(19)
(11)EP 3 953 494 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
03.08.2022 Bulletin 2022/31

(21)Application number: 20718610.7

(22)Date of filing:  06.04.2020
(51)International Patent Classification (IPC): 
C14B 1/30(2006.01)
B32B 9/02(2006.01)
B68F 1/00(2006.01)
C14B 1/44(2006.01)
B29C 51/00(2006.01)
B32B 37/10(2006.01)
C14B 1/58(2006.01)
(52)Cooperative Patent Classification (CPC):
C14B 1/30; C14B 1/58; B68F 1/00; C14B 1/44
(86)International application number:
PCT/EP2020/059785
(87)International publication number:
WO 2020/207977 (15.10.2020 Gazette  2020/42)

(54)

MANUFACTURING PROCESS OF THREE-DIMENSIONAL LEATHER OBJECTS

VERFAHREN ZUR HERSTELLUNG VON DREIDIMENSIONALEN LEDERGEGENSTÄNDEN

PROCÉDÉ DE FABRICATION D'OBJETS EN CUIR TRIDIMENSIONNELS


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
KH MA MD TN

(30)Priority: 08.04.2019 IT 201900005366

(43)Date of publication of application:
16.02.2022 Bulletin 2022/07

(73)Proprietor: Egas Consulting Societa' a Responsabilita' Limitata Semplificata
60022 Castelfidardo (AN) (IT)

(72)Inventor:
  • CINGOLANI, Corrado Luigi
    60022 CASTELFIDARDO (AN) (IT)

(74)Representative: Cutropia, Gianluigi 
Ing. Claudio Baldi s.r.l. Viale Cavallotti, 13
60035 Jesi (AN)
60035 Jesi (AN) (IT)


(56)References cited: : 
EP-A1- 3 348 653
FR-A1- 2 933 894
DE-B3-102004 033 662
JP-A- 2001 259 264
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to a manufacturing process of three-dimensional leather objects.

    [0002] A three-dimensional leather object is obtained by performing a pre-forming operation on the leather in order to shape the leather with a permanent three-dimensional geometry, without using a fixed rigid support.

    [0003] Such a pre-forming process can be used to create leather objects with an autonomous three-dimensional shape, and also to create semi-finished items used for coating three-dimensional objects, giving the semi-finished item the shape that it will have after being fixed to the structure to be coated.

    [0004] Automated coating processes that use different types of materials other than leather are currently known. However, automated processes are rarely used for leather coating. In fact, generally speaking, automated leather coating processes are only used for linear geometries and simple shapes because of the difficulties encountered in forming complex leather shapes.

    [0005] Leather pre-forming operations based on forming processes have been proposed and experimented in the prior art. However, the forming processes are expensive and suitable only for mass productions. Moreover, these forming processes are impaired by a considerable limitation of the geometries and finishes of the leather objects.

    [0006] Fig. 1 is a diagrammatic view of a forming process of a leather coating according to the prior art.

    [0007] In step 1, a piece of leather (101) with a flesh side (101a) and a grain side (101b) is provided. The grain side (101b) has a surface grain and/or pattern.

    [0008] The piece of leather (101) is pre-treated with steam and/or starch to increase the elasticity, the malleability and the maintenance of the impressed form, and is disposed in a heated mold that comprises a male half-mold (A) and a female half-mold (B). The heated metal surfaces of the half-molds (A, B) and the pressure exerted on the piece of leather (101) tend to stretch the leather, eliminating the grain and/or surface print on the grain side (101b) of the leather. When the process is finished, the piece of leather (101) maintains its the shape, but loses its softness almost completely.

    [0009] In step 2, a supporting structure (100) composed of thermo-formable and/or injectable material is formed in a heated mold that comprises a male half-mold (C) and a female half-mold (D), in such a way to obtain the desired shape.

    [0010] In step 3, the piece of leather (101) and the supporting structure (100) are coupled by means of an adhesion element (102) as adhesive, polyurethane (PU) foam, resins, water or solvent-based adhesive and the like. Such a coupling is performed with a heated mold provided with a male half-mold (E) and a female half-mold (F).

    [0011] The male half-mold (E) that operates on the grain side (101b) of the piece of leather is provided with a pattern of the grain and/or surface pattern of the leather, in such a way to restore the original grain and/or surface pattern or create a specific pattern.

    [0012] In this way a three-dimensional leather object (103) is obtained. However, in spite of being technically and technologically appreciated in terms of repeatability, precision and speed of execution, the final result is impaired by the fact that leather loses the softness and tactile perception that are typical of leather objects that are not hot-formed. Moreover, the molds for such a process are very expensive and are only feasible for productions of more than 50,000-100,000 pieces.

    [0013] DE102004033662 discloses a process to form leather products.

    [0014] The purpose of the present invention is to eliminate the drawbacks of the prior art by disclosing a manufacturing process of three-dimensional leather objects that does not alter the sensory perception of the leather.

    [0015] Another purpose is to disclose such a manufacturing process of three-dimensional leather objects that is efficient, effective, reliable, versatile, practical, inexpensive and easy to make.

    [0016] These purposes are achieved according to the invention with the characteristics of the independent claim 1.

    [0017] Advantageous embodiments of the invention appear from the dependent claims.

    [0018] The purpose of the applicant is to create three-dimensional leather objects to obtain leather objects with a specific shape that is maintained over time and to facilitate the application process of said three-dimensional leather objects on structures that are to be coated such as logos, trademarks, lasts and accessories for shoes, patterns and geometric shapes, car parts, leather components, accessories, cases or boxes in general.

    [0019] The main technical problem is represented by the fact that leather needs to maintain the deformation without irreversibly altering the mechanical, aesthetic and organoleptic features of the deformed material.

    [0020] The manufacturing process of three-dimensional leather objects is defined in claim 1.

    [0021] Additional features of the invention will be clearer from the following detailed description, which refers to a merely illustrative, not limiting embodiment, which is shown in the appended figures, wherein:

    Fig. 1 is a diagrammatic view of the steps of a manufacturing process of three-dimensional leather objects according to the prior art;

    Fig. 2 is a diagrammatic view of a first step of the manufacturing process of three-dimensional leather objects according to the invention;

    Fig. 3 is a diagrammatic view of a roller coating machine for the application of additive on a piece of leather;

    Fig. 4 is a diagrammatic view of a second step of the manufacturing process of three-dimensional leather objects according to the invention;

    Figs. 5 and 6 are diagrammatic views of the following steps of the manufacturing process of three-dimensional leather objects according to the invention; and

    Fig. 7 is a diagrammatic view of a variant of the manufacturing process of three-dimensional leather objects according to the invention.



    [0022] The manufacturing process of three-dimensional leather objects according to the invention comprises the provision of a piece of leather (1) with a flesh side (1a) and a grain side (1b). A hardener additive (2) is applied on the flesh side (1a) of the piece of leather, in such a way to be absorbed by the leather fibers without reaching the grain side (1b) of the piece of leather. The additive (2) applied on the piece of leather (1) undergoes a drying process (3) that can be performed in the fresh air for 20-30 minutes or in a drying chamber.

    [0023] The additive (2) is a chemical compound that is activated at a temperature comprised between 40°C and 50°C. The additive (2) comprises

    [0024] Thiophene, Sodium Dioctyl Sulphosuccinate, Alcohols, Fatty Alcohols (long-chain alcohols) C12-18 (even numbered) and Ethoxylates.

    [0025] It must be considered that when the temperature increases, the elasticity and plasticity of leather generally increase and leather can be given the desired shape by uniformly distributing a pressure according to a specific geometry.

    [0026] The addition of the additive (2) on the piece of leather (1) increases the homogeneous elasticity of the piece of leather (1) on every part of the geometric area where pressure is exerted.

    [0027] The additive (2) must be homogeneously applied on the flesh side (1a) of the piece of leather. Spray-coating machines or roller coating machines can be used to apply the additive (2); otherwise, the additive (2) can be applied manually with a sponge or a roller. In order for the additive (2) to penetrate the piece of leather (1) with the correct depth, without getting the grain side (1b) of the piece of leather wet, an average dose of additive from 300 to 500 g/m2 is used according to the features of the leather and the result to be obtained.

    [0028] Fig. 3 illustrates a roller coating machine, wherein the piece of leather (1) is fed between a first counter-rotating roller (R1) and a second counter-rotating roller (R2), and the flesh side (1a) of the piece of leather is directed towards the first roller (R1). The additive (2) contained in a tank (V) is used to get the first roller (R1) wet.

    [0029] With reference to Fig. 4, when the piece of leather (1) is treated with the additive (2) and is completely dried, said piece of leather (1) is disposed on a forming shape (4), with the flesh side (1a) of the piece of leather disposed on the shape (4). The shape (4) can be selected according to the shape to be given to the piece of leather. Alternatively, the shape (4) can directly consist in a structure whereon the piece of leather is suitable for being glued in order to coat said structure with leather.

    [0030] Tensioning and holding elements (5) can be applied in the areas with the highest level of deformation and stretching of the piece of leather (1) in order to copy concave and/or convex geometries of the shape (4) and avoid the formation of wrinkles and creases.

    [0031] A membrane (60) is applied on the grain side (1b) of the piece of leather (1) in order to homogeneously exert a uniform pressure. The membrane (60) must be made of a soft, elastic material in such a way not to compress the grain side (1b) of the leather, without flattening and polishing the finishing of the grain side and maintaining the pattern of the original grain of the grain side (1b) of the piece of leather.

    [0032] With reference to Fig. 5, after the piece of leather (1) is disposed on the shape (4), the piece of leather (1) and the shape (4) are inserted in a vacuum sack (6) that generates the membrane (60) that is distributed on the grain side (1b) of the piece of leather. The vacuum sack (6) is hermetically closed and connected to a vacuum pump (61). Air is extracted from the vacuum sack (6) by means of the pump (61), in such a way that the flesh side (1a) of the piece of leather is in close contact with the shape (4), without compressing the piece of leather. In view of the above, the piece of leather and the shape (4) will not change their position during the following handling steps. A rough vacuum (RV) is applied during this step: 1 × 105 Pa -1 × 102 Pa. The rough vacuum is sufficient to make the piece of leather adhere to the shape.

    [0033] With reference to Fig. 6, the vacuum sack (6) with the shape (4) and the piece of leather (1) is inserted in a hot chamber (7) that is heated at a temperature of 40°-75°C. Such a hot chamber (7) may be ventilated. The vacuum sack (6) with the shape (4) and the piece of leather (1) remains in the hot chamber (7) for 3-10 minutes, according to the dimensions and thickness of the piece of leather (1) and of the shape (4), in such a way that the piece of leather reaches a uniform temperature of approximately 50°C. The additive (2) is activated at the temperature of 40°-50° and the deformability of the piece of leather increases.

    [0034] It must be considered that the process according to the invention is performed at a low temperature (approximately 50°), i.e. at a temperature that is considerably lower than the temperature of the piece of leather (1) for the formation of the grain on the grain side (1b). Therefore, the leather is not significantly altered in the areas with the highest deformation and/or stretching, as it occurs in the hot forming process wherein leather is in contact with hard surfaces, such as the heated aluminum or steel surface of the half-mold.

    [0035] Vacuum is applied to the vacuum sack (6) and air is extracted gradually by means of the vacuum pump (61), in such a way to progressively compress the piece of leather (1) on the shape (4) until the desired shape is achieved. In this step a high vacuum (HV) can be gradually achieved: 1 × 10-1 Pa - 1 × 10-5 Pa.

    [0036] When the desired deformation of the piece of leather (1) is achieved, the vacuum sack (6) is extracted from the hot chamber, keeping the vacuum pressure in the vacuum sack (6).

    [0037] The vacuum sack (6) with the shape (4) and the piece of leather (1) is cooled in the fresh air or in a ventilated environment until the piece of leather (1) reaches a temperature of 25°C. When the piece of leather reaches a temperature of 25°C, the vacuum sack (6) is opened and the shape (4) and the piece of leather (1) are extracted.

    [0038] The use of the vacuum sack (6) permits to exert a homogeneous pressure on all the surfaces of the piece of leather (1), in any direction, without the limitation of the closing direction of the mold that occurs in the hot forming process according to the prior art. In view of the above, undercuts or reliefs can be copied also in the lateral sides of the shape (4), without using any lateral movement of the shape or any special automation.

    [0039] Now the piece of leather (1) can be detached from the shape (4). The piece of leather (1) has taken the form of the shape (4) whereon it has been pressed, maintaining the geometry and the original elasticity and softness properties.

    [0040] With reference to Fig. 7, according to a variant of the method of the invention, before disposing the piece of leather (1) on the shape (4), an adhesive (8) is applied on the flesh side (1a) of the piece of leather. Such a type of adhesive is an aqueous-based adhesive that is activated at a temperature higher than 70° C.

    [0041] When the adhesive (8) is dry, the piece of leather (1) is disposed on the shape (4) and the shape (4) with the piece of leather (1) are disposed in the vacuum sack (6). Considering that the vacuum forming process occurs at a temperature of approximately 50°C of the piece of leather, the adhesive (8) is not activated and therefore, when the process is finished, the piece of leather (1) can be detached from the shape (4) because adhesion was not obtained. When the piece of leather (1) must be fixed to a supporting structure, it will be simply necessary to heat such a piece of leather at a temperature equal to the activation temperature of the adhesive (8) in such a way that the piece of leather is adhered on the supporting structure.

    [0042] For illustrative purposes, Fig. 8 illustrates a three-dimensional leather object (9) obtained with the process of the invention.

    [0043] As clearly shown in Fig. 8, the grain of the grain side of the leather is unaltered; moreover, several recessed or undercut lateral parts of the three-dimensional leather object (9), which cannot be obtained with a hot forming process, are obtained.


    Claims

    1. Manufacturing process of three-dimensional leather objects, comprising the following steps:

    - providing a piece of leather (1) with a flesh side (1a) and a grain side (1b);

    - providing a shape (4) with the same shape as a three-dimensional object to be obtained;

    - positioning the flesh side (1a) of the piece of leather on the shape (4);

    - introducing the shape (4) with the piece of leather (1) inside a vacuum sack (6) in such a way that the vacuum sack generates a membrane (60) applied on the grain side (1b) of the piece of leather; and

    - applying rough vacuum in said vacuum sack (6) in such a way that the flesh side (1a) of the piece of leather adheres on the shape (4);
    characterized in that said process comprises the following steps:

    - applying a hardener additive (2) on the flesh side (1a) of the piece of leather; wherein said hardener additive (2) is activated at an activation temperature of approximately 40°C-approximately 50°C;

    - drying of the hardener additive (2);

    - heating the vacuum sack (6) with the shape (4) and the piece of leather (1) until the piece of leather (1) reaches the activation temperature of the hardener additive;

    - applying vacuum progressively during the heating step, in such a way to progressively compress the piece of leather (1) onto the shape (4) until the desired shape is obtained;

    - cooling the vacuum sack (6) with the shape (4) and the piece of leather (1) until the piece of leather (1) reaches a temperature of approximately 25°C in vacuum conditions;

    - extracting the shape (4) with the piece of leather (1) from the vacuum sack (6); and

    - removing the piece of leather (1) from the shape (4) in such a way that the piece of leather (1) has the shape of a three-dimensional object.


     
    2. The process of claim 1, wherein said hardener additive (2) is applied on the flesh side (1a) of the piece of leather, in such a way to be absorbed by the leather fibers without reaching the grain side (1b) of the piece of leather.
     
    3. The process of claim 2, wherein said hardener additive (2) has an average dosage of 300-500 g/m2.
     
    4. The process of any one of the preceding claims, wherein said hardener additive (2) comprises Thiophene, Sodium Dioctyl Sulphosuccinate, Alcohols, Fatty even numbered Alcohols C12-18 and Ethoxylates.
     
    5. The process of any one of the preceding claims, wherein tensioning and holding elements (5) are applied in the areas with the highest level of deformation and stretching of the piece of leather (1) in order to copy concave and/or convex geometries of the shape (4), avoiding the formation of wrinkles and creases.
     
    6. The process of any one of the preceding claims, wherein said heating step is performed by positioning the vacuum sack (6) with the shape (4) and the piece of leather (1) in a hot chamber (7) that is heated at a temperature of 40°C-75°C for 3-10 minutes.
     
    7. The process of any one of the preceding claims, wherein in said step of progressively applying high vacuum during the heating step, high vacuum is obtained inside said vacuum sack (6).
     
    8. The process of any one of the preceding claims, wherein after drying the hardener additive (2) and before positioning the flesh side (1a) of the piece of leather on the shape (4), an adhesive (8) is applied on the flesh side (1a) of the piece of leather, said adhesive (8) having an activation temperature higher than 70°C, in such a way not to be activated during the heating of the vacuum sack (6) with the shape (4) and the piece of leather (1).
     
    9. The process of any one of the preceding claims, wherein said drying step of the hardener additive (2) is performed in fresh air or in a ventilated chamber.
     
    10. The process of any one of the preceding claims, wherein said cooling step of the vacuum sack (6) with the shape (4) and the piece of leather (1) is performed in fresh air or in a climatic chamber.
     


    Ansprüche

    1. Verfahren zur Herstellung von dreidimensionalen Lederobjekten, umfassend die folgenden Schritte:

    - Bereitstellen eines Lederstücks (1) mit einer Fleischseite (1a) und einer Narbenseite (1b);

    - Bereitstellen einer Form (4) mit derselben Form wie ein zu erhaltendes dreidimensionales Lederobjekt;

    - Bestimmen der Fleischseite (1a) des Lederstücks auf der Form (4);

    - Einlegen der Form (4) mit dem Lederstück (1) in einen Vakuumsack (6), so dass der Vakuumsack eine Membran (60) erzeugt, die auf die Narbenseite (1b) des Lederstücks aufgebracht wird; und

    - Aufbringen eines Grobvakuums (rough vacuum) in dem Vakuumsack (6), so dass die Fleischseite (1a) des Lederstücks an der Form (4) haftet;
    dadurch gekennzeichnet, dass das Verfahren die folgenden Schritte umfasst:

    - Aufbringen eines Härterzusatzes (2) auf der Fleischseite (1a) des Lederstücks; wobei der Härterzusatz (2) bei einer Aktivierungstemperatur von ungefähr 40 °C - ungefähr 50 °C aktiviert wird;

    - Trocknen des Härterzusatzes (2);

    - Erwärmen des Vakuumsacks (6) mit der Form (4) und dem Lederstück (1) darin, bis das Lederstück (1) die Aktivierungstemperatur des Härterzusatzes erreicht;

    - schrittweises Aufbringen von Vakuum während der Erwärmungsphase, um das Lederstück (1) schrittweise auf die Form (4) zu drücken, bis die gewünschte Form erhalten wird;

    - Abkühlen des Vakuumsacks (6) mit der Form (4) und dem Lederstück (1) darin, bis das Lederstück eine Temperatur von ungefähr 25 °C unter Vakuumbedingungen erreicht;

    - Herausnehmen der Form (4) mit dem Lederstück (1) aus dem Vakuumsack (6); und

    - Entfernen des Lederstücks (1) von der Form (4), so dass das Lederstück (1) die Form eines dreidimensionalen Objekts aufweist.


     
    2. Verfahren nach Anspruch 1 wobei der Härterzusatz (2) auf der Fleischseite (1a) des Lederstücks aufgebracht wird, so dass er von den Lederfasern absorbiert wird, ohne bis zur Narbenseite (1b) des Lederstücks zu gelangen.
     
    3. Verfahren nach Anspruch 2 wobei der Härterzusatz (2) eine durchschnittliche Dosierung von 300-500 g/m2 aufweist.
     
    4. Verfahren nach einem der vorstehenden Ansprüche, wobei der Härterzusatz (2) Thiophen, Natriumdioctylsulfosuccinat, Alkohole, geradzahlige Fettalkohole C12-18 und Ethoxylate umfasst.
     
    5. Verfahren nach einem der vorstehenden Ansprüche, wobei Spann- und Halteelemente (5) in den Bereichen mit höherer Verformung und Dehnung des Lederstücks (1) aufgebracht werden, um konkave und/oder konvexe Geometrien der Form (4) zu kopieren und die Bildung von Falten und Knicken zu vermeiden.
     
    6. Verfahren nach einem der vorstehenden Ansprüche, wobei der Schritt des Erwärmens ausgeführt wird, indem der Vakuumsack (6) mit der Form (4) und dem Lederstück (1) darin in einer Wärmekammer (7) angeordnet wird, die für 3 - 10 Minuten auf eine Temperatur von 40 °C - 75 °C erwärmt wird.
     
    7. Verfahren nach einem der vorstehenden Ansprüche, wobei in dem Schritt des schrittweisen Aufbringens von Vakuum in der Erwärmungsphase ein Hochvakuum (high vacuum) in dem Vakuumsack (6) erzielt wird.
     
    8. Verfahren nach einem der vorstehenden Ansprüche, wobei nach dem Trocknen des Härterzusatzes (2) und vor dem Anordnen der Fleischseite (1a) des Lederstücks auf der Form (4) auf der Fleischseite (1a) des Lederstücks ein Haftmittel (8) aufgebracht wird, das eine Aktivierungstemperatur von über 70 °C aufweist, so dass es während des Erwärmens des Vakuumsacks (6) mit der Form (4) und dem Lederstück (1) darin nicht aktiviert wird.
     
    9. Verfahren nach einem der vorstehenden Ansprüche, wobei der Schritt des Trocknens des Härterzusatzes (2) an frischer Luft oder in einer belüfteten Kammer ausgeführt wird.
     
    10. Verfahren nach einem der vorstehenden Ansprüche, wobei der Schritt des Abkühlens des Vakuumsacks (6) mit der Form (4) und dem Lederstück (1) darin an frischer Luft oder in einer Klimakammer ausgeführt wird.
     


    Revendications

    1. Processus pour la réalisation d'objets en peau tridimensionnels, comprenant les phases suivantes :

    - prédisposition d'une pièce de peau (1) ayant un côté chair (1a) et un côté fleur (1b);

    - prédisposition d'un modèle (4) ayant la forme de l'objet tridimensionnel que l'on veut obtenir ;

    - disposition du côté chair (1a) de la pièce de peau sur le modèle (4) ;

    - introduction du modèle (4) avec la pièce de peau (1) dans un système de sac sous vide (6) de façon à ce que le système de sac sous vide génère une membrane (60) appliquée sur le côté fleur (1b) de la pièce de peau ; et

    - application d'un vide primaire (Rough Vacuum) dans ledit sac sous vide (6), de façon à ce que le côté chair (1a) de la pièce de peau adhère au modèle (4) ;
    caractérisé en ce que ledit processus comprend les phases suivantes :

    - application d'un additif durcisseur (2) sur le côté chair (1a) de la pièce de peau ; où ledit additif durcisseur (2) s'active à une température d'activation d'environ 40°C - approximativement 50°C ;

    - séchage de l'additif durcisseur (2) ;

    - réchauffement du sac sous vide (6) avec à l'intérieur le modèle (4) et la pièce de peau (1), jusqu'à ce que la pièce de peau (1) atteigne la température d'activation de l'additif durcisseur ;

    - application progressive du vide pendant la phase de réchauffement de manière à écraser progressivement la pièce de peau (1) sur le modèle (4) jusqu'à obtenir la forme désirée ;

    - refroidissement du sac sous vide (6) avec à l'intérieur le modèle (4) et la pièce de peau (1), jusqu'à ce que la pièce de peau atteigne une température d'environ 25°C, en condition sous vide ;

    - extraction du modèle (4) avec la pièce de peau (1) du sac sous vide (6) ; et

    - décrochage de la pièce de peau (1) du modèle (4) de façon à ce que la pièce de peau (1) ait la forme d'un objet tridimensionnel.


     
    2. Processus selon la revendication 1, où ledit additif durcisseur (2) est appliqué sur le côté chair (1a) de la pièce de peau, de façon à ce qu'il soit absorbé par des fibres de la peau sans qu'il ne pénètre du côté fleur (1b) de la pièce de peau.
     
    3. Processus selon la revendication 2, où ledit additif durcisseur (2) a un dosage moyen de 300-500 g/m2.
     
    4. Processus selon l'une quelconque des revendications précédentes, où ledit additif durcisseur (2) comprend Thiophène, Sulfosuccinate de dyoctile et de sodium, Alcools, Alcools gras C12-18 nombres pairs et éthoxylates.
     
    5. Processus selon l'une quelconque des revendications précédentes, où les tenseurs et éléments de maintien (5) sont appliqués sur des zones de plus grande déformation ou étirement de la pièce de peau (1) pour copier les géométries concaves et/ou convexes du modèle (4), en évitant la formation de plis et de rides.
     
    6. Processus selon l'une quelconque des revendications précédentes, où ladite phase de réchauffement est effectuée en disposant le sac sous vide (6) avec à son intérieur le modèle (4) et la pièce de peau (1), dans une chambre chaude (7) réchauffée à une température de 40°C - 75°C, pendant un temps de 3 - 10 minutes.
     
    7. Processus selon l'une quelconque des revendications précédentes, où ladite phase d'application progressive du vide pendant la phase de réchauffement est obtenue en atteignant un vide élevé (High Vacuum) dans ledit sac sous vide (6).
     
    8. Processus selon l'une quelconque des revendications précédentes, où après le séchage de l'additif durcisseur (2) et avant la disposition du côté chair (1a) de la pièce de peau sur le modèle (4), sur le côté chair (1a) de la pièce de peau on applique un adhésif (8) ayant une température d'activation majeure de 70°C, de manière à ce qu'il ne soit pas activé pendant le réchauffement du sac sous vide (6) avec à l'intérieur le modèle (4) et la pièce de peau (1).
     
    9. Processus selon l'une quelconque des revendications précédentes, où ladite phase de séchage de l'additif durcisseur (2) s'effectue à l'air libre ou dans une chambre ventilée.
     
    10. Processus selon l'une quelconque des revendications précédentes, où ladite phase de refroidissement du sac sous vide (6) avec à l'intérieur le modèle (4) et la pièce de peau (1) s'effectue à l'air libre ou dans une chambre climatisée.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description