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ONE PIECE HEAT SEALABLE FOLDING CARTONS:

A STUDY OF CHARACTERISTICS AND SEALING METHODS

By

Terry McAvoy Brown

A THESIS

Submitted to the College of Agriculture
Michigan State university of.Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of
MASTER OF SCIENCE

Department of Forest Products

School of Packaging

1958

AN.ABSTRACT

One of the most distinct trends in modern packaging is toward the
elimination of both inner liners and overwraps on packages used for
dry and powdered products} This is being accomplished by the use of
functional coatings, which means merely that the protective function
of the package is provided by a material coated directly onto the carton
board.

Due to the nearly perfect plastic surface presented by many of
these coatings, sealing of the one piece package becomes difficult.
Common adhesives are no longer adequate, and increased production speeds
necessitate a much faster setting material.

Two solutions to the sealing problem for one piece folding cartons
are presented. First, thermoplastic hot melt adhesives are employed,
being applied in a manner similar to the application of standard adhesives.
They are, of course, softened by heat and set upon cooling, thereby
providing the setting speed.necessary in modern production methods.

Secondly, a number of functional coatings being presently used are
thermoplastic, and hence can be heat sealed or welded to a similarly
coated surface. Therefore, a carbon coated on both sides with vinyl,
pdlyethylene, or similar thermoplastic can be sealed by softening the

coating by heat and subsequent cooling under pressure.

ii

Presently in production.are a number of liquid holding cartons
using the principle of plastics welding in their sealing. The weld—
ability of the coating materials used on these cartons was studied in
terms of unique properties, and sealing methods used in production were
discussed.

Tests were conducted on liquid holding cartons which employ the
principle of plasticswelding, and their functional characteristics
were compared with similar wax-coated cartons sealed with adhesives.
Significant differences could not be found in the ability of these
cartons to withstand stressed conditions, but plastic coated cartons
proved more acceptable according to customer survey studies conducted
by the Dairy Department of Michigan State University. Time test-s also
showed that plastic coated cartons retain their liquid holding capacity
for a greater length of time.

In this project, by obserVation and eXperimentation, it has become
apparent that the adhering of thermoplastic materials and surfaces is
an answer to many of the existing problems in the production of function—
ally coated one piece packages. 'With the adaptation of thermoplastic
adhesives and weldable coatings to one piece folding carton production,
these cartons can be produced at higher speeds with equal or greater

integrity .

iii

ACKNOWLEDGMENTS

The author wishes to express his thanks to Mr. Lloyd
Stouffer and Mr. Charles Southwick of Modern Packaging
magazine for their help and suggestionsfiin this study, and
to Modern Packaging magazine for providing the fellowship
which made this project possible.

 

 

Thanks are due, also, to Dr. James Goff and Dr. H. J.
Raphael of the School of Packaging at Michigan State Uni-
versity for their guidance and assistance at various
stages of the project.

Dr. Theodore Hedrick and Mr. John Barnes of the
Michigan.State University Dairy also deserve thanks for
their help and cooperation, especially during the study
of plastic coated cartons.

\IV

J’J’J’A'..".. .. commute! we -
n n n n I\ n l\ n n n n I. A‘)\ v

iv

TABLE OF CONTENTS

Page

INTRODUCTION....... ............. . ................................. l
I. THE MECHANICS or" ADHESIVE SETTING ............................ 3
Introduction. ............. ...... ..... .............. ....... 3
Mechanical Adhesion............. ........ ...... .. ...... 3
Implications of the Nature of Mechanical Adhesion. ...... 5
Specific Adhesion..... .................. . ..... .... ........ S

The Solution: Hot Melts.............. .................... 6

The Nature of Hot Melts........ ................. . ......... 7'

Types of Heat Seals......... .............................. 9

Factors Affecting Thermoplastic Adhesives............ ..... 10
Application of Hot Melts.. ....................... . ........ 11

II. THE'WELDING OF THERMOPLASTICS- ............................... 13
Introduction ...... ...... ........ ’ ........................ 13

The Nature of'Weldable Plastics. ..... . ...... ... ....... .. 13
Polyethylene: An Example. . . . ........................... .. 15

III. EXAMINATION AND TESTING-OF HEAT SEALED CARTONS .............. ; 18
Introduction...................... ........................ 18
Suggested Improvements in Carton .......................... 18

Choice of Test Methods............. ......... .............. 21

Tests of Individual Cartons ............................... 22

Tests of Cartons in Cases... .............. . ............... 26

Flat Table Vibration Tests...... .......................... 30

Heat Transfer Tests...... ................................. 31

IV. CONCLUSIONS........ ....... ...... .......... .......... ......... 3h
Proposed Test for Siftproofness ................... ........ 35
Proposed Test for Mechanical Tightness ............ . ....... 36
Conclusions on Tests....... ............................... 3?
.APPENDIX ....................... . ............................... ... 38
REFERENCES ...................... '.. ........ . ....................... 52

TABLE

I.

II.

III.

VII.
VIII.
IX.
X.

XI.

LIST or TABLES

Drop test results, cartons coated with vinyl copolymer
immediately after packing............. ........ ... ........... 38

Drop test results, cartons coated with vinyl copolymer after
seventy-two hour storage.......... ......... . ................ 39

Drop test results, cartons coated with polyethylene,
immediately after packing..................... ........ . ..... to

Drop test results, cartons coated with polyethylene (X poly)
immediately after packing...................................

Drop test results, cartons coated with polyethylene (X poly)
after seventy-two hour storage..... ........... . ...... ...... h2

. Control group—-stored for seventy-two hours, not drop tested h3

Impact test results, polyethylene coated cartons (X poly)... hh
Impact test reSults, wax coated cartons (X wax) ............. hh
Vibration test results, polyethylene coated cartons (X poly) hS
Vibration test results, wax coated cartons (X wax) .......... h;

Measurement of temperature decrease, wax coated cartons ..... ho

XII. Measurement of temperature decrease, polyethylene coated

XIII.

XIV.

XV.

XVI.

mtonSDOOOOOOOOOOOO00.00... ...... D. 00000000 ...... .......... 1*?
Measurement of temperature increase, wax coated cartons ..... h8

Measurement of temperature increase, polyethylene coated
cartonSOIOOO'OOOOOI.00............ 00000000 Q ....... O OOOOOOOOO 149

Graph of temperature decrease as a function of time, wax and
pOlyet'Mlene coated cwt‘onSD. 99999 OIIIOOOODOOOOIOIOOIOIOOOQD SO

Graph of temperature increase as a function of time, wax and
polyethylene coated cartons....... ......... . ............... . 51

vi

LIST OF FIGURES

FIGURE Page
1. Relative comparison between viscosities of hot melt
adhesives and waxes as temperature changes ........ . ......... 8
2. Cross section drawing showing the irregular thickness of a
thin plastic coating on rough base material..... ............ 17
3. Scale drawing of experimental milk carton blank ............. 20
h. Scale drawing of proposed change in experimental milk carton

meDOOOOOODO'IIOOO'OCII'IOO00...... ..... ..O'ODO'I OOOOOOOO 20

Standard drop test apparatus, experimental milk carton, and
milk carton.in present use............................ ...... 2h

Michigan State University aluminum case in which milk
cartons were tested......................... ..... .. ......... 28

Michigan.State University wire case in which milk cartons
‘were tested.................. ..... .. ...... . ................. 28

vii

INTRODUCTION

One of the most distinct trends in packaging today is toward the
elimination of both inner liners and outer wraps in folding cartons.
In.order to accomplish this goal, packaging engineers must find a means
of incorporating the protective function of the package into the carton
board itself, thereby making a one piece folding carton.

Through functional coatings on carton board, this end has partially
been served. These coatings, through research, become more highly
water and grease resistant, and are steps in the development of one
piece cartons. .At the same time, these functional coatings provide a
smoother, more plastic (non~porous) Surface for offset printing, result—
ing in a more attractive package from the marketing standpoint.

Although the advantages of one piece functionally coated cartons
are obvious in the areas of machinability, protection, and appearance,
certain disadvantages are also apparent which must be resolved before
the package can come into universal use.

.As more highly water and grease resistant coatings are applied to
carton board, the difficulty in adhering the board and sealing the
carton increases. Faster machine production Speeds and recent advances
in packaging machinery necessitate faster setting adhesives. Carton
sealing must be adjusted to the faster machines, new coatings on board,
and automatic operations.

Two methods present themselves as possible solutions to the seal-

ing problem for one piece folding cartons. First, the carton may be

sealed with a thermoplastic adhesive of the hot melt type. The first
part of this paper deals with thermoplastic adhesives and their
application.

The second solution to the sealing problem of one piece folding
cartons is the sealing of the coating itself without the use of
adhesives. This, of course, is only possible where the coating is of
a thermoplastic material, which can be welded or heat sealed to similar
surfaces. 'The last part of this paper deals with the heat sealing of
cartons continuously coated with such a thermoplastic material.

It is the purpose of this study to examine the sealing methods
which are uSed with one piece folding cartons, to devise a means of
testing the seals on these cartons, and to draw conclusions on these

tests.

I. THE MECHANICS OF.ADHESIVE SETTING

trgduction

 

“Adhesive" is a very general term which applies to any substance
applied as an intermediate layer between two surfaces which tend to
hold them together. The term includes cements, pastes, gums, animal
glues, and mucilage. The term also includes plastic resins, waxes, and
blends of waxes, resins, and solvents which make up thermoplastic
adhesives, and which tend to hold together their substrates.

Two basic types of adhesion are utilized in the packaging industry.
These types will be discussed in.terms of their application to folding

carton packaging.

Mechanical Adhesion

 

Mechanical adhesion is most important where porous substances Such
as wood, cloth, or paper are involved. Liquid adhesives are used to
effect mechanical adhesion, which consist of a solid bonding agent
carried in a fluid vehicle. This is true of most adhesives including
the well—known semi-solid library paste, which, in Spite of its consist-
ency, uses water as a vehicle.

For adhesion to take place, then, the liquid vehicle must be
removed in order that the solids be allowed to coagulate. This is
accomplished either by evaporation of the vehicle or absorption into
the substrate. In more porous materials, the latter is the most

effective method. In bonding the surfaces of conventional folding

carton board, mechanical adhesion is involved. Penetration of the
liquid vehicle into the stock is accomplished, and consequently the
strength and plasticity of the adhesive is not of prime importance.1

.Adhesives presently used in packaging which utilize the principle

of mechanical adhesion.are as follows:

Egggtable adhesive§_which rely on strong cohesive bonds of
dextrins, caused by the loss of its water vehicle.

Resin emulsions and latice§_are stable dispersions of adhesive
Solids in.water. They set and form a bond when enough.water
is removed to cause the dispersion to break. An increase of
the solids in dispersion to around 70% will result in the
formation of a bond.2

Lacquers are similar to vegetable adhesives in that most or all of
the liquid vehicle must be removed before a bond results.
Any residual solvent acts as a plasticiser and lowers the
cohesive strength of the substance.

.Animal glue adhesives are a solid gel at room temperature and are
run in production at elevated temperatures. The cohesive
bond is formed by both cooling and by the loss of water.

In many packaging operations the return to the gel state and
its inherent tackiness is more important than the loss of

water. All of the solvent must be removed, however, before

the ultimate bond strength is reached.

1L. J. Wood, Jr., Bleached Board Seminar, Packaging Institute 19th
Annual Forum, October 28, 1957.

2Thomas Flanagan, "Faster Setting.Adhesives Boost Production Line
Speeds," Package Engineering, Vol. 3, No. h, April 1958, p. 25.

'Dgpligatiops of the Naturefiof MechanicalJAdhesipn

Several limiting factors are present which cause packaging engi-
neers to look critically at mechanical adhesion and the adhesives
employing this principle.

First, the moisture content of the stock used in packaging has a
direct relationship to the effectiveness of the adhesive. Since in
most packaging applications the vehicle must soak into the stock,
removal becomes more difficult as the moisture content of the paper
increaSes. Soaking wet paper cannot be adhered for this reason, since
there is no place for the water or vehicle to go.

Secondly, variations in density, porosity, and absorbency of stock
has a great influence on the effectiveness of adhesives. More dense
(less porous) stock has greater resistance to the passage of liquid and
hence retards the removal of the vehicle from the adhesive. Super-
calendared paper or paperboard is an example of‘a packaging material
which should resist the passage of liquid because of its density.

The first criticism of mechanical adhesion in modern adhesive
application is the difficulty encountered in attempting to adhere new

coatings with adhesives having a limited affinity for the coating.

Specific Adhesipp;

The common denominator in the limitations of mechanical adhesion
in packaging applications is the slow setting speed. This, of course,
is due to the fact that the vehicle which carries the adhesive material

must be completely removed before an effective bond results.

Specific adhesion, however, involves intermolecular forces at the
interface between the adhesive and the substrate. Strength and plasticity
of the adhesive film become the primary considerations rather than the
molecular penetration of the adhesive into the substrate.

This type of adhesion is made necessary by impenetrable Surfaces
such as glass, polished metal, and plastic. Theoretically, unbalanced
forces at the Surface of these materials render it more active than the
interior of the mass, making possible Specific adhesion in a material
which could not otherwise be adhered.

A dual problem then arises when attempting to seal folding cartons
made from board which has been coated with plastic materials. In attempt-
ing to achieve the optimum in greaseproofness, moistureproofness, and
printability, packaging engineers have made the surfaces of paperboard
smoother and less porous. 'We then find that we can no longer use low
cost adhesives employing the principle of mechanical adhesion, since
we are attempting to seal a Surface which will not allow the vehicle to
be removed from the adhesive material.

Many of our recent developments in folding cartons present nearly
plastic surfaces for sealing, and we must resort to adhesives which
use a high strength plastic polymer as a base. This type of adhesive
will remain fairly flexible, and will resist disruption of the adhesive

bond by flexing and pressure on the flaps of a folding Carton.

The Solution: Hot Melts

v————f—_

The adhesive material known.as hot melt is a solid thermoplastic

substance which contains no liquid vehicle and sets upon cooling alone.

It is 100% solid material whiCh is melted down to a molten liquid by
the application of heat. In packaging applications, it is applied in
this liquid state and the second surface to be bonded is joined to it
immediately, before the material has solidified.

The resolidification of the adhesive is all that is necessary to
effect a bond, and this is caused by cooling alone. Hot melts do not
pass through the jell state as do animal glues, but have a definite
transition from liquid to solid.. Room temperature does not affect the
setting speed, since the entire operation is performed at high tempera-
tures. Hot melts, being insoluble in Water, are not affected by vari-
ations in relative humidity and very little by the moisture content of

1
the substrate.

The Nature of Hothelts

How do not melts differ from waxes and asphalt and other thermo—
plastic materials? First, the basic difference is in the polymeric
constituent in a hot melt which tends to give it a definite softening
range over the transition from liquid to solid. Such high molecular
'weight polymeric materials contribute to the toughness and specific

adhesion.which is lacking in waxes and aSphalt. (See Figure 1 below)

_‘_

.lThomas,Flanagan,_Pfaster Setting Adhesives Boost Production Line
Speeds," Package Engineering? Vol. 3 No. h, April.l958, p. 25.

 

Microcrystalline'Wax

Y1

Viscosity Increase

 

 

Temperature Decrease
FIGURE 1. Relative comparison between viscosities
of hot melt adhesives and waxes as temperature
changes.i
A multitude of different types of hot melt thermoplastic adhesives
have been developed and are becoming popular in various packaging
applications.‘ Most of these are blends of polymers, plasticisers, and
oils, usually in emulsion form, which, at room temperatures, are whitish
or cream colored solids resembling wax in consistency.
Many advantages are offered by the use of heat sealing thermoplastic
adhesives in packaging applications. Let us compile some of these and

examine them here:

1. Instant tack, and positive adhesion, due to the cooling
property of the material.

2. Versatility on a wide variety of surfaces. Although hot
' melts are especially adapted to nearly plastic surfaces where
Specific adhesion is required, they are also equally adaptable
to more porous surfaces, and result in a strong bond.

3. Production speeds using thermoplastic adhesives have been
shown to increase two to three times.2

ill—aid .
3National Starch Products Co., Technical Service Bulletin No. 305.

 

New applications of heat sealing with thermoplastics have not been
thoroughly explored, although this type of sealing is presently being

examined by a number of firms involved in extensive packaging operations.

Types of_Heat Seals

Heat seals are either of the direct type or employ delayed tack.
The direct heat seal has essentially no time delay characteristic, and
must be activated and applied simultaneously to the surface being
adhered by heat and pressure. Upon activation by heat, the adhesive
coating will become tacky, butwupon removal of heat it will lose its
tack almost immediately.

Direct heat sealing is further divided into two principle claSses.
Some direct heat seals may be made by applying the adhesive to only
one surface and then joining the coated part to the uncoated part.
Other adhesives require that each face to be adhered must be coated,
and then sealed "face to face."

Delayed tack heat seals occur in the use of adhesives which are
activated upon application of heat, and remain tacky for some time.
Once activated, they will adhere to most surfaces with the application
of pressure alone. This time delay feature distinguishes this group
of hot melts from those employing direct or instant bonding. .An in-
teresting feature of this type of heat seal is that in some applications
where tension is not immediately put on the seal, a delayed tack heat

seal may be used as a direct seal.

10

Factors_Affecting_Thermoplastic.Adhesives

Successful heat sealing with thermoplastics depends essentially

on four variables. .An effective heat seal depends on reasonable con-

trol over these four elements:

1.

Time—~the period of dwell during which the heating element

is in contact with the adhesive coated material.

. Temperature-~the surface temperature of the heating element,

and theoretically the temperature of the adhesive in the
molten state.

Pressure-~the force which the heating or sealing element exerts
on the stock, and consequently, the pressure of the stock on
the adhesive layer.

Insulating effect~—different weights of paperboard will have
varying heat conductivity. If the weight of the board is
lighter, it will usually permit a reduction in heat seal

temperature.

Other factors which influence the integrity of heat seals are the

adhesive film itself and the paper to which it is applied. Uniformity

of the adhesive film is essential. Striated coatings, for example,

often caused by direct roll application or simple knife coating, reduce

the effective contact area. Fluctuations in film thickness will result

in poor adhesion due to excessive or insufficient adhesive.

In addition to the weight or insulating effect of the paper, the

adsorptive qualities of the paper should be such that a maximum of the

adhesive remains on the surface and does not penetrate into the substrate.

Most of the functionally coated paperboard used today has this quality,

which allows for better specific adhesion.

,Appliggtion of Ebt Melts

[n packaging applications, the use of hot melt adhesives can re-
sult in increased production.rates. One machine company reports loading
five inch pies into cold wax printed cartons at speeds up to 265 per
minute.1 A somewhat similar technique is used in the cereal field,
with a different cartoning machine recording production of 350 per
minute.2

The hot melt adhesive is applied by intaglio glue rolls after a
preheating of the end flaps. After adhesive application, the loaded
carton passes into a flap folding station and then into a chilling
section which replaces the drying conveyor of conventional machines.
The end.flaps are chilled so as to set the adhesive quickly, as well as
to prevent further heating of the carton. The adhesive is applied
around the periphery of the end flap, and is claimed to be "pretty close
to a leakproof carton."3

The intaglio glue rolls, which are a recent develOpment, are
eSpecially adapted to thermal application of hot melt adhesives. Their
use gives an especially suitable pattern application around the

periphery of the flaps, lending to the integrity of the package.

 

*7

1R..A. Jones and Company, Inc., Cincinnati, Ohio.
2Stokes and Smith Company, Philadelphia, Pa.

3"Wrapless, Linerless Cartons," Modern Packaging Magazine,
August, 1957, p. 92.

12

A constant stream of adhesive, supplied from a heated reservoir by

pump, flows down the roll. .All surface adhesive is removed by a heated,
Spring loaded scraper. The small cavities in.the roll retain the
adhesive which is transferred simultaneously to the top and bottom
flaps of the carton in much the same manner as gravure printing. It
must be noted, however, that all machine parts in contact with the
adhesive must be heated to prevent coagulation on the parts.

.At present, thermoplastic sealed cartons are being used by a
producer of frozen foods and the baby cereal division of a pharmaceutical
company. It was impossible to obtain.technical information on these
cartons or procure any samples for testing. The machine company
guarantees full fibre tear seal and the ability of the sealed carton
to withstand ~hO degree temperatures. The carton is a waxed, four
flap each end, glued flap type with full length top and bottom flaps.
Directions, which are printed directly on the carton, cannot be thrown
away by the consumer, as often is the case with overwrapped cartons.

Thermoplastic hot melt sealed cartons of this type, then, are a
key to the elimination of overwraps and inner liners and their replace-
ment by functional coatings. Hot melts furnish the method whereby

these nearly plastic coatings can be adhered in production.

13

[1. THE WELDING or TIERMOPLASTI’CS

[ntrgduction

A number of the functional coatings which are being applied to
folding boxboard are thermoplastic in themselves, and can be welded or
sealed to a similarly coated surface. Therefore, a folding carton
coated on both sides with a vinyl copolymer, polyethylene, or similar
thermopLastic can be sealed by softening the coating with heat and
subsequent cooling under pressure. In order to understand thoroughly
how the principle of weldability is applied to folding cartons, it
will be necessary to examine the nature of weldable materials and the

theory of plastics welding.

The Nature of'Weldable Plastics_

Plastics fall into the category of amorphous, or noncrystalline
Substances, as opposed to the other division of solid matter which is
crystalline. Crystalline materials demonstrate a regular pattern or
geometric arrangement of molecules depending on the degree of stress on
the material and the nature of the constituent atoms.

.All plastic materials which are used in the coating of folding
boxboard are amorphous or noncrystalline. They show little or no
organization in their structure, and the atoms lose their individuality
in becoming a part of the larger molecular structure.

Because of the random arrangement of molecules, plastic coatings
Show'no definite melting point, but soften gradually with increase in

temperature. As the weak bonds between the long chain molecules begin.

1h

to break down, the material is ready to be sealed or welded to a
similarly coated surface.

This heating, which causes softening of the film and allows it to
be sealed, can be accomplished by a number of methods. Unsupported
plastic films can best be sealed with a jaw type sealer which exerts
pressure from both sides simultaneously. In folding carton sealing,
however, the product inside the carton prevents the insertion of a
mandrel, and the method of folding the flaps flat leaves no lip for
the jaws to grip.

Radiant heating can be used for the sealing of folding cartons.
The flaps to be sealed must be radiant heated beyond the softening
range of the coating, and then closed with the usual pressure and cool-
ing. This method is presently employed by the Pure-Pak Division of
EX‘CSil-O Corporation on their experimental polyethylene coated milk
carton, which will be examined and tested later in this paper. The
equipment used includes a rod type heating element to which the carton
is exposed during part of its cycle. 'With this element held at lhOO
degrees F., the coating on the carton is heated over the 250 degrees
necessary for softening. The necessary folds are then made while the
carton is heated, and a water cooled platen applies pressure until the
seal is effected.

.Another possible method of heat sealing folding cartons coated
‘with thermoplastic material is through the use of a band sealer. In
this methodthe cartons to be sealed are conveyed between two steel

belts to a heating station, Where the resin is melted and the seal

15

accomplished. The carton then passes on, still held between the steel
belts to a cooling station, after which it is released. This technique
virtually eliminates the problem of sticking of the plastic coating to
the sealing tool. Since the process is continuous, band sealing would
be especially suited to the high Speed "assembly-line" filling and
Sealing mechanisms used in folding carton production. Sealers of the
band type require somewhat less attention to temperature and pressure
than do other types of heat sealers, due to the extensive length of

dwell time involved.

Po et lene:‘;An Example

The most popular and possibly the most versatile coating which
can be heat sealed to itself is polyethylene. In the solid state,
polyethylene is a white transluscent, rubbery solid which is applied
to its base stock by conventional extrusion-coating processes. A film
of polyethylene is extruded and applied to the stock under pressure
while in a softened state. .Adhesion to paper and board is excellent,
and very thin coatings can be applied at Speeds of 370 feet per minute
or higher.

Chemical properties of polyethylene coatings render it an excellent
barrier material for folding cartons. It is substantially inert, being
unaffected by acids at room temperatures, although softened somewhat by
chlorinated hydrocarbons. This, of course, means that acidic foods
can be packaged in polyethylene without fear of disintegration of the

coating at lower temperatures.

l6

Folding boxboard coated with polyethylene offers physical proper-
ties which serve to integrate the protective function of the package
into one piece. The coating is free from taste, odor, and toxicity,
and resistant to chemicals, solvents, and greases. Its excellent low
temperature flexibility permits its use as a coating on frozen food
packages or with products intended for arctic use. It does not crack
or separate upon folding of the carton'blank, and will resist any depth,
width, or pressure of scoring rule now used in production.

A property of polyethylene which is eSpecially important in its
use as a coating for liquid holding cartons is its excellent resistance
to permeation'hy liquids. The abSorption of water by duPont‘s Alathon
16 is negligible, only 0.01% by standard test.1 'Water vapor permeability
depends on the thickness of the coating and the smoothness of the base
material, but in most cases is very low, Constructions having coatings
as thin as one-half mil (0.0005) are appreciably more resistant to the
passage of Water than uncoated materials, even those considered reason-
ably good barriers. Coatings on rough Surfaces may not be as effective
as on Smooth ones, since the coating, in the molten state, will tend
to fill in the low Spots and barely cover the high ones. Such a coat-

ing, greatly magnified, can be visualized in the following figure.

__l._.

1"Alathon" As LCoatjglgMaterial, duPont Company, Wilmington:
Delaware. ——~ ___

l?
L \

POLYE ‘ IIENE CiATHi} 1

COARSE BASE MATERIAL

  

 

‘ \

FIGURE 2. Cross section drawing showing the irregular thick-
ness of a thin plastic coating on rough base material.

The protruding fibres act as wicks to transmit grease and moisture.

Finally, polyethylene coatings can be heat sealed, in the tempera-
ture range of 250-300 degrees F. Progressively higher sealing tempera-
tures are necessary as the thickness of the base stock increases.
Excellent heat Seals can be made even when some products deposit dust
on the area to be sealed, which might occur in the packaging of dry
cereals or meal. Difficulty arises because of the thickness of the
paperboard base, but can be reduced by the use of band sealing or.
radiant heat.

To demonstrate the liquid holding capacity of resin coated cartons,
sealing methods used in production, and tests used to evaluate heat
Sealed cartons, we will examine a paperboard milk carton in the next
section. This carton is an experimental design by the Pure-Pak Division
of Ex-Cell-O Corporation, and is in limited test production at the

Dairy of Michigan State University.

18

III. EXAMINATION.AND TESTING OF HEAT SEALED CARTONS

Introdugtion

The polyethylene coated heat sealed carton referred to previously
demonstrates the liquid holding quality of this type of functionally
coated carton. It is presently made in the one quart size, and is in
limited production and uSage at Michigan State University.

Board stock used in the carton is conventional .019 fourdrinier
kraft, 250# per ream, which is also used on the company's popular wax
coated milk carton. It is coated with duPont.Alathon 3h, using a
heavier (.0015) coating inside and 3/h mil or .00075 coating outside.
The carton blank (see Figure 3) is prepared by the Internatibnal Paper
Company. The Side seam of this carton is sealed using the hot melt
method of Specific adhesion mentioned earlier in this paper. The adhesive
used is prepared in rope form and called "Thermogrip" by the United Shoe
Machinery Manufacturing Company, and is applied by automatic machinery.
The carton is delivered to the dairy in "knocked down" form.

The machine used in filling and scaling is basically similar to
the Standard Ex-Cell-O machine presently in use preparing wax coated
cartons. The tank of molten paraffin is, of course, omitted, and heat-
ing elements which Soften the plastic coating and make heat sealing

possible are installed.

Suggested Improgpments in Carton

 

‘Upon examination of the production carton after filling and seal-

ing, a number of possible improvements were observed. First, it was

19

noted that upon folding the gable top of the carton, a delamination
occurred in the side seam where it is folded on a reverse score. This
delamination causes what is known as a "shoulder leaker" and causes
the bottle to be rejected. The delamination occurs in every case, but
most do not leak immediately and are, at the time of production,
acceptable cartons.

The delamination at this point, however, exposes a greater amount
of paper fibre to liquid action which in.turn causes further delamination,
leading to the development of leaks after a period of time. After
experimental scoring and folding of this side seam, it was found that
by rotating the seam ninety degrees either way, placing it on a dif-
ferent corner of the carton, the condition could be eliminated. Since
the seam would no longer be folded on a.reverse score, it would not be
Subject to as extensive a stress upon folding, and would not tend to
delaminate as readily. To accomplish this in production would entail
a complete change in both scoring and printing dies. (See Figure h)

Another area where leaks frequently occurred was on the side
opposite the pouring Spout, directly under the sealed area. This ap-
peared to be caused by'a slight failure in.the seal, which was stressed
slightly by the tendency of the gable fold to rebound. The only
apparent solution was to increase the area of the heat seal, which
would impair the easy-opening feature of the pour—spout container.
Additional heating of the seal resulted in 85% acceptable cartons, and

was considered adequate by technicians of the machine company.

20

3/8 = 1).
a)‘__,

Experimental carton blank (Scale:
I/\

FIGURE 3.

.—F

 

 

’11

 

 

r
T

j

 

_Jr_____li__7\_ T_____
4— \‘r

\

¢_-s.
l
I
l
I
|
I
I
l
I

_k____7'}_ ..__._+\._..__
l

L-..
l
l
l
l
l
l
l
l

.7t.___.
1

/

V

I ‘\
.L

 

 

 

 

3/8 = 1)-

Proposed carton blank (Scale:

FIGURE LL.

 

 

 

 

 

 

 

 

 

 

21

Choicergf Test Methods

In order to arrive at tests which would reflect actual conditions
to which milk cartons would be subjected, it was necessary to examine
the two basic areas of damage which may occur. First, damage may occur
in the commercial handling of the package, during filling,loading into
cases, loading in trucks, and in delivery. Since the loading of milk
cartons into cases is in most situations by hand, a test of individual
cartons would be necessary to reflect possible damage in this area.

In all other possible damage situations in commercial handling, the
cartons would be loaded in cases of sixteen or twenty and would be
supported on all sides by the caSe and/or adjoining cartons.

The second basic area of possible damage is in consumer handling-—
the shocks and stresses to which the carton is subject after its delivery
to the retail store or to the consumer. Therefore, tests would be
necessary which reflect retail store and consumer handling and give
realiStic results.

'Water was used as a filler in.all cartons tested in this project.
Tests conducted by the PuresPak Division showed no significant dif~
ferences in the wettability of water and milk, and although milk titrates
to .01 acid due to proteins and other ingredients, it was felt by the
dairy department that water would yield results as reliable as would
milk. It would also, of course, be more economical considering the

number of filled cartons involved.

22

Tests of Individual_0artons

In order to reflect the damage which may occur in consumer handling
of milk cartons, a standard drop test has been devised by the Pure-Rak
Division. It consists of a steel frame which directs the fall of the
carton, and a steel damage plate with raised corners which simulates a
corner drop on.all four corners Simultaneously. (See Figure 5) The
experimental polyethylene cartons (hereinafter referred to as.X poly)
‘were subjected to the drop test in comparison with two types currently
in production (hereinafter referred to as Y poly and Y vinyl).

The cartons were divided into three groups, each group containing
representative samples of each type of carton. The first group was
drop tested immediately after packing and was observed for leaks. The
second group was drop tested and observed for leaks after having been
stored.at standard conditions of 73 degrees and 50% relative humidity
for Seventy-two hours. It is not likely, however, that milk would be
allowed to stand as long as 72 hours under those conditions, but this
appeared valuable in determining the type of damage which would occur.
The third group of cartons was allowed to stand under standard condie
tions for a period of 72 hours as a control. These were not drop tested
but merely observed at the end of that period for any leaks which may
have developed.

A leak, as referred to in these tests, was defined as any appear-
ance of water on the outside of the carton, and usually occurred as a

bead of water on or near a seam or fold.

23

The drop tests were conducted in accordance with the standard
procedure as outlined by the Pure-Rak Division in the apparatus pictured
in Figure 5. Each carton was dropped ten times from a height of seven
inches onto the plate with raised corners. The carton.was then placed
onla sheet of clay coated chip board which served to indicate the ap-
pearance and source of leaks. The time of occurrence and the total
number of leaks was recorded. In production of milk cartons, one leak
causes rejection, but in this test the number and position of the leaks
'were recorded in order to diScover any weaknesses in the carton. The
results of drop testing will be found in the Appendix, Tables I through
VI.

It should be noted that the 1 poly carton did not withstand the
time test. All cartons in the control group and the group to be drop
tested after seventy-two hours of this type developed leaks. These
leaks did not occur as beads of water appearing at weak points in the
carton, but as a thorough wetting of the board on the bottom of the .
carton. It is believed by the author that this wetting action was due~
to two factors. First, that the coating of polyethylene on the inside
of the carton was not heavy enough to cover the rough surface of the
board. Although the lower areas were filled with the molten plastic,
the higher regions received little or no coating. Rough fibres pene-
trating the coating served as wicks which transmitted moisture into the
base stock, and eventually wet the material thoroughly. (See Figure 2)

Due to the method used in sealing this particular carton, the out-

side of the base stock on the bottom was not coated. Since hot irons

(.

HHWGENIZED
MHK . ‘ f

,. A“

‘

I

\. ’9.

. ’ ‘

fill. ' I .‘hgt.'f.%-_i_‘i_‘ 1.0'. ' 1 \~*‘:. (“11* I ‘ .

. v.
- - - ---s»..¢ .d .- .. ‘,v‘\.-- ’

FIGURE 5. Standard drop test apparatus, experimental milk carton (1.)
and milk carton in present use (r.)

 

21;

25

are used for sealing, the coating is omitted to prevent its sticking
to the surface of the iron. The irons could be coated with teflon or
teflon impregnated cloth which would also prevent sticking and still
allow the outer surface of the base stock to be coated with polyethylene.

Therefore, figures are not available on the Y poly carton.since

leaks were observed in each of them after seventy-two hour storage.

Due to the construction of the cartons tested, each could fail in

a total of five possible ways. The standard test submits each corner
to pressure similar to a corner drop, and the side seam is also sub-
jected to a stress. 'Where other types of damage occurred, it will be
noted in the Appendix, Table I through.VI, where test results are
reported.

The following reSults and relationships were noted from the data

recorded in the drOp tests:

1. Storage of all cartons for a period of seventy~two hours at
standard conditions increased the tendency to leak after drop
testing. This is due to the wetting and subsequent weakening
of the paper fibres.

2. More leaks of the soaking-through type appeared in cartons
stored for seventy-two hours than in those tested immediately
after packing. The packages tended to delaminate in the area
of the heat seal and allow the water to soak through.

3. Y poly carton did not stand up'under storage for seventy-two
hours at standard temperature and humidity. The author would
recommend that tests be repeated with all cartons under re—

frigeration.

26

1;. Differences appearing in one type of carton between those
tested immediately and those stored for seventy—two hours are
greater when observed after twenty-four hours than when observed
fifteen minutes after testing. It would appear, then, that time
in storage before testing is directly related to the time rate
of leakage after testing. (See Tables I, II, IV, and V.)

S. X poly cartons withstood both drop and storage time tests better
than did Y poly cartons. X poly alsO appeared more resistant
to leaks after drop testing. (See Appendix, Tables III, IV,

and V.)

[1‘33ng Cartons in Caigs

In order to reflect the damage which might occur when fibre milk
carbons are handled and shipped commercially, it was necessary to
utilize tests in which milk cartons loaded in shipping cases could be
Subjected to adverse conditions. Due to the similar size and weight of
loaded milk cases to corrugated shipping cases, two standard test
methods were used. '

Inclinilvmpagt. In nany dairies, milk cases are loaded in and
unloaded from trucks by the use of an inclined plane on which the cases
slide for) distances of anywhere from one to ten feet. It was felt that
a test was necessary which would subject the cases to similar conditions
and would result in damage similar to that suffered in loading and un-
loading on inclined planes.

The test chosen to accoxnplish this was the standard incline impact

test for Shipping containers, ASTM standard D-880-50. The loaded cases

27

' were placed on a 10 degree incline, and a slide distance of three and
one-half feet was used. The cases were impacted first on the bottom,
to simulate a Short drop. The next four impacts were on the sides of
the caSe, simulating the shock received by'a case sliding on an inclined
loader. Each side was impacted once, the case being rotated clockwiSe
ndnety degrees after each impact. A sixth.impact was then given to the
bottom of the case to again Simulate a short drop received in loading
or unloading the truck. ’

The cartons were then removed from.the case and placed on sheets
of clay coated chipboard which served to indicate the occurrence and
location of leaks. Each carton was wiped dry with cheesecloth before
observation to eliminate the effect of water from other cartons appear-
ing on the surface. (Leaking cartons were made apparent by dark Spots
which appeared on the chipboard. The number of leaking cartons per case
was recorded and will be found in the Appendix, Tables VII and VIII.
Both wire and aluminum cases were used, and are pictured in Figures 6
and 7. Before attempting to interpret the results of the incline
impact tests, the following considerations must be noted:

'1. That variations occurred from day to day in identical tests.
This could be attributed to-—
a) variations in sampling from production runs, or
b) variations in atmospheric conditions which would tend
to cause differences in carton moisture content and

temperature.

k
\

 

a

4—-

iii; If \3’: ii).

y(I :i I!" :1". .“ain'ls
"9 ll 3:: :1”! 3.»;

L... .... -.. 1-!”
v;’” (I'llllhus IjLfl’.___1..¢:-IIIII'II ”, .g’V
Hm ...? ......I
'I'
if: \ fl"

‘ “any

  

Imvlu‘v [x\ I.

IX“,\

 

 

 

Michigan State University wire case

in which milk cartons were tested

FIGURE .7.

FIGURE 6. Michigan State University aluminum case

in which milk cartons were tested

28

2.

29

That a limited sampling was available and could not be analyzed
statistically with any degree of accuracy. The tests made
possible the obServation of relative ability to withstand
adverse conditions, and of points of weakness in the carton,

rather than a statistical analysis of damage and variance.

Conclusions, based on the results of impact testing, are as

follows:

1.

The most apparent weakness in both X poly and X wax cartons
upon.impact was the opening of the top seal. The impact
perpendicular to the line of the gable tended to pull out the
staple in the wax carton.and to delaminate the board in the
seal area of the poly carton. Leaks of this nature are noted

in the Appendix, Tables VII and VIII.

. In no case did the side seam weaken or break as was eXpected

under this type of test. The support of other cartons within
the case apparently prevented this.

Reaction of identical cartons to different type of caSes in
this test caused different results. The raw edges of the wire
case tended to chafe and puncture the cartons, causing the
damage in this type of case to be more extensive.

Storage time of Seventy-two hours caused weakening of the
cartons which resulted in a greater number of leaks appearing

after testing.

30

flat Table Vibration Testis

Much damage can be done to the bottoms of fibreboard milk cartons
by the vibration and bouncing action Caused by the delivery truck.

This causes friction on the sides of the carton and frequent short
drops on the bottom of the caSe. In order to simulate this bounce and
vibration, samples of X poly and X wax cartons were subjected to the
standard vibration test, ASTM standard 13-999-148'1‘.

In the first part of the test, cartons of the X poly and X wax
types were packed and conditioned for twenty—four hours under rei‘riger-
ation at forty degrees F. Samples were packed in both aluminum and
wire cases, diagrams and descriptions of which shall be found in
Figure 6. The swple cases were placed on a vibrating table driven by
eccentrics which give it a circular harmonic vibratory motion in a
vertical plane. ‘ Procedure "A" was followed, with the cases placed on
the table without fastening.1

The table was operated at a Speed which resulted in forces equiva-
lent to one times gravity acting on the case, with a vertical distance
of one inch. The test was continued for two minutes. Detailed records
of the test on each case, including type of damage to containers and
number of cartons which leaked, as well as other observations, will be
found in the Appendix, Tables DC and X.

Conclusions baSed on test reSults and observations are as
follows:

1Alrlerican Society for Testing Materials, Standards 3n Paper and
Paper Prpgicts and ShippiflContainers.

31

1. Size of the case in which milk cartons are delivered is a
primary consideration in the resistance of the carton to vi—
bration in a vertical plane. The standard Michigan State
University aluminum caSe, which is slightly larger than the
standard Michigan State University wire caSe, gave vibration
test results of ConSiderably more damage. The cartons tended
to bounce within the caSe instead of "staying with it," and
hence more damage was caused to the bottoms. It was also
observed that the printing on the Sides of the carton was
obliterated on the polyethylene cartons which were tested in
aluminum cases due to excessive motion within the case.

2. Cartons stored for seventy-two hours under forty degree
refrigeration showed leSs tendency to bounce and leak than
those tested twenty-four hours after packing. The tendency of
the carton to bulge and conform to the dimensions of the caSe
over a period of time reSulted in less damage as a result of

vibration testing .

£6th Transfer Tests

A customer acceptance survey was conducted by the Dairy Depart-
ment of Michigan State UniverSity concerning the user‘s reaction to
the experimental polyethylene coated milk carton. Consumer acceptance
was unanimous in such areas as looks, feel, "in the refrigerator" and

1
"on the table," but a significant number complained that the new

L A

1From Consumer Acceptance Questionnaire, Michigan State University
Dairy Department.

32

carton did not "keep the milk as cold" as the standard wax coated
carton.

The hypothesis was then made that the polyethylene coating, being
a.better insulator than wax, would prevent the milk from reaching the
refrigerator temperature at as fast a rate as would the milk in the
wax carton, The manifestations of this condition would be: a) that
upon removal from the refrigerator and remaining open for a length of
time, the temperature of the milk in each carton would raise at the
same rate, and b) that upon recloSure and replacement in the refriger-
atOr, the milk in the wax carton would return to the refrigerator
temperature at a faster rate. If removed before a certain length of
time, then, the milk in.the polyethylene carton would be warmer than
that in the wax.

In order to examine this hypothesis, a test was devised in which
the heat transfer rate was measured and recorded for each type of
carton. Two Sets of cartons of each type were used for the heat trans~
fer tests.

The first group of cartons, ten wax coated and ten polyetnylene
coated, were refrigerated for twenty—four hours after packing at a
temperature of forty degrees F. They were then removed to the con»
ditioning room of the packaging Laboratory under conditions of seventy—
three degrees F. and fifty percent relative humidity.

The second group of cartons, ten'wax and ten heat Sealed poly—
ethylene, were stored at standard conditions of seventy-three degrees

F. and fifty percent relative humidity for a period of twenty-four

33

hours. They were then removed to refrigerated conditions of forty—three
degrees F.

The temperature change was measured every hour and was recorded.
The data sheets are reproduced in Tables XI through XIV‘ in the Appendix.
In Tables XV and XVI the temperature change is plotted as a function of
time and the differences are more clearly represented.

Results of the tests are as follows:

1. Milk in wax coated cartons increases in temperature at a faster
rate than milk in polyethylene coated cartons. This rate
decreases with time, as can be Seen in Table XVI in the Appendix.

2. Milk in wax coated cartons decreases in temperature at 8.
Slightly faster rate for approximately two and one-half hours,
then decreases more slowly than milk in polyethylene coated
cartons. (See Appendix, Table XV.)

Conclusions:

1. Polyethylene cartons serve as better insulators for milk and
tend to resist temperature change more than wax cartons.

2. A wax carton under refrigeration for less than two and one-half
hours after having been exposed to higher temperature will give
lower temperature readings than a polyethylene coated carton
under the same conditions. The milk, therefore, in the wax
carton would be colder than that in the plastic carton up to

two and one-half hours after refrigeration.

3h

IV. CONCLUSIONS

One piece heat sealed folding cartons have advantages to both
consumer and the producer. in their preSent form they also have
disadvantages which must be resolved before universal acceptance is
feasable. I

First, one piece cartons which are functionally coated are ex—
tremely difficult to seal, and the packager must rely on either
expenSive hot melts or equally expensive thermoplastic coatings which
can.be sealed. Either method leaves room for improvement which can.be
brought about by testing and research. .Adhesive producers, carton
manufacturers, and machinery producers can.aid in.the solution of these
problems by coOperation with universities such as Michigan State who
show an interest in packaging as a true science.

It is imperative, however, that cooperation between industry and
the university in the interests of packaging as a Science be placed
before the selfish interests of the individual concern. Research
cannot take place at the university level without this cooperation, and
duplication of work due to poor communications must be prevented at all
costs.

Since only two hot melt Sealed folding cartons are presently being
produced commercially, the potential for gathering information.in this
area is large. Hewever, it was found to be exceedingly difficult to
obtain technical information concerning the production or sealing of

these cartons. ID‘WES equally difficult, in fact impossible, to

35

obtain sample cartons, either sealed, unsealed, or in flat blank form.

It is recommended that as Soon as materials and technical infor-
mation become available in the area of hot melt sealed one piece folding
cartons, tests for siftproofness be deviSed. This feature would be
essential in a one piece carton used for powdered or dry products, and
although the producers of the frozen food carton mentioned earlier
claim siftproofness of cartons, they show no data or test methods with
Which to uphold this claim. They also declined to furnish sample
cartons for testing by the author using proposed methods.

It was originally planned. to include in this project the develop—
ment of two. t-eSts-one for siftproofness and one for mechanical tight-
ness—and to attempt to correlate the two. The proposed tests will be
outlined herein in the hOpe that as materials and information become

available they can be examined .

fgpposgd Test for Siftproofnesg

One piece heat sealed folding cartons shall be filled with uniformly
fine sand which has been oven dried. The weight of each carton shall be
meaSured accurately to the nearest .01 pound. These cartons shall be
confined in an apparatus which will rotate the carton around its center
axis in circular harmonic motion for a designated period of time. At
the end of this period the carton shall be removed from the apparatus
and agin weighed accurately. The weight loss of each carton will

then give an indication of its siftproofness.

36

It is suggested that the apparatus frequently used in retail stores
for mixing paint gives the type of motion which would put maximum pres-

sure of the carton contents on the Sealed areas.

Proposed Test £9?,!53th;EE; Tightness

One piece cartons shall be heat sealed with no material being
placed inside. Each test carton.shall.be placed flat between.the
platens of a press which will measure accurately any change in.pressure
exerted against the upper platen. It is suggested that a Baldwin-Emery
or similar testing machine which can.be equipped with a sensitive load
cell be used. Each carton to be tested shall be fitted with a rubber
diaphragm on the narrow side, which will allow the insertion of a hypo~
dermic needle into the carton without allowing the escape of air. .Air
will then be introduced into the carton through the needle until a
predetermined pressure is reached. The escape of air from within the
carton shall be timed accurately as the presSure reduces from the pre~
determined point to zero.

Mechanical tightness can then be reported in terms of the time
rate of air escape through the sealed areas of the carton. It may be
necessary to meaSure first the porosity of the material.used in the
carton to be tested, and to allow for the effect of air escape through
the walls of the carton,

.An attempt should then be made to study any correlation of mechani-
cal tightness with siftproofness, in order to prevent duplication of
information, It is possible that the two tests may, in effect, measure

the same thing.

37

ancljisions on Tests

Cartons continuously coated with thermoplastic materials can be
heat sealed by the softening of the coating, welding by pressure, and
subsequent cooling. Tests conducted on experimental milk cartons of
this type showed that the integrity of the seal is as great as that of
adhesive sealed cartons. The experimental carton stands up well under
adverse conditions. and is an acceptable package according to consumer
surveys.

In individual drop tests, it proved a better liquid holding carton
than types presently in production. In impact and vibration tests, it
proved equal in ability. to withst stress, and similar in types of
damage suffered .

The advantages of faster production Speeds, one piece construction,
and eaSe of sealing will eventually bring heat sealed folding cartons
to the fore as the most popular with both consumers and producers of

packaged products .

APPENDIX

TABLE I
DROP TEST RESULTS

CARTONS COATED WITH VINYL COPOLIMER-—IMMEDIATELY AFTER BACKING

 

7——

“ v—w—v v ffi h v

 

 

Sample . 15 Min. 1 Hour 21; Hours Remarks
1 O l 1 corner leak
2 l l 1 corner leak
3 O l 1 corner leak
)4 2 2 2 ’ corner leak
S 2 2 h beads of water appearing on
bottom edge
6 l l 1 corner leaks
7 3 3 h beads of water on.bottom edge
8 2 2 2 corner leak
9 l l 2 corner leak
10 3 3 , h delamination in seal area
ll 1 l 1 corner leaks
l2 2 2 b, beads of water on bottom edge
Total 18 2O 28

Mean ‘ 1.5 1.66. 2.33

39

TABLE II
DROP TEST RESULTS

CARTONS CQATED WITH VINYL COPOLYMERFHAFTER 72 HOUR STORAGE

A ___L 4 ’__
' V r--- v 'i fi—v — ——v~ ———
; 4—1;
—— w ‘— fi __

 

 

Sample 15 Mint 1 Hour 2h Hours Remarks
1 1 1 3 all corner leaks
2 2 3 3 all corner leaks
3 O O 1 corner leak
u 2 2 1. all corner leaks
S 1 1 5 small beads on bottom edge*
6 1 1 h small beads on bottom edge
7 3 3 .h delamination in area of seal
8 l l 2 corner leak
9 2 2 3 small beads on bottom edge
10 3 3 h small beads on bottom edge
11 3 3 h small beads on bottom edge
12 2 2 2 small beads on bottom edge
Total 21 22 39
Mean 1.75 1.83 3.25

k

m V—ffi

TAppearance of Small beads on.bottom edge denotes a soaking
through effect.

ho

TABLE III
DROP TEST RESULTS

CARTONS COATED WITH POLYETHYLENE (Y POLY)-~D’1MEDIATELY AFTER PACKING

A ._4_‘
k _- 1 A L‘

__v

 

 

Sample 15 Min. 1 Hour 2h Hours Remarks
1 3 3 5 four corner leaks, on bottom
edge bead
2 2 3 h all corner leaks
3 2 2 3 corner leaks
h 2 2 h corner leaks
S 2 2 3 corner leaks
6 O 1 l soaking effect near side seam
7 2 2 3 corner leaks
8 l 1 h corner leaks, beads on edge
9 3 3 3 corner leaks
10 2 2 h corner leaks
11 2 2 3 corner leaks
12 1 1 3 corner leaks
Total 2 2 2).; 110

Mean 1 .83 2 .OO 3 .3H

bl

TABLE IV
DROP TEST RESULTS

CARTONS COATED WITH POLYETHEENE (x POLY)~—M4EDIATELY AFTER PACKING

F. A ‘ A __ ....__
_——. v—t V1.7 —-——v w fi‘ —
¥k A - . 4

FT—vwv w—v fifi

 

 

Sample 15 Min. 1 Hour 2h Hours Remarks
1 O ' O l leak in side seam corner
2 O O O
3 O O O
h o o o
5 O O 1 failure of bottom seal
6 O O O
7 O O O
8 O O O
9 O O O
10 l l 2 failure of bottom seal
11 O O 0
12 O. O 0
Total 1 l h

£2

TABLE V
DROP TEST RESULTS

CARTONS COATED WITH POLYETHEENE (x Pomp-AFTER 72 HOUR STORAGE

 

 

 

 

 

 

=========================se —-e~— -:===========:*- __;===
Sample 15 Min. 1 Hour 2h Hours Remarks
1 O O 1 side seam corner
2 l 1 2 failure of bottom seal at side
3 O o o
h 0 O 1 failure of bottom seal at side
5 O l 2 failure of bottom seal at side
6 O O O
7 O l 2 side seam corner, bottom seal
8 O O O
9 l l - 1 side seam corner
10 O O 0
ll 0 O 1 failure of bottom seal
12 O O 0
Total 2 h 9

Mean .166 .33 .75

——V

Sample

1. Y Vinyl carton
2. Y Poly carton

3. X Poly carton

TABLE VI

CONTROL GROUP

STORED FOR 72‘ HOURS, NOT DROP TESTED

Remarks

no leaks Observed after atorage
all cartons leaked after storage

no leaks observed after storage

fi

—_v

)43

TABLE VI:
‘LMRACT‘TEST RESULTS
ASTM STANDARD Dado-So

POLYETHILFNE COATED CARTONS (X POLY)

. .

 

 

 

 

 

 

 

Remarks
'Wire-Case
2h hours 20 9 , delamination of top seal
72 hours 20 3 delamination of top seal
Aluminum Case .
2h hours 20 lo delamination of top seal
72 hours I _ 20.. .10, .VIdelamination of top seal.
TABLE VIII
DMRACT TEST RESULTS
ASTM STANDARD D880-5O
.. ,,,.WAX COATED CARTONS (X WAX)
RemarkS'
'Wire Case
2h hours 20 17 staple pulled out at top
72 hours 20 15 staple pulled out at top
,Alumigpm_Case
2h hours 20 1h staple pulled out at top

72 hours 7, , 20’ . 13 , staple pulled out at top

————v ‘_V

MS

TABLE IX
VIBRATION TEST RESULTS
ASTM STANDARD D999-h8T
POLYE‘I‘HYLENE COATED CARTONS (x POLY)

v—V—

 

 

 

 

 

 

‘Remarks
‘Wire Case
2h hours 20 5 leaks in.bottom seal
72 hours A0 9 leaks in bottom seal
A; m ' ‘ ind ode:
2h hours 20 O
72 hours ho ,. p 0
TABLE X
VIBRATION TEST RESULTS
'ASTMTSTANDARD.D999~A8T
WAX COATED CARTONS (X WAX)
Remarks
‘Wire CaSe
2h hours I 20 6 failure of bottom corners
72 hours 20 1 top side seam failure

AluminmeCaSe
2h hours 20 3 wax failure on bottom seam
72 hours 20 O

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TABLE XVI

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REFERENCES
Arnerioan Society for Testing Materials, Standards on Paper and Paper
Pmdugts andéhigping Containers.

Darden, E. T.Aand Hammer, C. F. "How- to Pick the Right Polyethylene,"
Materials wand Methods 1111:9847, September 1956.

Davies, B. L., The Technolfl of P1aStics, Great Britain: Pitman and
Sons, Ltd., 19149

deBruyne, N. A., and Houwink, R., Adhesion and Adhesives, London:
Cleaver-Hume Press Ltd., 1951. '—

Delmonte, John, The Technolo of Adhesives, New York: Reinhold
Publishing Corporation, 9117.

DuPont Alathon as a Coating Resis for Flexible Materials, Polychemicals
fi Department, duPont Company, Wilmington, Delaware.

 

DuPont Alathon for Specific Pas ka g Needs, Polychemicals Department
duPont Commny, Winnington,De ware.

Flanagan, Thorns, "Adhesives for High Speed Packaging," Package Engi-
neering, Vol. 3, No. 14, April, 1958, p. 25ff.

"Jones New Thermocartoning," Technical Service Bullet_i_n_, R. A. Jones
and Co. 1110., Cincinnati, Ohio. '

National Starch Products Company, Technical Service Bulletin No.fi3Q5fi.

 

Sperati, C. A., and Franta, W. A., "The Molecular Structure of Poly-
ethylene," J. Am; Chem. Soc. , 75, 6110ff, 1953.

Symposium on the Theory of Plastics Extrusion, Ind. and Eng. Chem. , 145,

Wolper, P. K., "Protective Coatings for Packaging," Modern Packaging
Encyplopedia, XXIX, Packaging Catalog Corp., Birstol, Connecticutt,
1333.

Wood, L. J. Jr., "Functional Coatings and Adhesives on Bleached Board,"
Bleached Board Applications Seminar, Packaging Institute 19th
Forum, New York, October 29, 1957.

"Wrapless, Linerless Cartons," Modern Packaging, August 1957, p. 92ff.

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