US3548781A - Hot melt adhesive applicator - Google Patents

Description

I United States Patent [1113,548,781

[72] Inventor Helmut O- Hornung 2,835,221 5/1958 Slayter et al. 118/202 A1toona,Pa. 3,030,915 4/1962 Shannon 118/202 211 App]. No. 739,079 3,124,476 3/1964 Park et a1..... 118/63X [22] Filed June 21,1968 3,412,707 11/1968 West 118/5 [45] Patented Dec. 22,1970 [73] Assignee F. 1.. Smlthe Machine Company, Inc. Zgggigfi'gg 32115 McIntosh Duncansvl11e,Pa. a corporation of New York [54] WE APPLICATOR ABSTRACT: A hot melt adhesive applicator for application to a paper line, such as spaced or overlapped envelopes, 1n WhlCh [52] US. Cl. 11815, the t f to i resiliently covered and is located in a 118/2 chamber having a controlled temperature environment. The [51] Int B059 1/00, applicator is provided with a contiguous melt box and B059 11/00 chamber. The melt box is provided with an opening in a wall of Search u I 18/5, thereof through which a part of the dispensing roller projects 212, 216, Digest)? 117/1193 thereby essentially filling the opening. The dispensing roller picks up the adhesive and passes it to the transfer roller. The [56] References Cited chamber is provided with a hot air environment in order to UNITED STATES PATENTS control the temperature of the transfer roller, the latter having 2,693,429 1 H1954 Radtke et a] 1 18/202X a resilient covering.

IfATENTED(15!:221970 3548.781

INVENTOR Nsvs IHELMUT 0. HORNUIVG HOT MELT ADHESIVE APPLICATOR BACKGROUND OF THE INVENTION A hot melt applicator is known as a heated applicator roller or a direct applicator roller which is in the form of a smooth, hard-surfaced cylinder that is etched to a particular depth and design. Thus, when the cylinder is rotated in the hot melt adhesive, it is coated uniformly. Thereafter, a scraper or doctor blade scrapes off the surface of the cylinder leaving only that adhesive material which is in the etched area. The rotating cylinder then is adapted to apply the adhesive to the paper material. The use of resilient material eliminates high precision machining operations necessary for manufacturing metallic rolls.

In addition, the use of resilient material provides a more even distribution of adhesives to the paper line.

SUMMARY OF THE INVENTION It is an object of the invention to provide a standard hardsurfaced cylinder rotating against another cylinder provided with a resilient covering. The hard-surfaced cylinder is adapted for rotation in molten adhesive in place of the expensive gravure cylinder.

The molten adhesive is transferred evenly by the resilient material on the other cylinder to the paper line. However, the transfer roll with the resilient covering is not heated internally as is the case with the standard hard-surfaced gravure cylinder since the high temperatures required in heating the transfer roll would destroy the resilient covering.

In order to overcome the heating problem with respect to the transfer roll, a controlled temperature environment has been evolved to keep the resilient applicator at the proper temperature without damaging the resilient coating thereof.

Another object of the present invention is to provide a resilient covered transfer roll which can be applied to either individual or overlapped blanks on a web form.'

BRIEF DESCRIPTION OF THE DRAWING Further objects and advantages of this invention will become apparent from the following description which will be best understood by reference to the appended drawing in which:

FIG. 1 is a diagrammatic sectional view of the hot melt adhesive applicator constructed in accordance with the teachings of the present invention; and

FIG. 2 is an alternative embodiment of the hot melt adhesive applicator as disclosed in FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, the hot melt applicator constructed in accordance with the present invention comprises a melt box in which a quantity of adhesive 12 is located therein. The temperature in the melt box 10 is thermostatically controlled by thermostat 14. Mounted partially within the melt box 10 is a rotatable hard surface roller 16. The part of the roller 16 that is not located within the melt box 10 projects through opening 18. The roller 16 when rotating picks up an excess of molten adhesive which is scraped off by an adjustable scraper 20 adjacent to the opening 18 in the melt box 10. Unused adhesive 12 is transferredback to the melt box 10 through the clearance 22 formed between the box 10 and the roller 16.

In order to overcome the problem of heat transfer to the transfer roll 24 having resilient coverings 26 on selected areas thereof, a controlled temperature environment has been achieved. In this regard, the surface temperature of the applicator wheel 24 is maintained at a slightly higher temperature than the temperature of the melt box 10. The heated environment in the chamber 28 is controlled in a thermostatihousin l5 and the roller 24.

The eed rollers 38 and 40 engage the paper line 42 and propel the web either in the form of individual spaced blanks or overlapped blanks B in the direction of the arrow C. The blanks are engaged by the resilient surfaces 26 of the transfer roll 24 in the proper timed relationship in order to place the adhesive at the proper location on each of the blanks B.

FIG. 2 shows a hot melt adhesive applicator such as shown in FIG. 1, however, the transfer roll 42 therein is provided with an uninterrupted resilient covering 44 instead of the discontinuous resilient covering 26 shown in FIG. 1. The structure of FIG. 2 is especially adapted for the application of adhesive to individual sheets in an overlap condition.

I claim:

1. A hot melt adhesive applicator for a line of paper comprising a melt box provided with an opening in a wall thereof, said melt box having an adhesive therein, a dispensing roller at least partly in said melt box in contact with said adhesive, means for controlling and maintaining the prescribed temperature in said melt box, a chamber operatively connected to said melt box, part of said dispensing roller projecting through the opening in said melt box into said chamber and to essentially fill said opening, a transfer roller in said chamber having a coating of resilient material, said transfer roller taking adhesive from said dispensing roller on said resilient material and transferring the same to said line of paper, and a constantly controlled hot air environment in said chamber to control the temperature of the transfer roller therein.

2. A hot melt adhesive applicator as claimed in claim I I wherein said transfer roll has discontinuous resilient surfaces.

3. A hot melt adhesive applicator as claimed in claim 1 wherein said transfer roll has a continuous, outer, resilient surface.

4. A hot melt adhesive applicator fora line of paper comprising a melt box provided with an opening in a wall thereof, said melt box having an adhesive therein, a dispensing roller at least partly in said melt box in contact with said adhesive, a chamber adjacent and operatively connected to said melt box, means in said chamber for maintaining a surface temperature therein which is higher than the surface, temperature in said melt'box, part of said dispensing roller projecting through the opening in said melt box into said chamber and essentially filling said opening, and a transfer roller in said chamber hav ing a coating of resilient material, said transfer roller taking adhesive from said dispensing roller on said resilient material and transferring the same to said line of paper.

5. A hot melt adhesive applicator fora line of paper comprising a melt box provided with an opening therein, said melt box having an adhesive therein, a dispensing roller at least partly in said melt box and in contact with said adhesive, means for controlling and maintaining the prescribed temperature in said melt box, a chamber operatively connected to said melt box, part of said dispensing roller projecting through the opening in said melt box into said chamber, a transfer roller in said chamber having a coating of resilient material, said transfer roller taking adhesive from said dispensing roller on said resilient material and transferring the same to said line of paper, and means in said chamber for controlling the temperature therein being a blower having a plurality of blades and a resistance element.

6. A hot melt adhesive applicator as claimed in claim 5 wherein said chamber is contiguous to said melt box, and said chamber is provided with an outlet adjacent to said transfer roller whereby hot air propelled by said blower is ejected through said outlet.

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