JP2004314336A - Hollow multilayered resin molded article and its molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hollow multilayered resin molded article, which is constituted so as to prevent the exposure of a resin constituting an intermediate resin layer to the inner surface of the molded article, has excellent sanitation properties, does not cause the disturbance such as non-uniform wall thickness, multiplicity, cutting and the like of the intermediate resin layer, ensures a uniform layered constitution and has excellent functionality, by compression molding. <P>SOLUTION: A ring or disc-shaped auxiliary resin lump 9 comprising an inner surface coating resin is fused to the upper end part of a cylindrical main resin lump 7 having another resin layer excepting the inner surface coating resin to obtain a main/auxiliary resin lump 10. In such a state that the main/auxiliary resin lump is seated on the bottom surface of a cavity, the auxiliary resin lump is compressed by a core mold 13 so as to flow along the cylindrical inner layer of the cylindrical main resin lump to allow the inner surface coating resin to flow along the inner surface of a main resin layer to coat the inner surface of the main resin layer with an auxiliary resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a hollow multilayer resin molded product and a method for molding the same, and more particularly to a hollow multilayer resin molded product formed by compression molding a hollow multilayer resin molded product such as a cylinder having an inner coating resin layer.
[0002]
[Prior art]
Conventionally, for example, a cylindrical composite parison formed of a multilayer resin including a barrier resin layer in the middle is formed by extrusion molding, and a multilayer structure manufactured by compression-molding the cylindrical composite parison with a core mold and a cavity mold. A plastic nozzle for a container is provided (see Patent Document 1). On the other hand, in such a composite parison, the barrier resin layer has almost the same outer diameter as the cylindrical parison in order to prevent the barrier resin layer from being exposed at the cut edges at both ends of the parison, and thus to be exposed at the ends of the molded product. A method of manufacturing a multilayer plastic container or container component using a composite parison having a donut-shaped or disk-shaped terminal member fused to an end of a cylindrical parison having an exposed barrier resin layer and covering a cut end. Is also provided (see Patent Document 2). Further, as a method of molding a compression molded product from a molten resin composed of a single layer of thermoplastic resin, a molten resin mass extruded from a die can be stretched to form a part of a compression molding die arranged in a female mold. A compression molding method is known in which the intermediate support member is placed on the surface of the intermediate support member and closed by closing the mold, and compression molding is performed by a male mold and a female mold at the recessed position (see Patent Document 3).
[0003]
[Patent Document 1]
JP 2001-55238 A
[Patent Document 2]
JP 2001-145952 A
[Patent Document 3]
Japanese Patent Publication No. Hei 7-61656
[0004]
[Problems to be solved by the invention]
The compression molding of the cylindrical multilayer resin molded product is performed between the cavity mold by pushing the core mold into the inside of the composite tubular parison supplied into the cavity mold as described above. The hollow multi-layer resin molded product obtained by compression molding is cut in the axial direction (that is, the movable direction of the core mold), and the cut surface is photographed and observed with a microscope, and the intermediate resin layer is formed on the inner wall surface of the molded product. Exposed portions, portions where the coating of the intermediate resin layer by the inner wall layer is thin, and portions where the thickness of the intermediate resin layer is excessively thin, cut off, or excessively thick exist. Rarely observed. Such unevenness of the intermediate resin layer, the presence of multiple layers, cuts, and the like impair the function of the intermediate resin layer. For example, if the intermediate resin layer is a gas barrier resin layer, the gas barrier function is impaired. There's a problem. In addition, when the thickness of the inner surface layer is not uniform and the coating of the intermediate resin layer by the inner surface layer is not sufficient, and the intermediate resin layer is exposed on the inner surface, for example, the molded product comes into direct contact with the contents in a container in a container. If this is not preferable, there is a problem that the contents may be adversely affected. Further, when the barrier resin is exposed, a problem (water shock) occurs in which the barrier resin absorbs moisture of the contents and the barrier performance is deteriorated.
[0005]
The present invention is intended to solve the above-mentioned problems of the prior art, and an intermediate molded article such as a parison made of a multilayer resin, or a hollow multilayer resin molded article such as a final molded article of a container or a member thereof is provided. During compression molding, the inner surface coating resin layer completely covers the intermediate resin layer and the intermediate resin layer is not exposed to the inner surface, or the intermediate resin layer becomes excessively thick, thin, and cut off. It is an object of the present invention to provide a hollow multi-layer resin molded product which can prevent the non-uniform thickness of the resin, can secure the thickness of the inner surface coating resin layer, and can be easily molded with a simple device, and a molding method thereof. I do.
[0006]
[Means for Solving the Problems]
The present inventors have first investigated the cause thereof to solve the above problems, and as a result, when compressing and molding a parison made of a cylindrical multilayer resin, the core mold was wound around the resin on the inner surface of the cylindrical resin. It turned out that the cause was the phenomenon of dragging downward. Therefore, as a result of diligent research on a method for solving the problem, when a conventional multilayer resin cylindrical molded product is compression-molded, a parison (resin block) having a desired multilayer configuration is obtained in advance by extrusion molding and the like, and then compression-molded. However, in the extrusion molding to obtain a multilayer resin mass, only the other layer components excluding the inner surface coating resin layer, which is the innermost resin layer, are extruded to obtain a main resin mass, and the resin to be the inner surface coating resin layer Is added to the upper portion of the resin mass at the time of compression molding, and at the time of compression molding, the inner surface coating resin is caused to flow with respect to the inner surface layer of the main resin mass obtained in advance, thereby forming the inner surface coating resin layer. The inventors have found that the point can be solved, and have reached the present invention.
[0007]
That is, the hollow multilayer resin molded product of the present invention is a hollow multilayer resin molded product comprising a main resin layer and an inner surface coating resin layer covering the inner surface of the main resin layer, wherein the inner surface coating resin layer is The resin layer is formed by flowing an inner surface coating resin to the resin layer. The layer structure and the resin of the hollow multilayer resin molded product are not particularly limited, but the main resin layer may be a single layer or a multilayer depending on the application. For example, when a gas barrier resin is used to give a function to the main resin layer, the gas barrier resin may be used as a single layer for the main resin layer, or may be used as a multilayer in combination with another resin.
When the main resin layer has a multilayer structure, for example, a main resin layer formed of an outer resin layer and an intermediate resin layer made of a gas barrier resin, and an inner surface coating resin layer covering the inner surface of the main resin layer. That is, the inner surface coating resin layer is formed by flowing with respect to the main resin layer. Alternatively, as another form, the main resin layer is formed of an outer resin layer, an intermediate resin layer, and an inner resin layer, and the inner surface of the inner resin layer is coated with an inner surface coating resin layer. Various forms can be adopted, such as flowing the resin layer to form the resin layer.
The intermediate resin layer is not limited to the above-mentioned gas barrier resin, but may be a functional resin material such as an oxygen-absorbing resin or a moisture-blocking resin, or a recycled resin (repro material). Further, the hollow multilayer resin molded product of the present invention is not particularly limited, and an intermediate molded product such as a parison made of a multilayer resin, or a final molded product such as a container or a member thereof is not particularly limited. The present invention can be applied to both molded products and bottomed molded products such as containers. In addition, the form of the hollow shape is not particularly limited as long as it has an inner surface facing the space, such as a tubular shape whose upper and lower ends are open.
[0008]
Then, the method of molding the hollow multilayer resin molded article of the present invention for molding the hollow multilayer resin molded article is performed by fusing a sub-resin mass formed of an inner surface coating resin to an upper end portion of the cylindrical main resin mass, The inner surface of the main resin layer is covered with the sub-resin by compressing the sub-resin mass so as to flow along the cylindrical inner layer of the cylindrical main resin mass. The sub-resin mass is preferably configured as a ring or a disk.
[0009]
The compression molding method of another hollow multilayer resin molded product of the present invention is a method of compression molding a hollow multilayer resin molded product comprising a main resin layer and an inner surface coating resin layer covering an inner surface of the main resin layer, A step of obtaining a cylindrical main resin mass having another resin layer except for the inner surface coating resin layer, and a main resin mass formed by fusing a sub-resin mass made of a resin to be the inner surface coating resin layer to an upper portion of the cylindrical main resin mass; A step of obtaining a sub-composite resin mass, and a step of compressing and molding the main and sub-composite resin mass with a cavity mold and a core mold. The inner surface of the main resin layer is covered with the auxiliary resin by compressing the inner surface of the main resin layer so as to flow along the inner layer.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view in the order of molding steps for explaining an outline of a method for molding a hollow multilayer resin molded product according to an embodiment of the present invention.
In this embodiment, a cylindrical hollow multilayer resin molded article 1 shown in FIG. 1E is molded, and the molded article 1 has a main resin layer as an outer resin layer 2 and an intermediate resin layer as a gas barrier. The inner resin layer 4 is covered with an inner surface coating resin layer 5. The inner surface coating resin layer 5 extends from an upper end surface coating resin layer 6 provided on the upper end surface of the multilayer tubular resin layer. Therefore, the upper ends of the gas barrier resin layer 3 and the outer resin layer 2 to the inner resin layer 4 are covered by the upper end surface coating resin layer 6 and are not exposed to the outside. Further, since the inner surface is formed by flowing the inner surface coating resin layer 5 with respect to the inner resin layer 4 as described later, the inner surface can be uniformly coated, and the gas barrier resin layer 3 and the inner resin layer 4 is formed without being exposed on the inner surface or having a nonuniform layer thickness.
[0011]
The hollow multilayer resin molded product 1 having the above-described layer configuration is molded as follows. First, a main resin block 7 in which the outer resin layer 2, the gas barrier resin layer 3, and the inner resin layer 4 are formed in this order by extrusion or the like is obtained in advance. Next, the ring-shaped or disk-shaped sub-resin mass 9 is fused to the upper end surface of the main resin mass 7 to obtain the main-sub-composite resin mass 10. The main and sub-composite resin masses thus obtained are placed in a cavity mold, as shown in FIGS. 3B to 3D, with a diameter larger than the inner diameter of the main resin mass 7 and the ring-shaped sub-resin mass 9. Is pressed into the cylindrical central portion of the main / sub composite resin block 10 to perform compression molding. In the compression molding, when the core mold 13 having a diameter larger than the inner diameter of the main resin mass 7 and the sub-resin mass 9 is lowered, the tip of the core mold 13 hits the resin near the inner diameter of the sub-resin mass 9, and in that state. When the core mold descends, the resin of the sub-resin mass 9 flows as the core mold 13 descends, as shown in FIG. , The entire main and sub composite resin blocks are pressed against the inner peripheral surface of a cavity mold (not shown) to perform compression molding. When the core mold 13 is completely lowered, the large-diameter upper flat mold surface 15 of the core mold 13 compresses the upper end surface of the sub-resin block 9 to a predetermined thickness to cover the upper end surface. Thus, a desired hollow multilayer resin molded article 1 continuously coated with the same resin is formed. Then, by releasing the mold, the hollow multilayer resin molded product 1 shown in FIG.
[0012]
Next, an embodiment in which a hollow multilayer resin molded product is compression-molded by the method of the present invention will be described with reference to FIG. FIG. 2 is a process chart showing an embodiment when the spout 20 shown in FIG. The spout 20, which is a hollow multilayer resin molded product of the present embodiment, has a four-layer structure except for an adhesive layer (not shown) provided between each layer, and includes an outer resin layer 21, a gas barrier resin layer 22, and an inner resin layer. It is composed of a resin layer 23, an upper end surface coating resin layer 24 and an inner surface coating resin layer 25.
[0013]
If these resins are thermoplastic resins, any resin can be adopted according to the application. For example, as the outer resin layer 21, the inner resin layer 23, the upper end surface coating resin layer 24, and the inner surface coating resin layer 25, olefin is used. It is preferable to select a resin such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and linear ultra-low-density polyethylene (LVLDPE). Polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer , Ethylene-vinyl acetate copolymer (EVA), ion-crosslinked olefin copolymer (ionomer) or These blends can be adopted. In addition, it can be used for thermoplastic polyester resins in general, and other polyesters such as ethylene phthalate-based thermoplastic polyester (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), or polycarbonate and polyarylate with these. Blends with E.g. The resin of the gas barrier resin layer 22, the outer resin layer 21, the inner resin layer 23, and the sub-resin mass 27 may be the same resin or different resins. For example, when the gas barrier resin layer 22 is used as an oxygen gas barrier layer, the most preferable example is that the content of vinyl alcohol units is 40 to 85 mol%, particularly 55 to 80 mol%, Is 96% or more, especially 99% of ethylene-vinyl alcohol copolymer.
[0014]
Other oxygen gas barrier resins include nylon resins, especially nylon 6, nylon 8, nylon 11, nylon 12, nylon 6,6, nylon 6,10, nylon 10,6, and nylon 6 / 6,6. Examples thereof include aliphatic nylons such as polymers, partially aromatic nylons such as polymethaxylylene adipamide, and polyglycolic acid resins.
These oxygen gas barrier resins have an oxygen permeability coefficient of 5.5 × 10 5 from the viewpoint of the storage stability and fragrance retention of the contents.^{− 12}cc · cm / cm²Sec · cmHg (23 ° C., 0% RH) or less.
[0015]
Further, when the intermediate resin layer is an oxygen-absorbing resin layer, oxygen absorption may be added to the gas barrier layer, and the resin of the gas barrier layer may have a structure having oxygen absorption. Examples of such a resin include those utilizing an oxidation reaction of the resin, and oxidizing organic materials such as polybutadiene, polyisoprene, polypropylene, ethylene / carbon oxide polymer, nylon-6, nylon-12, and meta- Polyamides such as xylylenediamine (MX) to which an organic acid salt containing a transition metal such as cobalt, rhodium, copper or the like, or a photosensitizer such as benzophene, acetophene or chloroketone is added as an oxidation catalyst. Can be used. When these oxygen-absorbing materials are used, further effects can be exhibited by irradiating high energy rays such as ultraviolet rays and electron beams.
Further, an oxidizable organic component may be contained in the resin of the gas barrier layer so as to exhibit oxygen absorption without lowering gas barrier properties due to oxidative deterioration of the gas barrier layer. As such an oxidized organic component, a polyene-based polymer derived from polyene is preferable, and a carboxylic acid group, a carboxylic anhydride group, and a hydroxyl group are preferably introduced. Examples of these functional groups include acrylic acid, methacrylic acid, maleic acid, unsaturated carboxylic acid, maleic anhydride, and anhydride of unsaturated carboxylic acid. Cobalt is preferred as the transition metal catalyst.
Further, an oxygen absorbent may be added to the resin constituting the gas barrier layer. Examples of such an oxygen absorbent include reducing metal powders, such as reducing iron powder, reducing zinc, and reducing tin. Powders, low-metal oxides, and those containing a combination of two or more of reducing metal compounds as main components are exemplified. These can be used in combination with an auxiliary such as an alkali metal, an alkaline earth metal hydroxide, a carbonate, a sulfite, an organic acid salt, a halide, further activated carbon, or activated alumina, if necessary. . Alternatively, a polymer compound having a polyhydric phenol in the skeleton, for example, a phenol-aldehyde resin containing a polyhydric phenol may be used.
[0016]
As the moisture barrier resin, a cyclic olefin-based copolymer or an amorphous to low-crystalline copolymer (COC) of an olefin and a cyclic olefin can be used.
Fillers, colorants, heat stabilizers, weather stabilizers, antioxidants, antioxidants, light stabilizers, ultraviolet absorbers, antistatic agents, metals A lubricant and a modifier such as soap and wax can be blended.
Further, in the case of the above-mentioned multilayer structure, an adhesive or an adhesive layer may be interposed between the resin layers as necessary.
The manufacturing process of the spout 20 which is the hollow multilayer resin molded product of the present embodiment is as follows.
[0017]
The compression molding device 32 of the present embodiment includes a combination of a female mold 34 having a cavity 33 and a core mold 36 which is a male mold, and is provided so that a plunger 35 penetrates the center of the cavity 33 so as to be vertically movable. Have been. The core mold 36 has a cylindrical shape portion 37 having an outer diameter corresponding to the inner diameter of the spout, which is the target molded product, and a height corresponding to the inner depth of the spout, and a lower end having a flat mold surface 38 at the top. A rod portion 39 whose diameter is equal to the outer diameter of the spout is driven up and down by a cylinder device (not shown). Then, the female mold 34 of the compression molding apparatus relatively moves below the multi-layered multi-ring die 30 for extruding the main resin mass and the ring die (not shown) for extruding the sub-resin mass 27, and directly into the cavity. The main resin mass and the sub-resin mass can be received from the die.
[0018]
Using the apparatus as described above, first, the resin constituting the inner resin layer, the gas barrier resin layer, and the outer resin layer is three-layered by a multi-layered ring die 30 as shown in FIG. The main resin block 26 is co-extruded so as to fit into a plunger 35 that penetrates vertically through the cavity 33 of the compression molding device 32, and cut into a predetermined length to form the main resin block 26. (FIG. 2B). The cut main resin mass falls into the cavity 34 guided by the plunger in a molten state (FIG. 3C). Next, the sub-resin mass 27 made of a single resin is extruded from the ring die so as to fit directly into the plunger and cut into a predetermined length. The sub-resin mass 27 that has dropped in the molten state falls onto the upper portion of the main resin mass 26 in the cavity and fuses with the main resin mass to form a main-sub-composite resin mass 28 (FIG. 4D). In this state, the core mold 36, which is a male mold, descends coaxially with the plunger, descends while pressing the upper end of the plunger, and compression-molds the main / sub composite resin mass 28 with the cavity. At the start of compression molding, the main and sub-composite resin blocks are seated at the bottom of the cavity as shown in FIG. This is an important factor in making the resin flow greatly to ensure the coating of the inner peripheral surface. FIG. 4E is an enlarged front view of the main and sub composite resin block 28.
[0019]
In the compression molding step, the tip of the cylindrical mold 37 is engaged with the tip of the engaging portion of the plunger 35, and the core mold 36 descends while pushing down the plunger. 40 is pressed against the upper surface of the sub-resin mass. By continuing the downward movement, the sub-resin in the contacting portion of the lower surface of the tip portion 40 is fluidized, and is drawn to the outer peripheral portion with the lowering of the columnar portion 37, thereby forming the hollow portion of the main resin mass. By entering, the inner peripheral surface of the main resin block advances while being covered with the auxiliary resin. Then, by pressing the main resin in the circumferential direction through the fluidized sub-resin and pressing against the cavity mold, with the downward passage of the core mold, the position is molded into a predetermined shape, and when it reaches the lower end. The resin is pressed between the bottom surface of the cavity mold and the end surface of the cylindrical mold portion, and a bottom wall having an opening 19 in a portion where the plunger 35 is located is formed (FIG. 6F). As described above, the spout 20 as the hollow multilayer resin molded product shown in FIG.
[0020]
FIG. 3 shows another embodiment of the present invention, and schematically shows an outline of compression molding of a bottomed hollow multilayer resin molded product. Only differences from the embodiment shown in FIG. 1 will be described.
In the present embodiment, the sub-resin mass 50 is not ring-shaped, but has a shape that covers the entire upper portion of the through-hole of the main resin mass, and may be a case where the central portion is thin as shown in the drawing. It may be in the form of a disk having the same thickness, and is appropriately selected according to the shape of the compression molded product. The main resin mass 51 can be selected from any of a single layer and a multilayer depending on the application. In this way, the main composite resin mass 52 is pressed and molded by the core mold 55 in the female cavity in the same manner as in the above embodiment. As shown in FIG. 3B, the core mold 55 of the present embodiment has a hemispherical lower end, and although not shown, the bottom surface of the cavity is also formed hemispherically. Accordingly, in the compression molding, according to the same principle as described above, as the core mold descends, the portion directly supported by the main resin mass and hit by the core mold is pressed most, and this portion flows, and the main resin flows. It descends while covering the inner peripheral surface of the lump, and at the lower end surface, the opening of the main resin lump concentrates at one point to form a continuous hemisphere according to the shape of the cavity. The hollow multilayer resin molded product 53 can be obtained.
[0021]
In the embodiment shown in FIG. 2, the main resin mass having a multilayer structure and the sub-resin mass having a single-layer structure are extrusion-molded by separate ring dies. However, as shown in FIG. By applying the parison molding apparatus, a main-sub-composite resin block in which a main resin block and a sub-resin block are fused can be obtained in one process using the same extrusion molding apparatus.
The extrusion molding apparatus 60 of FIG. 4 opens and closes the first die head discharge port 63 by moving the single-layer or multilayer main resin continuously extruded from the first resin extruders 61a to 61c by moving the core member 62 up and down. Thus, an intermittent main resin block 57 is formed. Then, the intermittent main resin mass portions are connected by a sub-resin made of one or more resins provided from a second die head ejection port 64 different from the first die head ejection port to form a sub-resin mass portion 58. This makes it possible to dispose two or more resin blocks in the longitudinal direction of the parison. Therefore, by cutting from the sub-resin mass, it is possible to obtain a main-sub composite resin mass in which the main resin mass and the sub-resin mass are fused in one process using the same extrusion molding apparatus.
[0022]
【Example】
Example 1
Polypropylene is supplied to the extruder for the inner and outer layers, and ethylene vinyl alcohol copolymer resin (Eval manufactured by Kuraray) is supplied to the extruder for the innermost intermediate layer. These adhesive layers are bonded to the extruder for the inner and outer layers. Supply materials. These are co-extruded into a cylindrical shape with a molten resin at a die temperature of 200 ° C. and cut.
The molten cylindrical main resin mass is dropped into a compression mold with a plunger while maintaining alignment, and the molten cylindrical sub-resin mass consisting of a single layer of polypropylene is set on the main resin mass. This is compression molded with a core mold, and the inner layer and the outer layer are a polypropylene resin layer, the inner and outer layers are an adhesive resin layer, and the innermost layer is 2.3 g in weight, 45 mm in height, 11 mm in outer diameter, and 1 mm in thickness. The spout shown in FIG. 2 (g) was obtained in which the intermediate layer was composed of an ethylene vinyl alcohol copolymer resin layer, and the inner surface was composed of three types and six layers coated with a polypropylene fluidized bed.
[0023]
Example 2
As a main resin, a flake-shaped recovered polyester resin is extruded from a twin-screw extruder into a cylindrical shape at a die temperature of 270 ° C. and cut. The molten cylindrical main resin mass is dropped into a compression mold while maintaining alignment with a plunger, and then a virgin polyester resin is extruded into a disk at a die temperature of 270 ° C. and set on the main resin mass. I do. This was compression molded with a core mold to obtain a two-layer preform having a weight of 25.0 g and having a recovered polyester resin as an outer layer and a virgin polyester resin as an inner layer as shown in FIG. 3C.
[0024]
Of the spouts of Example 1 obtained as described above, 10 were cut along the center in the vertical direction, and the cut surface was observed with a camera image. It was observed that a fluidized bed of polypropylene was formed with a substantially uniform thickness, and no portion where the adhesive or the ethylene-vinyl alcohol copolymer resin layer was exposed on the inner wall surface was observed. Further, it was observed that the ethylene vinyl alcohol copolymer resin layer as the intermediate resin layer was almost equal in thickness without any excessively thin portion, cut portion or excessively thick portion. Similarly, with respect to the two-layer preform of Example 2, ten pieces were cut along the axis and their longitudinal sections were observed by a camera image. The fluidized layer of virgin polyester resin was found on the inner wall surface of the molded product. Was observed to have a substantially uniform thickness and a continuous bottom portion, and no portion exposed to the adhesive or the outer layer was observed. From the above results, it was confirmed that the method for producing a hollow multilayer resin molded product according to the present invention is particularly effective for uniformly and favorably forming the inner surface coating resin layer.
[0025]
【The invention's effect】
As described above, according to the present invention, the inner surface coating resin layer can completely cover the inner surface of the main resin layer, the resin constituting the main resin layer is not exposed on the inner surface, the hygiene is excellent, and the intermediate layer It is possible to ensure uniform layer structure without unevenness such as uneven wall thickness, multiple layers, cuts, etc., and to exhibit the functions of the multilayer structure and have excellent functionality. A hollow multilayer resin molded product such as a final molded product of the member or the like can be obtained. Therefore, for example, when the intermediate layer is a gas barrier resin, according to the present invention, a hollow multilayer molded article having a higher gas barrier property than that obtained by a conventional molding method can be obtained. The method for producing a hollow multilayer molded article according to the present invention comprises the steps of: extruding a single-layer or multilayer cylindrical main resin block intermittently, dropping it directly into a cavity of a compression molding apparatus, and similarly forming a sub-resin block. Since it is dropped onto the main resin mass and directly compressed, the equipment can be simplified and the cost can be reduced as compared with the related art, and the material can be effectively molded with less material loss.
[Brief description of the drawings]
FIGS. 1A to 1E are schematic cross-sectional views showing the concept of a method for forming a hollow multilayer resin molded product of the present invention in the order of steps.
FIGS. 2A to 2G are process diagrams showing an embodiment of a molding method for compression-molding a hollow multilayer resin molded product of the present invention.
FIGS. 3A to 3C are schematic cross-sectional views showing the concept of another embodiment of the method for forming a hollow multilayer resin molded product of the present invention in the order of steps.
FIG. 4 is a cross-sectional view of a main part of an apparatus for extruding a main / sub composite resin block according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Multilayer cylindrical molded article 2, 21 Outer resin layer
3,22 Gas barrier resin layer 4,23 Inner resin layer
5, 25 Inner surface coating resin layer 6, 24 Upper end surface coating resin layer
7, 26, 51, 57 Main resin mass 9, 27, 50, 58 Secondary resin mass
10, 28, 52 Main / sub composite resin mass 13, 36, 55 Core type
30 Multi-layer multiple ring die 32 Compression molding device
33 cavity 34 female type
35 plunger 37 columnar part
60 Extruder 63 First die head outlet
64 2nd head ejection port

Claims (8)

A hollow multilayer resin molded article comprising a main resin layer and an inner surface coating resin layer covering an inner surface of the main resin layer, wherein the inner surface coating resin layer is formed by flowing the inner surface coating resin to the main resin layer. A hollow multilayer resin molded product characterized in that it is a resin layer formed. The hollow multilayer resin molded product according to claim 1, wherein the main resin layer comprises two or more multilayer resin layers. The hollow multilayer resin molded product according to claim 1 or 2, wherein the main resin layer has at least one or more gas barrier resins. The hollow multilayer resin molded product according to claim 1, 2 or 3, wherein the hollow multilayer resin molded product is a cylindrical molded product. The hollow multilayer resin molded product according to claim 1, 2 or 3, wherein the hollow multilayer resin molded product is a bottomed molded product. A method of molding a hollow multilayer resin molded product comprising a main resin layer and an inner surface coating resin layer covering the inner surface of the main resin layer, wherein a sub-resin mass formed of an inner surface coating resin is formed on an upper end portion of a cylindrical main resin mass. A hollow multilayer resin characterized in that the inner surface of the main resin layer is coated with the sub-resin by fusing and compressing the sub-resin mass so as to flow along the cylindrical inner layer of the cylindrical main resin mass. A compression molding method for molded articles. The compression molding method for a hollow multilayer resin molded product according to claim 6, wherein the sub-resin mass is ring-shaped or disk-shaped. A method for compression molding a hollow multilayer resin molded product comprising a main resin layer and an inner surface coating resin layer covering an inner surface of the main resin layer, the cylindrical main resin having a resin layer other than the inner surface coating resin layer A step of obtaining a lump, a step of fusing a sub-resin lump made of a resin to be the inner surface coating resin layer to an upper portion of the cylindrical main resin lump to obtain a main-sub-composite resin lump, And a step of compression molding with a core mold.The compression molding step comprises compressing the sub-resin mass by a core mold so as to flow along a cylindrical inner layer of the cylindrical main resin mass, thereby forming a main resin. A method for compression molding a hollow multilayer resin molded product, comprising coating an inner surface of a layer with a sub-resin.

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