United States Patent m
Hedblom
[54] PROCESS FOR MAKING
RETROREFLECTOR SHEET
[75] Inventor: Thomas P. Hedblom, Eagan, Minn.
[73] Assignee: Minnesota Mining and
Manufacturing Company, Saint Paul,
Minn.
[21] Appl. No.: 459,532
[22] Filed: Jan. 2, 1990
Related U.S. Application Data
[62] Division of Ser. No. 204,349, Jun. 9, 1988, abandoned.
[51] Int. CI.' B05D 5/06
[52] U.S. CI 427/163; 427/198;
427/204; 427/284; 427/428
[58] Field of Search 428/172, 180, 329, 331,
428/913, 168, 142, 131, 143, 161, 166, 323, 402, 325, 173, 167; 404/9, 12, 14, 16, 93, 94;
427/204, 163, 428, 284, 198
[56] References Cited
U.S. PATENT DOCUMENTS
2,108,645 2/1938 Bryant 427/204
2,143,946 1/1939 Hunter 427/163
3,418,896 12/1968 Rideout 94/1.5
3,436,359 4/1969 Hubin et al 260/2
3,580,887 5/1971 Hubin 260/47
3,935,365 1/1976 Eigenmann 428/322
4,020,211 4/1977 Eigenmann 428/323
4,040,760 8/1977 Wyckoff 404/14
4,069,281 1/1978 Eigenmann 264/1
[ii] Patent Number: 4,988,541 [45] Date of Patent: Jan. 29, 1991
4,117,192 9/1978 Jorgensen 428/337
4,248,932 2/1981 Tung 428/325
4,381,388 4/1983 Naples 528/59
4,388,359 6/1983 Ethen 428/143
4,530,859 7/1985 Grunzinger 427/385.5
4,573,763 3/1986 Thomas 350/105
4,681,401 7/1987 Wyckoff 350/105
4,701,019 10/1987 Fitzpatrick 427/163 X
4,758,469 7/1988 Lange 428/325
FOREIGN PATENT DOCUMENTS
0162229 11/1985 European Pat. Off. .
0237315 9/1987 European Pat. Off. .
Primary Examiner—Shrive Beck
Attorney, Agent, or Firm—Donald M. Sell; Walter N.
Kirn; Douglas B. Little
[57] ABSTRACT
Process for making retroreflector sheet having protrusions which are retroreflective on selected side surfaces of the protrusions. Continuous web of polymeric base sheet having a front surface with a plurality, of protrusions, each protrusion having a top surface and at least one side surface, is provided. The web is conveyed through a nip in contact with a liquid film of bonding polymer at sufficient pressure to displace the film from the protrusion top surfaces and onto selected side surfaces, depending upon the relative speeds of the web and bonding polymer film. Retroreflective beads are applied to the liquid film which is then solidified (e.g., by temperature change) to hold the beads in place.
6 Claims, 4 Drawing Sheets
