US2204664A - Method of making paper articles - Google Patents

Description

June 18, 1940. K. CLARK METHOD OF MAKING PAPER ARTICLES Original Filed April 11. 1934 INVENTOR ATTORNEY Patented June 18, 1940 UNITED STATES PATENT OFFICE METHOD] OF MAKING PAPER ARTICLES Kempton Clark, Little Compton, R. I., assignor to American. Seal- Kap Corporation of Delaware, Wilmington, Delaware I ,Del.,. a corporation of Original application Apiil l l, 1934, Serial No.

720,066. Di'videdand this applicationDecemy ber 28, 1937, Serial No. 182,033

p 1 Claim.

This invention relates to a method of making ,paperarticles and more particularly to those intended to contact with foods. One example of such an article is a milk bottle cap or closure,

and while it should be understood that the invention:is not to be restricted in its broadest aspects to closures for: milk bottles, the invention will be hereinafter more particularly described wit relation to-such use. I I

. This application is a division of my applica tionSer. No. 720,066,. filed April 11, 1934 for Paper article. I

In many cases it is desirable to use colors in connection with such articles, as forthe purpose of producing ornamental effects or for dis-.- tinguishing between grades or types of milk. For

example, one color may be usedin connection readily distinguished. Likewise in some localities the use of colored lettering is employed on the bottles themselves and it then may be desirable to employ sealing caps presenting the same color as the letters on the bottles.

. In most cases, however, it is undesirable that the food products themselves should come into contactwith colored paper material, not only because with the use of certain coloring materials there might actually be some chance of. contamination of the food product, or some undesired effect on the coloring material I itself through contact with such product, but also becausethe public has been generally educated up tothe point where there is a real demand for closure members which present an appearance of extreme purity and cleanliness where the food products are brought into contact therewith.

I According to this invention, therefore, the caps are formed of a paper material which presents exteriorly the desired color but which on the opposite face presents material entirely free from coloring material. In order to accomplish this purpose the. paper used is preferably of multiply stock, one face portion only being colored, the

other face portion being free from coloring mat ter.

The use of multi-ply paper permits the application of coloring matter to the stock of one or more of the. plies before the plies are brought "together to form the completed paper, the several layers of materialbeing'brought together while they are in a wet and more or less plastic condition so that they interfelt with each other in a manner well known in manufacture of multi-ply I paper.

It is, of course, important that the manufac-- turing processes in making the caps be socarried outthat the facing of the paper stock whichcontains the color forms the outside face of the cap, and in order to insure this and to insure ready handling of the paper in its various stages of formation, certain methods of handling thepaper have bee-n found highlydesirable more fully appear. I

as will later I For amore complete understanding of. this incaps are madeand certain subsequent treatments I to which these blanks may be subjected before forming them into caps.

Figure 4 is a fragmentary perspective showing a blank as in the condition subsequent to treatment b y the apparatus of Figure 3. I

Figure 5 is adiagrammatic representation of a manner of supporting and feeding the several blanks to the cap-forming dies.

Figure 6 is a perspective partly broken away of one form of completed cap.

Referring first to Figure l, at l, 2 and 3 are shown the several vats containing the paper stock from which the several plies of the paper are to bemade. As shown, the vat I contains a stock which is colored by any suitable means, such, for example, as a pigment or a dye of the desired color. A more detailed discussion of the desirable characteristics of such coloring will be givenlater. The vats 2 and 3 are shown as containing uncoloredstock which should be of such a nature that it contains no substances such as would be deleterious to the food product with which it is to. contact. While three separate vats are illustrated by which a three-ply paper may be made, it should, -:of course, be understood that any desired number might be used. Further reference pressed thereagainst by suitable couch rolls 8, .9

and Ill. The blanket then passes about a suction roll or other similar device as at H for the purpose of more completely removing the water from, the stock and from which it passes over suitable supporting rolls. l2, between the press rolls l3:

and M, the blanket returning around the roll l4 while the sheeted paper passes to the drier in,

dicated conventionally at 15 from which itmay be fed off to any suitable device, for example,

a winder shown at I6.

The paper thus produced is illustrated in Figure 2 and comprises a colored lamination 20 and two uncolored laminations 2| and 22, Paper for use as milk bottlecaps and which is subjected to a severe molding action when being died to form should be of a somewhat open and porous nature so that it can be readily impregnated by rriatB- rials such as water and waterproofing or' 'resistant materials such as wax, which not only facilitate thernolding operation, but also render the caps when completed substantially waterproof.

It has been found in practice that it is most advantageous to have substantially only onethird of the total paper by weight or thickness colored. If there is less than this, the uncolored portion of the paper will tend to show through on the colored side, particularly where the paper is subjected to substantial forming operations when being molded, which tends to produce undesirable surface abrasions or local thinning free from color, If the, amount of colored stock is more than one half of the total, there is a tendency for the color to show through the uncolored side, particularly after waxing, to such an extent thatit will give the appearance of being present on that side of the article which is brought into direct contact with the milk, which also is undesirable. While the most satisfactory proportions of thickness of colored and uncolored stock is generally about ,1 to 2, this mayvary from, according to conditions of, say, about 1 to 3 to 1 to l, with the thickness of paper most suitable for molding into milk bottle caps.

As the paper is subjected to moistening, as well as the'wax treatment, in order to facilitate the molding operation, it is, of course, necessary that the color should be thoroughly set so as to pre vent bleeding of coloring matter into the uncolored portion or plies of the paper. Furthermore, as the articles when in use may become moistened by contact with the milk, any such bleeding or flow of the color might havea very deleterious effect and even might escape into the milk. The sealed milk bottlesare also subjected to other conditions of great severity with relation to coloring material in the caps, such, for example, as the icing operations which not only subject the caps to the action of cold water, but also to abrasive actions of the ice. Two classes of coloring material are the most satisfactory, these being pigments, and dyes of the type. known as direct dyes. Such dyes have a great afiinity for sulphite pulp such as is most suitable as a basic stock material for bottle caps, and they may be thoroughly set by the use of a hot salt solution.

Most dyes used in papermaking are set by alum,

but for paper which is to be impregnated with waxes or the like, the use of alum is sometimes disadvantageous, and unless a size is employed with alum, the retention of the color and the setting efiect byithe. alum is less eflicient. Where pigments are employed the use of a small amount of size helps to retain the pigment, but of course this detracts to some extent, at least, from the open and porous character of the paper and the "ease with which itmay be impregnated with the wax. With the use of direct dyes the salt which is used in setting them is easily washed out and has no bad'eifect on the paper stock and such dyes do not bleed into the wax as is the case withmany dyes commonly used in papermaking. Not only would such bleeding into the wax be disadvantageous in, that the color; might spread through the uncolored portions of the paper, but it might also contaminate the wax in the treating'tankthrough which the blanks pass and thus pass into subsequently treated blanks in those portions where color is not desired.

. In order to make a paper satisfactory for the molding operations, it is also advantageous to hold the degreeof saturating qualities and the tensile. strengths in directions longitudinally and crosswise of the paper within proper limits, these limits depending somewhat on the severity of the stresses produced by the molding operations, which are in turn dependent on the amount of deformation which the paper must undergo during such molding Thepaper thus prepared may then be subjected to treatment both to condition it for resistance to moisture and for the molding opera- ,tion to which it must be subjected in forming it into the caps. In Figure 3 is-shown diagrammatically anapparatus by which the paper is cut into blanks and impregnated with the desired waterproofing agents and otherwise conditioned for the-molding operation. As shown in this figure,--the;paper is led from a suitable supply source, hereinwshown. as the roll 30, through a punching mechanism indicated at 3|, by which blanks 25.01? the proper size aresevered from the sheet material, the waste portions of the paper being then removed as by being wound up into a 'roll 32 while the blanks 25 themselves are passed, as by the conveyor 33 to the impregnating tank 34. Sometime previous to being incorporated'with the water-proofing materials, it

- is preferable to subject either the blanks or the paper to a moistening action which swells the fibres of the paper and softens it so that it may be added to the treating water, if desired. The

blanks. in moist condition are shown, therefore, as being .fed inbetween confronting faces of ' reticulated feeding belts 35 and 36, the reticulations. permitting the water resistant material, suchv as a suitable wax or mixture of waxes in molten condition, to find ready access to opposite faces, of. the blanks. By causing the treating waxes to be maintained at a temperature somewhat above the boiling point of the moisture in the blanks, a portion of this moisture is vaporized and passes off from the blanks sothat as the blanks pass out from the wax tank with a surface coating of molten wax thereon; subsequent chilling ofthe blanks and condensation of the moisture vapor therein, acts to drawin the ,wax

from the blank surfacespresultingin a more thorough penetration of. the waxiinto the interstices and perhaps even: into the fibres of the paper. Theblanks after removal from the tank are permitted to cool and are then deposited in any suitable receptacles. It is thenpreferable to permit the moistened and saturated blanks to stand for a time in order that they may become;

conditioned or tempered and uniformly sufficiently plastic to be most suitable for the molding operations. For this purpose they may be kept in closed containers for, a few hours.

When properly conditioned they may be sub jected to the forming action between suitable dies as has been illustrated diagrammatically in Figure 5. As therein shown the blanks 25 are,

fedlout one at a time from the lower end of a suitable containing tube 4|] by means of a feed plate, such as 4|, which maybe reciprocated across the open lower end of the tube 4|] by any suitable means, so that they may be delivered one at a time to any suitable conveying means,

as at 42, and brought in between the upper and above the usual disk-receiving ledge therein, an

outwardly turned portion 48 covering over the pouring lip of the bottle, and a skirt 49 depending therefrom to engage the outer face of the pouring lip. The entire outer face of the cap presents the desired color while the entire inner face of the cap is of uncolored stock so that no colored stock is presented where it may contact with the milk in the bottle.

In connection with the feeding of the cap blanks from the container 40 so that they may be delivered as desired to the forming dies, it is important that the blanks should be so positioned relative to the feed plate 4| that at each reciprocation it may engage the lowest blank in the stack and remove it from the tube 40. There is a tendency in making blanks of a suitable thickness for formation into bottle caps for the blanks to dish through unequal rates of drying at opposite face portions thereof, or from other causes. Should such a slightly dished blank be presented with its convex face downward, this may cause difliculty in the feeding action by reason of the feeding edge of the plate 4! passing in under the edge of the blank, and it is important, therefore, that the blanks be presented sothat if they are not exactly fiat, their convexed faces are positioned upwardly. This will result in the outer edge of the blanks where the feed plate enters being engaged by the feeding edge of this plate so that the blanks will be removed successively from the bottom of the stack as desired. It will be noted, however, that the blanks must be presented to the forming dies right side up so that the colored face shall always appear on the outside rather, than the inside of the cap, and it is therefore necessary, to insure proper feeding with such a mechanism, that provision be made so that the convex face of the blank shall always bear the same relation to the colored and uncolored faces. There are various ways of insuring this. For example, the

characters of the paperstock in the stock'vats of the paper machine may be so controlled that the colored stock when sheeted and processed shall be more extended in the conditioned blank than. the stock forming the remainder of the I blank; This may be accomplished either through controlling the relative shrinkages of the two types of stock in the formation and drying of the paper, .or through controlling the relative amounts to which these surface portions will be expanded by the saturating process, or through combinations of both. For example, this may be done by controlling the relative freeness or slowness of the colored and uncolored stock, as, by controlling the amount of beating to which the stock is subjected before it is employed in papermaking. Thus, if the uncolored stock is slower than the colored stock, the uncolored side of the paper tends to take up less Water than the colored side. It expands less and therefore is on the concave side of the paper. Another factor which may be of use is the rate of cooling of the blanks on the two sides after they leave the saturating tank. With the uncolored side up, the colored side being against the face of the conveyor, the uncolored side cools the more rapidly and assists in cupping the blanks in the proper direction. This is illustrated in Figure 3 Where thedirection of cupping is changed as the blanks cool on the conveyor 3|. further advantage from maintaining the uncolored stock slower than the colored stock in that theguncolored side of the paper is less porous and therefore takes up less of the wax from the saturating tank and is therefore less transparent, so that the probability of the color from the colored side showing through is reduced.

. It is also important, particularly from the standpoint of color and uniformity of color, that the completed blanks be quite accurate in thickness as the thickness of the blanks determines the action of the parts of the die thereon which are relatively spaced by predetermined dimensions. The amount of moisture and the amount of saturating material, as also the amount of the paper stock, is thus of importance since all these factors determine the thickness of the blank when it reaches the forming dies. If the blank is not thick enough the color of theblank itself will show up in the completed article. Where the blank is highly compressed during the forming operations, the color effect is deepened and where the compression is produced through a wiping action of the diesthereon, a glossy deeply colored finish is produced, different from that of the colored face of the blank before being molded. By suitable disposition of the excess stock which must be compressed in the molding operation ornamental variations in shadingmay be produced. For example, areas of, deepercolor 50 separated by areas of lighter color in pattern formation as indicated in Figure 6 may be produced, producing a pleasing ornamental effect.

From the foregoing description of a preferred construction and a method by which it may be made, it should be understood by those skilled in the art that various changes and modifications might be made without departing from the spirit or scope of this invention as defined by the appended claim.

I claim:

The method of making a severely molded paper article which comprises forming a laminated paper blank with the laminations at opposite.

surfaces of the blank having different absorption There is also a the blank, passing the same through a wax bath at a temperature and for a period of time to vaporize the moisture and drawa predetermined amount of the wax into the fibers thereof, a1- lowing the same to set for a time torende'r the blank plastic for molding while the difierent absorption characteristics of the laminations causes the blank to cup with the lamination having the higher absorption characteristics on the convex side, and forming the cupped blank into an article having a substantially fiat, disc-like characteristics for moisture and wax, moistening central portion and an inverted, generally U- shaped' marginal portion forming an upstanding marginal rim with the convex side of the blank forming the convex side of said marginal rim,

the amount of waxlabsorbed being sufiicient to permit said forming operation to take place Without cracking or abrading the paper to an extent that would cause either lamination to show through the other lamination and be visible from the opposite surface of the article.

KEMPTON CLARK.

Images