JP4186275B2 - Multi-layer thin container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer thin-walled container, and more specifically, a container in which a highly flexible neck and neck for mounting a cap are integrally blow-molded on a highly flexible body, which is a medical infusion container, food container, and beverage The present invention relates to a novel multilayer thin container suitable for containers and the like.
[0002]
[Prior art]
A thin-walled container blow-molded with a low-rigidity resin is suitable for medical infusion containers and the like because it has flexibility and is excellent in drainage and volume reduction. By the way, in the infusion container, it is necessary to attach a cap for sealing the infusion to the mouth and neck. However, since the above-mentioned thin container has low rigidity of the resin itself, it is difficult to integrally mold a mouth and neck portion having high rigidity enough to attach a cap. Therefore, in this type of thin-walled container, usually, the stiffening neck and neck member is welded to the neck and neck of the container in the subsequent process, or the stiffening neck and neck member is attached to the mouth of the container during blow molding. Inserted into the neck.
[0003]
[Problems to be solved by the invention]
By the way, in the prior art mentioned above, since the mouth-and-neck member for stiffening is separately shape | molded and this is attached to the mouth-and-neck part of a container, there exists a problem that a manufacturing apparatus and a manufacturing process become complicated. There is also a problem that pinholes are likely to occur. Therefore, the present invention, etc., as a result of examining increasing the rigidity of the mouth and neck by combining at least two resins having different rigidity, adopted a multi-layer structure of high-rigidity resin and low-rigidity resin, By appropriately setting the thickness, it has been found that containers having different rigidity can be integrally formed for each part, and the present invention has been completed. That is, an object of the present invention is a container in which a highly flexible neck portion for mounting a cap is integrally blow-molded on a highly flexible body portion, and can be reduced in volume, for example, a medical infusion container or disposal An object of the present invention is to provide a novel multilayer thin container suitable for a food container or a beverage container.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a multilayer thin-walled container according to the present invention has a body portion and a neck portion for mounting a cap by extrusion blow molding of a parison, and a high-rigidity resin layer and a low-rigidity resin layer. In the case of parison extrusion molding, a parison thickness control system capable of increasing or decreasing the extrusion amount of high-rigidity resin during the parison extrusion molding increases the height corresponding to the portion corresponding to the mouth and neck. By increasing the extrusion amount of the rigid resin more than the extrusion amount of the low-rigidity resin, the rigidity of the neck and neck is set higher than that of the trunk.
[0005]
In the multilayer thin-walled container of the present invention, a highly rigid mouth-neck portion that is integrally blow-molded makes it easy and reliable to attach the cap. Moreover, since the trunk | drum containing a shoulder part and a bottom part is thin compared with a mouth neck part and its rigidity is low, it exhibits the softness | flexibility which can be folded.
[0006]
In the multilayer thin-walled container of the present invention, in order to ensure the sitting stability and self-supporting property of the container, when the parison is extruded, the amount of extrusion of the high-rigidity resin to the portion corresponding to the bottom of the container is performed by the parison thickness control system. It is preferable to set the rigidity of the bottom part higher than the rigidity of the trunk part by increasing the amount of extrusion of the low-rigidity resin.
[0007]
Moreover, in the multilayer thin-walled container of the present invention, it is preferable that the outermost layer is made of a high-rigidity resin in order to more reliably attach the cap to the mouth and neck. Furthermore, in order to store the contained liquid in a safe and reliable manner, the low-rigidity resin is a resin excellent in chemical resistance, for example, polyethylene obtained by a metallocene catalyst, and this constitutes the innermost layer. Is preferred. In order to store the content liquid more safely and reliably, an intermediate layer of a gas barrier resin is preferably provided inside the outer layer.
[0008]
Furthermore, in the multilayer thin-walled container of the present invention, it is preferable that the thickness of the barrel is 2.0 mm or less in order to ensure the flexibility of the barrel. Furthermore, in order to ensure the flexibility of the trunk and the rigidity of the neck and neck, the thickness of the high-rigidity resin layer in the trunk is 5 to 50% of the wall thickness, and the thickness of the high-rigidity resin layer in the neck and neck Is preferably 50 to 95% of the wall thickness.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a multilayer thin container according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a multilayer thin-walled container according to the present invention. FIG. 2 is a cross-sectional view of a parison extruder used in extrusion blow molding of multi-layered thin containers. 3 is a cross-sectional view of an extrusion molding machine showing a cross section orthogonal to the cross section shown in FIG. FIG. 4 is a cross-sectional view showing different embodiments of the layer structure of the multilayer thin-walled container.
[0010]
The multilayer thin-walled container of the present invention has a body (2) and a mouth and neck (3) for attaching a cap, and has high rigidity by extrusion blow molding of a parison, as indicated by reference numeral (1) in FIG. The container is integrally molded as a thin-walled container having a multilayer structure including a resin layer and a low-rigidity resin layer. Such a multilayer thin-walled container (1) has a high-rigidity resin extrusion amount for the portion corresponding to the neck (3) by a parison thickness control system that can increase or decrease the extrusion amount of the high-rigidity resin during the extrusion of the parison. By increasing the amount of extrusion of the low-rigidity resin, the rigidity of the mouth and neck (3) is set higher than the rigidity of the trunk (2).
[0011]
In the example shown in FIG. 1, the multilayer thin-walled container (1) has a two-layer structure of an outer layer (A) made of high-rigidity resin and an inner layer (B) made of low-rigidity resin. However, in the multilayer thin-walled container (1) of the present invention, the layer structure is not limited to two layers, and may be an appropriate layer structure such as three layers, four layers, and five layers.
[0012]
The wall thickness of the mouth and neck (3) of the multilayer thin-walled container (1) is usually set to about 1.5 to 4.0 mm, and the outer layer (A ). The thickness of the body (2) excluding the mouth and neck (3), that is, the body (2) including the shoulder (4) and the bottom (5) is 2.0 mm or less, usually 0.5 to 1. The thickness is set to about 5 mm, and 5 to 50% of the wall thickness is constituted by the outer layer (A) made of a highly rigid resin. For this reason, the mouth and neck (3) has sufficient rigidity to attach a cap (not shown), and the trunk (2) including the shoulder (4) and the bottom (5) is foldable and flexible. It has.
[0013]
The shape of the mouth and neck (3) is an appropriate shape corresponding to the shape of a cap (not shown). For example, as shown to (a) of FIG. 1, it shape | molds in the stepped cylinder shape which the upper end expanded. Or as shown to (b) of FIG. 1, it shape | molds in the straight cylinder shape which has a male screw (3A).
[0014]
The parison is extruded by an extruder (6) shown in FIGS. The extrusion molding machine (6) includes a two-layer die (6A) for extruding a two-layer parison (P) of an outer layer (A) of high-rigidity resin and an inner layer (B) of low-rigidity resin. . The two-layer die (6A) is provided with a first extruder (6B) that supplies a high-rigidity resin and a second extruder (6C) that supplies a low-rigidity resin.
[0015]
The first extruder (6B) and the second extruder (6C) are screw in-line type extruders in the illustrated example, but may be accumulator type extruders. As shown in FIG. 3, the screw in-line type second extruder (6C) has a structure in which a screw (6D) for extruding resin is installed in a screw cylinder (6E). The 1st extruder (6B) shown in FIG. 2 is comprised similarly. The first extruder (6B) and the second extruder (6C) are configured to locally control the resin extrusion amount by controlling the number of revolutions of the screw (6D) by a parison thickness control system (not shown). It is configured to increase or decrease automatically.
[0016]
In the multilayer thin-walled container (1) of the present invention, the high-rigidity resin constituting the outer layer (A) is a resin obtained using a Philips catalyst or a multistage Ziegler catalyst, and has an MFR of 0.02 to 1.0 and Examples thereof include polyethylene having a density of 0.940 to 0.970, or LDPE or L-LDPE having an MFR of 0.2 to 4.0 and a density of 0.925 to 0.938. In addition, polypropylene having a density of 0.885 to 0.930 can also be used as the high-rigidity resin. In this case, a block copolymer having a rubber component of 5% or more is preferable.
[0017]
The low-rigidity resin constituting the inner layer (B) includes polyethylene having a density of 0.875 to 0.910 obtained by a gas phase method, a liquid phase method or a solution method using a metallocene catalyst (single site catalyst). It is done. This low-rigidity resin is a very homogeneous polymer having a very sharp molecular weight distribution (for example, Mw / Mn = 2 to 3.5) and a very sharp composition distribution. Such a resin is rich in flexibility, excellent in chemical resistance, and has a characteristic of high welding power with a gas barrier resin described later.
[0018]
In order to manufacture the multilayer thin container (1) of the present invention, a two-layer parison (P) of an outer layer (A) and an inner layer (B) is extruded by an extrusion molding machine (6) shown in FIGS. The parison (P) is blow-molded in a mold (not shown). When extruding the parison (P), the outer layer (A) of the parison (P) is configured by controlling the number of revolutions of the screw of the first extruder (6B) with an inverter by a parison thickness control system (not shown). The amount of the high synthetic resin to be extruded is locally increased only in the portion corresponding to the neck (3) of the multilayer thin container (1). In addition, since the parison (P) extruded from the two-layer die (6A) of the extrusion molding machine (6) has an outer layer (A) made of a highly rigid resin, the melt tension as a whole is high and its own weight Demonstrate sufficient shape retention.
[0019]
The multilayer thin-walled container (1) of the present invention manufactured by the above-described method has a thick-walled and highly rigid mouth-and-neck portion (3) integrally blow-molded. (Not shown) can be attached easily and reliably. Moreover, since the trunk | drum (2) except a mouth neck part (3), ie, the trunk | drum (2) containing a shoulder part (4) and a bottom part (5), is thin and rich in flexibility, it is easy. Can be folded. Furthermore, since the inner layer (B) is made of a resin excellent in chemical resistance, that is, polyethylene obtained by a metallocene catalyst, the contained content liquid can be stored safely and reliably. Therefore, the multilayer thin-walled container (1) of the present invention is suitable for medical infusion containers, food containers, beverage containers and the like.
[0020]
Moreover, in the multilayer thin container (1) of this invention, since the conventional neck and neck member for stiffening is unnecessary, the manufacturing apparatus and manufacturing process can be simplified. And it can prevent that a pinhole generate | occur | produces in a multilayer thin container (1) by a post process.
[0021]
In the multilayer thin-walled container of the present invention, as shown in FIG. 4A, the layer structure includes an outer layer (A) of high-rigidity resin, an intermediate layer (C) of low-rigidity resin, and an inner layer of gas barrier resin. A three-layer structure with (H) can be obtained. As the gas barrier resin, EVOH (ethylene-vinyl alcohol copolymer), PA (polyamide), or PEN (polyethylene naphthalate) can be used.
[0022]
In the multilayer thin-walled container having the three-layer structure described above, the inner layer (H) made of a gas barrier resin prevents intrusion of oxygen and the like, so that the content liquid contained in the multilayer thin-walled container can be stored more safely and reliably. I can do it.
[0023]
Further, as shown in FIG. 4B, the outer layer (A) of the high-rigidity resin, the first intermediate layer (D) of the low-rigidity resin, the second intermediate layer (E) of the gas barrier resin, A four-layer structure with the inner layer (B) of the rigid resin can be formed. Furthermore, as shown in FIG. 4C, the outer layer (A) of high-rigidity resin, the first intermediate layer (D) of low-rigidity resin, the second intermediate layer (E) of gas barrier resin, A five-layer structure of a third intermediate layer (F) of a rigid resin and an inner layer (G) of a normal resin can be formed. In this multi-layered thin container having a four-layer structure or a five-layer structure, the welding power of the layer made of a gas barrier resin can be increased by using polyethylene obtained by a metallocene catalyst as the low-rigidity resin.
[0024]
In the multilayer thin-walled container of the present invention, the rigidity of the bottom is made higher than the rigidity of the trunk by increasing the amount of extrusion of the high-rigidity resin to the portion corresponding to the bottom of the container as compared with the amount of extrusion of the low-rigidity resin. It can be set to ensure the sitting stability and independence of the container.
[0025]
Furthermore, in the multilayer thin-walled container of the present invention, it is possible to balance the flexibility and thickness of the barrel by increasing or decreasing the extrusion amount of the low-rigidity resin to the portion corresponding to the barrel.
[0026]
【The invention's effect】
As described above, according to the multilayer thin-walled container of the present invention, the highly rigid mouth-neck part integrally blow-molded makes it easy and reliable to attach the cap, and the thin-walled and low-rigid body part is folded. Since it exhibits possible flexibility, it is suitable for medical infusion containers, food containers, beverage containers and the like. And since the separate neck and neck member for stiffening becomes unnecessary, the manufacturing apparatus and manufacturing process can be simplified.
[0027]
In the multilayer thin-walled container of the present invention, when the rigidity of the bottom part is set higher than the rigidity of the trunk part by increasing the extrusion amount of the high-rigidity resin to the portion corresponding to the bottom part of the container more than the extrusion amount of the low-rigidity resin. Therefore, it is possible to ensure the sitting stability and independence of the container.
[0028]
In the multilayer thin-walled container of the present invention, when the high-rigidity resin layer is the outer layer, the cap can be more reliably attached to the mouth and neck. Further, when the inner layer is formed of a low-rigidity resin made of a resin excellent in chemical resistance, for example, polyethylene obtained by a metallocene catalyst, the contained content liquid can be stored safely and reliably. Furthermore, when an intermediate layer made of a gas barrier resin is provided between the outer layer and the inner layer, the content liquid can be stored more safely and reliably.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a multilayer thin container according to the present invention.
FIG. 2 is a cross-sectional view of a parison extruder used in extrusion blow molding of multilayer thin-walled containers.
FIG. 3 is a cross-sectional view of an extrusion molding machine showing a cross section orthogonal to the cross section shown in FIG. 2;
FIG. 4 is a cross-sectional view showing different embodiments of the layer structure of the multilayer thin-walled container.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1: Multilayer thin container 2: Body part 3: Mouth neck part 3A: Male screw 4: Shoulder part 5: Bottom part 6: Extruder 6A: Two-layer die 6B: 1st extruder 6C: 2nd extruder 6D: Screw cylinder 6E: Screw A: Outer layer B: Inner layer C: Intermediate layer D: First intermediate layer E: Second intermediate layer F: Third intermediate layer G: Inner layer H: Inner layer P: Parison

Claims (10)

It is a container integrally formed as a thin-walled container having a multilayer structure including a body part and a neck part for mounting a cap, and a high-rigidity resin layer and a low-rigidity resin layer by extrusion blow molding of Parison. In the extrusion molding of the parison, the extrusion amount of the high rigidity resin to the portion corresponding to the neck and neck is increased from the extrusion amount of the low rigidity resin by a parison thickness control system capable of increasing or decreasing the extrusion amount of the high rigidity resin. Therefore, the multi-layered thin container is characterized in that the rigidity of the mouth and neck is set higher than the rigidity of the trunk. When extruding a parison, the parison wall thickness control system increases the amount of high-rigidity resin extruded to the part corresponding to the bottom of the container over that of low-rigidity resin, so that the rigidity of the bottom is greater than the rigidity of the barrel. The multilayer thin-walled container according to claim 1, which is set to be high. The multilayer thin-walled container according to claim 1 or 2, wherein the layer of high-rigidity resin constitutes the outermost layer. The multilayer thin-walled container according to any one of claims 1 to 3, wherein a gas barrier resin layer is provided inside the outer layer. The multilayer thin-walled container according to any one of claims 1 to 4, wherein a thickness of the trunk is 0.5 to 2.0 mm. The thickness of the high-rigidity resin layer in the trunk is 5 to 50% of the wall thickness, and the thickness of the high-rigidity resin layer in the mouth and neck is 50 to 95% of the wall thickness. A multilayer thin-walled container according to crab. The high-rigidity resin is a resin obtained by a Phillips catalyst or a multistage Ziegler catalyst and has an MFR of 0.02 to 1.0 and a density of 0.940 to 0.970, or an MFR of 0.2 to 4.0. And a low-rigidity resin is a polyethylene having a density of 0.875 to 0.910 obtained by a metallocene catalyst, which is either LDPE or L-LDPE having a density of 0.925 to 0.938. A multilayer thin container according to any one of the above. The high-rigidity resin is polypropylene having a density of 0.885 to 0/930, and the low-rigidity resin is polyethylene having a density of 0.875 to 0.910 obtained by a metallocene catalyst. The multilayer thin-walled container as described. The multilayer thin-walled container according to any one of claims 1 to 8, wherein the low-rigidity resin layer constitutes the innermost layer. The multilayer thin-walled container according to any one of claims 4 to 9, wherein the gas barrier resin is EVOH, PA, or PEN.

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