WO2010100537A2

WO2010100537A2 - Tray and method for forming thereof

Info

Publication number: WO2010100537A2
Application number: PCT/IB2010/000385
Authority: WO
Inventors: Karl Huylebroeck
Original assignee: ROLTEX
Current assignee: ROLTEX
Priority date: 2009-03-03
Filing date: 2010-02-25
Publication date: 2010-09-10
Anticipated expiration: 2011-09-03
Also published as: WO2010100537A3; BE1018674A5

Abstract

The invention relates to a catering tray (1) for carrying tableware, comprising a polymerized composition of at least one layer that essentially consists of a filler impregnated with a polymerizable resin, characterized in that at least part of the polymerizable resin is a resin of plant origin.

Description

CATERING TRAY AND METHOD FOR ITS PRODUCTION

The present invention relates to a catering tray for carrying tableware, comprising a polymerized composition of at least one layer that essentially consists of a filler of plant origin and which is impregnated with a polymerizable resin. The invention also relates to a method for the production of such a catering tray.

Catering trays of this kind are well known, as they are widely used for example in hotels, restaurants and other catering establishments, as well as in the home, for carrying, serving and transporting tableware (such as plates, glasses, cups, mugs, eating implements, etc.) with or without any food and/or drink on or in it, for example in a hotel, restaurant, canteen, and so on. German Patent DE 20 44 698 discloses for example a catering tray that is made of a number of sheets of paper, which are superimposed on one another and impregnated with a synthetic thermosetting resin, such as for example a phenol-formaldehyde resin, an amino- plastic resin, and especially a melamine-formaldehyde resin.

However, the known catering trays based on synthetic resins have the disadvantage that they are not environment-friendly. First of all, the production of synthetic resins itself is already an environment-unfriendly process, partly because these resins are ultimately made from petroleum. Secondly, these catering trays are often incinerated at the end of their useful life, which - due to the presence of a synthetic resin in them - releases other harmful substances and extra CO₂ into the atmosphere, thus contributing to global warming. In addition, harmful substances such as phenols are released when the substrates are being impregnated with a synthetic resin, and when the known catering trays made with synthetic resins are being manufactured, and these harmful substances pollute both the working environment in the factory and the atmospheric air. These synthetic resins are therefore environmentally undesirable also at the time of their production.

A possible solution of this problem is described in Japanese Patent Specification JP 2000 / 273 ,709, which discloses a catering tray made of a number of sheets of a filler of plant origin, especially bamboo, which are placed on one another and impregnated with an adhesive made of a plant material and/or an inorganic material. However, these catering trays have the disadvantage that they are not suitable for professional use in hotels, catering establishments, hospitals, etc., because they are damaged in institutional dishwashers, which cause bubble formation, warping, swelling of the edges, surface blemishes, etc.

The aim of the present invention is therefore to provide an environment-friendly catering tray that is, in addition, suitable for professional use.

The aim of the invention is achieved by providing a catering tray for carrying tableware, comprising a polymerized composition of at least one layer, which essentially consists of a filler of plant origin, impregnated with a polymerizable resin, said layer essentially consisting of paper that acts as a filler and is impregnated with furan resin.

A catering tray formed in this way has the advantage that it is resistant to water and heat, so it can be cleaned in institutional dishwashers without any problem. Furthermore, such a catering tray meets all the legal requirements and standards.

Furan resin can be obtained in liquid form, which makes impregnation considerably easier. Furan resin has essentially the same properties as melamine resin as regards for example strength, moisture resistance and heat resistance, so it is very suitable for the production of catering trays.

Furthermore, the production of a resin of plant origin, namely furan resin, is better for the environment, because resins of plant origin are not made from petroleum derivatives but are obtained directly from natural materials present in living Nature.

Unlike in the case when synthetic resins are used, moreover, no harmful gases such as phenols are liberated either during the impregnation of the filler of plant origin with furan resin, or during the compression and molding of the pieces impregnated with furan resin.

The Inventor has also found that, when natural resins of plant origin are used, the manufacture and recycling of the catering trays according to the present invention have an essentially neutral CO₂ balance. This is because the CO₂ released during the incineration of the catering tray at the end of its useful life is taken up again by biological organisms, which can in turn be used again to obtain natural resins.

When a fairly large percentage of a material of natural origin is used in the production of the catering tray, it is possible to employ a larger amount of renewable basic natural materials that are continuously formed in nature, and a smaller amount of materials that can only be obtained once, such as for example substances derived from petroleum.

Another important advantage of working with materials of plant origin (such as for example furan resin) instead if synthetic resins (such as for example a phenol- formaldehyde resin) lies in the absence of poisonous substances such as phenols and the like, which may be released after a certain length of time has elapsed. This should be avoided especially in the case of products that come into direct contact with food, such as notably a catering tray, since the intake of these poisonous substances may be toxic to human beings.

The filler of the catering tray is also essentially of natural origin. If catering trays are made from a fairly large percentage of materials of natural origin, then one can use a larger amount of renewable natural raw materials, which can be continuously produced in nature, and one needs a smaller amount of materials that can only be obtained once, such as for example substances made from petroleum. More especially, the filler of the catering tray is essentially of plant origin. The advantage of fillers of plant origin is that they are largely produced in plants by the photosynthetic conversion of CO₂, which considerably improves the CO₂ balance of the catering tray.

The filler used in the catering tray according to the present invention consists of paper. Paper is a well-known material, obtained in the form of sheets of different sizes and thicknesses. One can write or draw on paper or else print on, using various printing techniques. Paper can be made for example from natural materials, such as reeds, bamboo or wood, or by reusing old materials, such as old fabrics or old paper. One of the advantages of paper in the context of the present invention is that it is a filler rich in fibers that lends itself to the production of sheets of the required size and thickness, in addition to which the sheets in question are porous, so they can be easily impregnated and can thus confer the required strength on the catering tray. In a preferred embodiment of the catering tray according to the present invention, the paper used as the filler is mostly kraft paper or recycled paper. The use of recycled paper further improves the CO₂ balance of the catering tray. Another advantage of recycled paper is that less water is needed for making it, and a smaller area of forest suffices for its production, leaving a larger area free for other trees or plants.

The preferred embodiments of the present invention are characterized in that, in the case when paper is used as the filler, the ratio, by weight, of the resin to the total weight of the impregnated filler is a number between 15 and 50% and preferably a number between 20 and 40%. It has been found that this ratio ensures the required physical properties, such as strength for example, for the catering tray according to the present invention.

Other preferred embodiments of the present invention are characterized in that the top and/or bottom surface of the catering tray is/are at least partially covered by a layer of melamine. The advantage of this layer is that it can come into contact with food without any undesirable consequences as to flavor or toxicity. It can also add to the mechanical strength and toughness by being resistant to scratches, moisture and heat. This is particularly important for example when the user cuts through food on the catering tray with a knife, when eating implements or plates slide about on the catering tray, when the catering tray is cleaned in a dishwasher, or when these trays rub against one another as they are being stacked.

Other preferred embodiments of the present invention are characterized in that the catering tray has a carrying surface whose circumference is at least partially surrounded by a raised edge. The raised edge makes the catering tray structurally sturdy, so that for example the thickness of the tray can be kept small. It has also been found that catering trays with raised edges are easier for example to stack by bringing the raised edges into contact with one another. Furthermore, the tableware placed on the carrying surface does not slide off and drop to the ground so easily, thanks to the raised edges. It is also easier to grasp such a catering tray, since the raised edge can be held more firmly by clamping it between the thumb on one side of the edge and the fingers on the other side of it. This is particularly important when carrying a full tray. Picking a catering tray up from the middle of the table is also made easier by this edge, so the user does not have to slide the tray to the edge of the table first.

Other preferred embodiments of the present invention are characterized in that the catering tray comprises at least two layers of paper acting as a filler, impregnated with furan resin. A catering tray with the required thickness, weight, stiffness, etc. can be obtained by using a number of such filler layers (superimposed on one another) in the catering tray according to the present invention.

In another embodiment, the various layers can be made of different materials according to the required physical properties of each layer in the catering tray. Thus, for example, scratch resistance and moisture resistance are important parameters for the outside layers, while strength is an important parameter for the inner layers.

The invention also relates to a method for the production of catering trays, where paper as a filler, impregnated with furan resin, is polymerized in the form of a catering tray.

The invention is elucidated below in more detail with the aid of the following description and the corresponding illustrations of the preferred embodiment of the catering tray, as is also the method for the production of the catering trays according to the invention. It will be realized that none of the details mentioned in the following description should be interpreted as a limitation to the protection sought for this invention in the claims.

The various numbered items included in the following description refer to the enclosed illustrations, where:

- Fig. IA shows a bottom view of the catering tray according to the invention

- Fig. IB shows a side view of the catering tray according to the invention - Fig. 1C shows a top view of the catering tray according to the invention

- Fig. 2A shows a bottom view of another catering tray according to the invention - Fig. 2B shows a side view of another catering tray according to the invention

- Fig. 2C shows a top view of another catering tray according to the invention

- Fig. 3 shows a method for making a catering tray according to the invention

- Fig. 4 shows the life cycle of a catering tray according to the invention, made from paper and furan resin.

Fig. 2 shows a catering tray (1) according to the invention. The carrying surface is preferably rectangular, and the catering tray (1) has a raised edge (5). hi some other embodiments, the carrying surface can be for example triangular, square, oblong, hexagonal, octagonal, trapezoidal, oval or circular. Fig. 1 shows an octagonal catering tray as an example.

In the preferred embodiments, the angles are generally rounded off to avoid sharp corners and injuries to the hand, which is important for example when the trays are shuffled in a canteen. The shape of the raised edges is also chosen in such a way that the catering trays can be both easily stacked and easily removed from the mold during manufacture. These raised edges (5) may surround the catering tray (1) either completely or in part. An advantage of a catering tray with a continuous edge running right around its circumference is that any liquid such as a drink or soup that may be spilled on the carrying surface will be contained, so it does not end up on the table. The volume of liquid that can be retained in this way can be varied by varying the height of the raised edge. The latter is also a suitable place for handles.

The bottom of the catering tray (1) preferably has some areas of extra thickness (6). The advantage of these extra-thick areas is that they ensure that the catering tray lies on the table in a stable manner, because now it only rests on a few preselected spots or ribs instead of its whole area. This prevents the catering tray from wobbling or rocking, whereby liquids might be spilled. By increasing the extra thickness of the areas in question, the catering tray can be easily picked up from the table without having to make the entire edge higher. This affords a considerable saving of material, which is important in the case of the present invention in the context of sustainability and the rational use of basic materials and energy. The edges can also be made with such extra-thick areas, acting as stiffeners.

The catering tray (1) according to the present invention comprises at least one layer that essentially consists of paper as a filler, impregnated with furan resin. The catering tray (1) is preferably formed by a number of superimposed layers of paper impregnated with furan resin, which is a thermosetting resin. The advantage of using such a resin is to ensure a better thermal stability, so that the product does not lose its shape and solidity at elevated temperatures. This is because it is important to ensure that the catering tray does not warp or become distorted when for example a hot plate is placed on it, when it - the tray - is placed in a dishwasher, or else boiling water is spilled on it. The furan resin used is obtained from sugar cane, more specifically from bagasse, which is a biomass formed in the production of sugar from sugar cane. When the canes are being harvested, they are generally cut off close to the ground. The canes obtained are generally processed in a sugar factory by pressing the juice out of them in order to extract the sugar from it. The remaining residues of the stems, called bagasse, can be used for example as a source for obtaining the furan resin mentioned above. Since bagasse is a natural waste material that cannot be used as human food, its use here means that less other material of plant origin is required for the production of the resin, for example furan resin, to produce the catering trays according to the present invention, so the other material of plant origin can instead (or also) be used for human food. The production of the resin, for example furan resin, therefore competes here with the production of human food to a lesser extent or not at all.

Fig. 3 shows a method for making the catering tray (1) according to the present invention. As mentioned before, the filler used here is preferably paper, and furan resin is preferably used as the polymerizable resin. Furan resin can be obtained from bagasse, which is an agricultural waste product of sugar canes; this waste product can be converted first into fufural and then into furfuryl alcohol. Furan resin can contain a mixture of di-, tri- and/or polysubstituted furan. However, this thermosetting resin can also be obtained from other agricultural waste products.

The paper used as the filler can be new paper, made for example from plant material such as wood, or it can be paper made from bagasse, but it can also be kraft paper or recycled paper. Sheets of paper can be impregnated as described below. Sheets of absorbent paper are immersed at least once in a bath of a liquid resin or the latter is poured over them. They are then pressed on several rollers passing to and fro over them in order to squeeze the excess resin out of them. The impregnated sheets are then partly dried without any polymerization. The ratio between the amount of paper to the amount of resin is decided in advance and is for example a grammage of 160 g/m² of filler versus a grammage of 235 g/m² of resined material. The 75 g/m² difference is the weight of the dried resin. In practice, the amount of filler and the amount of resin are expressed by the X/T ratio, where X is the weight of the filler (in g/m ) and T is the total weight of the filler plus resin (also in g/m ). Some commercially available values include 22/70, 160/235 and 160/380. It can be calculated from these figures that the ratio between the weight of the filler (X) and the total weight (T) varies from 30 to 42% in these examples. These impregnated sheets of paper are marketed for example as semi-finished products. For making the catering tray, a number of such sheets of paper are placed on one another and inserted into a steel mold, the number of sheets varying for example from 3 to 14 and preferably from 7 to 10. The sheets are then pressed together and kept under pressure and heated for a set time, during which polymerization takes place. This produces a three-dimensional structure that ensures that the catering fray is sturdy. The pressure applied for the compression is 10-200 bar/cm² and preferably 30-70 bar/cm². The temperature during the polymerization is 100-250°C, and preferably 110-130⁰C, 140-150°C or 190-200⁰C. The duration of the polymerization varies from 30 seconds to 5 minutes and is preferably 3-4 minutes. After the polymerization, the catering fray (1) is firm and stiff; it can be removed from the mold and is ready for use. The combination of paper and furan resin gives a product that is almost entirely made of materials of plant origin, which gives a particularly sustainable product. Since it is tough and resists scratches and heat, the resulting catering fray has a long service life and, moreover, can be cleaned in institutional dishwashers without any problem. This means that these trays do not need to be replaced so often, which is also beneficial for the environment.

In some other embodiments, paper can be replaced by other fillers of plant origin such as veneer or wood flour. In yet other embodiments, paper can be replaced by materials of animal origin, such as wool or silk, which are also sustainable and environment-friendly. In some further embodiments, the filler can be a mixture of ground products to which glass fibers have been added. In a preferred embodiment, the outside layers are made for example from a combination of paper and furan resin, while the intermediate layers are made from a material or a combination of materials chosen according to the physical properties required for these layers of the catering tray. For example, scratch resistance and moisture resistance are important parameters for the outside layers, while strength is an important parameter for the inner layers. Therefore, the filler for the intermediate (inner) layers can mainly consist for example of a mixture of ground products to which glass fibers and/or carbon fibers and/or natural fibers have been added. One of the advantages of a mixture of ground products to which fibers have been added in the context of the present invention is that it provides a filler that can be easily impregnated and which has the necessary strength for a catering tray, mainly because of the presence of glass fibers in it. Furthermore, this material comes in sheet or paste form, which simplifies the production of catering trays with the required thickness or the required number of layers. In addition, the characteristics of the catering tray can be optimized by varying the amount and length of the glass fibers added.

The method of making the catering trays may involve for example the use of a bulk molding compound (BMC) or a sheet molding compound (SMC). The latter comes in the form of sheets, for example sheets made from glass fibers and for example polyester resin, and it is known as such from the prior art, but the present invention involves the use of an SMC and/or BMC made with furan resin or another resin of plant origin. The ratio between the filler and the resin is again given in terms of X/T. For a catering tray according to the present invention, the filler represents 15 to 50 wt-% of the total weight when BMC or SMC is used. The use of a fairly large percentage of materials of plant origin gives a more sustainable catering tray than one made for example with a polyester resin. In the present invention, SMC made with carbon fibers or natural fibers such as flax or sisal is used by preference. SMC can be applied in layers, as described above in the case of paper. To make catering trays with SMC, the layer thickness used is preferably 2000-5000 g/m² and more preferably 2450 g/m². When catering trays are made from BMC, for example 0.5-1.5 kg of the paste are removed from the can and inserted into a steel mold, the latter is closed under pressure, heated to the required temperature and cured.

In some other embodiments, a melamine layer is added optionally. The use of melamine in catering trays is well known. The advantage of this layer is that it can come into contact with food without any deleterious consequences for the flavor or toxicity. It can also increase the mechanical toughness, because it resists scratching, moisture and heat, hi the context of the present invention, for example the top and/or bottom layer of the catering tray may be made of melamine.

Fig. 4 shows the life cycle of a catering tray according to the present invention, where the filler is made of paper, preferably recycled paper or kraft paper, and where furan resin is used as the polymerizable resin. The figure shows how furan resin can be obtained from sugar cane residues, namely bagasse. This figure also shows how the catering tray can be conveniently disposed of by thermal recycling at the end of its useful life. This means that a large part of the energy used in the production of the catering tray can be recovered at the end of its useful life. The energy released in the incineration can be utilized for example for making paper, for recycling old paper, or for heating the material during polymerization. This figure also shows that the production and recycling of these catering trays have an essentially neutral CO₂ balance. This is because the CO₂ that is liberated in the incineration of the catering tray at the end of its useful life is again taken up in biological organisms, which can then be used again for making the filler or the resin of plant origin, hi this way, the CO₂ that is liberated in the incineration of the filler is again converted into a biological material that can in turn be made into a filler again. The higher the percentage of filler of plant origin, the more environment-friendly is this cycle, and the more sustainable is the catering tray.

Claims

1. A catering tray (1) for carrying tableware, comprising a polymerized composition of at least one layer, which essentially consists of a filler of plant origin and which is impregnated with a polymerizable resin, characterized in that said layer essentially consists of paper as a filler, impregnated with furan resin.

2. The catering tray (1) as claimed in claim 1, characterized in that the paper used as the filler essentially consists of kraft paper or recycled paper.

3. The catering tray (1) as claimed in claim 1 or 2, characterized in that the ratio by weight between the filler and the total weight of the impregnated filler is a number between 15% and 50%.

4. The catering tray (1) as claimed in claim 3, characterized in that the ratio by weight between the filler and the total weight of the impregnated filler is a number between 30% and 42%.

5. The catering tray (1) as claimed in any one of the preceding claims, characterized in that the catering tray has its top (2) and/or bottom (3) at least partly covered by a melamine layer.

6. The catering tray (1) as claimed in any one of the preceding claims, characterized in that the catering tray has a carrying surface (4) whose circumference is at least partly surrounded by a raised edge (5).

7. The catering tray (1) as claimed in any one of the preceding claims, characterized in that the catering tray comprises at least two layers of paper as a filler, impregnated with furan resin.

8. The catering tray as claimed in claim 7, characterized in that the number of layers of paper used as a filler, impregnated with furan resin is greater than or equal to 3 and smaller than or equal to 14, and preferably greater than or equal to 7 and smaller than or equal to 10.

9. A method for the production of the catering tray as claimed in any one of the preceding claims, where the filler paper impregnated with furan resin is polymerized in the form of the catering tray.

10. The method as claimed in claim 9, characterized in that, during the polymerization, the impregnated filler is compressed under a pressure of 10 to 200 bar/cm² and preferably 30 to 70 bar/cm².

11. The method as claimed in claim 9 or 10, characterized in that the impregnated filler is polymerized at a temperature of 100-250°C and preferably at 110 to 130°C or 140-150°C, or 190 to 200°C.

12. The method as claimed in any one of claims 9-11, characterized in that the impregnated filler is polymerized for 30 seconds to 5 minutes, and preferably for 3 to 4 minutes.