FI120726B - Polymer-coated packaging material, use of the material, and packaging that is treated by heating - Google Patents

Description

Polymer-coated packaging material, use of the material and heat-treatable packaging

The present invention relates to a polymer-coated packaging material, particularly for heating packages to be treated, comprising a fiber base and polymer layers on both sides, which act as a moisture and / or light barrier. In addition, the invention encompasses the present invention. the use of packaging material for autoclave packaging; an autoclave packaging comprising polymer-coated fiber-based packaging material; and an oven-10 flow formed from polymer-coated packaging board.

Polymer-coated fiber-based packaging materials wherein one or both sides of the fiber base are provided with one or more overlapping coating layers are known for a variety of applications for various packaging purposes. An important area of application for such packaging materials is food packaging, such as cans, cases and boxes made of coated packaging cardboard and bags made of coated paper.

Typically required properties of food packages include a polymer-coated moisture barrier which may be intended to be a dry product. protection from external moisture, but also required to prevent the fiber · · j (* '20) substrates from wetting from the effects of the packaged product and / or external moisture.

Further, the properties required of the packaging material may include an oxygen barrier: ***, as well as a light shield designed to improve the shelf life of the packaged product and thereby *: .., thus extending its useful shelf life and / or shelf life. In many cases, the polymeric coating of the packaging material also requires heat sealability, ***: 25, which allows the product package to be sealed tightly.

• * * .., The moisture or water vapor barrier of the packing material can be achieved by a variety of coating · · · · · · · · · · · · · · · no no no no it no, depending on the type of polymer used and its layer thickness. Polyolefins, such as low density •: *: polyethylene (LDPE) and polypropylene (PP), which are the outer coating layer • · · ·. ··· are commonly used as moisture barrier. When arranged, they also serve as effective heat seal polymers. Polyethers such as polyethylene terephthalate (PET) can also be used as a moisture barrier in the packaging. Commonly used oxygen barrier polymers include, for example, ethylene vinyl alcohol copolymer (EVOH) and polyamide (PA). The traditional solution for providing light protection has been to provide the packaging material with aluminum foil 2, which has at the same time acted as an effective oxygen barrier, but now a replacement solution has been introduced to add light-absorbing pigments to the polymeric coating layers of the material. For example, WO 01/76976 discloses a packaging carton in which the heat sealing layer which becomes the inner surface of the package is dyed gray with carbon black and titanium dioxide in a manner that mimics the appearance of the aluminum foil traditionally used on the inner surface of the package.

The present invention relates specifically to packaging materials and packages formed therefrom which are subjected to heating, either during the manufacture of the product package or later when the product contained in the package is heated. 10 Such packages include, in particular, packages which are to be sterilized by heating, and in which the packaging material used must withstand the conditions of the sterilization treatment. Sterilization can be done by irradiation or by hot pressurized steam in an autoclave. The autoclave has typically processed closed metal can cans, but nowadays fiber-based packaging materials have also been offered for autoclave use. Thus, WO 02/28637 describes a packaging material for autoclave packages in which the cardboard base is provided with an oxygen barrier layer, polymeric heat seal layers and the necessary binder layers. The oxygen barrier layer is formed by an aluminum foil or alternatively an EVOH layer and polypropylene is used as the polymer for the binder and heat seal layers.

Another category of products to be heated is cooker meals intended to be heated in a microwave or oven. The coating polymer commonly used in these is PET, which withstands the furnace heating temperature without melting. The coating is on the inside of the flow to protect the cardboard base from packaging wax. In contrast, the outer surface of the stream may have been left • V. 25 without coating.

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In experiments with fiber-based food packaging to be processed in an autoclave, the Applicant has discovered the problem that -: **] bleached packaging board coated with transparent polymer layers tends to turn yellow in the autoclave at a temperature of about 130 ° C. Polymer coated cardboard * · *. In other words, the packaging changes its appearance in autoclave processing, which is a disadvantage for the market, especially for demanding applications.

• 9 9 9 999 · Corresponding cardboard yellowing problem also applies to oven heating or baking 9 99 | temperature-controlled cardboard oven cans. Yellowing or unchanged * * cardboard would be an advantage, especially in meal bowls, where the product is baked before 35 packages are marketed.

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The Applicant's earlier FI patent application 20030260, in accordance with PL 2 (2) in relation to the present application, proposes as a solution to the yellowing problem of the cardboard or autoclave package formed therefrom by white pigmentation of the nonwoven polymeric coating layer. With this solution, the packaging remains essentially white in the autoclave treatment, but in practice, slight yellowing cannot be prevented by the layer thicknesses and pigment levels involved. In other words, the packaging does not quite meet the requirement of unchanged appearance.

It is an object of the present invention to provide an alternative solution to the fiber base yellowing problem, the central object of which is that the appearance of the packaging material or the packaging formed therefrom is not noticeably altered in autoclave or similar heat treatment. It is essential in the packaging material of the invention that the other side of the fiber base, which becomes the outer surface of the package, is provided with two overlapping pigmented polymer layers such that the outer white pigmented polymer layer has 5-25% white pigment and the inner, closer , 05 to 0.5% of black pigment in order to stabilize the said side-brightness change of the material upon heating, with the public side 20 opposite to the fiber base the polymer layer is pigmented photoresist purposes only.

·· · I According to the invention, the overall color of the pigmented packaging material is white or ·· • * ·· slightly gray due to the effect of the black pigment under the white pigment. The degree of brightness depends on the amount of pigment used and their relationship, but the idea of the invention is to adjust the material ··· {*. *. 25 shades as close to white as possible and retain this shade on the packaging • •. ···. attenuation process. The result is achievable with a total amount of pigments of the same order of magnitude as the amount of white pigment in the top layer according to FI application 20030260.

The small amount of black pigment stabilized in accordance with the invention. The light color of the packaging material against the yellowing of the underlying fibrous base also has some light-absorbing effect. However, this effect is insufficient to protect Effective · · ·. ·; high light barrier pigmentation on the outside of the fiber substrate would render the material clear ·; · *: gray, like aluminum foil., If light protection is necessary, 35 invention requires a sufficient amount of pigmentation of the inner polymeric coating layer. , e.g., dyeing the inner coating layers of one or more fiber bases 4 as disclosed in said application FI20030260 or WO 01/76976.

The objects of the invention also include the use of packaging material as defined above for autoclave packaging, in particular autoclave 5, by heat-sterilizing food packaging.

Further objects of the invention comprise a sealed autoclave pack made of the above-described packaging material, characterized in that the package has two overlapping pigmented polymer layers on the outside of the fiber base such that the outer, white pigmented polymer layer has 10 the polymer layer is 0.05-0.5% black pigment for stabilizing against change in the brightness of the outside of the package fOR A autoclaving, and that inside the fiber base is packaged for protection purposes only light pigmented acid-lymeerikerros.

The desired shading of the material is achieved by overlapping pigmented layers having a total weight of 25-60 g / m, with a concentration of black pigment in the inner layer of between 0.05-0.5%, preferably about 0.06-0.15%, and the concentration of white pigment in the outer layer being between 5 and 25%, preferably between about 7 and 12%. Optionally, a black pigment-containing insert may be added. The white pigment may also be 5-25%, preferably about 7-15%, in the inner layer. It may be 5-25%, preferably about 7-15%. suitable for eg carbon black and white titanium dioxide.

* * ··· M · • Inside and outside the autoclave pack, tinting and packing ..]: Transparent polymeric heat seals can be imprinted on the inside and outside of the packaging, on the inside and outside of the package; ** flavoring layers which, in addition to insulating the inside of the package, are insulated with pigment. Polypropylene having a melting point of at least 130 ° C, i.e. higher than the heating temperatures used in the autoclave, is suitable as a heat seal polymer, as well as a polymer material for pigmented layers.

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It is also advantageous to provide the food package to be processed in the autoclave with at least one polymeric oxygen barrier layer, which may be located e.g. between the fiber base and the pigmented light barrier layer inside the package. Suitable materials for the oxygen barrier layer are e.g. EVOH and polyamide.

For packaging material according to the invention and for packaging to be treated by heating the bleaching paper or board made of bleached pulp is most suitable. However, due to the improved coverage of the pigmented polymeric layers according to the invention, the fiber base does not affect the color of the material to the extent that the white pigment is used according to the earlier application.

In addition to the autoclave package, special aspects of the invention also include a furnace pan made of polymer-coated packaging board that has the same heating yellowing problems as the autoclave package. The flow according to the invention is characterized in that it has two overlapping pigmented polymer layers on the outside of the base board such that the outer, white-pigmented polymer layer has 5-25% white pigment and the inner, closer to the base board has 0.05-0.5% a black pigment for stabilizing the brightness of the outside of the dish against change in the furnace heater-nuslämpötilassa, and in that the base board inside of the board 20 Resulting from this moisture-proof polymer layer ·· · • * • · ·

If the shelf life and shelf life of the product to be packaged in a dish, typically a microwave or oven cooked meal, is short, it may be unnecessary to equip the stream with light protection. However, if necessary, a light-absorbing pigment coating layer may be provided on the inner surface of the flow in the same manner as in the autoclave package described above, wherein the pigmented layer would be located between the cardboard base and the PET layer forming the inner surface of the flow.

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which Figures 1-5 schematically illustrate five different packaging materials used in the applications of the invention. Fig. 6 shows a packaging made of the packaging material of Fig. 2 by folding and heat-sealing, and Fig. 7 shows a mold made of a packaging material of the packaging material of Fig. 5.

Figure 1 illustrates a yellowing-protected and polymer-protected packaging board of a yell-protected and light-protecting packaging product in its simplest form. The packaging cardboard comprises, in the above order, a titanium dioxide-coated white layer 2, a carbon black pigmented coating layer 3, a bleached paperboard fiber base 4, a titanium dioxide and 10 carbon black 3-layer, blackened aluminum foil 9, a film coating 8. The overlapping coating layers can be formed by coextrusion on different sides of the fiber base 4. The material is foldable and heat sealable into a sealed product package such that the overlapping, pigment-coated polymer layers 2, 3 are applied to the outer surface of the package, i.e. outside the fiber base 4, and a gray light barrier layer 8 and a transparent heat seal layer 9 on the inner surface of the package, i.e. inside the fiber base 4. The overlapping pigmented layers 2.3 on the outside of the package give the package a light, almost white color which does not change during the heat treatment of the package.

Figure 2 shows a packaging carton suitable for food packaging, in particular autoclave, with transparent, polypropylene heat sealing layer 1 on the exterior surface of the packaging compared to Figure 1, polyamide and EVOHr oxygen oxide in fibrous base 4 , 6 as well as a binder layer 7 which adheres to the light barrier layer 8 of the EVOH layer 6, the materials of which are, for example, a polymer marketed by Mitsui Chemicals under the name Admer. The material package is thus protected by pigmented layers 2, 3 against the yellowing of the fiber base 4 in the autoclave, and the inner: * \ * oxygen barrier layers 5,6 and the light barrier layer 8 protect the packaged product pi-; *! *: for its shelf life and useful shelf life, • ·: 30 Figure 3 shows a modification of the packaging board of Figure 2, with the addition of a second polyamide layer 5 'and polypropylene and binder layers 9', 7 'dry, ·! · Between the base 4 and the polyamide layer 5. The arrangement enhances the oxygen barrier layers and fiber base adhesion. Additional features include the symmetry of the 5-layer combination 35 of binder 7 ', polyamide 5, • ·· * * EVOH 6, polyamide 5' and binder 7, which is advantageous in forming coating layers by coextrusion, and the possibility of incorporating polypropylene 9 ', binder 7 \ polyamide 5 , A five-layer structure of EVOH 6 and polyamide 5 'into a material as a film laminate, which are commercially available on the market. Such a finished laminate can be sealed to the board while the other coating layers 5 of the material are produced by coextrusion.

Figure 4 shows a second modification of the packaging material, which differs from that shown in Figure 3 only in that a second gray pigmented light barrier layer 8 'has been added to the inside of the fiber base 4, thereby obtaining a symmetrical overall layer symmetry.

Packaging cartons for autoclave use according to Figures 2-4 can be modified in various ways within the scope of the invention. For example, sufficient oxygen barrier may be achieved with a single EVOH layer 6, whereby the polyamide layers may be omitted. If the pigmented layers of the outer surface of the package are used as heat sealing layers 15, the outermost, transparent heat sealing layer 1 may also be unnecessary. Optionally, the inner layer 3 containing the black pigment may also be doped with a white pigment, e.g. titanium dioxide, whereby the overall color of the layer is light gray.

In the packaging materials of Figures 1-4, the fibrous base 4 may be formed by a packaging board containing an attenuated sulphate pulp having a weight in the range of 130 to 400 g / m 2, preferably 170 to 300 g / m 2. Alternatively, if the fiber base consists of lightweight paper, it may have a weight of 20-120 g / m2. The weight of each of the PA or EVOH oxygen barrier layers 5, 6 may be from 3 to 15 g / m 2, preferably from 5 to 10 g / m 2. The weight of the transparent heat sealing layers 1, 9 may be 5-30 g / m 2, preferably 7-20 g / m 2. The fiber white exterior white pigmented layer 2 may have a weight of 20 to 50 g / m 2, and the black pigmented layer 3 may have a weight of 5 to 10 g / m 2 of the fiber backing 4 inner gray pigmented light barrier layer. The weight of 8 may be 10-50 g / m 2, preferably 25-40 g / m 2. The content of titanium dioxide in the white colored coating layer 2 may be 5-25%, preferably 7-12%. Carbon black content. The thickness of the inner coating layer 3 may be 0.05-0.5%, preferably 0.06-0.15%.

If the layer 3 also contains titanium dioxide, its content may be 5-25%, preferably 7-15%. The gray pigmented light barrier layer 8 has a carbon black content of 0.05-0.5%, preferably 0.12-0.15% and a titanium dioxide content of 5-25%, preferably 7-12%, respectively. The admer binder layers 7 may have a weight of 3 to 35 g / m 2, preferably 5 to 10 g / m 2.

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Figure 5 illustrates a polymer-coated packaging board specifically designed for oven cans. The cardboard sandwich structure corresponds to that shown in Figure 1, except that the coating polymer is PET instead of polypropylene, which can withstand a maximum furnace operating temperature of about 250 ° C without melting. The overlapping coating layers 2, 3 containing white and black pigment 5 are applied to the outside of the flow to protect its appearance against the yellowing of the cardboard due to heat, and the inside coating layer 8, which mimics the appearance of aluminum foil, gives the sealed container a molded product. If there is no need for a light shield, the gray layer 8 on the inside of the flow may be left off.

Fig. 6 shows a rectangular rectangular sealed article package 10 made by folding and heat sealing the blank of the packaging material of Fig. 2. The figure includes a partial enlargement of the wall of the package, which shows that the overlapping polymer layers 2, 3 containing white and black pigment are on the outside of the base board 4, and a gray pigmented light protective layer 8 on the inside. The light exterior of the package does not change its appearance when autoclaved and the inside of the package is gray and resembles aluminum foil. At the seam locations 11 of the package, the edges of the blank overlap and the polypropylene layers 1, 9 of the opposite sides of the carton are heat sealed to each other. Polypropylene of the inner pigmented layers 2, 8 is also involved in the formation of seams.

M t • V Figure 7 shows a furnace pan 12 made by molding a blank of the packaging material of Figure 5. The figure includes a partial magnification of the Γ · .. wall of the stream, which shows that the white and black pigments contain poly-; ** ·. the sea layers 2, 3 are outside the bottom of the flow board 4 to prevent the flow of the flow i ·· 25 from heating, and the aluminum foil resembles a pigment -. '·· *. said light shield layer 8 enters the inside of the base board 4.

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The following examples include tests to test the masking effect of pigments added to polymer coatings against the yellowing of the fiber base of the packaging material in an autoclave. Fiber backing; On the I · 30 side, the light protection provided by the pigments is not affected by the autoclave treatment and has therefore not been tested.

• s ···. ·. ; Example 1 (Comparison) • * · * · * i A series of tests were carried out on packaging materials with a bleached pulp packaging board weighing 210 g / m 2. On the other side, the carton was coated with a yellowing polymer layer containing 7.5% titanium dioxide doped with polypropylene and having a basis weight of 58 g / m 2. The opposite side of the carton was coated with a polymeric, non-pigmented coating layer (Test Materials 1-4) or a layer structure formed by two or three overlapping non-pigmented polymer layers (Test Materials 5-9). The coating layers were made of polypropylene (test materials 1 and 2), a mixture of 70% polypropylene and 30% polyethylene (test materials 3 and 4), a double layer structure with an inner layer of COC (Topas 8007D) and an outer layer of said polypropylene and polyethylene. a blend (test material 5), a three-layer structure 10 with an inner layer of polyamide, a next layer of binder (Admer NF 912E) and an outer layer of said polypropylene / polyethylene blend (test materials 6 and 7), or a three-layer structure with an inner layer of ethyl vinyl alcohol copolymer Admer NF 912E) and outer layer of polypropylene (test materials 8 and 9).

The test pieces were heated in an autoclave for 20 minutes from room temperature to a treatment temperature of 130 ° C for 60 minutes. After treatment, the autoclave was cooled back to room temperature for 20 minutes where the specimens were removed from the autoclave. For each test material were measured to both sides of the brightness (ISO%) before the autoclave treatment (initial brightness) and after car 20 klaavikäsittelyn. The results are shown in Table 1, which also indicates the weights of the non-pigmented polymeric coating layers in each of test materials 1-9.

• a • · • ·· ··. table 1

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Il I Brightness (ISO%) ·· '·' Coating Amount, g / m2 Pigmented Pigmented! , * Half_____ half _ton half_. ***. Inner Intermediate Out Alkn 60 Start 60 "· '_layer Layer Layer__min .__ min.

I__ 69.4 87.8 82.5 83.3 63.8; v 2__ 41.7 87.9 82.1 83.7 64.7 Ϊ _3__ 62.1 87.3 80.7 83.6 64.7 4__ 38.4 88.1 82.5 83.9 65.5 * "· * _5_22.5 _ 33.1 87.7 80.8 83.3 62.3 ϊ. ·. 6_ 13.2 6.3 42 , 0 87.4 81.5 83.5 62.2 "ϊ · 7_12.9 5.9_ 50.4 87.8 81.9 83.4 61.5 8_ 10.4 5.6 42.1 88, 1 82.7 83.5 64.2 * "9 111.5 6.1 51.7 87.9 82.6 83.5 63.6 25 • · · '·. The test results in the table show the problem to be solved by the invention. , horizontally • s leuden a substantial drop due to the fiber base yellowing of what the fiber base of the unpigmented side of the colorless coating layers are unable to mask 10 system. fiber base on the opposite, the earlier FI application in accordance 20.03026 million titanium dioxide pigmented side of the initial brightness of the pigment makes was high and there has been a slight brightness autoclaving however, with the final lightness exceeding 80% ISO in all cases.

Example 2 (invention)

The test set corresponding to Example 1 was made on materials with a bleached pulp packaging board weighing 250 g / m 2. The other side (outside) of this carton, which is intended for the outer surface of the autoclave package, was provided with a two-layer polypropylene coating with carbon black and titanium dioxide (test materials 1-7) or carbon black (test materials) and the polypropylene was doped with titanium dioxide alone. In some materials (Test Materials 20-22), the opposite side of the carton, which becomes the inner surface of the autoclave package, was provided with a carbon black (0.15%) and titanium dioxide (12.5%) gray-pigmented polypropylene-based inner lightweight layer of 27 g / m. , and with a transparent polypropylene layer covering 23 g / m2. The measured material to the exterior of said brightness values before and after autoclaving are shown in Table 2. The Table also includes the exterior material of the pigmented polymer layers of pigment-20 concentrations and the layer weights.

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Table 2 ___

Exterior Coating floors ... D / "". ......,, 2. ..... .. Lightness ISO% Bale Stem G / M Pigment Concentrations (%)

Test Material ------ · TTi · Inner Layer Outer Inner Outer r .ah ctx ·,. floor Start 60 min layer layer c ^ Ti () 2 1 __9__19 0.15 12.5 12.5 67.7 68.2 2 __9__21 0.15 12.5 12.5 70.0 70.6 3 __9__28 0, 15 12.5 12.5 74.8 74.6 4 __12__25 0.15 12.5 12.5 74.2 72.3 5 __12__30 0.15 12.5 12.5 74.6 75.9 6 __12__34 0 , 15 12.5 12.5 71.0 72.0 7 __12__41 0.15 12.5 12.5 79.9 80.1 8 __6__21 0.12 - 12.5 65.2 63.4 9 __6__30 0, 12 - 12.5 76.3 75.0 10 __6__25 0.09 - 12.5 75.4 74.1 11 __6__30 0.09 - 12.5 77.4 74.5 12 __9__23 0.09 - 12.5 67.9 67.1 13 __9__29 0.09 - 12.5 74.2 73.2 14 6 26 0.06 - 12.5 76.9 75.0 j V 15__6__30 0.06 - 12.5 77.6 73.9 Γ ··. 16__9__26 0.06 - 12.5 74.6 71.0 f · .. 17__9__30 0.06 - 12.5 77.2 75.0. · * ·. 18__9__33 0.06 - 12.5 80.5 78.8: V. 19__9__40 0.06 - 12.5 82.3 81.0 ** .. f 20 6 19 0.09 - 12.5 73.3 70.9 21 __6__25 0.09 - 12.5 77.3 75.6 22 6 30 0.09 - 12.5 82.5 81.2 • · · • * • a ··· • · • 9 ···. From the results, it can be seen that the packaging material of the invention can be tinted to a brightness, which at best is more than 80% ISO, with a slight, practically insignificant change in the autoclave concept. The final brightness after treatment is i / .j almost the same as in FI application 20030260, but the stability of the light shade against the change in treatment is clearly better.

Claims (16)

1. Polymer-coated packaging material intended especially for packages treated by heating and comprising a fiber bottom and as a moisture and / or light-protecting polymer layer on each side of the fiber bottom, characterized in that one side of the fiber bottom is provided with two on each other. coated pigmented polymer layers such that the outer white pigmented polymer layer contains 5 - 25% white pigment and the inner polymer layer closest to the fiber bottom contains 0.05% - 0.5% black pigment to stabilize the brightness of the material. said side against changes that occur during heating, and that on the opposite side of the fiber bottom there is a pigmented polymer layer which provides light protection. Packaging material according to claim 1, characterized in that in said inner polymer layer there is mixed black and white pigment and that in the outer polymer layer there is only white pigment. Packaging material according to claim 1 or 2, characterized in that said polymeric layer providing light protection has been tinted gray with the help of black and white pigment. 20.. . Packaging material according to claim 3, characterized in that on the layer I 'provides light protection there is a transparent heat sealing layer made of polymer, the point of which of which is at least 130 ° C. a a • · * '... · 25 Packaging material according to any preceding claim, characterized in that the material is provided on each side with a highly transparent transparent heat sealing layer of polymer, the melting point of which is at least 130 ° C. 6. Packaging material according to any of the preceding claims, characterized. ** '. The material comprises at least one polymeric oxygen barrier layer. ··· * · * Σ Packaging material according to claim 8, characterized in that the oxygen barrier layer is located between the fiber bottom and the pigmented polymer layer. • * «e · • · ♦ ··· · 35 Packaging material according to claims 1-7, characterized in that the material comprises in that order a polymeric heat sealing layer, a white pigmented polymer layer, a polymer layer containing a black polymer, a fiber bottom, or several polymeric oxygen barrier layers, a binder pigment, a gripping pigment. -limeric light protection layer and a polymeric heat sealing layer. Packaging material according to any of the preceding claims, characterized in that polymeric material in the heat sealing layers and / or the pigmented layers is polypropylene. Packaging material according to any of the preceding claims, characterized in that the fiber bottom consists of bleached packaging material or cardboard. 10 Use of a packaging material according to any preceding claim in packages treated in an autoclave. Use according to claim 11 of food packaging to be sterilized in an autoclave. A closed autoclave package comprising fibrous-bottom packaging material and polymer coating, characterized in that there are two pigmented polymer layers outside the fiber bottom of the package, such that the outer white pigmented polymer layer contains 5-25% white pigment and the inner polymer layer as the inner polymer layer. contains 0.05% - 0.5% black pigment to stabilize the brightness of the outside of the package against changes that occur in an auto-claw treatment, and that on the inside of the fiber bottom there is a pigmented polymer layer that provides light protection for the packaged product . 25 • « Autoclave package according to claim 13, characterized in that it is a food package processed in an autoclave. • t · ··· 15. Oven mold formed of polymer-coated packaging board, characterized in that the V: 30 form outside the bottom carton comprises two pigmented polymeric layers, such that the outer white pigmented polymer layer contains 5-25%: white pigment and the inner polymer layer which is closer to the bottom layer. contains lti <J 0.05% - 0.5% black pigment to stabilize the brightness on the outside of the mold against the front. changes that occur at the oven's heating temperature, and that there is a polymeric layer on the bottom of the furnace inside a polymer layer that protects the carton from moisture from the product. 16. Oven mold according to claim 15, characterized in that on the inside of the bottom board there is also a pigmented polymer layer which provides light protection for the product to be packaged in the mold. 5 ·· · · · · · · · · · · · · · · · · · · · 1 · · · · · · · · · · · · · · ··· • · ··· • · · · · · · 1 · • · · · · · · ··· · · · · · 1 ♦ • · t * · ··· • · · · · · · 1 »· •»