JP5098132B2 - Fiber reinforced resin sandwich panel - Google Patents

Description

  The present invention relates to a sandwich panel made of a fiber reinforced resin that is lightweight, highly rigid and excellent in X-ray permeability and has a small thickness, and relates to a fiber reinforced resin sandwich panel suitable for medical devices, members for X-ray devices, and the like. .

  In recent years, a plate material made of a fiber reinforced resin in which a matrix resin is impregnated with a reinforcing fiber mainly made of carbon fiber that is lightweight and highly rigid has been proposed as a member for X-ray equipment.

  For example, an X-ray diagnostic apparatus plate material composed of a unidirectionally aligned carbon fiber prepreg laminate made of carbon fiber and a thermosetting resin has been proposed (see, for example, Patent Document 1). However, the carbon fiber prepreg laminate does not have sufficient X-ray transmission, and the amount of X-ray irradiation is small particularly in fields where photographing with soft X-rays (low energy X-rays) such as infants and breasts is required. Therefore, it was difficult to obtain a clear image. Further, in order to obtain a clear image with high contrast, it is necessary to increase the amount of X-ray irradiation, and there is a risk of exposure to the human body. Furthermore, X-ray equipment members are members that are directly carried and handled by X-ray technicians and are required to be lightweight. However, carbon fiber prepreg laminates do not lead to sufficient weight reduction. There was a problem that it took a big burden.

  In order to solve such problems, it has also been proposed to use molded products such as polyvinyl chloride and ABS resin having good X-ray permeability as members for X-ray equipment. When trying to ensure permeability, the required rigidity cannot be obtained, and thus the above problem has not been solved.

Further, there has been proposed a fiber reinforced resin plate material that is suitable for X-ray imaging cassettes that are less affected by charging and have less influence on the conductive storage phosphor (for example, see Patent Document 2). In addition, an X-ray imaging cassette having high-performance X-ray transmission has been proposed in which a front plate is made of a fiber reinforced resin reinforced with carbon fiber or the like, and its peripheral frame portion is molded with a thermoplastic resin. (For example, refer to Patent Document 3) None of these attempts to solve the above problem.
JP 60-32615 A JP-A-14-316376 JP-A-7-181629

  An object of the present invention is to provide a fiber-reinforced resin sandwich panel that is lightweight and thin with excellent X-ray permeability while maintaining rigidity. Another object of the present invention is to provide a fiber reinforced resin sandwich panel suitable for medical devices, members for X-ray devices, and the like.

The present invention employs the following means in order to solve such problems. That is,
(1) In a sandwich panel composed of a core material and a skin material containing a fiber reinforced resin in which a matrix resin is impregnated with reinforcing fibers arranged on both sides of the core material, the reinforcing fibers in the skin material are tensioned wherein the elastic modulus of the reinforcing fibers in the range of 200～850GPa, a reinforcing fiber content in said surface skin material is in the range of 40 to 80 wt%, the apparent density apparent density than the skin material to the core material is small with polypropylene or apparent density in the range of 0.23~0.46g / cm ³ uses polymethacrylimide any foamable resin is in the range of 0.03~0.12g / cm ^3, the heating the laminate comprising a core material and the skin material, a fiber reinforced resin sand overall thickness of the sandwich panel molded during pressure圧同 is being in the range of 0.5~5mm Touch panel.
(2) The skin material is a fiber reinforced resin having a single layer structure or a multi-layer laminated structure, and at least one layer in the fiber reinforced resin is a fiber reinforced resin layer containing continuous reinforcing fibers. The sandwich panel made of fiber-reinforced resin as described in (1) above.
(3) The fiber reinforced resin sandwich panel according to (2), wherein the fiber reinforced resin layer including the continuous reinforced fibers includes reinforced fibers aligned in one direction.
(4) The fiber reinforced resin layer in the skin material is arranged symmetrically with respect to the neutral surface of the sandwich panel, and the fiber reinforced resin layer containing continuous reinforcing fibers is in a symmetrical position with respect to the neutral surface. The fiber reinforced resin sandwich panel as described in (3) above, wherein the angle formed by the orientation directions of continuous reinforcing fibers in the fiber reinforced resin layer is within ± 3 °.
(5) The thickness of the skin material is in the range of 0.02 to 1.25 mm, and the total thickness of the skin material disposed on both surfaces of the core material is in the range of 0.4 to 50% of the total thickness of the sandwich panel. The fiber reinforced resin sandwich panel according to any one of (1) to (4), wherein the sandwich panel is inside.
(6) The ratio (Al equivalent (mmAl) / total thickness (mm)) of Al equivalent (mmAl) of the sandwich panel to the total thickness (mm) of the sandwich panel at an X-ray irradiation voltage of 60 kV is 0.003 to 0.14 mmAl The fiber-reinforced resin sandwich panel according to any one of the above (1) to (5), which is in a range of / mm.
(7) The sandwich panel made of fiber-reinforced resin according to any one of (1) to (6), wherein an apparent density of the sandwich panel is in a range of 0.1 to 1.4 g / cm ^3. .

  Further, the neutral surface represents a surface that does not stretch or contract when the member receives a bending moment.

  The projected area of the sandwich panel is the area of the surface having the maximum area of the sandwich panel.

  Further, the Al equivalent represents the thickness of aluminum having the same shielding ability as the substance in question under the same irradiation conditions.

  According to the fiber reinforced resin sandwich panel of the present invention, the skin material is made of a highly rigid fiber reinforced resin, the core material is made of a resin having an apparent density lower than that of the skin material, and the overall thickness is reduced. Further, it is possible to provide a fiber reinforced resin sandwich panel excellent in light weight and X-ray permeability while maintaining rigidity.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a fiber reinforced resin sandwich panel.

  In FIG. 1, a fiber reinforced resin sandwich panel uses a fiber reinforced resin in which a reinforcing fiber is impregnated with a matrix resin as a skin material 1, and the fiber reinforced resin in which the skin material 1 is arranged on both sides of a resin that is a core material 2. It is a resin plate material.

  The skin material 1 is for ensuring high rigidity. As the reinforcing fiber, the reinforcing fiber having a tensile modulus of 200 to 850 GPa is included in the range of 40 to 80% by weight with respect to the skin material 1. It is necessary to be When a reinforcing fiber having a tensile modulus of less than 200 Gpa is used, the required high rigidity cannot be ensured while maintaining lightness. On the other hand, when the tensile modulus of elasticity exceeds 850 GPa, the compressive strength of the reinforcing fibers is weak and easily broken, so that it is difficult to impregnate the reinforcing fibers with a matrix resin and mold the fiber reinforced resin. In addition, even if a reinforcing fiber having a tensile modulus of 200 to 850 GPa is used, if the weight content is less than 40%, the necessary high rigidity is secured while maintaining the lightness as described above. Can not do it. On the other hand, when the weight content of the reinforcing fibers exceeds 80%, it becomes difficult to uniformly impregnate the reinforcing fibers with the matrix resin, and the strength of the sandwich panel after molding and the appearance quality are extremely inferior. Quality problems may occur.

  Here, the reinforcing fiber is carbon fiber, glass fiber, organic high modulus fiber (for example, polyaramid fiber “Kevlar” manufactured by DuPont, USA), alumina fiber, silicon carbide fiber, boron fiber, silicon carbide fiber, etc. From these, those having the above strength and elastic modulus may be used alone, or a plurality of them may be used in combination and the weight average strength and the weight average elastic modulus are in the above range. You may make it become inside. In particular, in order to ensure light weight while maintaining high rigidity, it is preferable to use carbon fiber having a high specific elastic modulus, which is a ratio of elastic modulus to density, such as polyacrylonitrile (PAN-based), pitch-based, cellulose System, hydrocarbon-grown vapor-grown carbon fiber, graphite fiber, and the like, and two or more of these may be used in combination. Preferably, a PAN-based carbon fiber having a good balance between rigidity and price is preferable. Further, synthetic fibers such as polyamide fiber, polyester fiber, acrylic fiber, polyolefin fiber, vinylon fiber, and organic natural fiber may be used in combination.

  Further, as the reinforcing fiber of the skin material, continuous reinforcing fiber or discontinuous reinforcing fiber can be used, and both may be combined, but the skin material has a single layer structure or a multi-layer structure. It is a fiber-reinforced resin, and at least one layer in the fiber-reinforced resin is preferably a fiber-reinforced resin layer containing continuous reinforcing fibers. This is because by having a fiber-reinforced resin layer containing continuous reinforcing fibers, the strength and elastic modulus can be designed more efficiently. As a form of continuous reinforcing fibers, it is preferable to include reinforcing fibers arranged in one direction and reinforcing fibers of fabrics.

As the matrix resin, a thermosetting resin or a thermoplastic resin can be used. Specific examples include epoxy resins, phenol resins, unsaturated polyester resins, vinyl ester resins, ABS resins, polyethylene terephthalate resins, nylon resins, cyanate resins, benzoxazine resins, maleimide resins, polyimide resins, and the like. Preferably, it is a resin that is cured by heat or an external energy such as light or electron beam with a thermosetting resin such as an epoxy resin to form a three-dimensional cured product, but is not particularly limited.
Furthermore, the glass transition temperature of the matrix resin is preferably in the range of 80 to 250 ° C, more preferably 100 to 250 ° C. The reason for this is that the fiber reinforced resin sandwich panel of the present invention may be heat-treated at around 80 ° C. after molding. Therefore, if the glass transition temperature of the matrix resin is less than 80 ° C., This is because the rigidity of the sandwich panel is lowered, and there is a problem that deformation and warpage occur. On the other hand, if the temperature exceeds 250 ° C., the molding temperature becomes high, so that molding becomes difficult, causing the problem of warpage and the problem of cost increase.

For the core material 2, a thermosetting resin, a thermoplastic resin, a fiber reinforced resin, a foamable resin, or the like using the thermosetting resin or the thermoplastic resin can be used. For example, examples of the thermosetting resin include an epoxy resin, a phenol resin, an unsaturated polyester resin, and a vinyl ester resin. As the thermoplastic resin, polyamide resin, modified phenylene ether resin, polyacetal resin, polyphenylene sulfide resin, liquid crystal polyester, polyethylene terephthalate, polybutylene terephthalate, polyester resin such as polycyclohexanedimethyl terephthalate, polyarylate resin, polycarbonate resin, polystyrene resin, Styrenic resin such as HIPS resin, ABS resin, AES resin, AAS resin, acrylic resin such as polymethyl methacrylate resin, polyolefin resin such as vinyl chloride, polyethylene, polypropylene, modified polyolefin resin, ethylene / propylene copolymer, Ethylene / 1-butene copolymer, ethylene / propylene / diene copolymer, ethylene / carbon monoxide / diene copolymer Various types such as ethylene / glycidyl (meth) acrylate, ethylene / vinyl acetate / glycidyl (meth) acrylate copolymer, polyether ester elastomer, polyether ether elastomer, polyether ester amide elastomer, polyester amide elastomer, polyester ester elastomer There are elastomers. Is a fiber-reinforced resin, vinylon fiber reinforced resin, and the like tetronic fiber reinforced resin. Examples of the foamed resin include polyurethane, phenol, melamine, acrylic, polyethylene, polypropylene, polyvinyl chloride, polystyrene, ABS, polyetherimide, and polymethacrylimide. Specifically, a resin having an apparent density smaller than that of the skin material is used in order to ensure lightness and X-ray transparency. Preferably the apparent density of the core material 2 is within the range of 0.03~1.4g / cm ^3, and more preferably in the range of 0.05~1.2g / cm ^3. When the apparent density of the core material 2 is in the above range, it is possible to ensure lightness and X-ray transparency while maintaining rigidity.

  The fiber reinforced resin used for the skin material 1 is used by impregnating the reinforcing fiber with the matrix resin, and can be configured by laminating a single layer or a plurality of layers.

  The fiber reinforced resin sandwich panel of the present invention is constituted by arranging the fiber reinforced resin as the skin material 1 on both surfaces of the resin as the core material 2, and the overall thickness of the sandwich panel is in the range of 0.5 to 5 mm. More preferably, it is in the range of 1 to 3 mm. The thickness of the skin material 1 is preferably in the range of 0.02 to 1.25 mm, and the total thickness of the skin material 1 disposed on both surfaces of the core material 2 is 0.4 to 50% of the total thickness. It is preferable to be within the range.

  X-ray transparency is a parameter that represents the ease of X-ray transmission of the irradiated structure, and is determined by the molecular weight and thickness of the material. That is, since the apparent density of the fiber reinforced resin layer used for the skin material 1 is larger than that of the core material 2, the smaller the thickness of the skin material 1, the lighter can be ensured and the X-rays are easily transmitted. Furthermore, the smaller the overall thickness of the sandwich panel, the better the lightness and X-ray transmission. When used as a member for X-ray equipment, a clear image with high contrast can be obtained with a low X-ray dose. Therefore, when the thickness of the skin material 1 is less than 0.02 mm, high rigidity cannot be ensured, and when it exceeds 1.25 mm, high rigidity can be maintained, but lightness and X-rays can be maintained. There is a problem that the transparency cannot be secured. Even if the thickness of the skin material 1 is in the range of 0.02 to 1.25 mm, if the total thickness of the skin material 1 is less than 0.4% of the total thickness of the sandwich panel, it is high as described above. If the rigidity cannot be ensured and exceeds 50%, high rigidity can be maintained, but lightness and X-ray transparency cannot be ensured.

  Further, the fiber reinforced resin layer in the skin material is arranged symmetrically with respect to the neutral surface of the sandwich panel, and the fiber reinforced resin layer containing continuous reinforcing fibers is a fiber in a symmetrical position with respect to the neutral surface. The angle formed by the orientation direction of continuous reinforcing fibers in the reinforcing resin layer is preferably within ± 3 °. When the angle formed by continuous reinforcing fibers is within ± 3 °, it is possible to reduce sandwich panel warpage after molding, which is a problem in quality, and to obtain a molded product with excellent in-plane rigidity balance. be able to.

The ratio of the projected area (mm ² ) of the sandwich panel of the present invention to the total thickness (mm) of the sandwich panel (projected area (mm ² ) / total thickness (mm)) is 4,500 to 2,000,000 mm ² / The ratio of Al equivalent (mmAl) to the total thickness (mm) of the sandwich panel (Al equivalent (mmAl) / total thickness (mm)) at 0.002 to 1.4 mmAl / Mm is preferable.

Further, it is preferable that the apparent density of the sandwich panel of the present invention is in the range of 0.1~1.4g / cm ^3, and more preferably in a range of 0.3~1.2g / cm ^3. This is because light weight and X-ray transparency can be secured while maintaining high rigidity.

It is important that the sandwich panel is manufactured by laminating the skin material 1 and the core material 2 and then simultaneously forming them by heating and pressing using a hot press device and / or an autoclave device. By performing simultaneous molding, a low-cost fiber reinforced resin sandwich panel can be provided.

The measuring method of the tensile elasticity modulus of the carbon fiber used for the Example and the comparative example, the glass transition temperature of an epoxy resin, and the carbon fiber content of a fiber reinforced resin is shown below.
(A) Tensile modulus The tensile modulus was measured according to the resin-impregnated fiber bundle test method of the JIS R 7601 carbon fiber test method. The test piece length was 200 mm, the number of tests was 5 times, and the average value was adopted.
(B) Glass transition temperature The glass transition temperature was measured according to the method for measuring the transition temperature of JIS K 7121 plastic. The diameter of the test piece was 0.5 mm, the number of tests was 3, and the average value was adopted.
(C) Carbon fiber content rate The carbon fiber weight content rate was measured according to the test method of the prepreg consisting of JIS K7071 carbon fiber and epoxy resin. The test piece dimensions were 100 mm × 100 mm, the number of tests was three, and the average value was adopted.

<Example 1>
A fiber reinforced resin sandwich panel as shown in FIG. 1 was produced under the following conditions. The skin material 1 is composed of unidirectionally aligned carbon fibers having a tensile modulus of 230 Gpa and an epoxy resin having a glass transition temperature of 135 ° C., with a basis weight of 180 g / m ² , a carbon fiber content of 70% by weight, and an apparent density. A prepreg having a thickness of 1.58 g / cm ³ is formed at 0 ° / 90 ° / core symmetrically with respect to the neutral plane on both sides of the core 2 which is a polypropylene foam (density 0.30 g / cm ³ , thickness 2.0 mm). / 90 ° / 0 °, and this laminate was held at 130 ° C. for 3 minutes without applying pressure, and then held at 130 ° C. for 60 minutes while applying a surface pressure of 11.4 kg / cm ^2. A fiber reinforced resin sandwich panel was simultaneously molded and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel was 1.8 mm, the total thickness of the skin material 1 was 0.45 mm, the apparent density of the core material 2 was 0.46 g / cm ³ , and the projected area of the sandwich panel was 171000 mm ² . .

The apparent density of the obtained sandwich panel was 0.74 g / cm ³ . As a result of irradiating X-rays at 60 kV using an X-ray irradiation device (Toshiba diagnostic X-ray high voltage device KXO-30F) and measuring with a dosimeter (The 2025 Measurement System manufactured by Radcal Corporation), the Al equivalent is 0. .13 mm Al, and the ratio of the Al equivalent to the total thickness of the sandwich panel was 0.074 mm Al / mm. Further, in accordance with the bending test method for JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 92 mm was cut so that the carbon fiber direction of the outermost layer was the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 80 mm. As a result, the flexural modulus was 44 Gpa, and it was excellent in lightness and X-ray permeability while maintaining high rigidity.

<Example 2>
A fiber reinforced resin sandwich panel as shown in FIG. 1 was produced under the following conditions. The skin material 1 is composed of unidirectionally aligned carbon fibers having a tensile modulus of 230 Gpa and an epoxy resin having a glass transition temperature of 135 ° C., with a basis weight of 180 g / m ² , a carbon fiber content of 70% by weight, and an apparent density. A prepreg having a thickness of 1.58 g / cm ³ is symmetrically formed in a neutral plane on both sides of the core material 2 which is a polymethacrylimide foam (density 0.12 g / cm ³ , thickness 1.5 mm). Core material / Laminated at 90 ° / 0 °, and then this laminate was held at 130 ° C. for 3 minutes without applying pressure, and then held at 130 ° C. for 60 minutes while being pressurized at a surface pressure of 11.4 kg / cm ^2. Thus, a fiber reinforced resin sandwich panel was simultaneously molded and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel was 1.8 mm, the total thickness of the skin material 1 was 0.45 mm, the apparent density of the core material 2 was 0.10 g / cm ³ , and the projected area of the sandwich panel was 171000 mm ² . .

The apparent density of the obtained sandwich panel was 0.47 g / cm ³ . As a result of measuring the Al equivalent by the same measurement method as in Example 1, the Al equivalent was 0.085 mm Al, and the ratio of the Al equivalent and the total thickness of the sandwich panel was 0.047 mm Al / mm. Further, in accordance with the bending test method for JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 92 mm was cut so that the carbon fiber direction of the outermost layer was the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 80 mm. As a result, the flexural modulus was 44 Gpa, and it was excellent in lightness and X-ray permeability while maintaining high rigidity.

< Comparative Example 1 >
A fiber reinforced resin sandwich panel as shown in FIG. 1 was produced under the following conditions. The skin material 1 is composed of unidirectionally aligned carbon fibers having a tensile modulus of 230 Gpa and an epoxy resin having a glass transition temperature of 135 ° C., with a basis weight of 180 g / m ² , a carbon fiber content of 70% by weight, and an apparent density. A prepreg having a thickness of 1.58 g / cm ³ is 0 ° / 90 ° / core material / symmetrically with respect to the neutral plane on both surfaces of the core material 2 made of ABS resin (density 1.1 g / cm ³ , thickness 1.4 mm). After laminating at 90 ° / 0 °, this laminate was held at 130 ° C. for 3 minutes without applying pressure, and then held at 130 ° C. for 60 minutes while pressing at a surface pressure of 11.4 kg / cm ^2. A reinforced resin sandwich panel was formed at the same time and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel was 1.8 mm, the total thickness of the skin material 1 was 0.45 mm, the apparent density of the core material 2 was 1.05 g / cm ³ , and the projected area of the sandwich panel was 171000 mm ² . .

The apparent density of the obtained sandwich panel was 1.21 g / cm ³ . As a result of measuring the Al equivalent by the same measurement method as in Example 1, the Al equivalent was 0.21 mm Al, and the ratio of the Al equivalent and the total thickness of the sandwich panel was 0.121 mm Al / mm. Further, in accordance with the bending test method for JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 92 mm was cut so that the carbon fiber direction of the outermost layer was the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 80 mm. As a result, the flexural modulus was 46 Gpa, and it was excellent in lightness and X-ray permeability while maintaining high rigidity.

<Example 3 >
A fiber reinforced resin sandwich panel as shown in FIG. 1 was produced under the following conditions. The skin material 1 is composed of unidirectionally aligned carbon fibers having a tensile modulus of 230 Gpa and an epoxy resin having a glass transition temperature of 135 ° C., with a basis weight of 180 g / m ² , a carbon fiber content of 70% by weight, and an apparent density. A prepreg of 1.58 g / cm ³ is symmetric with respect to the neutral plane on both sides of the core 2 which is a polypropylene foam (density 0.23 g / cm ³ , thickness 5.0 mm). After laminating at 90 ° / 0 °, this laminate was held at 130 ° C. for 3 minutes without applying pressure, and then held at 130 ° C. for 60 minutes while pressing at a surface pressure of 11.4 kg / cm ^2. A reinforced resin sandwich panel was formed at the same time and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel was 3 mm, the total thickness of the skin material 1 was 0.45 mm, the apparent density of the core material 2 was 0.46 g / cm ³ , and the projected area of the sandwich panel was 171000 mm ² .

The apparent density of the obtained sandwich panel was 0.63 g / cm ³ . As a result of measuring the Al equivalent by the same measuring method as in Example 1, the Al equivalent was 0.19 mm Al, and the ratio of the Al equivalent and the total thickness of the sandwich panel was 0.063 mm Al / mm. Further, according to the bending test method of JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 140 mm is cut out so that the carbon fiber direction of the outermost layer is the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a distance between fulcrums of 100 mm. As a result, the flexural modulus was 30 Gpa, and it was excellent in lightness and X-ray permeability while maintaining high rigidity.

<Example 4 >
A fiber reinforced resin sandwich panel as shown in FIG. 1 was produced under the following conditions. The skin material 1 is composed of unidirectionally aligned carbon fibers having a tensile modulus of 230 Gpa and an epoxy resin having a glass transition temperature of 135 ° C., with a basis weight of 180 g / m ² , a carbon fiber content of 70% by weight, and an apparent density. A prepreg of 1.58 g / cm ³ is 0 ° / 90 ° symmetrical to the neutral plane on both sides of the core 2 which is a polypropylene foam (density 0.46 g / cm ³ , thickness 1.0 mm). After laminating at 90 ° / 0 °, this laminate was held at 130 ° C. for 3 minutes without applying pressure, and then held at 130 ° C. for 60 minutes while pressing at a surface pressure of 11.4 kg / cm ^2. A reinforced resin sandwich panel was formed at the same time and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel was 1 mm, the total thickness of the skin material 1 was 0.45 mm, the apparent density of the core material 2 was 0.46 g / cm ³ , and the projected area of the sandwich panel was 171000 mm ² .

The apparent density of the obtained sandwich panel was 0.97 g / cm ³ . As a result of measuring the Al equivalent by the same measurement method as in Example 1, the Al equivalent was 0.097 mm Al, and the ratio of the Al equivalent and the total thickness of the sandwich panel was 0.097 mm Al / mm. Further, in accordance with the bending test method of JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 60 mm was cut out so that the carbon fiber direction of the outermost layer was the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 40 mm. As a result, the flexural modulus was 70 Gpa, and it was excellent in lightness and X-ray permeability while maintaining high rigidity.

<Comparative Example 2 >
It is composed of unidirectionally aligned carbon fiber having a tensile modulus of 230 Gpa, which is the same material as in Example 1, and an epoxy resin having a glass transition temperature of 135 ° C., and has a basis weight of 180 g / m ² and a carbon fiber content of 70 wt. %, Prepreg with an apparent density of 1.58 g / cm ³ and 16 layers alternately in the 0 ° direction and 90 ° direction (0 ° / 90 ° / 0 ° / 90 ° / 0 ° / 90 ° / 0 ° / 90 ° / 90 ° / 0 ° / 90 ° / 0 ° / 90 ° / 0 ° / 90 ° / 0 °), and then the laminate is held at 130 ° C. for 3 minutes without applying pressure. A fiber reinforced resin sheet was simultaneously molded by holding at 130 ° C. for 60 minutes while pressing at 4 kg / cm ² , and cut into a length of 380 mm and a width of 450 mm. The overall thickness of the plate was 1.8 mm, and the projected area of the plate was 171000 mm ² .

The apparent density of the obtained carbon fiber reinforced resin sheet was 1.58 g / cm ³ . As a result of measuring the Al equivalent by the same measurement method as in Example 1, the Al equivalent was 0.28 mm Al, and the ratio of the Al equivalent and the total thickness of the plate was 0.16 mm Al / mm. Further, in accordance with the bending test method for JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 92 mm was cut so that the carbon fiber direction of the outermost layer was the longitudinal direction, and a round indenter having a radius of 5 mm. A three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 80 mm. As a result, the flexural modulus is 127 Gpa, and high rigidity can be ensured, but light weight and X-ray transparency cannot be maintained.

<Comparative Example 3 >
It is composed of unidirectionally aligned carbon fiber having a tensile modulus of 230 Gpa, which is the same material as in Example 1, and an epoxy resin having a glass transition temperature of 135 ° C., and has a basis weight of 180 g / m ² and a carbon fiber content of 70 wt. % Of the prepreg having an apparent density of 1.58 g / cm ³ and a 0 ° / 90 ° core symmetrically with respect to the neutral plane on both surfaces of the core 2 made of aluminum (density 2.7 g / cm ³ , thickness 1.4 mm). Material / Laminate at 90 ° / 0 °, and then hold the laminate at 130 ° C. for 3 minutes without applying pressure, and then hold at 130 ° C. for 60 minutes while applying a surface pressure of 11.4 kg / cm ^2. A fiber reinforced resin sandwich panel was simultaneously molded and cut into a length of 380 mm and a width of 450 mm. The total thickness of the sandwich panel is 1.8 mm, the total thickness of the skin material 1 is 0.45 mm, the apparent density of the core material 2 is 2.7 g / cm ³ , and the projected area of the sandwich panel is 171000 mm ² there were.

The apparent density of the obtained sandwich panel was 2.42 g / cm ³ . The Al equivalent was measured by the same measurement method as in Example 1. As a result, the Al equivalent was 1.42 mm Al, and the ratio of the Al equivalent to the total thickness was 0.079 mm Al / mm. Further, according to the bending test method of JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 92 mm is cut out so that one fiber direction is long and the other fiber direction is short. Using a round indenter with a radius of 5 mm, a three-point bending test was performed at a test speed of 5 mm / min and a fulcrum distance of 80 mm. As a result, the flexural modulus is 98 Gpa and high rigidity can be ensured, but light weight and X-ray transparency cannot be maintained.

<Comparative example 4 >
A 1.6 mm thick, 0.90 g / cm ³ polypropylene sheet is used for the core material 2 and a sandwich panel is formed by symmetrically laminating 0.25 mm, 2.7 g / cm ³ aluminum sheets on both sides of the polypropylene sheet. It cut out to 380 mm and width 450 mm. The overall thickness of the sandwich panel was 2.1 mm, and the projected area of the sandwich panel was 171000 mm ² .

The apparent density of the obtained sandwich panel was 1.25 g / cm ³ . As a result of measuring the Al equivalent by the same measurement method as in Example 1, the Al equivalent was 0.57 mm Al, and the ratio of the Al equivalent and the total thickness of the sandwich panel was 0.27 mm Al / mm. Further, in accordance with the bending test method of JIS K 7074 carbon fiber reinforced plastic, a strip-shaped test piece having a width of 15 mm and a length of 104 mm was cut out, a round indenter having a radius of 5 mm was used, a test speed of 5 mm / min, and a distance between fulcrums. A three-point bending test was performed at 80 mm. As a result, the flexural modulus is 25 Gpa, the rigidity is low, and lightness and X-ray transparency cannot be maintained.

The results of Examples 1 to 4 and Comparative Examples 1 to 4 are summarized in Table 1.

  The present invention is not limited to members for medical devices and X-ray devices, but can be widely applied to parts and casings of electric / electronic devices, reinforcing materials for construction / civil engineering structures, etc. It is not limited.

It is a perspective view which shows the structural example of the fiber reinforced resin sandwich panel which concerns on this invention.

Explanation of symbols

1: Fiber reinforced resin (skin material)
2: Resin (core material)

Claims (7)

In a sandwich panel composed of a core material and a skin material including a fiber reinforced resin in which a matrix resin is impregnated with reinforcing fibers arranged on both sides of the core material, the reinforcing fiber in the skin material has a tensile elastic modulus. 200 to 850 GPa is included, the reinforcing fiber content in the skin material is in the range of 40 to 80% by weight, and the core material has an apparent density smaller than the skin material of 0.23. And using a foamable resin of either polypropylene in the range of ~ 0.46 g / cm ³ or polymethacrylamide having an apparent density in the range of 0.03 to 0.12 g / cm ³ , and the core material and the skin material consisting of heating the laminate, a fiber-reinforced resin Sandoi', wherein the total thickness of the molded sandwich panel during pressure圧同 is within the range of 0.5~5mm Panel. The skin material is a fiber reinforced resin having a single layer structure or a multi-layer laminated structure, and at least one layer in the fiber reinforced resin is a fiber reinforced resin layer containing continuous reinforcing fibers. The fiber reinforced resin sandwich panel according to claim 1. The fiber-reinforced resin sandwich panel according to claim 2, wherein the fiber-reinforced resin layer containing the continuous reinforcing fibers includes reinforcing fibers arranged in one direction. The fiber reinforced resin layer in the skin material is arranged symmetrically with respect to the neutral plane of the sandwich panel, and the fiber reinforced resin layer containing continuous reinforcing fibers is in a position symmetrical with respect to the neutral plane. 4. The fiber-reinforced resin sandwich panel according to claim 3, wherein the angle formed by the orientation directions of continuous reinforcing fibers in the layer is within ± 3 °. The thickness of the skin material is in the range of 0.02 to 1.25 mm, and the total thickness of the skin material disposed on both sides of the core material is in the range of 0.4 to 50% of the total thickness of the sandwich panel. The fiber-reinforced resin sandwich panel according to any one of claims 1 to 4. The ratio (Al equivalent (mmAl) / total thickness (mm)) of the Al equivalent (mmAl) of the sandwich panel to the total thickness (mm) of the sandwich panel at an X-ray irradiation voltage of 60 kV is 0.003 to 0.14 mm Al / mm. The fiber reinforced resin sandwich panel according to any one of claims 1 to 5, wherein the sandwich panel is within a range. The fiber-reinforced resin sandwich panel according to any one of claims 1 to 6, wherein an apparent density of the sandwich panel is in a range of 0.1 to 1.4 g / cm ³ .

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