Method for thermoforming a plastic container with a complex bottom

Abstract

The thermoforming method according to the present invention makes it possible to produce a plastic container with a complex bottom. This method provides, in particular, for : - moving a movable female assembly ( 113 ) and / or a male assembly ( 12 ) towards each other until a portion of a preheated plastic sheet ( 9) is pinched and plastically deformed by compression to form the bottom of the container; - while said portion of the sheet ( 9) is pinched and kept pinched, jointly moving the movable female assembly ( 113 ) and the male assembly ( 12 ) to plastically deform by stretching the peripheral portion of the sheet ( 9) to form the side wall of the container. This method therefore includes an initial coining step by compression of the bottom wall of the container, in order to create articulated and complex geometries on said wall.

Description

DESCRIPTION"METHOD FOR THERMOFORMING A PLASTIC CONTAINER WITH A COMPLEX BOTTOM"

[0001] The present invention relates to a method for manufacturing a plastic container, for example for beverages or liquid foods .

[0002] Plastic containers are known to have walls with sufficient strength and rigidity to maintain the desired shape . One of the traditional methods for manufacturing such types of containers is thermoforming, under vacuum and / or pressure . In the case of vacuum thermoforming, a preheated sheet of plastic material lies on the mold by suction (vacuum) , reproducing all the shapes of the mold itself ; in the case of pressure thermoforming, instead, the sheet is pushed against the mold by a high pressure exerted from the outside by air, which also facilitates its cooling .

[0003] Thermoforming is a widely used method for manufacturing plastic containers because it is flexible in terms of mold change and related setup, and the cost of the equipment is lower compared to, for example, the injection molding method . Furthermore, this method allows the molding of very thin wall thicknesses . An example of a plastic container for carbonated beverages made by thermoforming is shown in document EP 0 079 682 Bl . Anexample of a capsule for the instantaneous preparation of beverages ( such as tea, coffee, herbal teas ) obtained by thermoforming is shown in document IT 2022 0002 2002 Al . Another example of automatic production of plastic containers for packaging is shown in document FR 2 766 754 Bl . In Figures 1 to 4 , the various stages of the thermoforming production of the container are shown . With reference to Figure 2 , the punch 215 and the central piston 117 begin to stretch the plastic portion 10a intended to form the bottom of the container, until a peripheral edge 119 of the bottom is pinched between the punch 215 and the mold 115 . In the subsequent step, shown in Figure 3 , the punch 215 and the mold bottom 115 stretch the plastic portion 10b intended to form the vertical walls of the container . As shown in Figure 4 , the punch 215 and the central piston 117 retract simultaneously with the introduction of pressurized air to stretch the plastic portion 10a, which adapts to the cooled walls of the mold 100 and the mold bottom 115 to form the bottom of the container . Therefore, in the method described in document FR 2 766 754 Bl , the bottom of the container is obtained by stretching .

[0004] However, thermoforming still has a number of disadvantages : it does not allow extreme precision in the dimensional tolerances of the object to be molded,compared with the tighter tolerances achievable with the injection molding technique ; there is also the risk of non-uniform and inconsistent stretching of the plastic over the shapes of the mold, particularly in the case of very small thicknesses .

[0005] As anticipated above, the obj ect of the present invention is a new method for manufacturing a plastic container, for example for the food, pharmaceutical, or cosmetic sectors . For explanatory purposes , in the following description reference will be made to a plastic container for beverages , and in particular to a cup for a capsule for packaging concentrated products ( for example in the form of powder or granules , insoluble or soluble ) , in predetermined single-use doses , for the instantaneous preparation of beverages ( such as tea, coffee, herbal teas , milk, chocolate, etc . ) by introducing, inside the capsule itself , a pressurized fluid (mainly hot water) . Beverage capsules contain a single prepackaged dose of the substance to be extracted, enclosed within a container called "cup" , closed by a lid . There are different types of automatic or semi-automatic machines for beverage preparation . The common operating principle of such machines involves perforating the capsule lid and injecting into the cup the pressurized fluid through which the beverage is obtained (by infusion / extract ion ofthe insoluble powder or by dissolving the soluble powder) . In such automatic machines , the dispensing of the beverage takes place without perforation of the bottom of the cup, which is in fact provided with an outlet duct , called a nozzle . This type of capsule is in fact equipped with internal opening means ( for example by perforation, tearing or detachment of an internal sealing disc) that are activated when a certain pressure level inside the cup is reached .

[0006] The thermoforming technology, while having undeniable advantages in terms of production simplicity, presents some drawbacks related to the difficulty of creating articulated and complex geometries . The known cups made by thermoforming, in fact , when intended for capsules with their own opening means , are very simple cup-shaped structures with a flat bottom, and require the use of internal inserts , made by injection molding, on which the means functional to the correct dispensing of the beverage are arranged . This solution involves production and assembly complexities , which considerably increase production costs .

[0007] The purpose of the present invention is to provide a method for manufacturing a plastic container, for example a cup for producing beverage capsules , which solves the problems of the prior art while taking into account theneeds of the field .

[0008] This purpose is achieved by a thermoforming manufacturing method which provides an initial stage of coining by compression of the bottom wall of the container, in order to create articulated and complex geometries on said wall . In the case of a cup-shaped container for a beverage capsule, this method makes it possible to equip the container with all the functional means necessary for the correct dispensing of the beverage, without the need for any internal insert .

[0009] This purpose is achieved by a method for manufacturing a plastic container according to claim 1 , as well as by a plastic container obtained by this method and by a thermoforming apparatus for performing this method . The dependent claims describe preferred embodiments of the invention .

[0010] The features and advantages of the manufacturing method according to the present invention will be evident from the description given below, provided by way of example and not limitation, in accordance with the attached figures , in which :

[0011] - Figure 1 shows a sectional view of a thermoforming apparatus for a plastic container ( in this specific case, a cup for a capsule for beverage preparation) for carrying out the manufacturing method according to thepresent invention;

[0012] - Figure 2 shows the first stage of the manuf cturing method according to the present invention, and in particular the initial coining stage by compression of the bottom wall of the container ;

[0013] - Figure 3 shows the second stage of the manufacturing method according to the present invention, and in particular the subsequent stage of stretching guided by a mandrel, and thus the actual thermoforming stage ;

[0014] - Figure 4 shows a sectional view of a plastic container ( in this specific case, a cup for a capsule for beverage preparation) obtained with the manufacturing method according to the present invention .

[0015] With reference to the attached figures , reference numeral 1 denotes , as a whole, a thermoforming apparatus for carrying out the manufacturing method according to the present invention .

[0016] Figure 4 instead shows an example of a container 2 produced by the manufacturing method according to the present invention .

[0017] The container 2 is provided with a body that is a single piece ( for example in the form of a glass , cup, or tray) . The body of the container 2 may have single-layer or multi-layer walls (that is , two or more layers ) ,depending on the starting plastic sheet 9 .

[0018] The container 2 is provided, at its upper end, with an opening 23 for access to an internal cavity 22 suitable for receiving a product .

[0019] The container 2 has , at its upper end, a coupling rim 21 configured to receive a closing element , such as a lid, for example . The rim may be a protrusion (or similar, such as a projection or a flange ) or a recess (or similar, such as a cavity or groove ) . The rim is a structure configured to engage a closing element and to hold it in the desired position . The rim 21 may extend around one or more portions of the container, or may extend along the entire periphery or circumference of the container 2 . The rim 21 may have a flat , curved, V- shaped, U-shaped or any other cross-sectional profile . In the example of Figure 4 , the rim 21 is a flat , annular, continuous protrusion extending along the entire circumference of the container 2 . In one embodiment , the rim 21 defines , on a side 212 opposite a coupling side 211 intended to receive the closing element , an integrated sealing ring .

[0020] The term "closing element" may include, without limitation, a cap, a lid, a film or sheet , multi-piece closures , snap closures and / or similar elements ; the closing element may be pierceable, tearable, orremovable .

[0021] The container 2 has , below the rim 21 , a side wall 24 , for example annular or tapered, ending in a transverse bottom 25 .

[0022] The bottom 25 is provided, internally and / or externally, with a plurality of ridges , radial and / or circumferential .

[0023] As shown in the section of Figure 4 , the bottom 25 of the container is defined by a lower wall 8 that substantially has the same thickness throughout the bottom 25 and is characterized by an alternation of ridges and recesses .

[0024] Preferably, but not exclusively, the lower wall 8 of the bottom 25 defining an internal ridge is the same lower wall 8 of the bottom 25 defining an external recess . In this example, the internal ridges of the bottom 25 are hollow inside, so that at each internal ridge there is a corresponding external recess . Each internal ridge of the bottom 25 therefore corresponds to a respective external recess . And vice versa : each external ridge of the bottom 25 corresponds to a respective internal recess . The geometry of an internal ridge substantially corresponds to the geometry of the respective external recess .

[0025] The thickness of the side wall 24 of the container 2is smaller than the thickness of the lower wall 8 of the bottom 25 . The thickness of the side wall 24 is also smaller than the thickness of the upper wall forming the rim 21 .

[0026] Figure 1 shows a thermoforming apparatus 1 according to the present invention, for producing a polymeric container 2 as described above .

[0027] The thermoforming apparatus 1 is provided with a mold assembly 10 intended to define the shape of the container 2 . The mold assembly 10 comprises a female assembly 11 with internal surfaces ( called lower femalecontact surface 133 and female side surface 134 ) defining the external geometry of the container, and a male assembly 12 with external surfaces ( called male side surface 124 and lower male-contact surface 123 ) . Only the lower surface of the male assembly ( called lower malecontact surface 123 ) defines the geometry of an internal part of the container 2 , and in particular of the bottom 25 .

[0028] The female assembly 11 defines within it a cavity 110 . The cavity 110 has , in section, a generally cylindrical or f rustoconical shape . Since the sheet or plate of polymeric material will be formed along the surfaces of the cavity 110 , and therefore will take on the shape of the cavity 110 , Figures 1-3 show a cavityfor thermoforming a cup-shaped object . However the cavity 110 may have different shapes and / or dimensions , for example a square, rectangular, polygonal, elliptical, oval, or any other suitable cross-section .

[0029] Preferably, to provide the elasticity required for thermoforming, the sheet 9 of polymeric material is heated or otherwise softened before, during, and / or after being placed in the starting position of Figure 1 , that is , stretched between the female assembly 11 and the male assembly 12 . Preferably, the sheet 9 is heated on both sides , preferably by means of hot air .

[0030] The female assembly 11 is formed by a fixed female assembly 112 arranged around a movable female assembly 113 , the latter being capable of vertically translating ( raising and lowering) with respect to the fixed female assembly 112 .

[0031] The fixed female assembly 112 defines the lateral portion and possibly also a peripheral portion of the bottom of the cavity 110 ; the fixed female assembly 112 thus forms the side wall 24 of the container 2 and possibly also a peripheral portion of the bottom 25 of the container 2 . The fixed female assembly 112 is a substantially annular body .

[0032] The movable female assembly 113 defines the bottom or only a central portion of the bottom of the cavity110 ; the movable female assembly 113 thus forms the bottom or only the central portion of the bottom 25 of the container 2 . The movable female assembly 113 is substantially a punch .

[0033] The cavity 110 of the female assembly 11 is defined by a female side surface 134 , determined by the fixed female assembly 112 , and by a lower female-contact surface 133 , determined by the movable female assembly 113 . The sheet 9 will come into contact with the entire surface of the cavity 110 : with the lower female-contact surface 133 as it is pinched in an initial coining step (Figure 2 ) , and with the female side surface 134 as it is pushed by the air flow in a subsequent thermoforming step (Figure 3 ) .

[0034] The female assembly 11 may comprise at least one fluid channel 121 for performing thermoforming under vacuum or pressure, in which the sheet 9 lies against the surfaces of the cavity 110 by suction or by air pressure . Preferably, the fluid channel 121 of the female assembly 11 is a suction channel . The fluid channels 121 are arranged at the female side surface 134 of the cavity 110 . No fluid channel 121 is present at the lower femalecontact surface 133 of the movable female assembly 113 . For example, in Figure 1 , the female assembly 11 is provided with four fluid channels 121 arranged at thefixed female assembly 112 .

[0035] Preferably, the fluid channel 121 of the female assembly 11 is located at a step recess of the cavity 110 . This solution allows proper adhesion of the sheet 9 at the surface forming the step .

[0036] Through a fluid network, the fluid channels 121 are in communication with a supply system . The fluid network may include, without limitation, a plurality of tubes , piping, conduits , other transport lines , valves , fluid distribution and cut-off devices , joints , fittings , inlets , outlets , channels and the like . The supply system comprises a device for suction or compression of fluids , configured to draw in or push air . The suction devices may comprise, for example, a diaphragm pump, a volumetric pump and / or any other mechanical, electrical or pneumatic device . The pres sure devices may comprise, for example, an air compressor or a similar device capable of imparting a positive pressure to a fluid .

[0037] The male assembly 12 comprises a mandrel 122 configured to apply to the sheet 9 a force in the direction of the cavity 110 of the female assembly 11 , in order to perform an assisted stretching of the sheet itself . The male assembly 12 is provided with a male side surface 124 , which will not come into contact with the sheet 9, and a lower male-contact surface 123 , which willcome into contact with the sheet 9 .

[0038] The male assembly 12 may also comprise at least one fluid channel 121 as described above, in order to inject pressurized air to push the sheet 9 against the walls of the cavity 110 , and in particular against the female side surface 134 of the cavity 110 . Preferably, the fluid channel 121 of the male assembly 12 is a thrust channel . In this case, the fluid channel 121 is arranged at the male side surface 124 .

[0039] In known thermoforming apparatuses , the lower surface of the mandrel is smooth and rounded to avoid tears , perforations and / or damage to the polymeric material sheet with which it comes into contact during the assisted stretching step .

[0040] In the thermoforming apparatus 1 according to the present invention, on the other hand, the mandrel 122 of the male assembly 12 is provided with a shaped lower male-contact surface 123 intended to come into contact with the sheet 9 to define its final shape . The movable female assembly 113 is also provided with a shaped lower female-contact surface 133 intended to come into contact with the sheet 9 to define its final shape . As shown in Figure 2 , the lower male-contact surface 123 of the mandrel 122 and the lower female-contact surface 133 of the movable female assembly 113 respectively act as anupper clamping element and a lower clamping element that apply a pinching force to the sheet 9 throughout the thermoforming process , so as to plastically deform it by compression and define its final geometry . This step is comparable to a coining or compression molding process , in which the shaped surfaces of the mandrel 122 and the movable female assembly 113 act as mold surfaces that shape the sheet 9, defining its final geometry .

[0041] Preferably, both the mandrel 122 and the movable female assembly 113 translate towards each other to clamp the sheet 9 . In this example, the mandrel 122 translates downward and the movable female assembly 113 translates upward .

[0042] In the clamping step of the sheet 9, a coining of the bottom 25 of the container 2 takes place, that is , its final shape is defined . The coining step of the bottom 25 (Figure 2 ) occurs before the stretching of the sheet 9 (Figure 3 ) , that is , before the actual thermoforming process . In fact , the thickness of the side wall 24 of the container 2 is smaller than the thickness of the lower wall 8 of the bottom 25 .

[0043] In a further embodiment , the coining step of the bottom 25 occurs after a partial pre-stretching step of the sheet 9 . In this example, the mandrel 122 moves downward until it meets the sheet 9 and exerts a downwardforce that begins to partially stretch the sheet 9 ; only at this point does the movable female assembly 113 move upward until it meets the sheet 9 and, together with the mandrel 122 , performs the clamping of the sheet 9 so as to plastically deform it by compression .

[0044] Once the sheet 9 is clamped between the mandrel 122 and the movable female assembly 113 , both are translated ( lowered) inside the cavity 110 defined by the fixed female assembly 112 , drawing the sheet 9 downward and stretching it . At the same time, air is drawn through the fluid channels 121 to perform thermoforming of the sheet 9 to obtain the side wall 24 of the container 2 . A vacuum (or pressure ) thermoforming with mandrel-assisted stretching is thus performed . The pressurized air between the male side surface 124 and the sheet 9 pushes the sheet 9 itself toward and against the female side surface 134 of the cavity 110 , thereby carrying out the thermoforming .

[0045] Finally, the separation of the thermoformed container 2 from the sheet 9 takes place, for example, by means of shaped dies (not shown) .

[0046] In summary, the manufacturing method for thermoforming a plastic container provided with a side wall and a bottom according to the present invention comprises the steps of :

[0047] - arranging a mold assembly 10 provided with a female assembly 11 having a cavity 110 , and a male assembly 12 ; the female assembly 11 is formed by a fixed female assembly 112 and a movable female assembly 113 vertically translatable ;

[0048] - arranging a sheet 9 of plastic material, preferably preheated, stretched between the female assembly 11 and the male assembly 12 , above the cavity 110 ;

[0049] - moving the movable female assembly 113 and / or the male assembly 12 towards each other until a portion of the sheet 9 is pinched between a lower male-contact surface 123 of the male assembly 12 and a lower femalecontact surface 133 of the movable female assembly 113 , plastically deforming by compression said portion of the sheet 9 to form the bottom of the container;

[0050] - while said portion of the sheet 9 is pinched and kept pinched, thermoforming a peripheral portion of the sheet 9 ; the thermoforming step includes jointly moving the movable female assembly 113 and the male assembly 12 towards and into the cavity 110 , and applying a suction and / or a fluid thrust through at least one fluid channel ( 121 ) of the female assembly ( 11 ) and / or of the male assembly ( 12 ) , plastically deforming by stretching said peripheral portion of the sheet 9 to form the side wallof the container;

[0051] - separating the container from the sheet 9 .

[0052] In summary, the thermoforming apparatus 1 according to the present invention, for producing a plastic container provided with a side wall and a bottom according to the above-described method, is provided with :

[0053] - a female assembly 11 defining a cavity 110 with a lower female-contact surface 133 and a female side surface 134 ; the female assembly 11 is formed by a fixed female assembly 112 arranged around a movable female assembly 113 ; the fixed female assembly 112 having the female side surface ( 134 ) ; the movable female assembly ( 113 ) being vertically translatable and having the lower female-contact surface ( 133 ) ;

[0054] - a vertically translatable male assembly ( 12 ) having a lower male-contact surface ( 123 ) and a male side surface ( 124 ) ;

[0055] - wherein the female assembly 11 and / or the male assembly 12 is provided with at least one fluid channel 121 ;

[0056] - wherein the female side surface 134 of the fixed female assembly 112 defines the side wall of the container by thermoforming; and

[0057] - the lower male-contact surface 123 of the male assembly 12 and the lower female-contact surface 133 of the movable female assembly 113 together define the bottom of the container by molding .

[0058] In particular, therefore, the movable female assembly 113 and / or the male assembly 12 are movable towards each other to perform a coining or compression molding process between the shaped lower female-contact surface 133 and the shaped lower male-contact surface 123 .

[0059] In summary, the thermoformed plastic container 2 according to the present invention, obtained with the manufacturing method described above, is a single-piece body and comprises :

[0060] - an upper rim 21 defining an opening 23 for access to an internal cavity 22 ;

[0061] - a side wall 24 extending from and below said rim 21 ;

[0062] - a lower wall 8 extending transversely from and below said side wall 24 ; said lower wall 8 defining a bottom 25 provided, internally and / or externally, with at least one ridge ; the side wall 24 having a thickness smaller than a thickness of the lower wall 8 of the bottom 25 .

[0063] By way of example, the geometry of a cup-shapedcontainer for a capsule for beverage preparation will now be described . The cup defines an internal volume V for containing at least one food substance, soluble or insoluble, typically in powder or granular form . The cup is a single-piece body, substantially f rustoconical in shape . The cup is provided, on one side, with a bottom 25 and, on the opposite side, with an inlet opening 23 defined by an outwardly projecting rim 21 . When used to form a capsule for beverage preparation, the inlet opening 23 is closed by a lid hermetically fixed to the rim 21 . The cup is externally provided, at the bottom 25 , with an outlet opening suitable for allowing the outflow of the infused beverage; it should be noted that this opening is obtained by shearing in a subsequent stage following thermoforming . Preferably, the outlet opening is defined by a nozzle . Preferably, the bottom 25 is concave and defines a "funnel-shaped" structure . The bottom 25 is internally provided with a plurality of internal ridges , some radial 320 and some circumferential 310 , vertically projecting toward the inside of the cup . The bottom 25 of the cup is also provided with a plurality of external ridges , radial and / or circumferential . The cup is produced by the manufacturing method described above, at the end of which a single body is obtained, without interruptions or openings in thebottom 25 . A subsequent shearing (or cutting or perforating) step is then performed on a central portion of the bottom 25 in order to create at least one outlet opening for the beverage flow .

[0064] The thickness of the side wall 24 of the cup is smaller than the thickness of the wall forming the bottom 25 . Preferably, the thickness of the side wall 24 of the cup is between 0 . 10 mm and 0 . 34 mm . Preferably, the thickness of the wall forming the bottom 25 is between 0 . 35 and 0 . 65 . The above thicknesses refer to a cup obtained from a starting sheet 9 having a thickness between 0 . 60 and 0 . 80 mm .

[0065] The cup can be used to produce a capsule for the preparation of an infused or soluble beverage . The capsule comprises a lid fixed, by gluing or welding, at the upper rim, to hermetically seal the cup at the top . The capsule is internally provided with a sealing disc, fixed inside the bottom 25 and configured to hermetically seal the cup at the bottom . The disc is positioned below the food substance and above the bottom 25 . In one embodiment , the disc is fixed in such a way that it detaches , that is , becomes unstuck, as a result of the increase in temperature and pressure inside the capsule . In another embodiment, the disc is permanently fixed to the bottom 25 and is provided with weakened portionssuch as cuts or incisions , which cause it to tear as a result of the increase in pressure inside the capsule . The capsule can be produced in dif ferent versions , for example for the preparation of infusion beverages ( such as coffee ) or soluble beverages . The capsule can be used for packaging concentrated products ( in the form of powder, granules or leaves ) in predetermined single-use doses , for the instantaneous preparation of beverages such as leaf or soluble tea, powdered or instant coffee, herbal teas , milk, chocolate , or other dehydrated and soluble products .

[0066] As mentioned above, the manufacturing method according to the present invention makes it possible to obtain a generic plastic container, and reference has been made specifically to a cup for capsules only for explanatory purposes .

[0067] Innovatively, the thermoforming manufacturing method according to the present invention provides an initial coining step by compression in order to obtain the bottom wall of the container, and subsequently a mandrel- assisted thermoforming step in order to obtain the side wall of the container .

[0068] Advantageously, the thermoforming manufacturing method according to the present invention makes it possible to obtain, in a single process , a containerprovided with a very thin side portion and a bottom having articulated and complex geometries . In the case of a cup-shaped container for a beverage capsule, this method makes it possible to obtain a light container which at the same time is provided with all the functional means necessary for the correct dispensing of the beverage, without the need for any internal insert .

[0069] Advantageously, the thermoforming manufacturing method according to the present invention makes it possible to obtain a very light container, with significant savings in terms of the raw material used, but at the same time provided with complex geometries that cannot be achieved with traditional thermoforming methods .

[0070] It is clear that a person skilled in the art may make modifications to the method, the container and the thermoforming apparatus described above, all of which fall within the scope of protection as defined by the following claims .

Claims

CLAIMS1. A method of manufacturing by thermoforming a plastic container provided with a side wall and a bottom, comprising the steps of:- arranging a mold assembly (10) provided with a female assembly (11) having a cavity (110) , and a male assembly (12) ; wherein the female assembly (11) is formed by a fixed female assembly (112) and a movable female assembly (113) vertically translatable;- arranging a sheet (9) of plastic material, preferably preheated, stretched between the female assembly (11) and the male assembly (12) , above the cavity (110) ;- moving the movable female assembly (113) and / or the male assembly (12) towards each other until a portion of the sheet (9) is pinched between a lower male-contact surface (123) of the male assembly (12) and a lower female-contact surface (133) of the movable female assembly (113) , plastically deforming by compression said portion of the sheet (9) to form the bottom of the container;- while said portion of the sheet (9) is pinched and keeping it pinched, thermoforming a peripheral portion of the sheet (9) ; wherein the thermoforming step includes jointly moving the movable female assembly (113) and the male assembly (12) towards and into the cavity (110) , andapplying a suction and / or a fluid thrust by means of at least a fluid channel (121) of the female assembly (11) and / or male assembly (12) , plastically deforming by stretching said peripheral portion of the sheet (9) to form the side wall of the container;- separating the container from the sheet (9) .

2. Manufacturing method according to claim 1, wherein the lower male-contact surface (123) of the male assembly (12) and the lower female-contact surface (133) of the movable female assembly (113) define at least a ridge on the bottom of the container.

3. Manufacturing method according to claim 2, wherein a respective outer recess corresponds to each inner ridge of the bottom and / or a respective outer ridge corresponds to each inner recess of the bottom. . Manufacturing method according to any one of the preceding claims, wherein the cavity (110) of the female assembly (11) is defined by the female side surface (134) of the fixed female assembly (112) and by the lower female-contact surface (133) of the movable female assembly (113) , and wherein the sheet (9) first comes into contact with the lower female-contact surface (133) during the step of plastic deformation by compression of the bottom of the container, and then with the female side surface (134) during the step of plastic deformationby stretching of the side wall of the container.

5. Manufacturing method according to any one of the preceding claims, wherein- the fluid channel (121) of the female assembly (11) is a suction channel and is arranged at the female side surface (134) , and / or- wherein the fluid channel (121) of the male assembly (12) is a thrust channel and is arranged at the male side surface (124) .

6. Manufacturing method according to any one of the preceding claims, wherein the pressurized air between the male side surface (124) and the sheet (9) pushes the sheet (9) towards and against the female side surface (134) of the cavity (110) .

7. Manufacturing method according to any one of the preceding claims, wherein the fixed female assembly (112) is an annular body and the movable female assembly (113) is a punch arranged below the fixed female assembly (112) to close the cavity (110) of the female assembly (11) at the bottom.

8. A thermoforming apparatus (1) for making a plastic container provided with a side wall and a bottom, said thermoforming apparatus (1) being provided with:- a female assembly (11) defining a cavity (110) having a lower female-contact surface (133) and a female sidesurface (134) ; wherein said female assembly (11) is formed by a fixed female assembly (112) arranged around a movable female assembly (113) ; said fixed female assembly (112) having the female side surface (134) ; said movable female assembly (113) being vertically translatable and having the lower female-contact surface (133) ;- a vertically translatable male assembly (12) having a lower male-contact surface (123) and a male side surface (124) ;- wherein said female assembly (11) and / or said male assembly (12) is provided with at least a fluid channel (121) ; said thermoforming apparatus (1) being characterized in that :- the female side surface (134) of the fixed female assembly (112) defines the side wall of the container by thermoforming; and- the lower male-contact surface (123) of the male assembly (12) and the lower female-contact surface (133) of the movable female assembly (113) define together the bottom of the container by molding.

9. Thermoforming apparatus (1) according to claim 8, wherein- the fluid channel (121) of the female assembly (11) is a suction channel and is arranged at the female sidesurface (134) ; and / or- the fluid channel (121) of the male assembly (12) is a thrust channel and is arranged at the male side surface (124) .

10. A thermoformed plastic container (2) , in a single piece, obtained by the manufacturing method according to one of claims 1 to 7, comprising:- an upper edge (21) , defining an opening (23) for accessing an inner cavity (22) ;- a side wall (24) extending from and below said edge (21) ;- a lower wall (8) extending transversely from and below said side wall (24) ; said lower wall (8) defining a bottom (25) provided, internally and / or externally, with at least a ridge; wherein the side wall (24) has a thickness less than a thickness of the lower wall (8) of the bottom (25) .

11. Plastic container (2) according to claim 10, wherein the thickness of the side wall (24) is less than a thickness of the edge (21) .

12. Plastic container (2) according to claim 10 or 11, wherein- the lower wall (8) of the bottom (25) defining an inner ridge is the same lower wall (8) of the bottom (25) defining an outer recess, and / or- wherein a respective outer recess corresponds to each inner ridge of the bottom (25) , and / or- wherein a respective outer ridge corresponds to each inner recess of the bottom (25) .

13. A cup for a capsule for preparing beverages, said cup being formed by a container according to claim 12, f rustoconical in shape; wherein the bottom (25) is provided with at least an outlet opening obtained by shearing following the thermoforming; and wherein the bottom (25) is internally provided with a plurality of ridges .

14. Cup according to claim 13, wherein the side wall (24) has a thickness between 0.10 mm and 0.34 mm, and the bottom (25) has a thickness between 0.35 and 0.65.

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