JP5151535B2 - Sandwich structure, molded body using the same, and electronic equipment casing - Google Patents

Description

  The present invention relates to a sandwich structure excellent in lightness, thinness, and rigidity. Specifically, the sandwich structure of the present invention has a fiber reinforcing material disposed on both sides of a specific core material, and has particularly excellent characteristics such as lightness and thinness.

  Furthermore, the present invention relates to a molded body in which a member having a planar shape made of the sandwich structure and a member having a honeycomb structure in the thickness direction are integrated. This molded body is preferably used for electrical / electronic equipment, office automation equipment, home appliances, medical equipment or automobile parts, aircraft parts, building materials, and the like.

  Fiber Reinforced Resin (FRP) reinforced with a continuous group of reinforcing fibers is used for transportation equipment such as aircraft, automobiles, motorcycles and bicycles, sports equipment such as tennis, golf and fishing rods, and construction structures such as seismic reinforcements. It is frequently used as a material for structures that require lightweight and mechanical properties.

  2. Description of the Related Art A sandwich structure in which FRP is arranged on a skin of a lightweight core material (core) is known as a structure that has improved lightness while ensuring mechanical characteristics. In order to reduce the weight of the structure, a lighter core material is selected, and especially honeycomb core cores with excellent compression properties are widely used for aircraft structural members, automobile members, building members, panel members, etc. It is used.

  Patent Document 1 proposes a sandwich structure having a honeycomb structure as a core, and this structure is useful as a lightweight and highly rigid structural member.

  Patent Document 2 proposes a honeycomb core made of a resin, and since this honeycomb core is excellent in formability such as a curved surface shape, it is useful for a member such as an automobile bumper.

  Patent Document 3 proposes a plastic honeycomb core.

  However, in these sandwich structures, it is difficult to achieve both thinness and mechanical properties, or there is a limit to producing a thin and complex shaped body with high productivity.

  The sandwich structure of Patent Document 1 is inferior in thinness because it is a plate-like molded body having a large honeycomb thickness. In addition, if the honeycomb is thick, there is a problem in formability, so that it cannot be used to form a compact having a complicated shape.

  The honeycomb core of Patent Document 2 uses a honeycomb material as a resin to give some cell walls bendability, thereby exhibiting good moldability. On the other hand, the mechanical properties of the cell wall bends are low. Since it is insufficient, the mechanical properties when the sandwich structure is formed are also insufficient.

  The honeycomb core of Patent Document 3 can be obtained by laminating a plurality of thermoplastic resin films and then stretching, but there is still a problem in productivity and thinness.

  The thinness of the sandwich structure is greatly influenced by the thickness of the core. However, in the first place, in order to enhance the effect of improving the rigidity of the sandwich structure, the core material usually has a certain thickness, satisfying both the lightness and the thinness, and A core material excellent in practical use has not been proposed. Conventionally known honeycomb cores are difficult to manufacture with a thin thickness, and even if a thick honeycomb is pressed and thinned, there are problems such as destruction of honeycomb cells. There was a limit.

  On the other hand, applications of FRP include housings for electrical / electronic devices such as personal computers, office automation devices, audiovisual devices, mobile phones, telephones, facsimiles, home appliances, and toy supplies. These are required not only for mass productivity, moldability, productivity and economy, but also in recent years, have been demanded to be thin and lightweight. In response to this requirement, a magnesium alloy having excellent thinness and rigidity has been utilized, but the metal material has a large specific gravity, so it is not always satisfactory in terms of light weight.

Patent Document 4 proposes an electronic device casing that is excellent in thinness, rigidity, and lightness while securing mass productivity by integrating a surface-shaped FRP and a thermoplastic member. . As electronic devices such as notebook computers, telephones, and information terminals are becoming more portable and the aging of the user population is expected to accelerate in the future, the weight of the electronic device cases listed in these personal digital assistants (PDAs) will be further reduced. Is required.
JP-A-8-258189 JP-A-8-142237 JP 56-98159 A JP 2004-140255 A

  An object of the present invention is to provide a sandwich structure excellent in lightness and thinness in view of the prior art. Another object of the present invention is to integrate the sandwich structure with other members, and to produce a molded body that can be manufactured with high mass productivity and is excellent in lightness and thinness. is there.

The present invention for solving this problem has the following configuration. That is,
(1) At least one structure of a honeycomb structure, an island-shaped structure, or a structure having a void portion penetrating in a direction parallel to the surface, formed by a molding method selected from injection molding, press molding, and punching molding And a fiber reinforcing material (II) composed of continuous reinforcing fibers (A) and a matrix resin (B) disposed on both sides of the core material (I). Sandwich structure (III), wherein the maximum thickness of the sandwich structure (III) is 0.3 to 2.0 mm.

  (2) In the compression test based on JIS-K 7181 (2006) of the sandwich structure (III), the specific compressive stress at 25% strain measured by the method described herein is 5 MPa or more. The sandwich structure according to 1).

  (3) In the compression test based on JIS-K 7181 (2006) of the core material (I), the specific compressive stress at 25% strain measured by the method described in this specification is 15 MPa or more, (1) Or the sandwich structure in any one of (2).

  (4) The sandwich structure according to any one of (1) to (3), wherein the core material (I) has a maximum thickness of 0.1 to 1.8 mm.

  (5) The sandwich structure according to any one of (1) to (4), wherein the specific gravity of the sandwich structure (III) is 0.1 to 1.5.

  (6) The core material (I) formed with the honeycomb structure has at least one cell cross-sectional shape selected from a perfect circle, an ellipse, and a hexagon, (1) to (5) The sandwich structure according to any one of the above.

( 7 ) The following formulas (1) to (1) of the core material (I) formed by forming at least one of the honeycomb structure, the island-shaped structure, or the structure having a void portion penetrating in a direction parallel to the surface. The sandwich structure according to any one of (1) to ( 6 ), wherein the porosity calculated in any one of (3) is 20 to 95%.
Porosity (%) = (total cross-sectional area in honeycomb structure cell / apparent cross-sectional area of core material) × 100: Formula (1)
Porosity (%) = (1− (total cross-sectional area of island-like structure / apparent cross-sectional area of core material)) × 100: Formula (2)
Porosity (%) = (total cross-sectional area of void portions penetrating in the direction parallel to the surface / apparent cross-sectional area of the core material in the direction parallel to the surface) × 100: Formula (3).

( 8 ) Maximum in the cross-sectional shape of the cell of the core material (I) formed of at least one of the honeycomb structure, the island-shaped structure, or the structure having a void portion penetrating in a direction parallel to the surface The sandwich structure according to any one of (1) to ( 7 ), wherein the length, the interval between the island-like structures, or the maximum length in the void portion is 1 to 10 mm.

( 9 ) The sandwich structure according to any one of (1) to ( 8 ), wherein at least a part of the cell wall thickness of the core material (I) or the width of the island portion is 0.05 to 1 mm. .

( 10 ) In the honeycomb structure or the structural core material (I) having a void portion penetrating in a direction parallel to the surface, the cell cross-sectional area or the cross-sectional area of the void portion is 25 mm ² or less. (1) The sandwich structure according to any one of to ( 9 ).

( 11 ) The sandwich structure according to any one of (1) to (10), wherein the core material (I) is a polypropylene resin.

( 12 ) The sandwich structure according to any one of (1) to ( 11 ), wherein the reinforcing fiber (A) is a carbon fiber.

(13) between the layers of the core material (I) and the fiber reinforcement (II), the adhesive layer is disposed, at least said adhesive layer, a modified polyolefin-based resin is selected from polyester resins, and polyamide resins The sandwich structure according to any one of (1) to (12), comprising one type.

( 14 ) A molded body in which the first member made of the sandwich structure according to any one of (1) to ( 13 ) and the second member made of another structural member are joined and integrated.

( 15 ) A molded body in which a face plate made of the sandwich structure according to any one of (1) to ( 13 ) and a frame portion are integrated, and an electric / electronic device, an office automation device, a home appliance, Molded body used for medical equipment, automobile parts, aircraft parts, or building materials.

  The sandwich structure of the present invention has excellent mechanical properties, light weight, and thin wall properties based on its characteristic structure. Further, the sandwich structure of the present invention that is lightweight and thin has excellent specific compressive stress. In addition, the integrated molded body using the sandwich structure of the present invention is suitably used as a component, member or casing of an electric / electronic device, and further, a personal digital assistant (PDA) exemplified in a mobile phone, a notebook computer, etc. ) And the like.

  Hereinafter, a sandwich structure of the present invention and an integrated molded body using the same will be described in detail with reference to the drawings. However, the present invention is not limited to the invention described in the drawings.

(Sandwich structure)
The sandwich structure of the present invention is disposed on both sides of a core material that forms at least one of a honeycomb structure, an island-like structure, or a structure having a void portion penetrating in a direction parallel to the surface. A sandwich structure (III) comprising a fiber reinforcement (II) composed of continuous reinforcing fibers (A) and a matrix resin (B), wherein the maximum thickness of the sandwich structure (III) is 0.3. A sandwich structure in the range of ~ 2.0 mm.

  The core material (I) of the present invention forms a honeycomb structure having cells (small chambers) penetrating in the thickness direction of the core material, or an island shape in which the core material exists independently in an island shape. It is essential to form a structure, or to form a structure having a void portion penetrating in a direction parallel to the surface of the core material. A sandwich structure that is lightweight and has good mechanical properties because the space part penetrates the top and bottom, right and left of the core material, and the cell wall that covers the space part or the core material wall that fills the space part is continuously formed vertically It is because it can obtain.

  The maximum thickness of the sandwich structure of the present invention is preferably in the range of 0.3 mm to 2 mm from the viewpoint of thinness, more preferably 0.3 to 1.5 mm, and most preferably 0.3 to 1.2 mm. Used. If the thickness of the sandwich structure satisfies the above range, the thickness of the core material (I) and the thickness of the fiber reinforcement (II) are not particularly limited, but the core material (I) The thickness is preferably in the range described in the following section (Thickness of the core material (I)).

  The maximum thickness described here is the thickest structure of the sandwich structure composed of the core material of at least one of a honeycomb structure, an island-shaped structure, or a structure having a void portion penetrating in a direction parallel to the surface. It refers to the thickness of the part, and does not include a part to which a shape such as a rib part, an uneven part, or a protrusion is intentionally added.

  FIG. 1 is a perspective view showing an example of a molded body of the present invention in which an example of a sandwich structure of the present invention is used as a first member. In FIG. 1, the molded body 3 is drawn in a disassembled state. A molded body 3 shown in FIG. 1 is a notebook personal computer casing including a first member (top plate) 1 and a second member (frame) 2 having a boss portion 4 and a hinge portion 5.

  FIG. 2 is a perspective view of an example of the sandwich structure (III) of the present invention. In FIG. 2, the sandwich structure (III) of the present invention is shown in an exploded state. In FIG. 2, the sandwich structure (III) 8 of the present invention comprises a core material (I) 6 having a honeycomb structure and a fiber reinforcing material (II) 7 disposed on both surfaces of the core material (I) 6. The fiber reinforcing material (II) 7 is formed of continuous reinforcing fibers (A) and a matrix resin (B). The core material (I) 6 and the fiber reinforcement (II) 7 are bonded to form a sandwich structure (III) 8.

  3 and 4 are perspective views of an example of the sandwich structure (III) of the present invention. 3 and 4, the sandwich structure (III) of the present invention is shown in an exploded state. 3 and 4, the sandwich structure (III) 8 of the present invention is made up of an island-shaped core material (I) 6 and fiber reinforcing material (II) 7 disposed on both surfaces of the core material (I) 6. Become. The fiber reinforcing material (II) 7 is formed of continuous reinforcing fibers (A) and a matrix resin (B). The core material (I) 6 and the fiber reinforcement (II) 7 are bonded to form a sandwich structure (III) 8.

  FIG. 5 is a perspective view of an example of the sandwich structure (III) of the present invention. In FIG. 5, the sandwich structure (III) of the present invention is shown in an exploded state. In FIG. 5, the sandwich structure (III) 8 of the present invention is a fiber reinforcement disposed on both surfaces of the core material (I) 6 and the core material (I) 6 having a void portion penetrating in a direction parallel to the surface. It consists of material (II) 7. The fiber reinforcing material (II) 7 is formed of continuous reinforcing fibers (A) and a matrix resin (B). The core material (I) 6 and the fiber reinforcement (II) 7 are bonded to form a sandwich structure (III) 8.

(Specific compressive stress of sandwich structure)
The sandwich structure of the present invention is excellent in thinness and light weight, and in particular, the specific compressive stress is very excellent. The specific compressive stress of the sandwich structure in the present invention can be verified by the test method described below.

  The maximum thickness formed by arranging the core material (I) and the fiber reinforcing material (II) composed of the continuous reinforcing fibers (A) and the matrix resin (B) on both surfaces of the core material (I) is 0.3. The flat plate portion of the sandwich structure (III) according to the present invention having a diameter of ˜2.0 mm is punched with a punching punch (“Belt punch PO-29” manufactured by Trusco Nakayama Co., Ltd.), and has an outer diameter of φ29 mm and a maximum sample thickness. A disk-shaped sample corresponding to a range of 0.3 to 2.0 mm is obtained.

  When the maximum thickness of the disk-shaped sample is less than 0.8 mm, the compression test is performed in a state where a plurality of the same samples are stacked so as to be 0.8 mm or more. When the maximum sample thickness is 0.8 mm or more, a compression test is performed on one sample. For the compression test jig, a compression test is performed using a cylindrical jig having a diameter of 50 mm and a thickness of 25 mm so that the flat surface portion touches the entire surface of the test piece.

The test conditions of the compression test were based on JIS-K 7181 (2006) except that the crosshead test speed was set to 1 mm / min, and the tensile test device “Instron” (registered trademark) 5565 type universal material testing machine (Instron Japan) (Commercially available) to conduct a compression test. The compressive stress at the time of 25% strain is measured by setting the strain at a compressive stress of 0.05 MPa to 0%, and the specific compressive stress is calculated by the following equation (4).
Specific compressive stress = Compressive stress at 25% strain / apparent specific gravity of sandwich structure: Formula (4).

[Calculation of apparent specific gravity of sandwich structure]
The specific gravity of the sandwich structure used in the formula (4) is an apparent specific gravity (bulk specific gravity), and means a specific gravity including the weight and volume of voids existing inside the sandwich. In order to calculate the specific gravity of the sandwich structure, the apparent volume of the sandwich structure is calculated. Here, the apparent volume of the sandwich structure is obtained by cutting out a flat plate portion of the sandwich structure, measuring the outer shape, and calculating the apparent volume.

<1. In case of flat sandwich structure>
The apparent specific gravity of the sandwich structure is calculated by cutting the sandwich structure, measuring the outer shape of the sandwich structure with a caliper or a micrometer, and calculating the apparent volume V1 of the core material. Further, the weight W1 of the core material is measured with a precision balance, and the specific gravity is calculated by the following formula (5).
Apparent specific gravity of the core material (flat plate) = (weight W1 / volume V1) / density of water: Formula (5)
Density of water: density of water at the same temperature as room temperature when measuring weight W1 and volume V1 (g / cm ³ ).

<2. Curved sandwich structure>
When the sandwich structure is formed with only a curved surface portion and it is difficult to calculate the apparent volume from the outer shape measurement, the appearance of the sandwich structure is determined by the A method (underwater substitution method) described in JIS-K 7112 (2006). The volume is calculated and the apparent specific gravity is calculated.

  In order to satisfy the favorable compressive properties and light weight of the sandwich structure, the specific compressive stress is preferably 5 MPa or more, more preferably 6 MPa or more, and most preferably 7 MPa or more. The upper limit of the specific compressive stress is not particularly limited, but if the specific compressive stress is about 50 MPa, it is sufficient to develop light weight and rigidity.

(Specific compressive stress of core material)
In order to make the sandwich structure of the present invention have both good mechanical properties, thinness and lightness, the core material (I) used for the sandwich structure must also be excellent in mechanical properties, thinness and lightness. Don't be.

  The specific compressive stress of the core material (I) used in the sandwich structure of the present invention can be verified by the test method described below.

  The flat part of the core material (I) having a maximum thickness of 0.1 to 1.8 mm is punched with a punch (“Belt Punch PO-29” manufactured by Trusco Nakayama Co., Ltd.), and has an outer diameter of φ29 mm and a maximum sample thickness. A disk-shaped sample corresponding to a range of 0.1 to 1.8 mm is obtained.

  When the maximum thickness of the disk-shaped sample is less than 0.3 mm, a compression test is performed in a state where a plurality of the same samples are stacked to be 0.3 mm or more. When evaluating an island-shaped core material, it is difficult to handle the core material by cutting out the core material alone and maintaining the void portion. Create and evaluate a model temporarily fixed with tape or adhesive tape. When the maximum sample thickness is 0.3 mm or more, a compression test is performed on one sample. For the compression test jig, a compression test is performed using a cylindrical jig having a diameter of 50 mm and a thickness of 25 mm so that the flat surface portion touches the entire surface of the test piece.

The test conditions of the compression test were based on JIS-K 7181 (2006) except that the crosshead test speed was set to 1 mm / min, and the tensile test device “Instron” (registered trademark) 5565 type universal material testing machine (Instron Japan) The compression test was performed. The compressive stress at the time of 25% strain is measured by setting the strain at a compressive stress of 0.05 MPa to 0%, and the specific compressive stress is calculated by the following formula (6).
Specific compressive stress = Compressive stress at 25% strain / apparent specific gravity of core material: Formula (6).

[Calculation of apparent specific gravity of core material]
The specific gravity of the core material used in the formula (6) is generally called apparent specific gravity (bulk specific gravity), and refers to the specific gravity including the weight and volume of the voids existing inside the sandwich. In order to calculate the specific gravity of the core material, the apparent volume of the core material is calculated. The apparent volume of the core material is calculated by cutting out a flat plate portion of the core material and measuring the outer shape. Further, when it is difficult to calculate the volume from the outer shape of the core material including the curved surface shape, the flat plate portion is cut out, the outer shape is measured, and the apparent volume is calculated. When the core material has an island-like structure, it is difficult to handle the state in which the core material is cut out and the gap portion is maintained. The gap portion is drawn on the drawing, and the required apparent volume is calculated.

The apparent specific gravity of the core material is calculated by cutting the core material, measuring the outer shape of the core material with a caliper or a micrometer, and calculating the apparent volume V2 of the core material. When the core material has an island-like structure, it is difficult to handle the state in which the core material is cut out and the gap portion is maintained. The gap portion is drawn on the drawing, and the required apparent volume is calculated. Further, the weight W2 of the core material is measured with a precision balance, and the specific gravity is calculated by the following formula (7).
Apparent specific gravity of core material = (weight W2 / volume V2) / water density: Formula (7)
Water density: Density of water at the same temperature as room temperature (g / cm ³ ) when weight W2 and volume V2 are measured.

  In order to develop an excellent specific compressive stress in the sandwich structure of the present invention, the specific compressive stress of the core material is preferably 15 MPa or more, more preferably 18 MPa or more, and most preferably 21 MPa or more. preferable. The upper limit of the specific compressive stress is not particularly limited, but if the specific compressive stress is about 100 MPa, it is sufficient to develop light weight and rigidity.

(Thickness of core material (I))
In order to satisfy the thinness of the sandwich structure in the present invention, it is desirable that the maximum thickness of the core material (I) used in the sandwich structure is also thin. From this viewpoint, the maximum thickness of the core material (I) is preferably in the range of 0.1 mm to 1.8 mm, more preferably 0.1 to 1.0 mm from the viewpoint of thinness, and 0.1 to 0.7 mm. Is most preferred.

  Here, the thickness of the core material (I) is the thickness of the portion corresponding to the core material in the distance in the thickness direction of the sandwich structure. For example, in the case of a honeycomb structure, the distance between the upper and lower surfaces of the structure, that is, the distance illustrated in h of FIG. In the case of an island structure, the distance in the thickness direction of the sandwich structure in the island structure is the distance exemplified in h of FIG. In the case of a structure having a void portion penetrating in a direction parallel to the surface, the distance is defined by the upper and lower surfaces of the core material, for example, the distance illustrated in h of FIG.

(Specific gravity of sandwich structure)
In the sandwich structure (III) in the present invention, it is important that the specific gravity of the core material (I) is lower than that of the fiber reinforcement (II) in order to achieve both rigidity and light weight. The smaller the specific gravity of the core material (I), the higher the light weight effect. If the specific gravity of the core material (I) exceeds 1.5, the sandwich structure (III) may not be sufficiently light. The specific gravity of the sandwich structure varies depending not only on the specific gravity of the core material and the specific gravity of the fiber reinforcement, but also on the weight ratio of the core material and the fiber reinforcement, but the specific gravity of the sandwich structure is 0.1-1. The range of 5 is preferably used, 0.1 to 1.0 is more preferable, 0.1 to 0.7 is most preferably used, and can be appropriately selected within the range of the specific gravity.

  The specific gravity of the sandwich structure is not limited to the specific gravity calculation method described in the above section [Calculation of apparent specific gravity of sandwich structure], but also A method (underwater displacement method) described in JIS-K 7112 (2006), B Specific gravity measured by any of the method (pycnometer method), C method (floating / sinking method), and D method (density gradient method) can be used. The specific gravity of the sandwich structure described here is generally called apparent specific gravity (bulk specific gravity), and refers to the specific gravity including the weight and volume of the voids existing inside the sandwich. Therefore, for example, when water enters the void portion in the cell inside the sandwich by the A method, it cannot be measured by this method.

As another specific gravity measurement method, as described in the above section [Calculation of apparent specific gravity of sandwich structure], the outer shape of the sample of the sandwich structure is measured with a caliper or a micrometer to calculate volume V3, The specific gravity may be calculated by measuring the weight W3 of the sample and using the following formula (8).
Specific gravity of sandwich structure = (weight W3 / volume V3) / water density: Formula (8)
Density of water: density of water at the same temperature as room temperature (g / cm ³ ) when weight W3 and volume V3 are measured.

(Honeycomb shape)
In general, the honeycomb structure is generally an aggregate of hexagonal cells (small chambers) (see FIG. 7A). However, in the honeycomb structure of the core material used in the sandwich structure of the present invention, the shape of the cells (small chambers) is not particularly limited, and is a polygon (3-12 dodecagon) (a quadrangular shape in FIG. 7C). Example is described), perfect circle shape (described in FIG. 7B), elliptical shape, indefinite shape, over-extended shape (OX), hanging bell shape (flexible), biset, feather, diamond (FIG. 8D) , Herringbone (FIG. 8 (E)), deformed ten gas (FIG. 8 (F)), sector (FIG. 8 (G)), ten gas (FIG. 8 (H)), ○ ten (FIG. 8 (I)), etc. Any one of the above can be used, and there is no particular limitation even if one shape or a plurality of shapes or sizes are mixed. Among these, in consideration of mechanical strength and mass productivity, a cell having a hexagonal shape, a perfect circular shape, or an elliptical shape is preferably used.

(Shape of island structure)
In the island-like structure of the core material used for the sandwich structure of the present invention, the shape of the island-like shape is not particularly limited, and is a polygonal (3-12 dodecagonal) shape such as a triangle, a square, or a rectangle, As shown in FIG. 9 (J), the black part is the core material), oval shape, indefinite shape, wave shape (the perspective views are shown in FIGS. 3 and 4), etc., any one shape can be used. Even if a plurality of shapes and sizes are mixed, there is no particular limitation. Among them, in consideration of mechanical strength and mass productivity, island-like shapes that are square, rectangular, wavy, perfect circle, and triangle are preferably used.

(The shape of the structure having voids that penetrate in the direction parallel to the surface)
In the shape of the core material having a void portion penetrating in the direction parallel to the surface of the core material used in the sandwich structure of the present invention, the shape is not particularly limited, and there are many void portions such as a triangle, a square, and a rectangle. Any shape such as a square (3-12 dodecagon) shape, a perfect circle (described in FIG. 10 (K), the black portion is a core material, the white portion is a gap), an ellipse, and an indefinite shape can be used. There is no particular limitation even if the shape or size is mixed. Among them, in consideration of mechanical strength and mass productivity, a mountain shape is preferably used among a square shape, a rectangular shape, a perfect circle shape, and an indefinite shape. The mountain shape is, for example, a case where a corrugated plate is used as the core material. For example, a gap shape when a corrugated core material having a wavelength L as illustrated in FIG. 10 (L) is used. That is.

Method for producing a core material obtained by forming a honeycomb structure for use in a sandwich structure of the invention is typically aluminum honeycomb or a paper honeycomb, when prepared using the stretched method or corrugated manner similar to the aramid honeycomb, thin resistance It is very difficult to manufacture a core material with a thickness.

As the core material (I) used in the present invention, it is necessary to use a core material obtained by punching or press-molding a sheet-like material, or a core material manufactured by injection molding. Further, when the cell wall thickness is reduced in order to achieve light weight, if the cell wall thickness is reduced, the cell wall covering the cell is easily broken, and there is a possibility that a cell and an adjacent cell are connected at the time of punching. In addition, when the cell wall thickness is thin, there is a possibility that problems such as undulation of the core material may occur, which may make it difficult to manufacture the honeycomb structure. Therefore, from the viewpoint of mass productivity and light weight, it is most preferable to use a core material produced by injection molding.

(Core material porosity)
The porosity of the core material used in the sandwich structure of the present invention is calculated by any one of the following formulas (1) to (3). In the case where the core material forms a honeycomb structure, the formula (1), and in the case where the core material forms an island structure, the formula (2) In the case of forming a structure having a void portion penetrating in the parallel direction, Expression (3) is used. Moreover, you may calculate the porosity of the core material used for the sandwich structure of this invention by following formula (9).

<Porosity measurement method 1>
Porosity (%) = (total cross-sectional area in honeycomb structure cell (total volume) / apparent cross-sectional area of core material (total volume)) × 100: Formula (1)
Porosity (%) = (1− (total cross-sectional area of island-like structure / apparent cross-sectional area of core material)) × 100: Formula (2)
Porosity (%) = (total cross-sectional area of void portions penetrating in the direction parallel to the surface / apparent cross-sectional area of the core material in the direction parallel to the surface) × 100: Formula (3).

  The apparent cross-sectional area of the core material in the formulas (1) to (3) is obtained by adding the total cross-sectional area of the cell walls (partition walls) covering the cells to the total cross-sectional area in the honeycomb structure cell, or the honeycomb structure The sum of the total volume of the cell walls (partition walls) covering the cell is added to the total volume in the cell.

  When the shape and size of the honeycomb structure cell does not change in the thickness direction, the porosity is calculated from the ratio of the cross-sectional areas, but when the shape and size of the honeycomb structure cell changes in the thickness direction, the volume ratio From this, the porosity is calculated.

  The total cross-sectional area and total volume in the honeycomb structure cell are not particularly limited by any measurement method, but the honeycomb structure cell is photographed with a digital microscope, a digital camera, etc., and the total area in the cell with image processing software, A method for measuring the total volume can be used. The total volume in the cell is calculated from the total area in the cell and the cross-sectional shape in the thickness direction using image processing software, or the total volume is calculated from the cross-sectional area in the cell in the thickness direction and the cell shape, etc. Can be used.

<Porosity measurement method 2>
Porosity (%) = (1−γ ₁ / γ ₂ ) × 100: Formula (9)
γ ₁ : Apparent specific gravity of the core material γ ₂ : True specific gravity of the core material.

The apparent specific gravity γ ₁ of the core material is calculated by cutting the core material, measuring the outer shape of the core material with a caliper or a micrometer, and the apparent volume when the porosity of the core material is 0%. V4 is calculated. Further, the weight W4 of the core material is measured, and the specific gravity can be calculated by the following formula (10).
Apparent specific gravity γ _{1 of} core material = (weight W4 / volume V4) / water density: Formula (10)
Water density: density of water at the same temperature as room temperature (g / cm ³ ) when weight W4 and volume V4 are measured.

The true specific gravity γ ₂ of the core material is determined according to JIS-K 7112 (2006), Method A (submersion method), Method B (Pycnometer method), Method C (Floatation method), Method D (Density gradient method) The specific gravity measured by any of the above can be used.

  The porosity of the core material (I) used in the sandwich structure of the present invention is preferably 20 to 95%, more preferably 50 to 95% from the viewpoint of lightness, and most preferably 70 to 95%. preferable.

(Maximum length of cell cross section, interval between island-like structures or maximum length in voids)
Regarding the size of the cells (small chambers) of the core material (I) used in the sandwich structure of the present invention, the interval between the island-like structures, or the length of the void portion, the cell size, the interval between the island-like structures, When the length is large, the reinforcing fiber material is loosened between the partition walls, and problems such as show-through on the sandwich surface may occur. Therefore, the length of the longest part of the cell, the interval between the island-like structures, or the maximum length in the void portion is preferably in the range of 1 to 10 mm, more preferably 1 to 5 mm, and more preferably 1 to 3 mm Is most preferably used. The length of the longest portion of the cell cross section described here indicates the length when the longest direction is reached in the cell. For example, the maximum length of the cell cross section is the diagonal line for a square, the diameter for a perfect circle, and the major axis for an ellipse. The interval between island structures is the shortest distance L among the distances from the end points of any island structures with scattered island structures to another island structure. means. For example, the distance L in FIG. 3 corresponds to the distance L in FIG. The maximum length of the void portion indicates the length when the length of the void portion in the structure having the void portion penetrating in the direction parallel to the surface is the longest direction. For example, the length L in FIG.

(Cell wall thickness (partition wall) thickness or island width (wall width)
Regarding the cell wall thickness (partition wall thickness) or the width of the island-shaped portion of the core material (I) used in the sandwich structure of the present invention, in consideration of lightness, mass productivity, show-through of the sandwich surface, etc. It is preferable that the thickness of the cell wall thickness or the width of the island portion of at least a part of the width of each cell (partition wall) or island portion is 0.05 to 1 mm, and 0.05 to 0.5 mm. Is more preferable, and it is most preferable that it is 0.05-0.3 mm. Further, the cell wall thickness or the width of the island-shaped portion is not particularly limited even if the thickness or width is constant in the thickness or width direction, or the thickness or width is changed. When the sandwich structure (III) is manufactured, heat press molding may be performed. At this time, the core material (I) is thinned by the influence of heating and pressurizing, and the cell wall thickness or island shape The width of the part may increase. In this case, it is only necessary that the cell wall thickness or the width of the island-shaped portion where the cell wall thickness or the width of the island-shaped portion is not expanded satisfies the above range.

  Here, the width of the island-shaped portion refers to the width of the wall portion forming the island-shaped portion of the core material, as exemplified by W in FIG. 3 and W in FIG. 9. Further, in the case of a core material having a structure having a void portion penetrating in a direction parallel to the surface, when a cell exists in the core material as shown in FIG. 10 (K), it means the cell wall thickness. And when the core material does not form the cell as shown in FIG. 10 (L), it means the thickness W of the plate forming the shape.

(Cross sectional area of cell)
Even if the longest portion of the cell cross section is long, the show-through of the sandwich surface can be eliminated if the shortest portion is short. If the area of the at least one cell of the core material (I) is 25 mm ² or less, preferably for show-through sandwich surface can be solved, more preferably 10 mm ² or less, and most preferably 5 mm ² or less.

(Material of core material)
The material of the core material (I) that forms the honeycomb structure used in the sandwich structure of the present invention is not particularly limited, and either metal or nonmetal can be used. Considering the lightness of the core material (I), it is preferable to use a resin composition for at least a part of the core material (I). In consideration of mass productivity, the core material (I) made of a thermoplastic resin composition capable of injection molding and extrusion molding is more preferably used.

  The group of the thermoplastic resin composition preferably used for the core material (I) used for the sandwich structure of the present invention is exemplified. That is, polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate (PTT) resin, polyethylene naphthalate (PENp) resin, liquid crystal polyester, polyethylene (PE) resin, polypropylene (PP) resin, polyolefin resin such as polybutylene resin, styrene resin, urethane resin, polyoxymethylene (POM) resin, polyamide (PA) resin, polycarbonate (PC) resin, polymethyl methacrylate (PMMA) resin , Polyvinyl chloride (PVC) resin, polyphenylene sulfide (PPS) resin, polyphenylene ether (PPE) resin, modified PPE resin, polyimide (PI) resin, polyamideimide (PAI) resin, Polyetherimide (PEI) resin, polysulfone (PSU) resin, modified PSU resin, polyethersulfone (PES) resin, polyketone (PK) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, poly Fluorine resins such as ether ketone ketone (PEKK) resin, polyarylate (PAR) resin, polyether nitrile (PEN) resin, phenolic resin, phenoxy resin, polytetrafluoroethylene, copolymers thereof, modified products, and Two or more kinds of blended resins may be used. Among the thermoplastic resin compositions exemplified in the above group, polyolefin resins, polyester resins, polyamide resins and the like are preferably used in consideration of adhesion to the fiber reinforcing material (II), strength of the molded body, and impact resistance. In view of the lightness of the core material, polypropylene (PP) resin having a low specific gravity and excellent heat resistance is most preferably used.

  The thermoplastic resin compositions exemplified in the above group are fiber reinforcing agents such as glass fibers and carbon fibers, impact resistance improvers such as elastomers or rubber components, and other fillers, as long as the object of the present invention is not impaired. Or may contain additives. Examples of these include inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers. , Release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, or coupling agents.

(Adhesive layer)
It is preferable that an adhesive layer is disposed between the core material (I) and the fiber reinforcing material (II) used in the sandwich structure of the present invention. In particular, when a polyolefin-based resin is used for the core material (I), the core is used for the purpose of improving the adhesion between the fiber reinforcement (II) and the core material (I) disposed on both sides of the sandwich structure (III). It is preferable that a modified polyolefin resin is disposed between the layers of the material (I) and the fiber reinforcement (II). The larger the functional group amount due to modification in the modified polyolefin-based resin, the better from the viewpoint of increasing the adhesive strength. The method for modifying the polyolefin resin is not particularly limited, and examples thereof include graft reaction of functional group-containing compounds, addition reaction to terminals, and copolymerization of functional group-containing blocks. Among these, a modification technique by graft reaction of a functional group-containing compound having a double bond to an unsaturated polyolefin is more preferable in terms of increasing the amount of functional groups.

  Preferred examples of the functional group include a carboxyl group, an acid anhydride, a hydroxyl group, an epoxy group, and an amino group. The functional group amount can be confirmed using an acid value, an OH value, an epoxy value, an amine value, or the like as an index. Of the modified polyolefin resins, acid-modified polyolefin resins are most preferable from the viewpoint of handleability and ease of modification.

  The modified polyolefin resin can be used by mixing with an unmodified polyolefin resin. From the viewpoint of handling, the blending amount of the acid-modified polyolefin resin is preferably 20% by weight or more, and more preferably 30 to 70% by weight. At this time, the acid value of the acid-modified polyolefin resin is preferably 10 or more, more preferably 20 or more, and most preferably 30 or more.

  When a polyamide-based resin is used for the core material (I), the core is used for the purpose of improving the adhesion between the fiber reinforcing material (II) and the core material (I) disposed on both sides of the sandwich structure (III). A polyamide-based resin is preferably disposed between the material (I) and the fiber reinforcement (II), and specifically, any of polyamides 6, 66, 610, and 612 is preferably used. These can be used singly, but for example, the same series blend resin or copolymer resin of polyamide 6 and polyamide 6, a resin obtained by blending a plurality of different series polyamides, or a copolymer resin is further preferably used.

Further, when a polyester resin is used for the core material (I), the core material (I) is disposed on both sides of the sandwich structure (III) for the purpose of improving the adhesion between the core material (I) and the fiber reinforcing material (II). It is preferable that a polyester resin is disposed between the material (I) and the fiber reinforcement (II), and the polyester resin is composed of one or more kinds of polyester resins, and at least one kind of polyester resin. Is an aromatic or alicyclic cyclic dicarboxylic acid and the following general formula (i)
HO-R-OH (i)
(In the formula, R is a linear or branched alkylene group represented by C _n H _2n (n is an integer of 2 to 10), or C _2n H _4n O _n (n is an integer of 1 or more). R in the diol represented by the above general formula (i), a hard segment composed of a diol represented by the formula (i), an aromatic ring type or alkylene dicarboxylic acid having 2 to 10 carbon atoms, A copolyester comprising a soft segment comprising a diol which is a chain alkylene oxide and containing 50 to 80% by weight of the hard segment is more preferably used.

(Aspect of adhesive layer)
FIG. 6 illustrates a preferred joining form of the core material (I) and the fiber reinforcement (II) forming the sandwich structure (III) of the present invention. FIG. 6 shows a structure in which an adhesive resin forming an adhesive resin layer 14 positioned between the core material 11 and the fiber reinforcing material 12 is impregnated in the gaps between a number of reinforcing fibers 15 constituting the fiber reinforcing material 12. It has become. The maximum impregnation length 18 of the adhesive resin is preferably 10 μm or more, and more preferably 15 μm or more.

(Reinforcing fiber (A))
A group of reinforcing fibers (A) used in the fiber reinforcing material (II) of the present invention is illustrated. That is, metal fibers such as aluminum fiber, brass fiber, stainless steel fiber, glass fiber, polyacrylonitrile series, rayon series, lignin series, pitch series carbon fiber and graphite fiber, aromatic polyamide fiber, polyaramid fiber, PBO fiber, polyphenylene sulfide Examples thereof include organic fibers such as fibers, polyester fibers, acrylic fibers, nylon fibers, and polyethylene fibers, and silicon carbide fibers, silicon nitride fibers, alumina fibers, silicon carbide fibers, and boron fibers. These are used alone or in combination of two or more. These fiber materials may be subjected to surface treatment. Examples of the surface treatment include a metal deposition treatment, a treatment with a coupling agent, a treatment with a sizing agent, and an adhesion treatment of an additive.

(About matrix resin (B))
As the matrix resin (B) of the fiber reinforcing material (II), a thermosetting resin selected from the group of thermosetting resins described later, or a thermoplastic resin selected from the group of thermoplastic resins described later is used. be able to.

  A group of thermosetting resins used in the sandwich structure (III) of the present invention is illustrated. That is, unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol (resole type) resins, urea / melamine resins, polyimide resins, and the like can be preferably used. These copolymers, modified products, and / or resins obtained by blending two or more of these may be used.

  Next, a group of thermoplastic resins used in the sandwich structure (III) of the present invention will be exemplified. That is, polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate (PTT) resin, polyethylene naphthalate (PENp) resin, liquid crystal polyester, polyethylene (PE) resin, polypropylene (PP) resin, polyolefin resin such as polybutylene resin, styrene resin, urethane resin, polyoxymethylene (POM) resin, polyamide (PA) resin, polycarbonate (PC) resin, polymethyl methacrylate (PMMA) resin , Polyvinyl chloride (PVC) resin, polyphenylene sulfide (PPS) resin, polyphenylene ether (PPE) resin, modified PPE resin, polyimide (PI) resin, polyamideimide (PAI) resin, Polyetherimide (PEI) resin, polysulfone (PSU) resin, modified PSU resin, polyethersulfone (PES) resin, polyketone (PK) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, poly Fluorine resins such as ether ketone ketone (PEKK) resin, polyarylate (PAR) resin, polyether nitrile (PEN) resin, phenolic resin, phenoxy resin, polytetrafluoroethylene, copolymers thereof, modified products, and Two or more kinds of blended resins may be used. In particular, from the viewpoint of heat resistance and chemical resistance, the PPS resin is a molded body appearance, and from the viewpoint of dimensional stability, the polycarbonate resin and the styrene resin are from the viewpoint of the strength and impact resistance of the molded body. A polyamide resin is more preferably used.

  The thermosetting resins and thermoplastic resins exemplified in the above group may contain impact improvers such as elastomers or rubber components and other fillers and additives as long as the object of the present invention is not impaired. good. Examples of these include inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers. , Release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, or coupling agents.

  Among the thermosetting resins and thermoplastic resins exemplified in the above group, from the viewpoint of the rigidity, strength, heat resistance, etc. of the sandwich structure (III) and the handling of the prepreg which is a molding material, a thermosetting resin is used. It is preferable to use an epoxy resin. In particular, an epoxy resin is most preferable from the viewpoint of the mechanical properties of the molded body and the heat resistance. The epoxy resin is preferably contained as a main component of the resin to be used in order to express its excellent mechanical properties, and specifically, it is preferably contained in an amount of 60% by weight or more per resin composition. When a flame retardant is blended, the flame retardancy required for electrical / electronic equipment applications can be imparted.

(Curved radius of sandwich structure and molding)
As shown in FIG. 1, the molded body 3 of the present invention comprises a sandwich structure (III) as a first member 1 and a second member 2 joined to the first member 1. For the purpose of achieving both the complicated shape of the molded body 3, mass productivity, and productivity, the sandwich structure (III) that is the first member 1 has a planar shape, and the second member 2 has a thickness direction. On the other hand, it has a shape change. The sandwich structure (III) of the present invention has a planar shape having a maximum thickness in the range of 0.3 to 2.0 mm.

  As represented by the integrated molded body 3 in FIG. 1, the surface shape means that the majority of the projected area is a planar shape or a gentle curved surface shape. For example, a curved surface with a radius of curvature of 1000 m or less may be formed for the purpose of increasing rigidity, and a plurality of these curved surfaces exist intermittently and intermittently in one surface of the molded body 3. It may be. In these planes, a diaphragm (curved surface portion) having a radius of curvature of 3 mm or more may be formed for the purpose of increasing rigidity or giving a degree of freedom to the shape.

  The surface shape may be composed of a plurality of surface shapes, and may have a three-dimensional shape as a whole.

  On the other hand, the second member 2 is integrated with the first member 1 for the purpose of imparting a complicated shape to the molded body 3. Complex shapes mean shapes with thickness changes in the vertical, horizontal, and height directions. Structural features, design geometric shapes, and intentionally formed protrusions and dents Including. A frame (frame) part, a standing wall part, a hinge part, a boss rib part, etc. represented by the 2nd member 2 of FIG. 1 correspond to this. The second member 2 is preferably manufactured by a method that is relatively more mass-productive and more productive than the first member 1.

  The second member 2 is not particularly limited, and is a thermosetting resin selected from the group of thermosetting resins described above, or a thermoplastic resin selected from the group of thermoplastic resins described above, cement, concrete. Alternatively, known materials such as fiber reinforced products, wood, metal materials and paper materials are preferably used. From the viewpoint of moldability, a metal material is preferably used for the purpose of further enhancing the mechanical properties of the molded product, although the thermoplastic resin is inferior in lightness and the fiber-reinforced thermoplastic resin is intended to enhance the mechanical properties. . In particular, it is particularly preferable to use a thermoplastic resin composition in which discontinuous reinforcing fibers are uniformly dispersed in a thermoplastic resin because both mass productivity, moldability, lightness, and mechanical properties are compatible. As the blending ratio of the reinforcing fiber in this case, when the reinforcing fiber is a carbon fiber, it is preferably 5 to 75% by weight with respect to the thermoplastic resin composition from the viewpoint of balance between moldability, strength, and lightness, 15 to 65% by weight is more preferable.

  The molded body 3 of the present invention preferably uses the first member 1 as a main material. 50% or more of the projected area of the molded body 3 is preferably occupied by the first member 1, and more preferably 70% or more of the projected area is occupied by the first member 1.

  In the molded body 3 of the present invention, when the first member 1 and the second member 2 are joined and integrated, it is preferable that excellent adhesion exists between them. Therefore, it is preferable that an adhesive layer is interposed at the bonding interface between the first member 1 and the second member 2. As the adhesive layer, a well-known adhesive such as acrylic, epoxy, or styrene can be used, and an adhesive layer independent of the first member and the second member can be formed. In order to further increase the productivity of integration, it is preferable to provide a thermoplastic resin layer on the outermost layer of the first member.

  In particular, when a thermosetting resin (for example, epoxy resin) is used for the matrix resin (B) of the first member 1 and a thermoplastic resin composition is applied to the second member 2, the first member 1 is used. By providing a thermoplastic resin layer having good affinity with the thermoplastic resin constituting the second member 2 in the outermost layer, the joining interface between the first member 1 and the second member 2 is made of thermoplastic resins. Can be heat-sealed. In this case, it is not necessary to separately provide an adhesive layer at the bonding interface.

  If the adhesive layer provided on the outermost layer of the first member 1 is made of the same material as the thermoplastic resin of the second member 2, it is possible to increase the bonding strength. The resin provided in the outermost layer of the first member 1 is not particularly limited as long as it is not the same resin but has good compatibility, and is optimal depending on the type of the thermoplastic resin constituting the second member 2. It is preferable to select one.

    When a thermosetting resin (for example, epoxy resin) is used as the matrix resin (B) in the fiber reinforcement (II) that forms the adherend surface of the first member 1, the thermoplastic resin of the adhesive layer is In addition, it is preferable that bonding is performed with an uneven shape at the interface with the matrix resin (B). In particular, excellent bonding strength can be obtained when a number of reinforcing fibers among the continuous reinforcing fibers (A) form a bonding form embedded in an adhesive layer formed of a thermoplastic resin.

  Examples of preferred application groups of the sandwich structure of the present invention and a molded body using the sandwich structure are as follows.

<Electrical and electronic equipment>
The sandwich structure of the present invention and the molded body using the same are, for example, various gears, various cases, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, optical pickups, Oscillator, various terminal boards, transformer, plug, printed wiring board, tuner, speaker, microphone, headphones, small motor, magnetic head base, power module, semiconductor, display, FDD carriage, chassis, HDD, MO, motor brush holder It is preferably used for parabolic antennas, notebook computers, mobile phones, digital still cameras, PDAs, portable MDs, liquid crystal displays, plasma displays, and other electrical / electronic equipment products, or parts, members, and housings thereof.

<Office automation equipment>
In addition, the sandwich structure of the present invention and a molded body using the sandwich structure are preferably used for office products such as telephones, facsimiles, copiers, typewriters, word processors, etc., or members and cases thereof.

<Household appliances>
Moreover, the sandwich structure of the present invention and the molded body using the same are a case, a VTR, a copy machine, a television, an iron, a hair dryer, a rice cooker, a microwave oven, an acoustic device, a vacuum cleaner, a toiletry product, It is preferably used for home appliances such as laser discs, compact discs, lighting, refrigerators and air conditioners, or members and casings thereof.

<Medical equipment>
Moreover, the sandwich structure of the present invention and the molded body using the same are preferably used for medical device products such as X-ray cassettes or parts and members thereof.

<Auto parts>
In addition, the sandwich structure of the present invention and a molded body using the sandwich structure include motor parts, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light days, suspension parts, various valves such as exhaust gas valves, fuel Relations, exhaust system or various intake system pipes, air intake nozzle snorkel, air cleaner box, resonator, intake manifold, stabilizer, various arms, various frames, various hinges, various bearings, fuel pump, gasoline tank, CNG tank, engine cooling water Joint, carburetor main body, carburetor spacer, exhaust gas sensor, cooling water sensor, oil temperature sensor, brake pad wear sensor, throttle position Sensor, Crankshaft position sensor, Air flow meter, Brake butt wear sensor, Thermostat base for air conditioner, Heating hot air flow control valve, Brush holder for radiator motor, Water pump impeller, Turbine vane, Wiper motor related parts, Distributor , Starter switch, starter relay, wire harness for transmission, window washer nozzle, air conditioner panel switch board, coil for fuel-related electromagnetic valve, connector for fuse, battery tray, AT bracket, headlamp support, pedal housing, handle, door beam, protector , Chassis, bulkhead, frame, subframe, armrest, horn terminal, Tep motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, noise shield, radiator support, spare tire cover, seat shell, solenoid bobbin, engine oil filter, ignition device case, under cover, scuff plate, pillar trim, propeller shaft, Motorcycles such as drive shafts, wheels, wheel covers, fenders, door mirrors, rear mirrors, fascias, bumpers, bumper beams, bonnets, trunk hoods, aero parts, platforms, cowl louvers, roofs, instrument panels, spoilers and various modules It is preferably used for automobile parts to be included, or automobile parts and skins.

<Aircraft parts>
In addition, the sandwich structure of the present invention and the molded body using the sandwich structure are used for aircraft parts such as landing gear pods, winglets, spoilers, edges, ladders, elevators, failings, ribs, or members and outer plates. Preferably used.

<Building materials>
In addition, the sandwich structure of the present invention and a molded body using the sandwich structure are preferably used for building material members or parts such as panels such as soundproof panels and heat insulation panels.

<Others>
Furthermore, the sandwich structure of the present invention and the molded body using the sandwich structure include various rackets, golf club shafts, yachts, boards, ski equipment, fishing rods, bicycles and other sports related parts, members and satellite related parts, It is preferably used for game or entertainment product parts such as pachinko machines, slot machines, game machines, members and cases, optical equipment such as microscopes, binoculars, cameras, watches, precision machine related parts, members and cases, etc.

  That is, the molded body in which the face plate composed of the sandwich structure according to the present invention and the frame portion are integrated is the above-mentioned electric / electronic device, office automation device, home appliance, medical device, automobile component, aircraft component, building material, etc. It is preferable to be used for. Among these, it is preferably used in applications of electrical / electronic devices such as personal computers, displays, mobile phones, and personal digital assistants, office automation devices, household electrical appliances, or medical devices that require lightweight and high rigidity.

  Furthermore, among the above applications, when the sandwich structure according to the present invention is used for the top surface (top plate) of the electronic device casing having many flat portions, it can sufficiently exhibit the characteristics of thin wall, light weight, and high rigidity. This is preferable. Therefore, the molded body having the top surface made of the sandwich structure according to the present invention and the frame portion made of the thermoplastic resin is preferably used for an electronic device casing in which the top surface and the frame portion are integrated. Among these, the sandwich structure and the frame portion are preferably used by an electronic device housing in which the thermoplastic resin layer is integrated through a thermoplastic resin layer.

  Hereinafter, the present invention will be described in more detail and specifically based on examples. In addition, all the mixture ratios (%) shown in the Examples are values based on% by weight unless otherwise specified.

  The object evaluation method used in the examples is as follows.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

(Measuring method)
(1) Measurement of specific compressive stress A sandwich structure having a predetermined size (thickness of 0.3 to 2 mm) was punched with a punch and a disk-shaped sample with a diameter of 29 mm was obtained.

  Except that the crosshead test speed was set to 1 mm / min for one sample, the crosshead displacement at 0 MPa compression strain was 0% strain based on JIS-K 7181 (2006). The compressive strength at 25% strain was measured, and the specific compressive stress of the sandwich structure (III) was measured by the following formula (9), and the specific compressive stress of the core material (I) was measured by the following formula (10).

(B) Specific compressive stress of sandwich structure (III) Specific compressive stress = Compressive stress at 25% strain / apparent specific gravity of sandwich structure: Formula (11)
(B) Specific compressive stress of core material (I) Specific compressive stress = Compressive stress at 25% strain / apparent specific gravity of core material: Formula (12).

(2) Maximum thickness In a sandwich structure including a core material or a honeycomb-shaped core material, the thickest portion was measured with a micrometer.

(3) Specific gravity measurement (apparent specific gravity)
The apparent specific gravity of the core material or sandwich structure is obtained by cutting a sample and measuring the outer shape of the sample with a caliper or a micrometer to calculate the volume V5. Further, the weight W5 of the sample is measured, and the specific gravity can be calculated by the following formula (13).
Specific gravity = (weight W5 / volume V5) / water density: Formula (13)
Density of water: density of water at the same temperature as room temperature when measuring weight W5 and volume V5 (g / cm ³ ).

(4) Cell cross-sectional shape The cross-sectional shape of the core cell was determined visually.

(5) Porosity The porosity of the core material was calculated from the following formula (14).

Porosity (%) = (1−γ ₁ / γ ₂ ) × 100: Formula (14)
γ ₁ : Apparent specific gravity of the core material γ ₂ : True specific gravity of the core material The true specific gravity of the core material was measured according to the underwater substitution method of JIS-K 7112 (2006).

(6) Maximum length of cell cross section, interval between island-like structures, or maximum length in void portion Using a digital microscope (optical microscope), the longest portion of one core void portion included in the core material was measured. .

(7) Measurement of cell wall thickness and width of island-like structure Using a digital microscope (optical microscope), the cell wall thickness (partition wall thickness) of the portion other than between the intersections of the cell wall (partition wall) covering one core is measured. It was measured. The width of the island structure was measured as it was.

(8) Cell cross-sectional area Using a digital microscope (optical microscope), the cross-sectional area of one core contained in the core material was measured.

(9) Maximum impregnation length After cutting the sandwich plate, the cross section is polished and the cross section of the sandwich structure is observed with an optical microscope (× 400 times), and the portion corresponding to the maximum impregnation length 18 shown in FIG. Was measured.

(10) Comprehensive determination The sandwich structure of the present invention was determined according to the following criteria from the viewpoint of thinness and mechanical properties.
[Thinness]
The maximum thickness of the sandwich structure is 2 mm or less:
The maximum thickness of the sandwich structure is greater than 2 mm: ×
[Mechanical properties]
<Sandwich structure>
Specific compressive stress (at 25% strain) is 5 MPa or more: ○
Specific compressive stress (at 25% strain) is less than 5 MPa: x
<Core>
Specific compressive stress (at 25% strain) is 15 MPa or more: ○
Specific compressive stress (at 25% strain) is less than 15 MPa: x.

(Reference Example 1)
The method for producing the adhesive layer used in the examples is described below.

[Reference Example 1-1]
30% by weight of acid-modified polypropylene resin (“Umex 1010” acid value about 52, melting point 142 ° C., Sanyo Chemical Co., Ltd.) and polypropylene resin (“J229E”, melting point 155 ° C., Mitsui Chemicals) 70 The pellets obtained by melt kneading at 200 ° C. using a twin-screw extruder (TEX-30α) manufactured by Nippon Steel Works, Ltd., having a weight of 150% by weight and a basis weight of 45 g / m ² film (F-1) ).

[Reference Example 1-2]
A pellet of polyamide resin (“CM8000”, quaternary copolymerized polyamide 6/66/610/12, melting point 130 ° C., manufactured by Toray Industries, Inc.) is a 150 × 150 mm size, 50 g / m ² basis weight film (F− Processed into 2).

[Reference Example 1-3]
A polyester hot melt adhesive (“Chemit R248”, manufactured by Toray Fine Chemical Co., Ltd.) was processed into a film (F-3) having a size of 150 × 150 mm and a basis weight of 45 g / m ² .

(Reference Example 2)
It describes below about the core materials (a)-(e) used in the Example and the comparative example.

  Core material (a): Polypropylene resin “Prime Polypro J830HV” (manufactured by Prime Polymer Co., Ltd.) was injection molded to obtain a core material forming a honeycomb structure of 150 × 150 mm and 1 mm thickness. Injection molding was performed using a J350EIII injection molding machine manufactured by Nippon Steel Works, and the injection molding temperature was 220 ° C and the mold temperature was 70 ° C. The cell shape is a regular hexagon as shown in FIG. 7A, the cell wall thickness (thinnest part) is 0.3 mm, the porosity is 80%, the cell size is 3.2 mm, and the core has a specific gravity of 0.18. It was.

  Core material (b): A polyamide resin “Amilan CM1001 (manufactured by Toray Industries, Inc.)” was injection molded to obtain a polyamide sheet having a size of 150 × 150 mm and a thickness of 0.5 mm. The injection molding was performed using a J150EII injection molding machine manufactured by Nippon Steel, Ltd., and the injection molding temperature was 260 ° C. and the mold temperature was 80 ° C. Further, the obtained polyamide sheet has a center pitch of 4 mm, a cell wall thickness (thinnest portion) of 1 mm, and a maximum length of the cell cross section of 3 mm (outside) so as to be the same as the 60 ° staggered arrangement shown in FIG. A punching sheet made of polyamide was obtained by punching with a punching punch ("Belt punch PO-3" manufactured by Trusco Nakayama Co., Ltd.) so that the diameter was 3 mm. .56.

  Core material (c): A polyester resin “Trecon 1401X31 (manufactured by Toray Industries, Inc.)” was injection molded to obtain a core material forming a honeycomb structure of 150 × 150 mm and a maximum thickness of 1.2 mm. Injection molding was performed using a J350EIII injection molding machine manufactured by Nippon Steel Works, Ltd., and the injection molding temperature was 250 ° C. and the mold temperature was 80 ° C. The cell shape is a square (4.5 mm square) as shown in FIG. 7C, the cell wall thickness (thinnest part) is 0.9 mm, the porosity is 69.4%, and the core has a specific gravity of 0.41. Met.

  Core material (d): Polypropylene resin “Prime Polypro J830HV (manufactured by Prime Polymer Co., Ltd.)” was injection molded to obtain a polypropylene sheet having a size of 150 × 150 mm and a thickness of 1 mm. The injection molding was performed using a J150EII injection molding machine manufactured by Nippon Steel Works, and the injection molding temperature was 220 ° C and the mold temperature was 70 ° C. The specific gravity of the core material was 0.91.

  Core material (e): Aramid honeycomb “Aramid honeycomb SAH-1 / 8-1.8, thickness 12 mm (manufactured by Showa Aircraft Co., Ltd.)” was cut into 150 × 150 mm. The specific gravity of the core material was 0.029, the cell shape was hexagonal, and the porosity was 88%.

  Core material (g): A polypropylene resin “Prime Polypro J830HV” (manufactured by Prime Polymer Co., Ltd.) was press-molded to obtain a film having a thickness of 1 mm. This was punched into a disk-shaped plate having a diameter of 3 mm. This disk-shaped plate was arranged as shown in FIG. 9 (J) so as to have a spacing of 3 mm at the time of press molding to form a core material.

  Core material (h): Polypropylene resin “Prime Polypro J830HV” (manufactured by Prime Polymer Co., Ltd.) was press-molded to obtain a corrugated film having a wavelength L of 3 mm, a thickness h of 2 mm, and a width W of 1 mm.

  Core material (i): A polypropylene resin “Prime Polypro J830HV” (manufactured by Prime Polymer Co., Ltd.) was press-molded to obtain a film having a thickness of 0.5 mm. Cylindrical Teflon (registered trademark) spacers having a diameter of 3 mm were arranged in parallel on this polypropylene resin film, and another polypropylene resin film was stacked from above and press-molded. After press molding, a Teflon (registered trademark) spacer was pulled out to obtain a core material as shown in FIG.

  Core material (j): Core material (h) (W-shaped corrugated film with a width of 1 mm) was cut to a width of 1 mm to create a corrugated island-shaped structure as shown in 6 of FIG. .

Core material (k): A prepreg impregnated with a group of carbon fibers arranged in one direction with an epoxy resin (thermosetting resin) ("Torayca (registered trademark)" prepreg P3052S-12 manufactured by Toray Industries, Inc. Eight pieces of “Torayca (registered trademark)” T700S manufactured by Co., Ltd., carbon fiber content: 67 wt%, fiber weight: 125 g / m ² ) were cut into a size of 200 × 200 mm. Using these sheets, the layers were sequentially laminated so as to be 0 degree / 90 degrees / 90 degrees / 0 degrees / 0 degrees / 90 degrees / 90 degrees / 0 degrees with respect to the fiber direction. Next, as a release film, “Tedlar (registered trademark)” films manufactured by Toray DuPont Co., Ltd. are placed on the top and bottom of the laminate, and set in a corrugated mold for press molding made of SUS, at 150 ° C. The epoxy resin was cured by applying a surface pressure of 1 MPa for 30 minutes to obtain a corrugated carbon fiber reinforced composite material having a wavelength of 3 mm and a thickness of 1 mm. The corrugated carbon fiber composite material was cut to have a width of 1 mm, and a corrugated island structure as shown in 6 of FIG. 3 was created.

Example 1
A prepreg impregnated with carbon fiber groups arranged in one direction with an epoxy resin (thermosetting resin) ("Torayca (registered trademark)" prepreg P3052S-12 manufactured by Toray Industries, Inc. "Torayca" manufactured by Toray Industries, Inc.) (Registered Trademark) “T700S used, carbon fiber content: 67 wt%, fiber weight: 125 g / m ² ), four prepreg sheets having a size of 150 × 150 mm were cut out to have a predetermined shape. Using these sheets, based on the fiber direction, 0 degree / 90 degrees / film (F-1) / core material (a) / film (F-1) / 90 degrees / 0 degree / film (F-2) In order to become, what was sequentially laminated was prepared.

  Next, as a release film, “Tedlar (registered trademark)” films manufactured by Toray DuPont Co., Ltd. are placed on the top and bottom of the laminate and set on a flat plate for press molding made of SUS at 145 ° C. for 10 minutes. Subsequently, the epoxy resin was cured by applying a surface pressure of 0.02 MPa at 130 ° C. for 20 minutes. After completion of curing, after cooling at room temperature, the release film was removed to form a sandwich plate. A predetermined size (110 (fiber direction) × 140 mm (top direction perpendicular to the fiber) top plate 1) was cut out from the sandwich plate to obtain a sandwich structure (a).

  The thickness of the sandwich structure (a) is 1.48 mm, and the core material (a) is thinned to 0.98 mm due to the effect of heating and pressurization during molding, and the specific gravity of the sandwich structure (a) Was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (a) and the sandwich structure (a), the specific compressive stress of the core material (a) was 25.0 MPa, and the specific compressive stress of the sandwich structure was 8 MPa. It was.

  When the bonded portion of the core material (a) and the fiber reinforcement of the sandwich structure (a) was cut out and the cross section was observed with an optical microscope, the heat constituting the film (F-1) as shown in FIG. Plastic resin was observed as a region of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  The obtained sandwich structure (a) was inserted into an injection mold, and using a long fiber pellet (TLP1146S manufactured by Toray Industries, Inc., carbon fiber content 20% by weight, polyamide resin matrix), the sandwich structure (a Outsert injection molding was performed so as to form the second member 2 as a frame having the boss rib portion 4 and the hinge portion 5 on the outer periphery of the). The injection molding was performed using a J350EIII injection molding machine manufactured by Nippon Steel Works, Ltd., and the cylinder temperature was 280 ° C. The obtained molded body was joined at an overlap length of about 5 mm at least at the portion where the film (F-2) was disposed, and was firmly integrated.

(Example 2)
The laminated structure of the sandwich laminate is 0 degree / 90 degrees / film (F-2) / core material (b) / film (F-2) / 90 degrees / 0 degree / film (F-2). A sandwich structure (b) was obtained by molding in the same manner as in Example 1 except that the layers were laminated.

  The thickness of the obtained sandwich structure (b) was 0.96 mm, and the core material (b) was thinned to 0.48 mm due to the influence of heating and pressurization during molding, and the sandwich structure (b ) Was 1.07. Furthermore, as a result of evaluating the specific compressive stress of the core material (b) and the sandwich structure (b), the specific compressive stress of the core material (b) is 11.0 MPa, and the specific compressive stress of the sandwich structure (b) is It was 6.3 MPa.

  When the joint part of the core material (b) and the fiber reinforcing material of this sandwich structure (b) was cut out and the cross section was observed with an optical microscope, a film (F-2) was formed as shown in FIG. Thermoplastic resins were observed as regions of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 25 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (b), the molded body (b) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (b) and the second member were produced. 2 was firmly integrated.

(Example 3)
The laminated structure of the sandwich laminate is 0 degree / 90 degrees / film (F-3) / core material (c) / film (F-3) / 90 degrees / 0 degree / film (F-2). Except having laminated | stacked, it shape | molded similarly to Example 1, and obtained the sandwich structure (c).

  The thickness of the obtained sandwich structure (c) was 1.65 mm, and the core material (c) was thinned to 1.16 mm due to the effects of heating and pressurization during molding, and the sandwich structure (c ) Was 0.72. Furthermore, as a result of evaluating the specific compressive stress of the core material (c) and the sandwich structure (c), the specific compressive stress of the core material (c) is 14.1 MPa, and the specific compressive stress of the sandwich structure is 7.8 MPa. Met.

  When the joining part of the core material (c) and the fiber reinforcing material of this sandwich structure (c) was cut out and the cross section was observed with an optical microscope, a film (F-3) was formed as shown in FIG. Thermoplastic resins were observed as regions of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (c), the molded body (c) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (c) and the second member were produced. 2 was firmly integrated.

Example 4
A prepreg impregnated with carbon fiber groups arranged in one direction with an epoxy resin (thermosetting resin) ("Torayca (registered trademark)" prepreg P3052S-12 manufactured by Toray Industries, Inc. "Torayca" manufactured by Toray Industries, Inc.) Registered trademark) ”T700S, carbon fiber content: 67 wt%, fiber weight: 125 g / m ² ), four prepreg sheets having a size of 50 × 150 mm were cut out in a predetermined shape. The core material (a) was cut into 50 × 150 mm to obtain the core material (f). Using these sheets and the core material, with reference to the fiber direction, 0 degree / 90 degrees / film (F-1) / core material (f) / film (F-1) / 90 degrees / 0 degree / film (F -2) was prepared by sequentially laminating.

  Next, as a release film, “Tedlar (registered trademark)” films manufactured by Toray DuPont Co., Ltd. are placed above and below the laminate and preheated to 150 ° C. in advance (FIG. 6) The mold is clamped after the 80 mm square convex shape and 110 mm square concave shape combination), and the epoxy resin is cured by applying a surface pressure of 0.02 MPa at 145 ° C. for 10 minutes and then at 130 ° C. for 20 minutes. It was. After curing, the mold was removed after cooling at room temperature, and the release film was removed to form a three-dimensional sandwich structure (f) shown in FIG. The sandwich plate (f) had a curved surface with a radius of curvature of 10 mm, and particularly the curved surface portion had a very high rigidity.

(Example 5)
Example 1 except that the disk-shaped plate prepared for the core material (g) is disposed between the film (F-1) and the film (F-1) so as to have the shape of the core material (g). In the same manner as above, a sandwich structure (g) was obtained.

  The thickness of the sandwich structure (g) is 1.48 mm, and the core material (g) is thinned to 0.98 mm due to the effects of heating and pressurization during molding, and the specific gravity of the sandwich structure (g) Was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (g) and the sandwich structure (g), the specific compressive stress of the core material (g) was 16.0 MPa, and the specific compressive stress of the sandwich structure was 6 MPa. It was.

  When the bonded portion of the core material (g) and the fiber reinforcing material of the sandwich structure (g) was cut out and the cross section was observed with an optical microscope, the heat constituting the film (F-1) as shown in FIG. Plastic resin was observed as a region of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (g), the molded body (d) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (g) and the second member were produced. 2 was firmly integrated.

(Example 6)
A sandwich structure (h) was obtained in the same manner as in Example 1 except that the core material (h) was used between the film (F-1) and the film (F-1).

  The thickness of the sandwich structure (h) is 1.48 mm, and the core (h) is thinned to 0.98 mm due to the effects of heating and pressurization during molding, and the specific gravity of the sandwich structure (h) Was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (h) and the sandwich structure (h), the specific compressive stress of the core material (h) was 16.0 MPa, and the specific compressive stress of the sandwich structure was 6 MPa. It was.

  When the bonded portion of the core material (h) and the fiber reinforcing material of the sandwich structure (h) was cut out and the cross section was observed with an optical microscope, the heat constituting the film (F-1) as shown in FIG. Plastic resin was observed as a region of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (h), the molded body (e) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (h) and the second member were produced. 2 was firmly integrated.

(Example 7)
A sandwich structure (i) was obtained in the same manner as in Example 1 except that the core material (i) was disposed between the film (F-1) and the film (F-1).

  The thickness of the sandwich structure (i) is 1.48 mm, and the core (i) is thinned to 0.98 mm due to the effects of heating and pressurization during molding, and the specific gravity of the sandwich structure (i) Was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (i) and the sandwich structure (i), the specific compressive stress of the core material (i) was 16.0 MPa, and the specific compressive stress of the sandwich structure was 6 MPa. It was.

  When the bonded part of the core material (i) and the fiber reinforcing material of the sandwich structure (i) was cut out and the cross section was observed with an optical microscope, the heat constituting the film (F-1) as shown in FIG. Plastic resin was observed as a region of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (i), the molded body (f) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (i) and the second member were produced. 2 was firmly integrated.

(Example 8)
A sandwich structure (j) was obtained in the same manner as in Example 1 except that the core material (j) was disposed between the film (F-1) and the film (F-1).

  The thickness of the sandwich structure (j) is 1.48 mm, and the core (j) is thinned to 0.98 mm due to the effect of heating and pressurization during molding, and the specific gravity of the sandwich structure (j) Was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (j) and the sandwich structure (j), the specific compressive stress of the core material (j) was 16.0 MPa, and the specific compressive stress of the sandwich structure was 6 MPa. It was.

  When the bonded portion of the core material (j) and the fiber reinforcing material of the sandwich structure (j) was cut out and the cross section was observed with an optical microscope, the heat constituting the film (F-1) as shown in FIG. Plastic resin was observed as a region of different contrast in the fiber reinforcement. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the reinforcing fiber bundle, and the maximum impregnation length 18 was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (j), the molded body (g) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (j) and the second member were produced. 2 was firmly integrated.

Example 9
A sandwich structure (k) was obtained in the same manner as in Example 1 except that the core material (k) was disposed between the film (F-1) and the film (F-1).

  The thickness of the sandwich structure (k) was 1.5 mm. The specific gravity of the sandwich structure (k) was 0.63. Furthermore, as a result of evaluating the specific compressive stress of the core material (k) and the sandwich structure (k), the specific compressive stress of the core material (k) was 50 MPa or more, and the specific compressive stress of the sandwich structure was 50 MPa or more. It was.

  When the joint part of the core material (k) and the fiber reinforcing material of the sandwich structure (k) was cut out and the cross section was observed with an optical microscope, the thermoplastic resin constituting the film (F-1) was found to be a core material ( k) and in the fiber reinforcement were observed as regions of different contrast. It was found that the region of the modified polyolefin resin layer was impregnated in the thickness direction of the core material (k) and the reinforcing fiber bundle, and the maximum impregnation length was 20 μm.

  Except that the sandwich structure (a) was changed to the sandwich structure (k), a molded body (h) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (k) and the second member were produced. 2 was firmly integrated.

(Comparative Example 1)
A prepreg impregnated with carbon fiber groups arranged in one direction with an epoxy resin (thermosetting resin) ("Torayca (registered trademark)" prepreg P3052S-12 manufactured by Toray Industries, Inc. "Torayca" manufactured by Toray Industries, Inc.) (Registered Trademark) “T700S used, carbon fiber content: 67 wt%, fiber weight: 125 g / m ² ), four prepreg sheets having a size of 150 × 150 mm were cut out to have a predetermined shape. Using these sheets, two sets of laminates each having 0 ° / 90 ° with respect to the fiber direction were prepared.

  Next, as a release film, “Tedlar (registered trademark)” films manufactured by Toray DuPont Co., Ltd. are placed on the top and bottom of the laminate and set on a flat plate for press molding made of SUS at 145 ° C. for 10 minutes. Then, the epoxy resin was cured by applying a surface pressure of 0.6 MPa at 130 ° C. for 20 minutes. After completion of curing, after cooling at room temperature, the release film was removed to obtain a skin layer composed of a two-layer laminate.

  The room temperature curable epoxy adhesive “Chemit Epoxy TE2220” (manufactured by Toray Fine Chemical Co., Ltd.), which is an adhesive, is applied to one side of the two skin layers, and the adhesive applied to the skin layer is the core. The layers were sequentially laminated so as to be in contact with the skin layer (0 degree / 90 degrees) / core material (d) / skin layer (90 degrees / 0 degree), while maintaining a surface pressure of 0.6 MPa. The adhesive was cured over a period of 24 ° C. for 24 hours to form a sandwich plate. A predetermined size [110 (fiber direction) × 140 mm (top direction perpendicular to the fiber) top plate 1] was cut out from this sandwich plate to obtain a sandwich structure (d).

  The sandwich structure (d) had a thickness of 1.50 mm, and the core material (d) had a thickness of 1.0 mm. The specific gravity of the sandwich structure (d) was 1.12. Further, as a result of evaluating the specific compressive stress of the core material (d) and the sandwich structure (d), the specific compressive stress of the core material (d) was 6 MPa, and the specific compressive stress of the sandwich structure was 4.3 MPa. It was.

  Except that the sandwich structure (a) was changed to the sandwich structure (d), the molded body (d) was produced by outsert molding in the same manner as in Example 1. As a result, the sandwich structure (d) and the second member were produced. The second member 2 peeled due to insufficient adhesion between the two.

(Comparative Example 2)
A prepreg impregnated with carbon fiber groups arranged in one direction with an epoxy resin (thermosetting resin) ("Torayca (registered trademark)" prepreg P3052S-12 manufactured by Toray Industries, Inc. "Torayca" manufactured by Toray Industries, Inc.) (Registered Trademark) “T700S used, carbon fiber content: 67 wt%, fiber weight: 125 g / m ² ), four prepreg sheets having a size of 150 × 150 mm were cut out to have a predetermined shape. Using these sheets, two sets of laminates each having 0 ° / 90 ° with respect to the fiber direction were prepared.

  Next, as a release film, “Tedlar (registered trademark)” films manufactured by Toray DuPont Co., Ltd. are placed on the top and bottom of the laminate and set on a flat plate for press molding made of SUS, at 150 ° C. for 5 minutes. The epoxy resin was cured by applying a surface pressure of 0.02 MPa. After completion of curing, after cooling at room temperature, the release film was removed to obtain a skin layer composed of a two-layer laminate.

  A room temperature curable epoxy adhesive “Chemit Epoxy TE2220 (manufactured by Toray Fine Chemical Co., Ltd.)” as an adhesive was applied to one side of the two skin layers, and the skin layer adhesive was applied to the core material. Laminate sequentially so as to be in contact with the skin layer (0 degree / 90 degrees) / core material (e) / skin layer (90 degrees / 0 degree) and maintain a surface pressure of 0.02 MPa at 25 ° C. × The adhesive was cured over 24 hours to form a sandwich plate. A predetermined size (110 (fiber direction) × 140 mm (perpendicular to the fiber) top plate 1 with the fiber direction as the longitudinal direction) was cut out from the sandwich plate to obtain a sandwich structure (e).

  The thickness of the sandwich structure (e) was 12.5 mm, and the specific gravity of the sandwich structure (e) was 0.24. Furthermore, as a result of evaluating the specific compressive stress of the core material (e) and the sandwich structure (e), the specific compressive stress of the core material (e) was 50 MPa, and the specific compressive stress of the sandwich structure was 5.5 MPa. It was.

  When Examples 1 to 3 and 5 to 9 and Comparative Examples 1 and 2 are compared in Table 1 with respect to various items, the sandwich structures described in Examples 1 to 3 and 5 to 9 are not only lightweight but thin. And excellent specific compressive stress. Further, the sandwich structure described in Example 4 was able to form a three-dimensional structure having a curved surface by taking advantage of its thinness. On the other hand, the sandwich laminate described in Comparative Example 1 has a heavy weight, so that the specific compressive stress is remarkably reduced. The sandwich laminate described in Comparative Example 2 has very good mechanical properties but is very thick and thin. Inferior to sex. Comparative Examples 1 and 2 could not achieve both thinness and specific compressive stress.

  The integrated molded article using the sandwich structure of the present invention is not limited to a molded article used for electrical / electronic equipment, office automation equipment, home appliances, medical equipment, automobile parts, aircraft parts, building materials, etc. -Application to transportation equipment such as ships is also possible, but the scope of application is not limited to these.

The perspective view of the state which decomposed | disassembled an example of the integrally molded product of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure of this invention. Sectional drawing of the junction part for demonstrating the joining state of the core material and fiber reinforcement in an example of the sandwich structure of this invention. Sectional drawing (1) of the core material in an example of the sandwich structure of this invention. Sectional drawing (2) of the core material in an example of the sandwich structure of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure using the core material of the island-shaped structure of this invention. The perspective view of the state which decomposed | disassembled an example of the sandwich structure using the core material of the structure which has the space | gap part penetrated in the direction parallel to the surface of this invention. Sectional drawing of the core material and metal mold | die in an example of the sandwich structure of this invention. The perspective view of the three-dimensional sandwich structure in an example of the sandwich structure of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st member 2 2nd member 3 Molded body 4 Boss part 5 Hinge part 6 Core material 7 Fiber reinforcing material 8 Sandwich structure 11 Core material 12 Fiber reinforcing material 13 Joining surface 14 Adhesive resin layer 15, 15a Reinforcing fiber 16 Matrix resin 17 Interface 18 Impregnation length 19 Outline line 20 Maximum impregnation site 21 Core material cross section (hexagonal honeycomb)
21-1 Cell size 21-2 Maximum length of cell cross section 21-3 Cell wall thickness 22 Core material cross-sectional view (perfectly shaped honeycomb)
22-1 Center pitch 22-2 Cell wall thickness 22-3 Center pitch 22-4 Maximum length of cell cross section 22-5 Cell arrangement angle 22-6 Center line passing through centroid of cell 23 Core material cross section (square honeycomb )
23-1 Maximum length of cell cross section 23-2 Cell wall thickness 23-3 Cell size 31 Core material cross section (diamond honeycomb)
32 Core material cross section (Herringbone honeycomb)
33 Cross-sectional view of core material (deformed ten gasli type honeycomb)
34 Cross section of core material (fan-shaped honeycomb)
35 Cross section of core material (ten gas honeycomb type)
36 Cross section of core material (10 type honeycomb)
37 Core material with island-shaped structure 38 Core material with a void portion penetrating in a direction parallel to the surface (the void portion is a perfect circle)
39 Core material having a void portion penetrating in a direction parallel to the surface (wave shape)
40 Cavity 41 Female Mold Cross Section 42 Core Material 43 Male Mold 44 Solid Sandwich Structure

Claims (15)

Forming at least one of a honeycomb structure, an island-shaped structure, or a structure having a void portion penetrating in a direction parallel to the surface, formed by a molding method selected from injection molding, press molding, and punching molding ; Sandwich structure comprising a core material (I) and a fiber reinforcing material (II) composed of continuous reinforcing fibers (A) and a matrix resin (B) disposed on both sides of the core material (I) (III) A sandwich structure having a maximum thickness of 0.3 to 2.0 mm of the sandwich structure (III). In the compression test based on JIS-K 7181 (2006) of the sandwich structure (III), the specific compressive stress at 25% strain measured by the method described herein is 5 MPa or more. The sandwich structure described. In the compression test based on JIS-K 7181 (2006) of the core material (I), the specific compressive stress at 25% strain measured by the method described herein is 15 MPa or more. The sandwich structure according to any one of the above. The sandwich structure according to any one of claims 1 to 3, wherein the core material (I) has a maximum thickness of 0.1 to 1.8 mm. The sandwich structure according to any one of claims 1 to 4, wherein the sandwich structure (III) has a specific gravity of 0.1 to 1.5. The core material (I) formed with the honeycomb structure has at least one cell cross-sectional shape selected from a perfect circle, an ellipse, and a hexagon. Sandwich structure. The following formulas (1) to (3) of the core material (I) formed by forming at least one of the honeycomb structure, the island structure, or the structure having a void portion penetrating in the direction parallel to the surface The sandwich structure according to any one of claims 1 to 6, wherein the porosity calculated in any of (1) to (20) is 20 to 95%.
Porosity (%) = (total cross-sectional area in honeycomb structure cell / apparent cross-sectional area of core material) × 100: Formula (1)
Porosity (%) = (1− (total cross-sectional area of island-like structure / apparent cross-sectional area of core material)) × 100: Formula (2)
Porosity (%) = (total cross-sectional area of void portion penetrating in the direction parallel to the surface / apparent cross-sectional area of the core material in the direction parallel to the surface) × 100: Formula (3) The maximum length in the cross-sectional shape of the cell of the core material (I) formed of at least one of the honeycomb structure, the island-shaped structure, or the structure having a void portion penetrating in a direction parallel to the surface, The sandwich structure according to any one of claims 1 to 7, wherein either the interval between the island-like structures or the maximum length at the void portion is 1 to 10 mm. The sandwich structure according to any one of claims 1 to 8, wherein at least a part of the cell wall thickness of the core material (I) or the width of the island portion is 0.05 to 1 mm. The core structure (I) formed by forming the honeycomb structure or the structure having a void portion penetrating in a direction parallel to the surface has a cell sectional area or a sectional area of the void portion of 25 mm ² or less. Item 10. The sandwich structure according to any one of Items 1 to 9. The sandwich structure according to any one of claims 1 to 10, wherein the core material (I) is a polypropylene resin. The sandwich structure according to any one of claims 1 to 11, wherein the reinforcing fibers (A) are carbon fibers. An adhesive layer is disposed between the core material (I) and the fiber reinforcement (II), and the adhesive layer is made of at least one selected from a modified polyolefin resin, a polyester resin, and a polyamide resin. The sandwich structure according to any one of claims 1 to 12, which is configured. A molded body in which the first member comprising the sandwich structure according to any one of claims 1 to 13 and the second member comprising another structural member are joined and integrated. A face plate made of the sandwich structure according to any one of claims 1 to 13, and a molded body in which a frame portion is integrated, an electric / electronic device, an office automation device, a home appliance, a medical device, an automobile part, Molded body used for aircraft parts or building materials.