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CN-117120689-B - Method for coating hollow containers containing molding syrup

CN117120689BCN 117120689 BCN117120689 BCN 117120689BCN-117120689-B

Abstract

The present disclosure relates generally to a method for providing a barrier coating on a hollow container (100) containing a molding syrup. The method includes providing a polymeric powder coating onto at least a portion of an inner surface (105 a) and an outer surface of the container (100) prior to solidifying and/or melting the powder coating. The invention also relates to a hollow container (100) formed by the method.

Inventors

  • Lars Sunderbury
  • Iselor Bouvassar
  • YAMADA SHOKO
  • Andreas Nestron
  • Christopher T. Carlson

Assignees

  • 比勒鲁迪有限公司

Dates

Publication Date
20260512
Application Date
20220325
Priority Date
20210331

Claims (14)

  1. 1. A method for providing a barrier coating on a hollow container (100) containing a molding syrup, the method comprising the steps of: Step a) providing a hollow vessel (100) comprising a molding syrup, wherein the hollow vessel (100) comprises a main portion (101) and an upper portion (102), the hollow vessel extending along a longitudinal centerline (103), wherein the longitudinal extension of the upper portion (102) corresponds to 5% to 30% of the maximum longitudinal extension of the hollow vessel (100), and wherein the longitudinal extension of the main portion (101) corresponds to 70% to 95% of the maximum longitudinal extension of the hollow vessel (100), wherein the hollow vessel comprises a bottom surface (104) and a side wall (105) extending from the bottom surface (104) to an opening (106) of the hollow vessel, the side wall (105) and the bottom surface (104) defining an outer surface and an inner surface (105 a) of the hollow vessel; Step b) depositing the polymer powder onto the inner surface (105 a) of the hollow container (100) by a spraying device (107) capable of charging the polymer powder before or during deposition of the polymer powder, wherein at least the main portion (101) of the hollow container (100) is indirectly during the polymer powder deposition, wherein the step b) of polymer powder deposition is performed in a moulding device (108) comprising an electrically conductive material, wherein the moulding device (108) comprises at least a first removable portion (108 a) and a second removable portion (108 b), wherein the first removable portion (108 a) is configured to enclose the upper portion (102) of the hollow container (100), and wherein the second removable portion (108 b) is configured to enclose the main portion (101) of the hollow container (100); Step c) of depositing polymer powder onto an outer surface of at least a portion of the upper portion (102) of the hollow container (100) by means of the spraying device (107), wherein the outer surface of the main portion (101) is free of a barrier coating comprising polymer powder, wherein the step c) of polymer powder deposition is performed by arranging the spraying device (107) at a distance d1 of 10mm to 250mm from the opening (106) of the hollow container, wherein during the step c) of polymer powder deposition the first removable portion (108 a) is removed from the molding device (108); Step d) after said step b) and said step c), treating said hollow container with heat or ultraviolet radiation under conditions such that said polymer powder melts and/or solidifies, Wherein during said step b) and said step c) of polymer powder deposition, the moisture content of said hollow vessel is 3% to 15%.
  2. 2. The method of claim 1, wherein the molding device comprises a formable conductive material.
  3. 3. The method according to claim 1 or 2, further comprising the step of: step a') after the step a) of providing the hollow vessel containing a molding slurry, the hollow vessel is conditioned to be at an ambient relative humidity of 30% to 100%.
  4. 4. The method according to claim 1 or 2, wherein, after the step a) of providing the hollow vessel containing a molding syrup, the step a') comprises adjusting the hollow vessel to be at an ambient relative humidity of 60% to 100%.
  5. 5. The method according to claim 1 or 2, wherein the step b) and the step c) of polymer powder deposition are performed simultaneously.
  6. 6. The method according to claim 1 or 2, wherein the hollow container is a bottle, wherein the upper portion (102) comprises a shoulder portion (102 a) and a neck portion (102 b), wherein the neck portion has a smaller cross-sectional area than the main portion and is configured to surround at least the opening (106) of the bottle, and wherein the shoulder portion (102 a) is arranged to taper between the main portion (101) and the neck portion (102 b).
  7. 7. A method according to claim 6, wherein at least the neck portion (102 b) of the upper portion (102) is coated in the step c) of polymer powder deposition.
  8. 8. A method according to claim 6, wherein the entire upper portion (102) of the hollow vessel (100) is coated in the step c) of polymer powder deposition.
  9. 9. The method according to claim 1 or 2, wherein step d) is performed by heating the hollow vessel (100) at a temperature of 120 ℃ to 220 ℃ for 1 to 30 minutes.
  10. 10. A hollow container (100) formed by the method according to any one of claims 1 to 9, wherein the hollow container comprises a main portion (101) and an upper portion (102), the hollow container extending along a longitudinal centre line (103), wherein the longitudinal extension of the upper portion (102) corresponds to 5% to 30% of the maximum longitudinal extension of the hollow container (100), and wherein the longitudinal extension of the main portion (101) corresponds to 70% to 95% of the maximum longitudinal extension of the hollow container (100), wherein the hollow container comprises a bottom surface (104) and a side wall (105) extending from the bottom surface (104) to an opening (106) of the hollow container, the side wall (105) and the bottom surface (104) defining an outer surface and an inner surface (105 a) of the hollow container, wherein the hollow container comprises a barrier-containing outer surface (101) of the polymer on the inner surface (105 a) of the hollow container and on at least a portion of the outer surface of the upper portion (102) of the hollow container, wherein the barrier-containing powder-containing outer surface of the polymer is free of the coated powder.
  11. 11. The hollow container according to claim 10, wherein the hollow container is a bottle, the upper portion (102) comprises a shoulder portion (102 a) and a neck portion (102 b), wherein the neck portion has a smaller cross-sectional area than the main portion and is configured to surround at least the opening (106) of the bottle, and wherein the shoulder portion is arranged to taper between the main portion and the neck portion, wherein the bottle comprises a barrier coating comprising polymer powder on an inner surface (105 a) of the bottle and on at least an outer surface of the neck portion (102 b) of the bottle.
  12. 12. A hollow container according to claim 10 or 11, wherein the barrier coating has a thickness in the range 5 to 300 μm.
  13. 13. A hollow container according to claim 10 or 11, wherein the barrier coating has a thickness in the range 20 to 100 μm.
  14. 14. A hollow container according to claim 11, wherein the outer surface of the main portion (101) of the bottle is free of barrier coating comprising polymer powder.

Description

Method for coating hollow containers containing molding syrup Technical Field The present disclosure relates generally to a method for providing a barrier coating on a hollow vessel containing a molding syrup. The method includes providing a polymeric powder coating portion onto at least a portion of the inner and outer surfaces of the container prior to solidifying and/or melting the powder coating portion. The invention also relates to a hollow container formed by the method. Background Plastic containers, packaging trays and vials are widely used for storing food products, such as flowable foods and beverages. Plastic articles can be easily molded, stretched, and produced at relatively low cost. However, the use of plastics is associated with environmental problems. In order to reduce the environmental burden, attempts have been made to replace plastic containers and vials with renewable materials such as molded syrup. Shaped pulp products such as paper containers and bottles may be formed by feeding pulp (e.g. papermaking pulp) into split molds and subsequently dewatering the pulp with heat and/or pressure, as disclosed for example in WO 16055072. Although paper is considered a sustainable packaging material, paper has a number of disadvantages compared to conventional plastics. Paper is generally more permeable to gases, grease and moisture. Prolonged exposure to moisture, which is often the case during beverage storage, may lead to degradation of the inner wall of the paper container. For this, the inner wall of the paper container may be coated with a barrier coating to protect the container from degradation due to liquid and moisture exposure. The barrier coating may also be used to control humidity, sealing properties, fragrance, etc. of the container. The barrier coating generally comprises a polymer such as a polyolefin polymer and may be applied to the inner container wall in various ways, for example by extrusion coating or as a liquid coating. In order to reduce the emission of Volatile Organic Compounds (VOC) and coating portion waste, the powder coating portion has received attention in recent years. The powder coating section is a dry, finely divided solid material commonly used for conductive metal substrates. The deposition of the powder coating section is typically achieved by electrostatic forces. For example, the powder may be charged by corona discharge and then sprayed onto a grounded substrate. Thus, a layer of powder is applied to a substrate, which is subsequently heated, so that the powder melts and forms a continuous film on the substrate. However, due to the inherently non-conductive nature of such substrates, depositing the powder coating onto the molded slurry substrate is challenging. The coated portion is not assisted by electrostatic attraction, which may result in poor adhesion of the powder to the substrate and non-uniform powder deposition. The complexity of depositing the powder coating portion increases if the product to be coated is shaped into a hollow container, such as a bottle. In this case, it may also be necessary to coat the upper outer part of the container, i.e. the part surrounding the opening of the container. This portion of the product is typically repeatedly exposed to moisture and liquid during drinking or pouring from the container. Accordingly, there is a need to provide a simplified method for applying a powder coating to a molded syrup container for storing flowable food or beverages, wherein the surface of the container that is primarily exposed to moisture and liquid is provided with a protective and durable barrier coating. Disclosure of Invention In view of the above, there is a need for an improved and simplified method for providing a powder coating on a hollow container containing a molding syrup that produces a liquid and wet barrier coating that protects the most exposed portions of the container. According to a first aspect, there is provided a method for providing a barrier coating on a hollow vessel containing a molding syrup, the method comprising: a) Providing a hollow vessel containing a molded syrup, wherein the hollow vessel comprises a main portion and an upper portion, the hollow vessel extending along a longitudinal centerline, wherein the longitudinal extension of the upper portion corresponds to 5% to 30% of the maximum longitudinal extension of the hollow vessel, and wherein the longitudinal extension of the main portion corresponds to 70% to 95% of the maximum longitudinal extension of the hollow vessel, wherein the hollow vessel comprises a bottom surface and a sidewall extending from the bottom surface to an opening of the hollow vessel, the sidewall and the bottom surface defining an outer surface and an inner surface of the hollow vessel, B) Depositing the polymer powder onto the inner surface of the hollow vessel by a spraying device capable of charging the polymer powder prior to or during deposition of the polymer pow