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CN-121986024-A - Multilayer polyethylene film

CN121986024ACN 121986024 ACN121986024 ACN 121986024ACN-121986024-A

Abstract

The multilayer polyethylene film comprises at least three layers, namely a first layer, a second layer and a third layer, wherein the softening point of the second layer is higher than that of the first layer and higher than that of the third layer, the ratio of the thickness of the second layer to the total thickness of the first layer and the third layer is 1-3, the temperature shown by the maximum value of a melting peak observed in the differential scanning calorimeter measurement of the multilayer polyethylene film exceeds 129 ℃ and is less than 134 ℃, and the absolute value of the molecular orientation degree of the multilayer polyethylene film is less than 1.07.

Inventors

  • KATO RYOJI
  • Wu Jingliao
  • Yuki Kamekawa
  • Yamamura Takahide
  • YAMASHITA YUUKI

Assignees

  • 凸版控股株式会社
  • 塔玛波里股份有限公司

Dates

Publication Date
20260505
Application Date
20240719
Priority Date
20230727

Claims (10)

  1. 1. A multilayer polyethylene film comprising at least three layers in order of a first layer, a second layer and a third layer, The softening point of the second layer is higher than the softening point of the first layer and higher than the softening point of the third layer, The ratio of the thickness of the second layer to the total thickness of the first layer and the third layer is 1-3, The temperature indicated by the maximum value of the melting peak observed in the differential scanning calorimetric measurement of the multilayer polyethylene film exceeds 129 ℃ and is less than 134 ℃, The multilayer polyethylene film has an absolute value of molecular orientation of less than 1.07.
  2. 2. The multilayer polyethylene film according to claim 1, wherein the polyethylene resins comprising the first, second and third layers each have a melt flow rate of 1.5 g/10 min or less under a load of 2.16 kg at 190 ℃.
  3. 3. The multilayer polyethylene film according to claim 1, wherein when the melt flow rates of the polyethylene resins constituting the first, second and third layers under a load of 2.16 kg at 190 ℃ are set to MFR 1 、MFR 2 and MFR 3 , respectively, MFR 1 -MFR 2 +.0.55 g/10 min and MFR 3 -MFR 2 +.0.55 g/10 min are set.
  4. 4. The multilayer polyethylene film according to claim 1, wherein when the melt flow rates of the polyethylene resins constituting the first, second and third layers under a load of 2.16 kg at 190 ℃ are set to MFR 1 、MFR 2 and MFR 3 , respectively, MFR 2 -MFR 1 +.0.55 g/10 min and MFR 2 -MFR 3 +.0.55 g/10 min are set.
  5. 5. The multilayer polyethylene film according to any one of claims 1 to 4, wherein the polyethylene resin comprising the first and third layers has a density of less than 0.945 g/cm 3 .
  6. 6. The multilayer polyethylene film according to any one of claims 1to 4, wherein the thickness of the first layer and the third layer is 1 μιη or more and 10 μιη or less.
  7. 7. The multilayer polyethylene film according to any one of claims 1 to 4, wherein the thickness of the second layer is 8 μιη or more and 30 μιη or less.
  8. 8. The multilayer polyethylene film according to any one of claims 1 to 4, wherein the softening point of the first and third layers is 120 ℃ or more and 160 ℃ or less.
  9. 9. The multilayer polyethylene film according to any one of claims 1 to 4, wherein the softening point of the second layer is 125 ℃ or more and 170 ℃ or less.
  10. 10. The multilayer polyethylene film according to any one of claims 1 to 4, wherein the multilayer polyethylene film has an absolute value of molecular orientation degree of 1 or more.

Description

Multilayer polyethylene film Technical Field The present invention relates to a multilayer polyethylene film. Background Polyethylene films are used as packaging materials because they are excellent in flexibility, transparency, moisture resistance, chemical resistance, and the like and are inexpensive. In recent years, with the rising demand for recycling society, recycling of packaging materials has been attempted. One of the methods for recycling the packaging material in which the respective materials are compounded is to re-separate the packaging material into the respective materials. However, since a laminate used in a packaging material is given a predetermined strength, thermal, chemical, and mechanical methods are required to separate the respective materials, and the separated materials are required to be distinguished by differences in specific gravity, spectroscopy, and the like, which is not efficient. In order to recycle packaging materials more efficiently, a single material is being studied in which a laminate is formed from raw materials of the same system and the laminate is reused as an integral raw material. For example, patent document 1 discloses a laminate comprising a base material, an adhesive layer, and a heat seal layer, wherein the base material and the heat seal layer comprise polyethylene, at least one of the base material and the adhesive layer and the heat seal layer and the adhesive layer comprises a vapor deposited film, and the base material comprises a stretched film, and a packaging material having sufficient strength, heat resistance, barrier properties, and excellent recyclability, which can be applied as a packaging material or the like. [ Prior Art literature ] [ Patent literature ] Patent document 1 Japanese patent laid-open No. 2020-55157 Disclosure of Invention [ Problem to be solved by the invention ] In order to develop a laminate into a single material, the present inventors have studied and as a result, depending on the type of polyethylene resin constituting each layer of the polyethylene film and the thickness of each layer, wrinkles may occur in the polyethylene film, and it is difficult to form a functional layer such as a deposition layer or a coating layer. Further, by stretching the polyethylene film, the occurrence of wrinkles in the polyethylene film can be suppressed, but there is a tendency that the adhesion is poor when the polyethylene film is bonded to various films such as a sealant film. Accordingly, an object of one aspect of the present invention is to provide a multilayer polyethylene film which is less likely to cause wrinkles and has excellent adhesion. [ Means of solving the problems ] One aspect of the present invention relates to a multilayer polyethylene film comprising at least three layers, a first layer, a second layer, and a third layer in this order, wherein the softening point (probe-down temperature) of the second layer is higher than the softening point (probe-down temperature) of the first layer and higher than the softening point (probe-down temperature) of the third layer, the ratio of the thickness of the second layer to the total thickness of the first layer and the third layer is 1 to 3, the temperature indicated by the maximum value of the melting peak observed in differential scanning calorimetric measurement of the multilayer polyethylene film exceeds 129 ℃ and is less than 134 ℃, and the absolute value of the molecular orientation degree of the multilayer polyethylene film is less than 1.07. The multilayer polyethylene film is excellent in adhesion, and is less likely to cause wrinkles by adjusting the size relationship and thickness ratio of softening points (probe lowering temperatures) of the layers, and by adjusting the temperature and molecular orientation degree shown by the maximum value of the melting peak of the multilayer polyethylene film to a predetermined range, in addition to forming the multilayer structure. In the multilayer polyethylene film, the melt flow rate of the polyethylene resin constituting the first layer, the second layer, and the third layer may be 1.5 g/10 min or less under a load of 2.16 kg at 190 ℃. In the multilayer polyethylene film, when the Melt Flow Rates (MFR) of the polyethylene resins constituting the first, second and third layers are set to MFR 1、MFR2 and MFR 3 at 190 ℃ under a load of 2.16 kg, MFR 1-MFR2 +.0.55 g/10 min and MFR 3-MFR2 +.0.55 g/10 min, respectively. Or may be MFR 2-MFR1 +.0.55 g/10 min and MFR 2-MFR3 +.0.55 g/10 min. By using a polyethylene resin having a melt flow rate in a specific range as the polyethylene resin constituting each layer of the multilayer polyethylene film, wrinkles are less likely to occur and adhesion is more excellent. In the multilayer polyethylene film, the polyethylene resin constituting the first and third layers may have a density of less than 0.945 g/cm 3. When a polyethylene resin having a density in a specific range is used as the