Two-layer preform manufacturing apparatus and two-layer preform manufacturing method

Abstract

The purpose of the present invention is to provide: an apparatus for producing a two-layer preform from which a two-layer delamination container is able to be easily produced by a hot parison blow molding method; a method for producing a two-layer preform; and a resin molded article.　An apparatus 100 for producing a two-layer preform 1, which is composed of a preform 2 for an inner layer and a preform 3 for an outer layer, according to the present invention is provided with a cavity mold 21 for an outer layer for injection molding the preform 3 for an outer layer; and the bottom surface of the cavity mold 21 for an outer layer is provided with a projection 24 for separating the preform 2 for an inner layer from the bottom surface, said preform 2 for an inner layer being arranged within the cavity mold 21 for an outer layer.

Description

[Technical Field]

[0001] The present invention relates to a manufacturing apparatus for a resin molded product having a two-layer structure in which an inner layer bottle is peelable from within an outer layer bottle, a manufacturing method for a resin molded product, corresponding preforms, and a resin molded product. [Background technology]

[0002] Conventionally, there have been known resin molded products having a two-layer structure in which an inner inner-layer bottle can be peeled from an outer outer-layer bottle, a manufacturing apparatus for the resin molded product, a manufacturing method for the resin molded product, and corresponding preforms. A peelable container, which is a resin molded product manufactured by this type of manufacturing apparatus, is configured so that two bottles, each having a body and a bottom, have an inner and outer two-layer structure, and a discharge plug such as a pump or a check valve is fixed to the neck portion (see, for example, Patent Documents 1 to 3).

[0003] Examples of peelable containers include airless pump containers used for cosmetics and squeeze containers used for soy sauce, eye drops, and the like. Peelable containers are designed so that the inner bottle is sealed to prevent outside air from entering, while collapsing to reduce its volume as the contents are poured out. Therefore, the inner bottle is peeled off from the outer bottle by allowing outside air to flow between the inner and outer bottles through a vent or the like provided in the outer bottle. As a result, the peelable container is sealed to prevent deterioration of the contents of the inner bottle, and also makes it possible to use up the contents of the inner bottle by collapsing the inner bottle.

[0004] Currently, most peelable containers are manufactured by extrusion blow molding. Some peelable containers are manufactured by cold parison blow molding, which uses a two-layer interlocking preform formed by simply interlocking and stacking an inner layer preform and an outer layer preform manufactured in separate devices or locations, or by hot parison blow molding, which uses one of the inner layer preform and the outer layer preform as an insert material and injection molds the other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-62146 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-82916 [Patent Document 3] Special Publication No. 5267901 Summary of the Invention [Problem to be solved by the invention]

[0006] However, among the above-mentioned conventional manufacturing devices, no device has been proposed that can produce two-layer peelable containers in a single operation by injection molding a two-layer preform using a single hot parison blow molding machine. The reasons for this include: (1) the inner layer preform and the outer layer preform tend to separate during blow molding; (2) the inner layer bottle, which has been reduced in volume and shrunk, tends to separate (easily fall out) from the outer layer bottle when the contents are consumed; and (3) it is difficult to form an air hole for peeling the inner layer bottle from the outer layer bottle. For this reason, peelable containers are generally produced using conventional extrusion blow molding, even though stretch blow molding, in which a preform is stretched longitudinally with a stretch rod and then expanded with compressed air, can improve the appearance, dimensional accuracy, and physical properties of peelable containers and reduce environmental impact by reducing waste material. Furthermore, peelable containers produced by extrusion blow molding generally have poor dimensional accuracy and appearance quality, such as in the neck portion. In peel-off containers such as squeeze containers and airless pump containers, airtightness between the neck of the inner bottle and the extraction stopper is important from the viewpoint of preventing deterioration of the contents and reducing the amount remaining. However, peel-off containers made by extrusion blow molding, which have poor dimensional accuracy in the neck and other areas, may not be able to achieve sufficient airtightness. This can lead to problems such as the contents easily deteriorating in squeeze containers and the contents not being fully consumed in airless pump containers.

[0007] Furthermore, when producing peelable containers using a cold parison stretch blow molding method, two preforms with different shapes corresponding to the inner layer preform and the outer layer preform are usually required. This requires the inner layer preform and the outer layer preform to be produced in advance using an injection molding machine separate from the blow molding machine, which increases manufacturing costs and reduces productivity. However, for the reasons mentioned above, it has been difficult to mold the material into a peelable container using only a hot parison blow molding device that combines an injection molding machine and a blow molding machine, without using a separate injection molding machine.

[0008] The present invention aims to provide a resin molded product manufacturing apparatus, a resin molded product manufacturing method, a preform, and a resin molded product that can easily manufacture two-layer peelable containers using a hot parison blow molding method. [Means for solving the problem]

[0009] The present invention is characterized in that, in an apparatus for manufacturing a two-layer preform consisting of an inner layer preform and an outer layer preform, it is provided with an outer layer cavity mold for injection molding the outer layer preform, and the bottom surface of the outer layer cavity mold is provided with a protrusion for separating the inner layer preform placed in the outer layer cavity mold from the bottom surface.

[0010] In this case, a neck mold for molding the neck portion of the preform may be provided, and the shape of the mold surface of the neck mold may be different when injection molding the inner layer preform and when injection molding the outer layer preform. A contact surface that narrows around the axis of the inner layer preform and contacts the outer layer preform may be formed between the neck portion and the body portion of the inner layer preform.

[0011] The present invention also provides a method for manufacturing a two-layer preform consisting of an inner layer preform and an outer layer preform, which includes the steps of injection molding the inner layer preform, placing the injection-molded inner layer preform in an outer layer cavity mold for injection molding the outer layer preform, and injection molding the outer layer preform onto the outer surface of the inner layer preform, wherein the bottom surface of the outer layer cavity mold is provided with a protrusion for separating the inner layer preform placed in the outer layer cavity mold from the bottom surface.

[0012] In this case, the step of injection molding the inner layer preform may further include a step of changing the shape of a mold surface of a neck mold that molds a neck portion of the preform before the step of placing the inner layer preform. The step of injection molding the inner layer preform may include forming an abutment surface on the inner layer preform that narrows around the axis of the inner layer preform between the neck portion and the body portion of the inner layer preform and abuts against the outer layer preform.

[0013] Furthermore, the present invention is characterized in that the resin molded product has a two-layer structure consisting of an inner layer bottle molded from an inner layer preform and an outer layer bottle molded from an outer layer preform, and a through hole is formed in the bottom of the outer layer bottle.

[0014] In this case, a contact surface may be formed between the neck and body of the inner layer bottle, narrowing around the axis of the inner layer bottle and contacting the outer layer bottle. [Effects of the Invention]

[0015] The present invention provides a resin molded product manufacturing apparatus, a resin molded product manufacturing method, a preform, and a resin molded product that can easily manufacture a two-layer peelable container using a hot parison blow molding method. [Brief explanation of the drawings]

[0016] [Figure 1] 1 shows a schematic diagram of a blow molding apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2a shows a cross-sectional view of an inner layer cavity mold being injection molded, FIG. 2b shows a cross-sectional view of an inner layer preform placed in an outer layer cavity mold, and FIG. 2c shows a cross-sectional view of the preform. [Figure 3] A cross-sectional view of the lower part of the vessel is shown. [Figure 4]Figure 4(a) shows a cross-sectional view when injection molding an inner layer preform, Figure 4(b) shows a cross-sectional view when injection molding an outer layer preform, and Figure 4(c) shows a cross-sectional view when blow molding. [Figure 5] Figure 5(a) shows a cross-sectional view when injection molding an inner layer preform, Figure 5(b) shows a cross-sectional view when injection molding an outer layer preform, and Figure 5(c) shows a cross-sectional view when blow molding. [Figure 6] FIG. 6(a) shows the neck mold used when injection molding the inner layer preform, and FIG. 6(b) shows the neck mold used when injection molding and blow molding the outer layer preform. [Figure 7] FIG. 7(a) shows the neck mold used when injection molding the inner layer preform, and FIG. 7(b) shows the neck mold used when injection molding and blow molding the outer layer preform. [Figure 8] Figure 8(a) shows a cross-sectional view when injection molding an inner layer preform, Figure 8(b) shows a cross-sectional view when injection molding an outer layer preform, and Figure 8(c) shows a cross-sectional view when blow molding. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Fig. 1 shows a schematic diagram of a manufacturing apparatus according to one embodiment of the present invention. Fig. 2(a) shows a cross-sectional view of an inner layer preform being injection molded in an inner layer cavity mold, Fig. 2(b) shows a cross-sectional view of an inner layer preform placed in an outer layer cavity mold, and Fig. 2(c) shows a cross-sectional view of the preform. Fig. 3 shows a cross-sectional view of the lower part of the container.

[0018] As shown in FIG. 1, the manufacturing apparatus (blow molding apparatus) 100 includes a first injection molding section 10, a second injection molding section 20, a first temperature adjustment section 30a, a second temperature adjustment section 30b, a blow molding section 40, and a removal section 50, and is an apparatus for injection-molding a preform 1 (see FIG. 2) and then blow-molding it to manufacture a container 1a. Note that the first temperature adjustment section 30a may be omitted. In this case, the manufacturing apparatus 100 includes the first injection molding section 10, the second injection molding section 20, the temperature adjustment section 30b, the blow molding section 40, and the removal section 50.

[0019] The first injection molding section 10, the first temperature adjustment section 30a, the second injection molding section 20, the second temperature adjustment section 30b, the blow molding section 40, and the removal section 50 are arranged in this order in an array that forms the six sides of a regular hexagon when viewed from above. Above these, a turntable 70 is provided on which neck dies 60 (see FIG. 4(a)) that hold the neck portions 2a (see FIG. 4(a)) of the preforms 1 molded in the injection molding section 10 are mounted. Six sets of neck dies 60 are arranged on this turntable 70 in an array that forms the six sides of a regular hexagon when viewed from above. As a result, the turntable 70 rotates counterclockwise around a vertical axis by a predetermined angle (for example, 60 degrees) on the first injection molding section 10, the first temperature adjustment section 30a, the second injection molding section 20, the second temperature adjustment section 30b, the blow molding section 40, and the removal section 50, and each of the six sets of neck molds 60 moves in order through the first injection molding section 10, the first temperature adjustment section 30a, the second injection molding section 20, the second temperature adjustment section 30b, the blow molding section 40, and the removal section 50, and each process is performed on the preform 1 held in the neck mold 60. Note that if the first temperature adjustment section 30a is not present, the first injection molding section 10, the second injection molding section 20, the second temperature adjustment section 30b, the blow molding section 40, and the removal section 50 are arranged in this order in an array that forms five sides of a regular pentagon when viewed from above. When the turntable 70 rotates by a predetermined angle (for example, 72 degrees), each of the five neck dies 60 moves to each molding section in turn, and each process is carried out on the preform 1 held in the neck die 60.

[0020] The preform 1 used in the manufacturing apparatus 100 according to this embodiment is a two-layer preform in which an outer layer preform 3 is formed so as to be in close contact with the outside of an inner layer preform 2. The inner layer preform 2 is molded from a first synthetic resin material, and the outer layer preform 3 is molded from a second synthetic resin material. It is desirable that the first synthetic resin material and the second synthetic resin material are different. The first synthetic resin material can be a synthetic resin material with excellent physical properties such as moisture barrier properties, gas barrier properties, and chemical resistance (e.g., polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), polyamide nylon (PA, nylon MXD6), cyclic olefin polymer (COC, COP), polyphenylsulfone (PPSU), polyethersulfone (PES), etc.), and the second synthetic resin material can be a synthetic resin material with excellent physical properties such as moldability, toughness, creep resistance, and transparency (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polyacrylonitrile (PAN)). It is desirable, although not essential, that the melting point of the first synthetic resin material be higher than that of the second synthetic resin material.

[0021] As shown in Figure 2(a), the first injection molding section 10 is equipped with an injection core mold 11a for injection molding the inner layer preform 2, an inner layer cavity mold 11b, and a first injection device 12, and is configured to injection mold the inner layer preform 2.

[0022] When injection molding the inner layer preform 2, the injection core mold 11a, the inner layer cavity mold 11b, and the neck mold 60 are combined to define a space corresponding to the inner layer preform 2. At this time, the injection core mold 11a molds the inner surface shapes of the neck portion 2a, body portion 2b, and bottom portion 2x of the inner layer preform 2, the inner layer cavity mold 11 molds the outer surface shapes of the body portion 2b and bottom portion 2x, and the neck mold 60 molds the outer surface shape of the neck portion 2a.

[0023] The first injection molding section 10 heats and melts a first synthetic resin material such as PP at a high temperature, injects the melted first synthetic resin material into between the injection core mold 11a, the inner layer cavity mold 11b, and the neck mold 60 using the first injection device 12, and then cools and solidifies the injected material to a temperature lower than the melting point to form the inner layer preform 2.

[0024] The inner layer preform 2, which has solidified to a certain extent after being injection molded in the first injection molding section 10, is lifted upward together with the turntable 70 while still held in the neck mold 60 and pulled out of the inner layer cavity mold 11, and is transported to the first temperature adjustment section 30a as the turntable 70 rotates counterclockwise by 60 degrees.

[0025] As shown in FIG. 1, the first temperature adjustment unit 30a is located next to the first injection molding unit 10 and includes a temperature-controlled core mold and a temperature-controlled cavity mold. The temperature-controlled core mold and the temperature-controlled cavity mold are cooled by a refrigerant flowing through channels formed inside them. The temperature of the inner layer preform 2 transported to the first temperature adjustment unit 30a is too high to injection mold the outer layer preform 3 around the inner layer preform 2. Therefore, the inner layer preform 2 is sandwiched between the cooled temperature-controlled core mold and the temperature-controlled cavity mold and further cooled (relatively cooled compared to immediately after molding in the first injection molding unit 10) to a temperature suitable for further injection molding. Note that an air inlet / outlet rod may be used instead of the temperature-controlled core mold. In this case, the inner layer preform 2 is cooled (temperature-controlled) by air circulating from the inside and by contact with the temperature-controlled cavity mold from the outside.

[0026] The inner layer preform 2, whose temperature has been adjusted in the first temperature adjustment section 30a, is lifted upward together with the turntable 70 while still held in the neck mold 60 and pulled out of the temperature-controlled cavity mold. As shown in Figure 1, the turntable 70 then rotates another 60 degrees counterclockwise and is transported to the second injection molding section 20.

[0027] As shown in Figure 2(b), the second injection molding section 20 is provided with an injection core mold 21a for injection molding the outer layer preform 3, an outer layer cavity mold 21b, and a second injection device 22 (see Figure 1), and is provided to injection mold the outer layer preform 3. The outer layer preform 3 does not have a neck portion, but only a body portion.

[0028] When injection molding the outer layer preform 3, the inner layer preform 2 molded in the first injection molding section 10 is placed inside the outer layer cavity mold 21b, the injection core mold 21a is inserted into the inner surface of the inner layer preform 2, and the inner layer preform 2, outer layer cavity mold 21b, and neck mold 60 are combined to define a space corresponding to the outer layer preform 3. At this time, the outer surface of the inner layer preform 2 molds the inner surface shape of the body portion 3b and bottom portion 3x (see FIG. 2(c)) of the outer layer preform 3, the outer layer cavity mold 21b molds the outer surface shapes of the body portion 3b and bottom portion 3x, and the neck mold 60 molds the outer surface shape at the upper end of the body portion 3b.

[0029] The second injection molding section 20 heats and melts a second synthetic resin material such as PET at a high temperature, injects the melted material into the space between the inner layer preform 2 and the outer layer cavity mold 21b and neck mold 60 using the second injection device 22, and then cools and solidifies the injected material to a temperature lower than the melting point to form the outer layer preform 3.

[0030] When the preform solidifies to a certain extent after being injection molded in the second injection molding section 20, the outer layer preform 3 adheres tightly to the outside of the inner layer preform 2, forming a two-layer preform 1, as shown in FIG. 2(c).

[0031] The preform 1 is lifted upward together with the turntable 70 while being held by the neck mold 60, and is pulled out of the outer layer cavity mold 21, and is transported to the second temperature adjustment section 30b as the turntable 70 rotates counterclockwise by 60 degrees.

[0032] As shown in FIG. 1, the second temperature adjustment unit 30b is disposed adjacent to the second injection molding unit 20 and includes a temperature-controlled core mold and a temperature-controlled cavity mold. The temperature-controlled core mold and the temperature-controlled cavity mold are cooled by a refrigerant flowing through channels formed therein. The preform 1 transported to the second temperature adjustment unit 30b is too hot for blow molding, so it is sandwiched between the cooled temperature-controlled core mold and the temperature-controlled cavity mold and further cooled (relatively cooled compared to immediately after molding in the second injection molding unit 20) to a temperature suitable for blow molding. Note that an air inlet / outlet rod may be used instead of the temperature-controlled core mold. In this case, the preform 1 is cooled (temperature-controlled) by air circulating from the inside and by contact with the temperature-controlled cavity mold from the outside.

[0033] The preform 1, whose temperature has been adjusted in the second temperature adjustment section 30b, is lifted upward together with the turntable 70 while still held in the neck mold 60 and pulled out of the temperature-controlled cavity mold. As shown in Figure 1, the turntable 70 then rotates another 60 degrees counterclockwise and the preform is transported to the blow molding section 40.

[0034] The blow molding section 40 is disposed next to the second temperature adjusting section 30b, and includes a blow cavity mold 41 (see FIG. 4(c)) and an air blowing member (not shown).

[0035] The blow cavity mold 41 has a mold surface formed on the inside thereof that corresponds to the shape of the container 1a, and has a mold surface that is significantly larger than that of the temperature control cavity mold of the second temperature control unit 30b. The air blowing member is provided to supply and exhaust air into the preform 1 inserted into the blow cavity mold 41. The air blowing member is composed of an air inlet / outlet member (blow core) that abuts airtightly against the neck portion 2a of the preform 1 and supplies and exhausts high-pressure air at a predetermined pressure (for example, 0.5 MPa or more and 3.5 MPa or less) into the body portion of the preform 1, and an extension rod that abuts against the inner bottom surface of the preform 1 and moves up and down.

[0036] The preform 1 transported to the blow molding section 40 is lowered together with the turntable 70 and inserted into the blow cavity mold 41 (see FIG. 4(c)), and the stretch rod of the air blowing member is inserted into the inner layer preform 2. At this time, the air inlet / outlet member is connected to the opening of the neck portion 2a of the preform 1 (more specifically, the inner layer preform 2), and the tip of the stretch rod advances to the bottom of the blow cavity mold 41 while hitting the bottom of the preform 1 (more specifically, the inner layer preform 2), causing the preform 1 to be stretched toward the bottom of the blow cavity mold 41 (the preform 1 is stretched vertically). Furthermore, when the air inlet / outlet member blows air (high-pressure air) into the preform 1 (more specifically, the inner layer preform 2), the body of the preform 1 (more specifically, the outer layer preform 3) is inflated (the body of the preform 1 is stretched in the outer diameter direction) until the entire outer surface of the body of the preform 1 (more specifically, the outer layer preform 3) is pressed tightly against the mold surface of the blow cavity mold 41, and the container 1a is molded. After molding is complete, air is exhausted from the container 1a via the air inlet / outlet member, and the air blowing member (the air inlet / outlet member and the stretching rod) moves above the neck mold 60 and away from the container 1a.

[0037] The container 1a blown in the blow molding section 40 is lifted upward together with the turntable 70 while being held by the neck mold 60 and pulled out from the blow cavity mold 41, and the turntable 70 further rotates counterclockwise by 60 degrees to transport it to the removal section 50.

[0038] The removal section 50 is disposed between the blow molding section 40 and the injection molding section 10. In the removal section 50, the neck mold 60 opens and no longer holds the container 1a, causing the container 1a to drop, and the container 1a is removed from the manufacturing apparatus 100. The manufacturing apparatus 100 molds the preform 1 and the container 1a according to the above-described process flow.

[0039] The injection molding process and the blow molding process will now be described in more detail. As shown in FIG. 2(a), the first injection molding section 10 first injection-moldes an inner layer resin (first synthetic resin material) such as PP into an inner layer cavity mold 11, which is part of the inner layer injection mold, to injection-mold an inner layer preform 2. Next, as shown in FIG. 2(b), the second injection molding section 20 places the injection-molded inner layer preform 2 in an outer layer cavity mold 21, which is part of the outer layer injection mold. Next, with the inner layer preform 2 placed in the outer layer cavity mold 21, an outer layer resin (second synthetic resin material) such as PET is injected between the outer layer cavity mold 21 and the inner layer preform 2 through a gate 23 formed in the center of the bottom surface, thereby injection-molding an outer layer preform 3.

[0040] The outer layer cavity mold 21 has protrusions 24 of a predetermined shape (for example, a cylindrical shape or an elongated convex rib shape) on its bottom surface (cavity surface) corresponding to the bottom 3x of the outer layer preform 3. As a result, the inner layer preform 2 placed in the outer layer cavity mold 21 is brought into close contact with the end surfaces of the protrusions 24, and a gap the width of which is the height of the protrusions 24 is formed between the inner layer preform 2 and the bottom surface of the outer layer cavity mold 21. This gap is filled with an outer layer resin such as PET, which is the material for the outer layer preform 3, and therefore, the injection-molded outer layer preform 3 has through holes (or thin film portions for through holes) 3a that function as vents formed in the bottom 3d, as shown in FIG. 2(c). In the preform 1, a through hole 3a is formed in the outer layer preform 3, and a through hole 3a' of approximately the same shape as the through hole 3a is formed in the bottom of the container 1a, allowing outside air to flow through the through hole 3a' between the inner layer bottle 2' (see Figure 4(c)) and the outer layer bottle 3' (see Figure 4(c)).

[0041] Figure 4(a) shows a cross-sectional view when injection molding an inner layer preform, Figure 4(b) shows a cross-sectional view when injection molding an outer layer preform, and Figure 4(c) shows a cross-sectional view when blow molding.

[0042] The neck mold 60 of this embodiment is designed so that the shape of the mold surface formed on the inner peripheral surface changes when the inner layer preform is injection molded and when the outer layer preform is injection molded and blow molded.

[0043] The neck mold 60 used when injection molding the inner layer preform 2 is configured by abutting a neck mold main body 61 provided on a rotating disk 70 and an inner layer neck mold 62 provided on an inner layer cavity mold 11, as shown in Figure 4(a).

[0044] The neck mold body 61 is a mold for shaping most of the neck portion 2a of the inner layer preform 2, and the mold surface is formed to form a cylindrical portion and a threaded portion formed on the surface of this cylindrical portion.

[0045] The inner layer neck mold 62 is provided to form the lower region of the neck portion 2a, i.e., the region between the region where the neck mold body 61 forms the neck portion 2a and the body portion 2b of the inner layer preform 2. The inner layer neck mold 62 has a cylindrical inner peripheral surface, and its lower end protrudes along this inner peripheral surface toward the axis C over the entire circumference. As a result, the lower end of the neck portion 2a of the inner layer preform 2 becomes thinner toward the axis C over the entire circumference, and the diameter becomes smaller, forming a first abutment surface (first recess) 2c. The inner layer neck mold 62 has a lower end surface that extends perpendicular to the axis C of the preform 1, and this lower end surface abuts against the inner layer cavity mold 11 to form a mold surface that shapes the outer surface of the inner layer preform 2. At this time, a second contact surface (second recess) 2d is also formed on the outer peripheral surface of the body portion 2b of the inner layer preform 2 due to the mold surface shape of the inner layer cavity mold 11. The first contact surface (first recess) 2c and the second contact surface (second recess) 2d are stepped (concave toward the axis C). These function as support parts that hold the inner layer preform 2 or inner layer bottle 2' to the outer layer preform 3 or outer layer bottle 3' during blow molding of the preform 1 or use of the container 1a. The inner layer neck mold 63 is connected to the inner layer cavity mold 11 via a guide member 62a so as to be slidable obliquely. The guide member 62a has a guide rod and a compression spring, which are inserted into recesses (sinkholes) of the inner layer neck mold 62 and the inner layer cavity mold 11. With the above-described configuration, the outer layer neck mold 63 is moved obliquely upward by the force of the compression spring when the mold is opened, and is moved obliquely downward by being pushed by the neck mold body 61 when the mold is closed.

[0046] The neck mold 60 used when injection molding the outer layer preform 3 is configured by abutting a neck mold main body 61 provided on the turntable 70 and an outer layer neck mold 63 provided on the outer layer cavity mold 21, as shown in Figure 4(b).

[0047] The outer layer neck mold 63 has a cylindrical inner circumferential surface that forms the lower region of the neck portion 2a of the inner layer preform 2. The lower surface of the outer layer neck mold 63 is formed so that the portion close to the axis C of the preform 1 is one step thinner than the other portions. Specifically, the outer layer neck mold 63 is formed so that the portion that abuts against the neck portion 2a of the inner layer preform 2 and the portion nearby are located on the same plane as the first abutment surface (first recess) 2c of the inner layer preform 2. Meanwhile, the outer layer neck mold 63 is thicker at a position away from the inner layer preform 2, and at the position where it changes from thin to thick, a step surface 23a that extends along the axis C of the preform 1 and faces the inner layer preform 2 is formed on the outer layer neck mold 63 as the cylindrical inner circumferential surface. The outer layer neck mold 63 is formed so that its lower end surface extends perpendicularly to the axis C of the preform 1, and abuts against the outer layer cavity mold 21 to form a mold surface that shapes the outer peripheral surface of the outer layer preform 3. At this time, the outer layer cavity mold 21 has a mold surface that forms the outer peripheral surface of the outer layer preform 3 formed so that it is flush with the step surface 63a. As a result, a convex upper end outer peripheral surface 3c is formed at the upper end of the outer layer preform 3. Furthermore, the outer layer neck mold 63 is arranged so that it can slide obliquely relative to the outer layer cavity mold 21 by means of the guide member 63b.

[0048] During blow molding, as shown in Figure 4(c), the upper end outer peripheral surface 3c formed around the upper end of the outer layer preform 3 may be brought into contact with the blow cavity mold 41. As a result, the upper end outer peripheral surface 3c is in contact with the step surface 41a and is therefore prevented from expanding in a direction away from the axis C. As a result, the air that flows in through the neck portion 2a during blow molding cannot push the outer layer preform 3 in a direction away from the axis C, and the first contact surface 2c of the inner layer preform 2 and the upper end surface 3e of the outer layer preform 3 are maintained in contact in the direction of the axis C, so the inner layer preform 2 is held so as not to move along the axis C toward the bottom relative to the outer layer preform 3.

[0049] The procedure for injection molding the two-layer preform 1 and blow molding it into a container 1a will be described below.

[0050] When manufacturing the container 1a, first, the inner layer preform 2 is injection molded in the inner layer cavity mold 11 of the first injection molding section 10. At this time, the inner layer neck mold 62 and the inner layer cavity mold 11 mold the inner layer preform 2 having a first contact surface (first recess) 2c and a second contact surface (second recess) 2d on the lower outer peripheral surface of the neck portion 2a. The material (first synthetic resin material) of the inner layer preform 2 is preferably an easily deformable material, such as a synthetic resin such as PP. (First injection molding process)

[0051] After the inner layer preform 2 is injected, the molded inner layer preform 2 is transported and placed in a temperature-controlled pot mold (not shown) of the first temperature control section 30a, whereby the inner layer preform 2 is adjusted and cooled to a temperature state suitable for further injection molding (temperature control step).

[0052] Once the inner layer preform 2 has been adjusted and cooled to a temperature suitable for injection molding, the molded inner layer preform 2 is transferred to and placed in the outer layer cavity mold 21. Once the inner layer preform 2 is placed in the outer layer cavity mold 21, the outer layer preform 3 is injection molded onto the outer surface of the inner layer preform 2. At this time, the outer layer preform 3 is engaged with the first abutment surface (first recess) 2c and the second abutment surface (second recess) 2d of the inner layer preform 2. The outer layer neck mold 63 and the outer layer cavity mold 21 also form the upper outer peripheral surface 3c and the through-hole 3a. This results in the molding of a two-layered inner / outer preform 1. The material (second synthetic resin material) for the outer layer preform 3 is preferably a material that can increase the rigidity of the container 1a, such as a synthetic resin such as PET (second injection molding process).

[0053] Once the preform 1 has been molded, the molded preform 1 is transported and placed in a temperature-controlled pot mold (not shown) of the second temperature control unit 30b, whereby the preform 1 is adjusted and cooled to a temperature state suitable for blow molding (temperature control step).

[0054] Once the preform 1 has been adjusted and cooled to a temperature suitable for blow molding, the temperature-adjusted preform 1 is transported and placed in the blow cavity mold 41 of the blow molding section 40. The preform 1 is blow-molded using high-pressure air and a stretch rod (not shown) to produce a container 1a. At this time, the stepped support portion consisting of the first contact surface (first recess) 2c prevents the inner layer preform 2 and the outer layer preform 3 from separating (falling off, shifting, or coming off) (blow molding process). Furthermore, the provision of a stepped support portion consisting of the second contact surface (second recess) 2d further prevents the inner layer preform 2 and the outer layer preform 3 from separating.

[0055] After the container 1a is transported to the removal section 50, the neck mold 60 is opened to recover the container 1a (removal step).

[0056] The support portion provided on the preform 1 can prevent the inner layer preform 2 and the outer layer preform 3 from easily coming apart (separating, falling off, or misalignment) during blow molding. Furthermore, when the contents are consumed, outside air is introduced between the inner layer bottle 2' and the outer layer bottle 3' through the through-hole 3a' in the container 1a, and the inner layer bottle 2' remains in a reduced and shrunk state and separates from the outer layer bottle 3'. Even in this case, the support portion can prevent the inner layer bottle 2' from easily coming apart from the outer layer bottle 3'. In the case of the container 1a, the support portion (first abutment surface (first recess) 2c) of the inner layer bottle 2' is held or engaged with the upper portion (top surface) of the outer layer bottle 3', preventing easy separation. Furthermore, the vent hole (through-hole 3a), which is essential for a peelable container during the injection molding process, can be easily formed. Furthermore, because the neck portion 2a can be molded with high dimensional precision, the airtightness between the neck portion 2a and the extraction plug can be improved compared to containers manufactured by extrusion blow molding, preventing deterioration of the contents and reducing the amount of remaining content. Therefore, peelable containers can be suitably manufactured using hot parison blow molding.

[0057] According to the above procedure, a two-layered preform 1 consisting of the inner layer preform 2 and the outer layer preform 3 is injection molded, and a two-layered container 1a is manufactured.

[0058] In the manufacturing apparatus 100 according to this embodiment, a protrusion 24 is provided on the bottom surface of the outer layer cavity mold 21 for separating the inner layer preform 2 placed in the outer layer cavity mold 21 from the bottom surface. This makes it possible to form a through hole 3a that penetrates only the outer layer preform 3 without providing a step for perforating only the outer layer preform 3 after blow molding. This makes it possible to easily manufacture a two-layer peelable container using the hot parison blow molding method.

[0059] Furthermore, the neck mold 60 of the manufacturing apparatus 100 has different mold surface shapes when injection molding the inner layer preform 2 and when injection molding the outer layer preform 3. As a result, even if the neck mold 60 used to injection mold the inner layer preform 2 continues to hold the preform 1 until after blow molding, the inner layer preform 2 and the outer layer preform 3 can be injection molded to have different shapes, and the first abutment surface 2c and the like can be easily molded into the preform 1. Therefore, even if there is a large difference in the amount of shrinkage after injection molding between the resin used to mold the inner layer preform 2 and the resin used to mold the outer layer preform 3, it is possible to prevent the inner layer preform 2 from becoming detached or misaligned from the outer layer preform 3 during blow molding. Furthermore, even in the case of a container 1a in which the inner layer bottle can be reduced in volume and the contents can be fully consumed, it is possible to prevent the inner layer bottle from becoming detached from the outer layer bottle when the container 1a is used.

[0060] Although the present invention has been described above based on the embodiments, the present invention is not limited thereto. For example, in the above embodiment, the inner layer preform 2 is formed with only the first abutment surface 2c to prevent the inner layer preform 2 from coming off the outer layer preform 3, but this is not limiting. For example, as shown in FIG. 5(a), a convex portion 2e may be further formed in the inner layer preform 2 using an inner layer neck mold 62 and an inner layer cavity mold. As shown in FIG. 5(b), when the outer layer preform 3 is injection molded, a part of the outer layer preform 3 may be interposed between the convex portion 2e and the outer layer neck mold 63, thereby forming a container as shown in FIG. 5(c). Alternatively, as shown in FIG. 6(a), the convex portion 2e may be formed using an inner layer neck mold 64. As shown in FIG. 6(b), when the outer layer preform 3 is injection molded, the convex portion 2e may be sandwiched directly laterally by an outer layer neck mold 65. 7(a), a convex portion 2f may be formed in the inner layer neck mold 66 and the inner layer cavity mold 67 at a position away from the axis C, and a wide first abutment surface 2c may be formed from the convex portion 2f toward the axis C. As shown in FIG. 7(b), when the outer layer preform 3 is injection molded, the convex portion 2f may be fitted into the outer layer preform 3 and the first abutment surface 2c may be in abutment with the outer layer preform 3 over a wide area, and the outer layer neck mold 67 may sandwich the outer layer preform 3 from the side. In the cases of FIGS. 5, 6, and 7, the convex portions 2e and 2f also function as supports that prevent the inner layer preform 2 and the outer layer preform 3, or the inner layer bottle 2' and the outer layer bottle 3', from coming off (separation, falling off, misalignment) (the convex portions 2e and 2f of the inner layer preform 2 or the inner layer bottle 2' engage with the upper part of the outer layer preform or the outer layer bottle 3', preventing easy coming off). Furthermore, the materials for the inner layer preform 2 and the outer layer preform 3 may be set to virgin material (first synthetic resin material) and recycled material (second synthetic resin material), respectively. In this case, the virgin material (first synthetic resin material) and recycled material (second synthetic resin material) may be the same type of material (e.g., PET, PEN, PP, PC, etc.). Because the weight ratio of the outer layer preform 3 is large in the preform 1, it is possible to ensure safety and hygiene while also contributing to the problem of waste plastic.

[0061] Furthermore, as shown in FIGS. 4 to 7 , the manufacturing apparatus 100 according to the above embodiment uses a double-layered neck mold (specifically, an inner layer neck mold 62 and an outer layer neck mold 63) to manufacture a two-layered preform 1 or container 1a having undercuts such as an upper end surface 3e or a protruding portion 2e below the neck portion 2a, but is not limited thereto. For example, as shown in FIG. 8 , the manufacturing apparatus 100 may be an apparatus that uses a normal neck mold that does not have a double-layered structure to manufacture a two-layered preform 1 or container 1a that does not have an undercut below the neck portion 2a. In either manufacturing apparatus 100, a mold having a protrusion on the bottom surface of the outer layer cavity mold 21 can be used to mold a ventilation through-hole in the bottom of the two-layered preform 1 or container 1a using a single apparatus. [Explanation of symbols]

[0062] 1...Preform 1a…Container 2...Preform for inner layer 2'...Inner bottle 2a...Neck 2b...Torso 2c...First contact surface 2e...Convex part 2f...Convex part 3...Outer layer preform 3'...Outer bottle 3a...Through hole 3b...Torso 3c...Top outer circumferential surface 3d...bottom 3e…Top end surface 10...First injection molding section 11...Inner layer cavity mold 12...First injection unit 20...Second injection molding section 21...Cavity mold for outer layer 22...Second injection device 23...Gate section 23a...Stepped surface 24…Protrusion 30a...first temperature adjusting unit 30b...second temperature adjusting unit 40...Blow molding section 41...Blow cavity type 41a...Stepped surface 50…Ejecting part 60...Neck type 61...Neck type body 62...Neck type for inner layer 62a...Guide member 63...Outer layer neck type 63a...Stepped surface 63b...Guide member 64...Neck type for inner layer 65...Outer layer neck type 66...Neck type for inner layer 67...Outer layer neck type 70...Turntable 100...Blow molding device (manufacturing device for resin molded products) C…Axis center

Claims

1. An apparatus for manufacturing a two-layer preform comprising an inner layer preform and an outer layer preform for blow molding a two-layer peelable container, a first injection molding unit including an inner layer injection core mold and an inner layer cavity mold for injection molding the inner layer preform; a second injection molding section including an outer layer injection core mold and an outer layer cavity mold for injection molding the outer layer preform; a neck mold body that holds a neck portion of the inner layer preform when the inner layer preform injection molded in the first injection molding section is transported to the second injection molding section, a protrusion is provided on a bottom surface of the outer layer cavity mold to separate the inner layer preform placed in the outer layer cavity mold from the bottom surface; When the inner layer preform is injection molded, an inner layer neck mold is coupled to the neck mold body to mold a neck portion of the inner layer preform; A two-layer preform manufacturing device characterized in that, when injection molding the outer layer preform, an outer layer neck mold having a mold surface with a shape different from that of the inner layer neck mold is connected to the neck mold main body to mold the upper end of the outer layer preform.

2. 2. The two-layer preform manufacturing apparatus according to claim 1, wherein a contact surface is formed between the neck portion and the body portion of the inner layer preform, the contact surface narrowing around the axis of the inner layer preform and contacting the outer layer preform.

3. A manufacturing apparatus for a two-layer preform including an inner layer preform and an outer layer preform for blow molding a two-layer peelable container, a first injection molding unit including an inner layer injection core mold and an inner layer cavity mold for injection molding the inner layer preform; a second injection molding section including an outer layer injection core mold and an outer layer cavity mold for injection molding the outer layer preform; a neck mold body that holds a neck portion of the inner layer preform when the inner layer preform injection molded in the first injection molding section is transported to the second injection molding section, injection molding the inner layer preform; placing the injection-molded inner layer preform in the outer layer cavity mold; and injection molding the outer layer preform onto the outer surface of the inner layer preform, a protrusion is provided on a bottom surface of the outer layer cavity mold to separate the inner layer preform placed in the outer layer cavity mold from the bottom surface; When the inner layer preform is injection molded, an inner layer neck mold is coupled to the neck mold body to mold a neck portion of the inner layer preform; A method for manufacturing a two-layer preform, characterized in that, when injection molding the outer layer preform, an outer layer neck mold having a mold surface with a shape different from that of the inner layer neck mold is joined to the neck mold body to mold the upper end of the outer layer preform.

4. 4. The method for manufacturing a two-layered preform according to claim 3, wherein the step of injection molding the inner layer preform includes forming an abutment surface on the inner layer preform that narrows around the axis of the inner layer preform between the neck portion and the body portion of the inner layer preform and abuts against the outer layer preform.

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