JPH0440301B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to electrical, electronic components, magnetic recording, optical recording,
Magneto-optical devices and reproducing devices, especially memory disks, soft and (fixed) hard disks, optical disks, magneto-optical disks, magnetic disk substrates, etc., which serve as storage elements for magnetic, optical, and magneto-optical devices, and disk substrates for high-strength, high-density recording; The present invention relates to mold materials for molding resin moldings, particularly disk substrates, resin lenses for eyeglasses, and other resin products. (Conventional technology) With the recent advances in electronics technology, especially information-related technology represented by computers,
Responses to a more full-fledged information society have already begun. Optical disk memory, which uses semiconductor lasers to quickly record and reproduce information such as documents, data, photographs, and TV images, has a recording density 50 to 500 times that of conventional magnetic memory, and can store large amounts of information. It has been put into practical use as a device for Optical disk memory ranges from CD (compact disk) and VD (video disk) to CD-ROM,
This has evolved into write-once disks, and it is expected that magneto-optical disks, which can be erased, read and written, will appear soon. The characteristics of optical memory are as follows. - Recording and playback is possible without contact. - Random access is possible. - Copy discs are cheap.・High density and high capacity are possible. While taking advantage of the above features, optical disks
From consumer products such as VD and CD, to video filing,
Applications are expanding to office automation equipment such as document filing, and information processing equipment, and in the future, even higher reliability and high speed will be an issue in order to expand into computer applications. At present, plastics, which are inexpensive and have excellent processability, are overwhelmingly used as materials for these disk substrates, and some optical discs for write-once large code data are being tested using chemically reinforced materials. Only. The chemically strengthened glass mentioned above includes crystallized glass, a glass substrate in which only the surface thin layer is chemically strengthened by ion exchange (replacing Na+ with K+), and the like. Glass whose surface thin layer has been chemically strengthened has a surface layer (reinforced layer) 2 of a glass substrate 1, as shown in FIG.
is chemically strengthened, and has a film (or laminating material) 3 on the surface layer 2. In this case, the surface layer 2 needs to be in compression with respect to the substrate 1, and the film material 3 needs to be in tension with respect to the surface layer 2. (Problems to be Solved by the Invention) Plastic substrates have drawbacks such as deformation due to heat, birefringence, and warping due to moisture absorption, making them unsuitable for achieving high density and high capacity. In addition, the chemically reinforced substrate has the disadvantage that if the substituted ions enter the surface layer 2 too deeply, a peeling phenomenon or a cracking phenomenon occurs in the direction of shrinkage. In order for the film material 3 and the glass substrate 1 to form a composite, it is necessary to match the expansion coefficients of the glass substrate 1 and the film material 3.
However, regardless of whether the film material 3 is inorganic or organic, the surface layer 2 is eroded due to reaction phenomena such as ion movement from it and its strength is reduced, and if tensile stress is applied in some form through the mating surfaces, Explosive destruction may occur. As described above, glass substrates made of chemically strengthened glass are extremely dangerous, and in many cases it is impossible to use them other than by themselves. As described above, plastic and glass as substrate materials each have advantages and disadvantages, and will be used depending on the purpose. However, it cannot be used as a disk material that will require higher performance in the future. The substrate for optical and magnetic disks must be a glass-ceramic substrate that has properties such as heat resistance, mechanical strength, high processing precision, and non-birefringence. Considering the required characteristics of the substrate in line with future technological trends, the position of the light spot in optical disks is controlled electro-optically, but this control is limited by the physical range, so The mechanical properties must also be sufficiently good. If there is undulation in the peripheral direction or orientation of the material, surface deflection will occur due to the heat generated by frictional resistance during rotation, and if the curvature is large, it will come into contact with the lens surface, and if the eccentricity is large, it will not work properly. becomes unstable. Therefore, not only are the flatness and concentricity of the substrate particularly important factors, but the disk substrate also serves as protection for the recording medium, so it is desirable that it be resistant to environmental conditions such as temperature, humidity, and mechanical strength. It will be done. Since some recording media may be exposed to high temperatures during film formation, heat resistance is desired, and as for optical properties, high transmittance is desired due to 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 noise more likely to occur. Particularly in the case of magneto-optical disks, since signals are detected using rotation of the plane of polarization of light, the presence of birefringence in the substrate is a major hindrance. Also, changes in the tilt and thickness of the substrate cause optical aberrations. The present invention provides a high-strength glass that eliminates the drawbacks of the above-mentioned prior art, and has the following features: - Does not allow oxygen or moisture in the air to pass through, preventing deterioration of the recording film - Virtually no birefringence - Does not warp due to moisture absorption - The objective is to provide an ideal material that has the following properties: good surface smoothness and resistance to scratches, high rigidity and no deformation during rotation, high processing accuracy, and resistance to eccentric surface runout. (Means for solving the problems) The present invention is based on weight, SiO ₂ 58.0-85.0%,
Al ₂ O ₃ 0.5-15%, R ₂ O (R is an alkali metal) 2.0-25.0%, BaO 0.2-20.0%, CaO 0.2-
20.0%, ZrO ₂ 0.1-6.0%, SO ₃ 0.1-3.0% and halogen ions 0.1-9.0%, and BaO and
This glass is characterized in that part of CaO and part of SO ₃ are reheated to uniformly disperse microcrystals of mainly barium sulfate and potassium sulfate. Regarding the composition of the glass-ceramic of the present invention, as shown in Japanese Patent Publication No. 17113/1983, crystallization of mainly calcium sulfate and barium sulfate occurs in the glass. In the present invention, further
By heat-treating the glass base after adding ZrO ₂ , the fine crystals described above are dispersed, become a compression factor, and are uniformly dispersed in the glass. It has been found that in the presence of halogen ions, it is possible to precipitate in a constant state (5 to 6% by volume) from the feedstock during operation, preferably by heat treatment, and based on this knowledge the present invention was made. . When crystal grains are precipitated by an appropriate reheating treatment in a conventionally used glass composition, it is difficult to control the growth rate of the grains in the glass matrix, and considerable skill is required to manufacture the crystal grains. The transparent and semi-transparent glasses produced tend to have uneven numbers and particle diameters of particles dispersed therein. When this material is processed, it has the disadvantage that cracks occur due to local differences in thermal expansion coefficients, resulting in damage to the product. The present invention was developed as a result of various researches aimed at improving the drawbacks of conventional transparent and translucent crystallized glasses and developing high-strength glass that can be manufactured under simple quality control. By reconsidering the composition of calcium sulfate and barium sulfate grain nuclei or crystal grains as shown in Publication No. 58-17133 and reheating, it was possible to control the state of precipitation occurring in the glass base. In the present invention, CaO, BaO, SO ₃ and halogen ions can be added to the glass whose basic components are SiO ₂ , Al ₂ O ₃ , R ₂ O (where R is the same as above) and ZrO ₂ . is necessary. and CaO
BaO and SO ₃ , which was conventionally used in small amounts as a glass manufacturing atmosphere adjustment and fining agent, are used as a source of a crystallization agent, and halogen ions, especially chlorine, are used in combination as a mineralizing agent to promote crystal growth. . Particles such as fluorides are not precipitated into the glass. By precipitating microcrystalline particles of calcium sulfate or barium sulfate through reheat treatment, translucent and translucent high-strength glass can be obtained. BaSO ₄ , CaSO ₄ whose growth is controlled to a maximum particle size of 0.3μ by reheating the glass in the metastable region
During the cooling process, compressive stress is generated due to the difference in occupied volume, and this remains in the glass, increasing its strength. _SiO2 in the basic components of the present invention needs to be in the range of 58.0-85.0% based on the total weight. If this amount exceeds 85%, it becomes difficult to melt and workability decreases. If this amount is less than 58.0%, scientific durability will deteriorate. Next, Al ₂ O 3 is used for purposes such as controlling or promoting crystal precipitation into the glass matrix, improving scientific durability and adjusting the viscosity of molten glass, but if the amount is less than 0.5%, these Moreover, if it exceeds 10.0%, the viscosity of the glass increases more than necessary, making it difficult to handle, which is not preferable. ZrO ₂ is an important component that mainly controls the precipitation of BaSO ₄ and CaSO ₄ in the molten glass, and at the same time enhances the strength of the glass before reheating and improves its chemical stability. _ZrO2 is 6.0
%, it becomes difficult to melt the glass. Furthermore, the alkali metal oxide, i.e. R ₂ O,
It is used in a range of 2.0 to 25.0% for the purpose of adjusting the viscosity and coefficient of thermal expansion of glass and lowering the melting temperature. If this amount is less than 2.0%, the glass becomes poorly soluble, and if it exceeds 25.0%, the viscosity not only decreases too much, but also causes deterioration in chemical properties and interference with particle crystallization, which is not preferable. In the present invention, CaO and BaO are added to bring about a translucent and transparent state through heat treatment.
should be in the range of 0.2 to 20.0%, respectively,
If these amounts are less than 0.2%, precipitation of calcium sulfate and barium sulfate microcrystals will be insufficient.
If the amount exceeds 20.0%, it is not preferable because it will adversely affect the stability against devitrification and the scientific durability of the glass. On the other hand, the amount of SO ₃ is chosen within the range of 0.1-3.0%.
If this amount is less than 0.1%, precipitation of crystals by heat treatment will be insufficient, and if this amount exceeds 3.0%,
This may cause corrosion of the melting equipment and contamination of the glass.
The amount of halogen ions is selected within the range of 0.1 to 9.0%, with chlorine preferably within the range of 0.1 to 6.0%. If this amount is less than 0.1%, the effect of promoting crystal precipitation during heat treatment will be insufficient, and if it exceeds 9.0%, it will cause corrosion of manufacturing equipment, which is inappropriate. In particular, ZrO ₂ can be used in combination with BaO, CaO and SO ₃ and with Cl and F as promoters to relax the conditions for crystallization of transparent crystals by reheating, allowing a wide composition range to be obtained. In addition to the above-mentioned basic components, the glass of the present invention further contains B ₂ O ₃ , AsO ₃ ,
At least one optional component selected from Sb ₂ O ₃ , TiO ₂ , ZuO, MgO, SrO, and PbO can be contained. These are added to improve the meltability, clarity, etc. of glass, but based on weight, B ₂ O ₃ is 5.0% or less, AS ₂ O ₃ ,
1.0% or less for Sb ₂ O ₃ , and less than 1.0% for TiO ₂ .
Even if it is contained within the range of 6.0% or less, mainly
No change occurs in the precipitation of crystal particles due to heat treatment of CaSO ₄ and BaSO ₄ . In particular, heat treatment in crystallization treatment is more effective in an atmosphere, and hydrogen gas or forming gas ( _H2
+N ₂ ) treatment results in good ion diffusion, resulting in a glass-ceramic with higher strength and translucency. This is probably because Cl and F as auxiliaries in the glass become HF and HCl and exit from the glass due to internal diffusion of hydrogen gas, leading to strengthening of the glass matrix. In both cases, only traces were detected as analytical values. The glass of the present invention can be easily manufactured by mixing the raw materials of each component at room temperature, charging the raw materials into a melting furnace, heating and melting at 1350 to 1500°C for several hours to over 10 hours, and then slowly cooling. Obtain a good glass base.
High strengthening treatment is reheat treatment, i.e. 560~580℃30
After holding at 630-650°C for 30 minutes and at 700-720°C for 60-90 minutes, slow cooling is performed. The present inventor discovered that during its production, the crystals of CaSO ₄ and BaSO ₄ mainly grew at a very slow rate in the glass matrix, and that the glass matrix was not subjected to the above-mentioned chemical strengthening treatment (ion-strengthening treatment). exchange)
is also possible. In addition, since the glass of the present invention has a homogeneous and stable state, it does not crack itself during processing, and even breaks when bonded to other glass substrates or films due to local differences in thermal expansion coefficients. It will not lead to (Example) Next, the present invention will be explained in detail with reference to Examples. Table 1 shows the composition of the eight samples. Note that all percentages in each example are based on weight. The blended raw materials are put into an open crucible and heated to approximately 1450 ml.
After heating and dissolving at ℃ for 10 hours, slowly cooling for 3 hours,
Obtained by reheating. Reheating treatment conditions are 560℃ 30 minutes, 630℃ 30 minutes,
The temperature was maintained at 705°C for 60 minutes and slowly cooled. Crystal analysis revealed that mainly BaSO ₄ and CaSO ₄
was detected, and the glass was translucent. Table 2 shows the physical properties of sample number 2 glass.
Shown below.

【table】

【table】

【table】

[Table] (Effects) Since the present invention has the above structure, the glass of the present invention has excellent mechanical properties such as bending strength and hardness, and therefore not only can the wall thickness be made thinner, but also the recording density can be raised. Moreover, since high surface smoothness (surface roughness 15 to 20 A) and high flatness (2 μm or less) can be obtained, an ideal glass substrate for high-density recording can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing conventional tempered glass. 1 is a glass substrate, 2 is a surface layer of the glass substrate, 3
is membranous.

Claims (1)

[Claims] 1 Based on weight, SiO ₂ 58.0-85.0%, Al ₂ O ₃ 0.5
~15%, _R2O (where R is an alkali metal) 2.0~
25.0%, BaO0.2~20.0%, CaO0.2~20.0%,
It consists of ZrO ₂ 0.1-6.0%, SO ₃ 0.1-3.0% and halogen ions 0.1-9.0%, and a part of BaO and CaO is mainly mixed with a small amount of barium sulfate and potassium sulfate by reheating along with a part of SO ₃ . Glass characterized by being formed by uniformly dispersing crystals. 2 (a) Based on weight, SiO ₂ 58.0-85.0%, Al ₂
O ₃ 0.5-15.0%, R ₂ O (R is an alkali metal) 2.0-25.0%, BaO 0.2-20.0%, CaO 0.2-
Basic component 89.0 consisting of 20.0%, ZrO ₂ 0.1-6.0%, SO ₃ 0.1-3.0% and halogen ions 0.1-9.0%
% or more, (b) B ₂ O ₃ , Sb ₂ O ₃ , As ₂ O ₃ , TiO ₂ , ZnO, MgO,
Contains 11.0% by weight or less of at least one additive component selected from optional components such as SrO and PbO, and a part of BaO and CaO is mainly converted to barium sulfate and calcium sulfate by reheating with a part of SO ₃ . A glass characterized by being formed by uniformly dispersing microcrystals.