Method for manufacturing a filament-resin composite monostrand comprising filaments embedded in a crosslinked resin using a specific resin composition

Abstract

The present invention relates to a method for manufacturing at least one filament-resin composite monostrand comprising filaments embedded in a crosslinked resin, using a specific resin composition. The present invention also relates to a composite based on at least one reinforcing element and said resin composition.

Description

[0001] DESCRIPTION

[0002] TITLE: Process for manufacturing a single-strand filament-resin composite comprising filaments embedded in a cross-linked resin using a specific resin composition

[0003] technical field

[0004] The present invention relates to the field of resin compositions and composites, such as filament-resin composite monostrands.

[0005] Composite reinforcements based on filament-resin composite monostrands are well known to those skilled in the art. An example of such a reinforcement, described for instance 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 consist of continuous, unidirectional glass fibers impregnated in a cross-linked vinyl ester resin.

[0006] Document FR 3 031 757 describes a multi-composite reinforcement based on CVR monostrands with improved mechanical properties. This document describes the use of an epoxyvinylester resin composition, also including a phosphine-type photoinitiator and a crosslinking agent, tris(2-hydroxyethyl)isocyanate triacrylate.

[0007] These single strands find applications particularly in connection with the reinforcement of semi-finished products or finished rubber articles such as tires for vehicles, of the pneumatic or non-pneumatic type.

[0008] Thanks to the above properties, it was shown in patent EP 1 167 080 that it was advantageously possible to substitute such single strands in CVR for steel cables, as new reinforcement elements for pneumatic tire belts, thus making it possible to significantly lighten the structure of the tires.

[0009] Patent application EP 1 174 250 (equivalent to US 6 926 853 or US 7 484 949) proposed a continuous manufacturing process for such CVR single strands, comprising the following essential steps:

[0010] - to create a straight arrangement of glass fibers and drive this arrangement in a direction of advancement;

[0011] - in a vacuum chamber, degas the arrangement of fibers by the action of a vacuum;

[0012] - upon exiting the vacuum chamber, after degassing, pass through a vacuum impregnation chamber so as to impregnate said arrangement of fibers with the resin in liquid state to obtain an impregnated material containing the fibers and the resin; - pass said impregnated material through a calibration die having a predefined surface area and shape section, to impose on it a single-strand shape;

[0013] - downstream of the process, in a UV irradiation chamber, stabilize and solidify the monostrand by photopolymerization of the resin under the action of UV;

[0014] - then wind up the resulting single strand for storage.

[0015] However, in these composite reinforcements, the resin compositions used classically include a photocurable resin, a photoinitiator and a crosslinking agent.

[0016] The photocurable resins generally used are vinyl ester resins, which are solid or highly viscous liquids at room temperature, making their use on an industrial scale difficult. To reduce their viscosity, these photocurable resins are usually sold with a reactive diluent, often styrene, at a concentration of up to approximately 50% by weight of the photocurable resin. Nevertheless, despite their presence, the viscosity of these resins remains high, making the implementation of processes involving such resin compositions often challenging.

[0017] At a time when styrene is perceived more and more negatively, it would be desirable to reduce the level of reactive diluent present in photocurable resins.

[0018] Furthermore, a crosslinking agent is added to these resins to increase the glass transition temperature of the crosslinked resin composition. Consequently, these resin compositions generally have a high manufacturing cost.

[0019] Description of the invention

[0020] The Applicant unexpectedly discovered that the presence of a resin comprising at least one specific monomer unit in a resin composition facilitated the implementation of single-strand manufacturing processes incorporating said resin. Furthermore, the Applicant discovered that such a resin increased the glass transition temperature of these resin compositions without degrading mechanical properties, such as tensile strength and elongation at break.

[0021] The present invention relates to a method for manufacturing at least one single-strand filament-resin composite comprising filaments embedded in a cross-linked resin, comprising the following steps: a) creating a straight arrangement of filaments and driving this arrangement in a direction of advancement; b) contacting said arrangement of filaments with a resin composition to obtain an impregnated material containing the filaments and the resin composition; said resin composition comprising:

[0022] - at least one photocurable resin chosen from the group consisting of resins comprising at least one monomer unit of the following formula (I):

[0023] (I), in which:

[0024] Ri and R2, whether identical or different, represent, independently of each other, a hydrogen atom, a group containing an acrylate function, or a group containing a methacrylate function, provided that Ri and R2 do not both represent a hydrogen atom; and

[0025] - at least one photoinitiating agent; c) passing said impregnated material through a calibration die having a predefined surface area and shape, to impose a single-strand shape on it; d) downstream of the die, in a crosslinking chamber, polymerizing the resin composition under the action of ultraviolet or visible radiation, the crosslinking chamber comprising a tube transparent to ultraviolet or visible light, called a crosslinking tube, through which the single strand being formed passes.

[0026] The invention also relates to a composite based on at least one reinforcing element and at least one crosslinked resin composition, said composite being a single strand of filament-resin composite comprising filaments embedded in said crosslinked resin composition, as well as a finished article or a semi-finished product comprising at least one single strand.

[0027] In this application, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0028] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0029] By "embedded", we mean that the reinforcing element is in direct contact with the resin composition over its entire surface, with the possible exception of the cutting areas of the composite.

[0030] 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.

[0031] By "crosslinked" resin, we mean of course 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 specific to so-called thermosetting polymers (as opposed to so-called thermoplastic polymers).

[0032] In this application, the term "fibre" is equivalent to the term "monofurin". Thus, the two terms may be used interchangeably.

[0033] 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 (that is, 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 (that is, including the strict bounds a and b). In this context, when an interval of values ​​is designated by the expression "from a to b," it also and preferably refers to the interval represented by the expression "between a and b."

[0034] Brief description of the figures

[0035] [Fig. 1] Figure 1 represents a diagram of the single-strand synthesis process according to the invention.

[0036] [Fig. 2] Figure 2, not shown to scale for ease of understanding, is a drawing representing a cross-section of the single strand according to the invention.

[0037] Description of the invention

[0038] As previously stated, a single strand of filament-resin composite, comprising filaments embedded in a cross-linked resin, is manufactured according to the process of the invention. Advantageously, the process for manufacturing said single strand comprises the following steps:

[0039] - the speed (Vi r ) passage of the single strand in the irradiation chamber is greater than 50 m / min;

[0040] - the duration (Di r ) passage of the single strand in the irradiation chamber is equal to or greater than 1.5 s and equal to or less than 10 s;

[0041] - the irradiation chamber includes a UV-transparent tube (such as a quartz tube or preferably a glass tube), called the irradiation tube, through which the single strand being formed circulates, this tube being traversed by a current of inert gas, preferably nitrogen.

[0042] All the steps (arrangement, degassing, impregnation, calibration, polymerization, possible winding and cutting) of the process of the invention are, independently of each other, steps known to the person skilled in the art, as well as the materials (multifilament fibers) used; they have for example been described in one and / or the other of applications EP 1 074 369 Al and EP 1 174250 Al.

[0043] The process according to the invention has the advantage of being able to be used at low temperatures, typically at room temperature (20°C), which reduces the energy used.

[0044] Furthermore, as previously stated, the resin composition used in the manufacturing process according to the invention comprises:

[0045] - at least one photocurable resin chosen from the group consisting of resins comprising at least one monomer unit of the following formula (I):

[0046] (I), in which:

[0047] Ri and R2, whether identical or different, represent, independently of each other, a hydrogen atom, a group containing an acrylate function, or a group containing a methacrylate function, provided that Ri and R2 do not both represent a hydrogen atom; and

[0048] - at least one photoinitiator. Thus, the resin comprising at least one monomer unit of formula (I) is isosorbide-based.

[0049] A photocurable resin, as defined above, is a resin capable of crosslinking in the presence of a photoinitiator under the action of light radiation, particularly ultraviolet or visible light. Preferably, the photocurable resin is a UV-curable resin.

[0050] Advantageously, the group containing an acrylate function can be an acrylate group or a glycidyl acrylate group, preferably an acrylate group.

[0051] Advantageously, the group containing a methacrylate function can be a methacrylate group or a glycidyl methacrylate group, preferably a methacrylate group.

[0052] Preferably, Ri and R2 represent the same group.

[0053] In a particularly preferred manner, Ri and R2 both represent a methacrylate group. Thus, according to this embodiment, the photocurable resin comprises at least one isosorbide-dimethacrylate (ISM) unit.

[0054] Advantageously, the photocurable resin is chosen from the group consisting of resins comprising said monomer units of formula (I) in a proportion in the range of 55% to 100% by weight, preferably 80% to 100% by weight, more preferably 100% by weight relative to the total weight of the monomer units.

[0055] Thus, according to a particular embodiment, the resin comprising at least one monomer unit of formula (I) may further comprise one or more monomer units of a formula different from formula (I), in a rate less than or equal to 45% by weight in relation to the total weight of the monomer units.

[0056] Examples of such monomers include acrylates, methacrylates, and vinyl esters.

[0057] The photocurable resin as defined above may contain a reactive diluent, such as styrene, at a concentration of up to approximately 40% by weight of the photocurable resin. It is common knowledge among those skilled in the art that commercially available photocurable resins are often sold diluted.

[0058] The proportion of photocurable resin in the resin composition may be in the range of 82.5% to 99.5% by weight, preferably 90% to 99.5% by weight, more preferably 95% to 99% by weight, even more preferably 97.5% to 99% by weight, and better still 98% to 99% by weight, relative to the total weight of the resin composition. When the photocurable resin includes a reactive diluent, the aforementioned proportions of photocurable resin include said reactive diluent.

[0059] A photoinitiator is a molecule that, when exposed to ultraviolet or visible radiation, generates reactive species such as free radicals, cations, or anions. Advantageously, the photocurable resin is UV-curable, and the photoinitiator is UV-reactive above 300 nm, preferably between 300 and 450 nm.

[0060] The photoinitiator is preferably chosen from the group consisting of type I photoinitiators and their mixtures. The photoinitiator may also be a photoinitiator that is not a type I photoinitiator, for example a type II photoinitiator or other, but this is not preferred.

[0061] Type I photoinitiators are chosen from the group consisting of benzoin ethers, benzyl ketals, alpha-dialkoxy-aceto-phenones, alpha-hydrody-alkyl-phenones, alpha-amino-alkyl-phenones, phosphine oxides and mixtures thereof.

[0062] Advantageously, the photoinitiating agent is chosen from the group consisting of phosphine oxides and their mixtures, preferably from the group consisting of mono(acyl)phosphine oxides, bis(acyl)phosphine oxides, and their mixtures. The phosphine oxide may preferably be a bis(acyl)phosphine oxide.

[0063] As an example of a photoinitiating agent 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 may be used in mixtures with other photoinitiators, for example, alpha-hydroxy ketone-type photoinitiators such as dimethylhydroxyacetophenone (e.g., “Omnirad 1173” from IGM) or 1-hydroxycyclohexyl 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).

[0064] The rate of photoinitiator agent is advantageously within a range of 0.5% to 2.5% by weight, preferably 0.5% to 2% by weight, more preferably 1% to 2% by weight relative to the total weight of the resin composition.

[0065] The resin composition may further comprise at least one crosslinking agent, other than a photoinitiator. The content of this crosslinking agent may be in the range of 0% to 15% by weight relative to the total weight of the resin composition. Advantageously, the content of at least one crosslinking agent, other than a photoinitiator, is less than or equal to 4% by weight, preferably less than or equal to 2% by weight, and more preferably less than or equal to 1% by weight relative to the total weight of the resin composition.

[0066] Preferably, the resin composition is free of crosslinking agents, other than photoinitiators.

[0067] Examples of crosslinking agents other than photoinitiators include multifunctional acrylate or methacrylate derivatives and peroxides well known to those skilled in the art.

[0068] 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.

[0069] As previously stated, the photocurable resin as defined above may contain a reactive diluent, such as styrene.

[0070] Advantageously, the resin composition is free from reactive diluent selected from the group consisting of styrene, 2-hydroxymethacrylate, methyl methacrylate, F-methyl acrylate, furfuryl methacrylate, and mixtures thereof, preferably free from reactive diluent.

[0071] This method of implementation is particularly advantageous in the context of the current problem of seeking to reduce the use of hydrocarbons, and for example styrene, which are perceived more and more negatively.

[0072] As previously stated, the invention also relates to a composite based on at least one reinforcing element and at least one crosslinked resin composition as defined above, said composite being a single strand of filament-resin composite comprising filaments embedded in said crosslinked resin composition.

[0073] A "reinforcing element" is defined as an element that provides mechanical reinforcement to a matrix in which it is intended to be embedded. The reinforcing element may be a wire element, and in particular, a filament.

[0074] 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.

[0075] 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.

[0076] As previously stated, the composite comprising a reinforcing element is a single-strand filament-resin composite (hereinafter "FRC") having filaments embedded in said resin composition, said resin composition being crosslinked (i.e., a resin hardened after crosslinking). In other words, the composite comprising a reinforcing element is a single-strand FRC having filaments embedded in a resin crosslinked from the resin composition as defined above.

[0077] 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.

[0078] Thus, preferably, the monostrand is made of glass-resin composite (abbreviated "CVR").

[0079] Examples of fibers that can be used in the context of the present invention include Owens Corning “R25H” or “SE1200” glass fibers, Nippon Electric Glass “AR320S-920S”, “AR640S-920S” or “AR1200S-920S” alkali-resistant glass fibers, Owens Corning “Cem-fil” basalt fibers, Basaltex “KVT400TEX14I-KV41”, Isomatex “FilvaTM”, Teijin “HTS40” carbon fibers, and Zoltek “ZOLTEK PX35”. 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.

[0080] The filaments advantageously represent 65% to 85% by weight, preferably 70% to 80% by weight of the monostrand, and the crosslinked resin represents 15% to 35% by weight, preferably 20% to 30% by weight of the monostrand in filament-resin composite.

[0081] The filament weight ratio 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 that 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.

[0082] Typically, the filaments are present as a single multifilament fiber or as several multifilament fibers joined together. In the latter case, the multifilament fibers are preferably essentially unidirectional. Each multifilament fiber can contain several dozen, hundreds, or even thousands of individual glass filaments.

[0083] Advantageously, the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

[0084] The average diameter of a filament can be determined by any method known to a person skilled in the art, and advantageously by the method as described below for determining the average diameter DM of the single strand, with the difference that the measurements are preferably carried out using a scanning electron microscope.

[0085] The single strand advantageously has a diameter DM 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 DM covers both single strands of essentially cylindrical shape (with a circular cross-section) and single strands of different shapes, for example oblong single strands (of more or less flattened shape) or of straight, square or rectangular cross-section.

[0087] The mean diameter DM is advantageously defined as follows: DM = (S / TI), where S is the cross-sectional area of ​​the single strand made of filament-resin composite, particularly glass-resin. To determine the mean diameter DM, at least five measurements are advantageously taken at different locations along the single strand. These measurements can be performed using an optical microscope, such as the Keyence VHX7000 or another optical microscope. Sections of the single strand can be prepared to obtain its cross-section. The sample can then be analyzed under a microscope, and its cross-section can be determined by image analysis.

[0088] In the case of a non-circular cross-section, and unless otherwise specified, the average diameter is conventionally the so-called overall diameter, that is, 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. The circumscribed diameter can be determined by microscopy, as described above.

[0089] The glass transition temperature (Tg) of the crosslinked resin is preferably greater than 175°C, preferably greater than 180°C, and in particular greater than 185°C. It can be 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 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, on a ramp of 10°C / min). It can also be measured by TMA (thermomechanical analysis), (TMA 40 device controlled by a TC 15 TA controller from Mettler Toledo).For example, cylindrical samples (e.g., 2 mm in diameter) of 10 mg can be photocured under a lamp (e.g., an Omnicure lamp) with a given wavelength (e.g., 365 nm). The sample can be placed between flat, circular Inconel discs and mounted centrally between the glass stage and the probe. The experiment can start at 25°C, and the sample can be held for 5 min under a static load (e.g., 0.28 N), then heated, for example, to 250°C, at a heating rate of up to 10°C / min (possibly under a nitrogen atmosphere). The sample displacement can be continuously recorded with respect to temperature. All measurements can be performed three times to ensure accuracy. The STARe evaluation software can be used to determine the glass transition temperature as the inflection point of the curve.

[0090] Another object of the invention is a finished article or a semi-finished product comprising at least one single strand as defined above. An example of a semi-finished product that may be cited is a tire bead or a non-pneumatic tire shear strip. The tire bead, for land vehicles or aircraft, is well known to those skilled in the art. It has, for example, been described in one or both of the applications WO 2013 / 182597, WO 2013 / 182598, and WO 2013 / 182599.

[0091] The composite based on at least one reinforcing element, said composite being a single strand of filament-resin composite comprising filaments embedded in the crosslinked resin composition, can be manufactured by any method known to a person skilled in the art depending on the object to be produced.

[0092] Figure 1 attached schematically illustrates in a very simple way an example of a device 10 allowing the production of single strands in CVR.

[0093] We see a reel 1a 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 name "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 tension exerted by the rotating receiver 26 that will allow the parallel fibers and the single-strand CVR to advance along the entire length of the installation 1.

[0094] This arrangement 12 then passes through a vacuum chamber 13 (connected to a vacuum pump not shown), arranged 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.

[0095] As already demonstrated by EP 1174250 A1, the use of rigid-walled tubing, both for the inlet and outlet 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 fiber breakage, while also ensuring sufficient sealing. If necessary, experimentally, the largest possible cross-sectional area, given the total cross-section of the fibers to be treated, can be determined while still providing 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.

[0096] Upon exiting the vacuum chamber 13 and the outlet tube 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 curable resin comprising at least one monomer unit of formula (I) as defined above. For example, the composition 17 further comprises (at a weight percentage 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). The impregnation composition 17 is, of course, in a liquid state.

[0097] Preferably, the length of the impregnation chamber is several meters, for example between 2 and 10 m, especially between 3 and 5 m.

[0098] Thus, from the impregnation chamber 14, in a sealed outlet tube 18 (still under primary vacuum), comes an impregnated material which comprises, 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.

[0099] 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 resin-to-fiber ratio to be adjusted, while simultaneously imposing on the impregnated material the desired shape and thickness for the monofilament. For example, this channel has a minimum circular cross-section whose downstream orifice has a diameter slightly larger than that of the target monofilament. The die's length is typically at least 100 times greater than the minimum cross-sectional dimension.Its function is to ensure high dimensional accuracy in the finished product; it can also play a role in regulating the fiber-to-resin ratio. In one possible embodiment, the die 20 can be directly integrated into the impregnation chamber 14, thus avoiding, for example, the use of the outlet tube 18.

[0100] Preferably, the length of the calibration zone is several centimeters, for example between 5 and 50 cm, in particular between 5 and 20 cm. 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-sectional shape is preferably essentially circular.

[0101] 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, whose diameter 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.

[0102] The polymerization or UV irradiation chamber then has the function of polymerizing and cross-linking the resin under the action of UV light.

[0103] The UV irradiation chamber may include one or more UV irradiators (or heaters). Advantageously, the irradiation chamber includes 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 includes 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. Even more preferably, the irradiation chamber includes at least three, and in particular at least four, UV irradiators in a line.

[0104] Even more preferentially, 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.

[0105] Suitable UV heaters for this process are well known to those skilled in the art, for example, those marketed by Dr. Honle AG (Germany) under the reference "1055 LCP AM UK", equipped with "UVAPRINT" lamps (iron-doped high-pressure mercury lamps). The nominal (maximum) power of each heater of this type is approximately 13,000 Watts, with the actual power output adjustable via a potentiometer between 30% and 100% of the nominal power.

[0106] The diameter of the irradiation tube (preferably made of glass) is preferably between 10 and 80 mm, more preferably between 20 and 60 mm. Preferably, the length of the irradiation chamber is several meters, for example between 2 and 15 m, in particular between 3 and 10 m.

[0107] In this example, the irradiation tube 23 is traversed by a nitrogen current.

[0108] The irradiation conditions are preferentially adjusted so that, at the outlet of the impregnation chamber, the temperature of the single strand in CVR, 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 270°C.

[0109] Once the resin has polymerized (hardened), the CVR 25 monostrand, now in solid state, carried in the direction of arrow F, then arrives on its final receiving reel 26.

[0110] 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 this, these tensions can be measured directly at the exit of the irradiation chamber, using appropriate tensiometers well known to those skilled in the art.

[0111] We finally obtain a finished composite block of manufacture as schematically shown very simply in figure 2, in the form of a continuous CVR monostrand 25, of very great 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.

[0112] The continuous CVR strand 25 can then be cut to a predetermined length (not shown in Figure 1), as required, by any means known to those skilled in the art, for example, using a hydraulic guillotine such as the Baileigh SH-5214. This step can be carried out directly at the exit of the irradiation chamber 23. It can also be carried out after being wound onto a final receiving reel 26. In this case, it is preferable to unwind the strand from the reel from the outermost axial end of the strand to avoid helical deformation. Indeed, unwinding the strand from the innermost axial end of the reel causes helical deformation, which can be detrimental to the breaking strength.

[0113] Examples of Measurement Methods

[0114] Mechanical properties

[0115] 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.

[0116] The measurements were carried out on CVR single strands with vinyl ester resins or with isosorbide-dimethacrylate (ISM) resins.

[0117] 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%)).

[0118] The 240 mm single-strand samples were placed under tension between the jaws (distance between the jaws: 130 mm) and subjected to traction at a nominal speed of 50 m / min. All results given are an average of 10 measurements.

[0119] Viscosity

[0120] Viscosity measurements were performed using the Anton-Paar ViscoQC 300 rotary viscometer at 25°C and atmospheric pressure. The geometries used were B-SC4-18 and B-SC4-27 with a shear slope between 30% and 100%. The reference oils, which came with a certificate of analysis and were recommended by Anton-Paar, were supplied by VWR. Measurements were performed according to ISO 3219 (2021).

[0121] Glass transition temperature

[0122] The glass transition temperature (Tg) of the resin compositions was measured by thermomechanical analysis (TMA) using a Mettler Toledo TMA 40 instrument controlled by a TC15 TA controller. Cylindrical samples (2 mm in diameter) of 10 mg were photocured for 5 seconds under an Omnicure lamp with a wavelength of 365 nm. The sample was placed between flat, circular Inconel discs and mounted centrally between the glass stage and the probe. The experiment began at 25°C, and the sample was held for 5 min under a static load of 0.28 N, then heated to 250°C at a rate of 10°C / min (rate under a 0.28 N load in a nitrogen atmosphere). The sample displacement was continuously recorded as a function of temperature. All measurements were performed three times to ensure accuracy.The STARe evaluation software was used to determine the glass transition temperature as the inflection point of the curve.

[0123] Synthesis of isosorbide dimethacrylate

[0124] Isosorbide dimethacrylate was synthesized according to the protocol below.

[0125] Dried isosorbide (40 g, 273.71 mmol) commercially available from Sigma-Aldrich was added to a 500 mL two-necked round-bottom flask equipped with a condenser under a nitrogen atmosphere, in the presence of 4-(dimethylamino)pyridine (1.67 g, 13.69 mmol). After 15 minutes of nitrogen purging, methacrylic anhydride (108 mL, 684.27 mmol) was added all at once. The mixture was then stirred at 500 rpm with an oval magnetic stir bar (40 x 20 mm) at 65°C without disturbance for 18 hours. After the reaction, the resulting mixture was subsequently purified using aqueous hydrochloric acid (pH = 4) (2 x 160 mL), saturated aqueous sodium bicarbonate (3 x 160 mL), deionized water (160 mL), and saturated brine (2 x 100 mL), and further dried using magnesium sulfate.Finally, the product was dried in a rotary evaporator to give a transparent to pale yellow isosorbide-dimethacrylate, with a yield of more than 75% by mass.

[0126] Preparation of resin compositions

[0127] Three resin compositions were prepared (Cl to C3).

[0128] For each composition, the photoinitiator (“Omnirad 819” from IGM) was used. The photoinitiator concentration was 1.5% by weight relative to the total weight of the resin composition.

[0129] When a vinyl ester resin was available, the vinyl ester resin (“ATLAC E-NOVA FW2045” from AOC) was used. When an isosorbide dimethacrylate (ISM) resin was available, the ISM resin, made from isosorbide dimethacrylate synthesized according to the protocol described above, was used.

[0130] Vinylester resin includes styrene as a reactive diluent, whereas ISM resin does not include a reactive diluent.

[0131] When a crosslinking agent was present (triacrylate hardener (“SR 368” from Sartomer)), the concentration was 15% by weight relative to the total weight of the resin composition. The C1 to C3 compositions are summarized in Table 1 below:

[0132] [Table 1]

[0133] Preparation of single strands in CVR

[0134] 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, and a length of 4 m (single-strands M1 to M3). The single-strands M1 to M3 comprise resin compositions Cl to C3, respectively.

[0135] The glass filaments of the monostrands M1 to M3 were "R25H" 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 crosslinked resin was 70 / 30.

[0136] The mechanical properties of the M1 to M3 single-strand resins and the glass transition temperature of the Cl to C3 resin compositions are presented in Table 2 below. The tensile strength is expressed in MPa.

[0137] [Table 2]

[0138] The results presented above show that the presence of a resin comprising at least one monomer unit of formula (I) allows for a resin with a higher glass transition temperature, which has the advantage of being usable at higher temperatures. Indeed, the glass transition temperature of composition C3 in the M3 single strand according to the invention is higher than that of composition Cl in the control M1 single strand and of composition C2 in the comparative M2 single strand.

[0139] Furthermore, increasing the glass transition temperature of the resin composition is achieved without significantly compromising the mechanical properties of the M3 single strand, despite the absence of a crosslinking agent other than the photoinitiator. The fact that the M3 single strand exhibits mechanical properties similar to those of the M2 single strand represents a highly advantageous benefit, directly related to the final industrial cost.

[0140] Another extremely interesting advantage is related to the absence of reactive diluent in the C3 composition present within the M3 monostrand, unlike the Cl and C2 compositions, from an environmental point of view.

[0141] Finally, thanks to the presence of the resin comprising at least one monomer unit of formula (I), exhibiting a lower viscosity, the implementation of the manufacturing process of a single strand is easier.

Claims

1. DEMANDS 1. A method for manufacturing at least one single-strand filament-resin composite comprising filaments embedded in a crosslinked resin, comprising the following steps: a) creating a straight arrangement of filaments and driving this arrangement in a direction of travel; b) contacting 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 chosen from the group consisting of resins comprising at least one monomer unit of the following formula (I): (I), in which: Ri and R2, whether identical or different, represent, independently of each other, a hydrogen atom, a group containing an acrylate function or a group containing a methacrylate function, and provided that Ri and R2 do not both represent a hydrogen atom; - at least one photoinitiating agent; c) passing said impregnated material through a calibration die having a predefined surface area and shape, to impose a single-strand shape upon it; d) downstream of the die, in a crosslinking chamber, polymerizing the resin composition under the action of ultraviolet or visible radiation, the crosslinking chamber comprising a tube transparent to ultraviolet or visible light, called a crosslinking tube, through which the single strand being formed passes.

2. A method according to claim 1, characterized in that Ri and R2 represent an identical group.

3. A method according to claim 1 or 2, characterized in that Ri and R2 both represent a methacrylate group.

4. A method according to any one of the preceding claims, characterized in that the photocurable resin is chosen from the group consisting of resins comprising said monomer units of formula (I) in a proportion in the range of 55% to 100% by weight, preferably 80% to 100% by weight, more preferably 100% by weight relative to the total weight of the monomer units.

5. A method according to any one of the preceding claims, characterized in that the percentage of photocurable resin in the resin composition is in the range of 82.5% to 99.5% by weight, preferably 90% to 99.5% by weight, more preferably 95% to 99% 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 their mixtures, preferably from the group consisting of mono(acyl)phosphine oxides, bis(acyl)phosphine oxides and their mixtures.

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 0.5% to 2% by weight, more preferably 1% to 2% by weight relative to the total weight of the resin composition.

8. A process according to any one of the preceding claims, characterized in that the resin composition is free of a crosslinking agent, other than a photoinitiator.

9. A process according to any one of the preceding claims, characterized in that the resin composition is free of reactive diluent selected from the group consisting of styrene, 2-hydroxymethacrylate, methyl methacrylate, methyl acrylate, furfuryl methacrylate, and mixtures thereof, preferably free of reactive diluent.

10. Composite based on at least one reinforcing element and at least one crosslinked resin composition as defined in any one of the preceding claims, characterized in that it is a single strand of filament-resin composite comprising filaments embedded in said crosslinked resin composition.

11. Composite according to claim 10, 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.

12. Composite according to claim 10 or 11, characterized in that the filaments represent 65% to 85% by weight, preferably 70% to 80% by weight of the monostrand, and the crosslinked resin represents 15% to 35% by weight, preferably 20% to 30% by weight of the monostrand.

13. Composite according to any one of claims 10 to 12, characterized in that the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

14. Finished article or semi-finished product comprising at least one monostrand as defined in any one of claims 10 to 13.

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