Patent Publication Number: US-2021178722-A1

Title: Biaxially oriented thermoplastic polymer laminate films for luggage articles and methods of making the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is continuation of U.S. application Ser. No. 16/493,442 filed on Sep. 12, 2019 and entitled “Biaxially Oriented Thermoplastic Polymer Laminate Films For Luggage Articles and Methods of Making the Same” which is the national stage application of International Patent Application No. PCT/EP2018/056586 filed on Mar. 15, 2018 and entitled “Biaxially Oriented Thermoplastic Polymer Laminate Films For Luggage Articles and Method of Making the Same” which claims priority to European Patent Application No. 17161218.7 filed on Mar. 15, 2017 and entitled “Biaxially Oriented Thermoplastic Polymer Laminate Films For Luggage Articles and Method of Making the Same”, the entire contents of which are hereby incorporated by reference herein in their entireties. 
    
    
     TECHNOLOGICAL FIELD 
     The present disclosure generally relates to luggage articles and, in particular, to the use of laminated biaxially oriented thermoplastic polymer films in the construction of the shell structure of a luggage case. 
     BACKGROUND 
     Hard side luggage cases provide durability and support by using formable, relatively hard materials to create the exterior of the case. One drawback of these materials is that they are difficult to manufacture and mold, demonstrating low tolerance of subtle variations in the manufacturing and molding processes. The unforgiving nature of the materials is particularly noticeable when producing deep drawn articles. A luggage shell or case produced from the materials may need to be relatively thick and/or relatively heavy to achieve the desired strength. The materials as well as the manufacturing and molding processes may also be expensive and the processes may be time-consuming. 
     Documents that may be related to the present disclosure in that they include various approaches to materials for luggage articles include EP1763430, GB1386953, U.S. Pat. No. 4,061,817, IN256542 and IN257341. These proposals, however, may be improved. 
     It is therefore desirable to provide an improved material for luggage articles, such as luggage shells, in particular a lightweight durable material, as well as to provide methods of making the material and the luggage article that are relatively easy, fast, forgiving, and inexpensive. 
     SUMMARY 
     According to the present invention there is therefore provided a material for making a luggage shell, a luggage shell constructed of the material, a method of making the material, a method of making the luggage shell and a luggage case including at least one shell constructed of the material, as described below and/or as defined in the accompanying claims. 
     The present disclosure in particular provides an improved plastic laminate material that is lightweight and impact resistant. The material is versatile and amenable to being deep drawn into articles such as luggage shells. A luggage shell constructed of the laminate is lightweight, thin, durable, resistant to deformation, and has exceptional impact resistance during handling. 
     A method of making the plastic laminate is provided that requires relatively little heat and pressure and is relatively fast and inexpensive. A method of making deep drawn articles, such as luggage shells, is provided. The method is relatively easy, fast, and inexpensive. 
     In one example, a luggage shell is formed of a laminate of a plurality of coextruded films. The films include a core of a biaxially oriented thermoplastic polymer and at least one outer layer of a thermoplastic polymer. The outer layer has a thickness of 0.5% to 25% of the thickness of the film. 
     In some examples, the film has a thickness of about 10μm±5%-about 100 μm±5%. 
     In some examples, the core has a thickness of about 10μm±5%-about 100 82 m±5%. 
     In some examples, the outer layer has a thickness of about 0.6 μm±5% to about 2.5 μm±5%. 
     In one example, the outer layer is about 2% to about 7% of the thickness of the film. The outer layer may be less than about 5% of the thickness of the film or may be about 2.5% of the thickness of the film. 
     In another example, at least two adjacent films are oriented in the same direction. 
     In a further example, all films are oriented in the same direction. 
     In one example, the biaxially oriented thermoplastic polymer of the core is biaxially oriented polypropylene. 
     In one example, the outer layer comprises a copolymer of polypropylene and polyethylene. 
     In another example, the outer layer comprises a terpolymer of polypropylene, polyethylene, and polybutene. 
     In some examples, the melting point of the core is higher than a melting point of the outer layer. The melting point may be at least about 10° C. higher than melting point of the outer layer. 
     In some examples, the film is stretched and is stretched to a greater extent in one of a transverse direction and a longitudinal direction than in the other of the transverse direction and the longitudinal direction. 
     In some examples, the film has a tensile strength of about 60 to about 190 MPa in the longitudinal direction. 
     In some examples, the film has a tensile strength of about 150 to about 300 MPa in the transverse direction. 
     In some examples, the film has a stiffness of about 3.5-5 GPa in the transverse direction. 
     In some examples, the film has a stiffness of about 1.5-3 GPa in the longitudinal direction. 
     In some examples, the laminate includes 10 to 50 films. The number of films may be 22 or 23 films. 
     In one example, the thickness of the laminate is about 0.25 mm to about 2.5 mm. The thickness of the laminate may be about 0.5 mm to less or equal to about 1 mm. 
     In some examples, the laminate may include at least one film constructed of a thermoplastic polymer different than the thermoplastic polymer of the core. 
     In some examples, the laminate includes a top layer. The top layer may include biaxially oriented polyester. 
     In some examples, the luggage shell includes a fabric lining layer. The fabric lining layer may include a mesh textile sheet. 
     In one example, a method of making a luggage shell includes providing films, laminating a plurality of films together to form a laminate, and molding the laminate to form a luggage shell. The films have a core of a thermoplastic polymer and an outer layer on each of the top and bottom side of the core. The films are laminated at a temperature of 130° C. or less and a pressure of 10 bar or less, or in some examples less than 10 bar. 
     In one example, the core and the outer layer are coextruded to form the film. 
     In some examples, the film has a thickness of 10 μm±5%-100 μm±5%. 
     In some examples, the core has a thickness of 10 μm±5%-100 μm±5%. 
     In some examples, the outer layer has a thickness of 0.6 μm±5% to 2.5 μm±5%. 
     In some examples, the outer layer has a thickness of 0.5% to 25% of the thickness of the film. The thickness of the outer layer may be 2% to 7% of the thickness of the film. 
     In another example, at least two adjacent films are oriented in the same direction. 
     In a further example, all films are oriented in the same direction. 
     In one example, the biaxially oriented thermoplastic polymer of the core is biaxially oriented polypropylene. 
     In one example, the outer layer comprises a copolymer of polypropylene and polyethylene. 
     In another example, the outer layer comprises a terpolymer of polypropylene, polyethylene, and polybutene. 
     In some examples, the melting point of the core is higher than a melting point of the outer layer. The melting point may be at least 10° C. higher than melting point of the outer layer. 
     In some examples, the film is stretched and is stretched to a greater extent in one of a transverse direction and a longitudinal direction than in the other of the transverse direction and the longitudinal direction. 
     In some examples, the film has a tensile strength of 60 to 190 MPa in the longitudinal direction. 
     In some examples, the film has a tensile strength of 150 to 300 MPa in the transverse direction. 
     In some examples, the film has a stiffness of 3.5-5 GPa in the transverse direction. 
     In some examples, the film has a stiffness of 1.5-3 GPa in the longitudinal direction. 
     In some examples, the laminate includes 10 to 50 films. The number of films may be 22 or 23 films. 
     In one example, the thickness of the laminate is 0.25 mm to 2.5 mm. The thickness of the laminate may be 0.5 mm to less than 1 mm. 
     In some examples, the laminate may include at least one film constructed of a thermoplastic polymer different than the thermoplastic polymer of the core. 
     In another example, the films are laminated at a temperature of 110° C. to 130° C. 
     In a further example, the films are laminated at a pressure of 5 kN/m to 35 kN/m. 
     In some examples, the films are laminated at a pressure of 10 kN/m to 30 kN/m. 
     In some examples, the films are laminated in a continuous process. 
     In one example, laminating the films is performed in an isochoric press. In another example, laminating the films is performed in an isobaric press. 
     In another example, the laminate is cooled at atmospheric pressure. 
     In some examples, molding the luggage shell is performed at a temperature of 140° C. to 180° C. 
     In one example, a method of making a luggage shell includes providing films, laminating a plurality of films together to form a laminate, and molding the laminate to form a luggage shell. The films have a core of biaxially oriented polypropylene and an outer layer on each of the top and bottom side of the core. The films are laminated at a temperature of 130° C. or less and a pressure of less than 10 bar. 
     In some examples, the laminating temperature is 110° C. to 130° C. 
     In some examples, the pressure is 1 bar to 9 bar. The pressure may be 1 bar to 5 bar. In other examples, the pressure is less than 10 bar, or equal to or less than 10 bar. 
     In one example, the laminating is a continuous process. 
     In one example, the laminating is performed in an isochoric press. In another example, laminating the films is performed in an isobaric press. 
     In another example, at least two adjacent films are oriented in the same direction. 
     In a further example, all films are oriented in the same direction. 
     In some examples, the molding is performed at a temperature of about 140° C. to about 165° C. 
     In one example, a luggage shell is provided that is made by a method that includes providing films, laminating a plurality of films together to form a laminate, and molding the laminate to form the luggage shell. The films have a core of a thermoplastic polymer and an outer layer on each of the top and bottom side of the core, and the films are laminated together. When the films are polypropylene films, the films are laminated at a temperature of about 130° C. or less and a pressure of less than about 40 kN/m, or, in an alternative example, less than about 10 bar. In another example the pressure is about 40kN/m or less. In a further example the pressure is about 10 bar or less. 
     In one example, a luggage case including at least one aforementioned luggage shell is provided. The luggage shell is made by a method that includes providing films, laminating a plurality of films together to form a laminate, and molding the laminate to form the luggage shell. The films have a core of a thermoplastic polymer and may include an outer layer on each of, or just one of, the top and bottom side of the core, and the films are laminated together. When the films are polypropylene films, the films are laminated at a temperature of about 130° C. or less and a pressure of less than about 40 kN/m, or, in an alternative example, less than about 10 bar. In another example the pressure is about 40 kN/m or less. In a further example the pressure is about 10 bar or less. In a further example, the luggage case includes a lid shell and a base shell, either or both of which are produced by the aforementioned method. 
     Additional embodiments and features are set forth in part in the description that follows, and will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosed subject matter. A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure. One of skill in the art will understand that each of the various aspects and features of the disclosure may advantageously be used separately in some instances, or in combination with other aspects and features of the disclosure in other instances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description will be more fully understood with reference to the following figures in which components are not drawn to scale, which are presented as various embodiments of the disclosure and should not be construed as a complete recitation of the scope of the disclosure, characterized in that: 
         FIG. 1  is a fragmentary illustration of a biaxially orientated thermoplastic polymer film according to one example. 
         FIG. 2A  is an illustration of a laminate of biaxially orientated thermoplastic polymer films according to one example. 
         FIG. 2B  is an illustration of the layers of films in the laminate of  FIG. 2A . 
         FIG. 3A  is an illustration of a system for making the laminate of biaxially orientated thermoplastic polymer films of  FIGS. 2A and 2B  according to one example. 
         FIG. 3B  is an illustration of the temperature and pressure changes of the films during the process of  FIG. 3A . 
         FIG. 4A  is an illustration of a system for making the laminate of biaxially orientated thermoplastic polymer films of  FIGS. 2A and 2B  according to another example. 
         FIG. 4B  is an illustration of a system for making the laminate of biaxially orientated thermoplastic polymer films of  FIGS. 2A and 2B  according to another example. 
         FIG. 5  is a block diagram of the steps of a method of making the laminate of biaxially orientated thermoplastic polymer films of  FIGS. 2A and 2B  according to one example. 
         FIG. 6A  is a front right isometric view of a luggage shell formed by the process of  FIG. 3A or 3C . 
         FIG. 6B  is a rear left isometric view of the luggage shell of  FIG. 6A . 
         FIG. 7A  is a front isometric view a luggage case including the luggage shell of  FIG. 5A . 
         FIG. 7B  is a rear isometric view of the luggage of  FIG. 7A . 
         FIG. 8  is a molding apparatus according to one example. 
         FIG. 9  is a block diagram of the steps of a method of making an article from the laminate of  FIGS. 2A and 2B  according to one example. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides an improved material for a luggage shell and an improved luggage shell constructed of the material. In particular, the present disclosure provides a material that is lightweight, impact resistant, versatile, and amenable to being deep drawn. In general, the material is constructed of a plurality of plastic films laminated together. The luggage shell constructed from the material is lightweight, thin, durable, and resistant to deformation. The amenability of the material to a deep drawing process helps produce a luggage shell substantially free of wrinkles, including in the corner regions, and separately or in combination, helps produce a high-quality surface finish. As used herein, the term “constructed of” may mean “includes” or “including.” 
     The present disclosure may also provide a method of making the improved material that requires relatively little heat and pressure. The method may also be relatively fast and/or inexpensive. In particular, the plurality of plastic films is laminated under moderate heat and low-pressure conditions. 
     A method of making a luggage shell from the improved material that is relatively easy, fast, and inexpensive is also provided. The material may be heated, tensioned, and deep drawn to produce a luggage shell. 
     Polymer Films 
     Referring to  FIG. 1 , a polymer film  100  includes a core  102  and at least one outer layer  104 . As used herein, a “film” is a structure that includes a non-woven, planar, continuous sheet element. The outer layer  104  may be positioned on a top side  103  of the core  102 , a bottom side  105 , or both  103 ,  105 . The core  102  is constructed of a thermoplastic polymer. The thermoplastic polymer may be biaxially oriented. As used herein, a “biaxially oriented” film is a film that has been stretched in two different directions, including as a non-limiting example being stretched in a transverse direction and a longitudinal direction, as described below in more detail. Examples of biaxially oriented thermoplastic polymers include biaxially oriented polypropylene homopolymer (BOPP), polyamide (BOPA), polyester (BOPET), polyvinylalcohol (BOPVA), polylactid acid (BOPLA), and polyethylene (BOPE). In one embodiment, the core  102  is constructed of BOPP. 
     The outer layer  104  is constructed of an oriented or non-oriented heat-sealable material. In one example, the outer layer  104  is constructed of a copolymer of polypropylene (PP) and polyethylene (PE). Polyethylene may constitute up to about 5% of the copolymer. In another example, the outer layer  104  is constructed of a terpolymer of polypropylene, polyethylene, and polybutene (PB). Polyethylene and polybutene together may constitute up to about 5% of the terpolymer. 
     The core  102  and outer layer  104  may be constructed of compatible polymers such that the core  102  and outer layer  104  may be coextruded. In some examples, the core  102  and outer layer  104  are constructed of polymers in the same polymer family. In one example, the core  102  is constructed of an oriented polypropylene homopolymer (OPP) and the outer layer  104  is constructed of a copolymer of polypropylene and polyethylene. In another example, the core  102  is constructed of an oriented polypropylene homopolymer and the outer layer  104  is constructed of a terpolymer of polypropylene, polyethylene, and polybutene. 
     The core  102  may have a thickness of about 10 μm±5% to about 100 μm±5%, such as about 30 μm±5% to about 50 μm±5%, or about 13 μm±5% to about 40 μm±5%, or about 40 μm±5%. The core  102  may have a melting point of about 150° C. to about 190° C. In one example, the core  102  has a melting point of about 170° C. 
     The outer layer  104  may have a thickness of about 0.6 μm±5% to about 2.5 μm±5%. In one example, an outer layer  104  has a thickness of about 1 μm±5%. The outer layer  104  may have a melting point of about 110° C. to about 135° C. In one example, the melting point is about 130° C. 
     The outer layer  104  has a lower melting point than the core  102 . The difference between the melting point of the core  102  and the melting point of the outer layer  104  may be from about 10° C. to about 60° C., or from about 10° C. to about 50° C., or from about 10° C. to about 40° C., or from about 10° C. to about 30° C., or from about 10° C. to about 20° C. In the construction and design of a film  100 , a greater difference (e.g., 60° C. instead of 5° C.) in melting point between the core  102  and the outer layer  104  may help produce a laminate  110 , described below, with improved mechanical and/or physical properties. Without being limited to any mechanism or mode of action, a greater difference in melting point may permit laminating at a temperature that melts the outer layer  104  but does not melt the core  102 . When the processing temperature approaches the melting point of the core  102 , the core  102  may start to soften and the molecules of the core  102  may lose their orientation, which in turn may degrade the physical and mechanical properties of the resulting laminate  110  as compared to a laminate  110  in which the core  102  has not been melted or softened. 
     In the construction and design of a film  100 , a difference in melting point between the core  102  and the outer layer  104  of at least about 10° C. may make the process of laminating a plurality of films  100  together easier. The layers of a film  100  may slide over each other, or adjacent films  100  may slide over each other when forming the laminate  110 , when the processing temperature is high enough to melt or partially melt the outer layer  104  but not melt the core  102 . While the mechanical properties of the laminate  110  are best maintained by not melting the core  102  during production of the laminate sheet, in an alternative example if the core  102  is softened or partially melted during production of the laminate  110  the mechanical properties may be reduced but may still be adequate for further use. The difference in melting point may also make the process of molding a laminate  110  easier because the laminate  110  is rendered malleable by the melting or partial melting of the outer layer  104  and the melting, partial melting, or softening of the core  102 . 
     In one example, the outer layer  104  defines an outer surface  106  and an inner surface  108  adjacent to and engaging with the film  100 . The outer surface  106  may be Corona treated, which may help provide sufficient wetting and adhesion to the film  100  for subsequent printing, laminating, or coating of the film  100 . In one example, the outer layer  104  may be Corona treated on the outer surface  106 . 
     A core  102  and at least one outer layer  104  may be coextruded to form a film  100 . In contrast to woven fabrics, in which threads or tapes are woven in two directions (warp and weft) to form a plastic fabric, a coextruded film  100  is produced by simultaneous extrusion of multiple layers. The film  100  may have a thickness of about 10 μm±5% to about 100 μm±5%. In one example, the film  100  has a thickness of about 30 μm±5% to about 50 μm±5%. In another example, the film  100  has a thickness of about 40 μm±5%. The film  100  may have a square weight of about 13 g/m 2 ±5% to about 37 g/m 2 ±5%. The film  100  may be transparent, translucent, or opaque. 
     The thickness of an outer layer  104  may be about 0.5-25% of the thickness of a film  100 . In some examples, the outer layer is about 2-7% of the thickness of the film  100 . In one example, the outer layer  104  is about 2.5% of the thickness of the film  100 . In another example, the outer layer  104  is about 5% or less than about 5% of the thickness of the film  100 . 
     The film  100  may be stretched in one or both of the transverse and longitudinal directions. In one example, the transverse direction T is defined as the width of a roll of a core  102  or outer layer  104  material, which in one example may be in the direction of the roller  226   a, b , or  c  in  FIG. 3A . The longitudinal direction L is defined as the length material of a roll of core  102  or outer layer  104  material extending in a direction orthogonal to the transverse direction, which in one example may be in the machine direction as shown in  FIG. 3A . Alternatively, the transverse direction T and the longitudinal direction L may be reversed from that described above and shown in  FIG. 3A . The film  100  may be stretched after it is coextruded. The amount of stretching in one direction may be the same as or different than the amount of stretching in the other direction. In some examples, a film  100  is stretched in the transverse direction about 4-15 times (i.e., about 400% to 1500%), about 5-14 times, about 6-13 times, or about 7-12 times. In one example, a film  100  is stretched about 9 times in the transverse direction. In some examples, a film  100  is stretched in the longitudinal direction about 3-10 times, about 4-8 times, or about 4-6 times. In one example, a film  100  is stretched about 5 times in the longitudinal direction. The variable stretching may produce an anisotropic film  100 . As a general note, the orientation of the transverse and longitudinal directions that are referenced throughout may be interchangeable. Also in general, the film  100  is stretched to a higher extent in one of transverse or longitudinal directions than in the other of the transverse or longitudinal directions. 
     The anisotropic film  100  has a tensile strength in each of the transverse and longitudinal directions. The tensile strength in one direction may be different than the tensile strength in the other direction. In some examples, the film  100  has a greater tensile strength in the transverse direction than in the longitudinal direction. In some examples, the film  100  has a greater tensile strength in the longitudinal direction than in the transverse direction. The film  100  may have a tensile strength in the transverse direction of about 150-300 MPa. In one example, the film  100  has a tensile strength in the transverse direction of about 250 MPa. In another example, the film  100  has a tensile strength in the transverse direction of about 207 MPa. The film  100  may have a tensile strength in the longitudinal direction of about 60-190 MPa. In one example, the film  100  has a tensile strength in the longitudinal direction of about 130 MPa. In another example, the film  100  has a tensile strength in the longitudinal direction of about 91 MPa. 
     The film  100  has a stiffness in each of the transverse and longitudinal directions. The stiffness may be a measure of bending stiffness in which the bending axis is generally orthogonal to the direction of stretching. The stiffness in one direction may be different than the stiffness another other direction. In some examples, the film  100  has a greater stiffness in the transverse direction than in the longitudinal direction. In some examples, the film  100  has a greater stiffness in the longitudinal direction than in the transverse direction. The film  100  may have a greater stiffness in the direction in which it stretched more. For example, a film stretched more in the transverse direction than in the longitudinal direction may have a greater stiffness in the transverse direction than in the longitudinal direction. Similarly, a film stretched more in the longitudinal direction than in the transverse direction may have a greater stiffness in the longitudinal direction than in the transverse direction. 
     In one direction, the film  100  may have stiffness of about 3.5-5.5 GPa or about 4-4.8 GPa. In the other direction, the film  100  may have stiffness of about 1.5-3 GPa or about 1.9 to 2.3 GPa. In one example, the film  100  is stretched more in the transverse direction and has a stiffness of about 3.5-5.5 GPa in the transverse direction and a stiffness of about 1.5-3 GPa in the longitudinal direction. 
     In some illustrative examples, the film  100  is constructed of a coextruded core  102  of oriented polypropylene and outer layers  104 , constructed of terpolymer of polypropylene, polyethylene, and polybutene, one each on either side of the core  102 . In some illustrative examples, the film  100  is constructed of a coextruded core  102  of oriented polypropylene and outer layers  104 , constructed of a copolymer of polypropylene and polyethylene, one each on either side of the core  102 . For convenience but not limitation, the film  100  may be referred to herein as [PP-BOPP-PP]. The core  102  may have a thickness of about 38 μm±5% and each outer layer  104  may have a thickness of about 1 μm±5%. The film  100  may have a square weight of about 36.4 g/m 2 ±5%. The film  100  may have a melting point of about 169.2±0.4° C. The film  100  may have a tensile strength in the transverse direction of about 207.2±5.4 MPa. The film  100  may have a tensile strength in the longitudinal direction of about 91.2±18.7 MPa. The film  100  may be Tatrafan KXE® (Terichem Ltd., Svit, Slovakia). Tatrafan KXE® is designed for wrapping food products, confectionaries, meat products, textiles, and other goods. 
     In another example, the film  100  may be constructed of a coextruded core  102  of oriented polypropylene and one outer layer  104  constructed of a copolymer of polypropylene and polyethylene or of a terpolymer of polypropylene, polyethylene, and polybutene. For convenience but not limitation, the film  100  may be referred to herein as [PP-BOPP] or [BOPP-PP]. The film  100  may have a thickness of about 20 μm±5% and may have a square weight of about 22.8 g/m 2 ±5%. The film  100  may be Tatrafan ONXE® (Terichem Ltd., Svit, Slovakia). Tatrafan ONXE® is designed for wrapping food products, confectionaries, meat products, textiles, and other goods. 
     Referring to  FIG. 2A , a plurality of films  100  form a laminate  110 . The number of films  100  in a laminate  110  may be about 3 to about 50 films 100, about 5 to about 50, about 10 to about 50, about 15 to about 50, about 20 to about 50, about 25 to about 50, about 30 to about 50, about 35 to about 50, about 3 to about 40, about 3 to about 35, about 3 to about 30, about 3 to about 25, about 3 to about 20, or about 3 to about 15 films  100 . In one example, a laminate  110  includes about 10 to about 50 films. In another example, a laminate  110  includes about 22 to about 35 films  100 . In another example, a laminate  110  includes about 3 to about 23 films  100 . In a further example, a laminate  110  includes about 24 to about 28 films  100 . In another non-limiting example, a laminate  110  may be formed of 22 to 26 film layers of Tatrafan KXE having one film layer of Tatrafan ONXE on each outer side, totaling 24 to 28 films  100 . In yet another example, a laminate  110  includes 22 or 23 films  100 . 
     The laminate  110  may include a center  112 , a first side or portion  114 , and a second side or portion  116 . A laminate  110  may include the same number of films  100  in each of the center  112 , first side  114 , and second side  116 , or the numbers may be different. The number of films  100  in the first side  114  and the second side  116  may be the same or different. In one example, the first side  114  and second side  116  have the same number of films  100  and that number is less than the number of films  100  of the center  112 . In one example, each of the first side  114  and second side  116  has one film  100  and the center has 10-50 films  100 . 
     The films  100  of the laminate  110  may be of the same type or different types. In one example, a laminate  110  includes a center  112  of one type of film  100 , a first side  114  of a second type of film  100 , and a second side  116  of a third type of film  100 . In another example, a laminate  110  includes a center  112  of one type of film  100  and a first side  114  and second side  116 , each of a second type of film  100 . 
     In one example, the center  112  is constructed of a plurality of [PP-BOPP-PP] films  100 . When a plurality of [PP-BOPP-PP] films  100  are laminated together, two PP layers, which may be PP/PE copolymers or PP/PE/PB terpolymers as described above, are positioned adjacent each other. 
     In one example, each of the first side  114  and second side  116  may be constructed of at least one [PP-BOPP] or [BOPP-PP] film  100 . When a [PP-BOPP] or [BOPP-PP] film  100  is laminated with a [PP-BOPP-PP] film  100 , two PP layers, which may be PP/PE copolymers or PP/PE/PB terpolymers as described above, may be positioned adjacent each other. 
     In one example, one or both of the first side  114  and second side  116  of the laminate  110  may be constructed of at least one BOPET-BOPP, BOPP-BOPET, or BOPET-BOPP-BOPET film  100 . In one example, the BOPET portion of the film  100  may be positioned on the outermost surface of the first side  114  or second side  116 . Positioning BOPET on the outermost surface of first side  114  or second side  116  may help achieve improved scratch resistance of the laminate  110  or an article formed from the laminate  110 . 
     In one example, and with reference to  FIG. 2B , the laminate  110  has the arrangement of films  100  represented by [BOPP-PP]-[PP-BOPP-PP] n -[PP-BOPP], where n is the number of films  100 . The [PP-BOPP-PP] films  100  may be Tatrafan KXE®. The [PP-BOPP] and [BOPP-PP] films  100  may be Tatrafan ONXE®. 
     As described above, a film  100  may be stretched in one or both of the transverse and longitudinal directions. In the laminate, the films  100  may be oriented in the same direction as an immediately adjacent film  100 . For example, two films  100  stretched more in the transverse direction than in the longitudinal direction may be immediately adjacent to each other. In other words, two immediately adjacent films  100  may be rotated 0° relative to each other in regards to the degree of stretching. Alternatively, two immediately adjacent films  100  may be rotated 90° relative to each other. For example, one film  100  stretched more in the transverse direction than in the longitudinal direction may be immediately adjacent to a film  100  stretched more in the longitudinal direction than in the transverse direction. At least two films  100  in the laminate  110  may be oriented in the same direction. In one example, all films  100  in at least the center  112  of the laminate  110  are oriented in the same direction. In another example, all films  100  in the laminate  110  are oriented in the same direction. 
     The laminate  110  may have a thickness of about 0.25 to about 2.5 mm, about 0.3 to about 2.5 mm, about 0.5 to about 2.5 mm, about 0.75 to about 2.5 mm, about 1.0 to about 2.5 mm, about 1.25 to about 2.5 mm, about 1.5 to about 2.5 mm, about 0.25 to about 2.25 mm, about 0.25 to about 2.0 mm, about 0.25 to about 1.75 mm, about 0.25 to about 1.5 mm, about 0.25 to about 1.25 mm, or about 0.25 to about 1.00 mm. In one example, the laminate  110  has a thickness of about 0.5 to about 2 mm. In another example, the laminate  110  has a thickness of about 0.9 to about 1.5 mm. In yet another example, the laminate  110  has a thickness of about 0.5 mm to less than about 1.0 mm. 
     The first side  114  may have the same thickness as the second side  116  or may have a different thickness. The thickness of the center  112  may be greater than the thickness of the first side  114  or the thickness of the second side  116  or the thickness of each of the first side  114  and second side  116 . The thickness of the center  112  may be greater than the thickness of the first side  114  and second side  116  combined. 
     The anisotropic properties of the films  100  may be imparted to the laminate  110  in which the films  100  are incorporated. For example, the laminate  110  has a tensile strength in one direction that is different than the tensile strength in the other direction. In some examples, the laminate  110  has a greater tensile strength in the transverse direction than in the longitudinal direction. In some examples, the laminate  110  has a greater tensile strength in the longitudinal direction than in the transverse direction. The laminate  110  may have a tensile strength in the transverse direction of about 100-250 MPa, or about 150-200 MPa. The laminate  110  may have a tensile strength in the longitudinal direction of about 50-150 MPa, or about 70-100 MPa. 
     In one example, the laminate  110  is clear, colorless, and transparent, translucent, or opaque. In another example, the core  102  of at least one film  100  is constructed of a colored film  100 , such as a PP, BOPP, or other type of film  100 , that introduces color to the laminate  110 . 
     The laminate  110  may include one or more auxiliary materials  118  in addition to the films  100  of the center  112 , first side  114 , and second side  116 . In the construction and design of the laminate  110 , an auxiliary material  118  may introduce a color, print, pattern, or design to the laminate  110 . In some examples, the auxiliary material  118  is constructed of a solid film, such as a cast polypropylene film, which may be constructed of the same polymer as the outer layer  104 . In some examples, the auxiliary material  118  includes a core  102  and at least one outer layer  104 . As described above, the outer layer  104  may have a lower melting temperature than the core  102 . The auxiliary material, or the outer layer  104  when present, may have a melting temperature of about 130° C. or lower. 
     The auxiliary material  118  may be introduced within the plurality of films  100  of the center  112 , first side  114 , or second side  116 . Alternatively, the auxiliary material  118  may be introduced between the center  112  and first side  114  or the center  112  and second side  116 . As another alternative, the auxiliary material  118  may be introduced on the outer surface of the first side  114  or the exterior of the second side  116  as the outermost layer (top film) of the laminate  110 . The auxiliary material  118  may be coextruded with the films  100  of the laminate  110 . Examples of auxiliary materials  118  include thermoplastic olefin films, printed films, colored polypropylene and/or polyethylene films, white or colored BOPP films, metallized BOPP films, short or chopped polypropylene fibers, short or chopped bicomponent (BICO) fibers, knitted fabrics, woven fabrics, nonwoven fabrics, polypropylene and/or polyethylene powder, and combinations thereof. 
     A laminate  110  may be formed by laminating a plurality of films  100  under predetermined pressure, temperature, and/or time conditions. The laminate  110  may be formed in a laminating machine. The laminating machine may be an isochoric press or an isobaric press. The laminating machine may include at least one roller, which may be a fixed roller or a circulating roller. In an isochoric press, constant volume is maintained, such as by maintaining a constant gap distance between pressure applicators, such as in one example opposing rollers spaced apart a fixed distance. In an isochoric press, and for example one using a circulating roller pressure module, a combination of constant volume and constant uniform pressure is maintained or attempted to be maintained. The rollers in an isochoric press may be fixed in position relative to the laminating machine, or may move relative to the laminating machine, such as in a circulating roller pressure module. The pressure applied by an isochoric press having fixed rollers is generally referred to as “line pressure,” measured in kN/m. The pressure is applied, for example, by at least one roller, and in at least one other example the line pressure is applied to the material being formed as it passes through the gap between opposing fixed rollers. In an isochoric press using a circulating roller pressure module, the pressure is applied between opposing rollers as the rollers circulate in the pressure module. Because typically the rollers used in a fixed roller press are larger (in one example, approximately 100 mm) compared to the rollers used in a circulating roller pressure module (in one example, approximately 25-40 mm) there is a smaller pressure drop between the adjacent rollers. The pressure applied in a circulating roller pressure module, because of the smaller pressure drop between adjacent rollers, may be considered to be, or estimated as, a pressure applied over an area of the material being formed. As a result, the pressure applied by a circulating roller pressure module is often measured as “bar.” 
     In an isobaric press, constant uniform pressure is maintained, such as by permitting the gap distance between pressure applicators to be defined by the infeed material. The pressure applied by an isobaric press is generally surface pressure, measured in kN/m 2  or bar, applied, for example, by at least one oil cushion. In other examples, the pressure applicators are opposing oil cushions spaced apart by a gap. As used herein, “bar” generally but not exclusively refers to a surface pressure generated by an isobaric press or an isochoric press including circulating rollers. As used herein, “kN/m” generally but not exclusively refers to a line pressure generated by an isochoric press having fixed rollers. Examples of laminating press equipment that may be utilized for this type of forming method, either isochoric or isobaric, or implementing a combination of both methods, may be manufactured by Sandvik, such as the Sandvik ThermoPress CB (CombiPress) (see http://processsystems.sandvik.com). 
     In some examples, the laminating machine is an isobaric press. In other examples, and with reference to  FIG. 3A , the laminating machine may be a double belt isochoric press  220  having fixed rollers. The press  220  includes an upper belt  222 , a lower belt  224 , a plurality of upper rollers  226 , and a plurality of lower rollers  228 . Some or all of the rollers  226 ,  228  may be operatively connected to springs  234 , which help adjust the pressure applied by the rollers  226 ,  228  to material passing between the rollers  226 ,  228 . The press  220  may also include at least one integrated heating zone  230  and at least one integrated cooling zone  232 . 
     The belts  222 ,  224  may be constructed of Teflon or steel. The belts  222 ,  224  may be conveyor belts. The upper belt  222  operatively connects at least two upper rollers  226 , such as four upper rollers  226   a,    226   b,    226   c,  and  226   d.  The lower belt  224  operatively connects at least two lower rollers  228 , such as five lower rollers  228   a,    228   b,    228   c,    228   d,  and  228   e.  An upper roller  226   a,    226   b,    226   c,    226   d  and a corresponding lower roller  228   a,    228   b ,  228   c,    228   d,  respectively, may be positioned opposite each other on either side of films  100  being laminated. 
     The distance or gap height, h g , between an upper roller  226  and a corresponding lower roller  228  may be adjustable. The gap height may be the same or different between each pair of rollers  226   a,    228   a,    226   b,    228   b,    226   c,    228   c,    226   d,    228   d.  Adjusting the gap height may help adjust or maintain the pressure applied by the rollers  226 ,  228 , may help maintain a uniform volume of material between the rollers  226 ,  228 , and may help control the thickness of the laminate  110 . In one example, the gap height is about 0.7 mm to about 1.2 mm. In another example, the gap height is about 0.95 mm to about 1.0 mm. 
     The belts  222 ,  224  and rollers  226 ,  228  may help advance a plurality of films  100  through the press  220 . The plurality of films  100  may move through the press at a constant or variable rate. Adjusting the rate may permit the application of a pressure or a temperature to the films  100  for varying amounts of time. The rate may be from about 1 m/min to about 8 m/min, about 2 m/min to about 8 m/min, about 3 m/min to about 8 m/min, about 4 m/min to about 8 m/min, about 5 m/min to about 8 m/min, about 1 m/min to about 7 m/min, about 1 m/min to about 6 m/min, about 1 m/min to about 5 m/min, about 1 m/min to about 4 m/min, about 1 m/min to about 3 m/min, or about 2 m/min to about 6 m/min. In one example, the rate is about 2 m/min. In another example, the rate is about 6 m/min. 
     In one example, the press  220  is a Flatbed Laminator System (Meyer, Roetz, Germany). 
       FIG. 4A  illustrates another example of a laminating machine that is a double belt isochoric press  220  having fixed rollers. The press  220  includes an upper belt  222 , a lower belt  224 , a plurality of upper rollers  226 , and a plurality of lower rollers  228 . The press  220  may also include at least one integrated heating zone  230  and at least one integrated cooling zone  232 . 
     The belts  222 ,  224  may be constructed of Teflon or steel. The belts  222 ,  224  may be conveyor belts. The upper belt  222  operatively connects at least two upper pressure modules  227 , such as seven upper pressure modules  227   a,    227   b,    227   c,    227   d,    227   e,    227   f , and  227   g.  The lower belt  224  operatively connects at least two lower pressure modules  229 , such as seven lower pressure modules  229   a,    229   b,    229   c,    229   d,    229   e,    229   f,  and  229   g.  An upper pressure module  227   a,    227   b,    227   c,    227   d,    227   e,    227   f,  and  227   g  and a corresponding lower pressure module  229   a,    229   b,    229   c,    229   d,    229   e,    229   f,  and  229   g,  respectively, may be positioned opposite each other on either side of films  100  being laminated. 
     Each pressure module  227 ,  229  may have the same width or different widths. In one example, each pressure module  227 ,  229  is about 1000 mm wide. 
     Each upper pressure module  227   a - g  may include one or more upper rollers  226 . Similarly, each lower pressure module  229   a - g  may include one or more lower rollers  228 . The number of upper rollers  226  may be the same or different for each upper pressure module  227 . The number of lower rollers  228  may be the same or different for each lower pressure module  229 . The number of upper rollers  226  may be the same as or different from the number of lower rollers  228 . With reference to  FIG. 4A , an upper pressure module  227  may include 5 upper rollers  226  and a lower pressure module  229  may include 5 lower rollers  228 . In the design and operation of a press  220 , the rollers  226 ,  228  may create line pressure on the material, such as films  100  or laminate  110 , positioned between the upper rollers  226  and lower rollers  228 . 
     The belts  222 ,  224  and pressure modules  227 ,  229  or rollers  226 ,  228  may help advance a plurality of films  100  through the press  220 . The plurality of films  100  may move through the press at a constant or variable rate. Adjusting the rate may permit the application of a pressure or a temperature to the films  100  for varying amounts of time. The rate may be from about 1 m/min to about 8 m/min, about 2 m/min to about 8 m/min, about 3 m/min to about 8 m/min, about 4 m/min to about 8 m/min, about 5 m/min to about 8 m/min, about 1 m/min to about 7 m/min, about 1 m/min to about 6 m/min, about 1 m/min to about 5 m/min, about 1 m/min to about 4 m/min, about 1 m/min to about 3 m/min, or about 2 m/min to about 6 m/min. In one example, the rate is about 2 m/min. In another example, the rate is about 6 m/min. 
     In one example, the press  220  is a double steel belt isochoric thermopress (Sandvik Process Systems, Sandviken, Sweden). 
     In some examples, and with reference to  FIG. 4B , the laminating machine may be an isochoric press having at least one module  235  including circulating rollers  236  and at least one module  237  including fixed rollers  238 . The material being formed moves from left to right in this example, first through the circulating rollers  236  and then through the fixed rollers  238 . The circulating rollers  236  of the isochoric press may apply surface pressure measured in bar. The fixed rollers  238  of the isochoric press may apply line pressure measured in kN/m. In one example, a heating zone  239 , such as in integrated heating zone  230  (see  FIG. 3A ), may include a plurality of circulating rollers  235 . In one example, a cooling zone  241 , such as an integrated cooling zone  232  (see  FIG. 3A ) may include a plurality of fixed rollers  238 . 
     Referring to  FIG. 5 , a method  200  of making a laminate  110  may include a step  202  of introducing a plurality of films  100  into a laminating machine, a step  204  of applying a first pressure to the films  100 , a step  206  of applying a first temperature to the films  100  for a first time, a step  212  of applying a second pressure to the films  100 , a step  214  of applying a second temperature to the films  100  for a second time, and a step  218  of releasing the laminate  110  from the machine. In some embodiments, the method includes one or more of a step  208  of applying a third pressure to the films  100 , a step  210  of applying a third temperature to the films  100  for a third time, and a step  216  of applying a fourth pressure to the films  100 . The method  200  may be a continuous process as opposed to a batch process. 
     When temperature is applied to the films  100  in any one or more of steps  206 ,  210 ,  214 , the temperature may be high enough to melt or partially melt the outer layer  104  but not high enough to melt the core  102 . 
     In the method  200  of making the laminate  110 , the outer layer  104  may be melted. Instead of or in addition to melting the outer layer  104 , the outer layer  104  and core  102 , or films  100  within or between the outer layer  104  and core  102 , may be cross-linked with each other, or otherwise bonded with each other, such as by chemical, physical, or adhesive bonding. Melting, cross-linking, and/or otherwise bonding films  100  may help produce a laminate  110  with improved physical properties, such as stiffness, tensile strength, and strain to failure. 
     In step  202 , a plurality of films  100  is introduced into a laminating machine. The laminating machine may be any machine described above, such as an isochoric or isobaric press. 
     In step  204 , the plurality of films  100  are subjected to a first pressure P 1 . Applying pressure may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. Referring to  FIG. 3A , the pressure may be applied by a pair of rollers, such as an upper roller  226   a  positioned on the opposite side of the films  100  from a corresponding lower roller  228   a.  The pressure may be applied to the portion of the films  100  positioned between the rollers  226   a,    228   a  as the films  100  move through the rollers  226   a ,  228   a  at any rate described above, such as about 2 m/min. In other examples, such as with isobaric presses, the pressure (surface pressure) is applied by at least one oil cushion. P 1  may be less than about 10 bar, such as about 1 to about 9 bar, about 1 to about 8 bar, about 1 to about 7 bar, about 1 to about 6 bar, about 1 to about 5 bar, about 1 to about 4 bar, about 1 to about 3 bar, or about 1 to about 2 bar. When P 1  is measured in kN/m (line pressure), P 1  may be less than about 40 kN/m, such as about 5 to about 35 kN/m or about 10 to about 30 KN/m. 
     Referring to  FIG. 3B , when P 1  is applied to the films  100  by the rollers, the films  100  may experience a spike in pressure. As shown in  FIG. 3B , in the space between the opposing rollers the pressure level in the films  100  is reduced until the next pair of opposing rollers are encountered. 
     Referring again to  FIG. 5 , in step  206 , the plurality of films  100  are heated to a first temperature T 1  for a first time t 1 . When T 1  is greater than ambient temperature, the heat may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. When T 1  is at or near the melting point of the outer layer  104  of the films  100 , the outer layer  104  may start to melt or become tacky. When T 1  is at or near the melting point of the core  102 , the core  102  may start to relax and/or shrink. Referring to  FIG. 3A , the temperature may be controlled in a heating zone  230 . T 1  may be about 90° C. to about 150° C., about 100° C. to about 150° C., about 110° C. to about 150° C., about 120° C. to about 150° C., about 130° C. to about 150° C., about 90° C. to about 140° C., about 90° C. to about 130° C., about 90° C. to about 120° C., or about 90° C. to about 110° C. In one example, T 1  is about  130 ° C. or less. In another example, T 1  is about 110° C. to about 140° C. In another example, T 1  is about 105° C. to about 135° C. In yet another example, T 1  is about 110° C. to about 130° C. In yet another example, T 1  is about 115° C. to about 120° C. To achieve the desired T 1 , the temperature of a heating element used to heat the films  100  may be at a higher temperature. 
     First time t 1  may be from about 15-120 seconds, about 30-120 seconds, about 45-120 seconds, about 60-120 seconds, about 75-120 seconds, about 90-120 seconds, about 15-90 seconds, about 15-75 seconds, about 15-60 seconds, about 15-45 seconds, or about 15-30 seconds, or about 30-90 seconds. In one example, t 1  is 45-55 seconds. 
     Referring to  FIG. 3B , when the plurality of films  100  is heated to T 1 , the temperature of the films  100  may increase over time t 1 . The pressure experienced by the films  100  may remain constant and lower than P 1  during t 1 . 
     Although shown as sequential steps in  FIG. 5 , in some embodiments, steps  204  and  206  may occur simultaneously. In general, the steps  202 ,  204 ,  206 ,  208  (when present),  210  (when present),  212 ,  214 ,  216  (when present), and  218  may be performed in the order depicted in  FIG. 5  or in a different order. 
     In step  212 , as shown in  FIG. 5 , the plurality of films  100  are subjected to a second pressure P 2 . Applying pressure may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. In some implementations, the application of pressure following the application of heat during t 1  may help press the films together or may help define a thickness of the laminate  110 . Referring to  FIG. 3A , the pressure may be applied by a pair of rollers, such as an upper roller  226   c  positioned on the opposite side of the films  100  from a corresponding lower roller  228   c.  The pressure may be applied to the portion of the films  100  positioned between the rollers  226   c,    228   c  as the films  100  move through the rollers  226   c,    228   c  at any rate described above, such as about 2 m/min. In other examples, such as with isobaric presses, the pressure (surface pressure) is applied by an oil cushion. P 2  may be the same as or different from P 1 . P 2  may be less than about 10 bar, such as about 1 to about 9 bar, about 1 to about 8 bar, about 1 to about 7 bar, about 1 to about 6 bar, about 1 to about 5 bar, about 1 to about 4 bar, about 1 to about 3 bar, or about 1 to about 2 bar. When P 2  is measured in kN/m (line pressure), P 2  may be less than about 40 kN/m, such as about 5-35 kN/m or about 10-30 KN/m. 
     Referring to  FIG. 3B , when P 2  is applied to the plurality of films  100 , the films  100  may experience a spike in pressure. The pressure may be about the same as P 1 . 
     In step  214 , as shown in  FIG. 5 , the plurality of films  100  are subjected to a second temperature T 2  for a second time t 2 . When T 2  is ambient temperature or less, the cooler temperature may help stabilize the laminate  110 . Referring to  FIG. 3A , the temperature may be controlled in a cooling zone  232 . The temperature may be controlled by, for example, circulating water through tubes in the cooling zone  232  or by spraying water on one or more belts  222 ,  224  in the cooling zone  232 . T 2  may be about 10° C. to about 30° C., about 15° C. to about 30° C., about 20° C. to about 30° C., about 25° C. to about 30° C., about 10° C. to about 25° C., about 10° C. to about 20° C., or about 10° C. to about 15° C. In one example, T 2  is about 15° C. to about 25° C. 
     Second time t 2  may be from about 2-90 seconds, about 5-90 seconds, about 10-90 seconds, about 20-90 seconds, about 30-90 seconds, about 40-90 seconds, about 50-90 seconds, about 60-90 seconds, about 2-60 seconds, about 2-50 seconds, about 2-40 seconds, about 2-30 seconds, about 2-20 seconds, about 2-10 seconds, or about 10-60 seconds. 
     Referring to  FIG. 3B , when T 2  is applied to the plurality of films  100 , the temperature of the films  100  may decrease over time t 2 . The temperature of the films  100  may fall below the starting temperature at the beginning of t 1 . During t 2 , the pressure experienced by the films  100  may remain constant and lower than P 2 . The pressure may be atmospheric pressure. In some embodiments, the plurality of films  100  are cooled in the absence of applied pressure. 
     Although shown as sequential steps in  FIG. 5 , in some embodiments, steps  212  and  214  may occur simultaneously. 
     The pressures and temperatures applied during the course of the method  200  are effective to laminate the plurality of films  100  together to form a laminate  110 . In step  218 , as shown in  FIG. 5 , the laminate  110  is released from the laminating machine. 
     In some embodiments, the method  200  includes a step  208  of subjecting the plurality of films  100  to a third pressure P 3 . Applying pressure may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. In some implementations, the application of pressure following the application of heat during t 1  may help press the films together or may help define a thickness of the laminate  110 . Referring to  FIG. 3A , the pressure may be applied by a pair of rollers, such as an upper roller  226   b  positioned on the opposite side of the films  100  from a corresponding lower roller  228   b.  The pressure may be applied to the portion of the films  100  positioned between the rollers  226   b ,  228   b  as the films  100  move through the rollers  226   b,    228   b  at any rate described above, such as about 2 m/min. In other examples, such as with isobaric presses, the pressure (surface pressure) is applied by at least one oil cushion. P 3  may be the same as or different from P 1  or P 2 . P 3  may be less than about 10 bar, such as about 1 to about 9 bar, about 1 to about 8 bar, about 1 to about 7 bar, about 1 to about 6 bar, about 1 to about 5 bar, about 1 to about 4 bar, about 1 to about 3 bar, or about 1 to about 2 bar. When P 3  is measured in kN/m (line pressure), P 3  may be less than about 40 kN/m, such as about 5-35 kN/m or about 10-30 KN/m. 
     As shown in  FIG. 3B , when P 3  is applied to the plurality of films  100 , the films  100  may experience a spike in pressure. The pressure may be less than each of P 1  and P 2 . 
     In some embodiments, the method  200  includes a step  210  of subjecting the plurality of films  100  to a third temperature T 3  for a third time t 3 . When T 3  is greater than ambient temperature, the heat may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. Referring to  FIG. 3A , the temperature may be controlled in a heating zone  230 . T 3  may be about 90° C. to about 150° C., about 100° C. to about 150° C., about 110° C. to about 150° C., about 120° C. to about 150° C., about 130° C. to about 150° C., about 90° C. to about 140° C., about 90° C. to about 130° C., about 90° C. to about 120° C., or about 90° C. to about 110° C. In one example, T 3  is about 130° C. or less. In another example, T 3  is about 110° C. to about 140° C. In yet another example, T 3  is about 110° C. to about 130° C. 
     Referring to  FIG. 3B , when T 3  is applied to the plurality of films  100 , the temperature of the films  100  may increase over time t 3 . The temperature of the films  100  during t 3  may be greater than the temperature of the films  100  during each of t 1  and t 2 . The pressure experienced by the films  100  during t 3  may remain constant and lower than each of P 1 , P 2 , and P 3 . 
     Referring again to  FIG. 5 , in optional step  216 , the plurality of films  100  are subjected to a fourth pressure P 4 . Applying pressure may help laminate the films  100  together and may help produce a laminate  110  with a high bonding strength. Referring to  FIG. 3A , the pressure may be applied by a pair of rollers, such as an upper roller  226   d  positioned on the opposite side of the films  100  from a corresponding lower roller  228   d.  The pressure may be applied to the portion of the films  100  positioned between the rollers  226   d,    228   d  as the films  100  move through the rollers  226   d,    228   d  at any rate described above, such as about 2 m/min. In other examples, such as with isobaric presses, the pressure (surface pressure) is applied by an oil cushion. P 4  may be the same as or different from any of P 1 , P 2 , or P 3 . P 4  may be less than about 10 bar, such as about 1 to about 9 bar, about 1 to about 8 bar, about 1 to about 7 bar, about 1 to about 6 bar, about 1 to about 5 bar, about 1 to about 4 bar, about 1 to about 3 bar, or about 1 to about 2 bar. When P 4  is measured in kN/m (line pressure), P 4  may be less than about 40 kN/m, such as about 5-35 kN/m or about 10-30 KN/m. In some embodiments, no pressure is applied and P 4  is about 1 bar or atmospheric pressure. 
     The laminate  110  produced by the method  200  may demonstrate a reduced level of shrinkage, and in some examples may only experience minimal shrinkage. For example, the laminate  110  may demonstrate about 1% shrinkage at 110° C. 
     Luggage Articles Constructed of Laminates of Biaxially Oriented Thermoplastic Polymer Films 
     A luggage shell  120 , such as a suitcase shell, may be constructed of a laminate  110  disclosed herein. Referring to  FIGS. 6A and 6B , the luggage shell  120  may be in the form of a lid shell  122  ( FIG. 6A ) or a base shell  134  ( FIG. 6B ). The lid shell  122  includes a rear side  124 , a lid top side  126 , a lid bottom side  128 , a lid right side  130 , a lid left side  132 , and one or more corner portions  146 . The base shell  134  includes a front side  136 , a base top side  138 , a base bottom side  140 , a base right side  142 , a base left side  144 , and one or more corner portions  146 . Each corner portion  146  may be an indentation for receiving a wheel when the shell  120  is used in a luggage article. 
     Any one or more of the sides  124 ,  126 ,  128 ,  130 ,  132 ,  136 ,  138 ,  140 ,  142 ,  144 , or corner portions  146  may include surface features  148 . The features may be positioned along the length, along the width, or at an angle of the sides  124 ,  126 ,  128 ,  130 ,  132 ,  136 ,  138 ,  140 ,  142 ,  144 , or corner portions  146 . The features  148  may be concave areas, such as grooves  147 , and convex areas, such as ribs  149 , which may alternate. The features  148  may be aesthetically pleasing. The features  148  may also help provide stiffness or resistance to bending or distortional forces exerted against the shell  120 , such as forces exerted orthogonally to the features  148 . 
     One or both of the base shell  22  and the lid shell  134  may be formed of a laminate  110  of a plurality of films  100  described above. In brief, the films  100  may be coextruded and may comprise a core  102  of oriented polypropylene and at least one outer layer  104  positioned adjacent to the core  102 . 
     The outer layer  104  may be constructed and designed as described above. In one example, the outer layer  104  is constructed of a copolymer of polypropylene and polyethylene. In another example, the outer layer  104  is constructed of a terpolymer of polypropylene, polyethylene, and polybutene. The outer layer  104  may have a thickness of less than about 5% of the thickness of a film  100 . In one example, the outer layer  104  is about 2.5% of the thickness of a film  100 . 
     The plurality of films  100  that form the laminate  110  from which the luggage shell  120  is constructed may be any number of films  100  described above. From about 10 to about 50 films, about 22 to about 35 films, 22 films, or 23 films, may form the laminate  110 . At least two adjacent films  100  are oriented in the same direction. In one example, all films  100  are oriented in the same direction. 
     The thickness of the laminate  110  from which the luggage shell  120  is constructed may be any thickness described above. For example, the thickness of the laminate  110  may be about 0.5 mm to about 2 mm or may be about 0.5 mm to less than about 1 mm. 
     One or both of the base shell  122  and the lid shell  134  may be deep drawn such that the depth of the base shell  122  or the lid shell  134  is quite large relative to its length or width. For example, the depth of the lid top side  126  and lid bottom side  128  may be up to one half the length or one half the width of the rear side  124 . As another example, the depth of the base top side  138  or base bottom side  140  may be up to one half the length or one half the width of the front side  136 . 
     Any luggage shell  120  described above may be used to form the body of a luggage case  150 , such as a hard-sided luggage case. Referring to  FIGS. 7A and 7B , a hard sided luggage case  150  is defined by a lid shell  122  and a base shell  134  operably coupled together to form a housing  152  having by an exterior layer  154 . Either or both of the lid shell  122  and base shell  134  may be produced by any aforementioned method. The exterior layer  154  may have a textured surface or a shaped surface. 
     The luggage case  150  includes a front panel  156 , a rear panel  158 , a top panel  160 , a bottom panel  162 , a right side panel  164 , and a left side panel  166 . Corner regions  168  are defined by the intersection of any two or three adjacent panels  156 ,  158 ,  160 ,  162 ,  164 , and  166 . For example, the luggage case  150  includes four upper corner regions and four lower corner regions, each formed by the intersection of three adjacent panels. Additionally, the edges formed by the intersection of any two adjacent panels may also be considered a corner region. The panels  156 ,  158 ,  160 ,  162 ,  164 ,  166  as described herein may also be referred to as “sides.” Thus, a first side, a second side, and/or a third side of the luggage case  150  may each be any of the various panels  156 ,  158 ,  160 ,  162 ,  164 ,  166  described herein. The luggage case  150  may also include a closure mechanism, such as a zipper, that extends along the central portions of the side panels  164 ,  166  and the top and bottom panels  160 ,  162 , and defines a line of closure  170 , which divides the luggage case  150  into the lid shell  122  and the base shell  134 . A hinge (not shown) for pivotally connecting the lid shell  122  and base shell  134  together is positioned along the line of closure  170 . The zipper can be unzipped to allow the lid shell  122  and base shell  134  to pivot about the hinge portion to allow access to the interior. Various types of closure mechanisms, such as a latch, and hinge structures are acceptable. The luggage case  150  also may include four wheels  172  that spin about a vertical axis as shown, or may include other wheel or support structures, to allow the user to pull or tow the luggage case  150  at an angle, or to guide it along in an upright position. The luggage case  150  may include a top carry handle  174  on the top panel  160  and a side carry handle  176  on a side panel  164 ,  166 . The luggage case  150  may also include an extendable pull handle  178 . The pull handle  178  may be aligned along the outside of the rear panel  158  of the luggage case  150 . Alternatively, the pull handle  178  may also be aligned along the rear panel  158  but positioned inside the luggage case  150 . 
     A laminate  110  may be molded into an article, such as a luggage shell  120 . In the construction of the article, forming the laminate  110  in a process performed prior to and separate from molding the article may help produce an improved article, such as in one example by resulting in an article free or substantially free of air bubbles formed between the films  100 . 
     The laminate  110  may be produced by the method  200  described above. The laminate  110  may cut to a pre-determined shape and size to form a piece or sheet of laminate  110 . The luggage shell  120  may be formed by molding the laminate  110  in a molding apparatus  240 , such as a press form machine or plug mold machine. The laminate may be molded by an apparatus and/or by using a process similar, in a non-limiting example, to those described in EP Patent No. 1763430, PCT/EP2014/055514, or DE10259883 (also US2004/0118504). Regarding the process described in EP Patent No. 1763430, it should be noted that the gripping of the laminate is less particular in the molding process of the laminate  110  since the temperature at which the laminate  110  is molded may be lower, which is an advantage, and which lessens or avoids problems caused by material shrinkage that may occur at higher molding temperatures. Also compared to the process described in EP Patent No. 1763430, which discloses deep drawing self-reinforced thermoplastic composite lamina at about 170° C., the temperature range over which the laminate  110  is molded may be larger, which is an advantage because it allows for greater flexibility in molding conditions. 
     Referring to  FIG. 8 , a molding apparatus  240  may include a lining dispenser  242 , a press  244 , and a heater array  246 . In some embodiments, the lining dispenser  242  receives and distributes textile sheets, such as mesh, knit, woven, or non-woven fabric cloths, for molding with a sheet of laminate  110 . A “mesh” may be a textile sheet having openings formed therethrough, such as a warp knitted open sheet. The textile sheet may serve as a lining of an interior of a luggage shell  120  produced in the molding apparatus  240 . The textile sheet may introduce a texture, color, print, pattern, or design to the laminate  110 . The textile sheets may be received and stored in a tray  248  before being distributed to sheets of laminate  110 . Alternatively, the textile sheets may be distributed to the laminate  110  before the laminate  110  enters the molding apparatus  240 . For example, the use of a mesh as the textile sheet may impart a textured nature to the surface of the laminate  110 . 
     The press  244  includes an upper table  250  and a lower table  252 . The upper table  250  may support an upper mold, which may be a male mold  254 , of a deep drawing tool  256 . In  FIG. 8 , a portion of the upper table  250  is removed to more clearly show the male mold  254 . The lower table  252  may support a lower mold, which may be a female mold  258 , of the deep drawing tool  256 . The tables  250 ,  252  are movable relative to each other. For example, the upper table  250  may descend towards the female mold  258  along and guided by column frame  260 . The lower table  252  may move upwards toward the male mold  254 . The molds  254 ,  258  are complimentary to each other such that one mold, for example the male mold  254 , fits at least partially inside the other mold, for example the female mold  258 . 
     The press  244  further includes a sheet gripping rack  264 . The rack  264  is configured to controllably hold each laminate  110  sheet in a position between the male mold  254  and the female mold  258 . The rack  264  may also be configured to stretch or apply tension to the laminate  110  sheets. 
     The heater array  246  includes an upper heater  266  and a lower heater  268 . The heaters  266 ,  268  may be configured to slide simultaneously from the heater array  246  to a position between the male and female molds  254 ,  258 . 
     Referring to  FIG. 9 , a method  280  of making a luggage shell  120  may include a step  282  of pre-heating a laminate  110 , a step  284  of introducing the laminate  110  into a molding apparatus  240 , a step  286  of clamping and heating the laminate  110 , a step  288  of molding the laminate  110  into an article, and a step  290  of releasing the article from the molding apparatus  240 . 
     In step  282 , the laminate  110  is heated to a desired temperature. The temperature is high enough to melt or partially melt the outer layer  104  and melt or partially melt the core 102. The temperature may be about 120° C. to about 190° C., about 125° C. to about 190° C., about 130° C. to about 190° C., about 135° C. to about 190° C., about 140° C. to about 190° C., about 145° C. to about 190° C., about 150° C. to about 190° C., about 120° C. to about 185° C., about 120° C. to about 180° C., about 120° C. to about 175° C., about 120° C. to about 170° C., about 120° C. to about 165° C., or about 120° C. to about 160° C. In one example, the temperature is about 145° C. to about 170° C. In yet another example, the temperature is about 140° C. to about 165° C. 
     Instead of or in addition to melting the outer layer  104  and core  102 , the outer layer  104  and core  102 , or films  100  within or between the outer layer  104  and core  102 , may be cross-linked with each other, or otherwise bonded with each other, such as by chemical, physical, or adhesive bonding. Melting, cross-linking, and/or otherwise bonding films  100  may help produce a luggage shell  120  with improved physical properties, such as durability, resistance to deformation, and impact resistance. 
     Referring again to  FIG. 9 , in step  284 , the sheet of laminate  110  is introduced to a molding apparatus  240 . The sheet of laminate  110  may be introduced to the press  244  from a sheet supply behind (as viewed in  FIG. 8 ) the press  244 . With reference to  FIG. 8 , the laminate  110  is held between the male mold  254  and the female mold  258  by the sheet gripping rack  264 . 
     In step  286 , the laminate  110  is clamped and heated. The laminate  110 , such as the edges of a sheet, may be clamped by the sheet gripping rack  264 . The rack  264  may or may not stretch or apply tension to the laminate  110 . In the construction of the article, the application of a tension or pressure may help further consolidate the films  100  of the laminate  110  together. The tension or pressure applied to the laminate  110  may be less than about 5 bar, such as about 0.5 to about 4 bar, about 0.5 to about 3 bar, about 0.5 to about 3.5 bar, about 0.5 to about 3 bar, about 0.5 to about 2.5 bar, about 0.5 to about 2 bar, or about 1.5 to about 2 bar. 
     With reference to  FIG. 8 , heaters  266 ,  268  may heat the laminate  110  sheet while it is being held between the male and female molds  254 ,  258 . The top and/or bottom sides of the laminate may be heated. The laminate may be gripped or gripped and stretched by the sheet gripping rack  264 . The laminate  110  may be heated to a temperature high enough to melt or partially melt the outer layer  104  and melt or partially melt the core  102 . The laminate  110  may be heated to a temperature of about 120° C. to about 190° C., about 125° C. to about 190° C., about 130° C. to about 190° C., about 135° C. to about 190° C., about 140° C. to about 190° C., about 145° C. to about 190° C., about 150° C. to about 190° C., about 120° C. to about 185° C., about 120° C. to about 180° C., about 120° C. to about 175° C., about 120° C. to about 170° C., about 120° C. to about 165° C., or about 120° C. to about 160° C. In one example, the laminate is heated to a temperature of about 145° C. to about 170° C. In another example, the temperature is about 140° C. to about 165° C. 
     In some implementations, step  286  includes introduction of a textile sheet to a top or bottom side of the laminate  110 . For example, the textile sheet may be placed between the upper heater  266  and the male mold  254 . 
     Referring again to  FIG. 9 , in step  288 , the sheet of laminate  110  is molded into an article, such as a luggage shell  120 . The laminate  110  sheet may be heated while being molded. The laminate  110  may be heated to a temperature high enough to melt or partially melt the outer layer  104  and melt or partially melt the core  102 . The laminate  110  may be heated to a temperature of about 120° C. to about 190° C., about 125° C. to about 190° C., about 130° C. to about 190° C., about 135° C. to about 190° C., about 140° C. to about 190° C., about 145° C. to about 190° C., about 150° C. to about 190° C., about 120° C. to about 185° C., about 120° C. to about 180° C., about 120° C. to about 175° C., about 120° C. to about 170° C., about 120° C. to about 165° C., or about 120° C. to about 160° C. In one example, the laminate 110 is heated to a temperature of about 140° C. to about 180° C. In another example, the laminate  110  is heated to a temperature of about 145° C. to about 170° C. In another example, the temperature is about 140° C. to about 165° C. 
     The laminate  110  may be heated for about 10 seconds to about 40 seconds, about 15 seconds to about 40 seconds, about 20 seconds to about 40 seconds, about 25 seconds to about 40 seconds, about 30 seconds to about 40 seconds, about 10 seconds to about 35 seconds, about 10 seconds to about 30 seconds, about 10 seconds to about 25 seconds, or about 10 seconds to about 20 seconds. In one embodiment, the laminate  110  is heated for about 15 seconds to about 35 seconds. 
     In one example of molding, the lower mold, such as the female mold  258 , moves upward to contact the underside of the heated and stretched laminate  110  sheet. The upper mold, in this case the male mold  254 , moves downward, which forces the laminate  110  sheet into contact with most or all the mold  254 ,  258  surfaces and thereby shapes the laminate  110  sheet. If present, the textile sheet is simultaneously adhered to the laminate  110  sheet. 
     The molds  254 ,  258  may come together, or close, quickly, which may help reduce the number of wrinkles produced in the corner portions  146  of a deep drawn article, such as a luggage shell  120 . The molds  254 ,  258  may remain in the closed position for about 15-45 seconds, about 15-40 seconds, about 15-35 seconds, about 15-30 seconds, about 20-45 seconds, about 25-45 seconds, or about 30-45 seconds. In one example, the molds  254 ,  258  remain in the closed position for about 30 seconds. 
     In step  290 , the luggage shell  120  is released from the molding apparatus  240 . The laminate  110  may be heated and formed into a luggage shell  120  in about 60-120 seconds, about 60-110 seconds, about 60-100 seconds, about 60-90 seconds, about 70-120 seconds, about 80-120 seconds, or about 90-120 seconds. In one example, a laminate  110  is heated and formed into a luggage shell  120  in about 90 seconds. 
     A luggage shell  120  produced by the method  280  described above may be used in a luggage case  150  as shown in  FIG. 7   b.    
     It should be noted that all directional and/or dimensional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, front, back, rear, forward, backward, rearward, inner, outer, inward, outward, vertical, horizontal, clockwise, counterclockwise, length, width, height, depth, and relative orientation) are only used for identification purposes to aid the reader&#39;s understanding of the implementations of the disclosed invention(s), and do not create limitations, particularly as to the position, orientation, use relative size or geometry of the invention(s) unless specifically set forth in the claims. 
     Connection references (e.g., attached, coupled, connected, joined, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, connection references do not necessarily infer that two elements are directly connected and in a fixed relation to each other. 
     In some instances, components are described with reference to “ends” having a particular characteristic and/or being connected with another part. However, those skilled in the art will recognize that the disclosed invention(s) is not limited to components that terminate immediately beyond their points of connection with other parts. Thus, the term “end” should be interpreted broadly, in a manner that includes areas adjacent, rearward, forward of, or otherwise near the terminus of a particular element, link, component, part, member or the like. In methodologies directly or indirectly set forth herein, various steps and operations are described in one possible order of operation, but those skilled in the art will recognize that steps and operations may be rearranged, replaced, or eliminated without necessarily departing from the spirit and scope of the present invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made that are within the scope of the appended claims.