JP2019217745A - Preform, plastic bottle, and method for manufacturing the same - Google Patents

Abstract

To provide a plastic bottle, a preform, and a method for manufacturing a preform having gas barrier property.SOLUTION: A preform 1 has a mouth portion 10, a trunk portion 16, and a bottom portion 17 successively in the axial direction. The trunk portion 16 has an intermediate layer. The intermediate layer 20a is between an outer layer 18a and an inner layer 19a. The intermediate layer 20a has gas barrier property and the like. A region of height H1 (H1=5-20 mm) from the mouth top surface 15 and a region of height H2 (H2=3-20 mm) from the bottom of the bottom portion 17 have no intermediate layer 20a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a preform, a plastic bottle, and a method for producing a preform, and more particularly, to a multilayer plastic bottle, a preform, and a method for producing a preform.

  Plastic bottles, especially PET (PolyEthylene Terephthalate) bottles, are often used as containers for filling beverages and the like. In addition, the market for multi-layer bottles in which another material is laminated to supplement the function that polyethylene terephthalate, which is the base material of PET bottles, is insufficient is also expanding.

  Patent Document 1 discloses a low-crystalline ethylene terephthalate having at least one inner and outer layer made of an ethylene terephthalate-based polyester resin and at least one intermediate layer made of a low-crystalline ethylene terephthalate-based polyester resin and an aromatic polyamide-based gas barrier resin. There is disclosed a multilayer preform in which the system polyester resin contains 7.5 to 15 mol% of isophthalic acid in the dicarboxylic acid component and the haze of the portion where the multilayer structure is formed is 5% or more. Further, Patent Document 1 discloses a multilayer stretch blow-molded container obtained by biaxially stretch-blowing a multilayer preform and having a haze of 3% or less in a body portion.

JP 2015-157469 A JP-A 1-254539 JP 2010-12605 A

  According to Patent Literature 1, by forming the inner and outer layers from a crystalline ethylene terephthalate-based polyester resin, it is possible to impart a uniform stretching ratio to the intermediate layer using a low-crystalline polyester resin having poor stretching properties. It is said that a multilayer stretch blow-molded container having excellent mechanical strength can be provided. Further, it is described that the multilayer stretch blow container obtained from the multilayer preform of Patent Document 1 can prevent delamination (delamination) due to a drop impact or the like.

  Patent Document 2 discloses a preform in which the mouth and bottom of the preform are substantially made of polyester, and the other part is made of a laminate of an inner and outer layer of polyester and a gas-barrier thermoplastic resin by using a co-emission method. Is disclosed. Furthermore, by removing the gas barrier thermoplastic resin layer from the mouth and the center of the bottom and forming these portions from a polyester single layer, it is possible to sufficiently perform thermal crystallization of these portions, and it is possible to perform hot water It is described that deformation and expansion of these parts can be almost completely suppressed during sterilization or sterilization.

  Patent Document 3 discloses a test tubular synthetic resin laminated preform in which at least one intermediate layer is laminated on a base layer made of a main resin, and a mouth portion and a bottom portion are regions where the intermediate layer is not laminated. Accordingly, it is said that the problem that the sealing property by the cap in the mouthpiece portion or the rising property of the bottle at the bottom portion is impaired can be effectively prevented.

  However, when the gas-barrier intermediate layer is provided at the upper end of the mouth, there is a problem that cracks occur and are not suitable for drinking. Similarly, when the bottom surface is provided with an intermediate layer, there is a problem that cracks easily occur. Since the bottom face has a low magnification at the time of stretch forming and is relatively thick, there is also a reason that the gas barrier intermediate layer is unnecessary.

  Therefore, an object of the present invention is to provide a preform which has a gas barrier property in a body portion and can be manufactured at low cost, a method of manufacturing the preform, and a plastic bottle obtained by blow molding the preform. is there.

  In order to solve the above problems, the present invention provides a preform having a multilayer structure including a mouth portion, a body portion, a bottom portion, and an annular support ring projecting outward at the mouth portion. It is characterized by being provided continuously from the vicinity of the ring in the trunk portion, being surrounded by the base material layer.

  Further, the intermediate layer has a gas barrier property.

  Further, the intermediate layer is provided in a range from 5 to 20 mm away from the top surface of the mouth to 3 to 20 mm from the bottom.

  Further, the weight of the intermediate layer is 2% by weight to 7% by weight based on the weight of the entire preform.

  Further, the present invention provides a method for manufacturing a preform according to the present invention, wherein a preform is manufactured by co-injection molding in which one material is injected and another material is injected. From the end of the injection until the end of the injection, after the start of the injection of the first molding material, the second molding material is injected for a predetermined time, the second molding material is the first molding material It is characterized by being injected between molding materials.

  Further, the present invention provides a plastic bottle obtained by molding the above-described preform by blow molding.

  The present invention relates to a preform having a multilayer structure having a mouth, a body, a bottom, and an annular support ring protruding outward at the mouth. Are provided in a continuous manner, so that there is no intermediate layer at the mouth and the bottom, so that it is possible to provide a plastic bottle in which the respective portions do not crack. As described above, the intermediate layer is applied to a portion to be stretched at the time of blow molding. However, by the injection molding method described below, it is possible to provide an excellent preform which is less likely to lose its shape due to unevenness of the material at the time of stretching. Can be.

  Further, since the intermediate layer is characterized by having a gas barrier property, it is possible to prevent the oxidation and carbon dioxide gas of beverages and the like contained in the plastic bottle from being reduced, and to provide a plastic bottle having excellent storage properties. Can be.

  Further, since the intermediate layer is provided in a range from 5 to 20 mm from the top surface of the mouth to a range from 3 to 20 mm from the bottom, there is no intermediate layer at the mouth and the bottom, so the crack is generated. A plastic bottle that does not generate can be provided. In particular, the bottom portion has a feature that the gas barrier property can be ensured even without an intermediate layer because the stretching ratio is low and the thickness is large.

Furthermore, by having such a configuration, the intermediate layer is not exposed on the top surface. In other words, the top surface is covered with the base material layer, and the intermediate layer is provided from the position separated from the top surface by 5 to 20 mm toward the bottom. By having such a configuration, when the preform of the present invention is formed into a plastic bottle, a safe plastic bottle for beverages can be obtained.
In addition, by adopting a configuration in which the mouth surface is covered with the base material layer, separation of the base layer and the intermediate layer can be prevented as compared with a case where the intermediate layer is exposed to the mouth surface. When peeling occurs in the mouth due to an impact on the mouth or the like, for example, when the preform of the present invention is used for a beverage bottle, the mouth and the mouth of a person come into contact. For this reason, by adopting a configuration in which the base material layer covers the top surface, it is possible to provide a preform that is a source of a plastic bottle with higher safety.

  Also, since the maximum value of the intermediate layer at the mouth is 20 mm, which is smaller than the height of the mouth at 21 mm, there is an intermediate layer at least over the entire shoulder below the mouth, and the circumferential extensibility in the blow molding is not uniform. Has the effect of eliminating

  Furthermore, since the range from 3 to 20 mm from the bottom has no intermediate layer, a more stable PET bottle is obtained. In other words, if there is an intermediate layer at the bottom, the intermediate layer may be triggered by a shock during transportation or the like, and cracks may occur. If the bottom is cracked, the PET bottle cannot stably stand. Therefore, in the present invention, since there is no intermediate layer at the bottom, it is difficult for the bottom to crack, and a highly stable PET bottle can be provided.

  Further, since the weight of the intermediate layer is from 2% by weight to 7% by weight with respect to the entire preform, the amount of the gas barrier material of the intermediate layer is small, and it becomes a base for a plastic bottle excellent in recyclability. Preform can be provided.

  Further, the manufacturing method of the present invention is a method for manufacturing a preform by co-injection molding in which one material is injected and another material is injected, wherein the first molding material is injected all the time from the start of injection to the end of injection. After the start of the injection of the first molding material, the second molding material is injected for a predetermined time, and the second molding material is sandwiched between the first molding materials and injected. Features. According to this method, the preform of the present invention can be efficiently manufactured.

  Furthermore, since the preform of the present invention is blow-molded to form a plastic bottle, it is possible to provide an excellent plastic bottle having excellent gas barrier properties, high safety, and less deformation and liquid leakage from the mouth. .

It is sectional drawing which showed an example of the preform which concerns on this embodiment. FIG. 2 is a cross-sectional view schematically illustrating a hot runner nozzle of an injection molding apparatus as an example of a preform manufacturing apparatus. 5 is a graph schematically showing the relationship between the injection rate of each co-injected molding material and time. FIG. 3 is a cross-sectional view schematically illustrating a state (step S1) in which each molding material flows from a hot runner nozzle to a cavity. It is sectional drawing which showed the outline of the state (step S3) in which each molding material flows from a hot runner nozzle to a cavity. It is sectional drawing which showed the outline of the state (step S3) in which each molding material flows from a hot runner nozzle to a cavity. It is sectional drawing which showed the outline of the state (step S5) in which each molding material flows from a hot runner nozzle to a cavity. It is sectional drawing which showed the preform and the PET bottle after blow molding typically. It is the front view which showed the PET bottle formed from the preform which concerns on this embodiment. It is sectional drawing of the PET bottle of FIG. It is the perspective view seen from the bottom face side of the PET bottle of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of a preform 1 (preformed body) for forming a PET (PolyEthylene Terephthalate) bottle according to the present embodiment will be described in detail. FIG. 1 is a sectional view showing an example of a preform 1 according to the present embodiment. The preform 1 has a bottomed cylindrical shape, and a mouth portion 10, a body portion 16, and a bottom portion 17 are sequentially provided in the axial direction. The preform 1 is formed into a bottle shape by stretching. At this time, it is preferable to use a known blow molding technique. FIG. 1 shows a plane cut from the mouth 10 to the bottom 17 at the center of the preform 1 in parallel with the axial direction.

  In the following, for convenience of explanation, the direction of the mouth 10 with respect to the bottom 17 in the preform 1 in the state of FIG.

  The mouth 10 has an opening 11 that is opened in a circular shape at the upper end in the axial direction. The opening 11 has an annular top surface 15 and a circular hole 11a. The mouth 10 has a male screw 12, a flap 13, and a support ring 14 on its outer peripheral surface. A male screw 12 for attaching a lid (not shown) spirally protrudes from the outer peripheral surface of the mouth portion 10 toward the radial outside of the preform 1. The flap 13 protrudes in a circular shape outwardly in the radial direction below the male screw 12. The support ring 14 protrudes to the outer side in the radial direction from the fob 13 in a circular shape below the fog 13.

  In general, the shape does not change at the position above the support ring 14 in the axial direction when the preform 1 is formed into a bottle shape. On the other hand, even in a range of a maximum of 20 mm below the support ring 14, it is hardly stretched when being formed into a bottle. This range is preferably 10 mm. Therefore, here, the range where the shape hardly changes when the preform 1 is molded into a bottle shape is defined as the mouth portion 10. As illustrated in FIG. 1, the mouth portion 10 has a substantially true cylindrical shape in which the inner diameter and the outer diameter of the portion below the support ring 14 in the axial direction are substantially the same in the upper and lower directions in the axial direction. Is also good.

  As described above, the shape of the mouth portion 10 does not change even after being formed by the blow molding machine. Here, the dimensions of each part such as the inner diameter, the outer diameter (corresponding to the thread root diameter), and the thread diameter of the mouth part 10 of the preform 1 are not particularly limited. However, it is preferable that the dimensions are the ones used as standard for beverage bottles, because the versatility of the existing lid and the sealing property of the beverage bottle can be ensured. For this reason, it is preferable that the opening 10 has a size corresponding to, for example, the PCO1810 standard or the PCO1881 standard.

  The body portion 16 is formed in a substantially true cylindrical shape having an inner diameter and an outer diameter that are substantially the same size in the upper and lower directions in the axial direction. However, the body portion 16 may be provided with a draft that is a slope for facilitating removal from the mold used for manufacturing the preform 1, that is, for facilitating release. Further, the inner diameter and the outer diameter of the body 16 may slightly change in the vertical direction in the axial direction. Furthermore, the upper and lower portions of the body portion 16 in the axial direction may have substantially the same outer diameter.

  The bottom part 17 is formed in an outwardly curved substantially hemispherical shape. The bottom 17 may have a conical shape, a cylindrical shape with rounded corners, or another shape.

  The outer diameter of the body 16 is preferably 12 mm or more and 30 mm or less in that an existing device can be used. Further, the length from the lower surface of the support ring 14 to the lower end of the bottom portion 17 is preferably 35 mm or more and 105 mm or less in that an existing device, particularly a blow molding machine can be used.

  The preform 1 includes a body 16 having a multilayer structure and an intermediate layer 20a between an outer layer 18a and an inner layer 19a. The preform 1 illustrated in FIG. 1 has an intermediate layer 20a in a region from the vicinity of the support ring 14 to a position short of the bottom 17. A region having a height H1 from the mouth surface 15 (H1 = 5 to 20 mm) and a region having a height H2 from the bottom of the bottom portion 17 (H2 = 3 to 20 mm) do not have the intermediate layer 20a. I have. In this manner, the structure in which the intermediate layer is not provided in the region above the support ring of the mouth can prevent the mouth from cracking. In addition, cracks can be prevented by using a structure having no intermediate layer at the bottom. Since the bottom portion has a low magnification at the time of stretch forming and is thick, the gas barrier property is also ensured, for example.

  The preform 1 has no adhesive layer or adhesive between the intermediate layer 20a and each of the outer layer 18a and the inner layer 19a. Therefore, the recycling of the preform 1 after use is not hindered. On the other hand, since the layers are not firmly bonded, there is a possibility that delamination may occur due to external force. Therefore, since the intermediate layer 20a is configured so as not to extend to the end of the opening 10, the end of the interface of each layer which is likely to be a starting point of destruction is not exposed on the top surface 15 and delamination is less likely to occur. .

  As illustrated in FIG. 1, in the preform 1, the intermediate layer 20 a is provided continuously from the height H <b> 1 near the support ring of the mouth portion 10 to the height H <b> 2 at the bottom portion. At this time, if the intermediate layer 20a has, for example, gas barrier properties, a plastic bottle having excellent gas barrier properties can be provided.

  The intermediate layer 20a has a uniform thickness. By being provided uniformly, even when heat is applied and the base material layer is deformed, there is little distortion. However, the intermediate layer 20a may be provided in the base material layer of the support ring 14 of the mouth portion 10 so as to protrude from the mouth portion 10 in the radial direction. By doing so, the preform 1 can be easily manufactured. As for the configuration of the opening 10, the intermediate layer is surrounded by the base material layer, and the intermediate layer is provided to protrude into the base material layer of the support ring 14 like a flange, and the thickness of the intermediate layer 20a in other portions is uniform. May be provided.

  In the preform 1 for a 280 ml PET bottle, the weight of the intermediate layer 20a is preferably 2 to 7% by weight based on the value obtained by dividing the weight of the intermediate layer 20a from the total weight. Thereby, the recyclability of the PET bottle 2 in which the preform 1 is formed by blow molding or the like is improved. This ratio can vary depending on the size of the plastic bottle. Even for 2 liter PET bottles, if it is 3% by weight, there is no difference in recyclability from the preform 1 for 280 ml PET bottles described above.

  Materials that exhibit various functions can be selected for the intermediate layer 20a. For example, for the intermediate layer 20a, a material that imparts a property of blocking light such as ultraviolet rays or a gas barrier property such as water vapor can be used. Here, it is preferable to use a gas barrier material for the intermediate layer 20a. Here, the gas barrier material is a mixed material of nylon and a metal complex, and a material having a ratio of nylon to metal complex of 11: 1 to 20: 1 may be used. Further, a thermoplastic polyester resin having excellent heat resistance can also be used as the material of the mid layer 20a of the present invention.

  Examples of the material of the outer layer 18a and the inner layer 19a of the base layer of the illustrated preform 1 include polyolefin such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene, and ethylene-vinyl alcohol. Various thermoplastic resins that can be blow-molded, such as polylactic acid or the like, made of a copolymer, a plant, or the like can be used. However, it is preferable that the outer layer 18a and the inner layer 19a are PET layers mainly composed of polyester such as polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyarylate, particularly, polyethylene terephthalate. The above-mentioned resin is blended with various additives such as a coloring agent, an ultraviolet absorber, a release agent, a lubricant, a nucleating agent, an antioxidant, and an antistatic agent as long as the quality of the molded product is not impaired. be able to.

  As the ethylene terephthalate-based thermoplastic resin constituting the outer layer 18a and the inner layer 19a of the preform 1, ethylene terephthalate units occupy most of the ester repeating portion, generally 70 mol% or more, and have a glass transition point (Tg). Is not less than 50 ° C. and not more than 90 ° C., and the melting point (Tm) is preferably not less than 200 ° C. and not more than 275 ° C. As an ethylene terephthalate-based thermoplastic polyester, polyethylene terephthalate is particularly excellent in terms of pressure resistance and the like, but in addition to ethylene terephthalate units, is composed of a dibasic acid such as isophthalic acid or naphthalenedicarboxylic acid and a diol such as propylene glycol. Copolyesters containing small amounts of ester units can also be used.

  Polyethylene terephthalate has the largest production among thermoplastic synthetic resins. The polyethylene terephthalate resin has various properties such as excellent heat resistance, cold resistance, chemical resistance, and abrasion resistance. Furthermore, polyethylene terephthalate resin has a lower ratio of petroleum to its raw material than other plastics, and can be recycled. As described above, according to the configuration including polyethylene terephthalate as a main component, a material having a large production amount can be used, and various excellent characteristics thereof can be utilized.

  Polyethylene terephthalate is obtained by condensation polymerization of ethylene glycol (ethane-1,2-diol) and purified terephthalic acid. As a polymerization catalyst for polyethylene terephthalate, it is preferable to use at least one of a germanium compound, a titanium compound, and an aluminum compound. By using these catalysts, it is possible to form a container having higher transparency and excellent heat resistance than using an antimony compound.

  If the amount of the intermediate layer 20a with respect to the entire preform 1 is too large, recycling after use of the preform 1 is hindered. On the other hand, if the amount of the intermediate layer 20a relative to the entire preform 1 is too small, the injection moldability will decrease. More specifically, it is difficult to fill the intermediate layer 20a during the molding of the preform 1, and forcibly pushing the intermediate layer 20a undesirably causes deterioration and uneven thickness. Therefore, the ratio of the intermediate layer 20a to the entire preform 1 needs to be at least 0.5% by weight or more. More preferably, it is between 2 and 7 weight percent.

  The intermediate layer 20a is not limited to a single layer but may be a multilayer. For example, the intermediate layer 20a may include a plurality of heat-resistant layers in addition to a gas barrier layer containing an oxygen absorbing material. For example, the preform 1 may have a five-layer structure (PET layer (outer layer 18a) / oxygen barrier layer / heat-resistant layer / oxygen barrier layer / PET layer (inner layer 19a)). The number of intermediate layers 20a may be further increased, and the preform 1 may have a maximum of seven layers. Since the intermediate layer 20a is configured as a multilayer, the function of the intermediate layer 20a can be further enhanced, and the intermediate layer 20a can have a plurality of functions.

  Then, next, an example of a method for manufacturing the preform 1 will be described in detail. FIG. 2 is a cross-sectional view schematically showing a hot runner nozzle 31 of an injection molding device as an example of a device for manufacturing the preform 1. The injection molding apparatus includes a heating cylinder (not shown) having a screw therein, a hot runner nozzle 31, and a mold 32. The injection molding apparatus is configured such that the molding material is melt-plasticized by being heated to, for example, 270 ° C. to 300 ° C. in a heating cylinder, and is sent out to a mold 32 via a hot runner nozzle 31 by a screw. ing.

  The hot runner nozzle 31 is configured to be long in the axial direction. The hot runner nozzle 31 has a straight flow path 33a, a first cylindrical flow path 33b, a second cylindrical flow path 34, and a check valve 35 which is an example of an on-off valve. Each channel extends substantially in the axial direction. The hot runner nozzle 31 further has a first inlet 36, a second inlet 37, and an outlet 38.

  The injection port 38 is formed at the center of one end of the hot runner nozzle 31. The injection port 38 communicates with the mold 32. On the other hand, the first injection port 36 and the second injection port 37 are respectively formed on the side surface near the other end of the hot runner nozzle 31. Each of the first inlet 36 and the second inlet 37 is connected to a separate heating cylinder. That is, the hot runner nozzle 31 is configured to be able to inject the first molding material and the second molding material from the first injection port 36 and the second injection port 37, respectively. The molding material flows from the first inlet 36 and the second inlet 37 toward the outlet 38.

  The straight flow path 33 a communicates with a flow path extending in the radial direction from the first injection port 36, and linearly extends from the center of the hot runner nozzle 31 to the injection port 38. After branching off from the straight flow path 33a, the first cylindrical flow path 33b passes radially outward of the straight flow path 33a and at a first junction 39a close to the injection port 38, the straight flow path 33a Has joined. The second cylindrical flow path 34 communicates with a flow path extending in the radial direction from the second inlet 37, and extends between the straight flow path 33a and the first cylindrical flow path 33b to form the first cylindrical flow path 33b. At the second junction 39b upstream of the junction 39a.

  The hot runner nozzle 31 has a check valve 35 for closing the second cylindrical flow path 34 at a second junction 39b. The check valve 35 responds to the difference in injection pressure between the first molding material passing through the straight flow path 33a and the second molding material passing through the second cylindrical flow path 34 at the second junction 39b. It is configured to move in the axial direction. The check valve 35 is configured to open the second cylindrical flow path 34 when the injection pressure of the second molding material is high. The check valve 35 may have another configuration as long as such an action is achieved.

  The mold 32 divided into a plurality of parts has a cavity 32 a which is a cavity having a shape corresponding to the preform 1, and a gate 32 b at a position corresponding to the bottom 17 of the preform 1. The cavity 32a communicates with the injection port 38 of the hot runner nozzle 31 via a gate 32b. The mold 32 is provided with a heater (not shown) for heating the mold 32 and a cooler (not shown) for cooling the mold 32. The mold 32 is configured such that the molten molding material is injected into the cavity 32a heated by the heater and pressed, and then cooled by the cooler to form the preform 1.

  FIG. 3 is a graph schematically showing the relationship between the injection rate of each co-injected molding material and time. The injection rate is indicated by the mass [g] of each molding material injected per unit time [s]. In FIG. 3, the first molding material a is indicated by a solid line, and the second molding material b is indicated by a broken line. Here, polyethylene terephthalate (hereinafter, referred to as PET resin a) is injected into the first molding material, and a mixture of nylon and a metal complex (hereinafter, gas-barrier resin) is injected into the second molding material. b) is shown. Then, for example, as shown in FIG. 3, the method of manufacturing the preform 1 includes a step of injecting the first molding material (step S1) and a step of injecting the second molding material at a higher injection rate than the first molding material. And a step of injecting the first molding material at a higher injection rate than the second molding material (Step S5). According to this method, the function of the intermediate layer 20a of the manufactured preform 1 can be reduced even after the stretching of the intermediate layer 20a, and the amount of the molding material of the intermediate layer 20a can be reduced. By performing injection molding in accordance with the injection timing shown in this figure, it is possible to mold one form of the preform of the present invention in which the intermediate layer 20a exists in the body from the vicinity of the support ring.

  First, PET resin a is injected (step S1). FIG. 4 is a sectional view schematically showing a state (step S1) in which each molding material flows from the hot runner nozzle 31 to the cavity 32a. The PET resin a is supplied from the first inlet 36 (see FIG. 2) through one of the linear flow path 33a (PET resin a1) and the first cylindrical flow path 33b (PET resin a2). They merge at the first junction 39a, and then flow in the order of the injection port 38 and the gate 32b to fill the cavity 32a. As illustrated in FIG. 4, the flow of the PET resin a via each of the linear flow path 33a (PET resin a1) and the first cylindrical flow path 33b (PET resin a2) causes the PET resin layer A1, And the PET resin layer A2, and the cavity 32a is filled as the PET resin layer A.

  At this stage, the gas barrier resin b has not been injected, and the second cylindrical flow path 34 is closed by the check valve 35 receiving the injection pressure of the PET resin a1.

  Next, the PET resin a is injected at a reduced injection rate to a predetermined injection rate (step S2). The lowered injection rate is determined in consideration of the injection rate of the gas barrier resin b injected in the next stage. Here, if the PET resin a is injected at the injection rate lowered in advance, and if there is no dimensional defect of the mouth 10 or shaping defects such as sink marks, step S2 may be omitted.

  Next, the gas barrier resin b is injected at a higher injection rate than the PET resin a (step S3). FIG. 5 is a cross-sectional view schematically showing a state where each molding material flows from the hot runner nozzle 31 to the cavity 32 (Step S3). The check valve 35 moves by the pressure at which the gas barrier resin b is injected, and the second cylindrical flow path 34 is opened. Then, as exemplified in FIG. 5, a gas barrier resin layer B is provided between the PET resin layer A1 passing through the straight flow path 33a and the PET resin layer A2 passing through the first cylindrical flow path 33b. Is formed. The gas barrier resin layer B flows at a higher speed than the PET resin layers A1 and A2 because the gas barrier resin layer B flows without contacting the molding die and the temperature does not decrease and the viscosity does not increase.

  Next, the gas barrier resin b is injected while the injection rate is maintained at the same level (step S3). FIG. 6 is a cross-sectional view schematically showing a state where each molding material flows from the hot runner nozzle 31 to the cavity 32a (Step S3).

  Next, the injection rate of the gas barrier resin b is gradually reduced to zero, and the injection is performed so that the injection rate of the PET resin a is gradually increased (step S4). As the injection rate of the gas barrier resin b gradually decreases, the gas barrier resin layer B is cut off after being injected so as to become gradually thinner. When the injection rate of the gas barrier resin b becomes zero, the check valve 35 moves, and the second cylindrical flow path 34 is closed.

  Next, the PET resin a is injected while being maintained at a predetermined injection rate (step S5). FIG. 7 is a cross-sectional view schematically showing a state where each molding material flows from the hot runner nozzle 31 to the cavity 32a (step S5). As illustrated in FIG. 7, the gas barrier resin layer B is pushed in by the PET resin layer A.

  Finally, the PET resin a is injected until the inside of the cavity 32a is filled. When the injection rate of the PET resin a gradually decreases, and when the inside of the cavity 32a is filled, the injection rate of the PET resin a becomes zero, and thereafter, pressure is maintained so that the PET resin a does not flow backward (step S6). ). After the molding material is cooled inside the cavity 32a, the mold 32 is opened, and the molded preform 1 is taken out.

  In addition, the injection pressure and injection rate of each molding material are appropriately designed according to the difference in their viscosities.

  As described above, the method for manufacturing the preform 1 according to the present embodiment includes a procedure for uniformly forming the intermediate layer 20a.

  Note that the manufacturing method may be another method. For example, by plasticizing and extruding a PET resin a, a gas barrier resin b, and a PET resin a in this order, a molten resin block (a billet) in which the gas barrier resin b is included in a U-shape is formed, and this is compression-molded. The method by which the preform 1 is manufactured may be used.

  The formed preform 1 may be box-stacked, so-called palletized, and temporarily stored in a warehouse or the like, or may be directly proceeded to the next step. That is, the so-called cold parison method (two-stage method) in which the molding of the preform 1 and the blow molding are performed in different places or apparatuses may be used, and the molding of the preform 1 and the blow molding are the same. A so-called hot parison method (one-stage method) performed at a place or an apparatus may be used. Further, the manufacturing process from the molding of the preform 1 to the filling of the contents may be continuous in-line.

  Next, an example of a method for forming a bottle from the preform 1 according to the present embodiment will be described in detail. When the preform 1 is formed into a bottle shape, first, the preform 1 is heated.

  The heating device includes a transfer device and a heater. The transport device is configured to transport the preform while rotating it around the axis of the preform in order to uniformly heat the preform in the circumferential direction. The heater is constituted by a plurality of, for example, halogen lamps, and is configured to heat the preform to a temperature suitable for blow molding, for example, 80 ° C to 140 ° C. Further, the heating device may include a reflection plate for reflecting heat from the heater to the preform, a shielding member for preventing heat from the heater from escaping to the outside of the heating device, and the like.

  The heated preform 1 is then molded into a plastic bottle, for example a PET bottle 2, by a blow molding machine. FIG. 8 is a cross-sectional view schematically showing the preform 1 and the PET bottle 2 after blow molding. The biaxial stretching blow molding device 50 as an example of the blow molding machine includes a mold 51, a stretching rod 52, a high-pressure air supply device (not shown), and a control device (not shown) for controlling these devices. Although a downward blow molding method is illustrated in FIG. 8, an upward blow molding method in which the material is less likely to be affected by gravity may be used.

  Here, the PET bottle 2 has an upper part 30, a body part 70, and a bottom part 80. Approximately before and after blow molding, the mouth 10 of the preform 1 corresponds to the upper portion 30 of the PET bottle 2, and the bottom 17 of the preform 1 corresponds to the bottom 80 of the PET bottle 2.

  The mold 51 has a shape corresponding to the PET bottle 2 to be formed. For example, a body mold 51 a which is formed in half corresponding to the body 70 and a bottom mold corresponding to the bottom 80. 51b. The surface temperature of the mold 51 is configured to be controlled at, for example, 30 ° C. to 130 ° C. in accordance with the use of the PET bottle 2, particularly heat resistance.

  The extension rod 52 is configured to be able to expand and contract inside the mold 51. The extension rod 52 is configured to extend the body 16 of the preform 1 in which the mouth 10 is attached to the mold 51 in the longitudinal (axial) direction. The high-pressure air supply device is configured to blow out the high-pressure air h whose temperature has been adjusted. The high-pressure air h may be supplied to the inside of the preform 1 attached to the mold 51, and may be blown out from the stretching rod 52, or may be blown out from a member different from the stretching rod 52. The high-pressure air h is configured to extend the body 16 of the preform 1 in the lateral (radial) direction and to lower the surface temperature of the body 16 after the stretching.

  The heated preform 1 is mounted on a mold 51 of a biaxial stretch blow molding device 50. Thereafter, the trunk 16 of the preform 1 mounted on the mold 51 is stretched in the longitudinal direction by the stretching rod 52. At this time, the longitudinal stretching ratio from the preform 1 to the PET bottle 2 is preferably 1.8 times or more and 4.0 times or less.

  Here, the longitudinal stretching ratio is a ratio of the length from the lower surface of the support ring 14 of the PET bottle 2 to the lower end of the bottom portion 80 to the length from the lower surface of the support ring 14 of the preform 1 to the lower end of the bottom portion 17. . The molecules of the preform 1 having an amorphous structure, which is an aggregate of an amorphous part and a crystalline part, undergo orientation crystallization by stretching, and as a result, the strength, rigidity, heat resistance, and the like of the PET bottle 2 increase. When the longitudinal stretching ratio is less than 1.8, the molecular orientation of the PET bottle 2 (preform 1) does not increase, while when the longitudinal stretching ratio is 4.1 or more, the PET bottle 2 is formed. It becomes difficult.

  Further, the body 16 of the preform 1 stretched in the longitudinal direction is stretched by the high-pressure air h in the transverse direction until it hits the mold 51. At this time, the transverse stretching ratio from the preform 1 to the PET bottle 2 is preferably 1.5 times or more and 6.0 times or less.

  Here, the transverse stretching ratio is a ratio of the trunk diameter of the PET bottle 2 to the trunk diameter of the preform 1 to the trunk diameter of the trunk 16. The distance between the centers of the thicknesses of the opposed wall surfaces of the body 70 is defined as the body diameter of the body 70. The molecules of the preform 1 are similarly oriented and crystallized by stretching in the lateral direction, and as a result, the strength, rigidity, heat resistance and the like of the PET bottle 2 are increased. When the transverse stretching ratio is less than 1.5, the molecular orientation of the PET bottle 2 (preform 1) does not increase, while when the transverse stretching ratio is 6.1 or more, the PET bottle 2 is formed. It becomes difficult.

  As described above, molding by the biaxial stretch blow molding apparatus 50 is performed when the stretching ratio in the longitudinal direction is 1.8 times or more and 4.0 times or less, and the stretching ratio in the horizontal direction is 1.5 times or more and 6.0 times or less. According to the configuration of the biaxial stretch blow molding, a PET bottle 2 that is reduced in weight with better blow moldability can be formed from the preform 1.

  As described above, in the PET bottle 2 according to the present embodiment, the preform 1 is formed into a bottle shape by the biaxial stretch blow molding device 50. Then, by using the biaxial stretch blow molding apparatus 50, it is possible to effectively form the lightweight PET bottle 2 with good blow moldability from the preform 1 according to the present embodiment.

  In the present embodiment, the use of the molded PET bottle 2 is not limited. Therefore, the PET bottle 2 may be formed to have pressure resistance, oxygen barrier properties, and the like.

  Next, the configuration of the PET bottle 2 formed from the preform 1 according to the present embodiment will be described in detail. FIG. 9 is a front view showing a PET bottle 2 formed from the preform 1 according to the present embodiment. The PET bottle 2 illustrated in FIG. 9 is a round bottle having a substantially circular cross section in a direction perpendicular to the axial direction. As described above, the PET bottle 2 has the upper portion 30, the body 70, and the lower portion 80. Then, as described above, the configuration of the upper portion 30 of the PET bottle 2 is similar to the configuration of the mouth portion 10 of the preform 1.

  The upper part 30 serves as a filling port and a spout for the contents, and the PET bottle 2 is sealed by attaching a lid (not shown) to the upper part 30.

  The body 70 has a substantially frustoconical shape in which a portion adjacent to the upper portion expands in diameter from above to below. In the trunk portion, a portion between the substantially frustoconical portion and the bottom has a cylindrical shape. The body 70 may have a pressure absorbing panel, a horizontal groove, and a vertical groove.

  The upper side of the bottom part 80 continues to the lower side of the body part 70. The bottom portion 80 illustrated in FIG. 11 has a so-called petaloid shape. The bottom portion 80 has a concave portion 81, a leg portion 82, a valley portion 83, and the like. The concave portion 81 located at the center in the radial direction of the bottom portion 80 is configured to protrude toward the inside (upper side in the axial direction) of the PET bottle 2. The leg portion 82 extends radially outward from the concave portion 81 toward the lower side in the axial direction. The leg 82 serves as a ground surface of the PET bottle 2. A valley 83 is formed between the adjacent legs 82. The valley portion 83 extends radially outward from the concave portion 81 and upward in the axial direction. The configuration of the bottom portion 80 is not limited to the example illustrated in FIG. 11, and may be a shape corresponding to the contents, for example, a shape in which ribs are radially provided.

  FIG. 10 is a sectional view of the PET bottle 2. Further, FIG. 10 shows the region A of the upper portion 30 in an enlarged manner. The PET bottle 2 is multilayered from the vicinity of the support ring 14 to the body 70, and has an intermediate layer 20 between the outer layer 18 and the inner layer 19. The intermediate layer starts from the vicinity of the support ring 15 which is 15 mm below the top surface, and the intermediate layer exists up to the trunk.

  By providing the gas barrier intermediate layer on the body, a PET bottle capable of suppressing the oxidation of the contents can be obtained, which is preferable.

  The type, material, amount, layer configuration, and the like of the intermediate layer 20 are the same as those of the preform 1 described above.

  The shape of the PET bottle 2 especially below the support ring 14 is not limited to the example shown in FIG. 9 and the like, and may be any shape as long as it is formed by blow molding the preform 1. . For example, in the present embodiment, the round bottle shown in FIG. 9 can be suitably formed. However, the plastic bottle formed in the present embodiment is not limited to a round bottle, and may be a square bottle. Further, the width of the body 70 may be widened downward. In addition, the shape of the pressure absorbing panel, the horizontal groove, and the vertical groove formed on the body 70 can be freely designed.

  The PET bottle 2 according to the present embodiment is not limited by size, and can be applied to various sizes. For example, the volume of the PET bottle 2 may be not less than 100 ml and not more than 1000 ml, and is particularly suitable for the PET bottle 2 having a volume of not less than 200 ml and not more than 700 ml. The total height of the PET bottle 2 may be 120 mm or more and 260 mm or less, and the body diameter of the body 70 may be 40 mm or more and 75 mm or less.

  Furthermore, the PET bottle 2 according to the present embodiment can be suitably used for a lightweight bottle. The mass of the PET bottle 2 is preferably, for example, 8 g or more and less than 16 g for an internal volume of 200 ml, and 10 g or more and less than 20 g for an internal volume of 550 ml. And from the viewpoint of maintaining the strength of the PET bottle 2 while maintaining the function of the mid layer 20 while maintaining the lightness, the value of the mass ratio to the inner volume of the PET bottle 2 is 0.0180 g / ml or more. It is preferably 0.0800 g / ml or less.

  A plastic bottle can be manufactured by blow molding the preform 1 in which the above-described material is injection-molded. Then, by using polyethylene terephthalate as the material, the PET bottle 2 as an example of the plastic bottle according to the present embodiment is manufactured. And a filling body is comprised by PET bottle 2 and the liquid to be filled. The filling body is manufactured by filling a liquid such as a beverage or a seasoning from the upper part 30 of the PET bottle 2 and sealing it with a lid (not shown) mounted on the upper part 30.

  The method for filling the PET bottle 2 with the contents is not limited. Therefore, the PET bottle 2 may be used for hot filling or for aseptic filling.

  As described above, the PET bottle 2 has the upper part 30, the body part 70, and the bottom part 80 sequentially in the axial direction, the body part 70 is configured in a multilayer, and the intermediate layer 20 is disposed between the outer layer 18 and the inner layer 19. Having. According to such a configuration, it is possible to reduce the amount of the molding material of the intermediate layer 20 while securing the function of the intermediate layer 20.

  Hereinafter, the present disclosure will be described in more detail and specifically with reference to examples. However, the present disclosure is not limited to the following embodiments.

<Material and manufacturing method>
[Example 1]
Polyethylene terephthalate (PET resin a) is used for the outer layer 18 and the inner layer 19, and a mixture of nylon and a metal complex (gas barrier resin b) is used for the intermediate layer 20, and a total of 22 g of the preform 1 is used. It was produced by the method shown in this specification such as FIG. The ratio of the gas barrier resin b to the entire preform 1 was 3% by weight. The weight of the preform was 22 g.

  Then, from the preform 1, a PET bottle 2 having a full filling volume of 295 ml as shown in FIG. 9 and the like was produced by blow molding. After the PET bottle 2 was filled with 280 ml of water, a lid was attached, and a filled body was produced.

  The intermediate layer 20 of the preform 1 according to Example 1 was provided continuously from a position about 10 mm from the top surface 15 to the trunk 70.

[Comparative Example 1]
In Comparative Example 1, a single-layer preform was manufactured using only the PET resin a without using the gas barrier resin b. The weight of the preform was 22 g. Then, a PET bottle 2 shown in FIG. After the PET bottle 2 was filled with 280 ml of water, a lid was attached, and a filled body was produced.

[Comparative Example 2]
In Comparative Example 2, the gas barrier resin b was used, and its ratio was 25% by weight. The intermediate layer 20 was provided continuously from a position about 10 mm from the top surface 15 to the trunk 70.

[Comparative Example 3]
In Comparative Example 3, the gas barrier resin b was used, and the ratio was 3% by weight. The intermediate layer 20 was provided continuously from a position approximately 2 mm from the mouth surface 15 to the trunk 70.

<Evaluation method>
(Amount of material used for gas barrier layer)
It was determined whether or not the reduction of the used amount was achieved based on the mass of the material of the gas barrier layer used in the PET bottles of Example 1 and Comparative Examples 1 to 3. In the determination of the reduction in the amount used, a threshold value was set as to whether the percentage of the gas barrier resin b in the entire PET bottle (each preform) was greater than or less than 20 wt%. Table 1 shows the results of the evaluation on the reduction rate of the material usage of the gas barrier layer in each PET bottle. ◎: The reduction rate is extremely high, ：: The reduction rate is high, ×: The reduction rate is low. It is written.

(Gas barrier properties)
In each of the PET bottles of Example 1 and Comparative Examples 1 to 3, it was determined whether the gas barrier properties were sufficiently achieved. To determine the gas barrier properties, each PET bottle was filled with green tea, capped, and stored at 40 ° C. for 1 month in an insulated box. Thereafter, the results of measuring the color difference ΔE are shown in Table 1. When the color difference is 5 or more, x is shown when the color difference is less than 5.

(Mouth crack)
Green tea was filled in 100 PET bottles of Example 1 and Comparative Examples 1 to 3 and wound with a capper to determine cracks in the mouth. The results are shown in Table 1. The number of cracks is represented by 0, and the number of cracks is represented by x.

(Comprehensive evaluation)
Based on the amount of the material used for the gas barrier layer described above and the gas barrier properties, comprehensive evaluations of the PET bottles (fillers) of Example 1 and Comparative Examples 1 to 3 were made. Table 1 shows the results of the comprehensive evaluation. The overall evaluation is indicated by ◎: extremely good, ：: good, ×: no suitability. The results of the evaluation of Example 1 and Comparative Examples 1 to 3 are shown. wt% is the weight percent of the gas barrier layer used. t is the position from the mouth of the gas barrier layer in mm.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for various plastic bottles that are filled with a liquid. However, the present invention is not limited to the embodiments and examples described above. The plastic bottle of the present invention is, for example, water, green tea, oolong tea, black tea, coffee, fruit juice, various non-carbonated drinks such as soft drinks, carbonated drinks, or seasonings such as soy sauce, sauce, mirin, cooking oil, liquors. It is useful for containing foods, detergents, shampoos, cosmetics, pharmaceuticals, and any other contents. Further, in the present disclosure, particularly, a gas barrier intermediate layer for preventing oxidation of the contents is provided, so that a plastic bottle excellent in preventing the contents from being oxidized and having high productivity can be provided.

1 Preform 2 PET bottle (plastic bottle)
DESCRIPTION OF SYMBOLS 10 Mouth part 14 Support ring 15 Mouth surface 16 Body part 17 Bottom part 18 Outer layer of PET bottle 2 18a Outer layer of preform 1 19 Inner layer of PET bottle 2 19a Inner layer of preform 1 20 Middle layer of PET bottle 2 20a Preform 1 Intermediate layer 30 Upper part 31 Hot runner nozzle 32 Mold 32a Cavity 32b Gate 33a Straight flow path 33b First cylindrical flow path 34 Second cylindrical flow path 35 Check valve (open / close valve)
36 first inlet 37 second inlet 38 outlet 39a first junction 39b second junction 70 trunk 80 bottom

Claims (6)

With mouth, torso, bottom,
In a multilayer preform having an annular support ring projecting outward at the mouth,
The preform, wherein the intermediate layer is provided continuously from the vicinity of the support ring in the body portion at the body portion and continuously provided.   The preform according to claim 1, wherein the intermediate layer has a gas barrier property.   The said intermediate | middle layer is provided in the range from 3-20 mm from the said bottom from the position spaced apart from the top surface of the said mouth by 5-20 mm, The Claims 1 or 2 characterized by the above-mentioned. Preform.   The preform according to any one of claims 1 to 3, wherein the weight of the intermediate layer is 2% by weight to 7% by weight based on the weight of the entire preform. In the preform according to any one of claims 1 to 4,
In a method of manufacturing a preform by co-injection molding injecting one material and injecting another material,
The first molding material is injected all the time from the start of injection to the end of injection,
After the start of injection of the first molding material, a second molding material is injected for a predetermined time,
The second molding material is injected by being sandwiched between the first molding material,
Preform manufacturing method.   A plastic bottle obtained by molding the preform according to any one of claims 1 to 4 by blow molding.

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