JP5700335B2 - 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 attached to the peripheral wall of the trunk of the container body The method of sticking to is used.
For example, Patent Document 1 describes a thin plastic bottle in which a label is attached and integrated on a peripheral wall of a body portion. However, the method described in Patent Document 1 requires a step of supplying the container main body and the label into a mold prepared for sticking the label after blow molding of the thin-walled container. There was a problem of being inferior.

  On the other hand, as one method of sticking this label, when the container body is blow-molded, an in-mold label (hereinafter sometimes simply referred to as a label) is set in advance on the mold surface and molded. There is a so-called in-mold molding method in which this label is attached at the same time.

According to this in-mold molding method, label sticking to the container main body is achieved simultaneously with the molding of the container main body, and no special separate step of sticking work is required, between the surface of the container main body and the label. Since there is no step, there is no risk of deterioration of the appearance and feel of the container due to this step, and it is possible to reliably obtain a strong and stable sticking of the label to the container body regardless of the thinning of the container body. The excellent action of being able to be performed is exhibited.

JP 2002-321722 A

  However, from the viewpoint of consideration of the global environment, such as reduction of fossil resource consumption, prevention of global warming by reducing carbon dioxide emissions, or cost reduction, further reduction of the amount of resin used in the container body, that is, further While thinning is required, it is required to reduce the thickness of the body of the container body to about several hundred micrometers.

On the other hand, if the thickness of the container body is reduced and the label is attached by the in-mold molding method, if the label rigidity or the label thickness is large, the label attachment area is the body part compared to the other areas. There is a problem that the contraction of the peripheral wall is suppressed and the peripheral wall is deformed.
FIG. 4 shows a typical example of this type of deformation seen in the plan view of the oval cylindrical body. In the region where the label 11 is attached, the shrinkage of the peripheral wall 2w is suppressed. The peripheral wall 2w is dented in the vicinity of the end portion 11e of the eleventh portion, and so-called sink marks are generated.

  In addition, in the method of attaching a label by the in-mold molding method, in addition to the above-described deformation, cracks starting from a notch-shaped groove formed at the end of the label, and air accumulation between the label and the peripheral wall Problems, and further problems related to curling of labels, and it is necessary to design the layer structure of the label while comprehensively considering these points.

The present invention creates a design index of a layer structure for effectively suppressing deformation of a container due to sticking of a label by an in-mold molding method to a thin-walled container made of synthetic resin by blow molding, and based on this index. Furthermore, it is an object to comprehensively solve the problems of deformation of the container, the problem of cracking starting from the end of the label, the problem of air accumulation, and the problem of curling of the label.

The main configuration of the present invention related to the means for solving the above problems is as follows.
In a thin-walled container in which an in-mold label is attached at the same time as blow molding on the peripheral wall of the body of the synthetic resin container body,
The average wall thickness of the peripheral wall of the body of the container body is 0.8 mm or less,
The in-mold label has a layer structure in which an adhesive layer that adheres to the peripheral wall of the body portion is laminated inside the base film layer, and has a thickness of 0.08 mm or less.
[Tensile elastic modulus of the label (MPa)] × [Label thickness (mm)] The A value calculated by ³ is 0.12 or less ,
The adhesive layer was laminated with a synthetic resin of the same system as the container body to a layer thickness in the range of 0.005 to 0.025 mm by an extrusion lamination method, and then unevenness was formed by embossing.
It is said.

Regarding the labels used for containers with in-mold labels, in consideration of the elements and problems described in the following 1) to 7), the structure of the label such as the laminated structure, the material of each layer, the layer thickness, etc. It is necessary to select a manufacturing method.
1) Productivity of label manufacturing process or processing process 2) Curling of label 3) In in-mold molding, labels are aligned in a predetermined holder, and are continuously and reliably fed into the mold one by one. Productivity related to the process 4) Generation of wrinkles on the label due to the parison made of high-temperature molten resin coming into contact with the label while expanding and deforming, and generation of air accumulation 5) Cooling and solidification and molding of the resin in the mold Deformation of container due to subsequent shrinkage 6) Adhesiveness of label to container surface 7) Container due to drop impact caused by V-shaped notch groove formed at boundary between label end and container body Cracking

In particular, in the case of a thin-walled container having an average thickness of the peripheral wall of the body portion of the container body of 0.8 mm or less, the problem of wrinkles and air accumulation described in 4) and the problem of deformation of the container described in 5) are remarkable. Since it appears, it is necessary to design the layer structure of the label from a viewpoint different from the case where the wall thickness of the peripheral wall is large.
For example, considering the suppression of wrinkles and air accumulation in the label during molding, increasing the elastic modulus of the label or the thickness of the label, on the other hand, the deformation of the container due to the sticking of the label is large Therefore, it is necessary to appropriately select the label configuration in consideration of the above-described elements and problems 1) to 7) as a whole.

In the main configuration of the present invention, the value A of the label includes the elastic modulus and thickness of the label, that is, a value that serves as an index of the rigidity or waist strength of the label. ) Related to the deformation of the container.
The inventors have improved the deformation of the peripheral wall of the barrel due to the in-mold molding method for thin containers with an average thickness of the peripheral wall of the barrel of 0.8 mm or less. While considering this A value as an index for the labels it has, by setting this A value to a value of 0.12 or less, it is possible to effectively suppress and prevent deformation of the container due to sticking of this type of label. We have found that it is possible to create the main configuration described above.
In other words, the A value of the label used in the main configuration is used as an index, and the A value is set to a value of 0.12 or less, thereby effectively suppressing the deformation of the peripheral wall as described above due to label sticking. It becomes possible to do.

On the other hand, the upper limit of the thickness of the label is related to the occurrence of cracks due to the notch-shaped groove of 7).
When a label is pasted by the in-mold molding method, a V-shaped notch-shaped groove is formed at the boundary between the end of the label and the peripheral wall. If the label is too thick, this groove becomes deeper and larger. In the case of thin-walled containers, there is a problem that the container breaks from this groove due to drop impact,
As in the above configuration, by making the label thickness 0.08 mm or less, the groove can be made small, and even in a thin container, it is possible to prevent the container from being cracked due to the notch-shaped groove. .

If the A value is too small, the productivity of the label manufacturing process or processing process described in 1), the label curling problem of 2), and the productivity in the label supplying process of 3) are described. Therefore, it is preferable to secure a certain waist strength by setting the A value to 0.02 or more.
At the same time, the label thickness is preferably set to 0.03 mm or more because the thickness of the label is too small to cause the same problem.

In the above SL principal configuration of the present invention, which an adhesive layer is laminated synthetic resin of the container body and the same type in a layer thickness in the range of 0.005~0.025mm the extrusion lamination method, followed by forming a concave-convex by embossing It is said that.

The above configuration has the above-mentioned 1) label production process or processing process productivity problem, 2) label curl problem, 3) productivity problem related to label supply, and 4) air. This is related to the problem of accumulation and 6) strong adhesiveness.
In the case of the extrusion laminating method, the curling of the label can be easily prevented by controlling the thickness of the extruded resin and the tension of the base film layer, and the decrease in productivity related to the supply of the label due to the occurrence of curling is prevented. can do.
In the case of the extrusion laminating method, the thickness of the adhesive layer can be set to about 0.01 to 0.02 mm, and the depth of embossing by embossing can be sufficiently ensured.

In addition, in the extrusion laminating method, if the layer thickness of the adhesive layer, which is an extruded resin, is too large, curling occurs on the label due to the shrinkage of the extruded resin after cooling, so the thickness of the adhesive layer is 0.025 mm. The following range is preferable.
On the other hand, if the layer thickness of the adhesive layer is too small, the depth of the unevenness due to embossing is insufficient, and wrinkles and air accumulation easily occur on the label. Therefore, the layer thickness of the adhesive layer is 0.005 mm or more. It is preferable to do this.

  In addition, since the adhesive layer is made of the same type of synthetic resin as the container body in the above configuration, the surface of the adhesive layer is melted by the heat of the parison, and the label is welded to the container body surface. Even when used in harsh environments such as high humidity, or when the container is squeezed or crushed to take out the contents, the label does not peel off.

Here, as a method for laminating the adhesive layer, in addition to the extrusion laminating method of the above configuration, a method of laminating an adhesive film on the base film layer by a dry laminating method, a method of applying a thermosensitive adhesive to the base film layer There is.
When laminating an adhesive film to be an adhesive layer on a base film layer by the dry laminating method, if the adhesive film does not have a certain thickness (the minimum thickness is approximately 0.03 mm), the tension at the time of dry laminating The adhesive film stretches or wrinkles enter.
For this reason, if the A value is kept in the range below the upper limit value so that the container is not deformed, it is necessary to reduce the thickness of the base film layer by the thickness of the adhesive film. Curling occurs due to tension on the base film layer.
For this reason, in a label in which the adhesive layer is laminated by the dry laminating method, it is difficult to prevent both the deformation of the container and the curling of the label due to the sticking of the label due to restrictions derived from the label manufacturing method. Yeah.
Moreover, since the adhesive layer cannot be thickened according to the method of applying the heat-sensitive adhesive, the emboss depth cannot be sufficiently increased.

  Still another configuration of the present invention is that the container body is made of polyethylene resin, the label is an extrusion lamination method in which a base film layer made of polypropylene resin unstretched film (CPP) is bonded to an adhesive layer made of low density polyethylene (LDPE) resin It is said that it is set as the structure laminated | stacked by.

The said structure concerns on the specific structure of the thin container with a label of this invention.
By using the same type of resin as the container body for the adhesive layer, the label can be firmly bonded and fixed together with the effects of the in-mold molding method.
Also, since CPP has a relatively low elastic modulus because it is an unstretched film, and has a lower tensile elastic modulus and isotropic than a stretched film, the A value can be relatively easily kept within the upper limit. Can do.

Since the labeled thin-walled container of the present invention has the above-described configuration, the following effects are exhibited.
In the case of the main structure, even if the container main body is 0.8 mm or less, the label calculated by [label tensile elastic modulus (Mpa)] × [label thickness (mm)] ³ By making the value of A corresponding to the index of waist strength of 0.12 or less, deformation of the container due to label sticking can be effectively suppressed, and the thickness of the label is reduced to 0. .08 mm or less can effectively prevent cracking due to the drop impact of the container due to the notch-shaped groove formed on the end face of the label,
While taking advantage of the characteristics of the in-mold molding method, it is possible to provide a thin-label container with a good appearance that adheres firmly to the surface of the container body and does not deform the container.

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 sectional drawing which shows the layer structure of the label used for the container of FIG. It is a schematic explanatory drawing which shows an example of the deformation | transformation aspect of a container in a plane cross section. It is a schematic explanatory drawing of the process for shape | molding the container of this invention. It is the table | surface which put together the laminated constitution of the various labels used for the container of an Example and a comparative example. It is the table | surface which put together the evaluation results, such as a physical property of a label in FIG. 6, and a sticking state.

Embodiments of a labeled container according to the present invention will be described below 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 sectional drawing which shows the layer structure of 11. FIG.
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 0.45 mm.

A rectangular label 11 is attached to the front and back of the body portion 2 simultaneously with the blow molding of the container body 1 by an in-mold molding method.
This label 11 has a layer structure of base film layer 12 / gravure printed layer 13 / anchor coat (AC) layer 14 / adhesive layer 15 (see FIG. 3).
The base film layer 12 is made of PP resin unstretched film (CPP) and has a layer thickness of 0.04 mm, and the adhesive layer 15 is obtained by laminating low density polyethylene (LDPE) resin by an extrusion laminating method before embossing described later. And the average thickness of the entire label 11 is 0.058 mm.
In the label 11 in which the adhesive layer 15 is embossed, the dimension indicated by t in FIG. 3 is the thickness of the label 11.

Here, FIG. 5 is a schematic explanatory diagram of the steps of the in-mold molding method for molding 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 blown air is blown in this state, the parison 22 expands (see the arrow direction in FIG. 5) and is shaped into the shape of the cavity (see the state of the two-dot chain line in FIG. 5), and the container body 1 is molded. At the same time as the molding, the label 11 fixed and arranged in advance on the mold surface by the reduced pressure intake passage 24 is adhered to the peripheral wall 2w of the trunk portion.

  The adhesive layer 15 of the label 11 has a function of adhering (welding) to the surface of the peripheral wall 2w of the barrel 2 of the container body 1 by an in-mold molding method. Concavities and convexities are formed on the layer 15 by embossing.

And this unevenness | corrugation exhibits the function as an escape route of the air at the time of in-mold shaping | molding, and the label 11 does not generate | occur | produce the float (blister) resulting from an air pool.
Further, the unevenness can alleviate the shrinkage behavior of the label due to the contact of the high temperature parison, which is the main cause of wrinkles, and can effectively suppress wrinkles.
Furthermore, in order to reduce the contact area between the label surface and the label back surface, where the irregularities overlap and align in the holder, the labels are removed from the holder securely one by one in the automatic feeding of the label, Can be supplied into the mold.

  And this label 11 corona-treats one surface of the base film layer 12, forms the printing layer 13 by gravure printing, and also adheres adhesives such as organic titanate, organic isocyanate, and polyethyleneimine. The adhesive layer 15 is laminated by an extrusion laminating method through an AC layer as a main component, embossed on the adhesive layer 15 as described above, and then punched out by a bush method in a predetermined shape.

  Next, in order to compare with the labeled container of the above example, five types of labels having a layer configuration different from the label used in the above example (hereinafter referred to as label L) were prepared and used in the example. These five kinds of labels (hereinafter referred to as labels Lc1 to Lc5) are attached to the same container body as the HDPE resin container body 1 by the same in-mold molding method, and the labels of Comparative Examples 1 to 5 are used. An attached container was prepared.

FIG. 6 is a table summarizing the layer structure of the label L and the labels Lc1 to Lc5. In this table, the abbreviations used in the description of the layer structure of the label are as follows.
-CPP: PP resin unstretched film-OPP: PP resin biaxially stretched film-Co-PP: Copolymerized polypropylene resin unstretched film-Extruded LDPE; Low-density polyethylene resin layer laminated by extrusion lamination method-AC; Anchor coat layer / DL; dry laminate layer In the table of FIG. 6, the values in parentheses are the layer thicknesses in micrometer units.
The synthetic paper used for the label Lc1 is YUPO IDS80 manufactured by YUPO Corporation.

Moreover, FIG. 7 shows the physical properties of the label L, the labels Lc1 to Lc5, the presence or absence of curl, and the container after the label is attached to the container body, for the containers with labels of Examples and Comparative Examples 1 to 5. It is the table | surface which showed collectively the result of the deformation | transformation, the presence or absence of an air reservoir, and the drop impact test.
In this table, the tensile elastic modulus of the label is a value measured by punching each label in the dumbbell shape of ASTM-1822L in the longitudinal direction and the transverse direction, and conducting a tensile test at a tensile speed of 1 mm / min.
Here, the vertical direction of the label corresponds to the axial direction of the container body 11 when the label is attached to the container body 11, and the horizontal direction corresponds to a direction perpendicular thereto. Accordingly, the A value is also calculated in the vertical and horizontal directions.
Moreover, the test method of the drop impact test is that the container is filled with a specified amount of water, left in a thermostatic chamber adjusted to 5 ° C. for 24 hours, then taken out and immediately taken upright from 1 m in height and lying down. Drop in order. This is one cycle, dropped 10 cycles, and if there is no damage to the container, no abnormality is assumed.

  Next, with respect to the examples described in the table of FIG. 7 and Comparative Examples 1 to 5, along with the data, the A value is 0.12 or less, corresponding to the design criteria of the layer configuration defined in the present invention, This will be described below in comparison with the requirement that the thickness of the label is 0.08 mm or less and the thickness of the adhesive layer is in the range of 0.005 to 0.025 mm.

(1) Container of Example The layer structure of the label L is as described above, the thickness of the label L is 0.058 mm, the A value is 0.044 in the vertical direction, 0.027 in the horizontal direction, and LDPE resin is extrusion laminated. The thickness of the adhesive layer 15 laminated by the method before embossing is 0.01 mm.
And in this label L, there is no generation | occurrence | production of curl, A value exists in the range of 0.12 or less, and the trunk | drum 2 of the container main body 1 resulting from sticking of a label is shown in the plane sectional view of FIG. There was no deformation of the peripheral wall 2w.
Further, the thickness of the adhesive layer 15 before embossing is 0.01 mm, the depth of the unevenness by the embossing can be sufficiently taken, there is no occurrence of air accumulation, and the adhesive layer 15 is of the same type as the container body 1. Strong adhesiveness is achieved by being made of a synthetic resin and combined with the effects of the in-mold molding method.
The thickness of the label L is 0.058 mm and a value of 0.08 mm or less, and a V-shaped notch-shaped groove formed at the boundary between the label end 11e (see FIG. 2) and the peripheral wall 2w. The container was not cracked by a drop impact caused by the groove.

(2) Container of Comparative Example 1 In Comparative Example 1, a synthetic paper is used as a base film, and a heat-sensitive adhesive resin is provided as an adhesive layer, and this adhesive layer is an embossed label Lc1. This is a so-called model example in which both the tensile modulus and thickness are large and the A value exceeds 0.12 and is 0.543 in the longitudinal direction. Deformation as shown occurred, and in the drop impact test, the container cracked due to the V-notch groove.
This type of label can be used when the thickness of the container body is sufficiently large, but it cannot be used in a thin-walled container such as the present invention.

(3) Container of Comparative Example 2 The layer structure of the label Lc2 used in Comparative Example 2 is substantially the same as that of the label L used in Examples, the layer thickness of the base film layer 12 is 0.02 mm, and the adhesive layer 15 This is an example in which the layer thickness is increased by 0.01 mm, and the adhesive layer 15 is not embossed.
Since the layer thickness was increased, the A value exceeded 0.12 to about 0.2, and the container was deformed as shown in the plan sectional view of FIG.
Further, the thickness of the label exceeded 0.08 mm, and in the drop impact test, the container was damaged due to the V notch.
In addition, air stagnation occurs when there is no unevenness due to embossing.

(4) Container of Comparative Example 3 The layer structure of the label Lc3 used in Comparative Example 3 is substantially the same as that of the label L used in Examples, but the base film is a biaxially stretched film (OPP) made of PP resin. In this example, the thickness is 0.04 mm and the thickness of the adhesive layer 15 is 0.01 mm to 0.02 mm.
By changing the material of the base film, the thickness of the label Lc3 is not greatly changed compared to the label L, but the tensile modulus is increased to about 4 times, and as a result, the A value is increased accordingly. Increased to about 0.2, and deformation as shown in the plan sectional view of FIG. 4 occurred.

(5) Container of Comparative Example 4 The layer structure of the label Lc4 used in Comparative Example 4 is substantially the same as the label L used in the Examples, and the layer thickness of the base film layer 12 is 0.05 mm to 0.06 mm. This is an enlarged example.
By changing the layer thickness, the label thickness and tensile elastic modulus of the label Lc4 become slightly larger than the label L, and as a result, the A value slightly exceeds 0.12 but becomes about 0.13. Also in this case, the deformation as shown in the plan sectional view of FIG. 4 was observed.

(6) Container of Comparative Example 5 The layer structure of the label Lc5 used in Comparative Example 5 is a Co-PP adhesive film embossed on the CPP base film layer 12 by the dry lamination method. This is an example in which the adhesive layer 15 is laminated.
When laminating the adhesive film to be the adhesive layer 15 on the base film layer 12 by the dry laminating method, the dry film must have a certain thickness (the minimum thickness is approximately 0.03 mm). The tension of the adhesive film stretches or wrinkles.
For this reason, when trying to make a layer structure in which the A value falls within the range of 0.12 or less and there is no deformation of the container as in the label Lc5, the layer thickness of the base film layer 12 is increased because the adhesive film is thicker. It is necessary to reduce the thickness (in this example, 0.03 mm), and the resulting label is curled due to the tension applied to the base film layer 12 during dry lamination.
When curling occurs in the label, the label cannot be placed in the hopper in an aligned state, and the label cannot be automatically supplied to the mold by the apparatus.
As can be seen from Comparative Example 5, in the label in which the adhesive layer 15 is laminated by the dry laminating method, both the deformation of the container and the curling of the label due to the sticking of the label are prevented from the restrictions derived from the label manufacturing method. Can be said to be difficult.

As mentioned above, although the evaluation result which concerns on the thin container with a label of an Example and Comparative Examples 1-5 was demonstrated, many labels which changed layer composition and layer thickness including these Examples and Comparative Examples 1-5 were used. From the evaluation results, it can be summarized as follows.
(1) The presence or absence of deformation of the container due to the sticking of the label can be predicted by the A value corresponding to the index of the waist strength of the label, and the deformation can be effectively performed by reducing the A value to 0.12 or less. Can be prevented.
(2) As described above, the extrusion lamination method is suitable for laminating the base film layer and the adhesive layer in order to prevent deformation of the container by setting the A value to 0.12 or less and to prevent curling of the label.
(3) By setting the thickness of the label to 0.8 mm or less, it is possible to prevent damage due to drop impact caused by the V notch formed at the end of the label.

As described above, the embodiment of the present invention and the operation and effect thereof have been described along the examples and with reference to the comparative examples. However, the present invention is not limited to the examples.
The combination of the materials used for the container body 1 and the label 11 can be various combinations.
For example, in the above embodiment, the container body 1 is made of HDPE resin, but other polyolefin resins such as PP resin, and resins conventionally used for blow molding, such as polyester resins, can be used. .

In addition, the layer structure of the label 11 can be variously configured within the category that the A value and the thickness of the label fall within a predetermined range. In the above embodiment, a CPP film is used as the base film layer 12, but other polyolefin resin films or polyester resin films can be used, for example. It can be appropriately selected in consideration of adhesiveness with the main body.

As described above, the thin-walled container with an in-mold label according to the present invention has no deformation of the container due to label sticking, no air accumulation, and cracking due to a drop impact starting from the label end face is suppressed. It is expected that it will be used in various applications as a thin-walled container with a high quality exterior with an in-mold label.

DESCRIPTION OF SYMBOLS 1; Container body 2; Body 2w; Body wall 11; Label 11e; End 12 (of label); Base film layer 13; Print layer 14; Anchor coat layer 15; Adhesive layer 21; Blow split mold 24; decompression intake passage

Claims (2)

A thin-walled container in which an in-mold label (11) is attached to the peripheral wall (2w) of the body (2) of the container body (1) made of synthetic resin simultaneously with blow molding,
The average wall thickness of the peripheral wall (2w) of the container body (1) is 0.8 mm or less,
The in-mold label (11) has a layer configuration in which an adhesive layer (15) that adheres to the peripheral wall (2w) is laminated on the inner side of the base film layer (12), and has a thickness of 0.08 mm or less. ,
[Tensile elastic modulus of the label (MPa)] × [Label thickness (mm)] The A value calculated by ³ is 0.12 or less ,
The adhesive layer (15) was formed by laminating a synthetic resin of the same system as the container main body (1) to a layer thickness in the range of 0.005 to 0.025 mm by an extrusion laminating method, and then forming irregularities by embossing. > A thin-walled container with an in-mold label. The container body (1) is made of polyethylene resin, and the label (11) is laminated on the base film layer (12) made of polypropylene resin unstretched film by the extrusion laminating method with the adhesive layer (15) made of low density polyethylene resin. configuration and claims 1 Symbol placement in-mold labeled thin container.

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