Coating processes – Solid particles or fibers applied – Applying superposed diverse coatings or coating a coated base
Reexamination Certificate
1999-07-07
2001-03-06
Parker, Fred J. (Department: 1762)
Coating processes
Solid particles or fibers applied
Applying superposed diverse coatings or coating a coated base
C427S242000, C118S308000, C118S312000
Reexamination Certificate
active
06197368
ABSTRACT:
BACKGROUND OF THE INVENTION
This patent deals generally with material coating, and more specifically with an apparatus and a method for coating limited areas of a moving web with particulate matter.
One type of product in the flooring industry requires the application of particle such as different colored vinyl particles on sheet material to create a pattern. This is accomplished by first applying a pattern of adhesive to the sheet material, and then covering the adhesive with the particles which are to be attached to the sheet. This application of particles has typically involved covering the entire sheet with particles to a uniform depth, and then removing all the loose particles, i.e. those which have not adhered to the adhesive pattern. In many circumstances this can entail supplying five times the amount of particles that are actually needed, and, of course, removing 80% of the particles from the sheet material before subsequent processing.
The removal of such a large quantity of particles is a major task. It usually involves blowing high pressure, high volume air against the sheet to dislodge the loose particles and simultaneously using a large vacuum pickup to remove the particles from the sheet. These processes are both performed on a continuous, fast moving, wide width sheet, which requires air supply and vacuum pickup fixtures which span the entire width of the sheet and can handle very large volumes.
Moreover, because of the large excess used, the loose particles removed from the sheet must be recycled. This recycling can then be the source of contamination of the particles by dirt, moisture, adhesive, and other foreign matter, and such contamination can cause separation of the components in the particles. The particles used are frequently actually a mix of different colors and textures, and any contamination or separation can cause inconsistent and unacceptable final product.
It would be very advantageous to have a means for adhering particles to a moving sheet which did not involve the application of a quantity of particles which greatly exceeded the amount actually remaining on the sheet. It would be particularly beneficial if any excess of particles applied to the sheet were so small that there would be no need to recycle the excess or that contamination of the applied particles from the small amount of recycled material would be minimized.
SUMMARY OF THE INVENTION
The invention is an apparatus and a method of adhering particles to limited areas of adhesive on a moving web while using a very limited amount of particulate matter so that material costs are minimized. As in conventional systems, a limited pattern of adhesive is first applied to a wide width moving sheet, and the sheet is then coated with loose particles.
However, the present invention applies a much smaller quantity of the particulate matter onto the moving web of sheet material than has previously been used. In fact, the quantity of particles deposited upon the moving web need only be slightly greater than the quantity needed to exactly cover the adhesive coated areas. Experimentation has shown that the excess quantity used can be less than five percent.
This limited quantity of particles is made to serve the same purpose as the great excess of material in the prior art systems by the unique construction of the travel path of the web.
Although other processing makes it advantageous to have the web enter and leave the particle coating station in a horizontal plane, in the present invention the web path is built to dip down to form a significantly deep trough with vertical or substantially vertical input and output sides. The moving web then is cleared of excess material which has not adhered to the adhesive because gravity acts on the loose particles as the web moves down and then up through the trough. Furthermore, the particles falling from the web, fall to the bottom of the trough where they are distributed over the entire width by the motion of the web, and the particles stay in the trough until they stick to the adhesive applied to a following portion of the web.
The loose particles are thereby retained in the trough and immediately recycled for use, without any exposure to other contaminating materials, and the amount of particulate material used approaches the ideal quantity which would be needed to cover only the adhesive areas. The effect of the invention is essentially to move the sheet of material with adhesive upon it through a trough full of particles, except the trough is formed by the sheet itself.
To control the depth of the trough in the web, vacuum rollers are located separated from each other by enough distance to determine the span, the open space, across the trough. The speeds of the two rollers are then automatically controlled using a position sensor located under the trough to regulate the working depth of the trough.
It is sometimes advantageous to use a low pressure, low volume air source to aid in dislodging any loose material from the moving web as the the web turns the corner from the substantially vertical output path of the trough to the following horizontal path. This air source also helps to agitate the particles within the trough so that they are distributed throughout the width of the web.
A small vacuum pickup fixture on the following horizontal path can also be used to clean the last remnants of any particles not adhering to the adhesive.
The present invention thereby produces patterns of coating on sheet material without the use of a great excess of particulate matter, and uses so little particulate material that it can be practical to eliminate recycling of the excess. However, if recycling is desired, it is much easier because the quantity handled is so much less, and the problems of the recycled material affecting the new material are greatly reduced.
Furthermore, the reduction of particulate material handled, less than twenty percent of the previous amount used, can also permit higher production speeds.
REFERENCES:
patent: 2219853 (1940-10-01), Tone
patent: 4405657 (1983-09-01), Miller, Jr. et al.
patent: 4530856 (1985-07-01), Kauffman et al.
patent: 4547245 (1985-10-01), Colyer
patent: 4761306 (1988-08-01), Clark et al.
patent: 5011709 (1991-04-01), Arbogost et al.
patent: 5728216 (1998-03-01), London
Kohl Edward M.
Valenti James P.
Armstrong World Industries Inc.
Parker Fred J.
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