Composite plate and production method therefor

Abstract

A composite plate having a thickness of no more than 2 mm, and having laminated therein a zirconia sintered body, an adhesive layer, and a base material, the elasticity of the base material being no more than 100 GPa, and the apparent density of the composite plate being no more than 4.3 g/cm.sup.3.

Claims

1. A composite plate comprising a laminate including a zirconia sintered body, an adhesive layer, and a base material having an elastic modulus of 100 GPa or less, and the composite plate has a thickness of 2 mm or less, wherein the base material comprising tempered glass, the zirconia sintered body and the base material are bonded to each other through the adhesive layer, a ratio of thickness of the zirconia sintered body to a thickness of the base material (the thickness of the zirconia sintered body/the thickness of the base material) is 0.1 to 0.88 and wherein the composite plate has an apparent density of 4.3 g/cm.sup.3 or less.

2. The composite plate according to claim 1, wherein the zirconia sintered body is zirconia containing 2-10 mol % of yttria.

3. The composite plate according to claim 1, 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 coloring pigment.

4. The composite plate according to claim 1, wherein the zirconia sintered body has a relative density of 97% or higher.

5. The composite plate according to claim 1, wherein the zirconia sintered body has a Vickers hardness of 1,000 or more.

6. The composite plate according to claim 1, wherein the tempered glass is chemically strengthened aluminosilicate glass.

7. The composite plate according to claim 1, wherein the composite plate has a high shock resistance being a fracture height of 10 cm or more in a test in which a steel ball of 130 g is freely falled.

8. A casing of a mobile electronic device, comprising the composite plate according to claim 1.

9. A watch component comprising the composite plate according to claim 1.

10. A production method of the composite plate according to claim 1, the method comprising bonding the zirconia sintered body and the base material using an epoxy-based thermosetting adhesive at a temperature of 300 C. or lower.

11. A production method of the composite plate according to claim 2, the method comprising bonding the zirconia sintered body and the base material comprising tempered glass using an epoxy-based thermosetting adhesive at a temperature of 300 C. or lower.

12. The production method according to claim 10, wherein the zirconia sintered body is obtained by forming a green sheet having a thickness of 0.1 to 1 mm using a slurry prepared by mixing zirconia powder and an organic binder, and then sintering the green sheet at 1,300 to 1,500 C.

Description

BRIEF DESCRIPTION OF DRAWING

(1) FIG. 1 is a diagram showing the correlation between steel ball fracture height and the ratio of the thickness of a zirconia sintered body and the thickness of tempered glass in composite plates using white zirconia (product name 3YS20A, manufactured by TOSOH Corporation). (Open circle): Examples 1 to 4 and 14 (composite plate thickness: about 1 mm). .circle-solid. (Solid circle): Comparative Example 1 (composite plate thickness: 1.49 mm).

EXAMPLES

(2) The present invention will be specifically described by way of Examples and Comparative Examples.

(3) (Relative Density)

(4) The density of a sample was measured using the Archimedes method. The obtained density was used to determine the relative density with respect to the theoretical density. The theoretical densities of sintered bodies obtained by sintering of powers used in the following Examples and Comparative Examples are as follows. A sintered body using a white zirconia powder (3YS20A): 5.51 g/cm.sup.3. A sintered body using a black zirconia powder (product name TZ-Black, manufactured by TOSOH Corporation): 6.06 g/cm.sup.3. A sintered body using a zirconia powder (product name 3YSE, manufactured by TOSOH Corporation): 6.09 g/cm.sup.3. Powders prepared by adding high-purity alumina in amounts of 40 wt % and 60 wt % to a zirconia powder (product name 3YS, manufactured by TOSOH Corporation) are denoted by 3YS40A and 3YS60A. The theoretical densities of their sintered bodies are 3YS40A: 5.03 g/cm.sup.3 and 3YS60A: 4.63 g/cm.sup.3.

(5) (Measurement of Impact Strength)

(6) The impact strength of a composite plate was evaluated using a steel ball drop test. A method similar to ISO14368-3 in the specifications of Dimensions of watch glass and test method was used for the steel ball drop test. Specifically, one of the composite plates obtained in the Examples and Comparative Examples was secured to a 5 mm-thick flat aluminum alloy (50 mm52 mm) using a 0.1 mm-thick double-sided tape (product number 4511-100, manufactured by 3M). Then a steel ball of 130 g was freely falled onto the central position of the composite plate from a any height, and the fracture height was determined in steps of 1 cm. The impact surface used was a mirror polished surface with a surface roughness Ra of 0.02 m or less.

(7) (Measurement of Dielectric Constant)

(8) The measurement of dielectric constant was performed by a capacitance method using an impedance analyzer. A surface bonded to an electrode was mirror polished, and the dielectric constant and dielectric loss tangent were measured at room temperature and a frequency of 1 GHz.

(9) (Biaxial Bending Measurement)

(10) The bending strength of a composite plate was measured according to biaxial bending strength measurement (ISO/DIS6872). The measurement was performed as follows. The radius of a support was set to 6 mm, and the center of the composite plate was placed on the support with the zirconia sintered body thin plate on the front side and the base material surface on the rear side. An indenter was placed such that a load was applied to the center of the zirconia sintered body thin plate. To compute the bending strength, a reduced diameter using a flat plate area was used. The zirconia sintered body used had opposite surfaces mirror-polished to a surface roughness Ra of 0.02 m or less.

Examples 1-13

Production of Zirconia Sintered Bodies

(11) Each of a white zirconia powder (product name 3YS20A, manufactured by TOSOH Corporation), a black zirconia powder (product name TZ-Black, manufactured by TOSOH Corporation), and a zirconia powder (product name 3YSE, manufactured by TOSOH Corporation) were molded at a pressure of 50 MPa using a die press. Each of the obtained compacts was further molded at a pressure of 200 MPa using a cold isostatic press (CIP) to obtain a disk-shaped compact.

(12) Zirconia powders (3YS40A and 3YS60A) were produced as follows. A high-purity alumina powder was added in an amount of 40 wt % or 60 wt % to a zirconia powder containing 3 mol % of yttria (product name TZ-3YS, manufactured by TOSOH Corporation), and the mixture was subjected to ball mill mixing in an ethanol solvent using zirconia-made balls with a diameter of 10 mm and then dried to obtain a raw material powder. The obtained raw material powder was molded under the same conditions as above.

(13) Each of the obtained compacts was sintered in air at a temperature rising rate of 100 C./h and a sintering temperature of 1,400 to 1,500 C. to obtain a sintered body of 17 mm. The properties of the obtained sintered body are shown in TABLE 6 as a reference example. The opposite sides of the obtained sintered body were grounded and polished to a prescribed thickness to thereby obtain a zirconia sintered body thin plate. In TABLEs, Hv10 represents a Vickers hardness measured using an indenter load of 10 kgf.

(14) The surface of the obtained zirconia sintered body thin plate and the surface of aluminosilicate-based chemically strengthened glass (32 mm25 mm) were washed with acetone. Then these bonding surfaces were coated uniformly with an epoxy-based thermosetting resin (product number XN1245SR, manufactured by Nagase ChemteX Corporation). With a load applied uniformly to the upper and lower surfaces of the composite plate, the zirconia sintered body and the chemically strengthened glass were bonded to each other under the condition of 140 C. for 30 minutes. The thicknesses of the layers of the obtained composite plate are shown in TABLE 1.

(15) The results of evaluation are shown in TABLE 1. The apparent densities of all the composite plates were 4.3 g/cm.sup.3 or less, and the Vickers hardnesses of all the composite plates were 1,000 or higher. The results of the shock resistance test were 10 cm or more for all the composite plates, and the composite plates were found to have high shock resistance.

Example 14

(16) A composite plate was produced under the same conditions as in Example 1 except that a zirconia sintered body thin plate having dimensions of 32 mm25 mm was obtained using the white zirconia powder (product name 3YS20A, manufactured by TOSOH Corporation). The result of the shock resistance test is shown in TABLE 1. Cracking of the composite plate occurred at 29 cm, and the composite plate was found to have high shock resistance.

Example 15

(17) A composite plate was produced under the same conditions as in Example 1 except that the adhesive used was a two-part epoxy-based adhesive (product numbers XNR3324 and XNH3324, manufactured by Nagase ChemteX Corporation). The bonding was performed at 100 C. for 30 minutes. The result of the shock resistance test is shown in TABLE 1. The fracture height of the composite plate was 24 cm, and the composite plate was found to have high shock resistance.

Example 16

(18) A 3YS20A composite plate of 32 mm25 mm was produced by the same method as in Example 14. #100 sand paper was placed on the surface of the zirconia sintered body thin plate of the produced composite plate, and an iron-made weight of 3 kg was used to apply a load. The iron-made weight was moved a distance of 30 cm on the sand paper and reciprocated 5 times to flaw the composite plate. The result of the steel ball drop test on the composite plate subjected to flaw treatment is shown in TABLE 1. The steel ball fracture height was 30 cm, and no reduction in impact strength due to the flaw treatment was found.

Example 17

(19) A 3YS20A composite plate of 32 mm25 mm was produced by the same method as in Example 14. The bonding was performed under the condition of 140 C. for 30 minutes using a hot press such that a pressure of 4 MPa was applied to the plate. The thickness of the adhesive layer of the obtained composite plate was 7 m. The steel ball fracture height was 47 cm, and the composite plate was found to have high shock resistance.

Examples 18 and 19

(20) 3YS20A composite plates of 32 mm25 mm were produced by the same method as in Example 14. The relative dielectric constant and dielectric loss tangent of each of the composite plates at room temperature and 1 GHz are shown in TABLE 2. The relative dielectric constant and dielectric loss tangent of each composite plate were found to be comparable to those of aluminosilicate glass.

(21) The relative dielectric constant of the aluminosilicate glass measured separately at room temperature and 1 GHz was 7.5, and its dielectric loss tangent was 0.0125. The dielectric constant of 3YS20A was 28.4, and its dielectric loss tangent was 0.003. The relative dielectric constant computed from these values under the assumption of a series model was 9.5 and agreed well with the measured values. It was found that the relative dielectric constant of a composite plate can be reproduced using the series model of the zirconia sintered body and the tempered glass.

Examples 20 and 21

(22) 3YS20A composite plates of 32 mm25 mm were produced by the same method as in Example 14, and their biaxial bending strength was measured. The bending strength was found to be a high value of about 940 MPa. The bending elastic modulus was estimated from the load-displacement curve in the test and found to be about 80 GPa. Each of these composite plates was found to have an elastic modulus comparable to that of tempered glass (70 GPa).

Example 22

(23) Using the same method as in Example 1, a composite plate in which the ratio of the thickness of the zirconia sintered body/the thickness of the tempered glass was 0.09 was produced using 3YS20A. The results are shown in TABLE 4. Although the composite plate exhibited high shock resistance, the Vickers hardness was 800, and the abrasion resistance was slightly low.

Example 23

(24) 700 g of TZ-3YS powder, 14 g of a commercial polycarboxylate macromolecular dispersant used as a dispersant, 3.5 g of commercial polyethylene glycol mono-para-iso-octylphenyl ester used as an antifoaming agent, 245 g of ethyl acetate used as a solvent, 245 g of n-butyl acetate used as a solvent, 49 g of butyral resin (degree of polymerization: about 1,000) powder used as a binder, and 42 g of industrial dioctyl phthalate used as a plasticizer were added to a ball mill and mixed for 48 hours. A green sheet was formed on PET used as a carrier film using a doctor blade device and a doctor blade.

(25) The obtained green sheet was placed on a porous alumina setter and sintered with an alumina setter used as a weight placed on the green sheet. During the sintering, temperature was increased from room temperature to 450 C. at 5 C./h, and the green sheet was held at 450 C. for 10 hours to perform degreasing. Then the temperature was increased from 450 C. to 1,000 C. at 50 C./h, and the green sheet was held at 1,000 C. for 5 hours. Then the green sheet was held at 1,450 C. for two hours to perform sintering. The relative density of the obtained sintered body was 99% or higher.

(26) The obtained sintered body was bonded to a 0.698 mm-thick chemically strengthened glass of 32 mm25 mm using an epoxy-based thermosetting resin (product number XN1245SR, manufactured by Nagase ChemteX Corporation) in the same manner as in Example 1. The surface of the zirconia sintered body thin plate of the bonded composite plate was ground and polished to produce a composite plate.

(27) The thickness of the sintered body was 0.302 mm, and the thickness of the adhesive layer was 45 m. The thickness of the zirconia sintered body/the thickness of the glass was 0.43. The apparent density of the composite plate was 3.55 g/cm.sup.3, and its Vickers hardness was 1,430. The shock resistance test using the steel ball dropped as in Example 1 was performed, and the fracture height of the composite plate was found to be 26 cm.

Comparative Example 1

(28) Using the same method as in Example 1, a composite plate in which the ratio of the thickness of the zirconia sintered body/the thickness of the tempered glass was 1.66 was produced using 3YS20A. The results are shown in TABLE 4. The apparent density of the composite plate was higher than 4.3 g/cm.sup.3.

Comparative Example 2

(29) The steel ball drop test was performed under the condition of no adhesive by the same method as in Example 1 using 3YS20A. The results are shown in TABLE 4. When the zirconia sintered body was placed directly on the glass with no adhesive, fracture occurred at about 3 cm, and it was found that the shock resistance characteristics were significantly low.

Comparative Examples 3 to 5

(30) Flaw treatment was performed on the surfaces of aluminosilicate-based tempered glasses with different thicknesses (32 mm25 mm, thickness: 0.55 mm, 0.7 mm, 1.1 mm) by the same method as in Example 15 to evaluate their shock resistance before and after the flaw treatment. The results are shown in TABLE 5. When the thickness was 0.55 mm, the base material was cracked by the flaw treatment. For the tempered glasses with thicknesses of 0.7 and 1.1 mm, the flaw treatment caused the steel ball fracture height to be reduced by about one half.

Comparative Examples 6 and 7

(31) Using the same method as in Example 1, composite plates were produced using sapphire single crystals (manufactured by ORBE PIONEER Ltd.) (32 mm25 mm) instead of the zirconia sintered body, and the steel ball drop test was performed under the same conditions. The results are shown in TABLE 7. The density of the sapphire was 3.99 g/cm.sup.3.

(32) In the composite plates using sapphire, the steel ball fracture height was less than 10 cm, and the shock resistance characteristics were lower than those of the composite plate using the zirconia sintered body. This may be because, since the elastic modulus of sapphire is about twice that of the zirconia sintered body (the elastic modulus of sapphire is 400 GPa), tensile stress occurs on the sapphire side.

Examples 24 to 28

(33) Using the same method as in Example 1, a composite plate of 32 mm25 mm was produced using 3YS20A and using, as the base material, one of an aluminum (97 wt %)-magnesium alloy (#5052, manufactured by Eggs), a magnesium (90 wt %)-aluminum-zinc alloy (product name AZ91D, manufactured by MG Precision Co., Ltd.), cloth Bakelite, and paper Bakelite (manufactured by Fuso Rubber Co., Ltd.).

(34) A composite plate of 32 mm25 mm was produced using 3YS20A and using rigid polyvinyl chloride (MISUMI Group Inc.) by the same method as in Example 1 except that cyanoacrylate was used as the adhesive.

(35) The results of evaluation are shown in TABLE 8. The apparent densities of all the composite plates were 4.3 g/cm.sup.3 or less, and the Vickers hardnesses of all the composite plates were 1,000 or more. The results of the shock resistance test were 10 cm or more for all the composite plates, and the composite plates were found to have high shock resistance.

(36) TABLE-US-00001 TABLE 1 STEEL THICKNESS RATIO BALL MATERIAL ZIR- ADHE- ZIR- APPARENT VICKERS FRACTURE ZIR- CONIA GLASS SIVE TOTAL CONIA/ DENSITY HARDNESS HEIGHT CONIA GLASS ADHESIVE mm mm mm mm GLASS g/cm.sup.3 Hv10 cm Example 1 3YS20A TEMPERED XN1245SR 0.322 0.699 0.033 1.054 0.46 3.42 1430 32 GLASS Example 2 3YS20A TEMPERED XN1245SR 0.342 0.684 0.030 1.056 0.50 3.47 1430 30 GLASS Example 3 3YS20A TEMPERED XN1245SR 0.330 0.550 0.041 0.921 0.60 3.60 1430 26 GLASS Example 4 3YS20A TEMPERED XN1245SR 0.485 0.551 0.036 1.072 0.88 3.88 1430 20 GLASS Example 5 3YS20A TEMPERED XN1245SR 0.496 0.701 0.080 1.277 0.71 3.72 1430 25 GLASS Example 6 3YS20A TEMPERED XN1245SR 0.309 1.103 0.037 1.449 0.28 3.12 1430 30 GLASS Example 7 3YS20A TEMPERED XN1245SR 0.487 1.094 0.030 1.611 0.45 3.39 1430 25 GLASS Example 8 3YS20A TEMPERED XN1245SR 0.783 1.100 0.035 1.918 0.71 3.72 1430 20 GLASS Example 9 3YS20A TEMPERED XN1245SR 0.343 0.545 0.159 1.047 0.63 3.63 1430 12 GLASS Example 10 3YS40A TEMPERED XN1245SR 0.297 0.693 0.035 1.025 0.43 3.22 1480 21 GLASS Example 11 3YS60A TEMPERED XN1245SR 0.312 0.691 0.031 1.034 0.45 3.13 1530 25 GLASS Example 12 TZ-Black TEMPERED XN1245SR 0.251 0.697 0.032 0.980 0.36 3.41 1240 29 GLASS Example 13 3YSE TEMPERED XN1245SR 0.276 0.696 0.024 0.996 0.40 3.48 1240 35 GLASS Example 14 3YS20A TEMPERED XN1245SR 0.311 0.692 0.048 1.051 0.45 3.40 1430 29 GLASS Example 15 3YS20A TEMPERED XNR/H3324 0.285 0.701 0.024 1.010 0.41 3.33 1430 24 GLASS Example 16 3YS20A TEMPERED XN1245SR 0.285 0.693 0.047 1.025 0.41 3.34 1430 30 GLASS Example 17 3YS20A TEMPERED XN1245SR 0.315 1.103 0.007 1.425 0.29 3.13 1430 47 GLASS

(37) TABLE-US-00002 TABLE 2 DIELECTRIC DIELECTRIC CONSTANT LOSS TANGENT THICKNESS RATIO ROOM ROOM MATERIAL ZIR- ADHE- ZIR- TEMPER- TEMPER- ZIR- CONIA GLASS SIVE TOTAL CONIA/ ATURE, ATURE, CONIA GLASS ADHESIVE mm mm mm mm GLASS 1 GHz 1 GHz Example 18 3YS20A TEMPERED XN1245SR 0.324 0.696 0.025 1.045 0.47 11.1 0.011 GLASS Example 19 3YS20A TEMPERED XN1245SR 0.190 0.549 0.028 0.767 0.35 10.1 0.012 GLASS

(38) TABLE-US-00003 TABLE 3 THICKNESS RATIO FRAC- BENDING MATERIAL ZIR- ADHE- ZIR- TURE BENDING ELASTIC ZIR- CONIA GLASS SIVE TOTAL CONIA/ LOAD STRENGTH MODULUS CONIA GLASS ADHESIVE mm mm mm mm GLASS kgf MPa GPa Example 20 3YS20A TEMPERED XN1245SR 0.269 0.694 0.026 0.989 0.39 59.0 947 81 GLASS Example 21 3YS20A TEMPERED XN1245SR 0.203 0.692 0.036 0.931 0.29 52.9 940 84 GLASS

(39) TABLE-US-00004 TABLE 4 STEEL THICKNESS RATIO BALL MATERIAL ZIR- ADHE- ZIR- APPARENT VICKERS FRACTURE ZIR- CONIA GLASS SIVE TOTAL CONIA/ DENSITY HARDNESS HEIGHT CONIA GLASS ADHESIVE mm mm mm mm GLASS g/cm.sup.3 Hv10 cm Example 22 3YS20A TEMPERED XN1245SR 0.098 1.103 0.040 1.241 0.09 2.70 800 25 GLASS Comparative 3YS20A TEMPERED XN1245SR 0.916 0.551 0.026 1.493 1.66 4.36 1430 18 Example 1 GLASS Comparative 3YS20A TEMPERED NONE 0.296 0.702 0.998 0.42 3.36 1430 3 Example 2 GLASS

(40) TABLE-US-00005 TABLE 5 THICK- STEEL STEEL NESS BALL BALL OF FRACTURE FRACTURE TEMPERED HEIGHT HEIGHT GLASS VIRGIN FLAWED REDUCTION mm cm cm RATIO Comparative 0.55 42 CRACKED Example 3 DUE TO FLAWS Comparative 0.7 31 18 42% Example 4 Comparative 1.1 50 25 50% Example 5

(41) TABLE-US-00006 TABLE 6 REFERENCE EXAMPLE RELATIVE DIELECTRIC FRACTURE DIELECTRIC LOSS TANGENT BENDING TOUGHNESS VICKERS CONSTANT ROOM ROOM TEMPER- RELATIVE STRENGTH VALUE HARDNESS TEMPERATURE, ATURE, SINTERING DENSITY DENSITY JISR1601 JISR1607 JISR1610 1 GHz 1 GHz TEMPERATURE g/cm.sup.3 % MPa MPa m.sup.0.5 Hv10 3YS20A 1500 C.-2 h 5.473 99.3 1300 4.7 1430 28.4 0.0003 3YS40A 1500 C.-2 h 5.001 99.4 1340 4.7 1480 21.6 0.0014 3YS60A 1500 C.-2 h 4.588 99.1 1160 4.0 1530 16.7 0.0009 3YSE 1450 C.-2 h 6.073 99.8 1400 4.7 1240 36.6 0.0022 TZ-Black 1400 C.-1 h 5.993 99.0 1199 5.1 1240 37.5 0.0053

(42) TABLE-US-00007 TABLE 7 STEEL THICKNESS RATIO BALL SAP- ADHE- SAP- APPARENT VICKERS FRACTURE MATERIAL PHIRE GLASS SIVE TOTAL PHIRE/ DENSITY HARDNESS HEIGHT GLASS ADHESIVE mm mm mm mm GLASS g/cm.sup.3 Hv10 cm Comparative SAP- TEMPERED XN1245SR 0.346 0.700 0.024 1.070 0.49 2.45 1800 6 Example 6 PHIRE GLASS Comparative SAP- TEMPERED XN1245SR 0.837 1.100 0.030 1.967 0.76 2.96 1800 9 Example 7 PHIRE GLASS

(43) TABLE-US-00008 TABLE 8 THICKNESS RATIO APPAR- STEEL MATERIAL FOR BASE MATERIAL BASE ADHE- ZIR- ENT VICKERS BALL BASE ELASTIC ZIR- MATE- SIVE CONIA/ DEN- HARD- FRACTURE MATE- MODULUS DENSITY CONIA RIAL LAYER TOTAL BASE SITY NESS HEIGHT RIAL GPa g/cm.sup.3 mm mm mm mm MATERIAL g/cm.sup.3 Hv cm Example 24 ALUMINUM 70 2.7 0.154 0.470 0.026 0.650 0.33 3.25 1430 20 ALLOY Example 25 MAGNESIUM 45 1.81 0.204 0.527 0.022 0.753 0.39 2.75 1430 25 ALLOY Example 26 CLOTH 8 1.4 0.254 0.462 0.025 0.741 0.55 2.75 1430 15 BAKELITE Example 27 PAPER 6.5 1.4 0.246 0.507 0.022 0.775 0.49 2.65 1430 15 BAKELITE Example 28 POLYVINYL 3.1 1.43 0.171 0.516 0.038 0.725 0.33 2.31 1430 10 CHLORIDE

INDUSTRIAL APPLICABILITY

(44) The composite plate of the present invention including a zirconia sintered body sintered body and a base material formed from at least one selected from the group consisting of tempered glass, Bakelite, aluminum, and magnesium has shock resistance and abrasion resistance and can therefore be used preferably for small and thin components such as components of mobile electronic devices and watch components.