KR20170015278A - Liquid crystal touch panel protective plate - Google Patents

Abstract

Wherein the spinel sintered body has an average particle diameter of 10 占 퐉 or more and 100 占 퐉 or less.

Description

{LIQUID CRYSTAL TOUCH PANEL PROTECTIVE PLATE}

The present invention relates to a liquid crystal touch panel protection plate, and more particularly to a liquid crystal touch panel protection plate formed of a spinel sintered body.

In many cases, the liquid crystal touch panel is provided with a protective plate for the purpose of protecting the surface from contamination or outside air. 2. Description of the Related Art In recent years, various portable devices have been rapidly spreading, and accordingly, a protective plate for a liquid crystal touch panel of a portable device is also required to have strength.

As a protective plate of a liquid crystal touch panel having strength, a technique using a tempered glass or a substrate of single crystal sapphire has been proposed.

Tempered glass is inexpensive to manufacture, but further improvement in strength is required. The single crystal sapphire has a higher hardness and strength than tempered glass and has excellent performance as a shielding plate, but has a high production cost, which is problematic from the standpoint of practical use.

Therefore, it is an object of the present invention to provide a liquid crystal touch panel protection plate having excellent strength and reduced manufacturing cost.

A liquid crystal touch panel protection plate according to an embodiment of the present invention is a liquid crystal touch panel protection plate formed of a spinel sintered body, and the spinel sintered body is a liquid crystal touch panel protection plate having an average particle diameter of 10 m or more and 100 m or less.

According to this aspect, it is possible to provide a liquid crystal touch panel protection plate having excellent strength and reduced manufacturing cost.

[Description of Embodiments of the Present Invention]

First, an embodiment of the present invention will be described and explained.

(1) A liquid crystal touch panel protection plate according to an embodiment of the present invention is a liquid crystal touch panel protection plate formed of a spinel sintered body, wherein the spinel sintered body is an LCD touch panel protection plate having an average particle diameter of 10 m or more and 100 m or less.

The particle size of the spinel sintered body affects the strength of the spinel sintered body. When the average particle diameter of the spinel sintered body is 10 mu m or more and 100 mu m or less, the spinel sintered body has excellent strength. Therefore, the liquid crystal touch panel protective plate formed of the spinel sintered body also has excellent strength.

(2) The liquid crystal touch panel protective plate preferably has a surface roughness (Ra) of 10 nm or less. According to this, the liquid crystal touch panel protection plate has high light transmittance and can have excellent image display quality.

(3) It is preferable that the spinel sintered body includes pores, the maximum diameter of the pores is 100 m or less, and the number of pores having a diameter of 10 m or more is 2.0 or less per 1 cm3 of the spinel sintered body.

According to this, since the spinel sintered body is excellent in strength and abrasion resistance, it is difficult to break and the surface is hardly damaged. In addition, the corrosion resistance is also improved. Therefore, the liquid crystal touch panel protective plate formed of the spinel sintered body also has excellent strength, abrasion resistance, and corrosion resistance.

(4) The spinel sintered body preferably has a composition of MgO.nAl ₂ O ₃ (1.05? N? 1.30). According to this, the spinel sintered body is improved in balance in strength and light transmittance. Therefore, the liquid crystal touch panel protective plate formed of the spinel sintered body is also improved in balance in strength and light transmittance.

(5) The spinel sintered body contains an impurity, and the impurity has an average particle diameter of 20 m or less and a content of 10 ppm or less. According to this, the spinel sintered body has a stable high light transmittance. Therefore, the liquid crystal touch panel protective plate formed of the spinel sintered body also has a high transmittance.

[Detailed Description of Embodiments of the Present Invention]

A specific example of the liquid crystal touch panel shielding plate according to the embodiment of the present invention will be described below. It is to be understood that the present invention is not limited to these examples, but is encompassed by the claims and includes all modifications within the meaning and scope equivalent to those of the claims.

<LCD touch panel protection plate>

A liquid crystal touch panel protection plate according to an embodiment of the present invention is a liquid crystal touch panel protection plate formed of a spinel sintered body.

The liquid crystal touch panel protective plate preferably has a surface roughness (Ra) of 10 nm or less, more preferably 5 nm or less. According to this, the liquid crystal touch panel protection plate has high light transmittance and can have excellent image display quality. The surface roughness (Ra) is an arithmetic average roughness of the JIS standard. The arithmetic mean roughness is a kind of parameter representing the roughness of the surface and is calculated as follows. Only the reference length is extracted from the position 0 to the position 1 in the direction of the average line from the roughness curve of a certain surface to catch the X axis in the direction of the average line and the Y axis in the direction of the longitudinal magnification. The arithmetic average roughness Ra in the region from the position 0 to the position 1 in the X-axis direction when the roughness curve is represented by y = f (x) is obtained by the following expression.

The size of the liquid crystal touch panel protective plate is not particularly limited as long as it can cover the surface of the liquid crystal touch panel.

The thicker the thickness of the liquid crystal touch panel protective plate is, the larger the strength is, but the response characteristic and the heat radiation property of the liquid crystal touch panel are lowered.

<Spinel sintered body>

A liquid crystal touch panel protection plate according to an embodiment of the present invention is formed of a spinel sintered body.

The spinel sintered body is a sintered body of spinel whose composition formula is represented by MgO.nAl ₂ O ₃ (1? N? 6). The spinel sintered body is polycrystalline and does not cause birefringence, and has excellent light transmittance. Further, since the spinel sintered body has excellent mechanical strength and abrasion resistance, it is difficult to break and the surface is hardly damaged. The corrosion resistance is also good. Therefore, the liquid crystal touch panel protective plate formed of the spinel sintered body also has excellent light transmittance, mechanical strength, abrasion resistance and corrosion resistance.

Further, since the spinel sintered body can be produced by using powder metallurgy technology in addition to the raw material being inexpensive, it can be produced at low cost. The shape is not limited. Also, it is easier to process than sapphire. Therefore, a liquid crystal touch panel protective plate formed of a spinel sintered body can also be manufactured at low cost.

The spinel sintered body has an average particle diameter of 10 mu m or more and 100 mu m or less. Generally, the smaller the particle diameter of the spinel particles constituting the spinel sintered body, the greater the strength of the spinel sintered body, but the lower the light transmittance. The present inventors have intensively studied the relationship between the particle diameter of the spinel particles constituting the spinel sintered body and the strength and the light transmittance of the spinel sintered body. As a result, when the average particle diameter of the spinel sintered body is 10 μm or more and 100 μm or less, Can obtain a good spinel sintered body.

The average particle diameter of the spinel sintered body is preferably 10 mu m or more and 100 mu m or less, more preferably 20 mu m or more and 60 mu m or less. When the average particle diameter of the spinel sintered body is smaller, for example, less than 10 m, the intergranular scattering of light increases, and the light transmittance of the spinel sintered body tends to decrease. On the other hand, the larger the average particle diameter of the spinel sintered body, for example, exceeds 100 m, the strength of the spinel sintered body tends to decrease according to the Hall-Petch rule.

The average particle diameter of the spinel sintered body was measured by subjecting the surface of the liquid crystal touch panel protective plate formed of the spinel sintered body to mirror-surface processing using a grinder (NF-300 manufactured by Nanofactor), observing a certain range with an optical microscope, Is a value obtained by measuring the particle diameters of all the spinel sintered bodies included in the sample.

It is preferable that the spinel sintered body includes pores, the maximum diameter of the pores is 100 占 퐉 or less, and the number of pores having a diameter of 10 占 퐉 or more is 2.0 or less per 1 cm3 of the spinel sintered body. According to this, scattering of light passing through the spinel sintered body is suppressed, and the light transmittance of the spinel sintered body is further improved. In addition, the spinel sintered body is improved in the weave coefficient, which is an indicator of the unevenness of the mechanical strength, and a stable product can be obtained. This excellent mechanical property is believed to be caused by the small number of pores.

The spinel sintered body preferably does not contain pores having a maximum diameter exceeding 100 mu m. Here, &quot; does not contain &quot; means that it does not substantially contain, and a small amount of pores having a maximum diameter exceeding 100 mu m may be included within a range that does not increase the light scattering factor. When the maximum diameter of the pores is 50 탆 or less, the light scattering factor is further reduced, which is preferable.

The maximum diameter of the pores contained in the spinel sintered body is measured by observing a certain range of the spinel sintered body with a microscope using transmitted light. Usually, the spinel sintered body is cut into a constant volume (preferably, 10 mm to 15 mm in thickness, 20 mm in length and 20 mm in width), the upper and lower surfaces are polished, the obtained sample is observed by a microscope, Can be obtained by measuring the diameter of the pores. When the pores are not spherical, the diameters of the pores in the respective directions are different from each other, and the maximum diameter of the pores is the maximum diameter.

Specifically, the spinel sintered body is cut to a thickness of 15 mm, a length of 20 mm and a width of 20 mm, and the upper and lower surfaces are polished to prepare a sample. For the 10 samples, the pore diameter is measured. When no pores having a maximum diameter exceeding 100 mu m are observed for eight or more samples, it is assumed that the maximum diameter does not substantially contain pores exceeding 100 mu m.

The fact that the number of pores having a diameter of 10 占 퐉 or more in the spinel sintered body is 2.0 or less per 1 cm3 of the spinel sintered body is measured by observing a certain volume of the spinel sintered body by a microscope using transmitted light. Specifically, the spinel sintered body is cut into a plurality of spinel sintered bodies having a thickness of 10 mm to 15 mm, a length of 20 mm, and a width of 20 mm (or a total volume of the spinel sintered body to be the same size as described above) The sample is observed by a microscope photograph to measure the diameter and number of the pores.

In one embodiment of the present invention, the spinel sintered body preferably has a composition of MgO.nAl ₂ O ₃ (1.05? N? 1.30). The value of n is more preferably 1.07? n? 1.25, and more preferably 1.08? n? 1.09. According to this, the spinel sintered body is improved in balance in strength and light transmittance. Accordingly, the liquid crystal touch panel protective plate formed of the spinel sintered body is also improved in balance in strength and light transmittance.

In one embodiment of the present invention, the spinel sintered body contains impurities, but the average particle diameter of the impurities is preferably not more than 20 占 퐉 and the content thereof is preferably not more than 10 ppm. The impurities contained in the spinel sintered body form internal defects such as pores to increase the light scattering factor and lower the light transmittance of the spinel sintered body. It also affects the refractive index and the like. Therefore, the smaller the average particle diameter of the impurity is, the better, and the smaller the content is, the better.

The impurities are included in the raw material powder or mixed in the production of the sintered body and contained in the spinel sintered body. Therefore, it is preferable to use spinel having a purity of 99.9% by mass or more for components that can be removed with high purity, preferably, by sintering. It is also preferable to control the sintering step so as not to contain impurities.

Specific examples of the impurities which are likely to be incorporated when preparing the impurities and the sintered body which are likely to be contained in the raw material powder include tungsten (W), cobalt (Co), iron (Fe), carbon (C), copper (Cu) ), Zinc (Zn), nickel (Ni), and the like. It is considered that these impurities are coalesced or precipitated in the sintering process to form impurity particles having a size adversely affecting the optical characteristics and increase the scattering factor of light to affect the permeability. It is preferable to control the purity of the raw material powder and the sintering process so that the total content of these impurities in the spinel sintered body is 10 ppm or less, and more preferably 5 ppm or less.

&Lt; Production method of spinel sintered body >

The spinel sintered body can be produced, for example, by the following method.

First, spinel particles are prepared, and the spinel particles are dispersed in a dispersion medium to prepare a slurry. The slurry can be produced by appropriately mixing spinel particles of high purity, a dispersion medium, a dispersant, and the like, and mechanically mixing them with stirring. Examples of the mechanical stirring mixing method include a method of mixing by a ball mill, a method of irradiating ultrasonic waves from the outside using an ultrasonic bath, and a method of irradiating ultrasonic waves by an ultrasonic homogenizer. The spinel particles are easily dispersed in a dispersion medium to be easily dispersed in a slurry, and a dispersing method using ceramics balls or the like is considered to be likely to incorporate oxides or salts as impurities, and thus a method using ultrasonic waves is preferable . The stirring mixing time should be appropriately adjusted according to the amount of the slurry or the irradiation amount of the ultrasonic waves. For example, in the case of using an ultrasonic bath in which the amount of slurry is 10 liters and the irradiation ability is about 25 kilohertz, As the dispersion medium for dispersing the spinel particles, water or various organic solvents can be used. After the stirring and mixing, the spinel concentration in the slurry can be increased by carrying out sedimentation by standing, centrifugation, concentration under reduced pressure by a rotary evaporator, and the like.

Next, the slurry is granulated by a spray dryer or the like, the granules are filled in a mold, and pressed into a predetermined shape to produce a spinel compact.

Dispersants such as polyacrylic acid ammonium salt (when the dispersion medium is water), ethyl oleate, sorbitan monooleate, sorbitan trioleate, polycarboxylic acid system (when the dispersion medium is an organic solvent) Organic binders such as polyvinyl alcohol, polyvinyl acetal, various acrylic polymers, methyl cellulose, polyvinyl acetate, polyvinyl butyral, various waxes and various polysaccharides may be added to the slurry to facilitate the formation of granules.

It is preferable that the raw material spinel particles have a high purity. Since the organic matter, halogen or water contained in the raw material is removed from the raw material in the primary sintering process and does not impair the characteristics of the spinel sintered body, incorporation of these impurities in the stage before the first sintering is permitted.

As a pressing method, a cold isostatic pressing (CIP) can be mentioned. The pressure of the press is preferably selected in the range that the relative density of the spinel compact after the first sintering is in the range of 95% to 96%, and is usually 100 to 300 MPa.

Next, the spinel molded body is firstly sintered. In the first sintering, the spinel formed body is sintered by heating at a predetermined atmospheric pressure or reduced pressure (vacuum) atmosphere at 1500 ° C to 1900 ° C. As the atmospheric pressure or reduced pressure (vacuum) atmosphere, a reducing atmosphere such as hydrogen or an inert gas atmosphere such as Ar is preferable. The pressure of the atmosphere is preferably reduced (vacuum), and specifically about 1 Pa to 200 Pa is preferable. The time for the first sintering is preferably about 1 hour to 5 hours.

The relative density of the spinel molded body (spinel primary sintered body) after the first sintering is preferably in the range of 95% to 96%. Here, the relative density refers to an actual density ratio (expressed as a ratio of the theoretical density.%) To the theoretical density (3.60 g / cm 3 at 25 ° C) of spinel. For example, the density of spinels having a relative density of 95% ) Is 3.42 g / cm &lt; 3 &gt;.

When the relative density of the spinel molded body (spinel primary sintered body) is less than 95%, sintering in the secondary sintering process is unlikely to proceed and it is difficult to obtain a transparent spinel sintered body. On the other hand, when the relative density exceeds 96%, coalescence of pores already existing in the spinel compact in the secondary sintering process tends to proceed, and pores having a maximum diameter of more than 100 mu are easily generated. The number of pores increases and it becomes difficult to obtain a spinel sintered body having a number of pores having a maximum diameter of 10 占 퐉 or more and 2.0 or less per 1 cm3 of the spinel sintered body.

The density of the formed body before the first sintering varies depending on the pressure of the press at the time of molding. The relative density of the spinel compact after the first sintering process varies depending on the density of the compact before the first sintering and the temperature and time of the first sintering. Therefore, the relative density in the range of 95% to 96% can be obtained by adjusting the pressure of the press at the time of molding and the temperature and time of the first sintering.

The spinel primary sintered body obtained by the primary sintering step is secondarily sintered. In the second sintering, the formed body is sintered by heating under pressure at 1500 to 2000 占 폚, preferably 1600 to 1900 占 폚. The pressing pressure is in the range of 5 MPa to 300 MPa, preferably about 50 MPa to 250 MPa, and more preferably about 100 MPa to 200 MPa. The second sintering time is preferably about 1 hour to 5 hours. The atmosphere of the secondary sintering is preferably an atmosphere of an inert gas such as Ar.

The relative density of the spinel molded body (spinel sintered body) after the second sintering step is preferably 99.9% or more. The relative density of the spinel molded body after the second sintering varies depending on the pressure and temperature in the second sintering step and the time of the second sintering. Therefore, the relative density of 99.9% or more can be obtained by adjusting the pressure and temperature in the second sintering process and the time of the second sintering.

By adjusting the relative density of the spinel sintered body after the secondary sintering process to be not less than 99.9% as described above, the particle growth of the spinel in the sintering process is controlled, and the coalescence of the fine pores due to the grain growth of the spinel can be suppressed . As a result, generation of pores having a maximum diameter exceeding 100 mu m is suppressed, and a spinel sintered body in which the number of pores is suppressed can be obtained.

&Lt; Manufacturing method of liquid crystal touch panel protection plate >

The spinel sintered body obtained by the method for manufacturing a spinel sintered body is processed into a liquid crystal touch panel shielding plate through a process such as cutting into a predetermined shape and polishing. When polishing the liquid crystal touch panel protective plate, it is preferable that the surface roughness (Ra) is 10 nm or less. The size or thickness of the liquid crystal touch panel protective plate may be determined according to the size or design of the liquid crystal touch panel to be applied, and is not particularly limited. A lens may be formed to form a penetrating portion on the surface of the liquid crystal touch panel protective plate or to enlarge a part of the liquid crystal touch panel.

In addition, an antireflection coating layer or a layer that performs optical action may be formed on the surface of the liquid crystal touch panel protection plate, if necessary. For example, by forming an antireflection coating layer on one side or both sides of the liquid crystal touch panel protection plate, the light transmission function can be further improved.

The antireflection coating layer is, for example, a layer of a metal oxide or a metal fluoride, and a conventionally known PVD method (physical vapor deposition method), specifically, a sputtering method, an ion plating method, a vacuum deposition method, or the like can be used.

Example

The present invention will be described more specifically by way of examples. However, the present invention is not limited by these examples.

<Fabrication of liquid crystal touch panel protection plate>

[Production Example 1]

4700 g (purity: 99.9% or more) of spinel particles having a composition of MgO.nAl ₂ O ₃ (n = 1.09), 3100 g of water (dispersion medium), and 40% by mass of ammonium polycarboxylate (dispersant, SN-D5468) were placed in an ultrasonic bath having a capacity of 40 liters, and mixed with stirring for 30 minutes while irradiating ultrasonic waves. Thereafter, 1000 g of a 10 mass% solution of polyvinyl alcohol (trade name: PVA-205C, manufactured by Kuraray Co., Ltd.) as an organic binder and 10 g of polyethylene glycol # 400 (reagent grade) as a plasticizer were added and stirred for 60 minutes to obtain a slurry Lt; / RTI &gt;

Next, the slurry was granulated by spray drying, and the moisture content of the granules was adjusted to 0.5% by mass. Then, the slurry was charged into a mold, primary molded at a pressure of 196 MPa, (CIP) to obtain a spinel molded article.

The obtained molded article was put into a vessel made of graphite and subjected to primary sintering in vacuum (5 Pa or less) at 1,700 占 폚 for 2 hours. The relative density of the obtained primary sintered body was measured by Archimedes' method and found to be 98%.

The primary sintered body was heated and pressurized by hot isostatic pressing (HIP) at 1700 캜 for 2 hours under an atmosphere of argon and atmospheric pressure of 196 MPa to obtain a secondary sintered body. The relative density of the obtained secondary sintered body was measured by Archimedes' method and found to be 99.8%.

The secondary sintered body of the spinel obtained by the above method was cut into a square having a major surface of 100 mm on one side with a thickness of about 1 mm and then both surfaces of the main surface were polished with a grinder (NF-300 manufactured by Nanofactor) To obtain a liquid crystal touch panel protection plate having a surface roughness (Ra) of 8 nm and a thickness of 1 mm (volume: 1.0 cm 3).

[Production Examples 2 to 7]

In Production Examples 2 to 7, a liquid crystal touch panel protective plate was produced by using the same raw materials and the same method as in Production Example 1, except that the conditions of the first sintering condition and the second sintering condition were set as shown in Table 1.

[Production Examples 8 and 9]

Production Examples 8 and 9 were prepared in the same manner as in Production Example 1 and in the same manner as in Production Example 1 except that the surface roughness (Ra) of the liquid crystal touch panel protective plate was changed to 5 nm for Production Example 8 and 10 nm for Production Example 9, Respectively.

[Production Examples 10 to 13]

Spinel particles having a composition of MgO.nAl ₂ O ₃ (n = 1.08), Production Example 11 of spinel particles having a composition of MgO.nAl ₂ O ₃ (n = 1.05), Production Example 12 Was prepared in the same manner as in Preparation Example 1 except that the spinel particles having a composition of MgO.nAl ₂ O ₃ (n = 1.10) and the spinel particles having a composition of MgO.nAl ₂ O ₃ (n = 1.15) A liquid crystal touch panel protection plate was produced.

[Production Examples 14 to 17]

In Production Example 14, 10 ppm of Si, 15 ppm of Si, 25 ppm of Si, and 30 ppm of Si were added to the spinel particles of Production Example 1, Production Example 14, Production Example 15 1 and a liquid crystal touch panel protective plate were produced in the same manner.

[Production Example 18]

Using a tempered glass, a liquid crystal touch panel protective plate having a size of 1 mm in a square of 100 mm on one side was obtained (volume 1.0 cm 3).

[Production Example 19]

A sapphire substrate was used to obtain a liquid crystal touch panel protective plate having a size of 1 mm in a square of 100 mm on one side (volume 1.0 cm 3).

<Measurement>

(Mohs hardness)

Mohs hardness was measured based on the method prescribed in JIS. The results are shown in Table 1.

(Light transmissive)

The average light transmittance (%) of the liquid crystal touch panel protective plate at a wavelength of 400 nm to 800 nm was measured. The results are shown in Table 1.

(Bending strength)

Based on the method prescribed in JIS, the three-point bending strength was measured. The results are shown in Table 1.

(Observation of pores)

The surface of the liquid crystal touch panel protective plate was observed at a magnification of 50 times using an optical microscope (T-300, Nikon Corporation), and the maximum diameter of pores and the number of pores having a diameter of 10 m or more were measured. The results are shown in Table 1.

(Impurity content)

The impurity content of the liquid crystal touch panel protection plate was measured by ICP emission analysis. The results are shown in Table 1.

(density)

The relative density of the liquid crystal touch panel protection plate was measured by the Archimedes method. The results are shown in Table 1.

&Lt; Evaluation result >

Comparing Production Examples 1 to 7, it was confirmed that the liquid crystal touch panel had excellent light transmittance and strength when the average particle diameter of the spinel sintered body included in the liquid crystal touch panel was 10 μm or more and 100 μm or less (Production Examples 2 to 6) .

From Production Examples 1, 8, and 9, it was confirmed that the liquid crystal touch panel had excellent light transmittance and strength when the surface roughness (Ra) of the liquid crystal touch panel protective plate was 10 nm or less.

From Production Examples 1 and 10 to 13, it was confirmed that the liquid crystal touch panel had excellent light transmittance and strength when the n value of 1.05? N? 1.30 in the composition of the raw material spinel particles MgO.nAl ₂ O ₃ .

From Production Examples 1 and 14 to 17, it was confirmed that the liquid crystal touch panel had excellent light transmittance and strength when the average particle diameter of impurities was 20 占 퐉 or less and the content was 10 ppm or less.

Comparing the production examples 1 to 17 and the production examples 18 and 19, it was confirmed that the production examples 1 to 17 had better strength than the tempered glass and excellent strength close to the sapphire substrate.

The liquid crystal touch panel protective plate of the present invention is advantageous for use in a portable device or the like because it has excellent strength.

Claims (5)

A liquid crystal touch panel protection plate formed of a spinel sintered body,
Wherein the spinel sintered body has an average particle diameter of 10 mu m or more and 100 mu m or less. The liquid crystal touch panel protecting plate according to claim 1, wherein the liquid crystal touch panel protecting plate has a surface roughness (Ra) of 10 nm or less. 3. The spinel sintered body according to claim 1 or 2, wherein the spinel sintered body comprises pores,
Wherein the maximum diameter of the pores is 100 占 퐉 or less and the number of pores having a diameter of 10 占 퐉 or more is 2.0 or less per 1 cm3 of the spinel sintered body. The liquid crystal touch panel according to any one of claims 1 to 3, wherein the spinel sintered body has a composition of MgO.nAl ₂ O ₃ (1.05? N? 1.30). The spinel sintered body according to any one of claims 1 to 4, wherein the spinel sintered body contains an impurity,
Wherein the impurity has an average particle diameter of 20 mu m or less and a content of 10 ppm or less.