Polypropylene-based sealing film for retort packaging and laminate using same

Abstract

The present invention provides a polypropylene-based film that is particularly excellent in low-temperature impact resistance and orange peel resistance, has both anti-blocking properties and heat-sealing properties, and can be widely used as a sealing film suitable for commercial large-scale retort packaging. A sealing film for retort packaging and a laminate using the same. A polypropylene-based sealing film for retort packaging comprising a resin composition containing 70 to 85% by weight of a propylene-ethylene block copolymer (a) and 15 to 30% by weight of a low-density polyethylene-based polymer (b) In the film obtained by melt-forming, the ratio of the xylene-insoluble portion at 20°C to 100% by weight of the propylene-ethylene copolymer (a) was 75 to 85% by weight, and the proportion of the insoluble portion Intrinsic viscosity ([η] H ) is 1.7~2.0dl / g, the intrinsic viscosity of the soluble part ([η] EP ) is 3.0-3.4dl / g, and the density of low-density polyethylene polymer (b) is 0.900-0.930g / cm 3 , The melt flow rate is 1-10g / 10 minutes.

Description

technical field [0001] The present invention relates to a polypropylene-based sealing film for retort packaging and a laminate using the same. Polypropylene-based sealing film for retort packaging and its laminate are widely used for high-temperature retort applications as excellent large retort packaging bags. Background technique [0002] Conventionally, an unstretched film mainly composed of a propylene / ethylene block copolymer (hereinafter sometimes referred to as CPP) has been used as a sealing film for retort packaging that is retort-sterilized at a high temperature of 120°C to 135°C. Its main method of use is as follows: Paste polyethylene terephthalate (hereinafter referred to as PET) stretched film, nylon stretched film (hereinafter sometimes referred to as ON), aluminum foil (hereinafter referred to as Al foil) Combined to make a laminate of PET film / ON / Al foil / CPP, PET film / Al foil / ON / CPP, or PET film / Al foil / CPP, and then use it as a bag. [0003] The CPP const...

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Problems solved by technology

[0010] In addition, in order to satisfy low-temperature impact resistance, heat sealability, bending whitening resistance, orange peel resistance, blocking resistance, etc. at a high level, it is proposed to adjust the amount of the rubber component in the main propylene-ethylene block copolymer and its molecular weight, and contains ethylene-α-olefin copolymers and polyethylene-based polymers (Patent Document 8), which can provide sealing films and laminates with excellent balance, but in recent years, sometimes higher levels are required Low temperature impact resistance, there are cases that cannot be satisfied

In addition, it is also proposed to adjust the rubber component amount and its molecular weight in the main propylene-ethylene block copolymer, and to include an ethylene-α-olefin copolymer, a polyethylene-based polymer, and a styrene-based block copolymer, or A proposal for a crystalline olefin block (Patent Document 9), but the impact resistance may not be satisfactory

[0011] As mentioned above, in order to cope with the increase in the size of commercial bags, the quality required for the sealing material for retort packaging has been increasingly required in recent years. For the quality of the structure disclosed so far, the low temperature impact resistance is still low. Insufficient, In addition, there is no sealing material that satisfies all properties such as orange peel resistance, blocking resistance, and heat-sealing strength at a high level and in a good balance.

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