Process for depositing dry powder particles onto a substrate and attaching the particles to the substrate

Patent metadata

Field	Value
Publication number	US-10414186-B2
Application number	US-201616063472-A
Country	US
Kind code	B2
Filing date	Dec 12, 2016
Priority date	Dec 18, 2015
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

Methods for using a hollow, rotating stencil roll to deposit flowable dry powder particles onto a moving substrate and to attach the particles to the substrate.

First claim

What is claimed is:

1. A method for attaching flowable dry powder particles to a moving substrate, the method comprising:
dispersing flowable dry powder particles onto a major radially inner surface of a hollow, rotating stencil roll,
contacting a first major surface of a moving substrate with a major radially outer surface of the hollow, rotating stencil roll;
imparting thermal energy to the moving substrate at least while the first major surface of the moving substrate is in contact with the major radially outer surface of the hollow, rotating stencil roll, so that a first portion of the moving substrate, which first portion includes the first major surface, is heated to a temperature sufficient to soften the first portion of the moving substrate;
as the moving substrate rotates with the stencil roll, allowing at least some flowable dry powder particles to pass through at least some apertures in the stencil roll so as to contact the softened first major surface of the moving substrate and to partially embed in the first portion of the moving substrate so as to become attached thereto; and, allowing at least some flowable dry powder particles that have not become attached to the first portion of the moving substrate to tumble freely along the major radially inner surface of the stencil roll as the stencil roll rotates;
and,
separating the first major surface of the moving substrate from the major outer surface of the hollow, rotating stencil roll so as to produce a substrate comprising an array of flowable dry powder particles attached to the first portion thereof.

2. The method of claim 1 wherein the substrate is a multilayer substrate with a first layer that provides the first portion and first major surface of the substrate, and is comprised of a material that is softenable at a first softening temperature; and, with a second layer that is a support layer and that is not softenable at a temperature of less than 30 degrees C. above the first softening temperature of the first layer.

3. The method of claim 1 wherein the substrate is a monolithic substrate and wherein the method is performed so that when thermal energy is imparted to the moving substrate so that a first portion of the substrate, which first portion includes the first major surface of the substrate, is heated to a temperature sufficient to soften the material of the first portion of the substrate, a second portion of the substrate remains at least substantially unsoftened.

4. The method of claim 1 wherein the imparting of thermal energy to the moving substrate so that the first portion of the substrate is heated to a temperature sufficient to soften the first portion of the substrate, is performed by an infrared heating unit.

5. The method of claim 1 wherein the imparting of thermal energy to the moving substrate includes a preheat step in which the moving substrate is heated before the first major surface of the moving substrate is in contact with the major radially outer surface of the hollow, rotating stencil roll.

6. The method of claim 1 where the particles are partially embedded in the first portion of the substrate to an embedment percentage of from about 20% to about 60%.

7. The method of claim 1 wherein the flowable dry powder particles that tumble freely along the major radially inner surface of the stencil roll as the stencil roll rotates, form a rolling bank as the stencil roll rotates.

8. The method of claim 1 wherein the stencil roll further comprises at least one particle-contacting member that at least closely abuts the major radially inner surface of the rotating stencil roll but is not attached to the stencil roll so as to rotate congruently therewith, which member assists in dislodging flowable dry powder particles from the major radially inner surface of the stencil roll so that the particles can tumble freely along the major radially inner surface of the stencil roll.

9. The method of claim 8 wherein the particle-contacting member is in the form of at least one brush that comprises bristles that contact the major radially inner surface of the stencil roll, wherein the brush is mounted at an angular distance, along the direction of rotation of the stencil roll, of from about 30 degrees to about 100 degrees from a gravitationally lowest point of the stencil roll.

10. The method of claim 1 wherein the major radially outer surface of the stencil roll is a release surface.

11. The method of claim 1 wherein at least selected apertures of the stencil roll are configured so that flowable dry powder particles can pass through each selected aperture only one at a time, so that for each complete rotation of the stencil roll, only one flowable dry particle is passed through each selected aperture to be attached to the substrate.

12. The method of claim 1 wherein at least selected apertures of the stencil roll are configured so that multiple dry powder particles can pass through each selected aperture at a time, so that for each complete rotation of the stencil roll, multiple flowable dry powder particles are passed through each selected aperture to be attached to the substrate.

13. The method of claim 1 wherein the stencil roll comprises a stencil shell that comprises a plurality of apertures extending therethrough, and wherein the apertures exhibit a radial length, on average, of from about 20 μm to about 4 mm.

14. The method of claim 13 wherein the stencil shell is a cylindrical screen-printing screen with a hardened screen-printing emulsion patterned thereon, wherein the hardened emulsion comprises interior edges that define areas of the screen-printing screen that do not have hardened emulsion thereon, which areas of the screen-printing screen that do not have hardened emulsion thereon provide apertures of the stencil shell.

15. The method of claim 1 wherein the apparatus comprises a backing roll that abuts the stencil roll to form a nip, and wherein the first major surface of the substrate is separated from the major radially outer surface of the stencil roll, at a location that is angularly within plus or minus 40 degrees from the nip.

16. The method of claim 1 wherein the dispensing of the flowable dry powder particles onto the radially inner major surface of the stencil roll comprises gravity-dropping the flowable dry powder particles onto the radially inner major surface of the stencil roll.

17. The method of claim 16 wherein the gravity-dropping comprises allowing additional flowable dry powder particles to gravity-drop onto a loose mass of flowable dry powder particles located at least in a lowermost angular portion of the interior of the rotating stencil roll.

18. The method of claim 1 wherein the flowable dry powder particles comprise partially reflective glass beads.

19. The method of claim 1 wherein the flowable dry powder particles comprise activated carbon particles.

20. The method of claim 1 wherein less than about 10% by number of the flowable dry powder particles are attached to areas of the first major surface of the substrate that had come into contact with the radially outer major surface of the stencil roll.

Assignees

• 3M Innovative Properties Co

Inventors

• Vandre Eric A
• Stay Matthew S
• Smith Matthew R D
• Gilman Ann M
• Dodds Shawn C
• Dable Jon E
• Brutinel Evan D

Classifications

• B41M1/12 Primary

  Stencil printing; Silk-screen printing · CPC title

• B41M1/22

  Metallic printing; Printing with powdered inks · CPC title

• B41M1/125 Primary

  using a field of force, e.g. an electrostatic field, or an electric current · CPC title

• B41M1/26

  Printing on other surfaces than ordinary paper (B41M1/40 takes precedence) · CPC title

• B41N1/247

  Meshes, gauzes, woven or similar screen materials; Preparation thereof, e.g. by plasma treatment · CPC title