Low-Temperature Vacuum Drying for Starch Hemostatic Microspheres
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Solution Overview
Problem
Existing methods for removing organic solvents from starch hemostatic microspheres, such as high-temperature vacuum drying, result in residual solvent issues due to rapid solvent volatilization, leading to energy inefficiency and potential product degradation, and do not meet biosafety standards for implantable medical devices.
Innovation Solution
A method involving the use of a low-temperature vacuum oven with adsorbents like activated carbon or molecular sieves in dialyzing paper bags to slowly volatilize and absorb organic solvents from starch hemostatic microspheres, ensuring complete removal and reducing residual solvent levels below 0.05% as per Pharmacopoeia standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-temperature vacuum drying is used to remove organic solvent, then solvent removal speed is improved, but solvent residue remains excessive and product degradation occurs
Solution Approach 1:
The patent changes the temperature parameter from high temperature to low temperature (4-20°C) and combines it with vacuum conditions to create a new drying regime. This parameter change allows slow volatilization of solvent from the microsphere interior without causing surface structure changes that would trap solvent, thereby achieving both efficient solvent removal and low residue levels.
Solution Approach 2:
The patent introduces adsorbent materials (activated carbon, molecular sieve, or silica gel) as intermediaries to absorb the organic solvent vapor during the vacuum drying process. These adsorbents act as mediators that capture solvent molecules as they volatilize, preventing residue accumulation and enabling complete solvent removal at low temperatures.
2Manufacturing precision
If high temperature is increased to remove trapped solvent, then solvent residue is reduced, but energy consumption increases and product yellowing occurs
Solution Approach 1:
The patent fundamentally changes the temperature parameter from high to low (4-20°C range) and compensates by extending the drying time under vacuum conditions. This parameter transformation eliminates the need for high energy input while achieving complete solvent removal, directly resolving the contradiction between low residue and low energy consumption.
Solution Approach 2:
The patent employs continuous vacuum drying with adsorbents present throughout the process, maintaining a constant low-temperature environment. This continuous action at stable low temperature allows gradual but complete solvent removal without the energy-intensive high-temperature bursts that cause product degradation.
3Manufacturing precision
If freeze drying is used to remove organic solvent, then solvent residue is reduced, but energy consumption increases due to freezing requirement
Solution Approach 1:
The patent changes the temperature parameter from sub-zero (freeze drying) to slightly above freezing (4-20°C), eliminating the need for energy-intensive freezing while maintaining effective solvent removal through vacuum and adsorption mechanisms.
Solution Approach 2:
The patent extracts the freezing step from the drying process entirely, using only vacuum and adsorbent materials to achieve solvent removal. This extraction of the freezing operation eliminates the associated energy consumption while preserving the effectiveness of solvent residue reduction.
4Ease of manufacture
If vacuum drying is used to remove organic solvent, then processing simplicity is improved, but solvent residue remains excessive
Solution Approach 1:
The patent introduces adsorbent materials as intermediaries within the vacuum drying system. These adsorbents actively capture solvent vapor, enhancing the simple vacuum drying process to achieve low residue levels without adding complex equipment or procedures.
Solution Approach 2:
The patent modifies the vacuum drying parameters by lowering the temperature range (4-20°C) and extending the drying duration, transforming a simple but ineffective process into an optimized procedure that achieves both simplicity and low solvent residue.
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 reduces solvent residues to safe levels, improving biosafety and energy efficiency while maintaining product performance and water absorption properties.
Implementation Method 1
taking an adsorbent according to a mass ratio of 20%-100% of a to-be-dried product and subpackaging the adsorbent into dialyzing paper bags for sealing; and placing the trays loaded with the starch hemostatic microspheres and the dialyzing paper bags loaded with the adsorbent on separators of a low-temperature vacuum oven
Implementation Method 2
enables the solvent in the starch hemostatic microspheres to be gradually and slowly volatilized by way of low temperature and negative pressure
Implementation Method 3
placing the trays loaded with the starch hemostatic microspheres and the dialyzing paper bags loaded with the adsorbent on separators of a low-temperature vacuum oven in layers, setting the oven temperature at 0-20° C., then vacuumizing
Data Source
AI summary
The present invention provides a method for removing an organic solvent from starch hemostatic microspheres, comprising the following steps: 1. taking to-be-dried starch hemostatic microspheres and laying them flatly on drying trays with attention to laying them as uniformly and thinly as possible; 2. taking an adsorbent and subpackaging it into dialyzing paper bags for sealing; and 3. placing the trays and the dialyzing paper bags completed in the previous two steps on separators of a low-temperature vacuum oven in layers, setting the oven temperature at 0-20° C., then vacuumizing and keeping pressure for 15-48 hours. The method provided by the present invention can reduce organic solvent residue in the starch hemostatic microspheres to less than 0.05%, which meets the requirements of relevant standards for medical devices, thereby improving safety of products.