Conformable magnetic articles for use with traffic bearing surfaces methods of making same systems including same and methods of use

• US 6,468,678 B1
• Filed: 10/22/1997
• Issued: 10/22/2002
• Est. Priority Date: 11/17/1994
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Dahlin, Thomas J., Keech, Robert L., Newell, Richard G., Fayling, Richard E., Lacey, Claud M., Jacobs, Gregory F., Gonzalez, Bernard A., Hopstock, David M.
• Primary Examiner(s): Watkins, III, William P.
• Application Number:
  US08/955,579
• Time in Patent Office: 1,826 Days
• Field of Search: 428/40, 428/343, 428/900, 428/143, 428/149, 428/156, 428/325, 428/692, 428/694.R, 428/694.B, 428/694.BC, 428/694.BU, 252/62.54, 264/108, 264/DIG.58, 180/167, 180/168, 340/901, 340/905, 404/6, 404/9, 404/16, 404/14, 701/205
• US Class Current: 428/800
• CPC Class Codes: E01F 9/30 Arrangements interacting with transmitters or receivers otherwise than by visible means, e.g. using radar reflectors or radio transmitters E01F11/00 takes precedence
• CPC Class Codes: E01F 9/512 Preformed road surface markings, e.g. of sheet material; Methods of applying preformed markings
• CPC Class Codes: Y10S 264/58 Processes of forming magnets
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/24372 Particulate matter
• CPC Class Codes: Y10T 428/24421 Silicon containing
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/28 Web or sheet containing structurally defined element or component and having an adhesive outermost layer

Abstract

Magnetic, conformable articles for use with traffic bearing surfaces are disclosed which comprise an organic binder having magnetic particles distributed therein. The articles may be employed in intelligent vehicle guidance systems, and in systems to guide other mobile objects such as farm animals, pets, or visually impaired pedestrians. Methods of making the articles and methods of using the systems to control and/or guide a mobile object using the magnetic field generated from the articles are also described.

Claims

1. An article comprising a conformable magnetic layer comprising:

(a) an organic binder; and

(b) at least 30 volume percent magnetic particles distributed in said organic binder, the magnetic particles capable of being remanantly magnetized to produce a magnetic field sufficient to be sensed by a sensor, said comformable layer being sufficiently conformable to demonstrate at least 25% inelastic deformation under the inelestic deformation test.

2. The article in accordance with claim 1 wherein said organic binder comprises organic materials selected from the group consisting of non-crosslinked elastomeric precursors, thermoplastic polymers, and combinations thereof.

3. The article in accordance with claim 2 wherein the non-crosslinked elastomer precursor is selected from the group consisting of acrylonitrile-butadiene polymers, neoprene, polyacrylates, natural rubber and styrene-butadiene polymers.

4. The article in accordance with claim 1 wherein the magnetic particles comprise up to about 95 weight percent of said article.

5. The article in accordance with claim 1 wherein the magnetic particles comprise up to about 75 volume percent of said article.

6. The article in accordance with claim 1 wherein the magnetic particles comprise up to about 60 volume percent of said article.

7. The article of claim 1 wherein the magnetic particles are oriented.

8. The article in accordance with claim 1 wherein the magnetic particles are capable of being remanently magnetized to produce a magnetic field of at least 10 milligauss at a distance ranging from about 15 to about 30 centimeters from a center of the article.

9. The article in accordance with claim 1 wherein the magnetic particles have a major axis length ranging from about 0.01 micrometer to about 1000 micrometers.

10. The article in accordance with claim 1 wherein the magnetic particles have a saturation magnetization ranging from about 10 to about 250 emu/g.

11. The article in accordance with claim 1 wherein the magnetic particles have a coercivity ranging from about 100 to about 20,000 oersteds.

12. Article in accordance with claim 1 wherein the magnetic particles have a coercivity ranging from about 200 to about 5000 oersteds.

13. Article in accordance with claim 1 wherein said article is a sheet and further comprises a vulcanized layer.

14. Article in accordance with claim 1 wherein said article is a sheet and has adhered thereto a layer of adhesive.

15. The article in accordance with claim 1 wherein said article is a magnetic tape having first and second major surfaces and comprises:

a) a conformable magnetic layer having;

(i) an organic binder; and

(ii) at least 30 volume percent magnetic particles distributed in said organic binder, the magnetic particles capable of being remanently magnetized to produce a magnetic flux of at least 10 milligauss at a distance ranging from about 15 to about 30 centimeters from a center of the tape; and

b) an adhesive layer adhered to one major surface of said article.

16. The article in accordance with claim 15 wherein said article further comprises a vulcanized layer adhered to the second major surface.

17. The article in accordance with claim 15 wherein the adhesive layer comprises adhesives selected from the group consisting of pressure-sensitive adhesives, hot-melt thermoplastic adhesives, heat-sensitive adhesives, and contact bond adhesives.

18. The article in accordance with claim 15 wherein the second major surface of the magnetic layer has an elastic support layer adhered thereto, the elastic support layer serving to bind a plurality of retroreflective elements thereto.

19. The article in accordance with claim 15 wherein the tape has a fibrous web material embedded therein.

20. The article in accordance with claim 15 wherein the conformable magnetic layer has:

a) a front surface;

b) a plurality of integral protuberances projecting from the front surface, there being a plurality of such protuberances across the width and down the length of the article, each of the protuberances having a top surface and at least one side surface connecting the top surface to the front surface of the conformability layer;

c) a first discontinuous layer of bead bond covering a selected set of surfaces of the protrusions; and

d) a first plurality of particles partially embedded in the first layer of bead bond and partially protruding from the first layer of bead bond.

21. The article in accordance with claim 20 wherein the particles are selected from the group consisting of anti-skid particles and retroreflective particles.

22. The article in accordance with claim 15 wherein the magnetic layer comprises of barium ferrite particles perpendicularly oriented in a nitrile rubber binder with a remnant magnetization (Br) of about 2500 gauss.

23. A magnetic mobile object control and/or guidance system comprising:

(a) at least one conformable, magnetic article of claim 1;

(b) a mobile object comprising at least one sensor which senses the magnetic field produced by the magnetic article; and

(c) an indicator.

24. The system in accordance with claim 23 wherein the sensor is a magneto-resistive sensor.

28. The article according to claim 1 wherein said magnetic particles are platelet shaped.

25. A method of making a conformable magnetic material comprising the steps of:

a) combining an organic binder precursor with at least 30 volume percent magnetic particles, the magnetic particles capable of being remanently magnetized to produce a magnetic field sufficient to be sensed by a sensor; and

b) exposing the binder precursor to conditions sufficient to form a conformable organic binder having the magnetic particles dispersed therein;

said conformable layer being sufficiently conformable to demonstrate at least 25% inelastic deformation under the inelastic deformation test.

26. The method in accordance with claim 25 further comprising:

imposing conditions sufficient to orient the magnetic particles in said material in a preferred direction.

27. The method in accordance with claim 26 wherein the orientation step comprises physically deforming the material.