PROCESSES FOR MOLDING PULP PAPER CONTAINERS AND LIDS
A process for molding recyclable, compostable, and disposable containers made of pulp paper is disclosed herein. The process includes disposing a wet pulp layer on a male or female mold, mating the mold with its counterpart, and applying a force on the pulp layer to remove moisture and thin the pulp. The process continues by applying a vacuum to either the male or female mold to hold the pulp layer, and removing the other mold. The process further comprises sequentially mating male and female molds until the pulp layer is the desired thickness and shape of the container. Embodiments of the process may include molding pulp containers to include pleats, stability features, reverse draft features, and puffed pulp configurations.
This application is a non-provisional patent application that claims the benefit of and priority to U.S. Provisional Patent Application No. 61/172,965, titled MOLDED PULP PAPER CONTAINER FOR LIQUIDS AND BEVERAGES, filed Apr. 24, 2009; U.S. Provisional Patent Application No. 61/219,712, titled CREATING AND RUNNING A REVERSE DRAFT ON PAPER PULP MOLDING MACHINERY AND SUBSEQUENT POSSIBILITIES FOR FORMING UNIQUE SHAPES AND PROFILES, filed Jun. 23, 2009; and U.S. Provisional Patent Application No. 61/301,934, titled MOLDED PAPER CUP CONTAINER FOR LIQUIDS AND BEVERAGES, filed Feb. 5, 2010; each of which is incorporated herein by reference in its entirety.
TECHNICAL FIELDThe present invention relates to containers made of paper, and more specifically to molding pulp or forming paper to form paper containers.
BACKGROUNDPaper tubs, containers, and cups are made out of pulp, which is inherently fragile when wet, and, accordingly, the standard methods of manufacturing paper containers begin with dry sheets of finished paper. Using a paper cup as an example, paper sheets are first die cut into specific shapes and then wound onto a mandrel. A cylindrical shape is formed, and the pulp paper cup is then glued or sealed at a seam. Next, a base of the cup is die cut and glued or sealed at a base seam adjacent to the cylindrical portion of the cup. Most paper cups and other paper containers have a top edge portion that requires an additional manufacturing step, e.g., creating a lip roll, which provides the container with circumferential strength. In addition, since paper is water permeable, the paper used in containers must be pre-printed and laminated with a water resistant layer, either before or after manufacturing, to ensure the containers are capable of holding food and beverages. Furthermore, paper containers, especially cups, made with this standard manufacturing method often necessitate the use of thermal insulating sleeves to prevent a user from being burned by the hot contents of the container. Manufacturing thermal insulating sleeves requires an additional manufacturing step and additional machining tools. Therefore, the standard method of manufacturing paper containers requires numerous processes and numerous machine tools.
Molding plastic is a less complex method of manufacturing containers. The elasticity of plastic simplifies manufacturing to the following steps: pouring heated plastic into a mold having a desired container shape, allowing the plastic to harden, and removing the hardened plastic from the mold. More complex shapes may also be made during thermo forming of plastics since the elasticity of plastic allows it to bend in different directions and resiliently recover when drawn from a mold. Unfortunately, molding techniques used for plastic containers are generally incompatible with pulp paper because wet pulp is inelastic and fragile. Applying standard molding techniques causes the pulp to tear. Additionally, pulp molding is less capable of attaining complex shapes, e.g., reverse drafts on surfaces, since it cannot elastically recover when drawn from molds. Therefore, it is desirable to have a less complex method for manufacturing paper containers that accommodates the material characteristics of pulp.
SUMMARYThe present disclosure is directed to a process for molding a pulp container that overcomes problems experienced in the prior art. The present disclosure is further directed to a method of molding a container that is made of recyclable, disposable, and/or compostable cellulose fiber materials. A generally accepted definition of compostable is a material that is able to break down into carbon dioxide, water and biomass at the same rate as paper. Compostable material also does not produce toxic material and is generally able to support plant life.
A container made in accordance with at least one embodiment of the present disclosure may be made from renewable resources that may include recycled materials, biodegradable materials, compostable materials, and organics, e.g., cellulose fiber, tapioca, wood, agricultural recycled crop materials, and plastics, e.g., PLA. The container may also be made from materials including non-organics, e.g., clay, metals, and petro plastics, e.g., silicone, PVC's, and PET styrene. An embodiment in accordance with the present disclosure includes molding a container made of pulp.
Embodiments of the present disclosure include processes for forming molded pulp containers, such as cups and/or lids. Some embodiments may include using molds having greater draft angles than typical molding to accommodate for the fragility of wet pulp. The processes disclosed herein may also result in greater insulation because the resulting pulp container has a less densely formed substrate due to the forming and pressing processes associated with embodiments of the invention. Molded containers manufactured with this process can include a variety of homogeneous and non-homogeneous shapes.
Embodiments in accordance with the present disclosure provide a process for molding containers that include a pleat. Pleats are advantageous since they allow containers to be molded with larger draft angles for easy removal from molds. The pleats are subsequently folded, thereby forming a seam and a container having a smaller draft angle, a smaller diameter, and a greater height than the mold.
Another embodiment of the present disclosure is drawn to processes that include containers having specially shaped edges. For example, cups may include a top edge having a contoured lip or roll. This forms a more desirable drinking surface and makes it easier to connect the cup to a lid.
Still other embodiments in accordance with the present disclosure provide a process for molding a container including a reverse draft feature. For example, lids include reverse draft features to securely connect to containers. Containers themselves also have reverse draft features. Embodiments in accordance with this process include first molding pulp along a horizontal axis to include pleat configurations, gradually bending the pulp to a reverse draft angle using sequential molds, removing the molds, and collapsing the pleats on the pulp to form the reverse draft feature.
In the drawings, the sizes and relative positions of the elements in the drawings are not necessarily drawn to scale. For example, the shapes of the various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings. Understanding that these drawings depict only one embodiment of the disclosure and are not therefore to be considered as limiting of its scope, the disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings.
Appendix A includes prospective views of other molded pulp paper containers in accordance with embodiments of the invention.
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
DETAILED DESCRIPTIONThe following describes embodiments of a process for molding a pulp container in accordance with the present disclosure. Embodiments in accordance with the present disclosure are set forth hereinafter to provide a thorough understanding and enabling description of a number of particular embodiments. Several specific details of the disclosure are set forth in the following description and in
Embodiments of processes in accordance with the present disclosure may include molds having tapered surfaces that form a draft angle between the mold and the parting line of the molded material. Draft angles allow for easy removal of the formed container for the mold. For example,
In the subsequent stage of the process illustrated in
In another embodiment in accordance with the present disclosure, the pulp layer 101 is formed directly on the first female mold 103 using with a process similar to the process discussed above. For example, the wet pulp can be initially coated or otherwise disposed on the interior surface of the female mold 103 and a vacuum can be drawn through the mold surface to hold the layer of pulp 101 against the first female mold 103. In this embodiment, the process begins at
The subsequent stages of the process are shown in
In accordance with the subsequent stage of the process shown in
In the next step of the process, the second female mold 105 is removed from the pulp layer 101, which remains on the male mold. This process is similar to that described above with reference to
In accordance with embodiments of the disclosure, the process includes mating additional female molds with the pulp layer on the male mold 104 until the pulp layer 101 is the desired shape and thickness of the cup. The process of mating an additional female mold is similar to the sequence of stages described above with reference to
The next female mold can be configured so that, when combined with the male mold, the molds will have an offset A at the lower portion of the mold that is slightly less than the an offset B at the upper portion molds. This provides greater compression thinning of the lower portion of the pulp layer during this step of the molding process. The subsequent female molds, when combined with the male mold, may have alternating variations of the offsets A′ and B′ at the lower and upper portions of the mold, respectively Varying the offsets within individual molds and alternating the position of the varied offset of subsequent molds decreases the defects on the completed pulp paper container since the pulp is not continuously compressed against the same portions of the male mold. In the illustrated embodiment, the final pair of female and male molds will have a selected offset, uniform or varied, that provides the desired thickness of the pulp layer for the final product. For example, if the final product is designed to have a uniform thickness, the offset between the final set of female and male molds will have a uniform offset.
In accordance with embodiments of the present disclosure, the process may also include a varying number of molding steps for molding the pulp layer between selected sequential sets of male and female molds depending upon the desired thickness and shape of the container. For example, one embodiment forms the molded pulp product using three molding steps with three sets of sequential pairs of molds, each having increasingly smaller offsets. Other embodiments can includes five to seven sequential molding steps with the selected pairs of male and female molds. Additional embodiments in accordance the present disclosure may include more or less repetitions. In some embodiments, the use of a greater number of molding steps can provide for better throughput in the molding process to provide a greater number of molded pulp products in a selected time period.
The molding process described above with reference to
In accordance with this embodiment of the process, each subsequent male mold has a greater diameter than the previous male mold so as to decrease the offset between the molds, and the number of male molds may vary depending upon the desired thickness and shape of the resulting molded pulp product. Additionally, as described above with reference to female molds, the male molds can be configured to provide varied offsets between different portions of a set of male and female molds, i.e., the lower portion compared to the upper portion of the mold. The positions of the varied offset may alternate between subsequent male molds.
Still further embodiments in accordance with the present disclosure can include alternating the vacuumed surface between male and female molds so that the pulp layer 101 is retained on a male mold at one molding station and then on the female mold at the next molding station. For example, as illustrated in
In operation of one embodiment, the pulp layer 101 is carried by the female mold 403 as discussed above. The male mold 404 is in the initial molding position with the mold segments 406 spaced apart before the male mold is inserted into the female mold. When the male mold 404 is axially inserted into the female mold 403 to compress the pulp layer, the first (bottom mold) segment 410 pressed into the bottom portion of the pulp layer to compress the pulp layer against the female mold. In this position, when the mold segments are still in the initial position, which defined the first drat angle, the mold segments provide some compressive forces against the pulp layer. The remaining mold segments 412-420 are then moved axially along the central shaft until the segments are stacked upon each other and in the final mold position. As the mold segments are moving to the final mold position, the effective draft angle of the male mold increases and the segments provide increased wedging and compression forces against the pulp layer that drives moisture from the pulp layer 101 and further thins the pulp layer. In one embodiment, the mold segments 412-420 can all be substantially simultaneously moved into the final mold position. In another embodiment, the mold segments can be moved sequentially into to their respective final mold positions. Although the illustrated embodiment shows male and female molds with a cup shape, other embodiments can provide molds for forming molded pulp containers with other shapes.
As shown in
Additional embodiments in accordance with the present disclosure include processes for molding pulp products having non-cylindrical features. For example,
Each of the above embodiments may further include a process for forming an upper edge feature on a container.
Still other embodiments of the present disclosure include processes for forming a container with a reverse draft. As described above, a reverse draft feature is one whose angle runs against the draw of the mold.
As shown in
In the process described above, three sequential male and female molds move the reverse draft feature from a horizontal plane to the vertical plane, thereby creating the bump 910 at a negative draft angle. However, it should be noted that more or less pairs of molds may be used to create a reverse draft feature. For example, each sequential pair of molds may change the angle of a pulp layer only a few degrees until the desired reverse draft feature is obtained. As discussed above, each additional mold set decreases offset to apply force to the pulp and extract excess moisture. Additionally, the offset may be varied within individual molds and alternate between sequential molds in order to decrease the defects transferred to the pulp.
In additional embodiments illustrated in
An additional embodiment in accordance with the present disclosure includes a process for forming a pulp product or a portion of a pulp product with a less dense construction, referred to as a puffed pulp construction. In some embodiments, this puffed pulp construction can be used to form portions that will elevate a reverse draft feature, such as on a container or a lid.
As illustrated in
This process of molding a pulp product with the puffed pulp process can be used to provide a wide range of products, including containers with or without lids. For example, the puffed pulp configuration can be used when forming a lid to provide a reverse draft feature that can engage a rim of a cup or other container.
All of the above processes may include heating the male and/or female mold. Heating the molds during the vacuum and the pressurized air application stages of the process facilitates a more rapid removal of the moisture from the pulp by turning it into steam. Adding heat is also advantageous in containers having a reverse draft feature as described above because it increases the memory of the pulp, thereby making it easier for the pulp layer to collapse from its horizontal orientation to its desired position after removal from the molds.
In each of the above embodiments, subsequent processes may be applied to the molded containers. For example, the containers may be printed, coated with a waterproof coating, and die cut. A coating may be applied to the containers while a vacuum holds a pulp layer against either the male or female mold. This has the additional advantage of assisting the coating in adhering to the container because the vacuum operates through the pours of the pulp paper container. The processes may further include applying a smooth and pleasing surface by using heat and press-in-place techniques. In additional embodiments, other surfaces and/or textures can be added to the container.
Each of the pulp molding processes described above may be performed by machines. These machines may include linear distribution lines wherein pulp layers are molded between male and female molds along an assembly line. The machines may also include circular revolving molds. It should be noted that any suitable machine for sequentially molding pulp into a container may be used to accelerate the process.
From the foregoing, it will be appreciated that specific embodiments of the disclosure have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. Furthermore, aspects of the disclosure described in the context of particular embodiments may be combined or eliminated in other embodiments. Further, while features and characteristics associated with certain embodiments of the disclosure have been described in the context of those embodiments, other embodiments may also exhibit such features and characteristics, and not all embodiments need necessarily exhibit such features and characteristics to fall within the scope of the disclosure. Accordingly, the disclosure is not limited, except as by the appended claims.
Claims
1. A process for making a molded pulp container comprising:
- disposing a pulp layer on a first mold;
- mating a second male mold with the first mold, the first and second molds being separated by a first offset and configured to exert a compressive force on the pulp layer to remove moisture and thin the pulp layer;
- drawing a vacuum through the second mold, the vacuum being configured to hold the pulp layer against the second mold;
- removing the first mold from the second mold and the pulp layer;
- mating a third mold with the second mold, the second and third molds being separated by a second offset, less than the first offset and configured to exert a compressive force on the pulp layer to further thin the pulp layer;
- drawing a vacuum through one of the second and third molds, the vacuum being configured to hold the pulp layer against the one of the second and third molds; and
- removing the other one of the second and third molds from the one of the second and third molds with the pulp layer thereon.
2. The process of claim 1 wherein the pulp layer is first disposed on a forming mold, mated with the first mold, and the forming mold is removed by drawing at least one of a vacuum through the first mold and pressurized air through the forming mold.
3. The process of claim 1, further comprising:
- applying pressurized air through at least one of the first and third molds when they are removed from the second mold.
4. The process of claim 1 wherein the first offset is greater in upper portions of the first and second molds and smaller in lower portions of the first and second molds, the process further comprising:
- varying the portions of subsequent male and female molds having a greater offset; and
- decreasing the size of subsequent offsets.
5. The process of claim 1, further comprising:
- repeating the mating and removing of subsequent molds until the container is a desired thickness and shape.
6. The process of claim 1, further comprising:
- repeating the mating and removing of subsequent molds;
- alternating the mold on which the vacuum operates to hold the pulp layer.
7. The process of claim 1, further comprising:
- mating a fourth mold with the second mold, the pulp layer having a portion extending beyond the fourth mold;
- drawing a vacuum through the fourth mold, the vacuum being configured to hold the pulp layer against the fourth mold;
- removing the second mold;
- mating a fifth mold with the fourth mold, the fifth mold having an upper portion configured to mold the portion of the pulp layer extending beyond the fourth mold at least partially against the fourth mold; and
- repeating the mating and removal of subsequent mating molds configured to mold the portion of the pulp extending beyond the fourth mold at least partially against the subsequent mating molds.
8. The process of claim 1 wherein first, second and third molds each have a draft angle, the draft angle configured to prevent the pulp layer from tearing when it is removed from at least one of the first, second and third molds.
9. The process of claim 1 wherein first, second and third molds have at least one indentation configured to form at least one pleat on the container.
10. The process of claim 1 wherein the first, second and third molds have a plurality of indentations configured to form a plurality of pleats on a circumference of the pulp layer, the process further comprising:
- molding a plurality of pleats about a circumferential portion of the pulp layer, wherein at least a portion of the pleats provides a reverse draft feature positioned at a negative draft angle.
11. The process of claim 10 wherein at least one of the first, second and third molds has a reverse draft portion with a greater porosity and a greater offset than the remainder of the mold, the reverse draft portion being configured to create a less dense pulp portion.
12. The process of claim 1 wherein the first, second and third molds are configured to imprint a pattern onto the pulp layer.
13. The process of claim 1 wherein first, second and third molds include angular lower portions, the angular lower portions configured to form stability features on the paper container.
14. The process of claim 1, further comprising:
- heating at least one of the first, second and third molds during mating.
15. The process of claim 1, further comprising:
- heating at least one of the first, second and third molds while a vacuum is applied to hold the pulp layer against it; and
- applying a coating to the pulp layer.
16. A method of manufacturing a pulp paper cup, the method comprising:
- disposing a pulp layer on a female mold;
- mating a male mold with the female mold, the female mold and the male mold having a first offset, wherein the first offset is the distance between the male and the first female mold and the first offset is non-homogeneous and is configured to apply a greater force on a first portion of the pulp layer;
- applying a vacuum to the male mold, the vacuum being configured to hold the pulp layer against the first male mold;
- removing the female mold, the female mold and male mold having a draft angle positioned between them and configured to prevent tearing of the pulp layer during removal of the female mold;
- mating a second female mold with the male mold, the second female mold creating a second offset, less than the first offset, the second offset is non-homogenous and is configured to apply a greater force on a second portion of the pulp layer, different than the first portion of the pulp layer; and
- removing the pulp layer from the male mold and the second female mold.
17. The method of claim 16, further comprising:
- providing a straight assembly line of sequential female molds; and
- repeating the mating of subsequent female molds with the male mold along the straight assembly line until the pulp layer is the desired thickness and shape.
18. The method of claim 16, further comprising:
- providing a circular manufacturing tool comprising male and female molds with sequentially smaller offsets; and
- repeating the mating of subsequent male and female molds until the pulp layer is the desired thickness and shape.
19. A process for manufacturing a molded pulp paper container having a reverse draft feature, the process comprising:
- disposing a pulp layer on a first female mold;
- mating a first male mold with the first female molds, the first male and female molds being separated by a first offset and having reverse draft portions with plurality of indentations configured to form a plurality of pleats on the pulp layer;
- applying a vacuum to the first male mold, the vacuum being configured to hold the pulp layer against the first female mold;
- removing the first female mold;
- mating a second female mold with the first male mold;
- applying a vacuum to the second female mold, the vacuum being configured to hold the pulp layer against the second female mold;
- removing the first male mold;
- mating a second male mold with the first female molds, the second male and female molds separated by an offset, smaller than the first offset, and having reverse draft portions configured an angular distance away from the draft;
- repeating the mating and removal of subsequent male and female molds until a portion of the pulp layer has a reverse draft feature, positioned at a negative draft angle;
- removing final male and female molds, wherein removing the molds expands the circumference of the paper container; and
- collapsing the paper container at the pleats to form the reverse draft feature.
Type: Application
Filed: Apr 26, 2010
Publication Date: Nov 25, 2010
Inventors: David Pierce (Renton, WA), Edward Urquhart (Bellevue, WA)
Application Number: 12/767,765
International Classification: D21J 3/10 (20060101);