WO2015173677A1

WO2015173677A1 - Method for making vegetable fiber containers

Info

Publication number: WO2015173677A1
Application number: PCT/IB2015/052856
Authority: WO
Inventors: Bruno SPOZIO; Giancarlo Bissoli
Original assignee: Isap Packaging S.P.A.
Priority date: 2014-05-14
Filing date: 2015-04-19
Publication date: 2015-11-19

Abstract

A method for the manufacturing of containers made of vegetable fiber comprises the operating steps of dipping the pulp of vegetable fiber in a bath with a first predetermined quantity of additives and to place the compound thus obtained within a thermoforming mold to form at least one first layer of such a vegetable compound with additives; dipping the vegetable fiber pulp in a bath with a second predetermined quantity of additives and placing the compound thus obtained into said thermoforming mold superimposed to said first layer to form at least one second layer of vegetable compound with additives; and making the drying of the first and second layer superimposed one to another so as to make a multi-layer thermoformed container having a specific geometric shape molded by said thermoforming mold.

Description

METHOD FOR MAKING VEGETABLE FIBER CONTAINERS

The present invention relates to a method for the production of containers made of vegetable fiber.

In particular, the subject invention finds application to advantage in the production of thermoformed containers in use in the sector of packaging and packaging of products and foodstuffs, to which the following description will make explicit reference without thereby losing generality. In the field of packaging of food products, it is known the use of thermoformed containers made from a pulp of vegetable fiber, such as cellulose from wood, bamboo, palm, sugar cane, waste paper or natural fibers and equivalent intended to be used in replacement of traditional plastic containers and the like with high environmental impact. Examples of such containers are described and illustrated in EP 1291283 A1 and EP 1325983 A1.

Currently, the food containers of the type specified above include plant fibers that are previously worked (pulping) and treated with addition of considerable amounts of additives, such as glues, starches, chemical additives containing fluorocarbon or similar substances, and/or other to make compatible the containers to the chemical- physical characteristics of the foods contained therein.

The addition of such large quantities of additives in the vegetable fibers, some of these (especially fluorine carbonates) of high cost, in addition to the contribution of energy required in the thermoforming process makes the final containers present very expensive, for their realization, and also the recipes applied in process currently do not allow to ensure the proper balance between the characteristics of biodegradable and compostable containers thus obtained required by current regulations regarding the disposal environment, and optimal performance in terms of strength and impermeability of the containers themselves.

Furthermore, in terms of specifications in the case concerning the packaging and containers for the containment and treatment of foods (for example heating and / or cooking in conventional ovens), you must follow narrow rules for individual different states and therefore the products certificates must match the requirements of the various regulations.

In particular, the main requirements are:

- The compliance suitability for food contact, for which are made the corresponding migration tests the conditions of use stated (eg: stay at high temperatures up to at least 180 °) ;

- The technological properties which are: waterproofing liquid, the resistance for the required time to the penetration of oil and grease, complete biodegradability and specifications for compostability, which in Europe is specifically regulated by the EN 13432. The most problematic aspect regards obtaining products which are able both to satisfy the high performance technological demands, which achieve the requirements of compostability, which depend mainly on the quantities of additives fluorine carbonates put into the mass of fibers ( expressed in ppm) and then release the element fluorine in the compost. This element unfortunately is what ensures the attainment of the grease resistance food.

To date, the technique used to achieve the technological requirements necessary for the use of the containers must give up or greatly limit such compostability.

The object of the present invention is that of providing a method for making containers of vegetable fiber capable of overcoming the drawbacks specified above.

In particular, an object of the present invention is to provide a method of making containers in vegetable fiber having a reduced overall rate of waterproofing additives.

Another object is to provide a method capable of allowing the reduction of the costs of the final containers vegetable fiber.

A further object is to provide a container vegetable fiber provided with optimal characteristics of biodegradability and at the same time of technological performance and water resistance.

The structural and functional characteristics of the present invention and its advantages with regard to the known art, will be still clearer and more evident from following claims, and in particular by an examination of the description that follows, referring to the attached figure, which shows the schematic of a preferred but non limiting form of implementation of the method in question. In accordance with the schematic shown, the method of the present invention comprises the following operating steps of:

- immersing or dipping the pulp vegetable fiber in a bath with a first predetermined quantity of additives (Figure attached at left), and placing the mixture thus obtained within a thermoforming mold for forming at least one first layer, defining the outer portion of a container, of such vegetable compound with additives (Figure attached at center);

- immersing or dipping the vegetable fiber pulp in a bath with a second predetermined quantity of additives, with a different recipe composition with respect to first amount (Figure attached at right) and placing the mixture thus obtained inside the mentioned thermoforming mold overlaying the first layer to form at least a second layer of vegetable compound with additives (Figure attached at center) defining the portion of a container which, in use, will come into contact with food;

- and making the drying of the first and second layer superimposed one to another so as to make a multi-layer thermoformed container having a determined geometric shape molded by said thermoforming mold.

In particular, the compound which defines the first layer, corresponding to the outer portion of the container, is in the wet state and substantially comprises a percentage of at least 70% of vegetable fibers of low quality, typically coming from extra-wooded vegetations, such as waste from cultures of reeds or straw (e.g. plantation of sugarcane or wheat) or hardwood plantations. These fibers with greater yield in their extraction (classified as short or very short fibers), if well refined and well mixed together give however sufficient strength characteristics, but above all they have a lower cost, and are still permitted for food use.

The above-mentioned first quantity of additives at low cost, such as starches, glues or similar defined exclusively for obtaining the eventual resistance to moisture penetration from the outside of the container or for the maximum increase of the resistance of a slow absorption time of the liquid from the inside of the container. In any case, no fluoride-based element, which is the most expensive and is also the one which conditions the attainment of the compostability is considered, so as to achieve a layer which, once dried, is able to be optimally biodegradable respecting the current regulations in terms of environmental recycling.

The possible addition of natural dyes or fillers (for example calcium carbonate) to the above cited low cost additives, is also able to define a specific color to the mixture which defines the first layer.

The compound which defines the second layer, corresponding to the inner portion of the container superimposed on the first layer, is in the wet state and substantially comprises either a percentage of about 30%, or preferably a lower percentage of vegetable fibers of high quality, or characterized by their greater compactness and strength and normally coming preferably from cellulose of conifers (long fibers with a low extraction yield). They have a higher cost and must meet all certifications permitted in use, still from their state of delivery and suitable for food contact according to the required standards. The mentioned second quantity of additives includes coagulants, natural or synthetic glues (e.g. AKD), bio-polymers, and fluorine-based chemicals, and is only defined for obtaining endurance performance over time, with resistance to the penetration of liquids and fats transmitted from the type of food, in direct contact with the interior of the container.

In this case, the additives of such second layer, even if unchanged in their concentration, lead to obtain a significant reduction of quantity than the entire mass of the container (sum of the two layers), and consequent cost reduction, unchanged technological performance and achievement of the requirements for the compostability.

The possible addition of natural dyes or fillers (for example calcium carbonate) to cited second quantity of additives is further able to define a second color specific to the compound that forms the second layer and it is such as to give a different color with respect to the color of said first layer. Preferably, but not limitedly, in the multi-layer thermoformed container thus obtained the thickness of the inner layer is equal to about a third of the total thickness of the multilayer container itself.

In this way, the container made of vegetable fiber obtained by applying the operating method described above is provided with optimal characteristics of biodegradability and at the same time of resistance and impermeability to food products that it will contain. Furthermore it must be noted that the subject method can be further developed so as to be able to produce also containers with three or more layers instead of two as heretofore described.

For example, keeping all environmental and technological characteristics unchanged, one can advantageously provide for the use of an intermediate layer disposed between said inner and outer layers.

Preferably, but not limitedly, such intermediate layer can be defined by materials suitably selected from external recycling sources, or also from other materials obtained from plastics which are either biodegradable or non-biodegradable, or from equivalent material, in order to increase the physical and mechanical properties of the container.

Claims

1. Method for the manufacturing of vegetable fiber containers characterized in that it comprises the operating steps of immersing vegetable fiber pulp in a bath with a first predetermined quantity of additives and disposing the compound thus obtained into a thermoforming mold for forming at least a first layer of said compound with additives, said first layer being defined in greater share by vegetable fibers of low quality from extra wooded vegetations; immersing the vegetable fiber pulp in a bath with a second predetermined quantity of additives and disposing the compound thus obtained inside said thermoforming mold in superimposition with said first layer to form at least a second layer of compound with additives defined in smaller share by high-quality cellulose fibers; and carrying out the drying of the first and second layers superimposed each other so as to realize a multi-layer thermoformed container having a determined geometric shape patterned by said thermoforming mold.

2. Method according to claim 1 , characterized in that compounds of said first and second layers are in the moist state.

3. Method according to claim 1 or 2, characterized in that said compound which defines the said first layer comprises substantially a percentage equal to about 70% of plant fibers of low quality defined by scraps from cultures of reeds or straw plantation of sugar cane, wheat or hardwood plantations.

4. Method according to one or more of the preceding claims 1 to 3, characterized in that said first quantity of additives comprises include starches, glues or similar.

5. Method according to claim 4, characterized in that said first quantity of additives further comprises natural colorings or equivalents..

6. Method according to one or more of the preceding claims 1 to 5, characterized in that said compound which defines the said second layer overlying said first layer comprises substantially a percentage equal to about 30% of plant fibers of cellulose.

7. Method according to one or more of the preceding claims 1 to 6, characterized in that said second quantity of additives includes coagulants, natural or syntetic adhesives, bio-polymers, or fluorine-based chemicals.

8. Method according to claim 7, characterized in that said second quantity of additives further comprises natural colorings or equivalents.

9. Thermoformed multilayer vegetable fiber container, in particular for food, obtained through the method according to one or more of the preceding claims 1 to 8.