Method and machine for producing thermoformed objects made of thick paper

Abstract

The solution described herein provides a process for producing thermoformed 3D objects made of thick paper comprising the steps of feeding thick paper to a processing machine, die cutting the paper to form flat developments for the 3D object to be formed, spreading a covering material onto the paper or onto the flat developments, inserting the flat developments into a heated die, deep drawing the flat developments into the die using a punch and removing the thermoformed 3D object from the die. In some embodiments, the paper is fed in single sheets. In alternative embodiments, the paper is fed in coils. In the embodiments described herein, the paper used is a coated paper. The covering material (Q) is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of silicon-oxygen bonds, in which, depending on the exact composition of the starting sol, some silicon¬ oxygen bonds may be replaced by bonds between the silicon and other species. Preferably, the other species are alkyl groups. The die is heated to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C, in order to obtain the transformation of the covering material (Q) into a vitreous layer. In the deep-drawing step, a first forming step is provided in which a first punch has a generous gap with respect to the matrix creating the die to prevent the paper getting torn, and a second step of removing creases, in which a second punch has a small gap and compresses the object against the matrix for removing all the remaining creases in the paper.

Description

[0001] Title: “METHOD AND MACHINE FOR PRODUCING THERMOFORMED OBJECTS MADE OF THICK PAPER”

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of technologies for producing thermoformed objects made of thick paper.

[0004] In particular, the present invention concerns a process and machine for producing containers such as coffee pods, lids for cups, primary and secondary containers for cosmetics, containers for sauces, containers for fruit purees, cups and tubs, containers for secondary packaging, containers for non-food products, etc.

[0005] PRIOR ART

[0006] Nowadays coffee pods made of cellulose pulp are available on the market. This process is mainly broken down into three steps: pulping step; forming step; and drying step.

[0007] The pulping system first requires water and paper to be fed into the hydraulic pulper in a 3:1 ratio for 40-minute mixing. Then the pulp is automatically transported to the pulp feeding tank. The pulp pump transports the pulp to the beater for mixing and finally into the pulp feeding tank, which conveys the pulp to the forming machine.

[0008] The pulp forming machine sucks the pulp from the pulp pump to the die of the forming machine through the vacuum pump. The excess water is adsorbed at the discharge pump for storage. After the die of the forming machine has absorbed the pulp, the product is formed.

[0009] The drying system indicates that the water in the wet tray is to be evaporated by means of high temperature to create a product that can be used normally.

[0010] Products made with this technology have some limitations:

[0011] 1 ) It is necessary to insert a plastic or bioplastic film inside the product to ensure: a. A liquid barrier; b. A gas barrier; and c. Low resistance to high and low temperatures. 2) The products are extremely permeable and when they come into contact with liquid, especially if under pressure and hot, they release the products contained in the paper which alter the organoleptic characteristics of the drink being prepared.

[0012] 3) They cannot be colored.

[0013] SUMMARY OF THE INVENTION

[0014] The object of the invention was achieved by a process as defined in claim 1 and by a machine as defined in claim 10.

[0015] The technology described herein is able to overcome all the limitations of pulp technology and to guarantee, with a single product (paper) all the characteristics of resistance to hot and cold liquids, resistance to oils and greases, barrier to water vapor and oxygen, ability to withstand high and low temperatures.

[0016] The solution described herein provides a process for producing thermoformed 3D objects made of thick paper comprising the steps of feeding thick paper to a processing machine, die cutting the paper to form flat developments for the 3D object to be formed, spreading a covering material onto the paper or onto the flat developments, inserting the flat developments into a heated die, deep-drawing the flat developments into the die using a punch and removing the thermoformed 3D object from the die.

[0017] In some embodiments, the paper is fed in single sheets. In alternative embodiments, the paper is fed in coils.

[0018] In the embodiments described herein, the paper used is a coated paper.

[0019] In various embodiments, the covering material is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of siliconoxygen bonds, in which, depending on the exact composition of the starting sol, some silicon-oxygen bonds may be replaced by bonds between the silicon and other species.

[0020] In some embodiments, the other species are alkyl groups.

[0021] In more detail, the die is heated to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C, to obtain the transformation of the covering material into a vitreous layer. In some embodiments, in the deep-drawing step a first forming step is provided in which a first punch has generous gap with respect to the matrix creating the die to prevent the paper getting torn, and a second step of removing creases, in which a second punch has small gap and compresses the object against the matrix for removing all the remaining creases in the paper.

[0022] Preferably, the first punch is a movable punch formed by various parts that intervene at different times.

[0023] The solution also provides a machine for producing thermoformed 3D objects made of thick paper comprising the stations for feeding thick paper, die cutting the paper for forming flat developments for the 3D object to be formed, spreading a covering material onto the paper or onto the flat developments, forming the 3D object using a heated die, deep-drawing using a punch and a matrix, and removing the thermoformed 3D object from the die.

[0024] In some embodiments, the paper is fed in single sheets, in other alternative embodiments the paper is fed in coils.

[0025] Typically, the paper used with these machines is coated paper.

[0026] The covering material is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of silicon-oxygen bonds, in which, depending on the exact composition of the starting sol, some silicon-oxygen bonds may be replaced by bonds between the silicon and other species, in which the other species are preferably alkyl groups.

[0027] In some solutions, the spreading station of the covering material provides a coating roller.

[0028] Further, the die is heated by electric resistors to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C, to obtain the transformation of the covering material into a vitreous layer.

[0029] In some embodiments, in the deep drawing station a first forming step is provided in which a first punch has a generous gap with respect to the matrix creating the die to prevent the paper getting torn, and a second step of removing creases, in which a second punch has small gap and compresses the object against the matrix for removing all the remaining creases in the paper. Preferably, the first punch is a movable punch formed by various parts that intervene at different times.

[0030] The solution also comprises thermoformed 3D objects made of thick paper produced according to the process described and the 3D objects made of thick paper produced using the machine.

[0031] In particular, the die used is heated to allow the covering material to be polymerized and to fix the paper product also conferring mechanical strength and liquid and gas barrier properties thereto.

[0032] Further, the forming of the paper is largely facilitated by the fact that the paper is wet with covering material as the wet fibers can easily move to adapt to the shape of the die for producing the 3D object.

[0033] BRIEF DESCRIPTION OF THE FIGURES

[0034] Hereafter in this description, reference will be made to the drawings shown in the accompanying figures, in which:

[0035] Figure 1 shows an example of a machine for producing thermoformed objects made of thick paper fed in sheets,

[0036] Figure 2 shows an example of a machine for producing thermoformed objects made of thick paper fed in coils,

[0037] Figure 3 shows an example of a coffee pod and flat development to obtain such a coffee pod,

[0038] Figure 4 shows some details of the flat developments for producing thermoformed objects made of thick paper,

[0039] Figure 5 shows some details of an example of a machine for producing thermoformed objects made of thick paper,

[0040] Figure 6 shows some details of the punch for producing the coffee pod in Figure 3,

[0041] Figure 7 shows another type of semi-spherical coffee pod and the related flat development,

[0042] Figure 8 shows details of the die / punch assembly for producing the coffee pod in Figure 7,

[0043] Figure 9 shows an example of a container for fruit puree and the related flat development, Figure 10 shows details of the die / punch assembly for producing the container for fruit puree in Figure 9,

[0044] Figure 11 shows an example of a lid for takeaway cups, and

[0045] Figure 12 shows details of the die / punch assembly for producing the lid for takeaway cups in Figure 11 .

[0046] The parts according to the present description are represented in the drawings, where suitable, employing conventional symbols, showing only the specific details allowing the understanding of the embodiments of the present invention, so as not to highlight details which will be immediately apparent to the person skilled in the art, with reference to the description provided below.

[0047] DETAILED DESCRIPTION OF THE INVENTION

[0048] The solution of the present invention is now described with the aid of the drawings. The technology proposed herein allows thick paper objects to be made by deep- drawing where the ratio between the height and diameter is greater than 1 (e.g. a cup 12mm high with a 10mm base) of any shape, whether circular or polygonal.

[0049] As already indicated, some examples of application of this technology are provided herein below:

[0050] Coffee pods;

[0051] Lids for cups;

[0052] Primary and secondary containers for cosmetics;

[0053] Containers for sauces;

[0054] Containers for fruit puree;

[0055] Glasses and cups;

[0056] Containers for secondary packaging;

[0057] Containers for non-food products;

[0058] Etc.

[0059] The starting paper used for this technology may be either in sheets or coils; the different choice between sheets or coils depends largely on the grammage of the paper.

[0060] In fact, paper in coils can be made for grammages of 450g / m2at most. For grammages over 450g / m2the paper can only be made in sheets. Naturally, the choice of the type of paper in sheets or coils is mainly made also according to the shape of the object and productivity. Production in coils is quicker but the investments are much higher both for the machines and the dies.

[0061] The solution proposed herein provides a process and a machine for producing objects made of thick paper.

[0062] The solution described herein provides a process for producing thermoformed 3D objects made of thick paper comprising the steps of feeding thick paper to a processing machine, die cutting the paper to form flat developments for the 3D object to be formed, spreading a covering material onto the paper or onto the flat developments, inserting the flat developments into a heated die, deep-drawing the flat developments into the die using a punch and removing the thermoformed 3D object from the die.

[0063] In the embodiments described herein, the paper used is a coated paper or glossy paper.

[0064] Coated paper is a type of paper covered with a very thin, white or slightly colored, coating, which gives it a shiny and polished appearance.

[0065] Various materials including kaolin, calcium carbonate, bentonite and talc can be used in the composition of the additional coating.

[0066] The mineral fillers are bound by a latex or mixture of latexes and binders, according to the characteristics that the coating has to confer to the paper.

[0067] The main aim of coating is to improve the print quality of the paper, but the coating can also be used to confer resistance to oil and grease, or to improve the waterproofing properties of the paper substrate.

[0068] The paper can be covered by a coating on one side only (in which case it is known as single-coated) or on both sides (in which case it is known as double-coated).

[0069] The single-coating is used when the print is provided on one side of the paper only, as often happens when the paper is used in the flexible packaging of food products; double-coating is applied when the paper is to be printed on both sides, as happens in the case of glossy magazines or books.

[0070] Single- or double-coated paper is used to confer surface finishes and to substantially reduce the porosity of the paper.

[0071] It is used to improve the print quality or to promote coating applications. For this solution it is possible to use all types of paper, but coated paper and doublecoated paper are preferably used as they are capable of further highlighting the characteristics of the covering material used (and described in detail in the following description) such as resistance to water, oil and grease. In fact, with this type of coated or double-coated paper, the covering material remains on the surface unlike uncoated paper where the covering material penetrates into the fibers and loses efficacy.

[0072] The papers that have been tested and that have produced the best results are selected from papers with a grammage comprised between 180 and 1010g / m2.

[0073] For papers comprised between 180 e 350 g / m2, we can cite by way of example the following papers made by different manufacturers:

[0074] METSA BOARD: PRO FSB CUP with grammage 265 g / m2,

[0075] BURGO: SUN ICE 2SC with grammage 350g / m2, and IGGESUND: INVERCOTE GPX with grammage 210 g / m2.

[0076] For papers with grammage from 400 to 1010 g / m2below are some examples: IGGESUND: INVERCOTE DUO with grammage 700g / m2, and BURGO: SUN ICE TRIO with grammage 900g / m2.

[0077] The solution proposed herein for the machine if the paper is fed in sheets is now described.

[0078] The machine M for producing objects C made of thick paper from single sheets F is shown in Figure 1 .

[0079] A sheet F is fed in any known way and with any known method to a die cutting tool 10 that produces the single developments S or flat shapes of the pods C or containers to be produced. As shown in Figure 1 a, numerous developments S can be made from every sheet F. According to the size of the sheets F and the size of the containers C to be produced, a relevant study will be performed in order to reduce waste.

[0080] Starting from the die cut sheet F, the individual developments S are taken by a dedicated gripping hand 12 and positioned on a conveyor belt 14 to then be treated with a covering material Q (described in detail in the following - Qwarzo material) using a spreading roller 20. The covering material Q is fed to the spreading roller 20 using a tank 25. Preferably, the covering material Q is in liquid or viscous form, so as to be able to be applied with a spreading roller 20.

[0081] The spreading with the covering material Q can be carried out on one or both sides. Depending on the type of product, it is generally always carried out on both sides. Once the developments S have been picked up, the waste or scraps SF of the sheet F are collected and accumulated in an area 16 for subsequent waste sorting and for recycling the paper.

[0082] The treated flat developments S+Q, i.e. already covered in covering material Q, are then inserted into the die 30, heated with electric resistors to at least 150 °C, by a manipulator 40 with a relevant gripping hand 42.

[0083] Once the flat developments S have been positioned in the die 30, the single flat developments are deep-drawn using a punch 50 controlled by a press 55 so as to form the 3D product or container.

[0084] Each machine M may have a single die 30 and a single punch 50 or a plurality of dies 30i and a plurality of punches 50i so as to be able to increase the production speed of the containers C.

[0085] In the proposed solutions, the die is hot to allow the covering material Q to be polymerized and the paper product to be fixed, also conferring mechanical strength and liquid and gas barrier properties thereto.

[0086] The forming of the paper is largely facilitated by the fact that the paper is wet with covering material Q as the fibers can easily move to adapt to the shape of the object. A discharge manipulator 60 removes the formed 3D product or container and positions it on an outlet belt 70.

[0087] The solution proposed herein in the case where the paper is fed to the machine through a coil B is now described.

[0088] The machine M1 for producing thick paper objects C from a continuous sheet on a coil B is illustrated in Figure 2.

[0089] It is unrolled from the coil B by an unwinder 100 and treated with a covering material Q (described in more detail below - Qwarzo material) by a spreading roller 110. The treated paper is then inserted into the die 130 by a thrust feeder 120 and a pull feeder 140 placed at the end of the die. Once the paper fed by the coil B covered with covering material Q enters the die 130, it is die cut and then deep-drawn using a punch 150 so as to form the formed 3D product or container C.

[0090] Also in this case, the die 130 is heated with electric resistors to at least 150 °C, to allow the covering material Q to be polymerized and the paper product to be fixed, also conferring mechanical resistance and a liquid and gas barrier thereto.

[0091] A very important part of the present solution is the study of the flat development S of the die-cut product. In particular, according to the characteristics of the 3D container to be produced, the flat development S is designed so as to prevent defects, tears, creases or the like.

[0092] Therefore, the preliminary study of the flat development S from which the final product or container C will be obtained is fundamental in order to prevent creases and esthetic defects and guarantee the possibility to make complex shapes.

[0093] With reference to Figure 3, a development S is shown for producing a known coffee pod CC of the type illustrated in Figure 3a.

[0094] The development S is flower-shaped with four petals P starting from a central portion PC.

[0095] The lines R that can be seen on all four petals P of the development S are scores so that the paper can be folded where necessary. Therefore, it is essential to perform the folds R on the paper at the right points, in order to limit esthetic and functional defects thereof. The central portion PC is instead free from lines.

[0096] For making the 3D products, it is possible to start from already pre-printed coils B and / or sheets F in order to be able to produce the objects C with the external part printed or decorated as preferred.

[0097] With reference to Figure 4, a development is shown which refers to a hemisphere for face creams used in the cosmetic sector. Nowadays these containers are made of plastic. As highlighted, on the edges of the petals it is possible to have areas Z1 and Z2 of the die cut parts which are scored or have reduced thickness as shown in Figure 4b so as not to create uneven thicknesses when overlapped. This technique can be applied to all shapes in which a very high esthetic characteristic is required. In particular, the two areas Z1 and Z2 have a reduced thickness so that, when they are overlapped, they form the same thickness as the rest of the container or pod CC. With reference to Figure 5, a die is shown for making the coffee pods in Figure 3 in the case of using a machine with coil feeding. In this case, the die is produced in two fundamental parts:

[0098] - a first part A of cutting and scoring the paper; in this step, the paper is cut using a cutting punch 200, the scoring is carried out and the waste SF removed,

[0099] - a second part B of the die carries out the forming of the pod, its trimming and removal.

[0100] In the machines described above, the sheet and coil are fed by a drive system.

[0101] In Figure 5, the single sheet and the one unrolled from the coil advance from left to right to receive the necessary processing to create the final object.

[0102] The second part B of the die is the most complex part and consists of the punch 210 and a matrix 220.

[0103] Preferably the punch 210 is movable. The punch 210 is made of distinct sectors (as shown in Figure 6) to allow it to be opened while it descends into the matrix 220. The punch 210 starts with the central part 212 retracted (see Figure 6b), thus in a more recessed position with respect to the forming portion 214. In this case, the central part 212 is on a parallel and more rearward plane than the plane containing the forming portion 214. After processing (see Figure 6b) the punch 210 has the central part 212 aligned with the forming portion 214, i.e. on the same plane.

[0104] In some processes, the forming punch 210 can also be fixed without any movement, i.e. produced of a single piece or used in the condition shown in Figure 6b. It depends on the complexity of the product to be produced.

[0105] The forming punch 210 has a much larger gap than the thickness of the paper to allow the paper to be folded without tearing. This means the dimensions of the forming punch 210 are smaller than the dimensions of the product to be made (typically a smaller diameter).

[0106] Again, with reference to Figure 5, the matrix 220 is a rotary matrix with four or more cavities to enable different steps to be carried out simultaneously on different developments S.

[0107] For example, considering the rotary matrix 220 shown in Figure 5 comprising four dies SM1 , SM2, SM3, and SM4 and four processing positions 1 , 2, 3, 4 there are the following steps: STEP 0- initialization) initially, the four dies SM1 , SM2, SM3, and SM4 are in the corresponding four processing positions 1 , 2, 3, 4, all empty;

[0108] STEP 1 - forming) a first development S1 is inserted into the first die SM1 which is in the first forming position 1 for forming the pod or container C1 , in collaboration with the movable or fixed punch 210,

[0109] STEP 2 - compression for removing creases) when the rotary matrix 220 rotates by one step the first development S1 contained in the die SM1 is brought into the second position 2 and a second development S2 is inserted into the fourth empty die SM4 which is in the first forming position 1 for forming the pod or container C2; the first development S1 housed in the first die SM1 which is now in the second position 2 is processed with a punch 230 with zero gap, moved by a cam which compresses the formed pod C1 and removes any creases in the paper. While the punch 230 with zero gap is being processed, a cutting element 232 also trims the edge of the pod C1 that was formed in step 1 of processing the first development S1 ,

[0110] STEP 3 - removal) when the rotary die 220 rotates by another step, the first development S1 in the first die SM1 is moved to the third position 3 and the second development S2 in the die SM4 is moved to the second position 2, where it is processed with a punch 230 with zero gap; meanwhile, a third development S3 is inserted into the die SM3 and moved to the first forming position 1 for forming the pod or container C3; the first development S1 which is in the third position 3 is removed in the form of a formed pod C1 ; removal can take place by vacuum or mechanical extraction;

[0111] STEP 4 - empty) empty step, when the rotary matrix 220 rotates by another step on the first revolution it is empty, but in subsequent revolutions it will be filled with new developments; in this step 4 the second development S2, housed in the die SM2 located in the third position 3, is removed in the form of a formed pod C2; removal can take place by vacuum or mechanical extraction.

[0112] To produce the first pod C1 , the die must be opened and closed three times, but subsequently a finished pod comes from every cycle. Therefore, the fourth position without processing is required for processing continuity, so as not to have any downtime. Since there are three active processing steps (forming, removing creases and removal), a fourth position is needed to start a further processing cycle when the first finished product is removed.

[0113] After the first incomplete cycles, the subsequent three active processing cycles (forming, removing creases and removal) are carried out simultaneously.

[0114] Otherwise, it would be necessary to wait for the die positioned in removal step 3 to be released before being able to start a new processing cycle.

[0115] As can be deduced, the different movements of the rotary matrix and the different processing tools can be carried out in any known way. For example, the rotary matrix can be rotated by an electric motor and the processing tools (or punches) can be controlled by electric or pneumatic motors.

[0116] As already mentioned, Figure 6 shows the movable punch 210 in a plan view (Figure 6a) in which the division of the movement sectors can be seen.

[0117] In particular, Figure 6b shows the starting position of the movable punch 210 with the central part 212 retracted and the forming portion 214 protruding.

[0118] Figure 6c, on the other hand, shows the movable punch 210 in the final position. The sectors are widened to form the pod.

[0119] In particular, the movable punch 210 has a substantially frustoconical tubular shape with a circular cross-section.

[0120] The forming portion 214, i.e. the outer portion, is formed, in the embodiment exemplified here, by three tubular elements 214a with a circular cross-section joined together by three tubular elements 214b with an arrow head cross-section.

[0121] The three tubular elements 214a with a circular cross-section have a central toothshaped protrusion on the chord portion.

[0122] Finally, the central part 212 of the movable punch 210 is substantially tubular shaped with a hexagonal cross-section, in which each side of the hexagon has a groove adapted to collaborate with the central tooth-shaped protrusion of the tubular elements 214a with a circular cross section and with the tail of the arrowheads of the tubular elements 214b with an arrowhead-shaped cross-section.

[0123] The grooves on the central part 212 with a hexagonal cross-section are used as rails for the tooth-shaped protrusions and the tails of the arrowheads.

[0124] Figure 7 show a second type of coffee pod CC, also of the known type.

[0125] Figure 7f shows the development SC for producing the known type of spherical coffee pod CC of the type shown in Figures 7a and 7b. Figure 8 shows the die SM and punch PUNZ assembly for the spherical pod CC in Figure 7.

[0126] In this case, for producing the semi-spherical pod CC, the punch of forming step 1 is divided into two pieces, whereas the punch of step 2 is whole with a matrix gap of 0.12mm.

[0127] Figure 9 shows another type of container obtainable with the solution described herein and in particular tubs CF for fruit puree.

[0128] Figure 9d shows the development SF for producing the tub CF for fruit puree in Figures 9a and 9b.

[0129] Figure 10a shows the die SM and Figure 10b shows the punch PUNZ for producing the tub CF for fruit puree in Figures 9a and 9b.

[0130] Figures 10c and 10d show the plan views of the die SM and the punch PUNZ, respectively.

[0131] In the event of producing the fruit pot or tub CF, the punch is fixed also in the first forming step and the second punch goes to zero to compact the paper, but they are similar except for the gap between the punch and the matrix in both cases (step 1 gap of 1 ,2mm, step 2 gap of 0.2mm).

[0132] Figure 1 1 shows another type of container C obtainable with the solution described herein and in particular a lid for cups CB, e.g. for hot or cold drinks to be transported. Figure 1 1f shows the development SB for producing the lid for cups CB in Figures 1 1 a and 1 1 e.

[0133] Figure 12a shows the die SM and Figure 12b shows the die SM and punch PUNZ assembly for producing the lid for cups CB, e.g. for hot or cold drinks to be transported.

[0134] In this case, for producing the lid for cups CB, the punch for forming step 1 is divided into four parts whereas the punch for step 2 is whole to compress and remove the lines.

[0135] The punch has a system of springs to allow the first central part to descend and then, in succession, the other parts, in order to fold the paper a little at a time and produce the desired profile.

[0136] The difference in the gap between the punch PUNZ and the matrix SM depends exclusively on the thickness of the paper being used. The concept is that in the aforesaid forming step 1 the punch 210 has a generous gap to prevent the paper tearing, the punch 230 in the crease removal step 2, on the other hand, compresses the object to remove all residual creases in the paper.

[0137] In relation to the scores on the paper (see Figures 3b, 4a and 4b) they are not always necessary depending on the type of object to be produced.

[0138] Obviously, each die SM and each punch PUNZ will have particular properties that while coupling allow the development S to be deep drawn in order to produce the final 3D product of the desired shape.

[0139] As explained, the step of producing 3D products is divided into two steps: the first forming step by “folding” while the second “compression” step for removing all the creases created during the folding step.

[0140] For the folding step, the gap between the punch and the matrix is comprised between a factor of 1.5 and 2 with respect to the thickness of the paper. For example, if the paper is 1 mm thick, the gap may be comprised between 1 .5 and 2mm.

[0141] For the compression step, the gap between the punch and the matrix is comprised between a factor of 0.5 and 0,8, with respect to the thickness of the paper. For example, if the paper is 1 mm thick, the gap between the punch and the matrix may be comprised between 0.5 and 0.8mm.

[0142] The covering material Q spread onto the sheets of paper will now be described.

[0143] The covering material Q has two functions: protecting the pod CC or container C from water and allowing the “paper to be glued”, in particular in the meeting and overlapping points of the developments S.

[0144] The material Q is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of silicon-oxygen bonds, in which, possibly, depending on the exact composition of the starting sol, some silicon-oxygen bonds may be replaced by bonds between the silicon and other species (frequently, alkyl groups). The structure consisting of this three-dimensional lattice forms on the surface of the paper, at macroscopic level, a layer with vitreous properties which makes it impermeable to liquids.

[0145] The sol can be prepared by dispersing or dissolving in water or hydroalcoholic mixtures at least one alkyltrialkoxysilane and at least a second component selected from micrometric silica and a tetraalkoxysilane, or both. The micrometric silica (also known in the art as “colloidal silica” or “fumed silica”) is a form of silica consisting of primary particles of silica of nanometric dimensions (i.e. dimensions less than a micrometer, pm) generally aggregated to form secondary particles of micrometric dimensions. This material is widely available on the market and is sold, for example, by the company Evonik Resource Efficiency GmbH in Essen (Germany) under the name AEROSIL® (for example, the product AEROSIL® OX 50), or by the company Cabot Corporation in Boston, Massachusetts (USA) under the name Cab-O-Sil®.

[0146] Tetraalkoxysilanes are compounds with general formula Si(OR)4, in which R is generally a C1 -C6 alkyl radical, preferably C1 -C2.

[0147] Alkyltrihaloxysilanes are compounds with general formula R’-Si(OR)3, in which R and R’, same or different from each other, are generally C1 -C6 alkyl radicals, preferably C1 -C2.

[0148] Tetraalkoxysilanes and alkyltrialcoxysilanes are also widely available products.

[0149] A sol useful for the purposes of the invention can be obtained by following the process described in patent application WO 2022 / 171893 A1 in the name of this Applicant, by dissolving or dispersing in water between 25 and 40% by weight of an alkyl-trihalcoxysilane and a second component selected from micrometric silica, a tetraalkoxysilane, or both. When present, micrometric silica is in quantities comprised between 5 and 20% by weight of the sol, while tetraalkoxysilane, when present, is in quantities comprised between 15 and 25% by weight of the sol. Optionally, one or more other components can be added to this sol, selected from a C1 -C6 alcohol or a mixture thereof and a base selected from NaOH and KOH in such quantities to regulate the pH in the range between 2 and 5.

[0150] Once distributed on the paper, the condensation reactions that lead to the formation of the vitreous layer as described above are made to take place by heating, typically to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C; in the case of heating to temperatures greater than about 230 °C (selfcombustion temperature of the paper), the heating must be rapid and only last long enough for the evaporation of the liquid components of the initial sol.

[0151] As already previously mentioned, types of coated paper are always used which allow improved spreading of the covering material Q and a better gluing effect.

[0152] An example of coated paper is INVERCOTE G 530g / m2made by IGGESUND. In summary, the steps for producing 3D products are as follows:

[0153] - The process start from sheets or a coil; in particular, it starts with a sheet when the paper has a grammage greater than 450g / m2and a coil when the paper has a grammage less than 400g / m2.

[0154] - The paper is impregnated with the covering material Q on all sides.

[0155] - The wet paper enters the die and the following steps take place here:

[0156] - Die cutting,

[0157] - Folding, and

[0158] - Compression.

[0159] All the steps take place simultaneously with the rotation of the die between the folding and compression steps. The die is hot, with a temperature of about 150 °C. When the paper impregnated with covering material Q is first folded then compressed, the covering material Q penetrates all the fibers and once solidified, due to the temperature of the die, it makes the paper extremely resistant to heat, water and oil, and increases its rigidity and mechanical properties.

[0160] The description of specific embodiments provided above shows the invention from a conceptual point of view so that others, using the prior art, will be able to modify and / or adapt in various applications those specific embodiments without further research and without departing from the inventive concept, and, thus, it is understood that such adaptations and modifications will be considered as equivalents of the specific embodiments.

[0161] The means and materials for achieving the various functions described may be of various nature, without departing from the scope of the invention.

[0162] It is worth noting that terminology or expressions used are only descriptive and therefore non-limiting.

[0163] Obviously, without prejudice to the principle of the invention, the construction details and the embodiments can widely vary with respect to that described and illustrated above by way of example, without however departing from the scope of the present invention.

[0164] Where the constructive features and techniques mentioned in the claims below are followed by references signs or numerals, such reference signs were introduced for the sole purpose of increasing the intelligibility of the claims themselves, and therefore, such reference signs have no limiting effect on the interpretation of each element identified, by way of example only, by such reference signs.

Claims

CLAIMS1 ) A process for producing thermoformed 3D objects made of thick coated paper with grammage selected from the range of 180 to 1010 g / m2, comprising the steps of: feeding thick paper (F, B) in a single sheet (F) or coil (B), to a machine (M, M1 ); die cutting (10, 200) the paper for producing flat developments (S) for the 3D object to be formed; spreading onto the paper (F, B) or onto the flat developments (S), upstream or downstream of the die cutting operation, a covering material (Q), wherein the covering material (Q) is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of silicon-oxygen bonds, wherein, depending on the exact composition of the starting sol, some siliconoxygen bonds may be replaced by bonds between the silicon and other species, wherein the other species are alkyl groups; inserting the flat developments (S) covered with covering material (Q) into a heated die (30, SM), deep-drawing the flat developments (S) in the die (30, SM) using a punch (50, PUNZ), wherein this deep-drawing step involves a first forming step with a first punch (210), with a gap with respect to the matrix (SM) creating the die comprised between a factor of 1 .5 and 2 with respect to the thickness of the paper and a second compression step with a second punch (230), with a reduced gap with respect to the matrix (SM) creating the die comprised between a factor of 0.5 and 0.8 with respect to the thickness of the paper to remove any creases created in the forming step, and removing the thermoformed 3D object from the die (30, SM).2) The process for producing thermoformed 3D objects made of thick paper according to claim 1 , wherein the coated paper is covered with a very thin coating which gives it a shiny and polished appearance, wherein such a coating is made of various materials such as kaolin, calcium carbonate, bentonite and talc and the mineral fillers are bound by a latex or a mixture of latex and binders.3) The process for producing thermoformed 3D objects made of thick paper according to claim 1 or claim 2, wherein the paper is single-coated.4) The process for producing thermoformed 3D objects made of thick paper according to claim 1 or claim 2, wherein the paper is double-coated.5) The process for producing thermoformed 3D objects made of thick paper according to any one of the preceding claims, wherein the die is heated to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C, to obtain the transformation of the covering material (Q) into a vitreous layer.6) The process for producing thermoformed 3D objects made of thick paper according to any one of the preceding claims, wherein said first punch (210) is a movable punch formed by various parts (212,214) intervening at different times.7) A machine (M, M1 ) for producing thermoformed 3D objects made of thick paper, comprising the stations for: feeding thick coated paper (F, B) with grammage selected from the range of 180 to 1010 g / m2, in sheets (F) or coils (B); die cutting (10, 200) the paper for producing flat developments (S) for the 3D object to be formed; spreading onto the paper (F, B) or onto the flat developments (S), upstream or downstream of the die cutting operation, a covering material (Q), wherein the covering material (Q) is a sol, i.e. a viscous solution containing silicon compounds which in the phases subsequent to depositing on the paper cause condensation reactions forming a three-dimensional lattice of silicon-oxygen bonds, wherein, depending on the exact composition of the starting sol, some siliconoxygen bonds may be replaced by bonds between the silicon and other species, wherein the other species are alkyl groups, forming the 3D object using a heated die (30, SM), deep-drawing using a punch (50, PUNZ) and a matrix (SM), wherein this deep-drawing station involves a first forming step with a first punch (210) with a gap with respect to the matrix (SM) creating the die comprised between a factor of 1 .5 and 2 with respect to the thickness of the paper and a second compression step with a second punch (230) with a reduced gap with respect to the matrix (SM) creating the die comprised between a factor of 0.5 and 0.8 with respect to the thickness of the paper to remove any creases created in the forming step, andremoving the thermoformed 3D object from the die (30, SM).8) The machine for producing thermoformed 3D objects made of thick paper according to claim 6, wherein the coated paper is covered with a very thin coating which gives it a shiny and polished appearance, wherein such a coating is made of various materials such as kaolin, calcium carbonate, bentonite and talc and the mineral fillers are bound by a latex or a mixture of latex and binders.9) The machine for producing thermoformed 3D objects made of thick paper according to claim 8 or 9, wherein the paper is single-coated.10) The machine for producing thermoformed 3D objects made of thick paper according to claim 8 or 9, wherein the paper is double-coated.1 1 ) The machine for producing thermoformed 3D objects made of thick paper according to one of claims 8-1 1 , wherein said station for spreading the covering material (Q) has a spreading roller (20,1 10).12) The machine for producing thermoformed 3D objects made of thick paper according to any one of the preceding claims 8-12, wherein the die is heated by electric resistors to temperatures comprised between 100 and 250 °C, preferably between 150 and 200 °C, in order to obtain the transformation of the covering material (Q) into a vitreous layer.13) The machine for producing thermoformed 3D objects made of thick paper according to claim 12, wherein said first punch (210) is a movable punch formed by various parts (212,214) which intervene at different times.14) A thermoformed 3D object made of thick paper, produced according to the process of claims 1 -6.15) A thermoformed 3D object made of thick paper, produced using the machine according to claims 8-13.

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