JP5182660B2 - Thin container with in-mold label - Google Patents

Description

  The present invention relates to a thin container with an in-mold label in which a label is attached simultaneously with blow molding.

As a means to achieve the display of decorative patterns and product names and explanations on the surface of synthetic resin containers by blow molding, a label printed with decorative patterns or product names and explanations on the surface is placed on the body surface of the container body Many means of sticking are used.
For example, Patent Literature 1 describes a thin plastic bottle in which a label is bonded and integrated on the outer peripheral surface of a body portion. However, as in Patent Document 1, after forming a thin container, a process of supplying the label and the container into the labeling mold is necessary, and there is a problem that production efficiency and energy efficiency are inferior.

  On the other hand, as one of the methods for sticking the label, there is a so-called in-mold molding method in which when the container body is blow-molded, the label is set in advance on the molding die surface and stuck simultaneously with the molding.

In this in-mold molding method, labeling to the container body is achieved at the same time as the molding of the container body, and no special separate process of pasting work is required, and between the surface of the container body and the in-mold label. Since there is no step, there is no risk of deterioration of the appearance or tactile sensation of the container due to this step, and reliable and stable sticking of the label to the container body is ensured regardless of the thinness of the container body. It has an excellent effect of being able to.
JP 2002-321722 A

  However, there is a demand for further reduction in the amount of resin used in containers and labels, that is, further reduction in wall thickness, from the viewpoint of consideration of the global environment, such as reduction of fossil resource consumption and reduction of carbon dioxide emissions. When the thickness of the body of the container body is reduced to about several hundred microns or less, the rigidity of the container body is low, and the molding shrinkage rate of the container body becomes considerably larger than the shrinkage rate of the label. If sink marks occur so that the body wall near the edge is dented and the container is deformed, the label gets wrinkled, or if the label is not sufficiently adhered, the label may partially peel off and the label may float The problem arises.

  Accordingly, the present invention has an object to effectively suppress the occurrence of sink marks and deformation due to sticking of a label by an in-mold molding method in a blow-molded container, particularly a thin-walled container, and the occurrence of wrinkles and floating in the label. The purpose of the present invention is to provide a blow molded container that is neatly and high-quality packaged at low cost and with little energy without lowering the production efficiency.

The configuration of the present invention for solving the problems of the present invention is as follows.
Molding shrinkage in the height direction, with the average thickness of the barrel by blow molding in the range of 0.1 to 0.6 mm and the molding shrinkage in the radial direction of the barrel in the range of 1.8 to 2.2%. In a thin-walled container with an in-mold label in which a label mainly composed of a synthetic resin film is adhered to the body by an in-mold molding method simultaneously with molding into a container body having a rate in the range of 1.3 to 1.8% .
The MD direction (take-off direction) of the film is the lateral direction of the label, the thermal contraction rate in the horizontal direction of the label is in the range of 1.5 to 3.0%, and the thermal contraction rate in the vertical direction of the label is 1.0. 3.0% range and the fact, in.

  If the container body is thin, if the thermal contraction rate of the label is small relative to the molding shrinkage rate of the container body, sinking or deformation may occur in the container body due to the difference in shrinkage rate, Although floating may occur, the horizontal shrinkage rate of the label in the lateral direction is 1.5 by the above configuration even if the container body is a thin-walled container having an average thickness of 0.1 to 0.6 mm. % Or more, and the thermal contraction rate in the vertical direction of the label is 1.0% or more, it is possible to effectively suppress the sinking and further deformation of the container body and the occurrence of wrinkles and floating in the label.

On the other hand, if the thermal contraction rate of the label in a thin container is larger than the molding shrinkage rate of the container body, the container body may be deformed due to the shrinkage of the label in the region where the label is attached, or the label may be distorted. Although it occurs, such deformation can be effectively suppressed by setting the thermal shrinkage rate in the horizontal and vertical directions of the label to 3.0% or less.
Usually, the thermal shrinkage rate in the MD direction (take-off direction) of the film formed by the extrusion method is larger than that in the TD direction (lateral direction (direction perpendicular to the MD direction)).
In the case of blow molding, in particular, a box-shaped container body has a larger molding shrinkage ratio in the radial direction (circumferential direction) than its height direction. As a whole, the shrinkage difference between the labels can be reduced.

  Here, in general, the surface rigidity in the circumferential direction of the body portion of the container body formed in a bulging shape by blow molding is smaller than the surface rigidity in the body portion height direction. In the direction (longitudinal direction), it is possible to widen the range of allowable shrinkage rate compared to the radial direction (lateral direction).

Another configuration of the present invention is:
The shrinkage difference calculated by [molding shrinkage rate in the radial direction of the container body (%)] − [thermal shrinkage rate in the lateral direction of the label (%)] is in a range of −1.5 to 0.7%,
And,
The difference in shrinkage calculated by [molding shrinkage in the height direction of the container body (%)] − [thermal shrinkage in the vertical direction of the label (%)] is in the range of −1.9 to 1.0%. That's it.

The above configuration is to set the range of the shrinkage rate difference between the container body and the label, in addition to the molding shrinkage rate of the container body,
The difference in shrinkage calculated by [molding shrinkage rate of container body (%)] − [thermal shrinkage rate of label (%)] is within 0.7% in the radial direction of the container body and 1.0% in the height direction. By making it within the range, it is possible to more reliably and effectively suppress the occurrence of sink marks and deformations in the container body due to a large molding shrinkage rate of the container body, and wrinkles and floats in the label. .

On the other hand, if the thermal contraction rate of the label is large compared to the molding shrinkage rate of the container body in a thin container, the molded body deforms as the label shrinks in the area where the label is affixed. Distortion may occur,
The difference in shrinkage calculated by [molding shrinkage rate of container body (%)] − [thermal shrinkage rate of label (%)] is within −1.5% in the radial direction of the container body, and −1 in the height direction. By setting the range within 9%, such deformation can be effectively suppressed.

  Here, generally, the surface rigidity in the circumferential direction of the body portion of the container body formed in a bulging shape by blow molding is smaller than the surface rigidity in the body portion height direction, so the height direction of the container body Then, it is possible to widen the range of allowable shrinkage rate differences compared to the radial direction.

  Another configuration of the present invention is that the total thickness of the label is 20 to 80 microns.

If the total thickness of the label is too thick, the rigidity of the label increases, and sink marks and deformation in the container body tend to occur. Therefore, by making the total thickness of the label 80 μm or less, not only the amount of resin used can be reduced, but also sinking and deformation in the container body can be effectively suppressed.
In addition, in the case of a container with a label attached by an in-mold molding method, a V-shaped notch-shaped groove is formed at the boundary between the label end and the container. In particular, in the case of a thin-walled container, there is a problem that when the container is dropped, there is a problem that the container is easily damaged with the groove as a starting point. However, by making the total thickness of the label 80 μm or less, the groove can be made small, Even in the case of a container, the container is less likely to be damaged due to the groove.

  On the other hand, the total thickness of the label is preferably 20 microns or more from the viewpoint of ease of setting the label in the mold by the in-mold molding method and suppressing the generation of wrinkles.

  Another configuration of the present invention is that the container body is made of a polyolefin resin, and the film mainly constituting the label is a polyolefin film.

  With the above configuration, the container body is made of a polyolefin resin, and the film mainly constituting the label is made of a polyolefin film, that is, the base material of the label is made of a polyolefin film. Although the molding shrinkage rate of the container body is increased, the difference between the molding shrinkage rate of the container body and the thermal shrinkage rate of the label can be reduced by using a polyolefin-based film as the label base material. It is also possible to weld the label directly to the container body regardless of the adhesive.

Here, as the polyolefin resin constituting the container body in the present invention, a polyethylene resin, a polypropylene (hereinafter abbreviated as PP) resin, or a copolymer mainly composed of ethylene or propylene can be used, and these polyolefin resins. Blends based on the system can be used. Further, another resin may be provided as an intermediate layer and may be laminated. For example, a gas barrier resin such as ethylene-vinyl alcohol copolymer may be provided as an intermediate layer.
In addition, as a polyolefin-based film mainly constituting a label, a polyethylene resin, a polypropylene resin, a film made of a copolymer mainly composed of ethylene or propylene and a synthetic paper can be used, a co-extruded film, a laminate film, an unstretched film, Depending on the stretched film, the stretching mode, the heat setting temperature, and the like, the thermal shrinkage rate can be selected within a wide range.

Since the present invention has the above-described configuration, the following effects can be obtained.
That is, in a thin container with an in-mold label, the thermal contraction rate in the horizontal direction of the label is in the range of 1.5 to 3.0%, and the thermal contraction rate in the vertical direction of the label is in the range of 1.0 to 3.0%. By doing so, problems such as sink marks and deformation in the container main body due to the difference in contraction rate between the container main body and the label, and generation of wrinkles and floating in the label can be effectively solved.

  Further, the difference in shrinkage calculated by [molding shrinkage in the radial direction of the container body (%)] − [thermal shrinkage in the lateral direction of the label (%)] is in the range of −1.5 to 0.7%. And a difference in shrinkage calculated by [molding shrinkage in the height direction of the container body (%)] − [thermal shrinkage in the vertical direction of the label (%)] is −1.9 to 1.0%. By setting this range, problems such as sink marks and deformation in the container main body due to the difference in shrinkage rate between the container main body and the label, and generation of wrinkles and floats in the label can be more effectively solved.

  In the invention in which the MD direction of the film constituting the label is the lateral direction of the label, the difference in shrinkage rate between the container body and the label can be reduced as a whole.

  In the invention in which the total thickness of the label is 20 to 80 microns, the amount of resin to be used can be reduced, and sink marks and deformation in the container body can be suppressed. Further, even if the container is thin, the container is less likely to be damaged due to the groove.

  In the invention in which the container body is made of a polyolefin resin and the base material of the label is made of a polyolefin film, the shrinkage difference between the container body and the label can be reduced as a whole. It is also possible to weld the label directly to the container body regardless of the adhesive.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings.
1 to 3 show an embodiment of the container of the present invention. FIG. 1 is a front view, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. It is a longitudinal cross-sectional view which shows the 11 layer structure.
The container body 1 is a casing having an elliptical cylindrical body portion 2 made of high-density polyethylene (HDPE) resin by direct blow molding, having a height of 200 mm and a capacity of 400 ml. The average thickness of the body portion 2 is 0.4 mm.
Further, the molding shrinkage rate of the body portion 2 of the container body 1 is 2.2% in the radial direction and 1.8% in the height direction.

A rectangular label 11 is affixed to the front surface of the body portion 2 simultaneously with the blow molding of the container body 1 by an in-mold molding method.
This label 11 uses a PP resin unstretched film (CPP) as a base material 12,
The substrate 12 (CPP) / gravure printed layer 13 / dry laminate layer 14 / adhesive layer 15 (CPP)) (see FIG. 3).
Here, the adhesive layer 15 made of CPP fulfills the function of adhering (welding) to the surface of the body portion 2 of the container main body 1 by in-mold molding, but has irregularities formed by embossing. The unevenness exerts a function as an air escape path during in-mold molding so that the label 11 does not generate blisters due to air accumulation.
The dry laminate layer 14 functions to bond the base material 12 or the printing layer 13 and the CPP adhesive layer 15 in a dry lamination process.

  The substrate 12 has a layer thickness of 30 microns, the adhesive layer 15 has a layer thickness of 30 microns, and is laminated with the dry laminate layer 14 with the MD direction being the take-up direction aligned. The thickness of the entire label is 65 microns. The heat shrinkage rate in the MD direction of the entire label 11 is 2.0%, and the heat shrinkage rate in the TD direction, which is a direction perpendicular to the MD direction, is 1.4%. 1 is attached to the body 2 of the body. The thermal contraction rate in the horizontal direction of the label is 2.0%, which is included in the range of 1.5 to 3.0%. Moreover, the thermal contraction rate in the vertical direction of the label is 1.4%, which is included in the range of 1.0 to 3.0%.

Here, the shrinkage rate difference between the container body 1 and the label 11 is calculated as follows.
That is, the difference in shrinkage calculated by [molding shrinkage in the radial direction of the container body (%)] − [thermal shrinkage in the horizontal direction of the label (%)] is 2.2% −2.0%, which is 0. 2%, which is included in the range of -1.5 to 0.7%.
The difference in shrinkage calculated by [molding shrinkage in the height direction of the container body (%)] − [thermal shrinkage in the vertical direction of the label (%)] is 0 to 1.8% −1.4%. .4%, which is included in the range of -1.9 to 1.0%.

Here, FIG. 5 is a schematic explanatory diagram of a process of forming the thin container with an in-mold label according to the present embodiment. A cylindrical HDPE resin parison 22 is extruded from a die 21, and the upper and lower sides thereof are sandwiched by a blow molding split mold 23.
When blow air is blown in this state, the parison 22 expands (see the arrow direction in FIG. 6) and is shaped into the shape of the cavity (see the state of the two-dot chain line in FIG. 6), and the container body 1 is molded. At the same time as the molding, the label 11 previously disposed on the mold surface is attached in a state of being integrated with the body wall 2W.

FIG. 2 shows a plane cross section of the body portion 2 of the container body 1 formed in this way. The label 11 is neatly adhered to the front surface of the container main body 1 on the same plane as the surface of the body wall 2W over almost a half circumference without any wrinkles or floating.
Further, the occurrence of sink marks in which the body wall 2W in the vicinity of the peripheral edge of the label 11 is indented is sufficiently suppressed to such an extent that it cannot be detected by appearance.
In addition, due to the combined effect of embossing of the CPP which is the adhesive layer 15, the label 11 is in a smooth and high-quality state without blisters.

  Here, a drop test (temperature: 5 ° C., drop height: 1 m, number of drops: 2 times) with the label 11 face down was performed for damage caused by the edge 11e at the peripheral edge of the label 11. There was no damage to the container.

[Comparative example]
As a comparative example with respect to the above example, in the above example, a container was formed by changing only the point where the TD direction of the label 11 was changed to the horizontal direction.
Thus, the thermal contraction rate in the horizontal direction of the label 11 with the TD direction set in the horizontal direction is 1.4%, which is out of the range of 1.5 to 3.0%. Moreover, the thermal contraction rate of the vertical direction of the label 11 is 2.0%, and is included in the range of 1.0 to 3.0%.
Moreover, it becomes as follows which calculates the shrinkage | contraction rate difference of the container main body 1 and the label 11 at the time of sticking the label 11 by making the TD direction into a horizontal direction in this way.
That is, the difference in shrinkage calculated by [molding shrinkage rate in the radial direction of the container body (%)] − [thermal shrinkage rate in the lateral direction of the label (%)] is 2.2% −1.4% and is 0. 8%, which is out of the range of -1.5 to 0.7%.
Further, the difference in shrinkage calculated by [molding shrinkage in the height direction of the container body (%)] − [thermal shrinkage in the vertical direction of the label (%)] is 1.8% −2.0% − It is 0.2%, and is included in the range of -1.9 to 1.0%.

  That is, in this comparative example, the thermal contraction rate in the lateral direction of the label 11 with respect to the molding shrinkage rate in the radial direction of the container body 1 is small. In particular, the body portion 2 of the container body 1 is formed in a bulging shape in the radial direction. Therefore, the label 11 is partly peeled off and is lifted in the vertical direction, which deteriorates the appearance.

  Here, FIG. 4 shows an example of a flat cross-sectional shape of the body portion 2 of the comparative example, and due to shrinkage in the circumferential direction of the body wall 2W, as shown in FIG. The arc-shaped body wall 2W is deformed inwardly to form a so-called sink, and the body part protrudes from a normal state, and the entire container is deformed.

  Next, two containers 11 and several kinds of labels 11 having different heat shrinkage rates are combined to form a thin container with an in-mold label by an in-mold molding method. Described below are the experiments that examined the occurrence of deformation, wrinkles in the label, and the occurrence of floating, and the results.

[Experiment 1]
(1) Container body: A housing having an elliptical cylindrical body 2 made of HDPE resin by direct blow molding, having a height of 200 mm, a capacity of 400 ml, and an average thickness of the body 2 of 0.4 mm is there. The molding shrinkage rate of the body part 2 is 2.2% in the radial direction and 1.8% in the height direction. (This is the same as the embodiment described above.)
(2) Labels: A total of six types of labels having three heat shrinkage rates each made of CPP and OPP were used.
Table 1 shows the results of sticking to the container body 1 with the MD direction of the base material set in the horizontal direction of the label 11 and Table 2 with the TD direction set in the horizontal direction of the label 11.
(3) The thermal contraction rate of the label 11 is measured at 120 ° C. for 10 minutes.
(4) In the external appearance evaluation in Tables 1 and 2 (the same applies to Tables 3 and 4 to be described later), those that can be used as products were marked with ◯, and those that could not be used were marked with ×.
(5) Test No. in Table 1 1-4 is a test No. in the above-mentioned Examples and Table 2. 2-4 corresponds to the comparative example described above.

[Experiment 2]
(1) Container body: A casing having a cylindrical body part 2 made of polypropylene (PP) resin by direct blow molding, having a height of 150 mm, a capacity of 200 ml, and an average wall thickness of 0. 5 mm.
Further, the molding shrinkage rate of the body portion 2 of the container body 1 is 1.8% in the radial direction and 1.3% in the height direction.
(2) Labels: A total of six types of labels having three heat shrinkage rates each made of CPP and OPP were used.
Table 3 shows the results of sticking to the container body 1 with the MD direction of the base material set in the horizontal direction of the label 11 and Table 4 with the TD direction set in the horizontal direction of the label 11.
(3) The thermal contraction rate of the label 11 is measured at 120 ° C. for 10 minutes.

As can be seen from the results of Tables 1 to 4, the horizontal heat shrinkage rate of the label 11 is in the range of 1.5 to 3.0%, and the heat shrinkage rate of the label in the vertical direction is 1.0 to 3%. By setting the content within the range of 0.0%, the container body 1 can be deformed, and the thin container with an in-mold label can be obtained without any distortion in the label 11. In particular, when the container body is made of polyolefin, the material constituting the label is selected in advance so that the thermal contraction rate of the label is in the above range, thereby preventing deformation of the container body 1 and distortion of the label 11. Can do.
In addition, by making the difference in thermal shrinkage between the container body 1 and the label 11 in the range of -1.5 to 0.7% in the radial direction and in the range of -1.9 to 1.0% in the height direction, It can be set as the thin container with an in-mold label without the deformation | transformation of the container main body 1, or the label 11 being distorted.

As mentioned above, although the structure of this invention and its effect were demonstrated along the Example, this invention is not limited to this Example.
The combination of the material used for the container main body 1 and the label 11 can be various combinations within a range that satisfies the requirements related to the difference in shrinkage rate. For example, in the above embodiment, the container body 1 is made of HDPE resin. However, other polyolefin resins such as PP resin, polyester resins, polystyrene resins, and the like conventionally used for blow molding are used. Can be used.

In addition to the PP resin film, for example, a film such as a polyester film can be used as the base material of the label 11, and the container body is selected from a non-stretched film or a stretched film having various stretch ratios. The shrinkage rate difference from 1 can be adjusted.
Moreover, although the embossed CPP film which heat-seal | fuses with a label was used as an adhesive layer of a label, you may provide heat-sealable resin instead.

  As described above, the thin-walled container with an in-mold label of the present invention is caused by the shrinkage rate difference between the container body and the label, and is prominent in the thin-walled container. Generation is effectively suppressed, and development in various applications is expected as a thin-walled container with excellent appearance.

It is a front view which shows one Example of the container of this invention. It is a plane sectional view shown along the AA line in FIG. It is a longitudinal cross-sectional view which shows the layer structure of the label used for the container of FIG. It is explanatory drawing which shows an example of the deformation | transformation state of a container main body in case the shaping | molding shrinkage ratio of the radial direction of a container main body is large in a plane cross section. It is a schematic explanatory drawing which shows one Embodiment of the process for shape | molding the container of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Container body 2; Body part 2w; Body wall 11; Label 11e; Edge part 12; Substrate 13; Print layer 14; Dry laminate layer 15; Adhesive layer 21; Air intake path

Claims (4)

The average thickness of the body (2) by blow molding is in the range of 0.1 to 0.6 mm , and the molding shrinkage ratio in the radial direction of the body (2) is in the range of 1.8 to 2.2%. The label (11) mainly composed of a synthetic resin film is formed on the container body (1) having a molding shrinkage in the height direction in the range of 1.3 to 1.8% simultaneously with molding by an in-mold molding method. In the thin container with an in-mold label attached to the body (2),
The MD direction (take-off direction) of the film is the lateral direction of the label (11), and the thermal contraction rate in the lateral direction of the label is in the range of 1.5 to 3.0%. A thin-walled container with an in-mold label, wherein the shrinkage ratio is in the range of 1.0 to 3.0%.   The shrinkage difference calculated by [molding shrinkage rate (%) in the radial direction of the container body] − [thermal shrinkage rate (%) in the lateral direction of the label] is in the range of −1.5 to 0.7%, and The difference in shrinkage calculated by [molding shrinkage in the height direction of the container body (%)] − [thermal shrinkage in the vertical direction of the label (%)] is in the range of −1.9 to 1.0%. The thin-walled container with an in-mold label according to claim 1. The thin-walled container with an in-mold label according to claim 1 or 2 , wherein the total thickness of the label is 20 to 80 microns. The thin-walled container with an in-mold label according to claim 1 or 2, wherein the container body (1) is made of a polyolefin resin, and the film mainly constituting the label (11) is a polyolefin film.

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