Plastic ice rink panel for use as a running surface in a synthetic ice rink and method for the production thereof

Abstract

The invention relates to a plastic sliding panel (10) for use as a running surface in a synthetic ice rink, comprising a matrix (1) made of PE-HMW, characterised in that - the matrix (1) contains embedded grains (2) made of high-density polyethylene (HD-PE), wherein the grains (2) in the plastic sliding panel have a mass fraction of 10 wt.% to 30 wt.%, and - the plastic sliding panel (10) has surfaces (3, 4) planed in a plane-parallel manner, wherein some of the grains (2) cut there lie open on the surfaces (3, 4).

Description

[0001] Plastic ice rink sheet for use as a running surface in an artificial ice rink and methods for its manufacture

[0002] The invention relates to a plastic ice rink panel for use as a running surface in an artificial ice rink, comprising a panel matrix made of PE-HMW, and a method for its production.

[0003] Until now, artificial ice rinks have been used almost exclusively for ice sports. These rinks use a refrigerant that is cooled below freezing by refrigeration units. Water sprayed onto a flat surface freezes due to the artificial cooling and can be maintained as an ice layer with continuous refrigeration. However, this cooling system is only economical within a specific ambient temperature range, which is not always present outdoors, even in winter in temperate latitudes. In any case, an artificial ice rink requires significant energy consumption for ice production and continuous cooling.

[0004] Alternatives exist in the form of plastic panels with particularly low-friction surfaces. German patent DE 198 12 311 A1 describes a plastic ice rink panel with a sandwich construction. This makes ice skating as a recreational activity fundamentally possible. However, the durability of these and other plastic ice rink panels is limited. Since ice rinks with plastic panels are generally permanently installed outdoors, they are exposed to high levels of UV radiation. Furthermore, the plastic panels wear down due to the skate blades, which is why special blades with a series of small wheels have already been developed. However, these do not provide the same natural feel as skating on real ice.Furthermore, conventional synthetic ice rink tiles are prone to cupping, meaning they sag in a central area relative to the edges, resulting in a surface that is no longer perfectly parallel. Additionally, even with new tiles, semi-professional and professional use has shown that skating characteristics on conventional synthetic ice rink tiles still differ significantly from those on real ice.

[0005] The object of the invention is therefore to create a plastic ice rink panel for use as a skating surface in an artificial ice rink, which is well-suited for even skating, which is particularly durable due to a hard surface and which in particular enables a skating feel comparable to that of real ice surfaces.

[0006] This problem is solved by a plastic ice rink panel having the features of claim 1. A method for its manufacture is specified in claim 8.

[0007] In the following description of the invention, the term "artificial ice rink" is used as a generic term for all surfaces usable with ice skates.

[0008] To distinguish between them, the term "real ice rink" is used for artificial ice rinks where the usable surface consists of frozen water.

[0009] The basic idea of ​​the invention is to use PE-HMW, a material known as a good sliding material, to form a plate matrix and to embed a not insignificant proportion of high-density polyethylene (HD-PE) grains in it.

[0010] These granules are made from plastic granules or particles of shredded recycled plastic material, which are only slightly deformed during the manufacturing process of the plastic ice rink surface, but are not completely melted. They are merely flattened and rounded.

[0011] Within the scope of the present invention, the term "grains" refers to those solid particles that are embedded in the matrix of the finished plastic ice rink panel.

[0012] Since the synthetic ice rink surface is manufactured by pressing under pressure and heat, the grains are present in the matrix in a flattened, egg-shaped, or lenticular form. The narrow sides of the grains point towards the edges of the synthetic ice rink surface, while the broad surfaces are oriented more or less parallel to the surface. This embedding of the grains results in an inhomogeneous structure within the synthetic ice rink surface, so that local loads on the surface, e.g., when a skate blade strikes the surface, are always anisotropically distributed within the matrix. Due to the choice of materials, the matrix and the grains have different hardnesses.The different hardness of the matrix and grains leads to a barely predictable stress structure under load, so that it is almost impossible for individual zones to form within the plastic ice rink slab that are repeatedly subjected to high loads and that could form a starting point for microcracks.

[0013] A particular advantage of the embedded grains lies not only in the described reinforcement within the sheet material, but above all in the surface used for ice skating. Since the surface is planed by pressure and heat after sheet production, partially cut PE-HD grains are always exposed on the surface. Although the grains are only present in the matrix at a weight fraction of 10% to 30%, they make up at least 10% of the surface area. This apparent discrepancy between surface area and weight fraction is due to the fact that the grains are flattened during production and aligned parallel to the surface area, as described above.

[0014] The surface therefore consists of an irregular mix of the matrix plastic PE-HMW and the PE-HD granules. The greater hardness of the embedded granules significantly reduces wear when in contact with ice skate blades.

[0015] Another advantage here is that the surface is not homogeneous with isotropic properties, but rather exhibits locally varying, anisotropic properties, just like natural ice rinks. These local differences, however, are small compared to the length of a skate blade. The distribution of the grains within the matrix is ​​specifically chosen so that the blade will never come into contact with only a single PE-HD grain or only with the PE-HMW matrix material. For this reason, users describe the skating experience on a synthetic ice rink as particularly natural compared to a natural ice rink.

[0016] The high-density polyethylene (HDPE) granules are primarily recycled material, preferably shredded plastic packaging collected during clean-up operations in waterways and marine environments. Since these granules are often partially embrittled due to UV exposure, they possess an even higher hardness than virgin material, which is advantageous for the purposes of the present invention.

[0017] According to the invention, the PE-HMW matrix is ​​filled with a silicone oil to reduce the coefficient of friction on the usable surface of the plastic ice rink panel. To prevent the silicone oil from bleeding out of the matrix, it is bound to the matrix with an adhesion promoter oil.

[0018] Preferably, a medical white oil is used as an adhesion promoter oil.

[0019] In the process for manufacturing a plastic ice rink panel according to the invention, a material mixture is first produced which comprises at least:

[0020] - PE-HMW as the matrix-forming material; preferably with a particle size of 200 to 300 pm and comprising 50 wt.% to 90 wt.% of the total sheet; preferably 52 wt.% to 89 wt.%, wherein the matrix preferably consists of virgin material; and

[0021] - High-density polyethylene (HD-PE) as a filler for the matrix in the form of granules or pellets with a particle size of 3 to 7 mm and with a mass fraction of 10 wt.% to 30 wt.%.

[0022] The following are also added:

[0023] - Silicone oil with a proportion of up to 5 wt.%, preferably 1 wt.% to 5 wt.%, and adhesion promoter oil with a proportion of up to 5 wt.%, preferably 1 to 5 wt.%,

[0024] - UV stabilizers with a proportion of up to 2 wt.%, preferably 1 to 5 wt.%.

[0025] To increase the hardness of the finished plastic ice rink panel, titanium dioxide can be added in a ratio of up to 1 wt.%.

[0026] Dyes can also be added; however, these are preferably not used for direct coloring of the matrix material, but rather to reduce the contrast between the opaque matrix material and the white-dyed, cut grains, and to create an overall visually pleasing surface. For this purpose, a proportion of up to 5 wt.% of green-dyed PE-HMW can preferably be used. The addition of PE-UHMW is also possible. The green color results from the processing of production waste in the manufacture of technical sliding plates for mechanical engineering and process engineering, which are typically green-dyed at the applicant's company. In the plastic ice rink plate according to the invention, the green color also serves as an indicator of a sustainable product.

[0027] The use of high-molecular-weight polyethylene (PE-HMW) as the matrix material means that, as is known per se, the production of sheets is only possible in a heated press, and not by injection molding or extrusion processes. The molecular weight of the PE-HMW matrix material is between 400,000 g / mol and 600,000 g / mol, in particular 450,000 g / mol to 550,000 g / mol, and preferably 500,000 g / mol. This material is pressable, but when heated appropriately in the mold, it is also sufficiently flowable so that it can completely encapsulate the PE-HD granules, pellets, or shredded particles embedded in the material mixture during the pressing process.

[0028] An advantage of the method according to the invention is that recycled polyethylene PE-HD can be used as filler, which is contaminated with olfactory substances from its use in the first product cycle and is therefore only very limitedly recyclable in other ways.

[0029] The mixture of ground PE-HMW as the matrix material and PE-HD granules, pellets, etc., is mixed in using gravimetric dosing at a ratio of 10% to 30%. Initially, the ratio is chosen to be closer to the lower end of this range, and sample panels are produced. Since the exact material properties of the PE-HD components are not fully known when they are made from recycled material, the surface area ratio of the granules appearing on the finished, planed plastic ice rink panel can vary relative to the surface area formed by the matrix material. By varying the proportion of granules added, the surface area ratios of granules and matrix can be adjusted for subsequent production. The material mixture is then filled into a panel press and leveled.While doctoring is necessary to ensure a uniform fill level in the plate press anyway, within the scope of the invention it has the additional effect of flattening granules or shredded particles that are still oriented vertically in near-surface areas. This results in a high proportion of cut particles appearing on the usable surface of the finished, planed plate. Multiple partial filling operations, each followed by doctoring, are also possible until the desired layer thickness is reached in the press.

[0030] The material mixture prepared in the mold is pressed under the influence of temperature and pressure, a process that will be explained in more detail below. During pressing, the matrix is ​​formed by the complete melting of the PE-HMW component. The high-density polyethylene (HDPE), added in the form of granules or pellets, is deformed into solid granules embedded within the matrix. It may be softened, but it is not melted.

[0031] In contrast to conventional pressing of homogeneous PE-HMW sheets, the difficulty in the pressing process lies in achieving a strong compaction of the matrix with complete encapsulation of the grains and complete displacement of the air, without melting the PE-HD grains too much as they are a thermoplastic and free-flowing plastic.

[0032] First, the mold with the already filled material mixture is preheated at 100° to 140°C for a period of 30 to 60 minutes.

[0033] The material mixture, preheated in the plate press mold, is then subjected to a pressing pressure of 0.2 to 10 N / m2 for a period of 90 to 180 min.

[0034] In a final stage of the manufacturing process, it may be necessary to cool the semi-finished product in the mold to prevent excessive melting and flow of the high-density polyethylene (HDPE) granules. However, this is only necessary for batches of recycled HDPE with a relatively low molecular weight.

[0035] Furthermore, the process is designed to achieve a temperature of at least 135°C across the entire thickness of the semi-finished product in the press and only then allow it to cool uniformly. This relieves any stresses that may have resulted from the pressing process and prevents residual stresses from being frozen in during subsequent cooling. This could lead to the so-called cupping of the sheet, negatively affecting its flatness.

[0036] Finally, planing as a finishing step in the invention is an important step, as it is only through this process that the completely flat working surface with exposed, cut PE-HD grains is obtained. The thickness of the finished sheet should be at least 15 mm, preferably 20 mm. The pressed sheet blank has a thickness of approximately 17 or 23 mm before planing.

[0037] The invention is explained in more detail below with reference to the embodiment shown in the drawings. The figures show in detail:

[0038] Fig. 1 shows an oblique view of a surface of a plastic ice rink panel designed according to the invention and

[0039] Fig. 2 shows a diagram of the pressure and temperature profile over time during the pressing process.

[0040] Figure 1 shows an oblique view of a surface 3 of a plastic ice rink panel 10 designed according to the invention. Opaque areas of the matrix material 1 alternate on the surface 3 with white areas formed by cut grains 2. The visible dark speckles originate from production waste of green and / or black dyed PE-HMW or PE-UHMW. This serves two purposes: firstly, it allows the matrix material 1 to be filled with this waste, thus utilizing production waste; and secondly, it reduces the strong contrast between the very light, dyed areas of the grains 2 and the matrix material.

[0041] Figure 2 is a diagram in which the pressure 21 over time is shown as a solid line and the temperature 22 over time is shown as a dashed line.

[0042] In the illustrated embodiment, the manufacturing process is divided into three phases 23, 24, 25, which takes a total of 90 min to 180 min for a semi-finished sheet approximately 23 mm thick, from which a finished plastic ice rink sheet with a thickness of 20 mm is manufactured.

[0043] In a first phase 23, the pressure 21 is built up quickly and increases to a maximum pressure of up to 10 N / mm². 2 , typically up to 7 N / mm 2The pressure is then reduced at an even higher rate, built up again, and reduced once more. This intermediate step allows any air contained in the solid mixture to escape. In a second phase 24, the pressure remains at the reduced level until the temperature 22 reaches the target temperature of 150 °C in the core. After reaching the target temperature, a holding period follows to ensure complete heating to the core of the sheet material. From this point on, the matrix material is fully flowable.

[0044] A final phase 25 follows, in which the pressing pressure 21 is increased again to its maximum pressure while the temperature 22 is simultaneously reduced. This achieves a further compaction of the matrix material, which also encloses the embedded solid PE-HD particles. These particles are partially softened without being completely melted and are rounded and rolled out by the increased pressing pressure. From granules or shredded particles, which are cylindrical and / or angular in the initial mixture, lenticular or egg-shaped particles are formed, embedded in the matrix. At the end of phase 25, the press is opened and the manufactured sheet semi-finished product is removed. It is left to cool completely for approximately 120 minutes before the manufacturing process of the plastic ice rink panel is completed by planing the surfaces parallel to each other.

Claims

Patent claims:

1. Plastic sliding plate (10) for use as a running surface in an artificial ice rink, comprising a matrix (1) made of PE-HMW, characterized in that the matrix (1) contains embedded grains (2) made of high-density polyethylene (HD-PE), wherein the grains (2) have a mass fraction of 10 wt.% to 30 wt.% in the plastic sliding plate and that the plastic sliding plate (10) has planed surfaces (3, 4) parallel to the surface, wherein a part of the grains (2) cut there are exposed on the surfaces (3, 4).

2. Plastic sliding plate (10) according to claim 1 , characterized in that the finished plastic sliding plate, planed on both surfaces (3, 4), has a thickness of 15 mm to 20 mm.

3. Plastic sliding plate (10) according to claim 1 or 2, characterized in that it contains silicone oil in a proportion of 1 wt. % to 5 wt. % which is bound to the matrix (1) by means of an additional adhesion promoter oil.

4. Plastic sliding plate (10) according to claim 3, characterized in that a medical white oil is contained as an adhesion promoter oil.

5. Plastic sliding plate (10) according to one of claims 1 to 3, characterized in that the matrix (1) is formed from PE-HMW with a molecular weight of 400,000 g / mol and 600,000 g / mol 6. Plastic sliding plate (10) according to one of claims 1 to 5, characterized in that the embedded grains (2) consist of recycled high-density polyethylene (HD-PE) with an average molecular weight of 80,000 g / mol to 100,000 g / mol.

7. Plastic sliding plate (10) according to one of claims 1 to 6, characterized in that the embedded grains (2) have a lens shape, the largest planar extent of which extends predominantly parallel to the surfaces (3, 4).

8. Method for manufacturing a plastic sliding plate (10) for use as a running surface in an artificial ice rink, comprising at least the following steps: - Production of a material mixture comprising at least: o PE-HMW in powder form with a particle size of 200 to 300 pm and with a proportion of 50 wt.% to 90 wt.%; as a matrix-forming material; o High-density polyethylene (HD-PE) in the form of granules or pellets with a mass fraction of 10 wt.% to 30 wt.%; Pouring the material mixture into a plate press mold and scraping off the material mixture in the plate press mold; - Preheating at 100° to 140°C for 30 to 60 minutes; pressing the preheated material mixture in the plate press mold with a pressing pressure of 0.2 to 10 N / m² for 30 to 60 minutes, whereby the matrix (1) is formed by complete melting of the PE-HMW and the high-density polyethylene (HD-PE) added in the form of granules or pellets is deformed into solid grains (2) embedded within the matrix (1); cooling of the material mixture during continued pressing until a core temperature of less than 30 to 40°C is reached; demolding of the resulting plate semi-finished product from the plate press mold; and planing of both surfaces (3, 4) parallel to each other on the plastic sliding plate (10).

9. Method according to claim 8, characterized in that the mold with the already filled material mixture is preheated at 100° to 140°C for a period of 30 to 60 min.

10. The method according to claim 9, characterized in that the material mixture preheated in the plate press mold is subjected to a pressing pressure of 0.2 to 10 N / m² for a period of 90 to 180 minutes.

11. Method according to claim 10 or 11, characterized in that in a final stage of the manufacturing process the sheet semi-finished product located in the mold is cooled.

12. Method according to claims 9 to 11, characterized in that after pressing a temperature of at least 135° is reached over the entire thickness of the sheet material in the press mold and the sheet material is then cooled uniformly.

13. Method according to one of claims 8 to 12, characterized in that the pressed sheet semi-finished product has a thickness of about 17 mm to 23 millimeters before planing the surfaces and up to 2 mm are removed by planing.

14. Method according to one of claims 8 to 13, characterized in that a silicone oil with a proportion of 1 wt.% to 5 wt.% and an adhesion promoter oil with a proportion of 1 wt.% to 5 wt.% is added to the material mixture.

15. Method according to claim 14, characterized in that a medical white oil is used as the adhesion promoter oil.

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