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CN-118591499-B - Multilayer container and method for manufacturing multilayer container

CN118591499BCN 118591499 BCN118591499 BCN 118591499BCN-118591499-B

Abstract

Provided are a multilayer container which has high transparency after boiling treatment and after retort treatment, is excellent in oxygen barrier property after retort treatment, and has excellent moldability, and a method for producing the same. A multilayer container comprising a polyolefin layer comprising an acid-modified polyolefin and an acid-unmodified polyolefin, and a polyamide resin layer which is in contact with the polyolefin layer and comprises a polyamide resin (a) wherein 70 mol% or more of the structural units derived from a diamine of the polyamide resin (a) are derived from m-xylylenediamine, 30 to 60 mol% of the structural units derived from a dicarboxylic acid are derived from an alpha, omega-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, 70 to 40 mol% are derived from isophthalic acid, the melt flow rate of the acid-unmodified polyolefin is 20g/10 min or more, and the temperature X PO is the melting point +65 ℃ of the acid-unmodified polyolefin.

Inventors

  • OGURO HATSUKI
  • Kohno Koji
  • MIYABE TAKANORI

Assignees

  • 三菱瓦斯化学株式会社

Dates

Publication Date
20260508
Application Date
20221209
Priority Date
20220127

Claims (15)

  1. 1. A multilayer container, having: a polyolefin layer comprising an acid-modified polyolefin and an acid-unmodified polyolefin, and, A polyamide resin layer which is in contact with the polyolefin layer and contains a polyamide resin, The polyamide resin comprises a polyamide resin (a) which comprises a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, wherein 70 mol% or more of the diamine-derived structural unit is derived from m-xylylenediamine, 30 to 60 mol% of the dicarboxylic acid-derived structural unit is derived from an alpha, omega-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, 70 to 40 mol% is derived from isophthalic acid, The acid-unmodified polyolefin has a melt flow rate of 20g/10 minutes or more measured at a temperature of X PO ℃ under conditions of 2.16kgf according to JIS K7210-1:2014, The temperature X PO is the melting point +65℃.
  2. 2. The multilayer container according to claim 1, wherein the acid-modified polyolefin has a melt flow rate greater than that of the acid-unmodified polyolefin measured according to JIS K7210-1:2014 at a temperature of X mPO ℃ under conditions of 2.16kgf, The temperature X mPO is the melting point +55℃.
  3. 3. The multilayer container according to claim 1 or 2, wherein the content of the alkali metal salt of the higher fatty acid contained in the polyamide resin layer is less than 50 mass ppm in terms of alkali metal atomic conversion.
  4. 4. The multilayer container according to claim 1 or 2, wherein the acid-modified polyolefin comprises acid-modified polypropylene.
  5. 5. The multilayer container according to claim 1 or 2, wherein the acid-modified polyolefin has a melt flow rate exceeding 20g/10 min and 500g/10 min or less.
  6. 6. The multilayer container according to claim 1 or 2, wherein the acid-unmodified polyolefin comprises polypropylene.
  7. 7. The multilayer container according to claim 1 or 2, wherein the acid-unmodified polyolefin has a melt flow rate of 20 to 50g/10 minutes.
  8. 8. The multilayer container according to claim 1 or 2, wherein the terminal amino group concentration of the polyamide resin is 10 to 70 μeq/g.
  9. 9. The multilayer container according to claim 1 or 2, wherein the multilayer container is a multilayer injection molded container.
  10. 10. The multilayer container according to claim 1 or 2, wherein the multilayer container has a haze of 10% or less measured according to JIS K-7105.
  11. 11. The multilayer container according to claim 1 or 2, wherein haze measured according to JIS K-7105 after boiling treatment at 85 ℃ for 30 minutes is 2 times or less of haze before boiling treatment.
  12. 12. The multilayer container according to claim 1 or 2, wherein the polyamide resin (a) is an amorphous resin.
  13. 13. A method of manufacturing a multilayer container, the method comprising the steps of: The composition for forming a polyolefin layer and the composition for forming a polyamide resin layer are injected into a mold so that the polyolefin layer formed from the composition for forming a polyolefin layer is in contact with the polyamide resin layer formed from the composition for forming a polyamide resin layer, and injection molding is performed, The composition for forming a polyolefin layer comprises an acid-modified polyolefin and an acid-unmodified polyolefin, and the acid-unmodified polyolefin has a melt flow rate of 20g/10 minutes or more measured at a temperature of X PO ℃ under conditions of 2.16kgf according to JIS K7210-1:2014, The composition for forming a polyamide resin layer comprises a polyamide resin (a) containing a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, wherein 70 mol% or more of the diamine-derived structural unit is derived from m-xylylenediamine, 30 to 60 mol% of the dicarboxylic acid-derived structural unit is derived from an alpha, omega-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 70 to 40 mol% of the dicarboxylic acid-derived structural unit is derived from isophthalic acid, The temperature X PO is the melting point +65℃.
  14. 14. The method for producing a multilayer container according to claim 13, wherein the acid-modified polyolefin has a melt flow rate measured at a temperature of X mPO ℃ under 2.16kgf according to JIS K7210-1:2014 which is greater than the melt flow rate of the acid-unmodified polyolefin, The temperature X mPO is the melting point +55℃.
  15. 15. The method for producing a multilayer container according to claim 13 or 14, wherein the multilayer container is any one of claims 1 to 12.

Description

Multilayer container and method for manufacturing multilayer container Technical Field The present invention relates to a multilayer container and a method for manufacturing the multilayer container. And more particularly to a multilayer container having a polyamide resin as a barrier layer. Background Conventionally, as a method for preserving foods and medicines, canning and bottling have been used for the purpose of preventing deterioration, discoloration and discoloration of foods. However, in the case of canning or bottling, there is a problem that the heating treatment using a microwave oven cannot be performed, the filled food is not easily taken out when it is put into a dish or the like, the canning volume is large because the filled food cannot be stacked when it is discarded after use, and the disposal treatment is not satisfactory, although the effect is high with respect to various gas barrier properties such as oxygen and water vapor. As a storage container in place of this, there is a thermoformed container formed of a thermoplastic resin, which is widely used. In particular, containers made of polyolefin, particularly polypropylene (hereinafter, sometimes abbreviated as "PP"), have a melting point higher than the retort sterilization treatment temperature, and are therefore widely used as containers for preserving foods requiring retort treatment. However, PP has excellent moisture resistance, but has a property that oxygen gas easily permeates, which causes deterioration, discoloration, and discoloration of foods and medicines, and thus has insufficient performance as a container for long-term storage of foods and medicines. As a method for realizing long-term storage of foods and medicines using a container formed of PP, a method of using a multilayer container having a thermoplastic resin layer having oxygen barrier properties as an intermediate layer is known. Specifically, a coinjection molded multilayer structure is known which has a barrier layer and an outer layer laminated on both sides thereof, wherein the barrier layer is formed from a resin composition comprising an ethylene-vinyl alcohol copolymer (a) having an ethylene content of 20 to 60 mol% and a saponification degree of 90% or more, and a Melt Flow Rate (MFR) at 190 ℃ and 2160g of 3 to 20g/10 minutes, and the outer layer is formed from a resin composition comprising an unmodified polypropylene (E) and a maleic anhydride-modified polypropylene (F) having a melt viscosity lower than that of 50 to 1500ppm in terms of metal atoms, and a mass ratio [ F/(e+f) ] of the maleic anhydride-modified polypropylene (F) to the total of the unmodified polypropylene (E) and the maleic anhydride-modified polypropylene (F) of 0.025 to 0.2 (patent document 1). Prior art literature Patent literature Patent document 1 International publication No. 2018/074445 Disclosure of Invention Problems to be solved by the invention However, it is clear that the transparency of the multilayer container is poor after boiling or steaming. In addition, oxygen barrier properties after retort treatment are also required for multilayer containers. In addition, in the multilayer container, the moldability (appearance) was found to be inferior. The present invention has been made to solve the above problems, and an object of the present invention is to provide a multilayer container having high transparency after boiling treatment and after retort treatment, excellent oxygen barrier property after retort treatment, and excellent moldability, and a method for producing the same. Solution for solving the problem In view of the above problems, the present inventors have studied and as a result, have found that the above problems can be solved by using a predetermined polyamide resin as a barrier resin and blending an acid-modified polyolefin and an acid-unmodified polyolefin having a predetermined MFR into a polyolefin layer. Specifically, the above problems are solved according to the following means. <1> A multilayer container, which has: a polyolefin layer comprising an acid-modified polyolefin and an acid-unmodified polyolefin, and, A polyamide resin layer which is in contact with the polyolefin layer and contains a polyamide resin, The polyamide resin comprises a polyamide resin (a) containing a diamine-derived structural unit and a dicarboxylic acid-derived structural unit, wherein 70 mol% or more of the diamine-derived structural unit is derived from m-xylylenediamine, 30 to 60 mol% of the dicarboxylic acid-derived structural unit is derived from an alpha, omega-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, 70 to 40 mol% is derived from isophthalic acid, The acid-unmodified polyolefin has a melt flow rate of 20g/10 minutes or more as measured at a temperature of X PO ℃ and a temperature of 2.16kgf according to JIS K7210-1:2014, The aforementioned temperature X PO is the melting point +65℃. <2> The multilayer container according to <1>, wherein