US2145334A - Method and means for sealing paperboard blanks - Google Patents

Description

Jan. 31, 1939. s. BERG-STEIN METHOD AND MEANS FOR SEALING PAPERBOARD BLANKS Filed s t. 10, 1936 mm m M m vs in; 5 M L W M a atente d Jan. 31, 1939 METHOD AND MEANS FOR SEALING PAPER- I BOARD BLANKS SamueiBergstein, Cincinnati, Ohio, assignor to Edna May Bergstein and Robert Morris Bergstein,as trustees Application September 10, 1936, Serial No. 100,141

4 Claims.

My invention relates to means and method for securing rapid adhesion between folded portions of blanks made of paperboard or other flexible semi-rigid material, and preferably while said 5 blanks are in motion.

It has been customary practice where the nature of the sealing operation is such as to require almost instant adhesion, to use material on which adhesive has previously been coated.

0 The pre-coated and dried adhesive portions are reactivated during the course of the subsequent sealing as by a moistening operation, and adhesion is much more rapid than in the case where a liquid or flowing adhesive is applied immediately prior to, or duringflthe course of said sealing operation.

In making stifi-setup or non-collapsible boxes, it has been the practice to fold the walls of the blanks, having cut-out corner portions, at right angles to the main body panel, and at right angles to each other also. In this operation the folded blank is placed in a machine (commonlyreferred to as a staying machine) which feeds out a strip of gummed tape which is moistened as it is fed, and bent 'into right angle form and applied to the corner of the box. The machine thereafter delivers a rapid pressure stroke over the corner of the box which causes one leg of the angle of the tape to adhere to one wall and the other leg to the adjoining wall at a right angle thereto, thereby securing the corner. If an ordinary strip of paper were to be used, to which adhesive were to be applied as the strip was fed out over the corner portion, the machine would not function because of the greater length of time required for the freshly applied adhesive to take effect, unless the machine were changed so that it paused at the point of compression for sufficient time for the excess moisture of the freshly applied adhesive to become absorbed into the fibres of the material.

It is one of the objects of my invention to effect as rapid adhesion of freshly applied adhesive as can be accomplished by reactivating pre-coated and dried adhesive. To appreciate this distinction fully it is important to consider the nature of freshly applied adhesive.

To take effect, or to grip, adhesive has to be in such condition as will cause it to be tacky or 50 sticky. In this condition, however, it is impossible to transfer the adhesive from the adhesive supply to the coating rolls, to control the uniform film on the rolls, and to roll or spread out the ad hesive evenly from the rolls on the surface of the paperboard. To make it possible, therefore,

(oi. 92-1) I for adhesive to be applied during the sealing operation, a surplus moisture content is introduced to cause the adhesive to be film forming and to flow freely and evenly. Accordingly when free flowing adhesive has been applied and the surfaces to be adhered folded into contact, pressure has been required for a suficiently long enough time to permit the surplus moisture to become absorbed or impregnated into the fibres of the paper board, before firm adhesion will result.

It is a further object of my present invention to heat the freshly applied adhesive surface sufficiently to eliminate the excess moisture present so that when the surfaces of the paperboard ply extensions, is essential in order for such portions to remain in position while subsequent operations are performed upon the blank. To accomplish this, as stated therein, I pre-coat such areas as are to be sealed with pre-coated and dried adhesive, as disclosed in my Patent No. 1,956,820. The coated areas, as described in my application Serial No. 59,423, may then be reactivated to obtain the immediate adhesion required. ,By my present invention as herein disclosed I accomplish this same objective without the preceding separate operation of. pre-coating with adhesive and predrying the coated areas, the elimination of which operation, facilitates manufacture and produces decided economies.

My co-pending application referred to, illustrates the need for quick adhesion in certain types of manufacture. In the art there are machines which apply glue and fold cartons at a high rate of speed, delivering the cartons thereafter into conveyor belts or other means in which the folded cartons are pressed while in substantially overlapping relationship to cause adhesion to take effect. In any such operations where the folded cartons can be placed in overlapping or adjoining position while pressure is applied, or in cases where the pressure application is the final step in a particular series of operations,

there is not the need for extremely rapid adhesion.

However, when the nature of a process is such that the folded cartons cannot have pressure applied to them, while in overlapping relationship, or when subsequent operations in a continuous series are required then the pressure to effect adhesion has to be applied to the blanks singly, and since the blanks are traveling at a high rate of speed and the adhesion must take effect to retain portions in position for operations which follow subsequently, the need for instantaneous adhesion is imperative.

Referring again to my co-pending application Serial 59,423 as an example, it is obvious that the double-ply extensions have a strong tendency to spring open due to the natural resistance of paperboard or other semi-rigid material to folding. It is further obvious that these double-ply extensions need to be adhered rapidly so that they will remain in position during the subsequent gluing of the corner portions as part of the same series of operations.

It is therefore a further object of my invention to provide immediate adhesion between folded portions of blanks traveling at a high rate of speed where such immediate adhesion is essential to offset the tendency of folded portions to spring open, and where the pressure to effect adhesion can only be applied for a short interval due to the need for applying pressure to the blanks individually and where folded portions have to be retained in position for subsequent operations in the same continuous series.

Referring now to the drawing: c

Figure I is a side elevation showing one embodiment of my invention.

Figure If is a more detailed end view of the delivery pressure rolls.

I have shown at I a hopper in which the paper blanks 2 to have portions thereof adhered together are stacked. The feed roller 3 feeds the blanks onto the conventional carton folding machine conveyor comprising parallel traveling conveyor chains H having upwardly projecting fingers l5 which engage the back of the blanks 2 to shove them along the side guides or conveyor support 4. A glue or adhesive receptacle 5 having a doctor roller 6 applies a film of the free flowing non-tacky adhesive, indicated at 'l, to the applying roller 8 which is of such size and may be so constructed as to apply the adhesive to predetermined areas of the blanks 2.

A supporting roller 9 cooperates with the adhesive applying roller and the blanks, coated on predetermined areas with the flowing adhesive,

feed along the conveyor to the turnover belts 9A which fold over those portions of the blanks which are to be in face to face contact with other parts of the blanks.

Before being folded over and adhered, the adhesive coated areas of the blanks are exposed, during their rapid movement, tothe heat (preferabiy dry). from electrically heated resistance elements I0. I have shown an upper heating element l0 and a lower auxiliary element IDA which may be-employed if desired. The exposure to this dry heat-is such as to make the adhesive, still in free flowing, film forming condition into tacky or sticky condition so that after the cartons pass through the fold down or turn over plates the adhesive coated parts will quickly adhere without the necessity of a prolonged interval of pressure. r

After leaving the turn over-belts 9A the blanks are fed to the pressure rollers II, HA which may be provided with flanged portions I2 which contact the area of the surface of the folded over portion between which adhesive had previously been applied. Moving from the pressure rollers H, A the blanks pass to a conveyof illustrated at l3, which may be of any desired type and which carries the blanks to the stacking tables or further processing.

The upper heating element I0 is positioned above the line of travel of the blank, so that it radiates or reflects heat upon the freshly applied free flowing adhesive portions, but does not contact them directly. If the heater element should touch the blank it would tend to wipe ofi or destroy the film of freshly applied adhesive.

If desired the auxiliary heating element IDA blank itself, because if it directly contacted the blank the heat would scorch the paperboard stock, especially since that surface is the one on which the printing is commonly done, and any direct contact with an element of high temperature would injure the ink surface.

After passing the heated elements the blanks are moved by the belt 9A which folds the portions of the blank to be adhered into overlapping relationship, and the folded blanks are thereupon conveyed through the pressure rolls H and Na which effect the adhesion.

As illustrated in Figure II the,pressure rolls may be such that the area of the .blank which they contact is confined to the particular surface of the folded over portion of the blank between which the adhesive has been applied to localize the pressure over the adhesive areas alone. These pressure means are arranged .to apply the pressure to the blanks one at a time as the blanks pass through, and are arranged to apply pressure that is not sufficient to cause distortion or injury to the folded portions which .they contact,;nor to retard the speed of movement of the blank.

The degree of heat and the length of the heating element required for the most successful results depend upon two factors; the speed at which'the blank is moving; and the thickness of the fllm of coating applied.

I flnd for instance that when the carton is moving at a rate of approximately feet per minute, heating element 36 inches in length, heated to approximately 600 degrees F. at least over 500 degrees F. and spaced approximately one-half inch above the surface of the blank, eliminates suflicient moisture from the adhesive by vaporization and renders it tacky, so that upon folding, the pressure rolls will thereafter bring about almost instantaneous adhesion. The temperature, however, can be regulated to 1200 degrees F. or more without having any-harmful effect upon the blank, if a higher speed of operation is desired, or the heating element can be lengthened to give more time for vaporization.

It is important, however, for the heating element to be placed so that it will radiate substantially dry heat directly on the coated portions, to bring about the desired change in consistency of the adhesive. If the heating element were to be placed on the side of the blank opposite to that on which the adhesive has been applied, the

amasal paper board would then retard the penetration of the heat, so that it would require a much longer time to bring about the desired degree of evapora tion, and by retarding the evaporation, it would lessen the speed of operation. An auxiliary heater, however, can be placed on the opposite side to advantage, to augment the other heating element.

The application of adhesive can be varied depending upon the type of adhesive used. For example, where an ordinary dextrine or similar adhesive is used, I find it desirable to apply the adhesive to only one of the faces which are to be brought into contact and adhered. If an adhesive of the rubber latex type is employed it is more desirable to apply the adhesive to both faces which are to be brought into contact and adhered, and in any case the heating elements are positioned so as to radiate heat on the portions of the blank that have been covered with adhesive.

I have described my process with reference to carton blanks. it may be employed for tape applied to shipping cases or for various other applications where conditions are such that an extended drying period is impossible or impractical.

I have, to make the various steps of the process clear, illustrated mechanism for carrying out my new method. To a degree, much limited as to speed, it may be carried out by a hand operation in which the adhesive may be applied to the blank with a brush, the coated areas then exposed to a relatively high dry heat and the parts to be adhered then brought into surface contact and pressed together manually.

Having thus described my invention, what I claim as new and desire to secure by- Letters Patent is:

1. The method of sealing paperboard blanks which consists in conveying the blanks, applying adhesive in film forming condition to portions of the blanks, radiating heat against the adhesively coated areas of the blanks while in continued motion to render the adhesive tacky and thereafter folding the blanks into an overlapping relation so that rapid adhesion of portions of the blank againstthe tacky surface is efiected, and compressing the blank on the overlapping portions while the blank is moved along.

2. The method of rapidly sealing paperboard blanks which consists in rapidly conveying the blanks in sequence, applying adhesive in film forming condition to portions of each blank while it is in rapid movement, radiating heat against the adhesive coated portions of the blanks while in continued motion so as to render the adhesive coating tacky, and folding portions of each blank while it is in rapid movement so that portions including the tacky surface are brought into surface contact, and compressing the surface contacting portions while the blank continues in movement, so that instantly dependable adhesion is efiected therebetween to permit subsequent manipulations of said blank in the same series of continuous operations.

3. In apparatus of the character describedmeans for continuously conveying blanks of semirigid material, means for applying adhesive in him forming condition to desired surface areas of said blanks, and means for radiating heat against the adhesive surfaces of the blanks so as to render the adhesive tacky. and means for folding the portions of the blank to be sealed into overlapping surface contacting relationship and means for applying pressure to cause rapid adhesion of the overlapping surface contacting portions, said means for applying pressure to overlapping portions so constructed and arranged as to cause adhesion while the blank is moving by a pressure which is relatively light, so that instantly dependable adhesion is efiected therebetween to permit subsequent manipulations of said blank in the same series of continuous operations.

a. In apparatus of the character described means for feeding blanks of paper board in a continuous sequence, means for applying a controlled thickness of an adhesive film to desired surface areas of the blank, means for directing dry radiant heat wlthoutdirect contact of the surface of the blank by the heating element, at least on the adhesive coated surface of the blank, means for moving said blank and means acting on the blank while moving for folding portions to be adhered into face-to-face contact, means for compressing said folded portions to efiect rapid adhesion thereof, so that instantly dependable adhesion is effected therebetween to permit subsequent manipulations of said blank in the same series of continuous operations.

5 J l BERGSTEIN.

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