JP2010000670A - Preform for molding resin container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a failure in which preforms for molding a resin container with narrow barrel parts get closely contact with each other to make their extraction impossible or difficult when the preforms are stacked up. <P>SOLUTION: Each of the preforms 1(1) and 1(2) has the barrel part 4 which can be inserted into a mouth part 2, and the tip of the barrel part 4 is blocked by a hemispherical bottom part 5. The whole of a hemispherical surface-shaped bottom part outer surface 5a is made a texturing region 6. When the preform 1(2) is inserted into the mouth part 2 of the preform 1(1) to be stacked, the textured bottom part outer surface 5a of the preform 1(2) is brought into contact with the tapered curvature inner surface 3b of the neck part 3 of the preform 1(1). Since the contact part is not in a closely contact state, the preform 1(2) can be easily extracted from the preform 1(1). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin container molding preform used for manufacturing a resin container such as a PET bottle by stretch blow molding or the like, and more specifically, for stretch blow molding having a barrel portion that is slightly thinner than a mouth portion. The present invention relates to a preform improvement technique.

  A container made of a thermoplastic resin such as a PET bottle is manufactured by heating a preform (parison) in the shape of a test tube, which is an injection-molded product, and biaxially stretching in a blow mold. In recent years, there has been a strong demand for thinner and lighter resin containers. Further, various shapes of the resin container are required. In order to respond to these demands, a thinner preform body than the mouth has been used. A preform having this shape is disclosed in Patent Document 1.

As disclosed in Patent Document 1, in the preform having this shape, when the body portion is thick enough to be inserted into the mouth portion, the body portion of another preform is inserted into the mouth portion of the preform. May occur. Since the outer peripheral surface and inner peripheral surface of the preform are smooth surfaces, the inner peripheral surface and outer peripheral surface of both preforms are in close contact with each other and cannot be separated from each other, or cannot be easily pulled out. Problems occur. In Patent Document 1, protrusions are formed on the bottom surface of the preform so as to avoid a close contact state between the preforms.
JP 2007-296720 A

  In the method of forming protrusions on the bottom surface of the preform and avoiding the close contact state between the preforms, it is necessary to appropriately set the size, formation position, and number of protrusions. If the protrusions are too large, there is a risk that the protrusions may interfere with the preform handling work, such as preventing the preform from being conveyed. In addition, if the protrusions are too large, traces of the protrusions may remain in the resin container obtained by biaxial stretch blow molding, and the moldability may be affected, such as the thickness of the protrusion forming part being different from other parts. There may be. Furthermore, if the formation position and the number of the protrusions are not appropriate, the close contact state between the preforms may not be avoided.

  An object of the present invention is to propose a preform for molding a resin container capable of avoiding close contact between the preforms with an extremely simple structure.

In order to solve the above problems, the present invention provides:
A cylindrical mouth part, a neck part of a circular cross section whose thickness is gradually reduced continuously in a coaxial state at the mouth part, and a cylindrical body part of a constant thickness which is continuously coaxially connected to the neck part; In the preform for resin container molding having a bottom portion that seals the tip of the cylindrical body portion, and the body portion has a thickness that can be inserted into the mouth portion,
The bottom portion is provided with a hemispherical bottom outer peripheral surface that is smoothly continuous with the end of the circular outer peripheral surface of the trunk portion and that is centered on the preform center axis.
At least a part of the bottom outer peripheral surface is a rough surface region subjected to rough surface processing such as embossing,
A circular contact line between the bottom outer peripheral surface and the tapered inner peripheral surface is formed when the bottom outer peripheral surface is pressed coaxially from the mouth side to the tapered inner peripheral surface of the neck. As described above, the rough surface area is set.

  In the preform for molding a resin container of the present invention, a rough surface area is formed on the outer peripheral surface of the bottom, and when this preform is inserted from the mouth of another preform of the same shape, the rough surface area It is avoided that both preforms fall into close contact. The rough surface region can be easily formed by applying a texture or the like to the outer peripheral surface of the bottom. Moreover, it can form simply by making the shaping | molding surface of the shaping | molding die used for injection molding of a preform into a rough surface. Furthermore, a rough surface does not remain in a resin container obtained by biaxially stretching blow-molding a preform. Furthermore, it is only necessary to set the rough surface area wide so that the rough surface area is always located at the contact part of both preforms. There is no need to do.

  In addition, the preforms for molding a resin container having a narrow body portion may be stored in a stacked state, and in such a case, the preforms are generally stacked in a coaxial state. Therefore, if the region including the contact portion (circular contact line) between the preforms when stacked in the coaxial state is a rough surface region, the contact state between the preforms can be reliably avoided.

  Next, in the preform for molding a resin container according to the present invention, the rough surface area is formed on the entire outer surface of the bottom portion.

  Next, in the preform for molding a resin container according to the present invention, the region including the circular contact line on the tapered inner peripheral surface of the neck is subjected to rough surface processing such as embossing. . By doing so, since the rough surfaces come into contact with each other, the contact area between them can be greatly reduced, and it can be reliably avoided that the preforms are brought into close contact with each other and cannot be pulled out or are difficult to pull out.

On the other hand, in the preform for molding a resin container of the present invention,
Take a cross section including the preform center axis,
Draw a tangent to the contour curve so that it passes through a point that intersects the circular contact line on the contour curve defining the bottom outer peripheral surface,
If the inclination angle of the tangent to the preform center axis is α,
The curved shape of the bottom outer peripheral surface and the curved shape of the tapered inner peripheral surface of the neck are set so that the inclination angle α is 45 ° or more.

  The smaller the inclination angle α, the more easily the preform falls into a state where it cannot be pulled out or is difficult to pull out. When the angle α is set to 45 ° or more, the bottom of the preform fits into the tapered circular inner peripheral surface of the neck of another preform, and the possibility that it cannot be pulled out or is difficult to pull out is reduced.

  In the preform for molding a resin container according to the present invention, a rough surface region is formed on the outer peripheral surface of the bottom portion by a texture process or the like. Since the rough surface region is formed on the surface where the preforms are in contact with each other, it can be avoided that the preforms are brought into close contact with each other and cannot be separated or separated.

  Hereinafter, embodiments of a preform for molding a resin container to which the present invention is applied will be described with reference to the drawings.

  1A and 1B are a side view and a longitudinal sectional view showing a preform for molding a resin container according to the present embodiment. A preform 1 for molding a resin container is an injection-molded product of a thermoplastic resin such as PET, and has a cylindrical mouth portion 2 and a circular cross section in which the thickness is gradually reduced continuously in a coaxial state to the mouth portion 2. , A cylindrical body 4 having a constant thickness that is concentrically connected to the neck 3, and a bottom 5 that seals the tip of the cylindrical body 4. . The body 4 has a thickness that can be inserted into the mouth 2, and the outer diameter of the body 4 is slightly smaller than the inner diameter of the mouth 2.

  The mouth portion 2 is a cylinder having a constant thickness, and a screw portion 2a is formed on the circular outer peripheral surface thereof, and a large-diameter support ring 2b is formed on the neck portion 3 side. The neck portion 3 also has a certain thickness, and is defined by a tapered curved outer peripheral surface 3a and a tapered curved inner peripheral surface 3b that are curved toward the preform center axis L from the mouth portion 2 toward the trunk portion 4. Yes. The body portion 4 has a constant thickness and is defined by a circular outer peripheral surface 4a having a constant outer diameter and a circular inner peripheral surface 4b having a constant inner diameter.

  The bottom portion 5 is also substantially the same thickness as the body portion 4, and has a hemispherical bottom outer peripheral surface 5 a that is smoothly continuous with the end of the circular outer peripheral surface 4 a of the body portion 4, and a circular inner peripheral surface of the body portion 4. 4b is defined by a hemispherical curved inner peripheral surface 5b smoothly continuing to the end of 4b. Here, as shown in FIG. 1A, the bottom outer peripheral surface 5a of the bottom 5 is roughened as a whole. The bottom outer peripheral surface 5a of this example is a textured region 6 that has been textured. You may make it give well-known rough surface processing other than embossing.

  The resin container molding preform 1 is biaxially stretched and blow molded in a blow mold (not shown), and becomes, for example, a resin container 10 having a shape indicated by an imaginary line in FIG. The bottom outer peripheral surface 5a that is a textured surface is a portion that becomes the bottom surface of the resin container 10, and the textured surface is eliminated by biaxial stretch blow molding, and a smooth bottom surface is formed.

  FIG. 2 is an explanatory view showing a case where the preform 1 for molding a resin container is stacked in a coaxial state. From the opening 2c of the mouth part 2 of one resin container molding preform 1 (1), the other resin container molding preform 1 (2) is inserted coaxially from the bottom part 5 side of the body part 4. Yes.

  The entire surface of the bottom outer peripheral surface 5a of the resin container molding preform 1 (2) is a textured surface, and this bottom outer peripheral surface 5a is the tapered curved inner periphery of the neck 3 of the resin container molding preform 1 (1). It is pressed against the surface 3b in a coaxial state. In this state, the bottom outer peripheral surface 5a is in line contact with the tapered curved inner peripheral surface 3b along the circular contact line C. When both contact surfaces are smooth surfaces, they are in close contact with each other, and the inserted resin container molding preform 1 (2) may be unable to be pulled out or fall into a difficult state. In this example, since one contact surface of both the preforms is a textured surface, the contact area is small and air can be circulated through the contact portion. Therefore, it is possible to avoid the resin container molding preform from being pulled out or falling into a difficult state.

  FIG. 3A is an explanatory view showing another example of the embossed region (rough surface region) of the bottom outer peripheral surface 5a. The resin container molding preform is generally stacked coaxially as shown in FIG. Therefore, the textured region (rough surface region) may be formed on the bottom outer peripheral surface 5a including the circular contact line C where the preforms are in contact with each other. In the resin container molding pull form 1A shown in FIG. 3 (A), a textured region 6 formed in an annular shape with a constant width around the preform center axis L is formed.

  FIG. 3B is an explanatory diagram showing another example of the formation position of the embossed region. In the resin-molding preform 1B shown in this figure, instead of forming the embossed region 6 on the bottom outer peripheral surface 5a, a ring-shaped region is formed on the tapered curved inner peripheral surface 3b of the neck portion 3 with which the bottom outer peripheral surface 5a contacts. Is formed. Of course, you may form in the whole surface of the taper-shaped curved inner peripheral surface 3b. Further, the textured region 6 may be formed on both the bottom outer peripheral surface 5a and the tapered curved inner peripheral surface 3b.

  Next, referring to FIG. 4, when viewed in a cross section including the central axis L of the preform 1 for molding a resin container, a circular contact line C on a contour curve 5L defining the bottom outer peripheral surface 5a. A tangent line T is drawn on the contour curve 5L so as to pass through a point P intersecting with, and an inclination angle of the tangent line T with respect to the preform center axis L is α. The smaller the inclination angle α, the more easily the preform cannot be pulled out or is difficult to pull out when the preform 1 is stacked. Therefore, it is desirable to set the curved surface shape of the bottom outer peripheral surface 5a and the curved shape of the tapered curved inner peripheral surface 3b of the neck portion 3 so that the inclination angle α is 45 ° or more.

It is the side view and longitudinal cross-sectional view of the preform for resin container shaping | molding to which this invention is applied. It is explanatory drawing which shows the state which stacked the preform for resin container shaping | molding of FIG. 1 coaxially. It is explanatory drawing which shows the formation position of an embossing area | region. It is explanatory drawing which shows the stack state of the preform for resin container shaping | molding of FIG.

Explanation of symbols

1, 1 (1), 1 (2), 1A, 1B Resin container molding preform 2 Port 2a Screw 2b Support ring 2c Opening 3 Neck 3a Tapered curved outer peripheral surface 3b Tapered curved inner peripheral surface 4 Body 4a Circular outer peripheral surface 4b Circular inner peripheral surface 5 Bottom 5a Bottom outer peripheral surface 5b Curved inner peripheral surface 6 Wrinkle processing region (rough surface processing region)
10 Resin container L Preform center axis C Circular contact line 5L Contour curve P of outer peripheral surface of bottom portion Contact point T Tangent line α Inclination angle

Claims (4)

A cylindrical mouth portion (2), a neck portion (3) having a circular section whose thickness is gradually reduced continuously in a coaxial state with the mouth portion (2), and a neck portion (3) that is coaxial with the neck portion (3). A cylindrical body portion (4) having a constant thickness and a bottom portion (5) sealing the tip of the cylindrical body portion (4), wherein the body portion (4) In the resin container molding preform (1) having a thickness that can be inserted into the part (2),
The bottom portion (5) is smoothly continuous with the end of the circular outer peripheral surface (4a) of the trunk portion (4) and has a hemispherical bottom outer peripheral surface (5a) centered on the preform center axis (L). )
At least a part of the bottom outer peripheral surface (5a) is a rough surface region (6) subjected to rough surface processing such as embossing,
These bottom outer peripheral surfaces (5a) are formed when the bottom outer peripheral surface (5a) is pressed coaxially from the mouth (2) side to the tapered inner peripheral surface (3b) of the neck (3). ) And the tapered inner peripheral surface (3b), the rough surface region (6) is formed so as to include a circular contact line (C), and the resin container molding preform (1) . In the preform (1) for molding a resin container according to claim 1,
The preform (1) for molding a resin container, wherein the rough surface region (6) is formed on the entire surface of the bottom outer peripheral surface (5a). In the preform (1) for molding a resin container according to claim 1 or 2,
The region including the circular contact line (C) in the tapered inner peripheral surface (3b) of the neck (3) is subjected to rough surface processing such as embossing. Reform (1). In the preform (1) for molding a resin container according to any one of claims 1 to 3,
Take a cross section including the preform center axis (L),
A tangent line (T) is drawn to the contour curve (5L) so as to pass through a point (P) intersecting the circular contact line (C) on the contour curve (5L) defining the bottom outer peripheral surface (5a). ,
When the inclination angle of the tangent line (T) with respect to the preform center axis (L) is α,
The curved shape of the bottom outer peripheral surface (5a) and the curved inner peripheral surface (3b) of the neck (3) are set so that the inclination angle α is 45 ° or more. Resin container molding preform (1).

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