Microfibrous Suede Fabric Process Without Organic Solvents
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Solution Overview
Problem
Existing processes for producing non-woven microfibrous suede-like fabrics face challenges in achieving high durability, resistance to yellowing, and low environmental impact, while also avoiding the use of hazardous substances and maintaining good hand and dyeing resistance.
Innovation Solution
A process involving needle punching of bicomponent 'island-in-the-sea' fibers, followed by hot impregnation with polyvinyl alcohol (PVA) or water, subsequent cold impregnation with polyurethane (PU), and coagulation, without the use of organic solvents, to produce a microfibrous fabric with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvents (DMF, trichloroethylene) are used for impregnation and dissolution, then the fabric achieves good hand and resistance, but environmental impact increases and hazardous substances are used
Solution Approach 1:
The patent changes the solvent parameter from organic (DMF, trichloroethylene) to water, eliminating hazardous substances while maintaining fabric quality. This is achieved by adjusting the chemical composition parameters of the polymeric components to ensure they are water-soluble or water-dispersible, thereby resolving the contradiction between fabric performance and environmental safety
Solution Approach 2:
The patent uses water as a temporary solvent that is easily removed through drying, replacing persistent organic solvents. The water-soluble PVA and water-dispersible PU are applied in aqueous form and then eliminated through evaporation, leaving no harmful residues in the final fabric product
2Ease of manufacture
If PVA with lower degree of saponification is used, then impregnation is easier, but dyeing resistance decreases and yellowing resistance worsens
Solution Approach 1:
The patent optimizes the degree of saponification of PVA to at least 94%, which balances the competing requirements of impregnation ease and final fabric performance. This specific parameter range ensures sufficient solubility for impregnation while maintaining the chemical stability needed for resistance to yellowing and dyeing, resolving the contradiction between manufacturing ease and product reliability
3Reliability
If boric acid is used to complex PVA, then fabric resistance improves, but health hazards increase and process variability increases due to partial solubility
Solution Approach 1:
The patent removes boric acid from the process entirely by using water-soluble PVA and water-dispersible PU that can be applied directly in aqueous solutions. The resins themselves provide sufficient binding and resistance properties without requiring boric acid complexation, thereby eliminating health hazards and the solubility variability issues associated with PVA-boric acid complexes
Solution Approach 2:
The patent uses water as an intermediary solvent to carry PVA and PU through the impregnation process, replacing the PVA-boric acid complex as the binding medium. This water-based approach provides consistent solubility and eliminates the need for hazardous crosslinking agents, resolving both health and process variability concerns
4Length of stationary object
If fabric thickness is reduced, then more applications become possible, but durability may decrease
Solution Approach 1:
The patent creates a composite structure combining water-soluble PVA and water-dispersible PU in a microfibrous non-woven fabric. This composite material system provides enhanced strength and durability even at reduced thickness, as the synergistic interaction between the two polymers creates a robust matrix that maintains mechanical integrity while enabling thin-fabric applications
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 a fabric with excellent resistance to yellowing, high durability, and improved dyeing resistance, while being environmentally friendly and cost-effective, with the ability to produce thin materials and reduce thickness further.
Implementation Method 1
preparing a felt via needle punching of a bicomponent fibre
Implementation Method 2
hot impregnation of said felt with an aqueous solution of polyvinyl alcohol (PVA)
Implementation Method 3
fixing the PU to the microfibrous intermediate product by means of coagulation
Data Source
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AI summary
The present invention refers to a process for the preparation of a non-woven microfibrous suede-like synthetic fabric that does not require the use of organic solvents and that makes it possible to obtain a finished product offering a good hand, excellent resistance to yellowing and high durability. It comprises needle-punching a felt of sea/island fibres, (a) impregnation with hot aqueous solution of PVOH having a degree of saponification of at least 94% or (b) impregnation with hot water followed by impregnation with cold PUR, removing the sea component, impregnating with PUR, coagulating the PUR, removing the PVOH, grinding the surface, dyeing and splitting in two sheets.