Process for manufacturing a crosslinked resin composition from a mixture obtained by depolymerizing polystyrene

Abstract

Title: Method for manufacturing a crosslinked resin composition from a mixture resulting from a depolymerization of polystyrene The present invention relates to a method for manufacturing a crosslinked resin composition comprising particular steps a) and b), implementing a resin composition comprising a photocrosslinkable resin comprising a reactive diluent selected from at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene.

Description

Title of the invention: Process for manufacturing a crosslinked resin composition from a mixture obtained by depolymerizing polystyrene. Technical field

[0001] The present invention relates to the field of resin compositions and composites, such as filament-resin composite monostrands. In particular, the present invention relates to the field of manufacturing processes for resin compositions using a mixture resulting from the depolymerization of polystyrene compounds.

[0002] The production of plastic products increases year after year to meet ever-growing consumer demand. Their use generates plastic waste, and their disposal can lead to environmental pollution, for example, in the air and groundwater. One example of a plastic product is polystyrene, which is manufactured in very large quantities from its monomer, styrene. Styrene is increasingly viewed negatively, to the point that bans on non-recyclable polystyrene packaging are being considered by various jurisdictions. Consequently, its recycling for reuse is of great interest.

[0003] This issue is part of a broader effort to reduce carbon dioxide emissions, and the use of recycled materials is one way to achieve this. In processes involving polystyrene recycling, additives and stabilizers are often added to improve its subsequent use and processing. It is therefore difficult to obtain a pure product from a recycling process. This has a negative impact, particularly on the mechanical properties of materials incorporating recycled products, for example, products resulting from polystyrene depolymerization.

[0004] Among products using styrene, composite reinforcements based on filament-resin composite monostrands, well known to those skilled in the art, can be cited. An example of such a reinforcement, described in particular in patent EP 1,167,080 (or US 7,032,637), is that of glass-resin composite monostrands (“CVR” for short) which exhibit high mechanical properties. The monostrands comprise continuous, unidirectional glass fibers impregnated in a crosslinked vinyl ester resin.

[0005] Indeed, (photo)curable resins are used in these composite reinforcements. These (photo)curable resins are generally sold in the trade with a reactive diluent, which is often styrene, at a content of up to about 50% by weight of the resin (photo jcrossable.

[0006] It would therefore be desirable to find an alternative to this use of styrene in resins (photo j crosslinkable. Description of the invention

[0007] Continuing its research, the Applicant unexpectedly discovered that a manufacturing process for a crosslinked resin composition using a mixture resulting from the depolymerization of styrenic compounds made it possible to obtain composites, incorporating these crosslinked resin compositions, exhibiting undegraded properties, both in terms of mechanical properties and glass transition temperature.

[0008] The present invention therefore relates to a method for manufacturing a crosslinked resin composition comprising the following successive or simultaneous steps a) and b):

[0009] a) expose at least one resin composition to UV radiation in a UV irradiation chamber,

[0010] said resin composition comprising:

[0011] - at least one photocurable resin comprising at least one selected reactive diluent among at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene;

[0012] - a crosslinking system comprising at least one photoinitiator; and

[0013] - optionally a crosslinking agent other than the photoinitiator;

[0014] b) heat said resin composition to a temperature in the range of 80°C to 350°C, said temperature being higher than the glass transition temperature of the resin after polymerization.

[0015] The invention also relates to a crosslinked resin composition that can be obtained by the manufacturing process according to the invention.

[0016] Another object of the invention is a composite based on at least one reinforcing element and said crosslinked resin composition, as well as a method for manufacturing a single strand of filament-resin composite comprising filaments embedded in a crosslinked resin.

[0017] In this application, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0018] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these constituents being able to react and / or intended to react with each other, at least partially, during the various manufacturing phases of the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0019] By "embedded", it is meant that the reinforcing element is directly in contact with the resin composition over its entire surface, with the possible exception of the cutting areas of the composite.

[0020] By "resin composition", we mean here the resin as such or any composition based on this resin and comprising at least one additive (i.e. one or more additives) before crosslinking.

[0021] By "crosslinked" resin or "crosslinked" resin composition, it is understood that the resin is hardened (photocured and / or thermocured), in other words in the form of a network of three-dimensional bonds, in a state characteristic of so-called thermosetting polymers (as opposed to so-called thermoplastic polymers).

[0022] In this application, the term "fibre" is equivalent to the term "monofrain". Thus, the two terms may be used interchangeably.

[0023] By "mostly styrene", it is meant here that styrene is present at more than 50% by mass in the mixture considered.

[0024] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from greater than a to less than b (i.e., excluding the bounds a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict bounds a and b). In the present case, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated. Brief description of the figures

[0025] [Fig-1] Fig. 1 represents a diagram of the single-strand synthesis process according to the invention before the latter is cut to a predetermined length.

[0026] [Fig. 2] Fig. 2, not drawn to scale for ease of understanding, is a drawing representing a cross-section of the single strand according to the invention. Description of the invention

[0027] As previously stated, the manufacturing process according to the invention includes, in particular, step a) as defined above, with a resin composition comprising:

[0028] - at least one photocurable resin comprising at least one selected reactive diluent among at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene;

[0029] - a crosslinking system comprising at least one photoinitiator; and

[0030] - optionally a crosslinking agent other than the photoinitiator.

[0031] The photocurable resin can be any resin capable of crosslinking in the presence of a photoinitiator under the action of light radiation, in particular ultraviolet or visible light. Preferably, the photocurable resin is a UV-curable resin.

[0032] The photocurable resin is advantageously chosen from the group consisting of vinyl ester, epoxy, polyester, novolac resins and their mixtures, preferably from the group consisting of vinyl ester, epoxy resins and their mixtures, more preferably from the group consisting of vinyl ester resins and their mixtures.

[0033] The term "polyester" resin is commonly understood to mean an unsaturated polyester resin. "Vinylester" resins, on the other hand, are well known in the field of composite materials.

[0034] Without this definition being limiting, the vinyl ester resin is preferably of the epoxy vinyl ester type. A vinyl ester resin, in particular of the epoxy type, is more preferably used, which at least in part is based on (i.e. grafted onto a structure of the type) novolac (also called phenoplast) and / or bisphenolic, or preferably a vinyl ester resin based on novolac, bisphenolic, or novolac and bisphenolic.

[0035] A novolac-based epoxyvinylester resin (part in brackets in formula I below) corresponds, for example, in a known manner, to the following formula (I):

[0036] A bisphenol A-based epoxyvinylester resin (part in brackets of formula (II) below) corresponds, for example, to the formula (the "A" indicating that the product is manufactured using acetone):

[0037] A novolac- and bisphenolic-type epoxyvinylester resin has shown excellent results. As an example of such a resin, the "MIRAMER PE250" vinyl ester resin from Miwon may be cited in particular.

[0038] As previously stated, the reactive diluent is chosen from at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene.

[0039] The depolymerization of polystyrene can be carried out by any method known to those skilled in the art. Various methods exist, such as those involving the use of microwave technology, for example, as described in application WO 2018 / 018153 A1. Other approaches have been explored, such as those described in applications US 2021 / 0277202 and WO 2024 / 003021. Thus, all the steps involved in the polystyrene depolymerization process have been described in these applications.

[0040] Thus, at the end of the depolymerization of polystyrene, the mixture obtained consists mainly of styrene, the monomer of polystyrene.

[0041] Advantageously, the styrene content in said mixture is less than or equal to 99% by weight, preferably is in the range of 90% to 99% by weight, more preferably of 95% to 99% by weight relative to the total weight of said mixture.

[0042] Said mixture resulting from the depolymerization of polystyrene may further comprise at least one compound other than styrene, preferably chosen from ethylbenzene, benzene, cumene, alpha-methyl styrene and mixtures thereof.

[0043] Preferably, the content of said compound(s) other than styrene, while remaining at a level less than or equal to the content of styrene by weight of said mixture, is greater than or equal to 1% by weight by weight of said mixture. Advantageously, the content of said compound(s) other than styrene is in the range of 1% to 10% by weight, preferably from 1% to 5% by weight by weight of the total mixture.

[0044] The rate of reactive diluent may be in the range of 15% to 40% by weight, preferably 20% to 35% by weight relative to the total weight of the resin composition.

[0045] As is known, a photoinitiator is a molecule that creates reactive species such as free radicals, cations, or anions when exposed to ultraviolet or visible radiation. Particularly advantageously, the photocurable resin is a UV-curable resin, and the photoinitiator is a UV-reactive photoinitiator above 300 nm, preferably between 300 and 450 nm.

[0046] For the purposes of the invention, particularly when the photocurable resin is chosen from the group consisting of vinyl ester, epoxy, polyester, novolac resins and mixtures thereof, the photoinitiator is preferably chosen from the group consisting of type I photoinitiators and mixtures thereof. The photoinitiator may also be a photoinitiator that is not a type I photoinitiator, for example a type II or other photoinitiator, but this is not preferred.

[0047] Type I photoinitiators are chosen from the group consisting of benzoine ethers, benzyl ketals, alpha-dialkoxyacetophenones, alpha-hydrody- alkyl-phenones, alpha-amino-alkyl-phenones, phosphine oxides and their mixtures.

[0048] Advantageously, the photoinitiator is chosen from the group consisting of phosphine oxides and mixtures thereof, preferably from the group consisting of mono(acyl)phosphine oxides, bis(acyl)phosphine oxides, and mixtures thereof. The phosphine oxide may advantageously be a bis(acyl)phosphine oxide.

[0049] By way of example of a photoinitiator usable within the scope of the present invention, one may cite bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (“Omnirad 819” from IGM or “speedcureBPO” from Lambson) or a mono(acyl)phosphine oxide (for example, “Esacure TPO” from IGM), such phosphine compounds being able to be used in mixture with other photoinitiators, for example, alpha-hydroxy-ketone type photoinitiators such as dimethylhydroxy-acetophenone (e.g., “Omnirad 1173” from IGM) or 1-hydroxy-cyclohexyl-phenyl-ketone (e.g., “Omnirad 184” from IGM), benzophenones such as 2,4,6-trimethylbenzophenone (e.g., “Esacure TZT” from IGM) and / or derivatives of thioxanthones such as isopropylthioxanthone (e.g., "Esacure Omnirad ITX" from IGM).

[0050] The photoinitiator content is advantageously within a range of 0.5% to 2.5% by weight, preferably 1% to 2% by weight relative to the total weight of the resin composition.

[0051] As an example of a crosslinking agent other than the photoinitiator, we can cite multifunctional acrylate or methacrylate derivatives and peroxides well known to those skilled in the art.

[0052] The crosslinking agent, other than the photoinitiator, may be chosen from the group consisting of multifunctional (meth)acrylates and their mixtures, preferably from the group consisting of tri(meth)acrylates and their mixtures. In particular, the crosslinking agent may be chosen from the group consisting of the triacrylate family.

[0053] As an example of a crosslinking agent other than the photoinitiator, we can cite multifunctional acrylate or methacrylate derivatives and peroxides well known to those skilled in the art.

[0054] The crosslinking agent, other than the photoinitiator, may be chosen from the group consisting of multifunctional (meth)acrylates and mixtures thereof, preferably from the group consisting of tri(meth)acrylates and mixtures thereof. In particular, the crosslinking agent may be chosen from the group consisting of the triacrylate family.

[0055] Advantageously, the crosslinking agent ratio is in a range from 0% to 15%, for example from 5% to 15% by weight relative to the weight of the resin composition.

[0056] Alternatively, the crosslinking agent content may be less than 4% by weight, preferably less than or equal to 2% by weight, more preferably less than 1% by weight relative to the total weight of the resin composition.

[0057] According to one embodiment, the resin composition is free of crosslinking agent, other than a photoinitiator.

[0058] As previously stated, the manufacturing process according to the invention comprises steps a) and b).

[0059] During step a), the resin composition can be exposed to UV radiation using any device equipped to deliver UV radiation. An example of such a device is a UV lamp, for example a mercury lamp. A second example is a UV LED lamp with a defined wavelength, for example 365 nm, 385 nm, 395 nm, or 405 nm. Several of these devices can also be used, successively or simultaneously, during step a).

[0060] This multiple exposure makes it possible to increase absorption at specific wavelengths, in order to adapt the process to the different styrene compounds that may be present after the depolymerization of polystyrene.

[0061] The manufacturing process according to the invention also includes step b) in which said resin composition is heated to a temperature in the range of 80°C to 350°C, said temperature being higher than the glass transition temperature of the resin after polymerization.

[0062] The resin composition can be heated by any method known to those skilled in the art. For example, it can be heated using an oven, a drying oven, or an infrared lamp.

[0063] Advantageously, the resin composition is heated to a temperature in the range of 100 to 300°C, preferably from 150 to 275°C, more preferably from 200 to 250°C.

[0064] Advantageously, the resin composition is heated for a period of time in the range of 0.5 to 30 seconds, preferably from 1 to 3 seconds.

[0065] Advantageously, step b) of heating is carried out by IR radiation.

[0066] As previously stated, the heating temperature during step b) is higher than the glass transition temperature of the resin after polymerization.

[0067] Thus, before implementing the manufacturing process according to the invention, the resin is polymerized, and then the glass transition temperature of said resin is measured. Once the transition temperature Once the glass transition temperature is determined, the heating temperature above which it must be applied in step b) is known. This heating temperature must therefore be in the range of 80°C to 350°C, while being higher than the glass transition temperature of the resin after polymerization.

[0068] The resin composition can be exposed to infrared radiation, as specified above. This exposure to this other type of radiation can be particularly advantageous insofar as it can complete the polymerization of the mixture, thereby making the manufacturing process according to the invention even more efficient.

[0069] Advantageously, steps a) and b) are carried out simultaneously.

[0070] In particular, steps a) and b) can be carried out simultaneously using a lamp emitting both UV and IR radiation. Such lamps are commercially available, for example under the name "UVAPRINT" from the Dr. Hônle company, with iron-doped mercury bulbs.

[0071] Another object of the invention is a crosslinked resin composition that can be obtained by the process according to the invention.

[0072] The crosslinked resin composition thus obtained is ready for use.

[0073] The invention also relates to a composite based on at least one reinforcing element and at least one crosslinked resin composition as described above.

[0074] By "reinforcing element" is meant an element enabling the mechanical reinforcement of a matrix in which this reinforcing element is intended to be embedded. The reinforcing element may be a wire element.

[0075] The wire element can be metallic or textile. By "wire element", we mean an element having a length at least 10 times greater than the largest dimension of its cross-section, regardless of the shape of the latter: circular, elliptical, oblong, polygonal, in particular rectangular, square or oval.

[0076] Advantageously, the reinforcing element is a reinforcing fiber, preferably chosen from the group consisting of glass fibers, basalt, carbon, aramid, polyester, polyethylene, boron, ceramics and their combinations, preferably the reinforcing fiber is chosen from the group consisting of glass fibers.

[0077] The composite comprising a reinforcing element is preferably a single-strand filament-resin composite (hereinafter "FRC") having filaments embedded in said crosslinked resin composition. In other words, the composite comprising a reinforcing element is preferably a single-strand FRC having filaments embedded in a crosslinked resin composition.

[0078] The filaments can be chosen from the group consisting of glass, basalt, polyester filaments, and their combinations, preferably from the group consisting of glass filaments.

[0079] Thus, preferably, the monostrand is made of glass-resin composite (abbreviated “CVR”).

[0080] By way of example of fibre usable within the framework of the present invention, we may mention the glass fibre “R25H” or “SE 1200” fibre of Owens Corning, the alkali-resistant glass fibre “AR320S-920S”, “AR640S-920S” or “AR1200S-920S” of Nippon Electric Glass or “Cem-fil” of Owens Corning, the basalt fibre “KVT400TEX14I-KV41” of Basaltex, “FilvaTM” of Isomatex, the carbon fibre* HTS40” of Teijin or “ZOLTEK PX35” of Zoltek. The skilled craftsman knows very well how to adapt the sizing to the surface of the filaments to improve the compatibility of the filaments with the resin used in the mineral-resin composite, in particular with the help of a silane-type compatibilizing agent.

[0081] The filaments advantageously represent 65% to 85%, preferably 70% to 80%, by weight of the filament-resin composite monostrand and the resin composition represents 15% to 35%, preferably 20% to 30%, by weight, of the filament-resin composite monostrand.

[0082] The weight percentage of the filaments is calculated by dividing the initial fiber count by the final monofilament count. The count (or linear density) is determined on at least three samples, each corresponding to a length of 50 m, by weighing this length; the count is given in tex (weight in grams of 1000 m of product – as a reminder, 0.111 tex is equivalent to 1 denier). The percentage by weight of crosslinked resin can be obtained by calculating the difference between the final monofilament count and the initial fiber count.

[0083] Typically, the filaments are present in the form of a single multifilament fiber or several multifilament fibers linked together. In the latter case, the multifilament fibers are preferably essentially unidirectional. Each of the multifilament fibers may comprise several dozen, hundreds, or even thousands of individual glass filaments.

[0084] Advantageously, the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

[0085] The single strand advantageously has a diameter ranging from 0.2 to 1.3 mm, preferably from 0.25 to 1.25 mm, more preferably from 0.3 to 1.2 mm.

[0086] The average diameter covers both monofilaments of essentially cylindrical shape (with a circular cross-section) and monofilaments of different shapes, for example oblong monofilaments (with a more or less flattened shape) or with a rectangular cross-section. In the case of a non-circular cross-section, and unless otherwise specified, the average diameter is by convention the so-called overall diameter. that is to say the diameter of the imaginary cylinder of revolution enveloping the single strand, in other words the diameter of the circumscribed circle surrounding its cross-section.

[0087] The glass transition temperature (Tg) of the crosslinked resin is preferably greater than 175°C, preferably greater than 180°C, in particular greater than 185°C. It is measured in a known manner by DSC (Differential Scanning Calorimetry), on the second pass, for example and unless otherwise specified in this application, according to ASTM D3418 of 1999 (Mettler Toledo "822-2" DSC apparatus; nitrogen atmosphere; samples previously heated from room temperature (23°C) to 250°C (10°C / min), then rapidly cooled to 23°C, before final recording of the DSC curve from 23°C to 250°C, according to a ramp of 10°C / min).

[0088] The present invention also relates to a method for manufacturing at least one single strand of filament-resin composite comprising filaments embedded in a cross-linked resin, comprising the following steps:

[0089] i) to create a straight arrangement of filaments and to drive this arrangement in a direction of advancement;

[0090] ii) bringing said arrangement of filaments into contact with a resin composition to obtain an impregnated material containing the filaments and the resin composition,

[0091] said resin composition comprising:

[0092] - at least one photocurable resin comprising at least one selected reactive diluent among at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene;

[0093] - a crosslinking system comprising at least one photoinitiator;

[0094] - optionally a crosslinking agent other than the photoinitiator;

[0095] iii) passing said impregnated material through a calibration die having a predefined surface area and shape section, to impose on it a single-strand shape;

[0096] iv) downstream of the die, in a crosslinking chamber, polymerize the resin composition according to the following successive or simultaneous steps 1) and 2):

[0097] 1) expose said resin composition to UV radiation, in a chamber UV irradiation;

[0098] 2) heat said resin composition to a temperature within a range ranging from 80°C to 350°C, said temperature being higher than the glass transition temperature of the resin after polymerization;

[0099] the crosslinking chamber comprising a tube transparent to ultraviolet light, called crosslinking tube, through which the single strand being formed passes.

[0100] The various preferred embodiments described above in the context of the manufacturing process according to the invention and of the composite according to the invention are applicable for the manufacturing process of said monostrand.

[0101] The composite based on at least one reinforcing element can be manufactured by any method known to a person skilled in the art, depending on the object to be produced.

[0102] The attached [Fig.1] schematically illustrates very simply an example of a device 10 enabling the production of single strands in CVR.

[0103] A reel 1 is shown containing, in the illustrated example, glass fibers 11b (in the form of multifilaments). The reel is continuously unwound by drive, so as to create a straight arrangement 12 of these fibers 11b. Generally, reinforcing fibers are supplied as "rovings," that is, already in groups of fibers wound in parallel on a reel; for example, fibers marketed by Owens Corning under the designation "Advantex" fiber, with a count of 1200 tex (as a reminder, 1 tex = 1 g / 1000 m of fiber), are used. It is, for example, the traction exerted by the rotating receiver 26 that will allow the parallel fibers and the single strand in CVR to advance along the entire length of the installation 1.

[0104] This arrangement 12 then passes through a vacuum chamber 13 (connected to a vacuum pump not shown), disposed between an inlet tube 13a and an outlet tube 13b opening into an impregnation chamber 14, the two tubes preferably having rigid walls having for example a minimum cross-section greater (typically twice as much) than the total cross-section of fibers and a length much greater (typically 50 times more) than said minimum cross-section.

[0105] As already demonstrated by PPE application 174250A1, the use of rigid-walled tubing, both for the inlet orifice in the vacuum chamber and for the outlet orifice of the vacuum chamber and for the transfer from the vacuum chamber to the impregnation chamber, proves compatible with high fiber flow rates through the orifices without breaking the fibers, while also ensuring sufficient sealing. If necessary, experimentally, it is sufficient to determine the largest possible cross-sectional area, given the total cross-section of the fibers to be treated, that still provides sufficient sealing, considering the fiber feed rate and the tubing length. Typically, the vacuum inside chamber 13 is, for example, on the order of 0.1 bar, and the length of the vacuum chamber is approximately 1 meter.

[0106] At the outlet of the vacuum chamber 13 and the outlet pipe 13b, the arrangement 12 of fibers 11b passes through an impregnation chamber 14 comprising a feed reservoir 15 (connected to a metering pump not shown) and a sealed impregnation reservoir 16 completely filled with an impregnation composition 17 based on a vinyl ester-type curable resin (for example, "MIRAMER PE250" from Miwon) and to which a reactive diluent has been added, selected from at least one mixture resulting from the depolymerization of polystyrene, said mixture comprising predominantly styrene. By way of example, the composition 17 further comprises (at a weight rate of 1% to 2%) a suitable photoinitiator for UV and / or UV-visible radiation with which the composition will be subsequently treated, for example bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide ("Omnirad 819" from IGM). Of course, the impregnation composition 17 is in liquid form.

[0107] Preferably, the length of the impregnation chamber is several meters, for example between 2 and 10 m, in particular between 3 and 5 m.

[0108] Thus, from the impregnation chamber 14, in a sealed outlet tube 18 (still under primary vacuum), an impregnated material comprising, for example (% by weight) 65% to 75% of solid fibers 11b, the remainder (25% to 35%) being made up of the liquid impregnation matrix 17.

[0109] The impregnated material then passes through calibration means 19 comprising at least one calibration die 20 whose channel (not shown here), for example circular, rectangular, or conical in shape, is adapted to the specific manufacturing conditions. The calibration die, by means of a cross-section of determined dimensions, generally and preferably circular or rectangular, allows the proportion of resin relative to the fibers to be adjusted, while imposing on the impregnated material the shape and thickness targeted for the monofilament. By way of example, this channel has a minimum circular cross-section whose downstream orifice has a diameter slightly larger than that of the targeted monofilament. The die has a length that is typically at least 100 times greater than the minimum dimension of the cross-section.Its function is to ensure high dimensional accuracy of the finished product; it can also play a role in dosing the fiber content relative to the resin. According to one possible embodiment, the die 20 can be directly integrated into the impregnation chamber 14, which avoids, for example, the use of the outlet tube 18.

[0110] Preferably, the length of the calibration zone is several centimeters, for example between 5 and 50 cm, in particular between 5 and 20 cm.

[0111] Thanks to the calibration means (19, 20) a "liquid" composite monostrand 21 is obtained at this stage (liquid in the sense that its impregnation resin is always liquid) whose cross-section shape is preferably essentially circular.

[0112] At the output of the calibration means (19, 20), the liquid composite monostrand 21 thus obtained is then polymerized by passing through a UV irradiation chamber 22 comprising a sealed glass tube 23 through which the composite monostrand flows; said tube, the diameter of which is typically a few cm (for example 2 to 3 cm), is irradiated by a plurality (here, for example 4) of UV irradiators (24) in line ("UVAprint" lamps from the Dr. Hônle company, with a wavelength of 200 to 600 nm) arranged at a short distance (a few cm) from the glass tube.

[0113] The polymerization or UV irradiation chamber then has the function of polymerizing, cross-linking the resin under the action of UV.

[0114] The UV irradiation chamber may comprise one or more UV irradiators (or heaters). Advantageously, the irradiation chamber comprises a plurality of UV irradiators, that is, at least two (two or more) arranged in a line around the irradiation tube. Each UV irradiator typically comprises one (at least one) UV lamp (preferably emitting in a spectrum from 200 to 600 nm) and a parabolic reflector at the focus of which is the center of the irradiation tube; it delivers a linear power preferably between 2,000 and 14,000 watts per meter. More preferably still, the irradiation chamber comprises at least three, and in particular at least four, UV irradiators in a line.

[0115] Even more preferably, the linear power delivered by each UV irradiator is between 2,500 and 12,000 watts per meter, in particular within a range of 3,000 to 10,000 watts per meter.

[0116] UV heaters suitable for the process are well known to those skilled in the art, for example those marketed by Dr. Hönle AG (Germany) under the reference "1055 LCP AM UK", equipped with "UVAPRINT" lamps (iron-doped high-pressure mercury lamps). The rated (maximum) power of each heater of this type is approximately 13,000 Watts, the actual power output being adjustable with a potentiometer between 30% and 100% of the rated power.

[0117] The diameter of the irradiation tube (preferably made of glass) is preferably between 10 and 80 mm, more preferably between 20 and 60 mm.

[0118] Preferably, the length of the irradiation chamber is several meters, for example between 2 and 15 m, in particular between 3 and 10 m.

[0119] In this example, the irradiation tube 23 is traversed by a nitrogen current.

[0120] Simultaneously with UV exposure, the resin composition is heated to a temperature of 250°C for a duration in the range of one to three seconds.

[0121] The irradiation conditions are preferably adjusted so that, at the outlet of the impregnation chamber, the temperature of the CVR single strand, measured on the surface of the latter (for example using a thermocouple), is greater than the Tg of the crosslinked resin (in other words greater than 175°C), and more preferably less than 200°C.

[0122] Once the resin has polymerized (hardened), the CVR monostrand 25, now in solid state, carried in the direction of arrow F, then arrives on its final receiving reel 26.

[0123] Between the calibration die and the final receiving support, it is preferable to maintain the tensions experienced by the mineral fibers at a moderate level, preferably between 0.2 and 2.0 cN / tex, more preferably between 0.3 and 1.5 cN / tex; to control For this, we can, for example, measure these tensions directly at the output of the irradiation chamber, using appropriate tensiometers well known to those skilled in the art.

[0124] A finished composite block is finally obtained as schematically shown very simply in [Fig.2], in the form of a continuous CVR monostrand 25, of very long length, whose unit glass filaments 251 are distributed homogeneously throughout the entire volume of hardened resin 252. Its diameter is for example equal to about 1 mm.

[0125] The continuous CVR monostrand 25 can then be cut to a predetermined length (not shown in [Fig. 1]), as required, by any means known to those skilled in the art, for example, using a hydraulic guillotine, such as the "SH-5214" from Baileigh. This step can be carried out directly at the exit of the irradiation chamber 23. It can also be carried out after being conditioned onto a final receiving reel 26. In this case, it is preferable to unwind the monostrand from the reel from the outermost axial end of the reel, in order to avoid helical deformation of the monostrand. Indeed, if the monostrand is unwound from the innermost axial end of the reel, this helical deformation of the monostrand can be detrimental to the breaking strength. Examples Measurement methods

[0126] Mechanical properties

[0127] The mechanical properties in extension of the single strand in CVR (stress at break Cr and elongation at break Ar) were measured using an "INSTRON" 68TM50 tensile testing machine (BLUEHILL® UNIVERSAL software supplied with the tensile testing machine), according to ASTM D2343, at a temperature of 23°C.

[0128] The measurements were carried out on CVR monostrands with petroleum-based styrene or with styrene from the depolymerization of polystyrene.

[0129] Before measurement, these monostrands were subjected to prior conditioning (storage of the monostrands for at least 24 hours in a standard atmosphere according to the European standard DIN EN 20139 (temperature of 23 °C ± 2°C; humidity of 50% ± 5%)).

[0130] The 240 mm samples tested were subjected to a tensile test at a nominal speed of 50 m / min, under a preload of 0.5 MPa (distance between the jaws: 150 mm). All results given are an average of 10 measurements.

[0131] Measurement of exothermicity

[0132] The exothermicity of the resin compositions was measured by DSC (Differential Scanning Calorimetry), on the first pass, according to ASTM D3418. 1999 (Mettler Toledo "822-2" DSC apparatus; nitrogen atmosphere; samples preheated from room temperature (23°C) to 250°C (10°C / min), then rapidly cooled to 23°C, before final recording of the DSC curve from 23°C to 250°C, at a rate of 10°C / min. It is expressed in J / g. This is the protocol followed for the polymerization shown in Table 3.

[0133] Photoreactivity measurement

[0134] A photo-DSC device was used to directly measure the exotherm of photopolymerization of the different samples. The measurements were carried out using an isothermal program, for a duration of 5 min at 25 °C under 80 mL / min of nitrogen. An LED lamp delivering UV radiation (365 nm) was switched on twice for 60 s at 100% intensity. The difference between the exotherms of the two irradiations gives the exotherm of photopolymerization, which is the enthalpy expressed in J / g. This is the protocol followed for the polymerization presented in Table 2. Resin Irradiation / Heating Protocol

[0135] 10 mg resin samples were loaded into DSC crucibles. Polymerization was carried out under a 365 nm UV LED light (from Omnicure), for 3 s, at 100% intensity.

[0136] The sample may then have been heated in an oven at 200°C for 30 min, as appropriate. Then, the exothermicity (and therefore the polymerization rate) was measured using the protocol described above (exothermicity measurement).

[0137] Other tests were carried out, detailed below, in which the resin was not, for example, irradiated with the UV LED, but the sample was placed directly in an oven at 100°C or 200°C for 30 min, and then the exothermic measurement in DSC was carried out. Preparation of resin compositions

[0138] Two resin compositions were prepared (Cl and C2).

[0139] For each of the compositions, the photoinitiator (“Omnirad 819” from IGM) and the crosslinking agent (triacrylate hardener (“SR 368” from Sartomer)) were used. The photoinitiator content was 1.5% by weight relative to the total weight of the resin composition, and the crosslinking agent content was 15% by weight relative to the total weight of the resin composition.

[0140] For composition Cl, vinyl ester resin (“MIRAMER PE250”) was used. To this resin, 30.6% by weight of petroleum-based styrene, relative to the total weight of composition Cl, was added. This reactive diluent is referred to hereafter as PRL. An example of commercial petroleum-based styrene is that sold by Sigma-Aldrich (product number 8.07679; CAS number: 100-42-5).

[0141] For composition C2, vinyl ester resin (“MIRAMER PE250”) was used. To this resin, 30.6% by weight of styrene obtained from the depolymerization of polystyrene, according to the protocol described in document WO 2018 / 018153, relative to the total weight of composition C2, was added. The resin contains the reactive diluent referred to hereafter as DR2.

[0142] The compositions Cl and C2 are summarized in Table 1 below:

[0143] [Tables 1] Composition Cl C2 Vinylester Resin (% by weight) 52.9 52.9 Reactive Thinner DR1 (% by weight) 30.6 - Reactive Thinner DR2 (% by weight) - 30.6 Photoinitiator (% by weight) 1.5 1.5 Triacrylate Hardener (% by weight) 15 15

[0144] Thus, the Cl and C2 compositions differ only in the nature of the reactive diluent.

[0145] Some characteristics concerning the Cl and C2 compositions are further summarized in Table 2 below. The Cl and C2 resin compositions were crosslinked according to the protocol described above for the evaluation of photoreactivity (expressed in J / g).

[0146] [Tables2] Composition of crosslinked resin Cl C2 Photo-reactivity - Enthalpy (J / g) 265 226

[0147] It is observed that the photo-reactivity of the crosslinked resin composition C2 has a lower value than that of the crosslinked resin composition CL

[0148] This table confirms that composition C2 exhibits lower reactivity than composition Cl due to the presence of a mixture resulting from a depolymerization of polystyrene, said mixture comprising mainly styrene, in the reactive diluent.

[0149] Furthermore, the Cl and C2 resin compositions were crosslinked according to various protocols.

[0150] According to a first protocol, the two resin compositions were crosslinked only under a 365 nm UV LED light (from Omnicure) for 3 s.

[0151] According to a second protocol, the two resin compositions were heated only in an oven at 100°C for 30 min. Furthermore, it was determined that the glass transition temperatures of the Cl and C2 resin compositions were within a range of 150°C to 200°C.

[0152] According to a third protocol, the two resin compositions were heated only in an oven at 200°C for 30 min.

[0153] According to a fourth protocol, the two resin compositions were crosslinked under a 365 nm UV LED light (from Omnicure) for 3 s and, simultaneously, heated in an oven at 100°C for 30 min.

[0154] According to a fifth protocol, the two resin compositions were crosslinked under a 365 nm UV LED light (from Omnicure) for 3 s and, simultaneously, heated in an oven at 200°C for 30 min.

[0155] Then the exothermic measurements in DSC were carried out.

[0156] The characteristics are summarized in Table 3 below:

[0157] [Tables3] Exothermic reaction of the Cl composition (J / g) Exothermic reaction of the C2 composition (J / g) Protocol 1: UV (3 s) 36 + 1 43 + 1 Protocol 2: Oven 100°C (30 min) 154 (no polymerization) 154 (no polymerization) Protocol 3: Oven 200°C (30 min) 154 (no polymerization) 154 (no polymerization) Protocol 4: UV (3 s) + Oven 100°C (30 min) 24 + 1 33 + 1 Protocol 5: UV (3 s) + Oven 200°C (30 min) 0 0

[0158] As shown in Table 3 above, the higher the exothermicity, the less advanced the polymerization. Indeed, in this table, "0" means that the resin composition has been completely polymerized.

[0159] In particular, it is observed that the resin compositions are not polymerized at all at the end of protocols 2 and 3, and that the resin compositions are not completely polymerized at the end of protocols 1 and 4.

[0160] On the other hand, protocol 5 allows the resin compositions to be completely polymerized.

[0161] Two extremely interesting lessons can be deduced from this table.

[0162] First, the fact that the C2 resin composition is completely polymerized, just like the Cl resin composition when using protocol 5 of Table 3, is a surprising result, since it had been observed that the polymerization of the C2 resin composition was less reactive than that of CL

[0163] It also appears from Table 3 that the two steps of exposure to UV radiation and heating are necessary to obtain complete polymerization, with a heating temperature that must be higher than the glass transition temperature of the resin after polymerization. Preparation of single strands in CVR

[0164] CVR single strands were manufactured according to the process described above with a flow velocity Vir of the single strand through the irradiation chamber of 110 m / min, an irradiation time Dir of the single strand in the irradiation chamber of 2.2 s, the length of the irradiation chamber being 4 m (single strands M1 to M2). The single strands M1 and M2 comprise resin compositions Cl and C2, respectively.

[0165] The glass filaments of the monostrands M1 to M2 were “SE 1200 300 TEX” filaments from Owens Corning. Their diameter was 0.54 mm, the tex of the glass fibers was 300 g / km and the mass ratio of glass fibers to the crosslinked resin was 70 / 30.

[0166] The mechanical properties of the single strands M1 to M2 and the glass transition temperature of the resin compositions Cl to C2 are presented in Table 4 below.

[0167] [Tables4] Monostrands M1 (comparative) M2 (invention) Tensile strength (MPa) 1234 1234 Elongation at break (%) 4.1 4.1 Temperature Tg (°C) 191 191

[0168] The results presented above show that the nature of the reactive diluent does not impact the mechanical properties of the single strands or the glass transition temperature of the crosslinked resin compositions present within the single strands.

[0169] This finding is an unexpected result. It is necessary to recall that the characteristics in Table 1 clearly show that the presence of a reactive diluent comprising at least one mixture resulting from the depolymerization of polystyrene, said mixture comprising predominantly styrene, impacts the reactivity of the resins. A person skilled in the art would therefore expect a degradation of the properties of monofilaments comprising a resin obtained by the manufacturing process according to the invention.

[0170] Contrary to expectations, the single strands according to the invention exhibit mechanical properties and a glass transition temperature equivalent to the single strands conventionally used.

[0171] This therefore represents an extremely interesting advantage, insofar as recycled materials, in particular those from a depolymerization of polystyrene, are recovered, thus opening up sustainable prospects for the environment.

Claims

Demands

1. A method for manufacturing a crosslinked resin composition comprising the following successive or simultaneous steps a) and b): a) exposing at least one resin composition to UV radiation in a UV irradiation chamber, said resin composition comprising: - at least one photocurable resin comprising at least one reactive diluent selected from at least one mixture obtained from a depolymerization of polystyrene, said mixture comprising predominantly styrene; - a crosslinking system comprising at least one photoinitiator; and - optionally a crosslinking agent other than the photoinitiator; b) heating said resin composition to a temperature in the range of 80°C to 350°C, said temperature being above the glass transition temperature of the resin after polymerization.

2. The method according to claim 1, characterized in that the photocurable resin is chosen from the group consisting of vinyl ester, epoxy, polyester, novolac resins and mixtures thereof, preferably from the group consisting of vinyl ester, epoxy resins and mixtures thereof, more preferably from the group consisting of vinyl ester resins and mixtures thereof.

3. A process according to claim 1 or 2, characterized in that said mixture further comprises at least one compound other than styrene, preferably selected from ethylbenzene, benzene, cumene, alpha-methylstyrene and mixtures thereof.

4. A process according to any one of the preceding claims, characterized in that the styrene content in said mixture is less than or equal to 99% by weight, preferably within a range of 90% to 99% by weight, more preferably from 95% to 99% by weight relative to the total weight of said mixture.

5. A process according to any one of the preceding claims, characterized in that the rate of reactive diluent is in the range of 15% to 40% by weight, preferably 20% to 35% by weight relative to the total weight of the resin composition.

6. A method according to any one of the preceding claims, characterized in that the photoinitiator is chosen from the group consisting of phosphine oxides and mixtures thereof, preferably from the group consisting of mono(acyl)phosphine oxides, bis(acyl)phosphine oxides and mixtures thereof.

7. A method according to any one of the preceding claims, characterized in that the photoinitiator content is in the range of 0.5% to 2.5% by weight, preferably 1% to 2% by weight relative to the total weight of the resin composition.

8. A method according to any one of the preceding claims, characterized in that step b) of heating is carried out by IR radiation.

9. A method according to any one of the preceding claims, characterized in that steps a) and b) are carried out simultaneously.

10. Crosslinked resin composition obtainable by a process according to any one of the preceding claims.

11. Composite based on at least one reinforcing element and at least one crosslinked resin composition as defined in any one of claims 1 to 10.

12. Composite according to claim 11, characterized in that the reinforcing element is a reinforcing fiber, preferably chosen from the group consisting of glass fibers, basalt, carbon, aramid, polyester, polyethylene, boron, ceramics and their combinations, preferably the reinforcing fiber is chosen from the group consisting of glass fibers.

13. Composite according to claim 11 or 12, characterized in that it is a single strand of filament-resin composite comprising filaments embedded in said crosslinked resin composition.

14. Composite according to claim 13, characterized in that the filaments represent from 65% to 85%, preferably from 70% to 80% by weight of the monostrand, and the crosslinked resin represents from 15% to 35%, preferably from 20% to 30% by weight of the monostrand.

15. A method for manufacturing at least one single strand of filament-resin composite comprising filaments embedded in a crosslinked resin, comprising the following steps: i) making a straight arrangement of filaments and driving this arrangement in a direction of advancement; (ii) to contact said arrangement of filaments with a resin composition to obtain an impregnated material containing the filaments and the resin composition, said resin composition comprising: - at least one photocurable resin comprising at least a reactive diluent selected from at least one mixture resulting from a depolymerization of polystyrene, said mixture comprising predominantly styrene; - a crosslinking system comprising at least one photoinitiator; - optionally a crosslinking agent other than the photoinitiator; iii) pass said impregnated material through a calibration die having a predefined surface area and shape section, to impose on it a single-strand shape; (iv) downstream of the die, in a crosslinking chamber, polymerize the resin composition according to the following successive or simultaneous steps (1) and (2): 1) expose said resin composition to UV radiation, in a UV irradiation chamber; 2) heat said resin composition to a temperature in the range of 80°C to 350°C, said temperature being higher than the glass transition temperature of the resin after polymerization; the crosslinking chamber comprising a tube transparent to ultraviolet light, called the crosslinking tube, through which the single strand being formed passes.

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