SE511651C2 - Food forms or packaging materials - Google Patents

Abstract

Material for trays or packagings, which material is built up from a number of layers, these layers comprising, seen from the inside of the tray/packaging, a first greaseproof paper (2), a layer of adhesive (4) and a second greaseproof paper (5). Applied outside said second greaseproof paper is a water-repellent layer (6).

Description

15 20 25 30 35 511 651 2 forms. 6. The food contained in the mold must be able to be examined with a metal detector, so metallic materials should be avoided. 7. The material should not include plastic, as there is a risk that plastic, at least in some countries, will be taxed in the future. 8. The material must be approved for human consumption.

The conventional material for this type of food mold is aluminum.

Aluminum, however, far from meets all the above requirements / wishes. In particular, it is not environmentally friendly and does not allow examination of the food with a metal detector.

Another type of known material is plastic-coated cardboard, which of course has the disadvantage that it contains plastic. The carton usually has a basis weight of about 300-400 g / m 2. The relatively environmentally friendly plastic polyethylene cannot be used in this type of material if the mold is to withstand high temperatures at e.g. baking, as polyethylene melts at these temperatures. Other plastics, e.g. polyesters, have the disadvantage that they have a tendency to release from the carton upon heating, causing blisters to form.

Another type of known material is so-called greaseproof paper. WO 96/1 15 76 discloses a material which is built up from the inside out by a water-repellent layer, a greaseproof paper, a grease-repellent layer and a greaseproof paper. It is further stated that the water-repellent layer can be a layer of lacquer and that the grease-repellent layer can be a layer of binder which also has the function of holding the two greaseproof papers together. On the outside of the outermost greaseproof paper there may be a decorative layer. This type of material meets most of the above requirements / wishes but not requirement 4. Moisture can enter the material from the outside, e.g. in a hot oven with a fi saturated atmosphere, or during thawing, whereby a mold made of the material collapses and loses its dimensional stability.

SOLUTION AND ADVANTAGES The present invention presents a material for molds, especially for food, which material meets all the above requirements / desires while being relatively inexpensive. The material also results in a reduced weight on the molds made of the material, in comparison with the heavier material plastic-coated cardboard according to the prior art. This is an important benefit from an environmental point of view.

The material according to the invention is defined in claim 1 and is a further development of the material presented in WO 96/1 1576, wherein an outermost layer, i.e. the layer furthest from the food in a mold made of the material, is a water-repellent stock. This outermost, water-repellent layer preferably consists of or mainly comprises an acrylic polymer, in particular a modified one which also contains wax. A particularly preferred modified acrylic polymer is an anionic aqueous dispersion of acrylate copolymer containing a certain amount of stearate. Also other types of water-repellent material, e.g. however, silicone, polyacrylate copolymer dispersion, styrene acrylate, acrylic acid copolymer or a combination of specified materials can be used for this extreme water repellent layer.

According to one aspect of the invention, a mold made of a material according to the invention has a surface which may be unbleached, bleached, colored or with print and which may moreover be different on the inside and the outside of the mold, respectively. The material further retains at least 60%, preferably at least 70% of its tear strength after being subjected to baking temperature in an oven at about 200-220 ° C for 20 minutes.

According to another aspect of the invention, the material may consist of a laminate with three or more layers of greaseproof paper.

DESCRIPTION OF THE FIGURES The invention will now be described with reference to Figure 1, which schematically shows the bearings in a preferred material according to the invention, the pieces in the description below being numbered in the same way as the bearings in the figure. The figure is not to scale. In reality, layers 2 and 5 are completely dominant in thickness. Layer 1 in figure 1 represents the layer which, in a mold made of a material according to the invention, faces the food, ie is on the inside of the mold.

The layer 1 consists of a grease and water-repellent layer, which preferably comprises mainly silicone and has a basis weight of 0.1-2 g / m 2, preferably 0.4-0.8 g / m 2. The silicone is applied in the manufacture of the laminate material on the next layer, e.g. with the help of a so-called blade coater or in a so-called glue press. Other types of grease and water repellent layers can also be used, e.g. 10 20 25 30 35 511 651 4 chromium stearate, which, however, has the disadvantage that it is less environmentally friendly. Silicone has the advantage that the surface releases the food well when it is taken out of the mold and that the molds do not stick to each other when stacking, which is an advantage in automated placement of the molds when they are to be used. For applications other than food, e.g. in molds or packages for toys or medicines or the like, this inner layer 1 is not always necessary.

. Layer 2 consists of a first greaseproof paper, which suitably has a basis weight of 30-100 g / m 2, preferably 60-75 g / m 2. This paper is preferably made from pulp made according to the sulphite method and which preferably has a grinding degree higher than 70 ° SR Schopper-Riegler. Such highly ground, greaseproof paper has a high density, at least 800 kg / m3 or about 900 kg / m3 at a basis weight of 75 g / m 2 and exhibits a fat resistance measured as so-called Air permeance according to SCAN P26-78 of less than 0.7 nm / (Passport), where a low value is a measure of a high fat resistance. In order for the greaseproof paper to look as wide as possible, a substance which gives this effect is added during manufacture, preferably titanium dioxide in an amount of about 1-10%, preferably 2.5-5% calculated on dry contents, alternatively t. ex. kaolin or calcium carbonate. Titanium oxide has the advantage that it provides fat capacity, whereby unattractive dark fat fl forms in the surface of the greaseproof paper. In order to make the greaseproof paper wet-strong so that a food form made from the material according to the invention retains its appearance and its stability during freezing, a wet-strength agent, preferably of the polyamide-epichlorohydrin resin dissolved in water, is added during the production of the greaseproof paper. what in Sweden is known under the trade name Kymene SLX.

The fact that the greaseproof paper should preferably be made of sulphite pulp is partly due to the fact that sulphate pulp gives good properties in the form of grease resistance, but also because sulphite pulp gives better dimensional stability than the more common sulphate pulp. Pulp made according to the sulphate method produces fibers that are stiffer than the fibers in sulphated pulp, so a food form of sulphate pulp loses its stability and shape. According to the invention, however, 1-50% of sulphate pulp can be mixed into the salt pulp without dramatically deteriorating the grain stability.

The first greaseproof paper in layer 2 is suitably coated 2a, 2b, with starch glue, latex, polyvinyl alcohol or the like, preferably with starch glue and preferably on both sides. This coating is suitably made in connection with the manufacture of the greaseproof paper in a so-called glue press. Each coating layer has a basis weight of 0.1-1 g / m 2, preferably about 0.5 g / m 2 and penetrates to some extent into the greaseproof paper. The coating layers are said to constitute barriers for the adjacent layers. If e.g. If the coating layer 2a did not exist, the amount of silicone required in the layer 1 would increase considerably in order to obtain the correct surface properties. Starch adhesive is preferred, as it provides a good barrier against silicone penetration and improves the paper's fat resistance (Air permeance).

. Layer 3 is a cover layer, which aims to give the material good sealing properties and good adhesion to adjacent layers. This cover layer has a basis weight of 0.1-1 g / m 2, preferably about 0.5 g / m 2 and preferably comprises mainly latex, alternatively polyvinyl alcohol. However, in some cases, just one water coating may be enough to avoid curling the paper. The coating is suitably done in sheet coaters but can also be done in glue press. This affects the requirements placed on the end product.

. Layer 4 is a layer of binder whose task is to join the two greaseproof papers together. The layer 4 has a basis weight of 1-10 g / m 2, preferably 3-6 g / m 2, depending on the surface structure of the paper, and mainly comprises a hardening adhesive, suitably polyurethane adhesive which is preferably solvent-free. This type of layer has the advantage over a layer of plastic that it can withstand high temperatures.

. Layer 5 consists of a second greaseproof paper which completely corresponds to the determinations given above for the first greaseproof paper 2.

The second greaseproof paper 5 is also coated Sa, Sb, in the same way as the first greaseproof paper 2, with the only difference that the coating layers Sa, Sb preferably mainly comprise a cellulose derivative, preferably sodium carboxymethylcellulose (CMC). The main purpose of the coating layers Sa, Sb is to form a barrier against adjacent layers and to improve the paper's fat resistance (Air permeance). Alternatively, the coating layers Sa, Sb may comprise starch adhesive, polyvinyl alcohol or the like.

. Layer 6 consists according to the invention of a water-repellent layer. This has the function of preventing moisture from penetrating into the greaseproof paper, otherwise the dimensional stability of a food mold made of the material may be lost, especially when it is exposed to a hot and humid atmosphere in the oven when baking the contents of the mold or or thawing. During thawing, the content of the air kond acts on the cold surface, whereby the mold risks collapsing if there is no extreme water-repellent layer 6. The layer 6 has a basis weight of 0.1-1 g / m 2, preferably 0.5-1 g / m 2 and preferably consists of or mainly comprises an acrylic polymer, especially a modified one which also contains wax. An especially preferred modified acrylic polymer is an anionic aqueous dispersion of acrylate copolymer containing a certain amount of stearate. Also other types of water-repellent material, e.g. However, silicone, polyacrylate copolymer dispersion, styrene acrylate, acrylic acid copolymer or a combination of specified materials can be used for this extreme water-repellent layer, but preferably not plastic material.

When manufacturing materials according to the invention, the starting point is the two greaseproof papers, which are already coated with layers 1, 2a, 2b and 3 and Sa, 5b and 6, respectively, in connection with their manufacture. The greaseproof papers 2 and 5, with their coatings, are then joined to the bearing 4 by roll coating in a laminating machine.

EXAMPLE Four different laminates were made of which laminate A was made according to the invention and the layers consisted inside and out of silicone, starch glue, a first greaseproof paper, starch glue, latex, solvent-free hardening glue, CMC, a second greaseproof paper, CMC and finally a modified acrylic polymer with wax . Laminate B was also made according to the invention in the same way as laminate A with the difference that the latex layer was omitted. Laminate C was also made according to the invention in the same way as laminate A but with opaque greaseproof paper, with the first greaseproof paper coated with latex instead of starch glue and with water instead of the latex layer present in laminate A. A fourth laminate D was made as reference and consisted of an innermost layer of polyester film, CMC, a first greaseproof paper, CMC, a modified acrylic polymer with wax, solvent-free curing adhesive, CMC, a second greaseproof paper, CMC and finally a modified acrylic polymer with wax. For the four different laminates, some characteristic properties were tested, which are reported in Table 1 below, taking into account that these results are derived from individual measurements with concomitant uncertainty in the values. 7 51 1 6 51 Table 1 Test method ABCD vwikf g / m * _1so5s6-1976 (E) 159 159 157 178 Density kg / ma ISO534-1988 (E) 964 964 * i 989 1053 Thickness um 165 165 159 169 Brightness ISO2470-1977 (E) 67 66 79 66 Opacity ISO2471-1977 (E) 65 64 85 66 Luñpermeans nm / (Pa-s) SCAN P26-78 <0.004 <0.004 <0.004 <0.004 Fat resistance s TAPPI454 om 89> 180O> 180O> 180O> 180O Wet strength% 1503781-1983 27 25 25 45 Water absorption g / mz ISO535-1991 (E) 12 12 12 0 Cobb ins o inside vauenabsofpiion gm? 1so535-1991 (E) is 17 19 19 Cobbóo outside f _ gg Vapor permeability g / mz 2411 32 49 125 10 25 ° C 50% RH Vapor permeability g / mz 2411 139 117 525 45 38 ° C 90% RH _ Sliding angle ° Special method 1 1 12 13 18 Inside Sliding angle ° Special method 13 13 15 14 Exterior Hot embrittlement% Special method 72 70 67 86 Baking test - /% Special method 5 / 10-30 5 / 10-30 5 / 10-30 4/95 1) Remaining tear strength after 20 minutes at 200 ° C. 2) Release factor 1-5, where 5 is the best / proportion of the surface covered with pastries (sponge cake).

Table 1 shows that all four laminates have very good grease resistance and heat permeability.

The reference laminate D shows slightly better results in terms of wet strength, water absorption on the inside and hot embrittlement. Laminate D has lower vapor permeability than laminates A, B and C, which can be positive for some products. However, laminates A, B and C have a better (= lower) sliding angle on the inside, which is positive because this is a measure of how easy it is to disassemble the molds from each other when they are stacked. Finally, the baking test shows that the surface on the inside of laminate D is covered with 95% remaining pastry when the pastry has been removed from the mold, while laminates A, B and C are only covered to 10-30%. In addition, Laminate C exhibits high brightness and opacity achieved by adding titanium dioxide to the pulp. The titanium dioxide also gives the laminate a good grease capacity, which eliminates the risk of grease stains. In summary, it can be said that the reference laminate D certainly has a lot of positive properties, but that laminates A, B and C are still preferable because some important properties are better for these laminates and the remaining properties are still very good, while these laminates do not include the disadvantages previously described for plastic coated laminates of type D. Laminate D is also more expensive than laminates A, B or C.

The invention is not limited by the above-mentioned embodiments and examples, but may be varied within the scope of the appended claims.

Claims (2)

1. 0 15 20 25 30 35 9 511 651 CLAIMS - Materials for molds or packages, which material is made up of a plurality of layers, these layers comprising, seen from the inside of the mold / package, a first greaseproof paper (2), a layer with adhesive (4) and a second greaseproof paper (5), characterized in that said first (2) and second (5) greaseproof papers are made mainly of pulp produced according to the salting method, that each of said first (2) and second (5) greaseproof papers have a basis weight of 30-100 g / m and that a water-repellent layer (6) is applied to the outside of said second (5) greaseproof paper. 2.. Material according to claim 1, characterized in that said water-repellent layer (6), which is applied on top of the second greaseproof paper (5), mainly comprises an acrylic polymer, preferably a modified one, alternatively a polyacrylate resin polymer, a styrene-acrylate copolymer , an acrylic acid copolymer or a combination thereof, with a modified acrylic polymer being most preferred. . Material according to claim 2, characterized in that said water-repellent layer (6), which is applied on top of the second greaseproof paper (5), also comprises wax. . Material according to claim 1, characterized in that said water-repellent layer (6), which is applied on top of the second greaseproof paper (5), mainly comprises silicone. . Material according to any one of the above claims, characterized in that a grease and water-repellent layer (1) is arranged on the inside of said first greaseproof paper (2). . Material according to any one of the preceding claims, characterized in that a cover layer (3) is arranged between said first greaseproof paper (2) and said layer of adhesive (4), preferably comprising latex, polyvinyl alcohol or water. . Material according to any one of the preceding claims, characterized in that said first greaseproof paper (2) is coated (2a, 2b), preferably on both sides, preferably with a starch adhesive, polyvinyl alcohol or latex, with starch adhesive being most preferred. 10. A material according to any one of the preceding claims, characterized in that said second greaseproof paper (5) is coated (Sa, Sb), preferably on both sides, preferably with a cellulose derivative, starch glue or polyvinyl alcohol, with cellulose derivatives being most preferred. Material according to claim 5, characterized in that said grease and water repellent layer (1), on the inside of the mold / packaging, mainly comprises silicone. Material according to any one of the preceding claims, characterized in that said layer of adhesive (4) mainly comprises a hardening adhesive, preferably a polyurethane adhesive which is free from solvent. Material according to any one of the preceding claims, characterized in that said first (2) and / or second (5) greaseproof papers contain wet strength agents. Material according to any one of the preceding claims, characterized in that said first (2) and / or second (5) greaseproof papers contain fillers, preferably titanium dioxide, preferably in an amount of about 1-10% and even more preferably 2.5- % calculated on dry concentrations.