Paperboard-based disposable cup provided with inner layer having low PPS value

Abstract

The present invention relates to a cardboard-based disposable cup formed from a cardboard-based laminate, in which a first side of the cardboard-based laminate forming an inner surface of the cardboard-based disposable cup comprises a layer of pigment coating having a gram weight in the range of 10-20 g / m2, and a second side of the cardboard-based laminate forming an outer surface of the cardboard-based disposable cup comprises a layer of pigment coating having a gram weight in the range of 10-20 g / m2. And an outermost polymeric coating layer having a gram weight in the range of 5-25 g / m2 wherein the interior surface of the paperboard-based disposable cup has a lt as determined according to ISO 8791-4: 2007; the surface smoothness of the PPS is 3 microns.

Description

Technical Field

[0001] The present disclosure relates to paperboard-based disposable cups. More particularly, the present disclosure relates to paperboard-based disposable beverage cups suitable for serving beer. Background Art

[0002] At large events such as outdoor festivals, beer is routinely served in plastic disposable cups. However, environmental concerns and changing legislation have led to strong pressure to reduce the use of plastic disposables. However, problems with excessive foaming using current cardboard-based cups limit their potential to replace plastic beer cups.

[0003] Coating paper and paperboard with plastics is often employed to combine the mechanical properties of paperboard with the barrier and sealing properties of plastic films. Paperboard provided with even relatively small amounts of suitable plastic materials can provide the required properties to make the paperboard suitable for many demanding applications, such as liquid or food packaging boards. In liquid or food packaging boards, polyolefin coatings are frequently used as liquid barrier layers, heat seal layers and adhesives.

[0004] The foaming tendency of beer generally limits the use of disposable cups based on cardboard in beer serving. Due to excessive foaming, the filling of the cup consumes too much time compared to glass or plastic beer cups. Especially at large festivals and similar events, the filling of the cup must be completed in a very short time. A typical requirement is that the cup should be filled with 400 ml of beer within 20 seconds without overflowing. This requirement is not met with the current 2PE (double polyethylene coating layer) cardboard-based cups. For example, the cardboard cup must be filled with beer so slowly that the current automatic tap machines are not suitable without adjustments, which affects the amount of beer that can be sold.

[0005] To solve the problem of excessive foaming of beer in paperboard-based disposable cups, previous attempts have included, for example, adding surfactants to polymer coatings forming the inner surface of the cup. However, adding additional components to surfaces intended to be in contact with the beverage to be consumed is generally undesirable.

[0006] Therefore, there remains a need for an improved solution for using paperboard-based disposable cups instead of plastic disposable cups while avoiding the problem of excessive foaming in beer serving. DETAILED DESCRIPTION

[0007] It is an object of the present disclosure to provide a paperboard-based disposable cup with reduced foaming in beer serving.

[0008] It is a further object of the present disclosure to provide a paperboard-based disposable cup with reduced foaming in beer serving using only components conventionally used in paperboard-based disposable cups.

[0009] The above-mentioned objects and other objects that will be recognized by those skilled in the art from the present disclosure are achieved by various aspects of the present disclosure.

[0010] According to a first aspect illustrated herein, there is provided a paperboard-based disposable cup formed from a paperboard-based laminate,

[0011] wherein a first side of the paperboard-based laminate forming the interior surface of the paperboard-based disposable cup comprises

[0012] With 10-20g / m 2 The pigment coating layer has a grammage in the range of

[0013] With 5-25g / m 2 The outermost polymer coating layer has a grammage in the range of

[0014] The interior surface of the paperboard based disposable cup has a PPS surface smoothness of < 3 μm as determined according to ISO 8791-4:2007.

[0015] Surprisingly, it was found that the surface energy of the plate has little influence on the foam formation. Instead, it was found that the smoothness of the inner surface of the cup is a key factor influencing the foam formation. The present invention is based on the understanding that by providing a pigment coating layer below the outermost polymer coating layer forming the inner surface of the cup, a very smooth surface of the inner surface can be obtained. It has been found that a smooth surface with a PPS surface smoothness of < 3 μm measured according to ISO 8791-4:2007 significantly reduces the foaming tendency of beer served in the cup.

[0016] Paperboard generally refers to a strong, thick paper or cardboard comprising cellulose fibers used for boxes and other types of packaging. Paperboard can be bleached or unbleached, coated or uncoated, and produced in a variety of thicknesses, depending on the end-use requirements.

[0017] The paperboard substrate used in the process of the present invention typically has a thickness of at least 100 g / m 2 The weight is less than 600-1000kg / m 3 Unless otherwise stated, the grammage is measured according to standard ISO 536. Unless otherwise stated, the density is measured according to standard ISO 534. In some embodiments, the paperboard-based laminate of the paperboard-based disposable cup comprises a paperboard-based laminate having a density in the range of 150-400 g / m 2 In some embodiments, the paperboard substrate has a grammage of >1.1 m 3 / kg, preferably >1.2m 3 / kg, and more preferably >1.3m 3 / kg bulk.

[0018] Paperboard can be a single-ply material or a multi-ply material consisting of two or more plies.

[0019] In some embodiments, the paperboard substrate is a multi-ply paperboard. In some embodiments, the paperboard substrate is a multi-ply paperboard consisting of two or more plies. In some embodiments, the paperboard substrate is a multi-ply paperboard consisting of three or more plies.

[0020] The conventional type of multi-ply paperboard consists of a lower density middle ply (sometimes also called a "body ply") sandwiched between two higher density outer plies. The lower density middle ply may typically have a density of 750 kg / m 3 Below, preferably 700kg / m 3 Below 650kg / m 3 Below, 600kg / m 3 Below 550kg / m 3 Below, 500kg / m 3 Below 450kg / m 3 Below 400kg / m 3 Below or 350kg / m 3 The higher density outer layer typically has a density at least 100 kg / m higher than the middle layer. 3 , preferably at least 200 kg / m higher than the middle layer 3 density.

[0021] The paperboard substrate typically comprises kraft pulp. In some embodiments, the paperboard substrate consists of kraft pulp. In some embodiments, the paperboard substrate consists of a mixture of kraft pulp and chemothermomechanical (CTMP) pulp or other mechanical pulp. In embodiments comprising a lower density middle ply sandwiched between two higher density outer plies, the outer plies may preferably consist of kraft pulp and the middle ply may preferably consist of a mixture of kraft pulp and chemothermomechanical (CTMP) pulp or other mechanical pulp.

[0022] Due to its fibrous composition, the paperboard substrate may typically have a relatively rough surface. In some embodiments, the paperboard substrate has a PPS (Parker Print-Surf) surface smoothness of >3 μm, typically >5 μm, as measured according to ISO 8791-4:2007.

[0023] Paperboard-based laminates are packaging materials formed primarily from a paperboard substrate. In addition to the paperboard substrate, paperboard-based laminates also contain additional layers or coatings designed to improve the performance and / or appearance of the laminate.

[0024] The paperboard substrate of the paperboard-based disposable cup is provided with a pigment coating layer on its first side facing the interior of the cup. The pigment coating is a coating comprising at least one pigment and at least one binder. The pigment and binder are typically applied to the surface of the paperboard substrate in the form of a liquid, preferably aqueous dispersion, and subsequently dried to obtain the pigment coating layer.

[0025] The weight of the pigment coating layer is 10-20g / m 2 In some embodiments, the pigment coating layer has a weight of 13-15 g / m 2 The gram weight is in the range of .

[0026] In some embodiments, the pigment coating layer comprises at least one pigment and at least one binder. In some embodiments, the pigment coating layer comprises 60-70 wt % pigment and 20-30 wt % binder, based on dry weight.

[0027] In some embodiments, the pigment comprises calcium carbonate and flake pigments, preferably selected from kaolin, talc, or mixtures thereof.

[0028] The adhesive may comprise a single adhesive or a combination of adhesives. The adhesive may preferably comprise a water dispersible adhesive or a water soluble adhesive, or a combination thereof. In some embodiments, the adhesive is a latex, preferably selected from styrene acrylic (SA) latex, styrene butadiene (SB) latex, or a mixture thereof.

[0029] The pigment coating layer may preferably be applied in at least two different coating steps, wherein the coated film is dried between the steps.Thus, in some embodiments, the pigment coating layer consists of two or more sub-layers.

[0030] In some embodiments, the pigment coating layer includes a pre-coating layer formed on a paperboard substrate and a top-coating layer formed on the pre-coating layer.

[0031] In some embodiments, the pre-coating layer has a thickness of 5-15 g / m 2 In the range of 6-12 g / m 2 The gram weight is in the range of .

[0032] In some embodiments, the pre-coat layer comprises 75-95 wt % pigment and 5-25 wt % binder on a dry weight basis.

[0033] In some embodiments, the pigment in the pre-coat layer is calcium carbonate or a mixture of calcium carbonate and talc.

[0034] In some embodiments, the top coating layer has a thickness of 5-15 g / m 2 In the range of 6-9g / m 2 The gram weight is in the range of .

[0035] In some embodiments, the top coating layer comprises 20-50 wt % pigment and 50-80 wt % binder on a dry weight basis.

[0036] In some embodiments, the pigment in the top coating layer is a flake pigment selected from kaolin, talc, or a mixture thereof.

[0037] In some embodiments, the flake pigments in the top coating layer have an aspect ratio of 10 or more, and preferably 20 or more.

[0038] The pigment coating layer can also be calendered, preferably in a soft calender or a belt calender.

[0039] In some embodiments, the pigment coating layer has a PPS surface smoothness of <2 μm, preferably <1.7 μm, and more preferably <1.5 μm, as determined according to ISO 8791-4:2007.

[0040] The paperboard-based laminate is further provided with an outermost polymer coating layer formed on the pigment coating layer. The outermost polymer coating layer preferably provides liquid barrier properties and mechanical protection to the paperboard-based laminate surface. The outermost polymer coating layer is preferably also heat sealable.

[0041] The outermost polymer coating layer is preferably applied to the pigment coating layer by extrusion coating. Extrusion coating is a process in which a molten plastic material is applied to a substrate to form a very thin, smooth and uniform layer. That is, in a preferred embodiment, the outermost polymer coating layer is an outermost extrusion-coated polymer layer.

[0042] The outermost polymer coating layer substrate may comprise any thermoplastic polymer conventionally used in protective and / or heat-sealable layers in paperboard based packaging laminates in general or polymers used in liquid or food packaging boards in particular. Examples include polybutylene succinate (PBS), poly(butylene succinate-co-adipate) (PBSA), polycaprolactone (PCL), poly(glycolic acid) (PGA), polyvinyl alcohol (PVOH), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), starch, thermoplastic starch (TPS), cellulose acetate (CA), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene furanoate (PEF), polypropylene (PP), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 10.10 (PA10.10) and polyamide 6.10 (PA6.10). Preferred examples include polyethylene (PE), polyethylene terephthalate (PET), polyethylene furanoate (PEF), polypropylene (PP), polyhydroxyalkanoate (PHA), polylactic acid (PLA), polyglycolic acid (PGA), polyvinyl alcohol (PVOH) and starch. Polyethylene, especially low-density polyethylene (LDPE) and high-density polyethylene (HDPE), are the most common and versatile polymers for liquid or food packaging boards. In some embodiments, the outermost polymer coating layer comprises polyethylene, preferably low-density polyethylene (LDPE). The polymer used is preferably made of renewable materials.

[0043] Alternatively, the outermost polymer coating layer is applied on the pigment coating layer by liquid coating method.In some embodiments, polymer is applied in the form of dispersion, latex or solution of polymer in liquid carrier, and is dried subsequently to form the outermost polymer coating layer.The outermost polymer coating layer applied by liquid coating method can be applied by contact or non-contact coating method.The example of useful coating method includes but not limited to rod coating, curtain coating, film pressing coating, cast coating, transfer coating, sizing pressing coating, flexographic printing coating, gate roller coating, double roller HSM coating, scraper coating such as short residence time scraper coating, jet coating machine coating, spray coating, gravure coating or reverse gravure coating.In a preferred embodiment, liquid dispersion is applied by scraper coating.

[0044] The polymer applied in the form of a dispersion, latex or solution of the polymer in a liquid carrier can, for example, be selected from latex (e.g. styrene-acrylate (SA) latex, styrene-butadiene (SB) latex or mixtures thereof), starch, carboxymethyl cellulose (CMC), polyolefins (e.g. polyethylene (PE), polypropylene (PP) or copolymers of polyethylene and polypropylene), polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB) and polylactic acid (PLA).

[0045] In some embodiments, the outermost polymer coating layer further comprises 1-20 wt % pigment on a dry weight basis.

[0046] The weight of the outermost polymer coating layer is 5-25g / m 2 In some embodiments, the outermost polymer coating layer has a weight of 9-15 g / m 2 The gram weight is in the range of .

[0047] The outermost polymer coating layer has a very smooth surface due to the underlying pigment coating layer. More specifically, the outermost polymer coating layer forming the interior surface of the paperboard based disposable cup has a PPS surface smoothness of < 3 μm as measured according to ISO 8791-4:2007.

[0048] In some embodiments, the interior surface of the paperboard-based disposable cup has a PPS surface smoothness of <2 μm, preferably <1.9 μm, and more preferably <1.8 μm, as measured according to ISO 8791-4:2007.

[0049] The second side of the paperboard-based laminate forming the exterior surface of the paperboard-based disposable cup may also be provided with one or more coating layers, for example to improve moisture resistance or printability of the exterior surface of the paperboard-based disposable cup.

[0050] In some embodiments, the second side of the paperboard-based laminate forming the exterior surface of the paperboard-based disposable cup comprises a 2 The pigment coating layer has a gram weight in a range of.

[0051] In some embodiments, the second side of the paperboard-based laminate forming the exterior surface of the paperboard-based disposable cup comprises an outermost extrusion-coated polymer layer, preferably a polyethylene layer, having a molecular weight of 5-50 g / m 2 The gram weight is in the range of .

[0052] The paperboard-based disposable cup is generally intended for serving beverages, and in particular beer.In some embodiments, the paperboard-based disposable cup has an inner volume in the range of 50-2000 ml.

[0053] According to a second aspect illustrated herein, there is provided a method for manufacturing a paperboard-based disposable cup, the method comprising:

[0054] a) Making paperboard-based laminates by

[0055] i. Provide paperboard substrate,

[0056] ii. applying a liquid dispersion comprising a pigment and a binder to a first side of a paperboard substrate, and drying the applied liquid dispersion to obtain a pigment coating layer having a viscosity of 10-20 g / m 2 and a PPS surface smoothness of <2 μm, preferably <1.7 μm, and more preferably <1.5 μm, as determined according to ISO 8791-4:2007,

[0057] iii. applying a polymer layer to the pigment coating layer by extrusion or liquid coating method to obtain an outermost polymer coating layer, the outermost polymer coating layer having a g / m 2 and a PPS surface smoothness of <3 μm as determined in accordance with ISO 8791-4:2007; and

[0058] b) converting the paperboard-based laminate into a paperboard-based disposable cup, wherein the outermost polymer coating layer forms the inner surface of the paperboard-based disposable cup.

[0059] The paperboard substrate, the pigment coating layer and the outermost polymer coating layer may be further defined as described above with respect to the first aspect.

[0060] In some embodiments, the pigment coating layer is formed by applying a first liquid dispersion containing a pigment and a binder to a first side of a paperboard substrate and drying the applied first liquid dispersion to obtain a pre-coating layer, and applying a second liquid dispersion containing a pigment and a binder to the pre-coating layer and drying the applied second liquid dispersion to obtain a top coating layer on the pre-coating layer. The composition and grammage of the pre-coating layer and the top coating layer may be the same or different. The composition and grammage of the pre-coating layer and the top coating layer may be further defined as described above with respect to the first aspect.

[0061] The liquid dispersion can be applied by contact or non-contact coating methods. Examples of useful coating methods include, but are not limited to, rod coating, curtain coating, film press coating, cast coating, transfer coating, size press coating, flexographic printing coating, gate roller coating, double roller HSM coating, blade coating such as short residence time blade coating, jet coater coating, spray coating, gravure coating or reverse gravure coating. In a preferred embodiment, the liquid dispersion is applied by blade coating.

[0062] The polymer applied in iii. is preferably applied by extrusion coating. The surface of the cooling cylinder used in extrusion coating should preferably be smooth. In some embodiments, the cooling cylinder used in extrusion coating is chrome-plated. In some embodiments, the cooling cylinder used in extrusion coating is highly polished. In some embodiments, the surface of the cooling cylinder used in extrusion coating has an average roughness (Ra) of <0.25 μm, preferably <0.10 μm, and more preferably <0.025 μm. In some embodiments, the cooling cylinder used in extrusion coating is a "GLF" type. In some embodiments, the cooling cylinder used in extrusion coating is a mirror finish or mirror groove type.

[0063] Generally, although products, polymers, materials, layers and processes are described as "comprising" various components or steps, the products, polymers, materials, layers and processes may also "consist essentially of" or "consist of" the various components and steps.

[0064] Although the present invention has been described with reference to various exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the basic scope thereof. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as being considered the best mode for carrying out the present invention, and the present invention will include all embodiments within the scope of the appended claims.

[0065] Example

[0066] Example - Beer Pour Test

[0067] The equipment used in the pour test involves a laboratory stand and two fixtures. An opened 330ml beer can containing lager beer is horizontally connected to the upper fixture. A 75ml glass funnel is connected to the lower fixture to simulate the mouth of a beer tap. The final pouring angle is adjusted so that the 330ml beer can is emptied in 17 seconds. A stopwatch is used to confirm the time. The time is selected based on such an assumption: a commercial beer tap fills a cup with 400ml of beer in 20 seconds. The distance between the bottom of the beer can and the top of the glass funnel is about 30mm in the setting. The temperature of the beer is 4°C in the experiment.

[0068] A 500ml disposable plastic (PP) beer cup was used as a reference sample. A 500ml disposable plastic beer cup was placed below the outlet of a glass funnel. The distance between the outlet and the inner wall of the cup was about 30-40mm. With the help of a plastic carrier placed below the cup, the cup was placed at an angle of 20° relative to a flat table surface. The beer first came into contact with the cup wall, rather than with the bottom of the cup as in a typical beer tap setting. The number of parallel determinations was three times.

[0069] The same procedure was then repeated using different types of coated paperboard as the inner surface of the cup, as set forth in Table 1. The paperboards included three different standard polymer coated paperboards and two different paperboards according to the proposed inventive concept. The inner wall of the plastic cup was covered with the paperboard substrate before the pouring test. After immediately removing the paperboard covering inside the cup, the height of the foam and liquid matrix was marked on the outer surface of the cup. The entire pouring test was recorded using a video camera to ensure the quality of the recording of the beer foaming behavior.

[0070] The properties and phenomena tracked during the experiment included: i) the height of the foam layer formed, ii) the structure of the foam (lamellar or non-lamellar) and iii) the potential occurrence of excessive foaming. The presence of lamellar foam is theoretically desirable because it indicates rapid degradation of the foam and therefore less risk of excessive foaming. In addition, the PPS (Parker Print-Surf) surface smoothness of each internal surface was determined according to ISO 8791-4:2007 (1.0 MPa).

[0071] Table 1.

[0072]

[0073] Notice:

[0074] -> 10 cm of foam means that the overbubbling is so intense that the initial height of the foam layer cannot be determined. 10 cm is still measurable and the overbubbling is not severe.

Claims

1. A paperboard-based disposable cup, the paperboard-based disposable cup being formed from a paperboard-based laminate, in, A first side of the paperboard-based laminate forming the interior surface of the paperboard-based disposable cup comprises With 10-20g / m 2 The pigment coating layer has a grammage in the range of With 5-25g / m 2 The outermost polymer coating layer has a grammage in the range of The interior surface of the paperboard based disposable cup has a PPS surface smoothness of < 3 μm as determined according to ISO 8791-4:2007.

2. The paperboard-based disposable cup according to claim 1, wherein the paperboard substrate has a PPS surface smoothness of >3 μm as measured according to ISO 8791-4:2007.

3. A paperboard-based disposable cup according to any one of the preceding claims, wherein the pigment coating layer has a g / m 2 The gram weight is in the range of .

4. The paperboard-based disposable cup according to any one of the preceding claims, wherein the pigment coating layer comprises at least one pigment and at least one binder.

5. The paperboard-based disposable cup according to any one of the preceding claims, wherein the pigment coating layer comprises 60-70 wt% pigment and 20-30 wt% binder, based on dry weight.

6. The paperboard-based disposable cup according to any one of claims 4-5, wherein the pigment comprises calcium carbonate and flake pigments, preferably selected from kaolin, talc or mixtures thereof.

7. The paperboard-based disposable cup according to any one of claims 4 to 6, wherein the adhesive is latex, preferably selected from styrene acrylic (SA) latex, styrene butadiene (SB) latex or a mixture thereof.

8. The paperboard-based disposable cup according to any one of the preceding claims, wherein the pigment coating layer consists of two or more sub-layers.

9. The paperboard-based disposable cup according to claim 8, wherein the pigment coating layer comprises a pre-coating layer formed on the paperboard substrate and a top-coating layer formed on the pre-coating layer.

10. The paperboard-based disposable cup according to claim 9, wherein the pre-coating layer has a thickness of 5-15 g / m 2 In the range of 6-12g / m 2 The gram weight is in the range of .

11. The paperboard-based disposable cup according to any one of claims 9-10, wherein the pre-coating layer comprises 75-95 wt% pigment and 5-25 wt% binder on a dry weight basis.

12. The paperboard-based disposable cup according to any one of claims 9 to 11, wherein the pigment in the pre-coating layer is calcium carbonate or a mixture of calcium carbonate and talc.

13. The paperboard-based disposable cup according to any one of claims 9 to 12, wherein the top coating layer has a thickness of 5 to 15 g / m 2 In the range of 6-9g / m 2 The gram weight is in the range of .

14. The paperboard-based disposable cup according to any one of claims 9 to 13, wherein the top coating layer comprises 20-50 wt% pigment and 50-80 wt% binder on a dry weight basis.

15. The paperboard-based disposable cup according to any one of claims 9 to 14, wherein the pigment in the top coating layer is a flake pigment selected from kaolin, talc or a mixture thereof.

16. The paperboard-based disposable cup according to claim 15, wherein the flake pigments in the top coating layer have an aspect ratio of above 10, and preferably above 20.

17. The paperboard-based disposable cup according to any one of the preceding claims, wherein the pigment coating layer has a PPS surface smoothness of <2 μm, preferably <1.7 μm, and more preferably <1.5 μm, measured according to ISO 8791-4:2007.

18. The paperboard-based disposable cup according to any one of the preceding claims, wherein the interior surface of the paperboard-based disposable cup has a PPS surface smoothness of <2 μm, preferably <1.9 μm, and more preferably <1.8 μm, measured according to ISO 8791-4:2007.

19. A method for making a paperboard-based disposable cup, the method comprising: a) Making paperboard-based laminates by i. Provide paperboard substrate, ii. applying a liquid dispersion comprising a pigment and a binder to a first side of a paperboard substrate, and drying the applied liquid dispersion to obtain a pigment coating layer having a viscosity of 10-20 g / m 2 and a PPS surface smoothness of <2 μm, preferably <1.7 μm, and more preferably <1.5 μm, as determined according to ISO 8791-4:2007, iii. applying a polymer coating layer onto the pigment coating layer to obtain an outermost polymer coating layer having a thickness of 5-25 g / m 2 and a PPS surface smoothness of <3 μm as determined in accordance with ISO 8791-4:2007; and b) converting the paperboard-based laminate into a paperboard-based disposable cup, wherein the outermost polymer coating layer forms the inner surface of the paperboard-based disposable cup.

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