WO2019221155A1

WO2019221155A1 - Material for reinforcing carbon-fiber-reinforced plastic and material for reinforcing plastic

Info

Publication number: WO2019221155A1
Application number: PCT/JP2019/019228
Authority: WO
Inventors: 一彰片桐; 俊彦奥村; 真平山口; 卓哉永廣; 園美川北; 粂　和弘
Original assignee: 地方独立行政法人大阪産業技術研究所; 美津濃株式会社
Priority date: 2018-05-15
Filing date: 2019-05-15
Publication date: 2019-11-21
Also published as: JP6664732B1; JPWO2019221155A1

Abstract

This material for reinforcing carbon-fiber-reinforced plastic is lightweight, has excellent impact strength, and includes at least one carbon-fiber-reinforced plastic layer and at least one cellulose nanofiber layer. At least one cellulose nanofiber layer is adjacently disposed on at least one surface of at least one carbon-fiber-reinforced plastic layer. The carbon-fiber-reinforced plastic layer contains carbon-fiber-reinforced plastic. The cellulose nanofiber layer contains cellulose nanofibers and a polymer compound. This material for reinforcing another material contains cellulose nanofibers and a polymer compound, and is used for reinforcing another material (such as a hydrophobic resin).

Description

Carbon fiber reinforced plastic reinforced material and plastic reinforced material

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

In sporting goods, since “lighter and stronger materials” are always required, many products using carbon fiber reinforced plastic (hereinafter sometimes referred to as “CFRP”) are manufactured. There is a great need for CFRP with high impact resistance, such as softball bats and tennis rackets, and there is a great potential demand. Therefore, research on the modification of matrix resins and the addition of fillers with excellent strength has been actively conducted. .

However, CFRP has light weight and high strength. However, since resin is used as a base material, the impact strength is practically one of the drawbacks due to the low impact strength of the resin. As shown in FIG. The resin on the surface cracks and leads to destruction. Actually, gravel and the like often collide and the surface is cracked. For this reason, one of the drawbacks of CFRP is the impact strength. For this reason, high-strength matrix resins have been studied, but there have been no reports of significant performance improvements.

By the way, cellulose nanofiber (hereinafter sometimes referred to as “CNF”) can be manufactured from wood and is lightweight yet excellent in strength. Therefore, as a method to improve the impact strength of CFRP, CNF is mixed with matrix resin. Increasing the impact strength of CFRP is being studied. Since CNF is a biomass resource derived from plant fiber, it can realize a sustainable recycling society without increasing the carbon dioxide causing global warming. However, since CNF has strong hydrogen bonds between the molecular chains, it cannot be dissolved in common organic solvents and is hydrophilic, so it is difficult to disperse CFRP in the matrix resin. It is indispensable to perform a hydrophobic treatment (for example, chemical modification 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 hydrophobic treatment. Examples of such a hydrophobizing treatment include a method in which CNF is added together with a chemical and reacted by heating. In this case, for example, the heating temperature is 120 ° C., the treatment time is 1 hour, 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (FAS13) or the like is used. Such a hydrophobization treatment is necessary, which increases costs, hinders the practical application of CNF complexing to CFRP, and even increases the strength of CFRP by the method of hydrophobization treatment. It has not reached.

Thus, the 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 the matrix resin of CFRP, and an appropriate method for improving the impact strength of CFRP has not been found. The above problems are related to application to CFRP, but the same problems exist when CNF is applied to other materials.

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

As a result of intensive investigations in view of the above-mentioned object, it is possible to arrange a carbon fiber reinforced plastic layer containing a carbon fiber reinforced plastic and a cellulose nanofiber layer containing a cellulose nanofiber and a polymer compound so that they are adjacent to each other. It has been found that a carbon fiber reinforced plastic reinforced material that is lightweight and excellent in impact strength can be obtained at low cost without applying a chemical treatment. Although a method of mixing CNF into a CFRP matrix resin has been proposed, a method of laminating CNF as a sheet on the surface of CFRP has not been studied. The inventors have also found that a cellulose nanofiber layer containing cellulose nanofibers and a polymer compound can be improved in strength by being applied to materials other than carbon fibers. The present inventors have further studied and completed the present invention. That is, the present invention includes the following configurations.
Item 1. Comprising at least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer;
At least one cellulose nanofiber layer is disposed adjacent to at least one surface of at least one carbon fiber reinforced plastic layer,
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 nanofiber and a polymer compound.
Item 2. Item 2. The carbon fiber reinforced plastic reinforcing material according to Item 1, wherein the thermosetting resin that is a 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 disposed between the two 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 layer and the cellulose nanofiber layer are alternately arranged.
Item 6. A plastic reinforced material comprising cellulose nanofibers and a polymer compound.
Item 7. Item 6. A method for producing a carbon fiber reinforced plastic reinforced material according to any one of Items 1 to 5,
(1) a step of bringing cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition solution in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating; A manufacturing method provided with the process of forming and heating-hardening a cellulose nanofiber layer on a carbon fiber reinforced plastic or its precursor using the dispersion liquid obtained at the process (1).
Item 8. Item 8. The method according to Item 7, wherein the carbon fiber reinforced plastic or a precursor thereof 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 a precursor thereof is a carbon fiber reinforced plastic or a carbon fiber prepreg.
Item 10. Item 7. A method for producing 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 paint.
Item 11. Item 11. The production 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 light in weight and excellent in impact strength can be obtained at low cost without applying a hydrophobic treatment. Further, according to the present invention, a material for reinforcing a plastic (such as a hydrophobic resin) can be obtained.

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

In the present specification, “containing” is a concept including any of “comprise”, “consistently of”, and “consist of”. In this specification, when the numerical range is indicated by “A to B”, it means A or more and B or less.

In this specification, “carbon fiber reinforced plastic reinforced material” means a composite material reinforced with carbon fiber reinforced plastic. The “plastic reinforced material” means a material reinforced with plastic.

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 comprises: All of them contain carbon fiber reinforced plastic, and all of the cellulose nanofiber layers contain cellulose nanofibers and polymer compounds, and at least one of the carbon fiber reinforced plastic layers contains the cellulose. The nanofiber layer is disposed adjacent to at least one layer. 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, impact strength can be dramatically improved by using cellulose nanofibers. On the contrary, it is possible to reduce the amount of carbon fiber reinforced plastic that has been conventionally required with respect to 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, particularly in the case of mobile bodies (automobiles, aircrafts, etc.), which can lead to improved fuel economy. Moreover, it is possible to improve the strength of plastics by using cellulose nanofibers.

(1-1) Carbon Fiber Reinforced Plastic Layer In the present invention, the carbon fiber reinforced plastic layer contains a carbon fiber reinforced plastic.

This carbon fiber reinforced plastic usually employs an autoclave method in which a plurality of prepregs impregnated with a thermosetting resin in carbon fiber and semi-dried are stacked and compressed and heated to cure the thermosetting resin. ing. That is, it has a configuration in which carbon fibers are dispersed in a thermosetting resin as 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). Examples thereof include a planar carbon fiber sheet, a pipe-shaped carbon fiber sheet, a wing-shaped carbon fiber sheet, an L-shaped carbon fiber sheet, and an H-shaped carbon fiber sheet. In particular, not only a carbon fiber material in which carbon fibers are arranged in a straight line 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 more sufficiently depositing a polymer compound and obtaining a carbon fiber prepreg. A known or commercially available product can be used as such a carbon fiber material.

Moreover, there is no restriction | limiting in particular as a thermosetting resin, For example, an epoxy resin, a phenol resin (novolak resin etc.), an acrylic resin, a nylon resin, a vinyl resin, a polyamide resin, a polyimide resin, a polyamideimide resin, a polystyrene resin, a polycarbonate Examples thereof include resins, polyolefin resins, polyesters, polyethylene terephthalate, polyethylene naphthalate, and polyethersulfone. These thermosetting resins can be used alone or in combination of two or more. These thermosetting resins are preferably those having the same functional group as the polymer compound in the cellulose nanofiber layer in consideration of the affinity with the cellulose nanofiber layer described later, and more preferably an epoxy resin.

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

In addition, the carbon fiber reinforced plastic layer further improves the strength and from the viewpoint of affinity with the cellulose nanofiber layer, the total amount of carbon fiber and thermosetting resin is 100% by mass, and the carbon fiber content is 20 to 20%. 70% by volume is preferable, and 25 to 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 nanofiber and a polymer compound.

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

Examples of plant-derived cellulose include hardwood-derived cellulose (eucalyptus, poplar, etc.), conifer-derived cellulose (pine, fir, cedar, cypress, etc.), herbaceous cellulose (wara, bagasse, reed, kenaf, abaca, sisal, etc.) , And seed hair fibers (such as cotton). The pulp used as a raw material may be mechanical pulp obtained by mechanically treating wood chips, chemical pulp obtained by chemically removing non-cellulose components from wood chips, and dissolution obtained by removing non-cellulose components and purifying them. Pulp may be used.

In addition, cellulose derived from animals such as sea squirts, cellulose derived from bacteria such as nata deco, and the like can also be used. Moreover, such cellulose does not necessarily need to be comprised only from a pure cellulose component, The non-cellulose component may accompany the cellulose which is a main component. Of course, you may be comprised only with the pure cellulose component.

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

Moreover, the pure cellulose component ratio in the cellulose nanofibers may be set as appropriate 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 in 100% by mass of 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 glycosidic bonds with respect to 100% by mass of the whole cellulose nanofiber.

What is necessary is just to set suitably also about the polymerization degree of the pure cellulose component contained in a cellulose nanofiber according to a use. For example, a cellulose component having a polymerization degree 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 can be, for example, 100,000.

The crystallinity of the pure cellulose component contained in the cellulose nanofiber is 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 can 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 nanofiber is not particularly limited, and when adopting the production method of the present invention described later, the diameter is preferably 4 to 100 nm and the length is preferably 500 nm or more from the viewpoint of dispersion in the electrodeposition solution. In the present specification, the diameter of the cellulose nanofiber 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. For this reason, the cellulose nanofiber contained in the carbon fiber reinforced plastic reinforced material of the present invention can include those not subjected to a hydrophobic treatment.

Moreover, there is no restriction | limiting in particular as a high molecular compound, For example, an epoxy resin, a phenol resin (novolak resin etc.), an acrylic resin, a nylon resin, a vinyl resin, a polyamide resin, a polyimide resin, a polyamideimide resin, a polystyrene resin, a polycarbonate resin , Polyolefin resin, polyester, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone and the like. These polymer compounds can be used alone or in combination of two or more. These polymer compounds are preferably those having the same functional group as the thermosetting resin in the carbon fiber reinforced plastic layer in consideration of the affinity with the carbon fiber reinforced plastic layer, and more preferably an epoxy resin.

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

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

(1-3) Carbon Fiber Reinforced Plastic Reinforcing Material The carbon fiber reinforced plastic reinforced material of the present invention includes at least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer, and at least one carbon fiber. At least one cellulose nanofiber layer is disposed adjacent to at least one side of the reinforced plastic layer. As a result, although the cellulose nanofibers are hydrophilic, the carbon fiber reinforced plastic layer using the thermosetting resin as a matrix and the cellulose nanofiber layer can be firmly bonded. As described above, the carbon fiber reinforced plastic layer is reinforced by the cellulose nanofiber layer, and the impact strength can be particularly improved.

The configuration of the carbon fiber reinforced plastic reinforced material of the present invention is not particularly limited as long as at least one cellulose nanofiber layer is disposed adjacent to at least one surface of at least one carbon fiber reinforced plastic layer. A structure in which at least one carbon fiber reinforced plastic layer is disposed between two cellulose nanofiber layers, or a structure in which carbon fiber reinforced plastic layers and cellulose nanofiber layers are alternately disposed (for example, It is possible to employ a structure in which a carbon fiber reinforced plastic layer, a cellulose nanofiber layer, a carbon fiber reinforced plastic layer, a cellulose nanofiber layer, and a carbon fiber reinforced plastic layer are formed in this order.

Thus, according to the present invention, since a carbon fiber reinforced plastic reinforced material having excellent impact strength can be obtained, it is possible to manufacture a lighter sports equipment that could not be achieved by conventional techniques. Specifically, practical application in golf clubs (entire), tennis rackets (frames, shafts, etc.), baseball / softball bats (overalls), badminton rackets (frames, shafts, etc.) can be expected.

For example, baseball / softball bats have a thick carbon fiber layer to increase durability because the surface and the carbon fiber layer break when repeatedly hitting the ball. According to the present invention, since a carbon fiber reinforced plastic reinforced material excellent in impact strength can be obtained, it is possible to reduce the weight by reducing the number of carbon fiber layers (carbon fiber reinforced plastic layer in the present invention).

In addition, although badminton rackets and the like do not cause breakage in the frame and shaft only by hitting the shuttle, they often hit other than the shuttle accidentally, and it is necessary to ensure impact strength as a product. Further, in order to reduce the weight of the shaft, a highly elastic carbon fiber may be used. In this case, the impact strength tends to be low, and the carbon fiber layer is thickened to increase the durability. According to the present invention, since a carbon fiber reinforced plastic reinforced material excellent in impact strength can be obtained, it is possible to reduce the weight by reducing the number of carbon fiber layers (carbon fiber reinforced plastic layer in the present invention).

Carbon fiber reinforced plastic materials are often used in aerospace and industrial applications because of the widespread use in the sports market. For this reason, in addition to the development of applications for sports equipment as described above, it can be applied to automobile bodies and parts, aircraft bodies and parts, aircraft main bars and parts, and highway ETC gate bars that are being further reduced in weight.

In Japan, where the aging society is increasingly accelerated, it is a major issue to maintain the health of the elderly. Elderly people gradually lose their physical strength and muscle strength, leading to a situation where movement itself becomes more difficult. Using the carbon fiber reinforced plastic reinforced material of the present invention for wear, shoes, orthoses, etc. that support the elderly's walking makes it possible to develop lightweight and highly durable products that are also useful for products for the elderly It is.

Further, the plastic reinforcing material of the present invention contains cellulose nanofibers and a polymer compound. What was mentioned above is employable about 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 (especially plastic) can be improved, so that it is possible to manufacture lightweight sports equipment that could not be achieved by conventional techniques. Become. Specifically, for example, it can be expected to be put to practical use in baseball helmets, catcher armor, shoe soles, wooden bat surface-enhanced paint, and canes for elderly people. In particular, cellulose nanofibers can be included to reinforce thin plastic films, such as capacitor insulation and thin film circuit boards, that can be easily broken by plastic alone.

2. Carbon fiber reinforced plastic reinforced material and method for producing plastic reinforced material
(1) a step of bringing cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition solution in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating; Using the dispersion obtained in the step (1), a step of forming a cellulose nanofiber layer on a carbon fiber reinforced plastic or a precursor thereof and curing it by heating is provided.

Moreover, the method for producing the plastic reinforced material of the present invention includes:
(1) 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 paint.

In the past, the present inventors have used an active electrodeposition technique in which carbon fibers and resin are firmly bonded to reduce energy consumption for manufacturing CFRP and facilitate curve arrangement of carbon fibers. We have been developing a resin impregnation method. Electrodeposition technology is a technology that has been used in automobile coating, and polymer compounds with epoxy groups are often dispersed in the electrodeposition solution, and the polymer compound is deposited on the surface of the object by electrophoresis. Can be made. From the viewpoint of environmental protection, an electrodeposition solution using water as a solvent has been developed. If the above-mentioned method is adopted, the cellulose nanofibers can be uniformly dispersed in the electrodeposition solution in the step (1) without being hydrophobized. The carbon fiber reinforced plastic reinforced material and the plastic reinforced material of the present invention can be produced at low cost.

Further, if such a method is adopted, it is possible to obtain a carbon fiber reinforced plastic reinforced material having dramatically improved impact strength by using a small amount of cellulose nanofibers. Moreover, if such a method is employ | adopted, the plastic reinforcement material which can improve the intensity | strength of a plastic can also be obtained by using a small amount of cellulose nanofiber. On the contrary, it is possible to reduce the amount of carbon fiber reinforced plastic that has been conventionally required for the required impact strength, and it can also lead to resource saving. As for carbon fiber reinforced plastic reinforced materials, since cellulose nanofibers are lighter than carbon fiber reinforced plastics, the weight of products can be reduced, and in particular in the case of mobile objects (automobiles, aircrafts, etc.), this can lead to improved fuel consumption.

(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 preferred embodiments are also the same. In addition, about a high molecular compound, a microgel can also be employ | adopted.

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 is not particularly limited as long as the above-described polymer compound is dissolved or dispersed, and the cellulose nanofibers can be dispersed. An electrodeposition solution is preferred. For example, in the case of electrodepositing a polymer compound charged positively (+), a cationic electrodeposition solution can be used, and a polymer compound charged negatively (−) is electrodeposited. In some cases, an anionic electrodeposition solution can be used.

Examples of such an electrodeposition liquid include Insuled 1000, Insuled 3000, Insuled 4000, and Eleclon KG400 and Elklon KG550 manufactured by Kansai Paint Co., Ltd. Insuled 1000 and Insuled 3000 contain a phenolic resin (novolac resin) as a polymer compound, and can impart insulation and heat resistance by precipitating an epoxy resin. Insuled 4000 is a polyamide. An imide resin is included, and by precipitating a polyamide-imide resin, insulation, heat resistance, and bending workability can be imparted. Of these electrodeposition solutions, Insuled 1000 and Insuled 3000 can deposit an epoxy resin as described above, and are usually sheet-like carbon used in step (2) in which the matrix resin is an epoxy resin. It is preferable from the viewpoint of affinity with the fiber reinforced plastic precursor.

Moreover, it is not limited only to the above-mentioned electrodeposition liquid, and a water-based epoxy resin or an epoxy resin paint can also be used in the same manner.

The epoxy resin paint 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 considering the dispersibility of the cellulose nanofibers, an aqueous epoxy resin paint is used. Is preferred.

Examples of the water-based epoxy resin include water-based epoxy resin W2801, water-based epoxy resin W2821 R70, water-based epoxy resin W3435 R67, water-based epoxy resin W8735 R70, water-based epoxy resin W1155 R55, etc., manufactured by Mitsubishi Chemical Corporation. As a water-based epoxy resin curing agent, it can be used in combination with WD11 M60 manufactured by Mitsubishi Chemical Corporation. In addition, as an epoxy resin paint, for example, Epoor series, Eponic series, Brassnon # 21, DNT universal primer, Eco Cool Smile HB, aqueous floor coat primer, Epoti, Kelvin α2.5, manufactured by Dainippon Paint Co., Ltd. HERCON CR-3A etc.

The contact method between the above-mentioned electrodeposition liquid, water-based epoxy resin, epoxy resin paint, etc. and cellulose nanofiber is not particularly limited. For example, a method of immersing cellulose nanofibers in the above-described electrodeposition liquid, water-based epoxy resin, epoxy resin paint, etc. (particularly, cellulose nanofibers are immersed in the above-mentioned electrodeposition liquid, water-based epoxy resin, epoxy resin paint, etc. and mixed) In consideration of the uniform formation of the cellulose nanofiber layer on the carbon fiber reinforced plastic or its precursor in the step (2) described later, the electrodeposition liquid described above, It is preferable to mix a water-based epoxy resin, an epoxy resin paint or the like with a dispersion of cellulose nanofibers. Although the usage-amount of each component in this case is not restrict | limited in particular, it can adjust so that the ratio of a cellulose nanofiber and a high molecular compound may be in an above-described range. It is considered that a polymer compound (particularly, a microgel of a polymer compound) enters the cellulose nanofiber network structure (= network) and is uniformly dispersed in combination with the action of the polymer functional group. In other words, in the present invention, the electrodeposition liquid, the water-based epoxy resin, the epoxy resin paint, etc. are not expected to be coated on the surface of metal or the like by electrodeposition as expected, but the dispersion of the cellulose nanofiber and the polymer compound It is used as a liquid.

(2-2) Step (2)
As described above, after the cellulose nanofibers are dispersed in the electrodeposition liquid, the water-based epoxy resin, the epoxy resin paint, etc. by bringing the electrodeposition liquid, the water-based epoxy resin, the epoxy resin paint, etc. into contact with the cellulose nanofiber, 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 a precursor thereof may be applied and dried, or the cellulose nanofiber layer may be formed into a sheet and then pressed with the carbon fiber reinforced plastic or a precursor thereof. The molding method at this time can be performed by a conventional method.

In an applied state or a sheet-shaped state, the contact material (particularly the mixture) of the electrodeposition liquid and the cellulose nanofibers contains water, so it can be dried to evaporate the water before heat curing. preferable. Thereby, the cellulose nanofiber layer containing a uniform and strong cellulose nanofiber and a polymer compound can be made into a cellulose nanofiber layer that is easy to handle. Alternatively, the obtained sheet-like material may be laminated on a sheet made of carbon fiber reinforced plastic or a precursor thereof and then dried to evaporate moisture.

It should be noted that, 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. For this reason, when the obtained sheet-like material is laminated on a sheet made of carbon fiber reinforced plastic or its precursor and then energized, and then dried to evaporate the water, the resulting carbon fiber of the present invention is obtained. In the material reinforced with the reinforced plastic reinforced material, the interface strength between the cellulose nanofiber layer and the carbon fiber reinforced plastic layer can be further improved.

Next, the carbon fiber reinforced plastic or the precursor thereof on which the cellulose nanofiber layer is formed is cured by heating. When applied and dried in the step (1), it can be cured by heating 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 then energized as necessary, and then dried as it is. Then, the carbon fiber reinforced plastic or its precursor can be heat-cured. When the pressure bonding and heat curing are performed, 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 limitations on the conditions during crimping, 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 not particularly limited. For example, the heating temperature may be 120 to 250 ° C. (especially 140 to 200 ° C.), and the heating time may be 0.1 to 3 hours (especially 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 examples.

[Impact strength]
Using Charpy impact value based on JIS K 7077 as a performance index, the impact strength of carbon fiber reinforced plastic that does not combine cellulose nanofiber is assumed to be 100% as existing technology, and the superiority when combining cellulose nanofiber is quantitative Evaluated. Specifically, a UF impact tester manufactured by Ueshima Seisakusho Co., Ltd. (impact speed: 3.45 m / s, 10 J) was used as the tester, and the sample was 80 × 10 × 1t.

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

In the following examples, an electroactive electrodeposition liquid (Insuleed 3030, epoxy resin content 20 mass%) manufactured by Nippon Paint Co., Ltd. was used as the electrodeposition liquid. In this electrodeposition solution, a polymer compound (epoxy resin) having an epoxy group is dispersed, and an irreversible deconducting reaction occurs by energization, and the epoxy resin is deposited on the surface of the material to be treated. It does not contain any physiologically active substances such as isocyanate curing agents, blocking agents, harmful heavy metal catalysts, or substances that are considered to cause harm to the global environment.

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

[Example 1]
When a predetermined amount of cellulose nanofiber dispersion (Chuetsu-CNF or Daio-CNF; average fiber diameter 50 nm, average fiber length 10 μm) is mixed in the electrodeposition liquid (Insuleed 3030 manufactured by Nippon Paint Co., Ltd.) Out and evenly dispersed. For this reason, it was understood that the cellulose nanofibers were sufficiently dispersed without being subjected to a hydrophobic treatment. Next, when the obtained electrodeposition liquid is 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 liquid It became a translucent and homogeneous sheet made of resin. From this, it was considered that the cellulose nanofibers were uniformly dispersed in the obtained sheet, and even with a sheet thickness of 0.3 mm, the strength was sufficient and handling was easy. An appearance photograph of the obtained sheet is shown in FIG.

The obtained sheet (cellulose nanofiber layer) is used as a cellulose nanofiber layer, and is pressure-bonded to the front and back surfaces of 9 layers of prepreg (Q-111 H1280 made by Toho Tenax), a precursor of carbon fiber reinforced plastic, at a pressure of 1 MPa. Heat curing was performed at 150 ° C. for 1 hour. As a result, a Charpy impact test was conducted, and an impact strength improvement of 20 to 30% was observed compared to the case where cellulose nanofiber was not added. The results are shown in FIG. In FIG. 3, CNF weight fraction means the content (mass%) of cellulose nanofibers, where the total amount of CFRP and cellulose nanofibers is 100 mass%.

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

The obtained sheet-like cellulose nanofiber layer was press-bonded at a pressure of 1 MPa on the surface of the resin-impregnated resin impregnated with carbon fiber in an electrodeposition solution, 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 mass% or 13 mass%), carbon fiber reinforced plastic layer, cellulose nanofiber layer, carbon fiber When the reinforced plastic layer, the cellulose nanofiber layer, and the carbon fiber reinforced plastic layer were laminated in this order (Laminate; CNF 5 mass%), an effect of improving the impact strength was observed. The results are shown in FIG. In FIG. 4, CNF weight fraction means the content (mass%) of cellulose inanofiber, where the total amount of CFRP and cellulose nanofiber is 100 mass%.

[Examples 3-6 and Comparative Examples 1-2]
When a predetermined amount of cellulose nanofiber dispersion (Chuetsu-CNF or Daio-CNF; average fiber diameter 50 nm, average fiber length 10 μm) is mixed in the electrodeposition liquid (Insuleed 3030 manufactured by Nippon Paint Co., Ltd.) Out and evenly dispersed. For this reason, it was understood that the cellulose nanofibers were sufficiently dispersed without being subjected to a hydrophobic treatment. Next, the obtained electrodeposition liquid was applied with a blade to 5 layers of prepreg (manufactured by Mizuno), which is a precursor of carbon fiber reinforced plastic, and dried. The thermosetting conditions were 150 ° C., 1 hour, and atmospheric pressure. 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 5 layers, Surface type (cellulosic nanofiber layer formed on the outermost surface and outermost surface) and Lamination type (outermost surface and outermost surface are prepregs). A cellulose nanofiber layer was formed immediately inside them, and a prepreg of three layers was formed in the center).

The sample preparation conditions of Examples 3 to 6 and Comparative Examples 1 to 3 were such that the mass of the prepreg was constant in 5 layers, that is, the mass of CFRP in the sample after production was constant. In addition, samples were prepared by adjusting the amount of CNF and the amount of resin derived from the electrodeposition solution in three stages. 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. In addition, the amount of resin derived from the electrodeposition liquid shown in Table 1 is 2-4 g, and it is difficult to spread slightly 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 uniformly distribute CNF without being repelled on the surface of the prepreg by thinly extending the sheet.

The obtained sample was subjected to a bending test. FIG. 7 shows the relationship between the CNF content and the bending stiffness, and FIG. 8 shows the relationship between the CNF content and the specific bending stiffness (= bending stiffness / sample density). With increasing CNF content, bending stiffness and specific bending stiffness showed an increasing trend. Regarding the laminated structure, the increasing 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). With increasing CNF content, bending strength and specific bending strength increased. Regarding the layered structure, the Lamination type showed a greater tendency to increase 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 obtained by measuring 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 electrodeposition liquid-derived resin layer into the surface resin layer of the prepreg, the prepreg was used for the sample of Example 5 using a digital microscope (VHX-1000, manufactured by Keyence Corporation). And the interface between CNF and the electrodeposition liquid-derived resin layer were observed.

Fig. 11 shows a photograph of the interface between the prepreg, CNF, and electrodeposition liquid-derived resin layer. Infiltration of the CNF and electrodeposition liquid-derived resin layer into the surface resin layer of the prepreg could be confirmed (Baffer® Layer shown in FIG. 11).

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

Claims

Comprising at least one carbon fiber reinforced plastic layer and at least one cellulose nanofiber layer;
At least one cellulose nanofiber layer is disposed adjacent to at least one surface of at least one carbon fiber reinforced plastic layer,
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 nanofiber and a polymer compound.
The carbon fiber reinforced plastic reinforcing material according to claim 1, wherein the thermosetting resin that 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 the two 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 layer and the cellulose nanofiber layer are alternately arranged.
A plastic reinforced material comprising cellulose nanofibers and a polymer compound.
A method for producing a carbon fiber reinforced plastic reinforced material according to any one of claims 1 to 5,
(1) a step of bringing cellulose nanofibers into contact with at least one selected from the group consisting of an electrodeposition solution in which a polymer compound is dissolved or dispersed, an aqueous epoxy resin, and an epoxy resin coating; A manufacturing method provided with the process of forming and heating-hardening a cellulose nanofiber layer on a carbon fiber reinforced plastic or its precursor using the dispersion liquid obtained at the process (1).
The production method according to claim 7, wherein the carbon fiber reinforced plastic or a precursor thereof contains an epoxy resin as a matrix resin.
The manufacturing method of Claim 7 or 8 whose carbon fiber reinforced plastic or its precursor is a carbon fiber reinforced plastic or a carbon fiber prepreg.
A method for producing 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 paint.
The production method according to any one of claims 7 to 10, wherein the polymer compound in the electrodeposition liquid is an epoxy resin.