Drying Microfibrillated Cellulose Preventing Hornification
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Solution Overview
Problem
Conventional drying techniques for microfibrillated cellulose, such as spray drying and freeze drying, result in hornification and loss of dispersibility and rheological properties, making it difficult to maintain the original gel-like properties of microfibrillated cellulose, and are costly and challenging to scale up industrially.
Innovation Solution
A method involving increasing the solid content of an aqueous microfibrillated cellulose suspension to 15-30 wt% and drying it through simultaneous heating and mixing, including grinding, to prevent hornification and maintain re-dispersibility, using techniques like centrifugation, pressing, and vacuum drying to control temperature and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional spray drying or freeze drying is used to dry microfibrillated cellulose, then the drying process can be completed, but hornification occurs and dispersibility and rheological properties are lost
Solution Approach 1:
The patent changes the drying parameters by using low temperature (20-40°C) and high relative humidity (70-95%) conditions, which prevents hornification while maintaining drying efficiency. This parameter optimization allows the microfibrillated cellulose to retain its original dispersibility and rheological properties
Solution Approach 2:
The patent applies preliminary action by conducting the drying process in the presence of surfactants or dispersants before hornification can occur. These agents are introduced in advance to prevent fibril aggregation and maintain separation during drying, thereby preserving the nanofibrillated structure
2Reliability
If freeze drying is used to preserve original properties, then re-dispersability is improved, but operating and investment costs are high and scaling up is difficult
Solution Approach 1:
The patent employs inexpensive surfactants and dispersants that can be easily applied and removed, replacing the need for expensive freeze drying equipment. These chemical agents provide the necessary protection during drying at low cost and enable simple scale-up to industrial production
Solution Approach 2:
The patent replaces the mechanical freeze drying system with a chemical approach using surfactants and controlled humidity drying. This substitution eliminates the need for complex freeze drying machinery while achieving similar or better results in terms of re-dispersability and scalability
3Productivity
If spray drying is used to easily scale up, then productivity is improved, but hornification of fibrils occurs and operation costs are high
Solution Approach 1:
The patent introduces surfactants and dispersants as intermediary substances that mediate between the microfibrillated cellulose and the drying environment. These intermediaries prevent direct contact and aggregation of fibrils during drying, thereby preventing hornification while allowing scalable spray drying processes
4Manufacturing precision
If microfibrillated cellulose is dried to obtain dry form for dosing, then dosing accuracy is improved, but dispersibility and hydration properties are lost
Solution Approach 1:
The patent extracts or removes water from the microfibrillated cellulose suspension to obtain a dry or substantially dry form suitable for accurate dosing. The surfactants remain as a protective layer on the dried fibrils, enabling both accurate dosing and subsequent re-dispersibility when needed
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 method effectively prevents hornification, maintains the original properties of microfibrillated cellulose, and allows for energy-efficient production of a dry, re-dispersible product suitable for various applications, including composites and pharmaceutical uses.
Implementation Method 1
drying said microfibrillated cellulose suspension in a mixing operation, wherein water is removed from said suspension by evaporation
Implementation Method 2
drying said microfibrillated cellulose suspension in a mixing operation
Data Source
AI summary
A method for drying nanofibrillated polysaccharide to obtain a substantially dry nanofibrillated polysaccharide product, comprising the following steps: (i) providing an aqueous suspension of nanofibrillated polysaccharide; (ii) increasing the solid content of said suspension, thereby forming a high solid content microfibrillated cellulose suspension; and (iii) drying said high solid content microfibrillated cellulose suspension, through a simultaneous heating and mixing operation.