CA2193386A1 - Method for forming corrugated paper container and container made therefrom - Google Patents
Method for forming corrugated paper container and container made therefromInfo
- Publication number
- CA2193386A1 CA2193386A1 CA002193386A CA2193386A CA2193386A1 CA 2193386 A1 CA2193386 A1 CA 2193386A1 CA 002193386 A CA002193386 A CA 002193386A CA 2193386 A CA2193386 A CA 2193386A CA 2193386 A1 CA2193386 A1 CA 2193386A1
- Authority
- CA
- Canada
- Prior art keywords
- paperboard
- layer
- flute
- contoured
- fluted
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
- B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants
- B65D81/26—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators
- B65D81/264—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators for absorbing liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
- B65D65/38—Packaging materials of special type or form
- B65D65/40—Applications of laminates for particular packaging purposes
- B65D65/403—Applications of laminates for particular packaging purposes with at least one corrugated layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
- B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants
- B65D81/26—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators
- B65D81/261—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators for draining or collecting liquids without absorbing them
- B65D81/262—Rigid containers having false bottoms provided with passages for draining and receiving liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
- B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
- B31B50/00—Making rigid or semi-rigid containers, e.g. boxes or cartons
- B31B50/59—Shaping sheet material under pressure
- B31B50/592—Shaping sheet material under pressure using punches or dies
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Food Science & Technology (AREA)
- Making Paper Articles (AREA)
- Containers Having Bodies Formed In One Piece (AREA)
- Container Filling Or Packaging Operations (AREA)
- Cartons (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
- General Preparation And Processing Of Foods (AREA)
- Auxiliary Devices For And Details Of Packaging Control (AREA)
Abstract
A method for forming a corrugated paperboard container and a container made therefrom having a first layer (12) of flat paperboard to which is attached a second layer (14) of contoured paperboard, said contoured layer having a plurality of flutes (16), each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, said forming method comprising, placing the corrugated paperboard into a stamping die, the stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed; pressing the paperboard between the die and the cavity to apply a pressure to the paperboard; applying heat to the paperboard simultaneously with said application of pressure; and removing said die from the cavity.
Description
W095135204 2 1 9 3 3 8 6 PCT~S95~7722 METHOD FOR FORMING cnRRn~T~n ~APER CONT~TN~R
AND ~- ~TN~R NADE L~ ~U-.
BA~U~_.J OF THE l~v~l~. lU_.
The present invention relates to a method of forming corrugated pAr~rho~rd containers, including food containers and food trays and, in particular, employing corrugated paperboard in a novel stamping process, which rAr~rhoArd has an increased frequency of flutes in its internal layer, such that upon introducing the corrugated paperboard to the stamping process, the paperboard does not break apart and is capable of being molded t~o produce a satisfactory unitary structure.
Heretofore, to produce unitary paperboard containers without gluing, manufacturers have attempted to stamp certain types of corrugated paperboard, such as E-flute corrugated paperboard, and have been unable to create a satisfactory unitary construction.
Efforts at stamping corrugated paperboard resulted in the paperboard breaking up during the stamping process and have failed to achieve a utilitarian molded unitary structure.
Accordingly, the use of corrugated paperboard for containers has been limited to an expensive multi-step manufacturing process in which the r~p~rhQArd must first be printed, then die cut and then passed through complex box folding machinery. Accordingly, a corrugated paperboard that would permit pressing and forming (stamping) into a container and a method of pressing and forming corrugated paperboard container would be desirable.
SUMMARY OF THE lhv~lluN
Generally speaking, in accordance with the instant invention, a method of forming a unitary container from corrugated paperboard is provided. The method comprises introducing corrugated paperboard having an outer flat layer of paperboard and an internal contoured layer of paperboard having a high frequency, per linear meter of paperboard, of flutes formed from alternating upper and lower curved surfaces into a die press and pressing the pAp~rhoArd between a die and a cavity to apply pressure to the Wo9S/3~204 2 1 9 3 3 8 6 P~ 1/ L ~. / /~
paperbo~rd. Applying heat to the paper~oard simultaneously with the application of pressure.
In a second type of container a three-layered corrugated paperboard tray is provided. The paperboard is formed of a first layer of corrugated paper, a second layer of industrial strength paper, and a third layer of paper having holes formed therein, the corrugated layer being sandwiched between the second layer and third layer. The top paper layer comprises a sheet of paper having a plurality of holes therein resting on the fluted crests of the corrugated layer. The upper surface of the top perforated layer is moisture resistant. The underside of the fluted layer and the bottom layer of the corrugated construction have moisture-resistant barriers to prevent leaking through the entire tray.
Accordingly, it is an object of this invention to provide an improved method for forming a unitary container of corrugated paper.
Another ob~ect of the invention is to form a container from corrugated paper by stamping, without the need for a complex box folding machinery or the need for die cutting.
Yet another object of the invention is to form a unitary box from single face or single ply corrugated paper.
A further object of the invention is to provide a container made out o~ lighter, cheaper and recyclable materials.
Still another object of the invention to provide a method for forming complex shapes by pressing and forming paperboard.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
WO95l35204 2 1 9 3 3 8 6 1~.,. "~
~ 3 BRIFF DFSCRIPTION OF T~F DRAWINGS
For a fuller understanding of the invention, reference is had to the following description, taken in connection with the accompanying drawings, in which:
FIG. 1 is a partial perspective view of the paperboard utilized in connection with the invention;
~ FIG. 2 is a front elevated view of the paperboard constructed in accordance with the invention;
PIG. 3 is a sectional view of stamp used in connection with the method of the invention;
FIG. 4 i5 a perspective view of a container constructed in accordance with the invention;
FIG. 5 is a perspective view of the pAr~rho~rd food tray constructed in accordance with another ~ of the present invention;
FIG. 6 is a partial top plan view of a paperboard utilized in connection with the present invention; and FIG. 7 is a cross-sectional view taken along line 3-3 of FIG. 5 of the paperboard utilized in connection with the present invention.
n~ATT.T~n D~SCRIPTION OF T~ ~K~KK~ h~u~L~
An example of corrugated paper used to form applicant~s box is disclosed in U.S. Patent No. 4,931,346 which is incorporated herein by reference. Reference is made to FIGS. 1 and 2, wherein a paperboard, capable of being pressed and formed (stamped), generally indicated as 10, comprising two layers is depicted. An outer layer 12 is flat p~p~rho~rd having a thickness in the range of 0.3 mm to l.S mm.
An internal layer, generally indicated as 14, of paperboard 10 is contoured, having a thickness in the range of 0.23 mm to 0.5 mm. The internal contoured layer 14 consists of flutes 16, each flute being formed by one of an alternating upper 18 or lower 20 curved surface. Internal layer 14 is glued to an inner surface 22 of the outer layer 12 along the lower curved surfaces 20. Gluing the lower curved surfaces 20 of the internal layer 14 W095135204 2 1 9 3 3 8 6 ~ , "~
.
to the inner surface 20 of the outer layer 12 allows for the formation of exposed ridges 24 and grooves 26 (FIG. 2) across the unattached surface of internal layer 14. Internal layer 14 has a high frequency (flutes/meter) of flutes 16 and a corresponding high frequency of ridges 24 on the exposed surface of internal layer 14 allowing the paperboard 10 to be pressed into a unitary structure.
One upper curved surface 18 and an alternating lower curved surface 20 make up one set of ~1utes 28. Each flute 16 has a height in the range of 0.9 mm to 1.2 mm or 0.035 inches to 0.047 Lnches, and sets of flutes 28 in the internal layer 14 have frequency within the range of 350-400 sets of flute 26 per linear meter of paperboard 10. In an exemplary embodiment, the number of sets of flutes is 375 per linear meter of paperboard, the flute repeat length to flute height ratio is 2.6 or less, and the coLl~s~"ding number of ridges on the top surface of the internal layer is 6 to 12 ridges per inch.
In producing the stampable p~r~rho~rd 10, internal contoured layer 14 has glue applied to the lower curved surfaces 20. Outer layer 12 and internal layer 14 are passed through rollers under a sufficient pressure to compress the two layers together to adhere them. As a result, lower curved surfaces 20 adhere to inner surface 22 of the outer layer 12 and the pressure causes the lower curved surfaces 24 to imbed and become indented into inner surface 20 of outer layer 12 by at least 0.1 mm (0.004 inches). In the preferred ~ ~ t, the amount of indent (or imh~ing) is 0.2mm (0.008"). The high frequency of flutes 16 per inch, and, hence, the colla~u.lding increased number of ridges 24 across the unattached surface of the internal layer 14, causes the flats (between curves 18 and 20) in each of the flute sets 28 to become more vertical and this adds strength during ~ ~saion so that the paperboard can be pressed and formed. Accordingly, by increasing the number of flutes 16, and hence the number of ridges 24, the ability of the corrugated paperboard to be pressed and formed consequently increases.
The flutes in the stampable paperboard have a higher frequency and higher amplitude when compared with other fluted 2 1 9 3 3 8 ~ PCTNS95/07722 .
paper. This maximizes the ratio of flute repeat length to flute height. Because of the more vertical flute rise at the midpoint between flute tips there is a greater rate of change of height over distance so that for a given height of flute rise, the corrugated paperboard will have a smaller repeat ratio when compared to E-flute or E-flute, by way of example, and for a given repeat ratio the described paperboard will have a higher amplitude than E-flute or F-flute corrugated paperboard. In the preferred embodiment the stampable corrugated paperboard has a flute repeat length to flute height ratio of 2.6, whereas in E-flute or F-flute, the flute repeat length to flute height ratio is 2.8.
It is the high frequency of flutes per inch in the corrugation that specifically allows the paperboard to be molded by the dye pressing method described in detail below. Unlike attempting to mold corrugated paperboard of the prior art, which paperboard does not have such high density fluting in the corrugation and consequently breaks up in the molding process, the corrugated paperboard described above does not break up in the molding/stamping process and, instead, is able to be molded into a unitary structure. This ability to mold the corrugated paperboard into a unitary structure is spec;~ie~lly due to the high density of fluting in the corrugation.
In one preferred ~'i t of the present invention, single-face corrugated paperboard comprising a flat outer layer and an internal contoured layer comprising a flute repeat length to flute height ratio of 2.6 is pressed and formed by introducing the single-face corrugated paperboard into a stamp and applying pressure and temperature for an amount of time such that the corrugated paperboard becomes pressed and formed to form a unitary container. ~he high frequency of flutes and ridges in the internal layer cause the single face paperboard to be stamped by this method to form a satisfactory unitary structure such as a container.
Reference is now made to FIG. 3 which is a stamp used in conjunction with the method for stamping the corrugated paper as shown. In an exemplary embodiment of the method, it is important that the p~p~rh~rd be flexible and easily deformed without W095/3~204 2 1 9 3 3 8 b PCT~S95/07722 .
fracturing or rr~rking Accordingly, in a first step moisture is added to the paperboard to soften the fibers. Moisture is added until the moisture level of each sheet is 8 to 11%, however, it is best to run as close to the lower end of this range in an exemplary embodiment to prevent excessive moisture forming steam beneath any coating applied to the paperboard in the forming process causing the coating to blister. However, the deeper the stamping the higher moisture content required. An additive such as fluorocarbon is added to the moistening process to achieve about a 1~ solution in water. The additive assists in water retention, aids forming and reduces grease wicking in the final process.
The moisture and fluorocarbon applied to the paperboard does not immediately penetrate the sheet so that the sheet remains stiff and difficult to form at first. Additionally, latent moisture may still be laying on top of the sheet, having not been absorbed by the fibers, therefore in an exemplary ~mho~i t, the paperboard sits for forty-eight to seventy-two hours before forming, allowing the board to reach equilibrium and to obtain a more uniform distribution of moisture throughout the cro8s-section of the sheet.
The r~r~rho~rd is deep drawn utilizing a stamp, generally indicated as 100. The stamp includes a bolster plate 102 upon which is seated a heated female cavity 104. A plunger is slidably mounted on bolster plate 102 to move into and out of heated female cavity 104.
A top die mounting plate 108 slidably supports a reciprocating platen 110. Platen 110 is attached to a male die 112. Male die 112 moves towards and is received in heated female cavity 104 with the reciprocating motion of platen 110. A draw ring 114 is mounted about male die 112 for positing paperboard prior to stamping.
The method of pressing or stamping the paperboard consist of the basic steps of feeding the paperboard, creasing the paperboard, cutting the paperboard and forming the paperboard. The moistened paperboard is creased in an area where corners will be formed while the r~r~rhoard blank is formed in a web. The web is w095/35204 2 1 933 86 P~ ' "~
.
then advanced a predet~rm; n~ amount centering the creased paperboard between male die 112 and heated female cavity 104.
Reciprocating platen 110 pushes male die 112 through the die cavity 104, shearing the registered pre-creased paperboard from the in~r of the web and urging it to fall through the die creating the blank. The pre-creased cut blank falls through and is centered between male die 112 and draw ring 114 and heated female cavity 114 mounted on bolster plate 102.
Draw ring 114 is extended and contacts the paperboard, tensioning the paperboard as male die 112 descends pushing the paperboard into female cavity 104. The draw ring holds the board tightly against the rim of the female cavity to discourage wrinkles from forming on the side panels of the container as it i8 being drawn. The draw ring 114 further forces excess paper into the corners and insures that neat, even folds are made, following the pre-creased lines. The more tension applied to the paperboard during forming, the neater the folds and fewer wrinkles formed on the side panels.
Once all of the paperboard has been drawn into the heated cavity, the press extends the male die slightly, depressing the female cavity 104 and bolster plate 102 by 1/30 seconds of an inch holding the tray under pressure and heat. In an exemplary ~mhn~i t, the pressure applied is approximately four tons at 120~E. This allows the moisture in the board to turn into steam and escape through vents provided in the die, setting the paperboard in the shape of the die. Essentially, the folds in the corners are steam ironed into the form of the container, imparting a structural integrity to the container.
The stamp (press) is then opened and plunger 106 is activated entering female cavity 104 e~ecting the container from the heated female cavity. The excess paper is then trimmed from the formed container.
FIG. 4 shows a corrugated paperboard container, generally indicated as 200, made by the stamping process of the present invention. The container has a clam shell construction and includes a lower compartment 210 for receiving food and the like W095~s204 21 933 8 6 - r~
and an upper compartment 240 for covering and closing the container. Lower compartment 210 includes a base 212 and four upstanding sidewalls 214, 216, 218 and 220, integrally formed with base 212 along fold line 222 formed during stamping. Wall 214 is coupled to wall 216 along a curve at connecting wall 224 formed during stamping. Similarly, wall 216 is coupled to wall 218 by a curved wall 226, wall 218 is coupled to wall 220 by curved wall 228 and curved wall 220 is formed integrally with front wall 214 by a curved w211 230. Each of curved walls 224, 226, 228, 230 are formed during stamping and easily could be formed as fold lines.
Wall 214 is formed with a lip 232 at an acute angle with wall 214 and having slot 234 formed therein.
Upper compartment 240 is similar in construction to lower compartment 210 and includes a top wall 242 and side walls 244, 246, 248 and 250, each of walls 244, 246, 248 and 250 are coupled to top wall 242 along a fold line 252 formed during stamping. Side walls 244, 246, 248 and 250 are also integrally coupled, each ad~acent sidewall by a respective curved wall 254, 256, 258 and 260. Side wall 248 of upper compartment 240 and side wall 218 of lower compartment 210 are pivotably coupled together by a hinge 262 formed as a fold line between lower compartment 210 and upper compartment 240 during the stamping process. ~pper compartment 240 rotates about hinge 262 in the direction of arrow A to close container 200 upon itself.
Side wall 244 is also formed with a lip 264 having a tab 266 formed thereon. Tab 266 is received within slot 234 to fa8ten upper cl ~~t 240 to lower component 210.
In a preferred embodiment, bottom compartment is formed with a receiving lip adapted to receive a lip about upper compartment 240 to further seal in a mating relationship, container 200.
As shown in FIG. 4, upper compartment 240 and lower compartment 210 are each formed from paperboard 10 including outer layer 12 to which is glued one contoured internal layer 14.
Contoured interior layer 14 consists of flutes 16 which are formed by alternating upper 18 and lower 20 curved surfaces. In a W09sl3s204 2 ~ 9 3 3 8 6 ~ ~I/U~
~ 9 preferred embodiment the ratio of flute repeat length to flute height is 2.6 or less. Upon gluing the lower curved surfaces 20 of the internal layer 14 to the inner surface of outer layer 20 ridges 24 and grooves 26 are formed on the outer surface of the internal layer 14.
The paperboard employed may be solid bleached sulfate (SBS) or rhirhn~rd, or a recycled material. In one ~mhn~i t, outer flat layer 12 may be chipboard, and internal layer 14 may be a recycled paperboard medium. In a preferred embodiment, the outer layer 12 has a thickness of 0.007 inches (7 points) and internal contoured layer 14 has a thickness of 0.040 inches (40 points).
The two layers together may have a working range from 30 to 60 points from the outer surface of outer layer 12 to the ridged top of internal layer 14. As a result, less paperboard is used, the container is light in weight, and although the container maintains its strength and rigidity as if layers were solid paperboard, it, at the same time, possesses the capability of becoming stamped.
As shown, the internal surfaces of walls 212, 214, 216 and 218 as well as 242, 244, 246 and 258 of compartments 210 and 240 are formed with ridges having upper ridges 24 and grooves 26 between ridges 24. There are 6 to 12 ridges per inch, and, in a preferred embodiment, there are 9 ridges per inch. As shown more clearly in FIG. 4, the upper ridges 24 of bottom wall 212 form a raised food-receiving surface on which the food is placed. Any moisture given off by the hot food within the container is received and collected within grooves 26. In this manner, the collected moisture is not absorbed by the food, and container 200 prevents the food from becoming soggy.
In a preferred embodiment, internal layer 14 is coated with a water-based coating prior to stamping. The coating is repulpable, recyclable, and resists the penetration of moisture given off by the hot food. As a result, the molded paperboard container maintains its strength and rigidity.
Reference is made to FIGS. 5 and 6 wherein a portion of a laminated paperboard 10 utilized in constructing a food tray 300, comprising three layers in accordance with another ~mho~i t of Wo95/35204 2 1 9 3 3 8 6 PCTNS95/07722 the invention is depicted. Two of the layers are similar in construction to the paperboard described above, the difference being the addition of a waterproof barrier. Like numerals are utilized to identify like structures.
A first outer layer 12 is flat paperboard having a thickness in the range .15 mm to 1.0 mm. An internal layer generally indicated as 14 of paperboard 10 is contoured, having a thickness in the range of .15 mm to .25 mm. Internal contoured layer 14 consists of flutes 16, each flute being formed by one of an alternating upper 18 or lower 20 curved surface. Internal layer 14 is glued to an inner surface 22 of the outer layer 12 along the lower curved surfaces 20. Gluing the lower curved surfaces 20 of the internal layer 14 to the inner surface 22 of the outer layer 12 allows for the formation of exposed ridges 24 and grooves 26 across the upper surface of internal layer 14. Internal layer 14 has a high-frequency (flutes/meter) of flutes 16 and the corresponding high frequency of ridges 24 in the upper surface of internal layer 14.
A moisture barrier coating 27 is provided on upper surface 22 of outer barrier layer 12. A similar moisture barrier (not shown) coating 29 is provided on the bottom surface of internal layer 14. The top surface of layer 14 is uncoated and therefore absorbs moisture coming in contact therewith. Barrier coatings 27, 29 create a moisture barrier which retains moisture captured by internal layer 14 within layer 14, and protects the tray from leakage.
One upper curved surface 18 and an alternating lower curved surface 20 make up one set of flutes 28. Each flute 16 has a height in the range of 0.9 mm to 1.2 mm or 0.35 inches to 0.047 inches, and sets of flutes 28 in the internal layer 14 have frequency within the range of 350-400 sets of flute 26 per linear meter of paperboard 10. In an exemplary : ' ~i t, the number of sets of flutes is 375 per linear meter of paperboard, the flute repeat length to flute height ratio is 2.6 or less, and the corresponding number of ridges on the upper surface of internal layer 14 is 6 to 12 ridges per inch. The high flute frequency w095~5204 2 l q3386 r~ "~2 provides a greater exposed layer surface per meter increasing the area of absorbing surfaces in layer 14.
Perforated top layer 30 is provided above internal layer 14. Layer 14 has a thickness and construction similar to that of outer layer 12. However, perforated openings 34 are provided uniformly on the surface of layer 30. Top layer 30 is glued at an inner surface to curved upper surface 18 of internal layer 14, in a way similar to that of gluing inner surface 22 of outer layer 12 along the lower curved surfaces 20 of internal layer 14.
Perforated openings 34 are provided at regular intervals in upper layer 30, which allow liquid to flow through upper layer 30, and come in contact with exposed surfaces on fluted internal layer 14.
In an exemplary ~hn~i t, the regularly spaced openings 34 each Pn ~s two complete upper curved surfaces 18 of ridges 24.
These holes are spaced at a distance of 1/2 or 12.7 mm in a chenk~rhn~rd pattern. The top surface of upper layer 30 is coated with a moisture barrier coating 33 protecting the upper surface from liquid being absorbed through the top of layer 30. Thus, all liquid emanating from the product funnels through openings 34 in the upper surface of top layer 30, and is absorbed and trapped by internal layer 14 and the inner aurface of top layer 30, and held there without seeping through internal layer 14 by moisture coating barriers 27, 29 and 30.
Paperboard 10, by its construction, is stampable. To form a tray 300 therefrom, internal contoured layer 14 has glue applied to lower curved surfaces 20 and upper curved surfaces 18.
Outer layer 12, internal layer 14, and upper layer 30 are passed through rollers under a sufficient pressure to compress the three layers together to adhere them. As a result, lower curved surfaces 20 and upper curved surfaces 18 adhere to inner surfaces 22 and the lower surface of upper layer 30, respectively, and the pressure causes lower curved surfaces 24 and upper curved surfaces 18 to embed and become indented into inner surface 20 of outer layer 12 and the lower surface of top layer 30 by at least 0.1 mm (0.004 inches). In a preferred embodiment, the amount of indent (or r~ing) is 0.2 mm (0.008 inches). The high frequency of flutes Wo95l35204 2 1 9 3 3 8 6 r~l~s~
(16 per inch) and the corresponding increased number of ridges (24 across the upper surface of internal layer 14) causes the flats between curves 18 and 20 in each of the flute sets 28 to become more vertical, and this adds strength during compression so that the paperboard can be pressed and formed. Accordingly, by increasing the number of flutes 16, and hence the number of ridges 24, the ability of the corrugated paperboard to be pressed and formed consequently increases.
In one preferred embodiment of the present invention, triple-layer corrugated paperboard comprising a flat outer layer, and internal contoured layer comprising a flute repeat length to flute height ratio of 2.6, and an upper flat top layer with evenly spaced apertures therein is pressed and formed by introducing the three layer corrugated paperboard into a stamp and applying pressure and temperature for an amount of time such that the three-layer paperboard becomes pressed and formed to form a unitary tray.
The high frequency of flutes and ridges in the internal layer causes the triple-layer paperboard to be stamped by this method to form a satisfactory unitary structure such as a food tray.
Tray 300 is then formed as described above in connection with stamp 100 shown in FIG. 3.
FIG. 5 shows a corrugated paperboard tray, generally indicated as 300, made by the stamping process of the present invention. Tray 300 includes a base 312 and four upstanding angled side walls 314, 316, 318 and 320, integrally formed with base 312 along fold line 322 formed during stamping. In a preferred embodiment, these angled sidewalls are disposed at a predet~rm;n~
angle of 142~ to the base. Wall 314 is coupled to wall 316 along a curved wall 324 formed during stamping. Similarly, wall 316 is coupled to wall 318 by a curved wall 326, wall 318 is coupled to wall 320 by curved wall 328, and curved wall 320 is formed integrally with front side wall 314 by curved wall 330. Each of curved walls 324, 326, 328 and 330 are formed during stamping and easily could be formed as fold lines. Walls 314, 316, 318 and 320, as well as curved walls 334, 326, 328 and 330, are formed with a lip 332 at an acute angle with the respective walls.
W095/35~04 13 21 q3386 r~ s //~
As shown in FIG. 5, corrugated paperboard container 300 is formed from paperboard 10 including outer layer 12 to which is glued contoured internal layer 14 to which, in turn, is glued top layer 30, including moisture barrier layer 33, and evenly spaced circular apertures 31. Contoured interior layer 14 consists of flutes 16 which are formed by alternating upper 18 and lower 20 curved surfaces. In a preferred embodiment, the ratio of flute repeat length to flute height is 2.6 or less. Upon gluing the lower curved surfaces 20 of the internal layer 14 to the lower surface of outer layer 20, ridges 24 and grooves 26 are formed on the upper surface of internal layer 14. Upon gluing the lower surface of upper layer 30 to upper curved surfaces 18 of internal layer 24, ridges 24 and grooves 26 are partially covered by upper layer 30 in the portions not comprised of regularly spaced perforated openings 34.
The paperboard employed may be solid bleach sulfate (SBS) or chipboard, or a recycled paper or paperboard or container board material. In one '_~i t, outer flat layer 12 may be chipboard, internal layer 14 may be a recycled paperboard medium, and upper layer 30 may be chipboard. In a preferred embodiment, the outer layer 12 has a thickness 0.007 inches (7 points), internal contoured layer 14 has a thickness of 0.040 inches (40 points), and upper layer 30 has a thickness of 0.007 inches (7 points). The three layers together may have a working range from 35 to 70 points from the outer surface of layer 12 to the upper surface of =top layer 30. As a result, less paperboard is used and the container is light in weight.
During use, food is placed in the container. As ~uices or other fluids leak from the food, they fall through perforated openings 34 in top layer 30. The uncoated lower surface of top layer 30 and the upper surface of internal layer 14 absorb the liquid, removing it from the food. The liquid is retained in internal layer 14 and top layer 30 by moisture barriers 27, 29 and 30 so that tray 10 does not leak over time.
As shown in FIGS. 5 and 7, the internal surfaces of walls 312, 314, 316 are formed with upper layer 30 and circular apertures Wogs/35204 r~ "~
.
31 overlaying ridges having upper ridges 24 and grooves 26 between ridges 24. There are six to twelve ridges per inch, and in the preferred embodiment, there are nine ridges per inch. As shown more clearly in FIG. 5, the perforated upper layer 30 overlaying upper ridges 24 forms a moisture wicking, raised food receiving surface on which food is placed. Any moisture given off by the food within the tray is wicked away from the food through perforated openings 34 in top layer 30 and collected within grooves 26 of internal layer 14. In this manner, the collected moisture is not absorbed by the food, and tray 300 prevents the food from be~ ing soggy, or from spoiling by Le -ining in contact with this moisture. There is no longer a need for a liquid absorbing napkin.
The tray would operate in a similar manner if top layer 30 had no perforations and was not coated with a moisture proof barrier.
In a preferred embodiment, internal layer 14 is coated with a water-based coating prior to stamping. The coating is repulpable, recyclable and resists the penetration of moisture given off by food. This coating 29 is placed on the bottom o~
internal layer 14. As a result, the molded paperboard container maintains its strength and rigidity.
Also in a preferred ~mhotli t, a similar coating 33 is placed on the upper 5urface of upper layer 30. However, this layer is not applied to layer 30 where perforated openings 34 exist.
Thus, upper layer 30 becomes impenetrable to moisture, and all moisture is wicked away from the food in tray 300 through perforated openings 34 in upper layer 30.
Although the container formed by the process of this invention is shown to have a particular shape, it should be understood that the stamping process for corrugated paperboard can be used to form a corrugated container of any shape, such as round, square, rectangular or oval, as well as non-container structures such as trays or the like. Advantageously, as a result of the present invention, there is provided a method o~ stamping corrugated p~pt~rht~r~ having an internal contoured layer containing a high frequency of=flutes and a food container formed by the method of stamping corrugated paperboard, such food container being W09s/35204 2 1 9 3 3 8 6 1 ~
able to resist the penetration of moisture, is rigid and strong, is light in weight and collects moisture in troughs or grooves to prevent food from becoming soggy.
By forming paperboard having one layer consisting of 350 to 400 sets of flutes per linear meter of paperboard, a light weight container capable of being formed in a stamping process is provided. By uti1i7ing such high frequency fluted paperboard, and by moistening the paperboard and holding the paper taut prior to pressing and by pressing at a high pressure and high temperature during the cycle, a unitary construction formed of corrugated paperboard is obtainable.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
AND ~- ~TN~R NADE L~ ~U-.
BA~U~_.J OF THE l~v~l~. lU_.
The present invention relates to a method of forming corrugated pAr~rho~rd containers, including food containers and food trays and, in particular, employing corrugated paperboard in a novel stamping process, which rAr~rhoArd has an increased frequency of flutes in its internal layer, such that upon introducing the corrugated paperboard to the stamping process, the paperboard does not break apart and is capable of being molded t~o produce a satisfactory unitary structure.
Heretofore, to produce unitary paperboard containers without gluing, manufacturers have attempted to stamp certain types of corrugated paperboard, such as E-flute corrugated paperboard, and have been unable to create a satisfactory unitary construction.
Efforts at stamping corrugated paperboard resulted in the paperboard breaking up during the stamping process and have failed to achieve a utilitarian molded unitary structure.
Accordingly, the use of corrugated paperboard for containers has been limited to an expensive multi-step manufacturing process in which the r~p~rhQArd must first be printed, then die cut and then passed through complex box folding machinery. Accordingly, a corrugated paperboard that would permit pressing and forming (stamping) into a container and a method of pressing and forming corrugated paperboard container would be desirable.
SUMMARY OF THE lhv~lluN
Generally speaking, in accordance with the instant invention, a method of forming a unitary container from corrugated paperboard is provided. The method comprises introducing corrugated paperboard having an outer flat layer of paperboard and an internal contoured layer of paperboard having a high frequency, per linear meter of paperboard, of flutes formed from alternating upper and lower curved surfaces into a die press and pressing the pAp~rhoArd between a die and a cavity to apply pressure to the Wo9S/3~204 2 1 9 3 3 8 6 P~ 1/ L ~. / /~
paperbo~rd. Applying heat to the paper~oard simultaneously with the application of pressure.
In a second type of container a three-layered corrugated paperboard tray is provided. The paperboard is formed of a first layer of corrugated paper, a second layer of industrial strength paper, and a third layer of paper having holes formed therein, the corrugated layer being sandwiched between the second layer and third layer. The top paper layer comprises a sheet of paper having a plurality of holes therein resting on the fluted crests of the corrugated layer. The upper surface of the top perforated layer is moisture resistant. The underside of the fluted layer and the bottom layer of the corrugated construction have moisture-resistant barriers to prevent leaking through the entire tray.
Accordingly, it is an object of this invention to provide an improved method for forming a unitary container of corrugated paper.
Another ob~ect of the invention is to form a container from corrugated paper by stamping, without the need for a complex box folding machinery or the need for die cutting.
Yet another object of the invention is to form a unitary box from single face or single ply corrugated paper.
A further object of the invention is to provide a container made out o~ lighter, cheaper and recyclable materials.
Still another object of the invention to provide a method for forming complex shapes by pressing and forming paperboard.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
WO95l35204 2 1 9 3 3 8 6 1~.,. "~
~ 3 BRIFF DFSCRIPTION OF T~F DRAWINGS
For a fuller understanding of the invention, reference is had to the following description, taken in connection with the accompanying drawings, in which:
FIG. 1 is a partial perspective view of the paperboard utilized in connection with the invention;
~ FIG. 2 is a front elevated view of the paperboard constructed in accordance with the invention;
PIG. 3 is a sectional view of stamp used in connection with the method of the invention;
FIG. 4 i5 a perspective view of a container constructed in accordance with the invention;
FIG. 5 is a perspective view of the pAr~rho~rd food tray constructed in accordance with another ~ of the present invention;
FIG. 6 is a partial top plan view of a paperboard utilized in connection with the present invention; and FIG. 7 is a cross-sectional view taken along line 3-3 of FIG. 5 of the paperboard utilized in connection with the present invention.
n~ATT.T~n D~SCRIPTION OF T~ ~K~KK~ h~u~L~
An example of corrugated paper used to form applicant~s box is disclosed in U.S. Patent No. 4,931,346 which is incorporated herein by reference. Reference is made to FIGS. 1 and 2, wherein a paperboard, capable of being pressed and formed (stamped), generally indicated as 10, comprising two layers is depicted. An outer layer 12 is flat p~p~rho~rd having a thickness in the range of 0.3 mm to l.S mm.
An internal layer, generally indicated as 14, of paperboard 10 is contoured, having a thickness in the range of 0.23 mm to 0.5 mm. The internal contoured layer 14 consists of flutes 16, each flute being formed by one of an alternating upper 18 or lower 20 curved surface. Internal layer 14 is glued to an inner surface 22 of the outer layer 12 along the lower curved surfaces 20. Gluing the lower curved surfaces 20 of the internal layer 14 W095135204 2 1 9 3 3 8 6 ~ , "~
.
to the inner surface 20 of the outer layer 12 allows for the formation of exposed ridges 24 and grooves 26 (FIG. 2) across the unattached surface of internal layer 14. Internal layer 14 has a high frequency (flutes/meter) of flutes 16 and a corresponding high frequency of ridges 24 on the exposed surface of internal layer 14 allowing the paperboard 10 to be pressed into a unitary structure.
One upper curved surface 18 and an alternating lower curved surface 20 make up one set of ~1utes 28. Each flute 16 has a height in the range of 0.9 mm to 1.2 mm or 0.035 inches to 0.047 Lnches, and sets of flutes 28 in the internal layer 14 have frequency within the range of 350-400 sets of flute 26 per linear meter of paperboard 10. In an exemplary embodiment, the number of sets of flutes is 375 per linear meter of paperboard, the flute repeat length to flute height ratio is 2.6 or less, and the coLl~s~"ding number of ridges on the top surface of the internal layer is 6 to 12 ridges per inch.
In producing the stampable p~r~rho~rd 10, internal contoured layer 14 has glue applied to the lower curved surfaces 20. Outer layer 12 and internal layer 14 are passed through rollers under a sufficient pressure to compress the two layers together to adhere them. As a result, lower curved surfaces 20 adhere to inner surface 22 of the outer layer 12 and the pressure causes the lower curved surfaces 24 to imbed and become indented into inner surface 20 of outer layer 12 by at least 0.1 mm (0.004 inches). In the preferred ~ ~ t, the amount of indent (or imh~ing) is 0.2mm (0.008"). The high frequency of flutes 16 per inch, and, hence, the colla~u.lding increased number of ridges 24 across the unattached surface of the internal layer 14, causes the flats (between curves 18 and 20) in each of the flute sets 28 to become more vertical and this adds strength during ~ ~saion so that the paperboard can be pressed and formed. Accordingly, by increasing the number of flutes 16, and hence the number of ridges 24, the ability of the corrugated paperboard to be pressed and formed consequently increases.
The flutes in the stampable paperboard have a higher frequency and higher amplitude when compared with other fluted 2 1 9 3 3 8 ~ PCTNS95/07722 .
paper. This maximizes the ratio of flute repeat length to flute height. Because of the more vertical flute rise at the midpoint between flute tips there is a greater rate of change of height over distance so that for a given height of flute rise, the corrugated paperboard will have a smaller repeat ratio when compared to E-flute or E-flute, by way of example, and for a given repeat ratio the described paperboard will have a higher amplitude than E-flute or F-flute corrugated paperboard. In the preferred embodiment the stampable corrugated paperboard has a flute repeat length to flute height ratio of 2.6, whereas in E-flute or F-flute, the flute repeat length to flute height ratio is 2.8.
It is the high frequency of flutes per inch in the corrugation that specifically allows the paperboard to be molded by the dye pressing method described in detail below. Unlike attempting to mold corrugated paperboard of the prior art, which paperboard does not have such high density fluting in the corrugation and consequently breaks up in the molding process, the corrugated paperboard described above does not break up in the molding/stamping process and, instead, is able to be molded into a unitary structure. This ability to mold the corrugated paperboard into a unitary structure is spec;~ie~lly due to the high density of fluting in the corrugation.
In one preferred ~'i t of the present invention, single-face corrugated paperboard comprising a flat outer layer and an internal contoured layer comprising a flute repeat length to flute height ratio of 2.6 is pressed and formed by introducing the single-face corrugated paperboard into a stamp and applying pressure and temperature for an amount of time such that the corrugated paperboard becomes pressed and formed to form a unitary container. ~he high frequency of flutes and ridges in the internal layer cause the single face paperboard to be stamped by this method to form a satisfactory unitary structure such as a container.
Reference is now made to FIG. 3 which is a stamp used in conjunction with the method for stamping the corrugated paper as shown. In an exemplary embodiment of the method, it is important that the p~p~rh~rd be flexible and easily deformed without W095/3~204 2 1 9 3 3 8 b PCT~S95/07722 .
fracturing or rr~rking Accordingly, in a first step moisture is added to the paperboard to soften the fibers. Moisture is added until the moisture level of each sheet is 8 to 11%, however, it is best to run as close to the lower end of this range in an exemplary embodiment to prevent excessive moisture forming steam beneath any coating applied to the paperboard in the forming process causing the coating to blister. However, the deeper the stamping the higher moisture content required. An additive such as fluorocarbon is added to the moistening process to achieve about a 1~ solution in water. The additive assists in water retention, aids forming and reduces grease wicking in the final process.
The moisture and fluorocarbon applied to the paperboard does not immediately penetrate the sheet so that the sheet remains stiff and difficult to form at first. Additionally, latent moisture may still be laying on top of the sheet, having not been absorbed by the fibers, therefore in an exemplary ~mho~i t, the paperboard sits for forty-eight to seventy-two hours before forming, allowing the board to reach equilibrium and to obtain a more uniform distribution of moisture throughout the cro8s-section of the sheet.
The r~r~rho~rd is deep drawn utilizing a stamp, generally indicated as 100. The stamp includes a bolster plate 102 upon which is seated a heated female cavity 104. A plunger is slidably mounted on bolster plate 102 to move into and out of heated female cavity 104.
A top die mounting plate 108 slidably supports a reciprocating platen 110. Platen 110 is attached to a male die 112. Male die 112 moves towards and is received in heated female cavity 104 with the reciprocating motion of platen 110. A draw ring 114 is mounted about male die 112 for positing paperboard prior to stamping.
The method of pressing or stamping the paperboard consist of the basic steps of feeding the paperboard, creasing the paperboard, cutting the paperboard and forming the paperboard. The moistened paperboard is creased in an area where corners will be formed while the r~r~rhoard blank is formed in a web. The web is w095/35204 2 1 933 86 P~ ' "~
.
then advanced a predet~rm; n~ amount centering the creased paperboard between male die 112 and heated female cavity 104.
Reciprocating platen 110 pushes male die 112 through the die cavity 104, shearing the registered pre-creased paperboard from the in~r of the web and urging it to fall through the die creating the blank. The pre-creased cut blank falls through and is centered between male die 112 and draw ring 114 and heated female cavity 114 mounted on bolster plate 102.
Draw ring 114 is extended and contacts the paperboard, tensioning the paperboard as male die 112 descends pushing the paperboard into female cavity 104. The draw ring holds the board tightly against the rim of the female cavity to discourage wrinkles from forming on the side panels of the container as it i8 being drawn. The draw ring 114 further forces excess paper into the corners and insures that neat, even folds are made, following the pre-creased lines. The more tension applied to the paperboard during forming, the neater the folds and fewer wrinkles formed on the side panels.
Once all of the paperboard has been drawn into the heated cavity, the press extends the male die slightly, depressing the female cavity 104 and bolster plate 102 by 1/30 seconds of an inch holding the tray under pressure and heat. In an exemplary ~mhn~i t, the pressure applied is approximately four tons at 120~E. This allows the moisture in the board to turn into steam and escape through vents provided in the die, setting the paperboard in the shape of the die. Essentially, the folds in the corners are steam ironed into the form of the container, imparting a structural integrity to the container.
The stamp (press) is then opened and plunger 106 is activated entering female cavity 104 e~ecting the container from the heated female cavity. The excess paper is then trimmed from the formed container.
FIG. 4 shows a corrugated paperboard container, generally indicated as 200, made by the stamping process of the present invention. The container has a clam shell construction and includes a lower compartment 210 for receiving food and the like W095~s204 21 933 8 6 - r~
and an upper compartment 240 for covering and closing the container. Lower compartment 210 includes a base 212 and four upstanding sidewalls 214, 216, 218 and 220, integrally formed with base 212 along fold line 222 formed during stamping. Wall 214 is coupled to wall 216 along a curve at connecting wall 224 formed during stamping. Similarly, wall 216 is coupled to wall 218 by a curved wall 226, wall 218 is coupled to wall 220 by curved wall 228 and curved wall 220 is formed integrally with front wall 214 by a curved w211 230. Each of curved walls 224, 226, 228, 230 are formed during stamping and easily could be formed as fold lines.
Wall 214 is formed with a lip 232 at an acute angle with wall 214 and having slot 234 formed therein.
Upper compartment 240 is similar in construction to lower compartment 210 and includes a top wall 242 and side walls 244, 246, 248 and 250, each of walls 244, 246, 248 and 250 are coupled to top wall 242 along a fold line 252 formed during stamping. Side walls 244, 246, 248 and 250 are also integrally coupled, each ad~acent sidewall by a respective curved wall 254, 256, 258 and 260. Side wall 248 of upper compartment 240 and side wall 218 of lower compartment 210 are pivotably coupled together by a hinge 262 formed as a fold line between lower compartment 210 and upper compartment 240 during the stamping process. ~pper compartment 240 rotates about hinge 262 in the direction of arrow A to close container 200 upon itself.
Side wall 244 is also formed with a lip 264 having a tab 266 formed thereon. Tab 266 is received within slot 234 to fa8ten upper cl ~~t 240 to lower component 210.
In a preferred embodiment, bottom compartment is formed with a receiving lip adapted to receive a lip about upper compartment 240 to further seal in a mating relationship, container 200.
As shown in FIG. 4, upper compartment 240 and lower compartment 210 are each formed from paperboard 10 including outer layer 12 to which is glued one contoured internal layer 14.
Contoured interior layer 14 consists of flutes 16 which are formed by alternating upper 18 and lower 20 curved surfaces. In a W09sl3s204 2 ~ 9 3 3 8 6 ~ ~I/U~
~ 9 preferred embodiment the ratio of flute repeat length to flute height is 2.6 or less. Upon gluing the lower curved surfaces 20 of the internal layer 14 to the inner surface of outer layer 20 ridges 24 and grooves 26 are formed on the outer surface of the internal layer 14.
The paperboard employed may be solid bleached sulfate (SBS) or rhirhn~rd, or a recycled material. In one ~mhn~i t, outer flat layer 12 may be chipboard, and internal layer 14 may be a recycled paperboard medium. In a preferred embodiment, the outer layer 12 has a thickness of 0.007 inches (7 points) and internal contoured layer 14 has a thickness of 0.040 inches (40 points).
The two layers together may have a working range from 30 to 60 points from the outer surface of outer layer 12 to the ridged top of internal layer 14. As a result, less paperboard is used, the container is light in weight, and although the container maintains its strength and rigidity as if layers were solid paperboard, it, at the same time, possesses the capability of becoming stamped.
As shown, the internal surfaces of walls 212, 214, 216 and 218 as well as 242, 244, 246 and 258 of compartments 210 and 240 are formed with ridges having upper ridges 24 and grooves 26 between ridges 24. There are 6 to 12 ridges per inch, and, in a preferred embodiment, there are 9 ridges per inch. As shown more clearly in FIG. 4, the upper ridges 24 of bottom wall 212 form a raised food-receiving surface on which the food is placed. Any moisture given off by the hot food within the container is received and collected within grooves 26. In this manner, the collected moisture is not absorbed by the food, and container 200 prevents the food from becoming soggy.
In a preferred embodiment, internal layer 14 is coated with a water-based coating prior to stamping. The coating is repulpable, recyclable, and resists the penetration of moisture given off by the hot food. As a result, the molded paperboard container maintains its strength and rigidity.
Reference is made to FIGS. 5 and 6 wherein a portion of a laminated paperboard 10 utilized in constructing a food tray 300, comprising three layers in accordance with another ~mho~i t of Wo95/35204 2 1 9 3 3 8 6 PCTNS95/07722 the invention is depicted. Two of the layers are similar in construction to the paperboard described above, the difference being the addition of a waterproof barrier. Like numerals are utilized to identify like structures.
A first outer layer 12 is flat paperboard having a thickness in the range .15 mm to 1.0 mm. An internal layer generally indicated as 14 of paperboard 10 is contoured, having a thickness in the range of .15 mm to .25 mm. Internal contoured layer 14 consists of flutes 16, each flute being formed by one of an alternating upper 18 or lower 20 curved surface. Internal layer 14 is glued to an inner surface 22 of the outer layer 12 along the lower curved surfaces 20. Gluing the lower curved surfaces 20 of the internal layer 14 to the inner surface 22 of the outer layer 12 allows for the formation of exposed ridges 24 and grooves 26 across the upper surface of internal layer 14. Internal layer 14 has a high-frequency (flutes/meter) of flutes 16 and the corresponding high frequency of ridges 24 in the upper surface of internal layer 14.
A moisture barrier coating 27 is provided on upper surface 22 of outer barrier layer 12. A similar moisture barrier (not shown) coating 29 is provided on the bottom surface of internal layer 14. The top surface of layer 14 is uncoated and therefore absorbs moisture coming in contact therewith. Barrier coatings 27, 29 create a moisture barrier which retains moisture captured by internal layer 14 within layer 14, and protects the tray from leakage.
One upper curved surface 18 and an alternating lower curved surface 20 make up one set of flutes 28. Each flute 16 has a height in the range of 0.9 mm to 1.2 mm or 0.35 inches to 0.047 inches, and sets of flutes 28 in the internal layer 14 have frequency within the range of 350-400 sets of flute 26 per linear meter of paperboard 10. In an exemplary : ' ~i t, the number of sets of flutes is 375 per linear meter of paperboard, the flute repeat length to flute height ratio is 2.6 or less, and the corresponding number of ridges on the upper surface of internal layer 14 is 6 to 12 ridges per inch. The high flute frequency w095~5204 2 l q3386 r~ "~2 provides a greater exposed layer surface per meter increasing the area of absorbing surfaces in layer 14.
Perforated top layer 30 is provided above internal layer 14. Layer 14 has a thickness and construction similar to that of outer layer 12. However, perforated openings 34 are provided uniformly on the surface of layer 30. Top layer 30 is glued at an inner surface to curved upper surface 18 of internal layer 14, in a way similar to that of gluing inner surface 22 of outer layer 12 along the lower curved surfaces 20 of internal layer 14.
Perforated openings 34 are provided at regular intervals in upper layer 30, which allow liquid to flow through upper layer 30, and come in contact with exposed surfaces on fluted internal layer 14.
In an exemplary ~hn~i t, the regularly spaced openings 34 each Pn ~s two complete upper curved surfaces 18 of ridges 24.
These holes are spaced at a distance of 1/2 or 12.7 mm in a chenk~rhn~rd pattern. The top surface of upper layer 30 is coated with a moisture barrier coating 33 protecting the upper surface from liquid being absorbed through the top of layer 30. Thus, all liquid emanating from the product funnels through openings 34 in the upper surface of top layer 30, and is absorbed and trapped by internal layer 14 and the inner aurface of top layer 30, and held there without seeping through internal layer 14 by moisture coating barriers 27, 29 and 30.
Paperboard 10, by its construction, is stampable. To form a tray 300 therefrom, internal contoured layer 14 has glue applied to lower curved surfaces 20 and upper curved surfaces 18.
Outer layer 12, internal layer 14, and upper layer 30 are passed through rollers under a sufficient pressure to compress the three layers together to adhere them. As a result, lower curved surfaces 20 and upper curved surfaces 18 adhere to inner surfaces 22 and the lower surface of upper layer 30, respectively, and the pressure causes lower curved surfaces 24 and upper curved surfaces 18 to embed and become indented into inner surface 20 of outer layer 12 and the lower surface of top layer 30 by at least 0.1 mm (0.004 inches). In a preferred embodiment, the amount of indent (or r~ing) is 0.2 mm (0.008 inches). The high frequency of flutes Wo95l35204 2 1 9 3 3 8 6 r~l~s~
(16 per inch) and the corresponding increased number of ridges (24 across the upper surface of internal layer 14) causes the flats between curves 18 and 20 in each of the flute sets 28 to become more vertical, and this adds strength during compression so that the paperboard can be pressed and formed. Accordingly, by increasing the number of flutes 16, and hence the number of ridges 24, the ability of the corrugated paperboard to be pressed and formed consequently increases.
In one preferred embodiment of the present invention, triple-layer corrugated paperboard comprising a flat outer layer, and internal contoured layer comprising a flute repeat length to flute height ratio of 2.6, and an upper flat top layer with evenly spaced apertures therein is pressed and formed by introducing the three layer corrugated paperboard into a stamp and applying pressure and temperature for an amount of time such that the three-layer paperboard becomes pressed and formed to form a unitary tray.
The high frequency of flutes and ridges in the internal layer causes the triple-layer paperboard to be stamped by this method to form a satisfactory unitary structure such as a food tray.
Tray 300 is then formed as described above in connection with stamp 100 shown in FIG. 3.
FIG. 5 shows a corrugated paperboard tray, generally indicated as 300, made by the stamping process of the present invention. Tray 300 includes a base 312 and four upstanding angled side walls 314, 316, 318 and 320, integrally formed with base 312 along fold line 322 formed during stamping. In a preferred embodiment, these angled sidewalls are disposed at a predet~rm;n~
angle of 142~ to the base. Wall 314 is coupled to wall 316 along a curved wall 324 formed during stamping. Similarly, wall 316 is coupled to wall 318 by a curved wall 326, wall 318 is coupled to wall 320 by curved wall 328, and curved wall 320 is formed integrally with front side wall 314 by curved wall 330. Each of curved walls 324, 326, 328 and 330 are formed during stamping and easily could be formed as fold lines. Walls 314, 316, 318 and 320, as well as curved walls 334, 326, 328 and 330, are formed with a lip 332 at an acute angle with the respective walls.
W095/35~04 13 21 q3386 r~ s //~
As shown in FIG. 5, corrugated paperboard container 300 is formed from paperboard 10 including outer layer 12 to which is glued contoured internal layer 14 to which, in turn, is glued top layer 30, including moisture barrier layer 33, and evenly spaced circular apertures 31. Contoured interior layer 14 consists of flutes 16 which are formed by alternating upper 18 and lower 20 curved surfaces. In a preferred embodiment, the ratio of flute repeat length to flute height is 2.6 or less. Upon gluing the lower curved surfaces 20 of the internal layer 14 to the lower surface of outer layer 20, ridges 24 and grooves 26 are formed on the upper surface of internal layer 14. Upon gluing the lower surface of upper layer 30 to upper curved surfaces 18 of internal layer 24, ridges 24 and grooves 26 are partially covered by upper layer 30 in the portions not comprised of regularly spaced perforated openings 34.
The paperboard employed may be solid bleach sulfate (SBS) or chipboard, or a recycled paper or paperboard or container board material. In one '_~i t, outer flat layer 12 may be chipboard, internal layer 14 may be a recycled paperboard medium, and upper layer 30 may be chipboard. In a preferred embodiment, the outer layer 12 has a thickness 0.007 inches (7 points), internal contoured layer 14 has a thickness of 0.040 inches (40 points), and upper layer 30 has a thickness of 0.007 inches (7 points). The three layers together may have a working range from 35 to 70 points from the outer surface of layer 12 to the upper surface of =top layer 30. As a result, less paperboard is used and the container is light in weight.
During use, food is placed in the container. As ~uices or other fluids leak from the food, they fall through perforated openings 34 in top layer 30. The uncoated lower surface of top layer 30 and the upper surface of internal layer 14 absorb the liquid, removing it from the food. The liquid is retained in internal layer 14 and top layer 30 by moisture barriers 27, 29 and 30 so that tray 10 does not leak over time.
As shown in FIGS. 5 and 7, the internal surfaces of walls 312, 314, 316 are formed with upper layer 30 and circular apertures Wogs/35204 r~ "~
.
31 overlaying ridges having upper ridges 24 and grooves 26 between ridges 24. There are six to twelve ridges per inch, and in the preferred embodiment, there are nine ridges per inch. As shown more clearly in FIG. 5, the perforated upper layer 30 overlaying upper ridges 24 forms a moisture wicking, raised food receiving surface on which food is placed. Any moisture given off by the food within the tray is wicked away from the food through perforated openings 34 in top layer 30 and collected within grooves 26 of internal layer 14. In this manner, the collected moisture is not absorbed by the food, and tray 300 prevents the food from be~ ing soggy, or from spoiling by Le -ining in contact with this moisture. There is no longer a need for a liquid absorbing napkin.
The tray would operate in a similar manner if top layer 30 had no perforations and was not coated with a moisture proof barrier.
In a preferred embodiment, internal layer 14 is coated with a water-based coating prior to stamping. The coating is repulpable, recyclable and resists the penetration of moisture given off by food. This coating 29 is placed on the bottom o~
internal layer 14. As a result, the molded paperboard container maintains its strength and rigidity.
Also in a preferred ~mhotli t, a similar coating 33 is placed on the upper 5urface of upper layer 30. However, this layer is not applied to layer 30 where perforated openings 34 exist.
Thus, upper layer 30 becomes impenetrable to moisture, and all moisture is wicked away from the food in tray 300 through perforated openings 34 in upper layer 30.
Although the container formed by the process of this invention is shown to have a particular shape, it should be understood that the stamping process for corrugated paperboard can be used to form a corrugated container of any shape, such as round, square, rectangular or oval, as well as non-container structures such as trays or the like. Advantageously, as a result of the present invention, there is provided a method o~ stamping corrugated p~pt~rht~r~ having an internal contoured layer containing a high frequency of=flutes and a food container formed by the method of stamping corrugated paperboard, such food container being W09s/35204 2 1 9 3 3 8 6 1 ~
able to resist the penetration of moisture, is rigid and strong, is light in weight and collects moisture in troughs or grooves to prevent food from becoming soggy.
By forming paperboard having one layer consisting of 350 to 400 sets of flutes per linear meter of paperboard, a light weight container capable of being formed in a stamping process is provided. By uti1i7ing such high frequency fluted paperboard, and by moistening the paperboard and holding the paper taut prior to pressing and by pressing at a high pressure and high temperature during the cycle, a unitary construction formed of corrugated paperboard is obtainable.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
Claims
16 WHAT IS CLAIMED IS:
1 . A method for molding a corrugated paperboard container having a first layer of flat paperboard to which is attached a second layer of contoured paperboard, said contoured layer having a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, said forming method comprising, placing said corrugated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed; pressing said paperboard between said die and said cavity to apply a pressure to said paperboard; providing moisture to said paperboard applying heat to said paperboard simultaneously with said application of pressure; and removing said die from said cavity, said paperboard having folds therein and said heat applied to said paperboard creating steam within said cavity to steam iron said folds to form a container and provide structural integrity.
2. The method of claim 1, wherein the flute repeat length to flute height ratio is no greater than 2.6.
3. The method of claim 1, wherein the first layer of paperboard has a thickness in the range of 0.3 mm to 1.5 mm.
4. The method of claim 1, wherein the contoured layer of paperboard has a thickness in the range of 0.23 mm to 0.5 mm.
5. The method of claim 1, further comprising the step of creasing said paperboard prior to placing said paperboard into said stamping die.
6. The paperboard of claim 6, wherein the amount of moisture added is substantially within the range of 3% to 11% by weight.
7. The method of claim 1, further comprising the step of ejecting said paperboard from said cavity after said die has been removed.
8. The method of claim 1, further comprising the step of coating at least one layer of said paperboard prior to placing said paperboard into said die.
9. The method of claim 9, wherein said stamping die includes a draw ring and further comprising the step of tensioning said paperboard while said paperboard is pressed between said die and said cavity.
10. The method of claim 1, wherein said pressure is substantially four tons.
11. The method of claim 1, wherein said heat is applied at a temperature of substantially 120°F.
12. A method for molding a corrugated paperboard container having a first layer of flat paperboard to which is attached a second layer of contoured paperboard, said contoured layer having a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, the first layer of paperboard having a thickness in the range of 0.3 mm to 1.5 mm, and the contoured layer of paperboard having a thickness in the range of 0.23 mm to 0.5 mm, said forming method comprising, the step of coating at least one layer of said paperboard;
providing moisture to said paperboard, the amount of moisture added is substantially within the range of 3% to 11% by weight and creasing said paperboard; placing said corrugated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed said stamping die including a draw ring; pressing said paperboard between said die and said cavity to apply substantially four tons of pressure to said paperboard; applying heat to said paperboard simultaneously with said application of pressure; tensioning said paperboard while said paperboard is pressed between said die and said cavity; said paperboard having folds therein and said heat applied to said paperboard creating steam within said cavity to steam iron said folds to form a container and provide structural integrity; removing said die from said cavity; and ejecting said paperboard from said cavity after said die has been removed.
13. The method of claim 13, wherein the flute repeat length to flute height ratio is no greater than 2.6.
14. A method of producing a single-faced corrugated paperboard which is adaptable to be molded into a container comprising gluing a first flat layer of paperboard having a thickness in the range of 0.3 mm to 1.5 mm to a contoured layer of paperboard, said contoured layer having a thickness in the range of 0.23 mm to 0.5 mm, said contoured layer forming 350 to 400 sets of flutes per linear meter of paperboard, each flute being formed as alternating upper and lower curved surfaces in the contoured layer with each flute having a height in the range of 0.9 mm to 1.2 mm, the flute rise being substantially vertical at the midpoint between the upper and lower curved surfaces, applying glue to each lower curved surface of the contoured layer; passing said first layer and second layer through rollers, and applying a sufficient pressure to press said first and second layers together to adhere them, forming ridges and grooves in said contoured layer, the lower curved surfaces of said contoured layer being indented within said first layer by at least 0.1 mm, increasing the area of surface contact and gluing area between said first and second layers, said second layer having 6-12 ridges per inch.
15. The method of claim 15, wherein the flute repeat length to flute height ratio is no greater than 2.6.
16. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch.
17. The container of claim 16, wherein the contoured layer has a flute repeat length to flute height ratio no greater than 2.6.
18. The container of claim 16, wherein the upper edges of said ridges form receiving surfaces on which an object received by said container rests, and grooves formed between said ridges for receiving and collecting moisture given off by said object.
19. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means, said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch;
the upper edges of said ridges form receiving surfaces on which an object received by said container rests, and grooves formed between said ridges for receiving and collecting moisture given off by said object; and said ridges are coated with a recyclable coating adapted to resist penetration of moisture.
20. The container of claim 18, wherein the paperboard of said upper and lower compartments has a thickness in the range of 0.030 inches to 0.060 inches.21. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch; and said ridged surfaces are coated with a coating to resist penetration of moisture.
22. The container in accordance with claim 16, wherein said upper and lower compartments each have four sidewalls.
23. The container as claimed in claim 16, wherein said hinge means is formed of perforated paperboard.
24. The container as claimed in claim 16, further comprising fastening means for releasably fastening said lower compartment to said upper compartment.25. The container as claimed in claim 16, wherein said fastening means includes a tab formed on said first compartment and a slit formed on said secondcompartment for receiving said tab.
26. The container as claimed in claim 21, wherein said coating is a water based coating.
27. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch;
the paperboard has a thickness in the range of 0.040 inches to 0.050 inches.
28. A laminated paperboard, comprising:
a layer of paperboard;
a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said first layer along said plurality of said lower curved surfaces of said second fluted layer;
a second layer of paperboard coupled with said second fluted layer along said plurality of said upper curved surfaces of said second fluted layer; and the second layer of paperboard is perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer.
29. The laminated paperboard of claim 28, wherein a moisture barrier layer is provided on the upper surface of said layer of paperboard.
30. The laminated paperboard of claim 1, wherein a moisture barrier layer is provided on the lower surface of said fluted layer of paperboard.
31. The laminated paperboard of claim 1, wherein the flute repeat length to flute height ratio of the fluted layer is 2.6 or less.
32. The laminated paperboard of claim 29, wherein a moisture barrier layer is provided on the upper surface of said second layer of paperboard.
33. A laminated paperboard, comprising:
a layer of paperboard;
a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said first layer along said plurality of said lower curved surfaces of said second fluted layer;
a second layer of paperboard coupled with said second fluted layer along said plurality of said upper curved surfaces of said second fluted layer; and the second layer of paperboard is perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer;
the second layer of paperboard being perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer;
each of said plurality of openings provided in said perforated layer of paperboard is dimensioned to have a diameter equal to the width of between two and three of said plurality of said upper curved surfaces.
34. The laminated paperboard of claim 29, wherein said plurality of openings provided in said perforated layer of paperboard are arranged in a checkerboard pattern.
35. A method for forming a laminated paperboard, comprising the steps of:
providing a layer of paperboard;
providing a fluted layer of paperboard having a plurality of upper and lower curved surfaces;
positioning said fluted layer of paperboard above and in contact with said first layer of paperboard;
providing a perforated layer of paperboard;
positioning said perforated layer of paperboard above and in contact with said fluted layer of paperboard; and coupling said fluted layer of paperboard with said perforated layer of paperboard and with said layer of paperboard.
36. The method of claim 35, further comprising the step of providing a moisture barrier on the upper surface of said layer of paperboard before positioning said fluted layer of paperboard above and in contact with said layer of paperboard.
37. The method of claim 35, further comprising the step of providing a moisture barrier on the lower surface of said fluted layer of paperboard before positioning said fluted layer of paperboard above and in contact with said layer of paperboard.
38. The method of claim 35, further comprising the step of providing a moisture barrier on the upper surface of said perforated layer of paperboard before positioning said perforated layer of paperboard above and in contact with said fluted layer of paperboard.
39. A laminated paperboard tray, comprising:
a base;
angled sidewalls being formed integrally with said bottom surface and set at a predetermined angle thereto;
curved walls being formed integrally with said angled sidewalls for connecting said angled sidewalls; and a lip being formed integrally with said angled sidewalls and said connecting walls and positioned thereabove;
said base, said angled sidewalls, said curved walls and said lip being formed of laminated paperboard, said paperboard having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer of paperboard and a perforated layer of paperboard coupled with said fluted layer of paperboard along said plurality of said upper curved surfaces of said fluted layer of paperboard.
40. The laminated paperboard tray of claim 39, wherein said upper curved surfaces are moisture absorbent, so that said upper curved surfaces absorb moisture given off by said object.
41. The laminated paperboard tray of claim 39, further comprising a moisture barrier disposed on the upper surface of said layer of paperboard.
42. The laminated paperboard tray of claim 39, further comprising a moisture barrier layer disposed on the lower surface of said fluted layer of paperboard.
43. The laminated paperboard tray of claim 39, further comprising a moisture barrier layer disposed on the upper surface of said perforated layer of paperboard.
44. A method for forming a laminated paperboard tray having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer and a perforated layer of paperboard having a plurality of openings therein coupled with said fluted layer along said plurality of said upper curved surfaces of said fluted layer, comprising the steps of:
placing said laminated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed;
pressing said paperboard between said die and said cavity to apply a pressure to said paperboard;
applying heat to said paperboard simultaneously with said application of pressure to affix said perforated layer to said fluted layer to permit fluid communication therebetween; and removing said die from said cavity.
45. The method of claim 44, further comprising the step of creasing said paperboard prior to placing said paperboard into said die.
46. The method of claim 44, further comprising the step of providing moisture to said paperboard before placing said paperboard into said stamping die.
47. The method of claim 46, wherein the amount of moisture added is substantially within the range of 3% to 11% by weight.
48. The method of claim 44, further comprising the step of ejecting said paperboard from said cavity after said die has been removed.
49. A method for forming a laminated paperboard tray having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer and a perforated layer of paperboard having a plurality of openings therein coupled with said fluted layer along said plurality of said upper curved surfaces of said fluted layer, comprising the steps of:
placing said laminated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed;
pressing said paperboard between said die and said cavity to apply a pressure to said paperboard;
applying heat to said paperboard simultaneously with said application of pressure to affix said perforated layer to said fluted layer to permit fluid communication therebetween;
removing said die from said cavity; and of coating at least one layer of said paperboard with a moisture barrier layer prior to placing said paperboard into said die.
50. The method of claim 44, wherein said stamping die includes a draw ring and further comprising the step of tensioning said paperboard while said paperboard is pressed between said die and said cavity.
1 . A method for molding a corrugated paperboard container having a first layer of flat paperboard to which is attached a second layer of contoured paperboard, said contoured layer having a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, said forming method comprising, placing said corrugated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed; pressing said paperboard between said die and said cavity to apply a pressure to said paperboard; providing moisture to said paperboard applying heat to said paperboard simultaneously with said application of pressure; and removing said die from said cavity, said paperboard having folds therein and said heat applied to said paperboard creating steam within said cavity to steam iron said folds to form a container and provide structural integrity.
2. The method of claim 1, wherein the flute repeat length to flute height ratio is no greater than 2.6.
3. The method of claim 1, wherein the first layer of paperboard has a thickness in the range of 0.3 mm to 1.5 mm.
4. The method of claim 1, wherein the contoured layer of paperboard has a thickness in the range of 0.23 mm to 0.5 mm.
5. The method of claim 1, further comprising the step of creasing said paperboard prior to placing said paperboard into said stamping die.
6. The paperboard of claim 6, wherein the amount of moisture added is substantially within the range of 3% to 11% by weight.
7. The method of claim 1, further comprising the step of ejecting said paperboard from said cavity after said die has been removed.
8. The method of claim 1, further comprising the step of coating at least one layer of said paperboard prior to placing said paperboard into said die.
9. The method of claim 9, wherein said stamping die includes a draw ring and further comprising the step of tensioning said paperboard while said paperboard is pressed between said die and said cavity.
10. The method of claim 1, wherein said pressure is substantially four tons.
11. The method of claim 1, wherein said heat is applied at a temperature of substantially 120°F.
12. A method for molding a corrugated paperboard container having a first layer of flat paperboard to which is attached a second layer of contoured paperboard, said contoured layer having a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, the first layer of paperboard having a thickness in the range of 0.3 mm to 1.5 mm, and the contoured layer of paperboard having a thickness in the range of 0.23 mm to 0.5 mm, said forming method comprising, the step of coating at least one layer of said paperboard;
providing moisture to said paperboard, the amount of moisture added is substantially within the range of 3% to 11% by weight and creasing said paperboard; placing said corrugated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed said stamping die including a draw ring; pressing said paperboard between said die and said cavity to apply substantially four tons of pressure to said paperboard; applying heat to said paperboard simultaneously with said application of pressure; tensioning said paperboard while said paperboard is pressed between said die and said cavity; said paperboard having folds therein and said heat applied to said paperboard creating steam within said cavity to steam iron said folds to form a container and provide structural integrity; removing said die from said cavity; and ejecting said paperboard from said cavity after said die has been removed.
13. The method of claim 13, wherein the flute repeat length to flute height ratio is no greater than 2.6.
14. A method of producing a single-faced corrugated paperboard which is adaptable to be molded into a container comprising gluing a first flat layer of paperboard having a thickness in the range of 0.3 mm to 1.5 mm to a contoured layer of paperboard, said contoured layer having a thickness in the range of 0.23 mm to 0.5 mm, said contoured layer forming 350 to 400 sets of flutes per linear meter of paperboard, each flute being formed as alternating upper and lower curved surfaces in the contoured layer with each flute having a height in the range of 0.9 mm to 1.2 mm, the flute rise being substantially vertical at the midpoint between the upper and lower curved surfaces, applying glue to each lower curved surface of the contoured layer; passing said first layer and second layer through rollers, and applying a sufficient pressure to press said first and second layers together to adhere them, forming ridges and grooves in said contoured layer, the lower curved surfaces of said contoured layer being indented within said first layer by at least 0.1 mm, increasing the area of surface contact and gluing area between said first and second layers, said second layer having 6-12 ridges per inch.
15. The method of claim 15, wherein the flute repeat length to flute height ratio is no greater than 2.6.
16. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch.
17. The container of claim 16, wherein the contoured layer has a flute repeat length to flute height ratio no greater than 2.6.
18. The container of claim 16, wherein the upper edges of said ridges form receiving surfaces on which an object received by said container rests, and grooves formed between said ridges for receiving and collecting moisture given off by said object.
19. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means, said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch;
the upper edges of said ridges form receiving surfaces on which an object received by said container rests, and grooves formed between said ridges for receiving and collecting moisture given off by said object; and said ridges are coated with a recyclable coating adapted to resist penetration of moisture.
20. The container of claim 18, wherein the paperboard of said upper and lower compartments has a thickness in the range of 0.030 inches to 0.060 inches.21. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch; and said ridged surfaces are coated with a coating to resist penetration of moisture.
22. The container in accordance with claim 16, wherein said upper and lower compartments each have four sidewalls.
23. The container as claimed in claim 16, wherein said hinge means is formed of perforated paperboard.
24. The container as claimed in claim 16, further comprising fastening means for releasably fastening said lower compartment to said upper compartment.25. The container as claimed in claim 16, wherein said fastening means includes a tab formed on said first compartment and a slit formed on said secondcompartment for receiving said tab.
26. The container as claimed in claim 21, wherein said coating is a water based coating.
27. A container formed as a unitary construction by stamping corrugated paper, said container comprising:
a first compartment having a base and sidewalls integrally formed therewith;
a second compartment having a top and sidewalls integrally formed therewith;
hinge means integrally joining said first compartment and said second compartment to allow said upper and lower compartments to move relative to each other about said hinge means;
said first compartment, second compartment and hinge means being formed of paperboard, said paperboard having at least a flat layer and a contoured layer, said contoured layer consisting of a plurality of flutes, each said flute including a first flute tip and a second flute tip, the flute rise being substantially vertical at the midpoint between said flute tips, each flute being formed by alternating upper and lower curved surfaces such that the contoured layer is formed with ridges providing increased strength and rigidity using less paperboard, said contoured surface having 6 to 12 ridges per inch;
the paperboard has a thickness in the range of 0.040 inches to 0.050 inches.
28. A laminated paperboard, comprising:
a layer of paperboard;
a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said first layer along said plurality of said lower curved surfaces of said second fluted layer;
a second layer of paperboard coupled with said second fluted layer along said plurality of said upper curved surfaces of said second fluted layer; and the second layer of paperboard is perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer.
29. The laminated paperboard of claim 28, wherein a moisture barrier layer is provided on the upper surface of said layer of paperboard.
30. The laminated paperboard of claim 1, wherein a moisture barrier layer is provided on the lower surface of said fluted layer of paperboard.
31. The laminated paperboard of claim 1, wherein the flute repeat length to flute height ratio of the fluted layer is 2.6 or less.
32. The laminated paperboard of claim 29, wherein a moisture barrier layer is provided on the upper surface of said second layer of paperboard.
33. A laminated paperboard, comprising:
a layer of paperboard;
a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said first layer along said plurality of said lower curved surfaces of said second fluted layer;
a second layer of paperboard coupled with said second fluted layer along said plurality of said upper curved surfaces of said second fluted layer; and the second layer of paperboard is perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer;
the second layer of paperboard being perforated, having a plurality of openings therein to allow fluid communication between an object resting on said second layer of paperboard and said fluted layer;
each of said plurality of openings provided in said perforated layer of paperboard is dimensioned to have a diameter equal to the width of between two and three of said plurality of said upper curved surfaces.
34. The laminated paperboard of claim 29, wherein said plurality of openings provided in said perforated layer of paperboard are arranged in a checkerboard pattern.
35. A method for forming a laminated paperboard, comprising the steps of:
providing a layer of paperboard;
providing a fluted layer of paperboard having a plurality of upper and lower curved surfaces;
positioning said fluted layer of paperboard above and in contact with said first layer of paperboard;
providing a perforated layer of paperboard;
positioning said perforated layer of paperboard above and in contact with said fluted layer of paperboard; and coupling said fluted layer of paperboard with said perforated layer of paperboard and with said layer of paperboard.
36. The method of claim 35, further comprising the step of providing a moisture barrier on the upper surface of said layer of paperboard before positioning said fluted layer of paperboard above and in contact with said layer of paperboard.
37. The method of claim 35, further comprising the step of providing a moisture barrier on the lower surface of said fluted layer of paperboard before positioning said fluted layer of paperboard above and in contact with said layer of paperboard.
38. The method of claim 35, further comprising the step of providing a moisture barrier on the upper surface of said perforated layer of paperboard before positioning said perforated layer of paperboard above and in contact with said fluted layer of paperboard.
39. A laminated paperboard tray, comprising:
a base;
angled sidewalls being formed integrally with said bottom surface and set at a predetermined angle thereto;
curved walls being formed integrally with said angled sidewalls for connecting said angled sidewalls; and a lip being formed integrally with said angled sidewalls and said connecting walls and positioned thereabove;
said base, said angled sidewalls, said curved walls and said lip being formed of laminated paperboard, said paperboard having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer of paperboard and a perforated layer of paperboard coupled with said fluted layer of paperboard along said plurality of said upper curved surfaces of said fluted layer of paperboard.
40. The laminated paperboard tray of claim 39, wherein said upper curved surfaces are moisture absorbent, so that said upper curved surfaces absorb moisture given off by said object.
41. The laminated paperboard tray of claim 39, further comprising a moisture barrier disposed on the upper surface of said layer of paperboard.
42. The laminated paperboard tray of claim 39, further comprising a moisture barrier layer disposed on the lower surface of said fluted layer of paperboard.
43. The laminated paperboard tray of claim 39, further comprising a moisture barrier layer disposed on the upper surface of said perforated layer of paperboard.
44. A method for forming a laminated paperboard tray having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer and a perforated layer of paperboard having a plurality of openings therein coupled with said fluted layer along said plurality of said upper curved surfaces of said fluted layer, comprising the steps of:
placing said laminated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed;
pressing said paperboard between said die and said cavity to apply a pressure to said paperboard;
applying heat to said paperboard simultaneously with said application of pressure to affix said perforated layer to said fluted layer to permit fluid communication therebetween; and removing said die from said cavity.
45. The method of claim 44, further comprising the step of creasing said paperboard prior to placing said paperboard into said die.
46. The method of claim 44, further comprising the step of providing moisture to said paperboard before placing said paperboard into said stamping die.
47. The method of claim 46, wherein the amount of moisture added is substantially within the range of 3% to 11% by weight.
48. The method of claim 44, further comprising the step of ejecting said paperboard from said cavity after said die has been removed.
49. A method for forming a laminated paperboard tray having a layer of paperboard, a fluted layer of paperboard having a plurality of upper and lower curved surfaces being coupled with said layer of paperboard along said plurality of said lower curved surfaces of said fluted layer and a perforated layer of paperboard having a plurality of openings therein coupled with said fluted layer along said plurality of said upper curved surfaces of said fluted layer, comprising the steps of:
placing said laminated paperboard into a stamping die, said stamping die having a male die and a female cavity shaped in the shape in which the paperboard is to be formed;
pressing said paperboard between said die and said cavity to apply a pressure to said paperboard;
applying heat to said paperboard simultaneously with said application of pressure to affix said perforated layer to said fluted layer to permit fluid communication therebetween;
removing said die from said cavity; and of coating at least one layer of said paperboard with a moisture barrier layer prior to placing said paperboard into said die.
50. The method of claim 44, wherein said stamping die includes a draw ring and further comprising the step of tensioning said paperboard while said paperboard is pressed between said die and said cavity.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/262,165 US5577989A (en) | 1994-06-20 | 1994-06-20 | Method for forming corrugated paper container and container made therefrom |
US40734195A | 1995-03-20 | 1995-03-20 | |
US08/262,165 | 1995-03-20 | ||
US08/407,341 | 1995-03-20 | ||
PCT/US1995/007722 WO1995035204A1 (en) | 1994-06-20 | 1995-06-19 | Method for forming corrugated paper container and container made therefrom |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2193386A1 true CA2193386A1 (en) | 1995-12-28 |
Family
ID=26949063
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002193386A Abandoned CA2193386A1 (en) | 1994-06-20 | 1995-06-19 | Method for forming corrugated paper container and container made therefrom |
Country Status (8)
Country | Link |
---|---|
EP (2) | EP0766622B1 (en) |
JP (1) | JPH10502585A (en) |
AT (1) | ATE197932T1 (en) |
AU (1) | AU2864295A (en) |
CA (1) | CA2193386A1 (en) |
DE (1) | DE69519573T2 (en) |
ES (1) | ES2156208T3 (en) |
WO (1) | WO1995035204A1 (en) |
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IT1291939B1 (en) * | 1997-03-21 | 1999-01-21 | Paros S R L | METHOD FOR MAKING A WRAP, PARTICULARLY FOR THE PACKAGING OF PRODUCTS, AND THE ENVELOPE MADE WITH THIS METHOD. |
FR2764864B1 (en) * | 1997-06-20 | 1999-09-24 | Jean Marie Vauzelle | CASE FOR PACKAGING AND TRANSPORT OF FOODSTUFFS |
US6491214B2 (en) | 1998-04-17 | 2002-12-10 | The Procter & Gamble Company | Multi-ply food container |
US6179203B1 (en) * | 1998-08-28 | 2001-01-30 | The Procter & Gamble Company | Selectively reinforced multi-ply food container |
US6386439B2 (en) | 1998-10-14 | 2002-05-14 | The Mead Corporation | Tray container and blank |
GB2367226B (en) * | 2000-09-15 | 2005-02-09 | Ekco Packaging Ltd | A container for food |
WO2003004256A1 (en) * | 2001-07-06 | 2003-01-16 | Innovative Packaging Corp. | Method of thermoforming a container of corrugated material and container container formed thereby |
US7681733B2 (en) | 2002-08-29 | 2010-03-23 | Colbert Packaging Corporation | Packaging container with criss-cross grain pattern having product holding chambers and method for making the same |
KR101071210B1 (en) * | 2005-02-21 | 2011-10-10 | 비나이 케이. 메타 | Ventilation board, ventilation box, ventilation system, insulating board and method for manufacturing ventilation board and box |
WO2009020805A1 (en) * | 2007-08-08 | 2009-02-12 | Meadwestvaco Corporation | Packaging tray with compartment |
JP5368956B2 (en) * | 2009-12-03 | 2013-12-18 | 積水化成品工業株式会社 | Food packaging sheet material and food packaging container |
NZ594363A (en) * | 2011-08-01 | 2012-12-21 | Corcel Ip Ltd | Method and machine for perforating corrugated board as part of a continuous cold forming process |
FR2997068B1 (en) * | 2012-10-18 | 2015-12-11 | Nicolas Saverino | TRAY |
US11420417B2 (en) | 2013-03-15 | 2022-08-23 | Scorrboard Llc | Methods and apparatus for producing scored mediums, and articles and compositions resulting therefrom |
AP2015008804A0 (en) | 2013-03-15 | 2015-10-31 | Corrugated Synergies Internat Llc | Establishing a registered score, slit or slot in corrugated board,and articles produced therefrom |
US10328654B2 (en) * | 2016-04-20 | 2019-06-25 | Scorrboard, Llc | System and method for producing a multi-layered board having a medium with improved structure |
US11027513B2 (en) | 2016-04-20 | 2021-06-08 | Scorrboard Llc | System and method for producing an articulating board product having a facing with score lines in register to fluting |
US11027515B2 (en) | 2016-04-20 | 2021-06-08 | Scorrboard Llc | System and method for producing multi-layered board having at least three mediums with at least two mediums being different |
US10800133B2 (en) | 2016-04-20 | 2020-10-13 | Scorrboard, Llc | System and method for producing a facing for a board product with strategically placed scores |
KR101938050B1 (en) * | 2017-03-15 | 2019-04-10 | 김경복 | Goal Gate Double layer honeycomb |
GB2560825A (en) * | 2017-03-20 | 2018-09-26 | Havi Global Solutions Europe Ltd | Food packaging |
CN106988156A (en) * | 2017-03-30 | 2017-07-28 | 天长市天达纸箱纸品厂 | A kind of preparation method of high-gloss water-proof corrugated case water lustering oil |
BR112020021184A2 (en) * | 2018-04-30 | 2021-01-19 | Westrock Mwv, Llc | COATED CARDBOARD CONTAINER, METHOD OF MANUFACTURING COATED CARDBOARD CONTAINER AND CUP BACKGROUND FORMATING APPLIANCE |
IT201900016793A1 (en) * | 2019-09-19 | 2021-03-19 | Ghelfi 1905 S R L | Concave products, relative semi-finished products and their preparation procedures |
IT202100005579A1 (en) * | 2021-03-10 | 2022-09-10 | Imbal Carton S R L | DIE-CUT CORRUGATED CARDBOARD CONTAINER FOR PACKAGING SOOTHING FOOD PRODUCTS |
IT202100020870A1 (en) * | 2021-08-03 | 2023-02-03 | Lic Packaging S P A | CARDBOARD DRAINING TRAY FOR FOOD |
IT202100020891A1 (en) * | 2021-08-03 | 2023-02-03 | Lic Packaging S P A | CARDBOARD DRAINAGE TRAY FOR FOOD PACKAGING IN MODIFIED ATMOSPHERE |
DE102022113982A1 (en) | 2022-06-02 | 2023-12-07 | Syntegon Technology Gmbh | Packaging made from fiber-based packaging material |
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US3379537A (en) * | 1964-09-14 | 1968-04-23 | Waldorf Paper Prod Co | Bulk butter package |
JPS5310182A (en) * | 1976-07-15 | 1978-01-30 | Nissan Motor Co Ltd | Process for forming corrugated cardboard |
AU562471B2 (en) * | 1985-03-06 | 1987-06-11 | Board Mills Of Aust. Ltd. | Shaping corrugated board in mould |
EP0222840A1 (en) * | 1985-05-30 | 1987-05-27 | Garwood Limited | Packaging |
US4637811A (en) * | 1985-10-15 | 1987-01-20 | Peerless Machine & Tool Corporation | Container die system |
US4778439A (en) * | 1987-06-18 | 1988-10-18 | Peerless Machine & Tool Corporation | Apparatus and method for forming a clamshell assembly |
US4950524A (en) * | 1988-02-16 | 1990-08-21 | Hacker Robert L | Bacon pad |
US4886696A (en) * | 1988-05-10 | 1989-12-12 | Manville Corporation | Corrugated paperboard automotive liner |
AU625378B2 (en) * | 1988-12-01 | 1992-07-09 | Emhart Australia Pty. Limited. | Improvements relating to moulded paperboard |
US4931346A (en) * | 1988-12-19 | 1990-06-05 | Book Covers Inc. | Lightweight laminated paperboard |
FR2713136B1 (en) * | 1993-11-30 | 1996-04-26 | Posson Cartonnages Sa | Non-insulating monobloc laminate trim and its manufacturing process. |
-
1995
- 1995-06-19 AU AU28642/95A patent/AU2864295A/en not_active Abandoned
- 1995-06-19 AT AT95923944T patent/ATE197932T1/en not_active IP Right Cessation
- 1995-06-19 DE DE69519573T patent/DE69519573T2/en not_active Expired - Fee Related
- 1995-06-19 EP EP95923944A patent/EP0766622B1/en not_active Expired - Lifetime
- 1995-06-19 EP EP00201024A patent/EP1023992A3/en not_active Withdrawn
- 1995-06-19 CA CA002193386A patent/CA2193386A1/en not_active Abandoned
- 1995-06-19 WO PCT/US1995/007722 patent/WO1995035204A1/en active IP Right Grant
- 1995-06-19 JP JP8502520A patent/JPH10502585A/en active Pending
- 1995-06-19 ES ES95923944T patent/ES2156208T3/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
WO1995035204A1 (en) | 1995-12-28 |
EP0766622A1 (en) | 1997-04-09 |
EP0766622B1 (en) | 2000-12-06 |
JPH10502585A (en) | 1998-03-10 |
ES2156208T3 (en) | 2001-06-16 |
DE69519573D1 (en) | 2001-01-11 |
DE69519573T2 (en) | 2001-07-19 |
EP1023992A3 (en) | 2001-06-06 |
EP1023992A2 (en) | 2000-08-02 |
ATE197932T1 (en) | 2000-12-15 |
AU2864295A (en) | 1996-01-15 |
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Legal Events
Date | Code | Title | Description |
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EEER | Examination request | ||
FZDE | Discontinued |