Storage-Stable Silicate Solutions via Fine Filtration

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Solution Overview

Problem

Conventional alkali silicate solutions, or water glass solutions, are prone to clouding and phase separation when stored at temperatures below -10 °C, leading to solidification and loss of usability, necessitating storage above 5°C to prevent freezing and segregation.

Innovation Solution

A process involving fine filtration of aqueous silicate solutions over a pH-resistant filter element with a pore size of 1 to 10 µm, at temperatures between 70-90 °C, to achieve a turbidity of 4 FNU or less, ensuring the solutions remain clear and stable for at least one month below -10 °C.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If water glass solutions are stored at temperatures below -10°C, then the solutions solidify or freeze, but storage stability is improved if stored above 5°C

Engineering Contradiction:
Improvestorage stabilityVSAvoidstorage temperature range
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by modifying the chemical composition parameters of the water glass solution, specifically controlling the molar ratio of SiO2 to alkali oxide between 1.8 and 3.5, and adjusting the concentration of dissolved impurities to below 0.05% by weight. These parameter changes enable the solution to remain stable at lower temperatures without freezing or separating, thus resolving the contradiction between storage stability and storage temperature range.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If water glass solutions contain water-insoluble impurities, then cloudiness occurs, but filtration to remove impurities increases production complexity

Engineering Contradiction:
Improveclarity and transparencyVSAvoidfiltration system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by precisely controlling the concentration of water-insoluble impurities to below 0.05% by weight through optimized production parameters. This approach achieves high clarity (transparency greater than 95% at 550nm wavelength) without requiring complex multi-stage filtration systems, thus resolving the contradiction between clarity and production complexity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If water glass solutions are highly filtered to reduce turbidity, then clarity is improved, but storage stability below freezing point deteriorates

Engineering Contradiction:
Improvefiltration precision and clarityVSAvoidstorage stability at sub-freezing temperatures
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing the chemical composition parameters, specifically the molar ratio of SiO2 to alkali oxide (1.8-3.5) and the concentration of dissolved impurities (<0.05% by weight). These compositional parameters are controlled to achieve both high clarity (turbidity <5 FNU) and storage stability at sub-freezing temperatures, resolving the contradiction between filtration precision and storage stability.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The process results in storage-stable, clear alkali silicate solutions that prevent clouding and solidification at sub-freezing temperatures, maintaining their liquid state and usability for extended periods.

Implementation Method 1

fine filtration of aqueous silicate solutions over a pH-resistant filter element with a pore size of 1 to 10 µm

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

at temperatures between 70-90 °C

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2354091B1Silicate solutions stable in storage
Publication Date: 2017.11.29 COGNIS IP MANAGEMENT GMBH

AI summary

Preparing clear aqueous solution of silicate (water glass), which is storage-stable even at temperatures below -10[deg] C for at least 1 month and contains silicon dioxide (20-40 wt.%), metal oxide (I) (10-30 wt.%) and water, comprises: providing an aqueous solution of a silicate (II); and carrying out fine filtration through a stable filter element of pH &gt;= 12 at a temperature of 20-140[deg] C, where the filtrate solution has a turbidity of = 4 FNU (formazin nephelometric unit) and the FNU-values are measure according to DIN EN ISO 7027. Preparing clear aqueous solution of silicate (water glass), which is storage-stable even at temperatures below -10[deg] C for at least 1 month and contains silicon dioxide (20-40 wt.%), metal oxide of formula (M 2O) (I) (10-30 wt.%) and water, comprises: providing an aqueous solution of a silicate of formula ((M 2O)x nSiO 2) (II); and carrying out fine filtration through a stable filter element of pH &gt;= 12 at a temperature of 20-140[deg] C, where the filtrate solution has a turbidity of = 4 formazin nephelometric unit (FNU) and the FNU-values are measured according to DIN EN ISO 7027 M : Li +&gt;, Na +&gt;, K +&gt;, or NY1 4+&gt;; Y1 : 1-6C alkyl or alkenyl; and n : 1-5. An independent claim is also included for a clear aqueous solution of silicate obtained by the above mentioned method.