JP2010247475A - Compound fiber-reinforced plastic and reinforced panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound fiber-reinforced plastic having a linear expansion coefficient equivalent to a linear expansion coefficient of an inorganic crystal molding for scintillator, lightweight, and equipped with excellent mechanical characteristics. <P>SOLUTION: The compound fiber-reinforced plastic is composed of laminating at least two inorganic fiber prepregs having different linear expansion coefficients. The linear expansion coefficients have anisotropy. A linear expansion coefficient of a specific direction is not less than 3 ppm/K and not more than 40 ppm/K, which is larger than a linear expansion coefficient of a direction orthogonal to the specific direction. The tensile strength is not less than 70 MPa. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite fiber reinforced plastic (composite FRP) formed by laminating inorganic fiber prepregs. Specifically, the present invention relates to a reinforcing panel that protects an inorganic crystal formed body for scintillators used in radiation detectors such as X-rays, γ-rays, and β-rays.

Scintillators are widely used in medical and industrial X-ray imaging and radiation detection apparatuses that detect radiation such as X-rays, γ-rays, α-rays, and β-rays. In the scintillator, inorganic crystal forming such as BGO crystal (Bi ₄ Ge ₃ O ₁₂ ), LSO crystal (Lu ₂ SiO ₅ ), GSO crystal (Gd ₂ SiO ₅ ), PWO crystal (PbWO ₄ ), NaI crystal, CsI crystal, etc. This inorganic crystal shaped body absorbs the energy of radiation in a specific wavelength region, generates visible light or an optical signal close to it, and determines the amount of energy of the target radiation from the optical signal. Can be detected.

  The inorganic crystal molded body described above is mechanically fragile, and particularly when used in the space field, the inorganic crystal body is easily damaged by a load or impact such as gravity applied when launching a satellite. It has been used by reinforcing the outer surface of the molded body with a high-strength material. As these reinforcing materials, fiber reinforced plastics which are excellent in mechanical properties, chemical properties, impact resistance and the like, have a relatively small specific gravity, are light and have high rigidity are used. (Non-patent literature)

  However, the conventional fiber reinforced plastic reinforcing material has a big problem due to the difference between the linear expansion coefficient of the inorganic crystal formed body and the linear expansion coefficient of the fiber reinforced plastic reinforcing material.

  That is, as described above, the shape due to thermal expansion / contraction generated in the inorganic crystal molded body due to the generation of thermal energy due to the load or impact such as gravity applied at the time of launch of the satellite, or the temperature change during the flight in space. This is a fatal problem in that the change and the linear expansion characteristic of the reinforcing material cannot follow the separation of the reinforcing material from the inorganic crystal molded body, the detection accuracy is reduced, or the destruction occurs.

As a method for controlling the linear expansion coefficient of a fiber reinforced plastic material, in Patent Document 1, in a grid structure made of fiber reinforced plastic, thermal strain between the reinforced fiber constituting the fiber reinforced plastic and the resin base material is balanced. ^Has proposed a grid structure characterized in that the overall thermal expansion coefficient is in the range of 0 ± 1 × 10 ⁻⁷ / K. However, although it is possible to suppress expansion by reducing the linear expansion coefficient, when used as a reinforcing material for an inorganic crystal molded body for scintillators, thermal strain of the inorganic crystal molded body due to temperature changes in the use environment or The amount of change in shape cannot be absorbed.

  Further, in Patent Document 2, at least one of two or more kinds of reinforcing fibers including a reinforcing fiber having a negative linear expansion coefficient is combined to thereby adjust one or two or more reinforcing fibers whose respective linear expansion coefficients are adjusted. An in-plane quasi-isotropic fiber reinforced resin composite material in which the sheet is combined to suppress the linear expansion coefficient has been proposed. In the above method, since the reinforcing fiber having a negative linear expansion coefficient is used, it is difficult to control the linear expansion coefficient in a large direction. At the same time, the in-plane quasi-isotropic fiber reinforced plastic has a predetermined mechanical property in any direction of the material, and at the same time has an isotropic linear expansion coefficient. It is difficult to follow the distortion.

JP20049453 WO00 / 64668

Internet "12.6 Hard X-ray Detector (HXD)" released

The present invention has been made in view of the above-mentioned background, and the object thereof is a composite having a linear expansion coefficient equivalent to that of an inorganic crystal molded body for scintillators and having light weight and excellent mechanical properties. It is an object to provide a fiber reinforced plastic.

  In order to achieve the above object, the invention of claim 1 is a composite fiber reinforced plastic (composite FRP) formed by laminating at least two kinds of inorganic fiber prepregs having different linear expansion coefficients, and the composite FRP has a linear expansion coefficient. Has an anisotropy, the linear expansion coefficient in a specific direction is 3 ppm / K or more and 40 ppm / K or less, is larger than the linear expansion coefficient in a direction orthogonal to the specific direction, and the tensile strength of the composite FRP is 70 MPa or more. It is characterized by being.

The composite FRP of the present invention has anisotropy in the linear expansion coefficient in a specific direction. The specific direction may be, for example, any of the X direction, the Y direction, and the Z direction, and refers to a direction that is susceptible to thermal influence (thermal expansion, thermal strain) in use conditions.

  In the present invention, the linear expansion coefficient in the specific direction is 3 ppm / K or more and 40 ppm / K or less, and is preferably larger than the linear expansion coefficient in the direction orthogonal to the specific direction. When the linear expansion coefficient is in the above range, a wide variety of structures and materials can be used when used as a reinforcing material for structures having different linear expansion coefficients. Moreover, it is because the thermal strain and thermal stress which generate | occur | produce by the anisotropy etc. of the shape aspect ratio or the linear expansion coefficient of the inorganic crystal molded object used for a scintillator can be relieved, for example.

  In the present invention, the composite FRP preferably has a tensile strength of 70 MPa or more. The tensile strength of the composite FRP can be designed to a desired value by changing the prepreg laminating direction and the type of inorganic fiber.

  The design of linear expansion coefficient and mechanical characteristics will be described below. For example, the typical linear expansion coefficient of carbon fiber reinforced plastic (CFRP), which is a typical fiber reinforced plastic, is about −2.0 to 2.0 ppm / K in the fiber direction, and the tensile strength is 800 to 4300 MPa. The specific gravity is 1.5 to 1.85. Further, the glass fiber reinforced plastic (GFRP) has a linear expansion coefficient of about 7 to 12 ppm / K in the fiber direction, a tensile strength of about 2000 MPa or less, and a specific gravity of 1.6 to 2.1.

  In producing the composite FRP of the present invention, in order to obtain the composite characteristics of CFRP and GFRP having the above characteristics, the lamination angle of the prepreg composed of each fiber (angle of fiber fabric or fiber bundle), the number of laminations, or It can be manufactured based on a precise design based on factors such as the lamination ratio of the prepreg of each fiber and the fiber diameter and material of each fiber.

  Based on the above design, in the composite FRP of the present invention, the proportion of carbon fiber is increased in order to improve the mechanical properties. Further, in order to improve the mechanical characteristics in a specific direction, the layers are laminated at an angle of 0 degree (relative to the direction of the fiber bundle).

  Moreover, in order to raise a linear expansion coefficient, it is necessary to increase the ratio of glass fiber. Furthermore, in order to improve only the linear expansion coefficient in a specific direction, it is necessary to design so that the direction of the glass fiber bundle is 0 degree.

  Moreover, in the reinforcement panel of the inorganic crystal molded body for scintillators which is one application of the composite FRP of the present invention, it is necessary to reduce the weight because it is mounted on a satellite and launched into space. In order to reduce the weight under such conditions, the ratio of glass fibers must be reduced. A desired composite FRP can be designed in consideration of the above factors.

  The composite FRP of the present invention has anisotropy in linear expansion coefficient, mechanical properties such as tensile strength are in-plane pseudo-isotropic, and higher properties are preferable. In other words, the linear expansion coefficient can follow the linear expansion coefficient of the inorganic crystal compact for scintillator, absorbs thermal strain and thermal deformation, and the mechanical characteristics as a reinforcing body have isotropic characteristics. It is preferable that the entire molded body can be protected.

  Next, the invention of claim 2 is the composite FRP according to claim 1, wherein the inorganic fiber is at least one inorganic fiber selected from carbon fiber, glass fiber, quartz fiber, and basalt fiber. To do. When used as a reinforcing panel for an inorganic crystal shaped body for a space satellite scintillator, it is desired to be lightweight and high in strength, so it is preferable to use carbon fibers and glass fibers. Each of these fibers may be a commercially available prepreg impregnated with a matrix resin.

  The inorganic fibers contained in the prepreg can be used in the form of filaments, blades, yarns, strands, filament bundles, spun yarns and the like. Moreover, you may use it, after processing into a woven fabric, a knitted fabric, a nonwoven fabric, etc.

  In addition, the ratio of the inorganic fiber and the matrix resin contained in the prepreg is preferably 45 to 75% by volume from the viewpoint of moldability, mechanical properties, linear expansion coefficient, and the like, and more preferably 50 to 65 volume% is more preferable. When the proportion of the inorganic fiber is 75% by volume or more, voids are likely to occur when the prepregs are laminated, causing a decrease in mechanical strength.

  As the matrix resin of the prepreg used in the present invention, unsaturated polyester, vinyl ester, epoxy, phenol, urea melamine, polyimide, copolymers thereof, modified products, or blended thermosetting resins can be used. . Among them, when used for a reinforcing panel of an inorganic crystal molded body for a scintillator mounted on a space satellite, an epoxy resin is more preferable because of an outgas problem affecting a base material and a measuring instrument in the satellite.

  Next, the invention of claim 3 is a reinforcing panel for an inorganic crystal formed body for scintillators, comprising the composite FRP according to any one of claims 1 to 2. When the composite FRP of the present invention is used as a reinforcing panel for protecting an inorganic crystal molded body for a scintillator mounted on a space satellite, the linear expansion coefficient has anisotropy. It can be suitably used because it absorbs the shape change and thermal strain caused by the anisotropy of the coefficient and the geometric shape anisotropy of the inorganic crystal compact and the satellite structure, and is high in strength and lightweight.

  Moreover, as an inorganic crystal molded body for scintillators, a crystal body such as BGO or LSO is used, and a reinforcing panel can be designed according to the mechanical or thermal characteristics of these crystal bodies.

  Next, the invention according to claim 4 is the reinforcing panel according to claim 3, wherein the reinforcing panel is fixed to the inorganic crystal formed body for scintillator with an adhesive. In the prior art, it was difficult to match the linear expansion coefficient between the inorganic crystal molded body for the scintillator and the reinforcing panel. The thermal strain due to was absorbed.

However, according to the present invention, the thermal strain of the inorganic crystal molded body for scintillator and the linear expansion coefficient of the reinforcing panel can be brought close to each other. Can be reinforced.

The thermal stress due to the linear expansion coefficient generated between the scintillator inorganic crystal and the FRP reinforcing material can be obtained from the following equation.
σ = EΔαΔT
In the formula, σ: thermal stress (MPa) generated between the reinforcing material and the inorganic crystal compact for scintillator
E: Young's modulus (GPa) of inorganic crystal compact for scintillator
Δα: Difference in linear expansion coefficient between reinforcing material and inorganic crystal compact for scintillator (/ K)
ΔT: Temperature change (K)
It is. Moreover, when providing a reflective layer on the surface of the inorganic crystal molded body for scintillators, it is necessary to consider the tensile strength and linear expansion coefficient of the reflective layer. Actually, this value is further increased or decreased depending on the geometric shape of the inorganic crystal molded body and the surrounding structure.

Since the temperature change of the inorganic crystal compact for a scintillator mounted on a space observation satellite is generally −40 ° C. to 60 ° C., the maximum temperature change is 60 ° C. when the composite FRP of this patent is used as a reinforcing panel. It is necessary to control the linear expansion coefficient of the reinforcing panel so that the value of the generated thermal stress is equal to or less than the tensile strength of the inorganic crystal molded body for scintillator.

  Next, the invention of claim 5 is the reinforcing panel according to claim 3, wherein a reflection layer is provided on the surface of the inorganic crystal molded body for scintillator, and the surface of the reflection layer and the reinforcement panel are fixed by an adhesive. It is characterized by. In order to more efficiently detect radiation in outer space, it is preferable to provide the reflective layer. Also, in the inorganic crystal formed body for scintillator provided with a reflective layer, in order to reinforce more strongly, it is preferable to directly adhere the reflective layer surface and the reinforcing panel surface with an adhesive.

  Next, the invention of claim 6 is the reinforcing panel according to claim 5, wherein the reflective layer is at least one reflective layer selected from barium sulfate, titanium oxide, an ESR material, and a fluororesin material. And

  Next, the invention according to claim 7 is the reinforcing panel according to claim 4 or 5, wherein the adhesive is at least one adhesive selected from epoxy, silicon, urethane, and acrylate adhesives. To do. The adhesive is selected depending on the environment to be used, and when used in aerospace applications, an epoxy adhesive is preferably used from the viewpoint of outgassing problems. In order to increase and stabilize the adhesive strength, the surface of the inorganic crystal formed body and the reinforcing panel may be subjected to surface treatment or primer treatment (adhesion aid) by etching or the like.

  Next, the invention of claim 8 is characterized in that in the composite panel according to any of claims 3 to 7, the thickness of the reinforcing panel is 0.6 mm or more and 4.0 mm or less. In addition to linear expansion coefficient, mechanical properties, and weight reduction, the reinforcing panel for inorganic crystal compacts for scintillators mounted on space satellites is required to have a compact outer shape. It is preferable that the thickness of the panel can be formed to 0.6 mm or more and 4.0 mm or less. This is because, while having an anisotropic linear expansion coefficient, the required mechanical properties can be satisfied and the weight can be reduced.

  The composite FRP of the present invention has an anisotropy in linear expansion coefficient, and has excellent characteristics such as light weight, high strength, and high rigidity. Therefore, the composite FRP is suitable as a reinforcing panel for inorganic crystal molded bodies for scintillators. Can be used.

The present invention will be described more specifically with reference to the following examples. In addition, this invention is not limited to this Example. Various characteristics of the present invention were performed using the measuring instruments and measurement conditions described below.

(1) Evaluation of linear expansion coefficient The linear expansion coefficient of the composite FRP was measured based on JIS K7197 using a thermal analyzer (Thermo puls TMA8310, manufactured by Rigaku Corporation).
(Measurement condition)
Load: 0.049N, temperature increase rate: 5 ° C / min
Cooling rate: 3 ° C / min
Measurement temperature: -50 to 100 ° C
Atmosphere: Nitrogen atmosphere (100 mL / min)
(2) Evaluation of tensile strength Using a tensile material tester Instron 4505 (manufactured by Instron Limited), the tensile strength was measured based on JIS K7164 (No. 6).
(Measurement condition)
Number of tests: n = 5
Tensile speed: 1mm
/ Min
Test piece size: thickness 1.2 mm, width 45 ± 0.5 mm, length 2 15 + 3-0 mm

As an inorganic crystal molded body for scintillator, a composite FRP optimum as a reinforcing panel of this crystal body was produced from various characteristics of the BGO crystal molded body. Various characteristics of the BGO crystal compact are shown in Table 1. Moreover, the thermal distortion etc. were computed from the BGO crystal molded object from the shape of 44 mm x 66 mm x 66 mm.

(Production of composite FRP)
Toray prepreg P3252S-15 (manufactured by Toray Industries, Inc.) was prepared as the raw material prepreg (A), and S-2 glass UD prepreg MTM28-1 / S2-GLASS UD (manufactured by Advanced Composites Group) was prepared as the raw material prepreg (B). The prepreg (A) is a unidirectional prepreg in which inorganic fibers are PAN-based carbon fibers T700S and an epoxy resin is used as a matrix resin. The prepreg (B) is a unidirectional prepreg in which the inorganic fibers are S-2 glass fibers and the matrix resin is used for the epoxy resin.

  In addition, the fiber mass content rate (Wf) of a prepreg (A) is 66.5%. The prepreg (B) resin content (Rc) is 30%.

  Using the above-mentioned two kinds of raw material prepregs, the prepregs (A) and (B) were laminated by putting them into molds that were each cut to □ 200 mm and subjected to release treatment. The lamination method was a total of nine prepregs, with the angle relative to the fiber orientation direction being 0 / + 45 / −45 / 90/0/90 / −45 / + 45/0 degrees. In the above-mentioned laminated state, the prepreg (B) was laminated in the 0 degree direction, and the prepreg (A) was laminated at a portion matching other angles to produce a laminated body of prepregs (A) and (B).

  Then, after the laminated body was vacuum-backed, the composite FRP (a) having a thickness of 1.2 mm was cured by being pressurized at a pressure of 588 kPa and heated at a temperature of 130 ° C. for 2.5 hours while being kept in a vacuum. ) Was produced.

  As a result of measuring the linear expansion coefficient of the composite FRP (a), the linear expansion coefficient in the direction of 0 degree of the fiber was 5.4 ppm / K, and the linear expansion coefficient in the 90 degree direction of the fiber was 4. It was 1 ppm / K.

  Moreover, the tensile strength of the fiber orientation direction 0 degree direction was 597 MPa, and the fiber tensile direction 90 degree direction tensile strength was 553 MPa.

  Since the linear expansion coefficient of the composite FRP (a) produced in this example is 3.46 ppm / K or less even when the difference from the linear expansion coefficient of the BGO crystal compact in Table 1 is the largest, it is a space observation satellite. Even when the temperature change occurring when used in the case of 60 ° C. was the maximum, the thermal stress was 23.2 MPa or less, so it was confirmed that the BGO crystal compact was not destroyed.

(Comparative Example 1)
Using only the prepreg (A), the angle with respect to the orientation direction of the fiber was laminated at 0 / + 45 / −45 / 90/90 / −45 / + 45/0, and the subsequent production conditions were the same as in Example 1 and the composite FRP (B) was produced.

  The thickness of the composite FRP (b) was 1.1 mm, and the linear expansion coefficient was 2.3 ppm / K in both the 0 degree and 90 degree directions of the fiber. The tensile strength was 829 MPa in both the 0 degree direction and the 90 degree direction of the fiber orientation direction.

  When this composite FRP (b) is used as a reinforcing panel for the BGO crystal compact shown in Table 1, even when the difference between the linear expansion coefficient of the BGO crystal compact and the composite FRP (b) is the largest. Since it is 3.46 ppm / K or more, the thermal stress becomes 23.2 MPa or more when the maximum temperature change generated when used in a space observation satellite is 60 degrees C. Therefore, the BGO crystal compact The structural destruction of is expected.

  The composite FRP of the present invention can be used for reinforcing panels such as detectors using X-rays such as X-rays and CT, and as other fields of application, reinforcement of inorganic crystal compacts of scintillators used for space observation, etc. It can use suitably for a panel etc.

Claims (8)

  A composite fiber reinforced plastic (composite FRP) formed by laminating at least two types of inorganic fiber prepregs having different linear expansion coefficients, wherein the composite FRP has anisotropy in the linear expansion coefficient, and a linear expansion coefficient in a specific direction The composite FRP is characterized in that is 3 ppm / K or more and 40 ppm / K or less, is larger than the linear expansion coefficient in the direction orthogonal to the specific direction, and the composite FRP has a tensile strength of 70 MPa or more.   The composite FRP according to claim 1, wherein the inorganic fiber is at least one inorganic fiber selected from carbon fiber, glass fiber, quartz fiber, and basalt fiber.   A reinforcing panel of an inorganic crystal formed body for scintillators, comprising the composite FRP according to claim 1. The reinforcing panel according to claim 3, wherein the reinforcing panel is fixed to an inorganic crystal formed body for scintillator with an adhesive.   The reinforcing panel according to claim 3, wherein a reflection layer is provided on a surface of the inorganic crystal formed body for scintillator, and the surface of the reflection layer and the reinforcement panel are fixed by an adhesive.   The reinforcing panel according to claim 5, wherein the reflective layer is at least one reflective layer selected from barium sulfate, titanium oxide, an ESR material, and a fluororesin material.   The reinforcing panel according to claim 4 or 5, wherein the adhesive is at least one adhesive selected from an epoxy, silicon, urethane, and acrylate adhesive.   The reinforcing panel according to any one of claims 3 to 7, wherein a thickness of the reinforcing panel is 0.6 mm or greater and 4.0 mm or less.