Filter-bag for infusion products and method for making filter-bag

Abstract

A filter-bag for liquid infusion products including a thermoformed body with filtration properties having an inner volume defined by a bottom, a mouth delimited on the perimeter by an upper flat edge, and a connecting wall between the bottom and the upper edge; the wall being provided with at least one rib extending from the bottom towards the upper edge in such a way as to define at least two chambers for containing corresponding infusion products separate from each other and included in the internal volume of the thermoformed body; a flat piece of non-thermoformable filter material, having transparency characteristics, and associated with the upper edge of the body for covering the opening and separating the chambers obtained in this way.

1 . A filter-bag for infusion products, wherein it comprises:
 a thermoformed body with filtration properties having an inner volume defined by a bottom, an opening delimited on the perimeter by an upper flat edge, and at least one connecting wall between the bottom and the upper edge; the at least one wall being provided with at least one rib extending from the bottom towards the upper edge in such a way as to define at least two chambers ( 6 ,  7 ) for containing corresponding infusion products (P 1 , P 2 ) separate from each other and included in the internal volume of the thermoformed body;   a flat piece of non-thermoformable filter material, having transparency characteristics, preferably of the fabric type, and associated with the upper edge of the thermoformed body for covering the opening and separating the chambers ( 6 ,  7 ) obtained in this way.   
     
     
         2 . The filter-bag according to  claim 1 , wherein the at least one rib extends towards the upper edge to form at least one further inner wall in such a way as to interrupt the continuity of the bottom. 
     
     
         3 . The filter-bag according to  claim 1 , wherein the at least one rib has an upper end and has an extension, calculated starting from the bottom, such that the upper end comes into contact with the flat piece of non-thermoformable filter material. 
     
     
         4 . The filter-bag according to  claim 1 , wherein the upper edge has a circular shape and the at least one rib is configured to obtain a diametric separation diameter of the thermoformed body in such a way as to define two chambers ( 6 ,  7 ) of volume substantially identical through the formation of a twin lobed bottom. 
     
     
         5 . The filter-bag according to  claim 4 , wherein the upper end of the at least one rib has a rectilinear extension in such a way as to define two separate further inner walls, mutually parallel, starting from the bottom and projecting towards the upper edge. 
     
     
         6 . The filter-bag according to  claim 4 , wherein the upper end of the at least one rib has an undulating extension in such a way as to define two separate walls with an undulating extension and parallel with each other, starting from the bottom and projecting towards the upper edge. 
     
     
         7 . The filter-bag according to  claim 4 , wherein the upper end of the at least one rib is coplanar with the upper edge and connected at the edge in at least two points which are opposite each other to define an upper auxiliary edge. 
     
     
         8 . The filter-bag according to  claim 1 , wherein the upper edge has a circular shape and the at least one rib is configured with an annular extension inside the perimeter of the upper edge to obtain a circular separation of the inner volume of the thermoformed body and in such a way as to define two separate chambers of different volumes. 
     
     
         9 . The filter-bag according to  claim 1 , wherein the at least one rib is ring-shaped and concentric relative to the upper edge in such a way as to define two chambers with annular extension. 
     
     
         10 . The filter-bag according to  claim 1 , wherein the at least one rib is ring-shaped and concentric relative to the upper edge in such a way as to define two chambers with annular extension one inside the other and concentric with each other. 
     
     
         11 . The filter-bag according to  claim 1 , wherein the flat piece is made of non-thermoformable filter material with air permeability greater than 1000 cm 3 /cm 2 ·s, preferably between 1000 and 10000 cm 3 /cm 2 ·s, more preferably between 3000 and 7000 cm 3 /cm 2 ·s. 
     
     
         12 . A method for forming a filter-bag for infusion products, wherein it comprises the steps of:
 preparing a continuous strip of thermoformable filter material;   preparing a die comprising a head provided with a cavity forming an inner volume for a thermoformed body of the filter-bag to be formed; the cavity having a bottom, a mouth delimited on the perimeter by an upper flat edge and at least one connecting wall between the bottom and the upper edge; the head of the die being equipped with at least one rib extending from the bottom towards the upper edge in such a way as to define at least two chambers which are separate from each other and included in the inner volume of the head;   preparing a punch comprising a head shaped to match the cavity of the head of the die;   positioning a portion of the continuous strip of thermoformable filter material between the die and the punch;   hot plastic deforming of the portion of strip of thermoformable filter material by moving towards each other the corresponding heads of the die and of the punch so as to obtain a thermoformed body having an inner volume defined by a bottom, a mouth delimited on the perimeter by an upper flat edge, at least one connecting wall between the bottom and the upper edge; the at least one wall being provided with at least one rib extending from the bottom towards the upper edge in such a way as to define at least two chambers for containing corresponding infusion products separate from each other and included in the internal volume of the thermoformed body;   dosing a first infusion product in a first chamber of the at least two chambers;   dosing a second infusion product in a second chamber of the at least two chambers;   preparing a flat piece of non-thermoformable filter material with transparency characteristics;   joining the piece of non-thermoformable material on the upper edge of the thermoformed body to close the opening, in such a way as to form a filter-bag.   
     
     
         13 . The method according to  claim 12 , wherein the step of preparing a flat piece of of non-thermoformable filter material with transparency characteristics comprises preparing a flat piece of non-thermoformable filter material with air permeability greater than 1000 cm 3 /cm 2 ·s, preferably between 1000 and 10000 cm 3 /cm 2 ·s, more preferably between 3000 and 7000 cm 3 /cm 2 ·s.