JP3272424B2 - Polyethylene injection label for in-mold molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene-injected label for in-mold molding which is less deformed and does not wrinkle when welded to the molded article.

[0002]

2. Description of the Related Art Conventionally, a film of polyethylene alone has been used as a label for in-mold molding of polyethylene injection.

[0003]

In the case of the above-mentioned polyethylene single film label, when the polyethylene is injected into a mold by injecting polyethylene having compatibility with the film, the label and the molded article main body are used. It is good for the integration of the label, but when you want to give the label a barrier property, or when you want to print on the label, etc. Was difficult. This is because the printing flow and the barrier property of polyethylene are low. Therefore, it has become necessary to make the label multi-layered with a resin film different from the resin for injection molding. From such a point, a laminated film such as polyester / paper / polyethylene is used as the label. Therefore, if printing is performed on polyester or paper of a laminated film with good barrier properties and printability, even if the resin that becomes the molded product main body is injected into this laminated label in the mold, the printed surface Therefore, the printing does not become unclear, and if the resin for injection molding is polyethylene, the innermost layer of the label is polyethylene, so that the integration of the label and the cap body is good. However, when the label is a laminated film, when the label is welded to the surface of the molded article body by injection molding, the elongation of polyester and paper and the follow-up force to the molded article due to the heat molding temperature, and the influence of the molded article itself. Due to the balance with shrinkage after molding, furthermore, steps for reinforcement at the peripheral edge of the surface of the molded body, ribs for stacking to prevent displacement when stacked, etc. Wrinkles are likely to occur, and the change as a molded product is remarkable. The present invention has been made in view of the above points,
It was created as a result of experiments and research, and its purpose is to prevent wrinkles from forming on the label surface when the laminated label is welded to the surface of the molded product by polyethylene injection in-mold molding. Another object of the present invention is to obtain a molded article with a small deformation of the cap body and high accuracy.

[0004]

In order to achieve the above object, in the present invention, a laminated film is used as a label, and its layer structure and the thickness of the innermost film in in-mold molding are specified. In this way, the problem is solved. That is, the polyethylene injection-molded in-mold label of the present invention comprises an outer layer made of a biaxially stretched polyester film and an innermost layer made of a chain low-density polyethylene film having a thickness of 80 μm or more.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIG. 4, an overcap (A ') such as a dry milk can or the like in which a conventional laminated label (a') is welded to the surface of a molded article body (b ') will be described. The conventional laminated label (a ′) is composed of polyester / paper / polyethylene as shown in FIG. 5, and is put in a mold with the polyethylene side inside and the mold is closed. When polyethylene is injected into this to form an overcap (A ') such as a dry milk can, the laminated label (a') is welded to the top plate (1 ') surface of the cap body (b'). However, this cap body (b ') prevents the deformation and strengthens the outer surface (2') of the top plate (1 ').
Is formed with a rib (4 ') for stacking to prevent a step (3') and a displacement when stacked.
Since the innermost layer of the laminated label (a ') is a polyethylene layer, and the cap body (b') of injection molding is also polyethylene, the laminated label (a ') is welded to the cap body (b'), but the outer layer is Polyester and paper have wrinkles (5 ') on their surfaces due to heating during injection molding and shrinkage of polyethylene in the cap body (b') after injection molding, steps, ribs, and the like. This wrinkle (5 ') is particularly pronounced in steps (3') and ribs (4 ')
And so on, and the deformation as a molded product is remarkable, so that the product is not good in appearance.

On the other hand, a polyethylene injection-molded label (a) according to an embodiment of the present invention is shown in FIG.
As shown in the figure, the polyester film comprises an outer layer (1) of a polyester film and an innermost layer (2) of a chain low-density polyethylene film, and the polyester film of the outer layer (1) is biaxially stretched. The chain low density polyethylene film of the inner layer has a thickness of 80 μ or more.
A polyethylene injection in-mold molding label (a) comprising an outer layer (1) of such a biaxially stretched polyester film and an innermost layer (2) of a chain low-density polyethylene film having a thickness of 80 μ or more. ) Is placed in a mold with the chain-like low-density polyethylene film (2) side inward, the mold is closed, low-density polyethylene is injected into the mold, and an overcap (eg, a dry milk can, etc.) A) is molded. In this case, the polyethylene injection label for in-mold molding (a) is the innermost layer (1).
Is a chain low-density polyethylene film and the injection resin for molding the cap body (b) is low-density polyethylene, so that the label (a) is well welded to the cap body (b) and integrated. At this time, since the thickness of the chain low-density polyethylene film (2) as the innermost layer is as thick as 80 μ or more, it follows the shrinkage of the low-density polyethylene of the cap body (a) after injection molding and absorbs the generation of wrinkles. At the same time, since the polyester film (1) of the outer layer is biaxially stretched, it shrinks uniformly by heating, follows the molded product, and has relatively strong stiffness. There is little deformation.

On the other hand, for example, when the innermost chain low-density polyethylene film (2) has a thickness of about 40 μm, even if the outer polyester film (1) is biaxially stretched. The temperature at the time of injection molding of the cap body (b), shrinkage and step of the injection resin, wrinkles due to ribs, etc. appear on the label (a) surface, and the chain low-density polyethylene film (2) has a thickness of 80 μ or more. However, if the polyester film (1) of the outer layer is not biaxially stretched, wrinkles will occur due to the temperature at the time of injection molding, the heat shrinkage of the injection resin, and the steps, ribs and the like. From the above, the polyethylene injection label for in-mold molding of the present invention (a)
Is a biaxially stretched polyester film layer (1) and 80
Together with the chain-like low-density polyethylene film layer (2) having a thickness of μ or more, wrinkles are prevented from occurring, and deformation of the lid is suppressed to a small extent. This prevents deformations formed on the outer surface (4) of the top plate (3) of the molded article body (b), steps for reinforcement (5), and ribs for stacking to prevent displacement when stacked. The presence of (6) has no effect, does not cause wrinkles, and causes little deformation as a molded article. In the in-mold molding of the molded article main body (b), low-density polyethylene is used.
This is because it has good moisture proof properties and is suitable as an overcap (A) for a dry milk can or the like.

[0008]

According to the present invention, a biaxially stretched polyester film is used as an outer layer and a chain low-density polyethylene film having a thickness of 80 μm or more is used as an inner layer as a polyethylene injection in-mold molding label. From this label, using a low-density polyethylene to be welded to a chain low-density polyethylene film and in-mold molding, for example, when forming an overcap such as a dry milk can, the temperature during injection molding of the molded article body, The effects of the injection resin shrinkage and the steps, ribs, etc. are affected by the chain low-density polyethylene film as thick as 80 μm or more in the innermost layer, which absorbs wrinkles, and the polyester film in the outer layer is biaxially stretched. Shrinks uniformly, follows the molded product,
Moreover, since it is relatively strong, it does not attract wrinkles and has little deformation as a molded product, and is extremely excellent as a label for an in-mold molded article of polyethylene injection.
In addition, the low-density polyethylene, which is an injection resin, has good fitting properties and moisture-proof properties, and is therefore truly suitable as an overcap for a dry milk can or the like.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a label in an overcap of a dry milk can or the like to which a polyethylene injection label for in-mold molding of the present invention is welded.

FIG. 2 is a partially cutaway view of the overcap.

FIG. 3 is a partial cross-sectional view showing a configuration of a polyethylene injection label for in-mold molding of the present invention.

FIG. 4 is a partially cutaway perspective view of a label in an overcap such as a dry milk can to which a conventional label is welded.

FIG. 5 is a partial cross-sectional view showing a configuration of a conventional label.

[Explanation of symbols]

 A Overcap of dry milk can, etc. a Label for in-mold molding b Cap body 1 Outer layer of polyester film 2 Innermost layer of chain low-density polyethylene film 3 Top plate 4 Outer surface 5 Step 6 Rib

Continuation of the front page (56) References JP-A-4-114191 (JP, A) JP-A-63-106692 (JP, A) JP-A-4-4121 (JP, A) JP-A-2-132487 (JP) , A) JP-A-61-67883 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09F 3/00 B29C 45/14

Claims (1)

(57) [Claims] 1. A polyethylene injection label for in-mold molding, wherein the outer layer is composed of a biaxially stretched polyester film and the innermost layer is composed of a chain low-density polyethylene film having a thickness of 80 μm or more.