US 3603218 A
Description (OCR text may contain errors)
United States Patent  METHOD OF MAKING PAPER CONTAINER HAVING A HIGH GLOSS EXTERIOR FINISH AND WAX COATED INTERIOR AND BOTTOM SURFACES 5 Claims, 13 Drawing Figs.
 US. Cl 93/36 PC, 93/34, 93/36 MM, 93/36.5, 93/39 C, 93/55.1, 93/59 MT  Field of Search 93/36 MM, 36 PC, 36.5, 34, 39 C, 39.3, 59 MT, 55.1, 84 FF  References Cited UNITED STATES PATENTS 1,175,406 3/1916 Bohlman 93/36 1,417,707 5/1922 2,074,348 3/1937 2,110,750 3/1938 2,141,556 12/1938 2,311,675 2/1943 Magill 93/55.1 2,368,273 1/1945 Tibbetts 93/36 2,435,806 2/1948 Tibbetts 93/36 3,015,596 1/1962 Couch 93/36 3,085,026 4/1963 Weisgerber 93/36 3,202,065 8/1965 Bolcato 93/36 3,215,050 1l/1965 Schroeder 93/36 3,286,005 11/1966 Cook 93/34 X 3,322,045 5/1967 Tanona 93/39 3,439,590 4/1969 Rosenberg. 93/55.l 3,505,933 4/ 1970 Schmidt 93/79 FOREIGN PATENTS 773,172 4/1957 Great Britain 93/36 Primary Examiner-Wayne A. Morse, Jr.
Attorney- Brooks, Haidt & Haffner ABSTRACT: Method of making a container by first printing and applying an overlying high gloss coating on a container blank adapted to form a container sidewall member having inner and outer plies with blocking adhesive therebetween; then forming said blank into a tubular sidewall member and attaching a preformed bottom member thereto; then holding the formed container such that its sidewall is inclined downwardly towards the open end of the container; applying a first coating of melted wax of particular composition and at a high temperature as set forth in specification, draining the excess wax from the container, and applying a second similar coating of the melted wax but at a lower temperature as described; and applying a melted wax coating to the exterior of the bottom of the container using nozzle guards, all in manner avoiding deposit of wax on high gloss exterior of sidewall m m re PATENTED SEP 7 I971 SHEET 1 [IF 2 Ill I I IN RODNEY E LUDDER METHOD OF MAKING PAPER CONTAINER HAVING A HIGH GLOSS EXTERIOR FINISH AND WAX COATED INTERIOR AND BOTTOM SURFACES This application is a division of my copending applications Ser. No. 605,338, files Dec. 28, I966, now abandoned and Ser. No. 677,906, filed Oct. 25, 1967.
This invention relates to two-piece paperboard containers intended especially for the packaging of comestibles and more particularly for cottage cheese and other cultured dairy products, salads, butter, spreads and the like which require low gas and/or moisture barrier properties. It has been found that in the packaging of foods of this nature it is difficult to prevent the transmission of moisture vapor and the transmission of oxygen gas, the passage of both of which must be prevented in order to protect the flavor and freshness of the food. For example, it has been found that paperboard containers heavily coated with a suitable wax are much more impervious to the passage of moisture vapor and oxygen gas than are many plastic containers. In the production of such heavily waxed paperboard containers, it is difficult to produce a highly glazed or glossy outer surface on the sidewall of the container, which is especially desirable where the sidewall bears fanciful designs often comprising multicolors.
In the conventional heavily waxed two-piece paperboard containers, a heavy coating of wax is applied to the exterior surface as well as to the interior surface and a highly glossy exterior surface of the sidewall is unobtainable without ruining the wax properties. For example, while it is possible to obtain high gloss on overall waxed food containers simply by cold quenching them while the wax is still liquid, this sets up surface stresses which crack under refrigeration and the containers fail rapidly offering no resistance to the food product.
According to the present invention, the sidewall or body comprises at least two plies which may be effected by a double wrap made ofone sheet or a single wrap comprising a plurality of sheets. In either event, an intervening blocking layer of material separates the inner and outer ply. The blocking layer may be in the form of an adhesive or glue which is impervious to the penetration of the hot wax applied to the interior of the container. or in the form of a blocking material which serves the same purpose, or a combination thereof. The purpose of such construction is to prevent the hot wax applied to the interior of the container from penetrating to the exterior surface ofthe container. which exterior surface is desired to be coated with a glossy finish, either by means ofa high gloss wax or by means of a suitable coating of plastic material, in the manner well known in the art.
The blank from which the sidewall is to be made may be printed with the desired design and colors, as is customary in present practice of paper printing and coating, and thus provide a clear, high gloss finish, preferably by means of a thermosetting resin.
After the sidewall and bottom of the container are assembled in the manner well known in the art, the interior of the container is coated by a special formulation of paraffin wax, which wax is prevented from passing to the highly glossy outer surface of the sidewall but is permitted to penetrate the entire bottom of the container.
To provide moisture resistance from exterior sources, such as when nest-able containers are placed in stacked relation and the bottom of one container is seated within the lid of a lower container which often acts as a depository for moisture, the bottom surface ofthe container is coated by a special formula tion ol paraffin wax. Allernatcly, the wax coating may be applied substantially to the ledge ol' the container bottom sur- 'lhcse coatings give the container the dual advantages of( I) an inner barrier to the transmission of moisture vapor and oxygen gas, thus protecting the flavor and freshness of the food product; (2) a superior outside finish which not only contributes additional holding qualities to the package but comdetailed description thereof when taken together with the accompanying drawings, in which:
FIG. 1 is a perspective top view of the container;
FIG. 2 is a sectional view taken at 2-2 of FIG. 1;
FIG. 3 is a somewhat diagrammatic view showing a cross section of a sidewall of the container made from a single sheet comprising two plies;
FIG. 4 is a similar view showing a cross section of a sidewall of the container made from a double wrap ofa one-ply sheet;
FIG. 4a is a plan view on a somewhat reduced scale of the blocking coating on said blank.
FIG. 4b is a greatly enlarged sectional view taken at 4b-4b of FIG. 4 showing the two-ply sidewall fabricated from the blank illustrated in FIG. 4a and showing the relation of the interior wax coating on the inner ply, the barrier between the two plies, an outer barrier, and the exterior glazed finish on the outer ply of the sidewall;
FIG. 5 is a longitudinal sectional view showing the first step of squirting or pouring wax into the interior ofthe container;
FIG. 6 is a similar view showing the draining of the excess wax out of the mouth of the container;
FIG. 7 is a view similar to FIG. 5 showing the second step of squirting or pouring wax into the container;
FIG. 8 is a greatly enlarged sectional view taken at 88 of FIG. 7 showing the two-ply sidewall and the relation of the interior wax coating on the inner ply, the barrier between the two plies and the exterior glazed finish on the outer ply of the sidewall; and
FIGS. 9, l0 and 11 inclusive, are longitudinal sectional views showing the coating of various portions of the container. bottom.
Referring to the drawings, and more particularly to FIGS. I and 2, it will be seen that the container indicated in gencrnlas 9 comprises a tapered sidewall designated in general as 10 and a bottom member designated in general as 11. The sidewall 10 comprises an inner ply I2 and an outer ply l3 and an intermediate barrier comprising a blocking layer 14, which may be in the form of a blocking adhesive 14a, (FIG. 4b), which is preferably polyvinyl alcohol or vinyl acetate, the preference being in the order named; or which may be in the form of ablocking coating 14b which (FIG. 4b) is preferably of a clay base, as for example, polyvinyl acetate and/or styrene butadiene latex combined with a clay material or titanium dioxide to obtain a white pigmentation to print upon. It is contemplated that other suitable adhesives may be employed, such as polyethylene or a starch adhesive, as well as a variety of suita-, ble coatings, formulated to effect the desired barrier for preventing the passage of hot wax through the outer ply 13.
As seen in FIG. 5, the container is formed in the manner well known in the art having a bottom member 11, with an interior surface Ila and an exterior surface 1112, which is secured in position as by providing a downwardly peripherally extending flange llc which is disposed between the outer wall portion adjacent the lower end of the sidewall 10 and the inwardly and upwardly turned end or skirt 10d of said end to form a pedestal 18. The bottom flange I It" is peripherally scaled between the adjacent portions We and Illd of the sidewall member I0 to provide a liquidtight seal, At the lower end of the pedestal l8, intermediate and integrally formed with said outer wall portion 10c and said upwardly turned skirt 10d is a bottom ledge 10s on which the container 9 is generally supported. The complete bottom surface 11f, as illustrated in FIG. 5, of the container 9, includes the bottom ledge 10s, skirt 10d and the exterior surface 11b, which is the portion of the bottom member 11 circumscribed by peripheral skirt llc. A suitable rolled rim or lip is formed on the open end of the container as is customary and in a manner well known in the art.
In FIG. 3 there is shown the conventional formation of a sidewall by a single wrap designated 100 which comprises at least two plies of material adhered together by blocking adhesive with the ends of a single wrap multi ply sheet secured together in a side seam 16; while in FIG. 4 there is shown the conventional manner of forming a sidewall by two or more wraps of a single-ply sheet wherein the plies are laminated together by means of an intervening adhesive, which may be a blocking layer, and the ends of the single-ply sheet are secured together as by side seam 1'7 as is customary in the prior art. As above indicated, the outer surface of the sidewall 10 commensurate with the outer surface of the container may be printed on the container blank before the sidewall of the container is formed and, whether plain or with a design, its exterior surface may be provided with the desired high gloss. Preferably, the high gloss finish is provided by first printing and then coating with a thermosetting resin to provide a clear, high gloss protective finish, such as 13,
In FIG. 4a, there is shown a plan view of the present blank by whichthe sidewall member 10b is formed in accordance with a preferred embodiment of the invention. The blank sidewall is of a length to form the double-wrap container illustrated in H0. 4 in which one half of the blank, when formed, is the inner ply l2 and the other half the outer ply 13. The paperboard stock carries a coating as, for example, a polyvinyl acetate along with a binder which is preferably of a clay base material, and which may form the blocking coating as hereinafter discussed.
Preferably, the high gloss finish is provided by first printing upon one half of one side of the wall 10b and then coating with a thermosetting resin to provide a clear, high gloss protective finish as 13. When the wall 10]? is of this double-wrap construction, the blocking adhesive 14a is applied opposite the printed side of the blank. When wrapped this surface 14a contacts 14b. The blocking coating 14b iscontained on the inner ply 12 so that, in assembled relation for a double-wrap container, we have illustrated in FIG. 417 an exterior high gloss coating 13', blocking coating 14b, outer ply I3, blocking layer 14, formed of either or both the blocking coating 14b and blocking adhesive 14a, inner ply 12 with an interior wax coating 12' hereinafter discussed in detail, Thus as illustrated in FIG. 4b, we have a container constructed in which the blocking layer 14 intermediate the inner ply l2 and outer ply 13 is comprised of both a blocking adhesive 14a and a blocking coating 14b. Depending upon the properties of the blocking adhesive 14a and the blocking coating 14b, either one or the combination ofthe two may constitute the blocking layer l4 and prevent the penetration of the wax 12 from reaching the outer ply 13, An additional feature is that a secondary blocking layer 14 may be provided between the outer ply 13 and the high gloss protective finish 13 in the form of blocking coating 14b to further assure the obtainment ofa container free from unsightly wax marring on the exterior surface thereof and as a base for printing upon the container sidewall 10. 7
After the sidewall and bottom have been assembled to complete the paperboard container 9 for either it single-wrap or double-wrap container, the container is suitably held in a holder designated and a series of containers so held is carried on a conveyor with the longitudinal axes disposed in the horizontal plane. The containers are rotated about their longitudinal axes while moved forward by the conveyor and wax is squirted or poured into the interior of the containers as by nozzles 21. It will he noted that the container 9 shown in the drawings has a tapered sidewall 10, which as is customary in remove the excess wax the container is tipped as shown in FIG. 6 to substantially increase the sidewall tilt and drain out excess wax 22. Of course, if it is desired to treat cylindrical containers, the holder 20is held on the conveyor so that the container sidewall is initially inclined at a suitable angle, say about 38, and thereafter tilted to a greater inclination to drain out excess wax 22. The increased tilt angle as shown in FIG. 6 may be efiected at one or more points in the path of travel of the container, as by means of cam segments (not shown) as is well known in the art.
The wax employed is preferably a composition comprising 99.5 percent of fully refined paraffin wax having a melting point of 132-l34 F. and it percent of a polyethylene additive, such as one made by Eastman Chemical Company known in the trade as Cl3." This formulation of wax is applied in two steps, the first at about 255 F. and after the excess has been drained from the container as shown in FIG. 6, a second application is made with the above composition at about 180 F such as by means of a nozzle 23. After the second application the excess wax is drained from the container and the con tainer is dried.
As will best be seen in FIG. 8, the wax not only coats the interior surface of inner ply 12 to provide the interior wax coating 12', but partially penetrates the same to inhibit flaking. While this wax coating thus applied is preventing from passing through the paper-adhesive laminate to the exterior surface of the sidewall 10, it does penetrate entirely through the bottom 11 of the container and a complete penetration through'the bottom of the container is desirable so that the bottom is fully covered and the extra wax on the bottom adds strength to the corner and center portions of the container and also further assures a sealing fillet between the bottom member 11, and sidewall 10.
For those containers stored or filled in a moisture-laden or wet environment, it has been found desirable to provide a protective coating of wax on the complete bottom surface of the container, or parts thereof, in a manner to prevent the moisture from saturating the seal between the outer wall portion We, upwardly turned skirt 10d of the wall 10 and the downwardly extending flange 11c therebetween. in practice, the filled containers are often stored in refrigerators and the bottom ledge [0e of the pedestal rests within the lid of a lower stacked container The lid often contains a degree of condensation, such as water, that upon storage for several days tends to saturate the ledge 10c, upwardly turned skirt 10d and downwardly extending flange 11c to effect a separation of the adhesive at the juncture therebetween which affects the structural rigidity of the container. When the skirt 1011 becomes saturated, it starts to return to its original flat shape thereby applying a force on the overlapped seal which has a tendency to crack the seal.
Referring more particularly to FIGS. 9, l0 and 11, we have illustrated an exterior wax coating on the bottom surface, which wax may be of the same type 12 as used to interiorly coat the container, and which wax is applied either subsequent to the application of the interior wax as described or thereafter. i
ln FIGv 9, the bottom surface llfis wax coated while the container is mounted generally vertically on a holder designated 25 and, which may be rotated, while the wax is applied as by squirting or pouring it on to the ledge lflr thereof by nozzle 26. Preferably when the entire bottom surface is to be coated the container and supply of melted wax are maintained in horizontally spaced relationship and moved along a defined path relative to each other to coat the surface thereof. Controlling means 27 is provided, which may be in the form of an outer guard means in the form of funnel 28 and an inner guard means in the form of funnel 29, mounted for relative movement with respect to each other in any conventional manner not shown, to confine the area of application of the wax and then move the container and control means relative to each other for waxing of the next container. The spacing at the mouth of the funnels is substantially equal to the width of the ledge e to assure that the wax substantially coats the ledge only and not the exterior high gloss finish.
FIG. 10 illustrates the invention wherein the bottom ledge [0e and skirt 10d are coated with the wax and particularly the junction between the latter and bottom member 11a. The nozzle 26 is positioned within the confining means 27 formed by the outer funnel 28 and inner funnel 29 and the latter terminating in spaced relation to the upwardly turned skirt 10d which is wax coated with the ledge l0e.
FIG. 11 illustrates the invention wherein the entire bottom surface 11f, including the skirt 10d, bottom ledge We and the exterior surface 11b, enclosed by the skirt 10d, are coated as by positioning the nozzle 26 in spaced relation to the bottom 11 and providing control means 27 in the form of the funnel 28 having a diameter at its base substantially equal to the outer diameter of the container. Alternately, the bottom member 11 and skirt 10d may be wax coated by reducing the diameter of the control means 27. The holder can be simultaneously rotated relative to the nozzle 26, in any conventional manner to properly disperse the wax being applied or the holder and nozzle 26 may be maintained in fixed relationship to each other. In addition the wax is applied through the nozzle 26 in timed relation to the positioning of the container in overlapping relation thereto. The container may be intermittently stopped when the wax is applied thereto.
Thus in accordance with the present invention applicant has invented a packaging container of the nestable type which for the first time combines many ideal characteristics not heretofore available in a single container. The invention permits the obtainment of a high exterior glossy finish which has long been desired for beauty and texture to properly attract the eye of the consumer, and still have the qualities that permit the storage of the container for prolonged periods of time, due to its wax coated interior and bottom surface. The wax coated bottom permits the container to remain on a damp or moistened surface for a considerable period of time without affecting the structure of the container and more importantly the contents contained therein.
Having thus described my invention with particularity with reference. to its preferred form, it will be obvious to those skilled in the art, after understanding my invention, that other changes aiid modifications may be made therein without departing from the spirit and scope of my invention, and I aim in the appended claims to cover such changes and modifications as are within the scope of the invention.
What is claimed is:
l. A method of making a two-piece paper container comprising the steps of: providing a tubular sidewall member having an outer ply and an inner paper ply adhered together by a blocking adhesive, securing a paper bottom member in sealed relationship to the lower end of said sidewall member thereby forming a container having an open end and an exterior bottom surface. holding said container with its sidewall inclined downwardly towards its open end and rotating the same about its longitudinal axis while moving the same in a linear direction, applying a first layer of melted wax at a preselected temperature into the interior of said container during said linear and rotational movement to evenly spread said melted wax substantially over the entire interior paper surface of the sidewalls and bottom of said container, tipping said container to increase the downward angle of its sidewall so as to drain out excess melted wax, applying a second application of melted wax to the interior of said container at a temperature substantially lower than the temperature of the wax during said first application and while moving the container linearly and rotationally about its axis for evenly spreading said second application of wax substantially over the entire interior surface of the sidewalls and the bottom of said container, draining excess wax from the interior of the container, and pen mitting said wax to solidify.
2. The method as set forth in claim 1 wherein said wax comprises a refined paraffin wax having a melting point of about 132-134 F. to which has been added about /z ercent of .a polyethylene additive, the temperature of sai wax being about 255 F. during the first application and about F. during the second application, and during at least the first of said wax applications, said container sidewall being inclined downwardly at an angle of from about 3 to about 8 with respect to the horizontal.
3. The method as set forth in claim 1 which further comprises applying an exterior coating of a melted wax to said bottom surface of the container to provide a moisture resistance barrier thereon.
4. The method as set forth in claim 3 wherein the exterior of said bottom surface of the container is defined by a bottom ledge, an upwardly extending skirt, and a portion of the bottom member circumscribed by said skirt, said step of applying an exterior coating of a melted wax to said bottom surface of the container comprising the steps of holding said container in a substantially vertical position, providing a nozzle for spraying melted wax, and moving said container in overlapping relationship to said nozzle to obtain an even coating of said wax on said bottom surface, said melted wax being applied upwardly through said nozzle.
S. A method of making a two-piece paper container of the character described having a high gloss outer surface and a wax impregnated inner surface which comprises providing a tubular sidewall member having an outer ply and an inner ply adhered together by a blocking adhesive, said member being formed by the steps of cutting a flat blank corresponding to said sidewall member from paper material, printing on one side of said blank corresponding to the outer surface of said sidewall member when formed into said tubular shape, and applying a high gloss finish overlyingsaid printing, and then wrapping said blank to form said tubular sidewall member, securing a bottom member in sealed relationship to the lower end of said sidewall member thereby forming a container having an open end and an exterior bottom surface, holding said container with its sidewall inclined downwardly towards its open end and rotating the same about its longitudinal axis while moving the same in a linear direction, applying melted wax into the interior of said container during said linear and rotational movement to evenly spread said melted wax, tipping said container to increase the downward angle of its sidewall so as to drain out excess melted wax, applying a second application of a melted wax to the interior of said container while moving the same linearly and rotationally about its axis, said wax comprising a refined paraffin wax having a melting point of about 132 134 F. to which has been added about /2 percent of a polyethylene additive, the temperature of said wax being about 255 F. during the first application and about 180 F. during the second application, draining excess wax from the interior of the container and drying the same, applying an exterior coating of a melted wax to said bottom surface of the container comprising the steps of holding said container in a substantially vertical position, providing a nozzle for melted wax, and moving said container in overlapping relationship to said nozzle to obtain an even coating of said wax on the peripheral area of said bottom surface using outer and inner guard means adjacent said peripheral area.