JP3727834B2 - Manufacturing method of heat-resistant neck bend container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called neck-bent container in which a spout is bent with respect to the axis of the container body in order to improve the ease of drinking and the like, and the container is produced with a high resistance to heat. It aims to improve efficiency and stabilize quality.
[0002]
[Prior art]
Conventionally, as a container filled with a liquid material, a synthetic resin container with a bent inner plug attached to the neck of the container or a bent neck of the container itself has been used for the purpose of improving the ease of pouring during use. Has been.
[0003]
Among the above-mentioned containers, a deformed container in which the neck of the container itself is bent is blow-molded by inserting a parison obtained by extrusion forming with a die into a mold from the viewpoint of moldability such as the degree of bending of the neck. In general, it is produced by so-called direct blow molding.
[0004]
By the way, containers for filling beverages such as soft drinks are not by direct blow molding, but generally by biaxial stretch blow molding represented by polyethylene terephthalate resin. Many small containers represented by size are on the market.
[0005]
In particular, there are cases where small containers for beverages are carried, and in this case, it is often seen that the contents are directly taken from the container without being transferred to a cup or the like, and this kind of container is also easy to drink. There is a need for improvements.
[0006]
In addition, drinking the contents in a normal state can be handled to some extent even with the current shape, but for example, if you drink while lying in a bed or the like, you can use a device such as a straw. If it is not used, it cannot be ingested from the container, and development of a container that takes these points into consideration has been demanded.
[0007]
Furthermore, when filling high-temperature contents as a sterilization treatment or when it is assumed that high-temperature liquid is touched to clean the container, shape deformation due to heat is inevitable. In addition, high resistance to heat is required.
[0008]
The subject of this invention exists in the place which is excellent in heat resistance and proposes the manufacturing method of the heat resistant neck bending container which can be manufactured efficiently under a comparatively simple process.
[0009]
[Means for Solving the Problems]
The present invention, in producing a neck-bending container in which the neck part forming the spout of the container is bent with respect to the axis of the container body,
First, prepare a preform made of a synthetic resin having a thin-walled portion and a thick-walled portion, and having an uneven-thickness cylinder where they are continuously and smoothly connected, and then subject this preform to primary biaxial stretch blow molding, The molded body by primary biaxial stretch blow molding is heat-treated to shrink the molded body and bend along the longitudinal direction to form an intermediate molded body, and the intermediate molded body is maintained in its curved state. A method for producing a heat-resistant neck-bending container, characterized in that a secondary biaxial stretch blow molding is performed to obtain a final molded product.
[0010]
In the above manufacturing method, it is preferable to use a preform in which the thickness difference between the thinnest portion and the thickest portion of the body portion is at least 5%.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The body of the container is an uneven body with a thin part and a thick part, and heat treatment is performed during the manufacturing process of the container, and a difference in shrinkage is produced between the thin part and the thick part, and then poured. The neck forming the mouth is bent with respect to the container body.
[0012]
【Example】
Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIGS. 1 (a) and 1 (b) show the appearance of a neck bend container according to the present invention and its AA cross section.
[0013]
In the figure, reference numeral 1 denotes a container body, and 2 denotes a neck portion formed integrally with the container body 1, and the neck portion 2 is bent with respect to the axis L of the container body 1.
[0014]
As shown in FIG. 1B, the container main body 1 finally has substantially the same wall thickness.
[0015]
The neck bend container as shown in FIG. 1 is manufactured as follows.
[0016]
First, a preform P having an uneven thickness cylinder as shown in FIGS. 2A and 2B is formed by applying an injection molding method.
[0017]
Then, into the mold k shown a preform P in FIG. 3 having a desired cavity, and clamping obtain a molded product P ₁ performs primary biaxial stretch blow molding.
[0018]
Next, the molded body obtained by primary biaxial stretch blow molding is subjected to heat treatment at 110 to 255 ° C. by a heating means such as a heater.
[0019]
This heat treatment is a process performed to relax the strain in the molded body P ₁ occurring during the primary biaxial stretch blow molding, thereby moldings P ₁ by the primary biaxial stretch blow molding is generally contracted However, as shown in FIG. 4, there is a difference in the amount of shrinkage between the thin and thick parts (the shrinkage is large at the thin part and the shrinkage is small at the thick part), and molding is performed. The whole body transforms into a banana shape.
[0020]
Next, insert the intermediate product P ₁ deformed into a banana shape the mold k ₁ for secondary biaxial stretch blow molding suitable for forming the neck bending container as shown in FIG. 5, the clamping blow molding The final molded product with the neck bent as shown in FIG. 1 is obtained.
[0021]
In order to blow mold a container made of a synthetic resin such as polyethylene terephthalate, a molded product having a desired cross-sectional shape can be obtained by a single blow molding. In this case, the resin density is less than 1.38 g / cm ^3. However, the maximum temperature at which deformation of the container can be avoided is limited to about 87 ° C.
[0022]
By the way, as in the present invention, the molded body obtained by the first biaxial stretch blow molding is subjected to heat treatment, the molded body is contracted to reduce strain, and a container having a desired cross-sectional shape. Therefore, it is obtained by performing the second biaxial stretch blow molding (double blow molding method) within a range in which substantially no strain remains at a smaller stretch ratio than the primary biaxial stretch blow molding. Further, the final molded product has a density of 1.38 g / cm ³ or more, the limit temperature of the container exceeds 90 ° C., and the heat resistance characteristics are remarkably improved.
[0023]
In applying the double blow molding method as described above, in order to improve the heat resistance of the neck portion of the container, the temperature of the jig 3 holding the portion corresponding to the neck portion of the container is increased during blow molding, and the temperature is increased. The part is crystallized (whitened).
[0024]
The reason why the heat resistance of the container is improved by the double blow molding method is that the resin density is increased by stretch crystallization (orientation crystallization) in secondary biaxial stretch blow molding, and primary biaxial stretch blow by heat treatment. This is because most of the distortion remaining in the molding can be removed, and the degree of shrinkage deformation caused by heat (contents, etc.) applied from the outside is extremely small.
[0025]
In the present invention, as the material constituting the container, a material that can be biaxially stretch blow molded such as a polyester-based resin typified by polypropylene or polyethylene terephthalate is useful.
[0026]
The container may be a laminated container containing a barrier layer such as EVOH or nylon in the middle in addition to the resin as described above. In addition to containers, it can be applied to products such as baby bottles that require heat resistance.
[0027]
The preform P used in manufacturing the container according to the present invention has the thickest part t ₁ and the thinnest part t ₂ so that the part corresponding to the trunk of the container body is more advantageously deformed during the heat treatment. Is preferably about t ₁ −t ₂ = 0.5 to 1.0 mm (or at least 5% thickness difference). The thickness difference occurs in the molded body P ₁ barrel after primary biaxial stretch blow molding by giving a condition relating to the preform, the preform was modified to banana by heating the molded body P ₁ as a result You can definitely get it.
[0028]
In addition, each process condition of the biaxial stretch blow molding at the time of manufacturing the container according to this invention should just be shape | molded on the conditions normally used. The following conditions are advantageously met when polyethylene terephthalate is used.
Preform: Heated to 70 to 130 ° C. capable of exhibiting stretching effect Mold: Heated to about 50 to 230 ° C. Stretched area ratio: 4 to 22 times, more preferably 6 to 15 times (preform basis)
[0029]
In the heat treatment,
Heating temperature: 110-255 ° C, more preferably 130-200 ° C
[0030]
In secondary biaxial stretch blow molding,
Mold: 60 to 120 ° C, more preferably 80 to 100 ° C Heating resin density: 1.380 to 1.395 g / cm ³ (final molded product)
[0031]
【The invention's effect】
According to the present invention, in the heat treatment for improving heat resistance, the molded body itself is actively deformed by heat shrinkage, and the neck portion of the container is bent using this deformation. Is required, efficient production is possible, and the quality is always stable.
[Brief description of the drawings]
FIGS. 1A and 1B are views showing an appearance of a container according to the present invention and an aa cross section thereof.
FIGS. 2A and 2B are views showing a cross section of a parison suitable for use in manufacturing a container according to the present invention in terms of its side and plane.
FIG. 3 is a view showing a state in which a primary blow molding is performed after being inserted into a mold and clamped.
FIG. 4 is a view showing a state in which a molded body by primary biaxial stretch blow molding is contracted by heat treatment.
FIG. 5 is a view showing a state in which a heat-treated primary biaxially stretched blow molded article is placed in a secondary biaxially stretched blow mold and clamped.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Container body 1a Thin part 1b Thick part 2 Neck part 3 Jig 4 Bottom bush P Preform P ₁ Molded body

Claims (2)

In producing a bent container in which the neck forming the spout of the container is bent with respect to the axis of the container body,
First, prepare a preform made of a synthetic resin having a thin-walled portion and a thick-walled portion and have an uneven-thickness cylinder that is connected continuously and smoothly, and then subject this preform to primary biaxial stretch blow molding, The molded body by primary biaxial stretch blow molding is heat-treated to shrink the molded body and bend along the longitudinal direction to form an intermediate molded body, and the intermediate molded body is maintained in its curved state. A method for producing a heat-resistant neck-bending container, characterized in that a secondary biaxial stretch blow molding is performed to obtain a final molded product. The manufacturing method according to claim 1, wherein a preform having a thickness difference of at least 5% between the thinnest portion and the thickest portion of the body portion is used.

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