JP2024022869A - Composite member and method for producing composite member - Google Patents

Abstract

To provide a composite member that breaks in a ductile manner, and a method for producing the same.SOLUTION: A composite member includes matrix material, and flake-shaped particles dispersed within the matrix material. The composite member has a bending strength in the range of 100-250 MPa, a flexural modulus in the range of 10-40 GPa, and a maximum bending strain in the range of 1-2%.SELECTED DRAWING: Figure 3

Description

Application for application of Article 30, Paragraph 2 of the Patent Act 1. Publication address: (1) https://member. spsj. or. jp/convention/tohron2021/index. php? id=2L12 (2) https://member. spsj. or. jp/convention/tohron2021/download_pdf. php? id=2L12 Release date: August 18, 2021 2. Research meeting name: 70th Polymer Symposium Date: September 7, 2021 (held online)

The present invention relates to a composite member and a method for manufacturing the composite member.

Composite materials whose strength is improved by adding fillers such as flake particles to resin are widely used as materials for various structures.

For example, in Patent Document 1, unfired mica is pulverized to obtain mica scale pieces, a slurry containing the pieces is made into paper, a composite mica material obtained is impregnated or coated with a thermosetting resin composition, and then heated. It is described that molding under pressure produces a composite mica product with improved flexural modulus and flexural strength.

Patent Document 2 discloses that a composite resin member is manufactured by orienting a mixture of a resin having a viscosity within a predetermined range at room temperature and flaky inorganic particles, and that the member manufactured in this manner has a high bendability. It is described that it has elastic modulus and bending strength.

Japanese Unexamined Patent Publication No. 57-82598 JP 2021-88149 Publication

It is desirable that a part of a member used for a vehicle outer panel, a fuel cell case, or the like not fall off when it is destroyed. However, according to the inventors' extensive studies, conventional composite members in which a filler is added to a matrix material such as a resin undergo brittle fracture, so that a portion of the composite member easily becomes fragments and falls off. If the composite member undergoes ductile failure, it is possible to suppress the falling of pieces.

Therefore, a composite member that undergoes ductile failure and a method for manufacturing the same are provided.

Aspects of the present disclosure include the following.
[1]
A composite member comprising a matrix material and flaky particles dispersed in the matrix material,
A composite member having a bending strength in the range of 100-250 MPa, a bending modulus in the range of 10-40 GPa, and a maximum bending strain in the range of 1-2%.
[2]
The composite member according to aspect 1, wherein the flaky particles are contained in an amount of 5 to 99% by volume based on the total volume of the composite member.
[3]
The composite member according to aspect 1, wherein the flake-like particles are contained in an amount of 50 to 99% by volume based on the total volume of the composite member.
[4]
Composite member according to any one of aspects 1 to 3, having a fracture toughness value in the range of 300 to 500 J/m ³ .
[5]
The composite member according to any one of aspects 1 to 4, wherein the flaky particles are mica particles.
[6]
The composite member according to any one of aspects 1 to 5, wherein the matrix material is a cured product of an epoxy resin composition.
[7]
7. The composite member according to aspect 6, wherein the epoxy resin composition includes a bisphenol A epoxy resin and poly(propylene glycol) diglycidyl ether.
[8]
producing a paper product containing flaky particles;
Impregnating the paper product with a curable resin composition;
Curing the curable resin composition under predetermined conditions;
A method for manufacturing a composite member, comprising:
The method, wherein the curable resin composition is a composition that forms a cured product having a tensile strength within a range of 1 to 30 MPa when cured under the predetermined conditions.
[9]
9. The method according to aspect 8, wherein the curable resin composition comprises an epoxy resin.
[10]
9. The method of aspect 8, wherein the curable resin composition comprises a bisphenol A epoxy resin and poly(propylene glycol) diglycidyl ether.
[11]
preparing a suspension comprising a fibrous or particulate thermoplastic material and flake particles;
making a paper product containing the thermoplastic material and the flaky particles by paper-making the suspension;
Hot-press molding the paper product at a temperature equal to or higher than the glass transition point of the thermoplastic material;
A method for manufacturing a composite member used under a predetermined temperature, comprising:
The method, wherein the thermoplastic material is a material having a tensile strength within the range of 1 to 30 MPa at the predetermined temperature.
[12]
Any one of aspects 8 to 11, wherein the composite member has a bending strength in the range of 100 to 250 MPa, a bending modulus in the range of 10 to 40 GPa, and a maximum bending strain in the range of 1 to 2%. The method described in.
[13]
The method according to any one of aspects 8 to 12, wherein the composite member contains the flaky particles in an amount of 5 to 99% by volume based on the total volume of the composite member.
[14]
The method according to any one of aspects 8 to 12, wherein the composite member contains the flaky particles in an amount of 50 to 99% by volume based on the total volume of the composite member.
[15]
A method according to any one of aspects 8 to 14, wherein the composite member has a fracture toughness value in the range of 300 to 500 J/m ³ .
[16]
The method according to any one of aspects 8 to 15, wherein the flaky particles are mica particles.

The composite member according to one embodiment of the present invention and the composite member obtained by the manufacturing method according to one embodiment of the present invention break ductilely.

FIG. 1 is a flowchart showing a method for manufacturing a composite member according to the first embodiment. FIG. 2 is a flowchart showing a method for manufacturing a composite member according to the second embodiment. FIG. 3 is a diagram schematically showing a cross section of the composite member according to the embodiment. FIG. 4 is a tensile stress-tensile strain curve of the cured resin composition used in the examples. FIG. 5 is a bending stress-bending strain curve of the composite member produced in the example. FIG. 6 is a graph showing the relationship between the tensile strength of the cured product of the resin composition used in the example and the bending strength of the composite member produced in the example. FIG. 7 is a graph showing the relationship between the tensile strength of the cured product of the resin composition used in the example and the flexural modulus of the composite member produced in the example. FIG. 8 is a graph showing the relationship between the tensile strength of the cured product of the resin composition used in the example and the maximum bending strain of the composite member produced in the example. FIG. 9 is a graph showing the relationship between the tensile strength of the cured product of the resin composition used in the example and the fracture toughness value of the composite member produced in the example. FIG. 10 is a cross-sectional SEM image of the composite members of Examples 1 to 4 produced in Examples. FIG. 11 is a SEM image of a fractured surface formed by a bending test of the composite members of Examples 1 to 4 produced in Examples.

<Method for manufacturing composite member (first embodiment)>
As shown in FIG. 1, the method for manufacturing a composite member according to the first embodiment includes a step of producing a paper product containing flaky particles (S11), and a step of impregnating the paper product with a curable resin composition (S12). ) and a step (S13) of curing the curable resin composition.

(1) Preparation of paper product (S11)
First, flaky particles are mixed with a dispersion medium to prepare a suspension.

As the flaky particles, for example, particles of inorganic materials such as natural mica, synthetic mica, smectite, talc, carbonate, silicate, phosphate, metal, etc. can be used. In this application, "flake-like" means that the equivalent circular diameter of the surface with the maximum projected area (flat surface) is larger than the maximum length (thickness) in the direction perpendicular to this surface. It can also be called scaly, plate-like, or flaky. The flake-like particles may, for example, have a median diameter d of 100 nm to 5000 μm and an average thickness t of 10 nm to 10 μm. Further, the aspect ratio of the flaky particles, that is, the ratio d/t of the median diameter to the average thickness, may be, for example, 100 or more, particularly 100 to 10,000. The median diameter d of flaky particles can be measured using a laser diffraction particle size distribution measuring device. The average thickness t of the flaky particles can be determined by measuring the thickness of 30 or more particles from a cross-sectional image of the flaky particles obtained using SEM or TEM, and calculating the arithmetic mean of the obtained values. You can ask for it.

Water, alcohol, etc. can be used as the dispersion medium.

The prepared suspension is made into a paper to produce a paper product. Paper making can be performed according to JIS P 8222:2015. Specifically, a suspension is made using a paper machine similar to that used in the paper manufacturing industry to obtain a wet mat on a mesh, and the liquid (dispersion medium) contained in the wet mat is removed by drying, etc. By doing so, a sheet-like paper product can be obtained.

In the paper product, the flake-like particles are arranged one on top of the other, and are oriented such that the thickness direction of the flake-like particles is parallel to the thickness direction of the paper product.

(2) Impregnation (S12)
The obtained paper product is impregnated with a curable resin composition. For example, the paper product can be impregnated with the curable resin composition by applying the curable resin composition to the paper product. Impregnation may be promoted by placing the paper product coated with the curable resin composition under reduced pressure or by lowering the viscosity of the curable resin by heating or the like.

The curable resin composition includes curable resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, epoxy acrylate resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, and cyanate resins. include. The curable resin may be used alone or in combination of two or more. The curable resin composition contains a polymerization initiator (thermal polymerization initiator, photopolymerization initiator, etc.), curing agent, curing accelerator, antifoaming agent, surfactant, flame retardant, coloring agent, pigment, phosphor, release agent, etc. It may also contain additives such as molding agents. The curable resin composition may be thermosetting or photocurable.

The curable resin composition is a composition that forms a cured product having a tensile strength within the range of 1 to 30 MPa when cured under the same curing conditions as in the subsequent curing step (S13). By using such a curable resin composition, the composite member obtained by the manufacturing method of the present embodiment has sufficiently high bending strength and bending modulus, and also has large maximum bending strain and ductility. It can show destructive behavior. The cured product of the curable resin composition may have a tensile strength within the range of 1 to 25 MPa or 2 to 24 MPa. Further, the cured product of the curable resin composition may have a tensile strength within the range of 15 to 30 MPa, 20 to 30 MPa, or 23 to 25 MPa. By using such a curable resin composition, the composite member obtained by the manufacturing method of this embodiment can further have a particularly high fracture toughness value. Conventional technology generally uses a material that forms a cured product exhibiting high tensile strength (for example, 40 MPa or more) as a resin composition used for manufacturing composite members reinforced with fillers. When such a material is used in this embodiment, the composite member does not exhibit ductile fracture behavior but undergoes brittle fracture. The tensile strength of the cured product of the curable resin composition can be determined from a tensile stress-tensile strain curve obtained by a tensile test according to JIS C 2151:2019 and ASTM D882. Specifically, tensile strength is the maximum tensile force recorded when a specimen is pulled to break.

The amount of the curable resin composition to be impregnated into the paper product is, for example, such that in the composite member manufactured by the manufacturing method of the present embodiment, the volume fraction of flaky particles is 5 to 99% by volume based on the volume of the composite member. The amount may be within the range of 40-99% by volume or 50-99% by volume. By including the flaky particles at such a high volume fraction in the composite member, the composite member can have sufficiently high bending strength and bending modulus.

(3) Curing (S13)
The curable resin composition impregnated into the paper product is cured. Depending on the shape of the composite member to be produced, pressure molding may be performed by stacking a plurality of paper products. Curing may be performed by heating, ultraviolet irradiation, etc., and the conditions for curing may be appropriately selected depending on the curable resin composition.

Through the above steps, a composite member including a matrix material and flaky particles dispersed in the matrix material is obtained. In the composite member obtained by the manufacturing method of this embodiment, the matrix material is a cured product of a curable resin composition. The flake particles are highly oriented such that the thickness direction of the flake particles is parallel to the thickness direction of the composite member.

<Method for manufacturing composite member (second embodiment)>
As shown in FIG. 2, the method for manufacturing a composite member according to the second embodiment includes a step of preparing a suspension (S21), a step of making a paper product by paper-making the suspension (S22), and a step of producing a paper product by paper-making the suspension. The method includes a step of hot-pressing molding the object (S23).

(1) Preparation of suspension (S21)
A suspension is prepared by mixing the fibrous or particulate thermoplastic material and flake particles with a dispersion medium in air or under an inert atmosphere such as a nitrogen atmosphere.

Examples of thermoplastic materials include thermoplastic resins such as polypropylene (PP), polyamide (PA), polyphenylene sulfide (PPS), and polyethersulfone (PES), glass, cellulose, and plants made from plants such as bamboo and kenaf. Examples include natural fibers.

The thermoplastic material is a material having a tensile strength within the range of 1 to 30 MPa at the operating temperature of the composite member manufactured by the manufacturing method of this embodiment. By using such a thermoplastic material, the composite member obtained by the manufacturing method of this embodiment can have sufficiently high bending strength and bending elastic modulus while having a large maximum bending strain when used. It can also exhibit ductile fracture behavior. The thermoplastic material may have a tensile strength in the range of 1 to 25 MPa or 2 to 24 MPa at the temperature of use of the composite part. The thermoplastic material may also have a tensile strength in the range of 15-30 MPa, 20-30 MPa, or 23-25 MPa at the temperature at which the composite member is used. By using such a thermoplastic material, the composite member obtained by the manufacturing method of this embodiment can further have particularly high fracture toughness values during use. In the prior art, as a thermoplastic material used to manufacture a composite member reinforced with a filler, it is common to use a material that exhibits high tensile strength (for example, 40 MPa or more) at the temperature at which the composite member is used. , when such a material is used in this embodiment, the composite member does not exhibit ductile fracture behavior but undergoes brittle fracture. The tensile strength of a thermoplastic material can be determined from a tensile stress-tensile strain curve obtained by a tensile test according to JIS C 2151:2019 and ASTM D882.

The fibrous thermoplastic material may have, for example, an average fiber diameter D _fib of 0.01 to 1000 μm and an average fiber length L _fib of 0.1 μm to 50 mm. Further, the aspect ratio of the fibrous thermoplastic material, that is, the ratio of average fiber length to average fiber diameter L _fib /D _fib may be, for example, 10 to 10,000. The average fiber length L _fib can be measured using an optical microscope image. The average fiber diameter D _fib is determined by measuring the diameters (circular equivalent diameter) of 30 or more fibers from a cross-sectional image of the fibers obtained using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It is determined by

The particulate thermoplastic material may have, for example, a flake-like, spherical, etc. shape. The flaky thermoplastic material may, for example, have a median diameter D _fl of 1 to 5,000 μm and a mean thickness T _fl of 0.1 to 100 μm. Further, the aspect ratio of the flaky thermoplastic material, that is, the ratio of median diameter to average thickness D _fl /T _fl may be, for example, from 10 to 10,000. The median diameter D _fl of the flaky thermoplastic material can be measured using a laser diffraction particle size distribution measuring device. The average thickness T _fl of the flaky thermoplastic material is determined by measuring and averaging the thicknesses of 30 or more particles from a cross-sectional image of the particles obtained using SEM or TEM.

The spherical thermoplastic material may, for example, have a median diameter D _sp of 10 nm to 1,000 μm. The median diameter D _sp of the spherical thermoplastic material can be measured using a laser diffraction particle size distribution measuring device.

As the flaky particles, for example, particles of inorganic materials such as natural mica, synthetic mica, smectite, talc, carbonate, silicate, phosphate, metal, etc. can be used. The flaky particles may, for example, have a median diameter d between 100 nm and 5000 μm and an average thickness t between 10 nm and 10 μm. Further, the aspect ratio of the flaky particles, that is, the ratio d/t of the median diameter to the average thickness, may be, for example, 100 or more, particularly 100 to 10,000. The median diameter d of flaky particles can be measured using a laser diffraction particle size distribution measuring device. The average thickness t of the flaky particles can be determined by measuring the thickness of 30 or more particles from a cross-sectional image of the flaky particles obtained using SEM or TEM, and calculating the arithmetic mean of the obtained values. You can ask for it.

The volume fraction V _fx of the flaky particles relative to the total volume of the thermoplastic material and the flaky particles to be mixed is in the range from 5 to 99% by volume, in particular in the range from 40 to 99% by volume or from 50 to 99% by volume. It's fine. By using flaky particles at a high volume fraction, the composite member manufactured by the manufacturing method of this embodiment can have sufficiently high bending strength and bending elastic modulus.

を満たしてよい。ここで、フレーク状粒子の平均体積ｖ_ｘは、上述のフレーク状粒子のメジアン径ｄ及び平均厚さｔに基づいて計算される。熱可塑性材料が繊維状で、且つ、その平均繊維長Ｌ_ｆｉｂが、フレーク状粒子のメジアン径ｄを超える場合は、熱可塑性材料の平均有効体積ｖ_ｙは下記式（２）
ｖ_ｙ＝πｄ（Ｄ_ｆｉｂ／２）^２ （２）
で計算され、それ以外の場合は、熱可塑性材料の平均有効体積ｖ_ｙは、上述の熱可塑性材料の各種寸法を用いて計算される熱可塑性材料の体積を指す。上記式（１）を満たす量のフレーク状粒子と熱可塑性材料を用いることにより、後続のステップで作製される抄造物においてフレーク状粒子間に熱可塑性材料がより確実に存在することができ、本実施形態の製造方法により製造される複合部材におけるフレーク状粒子の分散性が一層向上し、複合部材がより高い曲げ強さ及び曲げ弾性率を有することができる。 Further, the volume fraction V _fx of flaky particles and the volume fraction V _fy of thermoplastic particles with respect to the total volume of flaky particles and thermoplastic particles, the average volume v _x of flaky particles, and the average volume of thermoplastic particles The effective volume v _y is expressed by the following formula (1)

may be satisfied. Here, the average volume v _x of the flake-like particles is calculated based on the above-mentioned median diameter d and average thickness t of the flake-like particles. When the thermoplastic material is fibrous and its average fiber length L _fib exceeds the median diameter d of the flaky particles, the average effective volume v _y of the thermoplastic material is expressed by the following formula (2).
v _y = πd(D _fib /2) ² (2)
Otherwise, the average effective volume of the thermoplastic material v _y refers to the volume of the thermoplastic material calculated using the various dimensions of the thermoplastic material described above. By using the amount of flaky particles and thermoplastic material that satisfies the above formula (1), the thermoplastic material can be more reliably present between the flaky particles in the paper product produced in the subsequent step. The dispersibility of the flaky particles in the composite member manufactured by the manufacturing method of the embodiment is further improved, and the composite member can have higher bending strength and bending elastic modulus.

Water, alcohol, etc. can be used as the dispersion medium.

(2) Preparation of paper product (S22)
The prepared suspension is made into a paper product containing a thermoplastic material and flaky particles. Paper making can be performed according to JIS P 8222:2015. Specifically, a suspension is made using a paper machine similar to that used in the paper manufacturing industry to obtain a wet mat on a mesh, and the liquid (dispersion medium) contained in the wet mat is removed by drying, etc. By doing so, a sheet-like paper product can be obtained.

In the paper product, the flake-like particles are arranged one on top of the other, and are oriented such that the thickness direction of the flake-like particles is parallel to the thickness direction of the paper product. Thermoplastic material is present between the overlapping flake particles.

(3) Hot pressure molding (S23)
The paper product is hot-pressed to produce a composite member. Depending on the shape of the composite member to be produced, a plurality of paper products may be stacked and hot-press molded. Furthermore, in order to improve handling properties, the stacked paper products may be preliminarily crimped before hot-press molding. During crimping, the paper product may be heated to a temperature below the melting temperature of the thermoplastic material. Hot press molding is performed by heating the paper product to a temperature that is above the glass transition point or melting temperature of the thermoplastic material and below the decomposition temperature. The thermoplastic material thereby softens and expands to fill the spaces between the flaky particles. Thereafter, the thermoplastic material is solidified by cooling. Thereby, the paper product is molded, and a composite member containing a matrix material and flaky particles dispersed in the matrix material is obtained. In the composite member obtained by the manufacturing method of this embodiment, the matrix material is a thermoplastic material. The flake particles are highly oriented such that the thickness direction of the flake particles is parallel to the thickness direction of the composite member.

<Composite member>
As shown in FIG. 3, the composite member 10 of this embodiment includes a matrix material 2 and flaky particles 4 dispersed in the matrix material 2. The composite member 10 can be manufactured by the manufacturing methods of the first and second embodiments described above.

The composite member 10 may have a plate-like shape. In this application, the term "plate-like" includes not only a flat plate-like shape as shown in FIG. 3, but also a curved plate-like shape having a curved portion.

The matrix material 2 may be a cured product of the curable resin composition described in the above embodiment or a thermoplastic material. The curable resin composition, the thermoplastic material, the material examples of the flake-like particles 4, and the shape of the flake-like particles 4 have been described in detail in the above embodiment, so their explanation will be omitted here.

The composite member 10 contains flake particles 4 in an amount within the range of 5 to 99 volume %, particularly 40 to 99 volume % or 50 to 99 volume % based on the total volume of the composite member 10. good. Since the composite member 10 contains flaky particles 4 at a high volume fraction in this way, the composite member 10 can have sufficiently high bending strength and bending elastic modulus.

The flaky particles 4 are oriented such that their thickness direction is parallel to the thickness direction of the composite member 10. That is, the flaky particles 4 are oriented so that the flat surface 4a of the flaky particles 4 and the surface 10a of the composite member 10 are parallel to each other. Thereby, the composite member 10 can have sufficiently high bending strength and bending elastic modulus. In addition, in this application, "parallel" includes "substantially parallel", and specifically, the average angle between two surfaces or directions is 30 degrees or less, preferably 20 degrees or less, and more preferably 10 degrees. Hereinafter, cases where the angle is particularly preferably 5 degrees or less are also included. For example, from a cross-sectional SEM image or a cross-sectional TEM image of the composite member 10, the average angle between the flat surface 4a of the flaky particles 4 and the surface 10a of the composite member 10 is determined by the average angle between the flat surface 4a of 30 or more flaky particles 4 and It is determined by determining the angles formed by the surface 10a of the composite member 10 and averaging them.

The composite member 10 has a flexural strength in the range of 100 to 250 MPa, in particular 134 to 199 MPa, a flexural modulus in the range of 10 to 40 GPa, in particular 15 to 30 GPa, and a flexural modulus of 1 to 2%, preferably 1 to 1.5 %, especially in the range 1.26-1.29%. According to intensive studies by the inventors, the composite member 10 having such mechanical properties undergoes ductile failure. Therefore, it can be suitably used in applications that require both high strength and prevention of falling fragments when broken, such as vehicle outer panels. The composite member 10 also has a bending strength in the range of 150 to 250 MPa, preferably 180 to 220 MPa, especially 190 to 210 MPa, a bending modulus in the range of 20 to 40 GPa, especially 25 to 35 GPa, and a bending modulus of 1 to 2%. , preferably in the range from 1 to 1.5%, especially from 1.28 to 1.3%. According to intensive studies by the inventors, the composite member 10 having such mechanical properties not only undergoes ductile fracture but also has high fracture toughness values (specifically, 300 to 500 J/m ³ and 400 to 500 J/m 3 ). m ³ or 450 to 500 J/m ³ ). Therefore, it can be suitably used in applications that require high toughness in addition to high strength and prevention of falling off fragments upon fracture.

The bending strength, bending elastic modulus, maximum bending strain, and fracture toughness value of the composite member 10 can be determined from the bending stress-bending strain curve obtained by a three-point bending test according to JIS K 7017:1999. . Specifically, the bending strength is the bending stress applied to the composite member 10 at the maximum load during the test, the bending modulus is the slope of the stress-strain curve within the elastic limit, and the maximum bending strain is the bending stress applied to the composite member 10 at the maximum load during the test. This is the strain of the composite member 10 under load, and the fracture toughness value is the value obtained by integrating the stress-strain curve.

Although the composite member 10 having the above mechanical properties can be manufactured by the manufacturing method of the first or second embodiment, the manufacturing method of the composite member 10 is not limited thereto. Select a suitable material as matrix material 2, i.e. a material with a tensile strength in the range of 1-30 MPa, 1-25 MPa, 2-24 MPa, 15-30 MPa, 20-30 MPa, or 23-25 MPa, and By selecting shaped particles and setting their volume fractions to appropriate values, it is possible to manufacture the composite member 10 by a method different from the manufacturing method of the first or second embodiment.

The present inventors have discovered that because the matrix material 2 is a material having a relatively low tensile strength as described above, when bending stress is applied to the composite member 10, an appropriate shearing load is applied to the flaky particles. As a result, it is believed that the composite member 10 can exhibit ductile fracture behavior while having sufficiently high bending strength and bending modulus.

The composite member 10 may be further molded and used. That is, the composite member 10 can also be used as an intermediate material for manufacturing a final product.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention as described in the claims. It can be performed.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

で表されるビスフェノールＡ型エポキシ樹脂(三菱ケミカル株式会社製ｊＥＲ８２８)、軟質主剤として式（２）

で表されるポリ（プロピレングリコール）ジグリシジルエーテル（ナガセケムテックス株式会社製デナコールＥＸ－９３１）、硬化剤として４－メチルヘキサヒドロ無水フタル酸（ＤＩＣ株式会社製）、硬化促進剤として１，２－ジメチルイミダゾール（四国化成工業株式会社製）を用意した。 <Production of composite member>
(1) Preparation of resin composition As a hard base material, formula (1)

Bisphenol A type epoxy resin (JER828 manufactured by Mitsubishi Chemical Corporation) represented by the formula (2) as a soft base material

Poly(propylene glycol) diglycidyl ether represented by (Denacol EX-931 manufactured by Nagase ChemteX Corporation), 4-methylhexahydrophthalic anhydride (manufactured by DIC Corporation) as a curing agent, and 1,2 as a curing accelerator. -Dimethylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd.) was prepared.

These materials were mixed in the amounts listed in Table 1.

Specifically, weighed hard base ingredients, soft base ingredients, curing agent, and curing accelerator were mixed at 500 rpm under atmospheric pressure using a vacuum-type rotation-revolution mixer (Awatori Rentaro, manufactured by Thinky Co., Ltd.). Mixed for a minute. Further, the pressure inside the container was reduced to 1 kPa and mixing was performed at 500 rpm for 2 minutes, then at 1200 rpm for 1 minute, and further at 1500 rpm for 1 minute. Thereby, a composition containing an epoxy resin (epoxy resin composition) was obtained.

(2) Preparation of paper product White mica particles (diameter 280 μm, average thickness 1 μm, average aspect ratio 280, manufactured by Hubei Zhongtian Mica Products Co., Ltd.) were prepared as flaky particles. The diameter of the mica particles is the median diameter d50 measured using a laser diffraction particle size distribution analyzer (Mastersizer 3000 manufactured by Malvern), and the average thickness of the mica particles was determined from the SEM image. White mica particles were added to water and mixed to obtain a suspension.

2 L of water was added to the paper making device so that the water level was higher than the wire mesh of the paper making device. Next, the above suspension was added to the papermaking device and stirred, and then drained from the bottom of the papermaking device. Thereby, the suspension was filtered through the wire mesh, and a wet mat was formed on the wire mesh.

A cellulose filter paper was layered on the wet mat, and a stainless steel plate was further layered on top of that. The wet mat was compressed by rolling the stainless steel plate with a metal roller, and the water in the wet mat was absorbed by the filter paper.

The wet mat was removed from the wire mesh and filter paper and dried in an oven for 4 hours. Thereby, a sheet-like paper product was obtained. In the same manner, a total of five paper products were produced in each example.

(3) Impregnation Each paper product was cut into a size of 50 mm in length and 50 mm in width (weight 1.8 g). One paper product was placed in a silicone rubber mold measuring 50 mm in length, 50 mm in width, and 20 mm in height, and the above-mentioned resin composition was uniformly applied thereto. The coating weight of the resin composition in each example was as shown in Table 2. One sheet of the paper product was placed on top of it, and a resin composition of the weight shown in Table 2 was further applied uniformly. This process was repeated to apply the resin composition to five paper products.

The mold containing the five paper products coated with the resin composition was placed in a vacuum oven and heated at 80° C. for 30 minutes under reduced pressure. Thereby, the paper product was impregnated with the resin composition.

(4) Curing The paper product impregnated with the resin composition was transferred to a mold measuring 50 mm long, 50 mm wide, and 10 mm high, and heated at 120°C for 90 minutes using a heat press machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.). The resin composition was cured by pressing at a pressure of 5 MPa. Thereby, plate-shaped molded bodies (composite members) of Examples 1 to 4 were obtained. In all of the composite members obtained, the volume fraction of the cured resin composition was 40%, and the volume fraction of white mica particles was 60%.

<Tensile test of cured product of curable resin composition>
The resin compositions of Examples 1 to 4 prepared in (1) above were filled into a mold measuring 50 mm long, 50 mm wide, and 10 mm high, and cured at 120°C for 90 minutes under atmospheric pressure using a heat press machine. I let it happen. Five dumbbell-shaped test pieces (No. 7, thickness 2 mm) according to JIS K 6251:2017 were prepared from the obtained cured product for each example. A tensile test was conducted using a universal testing machine (Autograph AGS-X manufactured by Shimadzu Corporation) in accordance with JIS C 2151:2019 and ASTM D882. The tensile speed was 2 mm/min. The tensile stress-tensile strain curves obtained for each example are shown in FIG.

From the stress-strain curve in FIG. 4, the tensile strength (maximum tensile force recorded when the test piece was pulled until it was cut) of the cured resin composition of each example was determined. The results are shown in Table 3.

<Bending test of composite member>
Five test pieces with a length of 50 mm, width of 10 mm, and thickness of 2 mm were cut from each of the composite members of Examples 1 to 4, and tested using a universal mechanical testing machine (Autograph AGS-X manufactured by Shimadzu Corporation) to JIS K 7017: A three-point bending test was conducted in accordance with 1999. The distance between the supporting points was 32 mm, and the test speed was 1 mm/min. FIG. 5 shows the bending stress-bending strain curves obtained for each example. The composite members of Examples 1 and 2 exhibited brittle failure behavior, and the composite members of Examples 3 and 4 exhibited ductile failure behavior.

From the stress-strain curve in Figure 5, the bending strength of the composite member (the bending stress applied to the composite member at the maximum load during the test), the bending modulus (the slope of the stress-strain curve within the elastic limit), and the maximum bending strain ( The strain of the composite member at the maximum load) and the fracture toughness value (the value obtained by integrating the stress-strain curve) were determined. The results are shown in Table 3. In addition, the relationships between the tensile strength of the cured product of the curable resin composition used to produce the composite member, the bending strength, bending elastic modulus, maximum bending strain, and fracture toughness value of the composite member are shown in Figures 6 to 9. are shown respectively.

<Internal structure observation>
The cross sections of the composite members of Examples 1 to 4 were observed using a scanning electron microscope (TM3030Plus, manufactured by Hitachi High-Tech Corporation). The obtained SEM image is shown in FIG. In the SEM image of FIG. 10, the vertical direction is the thickness direction of the composite member, the light colored part represents the cross section of the mica particles, and the dark colored part represents the cured product of the resin composition (matrix material). In all of the composite members of Examples 1 to 4, mica particles were dispersed in the matrix material, and the mica particles were highly oriented so as to overlap in the thickness direction of the composite member.

<Observation of fracture surface>
The fracture surface of the composite member fractured in the bending test was observed using a SEM (TM3030Plus, manufactured by Hitachi High-Tech Corporation) from the thickness direction of the composite member. The obtained SEM image is shown in FIG. Many broken mica particles were observed on the fracture surfaces of the composite members of Examples 1 and 2. On the fracture surfaces of the composite members of Examples 3 and 4, many non-destructive mica particles were observed.

Based on these evaluation results, by selecting a resin with appropriate tensile strength as the matrix material, it is possible to have a sufficiently high bending strength and a sufficiently high bending modulus, a large maximum bending strain, and a high ductility. It has been shown that composite parts that break down can be obtained. Specifically, in Examples 3 and 4, by using a resin composition whose cured product has a tensile strength of 2 to 24 MPa, a sufficiently high bending strength of 134 to 199 MPa and a sufficiently high bending strength of 15 to 30 GPa can be obtained. A composite member having a high bending modulus, a large maximum bending strain of 1.26 to 1.29%, and ductile failure was obtained. In particular, in Example 3, by using a resin composition whose cured product has a tensile strength of 24 MPa, it has a higher maximum bending strength of 1.29% while having a higher bending strength and a higher bending modulus. A composite member was obtained which exhibits strain, ductile fracture and a particularly high fracture toughness value of 478.7 J/m ³ .

2 matrix material, 4 flake-like particles, 4a flat surface of flake-like particles, 10 composite member, 10a surface of composite member

Claims (16)

A composite member comprising a matrix material and flaky particles dispersed in the matrix material,
A composite member having a bending strength in the range of 100-250 MPa, a bending modulus in the range of 10-40 GPa, and a maximum bending strain in the range of 1-2%. The composite member according to claim 1, wherein the flake particles are contained in an amount of 5 to 99% by volume based on the total volume of the composite member. The composite member according to claim 1, wherein the flaky particles are contained in an amount of 50 to 99% by volume based on the total volume of the composite member. Composite member according to any one of claims 1 to 3, having a fracture toughness value in the range of 300 to 500 J/m ³ . The composite member according to any one of claims 1 to 3, wherein the flaky particles are mica particles. The composite member according to any one of claims 1 to 3, wherein the matrix material is a cured product of an epoxy resin composition. 7. The composite member according to claim 6, wherein the epoxy resin composition includes a bisphenol A epoxy resin and poly(propylene glycol) diglycidyl ether. producing a paper product containing flaky particles;
Impregnating the paper product with a curable resin composition;
Curing the curable resin composition under predetermined conditions;
A method for manufacturing a composite member, comprising:
The method, wherein the curable resin composition is a composition that forms a cured product having a tensile strength within a range of 1 to 30 MPa when cured under the predetermined conditions. 9. The method of claim 8, wherein the curable resin composition comprises an epoxy resin. 9. The method of claim 8, wherein the curable resin composition comprises a bisphenol A epoxy resin and poly(propylene glycol) diglycidyl ether. preparing a suspension comprising a fibrous or particulate thermoplastic material and flake particles;
making a paper product containing the thermoplastic material and the flaky particles by paper-making the suspension;
Hot-press molding the paper product at a temperature equal to or higher than the glass transition point of the thermoplastic material;
A method for manufacturing a composite member used under a predetermined temperature, comprising:
The method, wherein the thermoplastic material is a material having a tensile strength within the range of 1 to 30 MPa at the predetermined temperature. Any of claims 8 to 11, wherein the composite member has a bending strength in the range of 100 to 250 MPa, a bending modulus in the range of 10 to 40 GPa, and a maximum bending strain in the range of 1 to 2%. The method described in paragraph 1. The method according to any one of claims 8 to 11, wherein the composite member contains the flaky particles in an amount of 5 to 99% by volume, based on the total volume of the composite member. The method according to any one of claims 8 to 11, wherein the composite member contains the flaky particles in an amount of 50 to 99% by volume, based on the total volume of the composite member. A method according to any one of claims 8 to 11, wherein the composite member has a fracture toughness value in the range of 300 to 500 J/m ³ . The method according to any one of claims 8 to 11, wherein the flaky particles are mica particles.

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