Retro-reflective thread, method of manufacturing same and a textile

Patent metadata

Field	Value
Publication number	US-10427367-B1
Application number	US-201615051966-A
Country	US
Kind code	B1
Filing date	Feb 24, 2016
Priority date	Feb 24, 2016
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

Disclosed is a retro-reflective thread 100 including an internal section 10 ; a plurality of fibers 12 , each fiber comprising a respective longitudinal axis and a respective surface and each fiber comprising a first material that is at least partially optically transmissive, and wherein said plurality of fibers are configured with their respective longitudinal axes substantially co-linearly aligned with one another and said plurality of fibers are interconnected in series around said internal section and wherein a first part 12 b of said respective surface of each of said plurality of fibers faces into said internal section; and a reflective material 14 provided on said first part of said respective surface of each of said plurality of fibers.

First claim

What is claimed is:

1. A method of manufacturing a retro-reflective thread, the method comprising the steps of:
forming a thread by:
a. forming a core comprising a first surface; and

forming a plurality of fibers, each said fiber comprising a respective longitudinal axis and a respective surface and wherein said plurality of fibers are configured with their respective longitudinal axes substantially co-linearly aligned with one another and said plurality of fibers are interconnected in series around said core, each said fiber comprising a first material that is at least partially optically transmissive;
b. removing said core to form a void, said core being removed such that a first part of said surface of each of said plurality of fibers faces into said void; and
c. delivering a reflective material in a fluid state into said void in a quantity sufficient to coat said first part of said surface of each of said plurality of fibers and solidifying said reflective material coating said first part of said surface.

2. The method of claim 1 , wherein forming said plurality of fibers comprises forming said plurality of fibers in a spaced series and forming a plurality of connecting elements, each connecting element being formed between and interconnecting a respective pair of said plurality of fibers.

3. The method of claim 1 , wherein forming said plurality of fibers comprises forming each of said plurality of fibers to be touching a directly preceding one of said plurality of fibers and to be touching a directly subsequent one of said plurality of fibers.

4. The method of claim 1 , wherein said core comprises a second material that is soluble in a first solvent and said first material is insoluble in said first solvent, and wherein removing said core comprises dissolving said core in said first solvent.

5. The method of claim 1 , wherein said core comprises a water soluble polymer and each of said plurality of fibers comprises a non-water soluble polymer.

6. The method of claim 1 , wherein in step c. further comprises removing an amount of said reflective material not coating said first part of said surface of each of said plurality of fibers.

7. The method of claim 1 , wherein in step c. further comprises substantially filling said void with said reflective material in said fluid state and enabling all said reflective material to solidify.

8. The method of claim 1 , further comprising step d. comprising substantially filling said void with a polymer in a fluid state and enabling said polymer in said fluid state to solidify.

9. The method of claim 1 , wherein forming said core and forming said plurality of fibers comprises simultaneously extruding said core and said plurality of fibers.

10. The method of claim 1 , wherein said reflective material is one of a reflective metal, a reflective alloy and a polymer doped with reflective particles.

11. The method of claim 1 , wherein in step a. each of said plurality of fibers is formed having one of a substantially circular cross-section and a substantially elliptical cross-section.

12. The method of claim 1 , wherein said first part of said surface of each of said plurality of fibers is substantially circular in cross section and has radius, R core , and each said fiber has a radius, R surface , and wherein said plurality of fibers, N, is inversely proportional to the ratio of R surface to R core .

13. The method of claim 1 , wherein said first part of said surface of each of said plurality of fibers is substantially circular in cross section and has radius, R core , and each said fiber has a radius, R surface , and wherein each of said plurality of fibers is arranged just touching a directly preceding one of said plurality of fibers and just touching a directly subsequent one of said plurality of fibers, and said plurality of fibers, N, is given by

N
=

π

arcsin
⁡

(

R
surface

R
core

)

14. The method of claim 1 , wherein the maximum radius, R surface , of each of said plurality of fibers is given by

R
surface

=

R
core

⁢

sin
⁡

(

π
N

)

,

where N is said plurality of fibers.

15. The method of claim 1 , wherein said first material has a refractive index in the range 1.5 to 2.2.

16. The method of claim 1 , wherein said first material has a refractive index in the range 1.85 to 2.05.

17. The method of claim 1 , wherein said first material has a refractive index of between 1.85 and 2.05.

18. The method of claim 1 , wherein said first material has a refractive index of substantially 1.9.

19. The method of claim 1 , wherein said first material is substantially optically transmissive at visible wavelengths of light.

20. The method of claim 1 , wherein said first material is substantially optically transmissive at infra-red wavelengths of light and is substantially absorptive at visible wavelengths of light.

21. The method of claim 1 , wherein said core is formed in step a. having one of a circular cross-section and a non-circular cross-section.

Assignees

• Us Gov Sec Army

Inventors

• Ghebrebrhan Michael
• Hoke Landa

Classifications

• B29L2031/731

  Filamentary material, i.e. comprised of a single element, e.g. filaments, strands, threads, fibres (cables B29L2031/707) · CPC title

• B29D11/0074

  Production of other optical elements not provided for in B29D11/00009- B29D11/0073 · CPC title

• D06Q1/04

  by metallising (transfer of metal particles D06Q1/12) · CPC title

• D06M11/83

  with metals; with metal-generating compounds, e.g. metal carbonyls; Reduction of metal compounds on textiles · CPC title

• D01F11/00

  Chemical after-treatment of artificial filaments or the like during manufacture · CPC title