US3015596A - Moisture-resistant container - Google Patents

Description

Jan. 2, 1962 R. DE 5. COUCH ETAL MOISTURE-RESISTANT CONTAINER Filed Nov. 27, 1956 PAPERBoARD'gx FIGJ AREA OF MOISTURE }-PENETRATION INVENTORS ROBERT de S. COUCH MILTON YEZEK ATTORNEY United States Patent Gffice 3,015,596 Patented Jan. 2, 1962 3,015,596 MOISTURE-RESISTANT CONTAINER Robert de S. Couch and Miiten Yezek, Bettie Creek, Mich, assignors to General Foods Corporation, White Plains, N.Y., a corporation of Delaware Filed Nov. 27, 1956, Ser. No. 624,511 2 Claims. ((11. 154-50) This invention relates to a container for a perishable commodity which requires substantial protection against the ingress of water vapor.

This application is a continuation-in-part of copending application Serial No. 464,169, filed October 22, 1954, now Patent Number 2,828,240, issued March 25, 1958.

In the packaging of perishable commodities such as dehydrated food products, ready-to-eat breakfast cereals and like products produced with normally low moisture contents, it has been the practice to employ paper constructions of various types. It is usually the case that the paper packaging material has a moisture content of its own substantially in excess of that of the perishable commodity which it surrounds. As a result the moisture of the packaging material seeks equilibrium with the perishable product. It has been customary where the situation calls for it to employ a pouch suitably sealed against the moisture present in or penetrating the packaging material, but this practice greatly increases the expense of the package. For other commodities a pouch may not be required but, nevertheless, some protection agm'nst the ingress of water vapor is desired.

It appears that the moisture present in a packaging material, in attempting to achieve equilibrium with moisture in the perishable commodity which it contains, will cause the packaging material to absorb additional water vapor from the atmosphere. Thus, in addition to supplying moisture to the perishable commodity it contains, the packaging material will also readjust its own moisture content partly in response to the humidity in the atmosphere surrounding the package and partly in response to the state of its moisture equilibrium with the perishable commodity. As a result the package contents may be subjected further to the ingress of moisture as the packaging material repeats a cyclical absorption of atmospheric moisture, transfer of this moisture through the wall of packaging material, and continual readjustment of moisture equilibrium with the perishable commodity.

It is an object of this invention to provide a container which provides substantial protection against the ingress of water vapor to the perishable commodity contained and yet permits inexpensive packaging material to be employed in its fabrication.

In accordance with the present invention such a container is provided in the form of a carton fabricated from a laminated packaging material. This packaging material comprises a paperboard ply, a paper ply and a moistureresistant laminating adhesive composition interposed in a continuous film between said plies. The carton is fabricated from this packaging material in such a manher that the paper ply forms the outer part of the carton whereas the paperboard ply is the inner ply serving as a structural shell surrounding the package contents.

It has been found that a container of this construction provides significantly higher protection against absorption of moisture from outside the package. It appears that the outer ply of paper offers only a shallow reservoir for any water vapor which may be absorbed from the outside atmosphere. By being immediately adjacent the barrier of moisture-proof laminant, the paper ply presents little if any opportunity to moisture it picks up to penetrate through the laminated packaging material; instead moisture will generally evaporate from the paper ply back into the atmosphere from which it came. The inner ply of the more porous paperboard is exposed to atmospheric water vapor only on those edges of the packaging material exposed to the atmosphere so that any wicking of moisture by the paperboard which may take place is confined to those exposed edges and is comparatively slight. The paperboard ply will seek moisture equilibrium with the package contents and accordingly may undergo an adjustment of its moisture content. However, the opportunity for water vapor to be picked up by this inner ply by penetration through the packaging material is considerably reduced due to the shallow reservoir for atmospheric moisture provided by the outer ply of paper and the barrier oifered by the moisture-resistant laminating adhesive therebeneath.

The paperboard 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: 0.001 inch); on this basis any of the above types of board in the range of 20l60 lbs. and 540 points 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 package material comprises a suitable paper, in most cases a paper capable of being printed in the range of 2090 lbs. per three thousand square feet (basis 24 in. x 36 in.500 sheets: 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 or both 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 super-calendered, such as publishing papers, glassine, super-calendered sulphite papers, machine finish sulphite-sulphate papers; and machine finish and machine glazed sulphite-sulphate papers.

The laminant is applied to one or both surfaces to be laminated 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 alone or with added polyethylene, butyl rubber, a synthetic rubber-like material which is a copolymer of an olefin and a diolefin, polyisobutylene and/or paraifin; parafiin; polyethylene (20002l,000 molecular weight); vinyl acetate emulsion, polyamides, butyl rubber emulsions; and like moisture proof adhesives.

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 sufficiently 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 moistureresistant laminant with the result that there is reduced moisture pickup by the carton.

The structure of the novel container of the present invention will be better understood by reference to 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 the carton, partly broken away to reveal the contents thereof;

FIG. 2 is a vertical sectional view along line- 2-2 of FIG. 1, and

FIG. 3 is a fragmentary, vertical sectional view showing the diminished region of moisture penetration into a carton according to FIGS. 1 and 2.

Referring to the drawing, FIG. 1 shows an erected carton of conventional form and containing cereal flakes 11, a commodity that requires protection against water vapor.

The carton 10 is seen in cross section in FIG. 2, where the carton material is illustrated as consisting of an inner paperboard ply 12, an outer paper ply 14 and a layer 13 of moisture-resistant laminating adhesive. Layer 13 is interposed between plies 12 and 14 as a continuous film in contact with those plies over the entirety of their superposed surfaces. The paper ply 14 is of substantially less thickness than the paperboard ply 12, the latter having a porosity such that it is able to undergo an adjustment of its moisture content to reach a moisture equilibrium with the cereal flakes 11.

The view of a portion of the carton in FIG. 3 illustrates the relative positions of two sheets of carton material when one sheet of material overlies the other. From FIG. 3 it will be seen that the area of moisture penetration is substantially limited to the cut edge of the paperboard ply 12 of the upper sheet, this cut edge being the only exposed portion of the paperboard ply of the sheet material. The area of moisture penetration is greatly increased when the paperboard ply is the outer ply of the laminated sheet, as is the case in conventional, single laminated structures.

The improvements of the present invention are illustrated in the following table showing tests which demonstrate the improvements resulting from having the paper ply on the outside of the fabricated carton versus having the paper ply on the inside of a fabricated carton.

Each carton contained a ready-to-eat breakfast cereal. The codes with the L and without the R designate cartons fabricated with the paper ply on the outside of the carton. The code with the L-R is with the paper ply on the inside of the carton. Each number in the respective carton codes; viz, 25, 26, and 29, indicates the same base board was used. The following is a table showing the composition of each of the plies:

Laminant-1hs./ 3,000 sq. ft. Carton Code Paper Board Surface Total L-25 andL-R25- 35 lb./3,000 .015 Special Bend- 9. 9 12. 3

sq. it. ing chip board60 1b./3,000 sq. ft. L-26 and L-R-26- 551b./f3,000 d0 10. 5 11. 7

sq. t. L-29 and LR29 lb./3,000 do 9.8 13. 8

sq. ft.

The laminant in each case comprised 91% rnicrocrystalline wax melting at 160165 F. and 9% polyisobutylene. The laminant was applied to the paper ply by pressure rolls. In the above column Laminant-lbs./3000 sq. ft., by surface is meant the laminant which is removed from the adjoining surfaces of the paper and paperboard plies, laminant removal being effected by scraping and taking a difference in weight of the carton code before and after scraping; by total is meant the entire amount of laminant applied during the laminating proceses and includes surface laminant as well as that which may have penetrated into the paper and the paperboard.

The foregoing demonstrated improvement in moisture protective properties of wax laminated paperboard, with the paper ply on the outside of the container rather than the inside, is significant. The reduced gain in weight by the package, indicating substantially reduced moisture pickup, corresponds to 106%156% more protection against moisture pickup and in effect results in a considerable increase in the shelf life of the package contents.

Similar improvements in moisture protection is offered by the present carton construction over that afforded by a package which is made of a paperboard shell with a waxed paper overwrap. This is demonstrated by the following tables:

Table A Wax Lami- Control Wax Time of Storage, days nated Cartons. Wrapped Percent H20 Cartons,

Percent H20 1 Packages were drop tested in case lot of 24 from heightof 27 inches; 6 drops; once on each case panel.

The wax laminated cartons of Tables A and B are fabricated with a paper ply on the outside and a paperboard ply on the inside. The laminant and laminating procedure is the same as in the previous example. The paper ply weighed in the order of 55 lbs/3600 sq. ft., and the paperboard was 15 point chip board weighing lbs/1000 sq. ft. The weight of the laminant/3080 sq. ft. was about 10 lbs. (surface) and 13 lbs. (total). The wax wrapped cartons each consisted of a 20 point chip board shell weighing in the order of 80 lbs/1000 sq. ft. with a sealed waxed paper overwrap of sulphite-sulphate paper weighing 25 lbs/3000 sq. ft. coated with 12 lbs. of parafiin/3000 sq. ft. The Waxed paper overwrap had a fiat water vapor transmission rate of 0.3 gm./ 100 sq. in. for 24 hrs. The packages were held at 90 F. in a room having 85% relative humidity for the number of days indicated.

It will be noted from Tables A and B that the Wax laminated cartons of this invention had a much lower percent of moisture pickup than the Wax Wrapped cartons. This is true of packages which were drop tested as well as those which were not drop tested. Here again, the higher moisture protection offered by the carton constructions of the present invention result in a much longer shelf life.

From the foregoing it is clear that 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. The benefits of this construction are an ability to reduce penetration 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 and pouches. 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. Thus, expensive overwrapping machines or devices for providing filled pouches within the paperboard shell may be dispensed with, this being achieved without sacrificing moisture protection.

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 claims for a definition of its scope.

What is claimed is:

1. A carton for containing a commodity which requires protection against water vapor, said carton being formed from a carton material consisting of a paperboard ply, a ply of paper capable of being printed, said paper ply having substantially less thickness than said paperboard ply and lying in superposed relation to said paperboard ply, and a moisture-resistant laminating adhesive interposed between said plies as a continuous film of substantially uniform thickness in contact with said plies over substantially the entirety of their superposed surfaces, said carton being erected from said material so that said paper ply is the outer ply and said paperboard ply is the inner ply of said carton.

2. A carton for containing a commodity which requires protection against water vapor, said carton being formed from a carton material consisting of a paperboard ply of such porosity that it is able to undergo an adjustment of its moisture content to reach a moisture equilibrium With the commodity to be contained, a ply of paper capable of being printed, said paper ply having substantially less thickness than said paperboard ply and lying in superposed relation to said paperboard ply, and a moisture-resistant laminating adhesive interposed between said plies as a continuous film of substantially uniform thickness in contact with said plies over substantially the entirety of their superposed surfaces, said carton being erected from said material so that said paper ply is the outer ply and said paperboard ply is the inner ply of said carton.

References Cited in the file of this patent UNITED STATES PATENTS 1,458,918 Combs June 12, 1923 1,618,491 Taliaferro Feb. 22, 1927 2,123,760 Wilshire July 12, 1938 2,159,948 Hatch May 23, 1939 2,201,416 Wagner May 21, 1940 2,550,520 Bennett Apr. 24, 1951 2,551,087 Barnhart et al May 1, 1951 2,758,032 Pullman et al. Aug. 7, 1956

Claims (1)

1. A CARTON FOR CONTAINING A COMMODITY WHICH REQUIRES PROTECTION AGAINST WATER VAPOR, SAID CARTON BEING FORMED FROM CARTON MATERIAL CONSISTING OF A PAPERBOARD PLY, A PLY OF PAPER CAPABLE OF BEING PRINTED, SAID PAPER PLY HAVING SUBSTANTIALLY LESS THICKNESS THAN SAID PAPERBOARD PLY, AND LYING IN SUPERPOSED RELATION TO SAID PAPERBOARD PLY, AND A MOISTURE-RESISTANT LAMINATING ADHESIVE INTERPOSED BETWEEN SAID PLIES AS A CONTINOUS FILM OF SUBSTANTIALLY UNIFORM THICKNESS IN CONTACT WITH SAID PLIES OVER SUBSTANTIALLY THE ENTIRELY OF THEIR SUPERPOSED SURFACES, SAID CARTON BEING ERECTED FROM SAID MATERIAL SO

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