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
  • 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
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
• • 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
  • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B14/38—Fibrous materials; Whiskers
  • C04B14/386—Carbon
• • 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
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/02—Agglomerated materials, e.g. artificial aggregates
  • C04B18/021—Agglomerated materials, e.g. artificial aggregates agglomerated by a mineral binder, e.g. cement
• • 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
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/02—Agglomerated materials, e.g. artificial aggregates
  • C04B18/022—Agglomerated materials, e.g. artificial aggregates agglomerated by an organic binder
• • 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
  • C04B20/02—Treatment
  • C04B20/04—Heat treatment
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
  • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
  • E04C5/07—Reinforcing elements of material other than metal, e.g. of glass, of plastics, or not exclusively made of metal
  • E04C5/073—Discrete reinforcing elements, e.g. fibres
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
  • B29B2017/042—Mixing disintegrated particles or powders with other materials, e.g. with virgin materials
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
  • B29B2017/0424—Specific disintegrating techniques; devices therefor
  • B29B2017/0496—Pyrolysing the materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
  • B29K2105/12—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of short lengths, e.g. chopped filaments, staple fibres or bristles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2307/00—Use of elements other than metals as reinforcement
  • B29K2307/04—Carbon

Definitions

• the present disclosure relates to concrete or mortar compositions containing spindle-shaped carbon fiber aggregates, reinforced concrete or mortar structures, and methods of manufacturing the same.
• the present invention relates to concrete or mortar compositions containing spindle-shaped carbon fiber aggregates made from recycled carbon fibers, reinforced concrete or mortar structures, and methods for producing the same.
• Concrete or mortar structures whose main component is cement are used in large quantities in the fields of architecture and civil engineering because of their excellent properties such as compressive strength, durability, and nonflammability, as well as their low cost.
• these structures are made of aggregate such as sand or gravel, they basically have brittle physical properties and easily crack when stress such as tension, bending, or bending is applied. , it has disadvantages such as breakage.
• fiber-reinforced plastic wire using steel fiber, synthetic fiber, aramid fiber, glass fiber, etc.
• the mechanical properties such as flexural strength and flexural toughness of cement composite materials (reinforced concrete or mortar structures) are greatly improved.
• Carbon fiber has excellent specific strength and specific modulus, and is lightweight, so it is used as reinforcing fiber for various materials. Furthermore, as reinforcing fibers used in cement composite materials, they are also used in the fields of architecture and civil engineering because they undergo relatively little deterioration in alkali. In particular, many methods have been studied for using composite wire rods manufactured from carbon fiber reinforced plastic (CFRP) using carbon fibers, which are continuous fibers, in cement composite materials.
• CFRP carbon fiber reinforced plastic
• Patent Documents 1 to 3 describe cement composite materials in which a resin matrix or, as an alternative, an inorganic matrix is adhered to carbon fibers that are continuous fibers, and a composite wire material is then cured and cut. are doing.
• these methods cannot be applied to pre-cut short fibers, process end material fibers, recycled carbon fibers recovered from CFRP, etc., because they are cut after the continuous fibers have been hardened. .
• the production energy or cost of the curing process may become a problem.
• pre-cut carbon fibers are used as reinforcing materials as they are, they are not hardened and are easily dispersed into single fibers when mixed with a concrete composition or the like.
• dispersed into single fibers there are problems that the dispersed single fibers may break due to contact with the aggregate, and that the viscosity of the material increases during kneading, resulting in a decrease in handleability. Further, there was a problem that the reinforcing effect such as bending toughness was reduced.
• Patent Document 4 describes a cement composite material reinforced with carbon fibers having an average fiber length of 3 mm or less. Since the average fiber length is short, the probability of breakage of the dispersed single fibers is low, but it is expected that the reinforcing effects such as bending strength and bending toughness of the resulting cement composite material will be small. Furthermore, due to the increase in material viscosity, the characteristic values of the mortar composition before curing are reduced, such as slump and fluidity.
• the present disclosure provides carbon fiber-containing concrete that is easy to handle by using a reinforcing material made from pre-cut carbon fibers such as short fibers, process end fibers, and recycled carbon fibers recovered from CFRP.
• Another object of the present invention is to provide a mortar composition, and to provide a cured product of the carbon fiber reinforced concrete or mortar structure having a high fiber reinforcing effect.
• the present disclosure also aims to provide a method for manufacturing carbon fiber reinforced concrete or mortar structures.
• a carbon fiber-containing concrete or mortar composition comprising a carbon fiber aggregate composed of at least carbon fibers and a binder, the carbon fiber aggregate has a spindle shape;
• a carbon fiber-containing concrete or mortar composition characterized by:
• ⁇ Aspect 8> The carbon fiber-containing concrete or mortar composition according to any one of aspects 1 to 7, wherein the carbon fibers are recycled carbon fibers.
• ⁇ Aspect 9> The carbon fiber-containing concrete according to aspect 7 or 8, wherein the recycled carbon fiber contains a residual carbon component, and the residual carbon component is more than 0% by weight and 5.0% by weight or less based on the recycled carbon fiber.
• ⁇ Aspect 10> A carbon fiber reinforced concrete or mortar structure in which the composition according to any one of aspects 1 to 9 is cured.
• the reinforcing material is made from pre-cut carbon fibers such as short fibers, process end fibers, and recycled carbon fibers recovered from CFRP, etc., which makes the carbon fibers excellent in handling. It is possible to provide a concrete or mortar composition containing carbon fibers, a cured product thereof, a carbon fiber reinforced concrete or mortar structure with a high fiber reinforcing effect, and a method for producing the same.
• FIG. 1 is a schematic diagram of one embodiment of an agitated granulator that can be used with the present disclosure.
• FIG. 2 is a photograph of a plurality of carbon fiber aggregates according to Example 1.
• FIG. 3 is a photograph of one carbon fiber aggregate according to Example 1.
• FIG. 4 is a photograph of a plurality of carbon fiber aggregates according to Example 2.
• the concrete or mortar composition according to the present disclosure includes: At least including a carbon fiber aggregate composed of at least carbon fibers and a binder, It is characterized by containing spindle-shaped carbon fiber aggregates.
• the concrete or mortar composition according to the present disclosure contains spindle-shaped carbon fiber aggregates.
• spindle-shaped carbon fiber aggregates are manufactured by rolling granulation method, stirring granulation method, etc.
• carbon fibers are subject to stress in a certain direction such as centrifugal force. Therefore, it is considered that the single fibers are tightly fixed by the binder in a bundled state while arranging along a certain direction. Therefore, it is thought that it is difficult to unbundle when mixed with a concrete composition or the like, and it is possible to suppress dispersion into single fibers.
• the concrete or mortar structure according to the present disclosure is preferably reinforced with spindle-shaped carbon fiber aggregates having an average length of 1.5 mm to 60 mm.
• a feature of the spindle-shaped carbon fiber aggregate is that even if the length of the pre-cut carbon fibers used as raw materials is less than 1.5 mm, the average length of the carbon fiber aggregate can be extended. Therefore, it is possible to increase the anchoring force with the concrete structure, etc. as a reinforcing material, making it difficult for the reinforcing material to pull out from the base material, such as the concrete structure, due to tensile stress, resulting in good reinforcement efficiency. be able to.
• a spindle-shaped carbon fiber aggregate has excellent properties as a reinforcing material for concrete structures made of pre-cut carbon fiber as a raw material, and thereby has a fiber reinforcing effect.
• a carbon fiber assembly according to the present disclosure is an assembly composed of at least carbon fibers and a binder.
• the single fibers are bonded to each other by a binder.
• the amount of binder in the carbon fiber aggregate is preferably 0.1% to 10% by weight, particularly 0.5% to 8% by weight, or 1% by weight, relative to the carbon fiber aggregate. It may be up to 6% by weight. If the amount of binder is less than 0.1% by weight, the binder will be unbound and easily dispersed into single fibers when mixed with a concrete composition, etc., resulting in breakage of single fibers and an increase in material viscosity during kneading. This is not preferable because the handling properties may deteriorate.
• the amount of binder exceeds 10% by weight, the weight ratio of carbon fibers constituting the carbon fiber aggregate becomes small, so when comparing the same additive amount of the aggregate, there is a tendency that good reinforcement efficiency cannot be obtained. be.
• the carbon fiber aggregate according to the present disclosure has a spindle shape.
• the spindle shape means a shape that is thick at the center and gradually becomes thinner toward both ends.
• a method for obtaining a spindle-shaped carbon fiber aggregate using an agitation granulation method will be described later.
• a similar method for a method for obtaining a spindle-shaped carbon fiber aggregate using a rolling granulation method, reference may be made to, for example, the description in Japanese Patent No. 3452363.
• the average length of the carbon fiber aggregate may be 1.5 mm to 60 mm.
• the average length of the aggregate is 5 mm or more, 10 mm or more, 15 mm or more, 20 mm or more, or 25 mm or more, and/or preferably 55 mm or less, 50 mm or less, 45 mm or less, or 40 mm or less. If the average length of the carbon fiber aggregate is less than 1.5 mm, the anchoring force with the concrete structure etc. is small, and the aggregate is easily pulled out from the base material concrete structure etc. in response to tensile stress, which is good. This is not preferable because it is not possible to obtain sufficient reinforcement efficiency.
• the average length of the carbon fiber aggregate is greater than 60 mm, it may be difficult to uniformly mix the aggregate into a concrete composition or the like.
• the aggregates become entangled during mixing, it may become difficult to uniformly disperse them into a concrete composition or the like.
• the average length of the carbon fiber aggregates is determined by measuring the length of 50 carbon fiber aggregates in the longitudinal direction visually using a vernier caliper, or in an image taken with a digital camera or optical microscope. It can be calculated by averaging the measured values.
• the average length of the carbon fiber aggregate is 1.2 to 5.0 times the average length of the carbon fibers contained in the carbon fiber aggregate.
• the average length of the carbon fiber aggregate is within the above range, good reinforcing efficiency may be obtained.
• the average length of the carbon fiber aggregate is 1.4 times or more, 1.5 times or more, or 1.6 times or more the average length of the carbon fibers, and/or 4.5 times or more 4.0 times or less, 3.5 times or less, 3.0 times or less, or 2.5 times or less.
• the average length of the carbon fiber aggregate is within the above range, particularly good reinforcing efficiency may be obtained.
• the average maximum width of the carbon fiber aggregate may be 0.1 mm to 3.0 mm.
• the average length of the aggregate is 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, or 0.5 mm or more, and/or preferably 2.8 mm or less, 2.6 mm or less, It is 2.4 mm or less, 2.2 mm or less, or 2.0 mm or less.
• the average maximum width of the carbon fiber aggregate is the largest average length (width) in the direction perpendicular to the length direction.
• the average maximum width of the carbon fiber aggregate is less than 0.1 mm, the aggregate may break, and there will be many short aggregates that have low anchoring force to concrete structures, etc., and it is difficult to achieve good reinforcement efficiency. It is not desirable because it cannot be obtained.
• the average maximum width of the carbon fiber aggregates is larger than 3.0 mm, the number of aggregates dispersed in concrete structures etc. decreases when compared with the same amount of aggregates added. As a result, the total surface area of contact with concrete structures etc. becomes smaller, and good reinforcement efficiency tends to be difficult to obtain.
• the average maximum width of the carbon fiber aggregates is determined by measuring the length of 50 carbon fiber aggregates in the minor axis direction using a caliper or the like, or by measuring the length of 50 carbon fiber aggregates in an image obtained with a digital camera or optical microscope. It can be calculated by averaging the measured values.
• the aspect ratio of the aggregate may be between 5 and 150.
• the aspect ratio of the aggregate is 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more, and/or 120 or less, 100 or less, 80 or less, or 60 or less.
• the aspect ratio of the carbon fiber aggregate is a value obtained by dividing the major axis of the spindle-shaped aggregate by the minor axis, and can be expressed as average length/average maximum width. As the degree of elongation increases, the aspect ratio increases. If the aspect ratio is less than 5, the total surface area of contact with a concrete structure or the like becomes small, and the fixing force becomes small, making it impossible to obtain good reinforcing efficiency, which is not preferable.
• the aspect ratio is greater than 150, it becomes difficult to mix uniformly into concrete compositions, etc., and the aggregate may break, so good reinforcing efficiency tends not to be obtained.
• Carbon fibers are the raw material for the aggregate, and include ordinary carbon fibers (carbon fibers that are not recycled carbon fibers, so-called virgin carbon fibers), recycled carbon fibers, and mixtures thereof.
• the carbon fiber may be, for example, a PAN-based carbon fiber or a pitch-based carbon fiber.
• the form of the carbon fibers is not particularly limited, but may be in the form of a carbon fiber bundle composed of a plurality of single yarns (filaments).
• the number of filaments constituting the carbon fiber bundle may range from 1,000 to 80,000, or from 3,000 to 50,000. Further, the diameter of the filament constituting the carbon fiber may be 0.1 ⁇ m to 30 ⁇ m, 1 ⁇ m to 10 ⁇ m, or 3 ⁇ m to 8 ⁇ m.
• Regenerated carbon fiber contains a carbon fiber component and a carbon component other than the carbon fiber component (particularly a residual carbon component). Usually, in recycled carbon fibers, carbon components other than the carbon fiber component are attached to the surface of the carbon fiber component.
• the recycled carbon fiber is not particularly limited, but may be, for example, recycled carbon fiber obtained by heat treating a carbon fiber-containing plastic product such as carbon fiber reinforced plastic (CFRP).
• CFRP carbon fiber reinforced plastic
• the recycled carbon fiber is a recycled carbon fiber obtained by a semiconductor thermal activation method.
• a particularly preferred embodiment of the following method according to the present disclosure involves decomposing a plastic component contained in a carbon fiber-containing plastic product by a semiconductor thermal activation method to produce recycled carbon fiber.
• TASC method is a method of decomposing a compound to be decomposed such as a polymer using thermal activation of semiconductors (TASC).
• TASC method for a method of producing recycled carbon fiber by decomposing plastic components contained in carbon fiber-containing plastic products using a semiconductor thermal activation method, see, for example, the descriptions in Japanese Patent No. 4517146 and Japanese Patent Application Publication No. 2019-189674. can do.
• the carbon fiber component in the recycled carbon fibers may be modified by undergoing heat treatment or the like during the manufacturing process of the recycled carbon fibers.
• the residual carbon component in the recycled carbon fiber usually originates from the resin contained in the carbon fiber-containing plastic product used as a raw material when manufacturing the recycled carbon fiber. Generally, in the process of heat treating a carbon fiber-containing plastic product, the plastic component is thermally decomposed and residual carbon remains on the surface of the carbon fiber component.
• the residual carbon component is preferably more than 0% by weight and 5.0% by weight or less based on the recycled carbon fiber. In this case, it may be possible to obtain an aggregate with improved reinforcement efficiency.
• the residual carbon component is more than 0% by weight and less than 5.0% by weight
• single fibers may be It is thought that there is a relatively small amount of carbon components (particularly charcoal) that can become foreign substances that inhibit alignment and focusing. Therefore, it is possible to obtain an aggregate that is firmly fixed by the binder, so that it is difficult to unbundle when mixed with a concrete composition or the like, and it is thought that dispersion into single fibers can be suppressed.
• the residual carbon component is 4.0% by weight or less, 3.0% by weight or less, or 2.0% by weight or less based on the recycled carbon fiber. It is preferable that the residual carbon component is reduced as much as possible, but it is preferably 0.1% by weight or more, 0.2% by weight or more, 0.4% by weight or more, 0.6% by weight, 0.6% by weight or more based on the carbon fiber. It may be 8% by weight or more, 1.0% by weight or more, or 1.2% by weight or more.
• the content of residual carbon components in the recycled carbon fibers can be measured by thermogravimetric analysis (TGA method).
• Residual carbon content by thermogravimetric analysis can be measured using the following procedure: (i) Sample pieces of 1 to 4 mg obtained by pulverizing recycled carbon fibers were measured in a thermogravimetric analyzer using an air supply rate of 0.2 L/min, a heating rise rate of 5°C/min, and a With a recording speed of 6s, Raising the temperature from room temperature to 100°C, holding at 100°C for 30 minutes; Raising the temperature from 100°C to 400°C, and A thermogravimetric analysis was performed for a total of about 600 minutes, including a holding step at 400 ° C.
• the recycled carbon fiber contains resin derived from a sizing agent or the like, the above measurement can be performed after removing the resin.
• the carbon fibers can have an average length of 1 mm or more and less than 30 mm. Fibers with lengths in this range can be obtained, for example, by cutting fibers with relatively long dimensions.
• the average length of the carbon fibers may be 2 mm or more, 3 mm or more, or 4 mm or more, and/or 29 mm or less, 28 mm or less, 27 mm or less, 26 mm or less, 25 mm or less, 24 mm or less, 23 mm or less, 22 mm. Below, it may be 21 mm or less, or 20 mm or less. In particular, the average length of the carbon fibers may be 8 mm to 25 mm, or 9 mm to 20 mm.
• the average length of the carbon fibers is 1 mm or more and less than 30 mm, the single fibers are facilitated to be bundled while arranging in a certain direction, and the bundles are difficult to unravel when mixed with a concrete composition, etc. It is thought that dispersion into single fibers can be suppressed.
• the average length of the raw material fibers is sufficiently long, the fibers can be easily oriented in one direction, making it possible to obtain a spindle-shaped aggregate. it is conceivable that.
• the average length of carbon fibers can be determined by measuring the length of 50 carbon fibers visually using a vernier caliper, or in an image taken with a digital camera or optical microscope, and averaging the measured values. It can be calculated.
• a method for manufacturing a spindle-shaped carbon fiber aggregate according to the present disclosure includes: Providing a mixture consisting of at least carbon fibers and a binder-containing liquid (providing step); Producing a spindle-shaped precursor by rolling the mixture in a container (granulation step) and drying the precursor (drying step).
• the method according to the present disclosure provides a mixture comprising at least carbon fibers and a binder-containing liquid.
• the mixture consists in particular of carbon fibers and a binder-containing solution.
• the amount of binder-containing liquid in the mixture is preferably 10% to 70% by weight, particularly preferably 15% to 60% by weight, or 20% to 50% by weight.
• the fibers are bundled particularly well due to the liquid contained in the binder. Furthermore, in this case, the load of the drying process can be reduced because the amount of liquid contained in the binder does not become excessive.
• the binder-containing liquid is a binder dispersion liquid or a binder solution, and contains a binder and a solvent or a dispersion medium.
• the binder has the role of focusing the carbon fibers in the aggregate and maintaining the shape of the aggregate.
• the binder is not particularly limited, but is preferably a thermoplastic resin or a thermosetting resin. More specifically, the binder includes epoxy resin, urethane-modified epoxy resin, vinyl ester resin, acrylic resin, polyester resin, phenol resin, polyamide resin, polyurethane resin, polycarbonate resin, polyetherimide resin, polyamideimide resin, polyimide. Examples include resins, bismaleimide resins, polysulfone resins, polyethersulfone resins, epoxy-modified urethane resins, polyvinyl alcohol resins, and polyvinylpyrrolidone resins. These resins can be used alone or in combination of two or more.
• binder examples include bentonite, lignin sulfonate, molasses, carboxymethyl cellulose, konjac powder, sodium alginate, polyacrylamide, polyvinyl acetate, polyvinyl alcohol, and starch. These can be used alone or in combination of two or more, and can also be used in combination with the above resins.
• solvent or dispersion medium is not particularly limited as long as it is a liquid that can dissolve or disperse the binder.
• Solvents or dispersion media include water, alcohols (for example methanol or ethanol), ketones (for example methyl ethyl ketone or acetone), hydrocarbons (for example cyclohexane, toluene or xylene), halogenated hydrocarbons (for example dichloromethane), amides (for example N- methylpyrrolidone or dimethylformamide), ethers (eg tetrahydrofuran).
• the solvent or dispersion medium is particularly preferably water.
• the binder-containing liquid used in the present disclosure can be prepared, for example, by further adding a solvent or dispersion medium to a relatively concentrated commercially available sizing agent composed of a binder and a solvent or dispersion medium.
• a binder-containing liquid can be prepared by adding a dispersion medium (especially water) to a sizing agent containing a binder and a dispersion medium (especially water).
• the sizing agent (and the binder-containing liquid obtained by adding a solvent or dispersion medium to the sizing agent) may be, for example, in the form of a water emulsion in which the binder is dispersed in water, and in particular may be a water-based polyurethane.
• the concentration of the binder in the sizing agent is not particularly limited, but may be, for example, 10 to 80% by weight, 20 to 60% by weight, or 30 to 50% by weight.
• the amount of the binder may be 0.5% by weight or more, 1% by weight or more, 1.5% by weight or more, 2.0% by weight or more, or 3.0% by weight relative to the binder-containing liquid, and Or, it may be 20% by weight or less, 18% by weight or less, 16% by weight or less, 14% by weight or less, or 12% by weight or less.
• the amount of binder is particularly preferably from 1% to 16% by weight, or from 2% to 12% by weight, based on the binder-containing liquid.
• the amount of the binder is preferably 0.1% to 10% by weight, particularly preferably 0.5% to 8% by weight, or 1% to 6% by weight based on the carbon fiber aggregate. Weight%.
• the fiber component particularly the carbon fiber
• a fiber opening treatment By performing the fiber opening treatment, it may be possible to eliminate the entanglement of the fibers and promote orientation of the fibers in one direction in the granulation process.
• Carbon fibers that can be used to produce a spindle-shaped carbon fiber aggregate can be subjected to an opening treatment in advance. By performing the fiber opening treatment, it may be possible to promote convergence of the single fibers while arranging them along a certain direction in the granulation process.
• the method of opening the fibers is not particularly limited, but can be performed using a rotating blade, for example.
• the rotating blade for opening may be an auxiliary blade installed in the granulator.
• the opening treatment can also be performed by high-speed stirring.
• the method for obtaining a mixture from carbon fibers and a binder-containing liquid is not particularly limited.
• the carbon fibers and the binder-containing liquid can be put in the form of a mixture into a container used in the granulation process.
• a mixture may be obtained by pouring a binder-containing liquid onto a mass of carbon fibers and optionally stirring, and this mixture may be poured into a container.
• the carbon fibers and the binder-containing liquid can be separately charged into a container and mixed within the container to form a mixture. Mixing and granulation may be performed simultaneously.
• the carbon fibers and binder-containing liquid in the mixture do not necessarily need to be uniformly distributed within the mixture.
• the mixture can be stirred during the granulation process to improve uniformity.
• a spindle-shaped precursor is formed by rolling a mixture in a container (hereinafter, this process may be referred to as "granulation process"). Manufacture.
• the method of rolling the mixture in the container is not particularly limited, and known methods (particularly known granulation methods) can be used.
• the spindle-shaped precursor is produced by rolling the mixture in a container in the clearance between the inner wall of the container and a rotating body within the container.
• the method for rolling the mixture in the clearance between the inner wall of the container and the rotating body within the container is not particularly limited. An exemplary method for this is described below with reference to FIG.
• FIG. 1 is a schematic diagram of one embodiment of an agitated granulator that can be used in the present disclosure.
• the stirring granulator 10 in FIG. 1 has a cylindrical container portion 12 as a container and a stirring blade 14 as a rotating body.
• the stirring granulator 10 shown in FIG. 1 is of a horizontal type, and in normal use, the opening of the container portion 12 opens toward the side.
• FIG. 1 is a view looking into the inside of the container section.
• a shaft portion 16 is attached to the inner wall of the container portion 12 facing the opening (the wall on the back side in the above viewpoint).
• the shaft portion 16 extends in the horizontal direction.
• the stirring blade 14 can rotate around this shaft portion 16 (counterclockwise ("A") in the example of FIG. 1, but may also rotate clockwise). That is, the stirring blade 14 in FIG. 1 is configured to rotate in a plane parallel to the direction of gravity.
• an auxiliary blade for opening the fibers can also be installed in the container section 12.
• a mixture containing carbon fibers and a binder-containing liquid is optionally mixed and stirred by the stirring blade 14 rotating in the container 12, and the mixture is mixed and stirred between the inner wall of the container 12 and the stirring blade 14 inside the container 12. It is rolled with a clearance between (indicated by the symbol "C" in FIG. 1).
• the granulation process can be carried out at ambient temperature or by heating.
• the granulation process can be carried out for, for example, 1 minute to 1 hour, 5 minutes to 20 minutes, or 8 minutes to 15 minutes.
• the container of the present disclosure is not particularly limited as long as it is suitable for holding a mixture therein and for performing the above-described granulation treatment on the mixture.
• the container is made of a material with excellent rigidity and durability.
• the inner wall of the container be made of a material that does not cause wear during rolling of the mixture, or that the inner wall be subjected to a surface treatment for this purpose.
• the container is not tilted and is substantially parallel to the horizontal direction.
• the portion of the inner wall of the container that is located below in the direction of gravity may not be inclined but may be substantially parallel to the horizontal direction.
• the rotating body is configured to be able to roll a mixture containing carbon fibers and a binder-containing liquid between itself and the inner wall of the container by rotating within the container.
• the rotating body is, for example, attached to a shaft installed in the container and configured to be able to rotate around the shaft.
• the rotating body preferably has the form of a blade.
• the rotating body is particularly preferably a stirring blade.
• the stirring blade is preferably made of a material with excellent rigidity and durability, and in particular, it should be made of a material that does not cause wear during rolling of the mixture, or should be surface-treated for this purpose. is preferred.
• the size of the clearance between the inner wall of the container and the rotating body that is, the distance between the inner wall of the container and the rotating body may be constant, or may vary continuously or discontinuously. There may be.
• the size of the clearance between the inner wall of the container and the rotating body within the container can be set as appropriate depending on the desired size of the carbon fiber aggregate. For example, it may be 1 to 10 mm.
• a known stirring granulator can be used as the device having the above container and rotating body.
• the stirring granulator is not particularly limited, and for example, a Henschel type granulator (Henschel mixer), a bag mill type granulator, or an Eirich type stirring granulator can be used. Both vertical and horizontal types of stirring granulators can be used.
• spindle-shaped precursor contains carbon fibers and a binder, and also contains a liquid (particularly water) derived from the binder-containing liquid. In the drying step described below, liquid (particularly water) in the precursor can be removed.
• the method of drying the precursor is not particularly limited, and the temperature conditions, time conditions, etc. can be determined as appropriate depending on the moisture content of the obtained precursor.
• the mortar composition according to the present disclosure is obtained by adding water to a spindle-shaped carbon fiber aggregate, cement, fine aggregate such as sand, and an admixture and mixing the mixture. Concrete compositions are obtained by mixing these raw materials with coarse aggregate such as gravel. Various additives and other raw materials may be added to such concrete or mortar compositions for the purpose of improving physical properties depending on the intended use.
• the addition rate (content rate) of carbon fibers constituting the spindle-shaped carbon fiber aggregate according to the present disclosure can be selected depending on the application, but preferably 0% to the total amount of the concrete or mortar composition. 0.01 to 10% by volume, particularly 0.05 to 5% by volume, 0.1 to 3% by volume, or 0.2 to 1.5% by volume. Furthermore, the spindle-shaped carbon fiber aggregate according to the present disclosure and existing reinforcing fiber materials can be used in combination. If the carbon fiber addition rate is less than 0.01% by volume, it is not preferable because good reinforcing efficiency cannot be obtained.
• the addition rate of carbon fiber exceeds 10% by volume, it may become difficult to uniformly mix the aggregate into a concrete composition or the like.
• the aggregates become entangled during mixing, it may become difficult to uniformly disperse them into a concrete composition or the like. This is undesirable because the viscosity of the concrete composition may increase and the handling properties may deteriorate.
• ⁇ Method of adding carbon fiber aggregate As a method for adding the spindle-shaped carbon fiber aggregate according to the present disclosure to a concrete composition, for example, the aggregate is made into a dry premix with cement, fine aggregate, coarse aggregate, etc., and then water is added and kneaded. There are two methods: mixing cement, fine aggregate, coarse aggregate, etc., and water, then adding aggregate after sufficiently stirring the mixture.
• a pan type mixer As a mixer for kneading, a pan type mixer, a tilting mixer, an omni mixer, a Hobart mixer, a truck mixer, etc. can be used.
• the concrete or mortar structure according to the present disclosure can be manufactured by curing the concrete or mortar composition obtained as described above.
• the carbon fibers may exist in the form of spindle-shaped carbon fiber aggregates according to the present disclosure, and some or all of the aggregates may be unbundled and dispersed into single fibers or fiber bundles. It's okay.
• carbon fiber aggregates are mixed with concrete compositions, etc., so that the carbon fibers are relatively less likely to break even if they are dispersed into single fibers or fiber bundles during manufacturing. A uniformly dispersed structure can be obtained.
• the method for curing the concrete or mortar composition is not particularly limited, and the curing method and conditions can be determined as appropriate depending on the type of structure, construction conditions, location conditions, environmental conditions, etc. For example, it may be used in construction or repair methods such as 3D printing, coating, injection, filling, plastering, and spraying.
• Carbon fiber recycled carbon fiber with an average single fiber diameter of 6.7 ⁇ m, a single fiber tensile strength of 5.3 GPa, a Weibull shape coefficient of 7.6, and a residual carbon content of 1.4% by weight, obtained by a semiconductor thermal activation method, was used. .
• Single fiber tensile strength was measured in accordance with JIS R7606 as follows: Collecting at least 30 single fibers from the fiber bundle, Measure the diameter of the single fiber in the side image of the single fiber taken with a digital microscope, calculate the cross-sectional area, The sampled single fibers were fixed on a perforated mount using adhesive. The mount to which the single fibers were fixed was attached to a tensile testing machine, and a tensile test was performed at a sample length of 10 mm and a strain rate of 1 mm/min to measure the tensile breaking stress. Calculate the tensile strength from the cross-sectional area and tensile breaking stress of the single fiber, The average tensile strength of at least 30 single fibers was defined as the single fiber tensile strength.
• thermogravimetric analysis The amount of residual carbon component in the recycled carbon fibers was determined by thermogravimetric analysis (TGA method) as follows: (i) A 4 mg sample piece obtained by pulverizing recycled carbon fiber was measured in a thermogravimetric analyzer using an air supply rate of 0.2 L/min, a heating rise rate of 5°C/min, and a heating rate of 1/6 s. Thermogravimetric analysis with steps consisting of heating from room temperature to 100°C, holding at 100°C for 30 minutes, heating from 100°C to 400°C, and holding at 400°C for 480 minutes at a recording speed.
• Binder-containing liquid A binder-containing liquid (water emulsion sizing agent) containing 10.2 g of urethane resin as a binder and 255 g of water as a dispersion medium was prepared.
• granulation process For the granulation process, a vertical stirring granulator (30L MTI mixer, manufactured by Tsukishima Kikai Co., Ltd.) was used.
• the stirring granulator had a stirring blade and also had an auxiliary blade to promote opening of the fibers.
• the moisture content in the mixture was 33.3% by weight.
• the rotation speed of the stirring blade was 290 rpm, and the rotation speed of the auxiliary blade was 5,000 rpm.
• Binder content The binder content for the aggregate of Example 1 was 2.0% by weight.
• the average length of the carbon fiber aggregate according to Example 1 was 32.8 mm, and the average maximum width was 0.9 mm. Since the average length of the recycled carbon fibers was 15 mm, the average length of the carbon fiber aggregate was 2.2 times the average length of the recycled carbon fibers.
• the aspect ratio (major axis/minor axis) of the aggregate of Example 1 was calculated.
• the addition rate of carbon fiber in the obtained green mortar composition was 0.5% by volume.
• the water/cement ratio was 30.0% by weight and the fine aggregate/cement ratio was 45.0% by weight.
• the green mortar composition according to Example 1 was poured into a formwork of 40 mm width x 40 mm height x 160 mm length, and was cured in air at 20 °C for 2 days, and then in water at 20 °C for 4 days.
• a mortar structure specimen (cured product) for measuring bending fracture energy was manufactured.
• Example 2 ⁇ Preparation of materials> (Carbon fiber)
• Carbon fiber The same recycled carbon fiber as in Example 1 was used as the carbon fiber, except that it was cut to an average length of 10 mm.
• Binder-containing liquid A binder-containing liquid (water emulsion sizing agent) containing 10.2 g of urethane resin as a binder and 291 g of water as a dispersion medium was prepared.
• the stirring granulator had a stirring blade and also had an auxiliary blade to promote opening of the fibers.
• the moisture content in the mixture was 36.3% by weight.
• the rotation speed of the stirring blade was 320 rpm, and the rotation speed of the auxiliary blade was 3,000 rpm.
• FIG. 4 is a photograph of the carbon fiber aggregate according to Example 2. The obtained carbon fiber aggregate had a spindle shape.
• Binder content The binder content for the aggregate of Example 2 was 2.0% by weight.
• the average length of the carbon fiber aggregate evaluated in the same manner as in Example 1 was 18.9 mm, and the average maximum width was 1.6 mm. Since the average length of the recycled carbon fibers was 10 mm, the average length of the carbon fiber aggregate was 1.9 times the average length of the recycled carbon fibers.
• Comparative example 1 In Comparative Example 1, virgin carbon fiber bundles cut to an average length of 10 mm (24,000 single fibers per bundle, average single fiber diameter 6.8 ⁇ m, single fiber tensile strength) were used instead of recycled carbon fiber aggregates. A green mortar composition and a mortar structure were produced and evaluated in the same manner as in Example 1, except that a strength of 5.4 GPa and a Weibull shape factor of 4.9) were used. The results are shown in Table 1 below.
• the green mortar compositions according to Examples 1 and 2 exhibited fluidity equivalent to that of the raw mortar composition without fiber reinforcement according to Reference Example 1, and had better fluidity than the raw mortar composition according to Comparative Example 1. showed his sexuality. The reason for this is that the carbon fiber aggregates of Examples 1 and 2 had a higher bundling power than the cut virgin carbon fiber bundles of Comparative Example 1, and their dispersion into single fibers was suppressed. The reason is that the viscosity did not increase. Further, the mortar structures according to Examples 1 and 2 had higher bending strength and bending fracture energy than the mortar structures without fiber reinforcement according to Reference Example 1. Therefore, by using the green mortar compositions according to Examples 1 and 2, excellent moldability and reinforcement efficiency can be obtained at the same time.
• the mortar structure according to Example 1 has further increased bending strength and bending fracture energy than the mortar structure according to Example 2, and even though it contains recycled carbon fiber, it has a higher bending strength than the mortar structure according to Example 2. It exhibited higher bending strength and bending failure energy than such mortar structures.
• the reason for this is that the carbon fiber aggregate of Example 1 had a longer average length than the aggregate of Example 2, and the fixing force with the mortar was further increased, so that it was less susceptible to tensile stress. On the other hand, the aggregate became more difficult to pull out from the mortar, and the reinforcement efficiency was particularly good.

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