DESC:FIELD OF THE INVENTION
[001] The present invention generally relates to a coextruded biaxially oriented multilayer polypropylene (BOPP) Film. More particularly, the present invention relates to a coated BOPP film-based pressure sensitive label film having peel off effect, wherein the film is used for labeling the product.
BACKGROUND OF THE INVENTION
[002] There is a continuous demand of tamper evident label, protecting the product, item or container reveal any attempt of tampering by leaving the evidence behind on the substrate where it is applied. This prevents the unauthorized access to the protective products. Such films are widely used in diverse applications such as chip cards, road tax badges, labels for securing products like medicines, chemical composition against theft, or price tags and other various applications. Traditional labeling of the product with paper-based label secured with pressure sensitive adhesive is generally quick and relatively inexpensive but due to some disadvantage of paper label material like easy tear ability, less durable & poor water resistance, polymeric label material has gained the market share for tamper evident application.
[003] Hologram and void security label technology was introduced and commonly used solution for tamper evident application. However, this technology has become common, highly duplicated and hence decreasing its effectiveness as a security indicating option. Also, additional converting or printing process make it complex, less cost effective and low margin product for label material manufacturer. Destructive label material is another tamper indication solution in which film layers designed to be weak so that it gets splitted into multiple layers upon tampering. Forgery-preventing film disclosed in the prior art US7270874B2, US8158230B2, US7960022B2, US9375896B2, US7960022B2 uses different polymer material to produce label face stock including HDPE, LDPE, PET, CPP with non-laminated construction or multilayer laminates containing layers of same or different polymeric material. Again, multilayer laminated label material is a complex product with challenge in recyclability.
[004] The label material described in the prior art US7270874 B2 comprises a base layer of biaxially-oriented and voided high density polyethylene (HDPE) that is adhesive layer on the lower surface and coated printable surface on the top of base layer. This Label exhibit internal cohesive failure, measured by peel test in the embodiment, if attempt is made to peel the label off from the applied substrate and it leave the residue behind.
[005] However, the major drawback of these label film disclosed in the prior arts is complex manufacturing process, limited stiffness, and majority use of special/limited raw material or process to make the label film which makes the product expensive for the final application.
[006] Hence, there is a need to develop a newer, cost-effective label material with alternative material for security label applications which provides evidence of tampering.
SUMMARY OF THE INVENTION
[007] The primary objective of the present invention is to provide a multilayer voided (cavitated) biaxially oriented polypropylene film (BOPP) security label applications like tamper evident label films.
[008] Another objective of the present invention is to provide an alternative and cost-effective label face stock for security label applications which provide alternate option to the traditional face stocks.
[009] Still another objective of the present invention is to provide a BOPP film having printable matt coated surface on one side and corona treated white BOPP film surface on another side with the layer construction such that it reveals any attempt of tampering by leaving the residue/portion of film behind on the substrate where it is applied.
[0010] To achieve the above objectives, the present invention provided with a novel multilayered, voided opaque label material made from biaxially oriented polypropylene (BOPP) film (otherwise known as substrate layer), with the composition of respective layers selected such that it produces the desired density of overall thickness and internal cohesive strength between selected layers to impart peeling effect as a result of tampering. The film contains an upper and lower skin layer, adjacent and optional upper and lower tie layers and a core layer. Filler, antiblock, antistatic agent, matting agent, slip agent and/or processing aid may be added in respective layers of BOPP film depending on the application demand.
[0011] According to the present invention, at least one skin layer of the multi-layered destructive label film or substrate layer is coated with a matt coating layer (otherwise known as water-based formulation) and another skin layer of the BOPP film or substrate layer is surface treated (i.e., corona treated), where the matt side is compatible with wide variety of printing methods such as thermal transfer, UV, and water flexo, UV inkjet, UV and conventional offset etc. The corona treated side provides enhanced adhesive receptivity.
[0012] According to one embodiment of the present invention, the upper and lower tie layers are optional layers.
[0013] According to one embodiment of the present invention the substrate layer is a multi-layered, voided, Biaxially oriented polypropylene film. The formulation of the substrate layer comprising, (a) the upper skin layer comprises 5-50 % matt compound, 1-60% copolymer, 0-20% tercopolymer, 0-5% antiblock additives and 0-5% polymer processing aids, (b) the upper tie layer comprises 20-100% of homo polypropylene, 0-40% calcium carbonate masterbatch, (c) the core layer comprises 20-80 % of homo polypropylene, 5-30% of CaCO3 masterbatch, 1-10% titanium dioxide, 0-3% antistatic additives and 0-2% polymer processing aids, (d) the lower tie layer comprises 20-100 % of homo polypropylene, 0-30% of CaCO3 masterbatch and 0-10% of titanium dioxide, and (e) the lower skin layer comprises 30-98% of homo polypropylene or copolymer and 0-30% of tercopolymer and 1-10% antiblock additives.
[0014] According to one preferred embodiment of the present invention the lower skin layer is corona treated and the upper skin layer is later offline coated with printable water based matt coating using gravure technique.
[0015] The formulation of matt coating layer comprises 35-50% water based polymeric binder, 35-50% powder filler or combination of fillers, 1-10% powdered titanium dioxide (TiO2) and/or aluminium hydroxide [Al(OH)(3)], 0.1-1% of dispersing agent, and 0.5 to 4 % cross linker.
[0016] The thickness of the upper skin layer ranges between 1 to 5 % of total film substrate, the thickness of the upper tie layer ranges between 3 to 10% of total film substrate, the thickness of the core layer ranges between 60 to 90 % of total film substrate, the thickness of the lower tie layer ranges between 3 to 10% of total film substrate, and the thickness of the lower skin layer ranges between 1 to 5% of total film substrate.
[0017] The thickness of the matt coating layer ranges between 1-10 micron and the overall thickness of the multilayered film ranges between 70-90 micron.
[0018] The multi-layered film is a destructive label film (tamper evident label film).
[0019] According to another aspect of the present invention, it is provided a method of manufacturing of a multilayered destructive label film, comprising the steps of (a) manufacturing of biaxially oriented polypropylene film substrate by stretching the substrate film in both longitudinal and transverse directions (b) slitting the manufactured BOPP film substrate; and (c) applying matt coating formulation (otherwise known as water-based coating) on at least one surface of the BOPP substrate comprising matt compound. Further, another side of the BOPP film substrate is surface treated (i.e., corona treatment).
[0020] Thus, the advantages of the present invention including but not limited to a novel, cost-effective, multilayered white voided (cavitated) BOPP film for wide variety of applications like tamper evident, security label film, anti-counterfeiting film, forgery preventing film, and peel off film application. The white colored film is produced with the help of agents like CaCo3.
DETAILED DESCRIPTION OF DRAWINGS:
[0021] The foregoing and other features and advantages of the invention will be more fully understood from the following description made with reference to the drawings.
[0022] FIG. 1 illustrates a schematic cross-sectional view of multi-layered destructive label film according to one exemplary embodiment of the present invention.
[0023] FIG. 2 illustrates a schematic cross-sectional view of a substrate layer according to one exemplary embodiment of the present invention.
DETAILED DESCRIPTION:
[0024] Aspects of the present invention are best understood by reference to the description set forth herein. All the aspects described herein will be better appreciated and understood when considered in conjunction with the following descriptions. It should be understood, however, that the following descriptions, while indicating preferred aspects and numerous specific details thereof, are given by way of illustration only and should not be treated as limitations. Changes and modifications may be made within the scope herein without departing from the spirit and scope thereof, and the present invention herein includes all such modifications.
[0025] Several aspects of the present invention are disclosed herein. It is to be understood that these aspects may or may not overlap with one another. Thus, part of one aspect may fall within the scope of another aspect, and vice versa. Each aspect is illustrated by a number of embodiments, each of which in turn, can include one or more specific embodiments. It is to be understood that the embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another, or specific embodiments thereof, and vice versa.
[0026] A broad framework of the principles will be presented by describing various embodiments of this invention using exemplary aspects. The terms "one embodiment" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. For clarity and ease of description, each aspect includes only a few embodiments. Different embodiments from different aspects may be combined or practiced separately, to design a customized process or product depending upon application requirements. Many different combinations and sub-combinations of a few representative processes or structures shown within the broad framework of this invention, that may be apparent to those skilled in the art but not explicitly shown or described, should not be construed as precluded.
[0027] The present invention relates to a multi-layered biaxially oriented film for destructive label application and method of its manufacturing thereof.
[0028] Definitions:
[0029] Reference to "layer" or "film" as used herein refers to a structure of a single polymer type or a blend of polymers.
[0030] Reference to "BOPP film" as used herein refers to a Biaxially Oriented Polypropylene Film which is produced by stretching polypropylene film in both machine direction and transverse direction. These films are preferred substrate for food packaging and various other applications globally. These films exhibit a wide range of characteristics including their inherent moisture barrier properties, seal ability, high clarity, and graphic reproduction.
[0031] Reference to "skin layer" as used herein refers to the portion of BOPP film that is located outermost of all the layers of the BOPP film. The skin layer is subjected to coating or surface treatments like corona treatment or plasma treatment.
[0032] Reference to "core layer" as used herein refers to the portion of BOPP film that is located in the center of all the layers or being sandwich between the skin layers of the BOPP film.
[0033] Reference to "tie layer," as used herein refers to a material placed on one or more layers, partially or entirely, to promote the adhesion of one layer to another surface. Preferably, tie layers are the adhesive layers or coatings which is positioned between skin layers and the core layer of the BOPP film.
[0034] Reference to "corona treated," as used herein refers to a surface treatment technique used to modify the surface properties. In polymeric films, the corona treatment is done to improve adhesion property of the desired layer/surface. A low temperature corona discharge plasma is utilized for the modification of surface properties. In this, the corona discharge is an electrical discharge brought about by the ionization of a fluid such as air surrounding a conductor that is electrically charged. The generation of corona plasma is done by the application of high voltage to an electrode having a sharp tip. The plasma is formed at the tip of electrode. A linear array of electrodes is utilized quite often to create a curtain of corona plasma. The corona plasma curtain allows the passage of materials such as plastics, cloth, or paper through the corona plasma curtain to impart changes in the surface energy of the material.
[0035] Reference to "slip additive," as used herein refers to agents which are used to reduce the friction coefficient of the polymeric layer while maintaining the optic properties of the film, e.g., Clarity and transparency of the film.
[0036] Reference to "anti-block additive" as used herein refers to additives which are used to minimize the interaction between two layers. Suitable anti-blocking additive include, but are not limited to, talc, mica, natural silica, synthetic silica, limestone, zeolite, organic additives etc.
[0037] Reference to “antistatic additive” as used herein refers to additives to reduce the built up of static electricity development on the surface of the materials.
[0038] Reference to “Polymer Processing Aids” (PPA) as used herein refers to a material to be added in molten polymer to enhance the quality of finished product by reducing the damages like melt fracture, die build up and polymer degradation.
[0039] Reference to “dispersing agent” as disclosed herein refers to any compound that helps in dispersion of molecules. In other words, the dispersing agent chemical agents that are used for the separation of particles or molecules. Dispersing agents are otherwise known as surfactants. Several dispersion agents are there that based on the nature of the suspension such as water based, solvent based or solvent free formulations.
[0040] Reference to the term “fillers” as disclosed herein refers to an organic or inorganic particles that is added with polymer to improve the polymer properties and to reduce the cost. Generally used fillers are calcium carbonate (CaCO3), synthetic silica, aluminium silicate, or combinations thereof.
[0041] Reference to the term “cross linkers” as disclosed herein refers to an agent which links two polymer chains thereby providing stabilization to the polymer. Cross linkages are formed by creating a covalent or weak bond between two molecules by means of heat, pH, UV irradiation, electron beam irradiation, or by other means.
[0042] According to one aspect of the present invention, it discloses a multi-layered biaxially oriented polypropylene (BOPP) base voided label film or a multilayered destructive label film having printable matt coated surface at front side and corona treated white BOPP surface on the back side for various applications.
[0043] According to a preferred aspect of the present invention, FIG. 1 illustrates a multi-layered destructive label film comprising, a substrate layer (10) and a matte coating layer (20).
[0044] The substrate layer (10) is a biaxially oriented polypropylene (BOPP) film, and the formulation of the substrate layer (10) comprises
(i) a lower skin layer comprising polypropylene or polyethylene homopolymer or copolymer or combination of both, tercopolymer and antiblock additives,
(ii) a lower tie layer comprising polypropylene homopolymer or copolymer or combination of both, calcium carbonate (CaCO3) and optionally Titanium oxide TiO2,
(iii) a core layer comprising polypropylene homopolymer, calcium carbonate (CaCO3), titanium dioxide (TiO2), antistatic additives and optionally polymer processing aids,
(iv) an upper tie layer comprising polypropylene homopolymer or copolymer or combination of both CaCo3, and
(v) an upper skin layer comprising matt compound, polypropylene copolymer, tercopolymer, antiblock additives and polymer processing aids (PPA).
[0045] In one embodiment, the calcium carbonate masterbatch is added into lower tie layer.
[0046] According to the present invention, the antiblock additives are selected from the group comprising of 10% synthetic silica on PP homo (e.g., HOBLOCK-IO), 10% synthetic silica on heat-seal PP (e.g., SKIBLOCK of Ampacet, BLOCK 102AA), and 5 % organic antiblocking additives in a Terpolymer PP (e.g., BLOCK 2C01A of Highgrade) or combinations thereof.
[0047] According to the present invention, the antistatic additives are selected from the group comprising of migratory antistatic agent on PP carrier (e.g., AT 4130PP), Special agents for films with stable wetting tension after corona or flame treatment and low blooming (e.g., AT 4061 PP of Contstab), Slip & Antistatic blend on PP homo, High Molecular Weight Slip / Long & short term Antistatic blend on PP homo (e.g., COEXAS 2 of Ampacet), 12.6 % antistatic agent in Homo PP (e.g., ASPA 2485 S of Lyondel Basell) or combinations thereof.
[0048] According to the present invention, the polymer processing aids (PPA) are selected from the group comprising of Proprietary Processing aid additive on PP random copolymer carrier (e.g., PROFLOW 2 of Ampacet), 3-3.5 % active Polymer processing aid (e.g., PAMF 905 SC NP of Lyondel Basell, EIN 25005 of 3M PA 00852 PPR of Constab) or combinations thereof.
[0049] According to the present invention, at least one skin layer of the substrate layer (10) having the matt compound is coated with matt coating formulation to produce a matt coating layer (20), where the entire film is known as matt finished multi layered destructive label film or multi-layered destructive label film (100).
[0050] According to a preferred aspect of the present invention, the formulation of the substrate layer (10) comprising the following formulations.
[0051] The lower skin layer comprising polypropylene or polyethylene homopolymer or copolymer or combination of both and antiblock additives, where the percentage of polypropylene or polyethylene homopolymer or copolymer ranges between 30-98%, tercopolymer ranges between 0-30%, and the antiblock additives range between 1-10%.
[0052] The optional lower tie layer comprising polypropylene homopolymer or copolymer or combination of both and calcium carbonate (CaCO3), where the percentage of polypropylene homopolymer ranges between 20-100% and particularly 60-100%, and Calcium carbonate master batch ranges between 0-30%. In another embodiment, the tie layer is voided layer, where the formulation of the ingredients ranges between 20-100% of polypropylene homopolymer, 0-30% of calcium carbonate masterbatch and 0-10% of Titanium dioxide masterbatch.
[0053] The core layer comprising polypropylene homopolymer, calcium carbonate (CaCO3), titanium dioxide (TiO2) and antistatic additives, where the percentage of PP Homopolymer ranges between 20-80%, CaCO3 Masterbatch ranges between 5-30%, Tio2 Masterbatch ranges between 1-10%, Antistatic agent ranges between 0-3% and PPA ranges between 0-2%, according to one embodiment of the present invention. In another embodiment, the core layer comprising PP Homopolymer ranges between 20-80%, CaCO3 Masterbatch ranges between 5-30%, Tio2 Masterbatch ranges between 1-10%, and antistatic agent ranges between 0-3%.
[0054] The optional upper tie layer comprising polypropylene homopolymer or copolymer or combination of both, where the percentage of polypropylene homopolymer ranges between 20-100% and calcium carbonate master batch ranges between 0-40%.
[0055] The upper skin layer comprising matt compound, polypropylene copolymer, antiblock additives and polymer processing aids (PPA), where the percentage of matt Compound ranges between 5-50%, PP Copolymer ranges between 1-60%, Tercopolymer ranges between 0-20%, Antiblock ranges between 0-5% and PPA ranging between 0-5%.
[0056] According to another exemplary embodiment of the present invention, a multi-layered destructive label biaxially oriented polypropylene (BOPP) film comprises, a substrate layer and a matte coating layer. the substrate layer comprising upper and lower skin layers, optional upper and lower tie layers and a core layer. The matt coating layer is disposed over upper skin layer of the substrate layer having a matt compound and the lower skin layer is corona treated layer. In one embodiment, the matt coating layer is disposed on the corona treated upper skin layer of the substrate layer. In another embodiment, the matt coating layer is directly disposed on the non-corona treated upper skin layer of the substrate layer.
[0057] According to the present invention, the matt coating formulation in added in terms of (W/W) comprising 35-50% of water based polymeric binder, 35-50% of powder filler or combination of fillers, 1-10% of powdered titanium dioxide (TiO2) and/or aluminium hydroxide [Al(OH)(3)] , 0.1-1% of dispersing agent and 0.5 to 4 % cross linker.
[0058] In one embodiment, the water based polymeric binder is in latex emulsion. In another embodiment, the water based polymeric binder is in aqueous form.
[0059] The binder is selected from the group comprising of vinyl acetate polymer or copolymer, acrylic polymer or copolymer, styrene acrylic copolymer, styrene butadiene copolymer, polyurethane dispersion, hybrid acrylic-polyurethane dispersion or combinations thereof.
[0060] According to the present invention, the filler comprising of calcium carbonate (CaCO3), synthetic silica, aluminium silicate, or combinations thereof. In one embodiment, the filler is in solid form. In another embodiment, the filler is in liquid form. In yet another embodiment, the filler is in powdered form.
[0061] In one embodiment, the matt coating formulation comprising titanium dioxide (TiO2) and aluminium hydroxide [Al(OH)(3)] in the range between 1 to 10 (w/w). In another embodiment, the matt coating formulation comprising titanium dioxide in the range between 1-10% (W/W). In yet another embodiment, the matt coating formulation comprising aluminium hydroxide in the range between 1-10% (W/W).
[0062] According to the present invention, the cross linker is selected from the group comprising of aziridine, isocyanate, polyamine and other cross linkers that are known well in the prior art.
[0063] According to the present invention, the dispersing agents are one or more selected from the group comprising of block copolymer, anionic electrolytes, a high molecular weight block copolymer with pigment affinic groups (e.g., DISPERBYK 190), a structured acrylate copolymer with pigment affinic groups (e.g., DISPERBYK 2010 from BYK), anionic electrolyte, 35 % active dispersing agent (e.g., DISPEX AA 4144 EB of BASF) or combinations thereof.
[0064] According to the present invention, the substrate layer having at least one skin layer, is treated with surface treatment such as corona treatment. The matt coating formulation is applied by either offline or online coating techniques, but offline coating is highly preferred to produce matt coating layer. In one preferable embodiment, at least one skin layer of the substrate layer is first treated with corona treatment and then applied with matt coating. In another embodiment, at least one skin layer of the substrate layer is directly applied with matt coating.
[0065] According to one preferred embodiment of the present invention, the substrate layer (10) having at least one skin layer that lacks matt compound is treated with surface treatment such as corona treatment.
[0066] According to one embodiment of the present invention, the at least one layer of the film is a void layer.
[0067] According to a preferred embodiment of the present invention, the core layer is a void layer. According to one embodiment, the at least one tie layer is voided. The proportion of voids present in the multi-layered destructive label film corresponds to the desired low substrate layer density and internal cohesive strength. The formulating agents like fillers, rubbers, antioxidants, lubricants, antistatic agents, and other additives may be included in the film, as is conventional in the synthetic paper art. According to the present invention, the multi layered BOPP is a five layered or three-layered structure.
[0068] According to one embodiment the present invention, the multi-layered BOPP substrate is a five layered substrate structure having both upper and lower tie layers. According to another embodiment of the present invention, the multi-layered BOPP substrate is a three-layered substrate structure lacking both upper and lower tie layers.
[0069] According to the present invention, the thickness of the upper skin layer ranges between 1 to 5% of total film substrate.
[0070] According to the present invention, the thickness of the upper tie layer ranges between 3 to 10%of total film substrate.
[0071] According to the present invention, the thickness of the core layer ranges between 60 to 90 % of total film substrate.
[0072] According to the present invention, the thickness of the lower tie layer ranges between 3 to 10% of total film substrate.
[0073] According to the present invention, the thickness of the lower skin layer ranges between 1 to 5% of total film substrate.
[0074] According to the present invention, the thickness of the matt coating layer ranges between 1-10 micron.
[0075] According to the present invention, the overall thickness of the multi-layered destructive label film ranges between 70-90 micron.
[0076] According to the present invention, the multi-layered destructive label BOPP film manufactured from any method having a voided core layer, one or more skin layers and one or more tie layers (voided). The overall composition of these layers comprising a graded polypropylene, polyethylene, copolymer of polypropylene and terpolymer, antistatic additive, slip additive and antiblock additives. In one embodiment, the BOPP film substrate is a three-layered film having an upper skin layer, a core layer and a lower skin layer. In another embodiment, the BOPP film substrate is a five-layered structure having an upper skin layer, an upper tie layer, a core layer, a lower tie layer and a lower skin layer such that each skin layer sandwiches the core layer sandwiched between the tie layers from either side.
[0077] The composition of the respective layers may be the same or different. For instance, the substrate layer may comprise one, three, or five or more layers and typical multi-layer structures may be of the ABA, ABC, ABCDE. ADCEB, ADCBE or ABCBA type. According to one exemplary embodiment, the FIG. 2 illustrates a schematic cross-sectional view of a substrate layer (10) having five layered structure A, B, C, D, and E.
[0078] According to one embodiment of the invention, the composition of the core layer, one or more skin layer(s) and optionally one or more tie layer(s) is same. According to another embodiment of the present invention, the composition of the core layer, one or more skin layer(s) and optionally one or more tie layer(s) are different. The layers of the BOPP film comprise homopolymers, copolymers, terpolymers and/or combinations thereof. In one embodiment, the different layers of the BOPP film are made up of different polymers like polyethylene, polypropylene, nylon, EVOH, PVOH, PET, copolymers, block co polymers etc.
[0079] According to the present invention, the core layer, one or more skin layer(s) and one or more tie layer(s) further comprise additives such as, but not limited to, antiblock additive, slip additives, antistatic additives and/or combinations thereof. These layers additionally may contain organic and inorganic fillers.
[0080] According to the present invention, the density of the multi-layered destructive label film having matt coating layer on one side and corona treated on another side having density ranges between 0.6-0.75 g cm-3. The density of the multilayer coextruded voided destructive label BOPP film is not more than 0.7 and the layer construction reveals any attempt of tampering by leaving the residue/portion through thickness behind on the substrate where it is applied.
[0081] According to another aspect of the present invention, the substrate layer of the multi layered destructive label film of the present invention can be manufactured by the any of the known methods like biaxial orientation methods, extrusion methods, co-extrusion methods, voiding methods.
[0082] Further, the coating of matte coating is applied on to at least one surface of the skin layer of the substrate layer by gravure technique or microgravure technique. The matte coating composition generally include polymer, homopolymer or copolymer along with additives like fillers, white pigments, dispersing agents, and cross linkers. Then film is dried with the help of dryer or hot air oven to remove the moisture and water content in the applied coating. In one embodiment, the matt coating on substrate layer is performed by inline coating method. In another embodiment, the matt coating on substrate layer is performed by offline coating method.
[0083] Preferably, the multi-layered destructive label film comprising a coextruded BOPP film having voided core layer present in between two skin layers and tie layers. The density of the coextruded voided BOPP is not more than 0.7. Further, the matte coating is coated on at least one skin layer having the matte compound in its composition.
[0084] According to another aspect of the present invention, it is provided a method of manufacturing of a multilayered destructive label film, comprising the steps of (a) manufacturing of biaxially oriented polypropylene film substrate by stretching the substrate film in both longitudinal and transverse directions (b) slitting the BOPP film substrate; and (c) applying matt coating formulation (otherwise known as water-based coating) on at least one surface of the BOPP substrate. Further, another side of the BOPP film substrate is surface treated (i.e., corona treatment).
[0085] In one embodiment, the matt coating is applied to one side of the substrate film having a matt compound. The other side of the substrate film is subjected to corona treatment.
[0086] In one embodiment, the matt coating is applied to one side of the substrate film having a matt compound, where the one of the substrate films having matt compound is corona treated. In another embodiment, the matt coating is applied to one side of the skin layer of the substrate film having a matt compound directly.
[0087] The multi-layered destructive label film of the present invention is explained in more detail with the help of following Trials/examples. Examples/Trials are provided for illustrative purposes only and are not intended to limit the scope of the invention.
[0088] Examples
[0089] A label material comprising an extruded five layered BOPP film with corona treated on one side as an adhesive receptive layer and printable matt coating on another side.
[0090] Example 1
Film Layer Components Percentage Layer Thickness
Lower Skin layer (B) - PP or PE homopolymer or Copolymer 30-98% 1 to 5%
- Tercopolymer 0-30%
- Antiblock 1-10%
Lower Tie layer (E) - PP Homopolymer 20-85% 3 to10%
- CaCO3 Masterbatch 5-30%
- Tio2 Masterbatch 0-10%
Core layer (C) - PP Homopolymer 20-80% 60 to 90%
- CaCO3 Masterbatch 5-30%
- Tio2 Masterbatch 1-10%
- Antistatic 0-3%
- PPA 0-2%
Upper Tie layer (D) - PP Homopolymer 60-100% 3 to 10%
- CaCO3 Masterbatch 0-15%
Upper Skin layer (A) - Matt Compound 5-50% 1 to 5%
- PP Copolymer 1-60%
- Tercopolymer 0-15%
- Antiblock 0-5%
- PPA 0-5%
[0091] Example 2
Film Layer Components Percentage Thickness
Lower Skin layer (B) - PP or PE homopolymer or Copolymer 30-98% 1 to 5%
- Tercopolymer 0-30%
- Antiblock 1-10%
Lower Tie layer (E) - PP Homopolymer 60-100% 3 to10%
- CaCO3 Masterbatch 0-15%
Core layer (C) - PP Homopolymer 20-80% 60 to 90%
- CaCO3 Masterbatch 5-30%
- Tio2 Masterbatch 1-10%
- Antistatic 0-3%
-PPA 0-2%
Upper Tie layer (D) - PP Homopolymer 20-80% 3 to 10%
- CaCO3 Masterbatch 0-40%
Upper Skin layer (A) - Matt Compound 5-50% 1 to 5%
- PP Copolymer 1-50%
- Tercopolymer 0-20%
- Antiblock 0-5%
- PPA 0-5%
[0092] Example 3
Film Layer Components Percentage Thickness
Lower Skin layer (B) - PP or PE homopolymer or Copolymer 30-98% 1 to 5%
- Tercopolymer 0-30%
- Antiblock 1-10%
Lower Tie layer (E) - PP Homopolymer 60-100% 3 to10%
- CaCO3 Masterbatch 0-15%
Core layer (C) - PP Homopolymer 20-80% 60 to 90%
- CaCO3 Masterbatch 5-30%
- Tio2 Masterbatch 1-10%
- Antistatic 0-3%
Upper Tie layer (D) - PP Homopolymer 20-100% 3 to 10%
- CaCO3 Masterbatch 0-40%
Upper Skin layer (A) - Matt Compound 5-50% 1 to 5%
- PP Copolymer 1-50%
- Tercopolymer 0-20%
- Antiblock 0-5%
- PPA 0-5%
[0093] The BOPP substrate layer is produced according to any known methods as disclosed in the prior art using different percentages of the components/ingredients as disclosed in example 1 to 3. A water-based matt coating is applied on at least one skin layer surface of the substrate layer having matt compound produced according to example 1 to 3 to manufacture the final multi layered BOPP film according to the present invention with gravure method. The dry weight coating layer was maintained between 1 to 7 microns. A typical composition of matt coating formulation is as follows.
Sr. No Formulation- Matt coating Dry weight %
1 Styrene acrylic copolymer 35-50
2 Calcium carbonate filler 35-50
3 White pigment TiO2 5-10
4 Dispersing agent 0.2
5 Cross linker 0.5-4
[0094] The properties of multi layered BOPP film having matt coating (otherwise known as coated label polymeric sheet) are given in table 1 as follows.
Table 1
PROPERTIES UNIT TEST METHOD VALUE
Tensile Strength (MD) (TD) kgf/cm² ASTM D 882 500-700
1400-1700
Elongation (MD)
(TD) % ASTM D 882 120-160
20-40
Modulus of Elasticity (MD)
(TD) kgf/cm² ASTM D 882 12000-17000
25000-30000
[0095] There should be clear delamination or breaking of the label in parts through thickness on peel off. It is measured by the tape pull test mentioned in prior art US7270874, which involves measuring of force required to peel off an adhesive tape adhered to the labelling material. The effect of the removal of the tape on the integrity of the labelling material is also observed. The test may conveniently be carried out using 25 mm wide transparent tape of the kind supplied for domestic and office use. The tape is pressed into contact with the surface of the labelling material by hand (normally in the machine direction, if this is known) and the resulting bond is reinforced by running a 1 kg roller over the tape. The tape is then peeled away from the labelling material using “universal tester Machine” at a defined speed (typically 20 or 250mm min-l). The average force required for this over the duration of the peeling operation is recorded and provides a measure of the cohesive strength of the material under test. Average values for this peeling force should be lesser than 500 gram.force/25 mm. It is preferable to have lesser values of cohesive strength, to enhance the performance.
[0096] The typical Peel off performance of the multi layered BOPP film is evaluated by peel test using 25 mm transparent tape as described before in Patent US7270874. With this test, the cohesive strength between film layer preferably lower skin and lower tie layer was measured and the results were given in the table 2.
Table 2

Peel Speed
mm/min Average surface cohesive strength
(gmf/25mm)
20 235
250 295
[0097] Cohesive strength: For tampered film, lower the cohesive strength-better is the performance. It indicates easy peel off even under low pressure. Ideally, the cohesive strength of the film of the present invention should be lesser than 500gmf/25m, and more particularly 300 gmf/25m. The multi-layered destructive label film having better average cohesive strength than that of the traditional film, where the cohesive strength ranges between 235-295 gmf/25m.
[0098] Thus, the application and advantages of the present invention including, but not limited to, are a novel, destructive label film that finds its application in various fields like tamper evident labels, security label film, anti-counterfeiting film, forgery preventing film, and peel off film.
[0099] Further, the multi-layered destructive label film is cost-effective in nature when compared with the conventional destructive label films. Conventionally, different polymeric films are laminated together to form a single film, but according to the present invention, single film with mono-material such as PE or PP is provided for the same purpose. This makes the invention a cost-effective in nature, as the present invention does not involve the usage of multiple films with different polymer formulation and its cost of lamination together. Thus, this invention is cost-effective and includes lesser manufacturing steps and time.
[00100] Moreover, the multi-layered destructive label film of the present invention, can be recyclable in nature post use. Conventionally non-recyclable films are manufactured using lamination of multiple polymeric films such as polypropylene (PP) and polyethylene terephthalate (PET). The presence of the two dissimilar polymers is difficult to recycle. The multi-layered destructive label film of the present invention is made of only one type of polymer PP or PE, which is easy to recycle. This makes the film of invention an environmentally safe product, as the film does not pollute the environment unlike the traditional non-recyclable films.
[00101] Although the invention has been described with regard to its embodiments, specific embodiments, and various examples, which constitute the best mode presently known to the inventors, it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention. The scope of the claims should not be limited by the preferred embodiments set forth in the examples but should be given the broadest interpretation consistent with the description as a whole. All changes that come with meaning and range of equivalency of the claims are to be embraced within their scope.
REFERENCE NUMERALS
[00102] 100 - Multi-layered BOPP Film (or) multi-layered destructive label film
[00103] 10 – BOPP substrate layer
[00104] 20 – Matt coating layer
,CLAIMS:1. A multi-layered destructive label film (100) comprising:
a. a substrate layer (10) comprises a multi-layered, voided, biaxially oriented polypropylene film having a core layer, an upper and lower skin layer, and an upper and lower tie layer; wherein the lower skin layer is corona treated layer, and
b. matt coating layer (20) disposed on the upper skin layer of the substrate layer (10) having a matt compound.
2. The multi-layered destructive label film (100) as claimed in claim 1, wherein the formulation of the substrate layer (10) comprising:
a. the upper skin layer comprises 5-50 % matt compound, 1-60% copolymer, 0-20% tercopolymer, 0-5% antiblock additives and 0-5% polymer processing aids;
b. the upper tie layer comprises 20-100% of homo polypropylene, 0-40% calcium carbonate masterbatch;
c. the core layer comprises 20-100 % of homo polypropylene, 5-30% of CaCO3 masterbatch, 1-10% titanium dioxide, 0-3% antistatic additives and 0-2% polymer processing aids;
d. the lower tie layer comprises 20-100 % of homo polypropylene, 0-30% of CaCO3 masterbatch and 0-10% of titanium dioxide; and
e. the lower skin layer comprises 30-98% of homo polypropylene or copolymer and 0-30% of tercopolymer and 1-10% antiblock additives;
- wherein the lower skin layer is corona treated and the upper skin layer is later offline coated with printable water based matt coating,
- wherein at least one of the layers of the substrate layer (10) is voided.
3. The multi-layered destructive label film (100) as claimed in claim 2, wherein the thickness of the upper skin layer ranges between 1 to 5 % of total film substrate, the thickness of the upper tie layer ranges between 3 to 10% of total film substrate, the thickness of the core layer ranges between 60 to 90 % of total film substrate, the thickness of the lower tie layer ranges between 3 to 10% of total film substrate, and the thickness of the lower skin layer ranges between 1 to 5% of total film substrate

4. The multi-layered destructive label film (100) as claimed in claim 1, wherein the formulation of matt coating layer (20) comprises 35-50% water based polymeric binder, 35-50% powder filler or combination of fillers, 1-10% powdered titanium dioxide (TiO2) and/or aluminium hydroxide [Al(OH)(3)], 0.1-1% of dispersing agent, and 0.5 to 4 % cross linker.

5. The multi-layered destructive label film (100) as claimed in claim 1, wherein the thickness of the matt coating layer (20) ranges between 1-10 micron and the overall thickness of the multilayered film (100) ranges between 70-90 micron.

6. The multi-layered film (100) as claimed in claim 1 having density ranges between 0.6-0.75 g cm-3.

7. The multi-layered destructive label film (100) as claimed in claim 1 having cohesive strength less than 500 gmf/25m.

8. A method of manufacturing of a multilayered destructive label film, comprising the steps of
a. manufacturing a biaxially oriented polypropylene (BOPP) film substrate by stretching the substrate film in both longitudinal and transverse directions;
b. slitting the manufactured BOPP film substrate; and
c. applying water-based matt coating formulation on at least one skin layer of the BOPP film substrate comprising a matt compound and subjecting another side of the skin layer of the BOPP film substrate, that is free from matt compound to a surface treatment.