Patent Publication Number: US-2006000878-A1

Title: Insulating and light reflective material for packaging applications

Description:
BACKGROUND OF THE INVENTION  
      1) Field of the Invention  
      The present invention relates to a material for packaging applications, more particularly, to an insulating and light reflective material that can be used to manufacture insulating containers.  
      2) Description of the Prior Art  
      Since an important proportion of edible perishables are transported from their production site to a consummation site, containers have been developed with insulating properties. It is highly desirable to use a lightweight container material to reduce the transportation costs. The container material must also be strong enough to safely carry the perishable goods, inexpensive, and, preferably, fully recyclable for environmental concerns.  
      Honeycomb materials, consisting of a honeycomb core laminated between to linerboards as face members, are well-known for their heat insulating properties due to their numerous individual dead air space cells. They are also lightweight materials since, as mentioned above, they contain mainly air space cells. Moreover, their mechanical properties are often superior to the mechanical properties of other lightweight materials. Honeycomb materials probably offer the best strength to weight ratio of any material available. Honeycomb materials offers an eco-friendly alternative to traditional packaging materials.  
      Honeycomb materials for shipping containers are usually made of kraft paper which is usually characterized by a brownish color. The brown color is not however light reflective and an important proportion of the light that reaches the honeycomb container is absorbed by the latter. Consequently, the temperature of the container and its content slowly increases. The increasing temperature may permanently damage the perishable goods.  
      Panels covered with an highly reflective grade aluminum foil on their outer surface were disposed on the honeycomb material to reflect light. These panels were usually made of Kraft paper and helped to bond the aluminum foil to the outer surfaces of the face members perpendicular to the honeycomb core (See for instance U.S. Pat. Nos. 5,000,372, 5,429,264, and 5,492,267).  
      With the growing environmental concerns, it is highly desirable to provide containers that are fully and easily recyclable. This is not the case with the honeycomb material covered with aluminum foil since the foil must be removed before recycling the honeycomb material. Moreover, for environmental and economic concerns, it is highly desirable to minimize the quantity of material used to manufacture containers for packaging perishable goods. In the above mentioned patents, the aluminum foil is laminated on an additional Kraft paper bonded perpendicular to the honeycomb material.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a new packaging material that has light reflective and insulating properties.  
      It is another object of the present invention to provide a new packaging material that is lightweight, strong, and inexpensive.  
      It is a further object of the present invention to provide a new packaging material that is fully recyclable and that requires minimum raw material for the manufacturing process.  
      According to an aspect of the present invention, there is provided a light reflective and insulating paperboard honeycomb material. The material comprises a core portion including a honeycomb material having two faces and two face members, each having an inner surface and an outer surface. Each inner surface is laminated on a respective face of the core portion and at least one of the outer surfaces is light color.  
      According to another aspect of the present invention, there is provided a method to provide a reflective and insulating material. The method comprises the steps of: providing a core portion including a honeycomb material having two faces; providing two face members, each having an inner surface and an outer surface, at least one of the outer surfaces being light color; and laminating each of the inner surface of the face members on a respective face of the core portion.  
      According to a further aspect of the present invention, there is provided a paperboard container having side walls, a bottom wall, and a top wall. At least one of the wall comprises a core portion including a honeycomb material having two faces; and two face members, each having an inner surface and an outer surface. Each inner surface is laminated on a respective face of the core portion and at least one of the outer surfaces is light color. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:  
       FIG. 1  is a perspective view, partly sectioned, of a light reflective and insulating material according to a first embodiment of the present invention;  
       FIG. 2  is an exploded perspective view of the light reflective and insulating material according to the first embodiment of the present invention;  
       FIG. 3  is a perspective view, partly sectioned, of the light reflective and insulating material according to a second embodiment of the present invention; and  
       FIG. 4  is a perspective view of a container, partly sectioned, made with the light reflective and insulating material according to the first embodiment of the present invention. 
    
    
      It will be noted that throughout the appended drawings, like features are identified by like reference numerals.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring simultaneously to  FIGS. 1 and 2 , it will be seen that a light reflective and insulating material  10  of the invention includes a core portion  12  and two face members  14 . The core portion  12  is an honeycomb type material  16  with two faces  20   a ,  20   b . The honeycomb type material  16  is preferably a grid of hexagonal cells made of any wood fiber based materials such as cardboard, kraft paper, recycled paper, medium, chipboard, bleached or not, and the like. As it will be easily understood by one skilled in the art, any other lattice structure and/or geometrically patterned structure which provides enhanced strength for supporting and protecting loads and creates an air space as a result of that structure can be used.  
      The diameter and the height of the cells can be modified to obtain predetermined mechanical properties. A small diameter will be associated with a high resistance whereas a large diameter will have lesser resistance. A higher cell provides a stronger resistance to impact and vibration than a lower one.  
      The face members  14  are linerboards, each having two surfaces  24   a ,  24   b . One surface  24   a  of each face member  14 , the inner surface, is bonded to a respective face  20   a ,  20   b  of the core portion  12 . The other surfaces  24   b  of each face member  14  are the outer surfaces of the insulating material  10 .  
      At least one outer surface  24   b  is light color to increase the light reflection of the insulating material  10 . Preferably both outer surfaces  24   b  are light color. The outer surfaces  24   b  are preferably white since it reflects all colors of light. As it is well known, the color of an object is only the light wavelengths that are reflected from that object. A white light is made up of all visible (and invisible) wavelengths all mixed together. So an object that appears white is reflecting all of the incident wavelengths and absorbing nothing (or very little). Therefore, the face members  14  characterized with at least one light color outer surface  24   b  are highly reflective and increase the thermal insulating attributes of the material  10 . For example, a fully bleached paperboard with a double blade coating on the topside, having a thickness around 300 μm, a brightness of 85% and a gloss of 50%, can be used as a face member  14 .  
      Even if white is the preferred color, other light colors such as prime rose, straw yellow, pale pink, pale blue, softly beige and the like can be used.  
      When the core portion  12  is bonded between two face members  14 , the resulting material  10  is highly crush resistant due to the evenly spaced, perpendicularly disposed rigid walls of each honeycomb cell. Face members  14  strengthen the honeycomb core portion  12  by being disposed perpendicular to the latter, thereby ensuring an even distribution of weight over the honeycomb structure. Bonding of the face members  14  on the core portion  12  can be accomplished by known conventional methods such as by gluing.  
      The air spaces formed between both face members  14  creates an enhanced insulting effect since air is a poor conductor of heat and thus has valuable insulation properties.  
      One skilled in the art will understand that the material  10  can include only one face member  14  having an outer surface  24   b  that is light color. In that case, when manufacturing a container  30  ( FIG. 5 ) from the material  10 , the face member  14  having the light color outer surface  24   b  is preferably disposed on the outside of the container  30 .  
      One skilled in the art will appreciate that the core portion  12  can be an honeycomb type material  16  with two linerboards (not shown) laminated on its two faces  20   a ,  20   b . The face members  14  can be only light color paper sheet adhesively bonded on the linerboards. A face member  14  can also be a linerboard with a light color paper sheet adhesively bonded thereon.  
      The light color face member  14  can also be obtained by coating of a usual flat printing cardboard. The coating can be a water based coating or an extrusion coating.  
      Advantageously, a material that is water-based coated is recyclable and repulpable. A water-based coating can consist of applying a paint on at least one surface of a cardboard. For the present invention, the paint applied is light color.  
      The extrusion is an hydrophobic process wherein a polymer is applied on at least a surface of a cardboard. For the present invention, the polymer applied preferably has a light color pigment. For example, the polymer can contain TiO 2  particles giving a white coating to the cardboard where it is applied. The extrusion coated material preferably has biodegradable properties. Either a polylactic acid (PLA) resin, a polyhydroxyalkanoate (PHA) resin, a polyhydroxybutyrate (PHB) resin, a starch resin, polyester resin or any other biodegradable product can be used. Other polymers such as polyethylene, polyethylene tetraphalate, nylon containing or not white mineral charges can also be used. The choice of the polymer used is carried out by considering the desired barrier properties.  
       FIG. 3  shows another embodiment of the material  10   a  wherein one face member  14   a  is constituted of a corrugated medium  40  and two linerboards  42   a ,  42   b  laminated on each face of the corrugated medium  40 . The second face member  14   b  is a linerboard. The combination of the face member  14   a  and the core portion  12  increases the mechanical properties of the material  10   a . At least one of the face member  14   b  and the linerboard  42   b  that is not laminated on the core portion  12  is light color. Preferably, both the face member  14   b  and the linerboard  42   b  that is not laminated on the core portion  12  are light color. One skilled in the art will understand that the face member  14   a  can have either one or two light color linerboards  42   a ,  42   b  laminated on the corrugated medium  40 . Still more preferably, the whole material  10  is light color.  
      The outer surfaces  24   a ,  24   b  of the face members  14  are preferably flat to prevent the distortions that increase the light absorbtion.  
      The insulating materials  10 ,  10   a  can be either manufacture manually or continuously on any apparatus (not shown) well known by those skilled in the art.  
      Referring to  FIG. 4 , there is shown an example of an insulated container  30  made with the insulating material  10  of the invention.  
      Preferably, the insulated material  10  is wholly recyclable or biodegradable. It can be used as a packaging material due to its high strength for resisting stresses and strains.  
      The insulated material  10  is preferably made of any wood fiber based materials such as cardboard, kraft paper, recycled paper, medium, chipboard, bleached or not, and the like. It can be made entirely of recycled material. The material  10  can be impregnated with a resin to improve its resistance to water, grease or fire, its gas and vapor barrier properties, its non-slip properties, and the like.  
      One skilled in the art will appreciate that the use of a light density chipboard cardboard reduce the heat transfer in the insulating material  10 . This material can be treated with a water-based coating or a resin coating as described hereinabove.  
      The choice of the materials to join together the various components of the composite material  10  can also be made on the basis of recyclability or biodegradability. The adhesive must ensure good adhesion of paper to paper, remain on the top of the honeycomb structure, and bond very rapidly. Adhesives such as polyvinyl alcohol (PVA), stamp glue, dextrin, and polyurethane can be used to assembly the material  10 . Hot melt adhesives such as polyolefin and ethylene vinyl acetate (EVA) can also be used.  
      One skilled in the art will appreciate that the core portion  12  can be light color to delay the light absorption and maintain during a longer time period the insulating properties of the material  10 .  
      The insulated material  10  combining light reflective and insulating properties is adequate as a packaging material for shipping perishable goods. Moreover, it is a cost-efficient packaging material due to its lightweight and it is wholly recyclable or biodegradable.  
      Accordingly it is understood that the invention is not limited to the aforementioned material and container configurations and alternatives are possible.  
      The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.