公开(公告)号：JPH11171559A

公开(公告)日：1999-06-29

申请号：JP27077998

申请日：1998-09-25

Applicant: LUCENT TECHNOLOGIES INC

Inventor： CHEN YOU-LUNG ,  PATEL SANJAY ,  VALDES JORGE LUIS

IPC: C03B8/02 ,  C03B20/00 ,  C03B37/012 ,  C03C1/00

Abstract: PROBLEM TO BE SOLVED: To provide a new sol-gel process using only very small amounts of a stabilizer such as TMAH(tetramethylammonium hydroxide) and a gelation agent such as methyl formate. SOLUTION: In this production, by using a single stabilization/gelation agent which is capable of initially, stabilizing or assisting in stabilizing a liquid dispersion and then, being converted in situ into a gelation agent for inducing gelation of the liquid dispersion, the respective required amounts of a conventional stabilizer and a conventional gelation agent, both of which are required for bringing about both the stabilization effect and the gelation effect, can be reduced. Accordingly, this sol-gel process is superior to a conventional solgel process. The initial stabilization effect of the stabilization/gelation agent enables a remarkable reduction in required amount of an undesirable stabilizer such as TMAH. Further, since the stabilization/gelation agent itself is converted into a substance capable of contributing to gelation, only a very small amount of a conventional gelation agent such as methyl formate is required.

公开(公告)号：DE69801082T2

公开(公告)日：2002-03-21

申请号：DE69801082

申请日：1998-09-08

Applicant: LUCENT TECHNOLOGIES INC

Inventor： CHEN YOU-LUNG ,  VALDES JORGE LUIS ,  PATEL SANJAY

IPC: C03B8/02 ,  C03B20/00 ,  C03B37/012 ,  C03C1/00 ,  C01B33/148

Abstract: The invention provides an alternative to conventional sol-gel methods that utilize undesirably high amounts of a stabilizing agent such as TMAH and a gelling agent such as methyl formate. The method involves the steps of (a) providing a colloidal silica dispersion containing a stabilizing/gelling agent, where only a portion of the molecules of the agent ionize, and (b) subsequently adding to the silica dispersion a pH-reducing additive. The stabilizing/gelling agent has a dual function. The agent, e.g., an amine, initially acts as a stabilizer in the silica dispersion in that a portion of its molecules ionize, while an appreciable amount of the agent remains nonionized. The agent later transforms in situ to a gelling agent upon addition of a pH-reducing additive. Specifically, as the pH-reducing additive lowers the pH to values at or around the pKa of the stabilizing/gelling agent, more of the agent's molecules are ionized, these cations contributing to charge neutralization, and thus gellation, of the colloidal silica particles.

公开(公告)号：DE69801082D1

公开(公告)日：2001-08-16

申请号：DE69801082

申请日：1998-09-08

Applicant: LUCENT TECHNOLOGIES INC

Inventor： CHEN YOU-LUNG ,  VALDES JORGE LUIS ,  PATEL SANJAY

IPC: C03B8/02 ,  C03B20/00 ,  C03B37/012 ,  C03C1/00 ,  C01B33/148

Abstract: The invention provides an alternative to conventional sol-gel methods that utilize undesirably high amounts of a stabilizing agent such as TMAH and a gelling agent such as methyl formate. The method involves the steps of (a) providing a colloidal silica dispersion containing a stabilizing/gelling agent, where only a portion of the molecules of the agent ionize, and (b) subsequently adding to the silica dispersion a pH-reducing additive. The stabilizing/gelling agent has a dual function. The agent, e.g., an amine, initially acts as a stabilizer in the silica dispersion in that a portion of its molecules ionize, while an appreciable amount of the agent remains nonionized. The agent later transforms in situ to a gelling agent upon addition of a pH-reducing additive. Specifically, as the pH-reducing additive lowers the pH to values at or around the pKa of the stabilizing/gelling agent, more of the agent's molecules are ionized, these cations contributing to charge neutralization, and thus gellation, of the colloidal silica particles.