METALLIZED LAMINATE FILM FOR IN-MOLD LABELS AND PRINTED IN-MOLD LABELS FORMED FROM SUCH FILM

Abstract

A multilayer, metallized, laminate film employed to form in-mold labels, includes first and second multilayer structures adhesively bonded together. The first multilayer structure includes a polymer core layer and first and second outer polymer layers on opposed sides of the core layer. The first outer polymer layer includes a metal layer thereon, and the second polymer layer having an outer matte surface that is adapted, in the in-mold label formed from laminate film, to engage and bond to a molded article. The second multilayer structure is a clear structure including a core layer and first and second outer polymer layers on opposed sides of the core layer. The bonded interface of the first and second multilayer structures is free of any printed indicia or other graphics. Preferably both outer surfaces of the film are bottom outer layers and include matte surfaces.

A label in accordance with this invention is formed from the above-described laminate film by printing an outer surface of the film either before or after the film/label is printed.

A method of applying a printed molded label formed from the laminate film of this invention to a molded article during the molding operation also forms a part of this invention.

Claims

1. A multilayer, metallized, laminate film employed to form in-mold labels, said laminate film including first and second extruded multilayer structures, said first and second extruded multilayer structures each including a polymer core layer and first and second outer polymer layers on opposed sides of the core layer and being thinner than said core layer, each of said first and second outer polymer layers of each multilayer structure including an outer surface; a thin coating of a metal layer on the outer surface of an outer layer of one of said first and second extruded multilayer structures; an adhesive layer bonding the first and second extruded multilayer structures together through said metal layer to form a bonded interface, said bonded interface being free of printed indicia providing any product information; at least one of said multilayer structures being clear for providing visibility through the thickness thereof to permit viewing of at least a portion of the coating of the metal layer, and printed indicia providing product information on a surface of an outer polymer layer constituting an outer surface of the laminate film.

2. The multilayer, metallized, laminate film of claim 1, wherein said adhesive layer bonds said metal layer to the outer surface of an outer layer on the other of said first and second extruded multilayer structures.

3. The multilayer, metallized, laminate film of claim 1, where both said first and second multilayer structures are clear.

4. The multilayer, metallized, laminate film of claim 1, wherein one of said multilayer structures is opaque.

5. The multilayer, metallized, laminate film of claim 1, wherein said core layer and first and second outer polymer layers of each of said first and second multilayer structures are coextruded.

6. The multilayer, metallized, laminate film of claim 1, wherein at least one of the outer surfaces of said film is a matte surface.

7. The multilayer, metallized, laminate film of claim 1, wherein both outer surfaces of said film are matte surfaces.

8. The multilayer, metallized, laminate film of claim 1, wherein the composition of the layers in the first multilayer structure being the same as corresponding layers in the second multilayer structure.

9. The multilayer, metallized, laminate film of claim 1, wherein said first and second multilayer structures each are coextruded on the same extrusion line and are formed with substantially the same settings on said line.

10. The multilayers, metallized, laminate film of claim 1, wherein each of said extruded multilayer structure is biaxially oriented.

11. The multilayer, metallized, laminate film of claim 1, wherein the core layer of each of said multilayer structures has a thickness in the range of 25-27 microns, the top layer of each of said multilayer structures has a thickness of 0.5-2 microns and the bottom layer of each of said multilayer structures has a thickness of 1.5-5 microns.

12. A multilayer, metallized, laminate film including first and second extruded multilayer structures, said first and second extruded multilayer structures each including a polymer core layer and first and second outer polymer layers on opposed sides of the core layer and being thinner than said core layer, each of said first and second outer polymer layers of each multilayer structure including an outer surface; said first and second multilayer structures being attached to each other through a bonded interface free of any printed indicia providing product information; said bonded interface including a thin metal layer on an outer surface of said first extruded multilayer structures and an adhesive layer bonding the metal layer to the second extruded multilayer structure; at least one of said first and second multilayer structures being clear for providing visibility through the thickness thereof to permit viewing of at least a portion of the coating of the metal layer, and printed indicia providing product information on a surface of an outer polymer layer constituting an outer surface of the laminate film.

13. An in-mold label including extruded first and second multilayer structures, said first and second extruded multilayer structures each including a polymer core layer and first and second outer polymer layers on opposed sides of the core layer and being thinner than said core layer, each of said first and second outer polymer layers of each multilayer structure including an outer surface; a thin coating of a metal layer on the outer surface of an outer layer of one of said first and second extruded multilayer structures; an adhesive layer bonding said first and second multilayer structures together through said metal layer for providing a bonded interface, said bonded interface being free of printed indicia providing product information, at least one of said multilayer structures being clear for providing visibility through the thickness thereof to permit viewing of at least a portion of the coating of the metal layer, and printed indicia providing product information on a surface of an outer polymer layer constituting an outer surface of the in-mold label.

14. The in-mold label of claim 13, said adhesive layer bonding the metal layer to an outer surface of the other multilayer structure.

15. An in-mold label including extruded first and second multilayer structures, said first and second extruded multilayer structures each including a polymer core layer and first and second outer polymer layers on opposed sides of the core layer and being thinner than said core layer, each of said first and second outer polymer layers of each multilayer structure including an outer surface; said first and second multilayer structures being attached to each other through a bonded interface free of printed indicia including product information; said bonded interface including a thin metal layer on an outer surface of said first extruded multilayer structure and an adhesive layer bonding the first and second extruded multilayer structures together through said metal layer; at least one of said first and second multilayer structures being clear for providing visibility through the thickness thereof to permit viewing of at least a portion of the coating of the metal layer, and printed indicia including product information on a surface of an outer polymer layer constituting an outer surface of the in-mold label.

16. The in-mold label of claim 13, wherein an outer surface of at least one outer polymer layer of the in-mold label is a matte surface.

17. The in-mold label of claim 13, wherein both outer surfaces of the in-mold label are matte surfaces.

18. The in-mold label of claim 13, wherein the printed indicia is on an outer surface adapted to engage an inner mold surface during the formation of a molded article.

19. The in-mold label of claim 13, wherein a clear, protective layer is applied over the printed indicia and engages an inner mold surface during the formation of a molded article.

20. The in-mold label of claim 13, wherein the composition of the layers in the first multilayer structure being the same as corresponding layers in the second multilayer structure.

21. The in-mold label of claim 13, wherein said first and second multilayer structures each are formed from multilayer films coextruded on the same extrusion line with substantially the same settings on said line.

22. The in-mold label of claim 13, wherein each of said extruded multilayer structures is biaxially oriented.

23. The in-mold label of claim 13, wherein the core layer of each of said multilayer structures has a thickness in the range of 25-27 microns, the top layer of each of said multilayer structures has a thickness of 0.5-2 microns and the bottom layer of each of said multilayer structures has a thickness of 1.5-5 microns.

24. A method of applying the in-mold label of claim 13 to a molded article during the molding operation including the steps inserting the in-mold label in a mold with the printed surface of the in-mold label facing and contiguous to a surface of the mold defining a cavity in which the article is to be molded and with the opposed outer surface of the in-mold label facing the mold cavity of the mold and molding an article into engagement with surfaces defining the mold cavity and into bonding engagement with the in-mold label.

25. The method of claim 24, wherein the molded article is an injection molded article.

26. The method of claim 24, wherein multilayer structures contiguous to the surface of the mold is the clear structure.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0028] The invention may be more fully understood with reference to the accompanying drawing, which is a schematic representation of one embodiment of this invention showing the construction of two multi-layer structures adhesively bonded together to form a multi-layer, metallized, laminate film of this invention that is employed to form in-mold labels in accordance with this invention; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0029] A multi-layer, metallized, laminate film employed to form in-mold labels in accordance with the most preferred embodiment of this invention is indicated at 10 in the FIGURE. This laminate film includes first and second multi-layer structures 12 and 14 that are adhesively bonded together as will be described in greater detail hereinafter.

[0030] The preferred thickness of the film 10 is in the range of 40-120 microns. For small and medium size containers up to about 4 liters the preferred thickness range is 40-80 microns; more preferably in the range of 55-70 microns and most preferably about 60 microns. However, in the molding of larger containers such as plastic pails that can have up to a 20 liter capacity, the upper limit preferably is on the order of 100 microns, but if necessary can be extended to 120 microns. Also, it should be understood that the thickness of the film generally is varied or changed by adjusting the thickness of the core layer, without materially changing the thickness of the other layers in the laminate.

[0031] In accordance with this invention, as will be explained in greater detail hereinafter, top outer layer 18 of multi-layer structure 14 is adhesively secured to metal layer 22 formed on the top outer layer 18 of multi-layer structure 12. Most preferably the two multi-layer structures are formed on the same extrusion line from the same components; and preferably from the same production run. Thus, if the extruded film tends to curl in a particular direction, bonding the top outer layer 18 of the second multi-layer structure 14 to the metal layer 22 applied to the top outer layer 18 of the first multi-layer structure will tend to minimize or eliminate the curl problem. As noted earlier, a curl problem can be particularly significant when the film is cut and stacked into individual sheets to be directed into a sheet fed printer.

[0032] Referring to the FIGURE, the multi-layer structure 12 is a metallized structure including a core layer 16 and opposed first and second polymer layers 18 and 20 co-extruded with said core layer in a conventional manner; preferably in a tenter machine. In the most preferred embodiment of this invention the co-extruded laminate is biaxially oriented in the tenter machine in a manner that is well known to individuals skilled in the art.

[0033] In one commercial tenter machine an extrusion head includes five (5) extrusion slots and the polymers extruded through the central three slots are identical to form the core layer. 16. The opposed first and second polymer layers 18 and 20 are formed through the two outer slots.

[0034] After co-extrusion a very thin metal layer 22 is deposited on top polymer layer 18 by any well-known application method such as by vapor deposition; preferably to a thickness of less than 0.1 microns. In the preferred embodiment of this invention the metal layer 22 is aluminum, however, any well-known metal or metal oxide disclosed in the prior art for use in a metallized film structure may be employed in this invention.

[0035] Most preferably the thickness of the metallized laminate structure 12 is in the range of 20 to 50 microns; more preferably in the range of 25-35 microns and most preferably approximately 30 microns. The core layer 16 of the laminated structure 12 preferably is formed predominantly of polypropylene homopolymer or of a copolymer of propylene with another olefin in an amount that does not negatively impact the properties that make polypropylene desirable for the core layer. Representative copolymers utilized in this invention generally are referred to as mini random copolymers and include less than 2% polyethylene in the copolymer and more preferably less than 1%.

[0036] Unless the context indicates otherwise, the reference herein to polypropylene is intended to indicate either an isotactic homopolymer of propylene or a copolymer of propylene with an {acute over ()}-olefin, said {acute over ()}-olefin being present in an amount that does not negatively impact the properties that make propylene desirable for use in forming the core layer.

[0037] In a representative embodiment of this invention the core layer 16 is formed from about 98.3%-98.9%, by weight, based on the weight of the core layer, of a propylene homopolymer sold by Lyondellbasell in Geelong, Victoria, Australia under the designation Lyondellbasell HP 516 J, and about 1.1%-1.7%, based on the weight of the core layer, of a slip/antistatic masterbatch including erucamide and ethoxylated amine; sold under the designation Ampacet Grade 50860K, manufactured by Ampacet in Rayong 21140 Thailand. This Ampacet masterbatch includes, by weight, 4% erucamide, 4% ethoxylated amine and 8% glycerol mono stearate in 84% polypropylene homopolymer. In a representative embodiment wherein the label is used in the molding of medium size containers the core layer thickness preferably is in the range of 25-27 microns thick. However, the thickness can be varied without departing from the spirit and scope of the broadest aspects of this invention, and in the molding of large containers the thickness of the core layer will be greater than 26.2 microns.

[0038] The outer, top polymer layer 18 to which the metal layer 22 subsequently is to be applied is formed of a propylene/ethylene copolymer wherein the ethylene content is present in a weight percent of about 4%. A representative C2C3 copolymer employed in this invention is supplied under the designation Ineos KS414 by Ineos Olefins and Polymers Europe, located in Brussels Belgium. In the preferred embodiment of this invention the outer surface of layer 18 is oxidatively treated to enhance metal adhesion to that surface; preferably by plasma treatment in a gaseous environment of oxygen and argon. Preferably the polymer layer 18 has a thickness in the range of 0.5 to 2.0 microns and more preferably is about 0.8-1.0 microns. However, the thickness can be varied without departing from the spirit and scope of the broadest aspects of this invention.

[0039] The opposed outer polymer layer 20 preferably includes, based upon the weight of that polymer layer, 75%, by weight, of a matte masterbatch blended with 25%, by weight of a C2C3 copolymer, such as the Ineos KS414 copolymer described earlier herein. A preferred matte masterbatch is sold under the designation Tosaf MTO523DP by Tosaf Compounds Ltd of Kfar-Yona, Israel. It is believed that this latter masterbatch consists of 50%, by weight of a C2C3 copolymer and 50% by weight of a high density polyethylene. Specifically, this is a blend of incompatible polymers that form different phases when mixed and thereby provide the matte surface or finish. Preferably the thickness of the polymer layer 20 is in the range of 1.5 to 5.0 microns and more preferably is about 3 microns. However, the thickness can be varied without departing from the spirit and scope of the broadest aspects of this invention.

[0040] In accordance with the preferred embodiments of this invention, the multi-layer laminate 14 is secured to the multi-layer laminate 12 by any suitable adhesive.

[0041] As noted earlier, in accordance with the most preferred embodiment of this invention the multi-layer laminate 14 is of an identical construction to the multi-layer structure 12, with the individual layers of the structure 14 being identified by the same numerals as the corresponding layers of the structure 12, but with a prime () suffix. In particular, the thickness ranges and compositions specified for the layers 16, 18, 20 and 22 are the same for the layers 16, 18, 20 and 22 of the laminate structure 14. The only difference between laminate 12 and 14 is that it may not be necessary to oxidatively treat the top outer layer 18 of laminate 14 since it will be adhesively secured to the metal layer 22, as opposed to having a metal layer deposited thereon, as is the case with top outer layer 18 of the laminate 12. However, oxidatively treating each of the outer surfaces in both of the laminates 12, 14 is within the scope of this invention.

[0042] In the most preferred construction, it should be apparent that the bottom outer surfaces 20, 20 are the outer surfaces of the multi-laminate structure 10; both having matte surfaces. It has been determined that a matte surface can be very desirable for receiving printing inks thereon, as well as for providing a desired surface roughness for attachment to an article in an in-mold labeling operation.

[0043] In accordance with this invention the printed labels are attached to an article in an in-mold labeling operation by positioning an in-mold label of this invention in a mold with the printed surface facing and contiguous to the mold surface and a matte surface facing and communicating with the mold cavity in which a molded article is to be formed. The article is then molded in the cavity (e.g., injection molded) to both form the article and attach the in-mold label to the article. In the most preferred embodiment the opposed outer surface is a matte surface provided with printed indicia thereon.

[0044] As noted earlier, in the most preferred embodiments each of the laminates 12, 14 are formed of the same construction; preferably from the same production run on the same extrusion device. Also as noted earlier, commercially available tenter equipment used by applicant includes a five (5) slot extrusion die with the same composition being extruded through the central three slots to essentially form a uniform core layer. It should be understood that in accordance with this invention a three slot extrusion die could be employed to form the central core and the outer skin layers, respectively.

[0045] The presently preferred formulation of each of the laminates 12, 14 is a follows:

[0046] Core layers 16, 16 (formed through 3 of the slots)about 98.9%, by weight, based on the weight of the core layer, of a propylene homopolymer sold by Lyondellbasell in Geelong, Victoria, Australia under the designation Lyondellbasell HP 516 J, and about 1.1%, by weight, based on the weight of the core layer, of a slip/antistatic masterbatch including erucamide and ethoxylated amine; sold under the designation Ampacet Grade 50860K, manufactured by Ampacet in Rayong 21140 Thailand. As noted earlier, this Ampacet masterbatch includes, by weight, 4% erucamide, 4% ethoxylated amine and 8% glycerol mono stearate in 84% polypropylene homopolymer.

[0047] Top outer layers 18, 18propylene/ethylene copolymer wherein the ethylene content is present in a weight percent of about 4%. A representative C2C3 copolymer employed in this invention is supplied under the designation Ineos KS414 by Ineos Olefins and Polymers Europe, located in Brussels Belgium and identified earlier in this application

[0048] Bottom outer layers 20, 2075%, by weight, of a matte masterbatch blended with 25%, by weight of a C2C3 copolymer, such as the Ineos KS414 copolymer described earlier herein. A preferred matte masterbatch is sold under the designation Tosaf MTO523DP by Tosaf Compounds Ltd of Kfar-Yona, Israel.

[0049] In the most preferred embodiment of this invention the thickness of each of the core layers 16, 16 is 26 microns; the thickness of each of the top layers 18, 18 is 1 micron and the thickness of each of the bottom layers 20, 20 is 3 microns.

[0050] In the preferred construction each of the outer surfaces of each of the laminates 12, 14 are oxidatively treated; preferably by corona treatment. The treatment makes the surfaces more receptive to printing, metallizing and also adhesively bonding the laminates together to form the film 100.

[0051] As noted earlier, in the most preferred embodiment of this invention the laminates 12, 14 preferably are formed on the same extrusion equipment with the same settings; most preferably from the same extrusion run. Therefore, when the top surface 18 of laminate 14 is adhesively bonded to the metal layer 22 adhered to the top surface 18 of the laminate 12 any curling of each of the laminates 12, 14 will be in the same direction, as formed, and when bonded to each other as described above any curl will be in the opposite directions and tend to nullify, or cancel each other.

[0052] The most preferred adhesive for bonding the laminates 12, 14 together is a solventless adhesive and the bonding generally is provided by a contract laminator that acquires the laminates from a film manufacturer, such as Taghleef.

[0053] In addition to curl, another key parameter that needs to be minimized is static. The present formulation, as noted earlier, contains antistatic agents at a carefully controlled quantity which provides antistatic effect without affecting print performance. However, in accordance with this invention additional static controls are provided on the laminator to provide for successful converting by sheet-fed printers. Specifically, an AC static bar was fitted on the laminator; successfully eliminating static charge.

[0054] Post lamination, rolls in accordance with this invention were conditioned for 4-7 days in a temperature controlled environment of 40 C. to enable adhesive to cure. Post cure, the rolls were slit to a desired width, packed and then dispatched to the sheet-fed printer. No additional static control was required during the slitting operation under current set-up, but this may be required if done elsewhere.

[0055] It should be noted that the principal benefits of this invention are in the formation of in-mold labels that are printed with visible indicia on sheet fed printers. It is the requirement of obtaining acceptable printing on the labels through sheet-fed printers that makes curl and antistatic control so important. In addition, providing a matte surface on both the print side and the container engaging surface of the in-mold label enhances both the print quality and the retention of the label to a molded article.

[0056] In accordance with this invention print and bond receptivity are enhanced by the oxidative treatment of the opposed matte surfaces 20, 20; preferably by corona treatment.

[0057] Initial test results show that the application of the in-mold, metallized label 10 of this invention to a molded plastic container improves the barrier of that container to both moisture and oxygen.

[0058] Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention defined in the appended claims. For example, although the multi-layer structures 12, 14 had been described as three layer films, it is to be understood that multi-layer structures having additional layers, such as additional polymer layers, tie layers, etc. are also within the scope of the present invention. In other words, the number of layers in each of the structures does not constitute a limitation on the broadest aspects of this invention.