Synthetic resin container, and manufacturing method

Abstract

To provide a synthetic resin container which includes appearance that has a desired hue when a restored synthetic resin container is made into a raw material and a new synthetic resin container is manufactured by reusing this, and to provide a manufacturing method of the same.SOLUTION: A synthetic resin container includes: a visible part which appears in appearance in an upright state; and a non-visible part which does not appear in appearance. The synthetic resin container includes: a main material resin layer made of main material resin; and a sub material resin layer made of sub material resin. At least in the visible part, the sub material resin layer covers the main material resin layer and is positioned on the surface side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a container made of synthetic resin and a manufacturing method thereof.

Background Art

[0002] Conventionally, containers made of synthetic resin have been widely used for various purposes. In recent years, due to social demands, recycling technologies for collecting used and discarded containers and reusing them as recycling materials to manufacture new containers made of synthetic resin have been studied.

[0003] For example, Patent Document 1 discloses a technique related to the reuse (recycling) of a discarded packaging container made of thermoplastic resin, which includes a step of crushing and coarsely crushing the discarded packaging container made of thermoplastic resin into small pieces, applying impact crushing force to the obtained small pieces to separate the resin material from the adherents, and sizing the resin material. Patent Document 1 discloses that the discarded containers are sorted by resin materials such as PE / PET / PVC, and whether they are transparent or colored, and then subjected to a crushing process.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the recycling technology of collecting discarded containers and manufacturing new recycled containers from a resin material using the collected products as recycled raw materials, due to the mixing of various collected products, the color of the obtained recycled resin material may become mottled. Therefore, it is difficult to manufacture a recycled container having a desired color from a resin material using collected products in which various products are mixed as recycled raw materials. It is conceivable to sort recycled products by color and flavor to obtain a recycled resin material having a desired color and flavor. However, in that case, there are problems such as the cost of sorting all recycled products by color and flavor, and the difficulty of securing a sufficient amount of raw materials if only the selected desired recycled products are used for recycling. On the other hand, it is required to manufacture recycled containers using recycled materials in a high proportion.

[0006] An object of the present invention is to provide a synthetic resin container and a method for manufacturing the same, which enable an appearance having a desired color and flavor when manufacturing a new synthetic resin container (recycled container) by using a molded product made of a recycled synthetic resin as a raw material and recycling it.

Means for Solving the Problems

[0007] One form of the present invention is a synthetic resin container having a visible portion that appears in the appearance in an upright state and a non-visible portion that does not appear in the appearance, including a main material resin layer made of a main material resin and a sub-material resin layer made of a sub-material resin, and at least in the visible portion, the sub-material resin layer covers the main material resin layer and is located on the surface layer side.

[0008] In addition, one embodiment of the present invention is to sandwich a parison extruded from an extruder through a die head between a pair of split molds, blow air into the parison, and blow-mold it into a predetermined container shape having a mouth portion and a storage portion. When forming the parison by discharging the main material resin from the main material resin die head outlet provided in the die head, in a predetermined region, the auxiliary material resin is discharged from the auxiliary material resin die head outlet provided in the die head so as to be discharged to the outer peripheral side of the resin material discharged from the main material resin die head outlet, and a sub-material resin layer is partially formed on the outer peripheral side of the parison. The parison is sandwiched between the split molds and blow-molded so that a visible portion that appears on the appearance in an upright state among the container shapes is formed at a portion corresponding to the sub-material resin layer, and the sub-material resin layer is formed so as to be located on the surface layer side of the visible portion. It is a manufacturing method of a synthetic resin container.

Effects of the Invention

[0009] According to the present invention, when manufacturing a synthetic resin container having an appearance with a desired color and taste by recycling a recovered synthetic resin molded product as a raw material and reusing it, a synthetic resin container and a manufacturing method thereof can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0012] [First Embodiment] The first embodiment of the present invention will be described. FIG. 1 is an explanatory drawing showing an outline of a container 1 made of synthetic resin according to the present embodiment. The container 1 of the present embodiment is a so-called recycled bottle made of a recycled resin material obtained from a recycled synthetic resin molded product, and has a visible portion 7 that appears on the appearance in an upright state and a non-visible portion 6 that does not appear on the appearance. Here, the visible portion 7 refers to a portion that appears on the appearance in an upright state and can be visually recognized by the user, for example, on a storefront display shelf or the like when provided to the user. On the other hand, the non-visible portion 6 refers to a portion that does not appear on the appearance in the same state and cannot be visually recognized by the user. Note that the "recycled synthetic resin molded product" includes, in addition to synthetic resin molded products (post-consumer materials) such as lids (caps) of used PET bottles separately collected as recyclable waste, scrap materials (pre-consumer materials) generated in the process of manufacturing synthetic resin molded products.

[0013] The container 1 shown in FIG. 1 includes a mouth portion 2 that serves as an injection outlet for the content and a storage portion 3 that stores the content. The storage portion 3 has a body portion 4 connected to the lower end of the mouth portion 2 and a bottom portion 5 that closes the lower end side in the height direction of the body portion 4. In the illustrated example, the container 1 is molded to have a generally cylindrical container shape that tapers toward the bottom portion 5, but the shape of the container 1 is not limited to this.

[0014] Here, the height direction refers to the direction orthogonal to the horizontal plane when the container 1 is placed upright on the horizontal plane with the mouth portion 2 side facing upward, and the up-down, left-right, vertical, and horizontal directions of the container 1 are defined in the state shown in FIG. 1 when it is placed upright with the mouth portion 2 side facing upward.

[0015] In the illustrated example, a thread 21 for attaching a lid (not shown in FIG. 1) by screwing is provided on the outer peripheral surface of the mouth portion 2 formed in a cylindrical shape, but the attachment means of the lid is not limited thereto. By providing an engaging protrusion instead of the thread 21, the lid may be attached by capping.

[0016] Further, a label L is attached to the outer peripheral surface of the container 1 of the present embodiment. That is, the portion covered by the label L in the present embodiment becomes a non-visible portion 6 that does not appear in the appearance in the state where the container 1 is placed upright when provided to the user and cannot be visually recognized by the user, and the non-label attachment portion N excluding the portion covered by the attached label L appears in the appearance in the state where the container 1 is placed upright when provided to the user and becomes a visible portion 7 that can be visually recognized by the user. In FIG. 1, the label L is shown by a broken line. Also, in the illustrated example, a belt-shaped label L that is wound around and attached to the entire circumferential direction of the body portion 4 of the container 1 is shown, but the shape, attachment range, and position of the label L are not limited thereto.

[0017] Here, when using a recycled resin material obtained from a recovered molded article made of synthetic resin (also referred to as a recovered product) as a molding material for a recycled bottle, the color of the resin material becomes a problem. That is, the recovered products are already colored in various ways, and the recycled resin material obtained by collectively washing, pelletizing, etc. them may be mottled. Even if a masterbatch or the like to which a colorant is added is mixed with the mottled recycled resin material, it is difficult to obtain a desired color. Also, the composition of the recovered products included in a certain amount of recovered product group recovered for reuse is, in many cases, assumed to vary depending on the recovered product group. Therefore, the color of the recycled resin material obtained from the recovered products may differ depending on the recovered product group used. When manufacturing a new recycled container using such recycled resin materials having different colors, it may be excessively costly and time-consuming to control the color of the recycled resin material at any time, such as by changing the blending of the recovered product group, to obtain a product having an appearance with a desired color.

[0018] Also, when recovering products after use, it may be considered to sort the recovered products by color to obtain a recycled resin material having a desired color. However, in that case, there may be problems such as the cost of sorting all the recovered products by color, and the difficulty of securing a sufficient amount of raw material because only the sorted products are used as the recycling raw material. For example, when recovering the lids of PET bottles to make a recycled resin material, if the lids are sorted into white lids and non-white lids and used as the recycling raw material, the amount of white lids is less compared to non-white lids. There is a limit to the production volume of white lids, and it is difficult to stably secure a certain amount as the recycling raw material.

[0019] Therefore, in the container 1 according to the present embodiment, it includes a main material resin layer 1a made of a main material resin and a sub-material resin layer 1b made of a sub-material resin. The sub-material resin layer 1b is configured to cover the main material resin layer 1a and be located on the surface layer side, at least in the visual recognition part 7. In the illustrated example, the non-label attachment part N, which is the visual recognition part 7 of the container 1, exists in two locations: a part from the mouth part 2 to the upper end side of the body part 4 and a part from the lower end side of the body part 4 to the bottom part 5. In this way, by making the sub-material resin layer 1b cover the main material resin layer 1a at least in the visual recognition part 7 of the container 1, the main material resin layer 1a does not appear in the appearance when the container is placed upright when provided to the user. Note that FIG. 2 is an explanatory diagram schematically showing a cross-section of a synthetic resin container according to the present embodiment, and shows a cross-sectional schematic diagram cut at the position A-A in FIG. 1. Here, the thicknesses of the main material resin layer 1a and the sub-material resin layer 1b appearing in the cross-section are exaggerated and schematically depicted. Also in other drawings, the thicknesses of the layers appearing in the cross-section are appropriately exaggerated and schematically depicted.

[0020] In the present embodiment, the sub-material resin layer 1b that covers the main material resin layer 1a and is located on the surface layer side is configured as a container 1 made of a sub-material resin obtained from the white lid of a recycled PET bottle. By providing such a sub-material resin layer 1b on the surface layer side of the non-label attachment part N that becomes at least the visual recognition part 7, the non-label attachment part N that becomes the visual recognition part 7 can be made white regardless of the color of the main material resin layer 1a. Or, by kneading a masterbatch with a colorant added to the recycled resin material obtained from the white lid to obtain a sub-material resin having a desired color tone, the non-label attachment part N that becomes the visual recognition part 7 can be made to have the desired color tone.

[0021] As the main material resin for forming the main material resin layer 1a, any thermoplastic resin that can be extrusion-molded and is a recycled resin material obtained by cleaning, pelletizing, etc. a recovered synthetic resin container is not particularly limited. In this embodiment, the recovered molded product used as the main material resin may contain a plurality of colors other than white in the lid of a PET bottle. That is, the main material resin may be a variegated recycled resin material obtained from recycled raw materials in which recycled products of various colors are mixed. Examples of such thermoplastic resins include olefin resins such as low-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, or random or block copolymers of α-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and cyclic olefin copolymers; ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl chloride copolymers, etc. ethylene-vinyl copolymers; styrene resins such as polystyrene, acrylonitrile-styrene copolymers, ABS, α-methylstyrene-styrene copolymers; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, polymethyl acrylate, polymethyl methacrylate; polyamide resins such as nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12; polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and copolyester thereof; polycarbonate resins; polyphenylene oxide resins; biodegradable resins such as polylactic acid; etc. can be exemplified, and those having an extrusion grade melt flow rate are all used. Generally, olefin resins and polyester resins widely used in the packaging field are preferably used. In addition, as the recycled resin material, any material obtained by any treatment method of chemical recycling material, mechanical recycling material, or post-consumer recycling material can be used. In recent recycling technologies, material recycling and chemical recycling are cited as recycling technologies for reuse in molding as resin materials. Among the recycled materials obtained by material recycling, those obtained by washing recovered synthetic resin molded products so that they can be reused are called post-consumer recycling materials, and those with adjusted intrinsic viscosity and removed low molecular weight impurity components are called mechanical recycling materials. Further, the resin material obtained by chemically decomposing the synthetic resin contained in the recovered synthetic resin molded product is called a chemical recycling material. For example, when the recovered synthetic resin molded product is a polyester resin molded product, the polyester resin contained in the polyester resin molded product is depolymerized and decomposed at least to the oligomer component, and the repolymerized polyester resin is called a chemical recycling material.

[0022] As described above, the auxiliary material resin forming the auxiliary material resin layer 1b in the present embodiment is a recycled resin material obtained from the white lids among the recovered PET bottle lids. The lids of PET bottles are often formed from polyethylene or polypropylene, but the auxiliary material resin may be another extrudable thermoplastic resin. For example, as the thermoplastic resin of the auxiliary material resin, the same thermoplastic resins as those exemplified for the main material resin described above can be preferably used.

[0023] From the viewpoint of container molding, the main material resin layer 1a and the auxiliary material resin layer 1b of the container 1 are preferably formed of the same type of resin. As in the present embodiment, when the auxiliary material resin layer 1b is formed of a resin material using, as the auxiliary material resin, a recycled resin material obtained from a group of recovered products collected only from the white lids among the recovered PET bottle lids, the main material resin layer 1a can be formed of a resin material using, as the main material resin, a recycled resin material obtained from a group of recovered products collected from lids of various colors, which are the recovered PET bottle lids. However, if blow molding is possible, the main material resin and the auxiliary material resin are not necessarily limited to the same type of resin. Other resin materials having specific physical properties may also be used.

[0024] According to this embodiment, when manufacturing a new synthetic resin container 1 using a recycled resin material obtained from a recovered molded article made of synthetic resin, by partially providing a secondary material resin layer 1b formed of the secondary material resin obtained from the white lid at least in the non-label-attaching portion N that becomes the visual recognition portion 7, regardless of the color tone of the main material resin layer 1a formed of the main material resin, the color tone appearing on the surface layer of the non-label-attaching portion N that becomes the visual recognition portion 7 can be made white or a desired color tone. Also, by using a mottled recycled resin material obtained from a recycled raw material in which recycled products of various color tones are mixed as the main material resin and using it for most of the formation of the container 1, the proportion of using a large amount of mottled recycled resin with a high production volume can be increased, it becomes possible to stably secure a certain amount of recycled raw material, and it becomes possible to effectively utilize the recycled raw material. Further, it becomes possible to prevent a significant increase in the cost associated with the sorting of the recovered products recovered for recycling for the purpose of obtaining a recycled resin material of a desired color tone.

[0025] Such a synthetic resin container 1 can be manufactured by so-called direct blow molding in which a parison 10 extruded in a tubular shape from an extruder through a die head 110 is sandwiched between a pair of split molds and blow air is blown into the parison 10 to blow mold it into a desired container shape.

[0026] FIG. 3 is an enlarged cross-sectional view of a main part of a part of the parison 10 suitable for blow molding the container 1 according to this embodiment, and schematically shows a cross-section in the vicinity of a region including the secondary material resin layer 10b in the parison 10. In FIG. 3, the right side is the inner peripheral side of the parison 10. The parison 10 according to this embodiment includes a main material resin layer 10a formed from a main material resin, and is configured to partially include a sub-material resin layer 10b formed from a sub-material resin in a predetermined region on the outer peripheral side of the parison 10. Note that since only a part of the parison 10 is shown in FIG. 3, the sub-material resin layer 10b is shown as being formed at one location. However, in this embodiment, the parison 10 is formed such that the sub-material resin layer 1b is formed at two corresponding locations on the parison 10, i.e., at the portion from the mouth portion 2 of the container 1 to the upper end side of the body portion 4 and at the portion from the lower end side of the body portion 4 to the bottom portion 5. The sub-material resin layer 10b (FIG. 3) of the parison 10 in this embodiment is blow-molded to become the sub-material resin layer 1b (FIG. 2) of the container 1.

[0027] When the container 1 is molded by direct blow molding, the parison 10 that partially includes the sub-material resin layer 10b on its outer peripheral side can be formed as follows.

[0028] FIG. 4 is an explanatory diagram showing an outline of a parison molding apparatus 100 for molding a parison 10 for blow-molding the container 1 according to this embodiment. The illustrated parison molding apparatus 100 includes, in a die head 110, a main material resin die head discharge port 111 through which the main material resin is extruded in an annular shape, and a sub-material resin die head discharge port 112 through which the sub-material resin is extruded in an annular shape. In this embodiment, the sub-material resin die head discharge port 112 is arranged such that the sub-material resin discharged therefrom is discharged to the outer peripheral side of the main material resin discharged from the main material resin die head discharge port 111.

[0029] In this embodiment, when forming the parison 10 including the main material resin layer 10a by discharging the main material resin from the main material resin die head discharge port 111 by an extruder (not shown) using such a parison molding apparatus 100, a predetermined amount of the auxiliary material resin is discharged from the auxiliary material resin die head discharge port 112 in a desired region, and then the discharge of the auxiliary material resin is stopped to form the parison 10 including the auxiliary material resin layer 10b in a part of the region. Note that the discharge of the main material resin from the main material resin die head discharge port 111 can be made constant regardless of the discharge of the auxiliary material resin from the auxiliary material resin die head discharge port 112. Alternatively, it may be controlled such that the discharge amount of the main material resin from the main material resin die head discharge port 111 is increased or decreased according to the discharge of the auxiliary material resin from the auxiliary material resin die head discharge port 112. For example, the discharge of the main material resin from the main material resin die head discharge port 111 is reduced and a predetermined amount of the auxiliary material resin is discharged from the auxiliary material resin die head discharge port 112, and then the discharge of the auxiliary material resin is stopped and the discharge of the main material resin is increased to form the parison 10 including the auxiliary material resin layer 10b in a part of the region. To partially form two or more auxiliary material resin layers 10b on the outer peripheral side of the parison 10, when forming the parison 10, the auxiliary material resin may be discharged a plurality of times from the auxiliary material resin die head discharge port 112 provided in the die head 110 to form a parison having the auxiliary material resin layer 10b in a predetermined region.

[0030] When stopping the discharge of the auxiliary material resin, it is preferable to perform suck-back control. That is, when discharging the auxiliary material resin from the auxiliary material resin die head discharge port 112 by the auxiliary material resin extruder 122 and merging it with the main material resin, at an arbitrary timing, the resin pressure in the supply path of the auxiliary material resin supplied from the auxiliary material resin extruder 122 to the auxiliary material resin die head discharge port 112, that is, the communication path 140, is adjusted to perform suck-back control to draw back the auxiliary material resin from the auxiliary material resin die head discharge port 112. By performing suck-back control when stopping the discharge of the auxiliary material resin, partial discharge of the auxiliary material resin can be suitably controlled, and excessive discharge of the auxiliary material resin can be prevented. As a result, the thickness and formation range of the auxiliary material resin layer 10b can be easily adjusted.

[0031] Such partial discharge and suck-back control of the resin material can be performed, for example, by a gear pump 130 capable of irregular operation of forward and reverse rotation as shown in FIG. 4. The extruder 122 that supplies the auxiliary material resin is connected to the gear pump 130, and the auxiliary material resin is supplied to the die head discharge port 112 for the auxiliary material resin of the die head through the communication passage 140 by the forward rotation of the gear pump 130. Further, suck-back control is possible by reversing the gear pump 130. More specifically, the gear pump 130 includes a gear case 131 and two gears 132a, 133a. The gears 132a, 133a rotate while meshing in the direction indicated by the arrows in the figure. At the inflow portion 134, when the meshing of the two gears 132a, 133a is disengaged, the auxiliary material resin supplied from the extruder 122 enters the tooth grooves 132b, 133b. The auxiliary material resin that has entered the tooth grooves 132b, 133b is held between the gear case 131 and the tooth grooves 132b, 133b, and is carried to the outflow portion 135 along the rotation direction, that is, the direction indicated by the arrows in the figure, by the rotation of the gears 132a, 133a. At the outflow portion 135, when the teeth of the gears 132a, 133a mesh again, the auxiliary material resin in the tooth grooves 132b, 133b is extruded and sequentially supplied to the outflow portion 135. By using such a gear pump 130, by appropriately adjusting the extrusion amount of the auxiliary material resin from the extruder 122 and the rotation speed of the gears 132a, 133a, a predetermined amount can be supplied while controlling the flow rate of the auxiliary material resin supplied to the die head 110. Then, suck-back control can be performed by rotating the gears 132a, 133a of such a gear pump 130 in the reverse direction (rotating in the direction opposite to the direction indicated by the arrows in the figure).

[0032] Also, when the communication path 140 for supplying the auxiliary material resin to the die head 110 is long, even if the gear pump 130 functions as a suck-back mechanism, it takes a certain amount of time to draw back the auxiliary material resin from the auxiliary material resin die head discharge port 112, and it is considered difficult to obtain the effect of suck-back control instantaneously. In such a case, as shown in FIG. 4, a second suck-back mechanism 150 can also be provided at a position closer to the die head 110. The specific configuration of this second suck-back mechanism 150 is not limited as long as it can suck the auxiliary material resin in the communication path 140 and adjust the resin pressure in the communication path 140. For example, as shown in the drawing, the piston 150b can be operated in the direction of the arrow in the figure by the cylinder 150a to suck the auxiliary material resin in the communication path 140. The closer the second suck-back mechanism 150 is provided to the auxiliary material resin die head discharge port 112, the more sensitive the suck-back control acts. However, accordingly, the reduction rate of the resin pressure in the communication path 140 becomes large, and as a result, more auxiliary material resin than necessary may be drawn back from the auxiliary material resin die head discharge port 112. And in such a case, the wall thickness of the auxiliary material resin may also decrease. Therefore, in the present embodiment, the suck-back control may be used in combination with the gear pump 130 and the second suck-back mechanism 150. By combining the insensitive suck-back control by the gear pump 130 and the sensitive suck-back control by the second suck-back mechanism 150, it becomes easier to finely adjust the discharge of the auxiliary material resin from the auxiliary material resin die head discharge port 112.

[0033] The parison 10 thus formed is sandwiched between a pair of split molds, the tip side in the extrusion direction of the parison 10 is pinched off and fused, and then blow air is blown into the parison 10 to perform blow molding, whereby the container 1 can be manufactured. In the illustrated example, the parison 10 is sandwiched between the split molds so that the visible part 7 of the non-label attachment part N from the mouth part 2 to the upper end side of the body part 4 and the visible part 7 of the non-label attachment part N from the lower end side of the body part 4 to the bottom part 5 are formed at the part where the sub-material resin layer 10b of the parison 10 is located on the outer peripheral side, and blow molding is performed.

[0034] The formed container 1 has a part where the main material resin layer 1a is exposed on the surface layer side and a part where the sub-material resin layer 1b is exposed on the surface layer side. The label L is attached to the outer peripheral surface of at least the part where the main material resin layer 1a is exposed on the surface layer side of the formed container 1, and the main material resin layer 1a is covered by the label L, so that the label L and the sub-material resin layer 1b appear in the appearance. Thereby, when provided to the user, it can be made into a container having an appearance with a desired color tone along the desired product image in the upright state.

[0035] Note that the label L may be a shrink label attached by heat shrinkage or a seal label attached by an adhesive, and the label L can be attached to the container 1 by a known method.

[0036] [Second Embodiment] Next, a second embodiment of the present invention will be described.

[0037] In the container 1 according to the first embodiment described above, the sub-material resin layer 1b is formed of a sub-material resin obtained from the white lid of the recycled PET bottle. On the other hand, the container 1 according to the second embodiment has a configuration in which the sub-material resin layer 1b is formed of a sub-material resin made of a resin material (virgin material) that has not undergone a recycling process.

[0038] According to this embodiment, when manufacturing a new synthetic resin container 1 using a recycled resin material obtained from a recovered molded article made of synthetic resin, by using virgin material as a secondary resin, regardless of the color tone of the main resin layer 1a formed by the main resin, the color tone appearing on the surface layer of the non-label-attached portion N can be made as desired. Also, by using a mottled recycled resin material obtained from recycled raw materials in which recycled products of various color tones are mixed as the main resin and using it for most of the formation of the container 1, the proportion of using a large amount of mottled recycled resin with a high production volume can be increased, it becomes possible to stably secure a certain amount of recycled raw materials, and it becomes possible to effectively utilize the recycled raw materials. Even if virgin material is used as the secondary resin, the proportion of the secondary resin in the container 1 can be limited to only a part including the surface layer of the non-label-attached portion N which is the visual recognition portion 7, so the usage ratio of the recycled resin material will not be excessively reduced. Also, it becomes possible to prevent a significant increase in the cost associated with sorting the recovered products collected for recycling, which is done for the purpose of obtaining a recycled resin material with a desired color tone.

[0039] Also, according to this embodiment, by forming the surface layer side of the portion including the mouth portion 2 which becomes the visual recognition portion 7 of the container 1 with the secondary resin layer 1b made of virgin material, it is possible to reduce the deterioration of physical properties due to using the recycled resin material for the mouth portion 2 of the container 1. Also, by doing so, it is possible to enhance the adhesion between the mouth portion 2 and the seal surface of a lid body (not shown) and improve the sealing performance of the container 1. In particular, when the top surface of the mouth portion 2 is configured to be in contact with the lid body and sealed, forming the surface layer side of the mouth portion 2 from virgin material is effective for enhancing the adhesion between the mouth portion 2 and the seal surface of the lid body. Also, even when the container 1 is configured to be sealed by the inner peripheral surface of the mouth portion 2 being in contact with the outer peripheral side seal surface of an inner ring provided on the lid body, after molding the container 1, by cutting the inner peripheral surface of the mouth portion 2 using a rotary blade or the like to expose at least a part of the secondary resin layer 1b made of virgin material on the inner peripheral surface of the mouth portion 2, the adhesion between the mouth portion 2 and the seal surface of the lid body can be enhanced.

[0040] This embodiment is different from the first embodiment in the above points, but other configurations are the same as those of the first embodiment, so redundant explanations will be omitted.

[0041] As described above, the present invention has been described by showing preferred embodiments. However, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0042] For example, in the first embodiment described above, the label attachment part is shown as the non-visible part 6 of the container 1, and the non-label attachment part N is shown as the visible part 7 of the container 1. However, the non-visible part 6 and the visible part 7 of the present invention are not limited to the label attachment part and the non-label attachment part N. For example, as shown in FIG. 5, when the nozzle 8 formed separately from the container 1 is attached to the mouth part 2 of the container 1, a part of the mouth part 2 covered by the nozzle 8 can be set as the non-visible part 6, and a part of the mouth part 2 not covered by the nozzle 8, the body part 4, and the bottom part 5 can be set as the visible part 7. Since a part of the mouth part 2 of the container 1 is covered by the nozzle 8, even if the main material resin layer 1a is located on the surface layer side at that location of the container 1, the main material resin layer 1a does not appear in the appearance when provided to the user, and the user cannot visually recognize the main material resin layer 1a.

[0043] Also, as shown in FIG. 6, when the bottom portion 5 of the container 1 has a structure that cannot be visually recognized by the user when the container 1 is placed upright, a part of the bottom portion 5 can be set as the non-visible portion 6, and the other parts, that is, the mouth portion 2, the body portion 4, and a part of the bottom portion 5 can be set as the visible portion 7. In the illustrated example, the outer peripheral surface of the portion surrounded by the dashed-dotted line cannot be visually recognized by the user in the upright state and becomes the non-visible portion 6. In the illustrated example, the container 1 having a shape in which the bottom portion 5 has a bottom surface recessed inward of the container 1 is shown, but the shape of the container 1 having the non-visible portion 6 in at least a part of the bottom portion 5 is not limited to this. In the container 1 in which the bottom surface is difficult for the user to visually observe in the upright state of the container, the said portion can be preferably set as the non-visible portion 6. Even if the main material resin layer 1a is exposed on the surface layer side on the said bottom surface in the upright state of the container 1, the user cannot visually recognize the main material resin layer 1a because the bottom portion 5 is grounded on the grounding surface. In short, as long as the synthetic resin container of the present invention is configured to have a visible portion that appears in the appearance and a non-visible portion that does not appear in the appearance in the upright state, the members attached to the outer peripheral surface side and the container shape can be appropriately changed without being limited to the above-described embodiments.

[0044] In the first embodiment, an example in which the auxiliary material resin is a recycled resin material obtained from the white lid of the recycled PET bottle has been described. However, the auxiliary material resin may be a recycled resin material obtained from a molded product made of synthetic resin other than the lid of the PET bottle. Further, the auxiliary material resin forming the auxiliary material resin layer 1b may be a resin material having a desired color tone, not limited to white. For example, it may be a recycled resin material obtained from a specific selected product group selected by a desired color tone from the recycled synthetic resin molded products. That is, the auxiliary material resin forming the auxiliary material resin layer 1b may be a thermoplastic resin that can be extrusion-molded and may be any resin material having a desired color tone.

[0045] In the first embodiment, the container 1 includes the main material resin layer 1a formed of the main material resin and the auxiliary material resin layer 1b formed of the auxiliary material resin. However, at a part different from the position where the auxiliary material resin layer 1b is provided, the container 1 may be such that a second auxiliary material resin layer 1c formed of still another resin (second auxiliary material resin) covers the main material resin layer 1a and is located on the surface layer side. According to such a container 1, it is possible to obtain an appearance including the auxiliary material resin layer 1b and the second auxiliary material resin layer 1c having a different color tone from the auxiliary material resin layer 1b. For example, in the containers shown in FIGS. 1 and 2, the auxiliary material resin layer 1b is located on the surface layer side in the portion from the mouth part 2 to the upper end side of the body part 4, and the second auxiliary material resin layer 1c is located on the surface layer side in the portion from the lower end side of the body part 4 to the bottom part 5, so that the container 1 having different color tones can be provided for the two non-label mounting parts N.

[0046] Such a container 1 including the auxiliary material resin layer 1b and the second auxiliary material resin layer 1c is formed by forming a parison 10 that includes the main material resin layer 10a, has the auxiliary material resin layer 10b in a predetermined region on the outer peripheral side, and further has the second auxiliary material resin layer in a predetermined region on the outer peripheral side. The formed parison 10 is sandwiched between a pair of split molds, and blow air is blown into the parison 10 to blow-mold it into a desired container shape, whereby it can be manufactured. As shown in FIG. 4, the parison 10 for manufacturing such a container 1 can be manufactured by a parison molding apparatus 100 that further includes a third die head discharge port 113 from which the second auxiliary material resin is extruded in an annular shape in addition to the main material resin die head discharge port 111 and the auxiliary material resin die head discharge port 112. The third die head discharge port 113 is arranged such that the second auxiliary material resin discharged therefrom is discharged to the outer peripheral side of the main material resin discharged from the main material resin die head discharge port 111. The discharge of the second auxiliary material resin from the third die head discharge port 113 can be controlled in the same manner as the discharge of the auxiliary material resin from the auxiliary material resin die head discharge port 112. Using the parison forming apparatus 100 further including a die head discharge port 113, the parison 10 can be formed in the same manner as the manufacturing method of the above-described embodiment, except that the second auxiliary material resin layer 10c is further partially provided on the outer peripheral side of the parison 10. This embodiment is different from the manufacturing method of the above-described embodiment in the above point, but since other configurations are the same as those of the above-described embodiment, duplicate explanations are omitted.

[0047] Further, in the above-described embodiment, when forming the parison 10, a configuration in which the resin material is partially discharged by the gear pump 130 and suck-back control is performed at the time of discharge stop was exemplified, but the partial discharge of the resin material and the suck-back control are not limited to such a mode. For example, a configuration in which partial discharge of the resin material and suck-back control are performed by an accumulator may be used. The specific mode thereof will be described below.

[0048] FIG. 7 is an explanatory diagram showing an outline of another example of a parison molding apparatus 100 for implementing a method for manufacturing a container 1 made of synthetic resin according to the present invention. In this embodiment, an extruder 122 for supplying a secondary resin is connected to a switching section 161 and can intermittently extrude a predetermined amount of the molten secondary resin. The switching section 161 forms a part of a storage section 160 and switches between storage and supply of the secondary resin by a switching valve 165. The secondary resin extruded from the extruder 122 is temporarily stored in a storage section 160 including two accumulators 162 and 163. The switching valve 165 of the switching section 161 alternately connects and disconnects between the extruder 122 and the accumulators 162 and 163, and between the accumulators 162 and 163 and a communication passage 140. The communication passage 140 connects the storage section 160 and a die head 110, and the secondary resin stored in the storage section 160 is supplied through the communication passage 140 to a die head discharge port 112 for the secondary resin of the die head. At this time, the supply of the secondary resin is alternately and intermittently performed from the two accumulators 162 and 163. Specifically, the secondary resin melt-extruded from the extruder 122 is filled into one of the accumulators 162 through the switching valve 165. Then, at the time of discharging the secondary resin, the switching valve 165 is switched and the accumulator 162 is activated, and the secondary resin filled in the accumulator 162 is supplied through the communication passage 140 to the die head discharge port 112 for the secondary resin of the die head. At this time, the switching valve 165 connects one of the accumulators 162 and the communication passage 140, and at the same time, connects the other accumulator 163 and the extruder 122 (the state shown in FIG. 7). Thereby, the secondary resin extruded from the extruder 122 is filled into the accumulator 163. In this way, the secondary resin is alternately stored in the two accumulators 162 and 163 from the extruder 122, and a predetermined amount of the secondary resin is alternately supplied from the accumulators 162 and 163 to the die head discharge port 112 for the secondary resin of the die head.

[0049] Here, the switching operation of the switching valve 165 is performed by a cylinder not shown in the figure, and the operations of the two accumulators 162 and 163 are performed by their respective cylinders 162a, 163a, etc. At this time, by adjusting the operating speeds of the accumulators 162 and 163, the supply speed of the auxiliary material resin, that is, the amount of the auxiliary material resin added to the parison 10, can be adjusted. Thereby, the thickness of the auxiliary material resin layer 10b can be changed.

[0050] When performing the suck-back control, after supplying the auxiliary material resin from the accumulators 162 and 163, the respective cylinders 162a and 163a are operated in the reverse direction to draw back the auxiliary material resin in the communication passage 140 into the accumulators 162 and 163, so that the accumulators 162 and 163 function as a suck-back mechanism. Specifically, after supplying the auxiliary material resin from the accumulator 162, the piston 162b may be operated in the direction of the arrow in the figure to draw back the auxiliary material resin into the accumulators 162 and 163. Also, the second suck-back control as described in the above-described embodiment can be provided at a position closer to the die head. The suck-back control may be used in combination with the accumulators 162 and 163 and the second suck-back mechanism 150.

Explanation of Reference Numerals

[0051] 1 Container 1a Main material resin layer 1b Auxiliary material resin layer 6 Non-visible part 7 Visible part L Label N Non-label mounting part 10 Parison 10a Main material resin layer 10b Auxiliary material resin layer

Claims

1. A synthetic resin container having a visible portion that appears on the exterior in an upright state and a non-visible portion that does not appear on the exterior, comprising a main material resin layer made of a main material resin and a sub-material resin layer made of a sub-material resin, wherein at least in the visible portion, the sub-material resin layer covers the main material resin layer and is located on the surface layer side. A synthetic resin container characterized by this.

2. The synthetic resin container according to claim 1, wherein the main material resin is a recycled resin material obtained from a recovered molded article made of synthetic resin, and the recovered molded article made of synthetic resin includes a plurality of colors.

3. The synthetic resin container according to claim 1 or 2, wherein the sub-material resin is a recycled resin material obtained from a white molded article made of synthetic resin selected from recovered molded articles made of synthetic resin.

4. The synthetic resin container according to claim 1 or 2, wherein the sub-material resin is a virgin material.

5. The synthetic resin container according to claim 1 or 2, wherein a label is attached to a portion where the main material resin layer is located on the surface layer side.

6. When blow molding a parison extruded from an extruder through a die head into a predetermined container shape having a mouth portion and a housing portion by sandwiching the parison between a pair of split molds and blowing blow air into the parison, the main material resin is discharged from a main material resin die head discharge port provided in the die head to form a parison, and in a predetermined region, the sub-material resin is discharged from a sub-material resin die head discharge port provided in the die head so as to be discharged to the outer peripheral side of the resin material discharged from the main material resin die head discharge port, and a sub-material resin layer is partially formed on the outer peripheral side of the parison, the parison is sandwiched between the split molds and blow molding is performed so that a visible portion that appears on the exterior in an upright state of the container shape is molded at a portion corresponding to the sub-material resin layer, and the sub-material resin layer is formed to be located on the surface layer side of the visible portion. A method for manufacturing a synthetic resin container, characterized by this.

7. The method for manufacturing a synthetic resin container according to claim 6, wherein the discharge of the sub-material resin is controlled by sac-back control.

8. The method for manufacturing a synthetic resin container according to claim 6 or 7, wherein the auxiliary material resin is discharged a plurality of times from the auxiliary material resin die head discharge port provided in the die head, and the auxiliary material resin layer is partially formed at two or more locations on the parison.

9. The method for manufacturing a synthetic resin container according to claim 6 or 7, further comprising attaching a label to an outer peripheral surface of a portion of the container shape where the main material resin layer is located on the surface layer side.

Images