JP5168554B2 - 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, the method described in Patent Document 1 requires a process of supplying the label and the container into a mold prepared for applying the label after blow molding of the thin-walled container, resulting in poor production efficiency and energy efficiency. There was a problem.

  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, further reduction in the amount of resin used in the container body and label, that is, further thinning, is required from the viewpoint of consideration of the global environment, such as reduction of fossil resource consumption and reduction of carbon dioxide emissions. In particular, it is required to reduce the thickness of the body of the container body to several hundred microns or less.

On the other hand, if the container body is thinned, when the container body is molded by blow molding, the label shrinks due to the heat of the parison when the label is pasted by the in-mold molding method. Since the air between the label and the label cannot escape, floating may occur between the container body and the label.
Also, if the label is thick, the label slows down the cooling of the parison by the mold, so the surface of the container body where the label is affixed is larger than the molding shrinkage of the container body in other parts. Therefore, there is a problem that the container body is deformed due to its thin wall, and that the container body is also deformed when the elastic modulus of the label is large or the difference between the elastic modulus of the container body and the label is large. Occur.

Accordingly, the present invention has an object to effectively suppress the occurrence of 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 floats on the label. In addition, an object is to provide a blow molded container with a high quality exterior at low cost and with little energy without lowering the production efficiency.

The main configuration according to the means of the present invention for solving the above problems is as follows.
A synthetic resin base film layer and an adhesive layer are formed on a synthetic resin container body with an average wall thickness of 0.1 to 0.8 mm by a blow molding method by an in-mold molding method at the same time as molding. In a container in which a label laminated with is attached to the body part, the following constitutional requirements are satisfied.
However, the “label thickness” in the present application refers to the average thickness t from the surface of the base film to the top of the convex portion of the embossment of the adhesive layer in the cross section of the label as shown in FIG. This is the total thickness of the film that will be the dry laminate layer and the adhesive layer before embossing.
(1) The adhesive layer is made of a synthetic resin film of the same system as the surface of the container body, and further embossed.
(2) The label thickness is in the range of 30 to 80 microns.
(3) The elastic modulus of the label is in the range of 200 to 1000 MPa.
(4) The difference in elastic modulus calculated by [elastic modulus of container body] − [elastic modulus of label] is set to a range of −500 MPa or more.
(5) The label has a configuration in which a printed layer is formed on one surface of a base film layer having transparency, and an adhesive layer is laminated on the printed layer.

When a label is affixed to the container body in-mold, it is necessary to select the label material and thickness mainly in consideration of the following factors 1) to 4).
1) Productivity related to continuous supply of labels into the mold cavity 2) Due to generation of wrinkles on the label due to a parison made of high-temperature molten resin coming into contact with the label while expanding and deforming, or due to air accumulation Occurrence of float 3) Cooling and solidification of resin in the mold and deformation of the container due to shrinkage after molding 4) Strong adhesion of the label to the container surface Especially the average thickness of the body of the container body is 0 In the case of a thin container of about 1 to 0.8 mm, the problem of wrinkles and air accumulation generated in the label during the molding shown in 2), and the problem of container deformation caused by molding shrinkage shown in 3) To appear.

For this reason, for example, if the elastic modulus of the label is increased or the label is thickened only in consideration of suppressing the generation of wrinkles on the label during molding, the deformation of the container due to molding shrinkage increases. Therefore, it is necessary to select the material and thickness of the label in consideration of the above factors and problems 1) to 4) as a whole.

Therefore, the structural requirements (1) to (4) shown in the main configuration of the present invention are based on overall consideration of the elements and problems of 1) to 4) when sticking the label with the in-mold described above. Yes, by selecting the label material and thickness according to the requirements (1) to (4)
While ensuring productivity related to continuous supply of labels into the mold cavity, generation of wrinkles on the label during molding and occurrence of floating due to air accumulation can be sufficiently suppressed, and molding shrinkage can also be achieved. The resulting deformation of the container can be effectively suppressed, and the label can be firmly and integrally bonded to the body wall of the container main body with high productivity without sacrificing the characteristics of in-mold molding. On the other hand, it is possible to provide a thin container with a label having a good appearance with no wrinkles or floats on the label and no deformation of the container.

That is, in the component (1), if the adhesive layer is embossed, the unevenness formed by this embossing causes the shrinkage behavior of the label due to the contact of the high temperature parison, which is the main cause of wrinkles. It can be mitigated and the generation of wrinkles can be effectively suppressed.
Moreover, since the generation of wrinkles can be effectively suppressed by the unevenness due to the embossing as described above, it is not necessary to increase the thickness and elastic modulus of the label beyond a certain size in order to suppress the generation of wrinkles. As will be described later, it becomes possible to suppress the deformation of the container due to molding shrinkage due to the large thickness and elastic modulus of the label.

In addition, since the contact area between the labels superimposed by embossing is reduced, blocking between the labels can be prevented, and the labels in the holder can be reliably fed into the mold one by one. High productivity can be realized by eliminating troubles associated with the supply of labels.
Furthermore, the air between the parison and the label can escape by using the unevenness due to the embossing, and it is possible to effectively suppress the occurrence of floating in the label due to the air accumulation.

  In addition, by making the adhesive layer the same material as the container body surface, the adhesive layer surface is melted by the heat of the parison, and the label is welded to the container body surface. Even if the container is used in the environment or the container is squeezed or crushed to take out the contents, the label does not peel off.

  Next, in accordance with the structural requirements (2) and (3), the label thickness is set to 30 microns or more and the elastic modulus of the label is set to a range of 200 MPa or more. It is possible to reliably supply the sheet one by one into the mold, eliminating the trouble associated with the supply of the label into the mold and realizing high productivity. Thus, in order to realize the reliable supply of the label, it is necessary that the label thickness and the elastic modulus are both a certain value or more, the label thickness is set to 30 microns or more, and the elastic modulus is set to 200 MPa or more. By doing so, a reliable supply of labels can be realized.

  In the case of a container with a label attached by an in-mold molding method, a V-shaped notch groove is formed at the boundary between the label end and the container body. If the label is too thick, the groove becomes deeper. 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 this groove as a starting point. However, by making the label thickness 80 μm or less, the groove can be made small. Even in a thin container, the container is less likely to be damaged due to the groove.

Next, in the case of a thin-walled container, as described above, when the label is thick, the label slows down the cooling of the parison by the mold, so the surface of the container body where the label is attached is the other part. This is larger than the molding shrinkage of the container body, and the container body is deformed because it is thin. In addition, there is a problem that the container body is deformed even when the elastic modulus of the label is large or the difference between the elastic modulus of the container body and the label is large,
By selecting the material and thickness of the label along the configuration requirements (2), (3), and (4), the deformation of the container due to the molding shrinkage can be effectively suppressed.

Here, the material of the container body is selected in consideration of basic performance as a container such as appearance, chemical resistance, rigidity, and further material cost,
The requirement that the difference in elastic modulus calculated by [elastic modulus of container body] − [elastic modulus of label] in the component requirement (4) is in the range of −500 MPa or more is the material from the above viewpoint. The elastic modulus of the label is not increased more than necessary with respect to the elastic modulus of the selected container body.
And according to the structural requirements (2) and (3), the thickness of the label is set to 80 microns or less and the elastic modulus is set to a range of 1000 MPa or less, and the [elasticity of container body]-[elasticity of label] The difference in the calculated elastic modulus is set to a range of −500 MPa or more, and the upper limit of the elastic modulus of the label is suppressed. Deformation can be suppressed.
Furthermore, according to the configuration requirement (5), a design or a pattern can be made to appear by the printed layer, and high-quality decoration can be exhibited. Since the printing layer is not exposed on the label surface and is so-called film back printing, there is no concern that the printing peels off or discolors due to friction between the label surfaces or the exterior or contact with water or content liquid.

  In another configuration of the present invention, in addition to the above main configuration, the difference between the molding shrinkage rate of the container body and the thermal shrinkage rate of the label is within (+/−) 3%.

  With the above configuration, by making the difference between the molding shrinkage of the container body and the thermal shrinkage of the label within (+/−) 3%, the container is effectively deformed due to the difference in shrinkage between the container body and the label. Can be suppressed.

  Still another configuration of the present invention is that the container body is made of a polyolefin resin, and the base film layer and the adhesive layer of the label are made of a polyolefin film.

  With the above configuration, the polyolefin resin is crystalline, and the molding shrinkage rate of the container body is relatively large. However, by making the base film layer and the adhesive layer constituting the label made of a polyolefin film, the molding shrinkage of the container body The difference between the rate and the thermal shrinkage rate of the label can be reduced. Further, the label can be directly welded to the container body through the adhesive layer.

Here, as the polyolefin resin constituting the container body in the present invention, a polyethylene resin, a polypropylene (hereinafter sometimes abbreviated as PP) resin, or a copolymer mainly composed of ethylene or propylene can be used. A blended product mainly composed of polyolefin resin 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 the polyolefin film used for the base film layer and the adhesive layer, polyethylene resin, polypropylene resin, or a film made of a copolymer mainly composed of ethylene or propylene, or synthetic paper can be used. The heat shrinkage ratio can be selected in a wide range depending on the unstretched film, stretched film, further stretched mode, heat set temperature, and the like. Moreover, an antistatic agent, a coloring agent, a pearl material, etc. may be kneaded, and metal vapor deposition may be given to one side.

  Still another configuration of the present invention is the above configuration, wherein the container body is made of polyethylene resin, the label is formed on the base film layer made of PP resin unstretched film by gravure printing, and further dry laminated An adhesive layer made of a linear low density polyethylene (hereinafter abbreviated as LLDPE) resin film is laminated through the layers.

The said structure concerns the specific layer structure of a label, and can be used as a label especially suitable for a polyethylene-type container main body.

Since the present invention has the above-described configuration, the following effects can be obtained.
In other words, in a thin container with an in-mold label, the label adhesive layer is made of a synthetic resin film of the same system as the container body and further embossed, and the thickness of the label is 30. By setting the elastic modulus in the range of ˜80 microns, the elastic modulus in the range of 200 to 1000 MPa, and the difference in elastic modulus calculated by [elastic modulus of container body] − [elastic modulus of label] to be −500 MPa or more,
While ensuring productivity related to continuous supply of labels into the mold cavity, generation of wrinkles on the label during molding and occurrence of floating due to air accumulation can be sufficiently suppressed, and molding shrinkage can also be achieved. The resulting deformation of the container can be effectively suppressed, and the label can be firmly and integrally bonded to the body wall of the container main body with high productivity without sacrificing the characteristics of in-mold molding. On the other hand, it is possible to provide a thin-label container with a good appearance that does not have wrinkles or floats on the label, adheres firmly to the surface of the container, and does not deform. Furthermore, high-quality decoration can be exhibited safely.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below along the examples with reference to the 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 0.6 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, and the elastic modulus is about 550 MPa in both the radial direction and the height direction.

A rectangular label 11 is affixed to the front and back of the body 2 simultaneously with the blow molding of the container body 1 by an in-mold molding method.
The label 11 has a base film layer 12 made of PP resin unstretched film (CPP) and an adhesive layer 15 made of LLDPE resin film.
It has a layer structure of base film layer 12 / gravure printing layer 13 / dry laminate layer 14 / adhesive layer 15 (see FIG. 3).
The base film layer 12 has a layer thickness of 30 microns, the adhesive layer 15 has a layer thickness of 30 microns, the overall average thickness t is 65 microns, and the thermal contraction rate in the lateral direction of the label is 2.0%. The direction of thermal shrinkage is 1.4%. The elastic modulus is about 600 MPa in both the horizontal and vertical directions.

Here, the adhesive layer 15 made of an LLDPE resin film functions to adhere (weld) to the surface of the body portion 2 of the container body 1 by in-mold molding, but has irregularities formed by embossing.
And the unevenness | corrugation formed by this embossing can relieve the shrinkage | contraction behavior of the label by the contact of the high temperature parison which is a main factor of wrinkle generation, and suppresses generation | occurrence | production of wrinkles effectively.
In addition, in order to reduce the contact area between the label surface where the irregularities overlap and align in the holder, and the label adhesive surface, the labels are removed from the holder securely one by one in the automatic supply of labels to the mold. Can be supplied in the mold.
Further, the unevenness exerts a function as an air escape path during in-mold molding so that the label 11 is free from the occurrence of floating (blister) due to air accumulation.

  And this label 11 corona-treats one surface of the base film layer 12, forms a printed layer 13 by gravure printing, and further laminates an adhesive layer 15 via a dry laminate layer 14 in a dry lamination process, It is created by punching with a bush method in a predetermined shape.

Moreover, in the said container main body 1 and the label 11,
The difference in elastic modulus calculated by [elastic modulus of container body 1] − [elastic modulus of label 11] is about 550−600 = −50 MPa, and is in a range of −500 MPa or more.
The difference between the molding shrinkage of the container body 1 and the thermal shrinkage of the label is
[Molding shrinkage rate in the radial direction of the container body 1 is 2.2%] − [shrinkage rate in the horizontal direction of the label 11 is 2.0%], 0.2%,
[Molding shrinkage ratio 1.8% in the height direction of the container body 1]-[shrinkage ratio 1.4% in the vertical direction of the label 11] is 0.4%, both within (+/-) 3% It becomes the range.

Here, FIG. 5 is a schematic explanatory view of a process of forming the thin container with an in-mold label of 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 stuck to the body wall 2W in an integrated state.

FIG. 2 shows a plane cross section of the body portion 2 of the container body 1 formed in this way. Combined with the effect of the unevenness due to the embossing of the adhesive layer 15, the label 11 has no wrinkles or floats, and is cleanly flush with the front surface of the container main body 1 in the same plane as the surface of the body wall 2 </ b> W over almost a half circumference. It is stuck and is in a smooth and high-quality sticking state.
As for the deformation of the container, not only the deformation of the entire container due to the sticking of the label 11 but also the occurrence of sink marks in which the body wall 2W is dented inward in the vicinity of the edge portion 11e of the label 11 It was suppressed enough to be undetectable.

  FIG. 4 shows a case where the thickness of the label 11 is thick, the elastic modulus is high, or the molding shrinkage rate of the container body 1 is larger than that of the label 11 with respect to the range defined in the main configuration of the present invention. It is the schematic explanatory drawing which showed in a plane cross section the example of the deformation | transformation aspect of a container resulting from the molding shrinkage | contraction of a container main body differing between a label sticking surface and the other part. As shown in FIG. 4, at the portion where the label 11 is not attached (the left and right portions in the drawing), the trunk wall 2W is in a deformed state where it travels in a convex shape compared to the normal state, and the entire container is large. It is deformed.

As mentioned above, although embodiment of this invention and its effect were demonstrated along the Example, this invention is not limited to this Example.
The combination of the materials used for the container main body 1 and the label 11 can be various combinations within a range that satisfies the requirements relating to the elastic modulus and the 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, a film such as a polyester film can be used as the base material of the label 11, and can be selected from an unstretched film or stretched films having various stretching ratios. it can.

As described above, the thin-walled container with an in-mold label according to the present invention has no wrinkles or floats on the label, and does not deform the container. Is expected.

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 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 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; Base film layer 13; Print layer 14; Dry laminate layer 15; ; Decompression intake passage t; thickness

Claims (4)

Synthetic resin base material by the in-mold molding method at the same time as molding on the synthetic resin container body (1) having an average thickness of 0.1 to 0.8 mm in the body (2) by blow molding method In a container in which a label (11) on which a film layer (12) and an adhesive layer (15) are laminated is adhered to the body (2), the label (11) is made of a transparent base film layer (12 ) Is formed on one surface of the printed layer (13), and the adhesive layer (15) is laminated on the printed layer (13), and the adhesive layer (15) is the same type of synthetic resin as the container body surface. The film is made of an embossed film, the thickness of the label (11) is in the range of 30 to 80 microns, the elastic modulus of the label (11) is in the range of 200 to 1000 MPa, and [container body (1) Of elasticity]-[elastic modulus of label (11)] In-mold labeled thin container, wherein the difference in elastic modulus issued that the above range -500 MPa. The thin-walled container with an in-mold label according to claim 1, wherein the difference between the molding shrinkage of the container body (1) and the thermal shrinkage of the label is within (+/-) 3%. 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 base film layer (12) and the adhesive layer (15) of the label (11) are made of a polyolefin film. . The container body (1) has a surface made of polyethylene resin, a label (11) is formed on a base film layer (12) made of polypropylene resin unstretched film by gravure printing, and further dry laminated. The thin-walled container with an in-mold label according to claim 3, wherein an adhesive layer (15) made of a linear low density polyethylene resin film is laminated via the layer (14).

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