Degradable Polyester Filter Tow with Compatible Plasticizer
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Solution Overview
Problem
Conventional cigarette filter elements made of cellulose acetate are slow to degrade in the environment due to their compacted and bonded structure, which hinders biodegradation, and existing solutions face challenges in using degradable polymers like polylactic acid due to incompatibility with conventional plasticizers.
Innovation Solution
A fibrous tow filter material using degradable polyester filaments, such as polylactic acid, combined with a plasticizer composition that has a Relative Energy Difference of 0.8 or less with the polyester, allowing for inter-fiber bonding and enhanced degradation, utilizing solvents like dimethylisosorbide and triacetin to achieve the necessary cohesion and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cellulose acetate filter elements are tightly-compacted and highly crimped with fiber bonding, then filter cohesiveness and rigidity are improved, but biodegradation rate deteriorates
Solution Approach 1:
The filter element is divided into multiple segments with slits extending through the tow, creating separated sections that can degrade independently while maintaining overall structural integrity during use
Solution Approach 2:
The patent modifies the chemical composition by incorporating water-soluble cellulose materials and photoactive pigments that change the filter's responsiveness to environmental conditions, enabling accelerated degradation when exposed to moisture or light after disposal
2Duration of action of stationary object
If degradable polyester filaments like polylactic acid are used, then biodegradation rate is improved, but compatibility with conventional plasticizers deteriorates
Solution Approach 1:
The patent specifies precise Relative Energy Difference parameters (0.8 or less) for plasticizer-polyester combinations, identifying specific solvent compositions like dimethylisosorbide and triacetin that are chemically compatible with degradable polyesters, thereby enabling both degradability and manufacturability
Solution Approach 2:
The filter employs a composite structure combining degradable polyester filaments with specifically selected plasticizer compositions, creating a multi-material system where each component is chosen for its compatibility and functional contribution to both degradation and structural properties
3Duration of action of stationary object
If filter elements are unwrapped and fibers spread apart, then biodegradation rate is improved, but filter structural integrity deteriorates
Solution Approach 1:
Slits are incorporated into the filter element to divide it into segments, allowing the fibers within each segment to spread and degrade while the segmented structure itself maintains enough integrity to function as a filter during use
Solution Approach 2:
Water-soluble cellulose materials act as intermediary substances that facilitate fiber separation and degradation without completely compromising the filter's structural integrity during its service life
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 solution significantly accelerates the biodegradation of cigarette filter elements, with a weight loss of at least 20% after 60 days in soil or 30% after 15 days in a composter, while maintaining the necessary cohesiveness and rigidity for a functional filter.
Implementation Method 1
a plasticizer composition applied thereto, the plasticizer composition and the degradable polyester having a Relative Energy Difference calculated using Hansen Solubility Parameters of 0.8 or less
Implementation Method 2
The discarded portion of the cigarette rod is primarily composed of the filter element, which typically consists of tightly-compacted and highly crimped cellulose acetate fibers bonded at their contact points... biodegradation of the filter can take several years
Data Source
Figure 1
Figure 2
AI summary
A filter material adapted for use as a filter element (26) of a smoking article is provided, the filter material being in the form of a fibrous tow that includes a plurality of filaments of a degradable polyester and a plasticizer composition applied thereto, the plasticizer composition and the degradable polyester having a Relative Energy Difference calculated using Hansen Solubility Parameters of less than about 1.3. Exemplary degradable polyesters include polyglycolic acid, polylactic acid, polyhydroxyalkanoates, polycaprolactone, polybutylene succinate adipate and copolymers or blends thereof. Exemplary plasticizer compositions include one or more of dimethylisosorbide, propylene carbonate, methylbenzyl alcohol, glycerol carbonate acetate, glycerol carbonate ethyl ether, and mixtures thereof, optionally in combination with triacetin. Filter elements and smoking articles, such as cigarettes, that contain the filter material are also provided.