JP6058485B2 - Preform injection molding equipment - Google Patents

Description

  The present invention relates to an injection molding apparatus for molding a biaxial stretch blow molding preform, and in particular, for molding a preform in which an intermediate layer made of an intermediate resin is laminated on a base layer made of a main resin. The present invention relates to a nozzle of an injection molding apparatus used for the above.

  2. Description of the Related Art A biaxial stretch blow molded casing made of polyethylene terephthalate (hereinafter abbreviated as PET) resin is used in various fields such as beverages, foods, and cosmetics. Particularly in applications that require gas barrier properties, a casing in which an intermediate layer made of a resin having a gas barrier property such as nylon resin or ethylene vinyl alcohol copolymer resin is laminated on a base layer made of PET resin, which is the main resin. Is used. Patent Document 1 describes a method for forming a laminated preform, which is a primary molded product of a laminated casing by biaxial stretch blow molding, in which an intermediate layer made of nylon resin is laminated in a base layer made of PET resin. Yes.

  In the case of such a biaxial stretch blow molding, although the base layer and the intermediate layer are in close contact with each other, they are often not bonded because they are made of different materials. For this reason, there exists a possibility that both layers may peel partially by the effect | action of the shear force resulting from impacts, such as dropping. And, for example, in a carbonated beverage application, once a partially delaminated portion is formed as described above, carbon dioxide gas that has passed through the inner layer of the PET resin enters the peeled portion and is peeled off by the pressure of the carbon dioxide gas. Further progresses, and it is recognized from the outside that light is scattered or reflected at the peeling interface, resulting in a problem that the appearance is impaired.

  In this regard, the applicant of the present application proposes a laminated casing in Patent Document 2 that solves the problem of peeling in the casing having the intermediate layer as described above. Specifically, as shown in FIGS. 10A and 10B as an embodiment, the so-called mouth tube 202, neck ring 203, shoulder 204, cylindrical trunk 205, and a plurality of legs protrude to form a so-called so-called so-called example. In contrast to the case 201 made of the bottom portion 206 having a petaloid shape, in the illustrated example, the region between the outer layer 211a and the inner layer 211b, which are the base layer 211, in the region from directly below the lower end of the neck ring 203 to immediately above the upper end of the bottom portion 206 The intermediate layer 213 (shown by cross-hatching) is laminated on the upper layer, and the intermediate layer 213 is divided in the circumferential direction by a vertical belt-like connecting portion 214 formed by connecting the outer layer 211a and the inner layer 211b. According to the laminated casing having such a configuration, even if delamination occurs in one region of the intermediate layer due to an impact such as dropping, delamination progresses to an adjacent region by the vertical belt-like connecting portion. Since it can prevent, delamination generation | occurrence | production is stopped in the area | region which limited generation | occurrence | production and the external appearance of a housing can be maintained in a favorable and transparent state.

JP-A-1-254539 JP 2013-95035 A

  In addition, the applicant of the present application proposes, in Patent Document 2, a preform for forming the above-mentioned laminated casing by biaxial stretch blow molding, and an injection molding apparatus for injection molding the preform. . Specifically, as shown in FIG. 11 as an example, a preform 101 including a mouth tube portion 102, a neck ring 103, a cylindrical body portion 105, and a bottom portion 106, and a bottom portion from directly below the lower end of the neck ring 103. In the region extending to the upper end of 106, a vertical band formed by laminating an intermediate layer 113 (shown by cross-hatching) between the outer layer 111a and the inner layer 111b as the base layer 111 and connecting the outer layer 111a and the inner layer 111b. The intermediate layer 113 is divided in the circumferential direction by the connecting portion 114.

  As shown in FIG. 12 as an example, the injection molding apparatus has a nozzle portion 311 for injecting a molten resin to a mold 301 for forming the preform 101, and includes a shut-off pin 320, an inner side The inner flow path 315 (the region adjacent to the shut-off pin 320 is a region where the main resin for forming the inner layer 111b and the outer layer 111a of the preform 101 flows by the ring mandrel 324c, the intermediate ring mandrel 324d, and the outer ring mandrel 324e. An intermediate flow path 316 (which is cylindrical and has a cylindrical shape in a region beyond the tip of the shut-off pin 320) and an outer flow path 317 (cylindrical shape) and in which an intermediate layer resin for forming the intermediate layer 113 flows. (Cylindrical shape) and has three layer forming flow paths as a whole. Further, as shown in FIGS. 13 to 15, the middle flow path 316 is divided into a predetermined number of flow paths by blocking vertical rib pieces 316 </ b> R provided at intervals in the circumferential direction at the lower end (tip) portion of the inner ring mandrel 324 c. It is divided. Accordingly, the intermediate layer resin divided in the circumferential direction in the middle flow path 316 is caused to flow between the main material resins from the inner flow path 315 and the outer flow path 317 at the merge point 318, and in the merge flow path 319, the main material A multilayer molten resin fluid in which an intermediate layer resin is coaxially laminated between the resins is formed and injected into the cavity of the mold 301.

  By the way, in the junction 318 of the nozzle part 311, the flow of each molten resin is changed due to the difference in the speed of the molten resin flowing in another flow path and the direction of the resin flowing into the junction 318. For this reason, the flow of the intermediate layer resin evenly divided by the blocking vertical rib pieces 316R may greatly fluctuate due to the influence of the main resin, and as a result, the intermediate layer 113 in the preform and the vertical layer In some cases, the shape (width, thickness, etc.) of the strip-shaped connecting portion 114 changes beyond what is permitted.

  An object of the present invention is to solve such a problem, and the object of the present invention is a multilayer molten resin fluid formed in a nozzle portion of an injection molding device, particularly when joining with a main material resin. To provide an improved injection molding apparatus that can suppress the fluctuation of the flow of the intermediate layer resin and can form the intermediate layer and the vertical belt-like connecting portion in the preform with the shape and size as expected. It is in.

The present invention is used for injection-molding a biaxial stretch blow molding preform in which at least one intermediate layer is laminated in a base layer, and the main material resin forming the base layer and the intermediate layer are formed. An injection molding apparatus having a nozzle portion for injecting an intermediate layer resin,
The nozzle section includes at least an inner channel and an outer channel that form a base layer made of the main material resin, and an intermediate channel that is positioned between the inner channel and the outer channel and forms an intermediate layer made of an intermediate layer resin. An inner ring mandrel having three layer-forming flow paths and having the inner flow path on the inner side, and the intermediate flow between the inner ring mandrel and the inner ring mandrel. An intermediate ring mandrel having a path, and an outer ring mandrel surrounding the intermediate ring mandrel and having the outer flow path between the intermediate ring mandrel and the intermediate ring mandrel,
The intermediate flow path is divided into a predetermined number of flow paths by blocking vertical rib pieces provided to cross the intermediate flow path at the downstream end , and the blocking vertical rib pieces are tapered in the inner ring mandrel. partial or provided on the outer surface of the protruding toward the intermediate ring mandrel said provided on the inner face of the tapered portion of the intermediate ring mandrel is shall projecting toward the inner ring mandrel,
In the injection molding apparatus, the blocking vertical rib piece is inserted into at least one of the inner flow path and the outer flow path.

  Preferably, the blocking vertical rib piece enters at least the outer flow path.

  In the present invention, the blocking vertical rib piece that divides the intermediate path into a predetermined number of flow paths at the downstream end portion enters at least one of the inner flow path and the outer flow path that are provided coaxially across the intermediate path. It is Accordingly, the intermediate layer resin that flows between the blocking vertical rib pieces in the downstream region of the intermediate path can be guided by the blocking vertical rib pieces and can enter at least one of the inner flow path and the outer flow path. Even after merging with the material resin, it is possible to suppress fluctuations in the flow of the intermediate layer resin, and it is possible to form the intermediate layer and the vertical belt-like connecting portion with the expected shape and size.

It is sectional drawing which shows typically one Embodiment of the injection molding apparatus according to this invention. It is a front view of the inner side ring mandrel used for the injection molding apparatus shown in FIG. It is a perspective view which shows the inner side ring mandrel shown in FIG. 2 from the downstream. It is a bottom view which shows the inner side ring mandrel shown in FIG. 2 from the downstream. It is a bottom view which shows the modification of an inner side ring mandrel according to FIG. It is a partial expanded sectional view of the nozzle part periphery in the injection molding apparatus shown in FIG. It is a partial expanded sectional view of a nozzle part periphery about other embodiment of the injection molding apparatus according to this invention. It is a perspective view which shows the inner side ring mandrel used for the injection molding apparatus shown in FIG. 7 from the downstream. It is a front view which shows the inner side ring mandrel used for the injection molding apparatus shown in FIG. 7 from the downstream. (A) is a front view and (b) is a cross-sectional view taken along line AA of (a) with respect to the laminated casing exemplified in Patent Document 2. The preform of the laminated housing shown in FIG. 10 is shown, (a) is a half sectional view in front view, and (b) is a sectional view taken along line BB in (a). It is sectional drawing which shows an example of the injection molding apparatus for shape | molding the preform shown in FIG. It is a front view of the inner side ring mandrel used for the injection molding apparatus shown in FIG. It is a perspective view which shows the inner side ring mandrel shown in FIG. 13 from the downstream. It is a bottom view which shows the inner side ring mandrel shown in FIG. 13 from the downstream.

  Hereinafter, an embodiment of an injection molding apparatus according to the present invention will be described in detail with reference to the drawings. 1 is a sectional view schematically showing an embodiment of an injection molding apparatus according to the present invention, and FIG. 2 is a front view of an inner ring mandrel used in the injection molding apparatus shown in FIG. FIG. 4 is a perspective view showing the inner ring mandrel shown in FIG. 2 from the downstream side, and FIG. 4 is a bottom view showing the inner ring mandrel shown in FIG. 2 from the downstream side. FIG. 6 is a partially enlarged cross-sectional view around the nozzle portion in the injection molding apparatus shown in FIG.

  In FIG. 1, reference numeral 1 denotes a nozzle part that is a part of the injection molding apparatus, and reference numeral 2 denotes a hot runner block that is assembled on the upstream side of the nozzle part 1. Reference numerals A and B denote resin supply units that individually supply two different types of resins (main material resin and intermediate layer resin) in a molten state. Although illustration is omitted, a mold similar to the mold 301 shown in FIG. 12 is assembled on the downstream side of the nozzle portion 1 as a mold for forming a preform.

  In the nozzle portion 1, an inner ring mandrel 12, an intermediate ring mandrel 13, and an outer ring mandrel 14, each having a cylindrical shape, are arranged coaxially in this order around a cylindrical shutoff pin 11. . Thereby, between the shut-off pin 11 and the inner ring mandrel 12, a cylindrical shape in which the main material resin for forming the inner layer of the preform flows (a region beyond the tip of the shut-off pin 11 is a column shape). An inner flow path 15 is formed, and between the inner ring mandrel 12 and the intermediate ring mandrel 13, a cylindrical intermediate flow path 16 is formed in which an intermediate layer resin for forming an intermediate layer of the preform flows, Between the intermediate ring mandrel 13 and the outer ring mandrel 14 is formed a cylindrical outer flow path 17 through which the main resin for forming the outer layer of the preform flows, and there are three layer forming flow paths as a whole. Is provided.

  In addition, at the downstream end of the intermediate flow path 16 and the outer flow path 17, the flow path is reduced in diameter to become a tapered cylindrical flow path, and each layer forming flow is formed downstream of the tapered cylindrical flow path. A cylindrical merge channel 19 is formed via a merge point 18 where the resin flowing through the path merges.

  In addition, a blocking vertical rib piece 20 is provided in the tapered cylindrical portion so as to cross the intermediate flow path 16, and the intermediate flow path 16 has the same number of flow paths as the blocking vertical rib pieces 20 are provided. It is divided. In this embodiment, as shown in FIG. 2 to FIG. 4, a total of eight blocking vertical rib pieces 20 are circumferentially arranged on the tapered portion of the inner ring mandrel 12, which is the downstream end of the middle flow path 16. It is provided at intervals.

  Here, as shown in FIG. 4, the pair of side walls 20 a positioned on both sides in the circumferential direction of the blocking vertical rib piece 20 are upstream of the intermediate flow path 16 (the radially outer side of the inner ring mandrel 12). The side wall portion 20b is formed as an inclined surface in which the distance from each other becomes narrower from the downstream side to the upstream side of the middle flow path 16 (from the radially inner side to the outer side of the inner ring mandrel 12).

  Further, in the side wall 20 a of the blocking vertical rib piece 20, the downstream side wall portion 20 c positioned on the downstream side of the middle flow path 16 (inside in the radial direction of the inner ring mandrel 12) is the downstream side wall portion of the other adjacent blocking vertical rib piece 20. The gap s with 20c is constant from the upstream side to the downstream side (from the radially outer side of the inner ring mandrel 12 to the inner side).

  Here, the configuration in the vicinity of the junction 18 will be described in more detail. In the present embodiment, as shown in FIG. 6, the inner peripheral end 13 a of the intermediate ring mandrel 13 is connected to the inner peripheral end 20 e of the blocking vertical rib piece 20. (The inner peripheral end 13a is positioned on the upstream side of the outer flow path 17 relative to the inner peripheral end 20e) and is in contact with the blocking vertical rib piece 20 so that the blocking vertical rib piece 20 flows outward. The road 17 is entered. The effect on this point will be described later.

  On the other hand, as shown in FIG. 1, a passage through which the molten resin from the hot runner block 2 flows is formed on the upstream side of the three layer forming channels. In the present embodiment, the two manifolds 22 and 23 connected to the introduction path 21 are connected to the inner flow path 15 and the outer flow path 17, respectively. Further, the introduction path 24 provided separately from the introduction path 21 is connected to the middle flow path 16 via the manifold 25.

  The hot runner block 2 assembled on the upstream side with respect to the nozzle unit 1 has a supply port 26 for introducing the main material resin supplied from the resin supply unit A, the supply port 26, and the introduction path 21 described above. A hot runner 27 is provided to connect the two. Further, a supply port 28 for introducing the intermediate layer resin supplied from the resin supply unit B, and a hot runner 29 for connecting the supply port 28 and the aforementioned introduction path 24 are provided. Further, on the downstream side of the hot runner 29, a check valve 30 having a backflow prevention function by a ball valve is provided so that the supply of the intermediate layer resin can be started and stopped in a short time with high accuracy. Yes. The check valve 30 may be provided in the nozzle unit 1.

  In forming a preform using the injection molding apparatus configured as described above, the molten main material resin is introduced from the resin supply unit A to the supply port 26, and the molten intermediate layer resin is supplied to the resin supply unit. B is introduced into the supply port 28. As a result, the molten main material resin is distributed by the two manifolds 22 and 23 through the hot runner 27 and the introduction path 21, and is introduced into the inner flow path 15 and the outer flow path 17. On the other hand, the melted intermediate layer resin is introduced into the middle flow path 16 via the manifold 25 via the hot runner 29 and the introduction path 24 with the check valve 30 opened. In FIG. 6, the arrows a, b, and c respectively indicate the flow of the main material resin in the inner flow path 15, the flow of the intermediate layer resin in the intermediate flow path 16, and the flow of the main material resin in the outer flow path 17. Show the flow.

  Here, the upstream side wall portion 20b of the blocking vertical rib piece 20 provided in the middle flow path 16 is formed as an inclined surface whose width is narrower on the upstream side (the radially outer side of the inner ring mandrel 12) as shown in FIG. Therefore, the molten intermediate layer resin flowing through the intermediate flow path 16 from the upstream side toward the downstream side (from the radially outer side of the inner ring mandrel 12 to the inner side) flows without being blocked by the blocking vertical rib piece 20. be able to. If the molten resin stays in the injection molding apparatus, resin burning (carbonization) occurs, and the carbonized resin may be mixed as impurities in the preform, and the carbonized resin adheres to the blocking vertical rib pieces 20 and the like. As a result, the intermediate flow path 16 is narrowed, and as a result, the intermediate layer and the vertical belt-like connecting portion in the preform may not be formed with the required dimensions, but the upstream side wall portion 20b is formed as an inclined surface as described above. Thus, these problems can be effectively prevented.

  Further, as shown in FIG. 4, the downstream side wall portion 20c of the blocking vertical rib piece 20 has a constant gap s between the downstream side wall portion 20c of another adjacent blocking vertical rib piece 20 from the upstream side to the downstream side. Therefore, the flow width of the intermediate layer resin can be stabilized by flowing between these downstream side wall portions 20c.

  Then, the intermediate layer resin b divided into eight in the circumferential direction flows toward the junction 18 as shown in FIG. Here, in the present embodiment, the inner peripheral end 13a of the intermediate ring mandrel 13 is positioned radially outward from the inner peripheral end 20e of the blocking vertical rib piece 20 (the inner peripheral end 13a is more outwardly flowed than the inner peripheral end 20e). Since the blocking vertical rib piece 20 enters the outer flow path 17 by being in contact with the blocking vertical rib piece 20, the intermediate layer resin divided by the blocking vertical rib piece 20 is located on the upstream side of the path 17. Even after joining the main material resin c flowing in the outer flow path 17, b is guided by the adjacent blocking vertical rib pieces 20 and flows. Thereby, since the flow of the divided intermediate layer resin b can be poured into the joining point 18 in a stable state, the joining channel 19 has a laminated state as intended together with the main material resin a flowing in the inner passage 15. A multilayer molten resin fluid is formed. In addition, since the interruption | blocking vertical rib piece 20 will obstruct the flow of molten resin when the quantity which the interruption | blocking vertical rib piece 20 penetrates into the outer flow path 17 is too large, as shown in FIG. 6, the inner periphery of the intermediate ring mandrel 13 is shown. The step h between the end 13a and the inner peripheral end 20e of the blocking vertical rib piece 20 is preferably about 0.7 mm to 1.0 mm.

  Thereafter, the preform is molded by injecting and filling a multilayer molten resin fluid into a cavity of a mold (not shown). In addition, since the supply start and stop of the intermediate layer resin can be switched with high accuracy in a short time by opening and closing the check valve 30, the supply of the intermediate resin is performed for a predetermined time with respect to the supply start of the main material resin. By starting with a delay and ending the supply of main material resin earlier by a predetermined time, an intermediate layer is laminated in a region extending from directly below the bottom end of the neck ring to the top end of the bottom as shown in FIG. It is possible. In addition, the range which provides an intermediate | middle layer is not limited to the example of Fig.11 (a).

  Next, another embodiment according to the present invention will be described with reference to FIGS. FIG. 7 is a partially enlarged cross-sectional view around the nozzle portion according to another embodiment of the injection molding device according to the present invention. FIG. 8 shows an inner ring mandrel used in the injection molding device shown in FIG. 7 from the downstream side. FIG. 9 is a front view showing the inner ring mandrel used in the injection molding apparatus shown in FIG. 7 from the downstream side.

  As shown in FIG. 7, the present embodiment is different from the above-described embodiment in that the blocking vertical rib piece 20 is inserted into the inner flow path 15. More specifically, as shown in FIGS. 8 and 9, the inner peripheral end 20 e of the blocking vertical rib piece 20 extends until it is located radially inward of the opening edge 12 a of the inner ring mandrel 12. As a result, the intermediate layer resin b is guided by the adjacent blocking vertical rib pieces 20 and flows after joining the main material resin a flowing in the inner flow path 15. A multilayer molten resin fluid that is in a laminated state as intended is formed together with the main material resin c flowing in the passage 17. In addition, in this embodiment, since the interruption | blocking vertical rib piece 20 will be located in the radial inside rather than the opening edge 12a of the inner side ring mandrel 12, embodiment mentioned above is more excellent in terms of intensity | strength. .

  The injection molding apparatus according to the present invention is not limited to the above-described embodiment, and can be various variations. For example, in the two embodiments described above, the blocking vertical rib piece 20 enters only one of the outer flow path 17 and the inner flow path 15, but it may be allowed to enter both. In addition, the blocking vertical rib piece 20 is provided at the tapered portion of the inner ring mandrel 12, but it may be further extended to the upstream side and extended to the cylindrical outer peripheral surface of the inner ring mandrel 12. Further, in the example shown in FIG. 4, the upstream side wall portion 20 b of the blocking vertical rib piece 20 is connected to each other at an acute angle, but as shown in FIG. 5, the outer wall portion 20 d located on the radially outer side is left. Further, as shown in FIGS. 13 to 15, it is possible to use one provided with no inclined surface formed as the upstream side wall portion 20 b. And you may add the inclined surface of the upstream side wall part 20b shown to FIG. 4 and FIG. 5 to the interruption | blocking vertical rib piece 20 shown to FIG. 8, FIG. Further, the blocking vertical rib piece 20 can be provided on the inner surface of the intermediate ring mandrel 13 instead of the inner ring mandrel 12.

  Further, in the above-described embodiment, the nozzle portion is formed so that the laminated structure of the preform is two types and three layers. However, by appropriately adding a flow path to the nozzle portion, for example, two types, four layers, and three types are provided. Preforms having various laminated structures such as four layers can be formed. Further, the number of the blocking vertical rib pieces 20 can be appropriately changed according to the desired number of vertical belt-like connecting portions, and is not limited to a plurality, but may be one.

  According to the injection molding apparatus of the present invention, even if the injection molding of the preform is continuously performed, the longitudinal strip-like connecting portion can be formed with the desired shape and size, so that the quality-enhanced molding is achieved. Reform can be formed, and clogging of the nozzle portion can be suppressed, so that production efficiency can be improved.

DESCRIPTION OF SYMBOLS 1 Nozzle part 2 Hot runner block 11 Shut off pin 12 Inner ring mandrel 12a Opening edge 13 Intermediate ring mandrel 13a Inner peripheral edge 14 Outer ring mandrel 15 Inner flow path 16 Middle flow path 17 Outer flow path 18 Merge point 19 Merge flow path 20 Blocking vertical Rib piece 20a Side wall 20b Upstream side wall part 20c Downstream side wall part 20d Outer side wall part 20e Inner peripheral edge 21 Introduction path 22, 23 Manifold 24 Introduction path 25 Manifold 26 Supply port 27 Hot runner 28 Supply port 29 Hot runner 30 Check valve A Resin supply Part B Resin supply part a Flow of main resin in internal flow path,
b Flow of the intermediate layer resin in the middle flow path c Flow of the main material resin in the outer flow path h Step difference between the inner peripheral end of the intermediate ring mandrel and the inner peripheral end of the blocking vertical rib piece s Gap 101 Preform 102 Mouth tube portion 103 Neck ring 105 Trunk portion 106 Bottom portion 111 Base layer 111a Outer layer 111b Inner layer 113 Intermediate layer 114 Vertical belt-like connecting portion 201 Housing 202 Mouth tube portion 203 Neck ring 204 Shoulder portion 205 Trunk portion 206 Bottom portion 211 Base layer 211a Outer layer 211b Inner layer 213 Intermediate layer 214 Longitudinal connecting portion 301 Mold 311 Nozzle portion 315 Inner flow path 316 Middle flow path 316R Blocking vertical rib piece 317 Outer flow path 318 Merge point 319 Merge flow path 320 Shutoff pin 324c Inner ring mandrel 324d Intermediate ring mandrel 324e Outer ring mandrel

Claims (2)

A main material resin for forming the base layer and an intermediate layer resin for forming the intermediate layer, which are used for injection molding a biaxial stretch blow molding preform in which at least one intermediate layer is laminated in the base layer. An injection molding apparatus having a nozzle portion for injecting
The nozzle section includes at least an inner channel and an outer channel that form a base layer made of the main material resin, and an intermediate channel that is positioned between the inner channel and the outer channel and forms an intermediate layer made of an intermediate layer resin. An inner ring mandrel having three layer-forming flow paths and having the inner flow path on the inner side, and the intermediate flow between the inner ring mandrel and the inner ring mandrel. An intermediate ring mandrel having a path, and an outer ring mandrel surrounding the intermediate ring mandrel and having the outer flow path between the intermediate ring mandrel and the intermediate ring mandrel,
The intermediate flow path is divided into a predetermined number of flow paths by blocking vertical rib pieces provided to cross the intermediate flow path at the downstream end , and the blocking vertical rib pieces are tapered in the inner ring mandrel. partial or provided on the outer surface of the protruding toward the intermediate ring mandrel said provided on the inner face of the tapered portion of the intermediate ring mandrel is shall projecting toward the inner ring mandrel,
An injection molding apparatus in which the blocking vertical rib piece is inserted into at least one of the inner channel and the outer channel.   The injection molding apparatus according to claim 1, wherein the blocking vertical rib piece is inserted into at least the outer flow path.

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