MOLECULAR SIEVE CONTAINING STRUCTURE FOR ORGANOLEPTIC SCAVENGING

Abstract: An organoleptic multilayer paperboard based packaging uses a molecular sieve powder to adsorb low molecular weight oxidation products formed during the extrusion coating process. Figure 1 shows a polyethylene layer (10), adjacent a paperboard layer (12), and a low density polyethylene layer that contains a molecular sieve powder (14).

Description: MOLECULAR SIEVE CONTAINING STRUCTURE FOR ORGANOLEPTIC SCAVENGING BACKGROUND OF THE INVENTION Absorbents, such as molecular sieves (ecolites) , clays, silica and diatomaceous earth are used for removal of low molecular weight oxidation products formed during processing such as extrusion coating of polyolefins; removal of off-tastes and odors from that develop as the product in a structure degrades (such as hexanal from lipid oxidation or sulfides from protein degradation) / and removal of ink and/or varnish off-odors that can be transferred from glass to matte during storage in roll form or as flat blanks. Product producers of cereals, juices, and the like, have complained of polymer odor, and taste, in paperboard based gable-top cartons. More specifically, the odor and taste have been called λΛ plastic-like" . The gable-top cartons predominately have a polyolefin based product contact layer, such as low- density polyethylene. The off odor and off flavor has been identified to be low molecular weight volatile oxidation products such as hexanal. In addition, odors and tastes caused by degradation of the food products contained in the package is also a problem. Lipid oxidation in cereal causes the formation of hexanal which imparts a distinct odor to the cereal. Thirdly, unwanted odor causing compounds from printed substrates has also been identified as a problem. Lastly, the removal of unwanted compounds in a product that are not the result of product degradation have also been recognized to be a problem. Examples of this include water that contains off-flavor compounds or water that contains by-product compounds from the packaging or purification processes. Several patents exist that discuss the incorporation of a zeolitic molecular sieve into a plastic material for removal of odor causing compounds produced during manufacturing of the plastic material. U.S. Patent No. 5,750,611 relates to thermoplastic compositions having adsorption agents to reduce offensive odors and flavors . U.S. Patent No. 5,948,846 relates to a polyolefin based composition and process for the manufacture of shaped objects form this composition. Described is the use of 0.05-2 parts by weight of zeolite in polyolefins containing 0.1-5 parts by weight fatty acid based lubricating agent for improved organoleptics in shaped objects and bottle caps. U.S. Patent 5,436,282 relates to eliminating odor/taste producing substances in plastic materials and zeolites. Described is the addition of 0.05-0.3% by weight zeolite to a molten plastic to reduce emission of odor/taste producing substrates in plastic water pipes and bottles. U.S. Patent No. 5,834,079 relates broadly to zeolite in packaging fibers. International Publication 94/03534 relates to synthetic resin compositions having an adsorptive effect and packaging films prepared therefrom. The use of 0.5-20% zeolite in low or medium density polyethylene or polypropylene to bind gases formed during the ripening and decomposition of fresh fruits is discussed. None of the patents or publications discussed describe paper based packaging structures and more specifically disclose extrusion coating as the processing technique. It is an objective of the present invention to produce a paper based packing structure which contains a molecular sieve added during extrusion coating which can trap non-specific low molecular weight organics inside a zeolite structure and therefore lead to an improved product flavor. It is a further object of the present invention to disclose a paper based packaging structure that incorporates a molecular sieve that removes compound such as hexanal to extend product shelf life. It is a further object of the present invention to incorporate a molecular sieve in a paper based packaging structure to remove undesirable ink odors which affect packaged product food quality. SUMMARY OF THE INVENTION An adsorbent, such as a molecular sieve, is used in a paperboard laminate for removing compounds such as hexanal to extend product shelf life. The adsorbent allows for the removal of low molecular weight oxidation products formed during processing such as extrusion coating of polyolefins, such as low density polyethylene, high density polyethylene, linear low density polyethylene, metallocene, polypropylene, etc... The molecular sieve is incorporated into the paperboard packaging structure during extrusion. The molecular sieve powder was incorporated into the product contact low density polyethylene layers in amounts ranging from 5,000 pp to 10,000 ppm in the structures. BRIEF DESCRIPTION OF THE FIGURES FIGURE 1 is a cross-section of a laminate for a packaging structure embodying the present invention; FIGURE 2 is a cross-section of a laminate for an alternate embodiment of a packaging structure of the present invention; FIGURE 3 is a cross-section of a laminate for an alternate embodiment of a packaging structure of the present invention; FIGURE 4 is a cross-section of a laminate for an alternate embodiment of a packaging structure of the present invention; and FIGURE 5 is a cross-section of a laminate for an alternate embodiment of a packaging structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION A paperboard packaging structure that is produced by extrusion or coextrusion coating that incorporates a molecular sieve for organoleptic scavenging is produced. In a preferred embodiment molecular sieve powder, for example, Abscents 3000™ (sold by UOP) or Smellrite™ (sold by UOP) is compounded with a polyolefin polymer, such as low density polyethylene using a twin screw extruder. A 10% mastibatch is dry blended with the low density polyethylene and cast films (of 1 mil thickness) containing 1,000 ppm (0.1%), 5,000 ppm (0.5%), and 10,000 ppm (1.0%) molecular sieve powders were made. As shown in the table below (Table 1), the aldehydes octanal, nonanal, and dicaval were removed with greater than 70% efficiency in the three films compared to a low density polyethylene control film. TABLE 1 A second test was such where a 0.5 gram section of each film was. placed in a 20 ml glass headspace vial and sealed with a septum. A model solution containing twelve compounds that could represent either flavor components of food products or solvents used in printing inks and varnishes was spiked into the headspace vials at levels of 3-4 micrograms each compound. The vials were stored at 140°F for 2 hours to aid in volatilizing the model solution, then tested for scavenging relative to the LDPE control film. Results are shown in the table below. All three films exhibited significant removal of the low molecular weight compounds. d-Limonene, a desirable flavor component in orange juice, is too large to fit into the pores of the molecular sieve and was not removed. Table 2 The ability of the films to scavenge from an aqueous solution at both room temperature and refrigerated conditions was evaluated by placing 0.5 gram film in 15 ml water and spiking the sample with u.5-10 micrograms each component in a model solution. Samples were stored for 2 hours at 73°F or 40°F then evaluated, with results shown in the tables below. Table 3 - Films stored at 73°F Table 4 - Films stored at 40°F A gable top paperboard carton containing a 22 lb/3 sf LDPE product contact layer with and without the addition of 1% molecular sieve powder was extrusion coated at 600°F. Cartons were filled with spring water and stored at 100°F for 3 hours then at room temperature overnight before evaluation by a consumer taste panel using a standard triangle test. A statistically significant difference between the LDPE control and the structure containing 1% molecular sieve powder was detected at the 95% confidence level. The LDPE control was described by panelists as waxy and having a strong plastic taste and odor. Analytical testing, reported in the table below, showed a significant reduction in five low molecular weight components within the water from the 1% cartons. Table 5 The following paperboard packaging structures embody the present invention (all weights are given in lbs/3msf) . A standard mile carton is made from a laminate and the laminate 20 contains: a glass layer of low density polyethylene (9-12 lbs) 10; a basestock paperboard substrate (166-265 lbs) 12; and a matte or product contact layer of low density polyethylene (16-22 lbs) 14 containing 1,000-10,000 ppm of a molecular sieve powder added at extrusion (Figure 1) . A second structure with added oxygen barrier properties, the laminate 35, includes: a glass layer of low density polyethylene (9-12 lbs) 22; a basestock paperboard substrate (166-287 lbs) 24; a layer of a polyamide, such as nylon 26, on the interior surface of the substrate (5 lbs) ; a tie layer 28, such as a modified polyethylene (1.5 lbs); and a matte or product contact layer of low density polyethylene (5-22 lbs) 30 containing 1,000 to 10,000 ppm molecular sieve powder added at extrusion (Figure 2) . A third embodiment of a paperboard container packaging structure made from a laminate 40 includes: a glass layer of low density polyethylene (9-12 lbs) 42; a basestock paperboard substrate (166-287 lbs) 44; a layer of a polyamide, such as nylon 46, on the interior surface of the substrate (5 lbs) ; a tie layer 48, such as a modified polyethylene (1.5 lbs); a layer of a low density polyethylene polymer (12-18 lbs) 50; an organoleptic layer of low density polyethylene (4 lbs) containing 1,000 to 10,000 ppm molecular sieve powder added at extrusion 52; a tie layer (1.5 lbs) 54; a layer of high barrier ethylene vinyl alcohol copolymer (2 lbs) 56; a tie layer (1.5 lbs) 58; and a matte or product contact layer of low density polyethylene polymer (4 lbs) 60 containing 1,000 to 10,000 ppm of a molecular sieve powder added at extrusion (Figure 3) . The paperboard packaging structure can also contain a foil barrier layer and the laminate 62 include: a glass layer of low density polyethylene (9-12 lbs) 64; a basestock paperboard substrate (128-287 lbs) 66; a layer of low density polyethylene (12 lbs) 68; a tie layer (2-3 lbs) 70; a foil layer 72; a tie layer 2-8 lbs) 74; and a matte or product contact layer of low density polyethylene (15-25 lbs) 76 containing 1,000 to 10,000 ppm of a molecular sieve powder added at extrusion (Figure 4) . A further embodiment is a laminate 80 which includes a metallized oriented polypropylene layer and is made from: a glass layer of low density polyethylene (9-12 lbs) 82; a basestock paperboard substrate (128-287 lbs) 84 a layer of low density polyethylene (12 lbs) 686 a tie layer (2-3 lbs) 88; a layer of metallized oriented polypropylene 90; a layer of a polyolefin plastomer (2-8 lbs) 92, such as one sold by Dow under the tradename Affinity P71450; and a matte or product contact layer of low density polyethylene (15-25 lbs) 94 containing 1,000 to 10,000 ppm of a molecular sieve powder added at extrusion (Figure 5) . The unique paperboard packaging structure may also include combinations of different types of molecular sieves. While the invention has been disclosed in various preferred paperboard packaging structures, it will be obvious to those skilled in the art that modifications, additions and deletions may be made herein without departing from the spirit and scope of the invention as set forth in the following claims.

Claims: WHAT IS CLAIMED IS: 1. A paperboard packaging container, having organoleptic scavenging properties made from a laminate comprising: a glass layer of a polyolefin polymer; a paperboard substrate; and a product contact layer of low density polyethylene polymer containing from 1,000 to 10,000 parts per million of a molecular sieve powder, the molecular sieve powder being added to the low density polyethylene polymer during extrusion. 2. The paperboard packaging container as claimed in claim 1, further comprising: a layer of nylon; and a tie layer, extruded between the paperboard substrate and the product contact layer. 3. The paperboard packaging container as claimed in claim 2, further comprising: an interior layer of low density polyethylene; an interior layer of low density polyethylene containing from 1,000 to 10,000 parts per million of a molecular sieve powder, the molecular sieve powder being added to the interior layer of low density polyethylene during extrusion; a second tie layer; a layer of high barrier ethylene vinyl alcohol copolymer; and a third tie layer, all extruded between the tie layer and the product contact layer. 4. The paperboard packaging container as claimed in claim 1, further comprising: an interior layer of low density polyethylene; a tie layer; a foil layer; and a second tie layer extruded, or laminated, between the paperboard substrate and the product contact layer. 5. The paperboard packaging container as claimed in claim 1, further comprising: an interior layer of low density polyethylene; a tie layer; a layer of metallized polypropylene; and a layer of a polyolefin plastomer extruded between the paperboard substrate and the product contact layer.

Inventors: BUSHMAN ALEXANDER CRAIG, CALLANDER DERRICK BERNARD, REIGHARD TRICIA SUSAN, SAND IRVING DANIEL, BUSHMAN, ALEXANDER, CRAIG, CALLANDER, DERRICK, BERNARD, REIGHARD, TRICIA SUSAN, SAND, IRVING, DANIEL
Applicants: INT PAPER CO, INTERNATIONAL PAPER COMPANY
Application year: 2001
Main classification: B32B5
IPC codes: B32B27, B32B29, B65D65