Polypropylene Laminate Film, and Package Comprising the Same

• US 20080003386A1
• Filed: 02/18/2005
• Published: 01/03/2008
• Est. Priority Date: 03/18/2004
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Oogi, Hirokazu, Kawai, Kenji
• Granted Patent: US 7,879,439 B2
• Time in Patent Office: Days
• US Class Current: 428/35.2
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die
• CPC Class Codes: B29C 48/914 cooling drums
• CPC Class Codes: B29C 48/917 by applying pressurised gas to the surface of the flat article
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29C 55/143 firstly parallel to the direction of feed and then transversely thereto
• CPC Class Codes: B29K 2023/12 PP, i.e. polypropylene
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/10 linear, e.g. length, distance, width
• CPC Class Codes: B32B 2553/00 Packaging equipment or accessories not otherwise provided for
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 37/06 characterised by the heating method
• CPC Class Codes: B32B 37/08 characterised by the cooling method
• CPC Class Codes: B32B 37/153 at least one layer is extruded and immediately laminated while in semi-molten state
• CPC Class Codes: B32B 7/10 at least one layer having inter-reactive properties
• CPC Class Codes: Y10T 428/1334 Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]

Abstract

A wide polyolefin film may be made by high-speed film forming, which has uniform properties over its whole width and is free of thickness irregularities, and provides a packaging film applicable to large-scale production which has good gloss and bag-making property, as well as a package made from the film. A polyolefin laminate film includes an oriented base layer that is mainly made up of a polypropylene resin and a sealing layer mainly made up of a polyolefin resin which is formed on at least one surface of the base layer, which film has an effective product takeout width of not less than 5500 mm and satisfies the following relational formula of the thickness variation rate Y (%) of the film and the product takeout width X (mm) of the film:
Y≦0.001X+4.

Claims

1. A polyolefin laminate film comprising an oriented base layer mainly comprising a polypropylene resin and a sealing layer mainly comprising a polyolefin resin which is formed on at least one surface of the base layer, which film has a product takeout width of not less than 500 mm and satisfies the following relational formula of a width direction thickness variation rate Y (%) of the aforementioned film and a product takeout width X (mm) of the film:

Y≦

0.001X+4

2. The polyolefin laminate film of claim 1, which is biaxially oriented.

3. The polyolefin laminate film of claim 1 or 2, wherein the base layer comprises an antifog agent.

4. A package comprising the polyolefin laminate film of claim 3, wherein the sealing layer comprises an antifog agent migrated from the base layer.

6. A film roll of the polyolefin laminate film of claim 1, 2 or 3 wound into a roll, wherein the polyolefin laminate film of the roll has a product takeout width of not less than 500 mm and a length of not less than 2000 m.

7. The film roll of claim 6, wherein the polyolefin film of the roll shows a thickness variation Z (%) of not less than 3% and not more than 15%, when a test piece (20000 mm in the machine direction and 40 mm in the width direction) is cut out from the film in the stable region in the length direction of the film where the film property is stable and the thickness is continuously measured for 20000 mm in the machine direction.

8. A roll of the polyolefin laminate film of claim 1 wound into a roll, wherein the film has a width of not less than 5500 mm and a length of not less than 2000 m.

9. The polyolefin laminate film roll of claim 8, wherein the polyolefin film of the roll shows a thickness variation Z (%) of not less than 3% and not more than 15%, when a test piece (20000 mm in the machine direction and 40 mm in the width direction) is cut out from the film in the stable region in the length direction of the film where the film property is stable and the thickness is continuously measured for 20000 mm in the machine direction.

5. A production method of a polyolefin laminate film, which comprises melting by heating a base layer-forming resin mainly comprising crystalline polypropylene and a sealing layer-forming resin mainly comprising polyolefin having a swelling ratio smaller than that of the base layer-forming resin in separate extruders, laminating the sealing layer-forming resin on the base layer-forming resin in a T-die, melt extruding the laminate from an outlet slit of the T-die to give a film, and cooling the film to solidify into an unoriented film, wherein the unoriented film is brought into close contact with a chill roll by blowing a wind to the film-like resin at a wind pressure of 700-2200 mm H₂O with an air knife from the side opposite to the contact surface with the chill roll, while dropping said melt extruded film-like resin on the chill roll, and the unoriented film is heated to a temperature of 90-140°

C., drawn 3- to 7-fold in the longitudinal direction, cooled, led to a tenter type stretching machine, heated to a temperature of 100- 175°

C., drawn 8- to 12-fold in the width direction, heat treated at a temperature of 80-168°

C. for a relaxation treatment in the width direction by 2-15%, cooled and wound.