Method for producing a monofilament made of filament-resin composite comprising filaments embedded in a crosslinked resin, using a specific resin composition

Abstract

The present invention relates to a method for producing at least one monofilament made of filament-resin composite 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 the 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 typically include a photocurable resin, a photoinitiator, and a crosslinking agent. These resin compositions generally have a high manufacturing cost.

[0016] Furthermore, experience shows that single-strand fibers can still be improved. It is also desirable to be able to manufacture single-strand fibers at higher speeds in order to reduce the final industrial cost.

[0017] Description of the invention

[0018] The Applicant unexpectedly discovered that the presence of a filler at a specific concentration in a resin composition improved performance. In particular, the Applicant unexpectedly discovered that a filler at a specific concentration increased the production rate of a single strand, and potentially the glass transition temperature of resin compositions containing this filler, without degrading mechanical properties such as tensile strength and elongation at break.

[0019] 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:

[0020] - at least one photocurable resin;

[0021] - at least one filler with a concentration ranging from 0.5% to 2.5% by weight relative to the total weight of the resin composition; and

[0022] - 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.

[0023] The invention also relates to a composite based on at least one reinforcing element and at least one resin composition.

[0024] Another object of the invention is the use of at least one filler present in a resin composition at a specific rate for the production rate of a single strand, and possibly the glass transition temperature of said resin composition.

[0025] In this application, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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).

[0030] In this application, the term "fibre" is equivalent to the term "monofurin". Thus, the two terms may be used interchangeably.

[0031] 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 preferentially designates the interval represented by the expression "between a and b."

[0032] Brief description of the figures

[0033] [Fig. 1] Figure 1 represents a diagram of the process of synthesizing the single strand according to the invention before the latter is cut to a determined length.

[0034] [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.

[0035] Description of the invention

[0036] As previously stated, a single strand of filament-resin composite comprising filaments embedded in a crosslinked resin is manufactured according to the process according to the invention.

[0037] The process for manufacturing said single strand, which is particularly advantageous, comprises the following steps:

[0038] - the speed (Vir) of passage of the single strand in the irradiation chamber is greater than 50 m / min;

[0039] - 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;

[0040] - 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.

[0041] Advantageously, the speed (Vir) of passage of the single strand in the irradiation chamber is greater than 100 m / min, preferably greater than 120 m / min, more preferably is within a range of 125 to 160 m / min, even more preferably from 130 to 160 m / min.

[0042] All the steps (arrangement, degassing, impregnation, calibration, polymerization, possible winding, and cutting) of the process of the invention are, independently of one another, steps known to those skilled in the art, as are the materials (multifilament fibers) used; they have, for example, been described in one or both of applications EP 1 074 369 A1 and EP 1 174 250 A1. Furthermore, as indicated above, the resin composition used in the manufacturing process according to the invention comprises:

[0043] - at least one photocurable resin;

[0044] - at least one filler with a concentration ranging from 0.5% to 2.5% by weight relative to the total weight of the resin composition; and

[0045] - at least one photoinitiating agent.

[0046] A photocurable resin can be any resin capable of curing 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.

[0047] 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, and even more preferably from the group consisting of vinyl ester resins and their mixtures. As is known to those skilled in the art, these photocurable resins may contain a diluent, such as styrene, at a concentration of up to approximately 40% by weight of the photocurable resin. Commercially available photocurable resins are often sold diluted.

[0048] The term "polyester resin" commonly refers to unsaturated polyester resin. "Vinylester" resins, on the other hand, are well-known in the field of composite materials.

[0049] Without this definition being exhaustive, vinyl ester resin is preferably of the epoxy vinyl ester type. A vinyl ester resin, particularly of the epoxy type, is preferred if it is at least partially 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.

[0050] For example, a novolac-based epoxyvinylester resin (part in brackets in formula I below) corresponds, in a known manner, to the following formula (I): An epoxyvinylester resin based on bisphenol A (part in brackets of formula (II) below) corresponds, for example, to the formula (the "A" indicating that the product is manufactured using acetone):

[0051] A novolac and bisphenolic type epoxyvinylester resin has shown excellent results. As an example of such a resin, we can cite in particular the vinyl ester resins "ATLAC 590" and "ATLAC E-Nova FW 2045" from the company AOC (diluted with about 40% styrene) described in applications EP-A-1 074 369 and EP-A-1 174 250.

[0052] The proportion of photocurable resin in the resin composition may be in the range of 80% to 99% by weight, preferably more than 94.5% to 99% by weight, and more preferably more than 96% to 98% by weight, relative to the total weight of the resin composition. When the photocurable resin includes a diluent, the aforementioned proportions of photocurable resin include said diluent.

[0053] Advantageously, the filler is chosen from the group consisting of nano-clays, silica, carbon black, microcrystalline cellulose, zinc oxide, zirconium oxide, graphite, silicon dioxide and mixtures thereof, preferably nano-clays, microcrystalline cellulose, graphite, zirconium oxide and mixtures thereof, more preferably nano-clays, microcrystalline cellulose, zirconium oxide and mixtures thereof.These fillers are commercially available, for example, nano-clay "Nanoclay 682624" from Sigma-Aldrich, silica "904376" from Sigma-Aldrich, carbon black N232 from Cabot, microcrystalline cellulose "Cellulose microcrystalline, powder" from Sigma-Aldrich, zinc oxide "Zinc Oxide Nanopowder" from Nanografi, zirconium oxide "Zirconium oxide nanopowder" from Nanografi, graphite "Graphite (C) Micron Powder" from Nanografi, silicon dioxide "Silicon dioxide Micron Powder" from Nanografi.

[0054] Advantageously, the filler content is in the range of 0.5% to 2% by weight, preferably 0.7% to 1.3% by weight, and more preferably 0.8% to 1.2% by weight, relative to the total weight of the resin composition. Advantageously, the filler is in the form of particles with an average diameter in the range of 0.015 to 50 µm, preferably 0.5 to 40 µm, and preferably 1 to 30 µm. The average diameter of the filler can be easily measured by image analysis using an optical microscope, a scanning electron microscope, image analysis of a photograph using a transmission microscope, or analysis of X-ray scattering data.

[0055] 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.

[0056] 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.

[0057] Type I photoinitiators are selected from the group consisting of benzoin ethers, benzyl ketals, alpha-dialkoxyacetophenones, alpha-hydrodyalkylphenones, alpha-aminoalkylphenones, phosphine oxides, and mixtures thereof. Preferably, the photoinitiating agent is selected from the group consisting of phosphine oxides and mixtures thereof. The phosphine oxide may advantageously be a bis(acyl)phosphine oxide.

[0058] 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).

[0059] The rate of photoinitiator agent 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.

[0060] 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 1% by weight relative to the total weight of the resin composition.

[0061] Preferably, the resin composition is free of crosslinking agents, other than photoinitiators.

[0062] Examples of crosslinking agents other than photoinitiators include multifunctional acrylate or methacrylate derivatives and peroxides well known to those skilled in the art.

[0063] 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.

[0064] As previously stated, the invention also relates to a composite based on at least one reinforcing element and at least one resin composition.

[0065] 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.

[0066] The wire element may be metallic or textile. A "wire element" is defined as an element with 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, and in particular rectangular, square, or oval. Advantageously, the reinforcing element is a reinforcing fiber, preferably selected from the group consisting of glass, basalt, carbon, aramid, polyester, polyethylene, boron, ceramic fibers and their combinations; preferably the reinforcing fiber is selected from the group consisting of glass fibers.

[0067] The composite comprising a reinforcing element is preferably 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 preferably a single-strand FRC having filaments embedded in a resin crosslinked from the resin composition as defined above.

[0068] 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.

[0069] Thus, preferably, the monostrand is made of glass-resin composite (abbreviated "CVR").

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Advantageously, the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

[0075] 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.

[0076] The average diameter covers both monofilament strands that are essentially cylindrical (with a circular cross-section) and strands of different shapes, for example, oblong strands (more or less flattened) or strands with a rectangular cross-section. 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 enclosing the monofilament, in other words, the diameter of the circumscribed circle surrounding its cross-section.

[0077] The glass transition temperature (Tg) of the crosslinked resin is preferably greater than 175°C, preferably greater than 180°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 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, according to a ramp of 10°C / min).

[0078] Another object of the invention is the use of a filler present in a resin composition at a rate in the range of 0.5% to 2.5% by weight relative to the total weight of the resin composition to increase the production rate of a single strand in filament-resin composite, and possibly the glass transition temperature of the resin composition.

[0079] Advantageously, said use to increase the production speed of a single strand, and possibly the glass transition temperature of the resin composition is carried out without degradation of mechanical properties, such as tensile strength, elongation at break.

[0080] The various preferred embodiments described above in the context of the manufacturing process according to the invention and the composite according to the invention are applicable for said use according to the invention.

[0081] 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.

[0082] Figure 1 attached schematically illustrates in a very simple way an example of a device 10 allowing the production of single strands in CVR.

[0083] 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 11b fibers. 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.

[0084] 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.

[0085] As already demonstrated by application EP1174250A1, 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.

[0086] Upon exiting the vacuum chamber 13 and the outlet tube 13b, the fiber arrangement 12 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 (e.g., "ALTAC® E-Nova FW 2045" from AOC). 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.

[0087] Preferably, the length of the impregnation chamber is several meters, for example between 2 and 10 m, especially between 3 and 5 m.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 circulates; 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.

[0092] The polymerization or UV irradiation chamber then has the function of polymerizing and cross-linking the resin under the action of UV light.

[0093] 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 whose focal point 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] In this example, the irradiation tube 23 is traversed by a nitrogen current.

[0098] The irradiation conditions are preferentially adjusted so that, at the outlet of the impregnation chamber, the temperature of the CVR single strand, measured on its surface (for example using a thermocouple), is greater than the Tg of the crosslinked resin (in other words greater than 190°C), and more preferably less than 270°C.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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 "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 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. Examples

[0103] Measurement methods

[0104] Mechanical properties

[0105] 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.

[0106] The measurements were carried out on CVR single strands with or without crosslinking agent, and with or without filler.

[0107] 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%)).

[0108] The 240 mm samples tested underwent tensile testing at a nominal speed of 50 m / min, with a preload of 0.5 MPa (distance between the jaws: 150 mm). All results given are an average of 10 measurements.

[0109] Glass transition temperature

[0110] The glass transition temperature (Tg) of the resin compositions is measured by DSC (Differential Scanning Calorimetry), on the second pass, according to the ASTM D3418 of 1999 standard (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.

[0111] Preparation of resin compositions

[0112] Six resin compositions were prepared (Cl to C6).

[0113] For each composition, the vinyl ester resin (“ATLAC E-NOVA FW2045” from AOC) and the photoinitiator (“Omnirad 819” from IGM) were used. The photoinitiator concentration was 1.5% by weight relative to the total weight of the resin composition.

[0114] 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. When a nano-clay filler was present (product number 682624 sold by Sigma-Aldrich), the concentration was 1% or 3% by weight relative to the total weight of the composition.

[0115] When a zirconium oxide or microcrystalline cellulose filler was present, the rate was 1% by weight relative to the total weight of the composition.

[0116] The compositions Cl to C6 are summarized in Table 1 below:

[0117] [Table 1]

[0118] Preparation of single strands in CVR

[0119] 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, 130, or 150 m / min, an irradiation time Dir of the single-strand in the irradiation chamber of 2.2, 1.8, or 1.6 s, respectively, and a length of 4 m for the irradiation chamber (singles M1 to M6). The single-strands M1 to M6 comprise resin compositions Cl to C6, respectively.

[0120] The glass filaments of the M1 to M6 monostrands were Owens Corning "R25H" filaments. Their diameter was 0.54 mm, the tex density of the glass fibers was 300 g / km, and the mass ratio of glass fibers to crosslinked resin was 70 / 30. The mechanical properties of the M1 to M6 monostrands and the glass transition temperature of the C1 to C6 resin compositions are presented in Table 2 below. The tensile strength is expressed in MPa.

[0121] [Table 2]

[0122] The results presented above show that the presence of a filler at a rate of 1% by weight improves the glass transition temperature of the resin composition. Indeed, the glass transition temperatures of the C3, C5, and C6 compositions present in the M3, M5, and M6 single-strands, respectively, according to the invention, are higher than that of the Cl composition present in the control single-strand M1.

[0123] It is also observed that the glass transition temperatures of compositions C3, C5 and C6 present in the single strands M3, M5 and M6, respectively, according to the invention are similar to that of composition C2 present in the comparative single strand M2.

[0124] This finding is an unexpected result. Indeed, it is known to those skilled in the art that the presence of a crosslinking agent in a resin composition improves the glass transition temperature of said resin composition (see composition C2). It is also known that the most expensive ingredient in a resin composition is the crosslinking agent, which must also be present in a large quantity. The fact that compositions C3, C5, and C6 have a glass transition temperature similar to that of composition C2 represents a significant advantage. The final industrial cost of manufacturing a resin composition and a single strand will be considerably reduced.

[0125] The results presented above also show that the presence of a load at a rate of 1% by weight makes it possible to obtain advantageous mechanical properties.

[0126] Indeed, the elongation at break and the tensile strength of the M3, M5 and M6 single strands are similar to those of the M2 single strand. In other words, no degradation of mechanical properties is observed, despite the increased production speed and the absence of a crosslinking agent.

[0127] Here again, the fact that the M3, M5 and M6 single strands have similar mechanical properties to the M2 single strand represents an extremely interesting advantage, linked to the final industrial cost.

[0128] It is also observed that the mechanical properties of the M3 single strand are improved compared to those of the M4 single strand. It is thus clearly shown that the load factor is critical for the mechanical properties, representing an extremely interesting advantage.

[0129] Finally, the results show that thanks to the presence of a filler at a rate of 1% by weight, the process is implemented at a higher speed. Indeed, the production speed of the M3, M5, and M6 single strands is significantly higher than that of the M1 and M2 single strands.

Claims

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; - at least one filler with a concentration ranging from 0.5% to 2.5% by weight relative to the total weight of the resin composition; and - 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 process according to claim 1, characterized in that the photocurable resin is 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.

3. A method according to claim 1 or 2, characterized in that the percentage of photocurable resin in the resin composition is in the range of 80% to 99% by weight, preferably more than 94.5% to 99% by weight, more preferably more than 96% to 98% by weight relative to the total weight of the resin composition.

4. A process according to any one of the preceding claims, characterized in that the filler is chosen from the group consisting of nano-clays, silica, carbon black, microcrystalline cellulose, zinc oxide, zirconium oxide, graphite, silicon dioxide and mixtures thereof, preferably nano-clays, microcrystalline cellulose, graphite, zirconium oxide and mixtures thereof, more preferably nano-clays, microcrystalline cellulose, zirconium oxide and mixtures thereof.

5. A method according to any one of the preceding claims, characterized in that the charge is in the form of particles whose average diameter is in a range from 0.015 to 50 pm, preferably from 0.5 to 40 pm, preferably from 1 to 30 pm.

6. A method according to any one of the preceding claims, characterized in that the filler content is in the range of 0.5% to 2% by weight, preferably 0.7% to 1.3% by weight, more preferably 0.8% to 1.2% by weight relative to the total weight of the resin composition.

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 process according to any one of the preceding claims, characterized in that the resin composition further comprises at least one crosslinking agent, other than a photoinitiator, in a proportion of less than or equal to 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.

9. A process according to any one of claims 1 to 7, characterized in that the resin composition is free from a crosslinking agent, other than a photoinitiator.

10. Composite based on at least one reinforcing element and at least one resin composition as defined in any one of the preceding claims.

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 it is a single strand of filament-resin composite comprising filaments embedded in said resin composition, said resin composition being crosslinked.

13. Composite according to claim 12, 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.

14. Composite according to claim 12 or 13, characterized in that the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

15. Use of a filler present in a resin composition at a rate in the range of 0.5% to 2.5% by weight relative to the total weight of the resin composition to increase the production rate of a single strand of filament-resin composite, and possibly the glass transition temperature of said resin composition.

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