Alkali Silica Sol for Paper Drainage and Retention
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Solution Overview
Problem
Current silica sols used in papermaking lack improved drainage and retention performance, especially in producing paper and board from cellulosic suspensions with low conductivity and cationic demand, leading to inefficiencies in steam consumption and additive dosage.
Innovation Solution
A silica sol with a pH above 10, a molar ratio of SiO2: M2O (where M is an alkali metal) from 6:1 to 16:1, and a concentration of soluble silica above 3000 mg/l, produced through a process involving acidification, alkalization, and optional aluminum modification, which enhances particle formation and microgel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silica sols are used in papermaking, then drainage and retention performance is achieved, but improved performance in low conductivity suspensions is not obtained
Solution Approach 1:
The patent modifies the chemical parameters of the silica sol by controlling pH to be above 10 and adjusting the molar ratio of SiO2:M2O to 6:1 to 16:1. These parameter changes enable the silica sol to perform effectively in low conductivity suspensions while maintaining drainage and retention performance.
Solution Approach 2:
The invention creates a composite silica sol system combining inorganic silica particles with controlled organic polymer content. This composite structure enhances the sol's adaptability to low conductivity suspensions while preserving its drainage and retention functions.
2Reliability
If higher additive dosages are used to improve drainage and retention, then performance increases, but steam consumption and production costs increase
Solution Approach 1:
By optimizing the pH to above 10 and molar ratio to 6:1 to 16:1, the silica sol achieves enhanced performance at lower dosages, reducing the total amount of additive needed and consequently reducing steam consumption associated with heating and processing.
Solution Approach 2:
The invention creates a highly efficient silica sol formulation that replicates the performance of higher dosage conventional formulations but with reduced additive content, achieving the same drainage and retention effects with lower resource consumption.
3Reliability
If higher additive dosages are used to improve drainage and retention, then performance increases, but production costs increase
Solution Approach 1:
The optimized pH and molar ratio parameters enable the silica sol to achieve effective drainage and retention performance at lower dosages, reducing the quantity of additive required and thereby lowering production costs.
Solution Approach 2:
The invention develops a silica sol formulation that copies the effective performance of high-dosage conventional systems but with reduced additive content, achieving cost reduction while maintaining functional performance.
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 silica sol improves drainage and retention in papermaking, reduces steam consumption, allows for lower additive dosages, and enhances paper and board quality, stability, and production efficiency.
Implementation Method 1
the silica sol of the invention... is suitable for use as a flocculating agent
Implementation Method 2
increase adsorption of fine particles onto the cellulosic fibers
Implementation Method 3
particle formation and microgel formation
Implementation Method 4
microgel formation
Data Source
AI summary
The present invention relates to a silica sol having a pH above about 10, molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, concentration of soluble silica above about 3000 mg SiO2/l, and S-value of from about 18 to about 40%. The invention further relates to a process for producing a silica sol which comprises acidifying an aqueous alkali metal silicate solution to a pH of from 1 to 4 to form an acid sol, alkalizing the acid sol by addition of aqueous alkali metal silicate solution to obtain an intermediate sol and interrupt the addition of aqueous alkali metal silicate solution when the intermediate sol has reached a pH of from about 5 to about 8, stirring the intermediate sol for a time period of from about 10 to about 6000 seconds without addition of aqueous alkali metal silicate solution, alkalizing the intermediate sol by addition of aqueous alkali metal silicate solution to obtain a silica sol having a pH above about 10 and molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, and optionally adding an aluminum compound to the acid sol, intermediate sol or silica sol. The invention further relates to a silica sol obtainable by the process of the invention. The invention further relates to the use of the silica sol as a flocculating agent, in water purification and in producing paper and board. The invention further relates to a process for producing paper and board which comprises: (i) providing an aqueous suspension comprising cellulosic fibers; (ii) adding to the suspension one or more drainage and retention aids comprising the silica sol; and (iii) dewatering the obtained suspension to provide a sheet or web of paper or board.