US3049429A - Frozen food package - Google Patents

Description

1962 R. DE 5. COUCH ET AL 3,049,429

FROZEN FOOD PACKAGE Filed Aug. 26, 1958 FIG. 1

INVENTORS ROBERT de 8. COUCH MILTON YEZEK FlG'2 BY M ATTORNEY United States 3,049,429 Patented Aug. 14, 1962 filice 3,049,429 FROZEN FOOD PACKAGE Robert de S. Couch and Milton Yezek, Battle Creek, Mich., assignors to General Foods Corporation, White Plains, N.Y., a corporation of Delaware Filed Aug. 26, 1958, Ser. No. 757,180 1 Claim. ((11. 99192) This invention relates to a container for frozen food products having a high moisture content.

In the packaging of many perishable high-moisture products in a frozen condition (for instance, frozen peas, corn, beans and like food products) it is desirable to maintain the moisture content of these products as close to the original moisture content as possible; otherwise, due to the loss of moisture through their packaging material, the product will desiccate and hence toughen during prolonged storage such that they will lack desired eating quality. Heretofore, containers for frozen foods of a high moisture content have been proposed and have proven acceptable in the moisture protection offered, but they are expensive. To illustrate, unprinted carton shells have a wax-coated overwrap with printed matter thereon have been proposed but due to the number of separate packaging operations involved in erecting and filling the carton and applying and sealing the overwrap, the expense of such packaging has been high. More recently so-called poly-coated board has come into use; such a board is coated on one or both faces with a moisture resistant polymer like polyethylene and is printed by any suitable means such as lithography or rotogravure. Here also the expense of fabricating or printing such a board is relatively high. It would be desirable to provide a board which had the faithful reproduction of art work on its outer surface that paper has when it is processed through a rotogravure operation or by lithography. However, board material does not lend itself to efficient printing by such means and, accordingly, its expense is relatively high. I

It is anobject of the present invention to provide an improved container for frozen high moisture food products which is relatively inexpensive to fabricate, provides satisfactory protection against Water vapor transmission from inside the container to outside the container, and is printed in an attractive manner.

A- container meeting the foregoing object and finding wide application in the packaging of perishable frozen food products has now been developed. This container is provided in the form of a container fabricated from a laminated packaging material. This packaging material comprises a paper board ply, a printed paper ply and a moisture-resistant laminating adhesive composition interposed in a continuous film between said plies. The container is fabricated from the packaging material in such a manner that the paper ply bearing previously printed advertising matter forms the outer part of the container wall whereas the paper board ply is the inner ply serving as a structural shell surrounding the packed contents. The aforesaid laminant comprises a wax composition having good water vapor transmission resistance and tackiness, preferably microcrystalline wax, and plasticized properties :such as those offered by blending a polymer like polyisobutylene with the wax so as to retard cracking of the wax at freezing temperatures as well as to retard bleeding of the wax through the printed ply at elevated temperatures. It has been found that a container of this construction provides significantly high protection against egress of moisture from within the package such that the tendency of frozen food to desiccate and hence toughen is arrested. The outer ply of paper is printed prior to lamination by any suitable means such as lithography or rotogravure printing and can have a suitable lacquer applied thereto for gloss and scuff resistance although a dense hard paper is also satisfactory. The paper board ply apparently serves as a reservoir for water absorbed by it from the frozen food and by being immediately adjacent the barrier of moisture-proof substantially continuous laminant, reduces the opportunity of moisture it picks up to penetrate through the laminating packaging material. Rather unexpectedly it has been noted that the packaging material is able to strip cleanly from the frozen food and is not bonded thereto by any ice crystals; it appears that moisture absorbed from the exterior surface of the frozen product reduces the opportunity for a bond between the paper board ply and the frozen product. It appears also that by locating the paper ply and the paper board ply immediately adjacent the wax laminant the porosity of the separate plies and tendency of such plies to transmit moisture is significantly reduced in comparison to constructions such as the overwrap-carton shell structure referred to hereinabove.

The expense of this carton packaging material is considerably reduced since it can be laminated at high production speeds, the paper ply being previously printed in a relatively inexpensive manner in comparison to the printing cost attached to quality printing of heavier packaging material such as paper board.

The paper board forming the inner ply of the laminated material may be any of a wide variety of known kinds. For example, boards made from pure chemical pulp such as bleached and unbleached kraft, soda and sulphite board; boards made from semichemical pulp such as corrugating medium board and bleached semichemical board; board made from waste material such as chip board and jute board; and board made from compositions of waste, groundwood and chemical pulps. Such board is normally specified in weight per thousand square feet and in points thickness (one point=0.00 1 inch); on this basis any of the above types of board in the range of 20-l60 lbs. and 5-40 may be suitable for use depending upon the size of the package, the weight and physical form of the enclosed material, and the conditions to which the package is to be exposed.

The outer ply of the laminated packaging material comprises a suitable paper, in most cases a paper capable of being printed in the range of 20-90 lbs. (basis 24" x 36" x 500-3000 sq. ft.). Various kinds of paper are known, and as examples any of the following can be used: papers made from chemical pulps including, sulphate papers, sulphite papers, sulphate-sulphite combination papers, and soda pulp papers, these'various papers being either uncoated or coated on one orboth sides with a coating comprising clay, titanium dioxide and binder; papers made from chemical pulp or chemical pulp and groundwood which have been calendered or supercalendered, such as publishing papers, .glassine, supercalendered sulphite papers, machine finish sulphitesulphate papers; and machine finish and machine glazed sulphite-sulphate papers.

The laminant is applied to one or both surfaces to be liminated and these surfaces are then juxtaposed in any suitable manner, with or without heat and/ or pressure as may be appropriate to join the plies involved. Various procedures and apparatus for laminating materials together are well known in the art and need not be set forth in detail. For quantity production it will be desirable to laminate strips or sheets running continuously over rolls, the laminant being applied by spraying, dipping or brushing or the pressure of squeeze rolls as may be most convenient.

Suitable laminants include, for example, microcrystalline waxes with added polyethylene, butyl rubber, polyisobutylene and/ or paraffin; polymerized olefins like polyethylene (2,000-21,000 molecular weight); vinyl acetate emulsion, polyamides, butyl rubber emulsions; and like moisture proof adhesives. In general the adhesive should possess substantial resistance to water vapor transmission, be highly tacky, and be free from cracking at C. and below in order to provide a substantially continuous water vapor barrier and in order that the paper ply will not tend to peel at freezing.

Hence, it is essential to the present invention that the laminant be applied in a substantially continuous film to one or both surfaces to be laminated and that when these surfaces are juxtaposed that the film be substantially continuous so that a. substantially impervious barrier is created beneath the outer paper ply. In facilitating this operation it will be found desirable to employ a laminant which is substantially fluid during its application. In addition, this laminant should be sufiiciently plastic to yield to the stresses induced in creasing or folding the packaging material during its fabrication. The laminating composition should possess substantial tackiness whereby the outer paper ply and the inner paperboard ply are permanently located adjacent one another. In this way the plies are advantageously located with respect to the moisture-resistant laminant with the result that there is reduced moisture egress from the carton. A preferred laminant comprises about 91% microcrystalline wax melting at 160-165 F. and about 9% polyisobutylene, the laminant being applied to the paper ply by pressure rolls.

The structure of a package contining a high moisturecontaining, frozen food product according to the present invention will be more readily apparent from the illustration of a preferred embodiment thereof in the accompanying drawing, which forms a part hereof, and in which:

FIG. 1 is a perspective view of a package partly broken away to reveal the contents thereof, and

FIG. 2 is an enlarged, vertical sectional view of the package taken along the line 22 of FIG. 1.

Referring to the drawing, a carton of conventional design is substantially filled with frozen peas 11. The carton 10 includes an inner paperboard ply 12 in contiguous, face-to-face contact with the frozen peas, an outer paper ply 14 capable of being printed, and a layer of laminating material disposed between the paperboard ply 12 and the paper ply 14. The laminating layer '13 is substantially continuous and forms a barrier to the passage of moisture therethrough. Inner ply 12 is not resistant to the transfer of moisture therethrough so that it apparently acts as a reservoir for moisture passing to it from the frozen food product 11. This moisture passes through inner ply 12, but not to the outer ply 14 by reason of the moisture-proof barrier of substantially continuous laminant 13,

A carton of the present laminated packaging material fabricated so that the paper ply is provided on the outside of the carton constitutes a considerable improvement in the art of moisture resistant packaging for frozen foods. The benefits of this construction are an ability to reduce loss of water vapor through the laminated packaging material in a practical manner while offering the packaging economy of eliminating expensive water vapor protection alternatives such as waxed paper overwraps. This leads to substantial savings in the material cost of the packaging material, and operation of the packaging line is simplified and can be speeded up.

The phrase perishable high moisture frozen food product employed in the following claims is intended to cover a wide variety of frozen food products such as frozen peas, corn, beans and the like and in general embraces any such product having a moisture content higher than that of the packaging material of the container and of the atmosphere outside the container. In most instances the rnoisture content of the frozen product will be above at least 8% and in the majority of food products will be above 50% by weight of moisture.

While the present invention has been described with particular reference to specific examples and has been explained by means of theory, it is not to be limited thereby, but reference is to be had to the appended claim for a definition of their scope.

What is claimed is:

The combination of a package and a high moisturecontaining frozen food product positioned within said package, said product tending to emit water vapor therefrom to said package and the ambient atmosphere, said package being fabricated from a sheet of package material erected to form said package, said sheet comprising an inner ply of moisture-absorbent paperboard in contiguous face-to-face contact with said product, an outer ply of paper, and a moisture-resistant flexible laminating adhesive interposed between said plies in a substantially continuous film.

References Cited in the file of this patent UNITED STATES PATENTS 1,693,841 Gaylord Dec. 4, 1928 1,936,375 Beecher Nov. 21, 1933 2,048,123 Howard July 21, 1936 2,098,223 Barnhart Nov. 9, 1937 2,171,775 Wilshire Sept. 5, 1939 2,184,166 Rape Dec. 19, 1939 2,415,387 Graebner et al. Feb. 4, 1947 2,714,952 Ireton Aug. 9, 1955 2,758,032 Pullman et a1. Aug. 7, 1956 2,917,221 Risdon Dec. 15, 1959 2,999,758 Brown Sept. 12, 1961 OTHER REFERENCES Refrigerating Engineering, February 1954, pp. 45-48.

Images