Dual layer heat shrink tubing
The present disclosure provides a dual layer heat shrink tube having: an inner polymeric layer with a thickness t 1 and an outer diameter D 1 ; and an outer, expanded polymeric layer with a thickness t 2 ′ and an outer diameter D 2 ′ obtained by expanding a polymer tube from D 2 to D 2 ′ and t 2 to t 2 ′ at a selected temperature so that D 2 ′−2( t 2 ′)>D 1 , wherein a ring cut from a cross-section of the dual layer heat shrink tube, slit into a rectangle and gripped at cut ends by tension grips within a DMA, and subjected to a temperature sweep of 3° C./min at a frequency of 1 Hz from the onset of a melting endotherm of the inner polymeric layer to that of the outer, expanded polymeric layer is greater than 1° C. and less than 12° C. The disclosure further provides associated methods for preparing and using such tubes, as well as to products comprising such tubes.
1. A dual layer heat shrink tube comprising:
an inner polymeric layer consisting essentially of PFA, FEP, EFEP, or PVDF and, optionally, one or more pigments, dyes, or fillers, with a thickness t 1 and an outer diameter D 1 ; and
an outer, expanded polymeric layer consisting essentially of PTFE, FEP, PFA, PEEK, or PVDF with a thickness t 2 ′ and an outer diameter D 2 ′ obtained by expanding a polymer tube from D 2 to D 2 ′ and t 2 to t 2 ′ at a selected temperature so that D 2 ′−2(t 2 ′)>D 1 ,
wherein a ring cut from a cross-section of the dual layer heat shrink tube, slit into a rectangle and gripped at cut ends by tension grips within a DMA, and subjected to a temperature sweep of 3° C./min at a frequency of 1 Hz from the onset of a melting endotherm of the inner polymeric layer (as determined by DSC) up to the onset of a melting endotherm of the outer, expanded polymeric layer (as determined by DSC) has an area under a tan δ curve that is greater than 1° C. and less than 12° C.
2. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of a fluoropolymer selected from PTFE, FEP, PFA, and PVDF.
3. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of PTFE and the inner polymeric layer consists essentially of PFA.
4. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of PTFE and the inner polymeric layer consists essentially of FEP.
5. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of PFA and the inner polymeric layer consists essentially of FEP.
6. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of PEEK and the inner polymeric layer consists essentially of FEP.
7. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of FEP and the inner polymeric layer consists essentially of EFEP.
8. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer consists essentially of FEP and the inner polymeric layer consists essentially of PVDF.
9. The dual layer heat shrink tube of claim 1 , wherein the outer, expanded polymeric layer is removable after being heat shrunk.
10. The dual layer heat shrink tube of claim 1 , wherein the inner polymeric layer comprises a filler.
11. The dual layer heat shrink tube of claim 1 , wherein the inner polymeric layer is not an expanded polymeric layer.
12. The dual layer heat shrink tube of claim 1 , wherein the inner polymeric layer is not an oriented polymeric layer.