【発明の詳細な説明】[Detailed description of the invention]
＜産業上の利用分野＞
本発明は天然に大量に存在し、現在あまり多く
は利用されていないシラスをはじめとする火山ガ
ラス質堆積物を有効に活用し、強度が大なるガラ
スを製造する方法に関するものである。
＜従来の技術＞
火山ガラス堆積物はSiO2を主成分として約70
重量％、その他にAl2O3，Na2O，K2O等を含む
一種のけい酸塩であり、我が国に広く分布してお
り、その利用方法も多く研究されている。例え
ば、南九州に広く分布する火山ガラス質堆積物の
一種であるシラスの利用方法の一つとしてガラス
への応用があり、特公昭52―17338号公報で示さ
れる様な方法が提案されている。この特公昭52―
17338号公報で示されるのは、シラスに対して
CaO，ZrO2及びZnOを添加して、耐アルカリ性
に富んだガラスを製造しようとする方法である。
＜発明が解決しようとする問題点＞
上記した特公昭52―17338号公報で示される方
法によるガラスは、耐アルカリ性には富むが、そ
の強度が弱く特殊な用途にしか利用出来ないとい
う欠点があつた。
本発明は先に火山ガラス質堆積物を原料とし強
度が大なるガラスを製造し得る方法を開発し、既
に特許出願（特願昭60―266651号）を行なつてい
る。
この特願昭60―266651号による方法は、今迄活
用度が低かつた火山ガラス質堆積物を活用し、相
当の強度を有するガラスを得るという目的は達成
出来るものの、その後の研究により製造に要する
時間が長過ぎる、更にはなお強度不足であるとい
う更なる要改良点のある事が判明した。
本発明はそれらの要改良点を満足すべきガラス
の製造法を提供する事を目的とする。
＜問題点を解決する為の手段＞
本発明は上記目的を達成する為に次の如き方法
を採用するものである。即ち、Al2O3粉末５〜８
重量％、Li2O粉末５〜９重量％、残部火山ガラ
ス質堆積物粉末なる配合の混合粉末を、加熱溶融
した後、歪除去処理を施し、更に500〜650℃の温
度下で12〜24時間再加熱することを特徴とする強
化ガラスの製造法である。
上記混合粉末中のAl2O3は、得られるガラスの
マトリツクスを強化し、ガラスの強度を高める働
きを奏するものであり、その強度向上の効果は５
重量％未満では顕著ではないが、８重量％を越え
るとガラスの融点が高くなり過ぎる為にAl2O3の
量は５〜８重量％の範囲が望ましい。又Li2Oは
β―スポデユーメン（Li2O，Al2O3，4SiO2）結
晶の成長核となり、ガラスを強化せしめるもので
あり、その効果は５重量％未満では顕著でなく、
一方９重量％を越える如く多量になると、融点が
低下し過ぎ、結晶が粗大化して逆に強度低下があ
るのでLi2Oの量は５〜９重量％の範囲が望まし
い。
又歪除去処理の後の再加熱は、得られるガラス
が出来る限り微細結晶である事の要性から、必要
最低の温度範囲及び加熱時間を決めたもので、温
度は500〜650℃、時間は12〜24時間の範囲とし
た。
＜実施例及び作用＞
以下本発明の実施例を示し、他の比較例と比較
考量し乍ら本発明方法を詳述する。
この実施例では、火山ガラス質堆積物として鹿
児島県吉田町に産する所謂吉田シラスを用いた。
その吉田シラスの科学組成を下記第１表に示す。
この様な吉田シラスの未水洗品粉末97.60ｇ、市
販のAl2O3粉末7.11ｇ、市販Li2CO3粉末6.07ｇを
基本とし、Ig・Lossにより換算した場合で吉田
シラス102.93ｇ、Al2O37.11ｇ、Li2CO315.01ｇと
なる量ずつを混合して混合粉末を得た。この混合
粉末化学組成も同じく下記第１表に示す。
<Industrial Application Field> The present invention is a method for manufacturing glass with high strength by effectively utilizing volcanic glassy deposits such as whitebait, which exists in large quantities in nature but is currently not used in large quantities. It is related to. <Conventional technology> Volcanic glass deposits contain approximately 70% of SiO 2 as the main component.
It is a type of silicate containing Al 2 O 3 , Na 2 O, K 2 O, etc. in addition to weight%, and is widely distributed in Japan, and its usage is being studied extensively. For example, one method of using whitebait, which is a type of volcanic glassy deposit widely distributed in southern Kyushu, is to apply it to glass, and a method such as that shown in Japanese Patent Publication No. 17338/1983 has been proposed. . This special public service, Showa 52-
What is shown in Publication No. 17338 is for whitebait
This method attempts to produce glass with high alkali resistance by adding CaO, ZrO 2 and ZnO. <Problems to be Solved by the Invention> Although the glass produced by the method disclosed in Japanese Patent Publication No. 17338/1988 has high alkali resistance, it has the disadvantage that its strength is low and it can only be used for special purposes. Ta. The present invention has previously developed a method for manufacturing strong glass using volcanic glassy deposits as a raw material, and has already filed a patent application (Japanese Patent Application No. 266651/1982). Although the method described in Japanese Patent Application No. 60-266651 can achieve the objective of obtaining glass with considerable strength by utilizing volcanic glassy deposits that have not been utilized to date, subsequent research has made it difficult to manufacture. It was found that further improvements were needed, such as the time required being too long and furthermore, the strength being insufficient. It is an object of the present invention to provide a method for manufacturing glass that satisfies these improvements. <Means for Solving the Problems> The present invention employs the following method in order to achieve the above object. That is, Al 2 O 3 powder 5-8
After heating and melting a mixed powder with a composition of 5 to 9 weight % Li 2 O powder and the balance volcanic glassy deposit powder, it was subjected to strain removal treatment and further heated at a temperature of 500 to 650°C for 12 to 24 hours. This is a method for producing tempered glass characterized by reheating for a period of time. Al 2 O 3 in the above mixed powder strengthens the matrix of the resulting glass and increases the strength of the glass, and the strength improvement effect is 5.
If it is less than 8% by weight, it is not noticeable, but if it exceeds 8% by weight, the melting point of the glass becomes too high, so the amount of Al 2 O 3 is preferably in the range of 5 to 8% by weight. In addition, Li 2 O serves as a growth nucleus for β-spodumene (Li 2 O, Al 2 O 3 , 4SiO 2 ) crystals and strengthens the glass, and this effect is not noticeable at less than 5% by weight.
On the other hand, if the amount exceeds 9% by weight, the melting point will drop too much, the crystals will become coarse and the strength will decrease, so the amount of Li 2 O is preferably in the range of 5 to 9% by weight. In addition, for reheating after the strain removal treatment, the minimum necessary temperature range and heating time were determined because it is necessary for the obtained glass to be as finely crystalline as possible. The period ranged from 12 to 24 hours. <Examples and Effects> The method of the present invention will be described in detail below by showing examples of the present invention and comparing and considering other comparative examples. In this example, so-called Yoshida shirasu produced in Yoshida-cho, Kagoshima Prefecture was used as a volcanic glassy deposit.
The scientific composition of Yoshida whitebait is shown in Table 1 below.
Based on 97.60 g of unwashed powder of Yoshida whitebait, 7.11g of commercially available Al 2 O 3 powder, and 6.07g of commercially available Li 2 CO 3 powder, Yoshida whitebait is 102.93g and Al 2 when converted by Ig/Loss. A mixed powder was obtained by mixing 7.11 g of O 3 and 15.01 g of Li 2 CO 3 . The chemical composition of this mixed powder is also shown in Table 1 below.
【表】
上記混合粉末を、白金皿に入れ、これを電気炉
内にて1600℃で１時間溶融しカレツトを造つた。
次にこのカレツトを74メツシユ以下に粉砕し、再
び白金皿に入れ、電気炉内にて1600℃１時間溶融
を行ない、引き続いて歪除去処理を行なつた。こ
の歪除去処理は上記溶融に用いた電気炉とは別に
600℃に保持した炉内に、ステンレス鋼製の蓋付
容器を入れ、その中に更にカーボン製の蓋付容器
を入れ、該カーボン製容器の周囲にはコークス粉
を詰めた状態の容器を準備し、上記白金皿内の溶
融状混合物をそのカーボン製容器に移し、施蓋状
態下に30分間保持後除冷するという方法を採つ
た。この様にして得られたガラスを切断、研磨し
て５×５×15（mm）の試料を作り、その後500〜
660℃の範囲で20℃置きの各温度にて、それぞれ
一日間保持した後除冷した製品の曲げ強度を測定
した結果を図面に示す。
この結果から再加熱温度が500℃未満では得ら
れるガラスの強度が市販コツプ用のガラスのそれ
と比べあまり向上しておらず、その後次第に向上
をするが、一方620℃を越えると再び市販ガラス
の強度に近ずく事、強度向上が著しいのは520〜
580℃の範囲である事が判る。
特に再加熱温度が540℃の場合は6100Kg／cm2な
る大きな値を示しており、これは市販ガラスと比
べれば勿論、先に本発明者等の出願した特願昭60
―266651号による方法の場合が670℃、７日間の
加熱で最高4540Kg／cm2となる値と比べても著しく
大きな値である。
＜発明の効果＞
以上述べて来た如く、本発明によれば短時間か
つ低温の再加熱処理で曲げ強度が大なるガラスを
得る事が出来、強度面での効果があると共に製造
は短時間かつ低コストで行なえるという利点があ
る。[Table] The above mixed powder was placed in a platinum dish and melted in an electric furnace at 1600°C for 1 hour to produce cullets.
Next, this cullet was pulverized to 74 meshes or less, placed again in a platinum dish, and melted in an electric furnace at 1600°C for 1 hour, followed by strain removal treatment. This strain removal process is carried out separately from the electric furnace used for the above melting.
A stainless steel container with a lid is placed in a furnace maintained at 600°C, a carbon container with a lid is placed inside the furnace, and a container filled with coke powder is prepared around the carbon container. Then, a method was adopted in which the molten mixture in the platinum dish was transferred to the carbon container, kept with the lid closed for 30 minutes, and then slowly cooled. The glass obtained in this way was cut and polished to make a 5 x 5 x 15 (mm) sample, and then 500~
The drawing shows the results of measuring the bending strength of products that were held at various temperatures of 20°C in the range of 660°C for one day and then slowly cooled. These results show that when the reheating temperature is lower than 500°C, the strength of the glass obtained does not improve much compared to that of commercially available glass for pots, and then gradually improves, but on the other hand, when the reheating temperature exceeds 620°C, the strength of commercially available glass returns. It approaches 520 and the strength improvement is remarkable.
It can be seen that the temperature is in the range of 580℃. In particular, when the reheating temperature is 540℃, it shows a large value of 6100Kg/ cm2 , which is of course higher than that of commercially available glass, and it is also a large value when compared with commercially available glass.
This value is significantly larger than the maximum value of 4540 Kg/cm 2 obtained by heating at 670°C for 7 days using the method according to No. 266651. <Effects of the Invention> As described above, according to the present invention, glass with high bending strength can be obtained by reheating in a short time and at a low temperature, which is effective in terms of strength and can be manufactured in a short time. It also has the advantage of being low cost.
【図面の簡単な説明】[Brief explanation of drawings]
図面は本発明実施例で得たガラスの曲げ強度を
示すグラフ。
The drawing is a graph showing the bending strength of glasses obtained in Examples of the present invention.