CH715042B1 - Composite material based on natural material containing scleroproteins. - Google Patents

Abstract

The invention relates to a composite material based on particles of a natural material containing scleroproteins, in particular horn or leather. These particles are dispersed in a matrix of a thermoplastic polymer selected from polyamide 11 and polyether-block-amides. A process for preparing this composite material comprises mixing said particles and said thermoplastic polymer and shaping this mixture.

Description

The present invention falls within the field of the development of renewable natural resources, in particular protein residues of animal origin.

More particularly, the present invention relates to a composite material based on particles of a natural material containing scleroproteins and a thermoplastic polymer, as well as a process for preparing such a composite material. The invention also relates to the use of such a composite material for the manufacture of an article made of composite material, as well as such an article made of composite material.

[0003] The programmed depletion of fossil resources has for several years encouraged manufacturers to develop replacement solutions using renewable resources, in all areas of industry. Recycling and recovery of waste of animal or plant origin are therefore of growing interest, both from an economic and an environmental point of view.

[0004] It has thus for example been proposed by the prior art to manufacture composite materials from waste of animal origin and from polymer. Examples of such composite materials, based on a keratin material, are described in document US 2006/0084728.

The mechanical properties of such composite materials are however very unequal, and obtaining them, as well as their use for the manufacture of molded articles, often poses problems.

The present invention aims to provide a composite material based on particles of a natural material, in particular of animal origin, and of polymer, which has good mechanical properties, in particular in terms of both mechanical strength and which can easily, and with good reliability and good reproducibility, both be prepared and be used for the manufacture of molded articles, by means of hot forming techniques commonly used in industry.

[0007] An additional object of the invention is for this composite material to be entirely, or almost entirely, of natural origin. In particular, the invention aims for this composite material to contain a quantity by weight of less than 25%, and even less, for example less than 5%, of components which are not biobased.

[0008] It has been discovered by the present inventors that such objectives are achieved by a combined choice of a particular type of natural material, natural materials containing scleroproteins, and specific thermoplastic elastomers.

[0009] Scleroproteins, otherwise called fibrous proteins, constitute one of the three main classes of animal proteins. These are long molecules in the form of filaments, playing a structural and constitutive role in the organism, and entering into the composition of so-called supporting tissues, such as bones, antlers and connective tissues, as well as appendages, such as skin, hair, horns, hooves, and nails, and in ivory. There are different types: keratins, which form the body's protective tissues, such as the epidermis, hair, nails, hooves, horns or feathers of birds; collagens, which constitute connective tissues, such as cartilage; conchiolin, which forms the shells of molluscs, for example oysters; and elastins, also present in connective tissues.

[0010] Many industrial wastes from animal husbandry, such as horn, feathers, leather, or production scrap, such as scraps generated during leather working or horn working, etc., are mainly made up of scleroproteins. The use of this waste for the manufacture of articles in composite material, intended for multiple and varied applications taking advantage of the aesthetic and mechanical properties of these natural materials, proposed by the present invention, allows a quite interesting recovery, both economically and environmentally.

In the present description, the term “natural material” means a material of natural origin, as opposed to synthetic materials, such as a material of animal origin.

According to a first aspect, the present invention relates to a composite material based on particles of a natural material containing scleroproteins, these particles being dispersed in a matrix of a thermoplastic polymer. This thermoplastic polymer is chosen from polyamide 11 and polyether-block-amides, or any one of their mixtures.

[0013] In the present description, the term "natural material" encompasses both a single natural material and a mixture of several different natural materials, each of them containing scleroproteins.

[0014] Preferably, the natural material used contains more than 50% by weight of scleroproteins. This is the case for the majority of natural materials of animal origin based on scleroproteins: the scleroproteins are often substantially the only type of proteins present therein.

Polyamide 11, commonly designated by the abbreviation PA11, is a special thermoplastic polymer obtained by polycondensation of a C11 amino acid, 11-aminoundecanoic acid. This polymer has many advantages, in particular that of a biosourced origin, 11-aminoundecanoic acid being able to be extracted from a plant, Ricinus communus, also known under the name of common castor bean.

[0016] Such a polymer is in particular commercially available, for example sold under the name Rislan® PA11 by the company Arkema.

Polyether-block-amides, commonly designated by the abbreviation PEBA, are thermoplastic block copolymers comprising one or more flexible polyether blocks, and one or more polyamide blocks, which also have the advantage of being able to be obtained at least partially from renewable resources.

The polyamide blocks preferably comprise at least one polyamide block chosen from PA6, PA12 and PA11, PA11 being particularly preferred in the context of the invention.

The polyether blocks themselves preferably comprise at least one polyether block chosen from poly(ethylene oxide), polyethylene glycols, polytetramethylene glycols and poly(tetramethylene oxide).

The polyether-block-amides used in the context of the invention may contain any percentage by weight of polyamide block(s) and polyether block(s), the copolymer being all the more flexible as its percentage by weight of polyether block(s) is high.

[0021] The polyether-block-amides used according to the invention are also preferably UV-stabilized.

[0022] Such polymers are in particular commercially available, for example sold under the name PEBAX® by the company Arkema.

In particular embodiments of the invention, the thermoplastic polymer is a polyether-block-amide chosen from PEBAX® grade 35R53 or grade 25R53, these grades defining the Shore D hardness of the copolymer (equal to 35 for grade 35R53 and 25 for grade 25R53).

[0024] The particular thermoplastic polymers chosen according to the invention to enter into the composition of the composite material have the particular advantage of being able to be used in a wide range of processes for shaping materials, and in a wide range of temperature. They make it possible to prepare and shape composite materials in accordance with the invention in a particularly reliable, controlled and reproducible manner, including when the particles of the natural material are highly hygroscopic.

[0025] It has also been discovered by the present inventors that the composite material according to the invention, incorporating such thermoplastic polymers, has good mechanical strength, which is particularly good, its mechanical properties having good stability over time, including when is exposed to a humid environment.

The composite materials in which the thermoplastic polymer is a PEBA also have good flexibility, with a degree of flexibility which can advantageously be controlled in a particularly reliable and reproducible manner by an adequate choice of the particular copolymer used, in particular of the weight ratio between its polyether sequences and its polyamide sequences, its proportion in the mixture and the particle size of the particulate natural material.

The composite material according to the invention also has a good aesthetic appearance, close to that of the natural material, its composition is homogeneous and it is advantageously stable, both physically and aesthetically. The feel to its touch is also advantageously close to that of the natural material.

The above properties make the composite material according to the invention quite suitable for use in a wide range of applications.

The natural material containing scleroproteins entering into the composition of the composite material according to the invention is for example of non-human animal origin.

[0030] In particular embodiments of the invention, this natural material is chosen from horn, leather, wood and ivory of non-human animals, shells, and any of their mixtures.

[0031] It may otherwise consist of the wool, hoof, hair or feathers of non-human animals.

The scleroproteins which are contained in the natural material forming part of the constitution of the composite material according to the invention are for example essentially keratinous scleroproteins.

Preferably, the composite material according to the invention contains from 30 to 60%, in particular from 30 to 55%, by weight of particles of said natural material, relative to the total weight of said composite material. Such a range of values advantageously ensures properties to the touch close to those of the natural material, as well as an aesthetic appearance very close to that of the natural material.

The composite material according to the invention may also contain one or more additives, chosen according to the final properties desired for this composite material. Non-limiting examples of such additives are plasticizers, coupling agents, dyes, pigments, etc.

Preferably, these additives are present in the composite material in an amount of less than 10% by weight, preferably less than 5% by weight, relative to the total weight of the composite material.

The particles of natural material present in the composite material according to the invention preferably have dimensions of between 100 and 500 μm.

According to another aspect, the present invention relates to a method for preparing a composite material according to the invention, this material meeting one or more of the characteristics described above.

This preparation process comprises a step of mixing particles of natural material containing scleroproteins and thermoplastic polymer, chosen from PA11, PEBAs and mixtures thereof.

This mixture is preferably produced by compounding (also referred to by the term "intimate mixture"), that is to say by mixing at a temperature above the melting point of the thermoplastic polymer, and if necessary cooling . It falls within the competence of a person skilled in the art to determine this melting temperature, in particular by differential enthalpy analysis (commonly designated by the abbreviation DSC, for English Differential Scanning Calorimetry). This melting temperature is also generally indicated by the suppliers of commercially available thermoplastic polymers.

[0040] The temperature applied for the mixing step is also preferably lower than the degradation temperature of the natural material. Here again, it falls within the skills of a person skilled in the art to determine the degradation temperature of the natural material used. To this end, the person skilled in the art may in particular carry out a thermogravimetric analysis (TGA) of a sample of the natural material, in a conventional manner per se.

The mixing, if necessary the compounding, of the particles of the natural material containing scleroproteins and of the thermoplastic polymer, can be carried out according to any conventional method in itself for those skilled in the art. It can in particular be produced by extrusion, for example by means of an extruder, for example single- or twin-screw, or an internal mixer, according to conventional operating parameters.

In particular embodiments of the invention, the particles of the natural material have dimensions between 20 and 500 μm, preferably between 100 and 500 μm. This means that all their dimensions are included in these size ranges.

[0043]Preferentially, these particles have good uniformity of size, as well as preferably good uniformity of shape, which it is in particular possible to ascertain by observation under an electron microscope.

The natural material in particulate form containing scleroproteins used in the method according to the invention preferably has a moisture content of between 0 and 20%, for example approximately 12%.

We define here the moisture content, in a conventional way in itself, as the percentage by mass of water contained in the material, relative to the total mass of material, under conditions of 60% of relative air humidity and at around 20°C. This humidity level can in particular be determined by comparing the weight of a sample of material with the weight of this same sample after it has been subjected to a drying step at more than 100° C. until a weight is obtained. of the substantially constant sample.

Where appropriate, the method according to the invention may comprise, prior to the step of mixing the particles of the natural material and the thermoplastic polymer, a preliminary step of drying the natural material used, to obtain the desired humidity level. This drying step can be carried out in a suitable device that is conventional in itself, for example in a ventilated oven. It is within the competence of a person skilled in the art to determine the appropriate temperature and drying time to obtain the desired humidity level.

The process for preparing a composite material according to the invention may also comprise initial stages of cleaning, sorting and/or degreasing of the natural material, as well as, where appropriate, a prior stage of grinding this natural material so as to ensure that it is in a particulate form, and if necessary at the desired particle size.

During or after the step of mixing the particles of the natural material and the thermoplastic polymer, various additives, in particular one or more plasticizing agent(s), one or more agent(s) coupling, one or more dye(s), pigment(s), etc., can be incorporated into the mixture.

In particularly preferred embodiments of the invention, the process for preparing a composite material comprises a shaping step, in a shaping device, of the material obtained at the step of mixing the particles of the natural material and of the thermoplastic polymer.

[0050] This shaping step can be carried out according to any conventional method per se for those skilled in the art, in particular by injection, extrusion, molding, compression molding, injection-blow molding, etc.

The shaping device is also conventional in itself.

The shaping is preferably carried out at a temperature above the melting point of the thermoplastic polymer, and preferably below the degradation temperature of the natural material used.

In particularly advantageous embodiments of the invention, the step of mixing the particles of the natural material and of the thermoplastic polymer is carried out directly in the shaping device, in which are therefore carried out at the both the preparation of the composite material, and its shaping.

Advantageously, according to the invention, from the initial ingredients, a composite material is obtained directly shaped, in the form of an article made of composite material, in particular a molded article, of the desired shape.

The method according to the invention is thus advantageously simple and quick to implement.

The preparation of the composite material according to the invention can for example be carried out by injection molding, for example by means of an extruder, in particular a twin-screw extruder.

[0057] By way of example, a process for preparing a composite material according to the invention can be carried out by injection molding, by means of an extruder, with an extrusion temperature profile, for example, between 90 and 210° C. for the particular case of a mixture of cow horn particles and PA11.

The preparation process according to the invention may otherwise comprise the mixing by kneading of particles of the natural material and of the thermoplastic polymer, then compression molding, at a temperature between the melting temperature of the polymer and the temperature of degradation of natural material. For example, for the aforementioned particular case of particles of cow horn and PA11, the conditions applied in the mold can be 198° C. under a pressure of less than 10 MPa, for approximately 15 minutes.

According to another aspect, the present invention also relates to the use of a composite material according to the invention, corresponding to one or more of the above characteristics, for the manufacture of an article made of composite material, in particular by shaping said composite material, as described above.

The invention also relates to an article made of composite material made of a composite material according to the invention, in particular a molded article.

[0061] This article can for example be an accessory or small fashion accessory, an article of leather goods, jewelry, watches, tableware and the art of living, in the field of packaging. , decoration, etc.

Another aspect of the invention is a more general process for manufacturing an article made of composite material, comprising the preparation of a composite material in accordance with the invention and the shaping of this composite material, at the desired shape.

The composite material according to the invention can initially be shaped into a form suitable for storage, for example in the form of granules, then, in a second step, it can be shaped to form the article according to the invention, to the final shape desired for this article.

The characteristics and advantages of the invention will appear more clearly in the light of the examples of implementation below, provided purely by way of illustration and in no way limiting the invention.

Materials and methods

The polymers used for these examples are as follows: Rislan® PA11 T natural 2P from Arkema, melting point 183-188° C. (measured according to the ISO 1218 standard) Pebax® 35R53 SP 01 from Arkema, melting temperature 135°C (measured according to ISO 11357) Pebax® Rnew 35R53 SP 01 from Arkema, melting temperature 136°C (measured according to ISO 11357)

In the examples below, the extrusion operations are carried out in a Clextral EV25 twin-screw extruder with the following parameters: screw rotation speed: 220 rpm material flow rate: 1.4 kg/h average extruder torque: 22 N.m average pressure in the extrusion die: 11 bar

The injection operations are carried out in the same device, also with the above operating parameters.

For each experiment below, a temperature profile is applied in the extruder, between the feed hopper and the extrusion die, the minimum value and the maximum value of which are indicated for each experiment.

In all the examples below, granules are formed by extrusion of a mixture of polymer and natural material, then these granules are subjected to injection molding.

Example 1 - Bovine horn and PA11

Compounding by extrusion-granulation of the following substances is carried out, in the following percentages by weight: particles of bovine horn of Aubrac and Salers origin, crushed and micronised, with a particle size of 250 µm (degradation temperature between 210 and 230°C) 42% w/w PA11 54.5% w/w Citrofol® AHII (biobased plasticizer) 1.5% w/w carbon black ENSACO® 250G 2% w/w by extrusion with an extrusion temperature profile between 90 and 200°C.

A composite material of black color is obtained, shaped in the form of granules, approximately 0.5 mm in diameter and 0.5 mm thick.

These granules are introduced into an injection molding unit, comprising the twin-screw extruder described above.

The temperature profile applied in the extruder is between 180 and 200°C. The mold temperature is maintained at 60°C.

[0074] A homogeneous part is obtained, with a Shore D hardness of approximately 70-80, with good dimensional stability.

Example 2 - Bovine horn and PA11

The compounding of the following substances is carried out, in the following percentages by weight: particles of bovine horn of Aubrac and Salers origin, crushed and micronized, with a particle size of 250 μm (degradation temperature between 210 and 230° C.) 31 .5% w/w PA11 65% w/w Citrofol® AHII (biobased plasticizer) 1.5% w/w titanium dioxide (TiO2) 2% w/w

The operating conditions used are as described in Example 1 above.

[0077] A homogeneous part is obtained with a blond-chestnut tint, of dimensions 148×105 mm. Its properties are similar to those of the part obtained in Example 1, with good dimensional stability. The exterior finish is matte and uniform.

Example 3 - Mammoth ivory crust and PA11

The following substances are compounded, in the following weight percentages: mammoth fossil ivory crust powder from Siberia, with a particle size of 303 μm 50% w/w PA11 50% w/w

The operating conditions used are as described in Example 1 above, with the exception of the injection molding step, for which the injection temperature profile is between 180 and 210 °C and the mold temperature is 130°C.

[0080] A piece of dimensions 60×60×4 mm is obtained, with a dark shade verging on brown, with a granitic effect due to the composition of mammoth ivory. This part has good dimensional stability.

Example 4 - antler and PA11

[0081] Compounding of the following substances is carried out, in the following percentages by weight: deer antler powder, with a particle size of 303 μm 30, 40 or 50% w/w PA11 qsp 100% w/w

The operating conditions used are as described in Example 1 above, with the exception of the injection molding step, for which the injection temperature profile is between 180 and 210 °C and the mold temperature is 130°C.

[0083] For each of the 3 mixtures tested, a piece of dimensions 60x60x4 mm is obtained, of smooth appearance, of beige/green color which is accentuated all the more as the composite materials are more loaded with deer antler particles. . This part has good dimensional stability.

Example 5 - oyster shell and PA11

The following substances are compounded, in the following percentages by weight: oyster shell powder originating from the Thau basin, with a particle size of 280 μm 30, 40 or 50% w/w PA11 qsp 100% p/p

The operating conditions used are as described in Example 1 above, with the exception of the injection molding step, for which the injection temperature profile is between 190 and 210 °C and the mold temperature is 110 °C.

For each of the 3 mixtures tested, an off-white/beige colored part is obtained, all the darker as the composite materials are more loaded with oyster shell particles. The rendering is not homogeneous, a grainy effect is visible, due to the granulometry of the filler. This part has good dimensional stability.

Example 6 - soft leather and PEBA

[0087] Compounding of the following substances is carried out, in the following percentages by weight: Dust from shaving orange ovine leather, with a grain size of 157 μm 30, 40 or 50% w/w Pebax® Rnew 35R53 SP 01 qsp 100% w/w

The operating conditions used are as described in Example 1 above, with the exception of the temperature profile at the extrusion stage, which is between 150 and 190° C., and at except for the injection molding step, for which the injection temperature profile is between 170 and 190°C and the mold temperature is 40°C.

For each of the 3 mixtures tested, a flexible piece of dark brown color is obtained, all the darker as the composite materials are more loaded with leather particles.

Example 7 - soft leather and PEBA

[0090] Compounding of the following substances is carried out, in the following percentages by weight: Dust from shaving orange ovine leather, with a grain size of 157 μm 40 or 50% w/w Pebax® 35R53 SP 01 qsp 100% p/p

The operating conditions used are as described in Example 1 above, with the exception of the temperature profile at the extrusion stage, which is between 150 and 190° C., and at except for the injection molding step, for which the injection temperature profile is between 135 and 190°C and the mold temperature is 40°C.

For each of the 2 mixtures tested, a flexible piece of dark brown color is obtained, all the darker as the composite materials are more loaded with leather particles.

Example 8 - soft leather and PEBA

[0093] Compounding of the following substances is carried out, in the following percentages by weight: full-grain calfskin powder, blue in color, with a grain size of 500 μm 40% w/w Pebax® 35R53 SP 01 60% w/w

The operating conditions used are as described in Example 1 above, with the exception of the temperature profile at the extrusion stage, which is between 130 and 160° C., and at except for the injection molding step, for which the injection temperature profile is between 130 and 160°C and the mold temperature is 40°C.

[0095] A piece of bluish green/turquoise color is obtained, of homogeneous appearance with stain effects, semi-rigid, with a Shore D hardness of approximately 50.

Example 9 - soft leather and PEBA

[0096] Compounding of the following substances is carried out, in the following percentages by weight: full-grain calfskin powder, blue in color, with a grain size of 250 μm 40% w/w Pebax® 35R53 SP 01 60% w/w

The operating conditions used are as described in Example 1 above, with the exception of the temperature profile at the extrusion stage, which is between 125 and 165° C., and at except for the injection molding step, for which the injection temperature profile is between 175 and 190°C and the mold temperature is 50°C.

[0098] A piece of bluish green/turquoise color is obtained, of homogeneous appearance with spot effects. Its shore D hardness is around 30.

[0099] Indication of sources of genetic resources according to article 49a LBI Oyster shell Thau basin, Hérault department, South-West region, France Deer antlers France Cattle horn Aubrac and Salers breeds, department of Aveyron, France Graulhet sheep leather, Tarn department, France Graulhet calf leather, Tarn department, France Mammoth ivory Siberian mammoth fossil ivory

Claims (10)

1. Composite material based on particles of a natural material containing scleroproteins, said particles being dispersed in a matrix of a thermoplastic polymer, characterized in that said thermoplastic polymer is chosen from polyamide 11 and polyether-block-amides , or any mixture thereof. 2. Composite material according to claim 1, wherein said scleroproteins are keratin proteins. 3. Composite material according to claim 1, in which said natural material is chosen from horn, leather, wood and ivory of non-human animals, shells, and any one of their mixtures. 4. Composite material according to any one of claims 1 to 3, containing from 30 to 55% by weight of said particles, relative to the total weight of said composite material. 5. Process for preparing a composite material according to any one of claims 1 to 4, characterized in that it comprises a step of mixing particles of said natural material containing scleroproteins and of said thermoplastic polymer. 6. Preparation process according to claim 5, according to which the particles of said natural material have dimensions of between 100 and 500 μm. 7. Preparation process according to any one of claims 5 to 6, comprising a shaping step, in a shaping device, of the material obtained in the step of mixing the particles of said natural material and said polymer . 8. Process of preparation according to any one of claims 5 to 7, according to which the step of mixing the particles of said natural material and of said polymer is carried out in said shaping device. 9. Use of a composite material according to any one of claims 1 to 4 for the manufacture of an article of composite material. 10. Composite material article made of composite material according to any one of claims 1 to 4.