PRODUCT HAVING MICROPATTERN AND PROCESS FOR PRODUCTION OF SAID PRODUCT

Abstract

The present invention is in the technical field of packages, specifically surfaces of materials used for packages, and the manufacture thereof. According to the present invention, a micropattern is created on at least surface of a substrate, to obtain a material suitable for manufacturing packages.

Claims

1. A process for the production of a packaging material having a micropattern on at least one side of the material, the process comprising the steps of: a) providing a substrate on which the micropattern is to be created; and, b) treating the substrate by subjecting said substrate to force or pressure, to create a micropattern; wherein said substrate is in a non-melted state when said substrate is treated by force or pressure to obtain said micropattern; and wherein said micropattern created on the substrate mirrors the micropattern of the a surface exerting the force or pressure.

2. A process according to claim 1, wherein the force or pressure is created by a pair of forming surfaces.

3. A process according to claim 2, wherein each forming surface is shaped as a cylinder or as a cone.

4. A process according to claim 1, wherein the substrate is a paper product, a board, a film, or a laminate.

5. A process according to claim 1, wherein a temperature of said substrate in step b) is lower than a glass transition temperature of any polymer or polymers present on the surface of said substrate.

6. A process according to claim 1, wherein said micropattern is regular or irregular and wherein a depth of grooves or height of elevated areas of said micropattern is between 1-100 m.

7. A process according to claim 1, wherein a surface of the substrate, on which the micropattern is created, has been softened by heating but is in a non-melted state when the micropattern is created.

8. A packaging material obtainable according to the process of claim 1.

9. A product manufactured from a packaging material according to claim 8.

10. A product according to claim 9, wherein said product is a package for liquids.

11. A product according to claim 9, wherein said product is a cup.

12. A product according to claim 9, wherein said product is a tray.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] FIG. 1: micropattern forming die.

[0030] FIG. 2: micropattern roll alternatives.

DETAILED DESCRIPTION

[0031] The substrate on which the micropattern is to be provided is manufactured using methods known in the art.

[0032] In one embodiment of the present invention, the micropattern is created using a pair of forming cylinders (rotation die, also referred to as forming die, FIG. 1).

[0033] The forming die typically includes a smooth roll and a patterned roll, both mounted on a frame (FIG. 1). The rotating rolls form a nip which the substrate to be treated passes through and the micropattern is transferred from the roll surface onto the substrate. The intensity of treatment is determined by the adjustable nip force (F.sub.N) which is selected on basis of substrate material properties. The nip force is typically in the range of from 10 N/mm.sup.2 to 30 N/m.sup.2. Roll temperatures (T.sub.1and T.sub.2) can be adjusted to enhance the creation of micropatterns. For example, elevated roll temperatures cause softening of a polymer coating, thus making it more formable. Because of this, the nip force can be reduced to protect integrity of the base board onto which the micropattern is provided. However, the elevated temperatures are selected so that all parts of the substrate remain in a non-melted state. Typically, the elevated temperature is less than the glass transition temperature (T.sub.g) of the surface polymer of the substrate. Thus, the entire substrate is in a non-melted state. Preferably, the polymer coating is softened by heating but not melted.

[0034] The diameters of the rolls can be increased to enlarge the area under pressure in the nip as necessary. The micropattern can also be created in multiple phases by placing several consecutive forming dies in a row. If micropatterns are desired on both sides of the material, both rolls of the forming die can be patterned. The smooth cylinder can also have a soft surface layer if the material to be micropatterned requires it.

[0035] The micropattern can be provided on a roll in several different ways (FIG. 2). For example, the micropattern can be formed on the surface of the actual roll (a), on a steel plate that is wrapped around the roll (b) or on the segments that are clamped to the roll (c). Micropatterns can be created to the die surface using laser engraving, high precision machining and chemical milling. Also methods of additive manufacturing (AM) such as sintering and 3D-printing are suitable for the application.

[0036] The roll used to create the micropattern is typically in cylindrical form. Alternatively, the roll may have a conical shape which makes it applicable for example in the preparation of cupstock paperboard planks, which have curved shapes to be used in the cup-making process. Those conical rolls in nip will prepare, for example, line shaped surface micropatterns from bottom to top rim into the walls of a drinking cup. Due to the conical shape, the top rim circular length is greater than the bottom rim circular length. Therefore there will be a need to add extra micropatterned lines in to the top area of the cup planks to cover the entire surface in same surface density of patterns, equal to the bottom area. The blind spot type patterns or other non-directional (circular shape) micropatterns will fulfil all the patterned surface area without any geometrical positioned problems caused by the geometry of the paperboard planks.

[0037] The folding of a package may change the directions of micropatterned lines in the final packages if those lines are prepared only in the machine direction, i.e. as straight lines. To avoid this problem, circular micropatterns can be used, or there can be micropatterns in the surface area of the roll into the formation, that will prepare all the directed line-shaped micropatterns into the blanket in the right directions needed to ensure the material flow out of the final package in effective way. The right direction positioned micropattern line formations will help material release from the walls of the final package and flow easily out of the package through, for example, a pouring area or a hole created upon removal of a cap.

[0038] The process according to the present invention can for example be performed in the beginning of a blank feeding/material feeding step of a liquid packaging machine, a cup-making machine, a tray-forming machine or other 3-D forming device used for packaging material. In addition, the equipment required to carry out the process according to the present invention can arranged in close proximity to or even be integrated into other devices or machines such as off-coater lines, extrusion coating lines, paper machines and board machines etc. The process according to the present invention is scalable and can readily be adapted to existing processes and equipment used in the manufacture of packages.

[0039] In view of the above detailed description of the present invention, other modifications and variations will become apparent to those skilled in the art. However, it should be apparent that such other modifications and variations may be effected without departing from the spirit and scope of the invention.