JP6237130B2 - Composite plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a composite plate of zirconia and fiber reinforced plastics having high design properties, scratch resistance and impact resistance, and a method for producing the same.

  In recent years, there is an increasing demand for members having excellent scratch resistance and impact resistance in portable electronic devices such as smartphones. In particular, an exterior member of a portable electronic device has a thin plate shape with a thickness of 2 mm or less and must withstand a collision such as dropping, so that a material having particularly high impact resistance is required.

The materials used for the exterior member include metals, resins, and glass, but glass materials are widely used because of scratch resistance and high design. The glass material currently used is tempered glass tempered by ion exchange. In this tempered glass, a tempered layer of about several tens of μm is generated on the glass surface by ion exchange, and compressive stress is generated on the surface to prevent the progress of scratches. However, since the strengthening mechanism of tempered glass is derived from the tempered layer, there are the following problems and further improvements are required.
(1) If there is a scratch exceeding the reinforcing layer, there is a risk of immediate destruction.
(2) The glass itself has a Vickers hardness of about 600, and is easily scratched by contact with metal, concrete, etc., and the strength may be significantly reduced by scratches associated with use.
(3) In tempered glass, it cannot be processed after tempering.
(4) Even if chemically strengthened, the end face strength may be reduced due to the presence of processing flaws on the end face.
(5) Fine sharp fragments are generated by the breakage of tempered glass.
(6) Since the reinforcing treatment is performed after cutting and processing, surface irregularities are generated, and the design properties such as the reflected image are distorted are deteriorated.

  On the other hand, ceramics are widely used in industrial member applications because of their excellent heat resistance, wear resistance, and corrosion resistance. In particular, zirconia ceramics have high strength, high toughness, high hardness, and scratch resistance, and further, it is easy to improve the design by coloring, and therefore, the use of zirconia ceramics is increasing.

  In addition, the use of ceramics for exterior members such as portable electronic devices is also being studied. However, especially in the case of exterior members for portable electronic devices, if the members are made thicker to improve impact resistance, the members become heavier. It was not practical. Further, if the member is made thin for weight reduction, the member is not sufficiently resistant to impacts such as dropping and collision, and is easily cracked and cannot be used.

  For improving the impact resistance of ceramic members, a method similar to so-called laminated glass has been proposed in which a ceramic plate is joined to fiber-reinforced plastics to prevent the penetration of projectiles such as shells and bullets (for example, patents). Reference 1 and Patent Reference 2). Patent Document 1 reports that 8 mm thick alumina and silicon carbide are bonded to fiber reinforced plastics.

  An exterior member such as a portable electronic device is required to have resistance to free fall of an impact object of about the product's own weight (about 100 g). In the conventional method, thick ceramics must be used, so that the weight of the member increases and cannot be used as a portable exterior member. In order to reduce the weight, it is essential to improve the crack resistance with a thin plate, but hitherto, an impact resistant member that has improved the crack resistance against impacts such as dropping and collision in a zirconia plate with a thickness of 2 mm or less. And there was no manufacturing method.

  The present inventors have developed a composite plate having a light weight and high impact resistance by combining thin zirconia and fiber reinforced plastic. Furthermore, in order to maintain a high design property equivalent to that of bulk zirconia (only a zirconia sintered body having a thickness of 1 mm or more and not a composite plate), long-period flatness in the zirconia surface shape of the composite plate is required. The inventor found out that the present invention is important and has completed the present invention.

JP 2008-162164 A JP 2009-264692 A

  When zirconia ceramics is used as a member of a portable electronic device, it is necessary to increase the thickness of the member in order to improve its impact resistance, and there is still room for improvement. The present invention relates to a composite plate of a zirconia sintered body and fiber reinforced plastics, which are excellent in design and have improved impact resistance, particularly resistance to impact by impact, and a method for producing the same.

  In view of the above-mentioned problems, the present inventors have studied in detail the fracture phenomenon in dropping a steel ball of a zirconia thin plate. As a result, it was found that the ceramic plate was bent and a bending moment was generated by the drop impact of the steel ball, and tensile fracture occurred near the impact point on the back side of the impact surface. It was also found that the smaller the elastic modulus of the material, the greater the deformation due to the impact, and the longer the time taken to absorb the impact, the smaller the absolute value of the maximum tensile stress applied to the back surface of the impact surface.

  The inventors of the present invention have made extensive studies based on the above knowledge, and placed fiber reinforced plastics on the back surface of a zirconia thin plate (elastic modulus: 200 GPa), closely fixed them, and surface irregularities of the zirconia sintered body. By controlling the load, impact deformation capability is imparted to the zirconia thin plate to reduce the maximum tensile stress, and the back surface where the tensile stress is generated is made of fiber reinforced plastics, and the impact surface where the compressive stress is generated exclusively is the zirconia thin plate. The present invention has been completed by realizing the structure to improve the impact resistance of the thin zirconia sheet.

That is, the present invention is a composite plate having a thickness of 2 mm or less in which a zirconia sintered body and fiber reinforced plastics are laminated and fixed in close contact with each other, and the maximum value of the unevenness of the zirconia surface per cm ² is the maximum value. The present invention relates to a composite plate having a flatness of 50 μm or less and a manufacturing method thereof.

  Hereinafter, the present invention will be described in detail.

  The composite plate of the present invention is a composite plate having a thickness of 2 mm or less, in which a zirconia sintered body and fiber reinforced plastics are laminated and fixed in close contact with each other. For light weight, it is preferably 1.5 mm or less. More preferably, it is 1.0 mm or less.

  In the composite plate of the present invention, the ratio of the thickness of the zirconia sintered body to the thickness of the fiber reinforced plastics (zirconia sintered body thickness / fiber reinforced plastics thickness) is lightweight and impact resistant composite having excellent scratch resistance. Since a plate is obtained, it is preferably 0.01-1. Suppressing the increase in the apparent density of the composite plate due to the increase in the thickness of the zirconia sintered body, and the reduction in impact strength, and the scratch resistance due to the reduced thickness of the zirconia sintered body More preferably, it is 0.1-0.75 at the point which can suppress the fall of 0.1, More preferably, it is 0.1-0.5.

  The apparent density (ρ (composite plate)) of the composite plate of the present invention is calculated from the true density of the zirconia sintered body (ρ (zirconia)) and the true density of the fiber reinforced plastics (ρ (fiber reinforced plastics)). It is given by (1).

ρ (composite plate) = ρ (zirconia) × zirconia volume fraction + ρ (fiber reinforced plastics) × fiber reinforced plastic volume fraction
= Ρ (zirconia) x zirconia thickness fraction + ρ (fiber reinforced plastics) x fiber reinforced plastics thickness fraction (1)
The density of the fiber reinforced plastics varies depending on the type of plastics and the amount of fibers added, but a typical density is 0.9 to 2.45 g / cm ³ .

The apparent density of the composite plate of the present invention is preferably 4.3 g / cm ³ or less, particularly preferably 3.5 g / cm ³ , because it can provide a feeling of light weight enough to be used as an exterior member. It is as follows. Moreover, since glass is not used, it is excellent also about safety.

The maximum value of the unevenness per cm ^{2 on} the zirconia surface of the composite plate is 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less. By reducing the surface unevenness in this way, the zirconia becomes smooth, and the reflected image is specularly reflected on the zirconia without distortion, so that the design property comparable to that of the bulk can be maintained.

  In the composite plate of the present invention, the zirconia sintered body and the fiber reinforced plastics are closely fixed. Examples of the method for tightly fixing both of them include a fixing method using an adhesive, and a method of fixing plastics by dissolving them in heat, a solvent or the like and bringing them into close contact with a zirconia sintered body. When an adhesive is used, the thickness of the adhesive layer is preferably 200 μm or less. The thickness of the adhesive layer is preferably 100 μm or less, more preferably 50 μm or less. By tightly fixing in this manner, the zirconia sintered body and the fiber reinforced plastics are integrally deformed to absorb the impact, thereby improving the impact resistance.

  As the zirconia sintered body in the composite plate of the present invention, yttria-stabilized zirconia having both high strength, wear resistance, and high toughness is preferable, and by setting the yttria content to 2 to 10 mol% with respect to zirconia, Yttria-stabilized zirconia having high strength, wear resistance and high toughness can be obtained. A more preferable yttria content is 2 to 4 mol%. As the zirconia sintered body, a stabilizer other than yttria can be used. Examples of other stabilizers include calcia, magnesia, and ceria.

  The zirconia sintered body in the composite plate of the present invention may be zirconia containing at least one selected from the group consisting of a white pigment, a transition metal oxide, and a color pigment because designability can be improved. .

  Examples of white pigments include oxides such as alumina, silica, mullite, zinc oxide, and spinel. Examples of transition metal compounds include iron oxide, cobalt oxide, nickel oxide, manganese oxide, chromium oxide, vanadium oxide, and oxide. Examples of the color pigment include spinel complex oxides containing transition metals such as Fe, Co, Ni, and Mn, and rare earth oxides such as erbium, neodymium, and praseodymium. Further, zircon to which transition metal is added can be mentioned, and among these, alumina, silica, mullite, spinel, spinel composite oxide, rare earth oxide, and zircon to which transition metal is added are preferable.

  The relative density of the zirconia sintered body in the composite plate of the present invention is preferably 97% or more, and in order to further improve the scratch resistance, it is also caused by irregularities on the surface of the sintered body based on residual pores. In order to suppress a decrease in design properties during mirror finishing, 98% or more is more preferable, and 99% or more is even more preferable.

  The zirconia sintered body in the composite plate of the present invention has a Vickers hardness of preferably 1000 or more, more preferably 1100 or more, more preferably 1200 or more, in order to exhibit sufficient scratch resistance. Highly preferred.

  Examples of the fiber reinforced plastics used in the composite plate of the present invention include glass fiber reinforced plastics, carbon fiber reinforced plastics, aromatic polyamide fiber reinforced plastics, and cellulose fiber reinforced plastics. Carbon fiber reinforced plastics or glass fiber reinforced plastics that are easy to use industrially are preferred. Further, glass fiber reinforced plastics are preferable for members that require radio wave transmission.

  Examples of fiber reinforced plastics include unsaturated polyester thermosetting resins, epoxy resins, polyamide resins, phenolic resins, acrylic resins, silicones, polysulfone, polyethersulfone, and PET.

  On the other hand, examples of fibers that reinforce plastics include glass fibers, carbon fibers, cellulose fibers, aramid fibers, boron fibers, and polyethylene fibers. Examples of the method include finely cutting these fibers and uniformly coating the resin, or infiltrating the plastic with the fibers having directionality.

  The impact resistance (crack resistance) of the composite plate of the present invention is as follows. The composite plate is bonded onto an aluminum alloy with a double-sided tape having a thickness of 0.1 mm, and a 130 g steel ball can be freely dropped from any height. In the impact test, the height at which cracks occur in the zirconia sintered body (fracture height) is 10 cm or more, preferably 15 cm or more, and more preferably 20 cm or more. By using a breaking height of 10 cm or more, when used as a casing of a portable electronic device, impact resistance against dropping or collision can be imparted.

  Next, the manufacturing method of the composite plate of this invention is explained in full detail.

  The composite plate of the present invention can be produced, for example, by joining a thin plate made of a zirconia sintered body and fiber reinforced plastics at a temperature of 300 ° C. or lower using an adhesive. Examples of the adhesive used for bonding include an epoxy thermosetting adhesive, an acrylic adhesive that cures at room temperature, a cyanoacrylate adhesive, and an adhesive such as an ultraviolet curable resin. It is preferable to use an epoxy-based thermosetting adhesive in that the bonding strength between the zirconia sintered body and the fiber-reinforced plastics is high, and the heat resistance and impact resistance are also high. It is also possible to add a filler such as inorganic particles to the adhesive to improve the rigidity of the adhesive layer. In order to realize a higher adhesive force, it is preferable to clean the bonded surface by ultraviolet / ozone treatment or plasma treatment. Also, the bonded surface of zirconia can be cleaned by heating.

  Further, the fiber reinforced plastics can be melted with heat or a solvent and welded to the zirconia sheet. It is also possible to place a zirconia thin plate in the mold and pour the fiber-reinforced plastics imparted with fluidity into the mold for welding to obtain a joined body. In addition, a prepreg impregnated with fibers can be adhered to zirconia, and then cured by ultraviolet rays or heat to be polymerized to obtain a composite.

  The thin plate of the zirconia sintered body according to the composite plate of the present invention can be manufactured using a general ceramic molding method. For example, a press method, an extrusion method, a slurry casting method, an injection molding method, and a sheet molding method can be exemplified, and among these, a sheet molding method using a doctor blade is preferable. Specifically, a slurry obtained by mixing a zirconia powder and an organic binder is formed on a green sheet having a thickness of 1 mm or less with a doctor blade, and sintered at 1300 to 1500 ° C. to obtain a zirconia sintered body. After bonding to fiber reinforced plastics, the composite plate can be manufactured by grinding and polishing the surface of the zirconia sintered body. For the sintering, vacuum sintering, hot pressing, hot isostatic pressing (HIP) and the like can be used in addition to normal atmospheric sintering.

The zirconia sintered body used for the composite plate of the present invention is preferably one whose surface side is mirror-polished. As surface roughness which exhibits a mirror surface, Ra (arithmetic mean height) = 0.1 micrometer or less is preferable. The arithmetic average height is a value obtained by extracting a reference length from the roughness curve in the direction of the average line, and summing and averaging the absolute values of deviations from the average line of the extracted portion to the measurement curve. Moreover, the maximum value of the surface unevenness difference of the zirconia sintered body joined to the fiber reinforced plastic is 50 μm or less per 1 cm ² . Grinding and polishing zirconia by bonding to fiber reinforced plastics will easily cause warping and distortion due to residual stress due to processing, so the final shape is processed before bonding and the flattened material is bonded to fiber reinforced plastics It is preferable to do. In addition, when machining the zirconia side in a state of being bonded to the fiber reinforced plastic, it is preferable to perform grinding and polishing under conditions that do not leave residual stress as much as possible.

  Since the composite plate of the present invention is thin and has high impact resistance and scratch resistance, it can be used as a housing member for portable electronic devices such as smartphones, tablet terminals, notebook PCs, and small music players. Can do. It can also be used as an input device member such as a touch pad. Moreover, since the thing using glass fiber reinforced plastics has high radio wave permeability, it can be used also for members, such as a protection member of an antenna. Furthermore, by using colored zirconia, it is possible to use it as a watch member because it is easy to improve the design.

The three-dimensional surface shape of the zirconia composite plate of Example 1. The three-dimensional surface shape of the zirconia sintered body used in Example 1. The three-dimensional surface shape of the zirconia composite plate of Example 2. The surface profile of the composite plate of Reference Example 1. The surface shape of the zirconia sintered body of Reference Example 2.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Relative density)
Five zirconia sintered bodies were collected and the density of the sample was measured using the Archimedes method. The obtained density was determined as a relative density with respect to the true density. The true density of the sintered body using zirconia powder (product name “3YSE” manufactured by Tosoh Corporation) was set to 6.09 g / cm ³ . 3YSE is a system in which 0.25 wt% of alumina is added as an auxiliary to zirconia containing 3 mol% of yttria.
(Surface shape measurement)
The three-dimensional shape measurement of the surface unevenness of the composite plate was evaluated using ZygoNewView7100. The surface unevenness per cm ² was measured around the center of the test piece. For Comparative Example 1 with undulating undulations, the surface shape was measured by measuring the focal length using an optical microscope.
(Impact strength measurement)
The impact strength of the composite plate was evaluated using a steel ball drop test. For the steel ball drop test, a method similar to ISO14368-3 of the “Watch Glass Dimensions, Test Method” standard was applied. That is, a composite plate is fixed on a flat aluminum alloy (50 mm × 52 mm) having a thickness of 5 mm with a double-sided tape having a thickness of 0.1 mm (made by 3M, product number “4511-100”), and the center of the composite plate is fixed. A 130 g steel ball was dropped freely from an arbitrary height to the position, and the height at which the composite plate was broken was measured. The impact surface was mirror-polished to a surface roughness Ra = 0.02 μm or less.

Example 1
700 g of TZ-3YS-E (manufactured by Tosoh) powder, 14 g of a commercially available polycarboxylic acid ester type polymer dispersant as a dispersant, 3.5 g of commercially available polyethylene glycol mono-para-iso-octylphenyl ether as an antifoaming agent, 245 g of ethyl acetate and 245 g of ethyl acetate as a solvent, 49 g of butyral resin (polymerization degree: about 1000) powder as a binder, and 42 g of industrial dioctyl phthalate as a plasticizer were added and mixed in a ball mill for 48 hours. Using a doctor blade apparatus and a blade, polyethylene terephthalate (PET) was used as a carrier film, and a green sheet was formed on the carrier film.

The obtained green sheet was sintered by placing a weighted alumina setter on a porous alumina setter. Sintering is performed at room temperature to 450 ° C. at a heating rate of 5 ° C./h, held at 450 ° C. for 10 hours for degreasing, and from 450 ° C. to 1000 ° C., the heating rate is 50 ° C./h, It was held at 1000 ° C. for 5 hours and then held at 1450 ° C. for 2 hours for sintering. The density of the obtained zirconia sintered body was 6.085 g / cm ³ and the relative density was 99.9% or more.

  The obtained zirconia sintered body (thickness: about 0.5 mm) was cut into a size of 32 mm × 25 mm, and processed to a thickness of 0.321 mm using surface grinding and a mirror polishing machine. In order to remove the residual stress due to machining, the upper and lower surfaces were processed under equal conditions. Surface grinding was performed using a # 140 grindstone. When the grinding speed was high, the generation of residual stress was prominent and warping occurred, so the grinding speed was low. After grinding the upper and lower surfaces under the same conditions, mirror polishing was performed.

In the mirror polishing, the upper and lower surfaces were polished under the same polishing conditions using 9 μm, 6 μm, and 1 μm diamond abrasive grains using Tegra Force (Marumoto Strulus Co., Ltd.). The polishing conditions for the 9 μm and 6 μm abrasive grains were 10 minutes at a pressure of 3.5 N / cm ^2, and 1 μm was 10 minutes at a pressure of 2.8 N / cm ² . The thickness of the obtained sintered body was 0.250 mm, and the maximum value of the surface unevenness was a flat zirconia sintered body of 1.381 μm per cm ² .

Each surface of the obtained zirconia-zirconia-based sintered sheet and epoxy resin-based glass fiber reinforced plastics (manufactured by Nitto Shinko, epoxy / glass cloth laminate molded product SL-EC) was washed with acetone, and then epoxy-based A thermosetting resin (manufactured by Nagase ChemteX, product number “XN1245SR”) was evenly applied to the bonding surface, and the load was evenly applied to the upper and lower surfaces of the composite plate, and bonding was performed at 120 ° C. for 30 minutes. The obtained composite plate was cut to a size of 32 mm × 25 mm. The adhesive was not peeled off due to processing, and zirconia chipping was not observed. For the calculation of the apparent density, 2.0 g / cm ³ was used as the reinforced plastic density.

The prepared composite plate had a thickness of 0.900 mm, and each layer had a sintered body of 0.321 mm, an adhesive layer of 49 μm, and fiber reinforced plastics of 0.530 mm. The thickness of the zirconia sintered body / the thickness of the fiber reinforced plastic was 0.61. The apparent density of the composite plate was 3.35 g / cm ³ and the Vickers hardness was 1240. The maximum value of the surface unevenness of the obtained composite plate was 14.651 μm per 1 cm ² , and a flat composite plate having high design properties with little distortion of the reflected image was obtained.

  As a result of performing a steel ball drop test in increments of 5 cm, it was found to be 40 cm and exhibit high impact resistance. Further, a steel ball drop test was performed in which a healthy portion of the tested test piece was aimed at and dropped once from a steel ball drop height of 50 cm. There was no crack and the impact resistance was higher than that evaluated in 5 cm increments. It is considered that a high value was exhibited because the interface of the adhesive layer was not peeled off due to repeated impact tests.

Example 2
Black zirconia powder (manufactured by Tosoh Corporation, trade name “TZ-Black”) was molded by a mold press at a pressure of 50 MPa. The molded body was further molded by a cold isostatic press (CIP) with a pressure of 200 MPa. The obtained molded body was sintered in the air at a temperature rising rate of 100 ° C./h and a sintering temperature of 1400 ° C. for 1 hour. The obtained zirconia sintered body was subjected to double-side grinding and double-side polishing to a thickness of about 1 mm to obtain a zirconia plate. The density of the obtained zirconia sintered body was 5.993 g / cm ³ and the relative density was 99.0%. Here, the true density of black was set to 6.053 g / cm ³ .

Each surface of the obtained thin plate of zirconia sintered body and glass fiber reinforced plastic (manufactured by Nitto Shinko, epoxy / glass cloth laminated molded product SL-EC) was washed with acetone, and then an epoxy thermosetting resin (Nagase) A product number “XN1245SR” manufactured by Chemtex Co., Ltd.) was evenly applied to the bonding surface, and the load was evenly applied to the upper and lower surfaces of the composite plate, and bonding was performed at 120 ° C. for 30 minutes. Table 1 shows the thickness of each layer in the obtained composite plate. The obtained composite plate was cut to a size of 32 mm × 25 mm. By grinding and polishing the zirconia side of the cut composite plate, a composite plate of about 0.8 mm was finally obtained. Grinding and polishing were carried out under conditions that produce as little residual stress as possible. The adhesive was not peeled off due to processing, and zirconia chipping was not observed. For the calculation of the apparent density, 2.0 g / cm ³ was used as the reinforced plastic density.

The thickness of the produced composite plate was 0.817 mm, and the thickness of each layer was 0.270 mm of a zirconia sintered body, an adhesive layer of 37 μm, and fiber-reinforced plastics of 0.510 mm. The thickness of the zirconia sintered body / the thickness of the fiber reinforced plastic was 0.53. The apparent density of the composite plate was 3.23 g / cm ³ and the Vickers hardness was 1240. The maximum value of the difference in surface irregularities of the obtained composite plate was 11.107 μm per 1 cm ² , which was a flat composite plate, and a high design property with little distortion of the reflected image was obtained.

  As a result of performing a steel ball drop test in increments of 5 cm, it was found to be 40 cm and exhibit high impact resistance. Further, a steel ball drop test was performed in which a healthy portion of the tested test piece was aimed at and dropped once from a steel ball drop height of 50 cm. There was no crack and the impact resistance was higher than that evaluated in 5 cm increments. It is considered that a high value was exhibited because the interface of the adhesive layer was not peeled off due to repeated impact tests.

Reference example 1
Using a method similar to that of Example 2, a zirconia composite plate with remarkably surface irregularities was produced so that residual stress was applied to the workpiece as grinding and polishing conditions. The produced zirconia composite plate had a low design property in which an image reflected by zirconia was distorted. As a result of measuring the surface shape of the composite plate with an optical microscope, the maximum value of the surface unevenness per 1 cm ² was about 72 μm. FIG. 4 shows the surface profile with the most unevenness as the two-dimensional data.

Reference example 2
The surface uneven | corrugated image of the bulk zirconia sintered compact (thickness 1mm) produced in the procedure similar to Example 2 is shown. The difference between the maximum surface irregularities per 1 cm ² was 7.023 μm, and the reflection image on the surface of the sintered body showed high design without distortion.

  The composite plate of the zirconia sintered body and fiber reinforced plastics of the present invention is highly designed and lightweight, and has impact resistance and scratch resistance. Therefore, it is suitable for small and thin members such as portable electronic devices and watch members. It can be preferably used.

Claims (13)

A composite plate having a thickness of 2 mm or less in which a zirconia sintered body and fiber reinforced plastics are laminated and fixed in close contact with each other, and the maximum difference in surface irregularities of the zirconia sintered body is 50 μm or less per 1 cm ² Is a composite plate.   2. The composite plate according to claim 1, wherein the thickness ratio of the zirconia sintered body to the fiber reinforced plastics (zirconia sintered body thickness / fiber reinforced plastics thickness) is 0.01 to 1. 3. The composite plate according to claim 1, wherein an apparent density is 4.3 g / cm ³ or less.   The composite plate according to any one of claims 1 to 3, wherein the zirconia sintered body is zirconia containing 2 to 10 mol% of yttria with respect to zirconia.   The composite plate according to any one of claims 1 to 4, wherein the zirconia sintered body is zirconia containing at least one selected from the group consisting of a white pigment, a transition metal oxide, and a color pigment. The composite plate according to any one of claims 1 to 5, wherein a relative density with respect to a true density of the zirconia sintered body is 97% or more.   The composite plate according to any one of claims 1 to 6, wherein the zirconia sintered body has a Vickers hardness of 1000 or more.   The composite plate according to any one of claims 1 to 7, wherein the fiber reinforced plastic is glass fiber reinforced plastic or carbon fiber reinforced plastic.   The composite plate according to any one of claims 1 to 8, which exhibits high impact resistance having a fracture height of 10 cm or more in a test in which a 130 g steel ball is freely dropped.   The composite plate according to any one of claims 1 to 9, wherein the zirconia sintered body and the fiber reinforced plastics are bonded at a temperature of 300 ° C or lower using an epoxy thermosetting adhesive. Production method.   11. The composite plate according to claim 10, wherein the zirconia sintered body is obtained by forming a slurry obtained by mixing zirconia powder and an organic binder on a green sheet having a thickness of 1 mm or less and then sintering at 1300 to 1500 ° C. Method.   A housing of a portable electronic device using the composite plate according to claim 1.   A timepiece member using the composite plate according to claim 1.

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