This invention relates to a paper composite for realizing three-dimensional packages for possibly solidifiable products in the liquid state, or for granular or powder products, a method for realizing such packages and a package obtained through the method.
Methods for packaging in metered quantities possibly solidifiable liquid products or granular or powder products for consumption are known. In one of these methods, half-casings of substantially rigid plastics material for example polypropylene are thermoformed and joined together along their edges to form a cavity, which can then be filled by a traditional filling machine. If the product is to be used in the liquid state, granular state or powder state the package obtained in this manner is ready for marketing after sealing. If however the product is to be used in the solid state (for example ice-creams), after the filling operation the filled with the liquid product and sealed package is refrigerated and preserved under refrigerated conditions until its consumption.
Independently of the nature of the packaged material, these known packages have the advantage of being formable in practically any shape, but also have certain drawbacks, and in particular:
a considerable cost, related to the cost of the plastics material used,
practically no ecological merits, given the non-biodegradable nature of the plastics used,
a certain weight, with consequent transport costs,
a space requirement after use, in that the used package cannot be substantially reduced in volume compared with the full package.
It is also known to package generally liquid products using a continuous tubular element of polyethylene-coated cardboard which is filled in portions separated by transverse welds, transverse cuts then being made through said welds. The package is generally of tetrahedral, parallelpiped or cylindrical shape, depending on the manner in which the transverse welds are made and on the folding operations to which the package may be subjected after its separation from the continuous tubular element.
This known method considerably accelerates the packaging operations but has certain limitations both in terms of obtainable shapes, and of overall dimensions, of the package after its use, and of costs.
An object of the invention is to eliminate such drawbacks and to realize a composite for forming metered packages, practically of any shape, for products in the liquid, granular or powder state, which has a low cost.
A further object of the invention is to realize very light packages, such as to minimize packing and transport costs.
A further object of the invention is to provide a method which enables the package to be reduced to minimum volume after use.
A further object of the invention is to provide a method which enables traditional commercially available packaging equipment to be used.
All these objects are attained according to the invention through a paper composite for realizing packages in three-dimensional form having a layer of yieldable paper with a degree of yieldingness in any direction not less than 10% and impermeablilizing film having a yieldingness compatible with yieldable paper.
The invention also foresees a method for realizing packages where a leaf of composite is faced to a cavity of at least a mould, the leaf being bounded in correspondence of a continuous edge of the cavity, and subsequently tangentially stretching the leaf of composite to adhere to an inner surface of the cavity to obtain a concave valve. The valve has the shape of the cavity.
The package so obtained a concave container having a closure film applied to the filling, and may have two concave valves joined together along the facing edges.