JPWO2019221155A1 - Carbon fiber reinforced plastic reinforced material and plastic reinforced material - Google Patents

Abstract

At least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer, at least one surface of at least one carbon fiber reinforced plastic layer, at least one cellulose nanofiber layer is arranged so as to be adjacent. The carbon fiber reinforced plastic layer contains a carbon fiber reinforced plastic, and the cellulose nanofiber layer contains a cellulose nanofiber and a polymer compound. The carbon fiber reinforced plastic reinforced material is lightweight. It is a carbon fiber reinforced plastic reinforced material with excellent impact strength. The other material-reinforcing material containing the cellulose nanofibers and the polymer compound is a material for strengthening the other material (hydrophobic resin or the like).

Description

  The present invention relates to a carbon fiber reinforced plastic reinforced material and a plastic reinforced material.

  For sports equipment, there is always a demand for "lighter and stronger materials", so many products using carbon fiber reinforced plastic (hereinafter also referred to as "CFRP") are manufactured. Since there is a high need for CFRP with high impact resistance, such as softball bats and tennis rackets, and there is great potential demand, research is being actively conducted on modifying matrix resins and adding fillers with excellent strength. ..

  However, although CFRP is lightweight and has high strength, impact strength is one of the drawbacks in practical use due to the low impact strength of the resin because it uses resin as the base material. As shown in FIG. , The resin on the surface is cracked, leading to destruction. In reality, gravel and the like often collide with each other to cause cracks on the surface. For this reason, one of the drawbacks of CFRP is impact strength. Therefore, high-strength base material resins have been studied, but there is no report of significant performance improvement.

  By the way, cellulose nanofibers (hereinafter sometimes referred to as “CNF”) can be manufactured from wood, and while being lightweight, they are excellent in strength. It is considered to increase the impact strength of CFRP. Since CNF is a biomass resource derived from plant fiber, it can realize a sustainable recycling society without increasing carbon dioxide that causes global warming. However, since CNF has a strong hydrogen bond between molecular chains, it cannot be dissolved in a general organic solvent and is hydrophilic, so that it is difficult to disperse CFRP in a matrix resin. It is indispensable to apply a hydrophobizing treatment (for example, chemically modifying with a hydrophobic group) with a drug, and there is no example in which CNF is dispersed in a CFRP matrix resin without performing the hydrophobizing treatment. Examples of such a hydrophobic treatment include a method in which CNF is charged together with a chemical agent and reacted by heating. In that case, for example, the heating temperature is 120° C., the treatment time is 1 hour, and the chemical agent for treatment is 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (FAS13) and the like are used. Since such a hydrophobizing treatment is required, the cost becomes high, which hinders the practical application of the composite of CNF to CFRP, and the method of hydrophobizing can increase the strength of CFRP. Has not reached.

  Thus, application of CNF to sports equipment has been studied for a long time, but excellent results have not been obtained. In particular, for application to CFRP, it is very difficult to disperse CNF in a matrix resin of CFRP, and an appropriate method for improving the impact strength of CFRP has not been found. Although the above problems are related to the application to CFRP, the same problem occurs when CNF is applied to other materials.

  The present invention has been made to solve the above problems, and an object thereof is to provide a carbon fiber reinforced plastic reinforced material that is lightweight and has excellent impact strength. Another object of the present invention is to provide a material for reinforcing plastic (hydrophobic resin or the like).

In view of the above object, as a result of intensive studies, a carbon fiber reinforced plastic layer containing a carbon fiber reinforced plastic and a cellulose nanofiber layer containing a cellulosic nanofiber and a polymer compound are arranged so as to be adjacent to each other. It was found that a carbon fiber reinforced plastic reinforced material that is lightweight and has excellent impact strength can be obtained at low cost without subjecting it to chemical treatment. Although a method of mixing CNF with a matrix resin of CFRP has been proposed, a method of stacking CNF as a sheet on the surface of CFRP has not even been studied. The present inventors have also found that the strength of the cellulose nanofiber layer containing the cellulose nanofiber and the polymer compound can be improved by applying it to a material other than carbon fiber. The present inventors have conducted further research and completed the present invention. That is, the present invention includes the following configurations.
Item 1. At least one carbon fiber reinforced plastic layer, and at least one cellulose nanofiber layer is provided,
At least one surface of at least one carbon fiber reinforced plastic layer, at least one cellulose nanofiber layer is arranged so as to be adjacent,
The carbon fiber reinforced plastic layer contains carbon fiber reinforced plastic,
The cellulose nanofiber layer is a carbon fiber reinforced plastic reinforced material containing cellulose nanofibers and a polymer compound.
Item 2. Item 2. The carbon fiber reinforced plastic reinforced material according to Item 1, wherein the thermosetting resin that is the matrix of the carbon fiber reinforced plastic is an epoxy resin.
Item 3. Item 3. The carbon fiber reinforced plastic reinforced material according to Item 1 or 2, wherein the polymer compound in the cellulose nanofiber layer is an epoxy resin.
Item 4. Item 4. The carbon fiber reinforced plastic reinforced material according to any one of Items 1 to 3, wherein at least one carbon fiber reinforced plastic layer is arranged between two layers of the cellulose nanofiber layers.
Item 5. Item 4. The carbon fiber reinforced plastic reinforced material according to any one of Items 1 to 3, wherein the carbon fiber reinforced plastic layers and the cellulose nanofiber layers are alternately arranged.
Item 6. A plastic reinforced material including cellulose nanofibers and a polymer compound.
Item 7. A method for producing a carbon fiber reinforced plastic reinforced material according to any one of Items 1 to 5,
(1) A step of contacting cellulose nanofibers with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating, and (2) A production method comprising a step of forming a cellulose nanofiber layer on a carbon fiber reinforced plastic or a precursor thereof by using the dispersion liquid obtained in the step (1) and heating and curing the layer.
Item 8. Item 8. The method according to Item 7, wherein the carbon fiber reinforced plastic or its precursor contains an epoxy resin as a matrix resin.
Item 9. Item 9. The method according to Item 7 or 8, wherein the carbon fiber reinforced plastic or its precursor is a carbon fiber reinforced plastic or a carbon fiber prepreg.
Item 10. Item 6. A method for manufacturing a plastic-reinforced material according to Item 6,
(1) A production method comprising a step of bringing cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating material.
Item 11. Item 11. The method according to any one of Items 7 to 10, wherein the polymer compound in the electrodeposition liquid is an epoxy resin.

  According to the present invention, a carbon fiber reinforced plastic reinforced material that is lightweight and has excellent impact strength can be obtained at low cost without performing a hydrophobic treatment. Further, according to the present invention, a material for reinforcing plastic (hydrophobic resin or the like) can be obtained.

It is a schematic sectional drawing explaining the process (left figure) which cracks into the resin of the surface of CFRP, and leads to destruction, and the strengthening mechanism at the time of compounding CFRP and CNF (right figure). 1 is a photograph showing the appearance of the sheet obtained as a cellulose nanofiber layer (plastic reinforcing material) in Example 1. 5 is a graph showing the effect of improving impact strength when a cellulose nanofiber layer (plastic reinforced material) is pressure-bonded to a carbon fiber prepreg in Example 1. 5 is a graph showing the effect of improving the impact strength when the cellulose nanofiber layer (plastic reinforced material) and the carbon fiber reinforced plastic are pressure-bonded in Example 2. 1 shows a schematic cross-sectional view and an appearance photograph when a cellulose nanofiber layer (plastic reinforcing material) is pressure-bonded to a carbon fiber prepreg in Example 1. 1 shows a layer structure of carbon fiber reinforced plastic reinforced materials obtained in Examples 3 to 6 and Comparative Example 1. The relationship between the CNF content and the bending rigidity of the carbon fiber reinforced plastic reinforced materials obtained in Examples 3 to 6 and Comparative Example 1 is shown. The relationship between the CNF content of the carbon fiber reinforced plastic reinforced materials obtained in Examples 3 to 6 and Comparative Example 1 and the specific bending rigidity (=bending rigidity/sample density) is shown. The relationship between the CNF content and the bending strength of the carbon fiber reinforced plastic reinforced materials obtained in Examples 3 to 6 and Comparative Example 1 is shown. The relationship between the CNF content and the specific bending strength (=bending strength/sample density) of the carbon fiber reinforced plastic reinforced materials obtained in Examples 3 to 6 and Comparative Example 1 is shown. 6 is a photograph of an interface between the prepreg of the carbon fiber reinforced plastic reinforced material obtained in Example 5 and a CNF and a resin layer derived from an electrodeposition liquid by a digital microscope. The relationship between the CNF content and the bending rigidity and specific bending rigidity (=bending rigidity/sample density) of the carbon fiber reinforced plastic reinforced material when the curing temperature is 150°C and 170°C is shown. The relationship between the CNF content and the bending strength and specific bending strength (=bending strength/sample density) of the carbon fiber reinforced plastic reinforced material when the curing temperature is 150°C and 170°C is shown.

  In the present specification, the term “inclusion” is a concept including both “comprise”, “consisting essentially of”, and “consist of”. Further, in the present specification, when the numerical range is indicated by “A to B”, it means A or more and B or less.

  As used herein, “carbon fiber reinforced plastic reinforced material” means a composite material reinforced with carbon fiber reinforced plastic. Further, "plastic reinforced material" means a material in which plastic is reinforced.

1. Carbon fiber reinforced plastic reinforced material and plastic reinforced material The carbon fiber reinforced plastic reinforced material of the present invention comprises at least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer, and the carbon fiber reinforced plastic layer, Both contain carbon fiber reinforced plastic, the cellulose nanofiber layer, both contain a cellulose nanofiber and a polymer compound, at least one of the carbon fiber reinforced plastic layer, the cellulose It is arranged so as to be adjacent to at least one of the nanofiber layers. Further, the plastic reinforcing material of the present invention contains cellulose nanofibers and a polymer compound.

  According to such a configuration, when applied to carbon fiber reinforced plastic, it is possible to dramatically improve impact strength by using cellulose nanofibers. From this, conversely, it is possible to reduce the amount of carbon fiber reinforced plastic conventionally required for the required impact strength, which may lead to resource saving. In addition, since cellulose nanofibers are lighter than carbon fiber reinforced plastics, they can lead to weight reduction of products, and particularly to improvement of fuel efficiency in the case of moving bodies (automobiles, aircrafts, etc.). In addition, the strength of plastics can be improved by using cellulose nanofibers.

(1-1) Carbon fiber reinforced plastic layer In the present invention, the carbon fiber reinforced plastic layer contains carbon fiber reinforced plastic.

  For this carbon fiber reinforced plastic, usually, an autoclave method is adopted in which a plurality of prepregs obtained by impregnating a carbon fiber with a thermosetting resin and semi-dried are piled up, and the thermosetting resin is cured by compression heating to be molded. ing. That is, it has a structure in which carbon fibers are dispersed in a thermosetting resin that is a matrix.

  The carbon fiber material in this case is not particularly limited as long as it is a structure made of carbon fibers (particularly a structure made of conductive carbon fibers). For example, a flat carbon fiber sheet, a pipe-shaped carbon fiber sheet, a wing-shaped carbon fiber sheet, an L-shaped carbon fiber sheet, an H-shaped carbon fiber sheet and the like can be mentioned. In particular, not only a carbon fiber material in which carbon fibers are linearly arranged but also a carbon fiber material having a complicated three-dimensional shape can be used. The fiber diameter of one carbon fiber constituting such a carbon fiber material is preferably 0.001 to 50 μm on average, from the viewpoint of easily precipitating a polymer compound to obtain a carbon fiber prepreg. Known or commercially available products can be used as such carbon fiber material.

  The thermosetting resin is not particularly limited, and examples thereof include epoxy resin, phenol resin (novolac resin, etc.), acrylic resin, nylon resin, vinyl resin, polyamide resin, polyimide resin, polyamideimide resin, polystyrene resin, polycarbonate. Resin, polyolefin resin, polyester, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, etc. may be mentioned. These thermosetting resins can be used alone or in combination of two or more kinds. As these thermosetting resins, those having the same functional groups as those of the polymer compound in the cellulose nanofiber layer are preferable in consideration of the affinity with the cellulose nanofiber layer described later, and among them, the epoxy resin is more preferable.

  In such a carbon fiber reinforced plastic, the thickness of the polymer compound that coats each carbon fiber is preferably 20 to 200 μm, and 50 to 100 μm from the viewpoint of further improving the strength and affinity with the cellulose nanofiber layer. More preferable.

  Further, the carbon fiber reinforced plastic layer, the total amount of the carbon fiber and the thermosetting resin is 100 mass% from the viewpoint of affinity with the cellulose nanofiber layer while further improving the strength, and the content rate of the carbon fiber is 20 to 70% by volume is preferable, and 25-60% by volume is more preferable.

  Such carbon fiber reinforced plastic is not particularly limited, and known or commercially available products can be used.

(1-2) Cellulose Nanofiber Layer In the present invention, the cellulose nanofiber layer contains cellulose nanofibers and a polymer compound.

  As the cellulose nanofibers, known ones can be widely adopted, and there is no particular limitation. Moreover, as the cellulose constituting the cellulose nanofiber, any of plant-derived cellulose, animal-derived cellulose, and bacterial-derived cellulose can be preferably used. These may be used alone or in combination of two or more.

  As plant-derived cellulose, for example, hardwood-derived cellulose (eucalyptus, poplar, etc.), softwood-derived cellulose (pine, fir, cedar, cypress, etc.), herbaceous-derived cellulose (straw, bagasse, reed, kenaf, abaca, sisal, etc.) , And seed hair fibers (cotton, etc.). The raw material pulp may be mechanical pulp obtained by mechanically treating wood chips, chemical pulp obtained by chemically removing non-cellulosic components from wood chips, and further purified by dissolving non-cellulose components. It may be pulp.

  In addition, cellulose derived from animals such as ascidian, cellulose derived from bacteria such as nata de coco, and the like can be used. Further, such cellulose does not necessarily have to be composed only of a pure cellulose component, and a non-cellulose component may be attached to the main component cellulose. Of course, it may be constituted only by a pure cellulose component.

  The main non-cellulose component associated with the cellulose nanofibers is not particularly limited and can be appropriately selected depending on the application. For example, hemicellulose and lignin can be mentioned.

  Further, the pure cellulose component ratio in the cellulose nanofibers may be appropriately set according to the application. For example, the pure cellulose component ratio is preferably 70% by mass or more, and more preferably 80% by mass or more based on 100% by mass of the cellulose nanofibers. The upper limit of the pure cellulose component ratio can be 100% by mass. In the present specification, the cellulose ratio is a ratio of a pure cellulose component in which β-glucose molecules are linearly polymerized by a glycoside bond with respect to 100% by mass of the entire cellulose nanofiber.

  The degree of polymerization of the pure cellulose component contained in the cellulose nanofibers may be appropriately set depending on the application. For example, a cellulose component having a degree of polymerization of 500 or more, particularly 600 or more can be used. The upper limit of the degree of polymerization of the cellulose component is not particularly limited, but may be 100,000, for example.

  The crystallinity of the pure cellulose component contained in the cellulose nanofibers is also not particularly limited and is preferably 60% or more, more preferably 70% or more. The upper limit of the crystallinity of cellulose is not particularly limited, but may be 99%, for example. Examples of the crystal structure of the cellulose component include type I, type II, type III, and type IV.

  The size of the cellulose nanofibers is not particularly limited, and when the production method of the present invention described below is adopted, the diameter is preferably 4 to 100 nm and the length is preferably 500 nm or more from the viewpoint of being dispersed in the electrodeposition liquid. In the present specification, the diameter of cellulose nanofibers is a median diameter obtained by SEM observation of 50 or more randomly extracted cellulose nanofibers.

  In the present invention, the above-mentioned cellulose nanofiber can form a cellulose nanofiber layer without being subjected to a hydrophobic treatment. Therefore, the cellulose nanofibers contained in the carbon fiber reinforced plastic reinforced material of the present invention may include those that have not been subjected to the hydrophobic treatment.

  The polymer compound is not particularly limited, and examples thereof include epoxy resin, phenol resin (novolac resin, etc.), acrylic resin, nylon resin, vinyl resin, polyamide resin, polyimide resin, polyamideimide resin, polystyrene resin, polycarbonate resin. , Polyolefin resin, polyester, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone and the like. These polymer compounds may be used alone or in combination of two or more. As these polymer compounds, those having the same functional group as the thermosetting resin in the carbon fiber reinforced plastic layer are preferable in consideration of the affinity with the carbon fiber reinforced plastic layer, and among them, the epoxy resin is more preferable.

  Further, the cellulose nanofiber layer, the total amount of the cellulose nanofiber and the carbon fiber reinforced plastic is 100 mass% from the viewpoint of further improving the strength and affinity with the carbon fiber reinforced plastic layer, and the content rate of the cellulose nanofiber is 1 -20 mass% is preferable, and 2-15 mass% is more preferable.

  The thickness of such a cellulose nanofiber layer is, for example, preferably 0.001 to 500 μm, and more preferably 0.001 to 100 μm, from the viewpoint of further improving the strength and the affinity with the carbon fiber reinforced plastic layer.

(1-3) Carbon Fiber Reinforced Plastic Reinforcement Material The carbon fiber reinforced plastic reinforcement material of the present invention comprises at least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer, and at least one carbon fiber layer. At least one cellulose nanofiber layer is arranged adjacent to at least one surface of the reinforced plastic layer. As a result, even though the cellulose nanofibers are hydrophilic, the carbon fiber reinforced plastic layer having the thermosetting resin as a matrix and the cellulose nanofiber layer can be firmly bonded, as shown in the right diagram of FIG. 1. As described above, the carbon fiber reinforced plastic layer is reinforced by the cellulose nanofiber layer, and it is possible to particularly improve the impact strength.

  Such a structure of the carbon fiber reinforced plastic reinforced material of the present invention is not particularly limited as long as at least one surface of at least one carbon fiber reinforced plastic layer is arranged so that at least one cellulose nanofiber layer is adjacent. , A structure in which at least one carbon fiber reinforced plastic layer is arranged between two layers of cellulose nanofiber layers, or a structure in which carbon fiber reinforced plastic layers and cellulose nanofiber layers are alternately arranged (for example, , A carbon fiber reinforced plastic layer, a cellulose nanofiber layer, a carbon fiber reinforced plastic layer, a cellulose nanofiber layer, a carbon fiber reinforced plastic layer are formed in this order) and the like.

  As described above, according to the present invention, a carbon fiber reinforced plastic reinforced material having excellent impact strength can be obtained, and thus it becomes possible to manufacture a lightweight sports article which cannot be achieved by the conventional techniques. Specifically, it can be expected to be put to practical use in golf clubs (whole), tennis rackets (frames, shafts, etc.), baseball/softball bats (whole), badminton rackets (frames, shafts, etc.).

  For example, in a baseball/softball bat, when the ball is repeatedly hit, the surface and the carbon fiber layer are broken, so that the carbon fiber layer is thickened to improve durability. According to the present invention, a carbon fiber reinforced plastic reinforced material having excellent impact strength can be obtained, so that it is possible to reduce the carbon fiber layer (the carbon fiber reinforced plastic layer in the present invention) and reduce the weight.

  Further, the badminton racket or the like does not cause breakage in the frame and the shaft just by hitting the shuttle, but it often hits other than the shuttle by mistake, and it is necessary to secure impact strength as a product. Highly elastic carbon fiber may be used to reduce the weight of the shaft, but in that case, impact strength tends to be low, and the carbon fiber layer is thickened to improve durability. According to the present invention, a carbon fiber reinforced plastic reinforced material having excellent impact strength can be obtained, so that it is possible to reduce the carbon fiber layer (the carbon fiber reinforced plastic layer in the present invention) and reduce the weight.

  In many cases, carbon fiber reinforced plastic materials, which have been popular in the sports market, spread to aerospace and industrial applications. Therefore, in addition to the above-mentioned application to sports goods, it is possible to apply to automobile bodies and parts, aircraft bodies and parts, gate bars of expressways ETC, etc., which are being further reduced in weight.

  In Japan, where the aging society is accelerating more and more, maintaining the health of the elderly is a major issue. The elderly gradually deteriorate their physical strength and muscular strength, which makes it more difficult to move. By using the carbon fiber reinforced plastic reinforced material of the present invention for wear, shoes, orthosis, etc. that support walking of elderly people, it becomes possible to develop lightweight and durable products, and it is also useful for elderly products. Is.

  Further, the plastic reinforcing material of the present invention contains cellulose nanofibers and a polymer compound. The above-mentioned thing can be employ|adopted as a cellulose nanofiber and a high molecular compound.

  According to the plastic reinforced material of the present invention, the strength of the target polymer compound (particularly plastic) can be improved, and thus it is possible to manufacture a lightweight sports article which cannot be achieved by the conventional technology. Become. Specifically, for example, it can be expected to be put into practical use as a baseball helmet, a catcher armor, a shoe sole, a surface strengthening paint for a wooden bat, a cane for the elderly, and the like. In particular, cellulose nanofibers can be included to reinforce thin plastic membranes that are quickly destroyed by plastic alone, such as capacitor insulation and thin film circuit boards.

2. Method for producing carbon fiber reinforced plastic reinforced material and plastic reinforced material The method for producing carbon fiber reinforced plastic reinforced material of the present invention is
(1) A step of contacting cellulose nanofibers with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating, and (2) A step of forming a cellulose nanofiber layer on a carbon fiber reinforced plastic or a precursor thereof by using the dispersion liquid obtained in the step (1) and curing by heating is provided.

Further, the method for producing the plastic reinforced material of the present invention,
(1) A step of bringing the cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating material.

  So far, the present inventors have used an active electrodeposition technology in which carbon fiber and a resin are firmly bonded to each other in order to reduce the energy consumption involved in manufacturing CFRP and facilitate the curved arrangement of carbon fiber. The resin impregnation method was developed. Electrodeposition technology is a technology that has been used for coating automobiles, and polymer compounds having epoxy groups are often dispersed in the electrodeposition solution, and the polymer compounds are deposited on the surface of the object to be coated by electrophoresis. Can be made From the viewpoint of environmental protection, an electrodeposition solution using water as a solvent has been developed, and by adopting the above-mentioned method, even if the cellulose nanofibers are not subjected to hydrophobic treatment in the step (1), they can be uniformly dispersed in the electrodeposition solution. The carbon fiber reinforced plastic reinforced material and the plastic reinforced material of the present invention can be produced at low cost.

  Further, by adopting such a method, it is possible to obtain a carbon fiber reinforced plastic reinforced material with dramatically improved impact strength by using a small amount of cellulose nanofibers. Further, if such a method is adopted, a plastic reinforced material capable of improving the strength of plastic can be obtained by using a small amount of cellulose nanofiber. From this, conversely, it is possible to reduce the amount of carbon fiber reinforced plastic conventionally required for the required impact strength, which may lead to resource saving. Further, regarding the carbon fiber reinforced plastic reinforced material, since the cellulose nanofiber is lighter than the carbon fiber reinforced plastic, it may lead to weight reduction of the product, and particularly to improvement of fuel consumption in the case of a moving body (automobile, aircraft, etc.).

(2-1) Step (1)
As the polymer compound and the cellulose nanofiber, the polymer compound described in the cellulose nanofiber layer can be used. The same applies to the preferred embodiments and the like. Microgels can also be used for the polymer compounds.

  The electrodeposition liquid used in the present invention includes pigments (carbon, titanium oxide, lead silicate, aluminum phosphate, bismuth hydroxide, water) in addition to the polymer compound and solvent (cellosolve solvent, alcohol solvent, etc.). Yttrium oxide, aluminum silicate, talc, etc.), functional agents (microgel, etc.), acids (acetic acid, lactic acid, formic acid, propionic acid, sulfamic acid) and the like can also be included.

  The electrodeposition liquid used in the present invention, the above-mentioned polymer compound is dissolved or dispersed, is not particularly limited as long as it can disperse the cellulose nanofibers, considering the dispersibility of the cellulose nanofibers of the aqueous system An electrodeposition liquid is preferred. For example, in the case of attempting to electrodeposit a polymer compound that is positively (+) charged, a cation-type electrodeposition liquid can be used, and a polymer compound that is negatively (-) charged can be electrodeposited. In this case, an anion type electrodeposition liquid can be used.

  Examples of such an electrodeposition liquid include Insreed 1000, Insuleed 3000, Insuleed 4000 manufactured by Nippon Paint Co., Ltd., Elektron KG400, Elekron KG550 produced by Kansai Paint Co., Ltd., and the like. Insulind 1000 and Insulind 3000 contain phenolic resin (novolak resin) as a high molecular compound, and insulation and heat resistance can be imparted by depositing an epoxy resin. It contains an imide resin, and by precipitating a polyamide-imide resin, it is possible to impart insulation properties, heat resistance, and bending workability. Among these electrodeposition liquids, Insuleed 1000 and Insuleed 3000 can deposit the epoxy resin as described above, and the sheet-like carbon used in the step (2) in which the matrix resin is usually the epoxy resin. It is preferable from the viewpoint of compatibility with the fiber-reinforced plastic precursor.

  Further, not only the above-mentioned electrodeposition liquid, but also water-based epoxy resin and epoxy resin paint can be used in the same manner.

  The epoxy resin coating used in the present invention is not particularly limited as long as the epoxy resin is dissolved or dispersed and the cellulose nanofibers can be dispersed, but in consideration of dispersibility of the cellulose nanofibers, an aqueous epoxy resin coating is used. Is preferred.

  Examples of the above water-based epoxy resin, for example, water-based epoxy resin W2801, manufactured by Mitsubishi Chemical Co., water-based epoxy resin W2821 R70, water-based epoxy resin W3435 R67, water-based epoxy resin W8735 R70, water-based epoxy resin W1155 R55, and the like, As a water-based epoxy resin curing agent, it can be used in combination with WD11 M60 manufactured by Mitsubishi Chemical Corporation. As the epoxy resin paint, for example, Dainippon Paint Co., Ltd.'s Epoall series, Eponix series, Brasson #21, DNT universal primer, Ecocool Smile HB, aqueous floor coat primer, Epoty, Kelvin α2.5, HERCON CR-3A etc. are mentioned.

  The method of contacting the above-mentioned electrodeposition liquid, water-based epoxy resin, epoxy resin coating, etc. with cellulose nanofibers is not particularly limited. For example, a method of immersing the cellulose nanofibers in the above-mentioned electrodeposition solution, water-based epoxy resin, epoxy resin coating material, etc. (particularly by immersing and mixing the cellulose nanofiber in the above-mentioned electrodeposition solution, water-based epoxy resin, epoxy resin coating material, etc. Method) can be used, but considering that the cellulose nanofiber layer is uniformly formed on the carbon fiber reinforced plastic or its precursor in the step (2) described later, the above-mentioned electrodeposition solution, It is preferable to mix a water-based epoxy resin, an epoxy resin coating, or the like with a dispersion liquid of cellulose nanofibers. The amount of each component used at this time is not particularly limited, but can be adjusted so that the ratio of the cellulose nanofibers and the polymer compound falls within the above range. It is considered that the polymer compound (particularly, the microgel of the polymer compound) enters the network structure (=mesh) of the cellulose nanofibers and is uniformly dispersed together with the action of the polymer functional group. That is, in the present invention, the electrodeposition liquid, the water-based epoxy resin, the epoxy resin coating, etc. are not expected to be coated on the surface of a metal or the like by electrodeposition, which is originally expected, but the dispersion of cellulose nanofibers and polymer compounds. Used as a liquid.

(2-2) Step (2)
In this manner, the electrodeposition solution, the water-based epoxy resin, the epoxy resin coating or the like and the cellulose nanofibers are brought into contact with each other to disperse the cellulose nanofibers in the electrodeposition solution, the water-based epoxy resin or the epoxy resin coating, and then the carbon A cellulose nanofiber layer is formed on the fiber reinforced plastic or its precursor. At this time, the carbon fiber reinforced plastic or its precursor may be applied and dried, or the cellulose nanofiber layer may be formed into a sheet and then pressure-bonded with the carbon fiber reinforced plastic or its precursor. The molding method at this time can be performed by a conventional method.

  When applied or formed into a sheet, the electrodeposition solution and the contact material of cellulose nanofibers (especially a mixture) contain water, so it may be dried to evaporate the water before heat curing. preferable. As a result, the cellulose nanofiber layer containing the strong and uniform cellulose nanofibers and the polymer compound can be a cellulose nanofiber layer that is easy to handle. Alternatively, the obtained sheet material may be laminated on a sheet made of carbon fiber reinforced plastic or a precursor thereof and then dried to evaporate water.

  Before being dried after being formed into a sheet, it can be energized because it exists as an electrodeposition liquid, a water-based epoxy resin, an epoxy resin paint, or the like. Therefore, when the obtained sheet-like material is laminated on a sheet made of carbon fiber reinforced plastic or a precursor thereof and then energized, and then dried to evaporate water, the obtained carbon fiber of the present invention is obtained. In the material in which the reinforced plastic reinforced material is reinforced, the interfacial strength between the cellulose nanofiber layer and the carbon fiber reinforced plastic layer can be further improved.

  Next, the carbon fiber reinforced plastic on which the cellulose nanofiber layer is formed or its precursor is heat-cured. When applied and dried in the step (1), it can be heated and cured as it is. In addition, after the step (1), the obtained sheet-like material is laminated on a sheet made of carbon fiber reinforced plastic or a precursor thereof, and if necessary electricity is applied, and then dried, it is directly pressure-bonded. Then, the carbon fiber reinforced plastic or its precursor can be heat-cured. During pressure bonding and heat curing, the polymer compound in the cellulose nanofiber layer and the thermosetting resin in the sheet made of carbon fiber reinforced plastic or its precursor can be firmly bonded.

  There are no particular restrictions on the conditions for pressure bonding, and for example, a pressure of 0.01 to 30 MPa, preferably 0.1 to 5 MPa can be applied. The conditions for heat curing are also not particularly limited. For example, the heating temperature may be 120 to 250°C (particularly 140 to 200°C) and the heating time may be 0.1 to 3 hours (particularly 1 to 1.5 hours). it can.

  Thereby, the cellulose nanofiber layer and the carbon fiber reinforced plastic layer can be firmly bonded. When there are a plurality of cellulose nanofiber layers and carbon fiber reinforced plastic layers, the above steps can be repeated as many times as necessary.

  The present invention will be specifically described based on examples, but the present invention is not limited to these.

[Impact strength]
Charpy impact value based on JIS K 7077 is used as a performance index, the impact strength of carbon fiber reinforced plastic that does not compound cellulose nanofibers is 100% as existing technology, and the superiority when compounding cellulose nanofibers is quantitative. Evaluated to. Specifically, a UF type impact tester (impact velocity 3.45 m/s, 10J) manufactured by Kamijima Seisakusho Co., Ltd. was used as a tester, and the sample was 80X10X1t.

[Bending strength]
Bending test pieces were cut into 40×10 mm with a rotary cutter, and 5 pieces were produced for each CNF content. The three-point bending test was performed using a tabletop tensile compression tester (MCT-2150, manufactured by A&D Co., Ltd.), the span was 30 mm, and the load speed was constant at 10 mm/min. The load-deflection relationship data was acquired, and the rigidity and specific rigidity (=rigidity/density) were obtained from the slope of the linear portion, and the strength and specific strength (=strength/density) were obtained from the breaking load.

  In the following examples, an electrolytically active electrodeposition liquid (Insuleed 3030, epoxy resin content 20% by mass) manufactured by Nippon Paint Co., Ltd. was used as the electrodeposition liquid. In this electrodeposition liquid, a polymer compound (epoxy resin) having an epoxy group is dispersed, and an irreversible non-conductivity reaction occurs by energization, and the epoxy resin is deposited on the surface of the material to be treated. It should be noted that it does not contain substances having strong physiological activity or substances considered to be harmful to the global environment, such as an isocyanate curing agent, a blocking agent, and a harmful heavy metal catalyst.

  Cellulose nanofiber (CNF) is a dispersion of cellulose nanofiber produced from bamboo manufactured by Chuetsu Pulp Industry Co., Ltd. (cellulose content 2.5% by mass, average fiber diameter 50 nm, average fiber length 100 μm), or Daio Paper Co., Ltd. Using a dispersion of cellulose nanofibers produced from hardwood manufactured by Co., Ltd. (cellulose content 2% by mass, average fiber diameter 50 nm, average fiber length 10 μm), the prepreg is made by Toho Tenax Q-111 H1280 (resin content 25% by mass) was used.

[Example 1]
A certain amount of cellulose nanofiber dispersion liquid (Chuetsu-CNF or Daio-CNF; average fiber diameter 50 nm, average fiber length 10 μm) is mixed with an electrodeposition liquid (Insuleed 3030 manufactured by Nippon Paint Co., Ltd.) and stirred to obtain an appropriate viscosity. It came out and dispersed evenly. Therefore, it was understood that the cellulose nanofibers were sufficiently dispersed without being subjected to the hydrophobic treatment. Next, when the obtained electrodeposition solution was poured onto a Teflon (registered trademark) sheet, it spreads to have a constant thickness, and after drying, the thickness is uniform, and the cellulose nanofiber and the epoxy in the electrodeposition solution are A translucent and homogeneous sheet composed of resin was obtained. From this, it is considered that cellulose nanofibers are uniformly dispersed in the obtained sheet, and the sheet had sufficient strength and was easy to handle even when the sheet had a thickness of 0.3 mm. The appearance photograph of the obtained sheet is shown in FIG.

  Using the obtained sheet (cellulose nanofiber layer) as a cellulose nanofiber layer, pressure was applied to both front and back surfaces of 9 layers of prepreg (Q-111 H1280 manufactured by Toho Tenax), which is a precursor of carbon fiber reinforced plastic, at a pressure of 1 MPa, It was heat-cured at 150° C. for 1 hour. As a result, when the Charpy impact test was conducted, the impact strength was improved by 20 to 30% as compared with the case where cellulose nanofiber was not added. Results are shown in FIG. In addition, in FIG. 3, CNF weight fraction means the content (mass %) of the cellulose nanofibers with the total amount of CFRP and cellulose nanofibers being 100 mass %.

[Example 2]
In the same manner as in Example 1, a sheet-shaped cellulose nanofiber layer was produced.

  The obtained sheet-shaped cellulose nanofiber layer was pressure-bonded to the surface of a resin-impregnated resin by immersing carbon fiber in an electrodeposition liquid and energizing it, and heat-cured at 230° C. for 1 hour. At this time, when three layers of carbon fiber reinforced plastic are sandwiched between two layers of cellulose nanofiber layers (Surface; CNF 5% by mass or 13% by mass), carbon fiber reinforced plastic layer, cellulose nanofiber layer, carbon fiber In the case where the reinforced plastic layer, the cellulose nanofiber layer, and the carbon fiber reinforced plastic layer were laminated in this order (Laminate; CNF 5% by mass), the effect of improving the impact strength was observed. The results are shown in Fig. 4. In addition, in FIG. 4, the CNF weight fraction means the content (mass %) of cellulose inanofiber, with the total amount of CFRP and cellulose nanofibers being 100 mass %.

[Examples 3 to 6 and Comparative Examples 1 to 2]
A certain amount of cellulose nanofiber dispersion liquid (Chuetsu-CNF or Daio-CNF; average fiber diameter 50 nm, average fiber length 10 μm) is mixed with an electrodeposition liquid (Insuleed 3030 manufactured by Nippon Paint Co., Ltd.) and stirred to obtain an appropriate viscosity. It came out and dispersed evenly. Therefore, it was understood that the cellulose nanofibers were sufficiently dispersed without being subjected to the hydrophobic treatment. Next, the obtained electrodeposition liquid was applied to 5 layers of prepreg (manufactured by Mizuno), which is a precursor of carbon fiber reinforced plastic, with a blade and dried. The thermosetting conditions were 150° C., 1 hour, and atmospheric pressure atmosphere. The appearance of the cellulose nanofiber layer became transparent when dried, as shown in FIG. In addition, as shown in FIG. 6, the prepreg has a total of five layers laminated, and has a surface type (having a cellulose nanofiber layer formed on the outermost surface and the backside) and a lamination type (the outermost surface and the backside are prepregs). , A cellulose nanofiber layer was formed immediately inside them, and a central part was formed with three layers of prepreg).

  In each of the sample preparation conditions of Examples 3 to 6 and Comparative Examples 1 to 3, the mass of the prepreg was constant at 5 layers, that is, the mass of CFRP in the manufactured sample was constant. A sample was prepared by adjusting the amount of CNF and the amount of resin derived from the electrodeposition liquid in three steps. Specifically, the sample preparation conditions were as shown in Table 1. In addition, since the resin in the electrodeposition liquid is hydrophobic, CNF is repelled, and the resin amount of 2 to 4 g derived from the electrodeposition liquid shown in Table 1 is less likely to spread with respect to the area of the prepreg. The liquid and electrodeposition liquid were mixed and dispersed to make a highly viscous liquid. In particular, it was possible to evenly distribute the CNF without being repelled on the prepreg surface by rolling it thinly into a sheet.

A bending test was performed on the obtained sample. FIG. 7 shows the relationship between the CNF content and bending rigidity, and FIG. 8 shows the relationship between the CNF content and specific bending rigidity (=bending rigidity/sample density). The flexural rigidity and specific flexural rigidity tended to increase with the increase of CNF content. In addition, regarding the laminated structure, the increase tendency was more remarkable in the Lamination type than in the Surface type. On the other hand, FIG. 9 shows the relationship between CNF content and bending strength, and FIG. 10 shows the relationship between CNF content and specific bending strength (=bending strength/sample density). Bending strength and specific bending strength increased with the increase of CNF content. Regarding the laminated structure, the Lamination type showed a marked increase tendency, and showed a strong linearity as can be seen from the regression coefficient (R ² value). In particular, the specific strength was R ² =0.98. 7 to 10, each plot is a measurement of a sample prepared by appropriately changing conditions such as CNF content and resin amount.

  Next, in order to confirm the infiltration of the CNF and the electrodeposition liquid-derived resin layer into the surface resin layer of the prepreg, for the sample of Example 5, using a digital microscope (VHX-1000, manufactured by Keyence Corporation), the prepreg The interface between the CNF and the resin layer derived from the electrodeposition liquid was observed.

  FIG. 11 shows a photograph of the interface between the prepreg and the CNF and the resin layer derived from the electrodeposition liquid. It was possible to confirm the infiltration of the CNF and the resin layer derived from the electrodeposition liquid into the surface resin layer of the prepreg (Baffer Layer shown in FIG. 11).

  Next, a surface type sample (Surface 2) was prepared in the same manner as above except that the curing temperature was 170° C. instead of 150° C., and the bending test was similarly performed. FIG. 12 shows the relationship between the CNF content and the bending rigidity, and the relationship between the CNF content and the specific bending rigidity (=bending rigidity/sample density). Even in the sample at 170℃, the flexural rigidity and the specific flexural rigidity tended to increase as the CNF content increased. In addition, the curing tendency at 170 ℃ was more remarkable than that at 150 ℃. On the other hand, FIG. 13 shows the relationship between the CNF content and the bending strength, and the relationship between the CNF content and the specific bending strength (=bending strength/sample density). The bending strength and specific bending strength also increased with the increase of CNF content in the sample at 170℃. In addition, the curing tendency at 170 ℃ was more remarkable than that at 150 ℃.

Claims (11)

At least one carbon fiber reinforced plastic layer, and at least one cellulose nanofiber layer is provided,
At least one surface of at least one carbon fiber reinforced plastic layer, at least one cellulose nanofiber layer is arranged so as to be adjacent,
The carbon fiber reinforced plastic layer contains carbon fiber reinforced plastic,
The cellulose nanofiber layer is a carbon fiber reinforced plastic reinforced material containing cellulose nanofibers and a polymer compound. The carbon fiber reinforced plastic reinforced material according to claim 1, wherein the thermosetting resin which is a matrix of the carbon fiber reinforced plastic is an epoxy resin. The carbon fiber reinforced plastic reinforced material according to claim 1 or 2, wherein the polymer compound in the cellulose nanofiber layer is an epoxy resin. The carbon fiber reinforced plastic reinforced material according to any one of claims 1 to 3, wherein at least one carbon fiber reinforced plastic layer is disposed between two layers of the cellulose nanofiber layers. The carbon fiber reinforced plastic reinforced material according to any one of claims 1 to 3, wherein the carbon fiber reinforced plastic layers and the cellulose nanofiber layers are alternately arranged. A plastic reinforced material including cellulose nanofibers and a polymer compound. It is a manufacturing method of the carbon fiber reinforced plastic reinforced material according to any one of claims 1 to 5,
(1) A step of contacting cellulose nanofibers with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating, and (2) A production method comprising a step of forming a cellulose nanofiber layer on a carbon fiber reinforced plastic or a precursor thereof by using the dispersion liquid obtained in the step (1) and heating and curing the layer. The production method according to claim 7, wherein the carbon fiber reinforced plastic or its precursor contains an epoxy resin as a matrix resin. The manufacturing method according to claim 7 or 8, wherein the carbon fiber reinforced plastic or the precursor thereof is a carbon fiber reinforced plastic or a carbon fiber prepreg. A method of manufacturing a plastic-reinforced material according to claim 6,
(1) A production method comprising a step of bringing cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition liquid in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating material. The production method according to claim 7, wherein the polymer compound in the electrodeposition liquid is an epoxy resin.

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