JPH01239036A - High-strength glass - Google Patents

Abstract

PURPOSE:To contrive improvement in safety and rigidity, increase in density and decrease in hygroscopicity and enable reduction in sheet thickness, by constituting high-strength glass of SiO2, Al2O3, R2O, ZnO and B2O3 at a specific composition ratio. CONSTITUTION:Glass is subjected to chemical strengthening by carrying out prescribed ion exchange in glass with a treating solution consisting of, e.g., 100wt.% KNO3 or 60wt.% KNO3 and 40wt.% NaNO3, for the chemical strengthening and regulating the composition so as to provide 60.0-70.0wt.% SiO2, 0.5-14.0wt.% Al2O3, 10.0-32.0wt.% R2O (R is alkaline metal), 1.0-15.0wt.% ZnO and 0.5-14.0wt.% B2O3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to electrical parts, electronic parts, magnetic recording/optical recording/magneto-optical recording devices, and reproduction devices thereof, particularly the above-mentioned magnetic/magnetic recording devices.
High-density recording disk substrates used for memory disks serving as storage elements in optical/magnetic optical devices, i.e. substrates for magnetic disks, optical disks, magneto-optical disks, etc., as well as resin moldings, especially resin lens molds for eyeglasses. This product relates to materials used in transparent products that require strength and high-precision finishing, as well as molds for molding UV-curable resins.

[Conventional technology]

Plastics and inorganic glasses are being considered as disk substrates for high-density recording. However, the biggest weakness of plastic is that it is highly hygroscopic. Therefore, in order to compensate for these defects, improvement of the moisture resistance of the recording film and improvement of the substrate material are being studied.

However, as seen in changes over time, there are many unstable factors in achieving long-term credit flexibility.

Traditional soda lime glass, soda aluminosilicate glass,
When used alone, such as chemically strengthened borosilicate glass, the probability of natural failure is low, but the tensile stress factor caused by migration (ion movement/diffusion) due to bonding with the recording film There is a high probability that this will lead to explosive destruction.

Therefore, when used under bonding conditions, glass ceramics with a crystallized structure are considered to be optimal.

The contents of the above-mentioned natural fracture and cracking phenomena will be described in detail.

In the case of chemically strengthened glass, the combination of substrate glass, chemically strengthened layer, and recording film (inorganic/organic) is such that the chemically strengthened layer is different from the substrate glass, and the recording film or other bonding material is different from the compressive stress strengthening layer. A necessary condition is a relationship that results in tensile stress.

In terms of proper bonding, the combination of bonding materials has a lower melting point than the glass substrate, but the techniques for bonding conditions are not limited to the above, and of course there are a few exceptions. .

In the case of chemically strengthened glass, depending on the composition, especially if the chemically strengthened layer is inserted too deeply, peeling or cracking may occur in the direction of shrinkage. In addition, in the case of a composite with a mating material, it is necessary to match the thermal expansion coefficients of the base glass and the mating material.

However, regardless of whether the mating materials are inorganic or organic, phenomena such as migration occur, and if some form of tensile stress is generated through the mating surfaces, explosive destruction may occur, although there may be slight differences depending on the environmental conditions. may occur.

As described above, chemically strengthened glass is extremely dangerous in some cases, and in many cases it is impossible to use it other than as a single glass.

Glass parts that have not been treated against surface compressive stress generally require a plate thickness of 3 m/m or more, even if the glass is strengthened by rapid cooling or chemically strengthened.

In the case of the current high-density recording disk substrate, the plate thickness is 2 m.
There are many standards of less than / m, and it is thought that the plate thickness will continue to increase in the future as demand becomes even more dense.

Therefore, when compressive stress is uniformly applied to the surface of the glass, external tension is used to cancel out the compressive stress, and the glass is strengthened by that amount. Although this is a chemical strengthening phenomenon, consideration must be given to the case where the chemically strengthened N (compressive stress reinforcing layer) disappears due to migration and tensile stress is directly applied.

[Problems to be Solved by the Invention] With the recent advances in electronics technology, especially information-related technology represented by computers, efforts have already begun to respond to a more full-fledged information society.

Optical disk memory uses semiconductor lasers to quickly record and reproduce information such as documents, data, photographs, and TV images.
Recording density is 50 to 500 times higher than conventional magnetic memory.
Write-once optical disk memory has been put into practical use as a device capable of storing large amounts of information.

The characteristics of the optical disk memory mentioned above are that the optical memory is a CD.
(Compact Disc) and VD (Video Disc), CD-ROM (CD-Rea d○nly M
memory), write-once type (DRAW; Direct R
Ead After Wr-iLe) disks and magneto-optical type (EDRAW) that can be erased, replayed, and written.
; Er a s a b I eDirect
The appearance of Read After Write, -e) discs is also expected to be imminent.

The characteristics of optical disk memory are as follows.

1. Recording and playback is possible without contact.

2. Random access is possible.

3. Reproductions are inexpensive.

44 High density and high capacity are possible.

While taking advantage of the above characteristics, optical discs are CD, V
Applications are expanding from consumer use such as D to office automation equipment such as video filing and document filing, and information processing equipment.In the future, applications will be expanded to include computers, with higher reliability, faster transfer rates, and higher speeds. The development of search technology is an issue.

At present, plastic is overwhelmingly used as the substrate material for these optical discs, and some optical discs for additional large code data are made of chemically strengthened glass (soda lime glass, soda aluminosilicate glass, borosilicate glass). salt glass) has been tested.

However, it has been pointed out that conventional plastic substrates have defects such as deformation due to heat, birefringence, and warping due to moisture absorption. Furthermore, in conventional chemically strengthened glass, although the apparent strength of the substrate itself is improved, when combined with a recording film, the chemically strengthened layer is eroded by phenomena such as migration, resulting in a decrease in strength. Further, if tensile stress is generated in the recording film relative to the substrate glass, explosive destruction occurs, causing damage to surrounding equipment.

As mentioned above, plastic and chemically strengthened glass as substrate materials for optical disk memories each have their advantages and disadvantages, and will likely be used depending on the application. The material is not suitable for this purpose.

As substrates for optical disks, magneto-optical disks, etc., we use ZnO, which has heat resistance, mechanical strength, high processing accuracy, low birefringence, and has a compressive stress layer with little migration that is gently diffused. A high-strength glass substrate of the present invention is required, which is characterized by containing:

Although chemically strengthened glass is strengthened, it has been pointed out that it can break as described above and has drawbacks such as being expensive. However, the high-strength glass of the present invention exhibits high mechanical strength even when a recording film is bonded thereto, and the recording density is improved, so that the cost per unit memory is actually lower.

Therefore, the characteristics of the chemically strengthened glass substrate of the present invention can be expressed as follows.

In other words, since it does not allow oxygen or moisture in the air to pass through, deterioration of the recording film can be prevented.

2. There is almost no birefringence.

3. No warping due to moisture absorption.

4. High rigidity prevents deformation during rotation.

5. Machining accuracy is high, and eccentric surface runout is less likely to occur.

As described above, the substrate using the high-strength glass of the present invention overcomes the drawbacks of conventional substrates and has a completely ideal glass composition.

Future technological trends and required characteristics, as well as the characteristics of the high-strength glass of the present invention, are that in optical disks and magneto-optical disks, the optical spot position is controlled electro-optically, but this control is limited by the physical range. Therefore, the mechanical properties of the disk substrate itself must be sufficiently good. If there are undulations in the circumferential direction, or if the material has orientation (due to the glass forming process), the heat generated by the resistance friction during rotation will cause surface deflection, and if the warpage is large, there is a risk of contact with the lens surface. There is also.

If the eccentricity is large, the operation will become unstable. Therefore, the flatness and concentricity of the substrate are particularly important factors.Since the disk substrate also serves to protect the recording film, the substrate material must be resistant to environmental conditions such as temperature, 12 degrees Celsius, and mechanical strength. desired.

Regarding optical properties, the higher the transmittance of the glass substrate, the better, from the relationship between laser output and medium sensitivity. Furthermore, if the birefringence is large, the level of the photodetector will fluctuate, and the amount of light returned to the laser will increase, making it easier to generate noise.

Particularly in the case of magneto-optical disks, since signals are detected using the rotation of the plane of polarization of light, the presence of birefringence in the disk substrate is a major hindrance. Also, changes in the tilt and thickness of the substrate cause optical aberrations.

In any case, the substrate using the high-strength glass of the present invention is
It has better surface smoothness than substrates made of aluminum or plastic, and in addition, it has high strength, so the wall thickness can be made thinner and recording density can be improved. Bending strength and hardness are also important points, but we have achieved higher precision than conventional technology, with a surface roughness of 15 to 20 mm.
Flatness data (for 5.25 inch disks) of 2 μm or less was obtained.

[Means for solving problems]

The present invention provides highly safe glass that does not spontaneously break despite being chemically strengthened glass.

That is, the high-strength glass of the present invention has SiO
,60,0~70.0%,Af,030°5~14.0
%, R2O (R is an alkali metal) 10.0-3
2.0%, ZnO1.0~15°0%, Bz Oi 0
．． It is characterized by consisting of 5 to 14.0%.

(a) Based on weight, Si0260.0 to 70.0
%, A/! , o* 1.0-14.0%, R2O (where R is an alkali metal) 10°0-32°0%, ZnO
88% or more of the basic components consisting of 1.0~15.0%, B, 0.0°5~12.0%, and (b) based on weight, Pb
O,Bad,Zro, ,Tie, ,As2O,,S
b! It is characterized by containing 12% or less of at least one additive component selected from optional components such as O, MgO1SrO, which causes compressive stress on the glass surface due to migration, which causes stress on the glass surface after cooling. A high-strength glass with excellent reinforcement properties can be obtained.

The above-mentioned composition of the glass of the present invention is particularly suitable for chemically strengthening thin glass plates with a thickness of 3 m/m or less, and allows the stress layer to be slowly diffused to the depths without substantially damaging the surface. Because it diffuses, there is no natural destruction, and even if precision polishing is performed after chemical strengthening, the degree of strengthening will not change.

Chemical strengthening is done at the transition point of glass (around -100℃)
At the following temperatures, the alkali ions contained in the glass,
Ion exchange is performed by immersing the glass in a molten alkali salt containing alkali ions with an ionic radius larger than this.

As a result of the above ion exchange, compressive stress is generated on the glass surface due to the difference in the occupied volume of the alkali ions, and this stress remains on the glass surface after cooling, so that it is strengthened.

〔Example〕

The following three types of treatment liquids are suitable for use in chemically strengthening the high-strength glass of the present invention.

1. KNO3 100% (weight%) 2. KNOj 60% + Na Not 40% Cap 1%
) (especially effective when containing LixO) 3, KN○s9
9.5% 10Hz S i Os 0. 5% (wt%) The above treatment liquid exchanges Li'' and Na+ ions in the glass with Na+ and Ni'' ions in the treatment liquid.

Because two types of ion exchange occur at the same time, it exhibits excellent reinforcing properties.

Composition 1 (wt%) Sing 64. OAlOs 8.5Na, 0 8.
OK, 0 7. 0ZnO2,7Lit OI
0 BaO1, OB2Oi 2.0 TfOz 1. OZrC1z 4. 5As,
030.3 Composition 2 (wt%) Sloz 62. 4 Afiz 0,2
．． 9NazO9, OK2O 9. 1 Ca0 0. I MgO2,8ZnO11,
5Bz O31,l Ti1t 0.6 ASz ○, 0.2S
bz 03 0. 3 The relationship among the chemical strengthening treatment time, bending strength, Charpy strength, and stress strain layer thickness obtained by each side of Composition Examples 1 and 2 above is shown in Table 1 below.

There is almost no difference between Composition Examples 1 and 2.

Table 1 The above two glasses were prepared by putting the powder mixture into an open crucible,
It was melted by heating to 1450 to 1500°C, kept at this temperature for 4 to 12 hours, and then slowly cooled over 4 hours after clarification.

Note that from the viewpoint of structural homogeneity, a stable chemical strengthening method is to perform chemical strengthening treatment after completely removing strain. Therefore, if there is structural non-uniformity (such as distortion) or orientation during molding, bending, twisting, etc. will occur.

Inspection results using a surface stress needle show that the chemically strengthened layer diffuses more slowly than in ordinary soda lime glass, soda aluminosilicate glass, and borosilicate glass, and does not lead to natural failure.

As mentioned above, the object of the present invention is to obtain a glass composition that does not cause spontaneous fracture or fracture at the composite stage due to tensile stress caused by reaction phenomena such as migration caused by bonding with the recording film. Invention high-strength glass (refractive index 1.510 to 1.535, Atsbe number 63)
．． 5ift in the basic component of (as a range from 0 to 50.0)
is required in an amount of 60.0 to 70.0% based on the total weight.

When this amount is less than 60.0%, chemical durability deteriorates, and when it is more than 70%, it becomes difficult to melt and workability decreases.

Next, Al2O is used to improve chemical durability and adjust the viscosity of molten glass, but the amount is 0.5
If the amount is less than 14.%, these effects will be insufficient.
If it exceeds 0%, the viscosity of the glass increases more than necessary, making it difficult to handle, which is not preferable.

Furthermore, R2O (alkali metal oxides such as Nag06.
0-14.0%, Li, OO-5.0%, K, 04. O
~13.0%) is used in the range of 10°0 to 32.0% as R and O based on weight for the purpose of adjusting the viscosity, ion exchange component, thermal expansion coefficient, and lowering the melting temperature of the glass. If this amount is less than 10.0%, the glass becomes poorly soluble and chemical strengthening becomes impossible. Moreover, if it exceeds 32%, it is not preferable because it causes a decrease in the viscosity of the glass, a decrease in the refractive index, a deterioration in the chemical durability, and an adverse effect on the strength due to chemical strengthening of the glass.

The high-strength glass of the present invention contains ZnO1 in addition to the above components.
, 0-15.0% of the base component is required. This component is necessary for maintaining chemical durability and refractive index. It also prevents phenomena that can lead to destruction of chemically strengthened glass. In other words, ion exchange does not show a pronounced reinforcing layer as seen in soda aluminosilicate glass, soda lime glass, borosilicate glass, etc., and ion diffusion occurs slowly.
The chemically strengthened layer does not appear clearly in a layered manner. Therefore, there is no migration due to reaction and diffusion with the recording film or other mating materials, which does not lead to destruction.

In addition to the above-mentioned basic components, the high-strength glass of the present invention also has B! O*, PbO, BaO1ZrOz, Ti0z
, Lit 01Mg○, CaO1Asz Oz
, 5bzOz.

These are added to improve glass melting properties, bubble breakability, clarification, etc., but based on weight, B2O,
12.0% or less for Zr0□, 4.0 for Zr0□
% or less, PbO 12.0% or less, BaO 12.0% or less, TiO□ 1.0% or less, LizO 5.0% or less, MgO 4°0% or less, CaO 7.0% or less for As
Even if each of zO3 and 5bzOs is contained in a range of 1.0% or less, there is no adverse effect on the high-strength glass of the present invention.

Furthermore, in the present invention, in addition to the above-mentioned basic components or optional components, in cases where UV transmission is not required (N i 01
In addition to Coo colorants, coloring components commonly used in the production of ordinary colored glass can be included.

Examples of such coloring components include Se, CU○, C
ut o, Crz 03, Ndz O3, N 1O1
Coo, Mn0z (MnO), Few 03 (Fe
Metal oxides such as d) can be mentioned. These may be used alone or in combination of two or more. If the total amount of these coloring components is 3% or less based on the total weight of the high-strength glass of the present invention, no problem will arise.

Table 2 below shows the characteristic values of the high-strength glass of the present invention made with the composition 1, and Table 3 shows the characteristic values of the high-strength glass of the present invention made with various other compositions.

〔Effect of the invention〕

Since the high-strength glass of the present invention is composed of the composition described in the claims, it does not undergo spontaneous fracture even though it has been chemically strengthened and is highly safe, and can be made thinner. be able to. Therefore, it is suitable as a substrate material for optical disks, magneto-optical disks, etc. When the recording substrate is made of the glass of the present invention, it can prevent deterioration of the recording film, has almost no birefringence, does not warp due to moisture absorption, and has high rigidity. Therefore, effects such as no deformation during rotation, high machining accuracy, and less chance of eccentric surface runout can be obtained.

(Voluntary) procedural amendment 1, Indication of the case: Patent Application No. 62970 of 1988 2, Name of the invention: High-strength glass 3, Relationship with the person making the amendment: Patent applicant name: F.G.K. Co., Ltd. 4, Agent address: 2nd floor, 6th floor, Kimura Building, 2-11-12 Yoyogi, Shibuya-ku, Tokyo Claims (1) Based on weight, Sin, 60.0-70゜0%,
ADZ C) + o, 5-14.0%, R2O (R is an alkali metal) 10.0-32.0%, ZnO
1, () ~ 15. O%, Bz O* 0.5-14.0
High strength glass consisting of %.

(2) (a) Based on weight, SiO260.0-70,
0%, Ant 031. O~14.0%, R2O (where R is an alkali metal) 10.0~32.0%, ZnO1
,0 to 15.0%, Btu30.5 to 12.0%, and (b)Based on weight, PbO, BaO1ZrOz, T
i0z, ASZ 03, Sbz Ox, MgO, 5r
At least one selected from optional components of O1CaO
High-strength glass containing 12% or less of seed additives.

Claims (2)

[Claims] (1) Based on weight, SiO_260.0-70.0%
, Al_2O_30.5-14.0%, R_2O (where R is an alkali metal) 10.0-32.0%, ZnO1
．． High strength glass consisting of 0-15.0% and B_2O_30.5-14.0%. (2) (a) Based on weight, SiO_260.0-70
．． 0%, Al_2O_31.0-14.0%, R_2O
(R is an alkali metal) 10.0 to 32.0%, Z
nO1.0-15.0%, B_2O_30.5-12.
(b) Based on weight, PbO, BaO, ZrO_2, TiO_2, As_2O_3, Sb_2O
A high-strength glass containing 12% or less of at least one additive component selected from optional components such as _3, MgO, and SrO.