200911712 九、發明說明 【發明所屬之技術領域】 本發明關於一種製造玻璃之精確結構預形體的方法。 此等預形體可用來製備微結構光纖。 【先前技術】 結構預形體對於微結構光纖的製備係重要的。 微結構光纖典型地可由埋置於氧化矽基質內且沿著纖 維的Z -軸延伸之空氣柱陣列於以描述。 微結構光纖之興趣係因其作爲習用光纖的替代產品之 有前景選擇而被激發啓動。新產品係建基於諸不同的光學 原理，其促成在不同條件下的波導（wave-guiding)，如 同光子能帶隙波導（photonic band gap guidance)。對於 在此等條件下的波導已觀察並報告出數項新的性質，與其 他一起者爲超連續光譜（supercontinuum)之產生，高雙 折射率，永久地單一模式行爲和低彎曲損失。（Sol-gel derived microstructured fibres fabrication and characterization (Ryan T. Bise and Dennis J. Trevor, OWL 6))。 微結構光纖首次係使用習用光學組件如玻璃管和桿， 將彼等捆在一起並抽成纖維所製造。 順著此種方式’數份文件教導有各種改良和應用的相 關技術，其中有：EP 0 810 453 A，EP 0 652 184 A， EP 0 905 8 34 A，JP 09 227 1 3 1 A 和日本專利摘要，V〇l. 200911712 1 9 9 8 η. 1 , Jan. 3 0, 1 998 ° 由ΕΡ 1 1 72 3 3 9 Β1得知如何可經由溶膠-凝膠技術便 利地模塑出結構預形體。其述及一種合適的模具用於使用 “驗性溶膠”模塑結構預形體，其說明於U S 5.2 4 0.4 8 8和 US 5.3 79.3 64 中。 ΕΡ 1 172 3 39 Β1的教導特別地指向，所謂的“鹼性溶 膠”，其在先前引述的二個技術專利中有明確的定義。 根據其教導，ΕΡ 1 1 72 3 3 9 Β1陳述如何用鹼性溶膠 來使用模具；申請專利範圍第1項，步驟b )，陳述：“ 以含氧化矽溶膠塡充該容器的至少一部份，並允許或導致 該溶膠成爲凝膠，使得產生具有該複數個伸長元件的凝膠 體”，其教導符合鹼性溶膠，即爲“含氧化矽溶膠”的使用 ;其沒有提及烷氧化物，其不存在於此等溶膠調合物中（ 於US 5.240.488和US 5.379.364中所定義者）。沒有給 出與先前引述的US專利中所定義的溶膠調合物一致地相 關之溶膠製備的實施例。爲清晰起見，於彼等專利中，溶 膠完全用氧化矽，於“鹼性pH”（溶膠-pH超過12 )下製 備。 ΕΡ 1 I 72 3 3 9 B1中指向並限制於“鹼性溶膠”的教導 顯示一項缺點。雖然鹼性溶膠確實可用於製備氧化矽玻璃 的大型體，例如，光纖預形體和特別者預形體外包層（ over-cladding )，不過以此等溶膠系統對於精細結構複製 所要求的精確性並不能容易地達成。事實上沒有證據顯示 此系統係理想地各向同性者；再者，其係具有，一般而言 -5- 200911712 ，低收縮率的特徵之系統，此表明對於此一模塑系統的精 確度要求，最終比對於更具收縮性的系統顯著地更爲嚴苛 。再者，該文件沒有針對凝膠的凝析給出建議。 【發明內容】 本發明的標的爲一種使用已知的溶膠凝膠法製造拉製 微結構光纖所用玻璃的精確結構預形體之方法，其特徵在 於將溶膠注入一裝有許多插入物之模具內且於水凝膠發生 凝析之前抽出該插入物。 本發明發現用於高效能微結構光纖的細微結構預形體 所需精確度可經由溶膠凝膠法有利地透過相對於先前技藝 爲非常不同的溶膠調配物和不同的模塑程序而達成。 本發明的方法係建基於複合溶膠，在酸條件下膠凝和 水凝膠的超臨界乾燥，其在特定條件下，可由透過對玻璃 的熱稠化所維持的熱機械理想的均向性之特性予以描述。 此一系統，在用於精確結構光纖預形體的製備時，可針對 產品品質和程序效益產生優良的結果。 本發明用於模具內部空間的精確複製的溶膠可爲複合 溶膠’其係用來自矽的烷氧化物，於酸性pH下水解之矽 酸和’在此等條件下不可水解的發煙矽石以適當的比例組 合衍生者。 矽的烷氧化物之酸水解必須用到酸條件以經由膠凝將 多孔網狀結構降低到最低尺寸。鹼性膠凝傾向於（而非變 成）相當大尺寸的粗大，非孔型，球狀成分之聚集。（C. -6 - 200911712BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of making a precise structural preform of glass. These preforms can be used to make microstructured fibers. [Prior Art] Structural preforms are important for the preparation of microstructured fibers. Microstructured fibers are typically described by an array of air columns embedded within a yttria matrix and extending along the Z-axis of the fiber. The interest in microstructured fiber was motivated by its promising choice as a replacement for conventional fiber optics. The new product architecture is based on different optical principles that contribute to wave-guiding under different conditions, such as photonic band gap guidance. Several new properties have been observed and reported for waveguides under these conditions, along with other generations of supercontinuum, high birefringence, permanent single mode behavior and low bending loss. (Sol-gel derived microstructured fibres fabrication and characterization (Ryan T. Bise and Dennis J. Trevor, OWL 6)). Microstructured fibers were first fabricated using conventional optical components such as glass tubes and rods, which were bundled together and drawn into fibers. In this way, 'several documents teach various related techniques for improvement and application, among which are: EP 0 810 453 A, EP 0 652 184 A, EP 0 905 8 34 A, JP 09 227 1 3 1 A and Japan Patent Abstract, V〇l. 200911712 1 9 9 8 η. 1 , Jan. 3 0, 1 998 ° From ΕΡ 1 1 72 3 3 9 Β1 Learn how to easily mold the structure through sol-gel technology Form. It describes a suitable mold for molding a structural preform using an "acceptable sol" as described in U S 5.2 4 0.4 8 8 and US 5.3 79.3 64.教导 1 172 3 39 The teachings of Β1 are specifically directed to the so-called "alkaline sols", which are clearly defined in the two technical patents previously cited. According to its teachings, ΕΡ 1 1 72 3 3 9 Β1 states how to use the mold with an alkaline sol; patent application scope 1, item b), states: “filling at least a portion of the container with a cerium oxide-containing sol And allowing or causing the sol to become a gel, such that a gel having the plurality of elongate members is produced, the teaching of which is consistent with the use of an alkaline sol, ie, a "cerium oxide-containing sol"; It is not present in such sol blends (as defined in US 5.240.488 and US 5.379.364). No examples of sol preparations consistent with the sol blends defined in the previously cited U.S. patent are given. For the sake of clarity, in their patents, the sol is completely prepared with cerium oxide at "alkaline pH" (sol-pH over 12). ΕΡ 1 I 72 3 3 9 The teachings in B1 that point to and limit to “alkaline sols” show a disadvantage. Although alkaline sols can be used to prepare large bodies of yttria glass, for example, fiber preforms and special over-cladding, the accuracy required for such sol systems for fine structure replication is not Easy to achieve. In fact, there is no evidence that the system is ideally isotropic; moreover, it has, in general, -5 to 200911712, a system of low shrinkage characteristics, which indicates the accuracy requirements for this molding system. It is ultimately significantly more stringent than for a more contractile system. Again, this document does not give advice on the condensate of the gel. SUMMARY OF THE INVENTION The subject matter of the present invention is a method of making a precise structural preform of a glass for drawing a microstructured fiber using a known sol-gel process, characterized in that a sol is injected into a mold containing a plurality of inserts and The insert is withdrawn prior to condensate formation of the hydrogel. The present inventors have discovered that the precision required for fine structure preforms for high performance microstructured fibers can be advantageously achieved by sol gel processes through very different sol formulations and different molding procedures relative to prior art techniques. The method of the present invention is based on a composite sol, gelation under acidic conditions and supercritical drying of a hydrogel which, under certain conditions, can be maintained by a thermomechanical ideality that is maintained by thermal thickening of the glass. The characteristics are described. This system produces excellent results for product quality and program efficiency when used in the fabrication of precision structured fiber preforms. The sol of the present invention for the precise replication of the internal space of the mold may be a composite sol which is alkoxides derived from hydrazine, citric acid hydrolyzed at acidic pH and 'smoulderite which is not hydrolyzable under such conditions. The appropriate proportions are combined with the derivatives. The acid hydrolysis of the alkoxide of hydrazine must be carried out under acidic conditions to reduce the porous network to a minimum size via gelation. Alkaline gelation tends to (rather than become) a coarse, non-porous, globular component of considerable size. (C. -6 - 200911712
Jeffrey Brinker，George W· Scherer，SOL-GEL SCIENCE， pages 9 9-1 07 ) o 溶膠製備可基於下面所述特定程序： 矽的烷氧化物於水中的酸催化水解；水對矽烷氧化物 的莫耳比例可爲介於4與4 8之間。 在水解之前水之pH可爲從1.0至3.0 :較佳條件可爲 從 1 . 5 至 2.5。 在水解中以“發煙矽石”存在的二氧化矽可爲不超過 4/1的二氧化矽/矽烷氧化物莫耳比例。 溶膠中所含總二氧化矽可能不超過4/1的二氧化矽/ 烷氧化矽莫耳比例。 液相之選擇性萃取可經由減壓-蒸餾完成。此可完全 地或部份地完成。 選擇性地，可進行溶膠的機械及/或超聲波勻化。 溶膠的除氣可經由超聲波及/或減壓，及/或氦氣泡 完成。除氣步驟可幫助從溶膠移除氣泡。 若需要額外的一致性，可選擇性地對溶膠於550至 6 5 0“g”下進行離心。離心不是本發明方法所必要者。因此 ，此步驟可選擇性地進行。但，若有進行，其可導致一較 平滑的表面。 溶膠的p Η -値可調整到3 · 5至4.1，較佳者3.6 5至 3.80的範圍內以起始膠凝化。該調整可經由添加游離鹼所 完成。 溶膠可經塡充至用於所欲精確結構水凝膠的製備所用 200911712 模具內。 模具可按下述製備：製備適當的柱狀容器（“管狀，，） ，裝配有適當數量的插入物（內模具），藉由適當的材料 選擇或經由該等材料的適當表面處理其以提供模具關鍵表 面所需的抗黏著特質。具有系列之平行於水凝膠軸向的柱 體之柱狀水凝膠的精確結構化所用方法可建基於系列的突 出到凝膠內且於水凝膠的凝析發生之前可抽出之長形元件 。如於模塑中常見，且特別用於溶膠-凝膠模塑者，模具 的具有適當尺寸之內部空間具有所規劃的水凝膠之相同對 稱性之特徵。 該內部模具可由樹膠，天然疏水性材料，經特定疏水 性表面處理的玻璃或金屬所製造。塑膠可逕自使用而不必 任何表面處理。 在將溶膠注入模具之後，可適當地監測該模具已測定 其膠凝時間（典型地少於2小時）：膠凝之後，可將水注 於凝膠上。 在一固定的時間（典型地1 + 1 /2小時），添加更多水 之後，可將內模具於彼等會被“凝析”程序封阻之前抽出。 凝析係在膠凝及凝藤的適度熟化（aging)之後，於 溶膠-凝膠中觀察到的現象。其典型從凝膠熟化6小時後 即可觀察到。其本身係以從外部模具小幅回縮凝膠物質而 顯現出。其對於從外部模具回縮凝膠體而言典型地導致一 項益處，但對於任何最終的內模具會導致嚴重的壓縮問題 。凝析係以微孔中從相反方向彼此面對的矽烷醇基之交聯 -8- 200911712 模型來解釋。 結構凝膠可保留於外部，柱狀容器內並經歷熟化程序 (約48小時），中和程序（約72小時），溶劑交換程序 (10-15天），超臨界乾燥程序（24-36小時）及且製造 出氣凝膠，其載有水凝膠的相同結構，但由於凝析而有輕 微的各向同性收縮。 之後，可將氣凝膠從原容器取出並放入稠化爐中，於 該處對其在低於1400 °C的溫度施以已知的熱稠化程序使 其變爲最純矽玻璃的光纖預形體。 根據本發明的方法顯示可製出各向同性玻璃的精確形 體。其精確度大於一份每千份。 【實施方式】 實施例1 如下述製備酸溶膠： 添加500克的四乙基-正-矽酸酯至1500克0.01 N於 二次蒸餾水中的HC1。將該二相液體於磁攪拌提供的適當 機械攪拌下進行聲波處理10分鐘。在聲波處理之後，於 減壓下，於一轉動蒸發器中處理該單相液體，並從溶膠移 除等於65 0 cc體積的乙醇/水混合物。 於適當攪拌下，將2 8 5克發煙矽石AEROSIL® OX-50 添加到該溶膠。將所得懸浮液於一Ultra Turrax…T 50內 以5000 rpm句化10分鐘並以10000 rpm勻化30分鐘。 接著將勻化的液體以聲波處理予以除氣（450瓦1 0 200911712 分鐘）並以650 “g”離心30分鐘。 將所得均勻的複合溶膠其pH提升到3.7 1的値調理以 膠凝約1小時。 用該溶膠塡充模具並密封。 膠凝發生在少於1 2 0分鐘內。將蒸餾水添加到該凝膠 上。 在膠凝90分鐘之後，使用精確抽取器將內模具抽出 並添加足量水以補償抽取出的內模具之體積。將該結構凝 膠留置於外模具內，適當地密封並熟化4 8小時，接著於 模具的底部圍壁以“溶劑交換”型的圍壁替換且開始稍微通 入蒸餾水/丙酮以將圍繞凝膠的液體逐漸脫水並塡充其孔 洞。溶劑交換程序係在11天後，當圍繞凝膠的液體中之 水濃度低於〇 . 5 %時完成。 將凝膠置於一壓熱釜中，浸入丙酮內脫水。將溫度和 壓力係程式設定於2 8 0 °C和5 5巴。在壓熱循環之後，將 樣品從原容器取出成爲氣凝膠形式。將氣凝膠從原容器取 出並於已知的稠化循環中稠化爲玻璃，該循環包括去碳， 脫水和純化掉微量金屬。獲得純的矽玻璃，經完美地結構 化，沒有缺陷或變形而按照規劃到1份/千份之精確度。 -10-Jeffrey Brinker, George W. Scherer, SOL-GEL SCIENCE, pages 9 9-1 07 ) o Sol preparation can be based on the specific procedures described below: Acid-catalyzed hydrolysis of hydrazine alkoxide in water; water to decane oxide The ear ratio can be between 4 and 48. The pH of the water before the hydrolysis may be from 1.0 to 3.0: preferred conditions may be from 1.5 to 2.5. The cerium oxide present as "smoky vermiculite" in the hydrolysis may be a cerium oxide/decane oxide molar ratio of not more than 4/1. The total cerium oxide contained in the sol may not exceed 4/1 of the cerium oxide/alkoxide molar ratio. Selective extraction of the liquid phase can be accomplished via vacuum-distillation. This can be done completely or partially. Alternatively, mechanical and/or ultrasonic homogenization of the sol can be performed. Degassing of the sol can be accomplished via ultrasonic and/or decompression, and/or helium bubbles. The degassing step helps remove bubbles from the sol. If additional consistency is desired, the sol can be selectively centrifuged at 550 to 650 "g". Centrifugation is not necessary for the method of the invention. Therefore, this step can be selectively performed. However, if done, it can result in a smoother surface. The p Η -値 of the sol can be adjusted to a range of 3 · 5 to 4.1, preferably 3.6 5 to 3. 80 to initiate gelation. This adjustment can be accomplished by the addition of the free base. The sol can be filled into a mold for use in the preparation of the desired precise hydrogel for use in the 200911712 mold. The mold can be prepared as follows: Prepare a suitable cylindrical container ("tubular,"), fitted with an appropriate number of inserts (internal molds), provided by appropriate material selection or by appropriate surface treatment of the materials. The anti-adhesive properties required for the critical surface of the mold. The precise structuring of a columnar hydrogel with a series of columns parallel to the hydrogel axis can be based on a series of protrusions into the gel and in the hydrogel An elongate element that can be withdrawn prior to the occurrence of condensate. As is common in molding, and especially for sol-gel molding, the appropriate size of the internal space of the mold has the same symmetry of the planned hydrogel. The internal mold can be made of gum, natural hydrophobic material, glass or metal treated with a specific hydrophobic surface. The plastic can be used by itself without any surface treatment. After the sol is injected into the mold, the mold can be properly monitored. The gel time has been determined (typically less than 2 hours): after gelation, water can be applied to the gel at a fixed time (typically 1 + 1 /2 hours) After adding more water, the inner molds can be withdrawn before they are blocked by the "condensation" procedure. The condensation is in the sol-gel after proper aging of the gelling and vines. Observed phenomenon, which is typically observed after gel curing for 6 hours. It is itself manifested by a small retraction of the gel material from the outer mold. It is typically for retracting the gel from the outer mold. This leads to a benefit, but for any final inner mold it can cause severe compression problems. Condensation is explained by the cross-linking of stanol groups facing each other in opposite directions in the micropores-8-200911712. Can be retained in the outside, in a cylindrical container and subjected to a curing procedure (about 48 hours), a neutralization procedure (about 72 hours), a solvent exchange procedure (10-15 days), a supercritical drying procedure (24-36 hours) and An aerogel is produced which carries the same structure of the hydrogel but has a slight isotropic contraction due to condensate. Thereafter, the aerogel can be removed from the original container and placed in a thickening furnace where it is Applying it to temperatures below 1400 °C The known thermal thickening procedure turns it into the most pure glass-lined optical preform. The method according to the invention shows that an accurate shape of the isotropic glass can be produced with an accuracy greater than one part per thousand. Example 1 An acid sol was prepared as follows: 500 g of tetraethyl-n-decanoate was added to 1500 g of 0.01 N HCl in double distilled water. The two-phase liquid was subjected to suitable mechanical stirring provided by magnetic stirring. Sonication for 10 minutes. After sonication, the single phase liquid was treated in a rotary evaporator under reduced pressure and an ethanol/water mixture equal to 65 0 cc volume was removed from the sol. 8 5 g of smectite AEROSIL® OX-50 was added to the sol. The resulting suspension was spun in an Ultra Turrax...T50 at 5000 rpm for 10 minutes and homogenized at 10,000 rpm for 30 minutes. The homogenized liquid was then degassed by sonication (450 watts 1 0 200911712 minutes) and centrifuged at 650 "g" for 30 minutes. The resulting homogeneous composite sol was raised to a 3.7 1 hydrazine conditioning for gelation for about 1 hour. The mold was filled with the sol and sealed. Gelation occurs in less than 120 minutes. Distilled water was added to the gel. After gelation for 90 minutes, the inner mold was withdrawn using a precision extractor and sufficient water was added to compensate for the volume of the extracted inner mold. The structural gel was left in the outer mold, properly sealed and aged for 48 hours, then replaced with a "solvent exchange" type of wall at the bottom wall of the mold and a slight flow of distilled water/acetone was started to surround the gel. The liquid gradually dehydrates and fills its pores. The solvent exchange procedure was completed after 11 days when the water concentration in the liquid surrounding the gel was less than 0.5%. The gel was placed in an autoclave and dehydrated by immersion in acetone. Set the temperature and pressure system to 2 80 °C and 5 5 bar. After the autoclave cycle, the sample is removed from the original container into an aerogel form. The aerogel is removed from the original vessel and thickened into glass in a known thickening cycle which includes decarburization, dehydration and purification of trace metals. Obtaining pure bismuth glass, perfectly structured, without defects or deformation, is planned to 1 part per thousand accuracy. -10-