FR3146686A1 - Biodegradable polymer for 3D printing - Google Patents

Abstract

Biodegradable polymer comprising at least one mixture of polyhydroxyalkanoates (PHA) and at least one extract of calcareous algae, in particular coralline algae. The invention relates to a biodegradable material comprising at least (1) a mixture of biodegradable polymers comprising at least one polyhydroxyalkanoate (PHA) having a high melting point greater than about 120 °C, and at least one polyhydroxyalkanoate (PHA) having a low melting point less than about 80 °C, and (2) at least one dehydrated calcareous algae and/or a dry non-water-soluble residue of calcareous algae. The invention also relates to a method for manufacturing such a material, its use for growing a marine coral, a filament for 3-dimensional (3D) printing comprising said material as well as a device for holding a coral cutting formed from said material. Figure for the abstract: /

Description

Biodegradable polymer for 3D printing

The invention relates to a biodegradable material comprising at least (1) a mixture of biodegradable polymers comprising a first polyhydroxyalkanoate (PHA) having a melting point of greater than or equal to about 120 °C (high melting point), and a second polyhydroxyalkanoate (PHA) having a melting point of less than or equal to about 80 °C (low melting point), and (2) at least one dehydrated calcareous algae and/or a dry non-water-soluble residue of calcareous algae. The invention also relates to a method of manufacturing a biodegradable material as well as the use of a biodegradable material for the growth of a marine coral.

The invention also relates to a filament for 3-dimensional (3D) printing comprising a biodegradable material according to the invention.

Furthermore, the invention relates to a device for holding a coral cutting comprising a biodegradable material or produced with a filament for 3D printing according to the invention. Such devices can be used in aquariums but also in a marine environment to allow the growth of corals from cuttings.

Finally, the present invention also relates to a method of manufacturing these devices from the biodegradable material or from a filament for 3D printing comprising the biodegradable polymer according to the invention.

Corals are a diverse group of anemone-like animals that live in marine environments. Corals include soft corals, hard corals, sponges, gorgonians, etc. Hard coral, a member of the cnidarian family, consists of several individuals, or polyps, that share a common skeleton, mostly composed of calcium carbonate. Together, these polyps and their skeletons form a colony.

Coral reefs are among the richest and most complex ecosystems in the world, offering incredible biodiversity. In fact, a single coral reef can be home to thousands of species: from corals to algae, clownfish and pufferfish to sharks and stingrays, with which they live in perfect symbiosis.

Mainly due to human activities such as dynamite fishing, mining of minerals in the construction sector, or the flow of polluted water, entire reefs have been destroyed. Corals must also face the consequences of global warming and carbon dioxide emissions which warm and acidify the oceans. Nearly half of them have disappeared in the last twenty years. However, coral grows very slowly, one to two centimeters per year for some species. Sometimes thousands of years are necessary to obtain a mature coral reef.

To help rebuild these reefs, many types of coral can be cultured asexually by propagation from fragments or cuttings. For example, a piece of living coral can be broken into smaller pieces or fragments. A fragment is then attached to a base or support. After cutting a fragment from a colony, the living tissue of this fragment, or cutting, made up of polyps, will heal and resume its development, producing a skeleton and new polyps, thus creating a new colony. Coral cuttings allow, in particular, the implantation of cuttings on reefs to help their natural regeneration, to avoid collecting corals from the wild for the sale of corals to aquarists, the development of corals in the laboratory for scientific studies and display to the public, and the collection of endangered species.

Artificial reefs using these cutting techniques exist, but are mostly built with polluting materials, such as plastics or concrete.

Indeed, plastics such as polyethylene terephthalate or polyvinyl chloride can release endocrine disruptors such as antimony trioxide or phthalates. In areas polluted by plastic, it has been observed that corals are more susceptible to the development of diseases. Contact between plastic debris and corals can cause injuries to coral tissues, thus promoting their infection by bacteria. In addition, certain additives present in plastics attract and promote the ingestion of plastic by coral polyps, increasing the risk of transmitting toxic elements to them while diverting them from the real foods necessary for their development and survival.

The support solutions for coral cuttings that exist today are difficult to produce with bio-sourced and biodegradable resources.

Furthermore, these supports, which are entirely synthetic, are not always compatible with good adhesion and therefore optimal growth of the coral.

Finally, as mentioned above, the manufacturing process of the media currently available on the market has a significant impact on the natural environment and the planet's resources.

Today, it is necessary to be able to rebuild coral reefs with materials and a design conducive to the reappearance of life.

There therefore remains a need to offer coral reef regeneration supports made from entirely bio-sourced and compostable and/or biodegradable products proven to have no harmful impact on either the marine environment or operators.

There is also a need for a material for preparing coral reef regeneration media that does not present or whose implementation does not generate or involve any agent that is potentially toxic to the environment or corals.

There is also a need for a material to prepare coral reef regeneration media that is suitable for holding cuttings or fragments from any type of coral, branching or massive, of varying sizes.

In particular, there remains a need to be able to ensure traceability of raw materials, notably through the exclusivity of the materials used and the implementation of a “simple” formulation.

There is also a need for a material for preparing coral reef regeneration media that is simple to produce.

Furthermore, there is a need for a material for preparing coral reef regeneration media that is inexpensive to produce.

Furthermore, there is a need for a material for preparing coral reef regeneration supports that can be implemented in different industrial processes for preparing these supports, for example by 3D printing, blowing or molding.

There is also a need for a material to prepare coral reef regeneration media that promotes coral adhesion and growth.

There is also a need for a material to prepare coral reef regeneration supports that can give these supports flexibility and roughness.

There is also a need for a material to prepare coral reef regeneration scaffolds that are suitable for hot assembly.

There is also a need for a device for holding a coral cutting or fragment, or a support structure for such a device, whose biomimicry promotes the growth and development of the coral.

Finally, there is also a need for a material to prepare coral reef regeneration media that can replicate as closely as possible the natural in situ development of coral.

It is also necessary to have materials that are compatible with, or even promote, coral growth.

It is also necessary to have materials that can be degraded naturally as the corals grow.

It is necessary to have materials available that can provide biomimicry that promotes coral growth.

The present invention aims to satisfy these different needs in whole or in part.

According to a first object, the invention relates to a biodegradable material comprising at least

1. a mixture of biodegradable polymers comprising:

- a first polyhydroxyalkanoate (PHA) having a melting point greater than or equal to approximately 120°C, and

- a second polyhydroxyalkanoate (PHA) having a melting point less than or equal to about 80°C, and

2. at least one dehydrated calcareous algae and/or a dry, non-water-soluble residue of calcareous algae.

In particular, the first PHA may have a melting point ranging from about 125°C to about 200°C, in particular from about 145°C to about 190°C, more particularly from about 165°C to about 175°C.

In particular, the first PHA is a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid.

According to a particular embodiment, the second PHA may have a melting point ranging from about 25°C to about 75°C, in particular ranging from about 35°C to about 70°C, more particularly ranging from about 45°C to about 65°C.

In particular, the second PHA is a (homo)polymer of 3-hydroxyoctanoic acid.

According to a particular embodiment, the biodegradable material comprises:

- at least 70% by weight, in particular at least 80% by weight, more particularly at least 90% by weight, more particularly at least 95% by weight of a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid; and

- 30% or less by weight, in particular 20% or less by weight, more particularly 10% or less by weight, more particularly 5% or less by weight of a (homo)polymer of 3-hydroxyoctanoic acid,

relative to the total weight of the biodegradable material.

According to one embodiment, the biodegradable material may comprise a dehydrated calcareous algae.

According to one embodiment, the biodegradable material may comprise a non-water-soluble dry residue of calcareous algae.

In particular, the dehydrated calcareous algae and the dry non-water-soluble residue of calcareous algae may be micronized. The micronized dehydrated calcareous algae and the dry non-water-soluble residue of calcareous algae may comprise particles having an average diameter ranging from about 100 to about 250 µm, or an average diameter of about 200 µm.

In particular, the calcareous algae can be a coralline. The coralline can be chosen from corallines of the species Jania rubens or Corallina officinalis.

According to a particular embodiment, the biodegradable material comprises from about 60% to about 95% by weight of the mixture of biodegradable polymers, in particular from about 65% to about 90% by weight of the mixture of biodegradable polymers, more particularly from about 70% to about 85% by weight of the mixture of biodegradable polymers relative to the total weight of the biodegradable material.

According to a particular embodiment, the biodegradable material comprises from about 5% to about 40% by weight, in particular from about 10% to about 35% by weight, more particularly from about 15% to about 30% by weight of dehydrated calcareous algae and/or non-water-soluble dry residue of calcareous algae, in particular dehydrated coralline algae and/or non-water-soluble dry residue of coralline algae, relative to the total weight of the biodegradable material.

According to a second aspect, the present invention relates to a process for preparing a biodegradable material according to the invention, comprising at least one step consisting of mixing:

1. at least one mixture of biodegradable polymers comprising:

- at least one polyhydroxyalkanoate (PHA) having a melting point above about 120°C, and

- at least one polyhydroxyalkanoate (PHA) having a melting point below about 80°C, with

2. at least one dehydrated calcareous algae and/or a dry, non-water-soluble residue of calcareous algae.

According to another aspect, the present invention relates to a filament for 3-dimensional (3D) printing comprising a biodegradable material according to the invention.

The invention also relates to a device for holding a coral cutting comprising at least one biodegradable material according to the invention or produced with a filament according to the invention.

Finally, the invention relates to a method of manufacturing a coral cutting holding device according to the invention comprising at least one step consisting of printing in 3 dimensions (3D) said device from a biodegradable material according to the invention or from a filament according to the invention.

Indeed, the inventor has developed biodegradable material formulas comprising particular polyhydroxyalkanoates with additional charges in order to obtain 3D printable materials, these printing materials to be used to produce design, aquariology and coral restoration objects according to the following criteria:

- 100% bio-sourced;

- 100% locally manufacturable, particularly in France;

- 100% biodegradable;

- sourced with minimal impact on the natural environment; and

- containing elements proven to help coral grow.

The inventor has surprisingly demonstrated that a biodegradable material according to the invention as well as filaments for 3D printing comprising such a material make it possible to produce coral regeneration supports that are respectful of the cutting but also of the environment in which they are placed. In addition, it has been demonstrated that these supports, unlike supports prepared outside the invention, are more resistant to the natural growth conditions of coral cuttings, thus allowing them to heal and develop.

Detailed description Definitions

It should be noted that as used herein and in the appended claims, the singular forms "a" and "the" include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to "a device" includes reference to a plurality of devices, and reference to "a medium" includes reference to a plurality of mediums, and so on.

The expression “comprising a” should be understood as being synonymous with “comprising at least one”.

The terms “about” or “approximately” as used herein in connection with a numerical value or parameter refer to the usual error range, known to those skilled in the art in the technical field, for measuring that value or parameter. Reference to “about” “a value or parameter” includes and describes embodiments using that value or parameter. In some embodiments, the term “about” refers to ±10% of a given value. However, whenever the value in question refers to an indivisible object that would lose its identity when subdivided, then “about” refers to ±1 of the indivisible object.

The aspects and embodiments of the present invention described herein include the variants "having", "comprising", "consisting of" and "consisting essentially of" of such aspects and embodiments. The terms "have" and "comprise" used in connection with an element, or variants such as "has", "having", "comprises" or "comprising", are understood to imply the inclusion of the element(s) recited without exclusion of other elements. The term "consisting of" implies the inclusion of the element recited to the exclusion of any additional elements. The term "consisting essentially of" implies the inclusion of the element recited, and optionally other elements where such other elements do not materially affect the essential feature(s) of the disclosure. It is understood that the various embodiments of the disclosure using the term "comprising" or an equivalent cover embodiments where this term is replaced by "consisting of" or "consisting essentially of".

It is understood that certain features of the invention, which are, for the sake of clarity, described as separate embodiments, may also be combined in a single embodiment. Conversely, various features of the invention, which are, for the sake of brevity, described in the context of a single embodiment, may also be implemented separately or in appropriate subcombinations.

Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as that generally understood by those skilled in the art of the invention. Any methods and materials similar or equivalent to those described herein may also be used in practicing the invention. All publications mentioned herein are incorporated by reference to describe the methods and/or materials in connection with which such publications are cited.

The list of sources, ingredients and components described herein are listed such that combinations and mixtures thereof are also contemplated and included herein. The lists given may be read and interpreted to mean “selected from the group consisting of” the list of compounds or items given, “and mixtures thereof.”

Each maximum numerical limitation given in the description includes all lower numerical limitations, as if such lower numerical limitations were expressly written. Each minimum numerical limitation given in the description includes all higher numerical limitations, as if such higher numerical limitations were expressly described herein. Each numerical range given in the description includes the narrower numerical ranges included within such given numerical range, as if such numerical ranges were expressly described herein.

Reference is made in the description to given materials, compounds or equipment with a particular trade name. The invention is not limited to the implementation of these specific materials, compounds or equipment and includes any equivalent known in the art.

Biodegradable material

A biodegradable material according to the invention comprises (1) at least one mixture of biodegradable polymers comprising a first polyhydroxyalkanoate (PHA) having a melting point greater than or equal to about 120°C, and a second polyhydroxyalkanoate (PHA) having a melting point less than or equal to about 80°C, and (2) at least one dehydrated calcareous algae and/or a dry non-water-soluble residue of calcareous algae.

Mixture of polyhydroxyalkanoates

A biodegradable material according to the invention firstly comprises at least one mixture of biodegradable polymers comprising:

- a first polyhydroxyalkanoate (PHA) having a melting point greater than or equal to approximately 120°C (high melting point), and

- a second polyhydroxyalkanoate (PHA) having a melting point less than or equal to approximately 80°C (low melting point).

The melting point refers to the change of state of a polymer when it passes from a solid state to a liquid state. There are different melting point measuring devices, all based on the restitution of a temperature gradient. They can consist of either a heated metal plate such as the Kofler Bench or the Maquenne block, or an oil bath such as the Thiele tube or by calorimetry.

As used in the description, the term " biodegradable material " is intended to mean a material capable of being broken down into biomass by microorganisms, such as bacteria, fungi and algae, which use the material as a nutrient.

As used in the description, the term " biodegradable polymer " means a biodegradable molecule composed of numerous repeating subunits called monomers. In a polymer, the monomers may be identical, in which case it is called a homopolymer. Alternatively, a polymer may be composed of several different repeating units, for example at least 2 or 3, or more, different repeating units, in which case it is called a copolymer.

Polyhydroxyalkanoates, or PHAs, are biodegradable polyesters produced naturally by bacterial fermentation of sugars or lipids as carbon and energy storage.

The monomers forming PHAs can be the same or different.

In particular, PHAs are formed from identical monomers. These are then called homopolymers.

PHAs can also be formed from monomers that are different from each other. These are then referred to as copolymers. According to a particular embodiment, the PHAs are formed from a chain of at least two, in particular two, different monomers.

According to a particular embodiment, the first PHA of the biodegradable polymer blend is a copolymer. According to a particular embodiment, the second PHA of the biodegradable polymer blend is a homopolymer.

Thus, the first PHA can correspond to a sequence of patterns of the following formula (I):

(I)

where n ₁ is an integer from 2 to 6, in particular n ₁ is equal to 4; and n ₂ is an integer from 1 to 3, in particular n ₂ is equal to 1.

According to a particular embodiment, the second PHA has a molecular weight, measured by size exclusion chromatography (SEC, SEC-HPLC or HPSEC), ranging from 25,000 Da to 150,000 Da, in particular ranging from 40,000 Da to 120,000 Da.

The biodegradable polymer blend of the invention comprises a first PHA having a melting point greater than or equal to approximately 120°C and a second PHA having a melting point less than or equal to approximately 80°C.

Thus, the first PHA may be referred to as a “high melting point PHA,” meaning a PHA having a melting point of about 120°C or greater. The second PHA may be referred to as a “low melting point PHA,” meaning a PHA having a melting point of about 80°C or less.

According to a particular embodiment, the first PHA has a melting point ranging from about 125°C to about 200°C, in particular ranging from about 145°C to about 190°C, more particularly ranging from about 165°C to about 175°C.

In particular, the first PHA according to the invention may be a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid (or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer).

According to a particular embodiment, the second PHA has a melting point ranging from about 25°C to about 75°C, in particular ranging from about 35°C to about 70°C, more particularly ranging from about 45°C to about 65°C.

In particular, the second PHA may be a (homo)polymer of 3-hydroxyoctanoic acid (or poly(3-hydroxyoctanoate) polymer).

The second PHA may be a polyhydroxyalkanoate of medium chain length. In particular, the second PHA may be a (homo)polymer of 3-hydroxyoctanoic acid of molecular weight, as measured by size exclusion chromatography (SEC, SEC-HPLC or HPSEC), ranging from about 40 kDa to about 120 kDa.

According to a particular embodiment, the mixture of biodegradable polymers is a mixture of a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid and a (homo)polymer of 3-hydroxyoctanoic acid.

The molecular weight and melting temperature of a polymer suitable for the invention can be determined as described in Higuchi-Takeuchi et al. PLoS One. 2016;11(8):e0160981 (doi:10.1371/journal.pone.0160981).

According to a particular embodiment, the mixture of biodegradable polymers comprises:

- at least 70% by weight, in particular at least 80% by weight, in particular at least 85% by weight, more particularly at least 90% by weight, more particularly at least 95% by weight of the first PHA, and less than 100% by weight of the first PHA; and

- 30% or less by weight, in particular 20% or less by weight, in particular 15% or less, more particularly 10% or less by weight, more particularly 5% or less by weight of the second PHA, and more than 0% by weight of the second PHA,

relative to the total weight of the biodegradable material.

More specifically, the biodegradable polymer blend includes:

- at least 70% by weight, in particular at least 80% by weight, more particularly at least 90% by weight, more particularly at least 95% by weight of a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid; and

- 30% or less by weight, in particular 20% or less by weight, more particularly 10% or less by weight, more particularly 5% or less by weight of a (homo)polymer of 3-hydroxyoctanoic acid,

relative to the total weight of the biodegradable material.

According to a particular embodiment, the mixture of biodegradable polymers comprises:

- 95% by weight of the first PHA, in particular of copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid, and

- 5% by weight of the second PHA, in particular of (homo)polymer of 3-hydroxyoctanoic acid,

relative to the total weight of the biodegradable material.

According to a particular embodiment, the mixture of biodegradable polymers consists of a mixture of:

- 95% by weight of the first PHA, in particular of copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid, and

- 5% by weight of the second PHA, in particular of (homo)polymer of 3-hydroxyoctanoic acid,

relative to the total weight of the biodegradable material.

PHAs suitable according to the invention are notably offered by the company POLYMARIS BIOTECHNOLOGY under the references BIOSALITE-V and BIOSEALITE-O.

In particular, a biodegradable material according to the invention comprises from about 60% to about 95% by weight of the biodegradable polymer mixture, in particular from about 65% to about 90% by weight of the biodegradable polymer mixture, more particularly from about 70% to about 85% by weight of the biodegradable polymer mixture relative to the total weight of the biodegradable material.

Dehydrated calcareous algae and non-water-soluble dry residue of calcareous algae

A biodegradable material according to the invention further comprises at least one dehydrated calcareous algae or a non-water-soluble dry residue of calcareous algae.

According to a particular embodiment, the calcareous algae according to the invention are marine calcareous algae.

Calcareous algae or coralligenous algae are capable of building, by superposition of crusts or by accumulation of deposits, massifs comparable to coral massifs. The main species of calcareous algae are red algae which belong to the families Corallinaceae or Peyssonneliaceae .

According to a particular embodiment, the calcareous algae is chosen from Lithophyllum cabiochae , Mesophyllum expansum , Mesophyllum lichenoides , Peyssonnelia rosa marina , Halimeda tuna , Flabellia petiolata , Mesophyllum lichenoide , Lithophyllum frondosum , Jania rubens, Corallina caespitosa , Corallina elongata , Corallina frondescens , Corallina melobesioides , Corallina officinalis , Corallina pilulifera , Corallina pinnatifolia , or even Corallina vancouveriensis . In particular, the calcareous algae according to the invention is a coralline, and in particular the calcareous algae is chosen from Jania rubens, Corallina caespitosa , Corallina elongata , Corallina frondescens , Corallina melobesioides , Corallina officinalis , Corallina pilulifera , Corallina pinnatifolia , or Corallina vancouveriensis , and more particularly the calcareous algae is Corallina officinalis or Jania rubens .

As used in the description, a " dehydrated calcareous algae " is a product obtained by evaporation of water and volatile compounds contained in the fresh algae. According to a particular embodiment, the dehydrated calcareous algae is a dehydrated coralline algae.

A dehydrated calcareous algae can be obtained by one or more drying (or desiccation) steps of a fresh calcareous algae.

Methods for drying algae are known in the art. The algae according to the invention can in particular be dried in the open air, or in desiccators or dehydrators, for example a pulsed air dryer. In particular, a dehydrated calcareous algae can be obtained by drying the fresh calcareous algae at a temperature varying from about 40°C to about 70°C, in particular varying from about 45°C to about 65°C, more particularly at a temperature varying from about 50°C to about 60°C, and in particular at a temperature of about 55°C. In particular, a dehydrated calcareous algae can be obtained by drying the fresh calcareous algae at a temperature greater than or equal to 40°C, in particular greater than or equal to 45°C, more particularly at a temperature greater than or equal to 50°C. In particular, a dehydrated calcareous algae can be obtained by drying the fresh calcareous algae at a temperature of less than or equal to 70°C, in particular less than or equal to 65°C, more particularly at a temperature of less than or equal to 60°C. According to a particular embodiment, the step of drying the fresh algae has a duration of at least 12 hours and less than or equal to 100 hours, in particular at least 18 hours, in particular at least 22 hours. According to a particular embodiment, the duration of the drying step can range from 12 hours to 72 hours, in particular from 18 hours to 48 hours, more particularly from 20 hours to 30 hours.

According to a particular embodiment, the dehydrated calcareous algae, in particular dehydrated coralline algae, is obtained by drying fresh calcareous algae, in particular fresh coralline algae, in a desiccator or dehydrator at a temperature of approximately 55°C, for approximately 24 hours.

A calcareous algae according to the invention is considered to be dehydrated when the water content included in the algae is less than or equal to 20% by weight, in particular is less than or equal to 10% by weight relative to the total weight of the algae.

According to a particular embodiment, the dehydrated calcareous algae is a dry, non-water-soluble residue of calcareous algae. In particular, the dry, non-water-soluble residue of calcareous algae is a dry, non-water-soluble residue of coralline algae.

" Dry non-water-soluble residue of calcareous algae " means a dehydrated calcareous algae from which the water-soluble compounds have been removed. Such a residue can be obtained by water-solubilization of calcareous algae, in particular dehydrated calcareous algae. The water-soluble compounds of calcareous algae, and in particular coralline algae, include in particular minerals, proteins, taurine, floridoside, sugars, etc. The step during which the water-soluble compounds are removed from the calcareous algae is called the water-solubilization step.

The hydrosolubilization step of the algae can take place before or after the drying step. In particular, the hydrosolubilization step takes place after the drying step of the calcareous algae, and in particular of the coralline algae.

The hydrosolubilization of the algae can be carried out by any method known in the art. In particular, it can consist of the extraction of the water-soluble compounds from the calcareous algae by dissolving it in a solvent.

A solvent suitable for the hydrosolubilization of calcareous algae is in particular an aqueous phase, in particular water. The solvent may further consist of an acidic aqueous phase obtained, for example, by mixing water and one or more acids such as sulfuric acid or hydrochloric acid. According to a particular embodiment, a solvent suitable for the hydrosolubilization of calcareous algae is a mixture of water and at least one acid. In particular, the mixture comprises at least 75% by weight, in particular at least 85% by weight, more particularly at least 95% by weight of water, and less than 25% by weight, in particular less than 15% by weight, more particularly less than 5% by weight, even more particularly less than 1% by weight of an acid relative to the total weight of the mixture. In particular, a solvent suitable according to the invention has a pH ranging from 1 to 3, in particular has a pH of approximately 2. The duration of contact of the calcareous algae with the solvent can range from 1 hour to 5 hours, in particular from 2 hours to 4 hours, and more particularly the contact can last approximately 3 hours.

In particular, the hydrosolubilization process can be carried out at room temperature, that is to say in particular at a temperature between 10°C and 30°C, in particular between 15°C and 25°C.

According to a particular embodiment, a non-water-soluble dry residue of calcareous algae can be obtained by at least one step of hydrosolubilization of a dehydrated calcareous algae in a solvent consisting of an acidic aqueous phase, having a pH ranging from 1 to 3, at room temperature, for 1 hour to 5 hours.

A dehydrated calcareous algae, in particular a coralline algae, is considered to be water-solubilized when the content of water-soluble compounds is less than 15% by weight, in particular is less than 10% by weight, more particularly is less than 5% by weight relative to the total weight of the algae. In particular, a calcareous algae, in particular a coralline algae, is water-solubilized when it is free of water-soluble compounds.

Through his research, the inventor discovered that corals and/or their larvae attach better to supports that have been previously immersed in seawater and that have developed a film composed of living organisms on its surface. This phase, which is called biologization, should allow the development of a calcareous red macro-algae called coralline on the surface of the chosen support.

Coralline algae fulfill two key roles in reef ecosystems: it contributes significantly to reef calcification (and its strengthening) and it plays an important induction role in the attachment to hard substrate of larvae of many benthic organisms ( Secore, 2016 ).

The presence of these highly calcareous encrusting algae is also important for the settlement of coral larvae of "hard" corals (Fabricius et al., 2001, Soft Corals and Sea Fans: A comprehensive guide to the tropical shallow water genera of the central-west Pacific, the Indian Ocean and the Red Sea. Australian Institute of Marine Science, Townsville. 264 pp. ISBN: 0 642 322104; Harrington et al., 2004, Recognition and selection of settlement substrata determine post-settlement survival in corals. Ecology 85(12):3428-3437).

In particular, the coralline according to the invention may be any coralline belonging to the genus Corallina.

According to a particular embodiment, the coralline is chosen from corallines of the species Jania rubens and/or Corallina officinalis .

Calcareous algae, especially coralline algae, can be obtained by growing the algae in a photoreactor in seawater for 40 to 50 days. The algae is then harvested, and dried as described above.

In a calcareous algae or in a dry, non-water-soluble residue of calcareous algae, for example a coralline algae, according to the invention, calcium carbonate represents the most significant part of the algae in terms of mass content.

Dehydrated calcareous algae, in particular dehydrated coralline algae, and a non-water-soluble dry residue of calcareous algae, in particular coralline algae, suitable according to the invention are marketed in particular by the company CODIF INTERNATIONAL.

According to a particular embodiment, the dehydrated calcareous algae and the non-water-soluble dry residue of calcareous algae are micronized.

The term " micronization " is intended to designate a process consisting in reducing a solid product, possibly already particulate, into microscopic particles, i.e. into particles having an average diameter of between 1 and 500 µm. A " micronized " product is a product resulting from a micronization process. Micronization processes are known to those skilled in the art. As an example of a micronization process, mention may be made of milling or grinding. According to a particular embodiment, the micronization of the dehydrated calcareous algae and the non-water-soluble dry residue of calcareous algae, in particular coralline algae, may be carried out by a step of grinding the algae and/or the dry residue. The grinding step may be carried out by any method known to those skilled in the art to achieve such a particle size.

In particular, the dehydrated calcareous algae and the dry non-water-soluble residue of micronized calcareous algae comprise particles having an average diameter (hydrodynamic average diameter) of a particle varying from approximately 100 to approximately 500 µm, in particular from approximately 100 to approximately 250 µm, or even an average diameter of approximately 200 µm, in particular an average diameter of approximately 150 µm.

The mean diameter of a particle is calculated from the average of the diameters passing through the geometric center of the particle.

According to a particular embodiment, more than 50% of the particles forming the dehydrated calcareous algae or the non-water-soluble dry residue of calcareous algae, in particular more than 80% of the particles forming the dehydrated calcareous algae or the non-water-soluble dry residue of calcareous algae, more particularly more than 90% of the particles forming the dehydrated calcareous algae or the non-water-soluble dry residue of calcareous algae have an average diameter varying from approximately 100 to approximately 500 µm, in particular from approximately 100 to approximately 250 µm, or even an average diameter of approximately 200 µm, in particular an average diameter of approximately 150 µm.

The diameter of a particle can be measured by laser diffraction (wet and dry measurements) and DLS (dynamic light scattering) methods. These techniques are the most commonly used to determine particle size, particle size or particle size distribution in the art and are well known to those skilled in the art.

The average diameter of the particles of dehydrated calcareous algae or of a dry non-water-soluble residue of micronized calcareous algae can be measured by DLS and can have a value varying from approximately 100 to approximately 500 µm, in particular from approximately 100 to approximately 250 µm, or even an average diameter of approximately 200 µm, in particular an average diameter of approximately 150 µm.

According to a particular embodiment, a biodegradable material comprises from about 5% to about 40% by weight, in particular from about 10% to about 35% by weight, more particularly from about 15% to about 30% by weight of dehydrated calcareous algae and/or non-water-soluble dry residue of calcareous algae, in particular coralline algae, relative to the total weight of the biodegradable material.

Other optional ingredients

A biodegradable material according to the invention may further comprise one or more optional additives. Of course, any added additive must not compromise the biodegradable nature of the material. In particular, the additive(s) must be suitable for incorporation into filaments for 3D printing. In addition, these additives must be compatible with contact with cuttings of aquatic animals, or must even be conducive to the growth and development of cuttings of aquatic animals, in particular corals. They must not be toxic to the cuttings.

These additives can in particular be chosen from among colorants and biological active ingredients.

For the purposes of this text, the term "dyes" means coloring materials, in particular natural ones, which make it possible to impart a color to the material in which they are incorporated. The natural coloring materials suitable according to the invention may be derived from plants or invertebrates. They may also be mineral pigments, most often based on iron oxide. Examples of dyes suitable for a biodegradable material according to the invention are in particular ochres, oxides, earths (sienna), umbers, pigments extracted from algae, etc.

By "biological active ingredients" within the meaning of this text is meant molecules or active ingredients, in particular of natural origin, which have a particular biological effect on the cutting of aquatic animals. In particular, a biological active ingredient of interest must be able to be integrated into a material according to the invention. In addition, a biological active ingredient of interest should stimulate the growth and/or development of an aquatic animal cutting, that is to say that an aquatic animal cutting must have greater and/or faster growth and/or development when the composition comprises at least one biological active ingredient, than when the composition is devoid of it. In particular, a biological active ingredient makes it possible to strengthen the health of the cuttings, by activating their physiological metabolisms, and increase the yield in terms of quality and/or quantity.

Examples of biological active ingredients suitable for a material according to the invention include certain algae extracts.

Process for the preparation of a biodegradable material

The invention also relates to a method for preparing a biodegradable material according to the invention. This preparation method comprises at least one step consisting in mixing

1. at least one mixture of biodegradable polymers comprising:

- at least one polyhydroxyalkanoate (PHA) having a melting point above about 120°C, and

- at least one polyhydroxyalkanoate (PHA) having a melting point below about 80°C, with

2. at least one dehydrated calcareous algae and/or a dry, non-water-soluble residue of calcareous algae.

The mixture of biodegradable polymers and dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae may be as described above.

The step of mixing the mixture of biodegradable polymers and the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae can be carried out by any means known in the art.

According to one embodiment, the preparation method further comprises a step of homogenizing the mixture obtained.

According to a particular embodiment, the PHAs forming the mixture of biodegradable polymers are ground, more particularly are ground before their mixing with the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae.

The homogenization of the polymer mixture and the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae can be carried out, for example, in the melt process by co-rotating twin-screw extrusion.

Use of biodegradable material

Also described is the use of a biodegradable material as defined above for the growth of a marine coral.

As indicated above, the inventor has implemented a biodegradable material according to the invention as well as filaments for 3D printing comprising such a material making it possible to produce coral regeneration supports that are respectful of the cutting but also of the environment in which they are placed. In addition, by its formula, a biodegradable material according to the invention is particularly compatible with coral growth since the presence in particular of the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae makes it possible to create a surface promoting both the attachment of the cutting, but also its development.

The use of a biodegradable material according to the invention may in particular involve the manufacture of filaments for 3D printing as well as the manufacture of coral cutting holding devices comprising this biodegradable material. The 3D printing filaments and the coral cutting holding devices are described in more detail in the following paragraphs.

Filament for 3D printing

A biodegradable material according to the invention can be used for the preparation of filaments for 3-dimensional (3D) printing.

Thus, the present invention also relates to a filament for 3-dimensional (3D) printing comprising a biodegradable material as defined above.

3D printing means a process in which a filament of a thermoplastic material is drawn through a feed tube to a print head comprising heating means for heating the filament locally so as to melt it, and then the molten material is extruded through a nozzle located downstream of the heating means on the path of the filament. The molten material is deposited on a support, in the form of successive superimposed layers.

Filaments for 3D printing according to the invention can be used in methods following the technology by extrusion and deposition of fused material ("fused filament modeling" (FFM), "melted and extruded modeling" (MEM), "fused filament fabrication" (FFF), or "fused deposition method" (FDM) / "molten filament modeling" (FFM), "melted and extruded modeling" (MEM), "fused filament fabrication" (FFF), or "fused deposition method" (FDM)).

In particular, filaments according to the invention can be used in “fused filament fabrication” (FFF) technology.

Further described is a method of preparing filaments for 3-dimensional (3D) printing comprising a biodegradable material.

Methods for preparing filaments for 3D printing from materials comprising polymers are known in the art.

According to a particular embodiment, an intermediate step of the method of preparing such a filament comprises the step of producing granules from a biodegradable material as defined above.

An example of a method for preparing a filament for 3D printing according to the invention comprises the following steps: (1) grinding the mixture of biodegradable polymers, (2) mixing the mixture of biodegradable polymers with the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae, (3) heating the mixture obtained in an oven at a temperature of between 40°C and 100°C, in particular between 50°C and 90°C, in particular between 60°C and 80°C, for 2 hours to 12 hours, in particular from 4 hours to 10 hours, in particular from 6 hours to 8 hours, more particularly the mixture is obtained by heating at 70°C for 8 hours, (4) extruding the mixture by any extrusion means, in particular in an extruder, in particular in a co-rotating twin-screw extruder to obtain rods, (5) granulating the rods obtained using a MAAG Primo S60 granulator to obtain granules, (6) heating the granules in an oven at 70°C for 8 hours, and (7) extrusion of the granules on a single-screw spinning line to obtain filaments.

According to a particular embodiment, the filaments according to the invention have an average diameter of approximately 1.75 mm or approximately 2.85 mm. In particular, the filaments have an average diameter of approximately 1.75 mm.

Device for holding a coral cutting

The present invention further relates to a device for holding a coral cutting composed of at least one biodegradable material or a filament for 3D printing as described above.

Devices for holding a coral cutting suitable according to the invention are known in the art. In particular, their manufacture must be compatible with manufacture from a biodegradable material as described above or with manufacture by 3D printing from a filament as described above.

It is important to secure the coral fragment to a base or support during the early stages of propagation so that the coral can grow properly. If the coral is not properly secured to the base, the fragment may tilt or move, the natural attachment of the coral to the base will be delayed or will not occur, causing possible stunted growth.

The calcareous nature of the coral skeleton requires the use of adhesive agents such as epoxy resins (polyepoxides), cyanoacrylates, or even mortar-glue types, which have the disadvantage of presenting a certain toxicity with regard to coral and aquatic animals in general.

In particular, a device for holding a coral cutting that can be prepared with a material according to the invention is described in patent FR3107639. Such devices comprise: a first hollow tubular element extending along a longitudinal axis and comprising a distal end, a proximal end, an internal face and an external face, and a second element arranged coaxially at the proximal end of the first element and comprising a flared portion defining a flat surface comprising a plane diverging circumferentially around the longitudinal axis of the first element, and said device having a textured surface. These devices have the advantage of not requiring gluing, and can be adapted to massive corals.

The invention further relates to a method of manufacturing a coral cutting holding device comprising at least one step of 3D printing said device from a biodegradable material or a filament as described above.

Depending on the device to be manufactured, the printing process may include different parameters and printing methods.

3D printing processes are well known in the art.

Prior to printing, a device for holding a coral cutting is modeled. Such a model can be developed using different software, for example Catia, Fusion360, Solidworks, Creo, and the final format is generated in a machine-readable format, for example STEP, STL or OBJ. The resulting model is then cut into layers by a slicing software. The dimensions of the layers (length, diameter) are adapted to the printing equipment used, in particular the extrusion nozzle, the dimensions of the polymer filament, and also the extrusion rates/second. The layers must be thick enough and close to each other to ensure the solidity of the printed object, but also far enough apart and/or thin enough to give the printed object the desired flexibility. The software converts the model into coordinates that the 3D printer understands and the polymer is deposited in layers one above the other according to these coordinates during the printing process. When output, the model is in the form of a text file with a “.gcode” file extension.

A coral cutting holding device can be printed with a material according to the invention using various 3D printing technologies. 3D printing is an additive manufacturing technology where a 3D object is created by depositing layers of materials to create a physical object. Fused deposition modeling (FDM) printers typically use polymer filaments, such as PLA (polymer lactic acid), ABS (acrylonitrile butadiene styrene), PC (polycarbonate), PET-G (polyethylene terephthalate glycol), stereolithography (SLA) or DLP (Digital Light Processing) 3D printers use resins, and SLS (Selective Laser Sintering) technology uses a powder material, for example nylon.

In particular, a method of manufacturing a coral cutting holding device with a material according to the invention may use fused filament modeling (FFM), melted and extruded modeling (MEM), fused filament fabrication (FFF), or fused deposition method (FDM) technology.

In particular, a method of manufacturing a device for holding a coral cutting with a material according to the invention uses “fused filament fabrication” (FFF) technology.

A 3D printing method of a device for holding a coral cutting with a material according to the invention can be done in “vase” mode. This 3D printing mode implies that the wall is printed in a single layer, without interruption of the extruder (or printing nozzle). The z-axis rises gradually instead of making the layers one by one as in a standard print. Such printing is advantageously done without INFILL. The layer is gradually deposited on itself by rotating the printing nozzle around the longitudinal axis of the device. The stacking of the layer leads to the formation of striations forming the texturing of the surface.

A device for holding a coral cutting with a material according to the invention can be printed in 3D printing using fused deposition technology, with an extrusion nozzle with a diameter of approximately 0.8 mm. Printing speeds, layer thicknesses, extrusion temperatures will depend on the polymer used and the nozzle used. Typically, a layer thickness should not exceed 80% of the nozzle diameter.

For example, for a biodegradable polymer according to the invention, the nozzle temperature may be about 185°C (between 160°C and 200°C), the printing surface temperature about 80°C (between 60°C and 100°C), the printing speed about 8 mm/s (between 5 and 15 mm/s), and the layer height about 0.1 µm to about 30 µm.

Examples

Example 1: Preparation of biodegradable materials for 3D printing

Biodegradable materials were prepared according to the formulas below. The quantities below represent a mass percentage relative to the total weight of the corresponding composition. Formula A Formula B Formula C Formula D Copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid 76% 85.5% 76% 85.5% (Homo)polymer of 3-hydroxyoctanoic acid 4% 4.5% 4% 4.5% Dehydrated coralline of the species Jana Rubens 20% 10% / / Dry, non-water-soluble coralline residue of the species Jana Rubens / / 20% 10%

The above formulations were prepared by homogenizing PHA polymer matrix (PHA) comprising a mixture of 3-hydroxybutanoic acid-3-hydroxyvaleric acid copolymer and 3-hydroxyoctanoic acid (homo)polymer as shown in the table above with dehydrated coralline or dry non-water-soluble coralline residue.

Homogenization was carried out in the melt process by co-rotating twin-screw extrusion. Grinding of the PHA was carried out upstream of this step and drying of all the components (70°C/8 hours) preceded the extrusions. The rods produced were then granulated using a MAAG Primo S60 granulator.

Example 2: Preparing filaments for 3D printing

The pelletized formulas were then subjected to a second extrusion on a single-screw spinning line to produce standard 1.75mm diameter filaments for 3D printing using the “fused filament fabrication” (FFF) method. The pellets were systematically oven-cured beforehand (70°C/8H).

All the formulas in the form of filaments were evaluated by FFF 3D printing using a Creality CR10 V2 printer equipped with an E3D Titan direct Drive extruder and a Creality heating element equipped with an E3D-V6 nozzle with a diameter of 0.8 mm. The PrusaSlicer V2.3.0 software was used to prepare the prints. The filaments were systematically baked (70°C/8H) before the printing tests.

Two specific printing profiles have been developed, one in vase mode (continuous printing on a single perimeter) for the first model and the other in Rectilinear mode with a filling rate of 100%.

The filaments obtained from Formulas A to D of Example 1 were compared with filaments existing on the market. These filaments were prepared in the same way as filaments A to D, according to the following formulas:

Formula E : Polylactic acid + Oyster shell crush;

Formula F : Mixture comprising a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid and (homo)polymer of 3-hydroxyoctanoic acid (PHA) + Oyster shell ground material; and

Formula G : Mixture comprising a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid and (homo)polymer of 3-hydroxyoctanoic acid (PHA) alone.

From the filaments thus prepared, we proceeded to print supports for regenerating coral cuttings.

The filaments obtained from a biodegradable material according to the invention behave better during printing than the filaments obtained from formulas F and G. In fact, the latter are more viscous, adhere too much to the printing plate, regularly block the nozzles and give less solid printed layers, which makes the printed support more fragile.

The filaments obtained from a biodegradable material according to the invention have greater flexibility than the filaments obtained from formula E, and this flexibility persists for several minutes (about 15) after the end of the extrusion. This has the advantage of allowing slight modifications to the shape of the printed object before complete solidification of the object, and therefore the possibility of assembling the elements to be printed “hot”. The final object remains more flexible and less brittle.

Furthermore, the regeneration supports printed from filaments obtained with the biodegradable material formulas according to the invention have a roughness greater than the supports printed with formulas E and G, which is an advantage for the development of coral cuttings.

Finally, no difference was observed between the filaments obtained from formulas A to D, which allows us to conclude that the observed advantages are maintained whether the biodegradable material contains 10% or 20% of a dehydrated calcareous algae and/or a non-water-soluble dry residue of calcareous algae.

In conclusion, the filaments obtained from the biodegradable materials all presented a satisfactory quality for printing objects of interest by 3D printing.

Example 3: Coral cutting holding devices

Coral cutting regeneration supports, as described in patent FR 2 104 303, were 3D printed by the FFF method from filaments previously prepared from a biodegradable material according to the invention of formulas A and C. In addition, coral cutting regeneration supports were printed from biodegradable materials outside the invention of formulas 1 to 4. The formulas of the biodegradable materials tested are recalled in the table below. Formulas HAS* C* 1** 2** 3** 4** Mixture comprising a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid and (homo)polymer of 3-hydroxyoctanoic acid (PHA) 80% 80% 100% 80% Polylactic acid(PLA) 100% 80% Dehydrated coralline 20% Non-water-soluble dry residue of coralline 20% Crushed oyster shells 20% 20% * biodegradable material according to the invention
** biodegradable material outside the invention

In a closed water circuit where the environment reproduces the natural living conditions of corals, in a 100% controlled manner (the exact composition of the environment is known throughout the study), the supports printed from formulas 3 and 4 degrade too quickly. The supports printed from formulas A, C, 1 and 2 are more resistant to these conditions, allowing the cutting the time needed to heal and develop before being implanted on a new support or in situ .

Oyster shell crushing requires the consumption of crustaceans and a whole recycling process. It is therefore a complicated and expensive material to use, unlike dry extracts of calcareous algae, such as coralline algae, which are already produced industrially in a closed circuit without impacting the environment for equivalent efficiency.

In an open circuit with water from the port, loaded with nitrite and phosphate, the supports made from filaments of formulas A and C degrade very quickly. This gives the biodegradable materials according to the invention a certain advantage: that of indicating a significant increase in these two harmful elements in large quantities in the environment. The supports prepared from formulas 1 to 4, on the contrary, do not degrade as quickly in the presence of an excess of nitrite and phosphate and therefore cannot serve as indicators of water quality. In particular, and surprisingly, formulas 3 and 4 do not degrade at all under these conditions.

Claims (10)

Biodegradable material comprising at least
1. a mixture of biodegradable polymers comprising:
- a first polyhydroxyalkanoate (PHA) having a melting point greater than or equal to approximately 120°C, and
- a second polyhydroxyalkanoate (PHA) having a melting point less than or equal to about 80°C, and
2. at least one dehydrated calcareous algae and/or a dry, non-water-soluble residue of calcareous algae. Biodegradable material according to claim 1, characterized in that the first PHA has a melting point ranging from about 125°C to about 200°C, in particular from about 145°C to about 190°C, more particularly from about 165°C to about 175°C and/or in that the second PHA has a melting point ranging from about 25°C to about 75°C, in particular from about 35°C to about 70°C, more particularly from about 45°C to about 65°C. Biodegradable material according to any one of claims 1 or 2, characterized in that the first PHA is a copolymer of 3-hydroxybutanoic acid and 3-hydroxyvaleric acid and/or in that the second PHA is a (homo)polymer of 3-hydroxyoctanoic acid. Biodegradable material according to any one of the preceding claims, characterized in that the dehydrated calcareous algae and/or the non-water-soluble dry residue of calcareous algae are micronized, in particular the micronized dehydrated calcareous algae and/or the non-water-soluble dry residue of micronized calcareous algae comprise particles having an average diameter varying from approximately 100 to approximately 250 µm, or an average diameter of approximately 200 µm. Biodegradable material according to any one of the preceding claims, characterized in that the calcareous algae is a coralline, in particular a coralline chosen from corallines of the species Jania rubens or Corallina officinalis . A biodegradable material according to any preceding claim, comprising from about 60% to about 95% by weight of the biodegradable polymer blend, in particular from about 65% to about 90% by weight of the biodegradable polymer blend, more particularly from about 70% to about 85% by weight of the biodegradable polymer blend relative to the total weight of the biodegradable material. Biodegradable material according to any one of the preceding claims, comprising from about 5% to about 40% by weight, in particular from about 10% to about 35% by weight, more particularly from about 15% to about 30% by weight of dehydrated calcareous algae and/or a dry non-water-soluble residue of calcareous algae, in particular coralline algae, relative to the total weight of the biodegradable material. Process for preparing a biodegradable material according to any one of claims 1 to 7, comprising at least one step consisting of mixing:
1. at least one mixture of biodegradable polymers comprising:
- at least one polyhydroxyalkanoate (PHA) having a melting point above about 120°C, and
- at least one polyhydroxyalkanoate (PHA) having a melting point below about 80°C, with
2. at least one dehydrated calcareous algae and/or a dry, non-water-soluble residue of calcareous algae. A filament for 3-dimensional (3D) printing comprising a biodegradable material according to any one of claims 1 to 7. A device for holding a coral cutting comprising at least one biodegradable material according to any one of claims 1 to 7 or produced with a filament according to claim 9.