Sealant resin composition for use in retort film and sealant film

• US 6,110,549 A
• Filed: 04/30/1998
• Issued: 08/29/2000
• Est. Priority Date: 04/30/1997
• Status: Expired due to Term

• Current Assignee: Prime Polymer Company Limited (Mitsui Chemicals)
• Original Assignee: Mitsui Chemicals Incorporated (Mitsui Chemicals)
• Inventors: Hamada, Naoshi, Hirakawa, Sadamu, Ozaki, Shigeo
• Primary Examiner(s): KILIMAN, LESZEK B
• Application Number:
  US09/070,020
• Time in Patent Office: 852 Days
• Field of Search: 428/500, 428/521, 428/35.2, 428/35.7, 428/35.8, 428/461, 428/476.9, 428/483, 525/236, 525/240, 525/242, 525/244, 525/245
• US Class Current: 428/35.2
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: B32B 15/20 comprising aluminium or copper B32B15/016 and B32B15/017 take precedence
• CPC Class Codes: B32B 2307/558 Impact strength, toughness
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/34 comprising polyamides
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 2314/06 Metallocene or single site catalysts
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C09J 2423/00 Presence of polyolefin
• CPC Class Codes: C09J 2467/006 in the substrate
• CPC Class Codes: C09J 2477/006 in the substrate
• CPC Class Codes: C09J 7/22 Plastics; Metallised plastics
• CPC Class Codes: C09J 7/35 Heat-activated
• CPC Class Codes: C09K 2200/0617 Polyalkenes
• CPC Class Codes: C09K 2200/062 Polyethylene
• CPC Class Codes: C09K 3/10 Materials in mouldable or extrudable form for sealing or packing joints or covers filling pastes C09D5/34
• CPC Class Codes: Y10T 428/1334 : Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1355 : Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/31692 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31757 : Polymer of monoethylenically unsaturated hydrocarbon
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers

Abstract

A sealant resin composition for retort packaging film comprises a high density polyethylene as the main resin component and a linear low density polyethylene polymerized by use of the metallocene catalyst. A sealant film produced therefrom is resistant to whitening, heat fusion, heat deformation after being subjected to boiling sterilization treatment and prevent breakage of pouches produced therefrom even at low temperatures because of its high impact strength and heat sealing strength.

Claims

1. A sealant resin composition useful for retort film comprising:

(A) 60 to 90 parts by weight of high density polyethylene having a density of 0.945 to 0.970 g/cm³ and a melt flow rate of 0.5 to 10 g/10 minutes, as measured at a temperature of 190°

C., and a load of 2.16 kg, according to the method of ASTM D-1238; and

,

(B) 10 to 40 parts by weight of linear low density polyethylene prepared by using a metallocene catalyst, and having a density of 0.890 to 0.925 g/cm³ and a melt flow rate of 0.5 to 10 g/10 minutes as measured at a temperature of 190°

C., and a load of 2.16 kg, according to the method of ASTM D-1238,

wherein the total amount of (A) and (B) is 100 parts by weight.

5. A sealant resin composition according to claim 1, wherein the linear low density polyethylene (B) is an ethylene-α

-olefin copolymer comprising 95 to 99 mol % of ethylene and 1 to 5 mol % of α

-olefin having 3 to 12 carbon atoms.

6. A sealant resin composition according to claim 1, wherein a weight-average molecular weight (Mw)/a number-average molecular weight (Mn) of the linear low density polyethylene (B) is 1.5 to 3.5.

7. A sealant resin composition according to claim 1, wherein the composition is a resin composition from which a film may be molded that has a film impact strength at -5°

C. Of not less than 1,200 kg.cm/cm, a haze of not more than 5.5% after being subjected to boiling treatment at 120°

C. for 1,800 seconds, a tensile strength at break at -20°

C. of not less than 20N/15 mm and a tensile elongation at break at -20°

C. of not less than 200%.

9. The sealant resin composition according to claim 1 wherein the high density polyethylene (A) has a density of 0.950 to 0.960 g/cm³ and a melt flow rate of 1.0 to 6.0 g/10 minutes, as measured at 190°

C. and a load of 2.16 Kg, according to ASTM D-1238.

10. The sealant resin composition according to claim 1, comprising, based on 100 parts by weight of (A) and (B),to 90 parts (A) andto 40 parts (B).

11. The sealant resin composition according to claim 1, comprising, based on 100 parts by weight of (A) and (B),to 85 parts (A) andto 40 parts (B).

2. A sealant film useful for sealing a retort film, said sealant film formed from a resin composition comprising:

(A) 60 to 90 parts by weight of high density polyethylene having a density of 0.945 to 0.970 g/cm³ and a melt flow rate of 0.5 to 10 g/10 minutes, as measured at a temperature of 190°

C., and a load of 2.16 kg, according to the method of ASTM D-1238; and

,

(B) 10 to 40 parts by weight of linear low density polyethylene prepared by using a metallocene catalyst, and having a density of 0.890 to 0.925 g/cm³ and a melt flow rate of 0.5 to 10 g/10 minutes as measured at a temperature of 190°

C., and a load of 2.16 kg, according to the method of ASTM D-1238, wherein the total amount of (A) and (B) is 100 parts by weight.

3. A retort film suitable for making retort pouches comprising the sealant film according to claim 2 laminated to a substrate comprising a polyamide film, polyester film or aluminum foil.

4. A retort pouch obtained by forming the retort film of claim 3 into a pouch with the sealant film side of the retort film is in contact with itself and heat-sealing the pouch.

8. A sealant film according to claim 2, wherein the film has a film impact strength at -5°

C. of not less than 1,200 kg.cm/cm, a haze of not more than 5.5% after being subjected to boiling treatment at 120°

C. for 1,800 seconds, a tensile strength at break at -20°

C. of not less than 20N/15 mm and a tensile elongation at break at -20°

C. of not less than 200%.