JP5737653B2 - Synthetic resin square housing - Google Patents

Description

The present invention relates to a synthetic resin prismatic casing by biaxial stretch blow molding, and more particularly to a thick and small prismatic casing.

Conventionally, a biaxially stretched blow molded casing made of polyethylene terephthalate (hereinafter referred to as PET) resin has excellent transparency, mechanical strength, heat resistance, gas barrier properties, etc., and is widely used as containers for various beverages. However, the use as a substitute for small glass bottles for cosmetics is also progressing.
And in the case as a substitute for this kind of glass bottle, it is required to form a thick peripheral wall so that the texture of the glass bottle appears.
For example, Patent Document 1 describes an invention relating to a small round casing by stretch blow molding made of PET resin.

JP 2009-286457 A

Here, the casing described in Patent Document 1 is a round casing having a cylindrical body, but is small in size by a biaxial stretch blow molding from a cylindrical bottomed test tube preform and has a thick peripheral wall. When trying to form a square housing, the distance from the outer peripheral surface of the peripheral wall of the cylindrical preform to the corner wall of the molded body becomes long, so the peripheral wall of the preform is locally near the square wall. The wall thickness of the peripheral wall becomes thin due to stretching.
In particular, in the vicinity of the bottom, in addition to the lateral extension toward the square wall of the housing, the longitudinal stretching overlaps and local stretching deformation is further concentrated, so that local stretching deformation is further concentrated, so that the vicinity of the four square walls at the bottom of the housing The thinning becomes remarkable.

8 to 12 are diagrams for explaining the thinning of the above-described square wall and bottom in a small and thick square casing formed by biaxial stretching blow molding from a conventional test tube preform. FIG. 9 is a plan view and a half longitudinal front view showing an example of a conventional rectangular housing, FIG. 9 is a plan sectional view taken along the line EE of FIG. 8B, and FIG. 10 is a drawing deformation process inside the mold. FIG. 11 is a schematic diagram for explaining the above, FIG. 11 is a half longitudinal section of the lower half region of the housing, taken along line DD in FIG.
12 is a preform used to mold the casing 101 of FIG. 8, wherein (a) is a plan view, (b) is a half-longitudinal front view, and (c) is a FF line in (b). It is a plane sectional view shown along.

The housing 101 has a square cylindrical body portion 104 having a peripheral wall formed by four square walls 104c connecting the four panel walls 104p and the adjacent panel wall 104p, and a shoulder portion 103 is provided at the upper end of the body portion 104. The bottom tube 106 is formed in a square shape, has a total height of 82 mm, a lateral width of 27 mm, and extends from the trunk portion 104. The average wall thickness of the peripheral wall over the bottom wall 106 is about 3 mm.
A preform 111 shown in FIG. 12 is a test tube injection-molded product, and has a cylindrical tubular portion 114. The tubular portion 114 has an upper end 112 connected to the upper end and a bottom 115 connected to the lower end. It is configured.

  In the plane cross section of the casing 101 shown in FIG. 9, the plane cross section shape of the preform 111 shown in FIG. 12C is shown to be overlapped with a two-dot chain line. When blow-molding a meat square casing, the distance L12 from the peripheral wall of the cylindrical body 114 of the cylindrical preform 111 to the square wall 104c of the casing 101 is considerably larger than the distance L11 to the panel wall 104p. .

  For this reason, as shown in the schematic explanatory diagram of FIG. 10, in the process of stretching the preform 111, the cylindrical portion 114 is stretched and deformed into a bulging shape, and the outer peripheral surface of the peripheral wall is a circle 114a indicated by a one-dot chain line in the figure. As shown in the figure, the resin is cooled while contacting the position Mp corresponding to the left and right center part of the panel wall 104p of the cavity surface of the mold M, and further the contact area spreads on both sides of the position Mp. With the end of such a contact region as a base, local stretching deformation proceeds to a position Mc corresponding to the corner wall 104c of the cavity (see the white arrow in FIG. 10), and as a result, in FIG. As shown in FIG. 4, the thickness t12 of the square wall 104c of the casing 101 is thinner than the thickness t11 of the central portion of the panel wall 104p.

Next, FIG. 11, which shows a longitudinal sectional view in the diagonal direction of the lower half of the casing 101, shows the longitudinal sectional shape of the preform 111 shown in FIG. ing.
As can be seen from this figure, the corner portion 106c connecting the lower end portion of the peripheral wall of the cylindrical portion 114 and the bottom wall 106 of the barrel portion 104, particularly the lower end portion of the square wall 104c shown in FIG. In the corner portion 106c, the local stretching deformation in the vertical direction overlaps in addition to the local stretching deformation in the vicinity of the square wall 104c as seen in the plane cross section described above, and the thinning becomes remarkable.

In the case of a transparent or translucent container, the thickness non-uniformity represented by the thinning in the vicinity of the corner wall 104c or the corner portion 106c as described above can be seen from the outside of the container. Since optical spots appear due to non-uniformity and non-uniformity of stretch deformation, the clear transparency like a glass bottle is impaired, and there is a possibility that the appearance appearance as a product is greatly deteriorated. This is a major problem particularly in containers for cosmetics and the like intended to differentiate products with high-quality packaging.
Furthermore, if the above-mentioned local stretching deformation is concentrated at the bottom, in the extreme case, the grounding function, which is one of the important functions of the bottom, is impaired, and the standing posture of the housing becomes unstable. There is also a fear.

The present invention has been made in view of the problems related to the small and thick rectangular frame by the biaxially stretched blow molding in the prior art, particularly in the corner wall of the peripheral wall of the blow molded container and the corner of the bottom. It is a technical problem to suppress local stretching deformation and thinning due to this deformation, and it is an object to provide a small and thick rectangular box with a glass bottle-like high-quality appearance. To do.

The present invention comprises an invention relating to a synthetic resin square housing and an invention relating to a molding method thereof. First, an invention relating to a synthetic resin square housing will be described.
Among the means for solving the above-mentioned problems, the main structure relating to the synthetic resin prismatic casing of the present invention is a synthetic resin prismatic casing,
A cylindrical mouth portion is erected on the upper end of the cylindrical portion having a rectangular cross-sectional shape of the outer peripheral surface of the peripheral wall, and the inner peripheral surface of the cylindrical portion faces downward and the inner peripheral surface of the cylindrical mouth portion faces downward. It is a biaxial stretch blow-molded product by a hot parison method using a synthetic resin preform by a bottomed tubular injection molding in which the bottom end of the tubular portion is closed with a bottom wall, and is formed to extend.
It has a rectangular cylindrical body that is extended from the cylindrical part in a similar manner, and a cylindrical mouth tube part is erected on the upper end of the body part via a shoulder, and the lower end is a rectangular bottom wall The thickness of the four corner walls of the peripheral wall of the trunk is equal to or greater than the thickness of the four panel walls that form the peripheral wall of the trunk with the square wall, and from the center of the bottom wall In the region that reaches the lower end of the four corner walls of the peripheral wall of the body portion, the wall thickness increases in the vicinity of the corner wall (the corner portion that bends and connects the bottom wall and the lower end of the corner wall at a substantially right angle). , Ru der that the inner peripheral surface of the corner portion and arcuately chamfered shape.

Here, it is assumed that the peripheral wall of the rectangular tubular body of the casing is composed of four square walls that bend and connect the four panel walls and the adjacent panel wall at a right angle.
With the above configuration, the outer peripheral surface of the peripheral wall of the preform when viewed in a flat cross section is obtained by using a rectangular cylindrical preform having a cylindrical portion whose flat cross sectional shape of the outer peripheral surface of the peripheral wall is rectangular. Therefore, the difference between the distance to the position corresponding to the corner wall of the housing of the mold cavity and the distance to the panel wall can be reduced, and local stretching deformation in the vicinity of the corner wall can be mitigated.
Further, as described above, the local stretching deformation in the vicinity of the corner wall can be alleviated, so that significant local stretching in the corner portion formed from the lower end portion and the bottom wall of the trunk portion can be alleviated. It is possible to provide a small and thick rectangular casing that can suppress the thinning in the vicinity of the corner portion and exhibits a glass bottle-like high-quality appearance.

By forming the inner peripheral surface of the cylindrical body of the preform having the above-described configuration so that the inner peripheral surface of the cylindrical mouth portion extends downward, the flat cross-sectional shape of the outer peripheral surface is rectangular. The thickness of the square wall of the tubular portion of a certain preform can be increased, and accordingly, the thin wall can be more effectively suppressed by the square wall of the housing, and further, the square wall can be used as a panel wall. In comparison, it can also be made thick and rounded in a circular arc shape.

In the above SL principal configuration of the present invention according to the synthetic resin square bottle body, it is assumed the biaxial stretch blow molding by a hot parison method.

Biaxial stretch blow molding methods include the hot parison method and the cold parison method. The hot parison method is a method in which the preform maintains the residual heat of the injection molding and continuously moves to the blow molding process, while the cold parison method In this method, the injection molding process and the blow molding process of the preform are separated, and the injection molded preform is once cooled and then reheated to perform blow molding.

Here, in the cold parison method, the preform is once cooled and then reheated as described above. Therefore, in the case of a preform having a cylindrical portion having a rectangular outer peripheral surface as in the present invention, the preform is compared with other portions. The corners of the cylindrical part formed thick and thick and the corner part from the lower end part of the cylindrical part to the bottom wall are delayed in temperature rise due to reheating, and are stretched at a relatively low temperature. It becomes difficult to uniformly stretch the entire peripheral wall including the corner wall.
In this respect, the hot parison method moves to the blow molding process while maintaining the residual heat of the injection molding, so the temperature of the corners and corners can be maintained at a temperature suitable for stretching, including the corners and corner walls. The peripheral wall can be uniformly stretched as a whole.

  In addition, in the preform having a rectangular outer peripheral surface as in the present invention, it is necessary to achieve the position with respect to the blow molding die with high accuracy at the time of blow molding. However, according to the hot parison method, blow molding is injection molding. Therefore, it is not necessary to perform such alignment again, and productivity can be improved.

In the above main configuration, the thickness of the four corner walls of the peripheral wall of the trunk portion is equal to or greater than the thickness of the four panel walls that form the peripheral wall of the trunk portion together with the square wall. In the region reaching the lower end of the four corner walls of the peripheral wall, the wall thickness increases in the vicinity of the corner portion where the bottom wall and the lower end portion of the square wall are bent and joined at a substantially right angle. The configuration in which the inner peripheral surface of the cylindrical portion is chamfered in a circular arc shape is such that a cylindrical mouth portion is erected at the upper end of the cylindrical portion in which the flat cross-sectional shape of the outer peripheral surface of the peripheral wall is a rectangular shape . The inner peripheral surface is formed so that the inner peripheral surface of the cylindrical mouth portion extends downward, and the bottom portion of the cylindrical portion is closed with a bottom wall . This can be realized by using a preform, and by making the square wall or corner part thick and rounded into a circular arc shape, high quality Compact exhibiting appearance can provide a rectangular bottle of thick such.

  Still another configuration of the present invention relating to the synthetic resin square casing is that the average thickness of the peripheral wall from the trunk portion to the bottom wall is 2.5 mm or more in the main configuration described above. It is specified that it is a molded body.

Still another configuration of the present invention relating to the synthetic resin square casing is that in the above main configuration, the casing is transparent or translucent.
The rectangular casing of the present invention is a transparent or semi-transparent casing in which uneven stretching of the peripheral wall is suppressed by relieving local stretching deformation at the corner wall or the corner portion of the bottom. The glass bottle-like high-quality appearance can be revealed.

Next, the main configuration according to the molding method of the present invention is:
A method for molding a synthetic resin prismatic casing according to any one of the above ,
A cylindrical mouth portion is erected on the upper end of the cylindrical portion having a rectangular cross-sectional shape of the outer peripheral surface of the peripheral wall, and the inner peripheral surface of the cylindrical portion faces downward and the inner peripheral surface of the cylindrical mouth portion faces downward. It is assumed to be formed so as to extend , and a bottomed cylindrical synthetic resin preform in which the lower end of the cylindrical portion is closed with a bottom wall is injection molded,
Next, a preformed cylindrical portion is stretched and formed into a similar shape by a biaxial stretch blow molding method using a hot parison method to form a rectangular cylindrical body, and a rectangular bottom wall is formed . The thickness of the four corner walls of the peripheral wall of the trunk portion is equal to or greater than the thickness of the four panel walls that form the peripheral wall of the trunk portion together with the square wall. In the region extending to the lower end of the square wall, the thickness increases in the vicinity of the corner portion where the bottom wall and the lower end portion of the square wall are bent and connected at a substantially right angle, and the inner peripheral surface of the corner portion is seen in a longitudinal section. It is said that it is formed in a circular arc shape .

Since the synthetic resin prismatic casing of the present invention has the above-described configuration, the following effects can be obtained.
That is, in the rectangular housing having the main configuration of the present invention,
By using a rectangular cylindrical preform having a cylindrical portion with a rectangular flat cross-sectional shape of the outer peripheral surface of the peripheral wall, the mold cavity from the outer peripheral surface of the peripheral wall of the preform when viewed in a flat cross section The difference between the distance to the position corresponding to the corner wall of the housing and the distance to the panel wall can be reduced,
Further, as described above, the local stretching deformation in the vicinity of the corner wall can be alleviated, so that remarkable local stretching in the corner portion of the bottom portion can be mitigated, and thinning in the vicinity of the corner wall or corner portion is suppressed. It is possible to provide a small and thick rectangular housing that exhibits a glass bottle-like high-quality appearance.

It is a perspective view of one Example of the synthetic resin prismatic housings of the present invention. It is a half vertical front view of the housing of FIG. FIG. 1A is a plan view, and FIG. 1B is a bottom view. FIG. 3 is a plan sectional view taken along line AA in FIG. 2. FIG. 4 is a half vertical section of the lower half region of the housing of FIG. 1 taken along line BB in FIG. FIG. 2 is a half longitudinal front view of a preform used for forming the casing of FIG. 1. 6A is a plan view, and FIG. 6B is a cross-sectional plan view taken along line CC in FIG. (A) which shows the example of the conventional square housing is a top view, (b) is a half vertical front view. It is a plane sectional view shown along the EE line of Drawing 8 (b). It is a schematic explanatory drawing for demonstrating the extending | stretching deformation process of the preform inside a metal mold | die. FIG. 9 is a half vertical cross-sectional view of the lower half region of the housing shown along the line DD in FIG. 8A of the housing of FIG. 8. 8A is a plan view, FIG. 8B is a half longitudinal front view, and FIG. 8C is a cross-sectional view taken along line FF in FIG. 8B. FIG.

Hereinafter, an embodiment of a synthetic resin casing of the present invention will be described along examples, with reference to the drawings.
FIGS. 1 to 5 are for explaining one embodiment of a synthetic resin prismatic casing of the present invention or a molding method thereof, FIG. 1 is a perspective view, FIG. 2 is a half longitudinal front view, and FIG. 3 is a plan view, FIG. 3B is a bottom view, FIG. 4 is a plan sectional view taken along line AA in FIG. 2, and FIG. 5 is shown along line BB in FIG. It is a longitudinal cross-section of the lower half area | region of a housing.
FIGS. 6 and 7 show a preform 11 used for forming the casing 1 of the present embodiment, FIG. 6 is a front view in half, FIG. 7A is a plan view, and FIG. b) is a cross-sectional plan view taken along the line CC in FIG.

The housing 1 is formed by biaxial stretch blow molding by a hot parison method made of PET resin, and has a square cylindrical body portion 4 from the upper end of the body portion 4 through the shoulder portion 3. A cylindrical mouth tube portion 2 is erected and has a bottom portion 5 whose lower end is closed by a square bottom wall 6.
This is a transparent, small, and thick rectangular housing with an overall height of 82 mm, a lateral width of 27 mm, an average thickness of the peripheral wall of the body 4 of 3.2 mm, and a thickness of the center of the bottom wall 6 of 4 mm.
A grounding portion 7 is provided along the periphery of the bottom wall 6.

A preform 11 shown in FIGS. 6 and 7 has a cylindrical portion 14 formed on the body portion 4 of the casing 1, and a cylindrical mouth portion 12 is erected from the upper end of the cylindrical portion 14. Moreover, it has the structure which has the bottom part 15 which closed the lower end with the square-shaped bottom wall 16.
Further, as shown in FIGS. 7A and 7B, the cylindrical portion 14 has a square outer cross section on the outer peripheral surface, a circular inner cross section on the inner peripheral surface, and a thick wall at the corner portion 14c. It is trying to become.
The inner peripheral surface of the cylindrical portion 14 is formed so as to extend downward from the cylindrical inner peripheral surface of the mouth portion 12 in consideration of injection moldability.

Next, while comparing with the case 101 formed from the preform 111 having the cylindrical portion 114 of the conventional example described at the beginning with reference to FIGS. Features will be described.
In the plane cross-sectional view of the housing 1 in FIG. 4, the plane cross-sectional shape of the preform 11 shown in FIG. 7B is shown to be overlapped with a two-dot chain line. As can be seen by comparing with FIG. 9 or FIG.
As in the present embodiment, the flat cross-sectional shape of the outer peripheral surface of the peripheral wall of the cylindrical portion 14 of the preform 11 is rectangular, so that the distance L1 between the outer peripheral surface of the cylindrical portion 14 and the panel wall 4p and the square wall 4c. The difference in the distance L2 from the angle can be reduced, and local stretching deformation of the peripheral wall of the preform 11 in the vicinity of the square wall 4c can be suppressed.

As a result, the thinning at the corner wall 104c seen in FIG.
In the case of the present embodiment, a substantially uniform wall thickness distribution could be achieved over the entire circumference of the peripheral wall of the body 4 as shown in the plan sectional view of FIG.
In addition, the square wall 4c of the housing 1 has an arcuate shape due to the effect of increasing the thickness of the corner 14c of the preform 11 by making the inner peripheral surface of the cylindrical portion 14 of the preform 11 circular. The corner wall 4c is thicker than the wall thickness t1 of the panel wall 4p.

  Next, in FIG. 5 in which a longitudinal sectional view in the diagonal direction of the lower half of the casing 1 is shown, the longitudinal sectional shape of the preform 11 shown in FIG. However, the peripheral wall in the vicinity of the bottom wall 16 of the preform 11 is bent and deformed perpendicularly to the bottom wall 6 and the square wall 4c while being stretched and deformed in the vertical direction in addition to the horizontal direction in the direction of the black arrow in the figure. Part 6c is formed.

The casing 1 of this embodiment is molded by the hot parison method, and the preform 11 moves to the blow molding process while maintaining the residual heat of the injection molding. Therefore, the preform 11 is formed with a relatively thick wall. The portions near the corner portions 14c and the corner portions 16c can be maintained at a temperature suitable for stretching, and the peripheral wall including the corner portions 14c and the corner walls 16c can be stretched uniformly.
Then, as shown in FIG. 11 related to the case 101 of the conventional example, the progress of the local stretching deformation as seen in the corner portion 106c is eliminated, and the wall thickness further increases in the vicinity of the corner portion 6c, The corner portion 6c has a shape obtained by chamfering the inner peripheral surface into an arc shape.

  5 shows the shape of the corner portion 6c that connects the bottom wall 6 and the square wall 4c, the corner portion 6c that connects the bottom wall 6 and the lower end of the panel wall 4p is also shown in FIG. Further, the thickness increases in the vicinity of the corner portion 6c, and the inner peripheral surface of the corner portion 6c is rounded in an arc shape.

As mentioned above, although embodiment of this invention and its effect were demonstrated along the Example, embodiment of this invention is not limited to the said Example.
For example, in the above embodiment, a case made of PET resin has been described, but the structure of the present invention is made of polypropylene resin, made of PET-G resin containing 1,4 cyclohexanedimethanol (CHDM) component as a copolymer component, aromatic A biaxially stretched blow-molded rectangular housing made of other resin such as polyolefin resin is also effective.

As described above, the present invention provides a small, thick-walled synthetic resin-resin prismatic casing that exhibits a glass bottle-like high-quality appearance, and is widely used in cosmetic applications. Be expected.

1, 101; housing 2, 102; mouth tube portion 3, 103; shoulder portion 4, 104; barrel portion 4p, 104p: panel wall 4c, 104c; square wall 5, 105; bottom portion 6, 106; 106c; Corner part 7; Grounding part 11, 111; Preform 12, 112; Mouth part 14, 114; Cylindrical part 14c; Corner part 15, 115; Bottom part 16, 116;

Claims (4)

A cylindrical mouth portion (12) is erected at the upper end of the cylindrical portion (14) having a rectangular cross section on the outer peripheral surface of the peripheral wall, and the inner peripheral surface of the cylindrical portion (14) is It is assumed that the inner peripheral surface of the mouth part (12) is formed to extend downward, and is made of a synthetic resin by bottomed cylindrical injection molding in which the lower end of the cylindrical part (14 ) is closed by the bottom wall (16). It is a biaxially stretched blow-molded product by a hot parison method using a preform (11), has a rectangular cylindrical body (4) that is stretched in a similar manner from the cylindrical part (14), cylindrical mouth tube portion (2) standing set via a shoulder (3) on the upper end of the body portion (4), a closed but the bottle with a rectangular bottom wall (6) a lower end, cylinder The wall thickness of the four corner walls (4c) of the peripheral wall of the section (4) is equal to or greater than the wall thickness of the four panel walls (4p) that form the peripheral wall of the trunk section (4) together with the corner wall (4c), In the region from the center of the bottom wall (6) to the lower end of the four corner walls (4c) of the peripheral wall of the body (4), the wall thickness is below the bottom wall (6) and the corner walls (4c). The end portion is configured to increase in the vicinity of the corner portion (6c) that is bent and connected at a substantially right angle, and the inner peripheral surface of the corner portion (6c) is rounded in an arc shape when viewed in a longitudinal section. Synthetic resin square housing. Barrel (4) from the bottom wall (6) average wall thickness of the peripheral wall of the subjected to 2.5mm or more and claims 1 synthetic resin bottle body according. The synthetic resin casing according to claim 1 or 2, which is transparent or translucent. A method for molding a synthetic resin prismatic casing according to any one of claims 1 to 3,
A cylindrical mouth portion (12) is erected at the upper end of the cylindrical portion (14) having a rectangular cross section on the outer peripheral surface of the peripheral wall, and the inner peripheral surface of the cylindrical portion (14) is It is assumed that the inner peripheral surface of the mouth part (12) is formed so as to extend downward, and a bottomed cylindrical synthetic resin preform in which the lower end of the cylindrical part (14 ) is closed by the bottom wall (16) ( 11) injection molding
Then, hot more by parison method biaxial stretch blow molding method, thereby forming said preform (11) rectangular tubular body portion of the cylindrical portion extends formed by a similar shape (4), a rectangular shape The wall thickness of the four corner walls (4c) of the peripheral wall of the body portion (4) forms the peripheral wall of the body portion (4) together with the square wall (4c). The thickness of the panel wall (4p) is equal to or greater than the thickness of the panel wall (4p), and the thickness of the bottom wall (6p) extends from the center of the bottom wall (6) to the lower end of the four corner walls (4c) of the peripheral wall of the body (4). The lower end portion of the wall (6) and the square wall (4c) is configured to increase in the vicinity of the corner portion (6c) that is bent and connected at a substantially right angle, and the inner peripheral surface of the corner portion (6c) is formed in an arc shape when viewed in a longitudinal section. A method for forming a rectangular prismatic body made of synthetic resin, characterized by forming a square shape.

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