Method of magnetically and/or electrostatically positioning pressure-sensitive adhesive beads and magnetically positionable pressure-sensitive adhesive beads

• US 6,127,002 A
• Filed: 01/29/1997
• Issued: 10/03/2000
• Est. Priority Date: 03/09/1993
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Enanoza, Rudyard M., Callahan, Joseph P. Jr., Groess, Michael S., Weigel, Mark D.
• Primary Examiner(s): Le, Hoa T.
• Application Number:
  US08/790,645
• Time in Patent Office: 1,343 Days
• Field of Search: 428/402, 428/403, 428/323, 427/212, 427/189, 427/195, 427/458, 427/469, 427/472, 427/474, 427/598
• US Class Current: 427/472
• CPC Class Codes: C08J 3/12 Powdering or granulating
• CPC Class Codes: C08J 3/124 Treatment for improving the free-flowing characteristics
• CPC Class Codes: C08J 3/128 Polymer particles coated by inorganic and non-macromolecular organic compounds
• CPC Class Codes: C09J 2301/204 the adhesive coating being discontinuous
• CPC Class Codes: C09J 2433/00 Presence of (meth)acrylic polymer
• CPC Class Codes: C09J 7/38 Pressure-sensitive adhesives [PSA]
• CPC Class Codes: G03G 9/093 Encapsulated toner particles
• CPC Class Codes: G03G 9/09342 Inorganic compounds
• CPC Class Codes: G03G 9/09385 Inorganic compounds
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

The present invention provides pressure-sensitive adhesive beads that comprise a tacky pressure-sensitive adhesive core and a non-tacky shell material that surrounds the area wherein the beads are capable of being positioned via magnetic means. The present invention also provides method(s) of preparing adhesive coated substrates using pressure-sensitive adhesive bead(s) that are magnetically responsive, electrostatically responsive, or both by using magnetic forces, electrostatic forces or both.

Claims

1. A method for providing, a pressure-sensitive adhesive bead coated substrate comprising the step of:

(a) providing a first substrate and a pressure-sensitive adhesive free-flowing bead(s) wherein each of the beads(s) consists essentially of a pressure-sensitive adhesive core wherein the pressure-sensitive adhesive core consists essentially of pressure-sensitive adhesive and a tack-free shell therearound, wherein the pressure-sensitive adhesive bead(s) is electrostatically chargeable, magnetically responsive, or both;

(b) positioning the bead(s) on the first substrate by a means selected from the group consisting of electrostatic force(s), magnetic force(s), both electrostatic force(s) and magnetic forces to form a tack-free coating of the bead(s) on the first substrate;

wherein upon activation by heat and/or pressure the beads forms a layer of pressure-sensitive adhesive that displays pressure-sensitive lack on the substrate.

2. The method of claim 1 which further comprises the step (c) of activating the bead(s) on the first substrate to expose the pressure-sensitive adhesive core and provide a coating of the pressure-sensitive adhesive on the first substrate.

3. The method of claim 2 wherein the pressure-sensitive adhesive coating is selected from the group consisting of discontinuous coatings and continuous coatings.

4. The method of claim 3 wherein the pressure-sensitive adhesive coating is a discontinuous pattern coating.

5. The pressure-sensitive adhesive coated substrate prepared according to the method of claim 2.

6. The method of claim 2 which further comprises a step of securing the pressure-sensitive adhesive bead(s) to the first substrate, wherein the securing step can occur simultaneously with or subsequent to positioning step (b) but must occur prior to activating step (c).

7. The method of claim 1 which further comprises a step (c) of securing the pressure-sensitive adhesive bead(s) to the first substrate, wherein the securing step can occur simultaneously with or subsequent to the positioning step (b).

8. The method of claim 1 wherein each of the pressure-sensitive adhesive bead(s) is electrostatically chargeable and wherein each of the bead(s) is attracted to and contacted with the first substrate by means of an electrostatic force(s) thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating of the pressure-sensitive adhesive bead(s) thereon.

9. The method of claim 8 wherein each of the pressure-sensitive adhesive bead(s) is electrostatically chargeable and wherein each of the pressure-sensitive adhesive bead(s) is positioned on the first substrate by attracting and contacting the bead(s) to the first substrate by means of an electrostatic force(s) generated by a method selected from the group consisting of:

(i) generating an electrostatic charge on the first substrate opposite to an electrostatic charge generated on the pressure-sensitive adhesive bead(s) and bringing the charged pressure-sensitive adhesive bead(s) close to the charged first substrate so that the bead(s) contacts the first substrate and forms a tack-free coating on the first substrate;

(ii) generating an electrical field encompassing the first substrate and applying an electrostatic charge to the pressure-sensitive adhesive bead(s) wherein the electrical field is repulsive to the charged pressure-sensitive bead(s) and wherein the electrical field is positioned such that it is capable of positioning the charged bead(s) placed therein on the first substrate and bringing the charged pressure-sensitive adhesive beads into the field so that the pressure-sensitive adhesive bead(s) contacts the first substrate and forms a tack-free coating on the first substrate; and

(iii) both (i) and (ii).

10. The method of claim 1 wherein each of the pressure sensitive adhesive bead(s) is magnetically responsive and wherein each of the bead(s) is attracted to and contacted with the first substrate by means of a magnetic force(s) thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating of the pressure-sensitive adhesive bead(s) thereon.

11. The method of claim 10 wherein attracting and contacting the pressure-sensitive adhesive bead(s) to the first substrate occur by means of a magnetic attraction force(s) wherein

(i) when the magnetically responsive pressure-sensitive adhesive bead(s) comprises a permanent magnetic particle(s) the magnetic attraction force is provided by a magnetically responsive material in the first substrate or on a side of the first substrate opposite the pressure-sensitive adhesive bead(s);

(ii) when the magnetically responsive pressure-sensitive adhesive bead(s) are free from a permanent magnetic particle(s) the magnetic attraction force is provided by a magnetic field encompassing the first substrate and bringing the pressure-sensitive adhesive beads within the magnetic field thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating thereon, and bringing the pressure-sensitive adhesive beads close to the first substrate thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating thereon; and

(iii) both (i) and (ii);

thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating thereon.

12. The method of claim 1 wherein each of the pressure-sensitive adhesive bead(s) is magnetically responsive and electrostatically chargeable and wherein each of the bead(s) is attracted to and contacted with the first substrate both by magnetic force(s) and electrostatic force(s) thereby positioning the pressure-sensitive adhesive bead(s) on the first substrate to form a tack-free coating of the pressure-sensitive adhesive bead(s) thereon.

13. The method of claim 1 which further comprises a step selected from the group consisting of:

(i) activating the pressure-sensitive adhesive bead(s) to provide a coating of pressure-sensitive adhesive on the first substrate and transferring the pressure-sensitive adhesive to a second substrate to provide a coating of pressure-sensitive adhesive on the second substrate;

(ii) transferring the pressure-sensitive adhesive bead(s) to a second substrate by a means selected from the group consisting of magnetic force(s), electrostatic force(s), and both magnetic force(s) and electrostatic force(s) and simultaneously exposing the core of the pressure-sensitive adhesive bead(s) to form a coating of pressure-sensitive adhesive on the second substrate; and

(iii) transferring the pressure-sensitive adhesive bead(s) to a second substrate by a means selected from the group consisting of magnetic force(s), electrostatic force(s), and both magnetic force(s) and electrostatic force(s) and subsequently exposing the core of the pressure-sensitive adhesive bead(s) to form a coating of pressure-sensitive adhesive on the second substrate.

14. The pressure-sensitive adhesive coated substrate prepared according to the method of claim 13.

15. A method for providing a pressure-sensitive adhesive bead coated substrate comprising the steps of:

(a) providing a first substrate and a positioning particle(s) wherein each positioning particle is both electrostatically chargeable and magnetically responsive;

comprises a magnetically responsive material and an optional electrostatically chargeable tack-free coating thereon;

(b) positioning the positioning particle(s) on a first substrate by a means selected from the group consisting of electrostatic force(s), magnetic force(s), and both electrostatic forces and magnetic forces to form a coating of the positioning particles on the substrate;

(c) providing a free-flown pressure-sensitive adhesive bead(s) wherein each of the bead(s) consists essentially of a pressure sensitive adhesive core wherein the pressure sensitive adhesive core consists essentially of pressure-sensitive adhesive and a tack-free shell therearound, wherein the pressure-sensitive adhesive bead(s) is electrostatically chargeable, magnetically responsive, or both; and

(d) positioning the pressure-sensitive adhesive bead on the positioning particle coated substrate by attracting the positioning particle(s) and the pressure-sensitive adhesive bead(s) by a means selected from the group consisting of magnetic force(s), electrostatic force(s), both magnetic forces and electrostatic force(s); and

wherein upon activation by heat and/or pressure the beads forms a layer of pressure-sensitive adhesive that displays pressure-sensitive tack on the substrate.