JP3896733B2 - Optical glass for press-molded lenses - Google Patents
Optical glass for press-molded lenses Download PDFInfo
- Publication number
- JP3896733B2 JP3896733B2 JP26413799A JP26413799A JP3896733B2 JP 3896733 B2 JP3896733 B2 JP 3896733B2 JP 26413799 A JP26413799 A JP 26413799A JP 26413799 A JP26413799 A JP 26413799A JP 3896733 B2 JP3896733 B2 JP 3896733B2
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- JP
- Japan
- Prior art keywords
- temperature
- press
- glass
- optical glass
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/062—Glass compositions containing silica with less than 40% silica by weight
- C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
Description
【0001】
【産業上の利用分野】
本発明は比較的低温でプレス成形が可能な低融点光学ガラスに関する。
【0002】
【従来の技術】
近年、研磨を必要としない精密プレス成形によるレンズ製造法が広く行われている。その際、成形型の損傷を少なくなくする為、出来るだけ低い温度でプレス成形が可能な低融点ガラスを用いる必要がある。
【0003】
レンズ等の精密光学部品は、その光学恒数としては、屈折率(nd)が1.51〜1.57で、アッベ数(νd)が50〜63近辺のものが好適に用いられるが、このような光学恒数を有する光学ガラスは従来から生産されている。しかしながら、そのガラス組成としては、SiO2 含量が多く高粘性のため、プレス成形温度が高すぎるのが通例である。また、融点を低くするためにPbOを含有させたものも知られている。これによって、比較的融点の低い低融点ガラスが得られるが、それをプレス成形する際には、Pbが表面に析出して型と反応するため、成形型における成形面が荒れることから、成形型を頻繁に洗浄しなければならず、従って工業的規模でプレス成形を行うためのガラス素材として必ずしも適切なものではない。
【0004】
以上のような課題を解決するために、特開平5―193979号公報には、重量パーセントで、SiOが39〜65%、B2 O3 が10〜38%,Li2 Oが3〜12%、Na2 Oが0〜7%、K2 Oが0〜6.5%であり、かつLi2 OとNa2 OとK2 Oの合計量が9〜18%、さらにAl2 O3 が5〜15%、MgOが0〜6%、CaOが0〜6%、BaOが0〜6%の組成からなり、560℃以下の屈伏温度を有し、屈折率(nd)が1.51〜1.54、アッベ数(νd)が62〜65.5という光学恒数を有するプレス成形用ガラス素材が開示されている。
【0005】
【発明が解決しようとする課題】
前述した従来技術のガラス組成は、具体的には、その屈伏温度が514〜559℃であり、実際には、さらにこの屈伏温度より30〜50℃程度高い温度で成形されることになる。ところで、成形型の保護及びその長寿命化を図るには、成形温度をできるだけ低く抑制しなければならない。一般的な成形型の場合、実質的に600℃乃至その近傍の温度が使用限界であり、この使用限界温度に近づけば近づくほど成形型の損傷の可能性が高くなる。従って、プレス成形時の温度はこの使用限界温度から僅かでも低くできれば、それだけ成形型の寿命の点で著しく大きな差となって現れる。
【0006】
以上の点に鑑みて、本発明者は、レンズ等の精密光学部品として必要な光学恒数を有し、かつより低融点となるプレス成形用のガラス組成を得るべく鋭意研究を行った結果、粘性を高める成分であるSiO2 量が比較的少ない領域で、所定の範囲のB2 O3 、Al2 O3 、アルカリ金属酸化物を組み合わせることに依って、所期の目的を達成することを見出して、本発明を完成するに至った。しかして、本発明の目的とするところは、屈伏温度が500℃以下で、より低い温度でプレス成形が可能なプレス成形用光学ガラスを提供することにある。
【0007】
【問題を解決するための手段】
前述した目的を達成するために、本発明のプレス成形用光学ガラスの組成は、重量パーセントで、SiO2 が21〜37%、B2 O3 が22〜40%、Al2 O3 が10〜30%であり、かつSiO2 +B2 O3 +Al2 O3 が64〜83%、Na2 Oが3〜15%、K2 Oが0〜15%であり、かつLi2 O+Na2 O+K2 Oが14〜26%、さらにTiO2 +ZrO2 +Nb2 O5 +WO3 が0〜14%、BaO+SrO+CaO+MgO+ZnOが0〜14%からなるものであって、屈伏温度(Ts)が500℃以下、屈折率(nd)が1.51〜1.58、アッベ数(νd)が50〜63である。
【0008】
各成分範囲を以下のように限定した理由は次の通りである。
【0009】
まず、SiO2 、B2 O3 、Al2 O3 は必須成分である。その含量が64%未満では屈折率が高くなり過ぎ、83%を超えると屈伏温度が高くなり過ぎる。これらのうち、SiO2 量の範囲が本発明において特に重要であり、37%以下に保つことが500℃以下の屈伏温度を得るのに特に有効である。ただし、21%未満では化学的恒久性が劣化する。B2 O3 は40%を超えると化学的耐久性が劣化し、22%未満では屈伏温度が上昇しすぎると共に溶融性が悪くなる。Al2 O3 は分相傾向を抑制し、化学的耐久性を良くするのに10%以上必要であり、特にB2 O3 含量が多いところで有効に作用するが、30%を超えると屈伏温度が上昇しすぎる。
【0010】
アルカリ金属酸化物は低融点化、耐失透性向上、溶融点性改善のため、含量で14%以上必要であるが、26%を超えると化学的耐久性が劣化し過ぎる。アルカリ金属酸化物のうち、低融化効果の高いLi2 O、Na2 Oは本発明の必須成分である。それぞれ1%及び3%以上必要であるが、各々10%及び15%を超えると化学的耐久性が劣化する。K2 Oは任意配合成分であり、溶融性の改善、屈折率の調整等のために使用できるが、15%を超えると化学的耐久性が劣化する。
【0011】
TiO2 、ZrO2 ,Nb2 O5 ,WO3 は任意配合成分であり、主として光学恒数の調整に用いられるが、含量で14%を超えると分相傾向が増大すると共に屈伏温度が高くなり過ぎる。
【0012】
BaO,SrO,CaO,MgO,ZnOも任意配合成分であり、主として光学恒数の調整に用いられるが、含量で14%を超えると屈伏温度が高くなり過ぎる。なお、上記成分の他に、光学恒数の調整、化学的耐久性の改善等の目的で、本発明の目的に外れない範囲で、La2 O3 ,Ta2 O5 等を含有させることができる。また、脱泡材として少量のSb2 O3 ,F,Clなどを加えることも差し支えない。
【0013】
本発明の光学ガラスは酸化物、水酸化物、炭酸塩、硝酸塩等を使用し、所定の組成になるように秤量し、混合した後、白金性のるつぼを用い、電気炉で1150〜1300℃で溶解した上で、予熱した金型に鋳込み、徐冷することによって製造できる。
【0014】
【実施例】
次に、本発明の実施例について説明する。下記の表には、実施例1〜8で用いたガラスの成分組成を重量%で示し、併せて各実施例におけるガラスの光学恒数と屈伏温度とを示した。なお、表中において、屈折率(nd)、アッベ数(νd)は冷却温度−10℃/hourで徐冷して測定した値である。屈伏温度(Ts)は熱膨張計を用いて5℃/minで上昇した場合の測定値である。いずれも500℃以下の屈伏温度を有していた。
【0015】
次に、これらの組成から上記手順により、ガラスブロックを作り、切断、研削、研磨の加工工程を経て所定重量の研磨球を作製した。次にそれらを使ってプレス成形したところ、540〜570℃でプレス成形が可能であった。
【0016】
【表1】
【0017】
【表2】
【0018】
【発明の効果】
本発明によれば、比較的低温でプレス成形が可能であり、成形型の損傷を軽減でき、その長寿命化を図ることができ、光学ガラスの安定したプレス成形と低コスト化が実現できる等の効果を奏する。[0001]
[Industrial application fields]
The present invention relates to a low melting point optical glass that can be press-molded at a relatively low temperature.
[0002]
[Prior art]
In recent years, a lens manufacturing method by precision press molding that does not require polishing has been widely performed. At that time, in order to minimize damage to the mold, it is necessary to use a low-melting glass that can be press-molded at as low a temperature as possible.
[0003]
As precision optical components such as lenses, optical constants having a refractive index (nd) of 1.51 to 1.57 and an Abbe number (νd) of 50 to 63 are preferably used. Optical glass having such an optical constant has been conventionally produced. However, as the glass composition, the press molding temperature is usually too high because of the high SiO 2 content and high viscosity. In addition, one containing PbO in order to lower the melting point is also known. As a result, a low-melting glass having a relatively low melting point can be obtained. When press molding the glass, Pb precipitates on the surface and reacts with the mold, so that the molding surface in the molding die becomes rough. Must be washed frequently, and therefore is not necessarily suitable as a glass material for press forming on an industrial scale.
[0004]
In order to solve the above-mentioned problems, Japanese Patent Application Laid-Open No. H5-193979 discloses, in terms of weight percentage, 39 to 65% of SiO, 10 to 38% of B 2 O 3, and 3 to 12% of Li 2 O. , Na 2 O is 0 to 7% K 2 O is 0 to 6.5%, and the total amount of Li 2 O, Na 2 O and K 2 O is 9-18%, more Al 2 O 3 5 to 15%, MgO 0 to 6%, CaO 0 to 6%, BaO 0 to 6%, BaO has a yield temperature of 560 ° C. or less, and refractive index (nd) is 1.51 to 1.51. A glass material for press molding having an optical constant of 1.54 and an Abbe number (νd) of 62 to 65.5 is disclosed.
[0005]
[Problems to be solved by the invention]
Specifically, the above-described prior art glass composition has a yield temperature of 514 to 559 ° C., and is actually molded at a temperature higher by about 30 to 50 ° C. than the yield temperature. By the way, in order to protect the mold and extend its life, it is necessary to suppress the molding temperature as low as possible. In the case of a general mold, the temperature is practically 600 ° C. or a temperature in the vicinity thereof, and the closer to this service limit temperature, the higher the possibility of damage to the mold. Therefore, if the temperature at the time of press molding can be lowered even slightly from this use limit temperature, the difference in the life of the mold will appear as a significant difference.
[0006]
In view of the above points, the present inventors have conducted intensive research to obtain a glass composition for press molding having an optical constant necessary as a precision optical component such as a lens and having a lower melting point, Achieving the intended purpose by combining B 2 O 3 , Al 2 O 3 and alkali metal oxides in a predetermined range in a region where the amount of SiO 2 which is a component for increasing the viscosity is relatively small. As a result, the present invention has been completed. Therefore, an object of the present invention is to provide an optical glass for press molding that has a yield temperature of 500 ° C. or lower and can be press-formed at a lower temperature.
[0007]
[Means for solving problems]
To achieve the above object, the composition of the press-molding the optical glass of the present invention, in weight percent, SiO 2 is 21 to 37% B 2 O 3 is 22-40%, the Al 2 O 3. 10 to 30%, SiO 2 + B 2 O 3 + Al 2 O 3 64 to 83%, Na 2 O 3 to 15%, K 2 O 0 to 15%, and Li 2 O + Na 2 O + K 2 O Is 14 to 26%, TiO 2 + ZrO 2 + Nb 2 O 5 + WO 3 is 0 to 14%, BaO + SrO + CaO + MgO + ZnO is 0 to 14%, and the deformation temperature (Ts) is 500 ° C. or less, the refractive index (nd ) Is 1.51 to 1.58, and the Abbe number (νd) is 50 to 63.
[0008]
The reason why each component range is limited as follows is as follows.
[0009]
First, SiO 2 , B 2 O 3 and Al 2 O 3 are essential components. If the content is less than 64%, the refractive index becomes too high, and if it exceeds 83%, the yield temperature becomes too high. Of these, the range of the SiO 2 amount is particularly important in the present invention, and keeping it at 37% or less is particularly effective for obtaining a yield temperature of 500 ° C. or less. However, if it is less than 21%, the chemical permanence deteriorates. If B 2 O 3 exceeds 40%, the chemical durability deteriorates, and if it is less than 22%, the yield temperature increases excessively and the meltability deteriorates. Al 2 O 3 needs 10% or more to suppress the tendency of phase separation and improve chemical durability, and works effectively especially when the B 2 O 3 content is high. Rises too much.
[0010]
Alkali metal oxides require a content of 14% or more in order to lower the melting point, improve devitrification resistance, and improve the melting point. However, if it exceeds 26%, the chemical durability is excessively deteriorated. Of the alkali metal oxides, Li 2 O and Na 2 O, which have a high low melting effect, are essential components of the present invention. 1% and 3% or more are necessary respectively, but if it exceeds 10% and 15%, respectively, chemical durability deteriorates. K 2 O is an optional compounding component and can be used for improving the meltability and adjusting the refractive index. However, if it exceeds 15%, the chemical durability deteriorates.
[0011]
TiO 2 , ZrO 2 , Nb 2 O 5 , and WO 3 are optional components, and are mainly used for adjusting the optical constants. However, if the content exceeds 14%, the tendency to phase separation increases and the yield temperature increases. Pass.
[0012]
BaO, SrO, CaO, MgO, and ZnO are also optional components and are mainly used for adjusting the optical constant, but if the content exceeds 14%, the yield temperature becomes too high. In addition to the above components, La 2 O 3 , Ta 2 O 5, and the like may be included for the purpose of adjusting optical constants, improving chemical durability, and the like within the scope of the present invention. it can. Further, a small amount of Sb 2 O 3 , F, Cl or the like may be added as a defoaming material.
[0013]
The optical glass of the present invention uses oxides, hydroxides, carbonates, nitrates, and the like, weighed to have a predetermined composition, mixed, and then used a platinum crucible in an electric furnace at 1150 to 1300 ° C. It can be manufactured by melting it in, casting into a preheated mold, and slow cooling.
[0014]
【Example】
Next, examples of the present invention will be described. The following table | surface showed the component composition of the glass used in Examples 1-8 by weight%, and showed the optical constant and the sag temperature of the glass in each Example collectively. In the table, the refractive index (nd) and Abbe number (νd) are values measured by slow cooling at a cooling temperature of −10 ° C./hour. The yield temperature (Ts) is a measured value when it is increased at 5 ° C./min using a thermal dilatometer. All had a yield temperature of 500 ° C. or lower.
[0015]
Next, a glass block was made from these compositions according to the above-described procedure, and a polishing ball having a predetermined weight was prepared through processing steps of cutting, grinding, and polishing. Next, when they were used for press molding, press molding was possible at 540 to 570 ° C.
[0016]
[Table 1]
[0017]
[Table 2]
[0018]
【The invention's effect】
According to the present invention, press molding can be performed at a relatively low temperature, damage to the mold can be reduced, its life can be extended, stable press molding of optical glass and cost reduction can be realized, etc. The effect of.
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP26413799A JP3896733B2 (en) | 1999-09-17 | 1999-09-17 | Optical glass for press-molded lenses |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP26413799A JP3896733B2 (en) | 1999-09-17 | 1999-09-17 | Optical glass for press-molded lenses |
Publications (2)
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JP2001089183A JP2001089183A (en) | 2001-04-03 |
JP3896733B2 true JP3896733B2 (en) | 2007-03-22 |
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JP26413799A Expired - Fee Related JP3896733B2 (en) | 1999-09-17 | 1999-09-17 | Optical glass for press-molded lenses |
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Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JP3555681B2 (en) * | 2001-10-29 | 2004-08-18 | 日本電気硝子株式会社 | Glass for mold press molding |
JP4143840B2 (en) * | 2003-09-17 | 2008-09-03 | 五鈴精工硝子株式会社 | Glass for press molding |
JP4453328B2 (en) * | 2003-10-09 | 2010-04-21 | 日本電気硝子株式会社 | Mold press molding glass and method for producing the same |
KR101026853B1 (en) * | 2008-02-27 | 2011-04-06 | 전북대학교산학협력단 | Borosilicate glass composition, and artificial tooth using the same and method for fabricating artificial tooth |
CN109384385A (en) * | 2017-08-09 | 2019-02-26 | 成都尤利特光电科技股份有限公司 | Negative anomalous dispersion optical glass |
JP2019135202A (en) * | 2018-02-05 | 2019-08-15 | 株式会社オハラ | Optical glass |
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1999
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