Molded-in label with removable portion

A multi-layer label to be applied to a blow molded plastic container during the molding process, wherein a removable portion of the label can be easily removed, yet the label provides a smooth and attractive label surface after being molded to the container. Preferably the label includes a removable top sheet composed of a latex impregnated paper releasably adhered to the base sheet at a side opposite the plastic container. The top sheet is adhered to the base sheet by a dry residue adhesive in a manner which allows uniform and simultaneous shrinkage to occur between the base sheet and the top sheet as the molded container cools and shrinks, while also allowing subsequent removal of the top sheet from the base sheet, leaving a nontacky and visually unobstructed base sheet and removed section of the top sheet.

BACKGROUND OF THE INVENTION 
This invention relates to a label of the type generally referred to as an 
in-mold label, which is molded into the surface of a blow-molded plastic 
container at the time the container is manufactured. More particularly, it 
relates to a two-ply label of the foregoing type in which the top ply can 
be easily removed from the container by a consumer, leaving the bottom ply 
attached to the container, with no tacky adhesive residue on either the 
removed top ply or on the remaining base ply. 
It is known in the coupon and label art to provide a two-ply label in which 
a top ply is easily removable, leaving a base label attached to a 
substrate and no tacky residue on either ply. The top ply can be a coupon 
or other promotional device, and the base ply can be a printed label or 
can be a clear material. This type of label is described in U.S. Pat. No. 
4,479,838, which is commonly assigned, and the teachings of which are 
incorporated herein by reference. This type of two-ply label has not 
previously been adapted to use on a blow-molded container where the label 
is molded into the surface of the container. 
Previous attempts to adapt this type of two-ply label to a blow-molded 
container have met with problems such as those caused by the contraction 
of the plastic when it comes out of the mold and cools. The label, being 
made from a different material than the plastic of the container, does not 
shrink at the same rate as the container. The two plies of the label must 
therefore be sufficiently adaptable to this contraction to remain firmly 
enough in contact with each other to provide a smooth surface once the 
bottle has come to room temperature. At the same time, the bond between 
the two plies of the label must be weak enough to enable the consumer to 
readily remove the top ply from the bottom ply. 
This invention overcomes these difficulties to provide a two-ply type label 
which can be molded into a blow-molded container, using standard blow 
molding and in-mold labelling equipment, while affording a smooth label 
surface on the container. 
It is an advantage of the invention to provide a two-ply type label which 
can be molded to a blow molded container. 
It is another advantage of the invention to provide a two-ply type label of 
the foregoing type which affords a substantially smooth label surface on 
the blow molded container. 
It is yet another advantage of the invention to provide a two-ply type 
label of the foregoing type which can be molded to a blow molded container 
without modification to a standard blow molding machine. 
It is still another advantage of the invention to provide a two-ply type 
label of the foregoing type which affords easy removal of the top ply from 
the base label. 
It is another advantage of the invention to provide a two-ply type label of 
the foregoing type without major modifications to standard label 
materials. 
SUMMARY OF THE INVENTION 
The foregoing advantages are accomplished by the present invention wherein 
a label is used in conjunction with a plastic substrate such as a 
container and the label has a base sheet molded to the container and a 
separate removable portion. 
A removable top portion or sheet is composed of a latex impregnated paper 
and is releasably adhered to the base portion or sheet at a side opposite 
the plastic container. The removable top sheet is adhered to the base 
sheet by an adhesive. The top sheet is adhered to the base sheet in a 
manner to allow uniform and simultaneous shrinkage to occur between the 
base sheet and the top sheet yet will allow easy removal of the top sheet 
from the base sheet in such a manner so that when the top sheet is removed 
from the base sheet there is no tacky residue on either sheet. 
In order to achieve the foregoing goals and in a preferred manner, the peel 
strength between the base and top sheets is in the range of 200 to 275 gm/ 
1" width. 
In another preferred manner, the base sheet is composed of paper that is a 
60 lb. paper and the top ply is 48 lb. paper; and the dry residue adhesive 
is a waterborne plasticized copolymer latex material. 
In one aspect of the invention, the plastic container is a blow molded 
bottle, and the top removable portion of the label is a coupon. 
A method of molding a label with a removable portion onto a plastic 
substrate is also provided as well as a label of this type for molding 
onto a plastic substrate.

DESCRIPTION OF THE EMBODIMENTS 
Referring to FIG. 1 of the drawing, the label is generally indicated at 10 
as applied to a typical blow molded container or bottle 11 having a side 
wall 13, a pour spout 14 and a handle 15. The label 10 has a base sheet 
18, which is secured to side wall 13, and a removable top sheet 17 which 
can serve as a coupon, instruction sheet or the like. 
In the embodiment shown in FIGS. 2 and 3, the top sheet 17 of label 10 is 
composed of a paper layer 20 having printing 21 and 22 on both sides. In 
this instance, the paper layer is preferably a 48 lb. super calendered, 
latex-impregnated and clay-coated paper available from Kimberly-Clark Co. 
in Munising, Mich., and is 2.8 mil thick. The base sheet 18 is composed of 
a paper layer 31 having printing 29 on one side. In this embodiment, this 
paper layer 31 is a standard 60 lb. clay-coated in-mold label stock 
available from the P. H. Gladfeter Company in Springrove, Pa., and is 3 
mil thick. This label stock comes with a layer of heat seal adhesive 33, 
such as 33P5 Norprine, available from the Morton Chemical Co., already 
applied to one side. This heat seal layer provides the tight bond between 
the label 10 and the bottle sidewall 13 when the label is applied to the 
bottle 11 in a standard in-mold-labeling process. 
As illustrated in FIGS. 1 and 3 the top sheet 17 is removable from the base 
sheet 18. It has been found that this is best effected by an adhesive 
combination of adhesive layer 23, release material layer 26 and varnish 
layer 28. This combination not only allows the release of top sheet 17 
from base sheet 18, but provides a transparent, non-tacky surface on the 
top sheet 17 and base sheet 18 when they are separated. This avoids the 
problems inherent with tacky adhesive residues on this type of product and 
allows unobstructed viewing of printed material 22 and 29 when the top 
sheet 17 and base sheet 18 are separated. 
The adhesive layer 23 is referred to as a "dry residue adhesive" in the 
previously mentioned U.S. Pat. No. 4,479,838, and is preferably a 
plasticized copolymer water emulsion of ethylene and vinyl acetate 
available from the H. B. Fuller Company of St. Paul, Minn. under the 
designation S-3487. This material is quick setting and has good water 
resistance. For application, it is diluted to a viscosity as measured by a 
40 reading on a Brookfield viscometer employing a number 3 spindle, at 100 
speed. 
The release material 26 is an alcohol based flexo-release varnish available 
from Production Color, Inc. in Oakwood, Ga. under the designation of 
PCF-3512. For application it is diluted to a viscosity of 24 seconds as 
measured in a No. 2 Zahn Cup. 
Varnish 28 is a quick-drying semi-gloss oil can varnish available under the 
tradename F67053 Oil Canister from Inmont Corporation in Neenah, Wisc. For 
application it is diluted to a viscosity of 16 to 18 seconds as measured 
in a No. 3 Zahn Cup. 
Top sheet 17 is produced by applying printing layers 21 and 22 on paper 
layer 20 using any of a number of standard printing techniques. Base sheet 
18 is produced by first applying printing layer 29 on paper layer 31 using 
any of a number of standard printing techniques. Varnish layer 28 is then 
applied over printing layer 29 using an anilox roller with 200 lines per 
inch, a doctor blade and a transfer plate. Release material 26 is then 
applied over the varnish layer 28 using an anilox roller having 800 lines 
per inch, a doctor blade and a transfer plate. The adhesive 23 is then 
applied over release material 26 using an anilox roller having 120 lines 
per inch, a doctor blade and a transfer plate. Top sheet 17 is then 
applied over the adhesive 23 before the adhesive 23 has set, and base 
sheet 18 and top sheet 17 are then nipped together under pressure. 
Typically, all of the foregoing processes are performed on continuous webs 
of material 20 and 31, and the resulting assembly is subsequently die cut 
to form individual labels 10 in the shape and size desired. 
FIG. 4 illustrates the process for applying the label 10 to the container 
11. The label 10 is pulled from a stack of labels by means of a vacuum pad 
50 with a vacuum being supplied by vacuum line 51. Label 10 is positioned 
between two mold halves 42 and 43 of a refrigerated mold, generally 40, 
having the usual vacuum passages 45, 46 and 47, 48, respectively. In the 
instance where two labels 10 are to be applied to the front and back of 
the container 11, two oppositely positioned pads such as 50 would be 
employed to place labels 10 inside both mold halves 42 and 43, as shown in 
the closed mold position of FIG. 4. With the label or labels 10 held in 
place, the mold halves 42 and 43 are closed and molten plastic is blown by 
the blow pin 53 in the form of a hot plastic parison 55 by fluid pressure 
against the walls of the refrigerated mold cavity 52. The molten plastic 
spreads to cover the inside of the cavity. The heat of the molten plastic 
activates the heat seal adhesive 33 on the back of the labels 10. This 
bonds the base sheet 18 tightly to the plastic bottle 11. The 
refrigeration of the mold 40 allows the molten plastic to begin hardening 
immediately upon contact with the walls of the mold cavity 52. When the 
forming process is complete, the mold halves 42 and 43 open, displaying 
the finished container 11 which is removed as the halves 42 and 43 part. 
The container or bottle 11 typically has a considerable amount of flashing 
around it. This flashing material is trimmed off such as indicated at 58, 
by use of the usual male/female dies. This process results in the plastic 
bottle 11 having labels 10 positioned flush with the surface of the bottle 
11, as the labels 10 have been molded directly into the side wall 13 of 
the bottle 11, as shown in FIGS. 1 and 3. 
When label 10 has been applied to the container 11 in the blow molding 
process, the adhesive force required to remove the base sheet 18 from the 
side wall 13 is much greater than that required to separate top sheet 17 
from base sheet 18. Stated in another manner, the adhesion effected by 
combination of the adhesive 23, the release material 26 and the varnish 
layer 28 between the top and base sheets 17 and 18, is less than that 
effected between base sheet 18 and the container side wall 13 by heat seal 
adhesive layer 33. However, it is critical that top sheet 17 adhere to 
base sheet 18 strongly enough that top sheet 17 will not wrinkle when the 
bottle 11 cools and shrinks during the cooling process and that top sheet 
17 will not prematurely release from base sheet 18 prior to separation by 
the consumer. 
The important aspects of molding the labels 10 onto the container 11 so 
that the top sheet 17 will be adequately adhered to and yet can be 
separated from the bottom sheet 18 are the following: 
1. The top sheet 17 must be of sufficient strength and flexibility to 
resist wrinkling and to prevent tearing during removal. The strength and 
flexibility are preferably provided by the use of a latex impregnated 
paper. 
2. The bond between the bottom sheet 18 and the top sheet 17 must have a 
strength, measured by those skilled in the art as "peel strength," weak 
enough that the top sheet 17 can be readily removed from the bottom sheet 
18, but at the same time strong enough that the top sheet 17 will be 
bonded tightly enough to the base sheet 18 so that the top sheet 17 will 
not wrinkle during or after the molding process as the bottle 11 cools and 
shrinks. This peel strength is measured by employing a standard Tag and 
Label Manufacturer's Institute test device wherein the label is tested at 
a 180.degree. angle and a low speed of 8.5. In the embodiment, described 
above, a peel strength in the range of 200 to 275 gm/ 1" width results and 
provides the desired characteristics. 
Preferably, and as described in U.S. Pat. No. 4,479,838, a selected area 
17a of the top layer 17 forming a part of the margin of the top layer 17 
is not adhered to the base sheet 18, as is illustrated in FIG. 1. The 
unadhered portion 17b forms a tab for the convenient grasping of the top 
portion to facilitate its removal from bottom portion 18. This can be 
achieved by limiting the application of adhesive 23, release material 26 
and varnish layer 28 to all areas of the label other than the desired tab 
portion. 
In some instances it may be desired to provide an in-mold label where a 
portion of top layer 17 is not removable. For example, it may be desired 
to provide a removable coupon smaller than the size of label 10. This type 
of coupon is shown as item 62 in FIG. 5, where the same numbers refer to 
the same components as previously described in conjunction with FIGS. 2 
and 3. The difference between the embodiment shown in FIGS. 1, 2 and 3 and 
the embodiment shown in FIG. 5 is that in FIG. 5, the release material 26 
is not applied over the area 61 between the adhesive layer 23 and the 
varnish layer 28. This prevents separation of the section 61, yet allows 
separation of the section 62 between the release material 26 and the 
varnish layer 28. A tear line 60 further facilitates separation and 
removal of coupon section 62. 
This invention is not limited to the specific components described above. 
Other combinations of materials will also work, although a different peel 
strength may be required to achieve the desired characteristics with 
different materials. For example, in the preceding description the top 
sheet 17 was described as a latex impregnated paper with a basis weight of 
48 lbs. If desired, latex impregnated papers of higher or lower basis 
weight could be employed, such as a 42 lb. or 60 lb. paper available from 
Kimberly-Clark Co. Similarly, the in-mold-label stock used in bottom sheet 
18 may also be of various basis weights and can be latex impregnated if 
desired. It is possible to adjust the peel strength achieved by the 
combination of adhesive 23, release material 26 and varnish 28 by varying 
the amount of the various components applied to base sheet 18 or by 
varying the application viscosity of the components. 
The adhesive 23, the release material 26 and the varnish 28 have been 
described in a combination which provides the preferred peel strength and 
release characteristics in the described embodiment. Other adhesives or 
varnishes or other materials, alone or in combination, may also be found 
to be useable in place of the described combination to achieve the desired 
strength and release characteristics or may be necessary to provide the 
required properties in different molding conditions or with different base 
or top sheets. 
While the base sheet 18 has been described as being purchased with a 
previously applied heat seal adhesive layer 33, the heat seal adhesive 
layer 33 could be applied at the same time the label 10 is being produced. 
Also while the top sheet 17 is described as having opposing sides of 
printing 21 and 22, only one side could be printed, if desired. The top 
sheet 17 is preferably employed as a coupon which is removable. However it 
could also be employed as some other type of promotional vehicle or as an 
instructional panel. Neither is it necessary that any particular plastic 
composition be used for the container 11 to which the label 10 is applied. 
In this instance, it is a high density polyethylene. All that is necessary 
is that the resin is able to be used in a blow-molding application. 
It is understood that the present invention is not limited to the 
particular construction and arrangement of parts illustrated and 
disclosed, nor to the materials specified, nor to the particular steps 
disclosed herein, but embraces such modified forms thereof as come with 
the scope of the following claims.