Method for producing a printed thermoplastic resin tape for packaging

A thermoplastic resin tape on which a desired marks or the like are printed is formed and then is pressed by embossing rollers to effectively disorder the micelle particle arrangement in the resin tape.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for producing a tape or band for 
wrapping around packages wherein the tape is made of a thermoplastic 
resin, and is printed thereon, and is usually operated upon for packaging 
by a packaging machine. 
Conventionally, packaging tapes with printings thereon have been produced 
by an extrusion method in which thermoplastic resin material is formed 
into a flat-surfaced tape and then the tape is treated with a printing 
device so as to print a desired figures and/or marks thereon. 
However, it has been found that the conventional method has defects not 
only in that the tape itself presents a serious disadvantage but also in 
that one fails to obtain the desired printing. Specifically, when the 
packaging tape of thermoplastic resin materials is extruded and extended 
up to 5-7 times as long as the original length of the materials in the 
lengthwise direction, the micelle particle arrangement is produced within 
the resin materials in the lengthwise direction, thereby often producing 
objectionable cracks or splits in the lengthwise direction of the extruded 
resin material. Furthermore, it has been found that the printings on the 
tape are faded out during a packaging operation by a packaging machine, 
which will be described below, since the tape has a flat surface and 
moreover the tape is printed on the flat surface thereof. 
Accordingly, an object of the present invention is to provide a new method 
for producing a thermoplastic resin packaging tape which has printings 
thereon, wherein the printing does not fade out or discolor but keeps the 
printings in a desired manner. 
Another object of the present invention is to provide a new method for 
producing a packaging tape which is made of thermoplastic resin materials 
and has printings thereon, wherein the printed tape prevents the resin 
tape from cracking or splitting in the lengthwise direction. 
According to the present invention, there is provided a method for 
producing a thermoplastic synthetic resin tape for packaging, comprising 
the steps of forming a tape, annealing the tape, printing the tape on the 
surface thereof, and pressing the tape to effectively disorder the micelle 
particle arrangement in the tape.

DETAILED DESCRIPTION OF THE INVENTION 
In FIGS. 1a and 1b which are explanatory schematic side views of the 
apparatus used in the process of the present invention, a thermoplastic 
synthetic resin material 1 which is produced by an extrusion device 2 
having a hopper loader 2a in a known method, which will not be described 
herein since it is well known in the art, is fed to a first cooling device 
3 such as a water tank. The water temperature of the first cooling device 
3 is kept below 20.degree. C since a tension of the extruded resin 
material which is sensitive to temperature is influenced by the 
temperature of the water tank. After the first cooling step, the extruded 
resin material 1 is fed to a first receiving device 4 having rollers as 
illustrated so that the cooled resin material may contain little water 
therein. Then, the resin material is fed to a heating device 5. The 
heating device 5 may be either of dry-type or of wet-type. However, in 
either type of the heating device a care must be taken that heating 
temperature should be kept about 95.degree. - 100.degree. C. In this 
instance, the resin material is in the form of a continuous band since the 
extruded resin material has been treated with the first receiving device 4 
as described. The band-like resin material treated with the heating device 
5 is then fed to, and treated with, a second receiving 6 device which is 
similar with the first receiving device 4 and has three rollers as 
illustrated. By the second receiving device 6 the band-like resin material 
1 is pressed by the cooperation of the rollers 6a, 6b, 6c and is extended 
to an extent of 5 to 7 times longer than the original resin material. 
Thus, a tape of synthetic resin materials is produced. Then, the resin 
tape is fed to an annealing device 7 for the purpose of preventing the 
tape from objectionable shrinkage. The applicant of the present 
application has found that the objectionable shrinkage will occur when the 
tape is left as it is after the resin material is pressed and extended to 
an extent of 5-7 times by the second receiving device 6. This is due to 
the fact that the tape is formed by the 5-7 times extension as described 
above. Also, the applicant has found from his experiments that a resin 
tape as long as 1 meter generally shrinks to 0.92 meter when the tape is 
not treated by the annealing device 7. The annealing device 7 has 
temperature of 90.degree. - 100.degree. C, but preferably 97.degree. - 
99.degree. C which, the applicant the found, is desirable for the purpose 
of preventing the above-stated shrinkage in the tape. 
After the resin tape is treated with the annealing device, the tape is fed 
to a printing device 9 by way of a third receiving device 8. The printing 
device 9 has a printing roller having a desired letters figures and/or 
marks disposed thereon, which will be described below with reference to 
FIG. 2. By the printing device, desired letters, figures, and/or marks are 
printed on the surface of the resin tape. Then, the printed tape is fed to 
an embossment device 10 to form concavo-convex area on the surfaces of the 
tape to effectively disorder the micelle particle orientation of the tape 
so as to prevent an objectionable splitting from ocurring in the 
lengthwise direction of the tape. The embossment device 10 will be 
described below with reference to FIGS. 3A and 3B. After the printed tape 
is treated with the embossment device 10, the tape which has now 
concavo-convex area on the surfaces thereof is fed to a second cooling 
device 11 to completely cool the tape which still keeps rather higher 
temperature. The cooling device 11 keeps the temperature therein below 
20.degree. C. Thus, the production of the desired tape on which desired 
marks, etc., are printed thereon is completed. Then, the tape is wound by 
a winding device 14 through a rotary water separator 12 and a pair of 
drawing rollers 13. As illustrated in the drawing, the steps described 
above are carried out continuously and sequentially. 
In FIG. 2 which shows principal parts of the printing device 9, the device 
has a printing roller 15 which has desired letters, figures and/or marks 
carved thereon, a roller 16 above the printing roller 15 so that the resin 
tape may be tightly pressed by the roller 16 and fed between the two 
rollers 15, 16. The printing device 9 further comprises an ink vessel 17 
below the printing roller 15 so that at least a rotary surface of the 
printing roller 15 may contact an ink contained in the ink vessel 17. The 
ink may be of any type but it may preferably be of immediate-drying type. 
In FIG. 3A, the synthetic resin tape 1 on which desired marks have been 
printed by the printing device 9 is delivered to the embossment device 10. 
The embossment device has embossing rollers 20a and 20b. As shown in FIG. 
3A, the rollers 20a and 20b have concavo-convex portions, i.e., embossed 
area, or their entire rolling surfaces so that the tape may be embossed on 
the entire surfaces of the printed tape. As shown in FIG. 4, a printed 
portion of the concaved area 1a of the tape cannot be touched with 
workman's hands or the like. Thus, even though a printed portion of the 
convexed area 1b of the tape should fade away during an operation of 
packaging machine, which will be described below, or with hands, the 
printed portion of the concaved area 1a remains as it and is not faded 
away. 
More preferably, from the view point of the characteristics of the tape, as 
illustrated in FIG. 3B, a thermoplastic synthetic resin tape 1 which is 
printed thereon is provided with a number of small indentations on the top 
and bottom surfaces thereof so that the tape has concavo-convex portions, 
which will be identified hereinafter as embossed portions 1a and 1b. The 
tape 1 is further provided on both surfaces thereof with a number of 
circular non concavo-convex portions, which will be identified hereinafter 
as non-embossed portions 1c. The non-embossed portions 1c occupy a 
relatively wide area on the tape 1 and are disposed at regular intervals 
on the central part of tape so that the non-embossed portions are aligned 
with one another and surrounded by the embossed portions as clearly shown 
in FIG. 3B. It is preferable that the total area occupied by the 
non-embossed portions 1c lies within the range of from 10% to 50% of the 
entire surface area of the tape 1. If the non-embossed portions 1c fall 
outside of the above-described range, either the desired rigidity cannot 
be obtained, or defective splittings will appear in the longitudinal 
direction of the tape. More specifically, if the non-embossed portions 
occupy an area less than about 10% of the whole tape area, a favorable 
rigidity in the tape will not be expected and a strain or flection will be 
produced on both sides of the tape; and if the non-embossed portions are 
more than about 50% of the entire surface area of the tape, prevention of 
cracking or splitting cannot be achieved due to the micelle particle 
arrangement in the thermoplastic synthetic resin material. Thus, it is 
important to have the non-embossed portions formed within the 
above-described range. 
The printed thermoplastic resin tape 1 having a predetermined thickness and 
width is fed into the nip of a pair of embossing rollers 20a and 20b and 
pressed by the rollers. Both rollers 20a and 20b have a number of small 
studs on the surface thereof which form a concavo-convex area 21 on the 
rolling surface of the rollers. The rollers are further provided with 
relatively large non-embossing portions 22 on the rolling surfaces thereof 
so that the non-embossed portions are surrounded with the concavo-convex 
area 21. The total of the area of the non-embossed portions on the rollers 
should be within the range of 10-50% of the entire effective rolling 
surface of the rollers so as to form, on the tape, the non-embossed 
portions 3 which lie within the range 10-50% of entire surface of the tape 
as described before. The non-embossed portions 22 formed on the rollers 
20a and 20b are of a circular shape and disposed at regular intervals on 
the rolling surfaces of the rollers, so that the non-embossed area 22 on 
each of the rollers are aligned with one another on the central portion of 
the rolling surface. The studs 23 each has a thickness which is at least 
as great as the thickness of the tape. The embossment rollers 20a and 20b 
are assembled in a known way such that the non-embossed portion of the 
roller 20a will be brought into alignment, and coincide with the 
non-embossed portion of the other roller 20b when the both rollers 20a and 
20b are rotated so as to form the embossed and non-embossed portions on 
the base tape 1. 
When both of the rollers 20a and 20b are rotated in opposite directions as 
illustrated by arrows in FIG. 3B, by a known driving mechanisms (not 
shown), the thermoplastic synthetic resin base tape 1a is fed into and 
pressed by the rollers 20a and 20b to continuously form the embossed 
portions 1a, 1b and non-embossed portions 1c, and is continuously 
delivered at a speed of 70 m/min. in the direction shown by the straight 
arrow of FIG. 3. The pressure applied to the tape 1 by the two rollers 20a 
and 20b is about 3 kg. m.sup.2. Thus, the tape 1 of the invention is 
produced by rotating the rollers 20a and 20b which have embossed areas 21 
and non-embossed portions 22 at regular intervals. 
In the packaging tape thus produced as described above, the non-embossed 
portions 1c are formed on the tape at regular intervals on the central 
area of the tape so that the non-embossed portions 1c are surrounded by 
the embossed portions 1a, 1b. The rollers 20a and 20b play a role not only 
to form the embossed and non-embossed portions but also to rearrange 
effectively the micelle particles to a more disorderly arrangement in the 
synthetic resin material of the tape 1 so as to prevent splitting in the 
longitudinal direction of the tape. 
A packaging operation will be described with reference to FIGS. 5 and 5A, 
the latter being a sectional view taken along V--V in FIG. 5, showing a 
general type of a packaging machine known per se. First the construction 
of the packaging machine will be explained. The packaging machine 30 has 
an arch-shaped fixed frame 31, a holding member 33, which is movable up 
and down, a clamping member 35, a limit switch 36, a movable metal plate 
37, a heated plate 38 which is movable in the lateral direction, a cutter 
39, a delivery roller 41, a rewinding roller 42, and a reel 44 on which 
the tape is wound. The limit switch 36 is electrically connected (not 
illustrated) to the delivery roller 41 and to the rewinding roller 42. 
Each of the rollers 41 and 42 has its own idler roller 41a and 42a 
respectively, which are disposed adjacent to an inlet 34 of the machine, 
the inlet 34 being in communication with a guide member which will be 
described with reference to FIG. 5A. As shown in FIG. 5A, the packaging 
machine further comprises, on the inner side of the arch-shaped fixed 
frame 31, a guide member 32 which has ledges 32a and 32b projecting in 
opposite directions toward each other. The guide member 32 is made of 
metal and is so formed that the ledges 32a and 32b are pivotable, as shown 
by the phantom lines in FIG. 5A, so that the tape 1 which is delivered 
within the guide member 32 can be forcibly removed from the guide member. 
The guide member may be of any shape or configuration provided that it can 
be removed therefrom by a pulling operation of the tape, the operation 
being described hereinafter. 
With respect to a packaging operation, an article 45 to be packed is placed 
in position as shown in FIG. 5. The tape 1 is delivered within the guide 
member 32 from the reel 44 around the rollers 43a through 43f and the 
inlet, by driving the delivery roller 41. The guide member 32 is disposed 
on the inside surface of the fixed frame 31. When the leading end of the 
tape 1 is delivered through the guide member 32 to come to the 
predetermined position below the movable metal plate 37, the limit switch 
36 is actuated to stop the rotation of the delivery roller 41, and to lift 
up the holding member 33 at the same time so as to firmly press or push 
the tape onto the movable metal plate 37 at the place adjacent to the 
leading end of the tape. Thus, the leading end portion of the tape is 
locked or grasped by the two members 33 and 37. After the leading end 
portion of the tape is locked, the delivery roller 41 and the free roller 
41a are released and the rewinding roller 42 is driven so as to reverse 
the direction of the tape. When the tape is pulled by the reversing 
operation of the rewinding roller while the leading end portion of the 
tape is still locked, the tape is forcibly removed from the guide member 
32. In this instance, the ledges 32a and 32b of the guide member are 
forcibly pivoted by the tape which has been pulled by the rewinding roller 
42 as described above. The pivotal movement of the ledges are shown by the 
phantom lines in FIG. 5A. Continued operation of the rewinding roller 42 
forces the tape 1 to come into contact with the article 45 so that the 
tape is wound tightly around the article 45. 
After the tape is wound tightly around the article by the operation of the 
rewinding roller 42, the heat plate 38, which is heated by a heating 
device (not illustrated) is inserted below the leading end portion of the 
tape so that the heated plate 38 slightly touches the lower surface of the 
leading end portion and is positioned between and adjacent to the two 
layers of the tape. Immediately after the heated plate is inserted in 
position, the clamping member 35 is lifted a little bit so that the other 
layer of the tape lightly contacts the lower surface of the heat plate 38. 
At this time, the two layers of the tape are thermally molten or fused at 
one side of each layer. After the lower surface of the upper layer (i.e., 
the leading end portion) and the upper surface of the lower layer of the 
tape 1 are thermally molten, the clamping member 35 is lowered and the 
heated plate 38 is then removed. Then, the clamping member 35 is lifted up 
again to make the thermally molten tape layers contact each other. 
After the thermal welding is completed between the two layers of the tape 
as described above, the movable metal member 37 is removed from the path 
of the tape just like the heat plate 38 was, and the tape is cut with the 
cutter 39 so as to complete the packaging operation. The cut portion of 
the tape will become a new leading end of the tape for another packaging 
operation. The driving mechanism for the rollers 41, 42, clamping member 
35, heat plate 38, etc. is not disclosed since the mechanism is known per 
se in the art and not the subject matter of the present invention. 
According to the present invention, since the thermoplastic synthetic resin 
tape is treated with the embossment device to effectively disorder the 
micelle particle arrangement in the tape, no splitting or cracking will 
present in the lengthwise direction of the tape. Further, since the 
printings in desired manners or configuration is conducted before the 
embossing step in which the tape with printings thereon is provided with 
indentations on both surfaces thereof to effectively disorder the micelle 
particle arrangement, the printings cannot fade away particularly at the 
area of indented portions of the tape. Thus, the printed tape produced by 
the present invention complies with the requirement of the industry.