HK1213844A1 - Microwave heating of heat-expandable materials for making packaging substrates and products - Google Patents

Abstract

Packaging containers (e.g., cups) or protective wraps may be made with two layers of sheet material and an expanded thermal insulation between the layers. The thermal insulation may be made from microencapsulated, heat-expandable particles that are expanded with a microwave heater at some point during processing substrate, building, conveying or packaging the containers. The particles may be applied to blanks formed from die cutting, expanded by heating, and then tampered. The blanks may be outer wraps to a double wall cup, formed by placing and adhering an inner cup to the outer wrap. Alternatively, an adhesive containing the particles are applied to inner cups, which may be adhered to outer wraps to complete formation of the double wall cups. The cups may then be heated with a microwave heater at a subsequent workstation as the cups are conveyed, stacked, placed in bags, the bags in cartons and the cartons stacked and palletized.

Description

Microwave heating of thermally expandable materials for making packaging substrates and products

Background

Consumers often purchase ready-to-use products, such as food and beverages, and other products, in containers made from packaging substrates. The thermally insulated container may be designed for hot or cold liquids or foods, such as hot coffee, iced tea, hamburgers, sandwiches or pizzas, and the like. It is desirable to enable these containers to maintain the temperature of the liquid or food inside for as long as possible by reducing the heat or cold transfer of the contents through the container.

To help insulate the consumer's hands from the heat of the hot beverage or to maintain the proper temperature of the contents of a food or beverage container for an extended period of time, the inventors have developed thermally expandable adhesives and coatings for packaging substrates, such as for multi-layer microgroove boards, paper or paperboard. Such expandable adhesives and coatings expand upon heating beyond a certain temperature range.

Drawings

FIG. 1 is a perspective view of an assembled cup having an outer wall.

FIG. 2 is a side cut view of a double wall cup.

Figure 3 is a cross-sectional view of a sleeve with a cup.

Fig. 4 is a side view of an example of a machine system for preparing a packaging material or container substrate.

Fig. 5 is a side view of a vacuum conveyor by which blanks (blanks) with thermally expandable particles adhered thereto may be processed.

FIG. 6 is a modified mandrel adapted with a raised strip including vacuum holes.

Fig. 7 is an example of an outer wall blank (or wrap) having a patterned coating of a thermally expandable material with gaps in which the raised strips of the mandrel of fig. 6 may be located.

FIG. 8 is a perspective view of a vacuum tube conveyor using the mandrel of FIG. 6 to transport a package including thermally expanded pellets on the inside.

Fig. 9 is a perspective view of a cup forming machine showing the application of a thermally expandable material to the outer surface of the inner cup.

Fig. 10 is a perspective view of the cup-forming machine of fig. 9, showing the insertion of the covered inner cup into an outer cup blank (or wrap) to construct a double wall cup.

Fig. 11 is a flow diagram of a plurality of stations or sites of a manufacturing process for manufacturing a packaged product, wherein microwave heat may be applied at or between the sites to expand thermally expansive adhesives or coatings that may be incorporated into or on a substrate layer of a packaging substrate and/or product.

Fig. 12 is a perspective schematic view of an example of an industrial microwave heater apparatus when positioned on a conveyor belt (conveyor belt).

Fig. 13 is a top plan schematic view of the microwave heater assembly of fig. 12.

Fig. 14 is a side plan schematic view of the industrial microwave heater assembly of fig. 12.

Fig. 15 is a front cross-sectional schematic view of the industrial microwave heater apparatus of fig. 12.

Fig. 16 is a flow diagram of an example of a method for making a multilayer sheet in a process that includes microwave heating of the multilayer sheet to accelerate expansion of a thermally expandable adhesive or coating.

Detailed Description

Disclosed are methods for heating, activating and expanding thermally expandable adhesives and coatings using microwave energy, which can be located on and/or within a substrate material that is subsequently used to be converted into a product or directly on or within a packaged product during its method of manufacture. The base material can be a single-or multi-layer material in roll, sheet or blank form, consisting for example of paper, cardboard, coated paper, fluted sheet material, plastic film, woven material, textile, non-woven material and/or a metallized base or any combination of these materials.

The multilayer sheet or web substrate can be bonded together by thermally expansive adhesives and coatings. The product can be a variety of packaged or unpackaged products such as, but not limited to, double-walled paper hot cups, paper bags, blisters (blister packs, meaning that the product is plastic shell wrapped), hot cup insulation sleeves, pop-up folding boxes, and cases. The method may comprise heating the packaged product made of the material after the product is made or after the product is packaged in a shipping container or after the container is loaded onto a trolley. The microwave heater activates the thermally expandable adhesive and coating using microwave energy to efficiently expand the thermally expandable adhesive and coating. The expansion of the adhesive or coating can help improve the thermal insulation and rigidity of the laminated or coated material, which helps to convert the material into a package or container and improves the thermal insulation of fluids and solids inside the container. The expansion of the adhesive or coating can also help reduce packaging materials by allowing less material to be used while maintaining the thermal insulation and rigidity required of the laminate and coating materials.

The above-described method can be automated to activate and expand the thermally expandable adhesive and coating on or in the base material (also referred to as "pre-activation") or on or in the product after product formation (referred to as "post-activation"). The thermally expandable adhesive or coating may be formulated with a composition comprising thermally expandable microencapsulated particles (e.g., microspheres or microtubes or other shapes) and other components (e.g., starch or other natural or synthetic adhesives and other adhesives as desired for a particular application). For example, the thermally expandable adhesive or coating may be prepared in one or a combination of the following: viscosity modifiers, humidity modifiers, defoamers, dispersants, mold inhibitors, and salts. Some examples of microencapsulated particles include: dualite supplied by Henkel, Expancel supplied by Akzo Nobel, microspheres F and FN series supplied by Matsumoto, and microspheres supplied by Kureha.

The material may be heated with a microwave heater at any of various points in the manufacturing process after application of the thermally expandable adhesive or coating. The multilayer sheet material may be laminated with any combination of the foregoing suitable materials and conveyed to final processing, such as conveying for printing, die cutting, forming, and/or otherwise assembling into product containers.

Heat may be applied to the material with a microwave heater at any or a combination of the preparation sites or stages (e.g., at or between stations following the preparation process). For example, microwave heat may be applied to the substrate while laminating or laminating, after the thermally expandable adhesive or coating has been applied. Further, microwave heat may be applied to the individual product containers containing the unexpanded microspheres after the product containers are formed (e.g., during transfer of the product to a station for packaging the product into shipping containers).

Alternatively or additionally, microwave heat may be applied through shipping containers (e.g., conventional trough cartons in which a plurality of products are packaged). In addition, the microwave heat may be applied through a loading trolley on which a plurality of transport containers are stacked. The thermally expandable adhesive or coating incorporated into the substrate of the product or laminated to the substrate may not expand (or fully expand) until microwave heat is applied at these later stages of the manufacturing process prior to shipping.

The packaging container may be constructed of and/or insulated with an insulating material. The insulating material may be comprised of a multi-layer laminate substrate or a coated substrate comprising a thermally expandable adhesive or coating. The thermally expandable adhesive or coating may be expanded by application of microwave heat before or after forming a packaging container from the multilayer substrate. In addition to microwave heat, other sources of heat and thermal energy may be applied, such as hot air or Infrared (IR).

The thermally expandable adhesive or coating may be applied to the container or within the container material or between container layers, or may be applied to the outer wall of the container or a combination of these. The insulating material comprising the thermally expandable adhesive or coating may expand before reaching the end user (e.g., when preparing the container and/or container jacket), and/or the insulating material may expand only at the end user and only in response to a certain level of temperature of, for example, a hot beverage or food served within the container. The expanded insulating material may be used to aid in the insulating properties of and/or to increase the rigidity of the container and/or container sleeve, and may help reduce the thickness of the material component of the container and/or container sleeve.

The sheet material used to prepare the packages, containers, and/or container sleeves may be prepared on a conveyor-type machine system in an automated assembly line process, an example of which will be discussed in more detail later. The thermally expandable adhesive or coating may be applied to the sheet material by a number of conventional application methods, such as non-contact spray and/or contact bars, rollers, nozzles or slit extrusion, spread and brush methods or other methods, such as, but not limited to, application to the corrugated media prior to lamination of the innerliner thereto. Whereby the thermally expandable adhesive or coating may be located between two layers of some kind of sheet material before expanding during the preparation process. When the insulating material is a coating, the insulating material may be applied to a single layer (or single) sheet or to the outer surface or interior of a multi-layer sheet prior to thermal expansion. Other embodiments are equally possible, as discussed subsequently, such as applying microwave heat to expand the expandable adhesive or coating at some other point during or after the manufacturing process, e.g., after forming a multi-layer substrate or after product formation or before shipping the container from a warehouse.

In some embodiments, the thermally expandable adhesive/coating is heated during a conveyor-type machine assembly process such that the expansion occurs as the container is prepared. With conventional machine systems, common heat sources are from hot air and/or Infrared (IR). Conventional heating methods (e.g., hot air ovens and/or infrared heaters) installed only on-line on machine systems are sometimes insufficient to fully activate thermally expandable microencapsulated particles, such as microspheres or microtubes added to the thermally expandable adhesive or coating, at production speeds (e.g., 150 feet per minute (fpm) to 600 fpm). This is due in part to space and thermal power limitations and these methods are based primarily on heating mechanisms that transfer heat from the outside to the inside by conduction, convection, and radiation to the material being heated. The use of these conventional heating sources therefore presents technical problems of means of thermal energy transfer, which leads to inefficient and limited expansion of the thermally expandable microparticles. For example, the outer portion of the coating may first dry and cure, significantly limiting the expansion of the expandable microparticles.

In the present invention it is proposed to apply microwave energy from an industrial microwave applicator which is adapted to apply microwave energy throughout the entirety of the substrate material or packaged product comprising the expandable adhesive or coating passing therethrough during the process. Thus, the microwaves from the microwave heater are able to penetrate and provide energy to the thermally expandable adhesive or coating inside the substrate, causing it to heat more uniformly, volumetrically (volumetrically) and rapidly than would be achieved by conduction, convection or surface radiation heating. This is due to the volumetric microwave heating of the thermally expandable adhesive/coating in a relatively short time. For example, thermally expandable microspheres incorporated into the adhesive/coating may expand rapidly when the mixture in which the microspheres are located is exposed to intense microwave energy to be rapidly heated.

The thermally expandable adhesive or coating may comprise thermally expandable microencapsulated microparticles, such as microspheres or microtubes from a plurality of different sources. Non-limiting examples include commercial products (such as Dualite, MicroPearl, and Expancel, discussed previously) and thermally expandable microtubes that may be used to formulate expandable materials.

The thermally expandable adhesive/coating may comprise a starch-based glue; may be based on synthetic or natural materials (e.g., polyacrylates, polyvinyl acetates, polyvinyl alcohols, starches, polylactic acids, and other materials); and can be applied to many different substrate materials such as paper, paperboard, corrugated board, plastic film, metallized film, textiles, woven or nonwoven materials, and other materials used to prepare laminates or coated substrates. The thermally expandable adhesive or coating may also help reduce materials, reduce packaging adverse environmental effects by reducing materials while maintaining volume and thermal insulation properties in the packaged product. These laminated or coated substrates can in turn be converted into a number of useful food and non-food packaging products such as, but not limited to, folding carton containers, hot and cold cups, boxes, paper blisters, fluted sleeves, micro-fluted blisters, E-flute boxes, bags and bag-in-boxes, and other packaging products (collectively referred to as containers). The multilayer material with intumescent material provides some with greater flexibility to expand the choice of size and basis weight for different substrates than those commonly available and offered by existing material suppliers.

These thermally expandable adhesives/coatings can be applied in a conventional corrugator laminator, printer, coater, coating applicator or other application method and expanded by means of an industrial microwave heater for efficient rapid expansion. The thermally expandable coating can be applied over the paper substrate either in full coverage or in any pattern of practical design and subsequently expanded with a microwave heater to produce a cellular or foamed structure in the coating with different end use advantages, some of which will be explained below.

Fig. 1 illustrates a container 100, such as a cup, having an inner wall 102 and an outer wall 104. The blank for the outer wall 104 may be in the form of a container sleeve or a sidewall wrap for the body of the container 100. The inner wall 102 can be formed of a laminate having an expandable thermal insulation material on its outer surface. The insulating material can also be located between the inner wall 102 and the outer wall 104. The outer wall 104 may not be needed when the inner wall 102 coated with the insulating material comprises sufficient volume and insulating properties.

The container 100 is not limited to a cup and may be any other container including, but not limited to, a bulk coffee container, a soup tub, a press-formed container, a plate, a sleeve (e.g., single-sided corrugated, double-sided corrugated, non-corrugated cardboard, etc.), a folding carton, a plate, a bowl, a blister, a bag, and other containers with or without a lid or sleeve. The container 100 may be a cylindrical cup or a container having other geometric configurations, including conical, rectangular, square, oval, etc.

The outer wall 104 blank is not limited to a corrugated die-cut blank and may be constructed of any type of paperboard, paper, foil, film, fabric, foam, plastic, etc. The outer wall 104 may be made from any nominal paper stock including, but not limited to, natural single facers, white top single facers, top coated and bleached single facers, corrugated, fluted corrugated paper, paperboard, white paper, recycled paper, coated paper board, or any combination of these materials. The outer wall 104 may be removed from the container 100 or the outer wall 104 may be adhered to the container 100. The outer wall 104 may be adhered, for example, by laminating the outer wall 104 blank to the container using a hot adhesive, a cold adhesive, and/or any other bonding or sealing mechanism. Alternatively or additionally, the outer wall 104 blank may be adhered with an insulating material. If the outer wall 104 is attached to the cup during manufacture, this attachment can be effectively enhanced by eliminating the need for an end user to use an insulating sleeve. In addition, the attachment can reduce the amount of storage space required by an end user (e.g., storing an item, such as a double-walled or multi-walled container) as compared to a container and insulating sleeve alone.

Fig. 1 is not necessarily drawn to scale. For example, the outer wall 104 may cover a greater or lesser portion of the surface of the container 100 than illustrated. For example, the outer wall 104 may provide full cup coverage. Increasing the surface area of the outer wall 104 may provide a larger insulating area and a larger printing surface. Although the figures illustrate the outer wall 104 on a cup, the outer wall 104 may be added to any other container (such as, but not limited to, bulk beverage containers, press-formed containers, and soup cans). The outer wall 104 may be added to the container as a package (fig. 2 and 3).

Fig. 2 is a side cut view of the container 100, which may be a double wall cup having an inner wall 102 and an outer wall 104 or a single wall cup having a laminate including an inner wall 102 and an outer wall 104 with an expandable insulation 216 between two layers of material (e.g., paper). The space 200 between the inner wall 102 and the outer wall 104 may be partially or completely filled with the expandable insulating material, which may be at least partially filled after the application of heat from, for example, a microwave heater, causing the insulating material to expand. The container 100 may be adapted to hold hot or cold liquids as well as solid materials (e.g., food). For cold beverages or foods, the improved insulation of the container walls will not only help to keep the beverage or food cold for a sufficient period of time, but will also help to reduce or eliminate moisture condensation on the outer walls of the container. The outer wall 104 can be connected with the inner wall 102 at the top and bottom to provide a closed gap therebetween.

The insulating material 216 may expand upon heat activation of the unexpanded thermally expandable microspheres (or other forming agent) added thereto after the container 100 is formed. Alternatively or additionally, the insulating material 216 may be pre-expanded in situ in the air pockets of the insulating material 216 by, for example, introducing pre-expanded microspheres, air, or an inert gas. The insulating material 216 may be activated by microwaves or by other heating methods, for example. The insulating material 216 may include, but is not limited to: aqueous coatings, adhesives, starch-based adhesives, natural polymer adhesives, inert gas foamed hot melts, synthetic materials, foam coatings comprising thermally expandable microspheres, or any combination of these or other materials. In one example, the insulating material 216 having thermally expandable microencapsulated microspheres may include a starch composition having a small amount (e.g., 1-10%) of microspheres mixed into the insulating material 216. The insulating material 216 may be biodegradable, compostable, and/or recyclable.

The insulation 216 may be expandable when wet or semi-dry or dry, depending on the formulation. The insulating material 216 may include any synthetic or natural bonding material, including water-based materials, high-solids, or 100% solids materials. The solids content is typically 20% to 80%, more preferably 30% to 60% of the material. Other components may also be added to the bonding material and/or insulating material 216, including but not limited to: pigments or dyes, inorganic or organic fillers/extenders, surfactants for dispersion, thickeners or solvents to control viscosity for optimum application, foaming agents, additives such as waxes or slip aids, wetting agents, salts for enhancing microwave energy absorption, and the like. Alternatively, the insulating material 216 may be an adhesive. The insulating material 216 may have several properties, including but not limited to: thermal insulation for keeping the container internal substance hot or cold; absorbing condensed moisture and/or liquid; can expand upon contact with a hot material (e.g., 150 ° F or higher); and may be kept inert until a preset activation temperature is reached. For example, the insulating material 216 will remain inert at about room temperature. The insulation 216 may be repulped, recyclable, and/or biodegradable.

Fig. 3 illustrates a cross-section of the outer wall 104 of fig. 2 (e.g., a sleeve or wrap assembled with the container 100). The diagram is intended to be illustrative, and not restrictive. The cup may be replaced by any container, such as a press-formed tray, a soup tub or a bulk liquid container. The outer wall 104 may have an inner surface 306 and an outer surface 304. Insulation 216 may be applied to inner surface 306, outer surface 304, and/or surface 302 between inner surface 306 and outer surface 304 (e.g., the inner wall of the sleeve). The inner surface 306 and the outer surface 304 do not necessarily contain a space 302 therebetween.

Insulation 216 (e.g., a thermally expandable material having thermally expandable microspheres in unexpanded form) may be applied to the inner surface 306 of the outer wall 104. The insulating material 216 may be applied as a full coating, film, or shape that does not materially alter the thickness of the outer wall 104 prior to expansion. Applying the insulating material 216 to the interior of the outer wall 104 may also maintain the printability of the outer surface of the outer wall 104. If the insulating material 216 on the outer wall 104 is assembled with, for example, a standard paper cup, it can maintain the slim profile of the cup. Alternatively, the thermally expandable material may be activated by microwaves to accelerate expansion prior to assembly as a wrap during manufacture. This ensures that the expandable adhesive/coating is expanded during manufacture and provides additional hardness and strength after manufacture and before use.

Fig. 4 is a view of an example of a machine system 400 for preparing packaging substrate material that can subsequently be used to prepare containers (such as the container 100 discussed above). For example, and without limitation, the machine system 400 may be a conveyor-type machine system having multiple stages, such as an Asitrademicroflute laminator manufactured by Asitrade AG, Grenchen, Switzerland, cited as just one example. Other types of printers, coaters and laminators can also be used to produce similar single and multi-layer substrate materials. Fig. 4 provides three parallel views of the method: a mechanical view A; view B in the manner in which the sheet material can travel through the machine, and cross-sectional view C of the resulting prepared product. The machine system 400 may extend longitudinally over a substantial length and may include a plurality of stations along its length. The sheet material assembled into the wrapper or base travels along the machine from right to left as shown in fig. 4.

The machine system 400 may use a first sheet material 402, which first sheet material 402 may be provided in bulk as a roll or web. The first sheet material 402 may be fed into the machine system 400 and passed through the steps of the method by a wheel-based, belt-based, or other conveyance system. FIG. 4 illustrates the use of a wheel-based system; for example, a conveyor belt (1213 in fig. 12-13) can be moved forward by a wheel 406 and a series of belts. Alternatively or additionally, as shown in fig. 4, the machine system 400 may use sheet material that may be pre-printed. Different machine systems may use die-cut blanks for particular packages (such as cups, containers, plates, blisters, trays, bags, or beverage container bottles, among others), in which case the sheet material 402 can be a blank.

The first sheet material 402 can be constructed of a generally flat material that is somewhat rigid and can be bent or scored to facilitate bending along a set line. For example, the sheet material 402 may be a single-sided liner paper, such as, but not limited to, kraft paper, clay coated newsprint board, white top liner, containerboard, Solid Bleached Sulfate (SBS) board, or other material. The material may be treated, for example to provide increased resistance to water or fluid, and may have printing on selected portions of the material. Alternatively or additionally, the sheet material 402 may be composed of paper, paperboard, recycled paper, recycled paperboard, corrugated paperboard, chip board, plywood, metalized paper, plastics, polymers, fibers, composites, mixtures, or combinations of the foregoing, and the like. The first sheet material 402 may be constructed of recyclable materials or may be degradable, biodegradable, or a combination thereof.

The first sheet material 402 may be conveyed to a first station 420 by rollers 408. The first station 420 may be a corrugating or coating or printing station. The first station 420 may also include a corrugating roller. The corrugation rollers can form the first sheet material 402 or other media sheet into a series of corrugations or flutes. Alternatively, a single layer or sheet of substrate may be passed directly as the first sheet material 402 or paper media without corrugating.

The first station 420 may also include an applicator that may apply a securing material to one side (i.e., the roof) of the first sheet material 402 or the side of the other media sheet. For example, the applicator may have a trough containing a securing material (e.g., adhesive) and an applicator roll applicator (e.g., a rod or roller) that may have a metering tool. The trough may be located adjacent to the corrugating roller such that the adhesive is applied to the tops of the waves or flutes produced by the corrugating roller. Additionally or alternatively, the securing material may be applied by spraying, brushing, nozzle extrusion, or other means. For example, the applicator may apply the securing material by spraying it onto one side of the first sheet (or other media paper) of material 402. The spray from the applicator may be continuous or intermittent and may produce a dotted line, stripe, dot or oval of securing material. The designs and patterns may be applied by moving the applicator or by moving the first sheet material 402 relative to the sprayer.

The securing material may be, for example, an adhesive, an insulating material 216, or other material or coating, such as those having securing or bonding properties. Various expandable insulating materials 216 have been previously discussed in detail. Further, the securing material may be a hot melt or non-hot melt adhesive or a condensation adhesive, such as a hot melt adhesive, starch-based adhesive, natural polymer adhesive, cellulose-based adhesive, glue, hot melt glue, polymer adhesive, synthetic material, foam, and the like.

The securing material may be transported from line 422 to the applicator, which may occur at conditioning and preparation station 432. The microspheres or other expandable insulation material may be pre-mixed with starch, binder, or other additive material at the conditioning and preparation station 432 and shipped to the applicator of the first station 420.

In some embodiments, the applicator may apply a pattern of the thermally expandable coating onto a first sheet material or other paper media (referred to herein as a single ply sheet) and then heat it with a microwave heater to cause the thermally expandable coating to expand. This coated and patterned single layer sheet can then be sent for processing into a final product with the patterned coating.

In another embodiment, the first sheet material 402 may also be joined with the second sheet material 404 by, for example, pressing the second sheet material 404 onto the first sheet material 402. The second sheet of material 404 may be secured to the first sheet of material 402 by a securing material obtained from a double layer of sheet material 426, such as the single face fluted sheet shown in fig. 4C. Alternatively or additionally, the laminate 426 may be a flat, two-layer laminate of different substrate materials as previously discussed.

The two-ply sheet material 426 may then be passed through an industrial microwave heater 427, which may be built near the conveyor belt after the first station 420, to apply microwaves to the two-ply sheet material (fig. 12).

Preferably moisture remains within the thermally expandable sheet insulating material 216 from the mixture prepared in conditioning and preparation station 432. The moisture readily absorbs the microwave power emitted from the microwave heater 427, thereby rapidly heating, causing the applicator-applied adhesive/coating insulation 216 to expand under the appropriate processing conditions (e.g., temperature, pressure, and time).

The microwave heater 427 is preferably of the planar type operating at or near about 915MHz or about 2.45GHz, or at some other acceptable frequency. The microwave applicator 427 may also be a tubular or other type of microwave applicator including a microwave applicator. These types of industrial microwave heaters can be used to dry aqueous mixtures or products containing polar molecules that absorb electromagnetic energy in a microwave field, resulting in heating and drying of the water and sometimes cooking of the product. If planar, the microwave heater 427 may include a narrow open slot between two plates of a microwave waveguide or channel for the passage of a paper web or other substrate, as seen in FIGS. 12-13. If the microwave applicator is tubular, a product having a tubular or circular cross-section can be passed through a suitably configured microwave applicator of the heater. The microwave heaters 427 may not only dry the web or substrate, but may also activate and expand the expandable material pre-applied between or on the paper layers.

The microwave heater may be designed or configured in different ways to heat the thermally expandable coating and adhesive in the base material or in the product at different points during the manufacturing process, as illustrated and discussed with reference to fig. 11.

The temperature at which the microwave heater 427 can heat a substrate or product comprising thermally expandable material (e.g., microspheres) can be in the range of 100-500 deg.F. The temperature may vary to a large extent depending on the type of microspheres used and the thickness of the material substrate and adhesive being heated. For example, some conventional microspheres are heated to temperatures in the range of 200 DEG F and 350 DEG F.

The two-ply material web 426 may exit the machine system 400 and undergo other processing (e.g., die cutting, printing, conditioning, bending, etc.) to obtain the final product. Alternatively, the double layer of sheet material 426 may be further processed by the machine system 400 described below. Note that the microwave heaters 427 may alternatively be located along a workstation downstream of the machine system 400 for further processing. For example, an expandable adhesive or coating may be applied at a later stage in the process, and the microwave heater 427 may be located at some point thereafter to expand the adhesive/coating, as discussed later. The location of the microwave heaters 427 is not critical, but some locations may be better for reasons of easy connection of the components of the machine system 400, or other steps of the manufacturing and product preparation process may be better applied at some locations.

The bi-layer sheet of material 426 may be conveyed to a second station 430. The second station 430 may include an applicator that may apply a securing material to one side of the two-ply sheet 426. For example, the applicator may apply a securing material to the second sheet material 404 side of the two-layer sheet 426, which may be the inner side of the two-layer sheet 426. Alternatively or additionally, the applicator may apply a securing material to the first sheet material 402 side of the two-layer sheet 426. The securing material may be or include an expandable adhesive or a thermal barrier coating. For example, the securing material may be an adhesive, such as a hot melt adhesive, a starch-based adhesive, a natural polymer adhesive, a cellulose-based adhesive, a glue, a hot melt glue, a condensation glue, an adhesive, a synthetic material, a polymeric binder, a foam, and the like.

The securing material may be applied by spraying, brushing, or other means. For example, the applicator may have a trough containing the securing material and a metering tool. The trough may be located adjacent to the rollers that feed the paper to the second station 430 to apply the securing material to the tops of the corrugations or flutes produced by the corrugated rollers. As a second example, the applicator may apply the securing material by spraying the securing material onto one side of the first sheet of material 402, the second sheet of material 404, or both. The spray from the applicator may be continuous or intermittent and may produce a dotted line, stripe, dot or oval of securing material. The design and pattern may be applied by moving the applicator or by moving the first sheet material 402 relative to the sprayer.

The double layer of sheet material 426 may be combined with a third sheet material (which may be, for example, a second liner), such as by pressing a third sheet material 434 onto the double layer of sheet material 426, resulting in a three layer sheet material 434.

The three-layer sheet material 434 may be constructed of a generally flat material that is somewhat rigid and capable of being bent or scored to aid in bending along a set line. For example, the three-layer sheet material 434 may be a single-sided liner paper, such as, but not limited to, kraft paper. The material may be treated, for example to provide increased resistance to water or fluid, and printing may be performed on selected portions of the material. Alternatively or additionally, the third sheet material 434 can be composed of corrugated paperboard, cardboard, SBS, metalized paper, plastic, polymers, fibers, composites, mixtures or combinations of the foregoing, or the like. The third sheet material 434 may be made of a recyclable material, or may be degradable, biodegradable, or a combination of these.

The second workstation 430 may be a printer, a coater, or a laminator. The layers of the multi-layer sheet (e.g., three layers of sheet material 434) can enhance the structural integrity and appearance of the resulting packaging material. The microwave heater 427 may alternatively be located at or near the second station 430 to irradiate the multiwall sheet passing through the second station 430 (e.g., during lamination) with microwave energy. The microwave heater 427 can then rapidly heat and thereby expand the adhesive or coating containing the thermally expandable component (e.g., microspheres) applied to the multiwall sheet as a securing material. The multiple layers of sheet material exiting the second station 430 may be further conditioned, cut or die cut and stacked for transport, as will be discussed in more detail with reference to fig. 11. The multiple layers of sheet material may then be formed into a container 100.

Several laboratory feasibility tests have been performed using common office microwave ovens and test panel industrial microwave heaters. E-grooved single-face corrugated board and F-grooved single-wall corrugated board were used as substrates in these tests. The results from these tests demonstrate the feasibility of activating and expanding the thermally expandable adhesive and coating sandwiched between the media and the liner. The test also shows an increase in drying and a reduction in steam energy consumption. The test also revealed that designing a suitable microwave energy field inside the microwave applicator is beneficial for achieving an optimal expansion efficiency of the thermally expandable adhesive and coating and thereby increasing the production speed.

As an example of the pre-activation method described previously, fig. 5 is a side view of a vacuum transfer device 500 through which a blank 503 may be coated with a thermally expandable material in any suitable pattern. The vacuum transfer device 500 may be used independently or integrated into a portion of an automated manufacturing system. The vacuum conveyor 500 may include a vacuum motor 510 that rotates in the desired direction of travel of the conveyor 513, which is shown by the solid black arrow in fig. 5.

The blank or printed blank 503 may be a single or multi-layer sheet material, such as but not limited to a sheet material prepared by the above-described machine system 400, which may be passed through the vacuum conveyor 500. In one example, the blank 503 is used in a cup or in a double-walled cup. A glue gun (or coating or printing station) 505 or other applicator 505 may apply the wet thermally expandable material 216 containing the microencapsulated particles 506. Microwave heater 427 or other source of thermal energy provides energy to activate and expand particles 506, causing the particles to expand into expanded particles 508. The expanded particles 508 may form a pattern of a particular desired height on the blank 503. The height of the expanded particles may vary to some extent.

The vacuum motor 510 of fig. 5 may be used to help keep the blank 503 flat to allow the proper amount of thermally expandable coating to be applied uniformly in a design pattern. To meet the proper dosing of the wet granulation 506, the controller driving the vacuum motor 510 may closely control the RPM of the vacuum motor. Alternatively or additionally, the glue gun or the switch of the coating station 505 may be controlled, for example intermittently, to apply an appropriate amount of granules containing thermally expandable material in a designed pattern onto each respective blank.

The expanded particles 508 may be tamped to a relatively uniform preset height using a tamp or sizing device (sizing device)509, such as a wheel, block, or roller. A visual inspection or detection system 512 may then detect the quality of the expanded particles 508 for quality control prior to further processing, such as by a double wall cup or container forming machine.

FIG. 6 is a modified mandrel 600 fitted with one or two raised strips 605, each raised strip 605 having vacuum holes 601 (where FIG. 6 shows only one raised strip as an example). The raised strip 605 may fit at a height that is approximately (or substantially) equal to the uniform height of the expanded particles 508 shown in fig. 5. The height of the raised band 605 is about equal to or slightly greater than the height of the expanded particles 508 so that each blank 503 with expanded particles 508 is smoothly and properly wrapped around the mandrel 600 to form a properly matched cup overwrap for a double-walled cup.

Fig. 7 is an outer wall blank 703 having a patterned coating 715 of thermally expandable material 216 with a gap 723 through which a raised band 605 of mandrel 600 may be positioned. In this manner, the vacuum holes 601 may still create sufficient suction on the smooth portions of the interior of the blank 703 to use to hold the blank 703 wrapped around the mandrel to be conveyed. After the blank 703 is formed into an outer wrap of a cup, a single wall cup is placed within the formed wrap in an automated process to make a double wall cup.

Fig. 8 is a perspective view of a vacuum conveyor 800 using, for example, the mandrel 600 described with reference to fig. 6, for conveying a green body having thermally expansive particles adhered to the inside of the green body. The vacuum transfer device 800 may receive the blank 503 from the vacuum transfer device 500 of fig. 5. The mandrel 600 may position one raised strip 605 thereof within the gaps 723 in the thermal expansion pattern 715 of the thermally expanded particles of the blank 503 and another raised strip 605 below the wrapped seam region of the blank 503, for example where the edges of the blank meet together to form a wrap. The vacuum holes 601 of the raised strip help to hold the wrap around the mandrel 600 so that the blank 503 can be removed from the vacuum conveyor 800 and conveyed through the cup overwrap forming step.

In the steps taken in fig. 5-8, a machine component is fabricated that is operable to construct a double wall cup in the following manner: wherein the thermally expandable material 216 on the substrate (blank 503) is first expanded prior to construction of the container (double wall cup), which is previously referred to as a preactivation process. As will now be explained, in the post-activation process, the double-walled cup may also be constructed by first constructing the cup in a machine-assembly process and then expanding the thermally expandable microspheres present within the thermally expandable material 216 to construct the insulated double-walled cup.

As one non-limiting example of many post-activation methods, FIGS. 9 and 10 show perspective views of a cup forming machine 900. The cup forming machine 900 may include a set of glue guns 505, a sled 908, a rod 910, and a belt 912. The machine 900 may also include a wheel 1001 operatively connected to the rod 910 and including a plurality of spokes 1010. The wheel 1001 may rotate in a direction tangential to the spokes 1010 while the cup on the cup arbor 600 may rotate about an axis parallel to the spokes 1010 when engaged by the rod 910. A mandrel 600 may be attached to the end of each spoke 1010. In the embodiment shown, the inner cup 1020 of the double wall cup is ready to be bonded to the outer wrap 1022 of the double wall cup (fig. 10).

As the belt 912 is pulled, the sled 908 rotates in the direction of the narrow arrow, causing the rod 910 to also rotate, which in turn rotates the inner cup 1020 on the mandrel 600. As the inner cup 1020 rotates, the glue gun 505 sprays the thermally expandable material 216 onto the inner wall of the inner cup 1020. The material application gun or nozzle is off-center to enable a plurality of individual lines 216 of adhesive to be applied to the outside of the inner cup 1020 with a predetermined spacing between the lines. The Revolutions Per Minute (RPM) of the rotational speed of the lever 910 may include tight tolerances, for example, time may be such that the coating from the gun 505 is properly spaced and evenly distributed: not too thick and not too thin. The wheel 1001 may then be rotated to repeatedly act on the inner cup 1020 of the next spoke, for example, clockwise (in the direction of the fat arrow). Each coated inner cup 1020 may then be inserted into the outer wrapper immediately following it, thereby forming a double wall cup.

The formed double wall cups can then be shipped, stacked, bagged, and placed in cartons that will be shipped on a trolley. As will be explained with reference to fig. 11, microwave or other heat may be applied to post-activate the thermally expandable material 216 at various stations after the cup is formed, in addition to before the cup is formed.

Fig. 11 is a flow chart 1100 of the multiple stations of the method of manufacturing the packaged product container where, or during which, microwave heat may be applied, thermally expandable microspheres (or other thermally expandable microparticulate material) incorporated as part of the substrate layer into the packaging substrate and/or container expand. The preparation method comprises transporting the packaging substrate or container between the work stations. Numbering the stations in sequence does not imply that a certain order is required unless the order is indicated. Microwave heat may be applied to the substrate or container at more than one station during the manufacturer's combined process so that the thermally expandable material may be expanded during more than one manufacturing stage to achieve a desired final degree of expansion of the thermally expandable material.

In addition to the first workstation 1120, the machine system 400 may include a printing workstation 1125 configured for printing the substrates used to prepare the containers that will ultimately be assembled for shipment. The printing ink may comprise thermally expandable microencapsulated microparticles. Microwave heater 427 may be used to heat the sheet material and securing material during or after printing so that the microspheres or other thermally expandable compound within the printed material expand at least to some extent.

As discussed with reference to fig. 4, the second workstation 430 may be configured to apply or laminate the coating in any pattern to the already formed packaging substrate material. The coating or laminating process may include the application of additional layers of sheet material or coating/laminating multiple layers of substrates to improve the structural integrity and appearance of the resulting packaging material. Microwave heaters 427 may then be used at some subsequent point to heat the sheet material and coating applied during lamination to expand the microspheres or other thermally expandable compounds within the coating and/or securing material at least to some extent.

The die cutting station 1140 may be configured to perform die cutting (rotary die cutting or planar die cutting or both), the result of which may include a blank 1143 that may be formed into a final product. The blank may comprise a blank 1143 such as, for example, a cup, container, panel, blister, tray, bag, or beverage container handle, among others. The blank may then be heated using microwave heater 427 to cause the microspheres or other thermally expandable compounds within any coating, laminating or securing material of the blank 1143 to expand at least to some extent while not already expanded.

The forming station 1150 may be configured to form a final product 1153 from the blanks 1143. The final product 1153 may then be heated using microwave heaters 427 to cause the microspheres or other thermally expandable compounds within any coating, laminating, or securing materials of the final product 1153 to expand at least to some extent while not already expanded.

The boxing workstation 1160 may be configured to package the end product 1153 into shipping cartons (e.g., conventional slotted cartons). The output of the boxing workstation 1160 includes stacked cartons 1163 filled with finished products 1153. The entire shipping carton 1163 may be heated using microwave heaters 1127 during the packaging process or after it is stacked to cause the microspheres or other thermally expandable compounds within any coating, laminating, or securing materials of the final product 1153 contained in the shipping carton 1163 to expand at least to some extent while not already expanded.

Where the container is a cup or container, it may be conveyed through a conduit that is part of the forming station 1150. Microwave heater 427 may be oriented about a portion of the conduit through which the cups or containers travel to heat the thermally expandable material, without having been expanded, on the way the cups or containers are conveyed through the conduit for packing and palletizing (palletizing).

The palletizing station 1170 may be configured to receive cartons of the stacked product containers onto a trolley. The trolleys of stacked cartons or containers may be heated using microwave heaters 427 to cause the microspheres or other thermally expandable compounds within the individual products contained in the cartons to expand at least to some extent while not yet expanded, but for the entire trolley at a time. The trolley is then loaded onto a truck for transport at a transport workstation 1290.

Fig. 12-15 include various schematic diagrams of microwave application waveguides that can be used for the microwave applicator 427. The microwave heaters 427 may be mounted about one or more conveyor belts 1213 that convey the paperboard, sheet material, or other substrate through the machine system 400. The microwave heater 427 may be of the flat plate type having a slot 1405 through which the web, sheet or blank material passes. Fig. 14 shows a side view perpendicular to the machine direction, and fig. 15 shows a front or machine direction view of the microwave heater 427. The microwave applicator 427 may include a plurality of microwave waveguide channels that are coupled together to provide an increased surface area with which microwave energy is applied to the sheet material. The dimensions of microwave applicator 427 shown in fig. 12-15 are exemplary only and not intended to be limiting. When a tubular microwave applicator is used for 427, the tubular applicator is generally circular in cross-section and there is an opening through the applicator to allow the product to pass.

Fig. 16 is a flow diagram of an example of a method for producing a multi-layer sheet material in a method that includes microwave heating of the multi-layer sheet material to accelerate expansion of the thermally expandable adhesive or coating. The dashed lines in fig. 17 represent alternative ways in which one or more steps of the method may be bypassed. At block 1600, a first sheet of material may be loaded into the machine system 400, and may be corrugated. At block 1610, a securing material may be applied to one side of the first sheet of material. The fixing material may be a thermally expandable adhesive or coating, which may comprise starch and microspheres or some other composition. At block 1620, a second sheet of material may be applied to the first sheet of material. If the two-ply sheet material has a securing material that includes a thermally expandable coating, the two-ply sheet material may be heated with microwave energy to expand the thermally expandable adhesive/coating at block 1630. At block 1640, the double layer sheet material may be transferred for processing into a final product, such as by printing, die cutting, removing from a blank, and/or assembling.

At block 1650, a second securing material may be applied to one side of the double layer sheet of material. The second fixing material may be a thermally expandable adhesive or coating, which may include starch and microspheres and/or some other suitable composition. After this step, the multiple layers of sheet material may be advanced through steps, heated and/or laminated without first applying a third layer of sheet material. Otherwise, at block 1660, a third sheet of material is applied to the exposed side of the first or second sheets of material. At block 1670, if the second securing material is a thermally expandable adhesive or coating, the multi-layer sheet material may be heated with microwave energy to expand the thermally expandable adhesive or coating. At block 1680, the multiple layers of sheet material may be laminated. That is, if the first, second, and third sheets of material have been applied together, the first, second, and third sheets of material may be laminated together at block 1680. At block 1640, the multi-layer sheet material or substrate may then be processed into a final product, which may include printing, die cutting, removing blanks, and/or assembling. Additionally or alternatively, the multi-layer sheet material or substrate may be microwaved at any of these multiple stages (or stations), including but not limited to printing, coating and/or laminating, die cutting, forming, boxing the RSC, and making a pallet truck ready for cartons or containers for transport.

For example, the resulting multi-layered sheet material may be further processed, such as by applying a package blank to the sheet material and then removing the package blank and assembling the blanks into a final product (block 1640). The final product of the process (which may be, for example, a cup, container handle, container sleeve, blister, tray, etc.) may be comprised of one or more layers of one or more of the foregoing materials. Where multiple layers of material are used, they may be bonded (e.g., without limitation, laminated, glued, or otherwise secured) together to improve strength.

As described above, the use of the insulating material 216 may help reduce the thickness of paper required to make containers, sleeves, and the like while maintaining the bulk of the laminated substrate and providing a more rigid feel to the consumer. The insulating material 216 may also improve the insulating properties of the container and help keep the beverage or food warm or cold for longer periods of time depending on the application. The substrate may be made of natural fibers, synthetic fibers, or both (e.g., cardboard with or without recycled fibers, natural or bleached paper, or natural or bleached paperboard). The features and methods disclosed herein collectively add significant flexibility and versatility to conventional conversion processes and broaden the options available to packaging converters to address any limitations in substrate supply in the supply chain. For example, a laminate of two thin inner liners can be used to make a bulkier paper with an expanded adhesive between the thin papers, which has the same or better thermal insulation as the thicker paperboard. The thermal interlayer wrap can be made of such a material, which can have greater flexibility than paperboard. As an additional example, a composite may be made from a low gauge polymer coated SBS board and clay coated news board with an expandable adhesive therebetween. As another example, a beverage cup for hot or cold fluids may be manufactured to include a laminate of two different low gauge paperboard with an expandable adhesive therebetween. The expandable adhesive can be activated during lamination, before or after cup formation. The expandable adhesive can also be applied in a pattern to achieve local expansion and thus local stiffness and insulation improvement.

While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments, variations, and implementations are possible within the scope of the invention. For example, unless otherwise indicated, the steps of a method illustrated in the figures or reflected in the claims below do require a particular order of execution to be presented. The disclosed steps are listed as examples such that additional or different steps may be performed, or the steps may be performed in a different order.

Claims (22)

1. A method of making, comprising:

placing the blanks on a conveyor system;

applying thermally expandable particles in a pattern to the matt as the matt is moved beneath the applicator by the belt of the vacuum conveyor system;

heating the particles with a microwave heater to expand the particles; and transporting the blanks along the conveyor system to a product forming machine, which assembles the product from the blanks.

2. The method of claim 1, further comprising:

the expanded particles are compacted to a uniform height by a variable size device prior to delivering the body to a product forming machine.

3. The method of claim 1, wherein applying the particles further comprises leaving gaps in the pattern of applied particles, the gaps configured to correspond to raised strips of a mandrel that holds the green body from the side to which the particles are applied with a vacuum to move the green body within the product forming machine.

4. The method of claim 3, further comprising:

the belt speed of the vacuum conveyor system is controlled to apply the particles uniformly in the pattern to each blank.

5. The method of claim 1, wherein the blank comprises an outer wrap and the product comprises a double wall cup.

6. A blank moving device comprising:

a frusto-conical mandrel; and

a raised strip formed on one side of the frusto-conical mandrel, the raised strip including vacuum holes adapted to draw a side of the blank including an applied pattern of expanded microencapsulated particles with vacuum suction.

7. The blank moving device of claim 6, wherein the raised strip is configured to match the gaps left in the application pattern of expanded microencapsulated particles on the side of the blank.

8. The blank moving device of claim 6, wherein the height of the raised band above the surface of the frustoconical mandrel comprises at least about the height of the expanded microencapsulated particles.

9. The blank moving device of claim 6, wherein the raised band comprises a first band, further comprising:

a second band formed at another location on the side of the frusto-conical mandrel for aligning the seam of the outer edge of the blank.

10. A method of making a double wall cup having a thermally expandable material between an inner wall and an outer wall, comprising:

forming an outer wrap for a double wall cup;

forming an inner cup;

applying an adhesive to the outer surface of the inner layer with an applicator, the adhesive having microencapsulated heat-expandable particles;

conveying the inner cup within a cup forming machine and inserting it into the outer wrap; and

the double-walled cup is heated with a microwave heater to expand the particles in the binder.

11. The method of claim 10, wherein the binder comprises a coating.

12. The method of claim 10, further comprising:

the double-walled cups are conveyed through a pipe, passed through a microwave heater to expand the particles and then stacked ready for bagging.

13. The method of claim 12, wherein the double wall cup is heated with a microwave heater while stacked with other double wall cups.

14. The method of claim 12, further comprising:

the double wall cups are packaged in cartons, wherein each carton is heated with a microwave heater to activate and expand the heat expandable adhesive in the double wall cups.

15. The method of claim 14, further comprising:

the cartons of the double wall cups with the heat expandable adhesive are stacked onto a trolley where the adhesive in the cups is activated and expanded with a microwave heater.

16. The method of claim 10, further comprising:

rotating a mandrel past the applicator to facilitate application of adhesive to the outer surface of the inner layer; and

the speed of rotation is controlled to apply the adhesive uniformly.

17. The method of claim 10, wherein the microwave heater is selected from the group of different types of industrial microwave heaters consisting of tubular, planar, and non-tubular microwave applicators for radiating a single stream or a stack of cups.

18. A method for manufacturing a packaging substrate material and a container, comprising:

passing at least first and second sheet materials into a conveyor-type machine system;

forming a substrate from the first and second sheet materials and from an adhesive comprising microencapsulated, thermally expandable particles located between the first and second sheet materials;

forming a packaging container from the base;

conveying the packaging container to be transported; and

heating the adhesive with a microwave heater at some point during the passing, forming and transporting process to expand the microencapsulated heat expandable particles, wherein the microwave heater is used at or between one or more stations selected from the group consisting of printing, coating or laminating, die cutting, forming, stacking, boxing and palletizing.

19. The method of claim 18, wherein the microwave heater comprises a microwave applicator surrounding a space through which the substrate passes or through which the packaging container passes.

20. The method of claim 18, further comprising treating the substrate comprising:

coating or printing on the multi-layer substrate with a material comprising said microencapsulated heat-expandable particles;

die cutting the multilayer substrate to produce a green body; and

the packaging container is formed from the blank.

21. The method of claim 20, wherein the packaging container is selected from the group consisting of: folding carton containers, hot and cold cups, blisters, recessed sleeves, bags and boxes.

22. The method of claim 20, further comprising:

the multi-layer substrate is laminated after printing and prior to die cutting.