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CN-122003326-A - Laminate for packaging and packaging bag

CN122003326ACN 122003326 ACN122003326 ACN 122003326ACN-122003326-A

Abstract

A laminate for packaging comprising a base layer, a gas barrier layer comprising an inorganic oxide layer, and a sealing layer in this order, wherein the base layer is a biaxially stretched polypropylene resin film, the sealing layer is a polypropylene resin film, the laminate comprises 90 mass% or more of a polypropylene resin based on the total amount of the laminate, and the heat shrinkage in the MD direction and the heat shrinkage in the TD direction of the laminate, which are obtained by the following formulas (1) and (2) after heating the laminate in an oven at 150 ℃ for 15 minutes, are less than 5%. (1) MD heat shrinkage (%) = (MD length before heating-MD length after heating)/MD length before heating×100. (2) TD-direction heat shrinkage (%) = (TD-direction length before heating-TD-direction length after heating)/TD-direction length before heating×100.

Inventors

  • ISHII RIKA

Assignees

  • 凸版控股株式会社

Dates

Publication Date
20260508
Application Date
20241126
Priority Date
20231128

Claims (13)

  1. 1. A laminate for packaging, wherein, The packaging laminate is a laminate comprising a base layer, a gas barrier layer comprising an inorganic oxide layer, and a sealing layer in this order, The base material layer is a biaxially oriented polypropylene resin film, The sealing layer is a polypropylene resin film, The laminate contains 90 mass% or more of a polypropylene resin based on the total amount of the laminate, The laminate has a heat shrinkage in the MD of less than 5.0% and a heat shrinkage in the TD of less than 10% as determined by the following formulas (1) and (2) after heating in an oven at 150 ℃ for 15 minutes, (1) MD heat shrinkage (%) = (MD length before heating-MD length after heating)/MD length before heating×100 (2) TD-direction heat shrinkage (%) = (TD-direction length before heating-TD-direction length after heating)/TD-direction length before heating×100.
  2. 2. The laminate for packaging according to claim 1, wherein, The gas barrier layer includes an adhesion layer including a urethane resin or a polyvinyl alcohol resin and the inorganic oxide layer on the adhesion layer from the substrate layer side.
  3. 3. The laminate for packaging according to claim 2, wherein, The adhesive layer is formed by drying the adhesive layer-forming composition applied to the base layer at a temperature of more than 60 ℃ and not more than 130 ℃ for 1 second to 2 minutes.
  4. 4. The laminate for packaging according to claim 2, wherein, The composite elastic modulus of the cross section of the sealing layer is 3.5-6.5 GPa.
  5. 5. The laminate for packaging according to claim 1, wherein, The heat shrinkage of the substrate layer in the MD direction obtained by the formulas (1) and (2) after heating the substrate layer in an oven at 150 ℃ for 15 minutes is 3.0% or more and less than 7.0%, and the heat shrinkage in the TD direction is 3.0% or more and less than 10%.
  6. 6. The laminate for packaging according to claim 1, wherein, A substrate protective layer is also arranged on the substrate layer, The heat shrinkage of the substrate protective layer in the MD direction obtained by the formulas (1) and (2) after heating in an oven at 150 ℃ for 15 minutes is less than 7.0%, and the heat shrinkage in the TD direction is less than 10%.
  7. 7. The laminate for packaging according to claim 1, wherein, The sealing layer has a heat shrinkage in the MD of the formulas (1) and (2) of less than 2.0% and a heat shrinkage in the TD of less than 2.0% after heating in an oven at 150 ℃ for 15 minutes.
  8. 8. The laminate for packaging according to claim 1, wherein, The inorganic oxide layer comprises aluminum oxide or silicon oxide.
  9. 9. The laminate for packaging according to claim 2, wherein, The gas barrier layer further comprises a gas barrier coating layer on the inorganic oxide layer, The gas barrier coating layer is formed using a gas barrier coating layer-forming composition containing at least one selected from the group consisting of hydroxyl-containing polymer compounds, metal alkoxides, silane coupling agents, and hydrolysates thereof.
  10. 10. The laminate for packaging according to claim 1, wherein, The thickness of the substrate layer is 12-38 mu m.
  11. 11. The laminate for packaging according to claim 6, wherein, The ratio of the thickness of the substrate protection layer to the thickness of the substrate layer, that is, the thickness of the substrate layer protection layer/the thickness of the substrate layer is 0.5-2.0.
  12. 12. The laminate for packaging according to claim 1, wherein, The laminate is for use in retort pouches.
  13. 13. A packaging bag comprising the laminate for packaging according to any one of claims 1 to 12.

Description

Laminate for packaging and packaging bag Technical Field The present disclosure relates to a laminate for packaging and a packaging bag. Background A laminate comprising a biaxially stretched PET (polyethylene terephthalate) film having excellent heat resistance and toughness as a base film and a polyolefin film such as polyethylene or polypropylene as a sealing layer is known (for example, refer to patent document 1). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2017-178357 Disclosure of Invention Problems to be solved by the invention In the background of the global concern about plastic waste, there is an increasing demand for environment-friendly packaging materials in order to realize a recycling society. Regarding packaging materials, many global enterprises set targets aimed at achieving more excellent recycling of plastic resources, and various countermeasures are proposed. For example, in the united states, recycling routes from recycling to reutilization of PE (polyethylene) have been perfected, and the like, and worldwide efforts are being accelerated to recycling based on a single material (single raw material). That is, in the past, there has been a demand for a single material for a laminate for packaging, which has been improved in performance by combining various different materials. When the conventional multi-material (composite material) packaging material is made into a single material, a packaging material that is modified to a PP (polypropylene) single material may be considered as the retort packaging material from the viewpoint of sealing properties. However, such a PP-based single-material packaging material has a problem that the gas barrier property is easily deteriorated after the retort treatment, as compared with a multi-material packaging material. The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a packaging laminate which can suppress deterioration of gas barrier properties after retort treatment even when polypropylene is mainly composed. The present disclosure also aims to provide a packaging bag using the laminate for packaging. Solution for solving the problem In order to solve the above-described problems, the inventors have found that, in a laminate having a polypropylene resin film in both a base material layer and a sealing layer, it is important to suppress heat shrinkage in MD direction/TD direction after heating at a predetermined temperature, and completed the laminate of the present disclosure. That is, the present disclosure provides the following laminate for packaging and packaging bag. [1] A laminate for packaging comprising a base layer, a gas barrier layer comprising an inorganic oxide layer, and a sealing layer in this order, wherein the base layer is a biaxially stretched polypropylene resin film, the sealing layer is a polypropylene resin film, and the laminate comprises 90 mass% or more of a polypropylene resin based on the total amount of the laminate, and the laminate has a heat shrinkage in the MD direction of less than 5.0% and a heat shrinkage in the TD direction of less than 10% as determined by the following formulas (1) and (2) after heating at 150 ℃ for 15 minutes in an oven. (1) MD heat shrinkage (%) = (MD length before heating-MD length after heating)/MD length before heating×100 (2) TD-direction heat shrinkage (%) = (TD-direction length before heating-TD-direction length after heating)/TD-direction length before heating×100 [2] The laminate for packaging according to [1], wherein the gas barrier layer comprises an adhesion layer comprising a urethane resin or a polyvinyl alcohol resin and the inorganic oxide layer on the adhesion layer from the substrate layer side. [3] The laminate for packaging according to [2], wherein the adhesive layer is formed by drying the adhesive layer-forming composition applied on the base layer at a temperature of more than 60 ℃ and 130 ℃ for 1 second to 2 minutes. [4] The laminate for packaging according to [2] or [3], wherein the adhesive layer has a composite elastic modulus of 3.5 to 6.5GPa in cross section. [5] The laminate for packaging according to any one of [1] to [4], wherein the heat shrinkage of the base material layer in the MD direction obtained by the formulas (1) and (2) after heating in an oven at 150 ℃ for 15 minutes is 3.0% or more and less than 7.0%, and the heat shrinkage in the TD direction is 3.0% or more and less than 10%. [6] The laminate for packaging according to any one of [1] to [5], wherein a base material protective layer is further provided on the base material layer, and the base material protective layer has a heat shrinkage in the MD direction of less than 7.0% and a heat shrinkage in the TD direction of less than 10% as determined by the formulas (1) and (2) after heating in an oven at 150 ℃ for 15 minutes. [7] The laminate for packaging according to any one of [1]