the machine direction of the printable linerless label structure may be between 4000 and 8000 MPa.
  • a printable linerless label structure has a monolayer structure comprising or consisting of one face layer and one adhesive layer.
  • the adhesive layer may be activatable.
  • the linerless label structure can be wound around itself to a roll for storage and/or transportation purposes. Thickness of the linerless label structure consisting of one face layer and one adhesive layer may be between 10 and 60 microns, for example between 10 and 40 microns, or between 10 and 30 microns.
  • an embodiment of linerless label structure 1 comprises a first face layer 2 having a first surface and a second surface, and a first adhesive layer consisting of an activatable adhesive 4 on the second surface of the first face layer 2.
  • the printed multilayer structure 24 may comprise multiple layers in the following order: a release layer 14, a second face layer 20, a second adhesive layer 18, printing MRK1 , a first face layer 2, and a first adhesive layer 4.
  • the second face layer 20 may comprise printing MRK 2.
  • the printed multilayer structure 24 may comprise multiple layers in the following order: a release layer 14, a second face layer 20, printing MRK 2, a second adhesive layer 18, a first face layer 2, and a first adhesive layer 4.
  • an adhesive layer of initially tacky adhesive such as PSA
  • the printable multilayer linerless label structures described above may further comprise a second adhesive layer, such as a heat sealable layer on a second surface of the second face layer (at the surface of the face layer opposite to the surface comprising the release layer). If the second adhesive layer is included it is preferably non- tacky at room temperature for allowing the label structure to be wound on a roll.
  • a second adhesive layer such as a heat sealable layer on a second surface of the second face layer (at the surface of the face layer opposite to the surface comprising the release layer). If the second adhesive layer is included it is preferably non- tacky at room temperature for allowing the label structure to be wound on a roll.
  • a first adhesive layer 4 of initially tacky adhesive may comprise or consists of a pressure sensitive adhesive (PSA).
  • PSA pressure sensitive adhesive
  • Examples of pressure sensitive adhesives include water based PSAs, solvent based PSAa and hot melt PSAs.
  • the PSA layer may consists of, for example, UV-curable hot melt which is cured by UV light after coating.
  • Pressure sensitive adhesive may be acrylic based adhesives or adhesives comprising natural or synthetic rubber. Tackifiers may be used in order to improve adhesion properties the PSAs
  • Pressure sensitive adhesive also known as self-stick or self-adhesive, forms a bond when pressure is applied at room temperature. PSA labels can be adhered to most surfaces through an adhesive layer without the use of a secondary agent such as solvents or heat to strengthen the bond.
  • a face layer according to some embodiments is opaque.
  • Opaque face layer may have an opacity of at least 70%, at least 75%, or at least 80%, for example between 70 and 95% or between 70 and 80%.
  • the ratio of elongation at break in machine direction of the face layer to elongation at break in cross direction of the face layer may be between 0.4 and 0.9.
  • 1 % secant modulus in the machine direction of the face layer may be between 4000 and 8000 MPa, preferably between 5000 and 7500 MPa.
  • the face layer may further be combined with an adhesive layer so as to form a linerless label structure from which the individual labels may be cut and subsequently applied onto the surface of an item.
  • the face layer may be printed in order to provide a printed linerless label.
  • the linerless label structure may also comprise another face layer comprising polyethylene terephthalate at least 80 wt.% and having an orientation ratio at least 4.

Abstract

The invention relates to a linerless label structures, and to a method for manufacturing said linerless label structures. According to an embodiment a linerless label structure comprises at least one face layer comprising polyethylene terephthalate at least 80 wt.% and having monoaxial orientation ratio at least 4. The invention further relates to a labelled item.

Description

Linerless labels
Field of the Application
The application concerns linerless label structures, which are woundable onto itself to a linerless label roll. In particular, the application relates to linerless label structures suitable for printing and printed linerless label structures produced thereof. Further the application concerns manufacturing of linerless label structures.
Background of the Application
It is general practice to apply a label to a surface of an item to provide decoration, and/or to display information about the product being sold, such as the content of the item, a trade name or logo. The label comprises at least a printable face layer. In addition, the label may comprises an adhesive layer in order to bond the printable layer to the surface of an article.
Summary of the Application
It is an aim of the embodiments to provide a printable linerless label structure. It is another aim to provide a printed linerless label structure. It is another object to provide a method for producing said linerless label structures.
According to an embodiment a printed linerless label structure comprises: at least one face layer, at least one print layer, and an adhesive layer for attaching the linerless label structure to a surface of an item to be labelled. At least one face layer of the linerless label structure comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. According to an embodiment a printable linerless label structure comprises: at least one printable face layer, a first adhesive layer for attaching the linerless label structure to the surface of an item to be labelled. At least one printable face layer of the printable linerless label structure comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
According to an embodiment a method for producing a printed linerless label comprises:
providing a non-oriented face layer comprising at least 80 wt.% of polyethylene terephthalate;
stretching the non-oriented face layer in machine direction with an orientation ratio between 4 and 9 so as to provide oriented face layer;
printing at least one of a first surface and a second surface of the oriented face layer;
applying an adhesive layer comprising initially tacky adhesive or applying an activatable adhesive layer to the second surface of the oriented face layer. In addition, the method may comprise coating of the first face surface comprising printing with a release layer. According to an embodiment a method for producing a printed linerless label comprising multiple layers comprises:
providing a printable linerless label structure having multiple layers in the following order: a first printable face layer, a first adhesive layer comprising pressure-sensitive adhesive, a release layer comprising a release agent, a second printable face layer, wherein at least the first printable face layer or the second printable face layer comprises at least 80 wt.% PET and is stretched in machine direction with an orientation ratio between 4 and 9; printing at least one of the first surface of the first printable face layer and the second surface of the second printable face layer;
delaminating the structural unit comprising a release layer and the second printable face layer;
attaching the delaminated structural unit on top of the first printable face layer so that the release layer forms a topmost layer of the printed linerless label structure.
In addition the method may comprise attaching the delaminated structural unit on top of the first printable face layer by applying a second adhesive at the surface of the second face layer or by activating the second face layer comprising a heat sealable layer.
According to an embodiment a labelled item comprising the printed linerless label attached to a surface of the item is provided.
Further embodiments of the application are presented in the dependent claims. According to an example the adhesive layer attaching the label to the surface of an item to be labelled and a topmost layer of the printed linerless label structure are arranged to have a low release force against each other. The topmost layer is one of the following: the at least one face layer, the at least one print layer and a release layer.
According to an example the adhesive layer attaching the label to the surface of an item is activatable and non-tacky before activation at room temperature and arranged to provide the low release force against the topmost layer of the printed linerless label structure.
According to an example a printed linerless label structure consists of the following layers in the following order: the one print layer, the one face layer, the adhesive layer. The one face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
According to an example the topmost layer of the printed linerless label structure is a release layer. According to an example the printed linerless label structure may comprise the following layers in the following order: the release layer, the one face layer, the at least one print layer arranged adjacent to at least one of a first surface and a second surface of the face layer, the adhesive layer comprising pressure sensitive adhesive for attaching the linerless label structure to a surface of an item. The one face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
According to an example a printed linerless label structure comprises multiple layers in the following order, wherein the at least one face layer consists of a first face layer and a second face layer: the release layer, the second face layer, a second adhesive layer, the first face layer, and the adhesive layer for attaching the linerless label structure to the surface of an item to be labelled. At least one of the first face layer and the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. In addition, the at least one print layer is arranged adjacent to at least one of the second face layer and the first face layer. According to an example the first face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and the second face layer is oriented at least in one direction of the second face layer. The second face layer may be monoaxially oriented in a machine direction of the layer. The second face layer may comprise at least 80 wt.% of polyolefin(s).
According to an example the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and the first face layer is oriented at least in one direction of the first face layer. The first face layer may be monoaxially oriented in a machine direction of the layer. The first face layer may comprise at least 80 wt.% of polyolefin(s).
According to an example both the first face layer and the second face layer comprise at least 80 wt.% of polyethylene terephthalate and are monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. Both the first face layer and the second face layer may comprise the orientation ratio between 4 and 9 in the machine direction of the monoaxially oriented face layer. Both the first face layer and the second face layer may comprise the orientation ratio between 5 and 8 in the machine direction of the monoaxially oriented face layer. Both the first face layer and the second face layer may comprise less than 10 wt.%, preferably less than 5 wt.%, more preferably less than 2 wt.% of polymer(s) other than polyethylene terephthalate. Both the first face layer and the second face layer may comprise polyethylene terephthalate between 80 and 100 wt.%, preferably between 90 and 100 wt.%. Both the first face layer and the second face layer may have shrinkage between 0.5 and 10% at temperatures between 20 and 50 degrees C.
According to an example a printed linerless label structure is wound around itself to a roll.
The ratio of the 1 % secant modulus in the machine direction of the printed linerless label structure to the 1 % secant modulus in the cross direction of the linerless label structure may be between 2 and 4.
The tensile strength in the machine direction of the printed linerless label structure may be between 250 and 400 MPa.
The ratio of the tensile strength in the machine direction of the printed linerless label structure to the tensile strength in the cross direction of the linerless label structure may be between 3 and 5.
An elongation at break in the machine direction of the printed linerless label structure may be less than elongation at break in the cross direction of the printed linerless label structure.
The ratio of the elongation at break in the machine direction of the printed linerless label structure to the elongation at break in the cross direction of the printed linerless label structure may be between 0.4 and 0.9.
1 % secant modulus in the machine direction of the printed linerless label structure may be between 4000 and 8000 MPa.
1 % secant modulus in the machine direction of the printed linerless label structure may be between 5000 and 7500 MPa. According to an embodiment a printable linerless label structure comprises the first adhesive layer which is activatable and initially non-tacky at room temperature and activatable into tacky state when exerting energy into the adhesive layer.
According to an embodiment a printable linerless label structure according comprises multiple layers in the following order: a first printable face layer, the first adhesive layer comprising a pressure sensitive adhesive, a release layer, and a second face layer. At least one of the first printable face layer and the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
According to an embodiment a printable linerless label structure further comprises a second adhesive layer underlying the second face layer.
According to an embodiment a printable linerless label structure comprises a first printable face layer comprising at least 80 wt.% of polyethylene terephthalate and being monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. In addition, the second face layer is oriented at least in one direction of the second face layer. The second face layer may be monoaxially oriented in a machine direction of the layer. The second face layer may comprise at least 80 wt.% of polyolefin(s). According to an embodiment a printable linerless label structure comprises the second face layer comprising at least 80 wt.% of polyethylene terephthalate and being monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. In addition, the first printable face layer is oriented at least in one direction of the first printable face layer. The first printable face layer may be monoaxially oriented in a machine direction of the layer. The first printable face layer may comprise at least 80 wt.% of polyolefin(s).
According to an embodiment a printable linerless label structure includes both the first printable face layer and the second face layer comprising at least 80 wt.% of polyethylene terephthalate and being monoaxially oriented in a machine direction comprising an orientation ratio greater than 4. Both the first printable face layer and the second face layer may comprise the orientation ratio between 4 and 9 in the machine direction of the monoaxially oriented face layer. Both the first printable face layer and the second face layer may comprise the orientation ratio between 5 and 8 in the machine direction of the monoaxially oriented face layer. Both the first printable face layer and the second face layer may comprise less than 10 wt.% preferably less than 5 wt.%, more preferably less than 2 wt.% of polymer(s) other than polyethylene terephthalate. Both the first printable face layer and the second layer may comprise polyethylene terephthalate between 80 and 100 wt.%, preferably between 90 and 100 wt.%. Both the first printable face layer and the second face layer may have shrinkage between 0.5 and 10% at temperatures between 20 and 50 degrees C. According to an example, a printable linerless label structure structure is wound around itself to a roll.
The ratio of the 1 % secant modulus in the machine direction of the printable linerless label structure to the 1 % secant modulus in the cross direction of the printable linerless label structure may be between 2 and 4.
The tensile strength in the machine direction of the printable linerless label structure may be between 250 and 400 MPa. The ratio of the tensile strength in the machine direction of the printable linerless label structure to the tensile strength in the cross direction of the printable linerless label structure may be between 3 and 5.
An elongation at break in the machine direction of the printable linerless label structure may be less than elongation at break in the cross direction of the printable linerless label structure.
The ratio of the elongation at break in the machine direction of the printable linerless label structure to the elongation at break in the cross direction of the printable linerless label structure may be between 0.4 and 0.9. 1 % secant modulus in the machine direction of the printable linerless label structure may be between 4000 and 8000 MPa.
1 % secant modulus in the machine direction of the printable linerless label structure may be between 5000 and 7500 MPa.
Description of the Drawings In the following some examples and embodiments of the invention will be described in more detail with reference to appended drawings, in which,
shows, in a cross-sectional view, an example embodiment of a printable linerless label structure (A) and a printed linerless label structure (B)
Fig. 2 shows, in a cross-sectional view, an example embodiment of a printed linerless label structure,
Fig. 3 shows, in a cross-sectional view, an example embodiment of a printed linerless label structure,
Fig. 4 shows, in a cross-sectional view, an example embodiment of a printed linerless label structure,
Fig. 5 shows, in a cross-sectional view, an example embodiment of A) a printable multilayer label structure B) a printed multilayer linerless label preform, and C) a printed multilayer linerless label structure,
Fig. 6 shows, in a cross-sectional view, an example embodiment of a
A) printable multilayer label structure B) a printed multilayer linerless label preform, and C) a printed multilayer linerless label structure, show, in a cross-sectional view, an example embodiment of a multilayer structure of a face layer, shows a label attached to a surface of an article, shows an example of a continuous linerless label web comprising plurality of pre-cut labels.
Detailed Description of the Application
In this description and claims, the percentage values relating to an amount of raw materials are percentages by weight (wt.%) unless otherwise indicated. The following reference numbers and denotations are used in this application:
Sx, Sy, Sz orthogonal directions,
TD transverse direction,
CD cross direction,
MD machine direction,
MRK1 graphics (printing, print layer),
MRK2 graphics (printing, print layer),
1 a printable linerless label structure,
2 a first face layer,
3 a printed linerless label structure,
4 a first adhesive layer,
6 a multilayer face layer structure,
8 a core layer,
10 a first skin layer,
12 a second skin layer,
14 a release coating layer,
16 a printable multilayer linerless label preform structure,
18 a second adhesive layer,
20 a second face layer,
22 an article, 23 a printed multilayer linerless label preform,
24 a printed multilayer linerless label structure,
26 a linerless label web comprising plurality of pre-cut labels.
Term "linerless label" refers to label structures suitable for adhering onto a surface of an article and which structures are not comprising a separate release liner (backing material) to be disposed of during labelling process. In other words linerless label does not contain a separate release liner during dispensing the label i.e. when applying the label onto the surface of an item. The linerless label is suitable for winding onto itself. It is also suitable for subsequent unwinding. Linerless label may be, for example, in a form of a continuous linerless label web, a printed linerless label web, or an individual cut linerless label having predefined shape and size. Linerless label comprises or consist of a face layer(s) and an adhesive layer adhering the label onto the surface of an item. Face layer may also be referred to as a face stock, a face material or a face hereinafter. Generally the release liner is used to protect the adhesive layer and discarded during label dispensing and subsequent application. Elimination of the release liner reduces material costs of the labels but also avoids the disposal of the release liner after the application of the labels. Moreover, the exclusion of the liner decreases the thickness in a roll of labels and more labels can be provided per roll.
Term "monolayer linerless label" refers to a label structure comprising or consisting of one face layer and one adhesive layer attached to the face layer.
Term "multilayer linerless label" refers to a structure comprising at least two face layers laminated together with an adhesive layer between the face layers. The multilayer linerless label further incudes another adhesive layer for attaching the linerless label onto the surface of an item.
Term "linerless label web" refers to a continuous linerless label structures. Individual labels may be cut from the continuous structures. Labels may be pre-cut, such as perforated during printing. Alternatively or in addition the labels may be cut during dispensing. Linerless label web may comprise plurality of pre-cut labels.
Linerless labels may be used in wide variety of labelling applications and end-use areas. For example in beverage labelling, food labelling, home and personal care product labelling, and labelling of industrial products. Surface of the labelled item may be, for example, plastic, glass, metal, ceramic, rubber based, or based on paper. The labelled item may be a container, such as a plastic bottle or glass bottle.
Term "release agent" refers to a composition that is able to prevent permanent bonding of other materials, such as adhesives, onto it. Release agent is able to provide a low release force. Release force value may be determined according to Finat test methods 3 and 4 at standard test conditions of 23°C ± 2°C and 50% RH ± 5% RH. Release force may be reported as centiNewtons (cN) per mm width. Release agent may be used between the layers of a multilayer structure in order to provide delamination of the structure. For example, release agent may be used to provide delamination of the linerless label structure. Thus, the release layer allows easy delamination of the label structures comprising several layers. Release agent provides also aligned delamination of the multilayer structure. In particular, the release agent may be used in a layer adjacent to the adhesive thus providing a separation of the adhesive layer from the release agent containing layer without negatively affecting the properties of the adhesive layer.
Term "printable surface" refers to a surface, such as a surface of a face layer, that is suitable for printing. Printable surface is also able to maintain the printing, such as printed text and/or graphics. Printable surface has sufficiently high surface tension. A low surface tension may lead to poor retaining capability of printing ink applied to the surface. For example, the plastic film may have a surface tension at least 36 dynes/cm, preferably at least 38 dynes/cm or at least 44 dynes/cm measured according to the standard ASTM D-2578. The surface tension may be between 36 and 60 dynes/cm, preferably between 38 and 56 dynes/cm or between 44 and 50 dynes/cm. The surface tension level may also be maintained higher than or equal to 38 dynes/cm after 50 or 120 days. According to an embodiment a printable linerless label structure comprises at least one printable face layer. For example, a printable multilayer label structure may include a first printable face layer and a second printable face layer.
Overlying/underlying refers to an arrangement of a layer in relation to another layer. Overlaying/underlying refers to an arrangement, where a layer partially or completely overlies/underlies another layer. The overlying/underlying layers are not necessarily in contact with each other, but one or more additional layers may be arranged between the overlying layers.
Adjacent refers to an arrangement, where a layer is next to another layer. Adjacent layers are in contact with each other and no additional layers are between the layers.
Topmost (outermost, uppermost, upmost) layer refers to a configuration of a linerless label structure, where the topmost layer forms upper part of the label structure arranged opposite to an adhesive layer (undermost layer) attaching the linerless label structure onto the surface of an item. Topmost layer of a linerless label structure may be, for example, a first face layer, a second face layer, a printing layer, or a release layer. Topmost surface of the linerless label structure may be a first surface of a first face layer, a first surface of a second face layer, a first surface of the printing layer, or a first surface of a release layer. For example, a printed linerless label structure comprising a multilayer structure has a release layer as a topmost layer. For example, a printable linerless label structure has a first face layer as a topmost layer and after printing a print layer over the first layer as a topmost layer.
According to one embodiment a printable linerless label structure has a monolayer structure comprising or consisting of one face layer and one adhesive layer. The adhesive layer may be activatable. The linerless label structure can be wound around itself to a roll for storage and/or transportation purposes. Thickness of the linerless label structure consisting of one face layer and one adhesive layer may be between 10 and 60 microns, for example between 10 and 40 microns, or between 10 and 30 microns. Referring to Fig. 1 A) an embodiment of linerless label structure 1 comprises a first face layer 2 having a first surface and a second surface, and a first adhesive layer consisting of an activatable adhesive 4 on the second surface of the first face layer 2. The activatable adhesive is initially non-tacky and non-blocking and capable of being transformed into a tacky adhesive form through an activation. After activation the linerless label can be attached onto an article. Since the label structure consists only one face layer it may also be referred to as a monolayer linerless label structure. A linerless label structure typically further includes printing, also referred to as a print layer. The linerless label comprising printing is referred to as a printed linerless label 3. Printing provides information and/or visual effect, such as information of the content of the item labelled. The printing may exist on a top surface, reverse side or both top and reverse side of the face layer. Print receiving surface of the face layer may be coated or surface treated prior to printing in order to provide better anchorage of the printing. The printing may comprise printed information in any form, like letters, numbers, images or codes. Referring to Fig. 1 B) the linerless label structure further includes printing MRK1 and is thus referred to as a printed linerless label structure 3. The first adhesive layer 4 consisting of initially non-tacky adhesive is activatable into tacky state before application onto the surface of an item. Above described linerless label structure consisting of a printed face layer and a first adhesive layer 4 of activatable adhesive is easy to manufacture and no extra layer is needed to protect the adhesive layer prior to or after printing. The printing MRK1 is arranged to provide the outermost (topmost) layer for the linerless label structure. In other words, there is no need for the additional layer covering the printing MRK1 . When the printed linerless label structure 3 is wound to a roll the layer next to the adhesive layer 4 is the printing MRK1 . Prior to activation the activatable adhesive does not attach to the layer adjacent to it, when wound (rolled) on itself.
Continuous linerless label structure comprising activatable adhesive is before activation of the adhesive suitable for winding onto a roll to form a self-wound linerless label web. Due to the activatable, initially non-tacky adhesive layer the continuous label structure (label web) can be rolled onto itself without using a release layer to prevent the blocking of the web. The rolled linerless label web is also suitable for unwinding. Prior to application the label web is cut into individual labels having a desired shape and size. A continuous label web may be partially cut, for example perforated, during label converting, such as during printing step. Optionally or in addition cutting may be performed during labelling step at the point of dispensing of the labels. Dispensing refers to a step of labelling, where the labels are released from the continuous label web and subsequently applied onto the surface of the items to be labelled. After unwinding, cutting into desired size and shape, and activation of the adhesive layer the individual printed labels can be attached onto an article.
Referring to Fig. 8, the printed linerless label 3 can be attached to the surface of an article 22. The printed label 3 can be affixed through the first adhesive layer to the substrate, i.e. to the surface of an article (item), such as a surface of a bottle.
According to one embodiment a printed linerless label structure includes first adhesive layer 4 of initially tacky adhesive. Initially tacky adhesive refers to an adhesive being tacky without a separate activation step. The initially tacky adhesive may be a pressure sensitive adhesive. Application of pressure may be enough to attach the label comprising pressure sensitive adhesive onto an article. The printed linerless label structure comprising a first adhesive layer 4 consisting of initially tacky adhesive has a low release force against the printed surface of the face layer 2 in order to provide winding of the linerless label structure to a roll and subsequent unwinding of the roll. According to an example, the printed first face layer 2 is coated with a release layer 14. A surface of the first adhesive layer 4 is adjacent to the release agent 14 when the linerless label structure is wound to a roll. The release layer next to the adhesive layer enables the label web to be releasably wound on itself.
Referring to Fig. 2, a first face layer 2 has a first surface and a second surface and a first adhesive layer consisting of an initially tacky adhesive on the second surface of the face layer and printing MRK1 on the first surface of the first face layer 2. Further, the printing MRK1 is covered with a release layer 14 comprising or consisting of a release agent. This kind of continuous printed linerless label structure may be wound to a roll to form a wound linerless label web. When the printed linerless label structure 3 is wound to a roll the layer next to the surface of the adhesive layer 4 is the release layer 14. The release layer 14 enables the continuous printed label web to be releasably wound on itself.
Referring to Fig. 3, printing MRK1 is on the second surface of the first face layer 2 adjacent to the adhesive layer 41 . Referring to the Fig. 4, both the first side and the second side of the face layer comprises printing. Printing MRK2 on the first side of the face layer may be further coated with a layer comprising or consisting of a release agent 14.
According to an embodiment, a linerless label structure may comprise several layers, such as a first face layer and a second face layer. The linerless labels may have a printable multilayer linerless preform structure 16 or a printed multilayer linerless label structure 24. Total thickness of the multilayer linerless label structure may be between 20 and 100 microns or between 20 and 90 microns, for example, between 20 and 65 microns or between 24 and 45 microns.
Referring to Fig. 5A, a printable multilayer linerless label preform structure 16 comprises layers in the following order: a first face layer 2, a first adhesive layer 4, a release layer 14, a second face layer 20, and a second adhesive layer 18. Second adhesive layer 18 may be initially non-tacky heat sealable coating on the surface of the second face layer. Due to the non-tacky heat sealable layer the printable multilayer linerless label preform structure 16 can be rolled onto itself without using a separate release layer to prevent the blocking of the linerless label web. In other words, the heat sealable layer is not adherent to the first face layer next to it when wounded to a roll.
The first surface of the first face layer 2 may be printed so as to provide a printed linerless label preform 23, as shown in Fig. 5B. The printed multilayer label preform 23 may be subsequently delaminated so as to form a printed linerless label suitable for adhering onto a surface of an item. Referring to Fig. 5B layers underlying (below) the adhesive layer 4 may be delaminated and replaced on top of the printing MRK1 . The printed label preform 23 may be delaminated between the first adhesive layer 4 and release layer 14 during printing step. The second adhesive layer 18 may consist of a heat sealable coating on the surface of the second face layer 20. The second adhesive layer 18 is arranged to attach the second face layer 20 with the first face layer 2 comprising printing MRK1 .
A printed multilayer linerless label structure 24 is shown in Fig. 5C. The printed multilayer linerless label 24 comprises layers in the following order: a release layer 14, a second face layer 20, a second adhesive layer 18, printing MRK1 , a first face layer, and a first adhesive layer. Alternatively, the printed multilayer structure 24 may comprise multiple layers in the following order: a release layer 14, a second face layer 20, printing MRK1 , a second adhesive layer 18, a first face layer 2, and a first adhesive layer 4. In a printed multilayer linerless label structure the release layer 14 forms the topmost layer of the structure. The first adhesive layer of the multilayer linerless label structure is initially tacky adhesive layer, such as pressure sensitive adhesive. When the printed multilayer label structure 24 is wound to a roll the layer next to the surface of the adhesive layer 4 is the release layer 14. The release layer 14 enables the continuous printed label web to be releasably wound onto itself.
An effect of the printed multilayer linerless label structure is avoiding a separate coating phase. The face layer comprising printing does not need any separate coating, but the existing delaminated layers are used to form an overlying layer to the printed face layer. This has effect of enabling printing and coating the printed surface at the same process phase. In one embodiment and referring to Figs. 6A-C a second adhesive layer 18, such as laminating adhesive, may be applied during printing step. The second adhesive 18 may be applied to the printed face layer 2. Alternatively, the second adhesive layer may be applied onto the surface of the second face layer 20 opposite the release layer 14. The layers underlying the first adhesive layer 4 may be delaminated and further attached on top of the first face layer 2 comprising printing MRK1 . Thus, the printed multilayer structure 24 may comprise multiple layers in the following order: a release layer 14, a second face layer 20, a second adhesive layer 18, printing MRK1 , a first face layer 2, and a first adhesive layer 4. Alternatively or in addition, the second face layer 20 may comprise printing MRK 2. Thus, the printed multilayer structure 24 may comprise multiple layers in the following order: a release layer 14, a second face layer 20, printing MRK 2, a second adhesive layer 18, a first face layer 2, and a first adhesive layer 4.
The second adhesive 18 may be initially tacky laminating adhesive. An effect of the embodiment is enabling printing and coating of the face layer comprising printing at the printing at the printing press.
According to an embodiment, a linerless label includes face layer(s) 2, 20 having a monolayer structure. Polymer based monolayer face layer may be blown or cast.
According to an embodiment, a face layer(s) may have a multilayer structure 6 as shown in Fig. 7. The multilayer structure 6 may be co-extruded. Alternatively, the multilayer structure may comprise several layers laminated together. For example, the polymer based layer may have a multilayer structure comprising at least two layers. Referring to Fig. 7, a three layer structure is presented. The three layer structure may comprise a core layer, a first skin layer and a second skin layer. A composition of the core layer, the first skin and the second skin may be equal. Alternatively, the composition of the layers may be different. Total thickness of the monolayer or multilayer face may be between 8 and 60 microns, for example between 12 and 50 microns or between 12 and 36 microns.
FIRST AND SECOND FACE LAYER COMPOSITIONS
At least one face layer of a linerless label structure is plastic (polymeric) based. At least one face layer of a printable label structure is suitable for printing. The plastic face layer may comprise polymers, such as polyolefin, polyester, polystyrene, polyurethane, polyamide, poly(vinylchloride) or any combinations of these. Alternatively, the polymer based face layer may comprise biodegradable polymers, such as lactic acid, starch or cellulose based. The polymer based face layer may include homopolymers, copolymers or it may consists of a polymer blend. For example, the polymer based layer may comprise mixtures of polyolefins, such as polyethylene (PE) and polypropylene (PP). In a linerless label structure at least one of the polymer based face layers is oriented monoaxially (uniaxially) in machine direction (MD). Machine direction refers to the movement of the polymer based layer i.e. longitudinal direction of the continuous plastic based face layer (winding direction of the plastic based face layer). Direction perpendicular to the machine direction is referred to as a transverse direction (TD) or cross direction (CD) of the polymer based face layer. In the figures of the present application MD corresponds to the direction Sx and CD to the direction Sy. MD oriented face layer may have a stretching ratio greater than 4, for example, between 4 and 9, preferably between 5 and 8 in MD. Stretching (orientation) ratio of the monoaxially in machine direction oriented face layer may be 4.5 or 5, preferably 6 or 7 or 8.
According to an embodiment, at least one face layer of the linerless label structure comprises or consists polyester polymers(s). The at least one face layer includes less than 10 wt.%, preferably less than 5 wt.%, more preferably less than 2 wt.% of polymer(s) other than polyester. Preferably the face layer comprises polyethylene terephthalate (PET) as a main polymer. Main polymer refers to a polymer having highest proportion in the face layer composition. The face layer comprises at least 50 wt.%, preferably at least 80 wt.% or at least 90 wt.% of polyethylene terephthalate. In the face layer total amount of PET may be between 50 and 100 wt.%, preferably between 80 and 100 wt.% or between 90 and 100 wt.%. According to an embodiment, total amount of PET may be between 50 and 98 wt.%, preferably between 80 and 98 wt.% or between 80 and 90 wt.%.
In addition, the polymer based face layer(s) may comprise minor components, such as inorganic additives or organic additives. Minor components, such as pigments or inorganic fillers may be used to provide, for example, a desired colour for the polymer based layer. Additives may include, for example, titanium dioxide, calcium carbonate and blends thereof. The polymer based face layer(s) may also comprise minor amounts of other additives and/or modifiers, e.g. plasticisers, stabilizers, anti-static agents, slip/anti-blocking agents. Total amount of minor component(s) is less than 10 wt.%, preferably less than 5 wt.% or less than 2 wt.% of the polymer based layer composition.
Due to the colouring agents, e.g. opaque and white polymer based face layer(s) may be achieved. Carbon black may be introduced to provide black or grey face layer(s). Anti-blocking additive(s) may be used in the skin layer(s) of the multilayer face structure. Anti-blocking additive may be at least one of the following: silicate, synthetic silica and synthetic kaolin. An amount of anti-blocking compound consisting of anti-blocking additive and polymeric carrier may be less than 3 wt.%, preferably less than 2 wt.%, for example 2 wt.% or 1 wt.%. Anti-blocking additive may have effect on surface roughness of the polymer based layer. For example, in the skin layer composition total amount of anti-blocking additive(s) may be between 0.05 and 0.5 wt.%.
In a monolayer linerless label structure a first face layer 2 comprises polyethylene terephthalate (PET) at least 80 wt.%. Further the first face layer is oriented in machine direction having an orientation ratio greater than 4.
In a multilayer linerless label structure at least a first face layer 2 or a second face layer 20 comprises polyethylene terephthalate (PET) at least 80 wt.%. In addition, at least the face layer comprising polyethylene terephthalate at least 80 wt.% is monoaxially oriented in a machine direction of the layer comprising an orientation ratio greater than 4. A face layer consisting of machine direction oriented PET may increase the stiffness of the linerless label providing positive effect on the dispensing properties of the label even with labels having reduced thickness. For example, higher modulus of the face layer may achieved.
A multilayer linerless label structure may comprise, in addition to a machine direction oriented PET based face layer, another face layer comprising other materials than PET. For example, another face layer may comprise or consist at least one of the following polymers: polyolefin, polystyrene, polyurethane, polyamide, poly(vinylchloride) or any combinations of these. Alternatively, the another face layer may comprise biodegradable polymers, such as lactic acid, starch or cellulose based polymers. For example, another face layer may be polypropylene based, such as biaxially oriented polypropylene (BOPP) or machine direction oriented polypropylene (MDO-PP). Alternatively, it may be PET based, for example biaxially oriented (BOPET ) or machine direction oriented (MDO-PET). The another face layer may comprise polyolefin(s), for example at least 70 wt.% of polyolefin(s), or at least 80 wt.% of polyolefin(s). Another face layer may also be paper based, such as coated paper or uncoated paper. If a multilayer linerless label structure comprises a paper based face layer, it is preferably used as a print receiving layer coated with a polymer based face layer. The polymeric based face layer is preferably clear or transparent providing visibility of the printing below. In other words, transparent face layer enables visibility of the printing underlying the face layer. For example, the paper based layer may be a first face layer 2 covered with a polymer based second face layer 20. Paper based face layer may have effect on the stiffness of the linerless multilayer label structure. Further it may have positive effect on the opacity of the labels. Paper based layer may also provide effect of reducing total thickness of the multilayer label structure. In one embodiment a printable multilayer linerless label structure comprises or consists of layers in the following order:
- a first face layer comprising PET between 50 and 100 wt.% and having an uniaxial orientation degree in machine direction between 4 and 9,
- an adhesive layer of initially tacky adhesive, such as PSA,
- a release layer comprising release agent,
- a second face layer comprising polyolefin, such as polyethylene, prolypropylene or any combination of these.
In one embodiment a printable multilayer linerless label structure comprises or consists of layers in the following order:
- a first face layer comprising polyolefin, such as polyethylene, prolypropylene or any combination of these.
- an adhesive layer of initially tacky adhesive, such as PSA,
- a release layer comprising release agent, - a second face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9. In one embodiment a printable multilayer linerless label structure comprises or consists of layers in the following order:
- a first face layer comprising paper based materials,
- an adhesive layer of initially tacky adhesive, such as PSA,
- a release layer comprising release agent,
- a second face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9.
In one embodiment, both the first face layer 2 and the second face layer 20 are polymer based and comprising polyethylene terephthalate (PET) as a main polymer. In other words, both face layers are PET based comprising between 50 and 100 wt.% of PET. In addition, the PET based layers are oriented monoaxially in machine direction having an orientation degree of at least 4.
According to specific embodiment the printable multilayer linerless label structures described above may further comprise a second adhesive layer, such as a heat sealable layer on a second surface of the second face layer (at the surface of the face layer opposite to the surface comprising the release layer). If the second adhesive layer is included it is preferably non- tacky at room temperature for allowing the label structure to be wound on a roll.
According to specific embodiment the second adhesive layer is applied after printing of the printable multilayer linerless label structure.
In one embodiment a printed multilayer linerless label structure comprises or consists of layers in the following order:
- a release layer comprising release agent,
- a second face layer comprising polyolefin, such as polyethylene, polypropylene or any combination of these, - a second adhesive layer, such as laminating adhesive,
- a print layer,
- a first face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9,
- a first adhesive layer comprising or consisting of initially tacky adhesive, such as PSA.
In one embodiment a printed multilayer linerless label structure comprises or consists of layers in the following order:
- a release layer comprising release agent,
- a second face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9,
- a second adhesive layer,
- a print layer,
- a first face layer comprising polyolefin such as polyethylene, polypropylene or any combination of these,
- a first adhesive layer comprising or consisting of initially tacky adhesive, such as PSA.
In one embodiment a printed multilayer linerless label structure comprises or consists of layers in the following order:
- a release layer comprising release agent,
- a second face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9,
- a second adhesive layer,
- a print layer,
- a first face layer comprising paper based materials,
- a first adhesive layer of initially tacky adhesive, such as PSA.
In one embodiment a printed multilayer linerless label structure comprises or consists of layers in the following order:
- a release layer comprising release agent, - a second face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9,
- a second adhesive layer,
- a print layer,
- a first face layer comprising PET between 50 and 100 wt.% and having a uniaxial orientation degree in machine direction between 4 and 9,
- a first adhesive layer of initially tacky adhesive, such as PSA.
In all embodiments of printed linerless label structure the undermost layer is a first adhesive layer attaching the label onto the surface of an article when labelled. It is also possible that a print layer is between the second face layer and the second adhesive layer. In other words, either first face layer 2 or a second layer 20 may comprise printing. According to a specific embodiment both the first face layer 2 and the second face layer 20 comprise printing.
ADHESIVE LAYERS
A linerless label structure includes at least one adhesive layer. A first adhesive layer 4 is used for attaching the label onto a surface of an item to be labelled. In one embodiment the first adhesive layer is activatable and initially non-tacky and non-blocking. In another embodiment the first adhesive layer is initially tacky, such as pressure sensitive adhesive layer. For example, a multilayer linerless label structure comprises also adhesive layer(s) other than the first adhesive layer 4, such as PSA, adhering the label to the surface of an item. Another adhesive layer of the multilayer linerless label structure may be, for example, a laminating adhesive.
A first adhesive layer 4 of initially tacky adhesive may comprise or consists of a pressure sensitive adhesive (PSA). Examples of pressure sensitive adhesives include water based PSAs, solvent based PSAa and hot melt PSAs. The PSA layer may consists of, for example, UV-curable hot melt which is cured by UV light after coating. Pressure sensitive adhesive may be acrylic based adhesives or adhesives comprising natural or synthetic rubber. Tackifiers may be used in order to improve adhesion properties the PSAs Pressure sensitive adhesive, also known as self-stick or self-adhesive, forms a bond when pressure is applied at room temperature. PSA labels can be adhered to most surfaces through an adhesive layer without the use of a secondary agent such as solvents or heat to strengthen the bond.
Alternatively, a first adhesive layer 4 may be activatable adhesive i.e. initially non-tacky, non-blocking and capable of being transformed into a tacky adhesive state through an activation. In other words, the activatable adhesive is non-tacky and non-blocking before activation. Activation may be performed by exerting energy to the adhesive layer. Activatable adhesive may be non- tacky at room temperature (between 18 and 25 °C). Activatable adhesive may be activated to a tacky state by exerting energy to the adhesive e.g. by heating the adhesive layer between 90 and 150 °C. After activation the tacky adhesive is capable of adhering to another surface. The non-tacky adhesive (prior to activation) may have a static friction coefficient less than 0.8 against aluminium at room temperature when measured according to standard ASTM D1894. The activatable adhesive may remain permanently tacky after activation. Alternatively, the activatable adhesive may return to a non-tacky state after activation and subsequent cooling to the room temperature. In other words, the activatable adhesive may be in a tacky state a specific time period after activation.
The first adhesive layer 4 may have a thickness in the range of about 5-40 μιτι, for example in the range of about 5-25 μιτι. The amount of the adhesive layer may be 10-20 g/m2, or preferably less than 15 g/m2; or more preferably less than 10 g/m2.
Tack (adhesion) of the first adhesive layer 4 towards the item labelled may be between 2 and 20 N/25mm, preferably between 3 and 15 N/25mm, for example between 7 and 12 N/25mm when measured according to Finat test method 9 (FTM9). Shear of the first adhesive layer may be more than 10 000 min when measured according to Finat test method (FTM8). Shear of the first adhesive may also be less than 10 000 min.
A multilayer linrless label structure may further include a second adhesive layer 18. Second adhesive layer may be applied onto the surface of the second face layer. Alternatively, the second adhesive layer may be applied onto the surface of the first face layer 2 comprising printing MRK1 . In a printed multilayer linerless label structure 24, the second adhesive layer is between the first face layer 2 and the second face layer 20. The second adhesive layer 18 may comprise, for example, UV curable adhesive, such as UV-curable acrylic laminating adhesive, polyurethane adhesive, such as solvent-based polyurethane, solventless polyurethane or moisture-curing polyurethane. Alternatively, the second adhesive may be a heat sealable coating on the second face layer. Preferably the second adhesive layer 18 does not comprise heat activated adhesive. However, the adhesive may be cured by heat or radiation.
The second adhesive layer 18 may have a thickness in the range of about 1- 20 μιτι, for example in the range of about 2-10 μιτι.
The adhesive layer(s) may be applied as a continuous coating covering 100% of the surface. Alternatively, adhesive layer(s) may be applied discontinuously as spots or strips covering less than 100% of the surface. For example, the adhesive may cover between 10 to 90% of the total area of the surface applied. The adhesive may be applied onto the first face layer surface and/or onto the, second face layer surface. In embodiments comprising activatable adhesive, adhesive covering less than 100% of the surface may have effect on reducing the time needed for the activation of the adhesive. Reduced amount of adhesive (less than 100% of the surface) may have effect on reducing the risk of blocking of the adhesive layers together during unwinding of a linerless label web.
RELEASE LAYER
The linerless label structure may comprise a release coating layer 14. The release coating layer may consists of a material having high repellence properties towards the adjacent adhesive layer. The release coating may consists of silicone compound, for example, cross linkable silicone compound which can be applied to the surface and cured into a cross-linked silicone, i.e. into a poly dimethyl siloxane network (PDMS). In order to achieve a silicone release coating layer a solvent-based, emulsion-based or solventless (100% solid) silicone systems may be used. The silicone may be cured, for example, by heat, ultraviolet (UV) radiation, LED, electron beam or any combination of different mechanisms. Preferably, the release layer consists of silicone which is thermal curing, UV radiation curing or mixture of these. UV curable silicone may be preferred if low melting plastic film substrates are used, such as low density polyethylene or polypropylene.
The release coating layer may consists of silicone compound. An amount of silicone compound may be less than 2 g/m2, less than 1 .5 g/m2 or less than 1 g/m2 (dry grammage). The amount of silicone compound may be at least 0.01 , 0.02 or 0.1 g/m2. The amount of silicone compound may be between 0.1 and 1 .5 g/m2 or between 0.4 and 1 .5 g/m2 or between 0.6 and 1 g/m2, for example 1 g/m2. Due to the release agent, such as silicone, delamination of the laminated structure may be achieved. Further, the release agent layer may have effect on the winding and unwinding properties of the printed label roll.
According to an embodiment, the release layer forms the topmost layer of the printed linerless label structure. The release layer provides a low release force against the adhesive layer, when the linerless structure is rolled around itself. Low release force between the layers allows subsequent unwinding of the roll. In other words, the adhesive layer can be detached from the release layer without negatively affecting the properties of the adhesive layer, such as tacky of the adhesive against the surface to be labelled. Release force of the first adhesive layer from the release layer may be controlled with the release layer composition, such a formulation of the silicone. Release force is also dependent on stiffness, size and shape of the label, and dispensing temperature and humidity. Low speed release may be between 3 and 20 cN/50mm, or between 4 and 15 cN/50mm, preferably between 5 and12 cN/50mm, for example between 5 and 7 cN/50mm when measured according to Finat test method 3 (FTM3). High speed release (with separation speed 100m/nnin) may be between 10 and 35 cN/25mm, or preferably between 10 and 25 cN/25mm when measured according to Finat test method 4 (FTM4).
MANUFACTURING
The non-oriented polymer based face layer(s) of a linerless label structure may be provided by known melt processing techniques, such as extrusion or co-extrusion process. For example, by cast-film or blown-film manufacturing. During extrusion process the polymeric raw material is heated to a molten state and extruded through a die in the form of sheet. The extruded sheet is subsequently cooled to provide non-oriented structure.
The method further comprises stretching of the continuous non-oriented structure in a machine direction of the structure with a specific orientation ratio providing a machine direction oriented structure for the face layer. Orientation (stretching) may be performed in an in-line or an off-line process. In-line process refers to a process in which the stretching is provided during the film manufacturing process i.e. directly after the melt processing of the non-oriented structure. During orienting (stretching) the randomly oriented polymer chains of the polymer based layer(s) of a linerless label structure are oriented in the direction of stretching (drawing). Stretching provides an oriented (stretched) structure for the polymer based layer(s) of a linerless label structure. Orientation under uniaxial stress provides orientation of polymer chains in the direction of stress provided. In other words, the polymer chains are oriented at least partially in the direction of stretching (drawing). Thus, the oriented product such as oriented polymer based layer(s) of a linerless label structure comprises or consists of polymer chains having specific orientation degree in the direction of stretching. The degree of orientation of the polymer chains depends on amount of stretching of the polymer based layer(s). Thus, the polymer chains in the product having higher orientation degree are more oriented when compared to the product having lower orientation degree. Through a machine direction orientation process, the melt processed structure is uniaxially stretched in the machine direction of the polymer based layer(s) so as to form uniaxially oriented structure. Machine direction refers to the movement of the polymer based layer(s) i.e. longitudinal direction of the continuous polymer based layer(s) (winding direction of the polymer based layer(s)). Direction perpendicular to the machine direction is referred to as a transverse direction (TD) or cross direction (CD) of the polymer based layer(s). In the figures of the present application MD corresponds to the direction Sx and CD to the direction Sy. Stretching is normally done by means of a machine direction orienter via rolls with gradually increasing speed. Alternatively, the stretching is done by means of orienter via rolls with rapidly increasing speed. The stretching occurs due to a difference in speed between the last and the first rolls. The rolls are heated sufficiently to bring the polymer based layer(s) to a suitable temperature, which is normally below the melting temperature (Tm), or around the glass transition temperature (Tg) of the polymer. A machine direction orientation (stretching) process is a one- step process followed by annealing.
MD oriented face layer comprising polyethylene terephthalate at least 80 wt.% may have a uniaxial machine direction stretching ratio greater than 4, for example, between 4 and 9, preferably between 5 and 8. Stretching (orientation) ratio of the monoaxially in machine direction oriented face layer may be 4.5 or 5, preferably 6 or 7 or 8.
An amount of orientation (stretching) is referred to as a stretching ratio also referred to as an orientation degree. Orientation degree is a thickness of the oriented (stretched) product relative to that of the non-oriented (non- stretched) initial structure. The initial non-oriented structure thickness is the thickness after extrusion and subsequent chilling of the structure. When stretching the initial non-oriented structure, the thickness of the non-oriented structure diminishes in the same ratio as the non-oriented structure is stretched or elongated. For example, an initial non-oriented structure may have a thickness of 100 micrometres before orientation. After the uniaxial orientation (stretching) and annealing the oriented product may have a fivefold diminished thickness of 20 micrometres. Thus, the orientation degree of the oriented product is 5.
Annealing may be performed after stretching for providing an annealed (heat- set) structure. Annealing may be performed in an annealing section, which allows stress relaxation of the oriented structure by keeping the oriented structure at an elevated temperature for a period of time. Annealing may be performed at a temperature between 190 and 240 degrees C so as to provide an oriented product, such as oriented face layer. After annealing, cooling of the oriented product to an ambient temperature may be provided. The ambient temperature may be between 18 and 25 degrees C. Annealing may enhance dimensional stability of the oriented structure, such as oriented face layer. Annealing may provide effect of reduced shrinking capability of the oriented product in subsequent converting steps, storage and/or shipping. Heat shrinkage of the oriented product may be less than 10% or less than 5%, preferably less than 2% at temperatures between 20 and 50 degrees C. For example, heat shrinkage of the oriented product is between 0.5 and 10% or preferably between 0.5 and 5% at temperatures between 20 and 50 degrees C in the direction of the orientation.
The method may further comprise surface treating of the face layer(s).
Surface(s) of the face layer(s), i.e. adhesive and/or print receiving surface(s) may be surface treated, for example, by flame treatment, corona treatment, plasma treatment. Surface treatment causes increase in a surface energy of the treated surface. Surface energy has effect on ability of a liquid, like ink or release agent, to wet the surface. Surface treatment may have effect on adhesion of the adhesive and/or printing layer. Surface treatment may have positive effect on printability and/or print quality.
According to an embodiment, the release agent layer 14 may be applied. Release layer may be applied, for example, as an aqueous emulsion using e.g. roll coating, gravure coating, roll brush coating, spray coating air knife coating, slot coating, or dipping. Subsequently heat may be applied in order to evaporate the water and cure and bind the coating to the face layer.
According to an embodiment, the first adhesive layer 4 is applied onto a second surface of the face layer 2. An emulsion adhesive layer may be applied e.g. by using a curtain coating, reverse gravure, slot-die or roller- coating methods. A hot-melt adhesive may be applied e.g. by using slot-die or roller devices. If emulsion adhesive is used the water may be evaporated from the adhesive dispersion by using e.g. hot air jets or infra-red heaters. In one embodiment of a multilayer linerless label structure a second adhesive layer 18 is applied to the second layer of the second face layer 20. The second face layer comprising the second adhesive layer 18 may be subsequently applied on top of the first face layer 2 comprising printing MRK1 . In one embodiment of a multilayer laminate structure the second adhesive layer 18 is applied directly to the first face layer 2 comprising printing MRK1 . Manufacturing further comprises printing. The printing may be carried out before cutting of the individual labels. Alternatively the printing may be carried out after pre-cutting the labels. Printing of the face layer may be provided by any suitable method compatible with the face layer and end use of the linerless label. Method may be gravure, flexographic, screen printing, offset, letter press, or thermal transfer. The printing MRK1 , MRK2 comprises ink. The inks used may comprise water-based, solvent-based or radiation- curable inks. Choice of printing technique and/or inks used depends on printable layer, among others. Printing may comprise character(s), symbol(s) or graphics, applied in mono- or multicolours. An amount of the printing (coverage of the print layer) at a face surface may be between 10 and 70% of the total surface area. Alternatively a face layer may comprise printing 3-10% of its surface area. In some examples, surface of the face layer may be fully printed, such as 70-100%, or 90-100% of the total area of the surface may be printed.
A continuous linerless label structure (linerless label web) may be cut in order to provide individual labels having a desired (predefined) shape and size. Cutting may be contactless and/or die-cutting. Contactless cutting may be performed by a laser. Contactless cutting does not apply pressure to the pressure sensitive adhesive of the label. For example, continuous linerless label structure may be partially die-cut, for example perforated, by the printer and then later cut through by a non-contact method at the point of dispensing of the labels. The linerless label web comprising pre-cut labels having predefined shape and size may be wound onto itself for storage and/or transportation. In a Fig. 9 shows an example of a continuous linerless label web comprising plurality of pre-cut labels. In embodiments comprising activatable adhesive the adhesive layer may be activated by heating using hot-air into tacky adhesive state. Alternatively, any other method exerting energy to the adhesive layer so as to reach the activation temperature of the adhesive may be used. For example, infra-red radiation or laser may be used for activation. In one embodiment a method for manufacturing a Iinerless label structure comprises:
-providing a non-oriented face layer structure comprising at least 80 wt.% PET,
-stretching the non-oriented face layer structure in machine direction with an orientation ratio between 4 and 9 so as to provide oriented face layer, -applying an activatable adhesive layer to the second surface of the oriented face layer. Further the method may comprise steps of printing of the first surface of the face layer for providing printed Iinerless label structure and cutting of the Iinerless label structure into several individual labels. During application of the label structure the adhesive layer is activated for attaching the Iinerless label onto the surface of an item to be labeled. The Iinerless label structure prior to printing and/or after printing may be wound onto a roll for storage and/or transportation.
In a specific embodiment a method for manufacturing a printed Iinerless label structure comprises:
-providing a non-oriented face layer structure comprising at least 80 wt.% PET,
-stretching the non-oriented face layer structure in machine direction with an orientation ratio between 4 and 9 so as to provide oriented face layer,
- applying an initially tacky adhesive layer to the second surface of the oriented face layer,
- printing a first surface and/or second surface of the oriented face layer, -coating the first surface with a release layer.
Further the method may comprise cutting of the Iinerless label structure into several individual labels. The printed Iinerless label structure may be wound onto a roll for storage and/or transportation.
In one embodiment a method for manufacturing a printable multilayer Iinerless label structure comprises: -providing a first face layer and a second face layer, wherein at least one of the face layers comprises at least 80 wt.% PET and is stretched in machine direction with an orientation ratio between 4 and 9,
-providing a multilayer structure having multiple layers in the following order: a first face layer, a first adhesive layer, a release layer, a second face layer.
The multilayer linerless label structure may be wound onto a roll for storage and/or transportation. In one specific embodiment the method for providing a printed multilayer linerless label structure further comprises
- printing the first surface of the first face layer,
- delaminating the structural unit comprising the release layer and the second face layer,
- applying a second adhesive layer on top of the printed face layer or at the surface of the second face layer opposite the release layer,
- attaching the structural unit comprising a release layer and the second face layer on top of the first face layer comprising printing. Further the method comprises step of cutting the printed multilayer linerless label structure into several individual labels. The printed multilayer linerless label structure may be wound onto a roll for storage and/or transportation.
In one specific embodiment the method for manufacturing a printed multilayer linerless labels structure further comprises
- applying a second adhesive layer at the surface of the second face layer,
- printing the first surface of the first face layer,
- delaminating the structural unit comprising the release layer, the second face layer and the second adhesive layer,
- activating the second adhesive layer,
- attaching the structural unit comprising the release layer, the second face layer and the activated second adhesive layer on top of the printed first face layer. Further the method comprises step of cutting the printed multilayer linerless label structure into several individual labels. The printed multilayer linerless label structure may be wound onto a roll for storage and/or transportation. According to at least some/all embodiments the continuous linerless label structure is woundable onto itself. In other words, linerless label web according to at least some/all embodiments is suitable for winding to a linerless label roll. The linerless label roll may be subsequently unrolled (unwound) for providing printing and/or cutting and dispensing of the labels. During rolling onto itself an adhesive layer of the label structure shall not attach (adhere) to the layer next to it. In an embodiment the adhesive is initially in a tacky state i.e. the adhesive is inherently a sticky adhesive. In a roll form the tacky adhesive is next to the printed face layer and the release layer in between prevents the blocking of the layers. In an embodiment the adhesive is activatable and non-tacky prior to activation. Thus, there is no need for extra layer between the printed face layer and the adhesive layer to prevent the blocking of the layers when wound to a roll.
According to at least some/all embodiments the printed linerless label structure has a low release force between the first adhesive layer 4 and the printed surface of the face layer 2 in order to provide winding of the linerless label structure to a roll and subsequent unwinding the roll. For example, the topmost surface of the linerless label structure may be repellent towards the first adhesive layer in order to provide winding and subsequent unwinding of the linerless label structure. Alternatively, the first adhesive layer may be non-tacky and non-blocking providing winding and unwinding of the linerless label structure. Low speed release between the topmost surface of the first face layer and the first adhesive layer may be between 3 and 20 cN/50mm, or between 4 and 15 cN/50mm, preferably between 5 and 12 cN/50mm, for example between 5 and 7 cN/50mm when measured according to Finat test method 3 (FTM3). High speed release (with separation speed 100m/nnin) may be between 10 and 35 cN/25mm, or preferably between 10 and 25 cN/25mm when measured according to Finat test method 4 (FTM4). In at least some/all embodiments the topmost layer(s), such as a release layer and/or a second face layer, covering the printing is protecting the print and has effect on visual appearance of the label. Topmost layer(s) may also have effect on the durability of the label against external influences, such as wear, humidity, UV-radiation and so on. A release layer as a topmost layer may also provide non-blocking layer against the first adhesive layer when the label structure is wound to a roll.
In at least some/all embodiments the topmost layer(s) covering the printing is transparent to allow visibility of the printing. A printable linerless label structure according to at least some/all embodiments is clear, thus being substantially transparent to visible light. Transparent no-label look appearance of the label is advantageous, for example, in applications where the objects beneath the label, i.e. the surface of a bottle, should be visible through the label. The haze level of a face layer should be lower than 35%, preferably equal to or lower than 25% or lower than 10%, when tested according to the standard ASTM D1003. For example, haze of the face layer is between 0.5 and 9.
A face layer according to some embodiments is opaque. Opaque face layer may have an opacity of at least 70%, at least 75%, or at least 80%, for example between 70 and 95% or between 70 and 80%.
1 % secant modulus may be used to describe the stiffness of the material. It may be measured according to ISO 527-3 standard for plastic films. 1 % secant modulus may be used to describe the rigidity of the product. Generally high modulus product requires more stress to produce a specific amount of strain (elongation). In polymer based products, such as face layers, the modulus may be directional. Directional modulus means that the modulus in a first direction may differ from the modulus in a second direction of the product. For example, the modulus may be different in MD and in CD of the face layer.
Linerless label structures according to at least some/all embodiments have effect on conformability of labels. Conformable label refers to a label being capable to conform smoothly and without wrinkles to the contour of the article even when this is curved in two-dimensions. To obtain a conformable label, also suitable conformability of the face layer(s) is required. At least some/all embodiments of the face layer have directional modulus. Directional modulus of the face layer may have effect on the conformability of the label. A linerless label structure according to at least some/all embodiments has 1 % secant modulus in machine direction (MD) at least 4000 MPa, preferably at least 5000 MPa or at least 6000 MPa, when tested according to ISO 527-3 standard for plastic films. For example, 1 % secant modulus may be between 4000 and 8000 MPa, preferably between 5000 and 7500 MPa or 6000 and 7000 MPa. A linerless label structure comprising 1 % secant modulus in MD between 4000 and 8000 MPa, more preferably between 6000 and 7000 MPa may have effect on providing sufficient rigidity for the linerless label structure in the machine direction. Sufficient rigidity is needed, for example, during dispensing of the labels. Sufficient rigidity may also have effect on stability of the linerless label structure during subsequent die-cutting process.
At least some/all embodiments have 1 % secant modulus in cross direction (CD) less than that in machine direction (MD) of the linerless label. Preferably the 1 % secant modulus is at least two times higher in MD than in CD of the linerless label. 1 % secant modulus in CD may be at least 1000 MPa, 1500 MPa or 2000 MPa, when tested according to ISO 527-3 standard for plastic films. For example, 1 % secant modulus in CD may be between 1000 and 4000 MPa, or between 1500 and 3500 MPa. 1 % secant modulus of the linerless label in CD below 3500 MPa, for example 3000 MPa, may have an effect of increased flexibility of the linerless label. For example, biaxially oriented film has 1 % secant modulus in CD of between 4000 and 5000 MPa.
At least some/all embodiments have 1 % secant modulus in machine direction (MD) of the linerless label at least twice that of cross direction (CD) of the linerless label. In other words, ratio of 1 % secant modulus in MD to 1 % secant modulus in CD (MD/CD) of the linerless label is at least 2. MD/CD ratio of 1 % secant modulus may be between 2 and 4, or between 2 and 3.5. For example, ratio of 1 % secant modulus in MD to 1 % secant modulus in CD (MD/CD) of the linerless label is 2 or 2.5, preferably 3 or 3.5. or 4. 1 % secant modulus ratio MD/CD of at least 2 may provide an effect of conformability of the linerless label. At least some/all embodiments have an elongation at break both in machine direction and in cross direction of the linerless label less than 50% or less than 40%, preferably less than 30%. Elongation at break in MD may be between 5 and 50%, or between 5 and 30%, or between 15 and 30%. Elongation in CD and in MD may be equal. Elongation at break in MD of the linerless label may be less than elongation in CD of the linerless label. Difference between the elongation at break in CD and MD may be less than 30%, preferably less than 20 or less than 10%. Elongation less than 50% in both CD and MD of the linerless label may have effect on die-cutting performance of the linerless label. For example, uniform and even die-cutting operation in both directions may be achieved.
At least some/all embodiments have the tensile strength in machine direction at least three times that of cross direction of the linerless label. In other words, at least some/all embodiments have the ratio of the tensile strength in MD of the linerless label to the tensile strength in CD of linerless label at least 3, for example between 3 and 5. For example, tensile strength in the machine direction of the linerless label is at least 200 MPa, preferably at least 250 MPa or at least 300 MPa. For example, tensile strength is between 250 MPa and 400 MPa in machine direction of the linerless label. Tensile strength in CD of the linerless label may be at least 30 MPa, preferably at least 50 or at least 70 MPa. For example, between 30 and 120 MPa.
Some examples for the machine direction oriented face layer comprising polyethylene terephthalate at least 80 wt.%, having an orientation ratio at least 4, and a thickness between 8 and 60 microns are presented below.
According to an example the face layer has the ratio of 1 % secant modulus in MD to 1 % secant modulus in CD of the face layer at least 2. Preferably, the ratio of 1 % secant modulus in MD to 1 % secant modulus in CD (MD/CD) of the face layer is between 2 and 4. Face layer may have a tensile strength in machine direction of the face layer between 250 and 400 MPa. In addition, the face layer may have a ratio of tensile strength in the machine direction of the face layer to tensile strength in the cross direction of the face layer between 3 and 5. Further, the face layer may have an elongation at break in the machine direction of the face layer less than elongation at break in the cross direction of the face layer. For example, the ratio of elongation at break in machine direction of the face layer to elongation at break in cross direction of the face layer may be between 0.4 and 0.9. In addition, 1 % secant modulus in the machine direction of the face layer may be between 4000 and 8000 MPa, preferably between 5000 and 7500 MPa. The face layer may further be combined with an adhesive layer so as to form a linerless label structure from which the individual labels may be cut and subsequently applied onto the surface of an item. The face layer may be printed in order to provide a printed linerless label. The linerless label structure may also comprise another face layer comprising polyethylene terephthalate at least 80 wt.% and having an orientation ratio at least 4.
The embodiments described above are only example embodiments of the invention and a person skilled in the art recognizes readily that they may be combined in various ways to generate further embodiments without deviating from the basic underlying invention.

Claims

Claims:
1 . A printed linerless label structure comprising:
- at least one face layer,
- at least one print layer, and
- an adhesive layer for attaching the linerless label structure to a surface of an item to be labelled,
wherein the at least one face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
2. A printed linerless label structure according to claim 1 , wherein the adhesive layer and a topmost layer of the printed linerless label structure are arranged to have a low release force against each other.
3. A printed linerless label according to claim 2, wherein the topmost layer is one of the following: the at least one face layer, the at least one print layer and a release layer.
4. A printed linerless label structure according to claim 2 or 3, wherein the adhesive layer is activatable and non-tacky before activation at room temperature and arranged to provide the low release force against the topmost layer of the printed linerless label structure.
5. A printed linerless label structure according to claim 4 consisting of the following layers in the following order:
- the one print layer,
- the one face layer,
- the adhesive layer,
wherein the one face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
6. A printed linerless label structure according to claim 3, wherein the topmost layer of the printed linerless label structure is the release layer.
7. A printed linerless label structure according to claim 6, wherein the printed linerless label structure comprises the following layers in the following order:
- the release layer,
- the one face layer,
- the at least one print layer arranged adjacent to at least one of a first surface and a second surface of the face layer,
- the adhesive layer comprising pressure sensitive adhesive for attaching the linerless label structure to a surface of an item, wherein the one face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
8. A printed linerless label structure according to claim 6, wherein the printed linerless label structure comprises multiple layers in the following order, wherein the at least one face layer consists of a first face layer and a second face layer:
- the release layer,
- the second face layer,
- a second adhesive layer,
- the first face layer, and
- the adhesive layer for attaching the linerless label structure to the surface of an item to be labelled,
wherein at least one of the first face layer and the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and
wherein the at least one print layer is arranged adjacent to at least one of the second face layer and the first face layer.
9. A printed linerless label structure according to claim 8, wherein the first face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and wherein the second face layer is oriented at least in one direction of the second face layer.
10. A printed linerless label structure according to claim 9, wherein the second face layer is monoaxially oriented in a machine direction of the layer.
1 1 . A printed linerless label structure according to claim 9 or 10, wherein the second face layer comprises at least 80 wt.% of polyolefin(s).
12. A printed linerless label structure according to claim 8, wherein the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and
wherein the first face layer is oriented at least in one direction of the first face layer.
13. A printed linerless label structure according to claim 12, wherein the first face layer is monoaxially oriented in a machine direction of the layer.
14. A printed linerless label structure according to claim 12 or 13, wherein the first face layer comprises at least 80 wt.% of polyolefin(s).
15. A printed linerless label structure according to claim 8, wherein both the first face layer and the second face layer comprise at least 80 wt.% of polyethylene terephthalate and are monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
16. A printable linerless label structure according to claim 15, wherein both the first face layer and the second face layer comprise the orientation ratio between 4 and 9 in the machine direction of the monoaxially oriented face layer.
17. A printable linerless label structure according to claim 15, wherein both the first face layer and the second face layer comprise the orientation ratio between 5 and 8 in the machine direction of the monoaxially oriented face layer.
18. A printable linerless label structure according to any of the claims 15- 17, wherein both the first face layer and the second face layer comprise less than 10 wt.%, preferably less than 5 wt.%, more preferably less than 2 wt.% of polymer(s) other than polyethylene terephthalate.
19. A printable linerless label structure according to any of the claims 15- 17, wherein both the first face layer and the second face layer comprise polyethylene terephthalate between 80 and 100 wt.%, preferably between 90 and 100 wt.%.
20. A printed linerless label structure according to any of the claims 9-19, wherein both the first face layer and the second face layer have shrinkage between 0.5 and 10% at temperatures between 20 and 50 degrees C.
21 . A printed linerless label structure according to any of the preceding claims, wherein the printed linerless label structure is wound around itself to a roll.
22. A printed linerless label structure according to any of the preceding claims, wherein the ratio of the 1 % secant modulus in the machine direction of the printed linerless label structure to the 1 % secant modulus in the cross direction of the linerless label structure is between 2 and 4.
23. A printed linerless label structure according to any of the preceding claims, wherein the tensile strength in the machine direction of the printed linerless label structure is between 250 and 400 MPa.
24. A printed linerless label structure according to any of the preceding claims, wherein the ratio of the tensile strength in the machine direction of the printed linerless label to the tensile strength in the cross direction of the printed linerless label structure is between 3 and 5.
25. A printed linerless label structure according to any of the preceding claims, wherein an elongation at break in the machine direction of the printed linerless label is less than elongation at break in the cross direction of the printed linerless label structure.
26. A printed linerless label structure according to any of the preceding claims, wherein the ratio of the elongation at break in the machine direction of the printed linerless label structure to the elongation at break in the cross direction of the printed linerless label structure is between 0.4 and 0.9.
27. A printed linerless label structure according to any of the preceding claims, wherein 1 % secant modulus in the machine direction of the printed linerless label structure is between 4000 and 8000 MPa.
28. A printed linerless label structure according to any of the claims 1 -26, wherein 1 % secant modulus in the machine direction of the printed linerless label structure is between 5000 and 7500 MPa.
29. A printable linerless label structure comprising:
- at least one printable face layer,
- a first adhesive layer for attaching the linerless label structure to the surface of an item to be labelled,
wherein at least one printable face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
30. A printable linerless label structure according to claim 29, wherein the first adhesive layer is activatable and initially non-tacky at room temperature and activatable into tacky state when exerting energy into the adhesive layer.
31 . A printable linerless label structure according to claim 29, wherein the printable linerless label structure comprises multiple layers in the following order: a first printable face layer, the first adhesive layer comprising a pressure sensitive adhesive, a release layer, and a second face layer,
wherein at least one of the first printable face layer and the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
32. A printable linerless label structure according to claim 31 , wherein the printable linerless label structure further comprises a second adhesive layer underlying the second face layer.
33. A printable linerless label structure according to claim 31 or 32, wherein the first printable face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4, and
wherein the second face layer is oriented at least in one direction of the second face layer.
34. A printable linerless label structure according to claim 33, wherein the second face layer is monoaxially oriented in a machine direction of the layer.
35. A printable linerless label structure according to claim 34, wherein the second face layer comprises at least 80 wt.% of polyolefin(s).
36. A printable linerless label structure according to claim 33, wherein the second face layer comprises at least 80 wt.% of polyethylene terephthalate and is monoaxially oriented in a machine direction comprising an orientation ratio greater than 4 and,
wherein the first printable face layer is oriented at least in one direction of the first printable face layer.
37. A printable linerless label structure according to claim 36, wherein the first printable face layer is monoaxially oriented in a machine direction of the layer.
38. A printable linerless label structure according to claim 37, wherein the first printable face layer comprises at least 80 wt.% of polyolefin(s).
39. A printable linerless label structure according to claim 31 or 32, wherein both the first printable face layer and the second face layer comprise at least 80 wt.% of polyethylene terephthalate and are monoaxially oriented in a machine direction comprising an orientation ratio greater than 4.
40. A printable linerless label structure according to claim 39, wherein both the first printable face layer and the second face layer comprise the orientation ratio between 4 and 9 in the machine direction of the monoaxially oriented face layer.
41 . A printable linerless label structure according to claim 39, wherein both the first printable face layer and the second face layer comprise the orientation ratio between 5 and 8 in the machine direction of the monoaxially oriented face layer.
42. A printable linerless label structure according to any of the claims 39- 41 , wherein both the first printable face layer and the second face layer comprise less than 10 wt.% preferably less than 5 wt.%, more preferably less than 2 wt.% of polymer(s) other than polyethylene terephthalate.
43. A printable linerless label structure according to any of the claims 39- 41 , wherein both the first printable face layer and the second layer comprise polyethylene terephthalate between 80 and 100 wt.%, preferably between 90 and 100 wt.%.
44. A printable linerless label structure according to any of the claims 33- 43, wherein both the first printable face layer and the second face layer have shrinkage between 0.5 and 10% at temperatures between 20 and 50 degrees C.
45. A printable linerless label structure according to any of the claims 30, 31 , or 33-44, wherein the printable linerless label structure is wound around itself to a roll.
46. A printable linerless label structure according to any of the claims 29- 45, wherein the ratio of the 1 % secant modulus in the machine direction of the printable linerless label structure to the 1 % secant modulus in the cross direction of the printable linerless label structure is between 2 and 4.
47. A printable linerless label structure according to any of the claims 29- 46, wherein the tensile strength in the machine direction of the printable linerless label structure is between 250 and 400 MPa.
48. A printable linerless label structure according to any of the claims 29-
47, wherein the ratio of the tensile strength in the machine direction of the printable linerless label structure to the tensile strength in the cross direction of the printable linerless label structure is between 3 and 5.
49. A printable linerless label structure according to any of the claims 29-
48, wherein an elongation at break in the machine direction of the printable linerless label structure is less than elongation at break in the cross direction of the printable linerless label structure.
50. A printable linerless label structure according to any of the claims 29-
49, wherein the ratio of the elongation at break in the machine direction of the printable linerless label structure to the elongation at break in the cross direction of the printable linerless label structure is between 0.4 and 0.9.
51 .A printable linerless label structure according to any of the claims 29- 50, wherein 1 % secant modulus in the machine direction of the printable linerless label structure is between 4000 and 8000 MPa.
52. A printable linerless label structure according to any of the claims 29- 50, wherein 1 % secant modulus in the machine direction of the printable linerless label structure is between 5000 and 7500 MPa.
53. A labelled item comprising the printed linerless label according to any of the claims 1 -28 attached to a surface of the item.
54. A method for producing a printed linerless label according to any of the claims 1 -7,or 21 -28, the method comprising:
- providing a non-oriented face layer comprising at least 80 wt.% of polyethylene terephthalate,
- stretching the non-oriented face layer in machine direction with an orientation ratio between 4 and 9 so as to provide oriented face layer,
- printing at least one of a first surface and a second surface of the oriented face layer,
- applying an adhesive layer comprising initially tacky adhesive or applying an activatable adhesive layer to the second surface of the oriented face layer.
55. A method according to claim 54, further comprising coating of the first face surface comprising printing with a release layer.
56. A method for producing a printed linerless label comprising multiple layers according to any of the claims 8-28, the method comprising:
- providing a printable linerless label structure having multiple layers in the following order:
o a first printable face layer,
o a first adhesive layer comprising pressure-sensitive adhesive,
o a release layer comprising a release agent,
o a second printable face layer, wherein at least the first printable face layer or the second printable face layer comprises at least 80 wt.% PET and is stretched in machine direction with an orientation ratio between 4 and 9,
- printing at least one of the first surface of the first printable face layer and the second surface of the second printable face layer,
- delaminating the structural unit comprising a release layer and the second printable face layer,
- attaching the delaminated structural unit on top of the first printable face layer so that the release layer forms a topmost layer of the printed linerless label structure.
57. A method according to claim 56, wherein the method further comprises attaching the delaminated structural unit on top of the first printable face layer by applying a second adhesive at the surface of the second face layer or by activating the second face layer comprising a heat sealable layer.
PCT/FI2014/050094 2014-02-10 2014-02-10 Linerless labels WO2015118209A1 (en)

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Cited By (1)

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WO2022112372A1 (en) * 2020-11-24 2022-06-02 Tesa Se Adhesive tape

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GB1131523A (en) * 1965-07-12 1968-10-23 Du Pont Polyethylene terephthalate film and process for its preparation
US5496636A (en) * 1992-12-29 1996-03-05 Ideal Tape Co., An American Biltrite Company Printable self-wound fire retardant pressure-sensitive adhesive tape
US6589463B1 (en) * 1999-06-01 2003-07-08 Dupont Canada Inc. High tensile strength polethylene terephthalate film and process
US20060141196A1 (en) * 2003-06-11 2006-06-29 Martin Utz Label sheet
US20090120571A1 (en) * 2005-05-12 2009-05-14 Max Otto Henri Rasmussen Heat-sealable label
JP2011227215A (en) * 2010-04-19 2011-11-10 Fukushima Printing Industries Co Ltd Pasteboard-less label and method for manufacturing the same
US20110293871A1 (en) * 2010-05-28 2011-12-01 Nathan Storfer-Isser Laminating film and method of using same

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GB1131523A (en) * 1965-07-12 1968-10-23 Du Pont Polyethylene terephthalate film and process for its preparation
US5496636A (en) * 1992-12-29 1996-03-05 Ideal Tape Co., An American Biltrite Company Printable self-wound fire retardant pressure-sensitive adhesive tape
US6589463B1 (en) * 1999-06-01 2003-07-08 Dupont Canada Inc. High tensile strength polethylene terephthalate film and process
US20060141196A1 (en) * 2003-06-11 2006-06-29 Martin Utz Label sheet
US20090120571A1 (en) * 2005-05-12 2009-05-14 Max Otto Henri Rasmussen Heat-sealable label
JP2011227215A (en) * 2010-04-19 2011-11-10 Fukushima Printing Industries Co Ltd Pasteboard-less label and method for manufacturing the same
US20110293871A1 (en) * 2010-05-28 2011-12-01 Nathan Storfer-Isser Laminating film and method of using same

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WO2022112372A1 (en) * 2020-11-24 2022-06-02 Tesa Se Adhesive tape

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