阅读说明：本技术 三维皮革制品的制造工艺 (Process for manufacturing three-dimensional leather product ) 是由 C·L·钦戈拉尼 于 2020-04-06 设计创作，主要内容包括：一种三维皮具的制作工艺,包括以下步骤：将硬化剂添加剂(2)施加在皮革片的肉面(1a)上,将皮革片的肉面(1a)定位在型材(4)上,将具有型材(4)的皮革片(1)放入真空袋(6)中,对真空袋(6)施加真空,加热具有型材(4)和皮革片(1)的真空袋(6),在加热步骤中逐渐施加真空,停止真空压力,冷却具有型材(4)和皮革片(1)的真空袋(6),打开袋并从真空袋(6)中取出具有皮革片(1)的型材(4)并将皮革片(1)从型材(4)中取出,从而使皮革片(1)具有三维制品的形状。(A manufacturing process of three-dimensional leather products comprises the following steps: applying a hardener additive (2) to the flesh side (1a) of the leather sheet, positioning the flesh side (1a) of the leather sheet on the profile (4), placing the leather sheet (1) with the profile (4) in a vacuum bag (6), applying a vacuum to the vacuum bag (6), heating the vacuum bag (6) with the profile (4) and the leather sheet (1), gradually applying a vacuum in the heating step, stopping the vacuum pressure, cooling the vacuum bag (6) with the profile (4) and the leather sheet (1), opening the bag and removing the profile (4) with the leather sheet (1) from the vacuum bag (6) and removing the leather sheet (1) from the profile (4), so that the leather sheet (1) has the shape of a three-dimensional article.)

1. The manufacturing process of the three-dimensional leather product comprises the following steps:

-providing a leather sheet (1) having a flesh side (1a) and a texture side (1 b);

-applying a hardener additive (2) on the flesh side (1a) of the leather sheet; wherein the hardener additive (2) is activated at an activation temperature of about 40 ℃ to 50 ℃;

-drying the hardener additive (2);

-providing a profile (4) having the same shape as the three-dimensional article to be obtained;

-positioning the flesh side (1a) of the leather sheet on the profile (4);

-placing the profile (4) with the leather sheet (1) in a vacuum bag (6) so that the vacuum bag produces a film (60) applied on the textured side (1b) of the leather sheet;

-applying a rough vacuum in said vacuum bag (6) so as to cause the flesh side (1a) of the leather piece to adhere to the profile (4);

-heating the vacuum bag (6) with the profile (4) and the leather sheet (1) until the leather sheet (1) reaches the activation temperature of the hardener additive;

-gradually applying vacuum during the heating step, so as to gradually press the leather sheet (1) onto the profile (4) until the desired shape is obtained;

-cooling the vacuum bag (6) with the profile (4) and the leather sheet (1) until the leather sheet (1) reaches a temperature of about 25 ℃ under vacuum conditions;

-removing the profile (4) with the leather sheet (1) from the vacuum bag (6);

-removing the leather sheet (1) from the profile (4) so that the leather sheet (1) has the shape of a three-dimensional article.

2. The method according to claim 1, characterized in that the hardener additive (2) is applied on the flesh side (1a) of the leather sheet so as to be absorbed by the leather fibres without reaching the grain side (1b) of the leather sheet.

3. The process as claimed in claim 2, characterized in that the average dosage of the hardener additive (2) is 300-500g/m²。

4. Process according to any one of the preceding claims, characterized in that the hardener additive (2) comprises thiophene, dioctyl sodium sulfosuccinate, alcohols, fatty alcohols C12-18 (even number) and ethoxylates.

5. Method according to any one of the preceding claims, characterized in that tensioning and fixing elements (5) are applied in the areas of the leather sheet (1) where the level of deformation and stretching is the highest, to reproduce the concave and/or convex geometry of the profile (4), avoiding the formation of wrinkles and folds.

6. Method according to any of the preceding claims, characterized in that the heating step is performed by positioning the vacuum bag (6) with the profile (4) and the leather sheet (1) in a hot chamber (7), the hot chamber (7) being heated at a temperature of 40-75 ℃ for 3-10 minutes.

7. Method according to any of the preceding claims, characterized in that in said step of gradually applying a high vacuum during the heating step, a high vacuum is obtained inside said vacuum bag (6).

8. Method according to any of the preceding claims, characterized in that after drying the hardener additive (2) and before positioning the flesh side (1a) of the leather sheet on the profile (4), an adhesive (8) is applied on the flesh side (1a) of the leather sheet, the activation temperature of said adhesive (8) being higher than 70 ℃, so as not to be activated in the heating of the vacuum bag (6) with the profile (4) and the leather sheet (1).

9. The method according to any of the preceding claims, characterized in that said drying step of the hardener additive (2) is carried out in fresh air or in a ventilated chamber.

10. Method according to any of the preceding claims, characterized in that the cooling step of the vacuum bag (6) with the profile (4) and the leather sheet (1) is carried out in fresh air or in a climatic chamber.

Technical Field

The invention relates to a manufacturing process of a three-dimensional leather product.

Background

Three-dimensional leather products are obtained by subjecting the leather to a preforming operation to obtain leather having a permanent three-dimensional geometry, without using a fixed rigid support.

This pre-forming process can be used to create leather products with autonomous three-dimensional shapes, and also to create semi-finished products for coating three-dimensional products, with the semi-finished products having a shape after fixing on the structure to be coated.

Automated coating processes using different types of materials than leather are currently known. However, automated processes are rarely used for leather coating. In fact, in general, automated leather coating processes are only used for linear geometries and simple shapes, because difficulties are encountered in forming complex leather shapes.

Leather preforming operations based on a forming process have been proposed and tested in the prior art. However, the molding process is expensive and is only suitable for mass production. Furthermore, these forming processes are considerably limited by the geometry and surface treatment of the leather articles.

Fig. 1 is a schematic view of a process for forming a leather coating according to the prior art.

In step 1, a leather sheet 101 having a flesh side (flesh side)101a and a grain side (grain side)101b is provided. The textured side 101b has a surface texture and/or pattern.

The leather sheet 101 is pre-treated with steam and/or starch to increase the elasticity, extensibility and retention of the impression form and placed in a heated mold comprising a male mold half a and a female mold half B. The heated metal surface of mold half A, B and the pressure applied to leather sheet 101 tend to stretch the leather, removing the texture and/or surface printing on leather textured side 101 b. When the process is complete, leather sheet 101 retains its shape, but loses its flexibility almost completely.

In step 2, a support structure 100 composed of a thermoformable and/or injectable material is formed in a heated mold comprising a male mold half C and a female mold half D, so as to obtain the desired shape.

In step 3, the leather sheet 101 and the support structure 100 are connected by means of an adhesive element 102 as an adhesive, polyurethane PU foam, resin, water or solvent based adhesive or the like. This coupling is carried out by heating a mould provided with a male mould half E and a female mould half F.

The male mold half E, operating on the textured side 101b of the leather sheet, has the texture and/or surface pattern of the leather, so as to restore the original texture and/or surface pattern or create a specific pattern.

In this way a three-dimensional leather article 103 is obtained. However, despite being technically appreciated in terms of repeatability, precision and execution speed, the end result is a drawback since the leather loses the flexibility and feel typical of non-thermoformed leather articles. Moreover, the molds of this process are very expensive and can only produce over 50,000 and 100,000 pieces.

DE102004033662 discloses a method of forming a leather product.

Disclosure of Invention

The object of the present invention is to eliminate the drawbacks of the prior art by disclosing a process for the manufacture of three-dimensional leather products that does not alter the sensory perception of the leather.

Another object is to disclose a process for the manufacture of three-dimensional leather products which is efficient, effective, reliable, versatile, practical, inexpensive and easy to make.

These objects are achieved according to the invention with the features of independent claim 1.

Advantageous embodiments of the invention emerge from the dependent claims.

The applicant's aim is to create a three-dimensional leather article to obtain a leather article with a specific shape that is maintained over time and to facilitate the application process of said three-dimensional leather article on the structure to be coated (for example logos, trademarks, lasts and footwear accessories, patterns and geometries, automotive parts, leather parts, accessories, boxes or boxes).

The main technical problem is represented by the need for the leather to maintain the deformation without irreversibly altering the mechanical, aesthetic and organoleptic characteristics of the deformed material.

A method of manufacturing a three-dimensional leather product as claimed in claim 1.

Drawings

Additional features of the invention will become clearer from the following detailed description, which relates to an exemplary and non-limiting embodiment only, and is illustrated in the accompanying drawings, in which:

FIG. 1 is a schematic representation of the steps of a process for making a three-dimensional leather article of the prior art;

FIG. 2 is a schematic view of a first step of the process for the manufacture of three-dimensional leather products according to the invention;

FIG. 3 is a schematic diagram of a roll coating machine for applying additives to leather sheets;

FIG. 4 is a schematic view of a second step of the process for the manufacture of three-dimensional leather products according to the invention;

FIGS. 5 and 6 are schematic views of the next steps of the process of manufacturing the three-dimensional leather product of the present invention; and

fig. 7 is a schematic view of a variant of the process for the manufacture of three-dimensional leather products according to the invention.

Detailed Description

The method of manufacturing a three-dimensional leather product according to the invention comprises providing a leather sheet 1 having a flesh side 1a and a grain side 1 b. The hardener additive 2 is applied to the flesh side 1a of the leather sheet so as to be absorbed by the leather fibres and not reach the grain side 1b of the leather sheet. The additive 2 applied on the leather sheet 1 is subjected to a drying process 3, which drying process 3 can be carried out in fresh air or in a drying chamber for 20-30 minutes.

Additive 2 is a compound that is activated at a temperature between 30 ℃ and 50 ℃. Additive 2 included thiophene, dioctyl sodium sulfosuccinate, alcohol, fatty alcohol (long chain alcohol) C12-18 (even number), and ethoxylate.

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

The addition of additive 2 to leather sheet 1 increases the uniform elasticity of leather sheet 1 over each portion of the geometric area where pressure is applied.

The additive 2 must be spread evenly on the flesh side 1a of the leather piece. The additive 2 can be coated by a spray coater or a roller coater; otherwise, the application agent 2 may be applied manually with a sponge or roller. In order to allow the additive 2 to penetrate into the leather sheet 1 at the correct depth without wetting the textured side 1b of the leather, an average dosage of 300 to 500g/m is used, depending on the characteristics of the leather and the result to be obtained²The additive of (1).

Fig. 3 shows a roll coater wherein a leather sheet 1 is delivered between a first counter-rotating roll R1 and a second counter-rotating roll R2 with the flesh side 1a of the leather sheet facing the first roll R1. Additive 2 contained in tank V is used to wet first roll R1.

Referring to fig. 4, when the leather sheet 1 is treated with the additive 2 and completely dried, the leather sheet 1 is disposed on the molding profile 4(shape), and the flesh side 1a of the leather sheet is placed on the profile 4. The profile 4 can be chosen according to the shape to be imparted to the leather sheet. Alternatively, the profile 4 may comprise directly a structure on which a piece of leather is suitable to adhere in order to coat said structure with leather.

The tensioning and fixing elements 5 can be applied to the areas of the leather sheet 1 where the level of deformation and stretching is the highest, in order to reproduce the concave and/or convex geometry of the profiles 4 and avoid the formation of wrinkles and creases.

The film 60 is applied on the textured side 1b of the leather sheet 1 to uniformly apply a uniform pressure. The film 60 must be made of a soft, elastic material so as not to press the textured side 1b of the leather, not to flatten and polish the finish (finishing) of the textured side, and to maintain the original grain pattern of the textured side 1b of the leather.

Referring to fig. 5, after the leather sheet 1 is placed on the profile 4, the leather sheet 1 and the profile 4 are inserted into the vacuum bag 6, and the vacuum bag 6 generates the film 60, and the film 60 is distributed on the textured surface 1b of the leather sheet. The vacuum bag 6 is sealed and connected to a vacuumAnd a pump 61. Air is drawn from the vacuum bag 6 by the pump 61 so that the flesh side 1a of the leather is in intimate contact with the profile 4 without compressing the leather sheet. In summary, the leather pieces and the profiles 4 do not change their position in the subsequent processing steps. A Rough Vacuum (RV) was applied during this step: 1X 10⁵Pa–1×10₂Pa. The rough vacuum is sufficient to adhere the leather sheet to the profile.

Referring to fig. 6, a vacuum bag 6 having a profile 4 and a leather sheet 1 is inserted into a hot chamber 7 heated at a temperature of 40-75 ℃. Such a hot chamber 7 can be ventilated. Depending on the size and thickness of the leather sheet 1 and the profile 4, the vacuum bag 6 with the profile 4 and the leather sheet 1 is kept in the hot chamber 7 for 3-10 minutes, so that the leather sheet reaches a uniform temperature of about 50 ℃. The additive 2 is activated at a temperature of 40 ℃ to 50 ℃ and the deformability of the leather sheet is increased.

It must be considered that the process according to the invention is carried out at a low temperature (about 50 ℃), i.e. at a temperature substantially lower than that of the leather sheet 1, so as to form a texture on the textured side 1 b. Thus, the leather does not change significantly in the area of maximum deformation and/or stretching as it occurs in the thermoforming process, wherein the leather is in contact with a hard surface (e.g., a heated aluminum or steel surface of a mold half).

Vacuum is applied to the vacuum bag 6 and air is gradually evacuated by means of the vacuum pump 61, so that the leather sheet 1 is gradually pressed onto the profile 4 until the desired shape is reached. In this step, a High Vacuum (HV) may be gradually reached: 1X 10^-1Pa–1×10^{- 5}Pa。

When the desired deformation of the leather sheet 1 is achieved, the vacuum bag 6 is removed from the hot chamber, and the vacuum pressure in the vacuum bag 6 is maintained.

The vacuum bag 6 with the profile 4 and the leather sheet 1 is cooled in a fresh air or ventilated environment until the leather sheet 1 reaches a temperature of 25 c. When the temperature of the leather sheet reaches 25 ℃, the vacuum bag 6 is opened and the profile 4 and the leather sheet 1 are removed.

The use of the vacuum bag 6 allows to apply a uniform pressure to all surfaces of the leather sheet 1 in any direction without limiting the mold closing direction that occurs in the thermoforming process according to the prior art. In view of the above, it is also possible to reproduce undercuts or reliefs on the sides of the profile 4 without using any transverse movement of the profile or any special automation.

The leather sheet 1 can now be separated from the profile 4. The leather sheet 1 has taken the form of its pressed profile 4, retaining the geometry and the original elasticity and flexibility.

With reference to fig. 7, according to a variant of the method of the invention, an adhesive 8 is applied to the flesh side 1a of the leather sheet before the leather sheet 1 is arranged on the profile 4. This type of adhesive is a water-based adhesive that is activated at temperatures above 70 ℃.

After the adhesive 8 has dried, the leather sheet 1 is placed on the profile 4 and the profile 4 with the leather sheet 1 is placed in a vacuum bag 6. Considering that the vacuum forming process is performed at a leather sheet temperature of about 50 c, the adhesive 8 is not activated, and thus, when the process is completed, the leather sheet 1 can be separated from the profile 4 because no adhesion is obtained. When leather sheet 1 must be secured to a support structure, it is only necessary to heat such leather sheet at a temperature equal to the activation temperature of adhesive 8, so that the leather sheet adheres to the support structure.

For illustrative purposes, fig. 8 illustrates a three-dimensional leather product 9 obtained with the process of the invention.

As shown in fig. 8, the texture of the leather textured side was not changed; furthermore, a plurality of concave or undercut lateral portions of the three-dimensional leather product 9 are obtained, which cannot be obtained by thermoforming processes.