Solid-state method for treating polyamide and polyester articles
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Solution Overview
Problem
Current methods for improving the fire resistance of polyamide and polyester articles, such as adding char formers or radiation treatment, are costly, affect physical properties, and are not suitable for industrial-scale fiber or fabric production due to issues like gel formation and equipment compatibility.
Innovation Solution
A solid-state method involving a coating composition with a polyene compound and a free radical initiator applied to polyamide and polyester articles below their crystalline melting temperature, followed by heating to induce crosslinking, which reduces melting and dripping without altering the article's dimensions or geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives such as char formers, organophosphorus compounds, organohalogen compounds, hydrated minerals, red phosphorus and borates are included to improve fire resistance, then fire resistance is improved, but costs increase, additional processing steps are required, and physical and/or aesthetic properties are affected
Solution Approach 1:
The invention changes the fundamental approach from additive-based fire resistance to crosslinking-based fire resistance. By transforming the thermoplastic polyamide or polyester through crosslinking, the material achieves fire resistance without requiring additional additives, thereby avoiding increased costs, additional processing steps, and aesthetic compromises
Solution Approach 2:
The invention creates a crosslinked composite structure within the polyamide or polyester matrix. The crosslinked network formed by reacting polyene compounds with the polymer chains creates a new composite material structure that inherently provides fire resistance, eliminating the need for separate fire-retardant additives
2Reliability
If crosslinking is performed by melt-blending polyene compound and free radical initiator with thermoplastic resin, then melting and dripping can be reduced, but special grades of resins are needed and compounding costs increase
Solution Approach 1:
The invention applies the coating composition containing polyene compound and free radical initiator to the finished article before the crosslinking reaction occurs. This preliminary application eliminates the need for pre-compounding special resin grades, as the crosslinking agents are applied externally rather than being mixed into the resin during manufacturing
Solution Approach 2:
The invention extracts the crosslinking agents (polyene compound and free radical initiator) from the resin compounding step and applies them as a separate coating on the finished article. This separation eliminates the need for special resin grades and reduces compounding costs while achieving the same crosslinking effect
3Reliability
If radiation treatment is used to crosslink nylon or polyester, then melting and dripping can be reduced, but the process is not amenable to industrial fiber or fabric production
Solution Approach 1:
The invention replaces radiation treatment with thermal treatment. Instead of using ionizing radiation to initiate crosslinking, the invention uses heat to decompose the free radical initiator and trigger the crosslinking reaction. This substitution makes the process compatible with existing industrial heating equipment used in fiber and fabric production
Solution Approach 2:
The invention introduces a free radical initiator as an intermediary substance that mediates the crosslinking reaction. This initiator can be activated by conventional thermal treatment rather than requiring radiation, thereby enabling crosslinking in industrial production environments where radiation equipment is not available
4Reliability
If polymers are crosslinked using polyene compound and free radical initiators in the melt, then melting and dripping can be reduced, but significant amounts of gels are produced that clog spinnerets and cause fiber breakage
Solution Approach 1:
The invention changes the physical state parameter from melt processing to solid-state processing. By applying the coating and performing crosslinking in the solid state rather than in the melt, the process avoids gel formation that would occur during melt processing, thereby preventing spinneret clogging and fiber breakage while still achieving the desired fire resistance
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
This method effectively enhances the fire resistance of polyamide and polyester articles by reducing or eliminating melting and dripping when exposed to flames, maintaining flexibility and tactile properties, and is adaptable to existing production lines.
Implementation Method 1
heating the coated article to a temperature of at least 70° C. but below the crystalline melting temperature of the polyamide and/or polyester resin to decompose the peroxy or azo free radical initiator to form free radicals
Implementation Method 2
produce crosslinking in the aliphatic polyamide and/or polyester resin
Implementation Method 3
the coating composition comprises i) at least one polyene compound, the polyene compound having 2 to 6 vinyl groups, an equivalent weight per vinyl group of up to 500 g/equivalent, and (ii) at least one free radical initiator
Data Source
AI summary
Solid-state branching and/or crosslinking of aliphatic polyamide or polyester articles is achieved using a topical approach. A surface of the article is coated with a composition that includes a polyene and a free radical initiator. The article and applied coating are then heated to induce branching and/or crosslinking in the polyamide or polyester. This is performed below the crystalline melting temperature of the polyamide or polyester, or in the case of a fabric, below the melting temperature of the fibers in the fabric. Fabrics treated in this manner exhibit reduced or even no dripping in vertical flame tests.