IT202200020922A1 - METHOD FOR THREE-DIMENSIONAL PRINTING OF FIBER COMPOSITE MATERIALS - Google Patents

Description

?METHOD FOR THREE-DIMENSIONAL PRINTING OF FIBER COMPOSITE MATERIALS?

Field of invention

The present invention relates to the field of three-dimensional molding of composite materials.

In particular, the present invention relates to an apparatus and a method for the three-dimensional printing of composite materials made of thermoplastic or thermosetting fibre and matrix.

Known technique

As is known, the term "composite" generally refers to a material obtained by combining two or more components so that the final product has properties that are different from those of the individual constituents. In the technical field, to better identify what is meant by the term "composite", it is customary to limit the class of composite materials to reinforced materials only, in which at least one component, usually in the form of fibres, has mechanical characteristics that are much superior to the others.

In general, it can be defined as a "composite material" or simply "composite" the union, by adhesion or cohesion, of two or more components, different in shape and chemical composition, insoluble in each other and separated by an interface.

Composites are generally made up of a continuous phase (called matrix) and a dispersed phase (often in the form of a reinforcing element). The dispersed phase is mainly responsible for the mechanical properties of the material (strength and stiffness), while the continuous phase is responsible for transferring external loads applied to the dispersed phase. This transmission occurs through shear stresses acting on the interface between the dispersed phase and the continuous phase. Furthermore, the matrix, in addition to stabilizing the composite under compression, has the function of holding together and protecting the fibres and creating the shape of the piece.

Ultimately, a composite material is a multiphase material that can be created artificially and is different from its constituents: according to the principle of combined actions, the optimization of a property is achieved through the careful and studied combination of two or more different materials.

Based on the matrix material that forms the continuous phase, composites are classified as metal matrix, ceramic matrix, and polymer matrix. Polymer matrix composites are generally made of synthetic fibers (e.g. carbon, nylon, aramid, or glass) embedded in a polymer matrix, which surrounds, protects, and binds the fibers. Typically, fibers make up about 50/60% of a polymer matrix composite by volume. Within the polymer matrix category, there are two subclasses of materials that make up the polymer matrix: thermoplastic polymers and thermoset polymers.

Thermoplastic polymers are a group of plastics that become malleable under the action of temperature. Subject to the action of temperature, thermoplastic polymers can be modeled or formed into finished objects and then, once cooled, return to being rigid structures. In fact, viscosity decreases as the temperature increases, but also with the increase in the flow speed and the shear stress. This heating/cooling cycle, theoretically, can be repeated several times based on the quality of the different plastics; in practice, it is possible to repeat the cycle a limited number of times since too much heating can degrade the polymers.

Thermosetting polymer materials have a cross-linked molecular structure formed by covalent bonds. Thermosetting polymers are cross-linked by a process called ?Curing?, through which the resin in the fluid state undergoes a series of chemical transformations passing through a gelled or rubbery layer until it passes to the glassy state. Some thermosetting resins are cross-linked by heat or by a combination of heat and pressure. In other cases, the chemical reaction can occur at room temperature (cold thermosetting) by means of light radiation, evaporation of substances, activation by humidity and finally due to the forced mixing of two elements (usually resin and catalyst).

Although thermoset resin products can soften under the effect of heat (Tg, glass transition temperature), the covalent bonds of the network prevent them from returning to the fluid state that existed before cross-linking. In fact, if heating causes the degradation temperature to be exceeded, they decompose by carbonizing. Thermoset materials, therefore, cannot be reheated and then melted as happens with thermoplastics.

Three-dimensional molding processes of composite materials are described for example in US9987798, US10011073 and US9126367.

The Applicant has observed that the known three-dimensional molding processes of fiber composite materials present limitations in the type of material and/or process that can be used. The Applicant has for example observed that in the case of thermosetting monomers capable of photopolymerization by the effect of electromagnetic radiation, the choice is often limited, for example opaque reinforcing fibers cannot be used (e.g. carbon fiber, basalt fiber, aramid fiber etc.). Another limitation in this case is given by the thicknesses that can be used, which cannot be too high.

The two above limitations result in deficiencies in the homogeneity and quality of the resulting product.

The Applicant has also noted that with reference to epoxy resins, these are often characterised by significant kinetic limitations, in other words the reactions that produce the polymer are very slow, such as to make these materials difficult to use in three-dimensional moulding processes.

Summary of the invention

Therefore, in a first aspect, the invention concerns a method for the three-dimensional printing of composite materials, comprising the phases of:

-feeding at least one continuous thread-like element to a feed head; said continuous thread-like element comprising at least one dispersed phase, preferably comprising a thermally conductive material, and at least one continuous phase reactive to frontal polymerization reactions;

-place said continuous thread-like element on a support surface;

-supplying to said continuous thread-like element an amount of energy such as to bring said at least one continuous phase to an ignition temperature so as to trigger a frontal polymerization reaction front in said at least one continuous phase;

- administer to said continuous thread-like element said quantity of energy repeatedly and in different positions along its extension, during the deposition phase, so as to trigger different polymerization fronts.

For the purposes of this invention, the following definitions apply:

?Frontal and/or frontal-type polymerization? refers to a polymerization reaction in which polymerization, i.e. the chemical reaction that leads to the formation of a polymer chain starting from simpler molecules called monomers, occurs directionally and through propagation from a localized reaction site [J. A. Pojman, ?Frontal Polymerization,? in Polymer Science: A Comprehensive Reference, Elsevier, 2012, pp. 957-980.]. This reaction occurs as a result of a trigger in the form of a localized stimulus and, once started, propagates in the material by the action of the reaction enthalpy, without the need for further energetic stimuli. In frontal-type polymerization processes, the heat generated by the reaction itself in the polymer chain propagation phase becomes the driving force for the propagation of the reaction itself, due to the activation of thermal initiator species upon reaching a trigger temperature [F. Petko, A. ?wie?y, and J. Ortyl, ?Photoinitiating systems and kinetics of frontal photopolymerization processes ? the prospects for efficient preparation of composites and thick 3D structures,? Polym. Chem., vol. 12, no. 32, pp. 4593?4612, 2021, doi: 10.1039/D1PY00596K.]. In particular, the activation of thermal initiator species, defined as those chemical species capable of producing reactive species under the action of temperature, is made possible by reaching said trigger temperature, characteristic of the specific thermal initiator species considered. Furthermore, it is evident that the monomeric species capable of giving rise to frontal polymerization reactions manifest highly exothermic reactions, thus capable of promoting the propagation of the reaction front.

By ?preliminary polymerization? we mean a polymerization of at least a part of the thread-like element that occurs at a time prior to and/or in a place prior to the feeding of the thread-like element to the feeding head.

In the context of a frontal polymerization, the "trigger temperature" refers to the temperature at which the activation of the thermal initiator species occurs, or the temperature at which the rapid decomposition of said initiator into reactive chemical species is favored, and therefore capable of initiating a polymerization reaction.

By "photosensitizing material and/or simply photosensitizing" we mean a chemical species that, when struck by electromagnetic radiation, is able to absorb it, bringing itself into an excited state. In this state, the photosensitizing species is able to transfer energy (for example through electron transfer or charge transfer mechanisms) to a photoinitiator, causing its activation and the consequent production of reactive chemical species. The use of photosensitizers may be necessary in the case in which a photoinitiator is not able to absorb radiation and, therefore, to activate itself autonomously, in the electromagnetic spectrum provided by the electromagnetic radiation source used in place of the source of the energy stimulus. The use of photosensitizers may be convenient in the case in which the radiation absorption process of the photoinitiator in the electromagnetic spectrum provided by the electromagnetic radiation source used in place of the source of the energy stimulus is poorly efficient.

By ?photoinitiator? we mean a chemical species capable of producing different and reactive chemical species by absorbing electromagnetic radiation, typically in the ultraviolet or visible electromagnetic spectrum. In the case of systems capable of photopolymerizing by the effect of electromagnetic radiation, with reference to the set or mixtures of monomer species, photoinitiators and any compounds with synergistic action, there are two main chemical processes of industrial relevance: radical and cationic. In the first case, the absorption of radiation by the initiator determines the production of reactive radicals. In the second, the absorption of radiation by the initiator determines the production of Br?nsted or Lewis acids, which are consequently capable of starting a ring-opening polymerization process, i.e. the type of chain polymerization reaction in which the reactive end of the growing polymer chain chemically attacks a monomer with a cyclic end to form a longer polymer chain. By ?cationic initiator? is understood as a chemical species capable of producing different and reactive chemical species, such as, for example, Br?nsted acids or Lewis acids, as a result of a photochemical or chemical stimulus. In particular, the term cationic initiator refers to those chemical species capable of starting cationic chain polymerization processes, as a consequence of the charge transfer between the initiator itself and the precursor monomer of the polymer being formed, making it in turn reactive towards other monomers. The production of reactive species can occur as a result of direct absorption of radiation, typically in the ultraviolet electromagnetic spectrum, by the cationic initiator species or as a result of oxidation reactions that occur in the presence of other reactive species participating in the reaction such as, for example, radical species.

By "synergistic compound" we mean an element of a photopolymerizable mixture conveniently added to improve the photoactivity of the mixture itself compared to the case of single use of the component materials of the mixture. The synergistic effect is reflected in the improved efficiency of the system in the radiation absorption phase, in the polymerization reaction phase, or both. For example, the use of combinations of different photoinitiators within a mixture can enable the use of different energy sources. The addition of elements such as amines or thiols can mitigate the effects of reaction inhibition caused by the presence of atmospheric oxygen, a known cause of poor efficiency of radical photopolymerization reactions.

The present invention, in the above aspect, may exhibit at least one of the preferred features described hereinafter.

Preferably, the amount of energy is applied directly to the continuous phase.

Conveniently, the amount of energy is applied to the dispersed phase so as to bring said at least one continuous phase to the ignition temperature.

Advantageously, the method includes:

-distribute at least one end of the continuous thread-like element on a respective support surface;

-subjecting said end of said thread-like element to an amount of energy such as to bring said at least one continuous phase to an ignition temperature so as to trigger a frontal polymerization reaction front in said at least one continuous phase;

-move said feed head with respect to the anchor point according to a pre-established path that defines the object to be printed.

This amount of energy can be supplied to directly heat said continuous phase or to heat said dispersed phase.

This amount of energy can be supplied by means of electromagnetic radiation sources.

Conveniently, this electromagnetic radiation is chosen from the infrared spectrum.

Conveniently, the feeding and deposition steps are implemented by exerting a tensile force on the continuous wire-like element by relative movement between a respective feeding head and the support surface or, by extrusion.

Advantageously, said at least one dispersed phase comprises a fiber material selected from carbon fibers, glass fibers, poly paraphenylene terephthalamide fibers, ultra high molecular weight polyethylene (UHWMPE) fibers, poly arylether ketone (PAEK) fibers, poly paraphenylene ? 2,6 ? benzobisoxazole fibers, poly ether sulfone (PES) fibers, beryllium fibers, tungsten fibers, carbon nanofibers, silicon carbide (SiC) fibers, boron fibers, polyimide (PI) fibers, poly benzoimidazole fibers, poly oxymethylene (POM) fibers, poly ether imide (PEI) fibers, metal alloy fibers, basalt fibers, natural fibers, and combinations thereof and similar materials.

Said at least one dispersed phase may comprise powdery material or material in the form of nanostructures.

Preferably, the powdery material chosen is carbon black, silicon dioxide, graphite, titanium oxide, boron nitride, zirconium oxide, calcium carbonate, calcium phosphate, molybdenum disulfide, lignin and their combinations and similar.

Preferably, the material in the form of nanostructures is chosen from graphene, single-walled carbon nanotubes, multi-walled carbon nanotubes, fullerene, clay nanoplates and their combinations and the like.

Conveniently, the continuous phase comprises at least a first compound comprising:

-a thermal initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %;

- a first monomer in an amount greater than or equal to about 20 mol % and less than or equal to about 99.9 mol %;

-a cationic initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %; and

-a first diluent in an amount greater than or equal to about 0 mol % and less than or equal to about 70 mol %.

Advantageously:

- said thermal initiator is selected from the group consisting of: 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED), benzopinacol bistrimethylsilyl ether (TPED-Si), dimethylsulfonyl peroxide (DMSP), tert-butyl peroxide (TBPO), tert-butylcyclohexylperoxodicarbonate (TBC-PDC), benzoyl peroxide (BPO), azobis(isobutyronitrile) (AIBN) and combinations thereof and similar;

-the first monomer? selected from the group consisting of: bisphenol A diglycidyl ether (DGEBA), bisphenol F diglycidyl ether (DGEBF), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (CE), 4-vinyl-1-cyclohexane 1,2-epoxide, vinylcyclohexene dioxide, 4,5-epoxytetrahydrophthalic acid diglycidyl ester, glycidyl methacrylate, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, poly(ethylene glycol) diglycidyl ether, epoxidized soybean oil, N,N-diglycidyl-4-glycidyloxyaniline, bis3,4-epoxycyclohexylmethyl adipate, diglycidyl 1,2-cyclohexane dicarboxylate, allyl glycidyl ether, phenyl glycidyl ether, diglycidyl 4,5epoxycyclohexane-1,2-dicarboxylate, 4,4''-methylenebis[N,N-bis(2,3-epoxypropyl)aniline], tris(2,3-epoxypropyl) isocyanurate, m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, triethoxy(3-glycidyloxypropyl)silane, 1,2-epoxycyclohexane, tris(4-hydroxyphenyl)methane triglycidyl ether, epoxy-phenolic resins (including those derived from novolacs), 9-[2-(2-methoxyethoxy)ethoxy]-9-[3-(oxiranylmethoxy)propyl]-2,5,8,10,13,16-hexaoxa-9-silaheptadecane, glycidyl stearate, resorcinol diglycidyl ether, 1,4-butanediol diglycidyl ether (BDGE), vinyl ethers, epoxy-phenolic resins (including those derived from dicyclopentadiene), carboxylic acid-functional acrylonitrile butadiene rubber (CTBN), epoxy-functional acrylonitrile butadiene rubber (ETBN) and combinations thereof and similar;

-the cationic initiator? selected from the group consisting of: [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium trieshafluorophosphate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate, (9-oxofluoren-2-yl)-pheniliodonium hexafluoroantimonate, [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium hexafluoroantimonate, [4-[(2-hydroxytetradecyl)oxy]phenyl]pheniliodonium hexafluoroantimonate, 4-octyloxydipheniliodonium hexafluoroantimonate, 10-(4-phenylphenyl)-2-propan-2-ylthioxanthen-10-io-9-one hexafluorophosphate, bis(4-dodecylphenyl)iodonium hexafluroranthomonate, bis-(4-t-butylphenyl)iodonium hexafluorophosphate, bis[4-(tert-butyl)phenyl]iodonium tetra(nonafluoro-tert-butoxy)aluminate, diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, diphenyliodonium hexafluorophosphate, bis(4-methylphenyl)iodonium hexafluorophosphate, (4-methylphenyl)[4-(propan-2-yl)phenyl]iodonium tetrakis(2,3,4,5,6-pentafluorophenyl) borate and combinations thereof; and

-the first diluent is selected from the group consisting of: polyfunctional glycidyl ethers, monofunctional aliphatic glycidyl ethers, monofunctional aromatic glycidyl ethers, 3-ethyl-3-oxetanomethanol (EOM), 3-methyl-3-oxetanomethanol, 1,4bis(glycidyloxy)benzene (CHDGE), 1,6-hexanediol diglycidyl ether (HDDGE), neopentyl glycol diglycidyl ether (NPDGE), 1,4-butanediol diglycidyl ether (BDGE) and combinations thereof.

Preferably, the first compound may comprise a photosensitizing material.

Advantageously, the photosensitizing material is present in an amount greater than or equal to about 0.00 1 mol % and less than or equal to about 5 mol %. Preferably, the photosensitizing material is selected from the group consisting of: anthracene, perylene, benzophenone, 9,10-diethoxyanthracene, 2,2-dimethoxy-2-phenylacetophenone, 2-isopropylthioxanthone (ITX), thioxanthen-9-one, vinylcarbazole and combinations thereof;

Alternatively, this amount of energy is delivered by electromagnetic radiation selected from the ultraviolet spectrum.

Alternatively, this energy is supplied by means of energy sources operating by convection.

According to an alternative embodiment, the continuous phase may comprise at least one second compound comprising:

-a photoinitiator in an amount greater than or equal to about 0.01 mol % and less than or equal to about 10 mol %;

- a second monomer in an amount greater than or equal to about 20 mol % and less than or equal to about 99.9 mol %;

advantageously the second compound also includes:

-a compound with synergistic action in an amount greater than or equal to 0 mol % and less than or equal to approximately 50 mol %;

-a second diluent in an amount greater than 0 mol % and less than or equal to approximately 70 mol %.

Preferably, the second compound is present in an amount greater than or equal to 0.1 mol% and less than or equal to 20 mol%. Conveniently, said second compound is subjected to a preliminary polymerization step upstream of the feed head. Advantageously, the second diluent is selected from the group consisting of: neopentyl acrylate, 3-methyl-1,5-pentadiol diacrylate, 1,6-hexanediol diacrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate and combinations thereof and the like. Preferably the synergistic compound is selected from the group consisting of molecules exhibiting amine groups including triethylamine, tri-N-butylamine, 2-dimethylaminoethanol, N-methyldiethanolamine, triethanolamine, 2-(dimethylamino)ethyl benzoate, ethyl 4-(dimethylamino)benzoate, 2-ethylhexyl-4-dimethylamino-benzoate, isoamyl 4-(dimethylamino)? benzoate, 2-butoxyethyl 4-(dimethylamino)-benzoate, N-phenylglycine, 4,4',4''-tris(dimethylamino)-triphenylmethane and their combinations and similar compounds or from the group consisting of molecules exhibiting thiol groups, including butyl 3-mercaptopropionate, trimethylolpropanetris(2-mercaptoacetate), trimethylolpropane - tris(2-mercaptopropionate), 2-benzothiazolethiol, 2-benzimidazolethiol, 1,6-hexane bis(3-mercaptopropionate), di[trimethylolpropane tris(3-mercaptopropionate)], pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-butanediyl bis(3-mercaptobutyrate), trimethylol propane tris(3-mercaptobutyrate) and their combinations and similar compounds. Advantageously, the photoinitiator is selected from the group consisting of: 2-hydroxy-2-methylpropiophenone, 2,2-dimethyl-2-hydroxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-hydroxy-2-methyl-4'-tert-butyl-propiophenone, 2-hydroxy-2-methyl-1-(4-tert-butylphenyl)-propanone, 1-hydroxycyclohexylphenylketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophenone, 2-hydroxy-[4'-(2-hydroxypropoxy)]-2-methylpropiophenone, 2-hydroxy-[4'-(2-hydroxypropoxy)phenyl]-2methylpropanone, oligo 2-hydroxy-2-methyl-1-[4-(1-methyl-vinyl)phenyl]propanone, 2-hydroxy-1-[4[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl]-2-methyl-propane-1-one, 2-methyl-4'-(methylthio)-2-morpholino-propiophenone, 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone, 2-(4-methylbenzyl)-2-(dimethylamino)-4-morpholinobutyrophenone, 2,2-dimethoxy-2-phenyl-acetophenone, 2,2-diethoxy-2-phenyl-acetophenone, 2,2-diethoxy-1-phenylethanone diethoxyacetophenone, 2-isopropoxy-2-phenylacetophenone, 2-N-butoxy-2-phenylacetophenone, 2-isobutoxy-2-phenylacetophenone, bis(2,4,6-trimethylbenzoyl)-(2,4-bis-pentyloxyphenyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl-bis-(2,4,6-trimethylbenzoyl)phosphine oxide, 4'-(tert.butyl)-2,2,2-trichloroacetophenone, 4'-(phenoxy)-2,2-dichloroacetophenone, 2-(4-methoxyphenyl)-4,6-bis-(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine, 2,4-bis(trichloromethyl)-6-(3,4-dimethoxy)-styryl-s-triazine, 2,4-bis(trichloromethyl)-6-(3,4-dimethoxy)-styryl-striazine, 1-phenyl-1,2-propandione-2-(o-ethoxy-carbonyl) oxime, 1-[4-(phenylthio)phenyl]-octane-1,2-dione-2-(o-benzoyloxime), benzophenone, 4-methylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, benzophenone-2-carboxy-(tetraethoxy)acrylate, 4-phenylbenzophenone, methyl 2-benzoylbenzoate, 1-{-4-[benzoylphenylsulfo]phenyl}-2-methyl-2-(4-methylphenylsulfonyl)-propan-1-one, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 1-chloro-4-propoxythioxanthone, 2,4-diisopropylthioxanthone, methyl phenylglyoxylate, 2-ethylanthraquinone, 2-ethyl-9,10-anthracene dione, polyethylene glycol-bis-[(4-acetylphenyl)-piperazine propionate], 3-benzoyl-7-methoxy-2H-chromen-2-one and combinations thereof. Preferably the second monomer ? selected from the group consisting of (meth)acrylate monomers, comprising: tricyclodecane dimethanol diacrylate, 3-[2,2-dimethyl-1-oxo-3-[(1-oxo-2-propenyl)oxy]propoxy]-2,2-dimethylpropyl acrylate, dihydro dicyclopentadienyl acrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, dipropylene glycol diacrylate, ditrimethylol propane tetraacrylate, isobornyl acrylate, dipentaerythritol hexacrylate, tert-butyl acrylate, trimethylol propane triacrylate, tripropylene glycol diacrylate, bisphenol A diacrylate n-ethoxylate (with 1< n < = 10), bisphenol A diacrylate, 3,3,5-trimethylcyclohexyl acrylate, (5-ethyl-1,3-dioxan-5-yl)methyl acrylate, trimethylol propane triacrylate n ethoxylate (with 1< n < = 10), neopentyl glycol diacrylate, triethylene glycol diacrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobutyl acrylate, dodecyl acrylate, butyl acrylate, isodecyl acrylate, dodecafluoroheptyl acrylate, hexahydro-4,7-methane-1H-indenyl acrylate, Acrylic acid or from the group consisting of acrylamide monomers, including N,N - dimethylacrylamide, isobutylmethylol acrylamide acrylate, 4-acryloylmorpholino, N-isopropylacrylamide, N,N-dimethylaminopropylacrylamide, N-hydroxyethylacrylamide, N,N-diethyl acrylamide, tris[2-(acryloyloxy)ethyl] isocyanurate.

Alternatively, the second monomer is selected from the group of monomers containing urethane groups and exhibiting (meth)acrylate functionality. Further features and advantages of the invention will become more apparent from the detailed description of some preferred, but not exclusive, embodiments of a method for three-dimensional printing of fiber composite materials according to the present invention.

Brief description of the drawings

This description will be set out below with reference to the attached drawings, provided for indicative purposes only and therefore not limiting, in which:

- Figures 1a-1c show three successive moments of the deposition phase of a continuous thread-like element of the method for three-dimensional printing of composite materials according to the present invention in which the energy source transmits energy directly to the continuous phase until the trigger temperature of a frontal polymerization reaction is reached;

- figures 2a-2c show three successive moments of the deposition phase of a continuous thread-like element of the method for three-dimensional printing of composite materials according to the present invention in which the energy source transmits energy to the dispersed phase which consequently increases its temperature transmitting heat to the continuous phase until the trigger temperature of a frontal polymerization reaction is reached;

-figures 3a-3c show three successive moments of the deposition phase of a continuous thread-like element of the method for three-dimensional printing of composite materials according to the present invention in which the energy source transmits energy to the dispersed phase, in the specific case in which the dispersed phase contains discontinuous or powdery material;

- Figure 4 shows an apparatus for three-dimensional printing of composite materials that implements the method according to the present invention.

Detailed description of embodiments of the invention

With reference to the figures, an apparatus for the three-dimensional printing of fibre composite materials is indicated in its entirety by the reference number 100. In particular, the apparatus 100 is suitable for printing a composite material starting from a continuous thread-like element 4 consisting of at least one continuous phase 2 and at least one dispersed phase 3.

Generally, the aforementioned at least one dispersed phase 3 comprises fiber material selected from carbon fibers, glass fibers, poly paraphenylene terephthalamide fibers, ultra high molecular weight polyethylene (UHWMPE) fibers, poly arylether ketone (PAEK) fibers, poly paraphenylene ? 2,6 ? benzobisoxazole fibers, poly ether sulfone (PES) fibers, beryllium fibers, tungsten fibers, carbon nanofibers, silicon carbide (SiC) fibers, boron fibers, polyimide (PI) fibers, poly benzoimidazole fibers, poly oxymethylene (POM) fibers, poly ether imide (PEI) fibers, metal alloy fibers, basalt fibers, natural fibers, and combinations thereof.

Generally, the fibers included in the dispersed phase 3 may be one or more continuous or long fibers joined together to form a continuous element or they may be short fibers (not joined together).

The dispersed phase 3 may also comprise, as in the case of figures 3a-3c, powdery material or in the form of nanostructures configured for specific tasks such as receiving energy, preferably by electromagnetic radiation, from a specific energy source 8 to raise the temperature of the dispersed phase 3 and/or of the continuous phase 2 in order to start a frontal polymerization reaction.

The powdery material is selected from carbon black, silicon dioxide, graphite, titanium oxide, boron nitride, zirconium oxide, calcium carbonate, calcium phosphate, molybdenum disulfide, lignin and their combinations.

The material in the form of nanostructures is chosen from graphene, single-walled carbon nanofibers, multi-walled carbon nanofibers, fullerene, clay nanoplates and their combinations.

Preferably, the continuous phase comprises at least a first compound comprising:

-a thermal initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %;

- a first monomer in an amount greater than or equal to about 20 mol % and less than or equal to about 99.9 mol %;

-a cationic initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %; and

-a first diluent in an amount greater than or equal to about 0 mol % and less than or equal to about 70 mol %.

Preferably, the thermal initiator is selected from the group consisting of: 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED), benzopinacol bistrimethylsilyl ether (TPED-Si), dimethylsulfonyl peroxide (DMSP), tert-butyl peroxide (TBPO), tert-butylcyclohexylperoxodicarbonate (TBC-PDC), benzoyl peroxide (BPO), azobis(isobutyronitrile) (AIBN) and combinations thereof. Preferably, the first monomer is selected from the group consisting of: 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED), benzopinacol bistrimethylsilyl ether (TPED-Si), dimethylsulfonyl peroxide (DMSP), tert-butyl peroxide (TBPO), tert-butylcyclohexylperoxodicarbonate (TBC-PDC), benzoyl peroxide (BPO), azobis(isobutyronitrile) (AIBN) and combinations thereof. selected from the group consisting of: bisphenol A diglycidyl ether (DGEBA), bisphenol F diglycidyl ether (DGEBF), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (CE), 4-vinyl-1-cyclohexane 1,2-epoxide, vinylcyclohexene dioxide, 4,5-epoxytetrahydrophthalic acid diglycidyl ester, glycidyl methacrylate, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, poly(ethylene glycol) diglycidyl ether, epoxidized soybean oil, N,N-diglycidyl-4-glycidyloxyaniline, bis3,4-epoxycyclohexylmethyl adipate, diglycidyl 1,2-cyclohexane dicarboxylate, allyl glycidyl ether, phenyl glycidyl ether, diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate, 4,4''-methylenebis[N,N-bis(2,3-epoxypropyl)aniline], tris(2,3-epoxypropyl) isocyanurate, m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, triethoxy(3-glycidyloxypropyl)silane, 1,2-epoxycyclohexane, tris(4-hydroxyphenyl)methane triglycidyl ether, epoxyphenolic resins (including those derived from novolacs), 9-[2-(2-methoxyethoxy)ethoxy]-9-[3-(oxiranylmethoxy)propyl]-2,5,8,10,13,16-hexaoxa-9-silaheptadecane, glycidyl stearate, resorcinol diglycidyl ether, 1,4-butanediol diglycidyl ether (BDGE), vinyl ethers, epoxy-phenolic resins (including those derived from dicyclopentadiene), carboxylic acid-functional acrylonitrile butadiene rubber (CTBN), epoxy-functional acrylonitrile butadiene rubber (ETBN) and combinations thereof; Preferably the cationic initiator is selected from [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium trieshafluorophosphate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate, (9-oxofluoren-2-yl)-pheniliodonium hexafluoroantimonate, [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium hexafluoroantimonate, [4-[(2-hydroxytetradecyl)oxy]phenyl]pheniliodonium hexafluoroantimonate, 4-octyloxydipheniliodonium hexafluoroantimonate, 10-(4-phenylphenyl)-2-propan-2-ylthioxanthen-10-io-9-one hexafluorophosphate, bis(4-dodecylphenyl)iodonium hexafluroranthomonate, bis-(4-t-butylphenyl)iodonium hexafluorophosphate, bis[4-(tert-butyl)phenyl]iodonium tetra(nonafluoro-tert-butoxy)aluminate, diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, diphenyliodonium hexafluorophosphate, bis(4-methylphenyl)iodonium hexafluorophosphate, (4-methylphenyl)[4-(propan-2-yl)phenyl]iodonium tetrakis(2,3,4,5,6-pentafluorophenyl) borate and combinations thereof.

Preferably, the diluent is selected from the group consisting of: polyfunctional glycidyl ethers, monofunctional aliphatic glycidyl ethers, monofunctional aromatic glycidyl ethers, 3-ethyl-3-oxetanomethanol (EOM), 3-methyl-3-oxetanomethanol, 1,4-bis(glycidyloxy)benzene (CHDGE), 1,6-hexanediol diglycidyl ether (HDDGE), neopentyl glycol diglycidyl ether (NPDGE), 1,4-butanediol diglycidyl ether (BDGE) and combinations thereof and the like.

In the continuous thread-like element 4, other additives and reinforcements may also be present.

According to another embodiment, the continuous thread-like element 4 and in particular its continuous phase 2 can comprise a photosensitizing material configured to receive energy administered by electromagnetic radiation 5 in the ultraviolet or visible spectrum from a specific energy source 8 so as to chemically activate said photosensitizer which in turn activates a cationic initiator to generate an exothermic reaction capable of raising the temperature of the continuous phase up to the trigger temperature of a frontal polymerization reaction.

Preferably, the photosensitizing material is present in an amount greater than or equal to about 0.001 mol % and less than or equal to about 5 mol %.

The photosensitizing material is selected from the group consisting of: anthracene, perylene, benzophenone, 9,10-diethoxyanthracene, 2,2-dimethoxy-2-phenylacetophenone, 2-isopropylthioxanthone (ITX), thioxanthen-9-one, vinylcarbazole and their combinations.

The apparatus 100 comprises a feeding head 7 for a continuous thread-like element 4, a support surface 9 on which the continuous thread-like element 4 is placed to create the object, preferably three-dimensional 20 to be printed, a relative movement group between the feeding head 7 and the support surface 9, so as to exert traction on the continuous thread-like element 4, an energy source 8 configured to supply the continuous thread-like element 4 with a predetermined amount of energy.

Specifically, the energy source 8 is configured to supply the continuous thread-like element 4 with a predetermined amount of energy such as to bring its continuous phase to an ignition temperature such as to trigger a frontal polymerization reaction front in the continuous phase itself.

The frontal polymerization reaction could be a RICFP <(>Radical Induced Cationic Frontal Polymerization) reaction. The rapid formation of molecular networks with a high degree of conversion (monomer-polymer conversion) that is obtained following frontal polymerization reactions, allows this type of reaction to be considered a valid alternative to traditional processes used in the production of polymer matrix composite materials. In addition, frontal polymerization reactions exploit the heat generated by the reaction itself to generate a self-propagating reaction front, making it more energetically efficient and the reaction products more homogeneous.

The feed head 7 is advantageously supported by a movement group for the relative movement between the feed head 7 itself and the object 20 to be printed.

During the feeding of the continuous thread-like element 4, the movement group exerts a traction force on the continuous thread-like element 4 and therefore also on the continuous fibres contained therein.

As a result, this tensile force is also transferred to the fibers.

Note that this pulling force causes the same continuous thread-like element 4 to be fed into the feed head 7.

Consequently, the higher the relative speed, the faster the advancement of the continuous thread-like element 4.

According to an alternative embodiment, the continuous thread-like element 4 is fed by extruding it from the feed head 7.

Advantageously, the continuous thread-like element 4 is fed by extruding it if the dispersed phase 3 comprises discontinuous, powdery fibres or nanostructures.

In further detail, the means of movement include at least one machine with numerically controlled movement on at least three axes.

According to a first embodiment not shown in the figures, the numerically controlled machine comprises a motorized arm 23 to support the above-mentioned feeding head 7 at a respective end portion.

The motorized arm 23, which is not described or illustrated in detail as it is of a known type, is capable of moving the head in at least three spatial axes, orienting the feed head to any position with respect to the object 20.

Note that the support surface 9, which is arranged under the feed head 7, can, in turn, be movable towards/away from the feed head 7. Said support surface 9 can be constituted by said continuous thread-like element 4 previously deposited during the production of the three-dimensional object 20.

According to a first embodiment, shown in figures 1a-1c, the energy source 8 can be constituted by a heat emission source intended to heat the continuous thread-like element 4.

Energy sources 8 of this type are generally based on the supply of a flow of hot air 5.

Alternatively, the energy source 8 may be a source of electromagnetic radiation (fig 2a-2c; 3a-3c). In this case, the energy source 8 may for example consist of at least one source of electromagnetic radiation in the infrared or ultraviolet range depending on the type of material the continuous thread-like element 4 is made of.

The energy source 8 is positioned downstream of the power head and is configured to deliver energy to the continuous wire element 4 at the support surface 9.

In any case, the energy source 8 is configured to transfer energy to the continuous thread-like element 4 or to at least one phase thereof substantially throughout the deposition process and at different points of the deposition element itself.

In other words, the energy source 8 is configured to repeatedly subject the continuous thread-like element 4 during its deposition to a predetermined amount of energy.

According to an alternative embodiment, the energy source 8 is configured to continuously subject the continuous thread-like element 4, during its deposition, to a predetermined amount of energy; as shown for example in figures 1a-3c. It should be noted that said amount of energy may not be constant during the deposition phase. Conveniently, said amount of energy may be modulated as a function of the speed of said relative movement.

The energy supply to the continuous thread-like element 4 occurs during the deposition of the continuous thread-like element 4 on the support surface 9 according to a precise path of the continuous thread-like element 4, therefore, occurs at different points of the continuous thread-like element 4 itself, thus supporting the frontal polymerization reaction.

In the embodiment shown in the figures, preferably upstream of the energy source 8 there is a cutting member, not shown in the figures, which can be represented by at least one blade moving towards/away from the energy source 8 to cut the continuous thread-like element 4.

According to this embodiment, the cutting member acts on the continuous thread-like element 4 after applying a part of it to the support surface 9.

The present invention relates to a method for three-dimensional printing of composite materials having at least one dispersed phase, comprising at least one preferably thermally conductive material, and at least one continuous reacting phase by means of frontal polymerization reactions which comprises the steps of:

-feed at least one continuous thread-like element 4 to a feed head 7; and;

-depositing said continuous thread-like element 4 on a support surface 9; -subjecting the continuous thread-like element 4 to an amount of energy such as to bring said at least one continuous phase to an ignition temperature so as to trigger a frontal polymerization reaction front in said at least one continuous phase; the polymerization reaction could be a RICFP (Radical Induced Cationic Frontal Polymerization) type reaction. The rapid formation of molecular networks with a high degree of conversion (monomer-polymer conversion) that is obtained following RICFP frontal polymerization reactions allows this type of reaction to be considered a valid alternative to traditional processes used in the production of polymer matrix composite materials. In addition, RICFP frontal polymerization reactions exploit the heat generated by the reaction itself to form a self-propagating reaction front, making it more energetically efficient and the reaction products more homogeneous.

<- >Administer to said continuous thread-like element 4 said quantity of energy repeatedly and in different positions along its extension determining the triggering of more than one frontal polymerization front during the deposition phase.

The feeding and deposition phases are carried out by exerting a drag force on the continuous thread-like element 4 created by relative movement between the feeding head 7 and the three-dimensional object 20 to be printed or between the feeding head 7 and the support surface 9.

In other words, by moving the feeding head 7 by means of the action of the numerically controlled machine, the continuous thread-like element 4 is gradually deposited on the support surface 9 or on a previously made portion of said three-dimensional object 20 which is produced by means of the feeding of the continuous thread-like element 4.

In some cases, the continuous thread-like element 4 is fed by extruding it from the feed head 7.

In more detail, to carry out the printing process, the continuous thread-like element 4 coming out of the nozzle of the feed head 7 is initially distributed on the respective support surface 9.

At this point, the continuous thread-like element 4 and in particular its end resting on the support surface 9 is hit by a predetermined amount of energy such as to trigger a frontal polymerization front and create an anchoring point between the continuous thread-like element 4 and the support surface 9.

The deposition of the continuous thread-like element 4 can therefore progress according to predefined paths and trajectories aimed at forming the three-dimensional object 20 to be printed.

The anchor point thus formed allows the continuous thread-like element 4 to arrange itself on the support surface 9 according to a precise path and to draw, while the numerically controlled machine moves, the object to be printed 20. The feed head 7 is thus moved by the numerically controlled machine according to a predetermined path that defines the object 20 to be printed.

This path is determined by suitable management software which is not described in this description as it is outside the scope of the invention. At the end of the printing process, or in any case when the continuous feeding of the continuous wire element 4 must be interrupted, the wire element or a derivative thereof is cut by the cutting mechanism.

The transformation of the continuous thread-like element 4 into composite material is initially triggered in the vicinity of the anchoring point between the support surface 9 and the continuous thread-like element 4 (figs.1a,2a,3a).

In all cases, the transformation occurs by supplying a predetermined amount of energy to the continuous thread-like element 4, capable of increasing the temperature of the continuous phase until the trigger temperature of frontal polymerization reactions is reached.

In particular, if the continuous thread-like element 4 does not have a dispersed phase capable of effectively increasing its temperature once subjected to energy through electromagnetic radiation, such as glass fibres, silicon oxide, zirconium oxide, the energy that strikes the continuous thread-like element 4 is advantageously supplied through the use of energy sources operating by convection or conduction.

In this case, the supplied heat causes the temperature of the continuous phase to rise directly above the trigger temperature of a frontal polymerization reaction. Preferably, the polymerization reaction is a RICFP (Radical Induced Cationic Frontal Polymerization) type reaction.

When the temperature of the continuous phase 2 is equal to or greater than the initiation temperature, a frontal polymerization reaction is triggered which is capable of propagating inside the continuous thread-like element 4.

The deposition of the continuous thread-like element 4 according to the preset trajectory subsequently shifts the point of application of the energy in the form of heat, generating subsequent triggers of frontal polymerization reactions (fig. 1b), thus resulting in an overall frontal polymerization reaction which thus propagates and sustains itself at a speed comparable to that of the deposition of the continuous thread-like element 4.

The application of energy to the continuous thread-like element 4 can occur at very close time intervals or in a continuous manner, as shown for example in figures 1a-3c.

Preferably, the application of energy in the form of heat to the thread-like element occurs throughout the deposition phase of the continuous thread-like element 4.

Alternatively, if the continuous thread-like element 4 has a dispersed phase capable of effectively increasing its temperature when subjected to energy by electromagnetic radiation, such as carbon fibre, basalt fibre, carbon black, graphene, carbon nanotubes, carbon nanofibres, metal alloys, advantageously the energy striking the continuous thread-like element 4 is supplied by electromagnetic radiation, preferably emitted by a source of electromagnetic radiation in the infrared or visible spectrum.

In this case, as in the examples of figures 2a-3c, the energy 5 supplied by the energy source 8 raises the temperature of the dispersed phase 3 which, preferably by conduction, increases the temperature of the continuous phase so as to bring it above a trigger temperature of a frontal polymerization reaction.

When the temperature of the continuous phase 2 is equal to or greater than the initiation temperature, a frontal polymerization reaction is triggered, capable of propagating inside the continuous thread-like element 4.

The deposition of the continuous thread-like element 4 according to the preset trajectory subsequently shifts the point of application of the energy, generating subsequent triggers of frontal polymerization reactions, thus resulting in an overall frontal polymerization reaction which thus propagates and sustains itself at a speed comparable to that of the deposition of the continuous thread-like element 4.

The application of energy to the continuous thread-like element 4 can occur at very close time intervals or continuously.

Preferably, the application of energy in the form of heat to the wire element occurs throughout the deposition phase of the continuous wire element 4.

Alternatively, if the continuous thread-like element 4 has a continuous phase comprising a sensitizer, such as 2-isopropylthioxanthone, thioxanthen-9-one, vinylcarbazole, the energy striking the continuous thread-like element 4 is administered by electromagnetic radiation preferably emitted by an electromagnetic radiation source and chosen in the ultraviolet or visible spectrum.

In this case, the supplied energy chemically activates the sensitizer which in turn activates a cationic initiator to generate an exothermic reaction capable of raising the temperature of the continuous phase to the initiation temperature of a frontal polymerization reaction.

The invention, as can be clearly deduced from the above description, allows to overcome the limitations of the three-dimensional moulding processes of known fibre composite materials in terms of materials and/or processes that can be used.

Furthermore, known alternative polymerization mechanisms (e.g. frontal polymerization) conveniently employed for the production of composite materials with a high degree of homogeneity, the present invention is able to allow overcoming the limited obtainable process speeds, intrinsic to these types of chemical reactions. Therefore, the present invention is proposed as an enabling solution for the effective use of these types of monomers and chemical reactions within three-dimensional molding processes of fiber composite materials. Various modifications can be made to the embodiments described in detail, while remaining within the scope of protection of the invention, defined by the following claims.

Claims (25)

1. Method for three-dimensional printing of composite materials, comprising the steps of: -feeding at least one continuous thread-like element (4) to a feed head (7); said continuous thread-like element (4) comprising at least one dispersed phase and comprising at least one continuous reacting phase by means of frontal polymerization reactions; -depositing said continuous thread-like element (4) on a support surface (9); -subjecting said continuous thread-like element (4) to an amount of energy (5) such as to bring said at least one continuous phase (2) to an ignition temperature so as to trigger a frontal polymerization reaction front in said at least one continuous phase; -administer to said continuous thread-like element (4) said quantity of energy repeatedly and in different positions along its extension, during the deposition phase, so as to trigger different polymerization fronts. 2. Method for three-dimensional printing of fibre composite materials according to claim 1, characterised in that said quantity of energy (5) is applied directly to said continuous phase (2). 3. Method for three-dimensional printing of fibre composite materials according to claim 1, characterised in that said quantity of energy (5) is applied to said dispersed phase (3) so as to bring said at least one continuous phase (2) to said ignition temperature. 4. Method for three-dimensional printing of fibre composite materials according to any of claims 1 to 3, characterised in that it comprises: -distributing at least one end of the continuous thread-like element (4) on a respective support surface (9); -subjecting said end of said continuous thread-like element (4) to said quantity of energy (5) such as to bring said at least one continuous phase (2) to an ignition temperature so as to trigger a frontal polymerization reaction front in said at least one continuous phase (2); -move said feed head (7) with respect to the anchor point according to a pre-established path that defines the object to be printed (20). 5. A method for three-dimensional printing of fiber composite materials according to any of the preceding claims 1 to 4, characterized in that said feeding and deposition steps are implemented by exerting a traction force on the continuous thread-like element (4) by relative movement between a respective feeding head (7) and said support surface (9) or by extrusion of the continuous thread-like element (4). 6. A method for three-dimensional printing of composite materials according to any of the preceding claims 1 to 5, characterized in that said at least one dispersed phase (3) comprises fiber material selected from carbon fibers, glass fibers, poly paraphenylene terephthalamide fibers, ultra high molecular weight polyethylene (UHWMPE) fibers, poly arylether ketone (PAEK) fibers, poly paraphenylene ? 2,6 ? benzobisoxazole fibers, poly ether sulfone (PES) fibers, beryllium fibers, tungsten fibers, carbon nanofibers, silicon carbide (SiC) fibers, boron fibers, polyimide (PI) fibers, poly benzoimidazole fibers, poly oxymethylene (POM) fibers, poly ether imide (PEI) fibers, metal alloy fibers, basalt fibers, natural fibers, and combinations thereof. 7. Method for three-dimensional printing of composite materials according to claim 1 to 6, characterized in that said at least one dispersed phase (3) comprises powdery material or in the form of nanostructures; said powdery material being selected from carbon black, silicon dioxide, graphite, titanium oxide, boron nitride, zirconium oxide, calcium carbonate, calcium phosphate, molybdenum disulfide, lignin and combinations thereof; said material in the form of nanostructures being selected from graphene, single-walled carbon nanotubes, multi-walled carbon nanotubes, fullerene, clay nanoplates and combinations thereof. 8. Method for three-dimensional printing of composite materials according to any of the preceding claims 1 to 7, characterised in that said continuous phase (2) comprises at least a first compound comprising: -a thermal initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %; - a first monomer in an amount greater than or equal to about 20 mol % and less than or equal to about 99.9 mol %; -a cationic initiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %; and -a first diluent in an amount greater than or equal to about 0 mol % and less than or equal to about 70 mol %. 9. Method for three-dimensional printing of composite materials according to claim 8, characterised in that: - said thermal initiator is selected from the group consisting of: 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED), benzopinacol bistrimethylsilyl ether (TPED-Si), dimethylsulfonyl peroxide (DMSP), tert-butyl peroxide (TBPO), tert-butylcyclohexylperoxodicarbonate (TBC-PDC), benzoyl peroxide (BPO), azobis(isobutyronitrile) (AIBN) and combinations thereof; -the monomer? selected from the group consisting of: bisphenol A diglycidyl ether (DGEBA), bisphenol F diglycidyl ether (DGEBF), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (CE), 4-vinyl-1-cyclohexane 1,2-epoxide, vinylcyclohexene dioxide, 4,5-epoxytetrahydrophthalic acid diglycidyl ester, glycidyl methacrylate, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, poly(ethylene glycol) diglycidyl ether, epoxidized soybean oil, N,N-diglycidyl-4-glycidyloxyaniline, bis3,4-epoxycyclohexylmethyl adipate, diglycidyl 1,2-cyclohexane dicarboxylate, allyl glycidyl ether, phenyl glycidyl ether, diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate, 4,4''-methylenebis[N,N-bis(2,3-epoxypropyl)aniline], tris(2,3-epoxypropyl) isocyanurate, m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline, triethoxy(3-glycidyloxypropyl)silane, 1,2-epoxycyclohexane, tris(4-hydroxyphenyl)methane triglycidyl ether, epoxyphenolic resins (including those derived from novolacs), 9-[2-(2-methoxyethoxy)ethoxy]-9-[3-(oxiranylmethoxy)propyl]-2,5,8,10,13,16-hexaoxa-9-silaheptadecane, glycidyl stearate, resorcinol diglycidyl ether, 1,4-butanediol diglycidyl ether (BDGE), vinyl ethers, epoxy-phenolic resins (including those derived from dicyclopentadiene), carboxylic acid-functional acrylonitrile butadiene rubber (CTBN), epoxy-functional acrylonitrile butadiene rubber (ETBN) and combinations thereof, -the cationic initiator? selected from the group consisting of: [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium trieshafluorophosphate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate, (9-oxofluoren-2-yl)-pheniliodonium hexafluoroantimonate, [4-(4-diphenylsulfoniophenyl)sulfonylphenyl]-diphenylsulfonium hexafluoroantimonate, [4-[(2-hydroxytetradecyl)oxy]phenyl]pheniliodonium hexafluoroantimonate, 4-octyloxydipheniliodonium hexafluoroantimonate, 10-(4-phenylphenyl)-2-propan-2-ylthioxanthen-10-io-9-one hexafluorophosphate, bis(4-dodecylphenyl)iodonium hexafluroranthomonate, bis-(4-t-butylphenyl)iodonium hexafluorophosphate, bis[4-(tert-butyl)phenyl]iodonium tetra(nonafluoro-tert-butoxy)aluminate, diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, diphenyliodonium hexafluorophosphate, bis(4-methylphenyl)iodonium hexafluorophosphate, (4-methylphenyl)[4-(propan-2-yl)phenyl]iodonium tetrakis(2,3,4,5,6-pentafluorophenyl) borate and combinations thereof; and - said diluent is selected from the group consisting of: polyfunctional glycidyl ethers, monofunctional aliphatic glycidyl ethers, monofunctional aromatic glycidyl ethers, 3-ethyl-3-oxetanomethanol (EOM), 3-methyl-3-oxetanomethanol, 1,4bis(glycidyloxy)benzene (CHDGE), 1,6-hexanediol diglycidyl ether (HDDGE), neopentyl glycol diglycidyl ether (NPDGE), 1,4-butanediol diglycidyl ether (BDGE) and combinations thereof. 10. Method for three-dimensional printing of composite materials according to any of the preceding claims 1 to 9, characterised in that said continuous phase (2) comprises at least one photosensitising material. 11. A method for three-dimensional printing of composite materials according to claim 10, characterized in that said photosensitizing material is present in an amount greater than or equal to about 0.001 mol % and less than or equal to about 5 mol %. 12. A method for three-dimensional printing of composite materials according to claim 10 or 11, characterised in that said photosensitizing material is selected from the group consisting of: anthracene, perylene, benzophenone, 9,10-diethoxyanthracene, 2,2-dimethoxy-2-phenylacetophenone, 2-isopropylthioxanthone (ITX), thioxanthen-9-one, vinylcarbazole and combinations thereof. 13. Method for three-dimensional printing of composite materials according to any of the preceding claims 1 to 12, characterised in that said energy (5) is supplied by means of electromagnetic radiation sources (8). 14. Method for three-dimensional printing of composite materials according to any of claims 1 to 12, characterised in that said energy (5) is supplied by energy sources operating by convection (8). 15. Method for three-dimensional printing of composite materials according to any of claims 1 to 13, characterised in that said energy (5) is supplied by electromagnetic radiation in the infrared spectrum. 16. Method for three-dimensional printing of composite materials according to any of claims 1 to 13, characterised in that said energy (5) is supplied by electromagnetic radiation in the ultraviolet spectrum. 17. A method for three-dimensional printing of composite materials according to any of claims 1 to 16, characterised in that said continuous phase (2) comprises at least a second compound comprising: -a photoinitiator in an amount greater than or equal to about 0.001 mol % and less than or equal to about 10 mol %; - a second monomer in an amount greater than or equal to about 20 mol % and less than or equal to about 99.9 mol %. 18. A method for three-dimensional printing of composite materials according to claim 17, characterized in that said second compound further comprises: -a compound with synergistic action in an amount greater than 0 mol % and less than or equal to approximately 50 mol %; -a second diluent in an amount greater than 0 mol % and less than or equal to approximately 70 mol %. 19. A method for three-dimensional printing of composite materials according to claim 17 or 18, characterized in that said second compound is present in an amount greater than or equal to 0.1mol% and less than or equal to 20 mol%. 20. A method for three-dimensional printing of composite materials according to any of claims 17 to 19, characterised in that said second compound is subjected to a preliminary polymerisation step upstream of the feed head (7). 21. A method for three-dimensional printing of composite materials according to any of claims 17 to 20, characterized in that said second diluent is selected from the group consisting of: neopentyl acrylate, 3-methyl-1,5-pentadiol diacrylate, 1,6-hexanediol diacrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate and combinations thereof. 22. A method for three-dimensional printing of composite materials according to any of claims 17 to 21, characterized in that said synergistic action compound is selected from the group consisting of molecules exhibiting amine groups including triethylamine, tri-N-butylamine, 2-dimethylaminoethanol, N-methyldiethanolamine, triethanolamine, 2-(dimethylamino)ethyl benzoate, ethyl 4-(dimethylamino)benzoate, 2-ethylhexyl-4-dimethylamino-benzoate, isoamyl 4-(dimethylamino)? benzoate, 2-butoxyethyl 4-(dimethylamino)-benzoate, N-phenylglycine, 4,4',4''-tris(dimethylamino)-triphenylmethane and combinations thereof or from the group consisting of molecules exhibiting thiol groups, including butyl 3-mercaptopropionate, trimethylolpropanetris(2-mercaptoacetate), trimethylolpropane - tris(2-mercaptopropionate), 2-benzothiazolethiol, 2-benzimidazolethiol, 1,6-hexane bis(3-mercaptopropionate), di[trimethylolpropane tris(3-mercaptopropionate)], pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-butanediyl bis(3-mercaptobutyrate), trimethylol propane tris(3-mercaptobutyrate) and combinations thereof 23. A method for three-dimensional printing of composite materials according to any of claims 17 to 22, characterized in that said photoinitiator is selected from the group consisting of: 2-hydroxy-2-methyl-propiophenone, 2,2-dimethy-2-hydroxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-hydroxy-2-methyl-4'-tert-butyl-propiophenone, 2 -hydroxy-2-methyl-1-(4-tertbutylphenyl)-propanone, 1-hydroxycyclohexylphenylketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophenone, 2-hydroxy-[4'-(2 -hydroxypropoxy)]-2-methylpropiophenone, 2-hydroxy-[4'-(2-hydroxypropoxy)phenyl]-2methylpropanone, oligo 2-hydroxy-2-methyl-1-[4-(1-methyl-vinyl)phenyl] propanone, 2-hydroxy-1-[4[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl]-2-methyl-propane-1-one, 2-methyl-4'-(methylthio)- 2-morpholino-propiophenone, 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone, 2-(4-methylbenzyl)-2-(dimethylamino)-4-morpholinobutyrophenone, 2,2-dimethoxy-2-phenyl-acetophenone, 2,2-diethoxy-2-phenyl-acetophenone, 2,2-diethoxy-1-phenylethanone diethoxyacetophenone, 2-isopropoxy-2-phenylacetophenone, 2-n-butoxy-2-phenylacetophenone, 2-isobutoxy-2-phenylacetophenone, bis(2,4,6-trimethylbenzoyl)-(2,4-bis-pentyloxyphenyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl-bis-(2,4,6-trimethylbenzoyl)phosphine oxide, 4'-(tert.butyl)-2,2,2-trichloroacetophenone, 4'-(phenoxy)-2,2-dichloroacetophenone, 2-(4 -methoxyphenyl)-4,6-bis-(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine, 2,4-bis(trichloromethyl)-6-(3,4-dimethoxy)-styryl-s-triazine, 2,4-bis(trichloromethyl)-6-(3,4-dimethoxy)-styryl-striazine, 1- phenyl-1,2-propandione-2-(o-ethoxy-carbonyl) oxime, 1-[4-(phenylthio)phenyl]-octane-1,2-dione-2-(o-benzoyloxime), benzophenone, 4- methylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, benzophenone-2-carboxy-(tetraethoxy)acrylate, 4-phenylbenzophenone, methyl 2-benzoylbenzoate, 1-{-4-[benzoylphenylsulfo]phenyl}-2-methyl-2-(4-methylphenylsulfonyl)-propan-1-one, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2, 4-Dimethylthioxanthone, 1-Chloro-4-propoxythioxanthone, 2,4-Diisopropylthioxanthone, Methyl phenylglyoxylate, 2-Ethylanthraquinone, 2-Ethyl-9,10-anthracene dione, Polyethylene glycol-bis-[(4-acetylphenyl)-piperazine propionate] , 3-benzoyl-7-methoxy-2H-chromen-2-one and their combinations ; 24. A method for three-dimensional printing of composite materials according to any of claims 17 to 23, characterized in that said second monomer is? selected from the group consisting of monomers exhibiting (meth)acrylate groups, including: tricyclodecane dimethanol diacrylate, 3-[2,2-dimethyl-1-oxo-3-[(1-oxo-2-propenyl)oxy]propoxy]-2,2-dimethylpropyl acrylate, dihydro dicyclopentadienyl acrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, dipropylene glycol diacrylate, ditrimethylol propane tetraacrylate, isobornyl acrylate, dipentaerythritol hexacrylate, tert-butyl acrylate, trimethylol propane triacrylate, tripropylene glycol diacrylate, bisphenol A diacrylate n-ethoxylate (with 1< n < = 10), bisphenol A diacrylate, 3,3,5-trimethylcyclohexyl acrylate, (5-ethyl-1,3dioxan-5-yl)methyl acrylate, trimethylol propane triacrylate n ethoxylate (with 1< n < = 10), neopentyl glycol diacrylate, triethylene glycol diacrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobutyl acrylate, dodecyl acrylate, butyl acrylate, isodecyl acrylate, dodecafluoroheptyl acrylate, hexahydro-4,7-methane-1H-indenyl acrylate, Acrylic acid or from the group consisting of acrylamide monomers, including N,N - dimethylacrylamide, isobutylmethylol acrylamide acrylate, 4-acryloylmorpholino, N-isopropylacrylamide, N,N-dimethylaminopropylacrylamide, N-hydroxyethylacrylamide, N,N-diethyl acrylamide, tris[2-(acryloyloxy)ethyl] isocyanurate and their combinations. 25. A method for three-dimensional printing of composite materials according to any of claims 17 to 24, characterized in that said second monomer is selected from the group of monomers containing urethane groups and exhibiting (meth)acrylate functionality.