Fibers made from soluble polymers
A fiber can be made having a structure with an axial core and a coating layer. The fiber can have a polymer core and one or two layers surrounding the core. The fine fiber can be made from a polymer material and a resinous aldehyde composition such that the general structure of the fiber has a polymer core surrounded by at least a layer of the resinous aldehyde composition.
1. A fine fiber comprising a nonreactive polymer and a self-crosslinked resinous aldehyde composition within the fiber wherein the resinous aldehyde composition is present in an amount of greater than 20 parts by weight per 100 parts by weight of the polymer, and further wherein the fine fiber has an average diameter of no greater than 5 microns.
2. The fine fiber of claim 1 wherein the nonreactive polymer and self-crosslinked resinous aldehyde composition forms a uniform mixture in a semi-interpenetrating network morphology.
3. The fine fiber of claim 1 comprising three phases, wherein the core phase comprises the polymer, the coating phase comprises the resinous aldehyde composition, and a transition phase comprises a mixture of the polymer and the resinous aldehyde composition.
4. The fine fiber of claim 1 which is prepared from a resinous aldehyde composition comprising reactive alkoxy groups and a nonreactive polymer.
5. The fine fiber of claim 1 wherein the resinous aldehyde composition comprises a resinous formaldehyde composition.
6. The fine fiber of claim 5 wherein the resinous formaldehyde composition comprises a resinous melamine-formaldehyde composition.
7. The fine fiber of claim 1 wherein the resinous aldehyde composition comprises a melamine-aldehyde composition; and wherein the aldehyde comprises formaldehyde, acetaldehyde, butyraldehyde, isobutyraldehyde, or mixtures thereof.
8. The fine fiber of claim 1 wherein the resinous aldehyde composition comprises a condensation product of urea and an aldehyde, a condensation product of phenol and an aldehyde, a condensation product of melamine and an aldehyde, or a mixture thereof.
9. The fine fiber of claim 1 wherein the resinous aldehyde composition comprises a condensation product of benzoguanamine and an aldehyde, a condensation product of glycoluril and an aldehyde, or a mixture thereof.
10. A fine fiber comprising a core phase and a coating phase; wherein the core phase comprises nonreactive polymer and the coating phase comprises a self-crosslinked resinous melamine-aldehyde composition; wherein the fine fiber is prepared from a resinous melamine-aldehyde composition in an amount of greater than 20 parts by weight per 100 parts by weight of the nonreactive polymer, and further wherein the fine fiber has an average diameter of no greater than 5 microns.
11. A filter media comprising a filtration substrate and a layer comprising a plurality of fine fibers of claim 1 disposed on the substrate.
12. The filter media of claim 11 wherein the fine fiber layer has a thickness of 0.05μ to 30μ.
13. The filter media of claim 11 wherein the filtration substrate is a non-woven substrate.
14. The filter media of claim 11 wherein the fine fiber layer is an electrospun layer and the filtration substrate comprises a cellulosic or synthetic nonwoven.
15. The filter media of claim 11 wherein the filtration substrate comprises a polyester nonwoven, a polyolefin nonwoven, or a blended nonwoven thereof.
16. The filter media of claim 11 wherein the filtration substrate comprises polypropylene nonwoven.
17. The filter media of claim 11 wherein the filtration substrate comprises a spunbonded or melt-blown support.
18. A filter element comprising a filter media of claim 11 .