Method for improving the alkali resistance of a substrate

Abstract

The present invention relates in particular to a method for improving the alkali resistance of a substrate, in particular a monofilament made of filament-resin composite comprising filaments embedded in a crosslinked resin, comprising a plasma treatment step for applying at least one organosilicon compound to the surface of the substrate, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for improving the alkali resistance of a substrate

[0003] technical field

[0004] The present invention relates to improving the alkali resistance of a substrate, such as a single strand of filament-resin composite. It has applications particularly for concrete reinforcement, but also for reducing the weight of concrete, and for reducing or preventing concrete cracking.

[0005] Concrete is arguably the most widely used construction material today due to its high compressive strength, durability, longevity, and resilience. These properties make it a material of choice, particularly in the fields of building construction, roadworks, and civil engineering structures.

[0006] Concrete is primarily composed of aggregates held together by a binder, most often Portland cement. To improve the properties of concrete, additives such as ultrafine particles (silica fume, for example), superplasticizers (also called water reducers), or metallic, synthetic, or mineral fibers are commonly used.

[0007] Although very resistant to compression, concrete has low tensile strength, often accompanied by the appearance of cracks.

[0008] To combat this problem, various approaches have been explored. One well-known solution is the use of reinforcing fibers, due to their advantageous mechanical properties. Reinforcing fibers are thus widely used to make concrete more ductile and improve its resistance to cracking.

[0009] However, metal fibers have the disadvantage of being susceptible to corrosion, which can be detrimental to the longevity of concrete containing such fibers. Furthermore, they often have densities exceeding 7.7 and are therefore not distributed homogeneously in concrete with a lower density (metal fibers tend to sink under the effect of gravity, or even under the effect of vibrations when the concrete is vibrated to remove air bubbles that may have been drawn in during pouring).

[0010] To address this issue, one proposal has been to replace metallic fibers with synthetic fibers. However, the mechanical strength (Young's modulus, tensile strength, for example) of these fibers is not as good as that of metallic fibers. Furthermore, their operating temperature (generally between 100°C and 160°C) is much lower than that of metallic fibers (approximately between 600°C and 900°C), which can limit their use in certain applications.

[0011] It should also be noted that concrete is an alkaline medium. Therefore, it is advantageous to have a substrate that offers good resistance to alkalis.

[0012] The Plaintiff unexpectedly discovered that a plasma treatment step to apply a particular compound to a substrate improved the alkali resistance of said substrate.

[0013] Description of the invention

[0014] The present invention relates to a method for improving the resistance to alkalis of a support comprising a plasma treatment step to apply at least one organosilicon compound to the surface of the support, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

[0015] The invention also relates to a method for manufacturing at least one single strand of filament-resin composite comprising filaments embedded in a crosslinked resin comprising the following steps: a) making a straight arrangement of filaments and driving this arrangement in a direction of advancement; b) bringing said arrangement of filaments into contact with a photocurable resin composition, in liquid state, called impregnation resin, to obtain an impregnated material containing the filaments and the resin composition; c) passing said impregnated material through a calibration die having a predefined surface area and shape cross-section, to impose on it a single strand shape;d) downstream of the die, in a crosslinking chamber, polymerize 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; e) subject the single strand obtained in step (d) to a plasma treatment to apply at least one organosilicon compound to the surface of the straight arrangement of filaments, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

[0016] The invention also relates to a monofilament that can be obtained by the method(s) according to the invention, as well as a filament-resin composite monofilament comprising filaments embedded in a cross-linked resin. Another object of the invention is the use of at least one monofilament according to the invention to reinforce concrete and / or reduce the weight of concrete and / or reduce or prevent cracking of concrete, as well as the use of at least one organosilicon compound comprising no atoms other than silicon, carbon, hydrogen, and oxygen, to improve the alkali resistance of a substrate.

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

[0018] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the 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.

[0019] 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.

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

[0021] By "crosslinked" resin, 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).

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

[0023] 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." Brief description of the figures

[0024] [Fig. 1] Figure 1 represents a diagram of the synthesis process of a single strand in fiber-resin composite.

[0025] [Fig. 2] Figure 2, not shown to scale for ease of understanding, is a drawing representing a cross-section of a single strand of fiber-resin composite.

[0026] Description of the invention

[0027] As previously stated, an organosilicon compound is applied to the surface of a support, said organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

[0028] Of course, for the purposes of the present invention, an "organosilicon compound" is a compound comprising at least one carbon atom and at least one silicon atom.

[0029] Preferably, the support is a single strand of filament-resin composite comprising filaments embedded in a cross-linked resin.

[0030] Furthermore, the invention relates to a method for manufacturing at least one single strand of filament-resin composite comprising filaments embedded in a cross-linked resin, as defined above.

[0031] In each of the two processes according to the invention, a plasma treatment step is implemented.

[0032] Plasma treatment is carried out to apply to said support at least one organosilicon compound comprising no atom other than silicon, carbon, hydrogen and oxygen.

[0033] After the plasma treatment step, the organosilicon compound, which does not include any atoms other than silicon, carbon, hydrogen and oxygen, is found on the surface of the support.

[0034] Advantageously, this application can be carried out using a device capable of implementing a plasma jet with organosilicon precursors at atmospheric pressure.

[0035] By "atmospheric pressure" we mean here that the pressure corresponds approximately to that of the surrounding environment.

[0036] The term distinguishes current plasma technology from low- and high-pressure plasma technologies that require a reaction vessel to maintain a substantial pressure differential with the environment. A person skilled in the art, a specialist in plasma technology, therefore understands that "atmospheric pressure" should not be interpreted as the unit of pressure "atm," defined as being equal to 101,325 Pa.

[0037] By "plasma jet" we mean here a plasma jet and / or a plasma jet afterglow.

[0038] This method of application is well known to those skilled in the art; for example, it was described in application EP 3 586 954 Al.

[0039] Advantageously, the process for manufacturing at least one single strand of filament-resin composite further includes f) a step of cutting the single strand obtained in step (e), preferably to a length of 5 to 85 mm, to obtain cut single strands.

[0040] The process for manufacturing said single strand, which is particularly advantageous, comprises the following steps:

[0041] - the speed (Vk) of passage of the single strand in the irradiation chamber is greater than 50 m / min;

[0042] - the duration (Dk) of passage of the single strand in the irradiation chamber is equal to or greater than 1 s and equal to or less than 10 s;

[0043] - 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.

[0044] 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 and resin compositions) 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] For example, a novolac-based epoxyvinylester resin (part in brackets in formula I below) corresponds, in a known manner, to the following formula (I):

[0050] 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 epoxy vinyl ester resin has shown excellent results. Examples of such a resin include the vinyl ester resins "ATLAC 590" and "ATLAC E-Nova FW 2045" from AOC (diluted with approximately 40% styrene) described in applications EP-A-1 074 369 and EP-A-1 174250. The proportion of photocurable resin in the resin composition may be in the range of 80% to 99.5% by weight, preferably more than 94.5% to 99% by weight, and more preferably more than 96% to 99% 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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).The rate of photoinitiator agent is advantageously within a range of 0.5% to 3% by weight, preferably 1% to 2.5% by weight, preferably 1% to 2% by weight, relative to the total weight of the resin composition.

[0056] 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.

[0057] Thus, preferably, the monostrand is made of glass-resin composite (abbreviated "CVR").

[0058] 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.

[0059] The filaments advantageously represent 60% to 85%, preferably 70% to 80%, by weight of the monostrand in fiber-resin composite and the resin composition represents 15% to 40%, preferably 20% to 30%, by weight, of the monostrand in fiber-resin composite.

[0060] 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.

[0061] Typically, the filaments are present as a single multifilament fiber or as several multifilament fibers bonded 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. Advantageously, each filament has an average diameter ranging from 5 to 30 µm, more preferably from 10 to 20 µm.

[0062] 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.

[0063] 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.

[0064] The single strand in fiber-resin composite advantageously has a length ranging from 10 to 80 mm, preferably from 15 to 60 mm.

[0065] The cut monostrand advantageously presents a length / diameter ratio ranging from 10 to 110, preferably from 20 to 90, more preferably from 25 to less than 80.

[0066] 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).

[0067] As previously stated, the organosilicon compound does not include any atoms other than silicon, carbon, hydrogen, and oxygen.

[0068] Advantageously, the organosilicon compound is chosen from the group consisting of compounds with the formula R x Si-(OR')(4- x) (I), Ri,2,3Si-[O-SiR4,5,ô]n (II) and their mixtures,

[0069] - formula (I) in which:

[0070] * R represents a C1-C4 hydrocarbon group, preferably a C2-C3 alkenyl group;

[0071] * R' represents a hydrocarbon group in C1-C4, preferably in C1-C2; * x is an integer from 1 to 3;

[0072] - formula (II) in which:

[0073] * Ri, R2, R3, R4, Rs, RÔ, identical or different, represent H or a hydrocarbon group in C1-C4, preferably in C1-C2, provided that at least 4 of the groups among Ri, R2, R3, R4, Rs, RÔ represent a hydrocarbon group in C1-C4, preferably at least 2 of the groups among Ri, R2, R3, R4, Rs, RÔ designate H;

[0074] * n is an integer from 1 to 3, preferably n is equal to 1.

[0075] Advantageously, the organosilicon compound is chosen from the group consisting of 1,1,3,3-tetramethyldisiloxane, trimethoxyvinylsilane and their mixture.

[0076] Advantageously, the crosslinked resin is based on at least:

[0077] - a photocurable resin 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;

[0078] - a crosslinking system comprising a photoinitiator agent.

[0079] Preferably, the photoinitiator agent is as defined previously.

[0080] The crosslinked resin may further comprise a crosslinking agent other than the photoinitiator.

[0081] The crosslinking agent is preferably chosen from the group consisting of the triacrylate family.

[0082] Advantageously, the rate of crosslinking agent other than the photoinitiator is in the range of 0% to 15% by weight, preferably from 0% to 4% by weight relative to the weight of the crosslinked resin.

[0083] Another object of the invention is a single strand capable of being obtained by the process and / or processes according to the invention, as well as a single strand in filament-resin composite comprising filaments embedded in a cross-linked resin, the single strand being covered at least partially, preferably totally, with at least one organosilicon compound, said organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

[0084] The various embodiments described above in the context of the processes are applicable to single strands. Advantageously, the organosilicon compound(s) form a layer with a thickness ranging from 2 to 500 nm, preferably from 5 to 50 nm, on the surface of the filaments of the single strand.

[0085] The invention also relates to the use of at least one monostrand to reinforce concrete and / or reduce the weight of concrete and / or reduce or prevent cracking of concrete, and also to the use of at least one organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen to improve the resistance to alkalis of a support, the support preferably being a monostrand of filament-resin composite comprising filaments embedded in a cross-linked resin.

[0086] The various embodiments described above in the context of the processes are applicable for the use of at least one single strand and the use of at least one organosilicon compound.

[0087] Figure 1 attached schematically illustrates in a very simple way an example of a device 10 allowing the production of single strands in CVR.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 also contains (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.

[0092] Preferably, the length of the impregnation chamber is several meters, for example between 2 and 10 m, especially between 3 and 5 m.

[0093] 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.

[0094] 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.

[0095] Preferably, the length of the calibration area is several centimeters, for example between 5 and 50 cm, especially between 5 and 20 cm.

[0096] 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.

[0097] 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.

[0098] The polymerization or UV irradiation chamber then has the function of polymerizing and cross-linking the resin under the action of UV light.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] The diameter of the irradiation tube (preferably made of glass) is preferably between 10 and 80 mm, more preferably between 20 and 60 mm.

[0103] Preferably, the length of the irradiation chamber is several meters, for example between 2 and 15 m, especially between 3 and 10 m.

[0104] In this example, the irradiation tube 23 is traversed by a nitrogen current.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] Then, the CVR single strand is subjected to continuous plasma treatment, as described above, to apply at least one organosilicon compound to the surface of the straight arrangement of filaments, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

[0110] The continuous CVR strand 25 can then be cut to a predetermined length (not shown in Figure 1), for example 45 mm, by any means known to those skilled in the art, such as 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 breaking Cr) were measured using an "INSTRON" tensile testing machine of the 68TM50 type (BLUEHILL® UNIVERSAL software supplied with the tensile testing machine), according to the ASTM D2343 standard, at a temperature of 23 °C.

[0115] The measurements were carried out on CVR single strands manufactured with or without coating, with or without aging in an alkaline environment.

[0116] Before measurement, these single strands (aged or not) underwent preconditioning (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 ± 2°C; humidity of 50 ± 5%)). The aged CVR single strands were previously dried on absorbent paper.

[0117] The 260 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.

[0118] Aging protocol in alkaline solution

[0119] Glass tubes 300 mm long and 30 mm in diameter were filled with 160 mL of an alkaline solution at a pH of 13.5. Glass tubes containing 260 mm long CVR monostrands were kept at 60 °C for 3 days before being washed with water.

[0120] The strands were then left to dry at room temperature before tensile testing. Tensile tests were performed on at least 5 repetitions and compared to tensile tests carried out on strands that had not undergone the alkaline aging protocol. All results given are an average of 5 measurements.

[0121] Preparation of single strands in CVR

[0122] Single strands of CVR with or without coating were manufactured according to the process described above (single strands M1 to M8).

[0123] The resin composition used was based on vinyl ester resin (AOC's "ATLAC E-NOVA FW2045"), a triacrylate hardener (Sartomer's "SR 368"), and a photoinitiator (IGM's "Omnirad 819"). The glass fibers of the M1 to M8 strands were 300tex "SE 1200" fibers from Owens Corning. The glass filaments of the M1 strands did not contain any plasma-deposited compound.

[0124] For the plasma treatment step, 5 compounds were used: 1,1,3,3-tetramethyldisiloxane (for single-strand M3), trimethoxyvinylsilane (for single-strand M4), F-aminopropyltriethoxysilane (for single-strand M5), 1H,1H,2H,2H-perfluorooctyltriethoxysilane (for single-strand M6), dodecylacrylate (for single-strand M7), and poly(vinyl alcohol-co-ethylene) (for single-strand M8).

[0125] Each of these compounds was introduced into a device using an atmospheric pressure plasma jet (PLSMASPOT® maxi device).

[0126] The monostrand Ml corresponds to a CVR monostrand without coating and which has not been subjected to aging in an alkaline environment.

[0127] The M2 monostrand corresponds to a CVR monostrand without coating and which has been subjected to aging in an alkaline environment.

[0128] The M3 to M8 single strands correspond to CVR single strands with coating and which have been subjected to aging in an alkaline environment.

[0129] Results

[0130] The mechanical properties of the single strands M1 to M8 are presented in Tables 1, 2 and 3 below.

[0131] The results are expressed in MPa as well as in percentage loss of tensile strength. The lower the percentage, the less the tensile strength is degraded and the better the resistance to alkalis. [Table 1]

[0132] [Table 2] [Table 3]

[0133] It is first observed that the organosilicon compound, which does not include any atom other than silicon, carbon, hydrogen and oxygen, is found on the surface of the support, such as a single strand of filament-resin composite, after the implementation of the plasma treatment.

[0134] The results presented above show that the presence of an organosilicon compound comprising no atoms other than silicon, carbon, hydrogen and oxygen on the surface of a single strand, and deposited using a plasma treatment, improves the breaking strength of the support after aging in an alkaline environment, compared to an uncoated support after aging in an alkaline environment.

[0135] Indeed, the breaking strength values ​​of the M3 and M4 single strands according to the invention are higher than those of the comparative M2 single strand. The percentage loss of breaking strength is lower for the M3 and M4 single strands compared to the M1 single strand than for the comparative M2 single strand.

[0136] It should also be noted that the tensile strength of the comparative M5 to M8 single strands is identical to that of the comparative M2 single strand. Therefore, the compounds deposited on the surface of the single strand have no impact on the tensile strength.

[0137] Thus, the presence of said organosilicon compound comprising no atom other than silicon, carbon, hydrogen and oxygen on the surface of a support, such as a single strand of filament-resin composite, according to the invention makes it possible to improve the resistance to alkalis of said support.

Claims

DEMANDS 1. A method for improving the alkali resistance of a support comprising a plasma treatment step for applying at least one organosilicon compound to the surface of the support, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

2. A method according to claim 1, characterized in that the support is a monostrand of filament-resin composite comprising filaments embedded in a crosslinked resin.

3. A method for manufacturing at least one single strand of filament-resin composite comprising filaments embedded in a crosslinked resin, comprising the following steps: a) making a straight arrangement of filaments and driving this arrangement in a direction of advancement; b) bringing said arrangement of filaments into contact with a photocurable resin composition, in liquid form, called impregnation resin, to obtain an impregnated material containing the filaments and the resin composition; c) passing said impregnated material through a calibration die having a predefined surface area and shape cross-section, to impose upon it a single strand shape;d) downstream of the die, in a crosslinking chamber, polymerize 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; e) subject the single strand obtained in step (d) to a plasma treatment to apply at least one organosilicon compound to the surface of the straight arrangement of filaments, the organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

4. A method according to claim 3, characterized in that it further comprises f) a step of cutting the monostrand obtained in step (e), preferably to a length from 5 to 85 mm, to obtain cut monostrands.

5. A method according to any one of claims 2 to 4, characterized in that the filaments are chosen from the group consisting of glass, basalt, polyester filaments, and combinations thereof, preferably from the group consisting of glass filaments.

6. A method according to any one of the preceding claims, characterized in that the organosilicon compound is selected from the group consisting of compounds of formula R x Si-(OR')(4-x) (I), Ri,2,3Si-[O-SiR4,5,ô]n (II) and their mixtures, - formula (I) in which: * R represents a C1-C4 hydrocarbon group, preferably a C2-C3 alkenyl group; * R' represents a hydrocarbon group in C1-C4, preferably in C1-C2; * x is an integer ranging from 1 to 3; - formula (II) in which: * Ri, R2, R3, R4, Rs, RÔ, identical or different, represent H or a hydrocarbon group in C1-C4, preferably in C1-C2, provided that at least 4 of the groups among Ri, R2, R3, R4, Rs, RÔ represent a hydrocarbon group in C1-C4, preferably at least 2 of the groups among Ri, R2, R3, R4, Rs, RÔ designate H; * n is an integer from 1 to 3, preferably n is equal to 1.

7. A process according to any one of the preceding claims, characterized in that the organosilicon compound is selected from the group consisting of 1,1,3,3-tetramethyldisiloxane, trimethoxyvinylsilane and mixtures thereof.

8. A method according to any one of claims 2 to 7, characterized in that the crosslinked resin is based on at least: - a photocurable resin 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; - a crosslinking system comprising a photoinitiator agent.

9. A method according to any one of claims 2 to 8, characterized in that the single strand 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.

10. A method according to claim 9, when it depends at least on claim 4, characterized in that the cut single strand has a length / diameter ratio from 10 to 110, preferably from 20 to 90, more preferably from 25 to less than 80.

11. Monostrand capable of being obtained by a process according to any one of claims 2 to 10.

12. Monostrand of filament-resin composite comprising filaments embedded in a cross-linked resin, the monostrand being coated at least partially, preferably totally, with at least one organosilicon compound, said organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen.

13. Monostrand according to claim 12, characterized in that the organosilicon compound(s) form a layer with a thickness ranging from 2 to 500 nm, preferably from 5 to 50 nm, on the surface of the filaments of the monostrand.

14. Use of at least one monostrand according to any one of claims 11 to 13, where they depend at least on claim 4, to reinforce concrete and / or reduce the weight of concrete and / or reduce or prevent cracking of concrete.

15. Use of at least one organosilicon compound not comprising any atom other than silicon, carbon, hydrogen and oxygen to improve the resistance to alkalis of a support, the support preferably being a single strand of filament-resin composite comprising filaments embedded in a cross-linked resin.

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