BIAXIALLY ORIENTED THERMOPLASTIC POLYMER LAMINATE FILMS FOR LUGGAGE ARTICLES AND METHODS OF MAKING THE SAME
A laminate ( 110 ) of polypropylene films ( 100 ), a luggage shell ( 120 ) constructed of the laminate ( 110 ), a method ( 200 ) of making the laminate ( 110 ), and a method ( 280 ) of making the luggage shell ( 120 ) are provided. The films ( 100 ) include a core ( 102 ) and at least one outer layer ( 104 ). The laminate ( 110 ) includes a plurality of films ( 100 ). The laminate ( 110 ) may be formed by laminating a plurality of films 100 under predetermined pressure, temperature, and time conditions. The shell ( 120 ) may be formed by deep drawing a sheet of laminate ( 110 ) while applying heat and tension to the laminate ( 110 ).
1 . A luggage shell comprising:
a shell formed of a laminate said laminate consisting of a continuous sheet wherein said continuous sheet includes a plurality of films comprising:
a core of a biaxially oriented polypropylene, and
at least one outer layer of polypropylene, the outer layer having a thickness of 0.5% to 25% of the thickness of the respective film,
wherein:
the laminate has a stiffness of 3.5-5 GPa in the transverse direction and a stiffness of 1.5-3 GPa in the longitudinal direction, and
the films are laminated at a temperature of 120° C.-190° C.
2 . The luggage shell of claim 1 , wherein the laminate comprises between 10 and 50 films.
3 . The luggage shell of claim 1 , wherein the laminate comprises at least one auxiliary material constructed of a thermoplastic polymer different than the thermoplastic polymer of the core.
4 . The luggage shell of claim 1 , wherein the auxiliary material is a film or the auxiliary material is positioned within the laminate or adjacent to and exterior to the laminate.
5 . The luggage shell of claim 1 , wherein the laminate is formed by heating and compacting the films together under pressure.
6 . The luggage shell of claim 1 , wherein the auxiliary material is selected from the group consisting of: a thermoplastic olefin film, printed film, colored polypropylene and/or polyethylene film, white or colored biaxially oriented polypropylene (BOPP) film, metallized BOPP film, short or chopped polypropylene fibers, short or chopped bicomponent (BICO) fibers, knitted fabric, woven fabric, nonwoven fabric, polypropylene powder and polyethylene powder.
7 . The luggage shell of claim 1 , wherein the laminate has a stiffness of 3.5-5 GPa in the transverse direction or a stiffness of 1.5-3 GPa in the longitudinal direction.
8 . The luggage shell of claim 1 , wherein the film has a thickness of 10 μm±5%-100 μm±5%, and/or the core has a thickness of 10 μm±5%-100 μm±5%, and/or the outer layer has a thickness of 0.6 μm±5% to 2.5 μm±5% or is 2% to 7% of the thickness of the film.
9 . The luggage shell of claim 1 , wherein from at least two adjacent films to all films of the plurality of films are oriented in the same direction.
10 . The luggage shell of claim 1 , wherein at least two adjacent films of the plurality of films are oriented in the same direction.
11 . The luggage shell of claim 1 , wherein the outer layer comprises a copolymer of polypropylene and polyethylene or comprises a terpolymer of polypropylene, polyethylene, and polybutene.
12 . The luggage shell of claim 1 , wherein a melting point of the core is higher than a melting point of the outer layer.
13 . The luggage shell of claim 8 , wherein a melting point of the core is at least 10° C. higher than a melting point of the outer layer.
14 . The luggage shell of claim 1 , wherein 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.
15 . The luggage shell of claim 1 , wherein the film has a tensile strength of 60-190 MPa in the longitudinal direction or a tensile strength of 150-300 MPa in the transverse direction.
16 . The luggage shell of claim 1 , wherein the thickness of the laminate is 0.25 mm to 2.5 mm.
17 . The luggage shell of claim 1 , wherein a film is stretched in the transverse direction 4-15 times and in the longitudinal direction 3-10 times.