Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
  • C04B20/0048—Fibrous materials
  • C04B20/0068—Composite fibres, e.g. fibres with a core and sheath of different material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B15/00—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00
  • B29B15/08—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00 of reinforcements or fillers
  • B29B15/10—Coating or impregnating independently of the moulding or shaping step
  • B29B15/12—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length
  • B29B15/122—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length with a matrix in liquid form, e.g. as melt, solution or latex
  • B29B15/125—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length with a matrix in liquid form, e.g. as melt, solution or latex by dipping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
  • B29C35/10—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation for articles of indefinite length
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
  • C04B20/10—Coating or impregnating
  • C04B20/1018—Coating or impregnating with organic materials
  • C04B20/1029—Macromolecular compounds
  • C04B20/1037—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/04—Portland cements
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs
  • C08J5/241—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres
  • C08J5/243—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres using carbon fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
  • B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
  • B29C2035/0827—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using UV radiation
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
  • C04B2103/0045—Polymers chosen for their physico-chemical characteristics
  • C04B2103/0062—Cross-linked polymers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/34—Non-shrinking or non-cracking materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins

Definitions

• the present invention relates to carbon-resin composite fibers for reinforcing concrete as well as to their method of obtaining them.
• Concrete is probably the most widely used construction material today due to its high compressive strength, durability, longevity and resilience. Its properties make it a material of choice, particularly in the fields of building, roads and engineering structures.
• Concrete is mainly composed of aggregates held together by a binder, most often Portland cement.
• a binder most often Portland cement.
• additives such as ultrafine particles (silica fume for example), superplasticizers also called water reducers or metallic, synthetic or mineral fibers.
• metal fibers have the disadvantage of being sensitive to corrosion, which can be detrimental to the longevity of concrete comprising such fibers. Furthermore, they often have densities greater than 7.7 and are therefore not distributed homogeneously in concrete with a lower density (metal fibers tend to flow under the effect of gravity, or even under the effect of vibrations when the concrete is vibrated to evacuate any air bubbles that may have been entrained during pouring). To solve this problem it was proposed to replace the metal fibers with synthetic fibers. However, the mechanical strength (Elastic Modulus (Young), tensile strength for example) of these fibers is not as good as that of metal fibers. Furthermore, their operating temperature (generally between 100°C and 160°C) is much lower than that of metal fibers (between approximately 600°C and 900°C), which can limit their use for certain applications.
• the Applicant has also noted numerous advantages provided by the fibers according to the invention.
• Their implementation is very easy compared to the concrete fibers of the prior art, in particular during the phase of mixing the different components of the concrete (easily dispersible), but also during the drying phase of the concrete: due to their density close to that of concrete, the fibers remain homogeneously distributed in the concrete (they do not tend to sink like metal fibers which are denser than concrete, nor to rise like synthetic fibers which are less dense than concrete) .
• the fibers of the invention also have a much higher maximum use temperature than the synthetic fibers currently used. Also, more generally, due to their density and their reinforcing capacity, the use of the fibers according to the invention makes it possible to significantly reduce overall CO2 emissions compared to the use of other fibers of the prior art, at constant level of reinforcement.
• the subject of the invention is a single strand of carbon-resin composite comprising carbon filaments embedded in a crosslinked resin, having a length comprised in a range ranging from 5 to 85 mm and a diameter ranging from 0.2 to 1.3 mm, and characterized in that the single strand has a porosity rate of less than 2%.
• the invention also relates to a process for manufacturing a single strand of carbon-resin composite comprising carbon filaments embedded in a crosslinked resin, comprising the following successive steps:
• the irradiation chamber comprising a tube transparent to UV, called irradiation tube, through which the single strand being formed, traversed by a current of inert gas, the speed (noted Vi r ) of passage of the single strand in the irradiation chamber being greater than 50 m/min, the irradiation duration (noted Di r ) of the single strand in the irradiation chamber being equal to or greater than 1.5 s,
• composition based on is meant 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 less partially, during the different phases of manufacturing the composition; the composition can thus be in the totally or partially crosslinked state or in the non-crosslinked state.
• any interval of values designated by the expression "between a and b" represents the range of values going from more than a to less than b (that is to say limits a and b excluded) while any interval of values designated by the expression “from a to b” means the range of values going from a to b (that is to say including the strict limits a and b).
• any interval of values designated by the expression “from a to b” means the range of values going from a to b (that is to say including the strict limits a and b).
• Tg glass transition temperature
• Figure 1 represents a diagram of the process for synthesizing the single strand according to the invention before the latter is cut to a determined length.
• FIG. 2 Figure 2, not shown to scale to facilitate understanding, is a drawing representing a cross section of the single strand according to the invention.
• the invention therefore relates to a single strand (or fiber, the two terms can be used equivalently) made of carbon-resin composite (abbreviated "CCR") comprising carbon filaments embedded in a crosslinked resin (i.e. say a resin hardened after crosslinking), having a length included in a range ranging from 5 to 85 mm and a diameter ranging from 0.2 to 1.3 mm, and characterized in that the single strand has a porosity rate of less than 2%.
• CCR carbon-resin composite
• carbon fibers which can be used in the context of the present invention
• Those skilled in the art know 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 carbon-resin composite, in particular using a silane type compatibilisation agent.
• carbon filaments are present in the form of a single multifilament fiber or several multifilament fibers associated with each other.
• the multifilament fibers are preferably essentially unidirectional.
• Each of the multifilament fibers can comprise several tens, hundreds or even thousands of single carbon filaments.
• These very fine unit filaments generally and preferably have an average diameter of 3 to 12 ⁇ m, more preferably 5 to 9 ⁇ m.
• the section of the unit filaments is preferably cylindrical.
• the filaments of the single-strand are essentially parallel to each other.
• the alignment rate of the carbon filaments is preferably such that more than 85% (% by number) of the filaments have an inclination with respect to the axis of the single strand which is less than 2.0 degrees, more preferably less than 1.5 degrees, with this tilt (or misalignment) measured as described in the above publication by Thompson et al.
• the CCR single strand according to the invention is not helically deformed, that is to say it is not twisted.
• the CCR single strand has a number of turns per meter of less than 5, preferably less than 2, preferably less than 0.5, preferably 0 to 0.5.
• the weight content of carbon fibers (that is to say filaments) in the CCR single strand is included in a range ranging from 50% to 70%, preferably from 55% to 65%.
• the weight content of the carbon fiber is calculated by taking the ratio of the title of the initial carbon fiber to the title of the final CCR single strand.
• the titer (or linear density) is determined on at least three samples, each corresponding to a length of 50 m, by weighing this length; the title is given in tex (weight in grams of 1000 m of product - as a reminder, 0.111 tex is equivalent to 1 denier).
• volume fraction of carbon fiber in the CCR single strand is advantageously included in a range ranging from 40% to 60%, preferably from 45% to 55%.
• the volume fraction of carbon fiber in the final CCR single strand corresponds to the surface fraction of carbon fiber in a cross section of the CCR single strand in relation to the total surface area of its section.
• the surface fraction of carbon fiber can be determined in the same way as described below for measuring the porosity rate.
• the crosslinked resin represents from 30% to 50%, preferably from 35% to 45%, by weight, of the CCR single strand of the invention.
• the volume fraction of resin in the CCR single strand is advantageously included in a range ranging from 40% to 60%, preferably from 45% to 55%.
• the weight percentage and volume fraction of crosslinked resin can be obtained using a method similar to the method for obtaining the weight percentage and volume fraction of carbon fiber described above.
• the resin used is by definition a crosslinkable resin (ze, curable) capable of being crosslinked, hardened by any known method, in particular and preferably by UV (or UV-visible) radiation, preferably emitting in a spectrum ranging at least from 300nm to 450nm.
• resin or “resin composition”, we mean here the resin as such or any composition based on this resin and comprising at least one additive (that is to say one or more additives) before crosslinking.
• crosslinked resin we understand of course that the resin is hardened (photocured and/or thermoset), 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 to so-called thermoplastic polymers).
• the crosslinked resin is based on at least:
• crosslinkable resin chosen from the group consisting of vinyl ester resins (preferably vinyl ester urethane resins), epoxy, polyester and their mixtures,
• crosslinking system preferably comprising a photoinitiator agent reactive to UV rays greater than 300 nm.
• a polyester or vinyl ester resin is preferably used, more preferably a vinyl ester resin.
• polymers polyethylene glycol dimethacrylate resin
• vinyl ester resins are well known in the field of composite materials.
• the vinyl ester resin is preferably of the epoxy vinyl ester type.
• a vinyl ester resin in particular of the epoxy type, which at least in part is based (that is to say 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.
• the initial extension modulus of the resin measured at 23°C, is greater than 3.0 GPa, more preferably greater than 3.5 GPa.
• An epoxyvinylester resin based on novolac (part in square brackets in formula I below) corresponds for example, in a known manner, to formula (I) which follows:
• An epoxyvinylester resin based on bisphenolic A (part in brackets of formula (II) below) corresponds for example to the formula (the "A" reminding that the product is manufactured
• An epoxyvinylester resin of the novolac and bisphenolic type has shown excellent results.
• Epoxyvinylester resins are available from other manufacturers such as for example AOC (USA - “VIPEL” resins).
• the impregnation resin (resin composition) crosslinking system comprises a photoinitiator sensitive (reactive) to UV beyond 300 nm, preferably between 300 and 450 nm. This photo-initiator is used at a preferential rate of 0.5 to 3%, more preferably 1 to 2.5%.
• the resin crosslinking system also comprises a crosslinking agent, for example at a level of between 5% and 15% (% by weight of impregnating composition), the crosslinking agent being as defined below. -above.
• this photo-initiator is from the family of phosphine compounds, more preferably a bis(acyl)phosphine oxide such as for example bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (“Omnirad 819” from the company IGM or “speedcureBPO” from the company Lambson) or a mono(acyl)phosphine oxide (for example “Esacure TPO” from the company IGM), such phosphine compounds being able to be used in mixture with other photo- initiators, for example photo-initiators of the alpha-hydroxy-ketone type such as for example dimethylhydroxy-acetophenone (eg “Omnirad 1173” from IGM) or 1-hydroxy-cyclohexyl-phenyl-ketone (eg “Omnirad 184” from IGM), benzophenones such as 2,4,6-trimethylbenzophenone (eg “Esacure TZT”
• the crosslinking agent is preferably chosen from the group consisting of the triacrylate family.
• the diameter D of the CCR single strand of the invention is preferably included in a range ranging from 0.2 to 1.3 mm, preferably from 0.25 to 1.25 mm, more preferably between 0.3 and 1, 2 mm, especially between 0.4 and 1.1 mm.
• D is by convention the so-called bulk diameter, that is to say the diameter of the cylinder of imaginary revolution enveloping the single strand, in other words the diameter of the circumscribed circle surrounding its right section.
• the length L of the CCR single strand of the invention is preferably included in a range ranging from 10 to 80 mm, for example from 15 to 60 mm.
• the length/diameter ratio L/D of the CCR single strands of the invention is advantageously included in a range ranging from 10 to 110, preferably from 20 to 90, preferably from 25 to 80, preferably from 30 at 70.
• the CCR single strand advantageously has a porosity rate of less than 1%, preferably less than 0.5%.
• the porosity rate of the CCR single strand is between 0% and 2%, preferably between 0.01% and 1%, preferably between 0.05% and 0.5%.
• the porosity rate can be measured by microscopy, for example by scanning electron microscopy, preferably using surface calculation software, such as FIJI program. To carry out the measurement, the following protocol is preferably carried out:
• a cold coating resin of the epoxy type for example, for example in a vacuum coating device (CitoVac from the company Stuers for example),
• the coated CCR single strand is cut, for example using a hydraulic guillotine, such as the “SH-5214” from the Baileigh company,
• the section of the CCR single strand is polished, for example using a mechanical polisher, from the company Mecapol for example, preferably to a final grain of 0.25 pm,
• a deposit of 1 to 4 nm of gold is carried out, for example using a gold metalizer, such as Cerssington from the 108 or 208 series from the company Elo ⁇ se,
• porosity of the CCR single strand means any gas (notably air) or vacuum present within the CCR single strand.
• the CCR single strand advantageously has a breaking stress Cr greater than 2300 MPa, more preferably greater than or equal to 2500 MPa.
• the single strand preferably has a breaking stress of between 2300 and 4500 MPa, preferably from 2500 to 4000 MPa.
• the CCR single strand has an initial extension modulus (denoted E23), also called Young's Modulus, measured at 23°C, greater than 140 GPa, preferably greater than 150 GPa, preferably greater than or equal to 160 GPa .
• E23 initial extension modulus
• the single strand preferably has an E23 of between 140 and 350 GPa, preferably between 145 and 300 GPa, preferably from 150 to 270 GPa.
• the glass transition temperature denoted Tg of the crosslinked resin is preferably greater than 190°C, preferably greater than 195°C, in particular greater than 200°C. It is measured in a known manner by DSC (Differential Scanning Calorimetry), on the second pass, for example and unless otherwise specified in the present application, according to standard ASTM D3418 of 1999 (DSC "822-2" device from Mettler Toledo; atmosphere nitrogen; samples previously heated from room temperature (23°C) to 250°C (10°C/min), then cooled quickly to 23°C, before final recording of the DSC curve from 23°C to 250 °C, at a ramp of 10°C/min).
• the density (or density in g/cm 3 ) of the CCR single strand is between 1.42 and 1.58. It is measured (at 23°C) using a specialized balance from the company Mettler Toledo of the “PG503 DeltaRange” type; the samples, a few cm in size, are successively weighed in air and immersed in ethanol; the device's software then determines the average density over three measurements.
• the invention also relates to a process for manufacturing single strands or fibers, the two terms which can be used equivalently) in carbon-resin composite (abbreviated “CCR”) comprising the following successive steps:
• the irradiation chamber comprising a tube transparent to UV, called irradiation tube, through which the single strand being formed, traversed by a current of inert gas, the speed (noted Vi r ) of passage of the single strand in the irradiation chamber being greater than 50 m/min, the irradiation duration (noted Di r ) of the single strand in the irradiation chamber being equal to or greater than 1.5 s, step at the end of which a CCR single strand is obtained comprising carbon filaments embedded in a crosslinked resin,
• 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 those skilled in the art, as are the materials (multifilament fibers and resin compositions) used; they have for example been described in one and/or the other of applications EP-A-1 074 369 and EP-A-1 174 250.
• the so-called “calibration” die allows, thanks to a straight section of determined dimensions, generally and preferably circular or rectangular, to adjust the proportion of resin in relation to the carbon fibers while imposing the shape and size of the impregnated material. thickness targeted for the single strand.
• the single strand at the outlet of the calibration die has a diameter ranging from 0.2 to 1.3 mm, preferably from 0.25 to 1.25 mm, preferably from 0.3 to 1.2 mm.
• the polymerization or UV irradiation chamber then has the function of polymerizing and crosslinking the resin under the action of UV.
• the UV irradiation chamber includes one or more UV irradiators (or radiators).
• the irradiation chamber comprises a plurality of UVs, that is to say at least two (two or more than two) which are arranged in a line around the irradiation tube.
• Each UV irradiator typically comprises one (at least one) UV lamp (preferably emitting in a spectrum of 200 to 600 nm) and a parabolic reflector at the focus of which is the center of the irradiation tube; it delivers a linear power preferably between 2,000 and 14,000 watts per meter.
• the irradiation chamber comprises at least three, in particular at least four UV irradiators in line.
• the linear power delivered by each UV irradiator is between 2,500 and 12,000 watts per meter, in particular included in a range of 3,000 to 10,000 watts per meter.
• UV radiators suitable for the process of the invention are well known to those skilled in the art, for example those marketed by the company Dr. Hônle AG (Germany) under the reference “1055 LCP AM UK”, equipped with “UVAPRINT” lamps. (high pressure mercury lamps doped with iron).
• the rated (maximum) power of each radiator in this type is equal to approximately 13,000 Watts, the power actually delivered can be adjusted with a potentiometer between 30 and 100% of the nominal power.
• the diameter of the irradiation tube (preferably glass) is preferably between 10 and 80 mm, more preferably between 20 and 60 mm.
• the tensions experienced by the carbon fibers at a moderate level, preferably between 0.2 and 2.0 cN/tex, more preferably between 0.3 and 1.5cN/tex; to control this, we could for example measure these tensions directly at the outlet of the irradiation chamber, using appropriate tensiometers well known to those skilled in the art.
• the final CCR single strand thus formed through the UV irradiation chamber, in which the resin is now in the solid state, is then harvested for example on a receiving reel on which it can be wound over a very long length.
• the process can thus include a winding step for storing the single strand after its passage through the UV irradiation chamber.
• the single strand can be cut so as to obtain single strands with a length comprised in a range ranging from 5 to 85 mm, preferably from 10 to 80 mm, preferably from 15 to 60 mm.
• the single strands advantageously have a length/diameter ratio ranging from 10 to 110, preferably from 20 to 90, preferably from 25 to 80, preferably from 30 to 70.
• the process for manufacturing the CCR single strand of the invention comprises the following essential steps:
• the duration (Di r ) 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;
• the irradiation chamber comprises a UV-transparent tube (such as a quartz tube or preferably glass), called an irradiation tube, through which the single strand circulates in during training, this tube being traversed by a current of inert gas, preferably nitrogen.
• a current of inert gas preferably nitrogen.
• the irradiation duration Di r of the single strand in the irradiation chamber is too short (less than 1.5 s)
• numerous tests have revealed that the resin is not crosslinked enough, which causes degradation. mechanical properties, including breaking stress and bending resistance.
• the irradiation duration Di r of the single strand in the irradiation chamber is too long (greater than 10 s for example), this increases the risk of the resin boiling and therefore creating more porosity and to degrade the mechanical properties, including the breaking stress.
• a high Vir irradiation speed (greater than 50 m/min, preferably between 50 and 150 m/min) was favorable on the one hand to an excellent rate of alignment of the filaments of carbon inside the CCR single strand, on the other hand better maintenance of the vacuum in the vacuum chamber with a significantly reduced risk of seeing raise a certain fraction of impregnation resin from the impregnation chamber to the vacuum chamber, and therefore to a better quality of impregnation.
• the speed Vir is between 50 and 150 m/min, more preferably in a range of 60 to 120 m/min.
• the irradiation duration Di r is between 1.5 and 10 s, more preferably in a range of 2 to 5 s.
• An object described herein is a CCR single strand capable of being obtained by a process according to the invention preferably according to which:
• the speed (Vir) of passage of the single strand in the irradiation chamber is greater than 50 m/min;
• the duration (Di r ) 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;
• the irradiation chamber comprises a UV-transparent tube (such as a quartz tube or preferably glass), called an irradiation tube, through which the single strand being formed circulates, this tube being traversed by a stream of inert gas, preferably nitrogen,
• the CCR single strand having a length ranging from 5 to 85 mm, preferably from 10 to 80 mm, preferably from 15 to 60 mm,
• the CCR single strand having a diameter ranging from 0.2 to 1.3 mm, preferably from 0.25 to 1.25 mm, preferably from 0.3 to 1.2 mm.
• the CCR single strand capable of being obtained by a process according to the invention therefore comprises carbon filaments impregnated in a crosslinked resin, has a length ranging from 5 to 85 mm, a diameter ranging from 0.2 to 1.3 mm , and a porosity rate of less than 2%. All the characteristics described above for the single strand according to the invention also apply to the single strand capable of being obtained by the process according to the invention.
• the single strand advantageously has a porosity rate of less than 1%, preferably less than 0.5% and/or a breaking stress greater than 2300 MPa, of preferably greater than or equal to 2500 MPa and/or an initial extension modulus denoted E23 of the single strand, measured at 23°C, is greater than 140 GPa, preferably greater than 150 GPa.
• the invention also relates to a ballot box comprising a plurality of CCR single strands according to the invention (or capable of being obtained by the process according to the invention) and at least one element for holding the single strands cut between them.
• this holding element is a breakable film, for example tearable, dispersible, water-soluble.
• the at least one holding element is a water-soluble thread.
• the holding element is a water-soluble film, preferably made of a material chosen from the group consisting of polyvinyl alcohols (PVA) or any water-soluble or bioplastic polymer, such as bioplastics derived from milk casein.
• PVA polyvinyl alcohols
• bioplastics derived from milk casein a material chosen from the group consisting of polyvinyl alcohols.
• the at least one water-soluble film is made of a material chosen from the group consisting of polyvinyl alcohols.
• the ballotin according to the invention advantageously comprises a number of cut single strands included in a range ranging from 300 to 20,000.
• the single strands making up the ballotin can be of identical or different dimensions.
• a ballotin may include single strands of different length, diameter and/or length to diameter ratio.
• the ballotin comprises single strands according to the invention having lengths and diameters presenting no more than 10%, preferably no more than 3%, difference from each other.
• the single strands according to the invention are particularly useful as an additive for concrete.
• the invention also relates to the use of at least one CCR single strand according to the invention (or capable of being obtained by the process according to the invention) or of a ballotin according to the invention, for reinforce concrete and/or reduce the weight of the concrete and/or reduce or prevent cracking of the concrete.
• the present invention also relates to a concrete comprising a plurality of single strands cut from CCR according to the invention (or capable of being obtained by the process according to the invention).
• the concrete can be prepared using any technique well known to those skilled in the art.
• the volume ratio of the single strands according to the invention in the concrete according to the invention is included in a range ranging from 0.1% to 6%, for example from 0.1% to 1.5% for concretes called " "conventional", for example of type BPS C40/50
• Figure 1 attached very simply schematizes an example of a device 10 allowing the production of CCR single strands conforming to the invention.
• This arrangement 12 then passes through a vacuum chamber 13 (connected to a vacuum pump not shown), arranged between an inlet pipe 13a and an outlet pipe 13b opening onto an impregnation chamber 14, the two pipes preferably at rigid wall having for example a minimum section greater (typically twice as much) than the total section of fibers and a length much greater (typically 50 times more) than said minimum section.
• the arrangement 12 of fibers 11b passes through an impregnation chamber 14 comprising a supply tank 15 (connected to a dosing pump not shown) and a tank of waterproof impregnation 16 completely filled with impregnation composition 17 based on a curable vinyl ester type resin (e.g., “ALTAC® E-Nova FW 2045” from AOC).
• a curable vinyl ester type resin e.g., “ALTAC® E-Nova FW 2045” from AOC.
• composition 17 further comprises (at a weight level of 1 to 2%) a photoinitiator agent suitable for UV and/or UV-visible radiation with which the composition will subsequently be treated, for example bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (“Omnirad 819” from the company IGM). It may also contain (for example approximately 5% to 15%) a crosslinking agent such as for example tris(2-hydroxyethyl)isocyanurate triacrylate (“SR 368” from the company Sartomer). Of course, the impregnation composition 17 is in the liquid state.
• a photoinitiator agent suitable for UV and/or UV-visible radiation with which the composition will subsequently be treated for example bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (“Omnirad 819” from the company IGM). It may also contain (for example approximately 5% to 15%) a crosslinking agent such as for example tris(2-hydroxyethyl
• the length of the impregnation chamber is several meters, for example between 2 and 10 m, in particular between 3 and 5 m.
• an impregnated material which comprises for example (% by weight) from 65% to 75% solid fibers 11b, the remainder ( 25 to 35%) being constituted by the liquid impregnation matrix 17.
• the impregnation then passes through calibration means 19 comprising at least one calibration die 20 whose channel (not shown here), for example of circular, rectangular or even conical shape, is adapted to the particular production conditions.
• this channel has a minimum cross section of circular shape whose downstream orifice has a diameter slightly greater than that of the single strand in question.
• Said die has a length which is typically at least 100 times greater than the minimum dimension of the minimum section.
• the die 20 can be directly integrated into the impregnation chamber 14, which avoids for example the use of the outlet pipe 18.
• the length of the calibration zone is several centimeters, for example between 5 and 50 cm, in particular between 5 and 20 cm.
• a "liquid” composite single strand 21 (liquid in the sense that its impregnation resin is always liquid) is obtained at this stage, the shape of the cross section of which is preferably essentially circular.
• the liquid composite single strand 21 thus obtained is then polymerized by passing through a UV irradiation chamber (22) comprising a sealed glass tube (23) through which the single strand circulates. composite; 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 company Dr .Hônle, of wavelength 200 to 600 nm) arranged at a short distance (a few cm) from the glass tube.
• UVAprint lamps from the company Dr .Hônle, of wavelength 200 to 600 nm
• the length of the irradiation chamber is several meters, for example between 2 and 15 m, in particular between 3 and 10 m.
• a nitrogen current flows through the irradiation tube (23).
• the irradiation conditions are preferably adjusted in such a way that, in the irradiation chamber, the temperature of the CCR single strand measured on the surface of the latter (for example using a thermocouple), is greater than the Tg of the crosslinked resin (in other words greater than 190°C), and more preferably less than 270°C.
• the CCR single strand (25) Once the resin has been polymerized (hardened), the CCR single strand (25), this time in the solid state, driven in the direction of arrow F, then arrives on its final receiving spool (26).
• the process of the invention can be implemented at high speed, greater than 50 m/min, preferably between 50 and 150 m/min, more preferably in a range of 60 to 120 m/min.
• the continuous CCR single strand (25) can be cut to a determined length (not shown in Figure 1), for example 45 mm by any means known to those skilled in the art, for example using a hydraulic guillotine , such as the “SH-5214” from the Baileigh company.
• This step can be carried out directly at the outlet of the irradiation chamber (23). It can also be carried out after the single strand has been conditioned on a final receiving reel (26).
• the porosity rate was measured according to the protocol:
• %porosity porosity area / (porosity area + area of the fibers + area of the crosslinked resin ).
• heel gluing (Material: 50 mm long cardboard; Adhesive used: Loctite EA 9483 (epoxy bi- components)) was carried out as follows. The surfaces of the two opposite heels have been glued as well as the reinforcement in order to limit the “dry zones” as much as possible (without adhesive). The heels were held in place for the curing time (12 hours at 23°C) in a template with the dimensions of the test specimens, with weights on the heels to ensure good heel/reinforcement contact. The traction module was determined by linear regression of the stress versus strain curve, between 0.1% and 0.6% strain.
• Single strands (Ml to M3) in CCR were manufactured according to the process described previously with a speed Vi r of passage of the single strand in the irradiation chamber of 100 m/min, an irradiation duration Di r of the single strand in the chamber irradiation time of 2.4 s, the length of the irradiation chamber being 4 m.
• the resin composition used was based on vinyl ester resin (“ATLAC E-NOVA FW2045” from the company), a triacrylate hardener (“SR 368” from the company Sartomer) and a photoinitiator (“Omnirad 819” from the company the IGM company).
• the carbon filaments of the Ml, M2 and M3 single strands were respectively “HTA40” filaments from the Teijin company.
• the diameter and tex of the single strands as well as their physical characteristics and mechanical properties are presented in table 1 below.
• the single strands of the invention make it possible to improve the cracking resistance of concrete. It has thus been noted that the single strands conforming to the invention present an improved performance compromise between in particular the mechanical strength, the corrosion resistance, the processability (in particular the dispersibility during mixing, the implementation temperature and the maintenance homogeneity during concrete drying).

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