BE1025436B1 - IMPROVED THREE-LAYER PAPER-LIKE PLASTIC FILM AND METHOD FOR MANUFACTURING IT - Google Patents

Abstract

The present invention relates to a three-layer paper-like plastic film for packaging fatty foods. The film comprises an outer layer, an inner layer, and an intermediate layer between the outer and inner layers. Each of the three layers comprises high density polyethylene. The interlayer also comprises calcium carbonate and an interlayer dye. Preferably, the film comprises at least 51 weight percent of high-density polyethylene. Preferably, the intermediate layer comprises a weight percentage of calcium carbonate that is greater than the weight percentage of calcium carbonate in each of the outer and inner layers.

Description

IMPROVED THREE-LAYER PAPER-LIKE PLASTIC FILM AND METHOD FOR MANUFACTURING IT

TECHNICAL DOMAIN

The invention relates to a three-layer paper-like plastic film comprising high-density polyethylene (HDPE), calcium carbonate (CaCO3), and a colorant.

BACKGROUND ART

A paper-like plastic film combines the advantages of a plastic film with regard to tensile strength, tear resistance, puncture resistance, impermeability to certain substances and peelability with the appearance, the feeling of touch, and the pliability of paper. Examples of paper-like plastic films can be found in, inter alia, US 5,667,872, US 6,054,223, DE 20 2014 007 536 U1, US 2015/247 017 A1, and WO 2014/169 448 A1.

A problem with known compositions for paper-like plastic films is that they still have relatively high fat absorption and / or permeability, certainly at room temperature. The tendency for increasing the dilution of plastic films due to environmental, cost and raw material depletion causes lack of firmness and an increased impact of said fat absorption and / or permeability.

It is an object of the present invention to find a solution to at least some of the aforementioned problems.

SUMMARY OF THE INVENTION

In a first aspect, the present invention relates to a three-layer paper-like plastic film for packaging fatty foods, according to claim 1.

In a second aspect, the present invention relates to a method for manufacturing a three-layer paper-like plastic film according to the first aspect of the present invention, as described in claim 10.

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In a third aspect, the present invention relates to a use of a three-layer paper-like plastic film according to the first aspect of the present invention, as described in claim 11.

The invention is advantageous because the presence of high density polyethylene (HDPE) in each of the three layers of the three layer film provides a higher strength density ratio, a higher tensile strength, a higher tear resistance and a reduced permeability compared to prior art films with a equal film thickness.

DETAILED DESCRIPTION

The invention relates to a three-layer paper-like plastic film, a method of manufacturing it, and a use thereof. The invention has been summarized in the section provided for this purpose. In the following, the invention is described in detail, preferred embodiments are explained, and the invention is illustrated with reference to examples.

Unless defined otherwise, all terms used in the description of the invention, including technical and scientific terms, have the meaning as generally understood by those skilled in the art of the invention. For a better assessment of the description of the invention, the following terms are explicitly explained.

"One", "de" and "it" in this document refer to both the singular and the plural unless the context clearly presupposes otherwise. For example, "a segment" means one or more than one segment.

When "about" or "round" is used in this document for a measurable quantity, a parameter, a duration or moment, and the like, variations are meant of +/- 20% or less, preferably +/- 10% or less, more preferably +/- 5% or less, even more preferably +/- 1% or less, and even more preferably +/- 0.1% or less than and of the quoted value, insofar as such variations of are applicable in the described invention. However, this should be understood to mean that the value of the quantity in which the term "about" or "round" is used is itself specifically disclosed.

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The terms "include", "comprising", "provided with", "contain", "containing", "include", "including", "withhold", "withhold" are "synonymous" and are inclusive or open terms that what follows to indicate, and which do not preclude or prevent the presence of other components, features, elements, members, steps, known from or described in the prior art.

The citation of numerical intervals by the end points includes all integers, fractions and / or real numbers between the end points, including these end points.

A non-exhaustive example list of plastics includes acrylonitrile butadiene styrene (ABS), ethylene ethyl acrylate (EEA), ethylene methyl acrylate (EMA), ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), phenol formaldehyde (PEN), high impact polystyrene (HIPS) , high density polyethylene (HDPE), ionomers (ION), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), melamine formaldehyde (MF), polyamide (PA), polybutylene (PB), polycarbonate (PC), polyepoxide (epoxy), polyester (PES) ), polyetheretherketone (PEEK), polyetherimide (PEI), polyethylene (PE), polyethylene terephthalate (PET), polyimide (PI), polylactide (polylactic acid (PLA)), polymethyl methacrylate (PMMA), polypropylene (PP), polystyrene ( PS), polytetrafluoroethylene (PTFE), polyurethane (PU), polyvinyl acetate (PVAC), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), styrene acrylonitrile (SAN), and urea formaldehyde (UF).

The term "colorant" includes pigments and dyes. A non-exhaustive example list of dyes includes alizarin, aluminum powder, aniline black, anthraquinone, azo dyes, azomethine-azo, azo compounds, bronze powder, quinacridone, chromium oxide, chromic acid, dioxazine, a spinel-shaped calcination, phthalocyanine (eg phthalocyanine blue, phthalocyanine green), iron hydroxide, iron oxide, indigo, izoindolinone, carmine, carbon pigments, perinone, perylene, Prussian blue, talc, thioindigo, triphenylmethane, titanium dioxide and vermilion. Depending on the material to be colored, the dye can also be added with one or more additives, such as, for example, antioxidants, film-forming resins, surfactants, organic solvents, ultraviolet absorbents, flame retardants and plasticizers. A non-exhaustive example list of dye-containing concentrates includes Ampacet LR-92010 (red), Ampacet LR-92011 (blue), Ampacet LR-92396 (blue), Ampacet LR-92397 (green), Ampacet LR-92398 (yellow), Milliken Clear Tint Amber 9808, Milliken Clear Tint Blue 9805, Milliken Clear Tint Green 9807, Milliken Clear Tint Red 9803, Schulman Polybatch Blue P4021, Schulman Polybatch Blue P4535, Schulman

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Polybatch Brown P1028F, Schulman Polybatch Green P3510F, Schulman Polybatch Orange P10307, Schulman Polybatch Red P50346 and Schulman Polybatch Yellow P2214F.

In a first aspect, the present invention relates to a three-layer paper-like plastic film for packaging fatty foods. The three-layer film comprises an outer layer comprising high-density polyethylene (HDPE), an inner layer comprising HDPE, and an intermediate layer positioned between the outer layer and the inner layer, the intermediate layer comprising HDPE, calcium carbonate and an intermediate layer dye.

In a preferred embodiment, the film comprises at least 51 weight percent of HDPE. Preferably, the film comprises at least 52 weight percent of HDPE. More preferably, the film comprises at least 53 weight percent of HDPE. Even more preferably, the film comprises at least 54 weight percent of HDPE. Most preferably, the film comprises at least

54.4 weight percent of HDPE.

The presence of HDPE in each of the three layers of the film provides a higher strength-to-density ratio, a higher tensile strength and a reduced permeability compared to prior art films with the same film thickness. Moreover, light can also be made less easy by a film with a higher HDPE content, which also benefits the storage of foodstuffs.

The three-layer paper-like plastic film comprises an average film thickness. In a preferred embodiment, the intermediate layer comprises an average thickness of at least 20% and at most 60% of the average film thickness and each of the outer layer and the inner layer comprises an average thickness of at least 20% and at most 40% of the average film thickness. Preferably, the intermediate layer comprises an average thickness of at least 25% and at most 55% of the average film thickness and each of the outer layer and the inner layer comprises an average thickness of at least 22.5% and at most 37.5% of the average film thickness. More preferably, the intermediate layer comprises an average thickness of at least 30% and at most 50% of the average film thickness and each of the outer layer and the inner layer comprises an average thickness of at least 25% and at most 35% of the average film thickness. Even more preferably, the intermediate layer comprises an average thickness of at least 33% and at most 47% of the average film thickness and each of the outer layer and the inner layer comprises an average thickness of at least 26.5% and at most 33.5% of the average film thickness. Even more preferably, the intermediate layer comprises an average thickness of

BE2017 / 5525 at least 36% and at most 44% of the average film thickness and each of the outer layer and the inner layer comprises an average thickness of at least 28% and at most 32% of the average film thickness. Most preferably, the intermediate layer comprises an average thickness of at least 37% and at most 43% of the average film thickness, such as 37%, 38%, 39%, 40%, 41%, 42%, 43% of the average film thickness, or similar which value in between, and each of the outer layer and the inner layer comprises an average thickness of at least 28.5% and at most 31.5% of the average film thickness, such as 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5% of the average film thickness, or any value in between.

In a preferred embodiment, the intermediate layer comprises at least 44 weight percent of HDPE. The intermediate layer preferably comprises at least 45% by weight of HDPE. Most preferably, the intermediate layer comprises at least 46 weight percent of HDPE.

In a preferred embodiment, each of the inner layer and the outer layer comprises at least 58 weight percent of HDPE. Preferably, each of the inner layer and the outer layer comprises at least 59 weight percent of HDPE. Most preferably, each of the inner layer and the outer layer comprises at least 60 weight percent of HDPE.

This is advantageous because in this preferred embodiment the intermediate layer comprising calcium carbonate is sufficiently shielded from contact with the foodstuff by means of the inner layer. Moreover, the film can be used on both sides. Due to the specific composition, the film is virtually non-absorbent and / or permeable.

In a preferred embodiment, the film comprises bimodal HDPE. Bimodal HDPE comprises two peaks in component distribution as a function of molecular weight. Preferably, the molecular weights at which the peaks occur are configured to obtain a substance with both improved polymer processing and improved mechanical properties. The intermediate layer preferably comprises bimodal HDPE. The inner layer preferably comprises bimodal HDPE. The outer layer preferably comprises bimodal HDPE.

In a preferred embodiment, the film comprises an average film thickness of at most 84 µm, preferably at most 80 µm, more preferably at most 78 µm, such as 78 µm, 77 µm, 76 µm, 75 µm, 74 µm, 73 µm, 72 µm, 71 μm, 70 μm, 69 μm, 68 μm, 67 μm, or any value in between.

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In a preferred embodiment, the film comprises an average film thickness of at least 60 μm and at most 84 μm, preferably at least 64 μm and at most 80 μm, more preferably at least 67 μm and at most 78 μm, such as 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, or any value in between.

In a preferred embodiment, the outer layer comprises an outer side that is printed.

In a second aspect, the invention comprises a method for manufacturing a three-layer paper-like plastic film according to the first aspect of the present invention. The method comprises the step of blow-coextruding molten compositions into a bubble for making the three-layer paper-like plastic film. The method further comprises the step of laterally cutting the bubble along two cutting lines and rolling up the two bubble halves on a first and a second roll to form two rolls of film. The method may include the additional step of printing the outside of the outer layer of the three-layer paper-like plastic film.

In a third aspect, the invention relates to a use of a three-layer paper-like plastic film according to the first aspect of the present invention as a packaging for butter. When using the film as a packaging for butter, a piece of film is cut off from a roll and the cut piece of film is pleated onto a plurality of fold lines.

In the following, the invention is described a.d.h.v. non-limiting examples that illustrate the invention, and which are not intended or may be interpreted to limit the scope of the invention.

EXAMPLES

EXAMPLE 1: FIRST COMPOSITION FOR THE FILM

In this first example, the film comprises an outer layer with an average thickness of about 30% of the average film thickness. Furthermore, the film comprises an inner layer with an average thickness of approximately 30% of the average film thickness. In this example, the inner and outer layers therefore have the same average thickness. The intermediate layer therefore comprises an average thickness of about 40% of the average film thickness. Each of the inner and outer layers comprises a composition

BE2017 / 5525 of about 60 weight percent of HDPE and about 40 weight percent of Schulman PaperMatch NG 4118. Schulman PaperMatch NG 4118 comprises calcium carbonate, a white colorant and HDPE. The inner and outer layers comprise the same composition in this example. The interlayer comprises a composition of about 46 weight percent HDPE, about 6 weight percent dye masterbatch, and about 48 weight percent filler. The dye masterbatch is herein either a blue dye masterbatch comprising both organic and inorganic pigments in a polyethylene matrix (e.g. Schulman Polybatch Blue 4535), or a dye masterbatch comprising 70 to 75% by weight of titanium dioxide. The filler here is Granic 422 master batch, comprising 80% by weight of chalk (calcium carbonate) and 20% by weight of LLDPE C8. Accordingly, the intermediate layer comprises at least 37 and at most 40 weight percent calcium carbonate, preferably at least 38 and at most 39 weight percent calcium carbonate, such as about 38.4 weight percent calcium carbonate. Accordingly, the interlayer comprises at least 8 weight percent LLDPE, preferably at least 9 weight percent LLDPE, more preferably at least 9.3 weight percent LLDPE, even more preferably at least 9.6 weight percent LLDPE. In this example, therefore, each of the inner, intermediate and outer layers comprises a dye and calcium carbonate. Preferably, the weight percentage of calcium carbonate in the intermediate layer is greater than the weight percentage of calcium carbonate in each of the inner and outer layers.

EXAMPLE 2: SECOND COMPOSITION

In this second example, the film comprises an outer layer with an average thickness of about 30% of the average film thickness. Furthermore, the film comprises an inner layer with an average thickness of approximately 30% of the average film thickness. In this example, the inner and outer layers therefore have the same average thickness. The intermediate layer therefore comprises an average thickness of about 40% of the average film thickness. Each of the inner and outer layers comprises at least 66 weight percent and at most 74 weight percent bimodal HDPE and at least 26 weight percent and at most 34 weight percent medium density polyethylene (MDPE). Preferably, each of the inner and outer layers comprises a composition of about 70 weight percent bimodal HDPE and about 30 weight percent MDPE. The inner and outer layers comprise the same composition in this example. The interlayer comprises a composition of about 46 weight percent of bimodal HDPE, about 6 weight percent of dye masterbatch and about 48 weight percent of Schulman PaperMatch NG 4118. Schulman PaperMatch NG 4118 comprises calcium carbonate, a white colorant and HDPE. The dye is masterbatch

BE2017 / 5525 herein either a blue dye masterbatch comprising both organic and inorganic pigments in a polyethylene matrix (e.g. Schulman Polybatch Blue 4535), or a dye masterbatch comprising 70 to 75% by weight of titanium dioxide.

EXAMPLE 3: ANALYSIS FILM ACCORDING TO FIRST EXAMPLE

Table 1 shows an analysis of a produced film according to the first example. MR stands for machine direction and DR for cross direction.

Table 1 - Analysis of a film according to the first example

Parameter Norm Value Width ISO 374 495 mm Minimum thickness ISO 374 60 μm Maximum thickness ISO 374 78 μm Average thickness ISO 374 68.7 μm Weight 86.8 g / m ² Tensile MR ASTM 0882 31.76 N / 15 mm Tensile strength DR ASTM 0882 21.91 N / 15 mm Tear strength MR ASTM 1922 807 mN Tear strength DR ASTM 1922 23147 mN Color Blue Opacity 70% Sliding resistance inside / inside static ASTM 1894 0.43 Sliding resistance inside / inside dynamic ASTM 1894 0.26 Sliding resistance outside / outside static ASTM 1894 0.43 Sliding resistance outside / outside dynamic ASTM 1894 0.28 Dartdrop ASTM 1709 95 grams MR ASTM 822 597% Rack DR ASTM 822 688%

Consequently, the film comprises an opacity of at least 60%, preferably at least

62.5%, such as an opacity of 62.5%, 65%, 67.5%, 70%, 72.5%, 75%, or any value in between or above it.

EXAMPLE 4: MIGRATION TESTS

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On a film with composition according to the second example and with an average film thickness of 70 μm, migration tests were carried out at 20 ° C by the Belgian Packaging Institute (BVI) according to European regulation 10/2011 and amendments with a first simulant comprising 10% by weight of ethanol and with a second simulant comprising 3 weight percent acetic acid. A global migration in the first simulant lower than 0.5 mg / dm ² and a global migration in the second simulant of approximately 0.5 mg / dm ^{2 were obtained} . These values are lower than 10 mg / dm ² , which is indicative that the film is suitable for contact with acidic foods (pH <4.5), such as, for example, sour butter.

Claims (9)

CONCLUSIONS A three-layer paper-like plastic film for packaging fatty foods, comprising: - an outer layer comprising high-density polyethylene; - an inner layer comprising high-density polyethylene; and - an intermediate layer positioned between the outer layer and the inner layer, the intermediate layer comprising high-density polyethylene, calcium carbonate and an intermediate layer dye, characterized in that each of the inner layer and the outer layer: - comprises at least 66 and at most 74% by weight of bimodal high-density polyethylene; and - comprises at least 26 and at most 34% by weight medium density polyethylene. A three-layer paper-like plastic film according to the preceding claim 1, wherein the film comprises at least 51% by weight of high-density polyethylene, preferably at least 54% by weight of high-density polyethylene. A three-layer paper-like plastic film according to any of the preceding claims 1 and 2, wherein the film comprises an average film thickness, the intermediate layer comprising an average thickness of at least 30% and at most 50% of the average film thickness, the inner layer and the outer layer each comprising a average thickness of at least 25% and at most 35% of the average film thickness. The three-layer paper-like plastic film according to the preceding claim 3, wherein the intermediate layer comprises an average thickness of at least 36% and at most 44% of the average film thickness and wherein the inner layer and the outer layer each have an average thickness of at least 28% and at most 32% of include the average film thickness. A three-layer paper-like plastic film according to any one of the preceding claims 1 to 4, wherein the intermediate layer comprises at least 44% by weight of high-density polyethylene. A three-layer paper-like plastic film according to any one of the preceding claims 1 to 5, wherein each of the outer layer and the inner layer comprises at least 58% by weight of high-density polyethylene. BE2017 / 5525 The three-layer paper-like plastic film according to any one of the preceding claims 1 to 6, wherein the intermediate layer comprises a weight percentage of calcium carbonate that is greater than the weight percentage of calcium carbonate in each of the 5 outer layer and the inner layer. A three-layer paper-like plastic film according to any one of the preceding claims 1 to 7, wherein the outer layer comprises an outer side and wherein the outer side is printed. A three-layer paper-like plastic film according to any one of the preceding claims 1 to 8, wherein the film comprises an average film thickness of at most 84 µm, preferably at most 80 µm, more preferably at most 78 µm. 10. A method for manufacturing a three-layer paper-like plastic film according to any of the preceding claims 1 to 9, comprising the step of blow-coextruding molten compositions into a bubble for making the three-layer paper-like plastic film. 11. Use of a three-layer paper-like plastic film according to any one of the preceding claims 1 to 9 as a packaging for butter.