Abstract A retroreflective indicator providing differing day and night coloration is provided by a retroreflective material having a transparent fluorescent dye composition forwardly of the reflective surface which fluoresces light of a first wavelength band and transmits light of a second wavelength band. The retroreflective material has a front face, a body portion of synthetic plastic material and reflective formations disposed inwardly of the front face. Under the diffuse ultravoilet electromagnetic radiation characteristic of sunlight, the indicator will fluoresce a colored light representative of the first wavelength band while under the generally columnar lower frequency electromagnetic radiation characteristic of artificial nightlight provided by automobile headlight beams, the indicator will retroreflect a colored light representative of the second wavelength band. The dye composition may be dispersed substantially throughout the retroreflective material, or it may be located only in one or more layers thereof. For highway safety signs or markers, the dye composition is desirably one which fluoresces orange in sunlight and retroreflects red at night.
The retroreflective indicator of Claim 1 wherein said front face is substantially planar and said reflective formations are spaced therefrom by resin of said body portion and wherein said dye composition is disposed in said body portion.
Claim 2
Dependent Claim
23 words
The retroreflective indicator of claim 1 wherein said dye composition is located exclusively in a coating providing said front face of said material.
Claim 3
Dependent Claim
24 words
The retroreflective indicator of claim 1 wherein said dye composition includes a fluorescent dye selected from the group consisting of rhodamine and fluorescein dyes.
Claim 4
Dependent Claim
55 words
The retroreflective indicator of claim 4 wherein said dye composition is a mixture of from about 1 to 2 parts by weight of rhodamine dye and 1 part of transparent fluorescent orange dye, whereby sunlight causes said indicator to fluoresce light of orange coloration and nightlight causes said indicator to retroreflect light of red coloration.
Claim 5
Dependent Claim
40 words
The retroreflective indicator of claim 1 wherein said front face is planar and said reflective formations are spaced therefrom by said body portion and said reflective formations comprise projections on the face of said body portion opposite said front face.
Claim 6
Dependent Claim
22 words
The retroreflective indicator of claim 6 wherein said reflective formations are comprised of a multiplicity of minute, closely spaced cube corner formations.
Claim 7
Dependent Claim
19 words
The retroreflective indicator of claim 6 wherein said indicator has a reflective coating on a surface of said projections.
Claim 8
Dependent Claim
18 words
The retroreflective indicator of claim 6 wherein said dye composition is disposed in at least said body portion.
Claim 9
Dependent Claim
46 words
The retroreflective indicator of claim 6 wherein said reflective formations are comprised of a multiplicity of minute, closely spaced cube corner formations; said dye composition is disposed in at least said body portion; and said indicator has a reflective coating on a surface of said projections.