IT202000031787A1 - PROCESS FOR THE PRODUCTION OF A BIO-BASED AND VEGAN LEATHERETTE MATERIAL - Google Patents

Description

TITLE

PRODUCTION PROCESS

OF A BIO-BASED AND VEGAN LEATHERETTE MATERIAL

DESCRIPTION

Field of Invention

The present invention generally relates to the material treatment sector, and more precisely it refers to a process with reduced environmental impact for the production of a bio-based and vegan leatherette material, i.e. derived completely or at least partially from renewable sources and free from materials of animal origin. The invention also concerns the material obtainable with this process, which is printable to give the appearance of natural leather and characterized by improved characteristics of mechanical strength and durability, useful for guaranteeing high quality? performance in a wide range of applications.

State of art

In the last few years ? Consumer demand for products of non-animal origin has increased not only in the food sector, but also in other sectors, including clothing, fashion accessories and footwear. Such products, free of animal-derived materials, are commonly classified as vegan or vegan. To these requests is often added the request for products with reduced environmental impact and the use of materials from renewable sources, which reduce the use of synthetic materials of fossil origin. Materials of this type, which are completely or at least partially derived from renewable sources, go by the name of bio-based materials.

To products made with such materials ? however, a pleasant aesthetic aspect is always required, the most? similar as possible to that of animal leather, to which the consumer is not? evidently willing to give up, and qualitative performance increasingly? high, in addition to a workability? and resistance more? or less depending on the application and intended use. In particular, in the case of synthetic leathers intended for the production of bags, shoes or other accessories, the physical and mechanical characteristics required of the material are particularly stringent, since the material must guarantee sufficient strength and resistance to be able to be sewn, for example, or in any case joined in portions of the same or different material, to make the finished product in the form of a bag, shoe, belt, and the like.

In order to aspire to obtain a material with these characteristics, the bio-based raw materials will obviously have to be selected with suitable sustainability characteristics. and be subjected to specific, suitable treatments which must in turn guarantee the desired ecology not only of the final product following the treatment, but also of the process itself and of the reagents and solvents used to create it. Sustainability? environmental impact of industrial productions? a new fundamental request to align with for every kind of production, with a view to countering environmental degradation and the destruction of natural ecosystems, as well as? to respect also the environmental regulations pi? stringent and ensure the health of people working at all stages of the production chain.

Several attempts have been made to date to meet the market demands illustrated above, but for how long? aware of the Applicant none of these ? completely satisfactory, ie it is configured as a material not of animal derivation but with the appearance of animal hide, with a reduced environmental impact and endowed with good strength and mechanical resistance.

Therefore, the need to have an ecological treatment process, with a reduced environmental impact, of sustainable raw materials, capable of supplying a high quality vegan material, endowed with the durability and resistance necessary to make it suitable for the It is used in the clothing, accessories and footwear sector, also having the softness to the touch and the aesthetic appearance of animal leather.

Summary of the Invention

Now the Applicant has found a production process of imitation leather with a reduced environmental impact described below which, by treating a bio-based polyurethane coagulate made from sustainable sources with a reduced environmental impact, allows to obtain a durable and mechanically resistant material, all analogous to a natural leather both in terms of softness to the touch and in terms of surface appearance once printed.

Advantageously, the production process of this invention provides for a limited use of chemical products and water, significantly less than that found in the treatment of animal hides. In particular, the process of this invention ? free from chromium or other metal treatments, and all the chemical products used comply with the MRSL (Manufacturing Restricted Substance List) ZDHC (Zero Discharge of Hazardous Chemicals) which limits the use of dangerous chemical substances in production processes.

Therefore, an object of the present invention is a production process of a bio-based leatherette material, as defined in the first of the appended claims.

A bio-based leatherette material obtainable from this process, its use as a substitute for animal skin and an article made therewith, as defined in the respective independent claims annexed hereto, represent a further object of the present invention.

Other important characteristics of the production process of a bio-based leatherette material, of the material so? obtained and its use, as well as? articles made with the material according to the invention are given in the following detailed description.

Brief description of the drawings

Figure 1a shows an intact sample of the material of the present invention after dry strength tests described in Example 1 below.

Figure 1b shows an intact sample of the material of the present invention after wet strength tests described in Example 1 below.

Figure 1c (comparison) shows a degraded sample of material not treated with the process of the present invention after dry strength tests described in Example 2 below.

Figure 1d (comparison) shows a degraded sample of material not treated with the process of the present invention after wet strength tests described in Example 2 below.

Detailed description of the invention

In the following description, unless otherwise specified, the percentage quantities are expressed as percentages by weight with respect to the total weight of the composition comprising them.

The Applicant has found that by treating a bio-based polyurethane coagulate with synthetic tannins in water and applying on the surface treated with a polyurethane adhesive, the coagulated acquires characteristics of high mechanical resistance, improved compared to the starting product, and a much greater stability? and durability over time, offering a soft and flexible surface which, after printing, is completely similar to that of natural leather.

Within the scope of the present invention, the term ?bio-based? means ?completely or at least partially derived from renewable sources?.

Furthermore, with the expression ?bio-based polyurethane coagulate? here we mean a product obtained by coagulation of polyurethane obtained from renewable sources on a fabric or non-woven fabric support. Various methods for preparing these materials have been known for decades; in this invention the preferred starting materials are the polyurethane coagulates prepared by directly coating the support with polyurethane in water. The support of the present polyurethane coagulate can? be, for example, made with a fabric in natural and/or artificial fibers on which? polyurethane was applied for coagulation. Preferably, these natural and/or artificial fibers are selected from linen, cotton, hemp, viscose, and their blends. Among these, favorite? viscose, classifiable as an artificial fiber as it is of natural origin from cellulose, but obtained by chemical and mechanical processing of cellulose. According to the FSC (Forest Stewardship Council) certification system, the cellulose comes from responsibly managed forests.

With the term ?vegan or vegan? as used herein we mean ?free from materials of animal origin?.

In one aspect of the process of this invention, the starting polyurethane coagulate is a bio-based polyurethane coagulate on viscose fabric, essentially consisting of polyurethane obtained from renewable sources and viscose, for example consisting of about 30% viscose and about 70% polyurethane.

With the term ?synthetic tannins? in this invention tannic acid derivatives of synthetic origin are meant which are substitution tannins with reduced environmental impact selected for example from phenolic, arylsulphonic, hydroxyarylsulphonic, dihydroxydiphenylsulphonic derivatives, and their mixtures or condensation products; according to this invention with the term ?synthetic tannins? are preferably meant arylsulphonic and hydroxyarylsulphonic derivatives, and more? preferably methylene bonded condensation products of arylsulfonic and hydroxyarylsulfonic acids.

The production process of an imitation leather material from renewable sources and not of animal origin of this invention, free of treatments with chromium and other metals and with a reduced environmental impact, includes the phases of:

i) wetting a polyurethane coagulate in a drum with water;

ii) treatment of said coagulated product with synthetic tannins by adding them to the drum;

iii) drying and spray and/or roller application of a polyurethane adhesive agent.

The wetting of the coagulated with water in phase i) of this process ? carried out for the time necessary to completely and uniformly wet the coagulated tissue, for example for about 30 minutes. In one aspect of this invention, the amount of water used? of about 200 liters every 10 meters of treated coagulated having a width of about 1.5 meters, a quantity? much lower than that usually used in tanning treatments. Furthermore, the temperature in this phase? preferably the environment one and no other water additives are used, such as for example surfactants, with a view to realizing a process with reduced environmental impact in all its aspects and in the various phases.

Advantageously, in the present process, phase ii) of treatment with synthetic tannins can be carried out without draining the water from the drum, but simply adding the powdered tannins to the drum at the end of the wetting, for example in a quantity equal to about 6% by weight with respect to the dry weight of the coagulated to be treated, and leaving the material in the bath for about 30 minutes. In one aspect of the process the pH of this phase ii) ? brought to a pH of between 5 and 6, preferably about a pH of about 5.2.

If you want to obtain a material with a particular colour, after treatment with tannins, this process can optionally include a dyeing phase that can be advantageously carried out in the same drum, without discharging the aqueous solution coming from phase ii), adding one or more? dyeing agents, preferably selected from azo dyes. Optimal results in terms of durability and solidity of the colors on the material of the invention have in fact been observed using this type of dyes in combination with the treatment with synthetic tannins described above.

In a particular embodiment of the process of the invention, after the treatment with tannins in phase ii), or after the dyeing phase if present, before extracting the treated material from the drum and drying it, one or more dyeing operations are carried out. fixing operations by adding a fixing agent, typically formic acid. This treatment causes a lowering of the pH which assists in the fixing of the treatment products within the material.

In phase iii) of this process the drying of the material can be carried out with any drying method suitable for the purpose, under conditions which any expert in the sector could identify on the basis of his ordinary knowledge. In a preferred aspect of the present process, the panels of the material unloaded from the drum after the treatment step with tannins or after the coloring step, if present, are dried at room temperature by setting out in the suitable tanning machinery; in this way, in fact, about 90% of the water is removed from the material, without having to provide for heating as usually occurs for the drying of these materials. Optionally, in order to quickly and completely remove the last part of the remaining water, in this phase the panels of the material can be subjected to forced drying, for example at a temperature of about 45°C. An effective way? of forced drying pu? for example, be made as in the traditional drying of animal hides using a catenary, or by placing the material to be dried in air suspension on special chains to allow it to disperse the last moisture residual present inside the material.

Once dried, in step iii) of the present process a polyurethane adhesive agent is applied to the material by spray application or, preferably, by roller, until a uniform layer is created on the material. In a preferred embodiment of the present process, the polyurethane bonding agent is an aliphatic polyurethane adhesive; the agents of this family have in fact been identified by the inventors as the most? performing to achieve the desired and necessary adhesion of the subsequent finishing layers that will be subsequently applied.

In a particular embodiment, before and/or after the application of the polyurethane adhesive agent, the present process provides for the application on the dry material, by spray and/or roller, of an anti-dusting agent, chosen for example from the agents water-based acrylics/polyurethanes commonly used in tanning finishing processes.

In one embodiment of the invention, the present process can also include one or more finishing phases with chemical or mechanical means, to obtain the desired visual or tactile effect; and/or a step of printing the material according to a desired design, for example with engraving plates or leather printing machines. Both l? One or more? both the finishing phases and the printing phase can be carried out according to the methods? and with the machinery and reagents commonly used in the treatment of animal hides. The inventors have been able to verify that these finishing and/or printing phases carried out on the material of the invention, first treated with tannins and with the polyurethane adhesive, result in a particularly attractive finished product and similar in appearance and touch to animal hides .

Most of the process steps of this invention can be advantageously carried out at room temperature, for example around about 20°C, without any expenditure of energy for heating, thus also contributing in this way to the sustainability of the process. environmental. Furthermore, the only solvent used in the process of the invention in quantity significant, however inferior to the quantities? used in known processes, ? l? water, and the pH contrary to known processes? maintained at values not too far from neutrality.

The bio-based leatherette material obtained with the process described above and also the object of the invention, can be used as a substitute for animal hides in any sector, to decorate or make clothing and accessories, including bags and footwear, but also to cover design objects and furnishings or the interior of cars.

The advantages associated with the present invention are manifold. First, the material resulting from the manufacturing process of this invention is particularly attractive in appearance once printed and soft to the touch, completely similar to animal leather despite not having any animal derivation and therefore being a vegan material.

How already? mentioned above, all the phases of the process of the invention are also carried out in conditions of reduced environmental impact, using non-toxic and non-toxic reagents and solvents. and environmentally sustainable temperature and energy consumption conditions. In particular, the present process does not use the metal salts, chromium in particular, of the traditional tanning processes, resulting in a finished material which can be metal-free and chrome-free.

Furthermore, the material obtainable with the process of this invention has acquired properties much better mechanics than those of the starting coagulate, so much so that with the material of this invention ? It was possible to make complex items such as bags and shoes by sewing parts of material cut according to patterns. Pi? in general, for polyurethane coagulates, this process has the surprising effect of improving their functional and performance characteristics, resulting in a finished material that is highly performing from a physical and mechanical point of view, extremely durable and stable over time, even in terms of colouring. Thanks to these characteristics, the material is so? obtained potr? be used successfully not only in the fashion sector, in particular to create and/or decorate garments and leather goods, but also in the furniture and design sector, and in any other related sector.

A further advantage of the process of this invention lies in its simplicity, cost-effectiveness and and in the fact that each phase that composes it can be carried out using pre-existing machinery and systems used up to now for the tanning treatments of animal hides.

The invention? described below by means of examples without however being limited to them, but? it means that you can vary the quantities? and percentages of the reagents described, cos? as the type of reactors and more? in general of conditions employed while remaining within the scope of the present invention.

Example 1

Panels of dimensions 100 cm x 145 cm of polyurethane and viscose coagulate were inserted into a tanning drum and kept for about 30 minutes in a water bath at 20°C, adding 200 liters to the drum for every 10 panels of material.

Without discharging water and always at a temperature of 20°C, powdered synthetic tannins were added to the drum, i.e. a methylene bonded condensation product of arylsulphonic and hydroxyarylsulphonic acids in the amount of 16% by weight on the weight of the coagulated panels starting from treat, and the material ? was maintained in this treatment bath for about 30 minutes at a solution pH of about 5.2. Yup ? then added an azo dye in the amount of 20% by weight and kept the material in this dye bath for about 30 minutes.

At the end of the dye? Was formic acid added to the drum in three installments to fix the previous treatments, in a first phase of 4 hours? 12% formic acid was added, in a second phase of 30 minutes 4% formic acid and in a third phase of a further 30 minutes 4% formic acid.

The material what? treaty ? extracted from the drum and dried at room temperature by setting out in a special machine generally used in leather tanning, then the panels obtained from this first drying were attached in a catenary and subjected to forced drying at 45°C.

On dry material? a layer of aliphatic polyurethane adhesive in solvent was spread with a roller which allows the fusion of the treated base for subsequent finishing applications. With a roller and spray machine were then applied more? layers of water-based polyurethane acrylic finishing, before passing the material to print a design in a hot plate printing machine.

The material what? obtained it appeared soft to the touch, with an appearance completely similar to that of a leather tanned from animal hides. Furthermore, this material had better mechanical resistance performances, evaluated by the inventors in particular as resistance to bending in the following experimental tests.

A sample of the material of the invention treated as described above? been subjected to a flexural strength test using a ?Bally? according to the standard procedures described in the UNI EN ISO 5402-1:2017 standard with the following results: after 100,000 dry flexures the sample of this material did not show any sign of breakage (test result: PASS; Figure 1a), equally no sign breaking? was highlighted after 30,000 wet flexes (test result: PASS; Figure 2b).

Example 2 (COMPARISON)

The same starting polyurethane and viscose coagulate of Example 1 above, not treated with the process of the invention? been subjected to the same mechanical strength tests, in particular to bending strength tests using a ?Bally? according to the same standard procedures of the aforementioned Standard. Yeah? after 20,000 dry push-ups yes ? a very serious break in the material occurred (test result: FAIL; Figure 1c), while only 1,000 wet flexures caused a very serious peeling of the material (test result: FAIL; Figure 1d).

The material not treated with the process of this invention therefore does not have the necessary mechanical strength to be able to be used in a similar way to animal hides, and does not even possess suitable visual and tactile characteristics, how can one? also grasp from the images in the figures.

The present invention ? heretofore described with reference to a preferred embodiment thereof. ? it should be understood that there may exist other embodiments which pertain to the same inventive core, as defined by the scope of protection of the claims set forth below.

Claims (15)

1. Process for the production of a bio-based and vegan leatherette material, with a reduced environmental impact and free from treatments with metal salts, including the phases of: i) wetting a polyurethane coagulate from renewable sources in a drum with water; ii) treating said coagulated with synthetic tannins by adding them to said drum; iii) drying and spray and/or roller application of a polyurethane adhesive agent. 2. The process of claim 1, further comprising a coloring step with azo dyes between step ii) of treatment with tannins and step iii) of drying. 3. The process of any one of claims 1 or 2, further comprising a fixing step at acid pH between step ii) of treatment with tannins and step iii) of drying or, if present, immediately after the coloring step. 4. The process of any one of the preceding claims, wherein said polyurethane coagulate is a fabric in natural and/or artificial fibers on which? was applied polyurethane from renewable sources for coagulation. 5. The process of claim 4, wherein said natural and/or artificial fibers are selected from flax, cotton, hemp, viscose, and their blends. 6. The process of any one of the preceding claims, wherein said polyurethane coagulate essentially consists of viscose and polyurethane from renewable sources. 7. The process of any one of the preceding claims, wherein said synthetic tannins are substitution tannins with reduced environmental impact selected from phenolic, arylsulphonic, hydroxyarylsulphonic, dihydroxydiphenylsulphonic derivatives, and their mixtures or condensation products. 8. The process of claim 7, wherein said synthetic tannins are methylene bonded condensation products of arylsulfonic and hydroxyarylsulfonic acids. 9. The process of any preceding claim, wherein said polyurethane bonding agent is an aliphatic polyurethane adhesive. The process of any preceding claim, further comprising applying an anti-dusting agent, by spray and/or roller, to said material after drying and before and/or after applying said polyurethane bonding agent. 11. The process of claim 10 wherein said anti-dusting agent is chosen from acrylic/polyurethane agents. 12. The process of any one of the preceding claims, further comprising finishing and/or printing steps of the material coming from said drying step iii) and application of the adhesive agent. 13. A bio-based and vegan leatherette material obtainable with the production process of claims 1-12, said material being a polyurethane coagulate from renewable sources treated with said process and having the tactile and visual characteristics of animal leather and improved durability, solidity? color and mechanical strength compared to the starting polyurethane coagulate. 14. Use of a leatherette material as defined in claim 13 as a substitute for animal hide. 15. An article made, in whole or in part, of the imitation leather material as defined in claim 13.