Method and apparatus for applying plastic sleeves to containers

The present invention relates to method and apparatus for applying a tubular plastic sleeve or label to a rigid base article or container, such as a glass or plastic bottle. The sleeve may be formed immediately prior to its application and be comprised of oriented, heat-shrinkable, thermoplastic material which is telescopically assembled over the container while both are conveyed through a coincidental aligned path. The container preferably consists of a hollow glass or plastic bottle held upright by its neck or finish portion. The tubular sleeve is made slightly larger in diameter than the container body portion. The sleeve is telescoped upwardly over the container body portion and held in aligned relation during its transport through a heat-shrinking tunnel oven. Electrical heat energy having a high level of infra-red energy is employed to heat-shrink the sleeves in a thermoconstrictive operation during such transport, the sleeve being contracted into snug engagement with the container body portion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the manufacture of composite containers and 
primarily to the assembly of a hollow sleeve or label onto the body 
portion of a container for heat-shrinking in situ thereon. The sleeve may 
be formed immediately prior to its application to the container, or, 
alternately, the sleeve may be in preformed, flattened condition and taken 
to a position immediately below the container where it is opened and moved 
into telescopic alignment with the container held in upright relation. The 
final shrinking of the sleeve tightly around the body portion of the 
container is performed by subjecting the sleeve to controlled infra-red 
radiation supplied by electrical energy. 
2. DESCRIPTION OF PRIOR ART 
This invention comprises an improvement over the methods and apparatus 
disclosed in issued U.S. Pat. Nos. 3,767,496, issued Oct. 23, 1974; 
3,802,942, issued Apr. 9, 1974; and 3,959,065, issued May 25, 1976, all of 
which are commonly owned by the same assignee as the present application. 
In each of these disclosures, a tubular sleeve is formed which is 
telescopically assembled onto the article from below by a push-up 
mechanism. None of these disclosures pertain to the thermal constriction 
of a thin, tubular sleeve of thermoplastic material which is telescoped 
upwardly over the upright container during their coincidental alignment 
and retention of the sleeve in place for its selective and controlled 
heating using infra-red radiation for thermoconstriction. 
In many of the previously-disclosed methods and apparatus for making 
composite containers having an integral plastic sleeve or label thereon, a 
glass or plastic bottle is loaded onto a conveyor retained by its finish 
prior to mounting the plastic sleeve. The plastic sleeves are carried on 
an underlying turret to pass into alignment with the bottles and serially 
moved vertically upwardly into telescopic assembly over the body portion 
of the bottles. The sleeves are then carried on the bottles into a heating 
apparatus such as a gas-fired tunnel oven wherein appropriate physical 
conditions shrink the sleeves into close-fitting conforming arrangement 
surrounding the bottle body surfaces where assembled. The heating 
apparatus has commonly consisted of a gas-fired, hot air oven through 
which the bottles are passed, the oven temperatures ranging from about 
170.degree. F. to 800.degree. F., depending upon the plastic material 
selected to form the sleeves. 
U.S. Pat. No. 3,959,065, owned by the common assignee of this application, 
discloses method and apparatus which assure against dislocation of the 
sleeve on the bottle without external handling mechanisms being required 
to restrain the sleeve in place between its assembly point with the bottle 
and the shrinking oven. U.S. Pat. No. 4,048,281, also owned by the common 
assignee of this application, discloses a method of supporting the sleeve 
from underneath during heating for its shrinkage while both the bottle and 
sleeve are conveyed, a cooled holding bar being used. 
Further, the cap sealing of bottles has been conventionally performed in 
recent years to provide for reasons of sanitation, pilfer-proofing, safety 
and appearance, the additional step of placing over and around the neck of 
the bottle, as well as preferably over at least part of its closure, a 
tubular sleeve of heat-contracting, synthetic resin material, severed to a 
prescribed length, and then shrinking the sleeve with hot air to conform 
to the bottle by thermal contraction. The synthetic resin tubing is 
usually pressed flat and delivered in rolls in many production processes, 
and since the tubing may or may not stay fully flattened, particularly 
where it is comprised of extremely flexible and resilient material, 
inefficiencies can and do result when the severed lengths of tubing are 
fitted onto the bottle necks. 
It is also possible to apply the tubes around the bottle necks without 
preforming the material, as taught by U.S. Pat. No. 3,861,918 to Muto; 
however, such method normally requires the application of a bonding agent 
to the bottle neck for firm, permanent adherence of the sleeve. The method 
and apparatus disclosed by this patent are exceedingly more complex and 
prone to occasionally misapplying the tubular band or label. U.S. Pat. No. 
2,852,899 to Murrell discloses a collar feeding mechanism which is 
designed to remove only the lowermost collar from a nested stack by 
frictional engagement with its inner surface. The collars are preformed 
and nested tightly into a stack from which they are deliverable onto the 
container necks. 
Normally when heat-shrinkable thermoplastic sleeves are mounted on 
container such as glass or plastic bottles having generally cylindrical 
body portions, with the containers in upright relation for heat-shrinking 
a relatively large, tubular sleeve therearound, special care must be taken 
not to overheat the bottle during such heat shrinkage, especially in the 
case of plastic bottles, which can deform their sidewalls and alter their 
specific volume. It is to solve this problem, as well as to provide more 
efficient heat shrinkage that the present invention is primarily directed. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a method for heat-shrinking 
tubular sleeves of thin, thermoplastic material on either glass or plastic 
bottles, the sleeves being placed on upright containers while both are 
conveyed in coaxial vertical alignment. The sleeves are preferably 
comprised of thin film or foam oriented thermoplastic material adapted to 
shrink in a circumferential direction and the containers preferably 
consist of glass or plastic bottles having right-cylindrical body 
portions. 
The present invention, as disclosed hereinafter in a specific preferred 
embodiment, provides both method and apparatus for applying a preformed, 
extremely-flexible, thin, tubular band or sleeve to major exterior 
surfaces of an upright container where it is positively restrained prior 
to subsequent controlled heat shrinking of the sleeve using infra-red 
energy onto the container surfaces in final conforming relationship. 
Normally, in the case of glass containers, they are preheated from about 
100.degree. F. to 200.degree. F. prior to applying the sleeves. In the 
case of plastic containers, no significant heating can be tolerated due to 
their thin sidewalls and heat sensitivity. The invention permits 
telescopic assembly of the band or sleeve around the container body 
portion, the sleeves being formed of flexible film, foam or film-foam 
laminated material. An individual sleeve is opened prior to moving same 
telescopically in an upward direction over the major exterior surfaces of 
the container held in upright relation. The band is temporarily retained 
in place on the container body portion until it is fully heat shrunken 
using electrical energy into conforming, essentially wrinkle-free, 
permanent relationship thereon. 
The method may employ a rotary turret mechanism adapted to form a tubular 
thermoplastic sleeve thereon and to open same into container-mounting 
configuration. The rotary turret permits precise axial and vertical 
alignment of the container body portion and opened sleeve so that the 
sleeve may be telescoped to an essentially all-encompassing position 
around the container body. The present invention relates to the 
heat-shrinking operation which utilizes improved and controlled heating of 
primarily the sleeve member, and not the container. 
Another feature of the invention is the rotary movement of the combined 
tubular heat-shrinkable, plastic sleeve surrounding the container body 
region while the container is supported upright by its neck region in 
offcenter relation within the heating apparatus for convenient and 
economical application of the sleeve onto such containers at production 
speeds. Upright retention of the container and sleeve permits the sleeve 
to shrink around the body portion without wrinkling due to a gravity 
effect.

DESCRIPTION OF PREFERRED EMBODIMENT 
The apparatus for producing containers with plastic sleeves thereon 
frequently consists of rotary turret machine (not shown) which is adapted 
to fabricate the tubular plastic sleeves immediately prior to their 
mounting on the containers. The containers 10 preferably consist of rigid, 
hollow, glass or plastic bottles which normally are in unfilled condition 
just after manufacturing. A web of stock thermoplastic material is 
commonly delivered from a roll through a suitable set of guide rolls onto 
a feed drum of the turret machine on which the web is severed into 
individual blanks for a cutter roll. The cutter roll operates in 
tangential relation to the feed drum to sever the blanks to a prescribed, 
uniform length. The blanks are each then wrapped on an individual 
rotatable mandrel which is mounted on the rotary turret of the machine. 
Such machine is disclosed in detail in U.S. Pat. No. 3,802,942. 
The mandrels are usually mounted in series in equispaced, vertical 
alignment on the rotary turret which is continuously rotated in a given 
direction. The sleeves are tightly wrapped on the mandrels and their 
overlapped ends are joined by a fusion-type axial seal. The forming of the 
blanks into presized sleeves on the rotating mandrels during the winding 
and sealing cycles is well known in the art. 
After the tubular sleeves are fully formed having a diameter slightly 
greater than the container body portion and an axial length comparable to 
the container body height, they are ready to be mounted on the container 
bodies. The sleeves are preferably formed from a flat, decorated blank 
immediately prior to their opening into tubular form and being mounted on 
individual containers. 
After the tubular sleeve 12 is formed having an axial seam, it is then 
combined with the container 10 into a composite package. The sleeve is 
moved upwardly from the mandrel by a stripping element onto the container 
with the components in coaxial, vertical alignment during their transport. 
The sleeves may be comprised of thin, flexible, oriented, thermoplastic 
film such as polyvinyl chloride, polyethylene, or polystyrene. The film 
may have a thickness of from 11/2 to 2 mils in the case of polyvinyl 
chloride, for example. Foamed, oriented polyethylene having a thickness 
ranging from 8 to 13 mils or foamed oriented polystyrene having a 
thickness ranging from 7 to 17 mils may also be used to form the sleeves. 
The sleeves may vary in thickness from 1/2 to 20 mils, depending upon 
selection of the desired thermoplastic material. The sleeves may also be 
comprised of a film-foam, laminated, thermoplastic material having the 
stated thickness, the film layer on the exterior surface for most 
desirable printing and decorating of the sleeves. 
FIG. 1 illustrates in part a container retention conveyor 15 which has a 
lineal reach extending in tangential alignment to sleeve-forming rotary 
turret designated by the numeral 16 in FIG. 2. The conveyor has a 
spaced-apart series of container chucking members 17 located in equispaced 
relation throughout its endless length adapted to grasp and retain the 
finish portion 11 of a container held in upright relation over the 
adjacent turret. The plurality of jaw elements of each chuck is adapted to 
being cammed open and closed by suitable camming means located along the 
conveyor path. The sleeve 12 is moved upwardly by the stripper element 
(not shown), mounted on the turret to raise the newly-formed sleeve 
telescopically around the container body portion when in vertical and 
axial alignment therewith. It is preferred to preheat the container in the 
case of glass bottles just prior to application of the sleeve, preferably 
to a temperature of about 100.degree. F. to 200.degree. F. However, no 
preheating is required, or desired, in the case of plastic bottles which 
are heat sensitive due to their normally thin sidewalls. 
The sleeve is thus moved telescopically upwardly to surround the container 
in closely-fitting, loose relation. The lower extremity of the sleeve is 
retained in precise, vertical alignment with respect to the container body 
portion in the tunnel oven by a horizontally-extending retention rail 20 
as shown in FIGS. 2, 3 and 4. The lower edge of the sleeve is thus 
positively restrained to permit its uniform shrinkage around the container 
body portion in precise position. The sleeve is initially held in place on 
the container by an intermediate flat plate 23 which extends between the 
turret and the tunnel oven. Rail 20, which is preferably a hollow pipe, 
has a fin-type upper edge member 21 which physically contacts and 
restrains the sleeve at one edge during its rotation. 
As shown in FIGS. 1 and 5, the containers 10 are each retained in upright 
position held by their neck with a tubular sleeve 12 therearound and moved 
horizontally into and through a tunnel oven 15. The oven extends 
horizontally a sufficient distance to permit controlled heat shrinking of 
the sleeves onto the containers. The neck retention chucks 17 are rotated 
to rotate the containers and their retained sleeves during passage through 
the tunnel oven. The oven is open at an upper region to permit transport 
of the containers, the chucks passing through a lineal, upper opening 
extending throughout the full length of the oven. 
The chucks 17 are each rotated by a friction roller 30 mounted on an 
intermediate region of the chuck spindle. The roller 30 is fully-rotatable 
to drive the spindle and the attached chuck 17. The roller 31 is driven by 
a rubber drive belt 31 which frictionally contacts the roller during its 
passage over the oven. The drive belt 31 is driven around an upper region 
of the oven over which the container conveyor extends. The rate of lineal 
movement of drive belt 31 and the conveyor speed, in combination, control 
the rate of container rotation. 
The oven 15 has a series of three electrical heaters 25, each having 
considerable horizontal extent mounted in vertical array along each side 
of the oven. The three heaters 25 are arranged in an arcuate, 
vertically-aligned pattern facing the top edge, central body and lower 
edge portions of the sleeve. The heaters comprise similar electrical strip 
heaters adapted to emit a high level of infra-red radiation. 
The heaters comprise the heat-energy radiating source and the thermoplastic 
sleeve the target. When the source is moved closer to the target, the 
amount of radiant energy received by the target from the source heater is 
increased. It follows that the power required to heat the product to the 
same temperature in the same time, at a closer distance, is less than that 
required at a further distance. 
The heaters are preferably comprised of Watlow Radiant Panels which 
constitute total area heat sources, or strip heaters, made and sold by the 
Watlow Company, St. Louis, Missouri. The entire surface area of such 
panels is heat generating. By distributing the heat generated over a large 
area, radiant panels operate at low, uniform temperatures. These panels 
deliver heat so evenly that the target material can be positioned as close 
as one inch from the surface without hotspotting or streaking. Watlow 
Panels maintain a constant efficiency rate, and the power input does not 
need to be increased with time. The subject radiant panels can be mounted 
much closer to the work further improving efficiency. 
At the lower operating temperatures of 800.degree. F. to 1100.degree. F. 
(compared to 1200.degree. F. to 1600.degree. F. with conventional units) a 
larger portion of the energy is emitted by the panels in the 3 to 4 micron 
wavelength range. Such energy is readily absorbed by most materials, 
including clear and translucent plastics. Less energy is wasted in the 
short, visible, infrared wavelengths than by the higher temperature units. 
The one-inch wide emitter strips have a sinuated nickel-chromium 
resistance wire which is electrically insulated from a surrounding steel 
sheath by high temperature mica, and preferably have a power of 15 watts 
per square inch. The emitter is especially treated with a black coating 
that provides a 93% efficient radiating surface. Normally, an apertured 
grille member 26 is mounted in front of each heater 25 to further improve 
heating uniformity and efficiency. 
Heat transfer rates for conduction and convection vary directly with the 
temperature difference, i.e., doubling the temperature difference doubles 
the heat output. Infra-red radiation transfer rates vary with the fourth 
power of the absolute temperature, i.e., doubling the temperature 
difference increases the heat output by sixteen times. The infra-red rays 
penetrate the surfaces of many materials from 0.010 to 0.050 inch depth. 
The conducting characteristics of the materials can then carry the heat to 
the interior. 
In the present process, the telescoped sleeve on the container is heated by 
direct heat transfer. The air between the heaters and the target plastic 
sleeve is not heated, only the solid target material. The infra-red 
radiation has 3.5 and 5.8 absorption peaks which generally coincide with 
the peak absorption range of a number of polymeric materials. Thus, a 
greater portion of the heat delivered is absorbed in this range. This 
absorption is also critical to the inks commonly used to decorate the 
plastic sleeve materials. The wavelengths emitted by the radiant panels 
are less sensitive to differentiation by different inks, i.e., they are 
less color sensitive to radiant heating effects. 
Whether the oriented sleeves be formed of film, foamed or film-foam 
laminates, the plastic materials are all acted on in the same general way, 
by heating using the radiant panels. With such heat-shrinkable materials 
being similarly acted upon on heating, the container may be a glass or 
plastic bottle, or also a metal can. The plastic bottles can have the 
sleeves heat-shrunk thereon without losing or changing volume, or 
deforming their sidewalls. By proper location of the strip heaters in the 
arcuate pattern, the heat delivered to the upper neck or finish portion of 
the bottles can be cut-off or minimized. The sleeves may be formed of a 
wide variety of thermoplastic materials such as polystyrene, polyethylene 
or polyvinyl chloride, either in film or foamed condition. 
The containers 10 bearing the sleeves 12 are moved through the tunnel oven 
15 while rotated by chucks 17. The containers are moved through the lineal 
tunnel in an off-center arrangement in a straight line while rotated about 
their axes. The side of the container which is moving against the lineal 
direction of travel has a higher surface speed than the air its passing 
through and the emitter. The side which is moving with the lineal 
direction of travel has a slower surface speed than the air its passing 
through and the emitter. This causes a heat imbalance from one side of the 
container to the other. In order to correct this imbalance, the side which 
is traveling faster past the emitter is moved closer thereto, and thereby 
the other side is moved further away. The heat loss that is due to such 
rotation and distance is calculable. Approximately 10% heat loss is due to 
the air speed when the one sleeve side is not presented to the same single 
point on the emitter as the other. The sleeve is normally heated from 
about 145.degree. F. to about 230.degree. F. during the shrinking 
operation. 
In the case of processing about 150 plastic bottles per minute through a 4 
to 8 foot oven, about 6.8 seconds of exposure time is required. The 
containers, in case of 2 liter volume plastic bottles, are located 
off-center so that the near side is about 3 inches from the emitters and 
the far side is about 5 inches therefrom. In this manner, the two sides of 
the container sleeves are subjected to nearly equal amounts of heat for 
smooth and uniform heat-shrinkage. 
As stated, upon entry into the oven, the sleeve is retained at its lower 
edge by holding rail 20. The sleeve is so retained through about half the 
length of the oven to ensure its precise positioning on the container 
body. Once the sleeve starts to contract around the container body, it 
adheres thereto and the holding rail may be ended. Such adherence or 
tacking once it occurs prevents vertical movement of the sleeve with 
respect to the container. During further travel of the container and 
sleeve through the oven, the radiant heat against upper and lower edge 
portions, as well as the central body portion of the sleeve causes overall 
thermal contraction of the sleeve. The sleeve then assumes the full 
exterior configuration of the container where applied. 
FIGS. 4, 5 and 6 show the sleeve 12 being held at its bottom edge during 
container rotation upon its entry into the oven. At this time, the sleeve 
loosely surrounds the full body portion of the right-cylindrical container 
except for the retained neck and finish portion. FIG. 5 shows the position 
of the container located off-center with the infra-red radiation emitting 
from the juxtaposed arrays of heaters to shrink the sleeve. The initial 
tacking and thermoconstriction of the sleeve normally occurs upwardly and 
downwardly from its central region where the heat is concentrated. 
The holding rail 20 is water cooled, such as by a continuous loop 27 of 
piping as shown in FIG. 8, to prevent its overheating within the oven. 
The aforesaid procedure for heat-shrinking the sleeve onto the container 
provides an improved labeled container having unique properties. The 
container is able to be fully surface-covered, as desired, such as where a 
very thin, flexible, thermoplastic material is employed. The use of thin, 
oriented, polyvinyl chloride film having a thickness of about 1 to 11/2 
mils may be readily applied in label form to glass or plastic bottles to 
smoothly cover the body area without distortion or roughness. The 
apparatus may be employed interchangably with both glass and plastic 
bottles with only minor adjustments being made. 
Various modifications may be resorted to within the spirit and scope of the 
appended claims.