Patent Publication Number: US-2016236845-A1

Title: Container with a cross-section which changes between a square contour and a rectangular contour

Description:
The invention relates to the field of containers made of thermoplastic material, such as PET, and more particularly, although not exclusively, the containers, such as bottles, that can be hot-filled. 
     A container is in general manufactured by blow molding or stretch blow molding of an injected preform, which is first heated in a stream in a furnace that is provided with elements for heating by radiation, and then introduced hot into a mold that is provided with a cavity that defines the counter-imprint of the container. 
     By way of indication, the temperature of the liquid during a hot-filling frequently exceeds 60° C. and commonly reaches 90° C. to 95° C. (or a temperature that is higher than 15 the glass transition temperature of the PET). 
     An ordinary container offers an inadequate mechanical strength that during hot-filling would be reflected by significant deformations resulting from the thermal shock that accompanies such a filling. In addition, during the subsequent cooling of the contents, the container would also deform because of the internal depressurization that accompanies the reduction of the temperature. 
     Also, the containers designed for hot-filling (referred to as HR, acronym for the English expression “heat-resistant”) benefit from a suitable manufacture and particular structural arrangements that make them less sensitive to deformations and make it possible for them to preserve their general shape permanently. 
     In general on the container, deformable zones with controlled deformation are provided. Thus, it is known to provide the body of the container with panels that, during filling, will bend under the combined action of the temperature and the hydrostatic pressure and that, when the liquid is going to cool down, will, conversely, be retracted for accompanying the reduction of the liquid volume. 
     Containers are thus also known that have an approximately square cross-section, provided with panels connected by slightly bent facets, placed on the four corners of the square and designed to be deformed by flattening to absorb the depressurization that accompanies the cooling of the contents, cf., for example, the U.S. Pat. No. 7,699,183 (COCA COLA). 
     Although in theory, the deformation of the container is controlled, it is noted in practice that such is not the case. Actually, the container has a tendency to deform overall, flattening from its initially square shape into a diamond shape in which the angles between the panels are no longer right angles. The result is a lack of rigidity of the container during handling. This lack tends to get worse with the reduction in the quantity of material used (which is the current general tendency in container manufacturers, essentially for reasons of cost and changes in pollution-control standards). 
     It is also noted that this deformation is all the greater at mid-height of the body. 
     Various solutions exist for eliminating this problem. 
     A first obvious solution consists in increasing the thickness of the container. A second solution consists in providing the container with a belt, cf., for example, the European patent application EP 2 473 413 (SIDEL PARTICIPATIONS). 
     These solutions both require, however, an addition of material for the manufacturing of the container, which is contrary to the current specifications, which in contrast require a reduction in the quantity of material used. 
     A first objective is to propose a container that offers better resistance to deformation, in particular due to depressurization that accompanies the cooling of the contents when the latter were introduced hot. 
     A second objective is to propose a solution that makes it possible for the container to preserve its general shape when it is subjected to internal depressurization. 
     A third objective is to propose a container with a square cross-section that does not have a tendency to adopt a diamond shape when it is subjected to internal depressurization. 
     So as to attain at least one—and preferably all—of these objectives, a container is proposed that is made of plastic material, comprising a body that extends along a main axis, a shoulder that forms an extension of the body from an upper side, and a bottom that forms an extension of the body from a lower side, with the body comprising four faces, namely a first pair of faces that, in cross-section, are parallel to one another, and a second pair of faces that, in cross-section, are parallel to one another and perpendicular to the faces of the first pair, with the faces of the first pair being separated, in the cross-section in the vicinity of the shoulder as well as in the vicinity of the bottom, by a distance D, and the faces of the second pair being separated, in the cross-section in the vicinity of the shoulder as well as in the vicinity of the bottom, by a distance D′, with this container being such that:
         The values of D and D′ are approximately equal, i.e., they verify the following equation:       

     
       
         
           
             0.95 
             &lt; 
             
               
                 D 
                 ′ 
               
               D 
             
             &lt; 
             1.05 
           
         
       
         
         
           
             In the cross-section in a median zone of the body, the faces of the first pair are separated by a first distance D 1  and the faces of the second pair are separated by a second distance D 2  that is different from D 1 . 
           
         
       
    
     This shape ensures better resistance on the part of the container to deformations, in particular during internal depressurization that accompanies the cooling of the contents. 
     Various additional characteristics can be provided, by themselves or in combination:
         The distances D 1  and D 2  are in a ratio of between 0.85 and 0.95;   The distances D 1  and D 2  are in a ratio of approximately 0.93;   At least one of the distances D 1  and D 2  is less than the distance D;   The distances D 1  and D 2  are both less than the distance D;   The body comprises beveled facets connecting the faces;   In the cross-section in the vicinity of the shoulder as well as in the vicinity of the bottom, the facets form an angle of approximately 45° with the faces;   In the cross-section in said median zone of the body, the facets form an angle that is, strictly speaking, less than 45° with the faces of the first pair;   In the cross-section in said median zone of the body, the facets form an angle of between 37° and 43° with the faces of the first pair;   In the cross-section in said median zone of the body, the facets form an angle of approximately 400 with the faces of the first pair.       

    
    
     
       Other objects and advantages of the invention will be brought out in the description of an embodiment, provided below with reference to the accompanying drawings in which: 
         FIG. 1  is a realistic front view showing a container made of plastic material; 
         FIG. 2  is a side view of the container of  FIG. 1 , rotated by 90° in relation to this figure; 
         FIG. 3  is a cross-section of the container of  FIG. 1 , taken interchangeably along the plane III-III or the plane III′-III′; 
         FIG. 4  is a cross-section of the container of  FIG. 1 , taken along the plane IV-IV. 
     
    
    
     A container  1  (in this case a bottle) made of plastic material such as PET is shown in  FIGS. 1 and 2 . In the illustrated example, the container has a capacity of 0.5 l, but this capacity could be any suitable or known value, whether it is lower (typically 0.33 l or 0.25 l) or higher (typically 1.5 l, or else 2 l). 
     The container  1  comprises multiple parts, namely a body  2 , a shoulder  3  that forms an extension of the body  2  from an upper end of the latter, a neck  4  that tops the shoulder  3 , and a bottom  5  that forms an extension of the body  2  from a lower end of the latter. 
     The body  2 , which forms the major portion of the volume of the container  1 , extends along a main axis X that approximately connects the geometric center of the neck  4  and that of the bottom  5 . In assuming that the container  1  is designed to be placed flat on a horizontal plane, the axis X of the container defines a vertical direction, with any plane that is orthogonal to the axis X being termed transverse and any direction perpendicular to the axis X being termed radial. 
     The shoulder  3  supplements the volume of the container  1  and forms an essentially conical junction between the body  2  and the neck  4 . The bottom  5  closes the body  2  transversely downward. 
     This container  1 , obtained by blow molding, or preferably by stretch blow molding from a parison (i.e., a preform or an intermediate container that has undergone a first blow molding that is not final) is designed in particular to be hot-filled, with the temperature of the filling liquid able to reach 95° C. or a temperature that can be higher than the glass transition temperature of the container  1 , all dependent upon its material (let us recall that the glass transition temperature of PET is approximately 80° C.). 
     According to a preferred embodiment illustrated in  FIGS. 1 and 2 , the body  2  is symmetrical in relation to a median plane P located essentially at mid-distance from the ends of the body  2 . In this embodiment, the body  2  has, in the area of the median plane P, a belt  6  where the body  2  is curved, i.e., its transverse dimensions are reduced. 
     The belt  6  divides the body  2  into an upper cross-section  7 , which extends between the belt  6  and the shoulder  3 , and a lower symmetrical cross-section  8  of the upper cross-section  7  in relation to the median plane P, and which extends between the belt  6  and the bottom  5 . 
     In its upper cross-section  7  as well as in its lower cross-section  8 , the body has four faces that extend approximately vertically from the shoulder  3  (or the bottom  5 ) to the belt  6 , namely:
         A first pair of lateral faces  9  that, in cross-section, are parallel to one another,   A second pair of lateral faces  10  that, in cross-section, are parallel to one another and perpendicular to the faces  9  of the first pair.       

     As shown in  FIG. 3 , in the cross-section in the vicinity of the shoulder (cutting plane III-III of  FIG. 1 ) as well as in the vicinity of the bottom (cutting plane III′-III′ of  FIG. 1 ), the faces  9  of the first pair are separated by a distance D, and the faces  10  of the second pair are separated by a distance D′ that is equal or approximately equal to the distance D between the faces  9  of the first pair, with the expression “equal or approximately equal” meaning that the separation between the distances D and D′ is, strictly speaking, less than 5%. 
     In other words: 
       D′≈D
 
     with: 
     
       
         
           
             0.95 
             &lt; 
             
               
                 D 
                 ′ 
               
               D 
             
             &lt; 
             1.05 
           
         
       
     
     The faces  9  of the first pair preferably have the same width, denoted L 2 . The faces  10  of the second pair also preferably have the same width, denoted L 2 . The widths L 1  and L 2  are advantageously equal or approximately equal (in the meaning indicated above): 
       L1≈L2
 
     with: 
     
       
         
           
             0.95 
             &lt; 
             
               
                 L 
                  
                 
                     
                 
                  
                 1 
               
               
                 L 
                  
                 
                     
                 
                  
                 2 
               
             
             &lt; 
             1.05 
           
         
       
     
     In the cross-section in the vicinity of the shoulder  3  as well as in the vicinity of the bottom  5 , the lateral faces  9 ,  10  are thus inscribed in a square (or almost square) contour of side D. Through improper use of language, a square is compared to a rectangle whose sides D, D′ are equal or approximately equal in the meaning indicated above, consequently allowing a variation of 5%. 
     By contrast, in the cross-section in a median zone of the body  2  (in this case in the vicinity of the belt  6 ), the faces  9  of the first pair are separated by a distance D 1 , while the faces  10  of the second pair are separated by a distance D 2  that is different from D 1 , with the term “different” meaning that the separation between D 1  and D 2  is greater than or equal to 5%. 
     Since the container  1  can allow symmetry of rotation of one-quarter turn around its main axis X, it is arbitrarily possible to declare that D 2  is, strictly speaking, greater than D 1 : 
       D2&gt;D1 
     in the sense that: 
     
       
         
           
             
               
                 D 
                  
                 
                     
                 
                  
                 1 
               
               
                 D 
                  
                 
                     
                 
                  
                 2 
               
             
             ≤ 
             0.95 
           
         
       
     
     The ratio between D 1  and D 2  does not, however, exceed 15%. In this case, the distances D and D 2  are in a ratio such that: 
     
       
         
           
             0.85 
             &lt; 
             
               
                 D 
                  
                 
                     
                 
                  
                 1 
               
               
                 D 
                  
                 
                     
                 
                  
                 2 
               
             
             &lt; 
             0.95 
           
         
       
     
     In the illustrated example, this ratio is approximately 0.93: 
     
       
         
           
             
               
                 D 
                  
                 
                     
                 
                  
                 1 
               
               
                 D 
                  
                 
                     
                 
                  
                 2 
               
             
             ≅ 
             0.93 
           
         
       
     
     In other words, in the cross-section in the above-mentioned median zone, the faces  9 ,  10  are inscribed in a rectangular contour whose sides have D 1  and D 2  for respective lengths, with the term “rectangle” meaning, in contrast to the square defined above, that the ratio between its sides is greater than or equal to 5%. 
     In the cross-section in this same median zone, the faces  9  of the first pair advantageously have the same length L 1 ′. Likewise, the faces  10  of the second pair advantageously have the same length L 2 ′. 
     At least one of the distances D 1  and D 2  is preferably less than the distance D; advantageously, the distances D 1  and D 2  are both less than the distance D, in such a way that, as illustrated in  FIG. 4 , the rectangle in which the body  2  is inscribed in the cross-section in the vicinity of the neck  4  as well as in the vicinity of the bottom  5  is, strictly speaking, included in the square in which the body  2  is inscribed in the cross-section in the vicinity of the neck  4  as well as in the vicinity of the bottom  5  (in dotted lines in  FIG. 3 ). 
     As  FIGS. 1 and 2  clearly show, the distances between the faces  9 ,  10 , parallel two by two, vary continuously along the axis X of the body  2 , respectively from the value D (that can be considered to be maximum when the plane of the cross-section being considered is also as close as possible to the upper end, or, conversely, lower than the body  2 ) to the value D 1 , and from the value D to the value D 2 . 
     In other words, the width of the body  2 , measured transversely, gradually—and not abruptly—decreases from the ends of the body  2  to its median zone. 
     According to a preferred embodiment, the body  2  also comprises beveled facets  11  connecting the faces  9 ,  10 . 
     As  FIG. 3  shows, in the cross-section in the vicinity of the shoulder (in the plane III-III) as well as in the vicinity of the bottom (in the plane III′-III′), the facets  11  preferably form an angle A of approximately 450 with the faces  9 ,  10 . 
     By contrast, this angle is not constant along the axis X of the container  1 . Actually, in the cross-section in said median zone of the body  2 , the facets  11  form a first angle A 1  that is, strictly speaking, less than 45° with the faces  9  of the first pair, while conversely, the facets  11  form an angle A 2  that is, strictly speaking, greater than 45°, complementary with the angle A 1 , with the faces  10  of the second pair: 
       A1+A2=90°
 
     According to a particular preferred embodiment, the angle A 1  is between approximately 37° (in which case the angle A 2  is approximately 530) and approximately 43° (in which case the angle A 2  is approximately 470). Preferably, the angle A 1  is approximately 400 (with the angle A 2  then being approximately 500). 
     As  FIGS. 3 and 4  clearly show, the facets  11  provide to the body  2  an essentially octagonal cross-section. It is possible, however, through improper use of language, to describe this cross-section as square, taking into account the considerably smaller widths of the facets  11  over those of the faces  9 ,  10 . 
     The change of an essentially square cross-section (in the vicinity of the ends of the body  2 ) to an essentially rectangular cross-section (in a median zone of the body  2 ) prevents the body  2  from deforming into a diamond shape when the latter is subjected to internal depressurization. 
     Actually, the rectangular cross-section of the body  2  in the median zone tends, under the action of depressurization in the container  1 , to become flattened also by decreasing the distance D 1  and jointly increasing the distance D 2 , with no significant alteration of the perpendicularity of the faces  9  to the faces  10 . The thus deformed cross-section of the body  2  was illustrated in broken lines in  FIG. 4 . 
     This controlled deformation is promoted by the facets  11 , whose angle A 1  tends to be closed while in contrast, the angle A 2  tends to be open, as illustrated by the broken lines of  FIG. 4 . 
     This controlled deformation makes it possible to maintain the rigidity of the container  1 , in particular during its handling, and also to preserve its appearance, with the flattening of the body  2  in the median zone remaining imperceptible to the consumer. 
     As can be seen in  FIGS. 1 and 2 , deformable panels  12  can be included in the faces  9 ,  10  in such a way as to absorb a portion of the deformations due to pressure variations within the container  1 . 
     In addition, stiffeners  13  can also be provided, in particular on the facets  11  for limiting the deformations of the latter and thus for promoting the controlled deformation of the rectangular cross-section of the body  2  in the median zone, as disclosed above.