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] Nevertheless, in these composite reinforcements, the resin compositions used classically include a photocurable resin, which is generally obtained from an oligomer in viscous form, a photoinitiator which is usually in solid form, and a crosslinking agent which is usually waxy.

[0016] One of the many difficulties today associated with the preparation of resin compositions is mixing these compounds which are in different states.

[0017] In particular, with regard to the waxy crosslinking agent, it is necessary to anticipate the melting of the product before use, which consumes a significant amount of energy. Furthermore, the product is sensitive to mechanical stress. It is also sticky on metallic surfaces, making it difficult to handle and measure.

[0018] Regarding the solid photoinitiator, material is generally lost during the preparation of resin compositions because the product sticks to the reactor valves and pipes. Furthermore, mixing it in a reactor containing liquids is difficult.

[0019] Thus, industrial constraints are numerous, and resin compositions generally have a high manufacturing cost. This high cost is not only due to the preparation of the resin compositions; it also stems from the high price of the crosslinking agent on the market.

[0020] Therefore, it would be desirable to be able to manufacture single strands with a reduced industrial cost.

[0021] Description of the invention

[0022] The Applicant unexpectedly discovered that the presence of a specific photoinitiator and crosslinking agent reduced the industrial cost of manufacturing crosslinked resin compositions within monostrands. Furthermore, their presence also lowered the viscosity of the resin compositions, facilitating the implementation of manufacturing processes for monostrands incorporating these compositions, without degrading the mechanical properties of the monostrands or the glass transition temperature of the crosslinked resin compositions.

[0023] 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:

[0024] - at least one photocurable resin having a viscosity at 25 °C less than or equal to 1000 mPa.s;

[0025] - a liquid photoinitiator at 20 °C;

[0026] - a crosslinking agent other than the photoinitiator having a viscosity at 25°C less than or equal to 1200 mPa.s; 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 the crosslinking tube, through which the single strand being formed passes.

[0027] The invention also relates to a composite based on at least one reinforcing element and at least one crosslinked resin composition.

[0028] In this application, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0029] The term "composition based on" refers to a composition comprising a mixture and / or the in-situ reaction product of the various constituents used, some of which may react and / or are intended to react with each other, at least partially, during the different stages of manufacturing the composition; the composition may thus be in a fully or partially crosslinked state or in a non-crosslinked state. "Embedded" means that the reinforcing element is in direct contact with the resin composition over its entire surface, with the possible exception of the composite's cutting edges.

[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 preferentially designates 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 crosslinked resin is manufactured according to the process according to the invention.

[0039] The process for manufacturing said single strand, which is particularly advantageous, comprises the following steps:

[0040] - the speed (V) of passage of the single strand in the irradiation chamber is greater than 50 m / min; - the duration (D) of 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 1 174 250 Al.

[0043] Furthermore, as previously stated, the resin composition used in the manufacturing process according to the invention comprises:

[0044] - at least one photocurable resin having a viscosity at 25 °C less than or equal to 1000 mPa.s;

[0045] - a liquid photoinitiator at 20 °C; and

[0046] - a crosslinking agent other than the photoinitiator having a viscosity at 25°C less than or equal to 1200 mPa.s.

[0047] Within the scope of the present invention, viscosity can be determined at 25°C and atmospheric pressure, according to the Brookfield method. Brookfield viscosity is a known characteristic of liquid substances. Apparent viscosity according to the Brookfield method is measured at a given temperature (e.g., 25°C) in accordance with the European and international standard EN ISO 2555 (1999). For example, a type A viscometer (e.g., model RVT) or a type B viscometer (e.g., model HAT) is used, preferably at a rotation frequency of 10 or 20 min⁻¹. -1 with a number of the moving part (1 to 7) adapted to the range of viscosity measured (according to Annex A of standard EN ISO 2555). Viscosity is expressed in mPa.s or centipoise (cP) (1 cP = 1 mPa.s).

[0048] Viscosity can also be determined at a temperature of 25°C and atmospheric pressure, for example, using the ViscoQC 300 rotary viscometer from Anton-Paar. The geometries used can be B-SC4-18 and B-SC4-27 with a shear slope between 30% and 100%. Standard oils with a certificate of analysis, recommended by Anton-Paar, can be obtained from VWR. Measurements can be performed according to ISO 3219 (2021). The 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] For example, a novolac-based epoxyvinylester resin (part in brackets in formula I below) corresponds, in a known manner, to the following formula (I):

[0053] 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):

[0054] 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 174250.

[0055] The said photocurable resin may contain a reactive diluent, such as styrene, at a concentration of up to approximately 40% by weight of the photocurable resin. As is known to those skilled in the art, commercially available photocurable resins are often sold diluted.

[0056] The said photocurable resin advantageously exhibits a viscosity at 25 °C ranging from 500 to 1000 mPa.s.

[0057] The proportion of photocurable resin in the resin composition may be in the range of 80% to 97.5% by weight, preferably in the range of 85% to 95% by weight, and more preferably in the range of 87% to 93% 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.

[0058] 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.

[0059] In the context of the present invention, the photoinitiator is liquid at 20 °C.

[0060] For the purposes of this invention, "liquid photoinitiator at 20°C" means a photoinitiator having a melting point of 20°C or less and at atmospheric pressure (1013.10 5 Pa).

[0061] For the purposes of the present invention, the melting point corresponds to the temperature of the most endothermic peak observed in thermal analysis (differential scanning calorimetry or DSC) as described in ISO 11357-3; 1999. The melting point can be measured using a differential scanning calorimeter (DSC), for example the calorimeter sold under the name "MDSC 2920" by TA Instruments.

[0062] 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.

[0063] 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.

[0064] Advantageously, 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. The phosphine oxide may advantageously be a bis(acyl)phosphine oxide.

[0065] As an example of a photoinitiator that can be used in the context of the present invention, we can mention the mixture of bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and ethyl(2,4,6-trimethylbenzoyl)-phenyl phosphinate (“Omnirad 2100” from IGM) or ethyl(2,4,6-trimethylbenzoyl)-phenyl phosphinate (TPO-L) from IGM.

[0066] 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.

[0067] As previously stated, the crosslinking agent other than the photoinitiator has a viscosity at 25°C less than or equal to 1200 mPa.s.

[0068] Advantageously, said crosslinking agent has the following formula (I): C(RI)(R.2)(R3)(R4) (I), in which Ri, R2, R3 and R4, identical or different, represent, independently of each other, an acrylate group, a methacrylate group or a vinyl group.

[0069] Advantageously, Ri and R4 are identical, preferably Ri and R4 all represent an acrylate group. The viscosity at 25 °C of said crosslinking agent other than the photoinitiator is advantageously less than or equal to 1100 mPa.s, preferably in the range of 400 mPa.s to 1100 mPa.s, more preferably in the range of 700 mPa.s to 1100 mPa.s, and even more preferably in the range of 900 mPa.s to 1100 mPa.s.

[0070] Advantageously, the rate of said crosslinking agent is in the range of 2% to 15% by weight, preferably in the range of 4% to 12% by weight, more preferably in the range of 6% to 9% by weight relative to the total weight of the resin composition.

[0071] The resin composition advantageously has a viscosity at 25°C less than or equal to 1000 mPa.s, preferably from 300 mPa.s to 1000 mPa.s, more preferably from 350 mPa.s to 650 mPa.s, even more preferably from 400 mPa.s to 550 mPa.s.

[0072] The invention also relates to a composite based on at least one reinforcing element and at least one crosslinked resin composition as described above.

[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] The composite, which includes a reinforcing element, is preferably a single-strand filament-resin composite (hereinafter "FRC") with filaments embedded in the crosslinked resin composition. In other words, the composite, which includes a reinforcing element, is preferably a single-strand FRC with filaments embedded in a crosslinked resin composition. The filaments may be selected from the group consisting of glass, basalt, polyester, and combinations thereof, preferably from the group consisting of glass filaments.

[0077] Thus, preferably, the monostrand is made of glass-resin composite (abbreviated "CVR").

[0078] Examples of fibers that can be used in the context of the present invention include Owens Corning “R25H” or “SE 1200” glass fibers, Nippon Electric Glass “AR320S-920S”, “AR640S-920S” or “AR1200S-920S” alkali-resistant glass fibers, Owens Corning “Cem-fil”, 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Advantageously, the filaments each have an average diameter ranging from 5 to 30 pm, more preferably from 10 to 20 pm.

[0083] 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.

[0084] The single strand advantageously has an average 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.

[0085] 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.

[0086] The mean diameter DM is advantageously defined as follows: DM = (S / 7i), 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.

[0087] 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.

[0088] The glass transition temperature (Tg) of the crosslinked resin is preferably above 175°C, preferably above 180°C, and in particular above 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 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).

[0089] The composite, based on at least one reinforcing element, can be manufactured by any method known to those skilled in the art, depending on the object to be produced. Figure 1 in the appendix provides a very simple schematic example of a device 10 for producing single-strand composites.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] At the outlet of 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 impregnation composition 17 based on a hardenable vinyl ester resin (for example "ATLAC® E-Nova FW 2045" from the company AOC). As an example, composition 17 further comprises (for example, 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, a mixture of bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and ethyl(2,4,6-trimethylbenzoyl)-phenyl phosphinate ("Omnirad 2100" from IGM). Of course, impregnation composition 17 is in liquid form.

[0094] Preferably, the length of the impregnation chamber is several meters, for example between 2 and 10 m, especially between 3 and 5 m.

[0095] 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.

[0096] 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.

[0097] Preferably, the length of the calibration area is several centimeters, for example between 5 and 50 cm, in particular between 5 and 20 cm.

[0098] 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 preferentially essentially circular.

[0099] 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.

[0100] The polymerization or UV irradiation chamber then has the function of polymerizing and cross-linking the resin under the action of UV light.

[0101] 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.

[0102] Even more preferentially, the linear power delivered by each UV irradiator is between 2,500 watts and 12,000 watts per meter, in particular within a range of 3,000 watts to 10,000 watts per meter.

[0103] Suitable UV heaters for this 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 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.

[0104] The diameter of the irradiation tube (preferably made of glass) is preferably between 10 and 80 mm, more preferably between 20 and 60 mm.

[0105] Preferably, the length of the irradiation chamber is several meters, for example between 2 and 15 m, especially between 3 and 10 m.

[0106] In this example, the irradiation tube 23 is traversed by a nitrogen current.

[0107] The irradiation conditions are preferably adjusted so that, upon exiting the impregnation chamber, the temperature of the CVR monostrand, measured on its surface (for example, using a thermocouple), is higher than the Tg of the crosslinked resin (in other words, higher than 175°C), and more preferably lower than 200°C. Once the resin has polymerized (cured), the CVR monostrand 25, now in its solid state, carried in the direction of arrow F, then arrives at its final receiving reel 26.

[0108] 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.

[0109] 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 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.

[0110] 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.

[0111] Examples

[0112] Measurement methods

[0113] Mechanical properties

[0114] 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.

[0115] The measurements were carried out on CVR single strands with different crosslinking agents and different photoinitiators. Before measurement, these single strands were subjected to prior conditioning (storage of the single strands 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%)).

[0116] 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.

[0117] Glass transition temperature

[0118] 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.

[0119] Viscosity at 25°C

[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] Preparation of resin compositions

[0122] Four resin compositions were prepared (Cl to C4).

[0123] For each of the compositions, vinyl ester resin (“ATLAC E-NOVA EW2045” from the company AOC) was used.

[0124] Two different photoinitiators were used (the "Omnirad 819 - solid" photoinitiator and the "Omnirad 2100 - liquid" photoinitiator, both from the company IGM). The photoinitiator content was 1.5% by weight relative to the total weight of the resin composition.

[0125] Two crosslinking agents were used (hardener "SR 368" and hardener "SR 295," both from Sartomer). The crosslinking agent content was 15% and 8% by weight, respectively, relative to the total weight of the resin composition. Hardener "SR 295" has a viscosity of 1071 mPa·s at 25 °C.

[0126] The Cl to C4 compositions are summarized in Table 1 below:

[0127] [Table 1]

[0128] Preparation of single strands in CVR

[0129] 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 M4). The single-strands M1 to M4 comprise resin compositions Cl to C4, respectively.

[0130] The glass filaments of the monostrands M1 to M4 were "R25H" filaments from the Owens Coming company. 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.

[0131] The mechanical properties of the M1 to M4 single-strand resins, and the glass transition temperature and viscosity at 25°C of the Cl to C4 resin compositions are presented in Table 2 below. The tensile strength is expressed in MPa.

[0132] [Table 2]

[0133] The results presented above show that the combined presence of a liquid photoinitiator at 20°C and a crosslinking agent with a viscosity at 25°C of 1200 mPa or less does not affect the mechanical properties of the monostrands or the glass transition temperature of the crosslinked resin compositions within the monostrands. Furthermore, their combined presence also reduces the viscosity at 25°C of the crosslinked resin compositions.

[0134] This maintenance of mechanical properties is an unexpected result. With the use of a liquid photoinitiator at 20°C and a crosslinking agent with low viscosity at 25°C, a person skilled in the art would indeed expect a degradation of the properties of the single strands.

[0135] On the contrary, the single strands according to the invention exhibit mechanical properties equivalent to those of conventionally used single strands.

[0136] Furthermore, the crosslinking agent content is lower in the resin compositions present in monostrands.

[0137] This therefore represents an extremely attractive advantage, linked to the final industrial cost.

[0138] Finally, thanks to the lower viscosity of the resin compositions, the implementation of the manufacturing process of a resin composition, and thus of a monostrand comprising this resin composition, is easier.

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 having a viscosity at 25 °C less than or equal to 1000 mPa.s; - a liquid photoinitiator at 20°C; - a crosslinking agent other than the photoinitiator having a viscosity at 25°C less than or equal to 1200 mPa.s; 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 the 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 97.5% by weight, preferably in the range of 85% to 95% by weight, more preferably in the range of 87% to 93% by weight relative to the total weight of the resin composition.

4. 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.

5. A method according to any one of the preceding claims, characterized in that said crosslinking agent has the following formula (I): C(RI)(R.2)(R3)(R4) (I), in which Ri, R2, R3 and R4, identical or different, represent, independently of each other, an acrylate group, a methacrylate group or a vinyl group.

6. A method according to claim 5, characterized in that Ri to R4 are identical, preferably Ri to R4 all four represent an acrylate group.

7. A process according to any one of the preceding claims, characterized in that the viscosity at 25°C of said crosslinking agent is less than or equal to 1100 mPa.s, preferably within a range of 400 mPa.s to 1100 mPa.s, more preferably within a range of 700 mPa.s to 1100 mPa.s, even more preferably within a range of 900 mPa.s to 1100 mPa.s.

8. A process according to any one of the preceding claims, characterized in that the rate of said crosslinking agent is in the range of 2% to 15% by weight, preferably in the range of 4% to 12% by weight, more preferably in the range of 6% to 9% by weight relative to the total weight of the resin composition.

9. A process according to any one of the preceding claims, characterized in that the resin composition has a viscosity at 25 °C less than or equal to 1000 mPa.s, preferably from 300 mPa.s to 1000 mPa.s, more preferably from 350 mPa.s to 650 mPa.s, even more preferably from 400 mPa.s to 550 mPa.s.

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.

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 crosslinked resin composition.

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.

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