WO2018037979A1

WO2018037979A1 - Preform cover, complex preform, manufacturing method of container

Info

Publication number: WO2018037979A1
Application number: PCT/JP2017/029442
Authority: WO
Inventors: 圭輔泉原
Original assignee: キョーラク株式会社
Priority date: 2016-08-26
Filing date: 2017-08-16
Publication date: 2018-03-01

Abstract

A complex preform is provided which can improve operability when mounting a preform cover on a preform. This complex preform is provided with a cylindrical preform and a cylindrical preform cover. The preform cover has an insertion end, which is the end on the side where the inserting end of the preform is inserted. The preform cover is mounted on the preform by insertion of the inserting end of the preform into the insertion end of the preform cover and by relative movement of the insertion end to a prescribed position of the preform. The sliding resistance between the preform and the preform cover in a first state, which is up to when the insertion end reaches an immediately preceding position, which is a position immediately preceding the aforementioned prescribed position, is less than the sliding resistance between the preform and the preform cover in a second state, which is after the insertion end has gone beyond the aforementioned immediately preceding position.

Description

Preform cover, composite preform, container manufacturing method

The present invention relates to a preform cover, a composite preform, and a method for manufacturing a container.

As a method for molding a plastic container (bottle), a blow molding method is widely used. An injection-molded preform is set in a mold, and air is blown to form a mold cavity. An axial stretch blow molding method or the like is known.

In recent years, various functions and performances are often required in the field of plastic containers, and ingenuity is required for the materials and molding methods used. For example, when a gas barrier property, a light shielding property, a heat retaining property, etc. are required, a material to be used has a gas barrier property, or a colorant or an ultraviolet absorber is added to a plastic material.

However, there are limits to the contrivance of materials and the like, and various functions are also given by multilayering plastic containers. By optimizing the constituent materials of each layer, it is expected that a plastic container having a composite function such as a light shielding container excellent in gas barrier properties can be realized.

In order to mold a multilayer plastic container, it is considered that a multilayer preform may be injection-molded and then biaxially stretched and blow-molded, and various multilayer preform molding methods have been proposed. However, there is a problem in terms of cost, for example, because advanced technology is required for molding a multilayer preform, and a large amount of equipment investment is required for the molding apparatus.

From such a situation, it has been proposed to form a composite container by mounting a preform cover separately formed on the outside of the preform and biaxially stretching blow-molding the preform cover (see Patent Document 1 and the like). . By using the preform cover, it is considered unnecessary to form a multilayer preform, leading to cost reduction and the like.

JP 2016-097669 A

(First viewpoint)
By the way, the preform cover may be formed by direct blow molding, and it is difficult to control the wall thickness with high precision by direct blow molding, so the inner surface shape of the preform cover may vary. For this reason, it is difficult to attach the preform cover to the outside of the preform because the inner diameter of the preform cover is too small, or the preform cover is easily detached from the preform because the inner diameter of the preform cover is too large. There is a problem that it may be trapped.

The first aspect of the present invention has been made in view of such circumstances, and provides a composite preform that can improve workability when a preform cover is attached to the preform.

(Second perspective)
By the way, the present inventor has been diligently studying to develop a preform cover having an EVOH layer having gas barrier properties in order to impart gas barrier properties by the preform cover, depending on molding conditions of the composite preform. It has been found that the EVOH layer is not uniformly stretched, and a portion where the EVOH layer is excessively thin may be formed in a container obtained by biaxial stretch blow molding.

The second aspect of the present invention has been made in view of such circumstances, and provides a preform cover capable of uniformly stretching an EVOH layer.

Hereinafter, means for solving the problems of the first and second viewpoints will be described. The solving means of the first and second aspects presented below can be combined with each other.

(First viewpoint)
According to a first aspect of the present invention, a cylindrical preform and a cylindrical preform cover are provided, and the preform cover is an end portion on the side where an insertion end of the preform is inserted. The insert cover is inserted into the preform cover from the inserted end, and the inserted cover moves relative to the predetermined position of the preform so that the preform cover moves relative to the preform. The sliding resistance between the preform and the preform cover in the first state until the inserted end reaches a position immediately before the predetermined position, which is configured to be mounted, A composite preform configured to be smaller than a sliding resistance between the preform and the preform cover in the second state after the inserted end exceeds the immediately preceding position. Beam is provided.

In the composite preform of the present invention, the sliding resistance in the first state is smaller than the sliding resistance in the second state. Therefore, until the inserted end of the preform cover reaches the predetermined position of the preform, the preform cover smoothly moves relative to the preform, and the inserted end of the preform cover is moved to the predetermined position of the preform. Since the preform cover can be surely attached to the preform at the stage of reaching, workability when attaching the preform cover to the preform can be improved.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the sliding resistance between the insertion end vicinity part and the preform cover which is a part near the insertion end in the first state is such that the insertion end vicinity part and the preform cover in the second state are Less than the sliding resistance between.
Preferably, the similarity ratio of the inner surface shape of the preform cover with respect to the outer surface shape of the preform is defined as an inner surface similarity ratio, and a region in the vicinity of the opposite end that is the end opposite to the inserted end is defined as a region near the opposite end. When the portion closer to the insertion end than the portion near the opposite end is the insertion end side portion, the inner surface similarity ratio at the portion near the opposite end is smaller than the inner surface similarity ratio at the insertion end side portion. .
Preferably, the thickness of the preform cover in the vicinity of the opposite end is larger than the thickness of the inserted end side portion.
Preferably, when the similarity ratio of the outer surface shape of the preform cover to the outer surface shape of the preform is an outer surface similarity ratio, the outer surface similarity ratio in the vicinity of the opposite end is the outer surface similarity ratio in the insertion end side portion. Smaller than.
Preferably, assuming that the portion of the preform cover near the inserted end is a portion near the inserted end, the sliding resistance between the preform and the portion near the inserted end in the first state is second. This is smaller than the sliding resistance between the preform and the vicinity of the inserted end in the state.
Preferably, the preform includes a preform small-diameter portion and a preform large-diameter portion, and the preform large-diameter portion has a larger outer shape than the preform small-diameter portion, and the preform small-diameter portion. Rather than the insertion end.
Preferably, the preform cover includes a preform cover small diameter portion and a preform cover large diameter portion, and the preform cover small diameter portion and the preform cover large diameter portion respectively include the preform small diameter portion and the preform cover small diameter portion and the preform cover large diameter portion. It arrange | positions in the position facing a preform large diameter part.
Preferably, the thickness at the large diameter portion of the preform cover is larger than the thickness at the small diameter portion of the preform cover.
Preferably, when the similarity ratio of the outer surface shape of the preform cover to the outer surface shape of the preform is an outer surface similarity ratio, the outer surface similarity ratio of the preform cover large-diameter portion is the outer surface of the preform cover small-diameter portion. It is smaller than the similarity ratio.

(Second perspective)
According to a second aspect of the present invention, there is provided a preform cover having an EVOH layer made of an EVOH resin, wherein the EVOH resin has a maximum uniaxial elongational viscosity measured at a temperature of 180 ° C. and a strain rate of 10 s ^−1. A preform cover is provided that is 0.0 × 10 ⁴ (Pa · s) or higher.

The present inventor examined the cause that the EVOH layer contained in the preform cover may not be uniformly stretched in the biaxial stretch blow molding of the composite preform. In the biaxial stretch blow molding of the composite preform, It has been found that the biaxial stretch blow molding is usually performed at a temperature suitable for the preform resin, and the temperature is not suitable for the EVOH resin, so that the stretching of the EVOH layer becomes non-uniform. Therefore, when the EVOH resin constituting the EVOH layer was further studied, when an EVOH resin having a maximum uniaxial elongational viscosity of 3.0 × 10 ⁴ (Pa · s) or more was used, a preform was used. It has been found that the EVOH layer can be uniformly stretched even when biaxial stretch blow molding is performed under conditions suitable for the present invention, and the present invention has been completed.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the EVOH resin has an ethylene content of 32 mol% or less.
Preferably, the EVOH resin has an MFR measured under conditions of a temperature of 210 ° C. and a load of 2.16 kg of 6 g / 10 min or less.
Preferably, the EVOH layer is sandwiched between a pair of polyolefin layers.
Preferably, the EVOH layer has a thickness of 0.3 to 1 mm.
According to another aspect of the present invention, there is provided a composite preform comprising a preform and a preform cover superimposed on the preform, wherein the preform cover is the preform cover described above. Is done.
According to another viewpoint of this invention, the manufacturing method of a container provided with the process of biaxially stretching blow-molding said composite preform is provided.

1A to 1E are sectional views showing a composite preform 10 according to a first embodiment of the first aspect of the present invention. FIG. 1A shows a state in which the preform 1 and the preform cover 11 are separated, and FIG. FIG. 1C shows a state before the inserted end 13 reaches the immediately preceding position B, FIG. 1C shows a state where the inserted end 13 has reached the immediately preceding position B, FIG. 1D shows a state where the inserted end 13 has reached the predetermined position A, and FIG. The enlarged view of the area | region X in FIG. 1B is shown. It is sectional drawing corresponding to FIG. 1A which shows the molded object 21 formed in the middle of manufacture of the preform cover 11 of 1st Embodiment of the 1st viewpoint of this invention. It is an enlarged view corresponding to FIG. 1E which shows the composite preform 10 of 2nd Embodiment of the 1st viewpoint of this invention. It is the enlarged view corresponding to FIG. 1E which shows the composite preform 10 of 3rd Embodiment of the 1st viewpoint of this invention. 5A to 5E are sectional views showing a composite preform 10 according to a fourth embodiment of the first aspect of the present invention. FIG. 5A shows a state in which the preform 1 and the preform cover 11 are separated, and FIG. FIG. 5C shows a state before the inserted end 13 reaches the immediately preceding position B, FIG. 5C shows a state where the inserted end 13 has reached the immediately preceding position B, FIG. 5D shows a state where the inserted end 13 has reached the predetermined position A, and FIG. The enlarged view of the area | region Y in FIG. 5C is shown. It is an enlarged view corresponding to FIG. 5E which shows the composite preform 10 of 5th Embodiment of the 1st viewpoint of this invention. 7A to 7D are sectional views showing a composite preform 10 according to a sixth embodiment of the first aspect of the present invention. FIG. 7A shows a state in which the preform 1 and the preform cover 11 are separated, and FIG. 7C shows a state before the inserted end 13 reaches the immediately preceding position B, FIG. 7C shows a state where the inserted end 13 has reached the immediately preceding position B, and FIG. 7D shows a state where the inserted end 13 has reached the predetermined position A. 8A to 8C are sectional views showing the composite preform 10 according to the seventh embodiment of the first aspect of the present invention. FIG. 8A shows a state in which the insertion end 13 has reached the immediately preceding position B, and FIG. FIG. 8C shows a state in which the insertion end 13 has reached the position C, and FIG. 8C shows a state in which the insertion end 13 has reached the predetermined position A. 9A to 9D are sectional views showing a composite preform 10 according to an eighth embodiment of the first aspect of the present invention. FIG. 9A shows a state in which the preform 1 and the preform cover 11 are separated, and FIG. 9C shows a state before the inserted end 13 reaches the immediately preceding position B, FIG. 9C shows a state where the inserted end 13 has reached the immediately preceding position B, and FIG. 9D shows a state where the inserted end 13 has reached the predetermined position A. 10A to 10D are cross-sectional views showing a composite preform 10 according to a ninth embodiment of the first aspect of the present invention. FIG. 10A shows a state where the preform 1 and the preform cover 11 are separated, and FIG. FIG. 10C shows a state before the inserted end 13 reaches the immediately preceding position B, FIG. 10C shows a state where the inserted end 13 has reached the immediately preceding position B, and FIG. 10D shows a state where the inserted end 13 has reached the predetermined position A. 11A to 11B show a first embodiment of the second aspect of the present invention, FIG. 11A shows the preform 1 and the preform cover 11 in a separated state, and FIG. 11B shows the preform 1 with the preform cover. 1 shows a composite preform 10 obtained by stacking 11 layers. 12A to 12B show a second embodiment of the second aspect of the present invention, FIG. 12A shows the preform 1 and the preform cover 11 in a separated state, and FIG. 12B shows the preform 1 with the preform cover. 1 shows a composite preform 10 obtained by stacking 11 layers. It is a graph which shows the relationship between the elapsed time from the measurement start about the EVOH resin used by the Example and the comparative example, and uniaxial elongation viscosity.

Hereinafter, embodiments of the present invention will be described. Various characteristic items shown in the following embodiments can be combined with each other. In addition, the invention is independently established for each feature. First, an embodiment of the first aspect of the present invention will be described, and then an embodiment of the second aspect of the present invention will be described. It is also possible to combine the features described in the first aspect and the features described in the second aspect.

(First viewpoint)
1. First Embodiment of First Aspect As shown in FIG. 1, a composite preform 10 according to a first embodiment of the first aspect of the present invention includes a cylindrical preform 1 and a cylindrical preform cover 11. .

The preform 1 includes a cylindrical (preferably cylindrical) body 2. A mouth 3 is provided at one end of the body 2, and the mouth 3 is provided with an engaging part 3 a for attaching a cap (not shown). The cap may be attached by a stopper type or may be attached by a screw type. The other end of the body portion 2 is an insertion end 4 to be inserted into the preform cover 11, and the insertion end 4 is a bottom portion 5 of the preform 1. The bottom 5 is hemispherical in one example, but the shape is not particularly limited. The preform 1 can be formed by injection molding a resin material. As the resin material, it is preferable to use a thermoplastic resin, particularly PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or PC (polycarbonate).

The preform cover 11 includes a cylindrical (preferably cylindrical) body 12. An insertion end 13 is provided at one end of the body portion 12, and the preform 1 is inserted into the preform cover 11 through the insertion end 13. The other end of the body portion 12 is an opposite end 14 that is an end portion on the opposite side of the insertion end 13, and the opposite end 14 is a bottom portion 15 of the preform cover 11. The bottom portion 15 is hemispherical in one example, but the shape is not particularly limited. A method for forming the preform cover 11 is not particularly limited, but in an example, the preform cover 11 is formed by extrusion molding in which a molten resin is extruded into a cylindrical shape and cooled and solidified, or direct blow molding in which a molten cylindrical parison is blow-molded as it is. In the case of extrusion molding, one end of a cylindrical molded product can be welded and closed. The resin material for forming the preform cover 11 may be the same as or different from the preform 1. The preform cover 11 may have a single layer structure or a multilayer structure.

In addition, as shown in FIG. 2, the preform cover 11, for example, forms a molded body 21 having a shape in which two preform covers 11 are connected by a connecting portion 22, and the molded body 21 is cut at a cutting position S. Can be formed. An end formed by cutting at the cutting position S is the insertion end 13. The thickness of the molded body 21 in the vicinity of the cutting position S is preferably 0.35 mm or more. This is because if the thickness is too small, when the molded body 21 is cut, the molded body 21 may be deformed by pressing with the blade and the cutting position may be shifted. Although the upper limit of this thickness is not specifically limited, For example, it is 1 mm. Specifically, this thickness is, for example, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 0.85, 0.9, 0.95, and 1 mm, and may be within a range between any two of the numerical values exemplified here.

As shown in FIGS. 1A and 1B, the preform 1 and the preform cover 11 are inserted into the preform cover 11 from the inserted end 13 of the preform cover 11 as shown in FIG. 1C. After the state, as shown in FIG. 1D, the preform cover 11 is configured to be attached to the preform 1 by the relative movement of the inserted end 13 to the predetermined position A of the preform 1. . The preform cover 11 may be formed so as to cover the entire preform 1. However, in the present embodiment, the preform cover 11 partially covers the preform 1 (specifically, a large portion of the body portion 2). It is configured to cover the part and the bottom 5).

In general, the inner surface shape of the preform cover 11 substantially matches the outer surface shape of the preform 1, and when the preform 1 is inserted into the preform cover 11, substantially the entire inner surface of the preform cover 11 is the preform 1. In this state, the preform 1 and the preform cover 11 are integrated. On the other hand, in the present embodiment, as will be described later, the preform 1 is not matched with the outer shape of the preform 1 according to the position of the inserted end 13 of the preform 1 without matching the outer shape of the preform 1. The preform 1 can be easily inserted into the preform cover 11 by changing the magnitude of the sliding resistance between the preform cover 11 and the preform cover 11. 11 is made difficult to come off from the preform 1.

Specifically, in the present embodiment, when the part near the opposite end 14 of the preform cover 11 is the opposite end vicinity part 16 and the part closer to the insertion end 13 than the part 16 is the insertion end side part 17. The similarity ratio of the inner surface shape of the preform cover 11 to the outer surface shape of the preform 1 (hereinafter referred to as “inner surface similarity ratio”) is smaller at the part 16 than at the part 17. For this reason, as shown in FIG. 1B, the insertion end vicinity portion 6 (the preform cover 11 is attached to the preform 1 as shown in FIG. 1D), which is a portion in the vicinity of the insertion end 4 of the preform 1. Since the sliding resistance between the preform 1 and the preform cover 11 is small while the portion facing the portion 16 near the opposite end in the state is facing the portion 17, the preform 1 is placed in the preform cover 11. It can be inserted smoothly. On the other hand, as shown in FIG. 1C, when the portion 6 near the insertion end starts to face the portion 16, the sliding resistance between the preform 1 and the preform cover 11 increases. For this reason, as shown in FIG. 1D, when the preform cover 11 is mounted on the preform 1, the preform cover 11 does not easily fall off from the preform 1. In the present specification, the two shapes for which the similarity ratio is to be calculated do not have to be strictly similar, and may be shapes that are similar to the extent that the similarity ratio can be calculated.

The inner surface similarity ratio at the portion 16 is preferably smaller than 1, more preferably 0.8 to 0.99. Specifically, the internal surface similarity ratio in the region 16 is, for example, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88. , 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99. It may be within a range between any two of the numerical values. The internal surface similarity ratio at the site 17 is preferably greater than 0.9, more preferably greater than 1, and even more preferably 1.01 to 1.2. Specifically, the internal surface similarity ratio at the portion 17 is, for example, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98. , 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, between any two of the numerical values illustrated here It may be within the range.

The value of {(the inner surface similarity ratio at the portion 17) − (the inner surface similarity ratio at the portion 16)} is preferably 0.01 to 0.4, and more preferably 0.05 to 0.2. Specifically, this value is, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0. 23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, and may be within a range between any two of the numerical values exemplified here.

Although the outer surface shape of the preform cover 11 is not particularly limited, in this embodiment, the outer surface shape of the preform cover 11 is similar to the outer surface shape of the preform 1. Therefore, the thickness at the portion 16 is larger than the thickness at the portion 17. Is also getting bigger.

Further, if attention is given to the inserted end 13 of the preform cover 11, the composite preform 10 according to the present embodiment has a state in which the inserted end 13 reaches a position B immediately before the predetermined position A. The sliding resistance between the preform 1 and the preform cover 11 in the first state is that between the preform 1 and the preform cover 11 in the second state after the inserted end 13 exceeds the immediately preceding position B. It is comprised so that it may become smaller than sliding resistance. The state until the inserted end 13 reaches the immediately preceding position B shown in FIG. 1C through the state of FIGS. 1A to 1B is the first state. In this state, the sliding between the preform 1 and the preform cover 11 is performed. The resistance is small, and it is easy to move the preform cover 11 relative to the preform 1. On the other hand, the state until the inserted end 13 exceeds the immediately preceding position B and reaches the predetermined position A is the second state. In this state, the sliding resistance between the preform 1 and the preform cover 11 is large. .

The ratio of the distance LB from the insertion end 4 of the preform 1 to the immediately preceding position B with respect to the distance LA from the insertion end 4 of the preform 1 to the predetermined position A is not particularly limited, but is preferably 0.5 or more, 0.8 The above is more preferable. Although the upper limit of this ratio is not specifically limited, For example, 0.99 is preferable. The larger this ratio, the easier it is to insert the preform 1 into the preform cover 11. However, if this ratio is too large, the preform cover 11 may be easily removed after being attached. Specifically, this ratio is, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, and may be within a range between any two of the numerical values exemplified here.

Incidentally, when the preform cover 11 is formed by direct blow molding, the inner surface shape of the preform cover 11 is likely to vary. For this reason, when the inner surface shape of the preform cover 11 is designed to match the outer surface shape of the preform 1, the preform 1 is inserted into the preform cover 11 when the inner diameter of the preform cover 11 varies so as to become smaller. When the preform cover 11 is dispersed so that the inner diameter of the preform cover 11 is increased, the preform cover 11 can be easily detached from the preform 1 even if the preform 1 is pushed into the bottom of the preform cover 11. . On the other hand, in the present embodiment, the inner surface similarity ratio at the portion 16 is designed so that the inner surface similarity ratio at the portion 17 is smaller than 1. For this reason, it is suppressed that it becomes difficult to insert the preform 1 into the preform cover 11 even if the inner diameter of the preform cover 11 varies at the portion 17, and the inner diameter of the preform cover 11 at the portion 16. The preform cover 11 is prevented from easily falling off from the preform 1 even if the dispersion is large. Therefore, according to the present embodiment, even when the inner shape of the preform cover 11 varies, the problem that the preform 1 becomes difficult to insert or the preform cover 11 falls off is less likely to occur. The workability at the time of attaching the preform cover 11 to the reform 1 can be improved.

As shown in FIG. 1D, the composite preform 10 of the present embodiment is set in a blow molding die after the preform cover 11 is mounted on the preform 1 and blow molded to correspond to the cavity shape inside the die. A formed container is formed. The composite preform 10 is blow-molded in a state of being heated and softened before or after being set in the mold.

2. Second Embodiment of First Aspect The second embodiment of the first aspect of the present invention will be described with reference to FIG. The present embodiment is similar to the first embodiment, and the main difference is the difference in the shape of the portion 16 near the opposite end of the preform cover 11. Hereinafter, the difference will be mainly described.

In the present embodiment, the shape of the preform 1 and the inner shape of the preform cover 11 are the same as those in the first embodiment, and the preform cover 11 is attached to the preform 1 by the same action as in the first embodiment. The effect that the workability at the time can be improved is exhibited. In the present embodiment, the outer shape of the portion 16 of the preform cover 11 is different from that of the first embodiment. In the first embodiment, by making the outer surface shape of the preform cover 11 similar to the outer surface shape of the preform 1 and making the thickness of the region 16 larger than that of the region 17, the inner surface similarity ratio at the region 16 is increased. A configuration in which the inner surface similarity ratio at 17 is smaller is realized. On the other hand, in this embodiment, when the similarity ratio of the outer surface shape of the preform cover 11 to the outer surface shape of the preform 1 is “outer surface similarity ratio”, the thickness at the portion 16 and the thickness at the portion 17 are substantially equal. Equally, the outer surface similarity ratio at the part 16 is smaller than the outer surface similarity ratio at the part 17. According to such a configuration, the preform cover 11 having a uniform thickness can be obtained. Preferred values for the outer surface similarity ratio are similar to those described for the inner surface similarity ratio.

3. Third Embodiment of First Aspect The third embodiment of the first aspect of the present invention will be described with reference to FIG. The present embodiment is similar to the first embodiment, and the main difference is the difference in the shape of the portion 16 near the opposite end of the preform cover 11. Hereinafter, the difference will be mainly described.

In this embodiment, the shape of the preform 1 is the same as that of the first embodiment. On the other hand, in the first embodiment, the preform cover 11 has the bottom 15, but in this embodiment, an opening 18 is provided at the opposite end 14 of the preform cover 11. Further, in the first embodiment, the outer surface shape of the preform cover 11 is similar to the outer surface shape of the preform 1, but in the present embodiment, it is not similar.

The inner surface shape of the preform cover 11 is the same as that of the first embodiment except that the opening 18 is provided, and when the preform cover 11 is attached to the preform 1 by the same operation as that of the first embodiment. The workability can be improved.

4). Fourth Embodiment of First Aspect The fourth embodiment of the first aspect of the present invention will be described with reference to FIG. This embodiment is similar to the first embodiment, and is mainly different in that a small diameter portion and a large diameter portion are provided in the body portions of the preform 1 and the preform cover 11. Hereinafter, the difference will be mainly described.

In this embodiment, the body portion 2 of the preform 1 includes a preform small diameter portion 2a and a preform large diameter portion 2b. The large-diameter portion 2b has a larger outer surface shape than the small-diameter portion 2a (outer diameter in the case of a cylinder) and is disposed at a position farther from the insertion end 4 than the small-diameter portion 2a. The large diameter portion 2b includes a large diameter body portion 2c and an inclined portion 2d. The inclined part 2d is disposed between the large diameter body part 2c and the small diameter part 2a. The value of the ratio of the outer diameter of the large-diameter body portion 2c to the outer diameter of the small-diameter portion 2a is not particularly limited, but is 1.1 to 2, for example, and preferably 1.2 to 1.5. Specifically, this value is, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, It may be within a range between any two of the numerical values exemplified here. The inclined portion 2d may be planar or curved in the cross section shown in FIG. 5A. The angle of the inclined portion 2d with respect to the central axis CA of the mouth 3 is not particularly limited, but is, for example, 10 to 60 degrees, and preferably 20 to 50 degrees. Specifically, this angle is, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 degrees, and within a range between any two of the numerical values exemplified here. There may be. Either one of the large-diameter trunk portion 2c and the inclined portion 2d can be omitted.

The body portion 12 of the preform cover 11 includes a preform cover small diameter portion 12a and a preform cover large diameter portion 12b. The large-diameter portion 12b has a larger outer surface size (outer diameter in the case of a cylinder) than the small-diameter portion 12a. The small diameter portion 12a and the large diameter portion 12b are disposed at positions facing the small diameter portion 2a and the large diameter portion 2b, respectively. The large diameter portion 12b includes a large diameter body portion 12c and an inclined portion 12d. The inclined portion 12d is disposed between the large diameter trunk portion 12c and the small diameter portion 12a.

In the present embodiment, the portion near the inserted end 13 of the preform cover 11 is replaced with a portion 19 near the inserted end (in the present embodiment, the portion 19 near the inserted end coincides with the large diameter portion 12b). Assuming that the portion on the opposite end 14 side from the inserted end vicinity portion 19 is the opposite end portion 20, the inner surface similarity ratio in the portion 19 is smaller than the inner surface similarity ratio in the portion 20. The inner surface similarity ratio at the portion 19 is preferably smaller than 1, and more preferably 0.8 to 0.99. Specifically, the inner surface similarity ratio in the region 19 is, for example, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88. , 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99. It may be within a range between any two of the numerical values. The internal similarity ratio at the site 20 is preferably greater than 0.9, more preferably greater than 1, and even more preferably 1.01 to 1.2. Specifically, the inner surface similarity ratio at the portion 20 is, for example, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98. , 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, between any two of the numerical values illustrated here It may be within the range.

The value of {(the inner surface similarity ratio at the portion 20) − (the inner surface similarity ratio at the portion 19)} is preferably 0.01 to 0.4, and more preferably 0.05 to 0.2. Specifically, this value is, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0. 23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, and may be within a range between any two of the numerical values exemplified here.

As shown in FIG. 5B, while the insertion end 4 of the preform 1 is inserted into the preform cover 11 and the portion 19 near the insertion end is opposed to the small diameter portion 2a, the preform 1 is located between the preform cover 11 and the preform cover 11. Therefore, the preform 1 can be smoothly inserted into the preform cover 11. On the other hand, as shown in FIG. 5C, the sliding resistance between the preform 1 and the preform cover 11 increases when the inserted end vicinity portion 19 starts to face the large diameter portion 2b. For this reason, as shown in FIG. 5D, the preform cover 11 is not easily detached from the preform 1 in a state where the preform cover 11 is attached to the preform 1.

Although the outer surface shape of the preform cover 11 is not particularly limited, in this embodiment, the outer surface shape of the preform cover 11 is similar to the outer surface shape of the preform 1, so that the thickness at the portion 19 is greater than the thickness at the portion 20. Is also getting bigger.

Further, if attention is given to the inserted end 13 of the preform cover 11, the composite preform 10 according to the present embodiment has a state in which the inserted end 13 reaches a position B immediately before the predetermined position A. The sliding resistance between the preform 1 and the preform cover 11 in the first state is that between the preform 1 and the preform cover 11 in the second state after the inserted end 13 exceeds the immediately preceding position B. It is comprised so that it may become smaller than sliding resistance. The state until the inserted end 13 reaches the immediately preceding position B shown in FIG. 5C through the state shown in FIGS. 5A to 5B is the first state. In this state, the sliding between the preform 1 and the preform cover 11 is performed. The resistance is small, and it is easy to move the preform cover 11 relative to the preform 1. On the other hand, the state until the inserted end 13 exceeds the immediately preceding position B and reaches the predetermined position A is the second state. In this state, the sliding resistance between the preform 1 and the preform cover 11 is large. . Thus, in this embodiment as well, as in the first embodiment, the sliding resistance in the second state is larger than the sliding resistance in the first state. The same effect as the embodiment is achieved.

5). Fifth Embodiment of First Aspect The fifth embodiment of the first aspect of the present invention will be described using FIG. This embodiment is similar to the fourth embodiment, and the main difference is the difference in the shape of the inserted end vicinity portion 19. Hereinafter, the difference will be mainly described.

In the present embodiment, the shape of the preform 1 and the inner shape of the preform cover 11 are the same as those in the fourth embodiment, and the preform cover 11 is attached to the preform 1 by the same action as in the fourth embodiment. The effect that the workability at the time can be improved is exhibited. In the present embodiment, the shape of the portion 19 of the preform cover 11 is different from that of the first embodiment. In the first embodiment, by making the outer surface shape of the preform cover 11 similar to the outer surface shape of the preform 1 and making the thickness of the portion 19 larger than the portion 20, the inner surface similarity ratio at the portion 19 is increased. A configuration in which the inner surface similarity ratio at 20 is smaller is realized. For this reason, in the first embodiment, the angle of the inclined portion 2d with respect to the central axis CA and the angle of the inclined portion 12d with respect to the central axis CA are substantially the same. On the other hand, in the present embodiment, the thickness at the part 19 is substantially equal to the thickness at the part 20, and the angle of the inclined part 12d with respect to the central axis CA is smaller than the angle of the inclined part 2d with respect to the central axis CA. By configuring as described above, a configuration is realized in which the inner surface similarity ratio at the portion 19 is smaller than the inner surface similarity ratio at the portion 20. According to such a configuration, the preform cover 11 having a uniform thickness can be obtained. Preferred values for the outer surface similarity ratio are similar to those described for the inner surface similarity ratio.

6). Sixth Embodiment of First Aspect The sixth embodiment of the first aspect of the present invention will be described with reference to FIG. This embodiment is similar to the fourth embodiment, and the difference in the shape of the preform cover 11 is the main difference. Hereinafter, the difference will be mainly described.

In the fourth embodiment, the inner surface similarity ratio at the insertion end vicinity portion 19 (large diameter portion 12b) is smaller than 1, and the sliding resistance at the large diameter portion 12b is increased. In this embodiment, the internal diameter similarity ratio at the large diameter portion 12b is greater than 1, and the sliding resistance at the large diameter portion 12b is reduced. On the other hand, in this embodiment, the inner surface similarity ratio at the opposite end vicinity portion 16 is smaller than 1 and the inner surface similarity ratio at the inserted end side portion 17 is larger than 1, as in the first embodiment. For this reason, the effect similar to 1st Embodiment is show | played.

In the present embodiment, the shape of the outer surface of the preform cover 11 is similar to the shape of the outer surface of the preform 1, and the thickness at the portion 16 is larger than the thickness at the portion 17. 16, the inner surface similarity ratio at the portion 17 is smaller than that at the portion 17, but the thickness at the portion 16 and the thickness at the portion 17 are substantially the same as in the second embodiment. And by making the outer surface similarity ratio at the portion 16 smaller than the outer surface similarity ratio at the portion 17, the inner surface similarity ratio at the portion 16 becomes smaller than the inner surface similarity ratio at the portion 17. It may be realized.

7). Seventh Embodiment of First Aspect The seventh embodiment of the first aspect of the present invention will be described with reference to FIG. This embodiment is similar to the sixth embodiment, and the difference in the shape of the preform cover 11 is the main difference. Hereinafter, the difference will be mainly described.

In the present embodiment, the inserted end vicinity portion 19 of the preform cover 11 has the same shape as that of the fourth embodiment, and the opposite end vicinity portion 16 has the same shape as that of the sixth embodiment. Yes.

In the present embodiment, the state until the inserted end 13 reaches the immediately preceding position B shown in FIG. 8A is the first state, and after the inserted end 13 exceeds the immediately preceding position B, it reaches the position C shown in FIG. 8B. The state until this is the second state of the first half, and the state from when the inserted end 13 exceeds the position C until it reaches the predetermined position A shown in FIG. 8C is the second state of the second half. The “second state” in the claims is constituted by the second state in the first half and the second state in the second half.

In the first state, the sliding resistance between the preform 1 and the preform cover 11 is small, and it is easy to move the preform cover 11 relative to the preform 1. In the second state of the previous period, the sliding resistance between the preform 1 and the preform cover 11 at the portion 16 near the opposite end increases. In the latter second state, the sliding resistance between the preform 1 and the preform cover 11 also increases in the portion 19 near the insertion end, so that the sliding resistance between the preform 1 and the preform cover 11 is further increased. Become. As described above, in this embodiment, the sliding resistance changes in three stages, so that the problem that it becomes difficult to insert the preform 1 or the preform cover 11 falls off is further less likely to occur.

8). Eighth Embodiment of First Aspect The eighth embodiment of the first aspect of the present invention will be described with reference to FIG. This embodiment is similar to the fourth embodiment, and the difference in the shape of the preform cover 11 is the main difference. Hereinafter, the difference will be mainly described.

In the present embodiment, the preform 1 is provided with a small-diameter portion 2a and a large-diameter portion 2b, but the preform cover 11 is not provided with the small-diameter portion 2a and the large-diameter portion 2b. , Has a certain shape over its longitudinal direction.

In the present embodiment, as shown in FIG. 9C, when the preform cover 11 is strongly pressed against the preform 1 from the state in which the inserted end 13 is in contact with the inclined portion 2d, the portion 19 near the inserted end is elastic. 9D, the part 19 is in a state of surrounding the large-diameter body 2c, and the preform cover 11 is attached to the preform 1.

9. Ninth Embodiment of First Aspect The ninth embodiment of the first aspect of the present invention will be described with reference to FIG. This embodiment is similar to the eighth embodiment, and the difference in the shape of the preform cover 11 is the main difference. Hereinafter, the difference will be mainly described.

In the present embodiment, the preform cover 11 has a pipe shape having only the body portion 12. The preform 1 is provided with a locking portion 2e at a position farther from the insertion end 4 than the large-diameter barrel portion 2c. When the preform 1 is inserted into the preform cover 11, the portion 19 is enlarged by the same action as in the eighth embodiment to surround the large-diameter body portion 2 c, and the preform cover 11 is further pushed into the preform 1. Then, the preform cover 11 is brought into contact with the locking portion 2e, and the preform cover 11 is mounted in a state of being positioned with respect to the preform 1. In the present embodiment, since the preform cover 11 is pipe-shaped, it can be manufactured at low cost by extrusion molding or the like.

(Second perspective)
1. First Embodiment of Second Aspect FIG. 11 shows a first embodiment of the second aspect of the present invention, FIG. 11A shows the preform 1 and the preform cover 11 in a separated state, and FIG. 11B shows the preform. 1 shows a composite preform 10 obtained by overlaying a preform cover 11.

The basic configuration of the preform 1 and the preform cover 11 is the same as that of the first embodiment of the first aspect.

The preform cover 11 includes an EVOH layer made of EVOH resin (ethylene-vinyl alcohol copolymer). In general, the EVOH layer has a property that it is easily stretched unevenly depending on molding conditions because stretchability is not good. For this reason, for example, when the preform 1 made of PET and the preform cover 11 having the EVOH layer are overlapped and biaxially stretch blow-molded, the biaxial stretching is performed at 100 to 120 ° C. which is a molding temperature suitable for PET. When stretch blow molding is performed, the EVOH layer of the preform cover 11 is stretched non-uniformly, and there is a problem that a portion where the EVOH layer is excessively thin is easily formed in a container obtained by biaxial stretch blow molding. In order to solve such a problem, in the present embodiment, the maximum value of the uniaxial elongation viscosity measured at a temperature of 180 ° C. and a strain rate of 10 s ⁻¹ is 3.0 × 10 ⁴ (Pa · s) or more. The EVOH layer is composed of EVOH resin. When such an EVOH layer is used, the stretchability of the EVOH layer during biaxial stretch blow molding is improved, and even when biaxial stretch blow molding is performed at a temperature suitable for the material of the preform 1. The EVOH layer is easily stretched uniformly. The uniaxial extensional viscosity can be measured based on the change over time of the load when the test piece is extended and deformed at a temperature of 180 ° C. and a strain rate of 10 s ⁻¹ . The measurement of the uniaxial extensional viscosity is shown in FIG. Thus, a graph showing the relationship between elapsed time and uniaxial elongational viscosity is obtained. The measurement of the uniaxial extension viscosity is continued until the test piece is cut, and the maximum value of the uniaxial extension viscosity observed during the measurement is the “maximum value of the uniaxial extension viscosity” in the claims.

The maximum value of the uniaxial extensional viscosity is, for example, 3.0 × 10 ⁴ to 3.0 × 10 ⁶ (Pa · s), specifically, for example, 3.0 × 10 ⁴ , 4.0 × 10 ⁴ , 5.0 × 10 ⁴ , 6.0 × 10 ⁴ , 7.0 × 10 ⁴ , 8.0 × 10 ⁴ , 9.0 × 10 ⁴ , 1.0 × 10 ⁵ , 2.0 × 10 ⁵ , 3 0.0 × 10 ⁵ , 3.0 × 10 ⁶ (Pa · s), and may be within a range between any two of the numerical values exemplified here.

The ethylene content of the EVOH resin constituting the EVOH layer is not particularly defined, and is, for example, 25 to 50 mol%. Since EVOH resin has a tendency that the gas barrier property of EVOH resin becomes higher as the ethylene content is smaller, the ethylene content of EVOH resin is preferably 32 mol% or less, and more preferably 30 mol% or less. Specifically, the ethylene content is, for example, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 40, 45, 50 mol%, and any of the numerical values exemplified here It may be within a range between the two.

EVOH resin tends to have higher rigidity and lower secondary workability as the ethylene content is smaller. However, the ethylene content is 32 mol% or less and the maximum value of uniaxial elongational viscosity is 3.0 × 10 ⁴ ( By using an EVOH resin that is equal to or higher than (Pa · s), both good gas barrier properties and stretchability can be achieved.

The EVOH resin constituting the EVOH layer preferably has an MFR (melt flow rate) measured under conditions of a temperature of 210 ° C. and a load of 2.16 kg of 6 g / 10 min or less. In this case, the EVOH layer flows appropriately and is easily stretched uniformly. The MFR of this EVOH resin is, for example, 2 to 6 g / 10 min, specifically, for example, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 g / 10 min. There may be a range between any two of the numerical values exemplified here.

The preform cover 11 may have a single layer configuration of an EVOH layer or a multilayer configuration including an EVOH layer. In the case of a multilayer structure, a structure in which the EVOH layer is sandwiched between a pair of polyolefin layers is preferable. When the EVOH layer absorbs moisture, the gas barrier property tends to decrease, and moisture absorption of the EVOH layer can be suppressed by sandwiching the EVOH layer between a pair of polyolefin layers. Examples of the polyolefin constituting the polyolefin layer include low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof. The polyolefin layer may have a laminated structure of a repro layer and a virgin layer. Here, the repro layer refers to a layer that is used by recycling burrs that are produced when the container is molded, and the virgin layer refers to a layer formed of a virgin material. When the polyolefin layer includes a repro layer, the layer constituting the innermost surface and the outermost surface of the preform cover 11 is preferably a virgin layer.

When the EVOH layer is sandwiched between a pair of polyolefin layers, the ratio of the thickness of the polyolefin layer on the outer surface side and the inner surface side to the thickness of the EVOH layer is preferably 0.5 to 3, respectively. In this case, the EVOH layer can be made thick enough for the EVOH layer to exhibit gas barrier properties while the polyolefin layer prevents moisture absorption of the EVOH layer. Specifically, this ratio is specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3 and may be within a range between any two of the numerical values exemplified here. It may be within the range between any two of the numerical values exemplified here.

It is preferable to provide an adhesive layer between the EVOH layer and the polyolefin layer in order to increase the adhesive strength between them. The adhesive layer is, for example, one obtained by adding an acid-modified polyolefin (for example, maleic anhydride-modified polyethylene) in which a carboxyl group is introduced to the above-described polyolefin, or an ethylene vinyl acetate copolymer (EVA). An example of the adhesive layer is a mixture of low-density polyethylene or linear low-density polyethylene and acid-modified polyethylene.

The thickness of the EVOH layer is preferably 0.3 to 1 mm, and more preferably 0.4 to 0.7 mm. This is because, with such a thickness, even when the preform cover 11 is stretched 5 times or more, a sufficient thickness is ensured to exhibit gas barrier properties.

As shown in FIGS. 11A to 11B, the preform cover 11 is overlapped with the preform 1 by inserting the insertion end 4 of the preform 1 into the preform cover 11 from the inserted end 13 of the preform cover 11. Can be attached to. The preform cover 11 may be formed so as to cover the entire preform 1. However, in the present embodiment, the preform cover 11 partially covers the preform 1 (specifically, a large portion of the body portion 2). It is configured to cover the part and the bottom 5).

The inner surface shape of the preform cover 11 substantially matches the outer surface shape of the preform 1. When the preform 1 is inserted into the preform cover 11, substantially the entire inner surface of the preform cover 11 is the outer surface of the preform 1. The preform 1 and the preform cover 11 are integrated in appearance.

A composite preform 10 obtained by overlaying a preform cover 11 on the preform 1 is set in a mold and biaxially stretched and blow molded to form a container corresponding to the cavity shape inside the mold. The composite preform 10 is biaxially stretch blow-molded before being set in a mold or after being set and heated and softened. In this embodiment, since the maximum value of the uniaxial elongation viscosity of the EVOH resin constituting the EVOH layer included in the preform cover 11 is 3.0 × 10 ⁴ (Pa · s) or more, the EVOH layer is uniformly stretched. As a result, a container having excellent gas barrier properties can be obtained. The thickness of the EVOH layer after stretching is not particularly limited, but is, for example, 40 μm or more, and preferably 50 μm or more. The draw ratio is not particularly limited, but is, for example, 5 to 10 times.

2. Second Embodiment A second embodiment of the second aspect of the present invention will be described with reference to FIG. In the present embodiment, the preform cover 11 has a pipe shape having only the body portion 12. In the present embodiment, since the preform cover 11 is pipe-shaped, it can be manufactured at low cost by extrusion molding or the like.

The following examples and comparative examples are mainly related to the invention of the second aspect.

<Measurement of maximum value of uniaxial elongation viscosity>
A pellet made of EVOH resin shown in Table 1 (all manufactured by Nippon Synthetic Chemical Co., Ltd.) was heated on a hot plate at 230 ° C., and the pellet was pressed with a hot plate to create a sheet having a thickness of 500 μm. A test piece of 18 mm × 10 mm × 0.5 mm was prepared by cutting to 18 mm × 10 mm. This test piece was set on an MCR rheometer (model: MCR302, manufactured by Anton Paar), melted at 200 ° C., lowered to 180 ° C., and measured for uniaxial elongational viscosity at a strain rate of 10 s ⁻¹ to obtain FIG. The graph which shows the relationship between the elapsed time shown in 1 and a uniaxial elongation viscosity was obtained, and the maximum value of the uniaxial elongation viscosity was obtained about each EVOH resin. The obtained values are shown in Table 1.

<Extendability evaluation>
Using EVOH resin shown in Table 1, in order from the outside, polypropylene layer (thickness 125 μm) / adhesive layer (thickness 10 μm) / EVOH layer (thickness 50 μm) / adhesive layer (thickness 10 μm) / repro layer (thickness) The preform cover 11 having a layer configuration of 200 μm) / polypropylene layer (thickness 105 μm) was formed by direct blow molding. The preform cover 11 is overlapped with the PET preform 1 to form a composite preform 10, and biaxial stretch blow molding is performed so that the stretch ratio is about 7 times when the composite preform 10 is heated to 100 ° C. Went to form a container. The thickness of the EVOH layer is measured at eight points arranged at equal intervals in the circumferential direction at the center in the height direction of the obtained container, and stretched based on the thickness ratio determined by the maximum thickness / minimum thickness. Sex was evaluated according to the following criteria.
◎: Thickness ratio is less than 1.5 ○: Thickness ratio is 1.5 or more and less than 2.0 ×: Thickness ratio is 2.0 or more

<Discussion>
As shown in Table 1, in Examples where the maximum value of the uniaxial extensional viscosity is 3.0 × 10 ⁴ (Pa · s) or more, the extensibility is excellent, and the EVOH layer is uniformly stretched in the biaxial stretch blow molding. However, in the comparative example in which the maximum value of the uniaxial elongation viscosity is less than 3.0 × 10 ⁴ (Pa · s), the stretchability is poor, and the EVOH layer is stretched unevenly in the biaxial stretch blow molding. It was.

1: Preform, 2: Body part, 2a: Preform small diameter part, 2b: Preform large diameter part, 2c: Large diameter body part, 2d: Inclined part, 2e: Locking part, 3: Mouth part, 3a: Engagement part, 4: Insertion end, 5: Bottom part, 6: Site near insertion end, 10: Composite preform, 11: Preform cover, 12: Body part, 12a: Preform cover small diameter part, 12b: Preform cover Large diameter part, 12c: Large diameter body part, 12d: Inclined part, 13: Inserted end, 14: Opposite end, 15: Bottom part, 16: Opposite end part, 17: Inserted end part, 18: Opening part 19: site near the inserted end, 20: site on the opposite end side, A: predetermined position, B: previous position, C: position, S: cutting position, CA: central axis, LA: distance, LB: distance

Claims

It has a cylindrical preform and a cylindrical preform cover,
The preform cover includes an insertion end that is an end portion on a side where the insertion end of the preform is inserted;
The insert end is inserted into the preform cover from the inserted end, and the inserted end moves relative to a predetermined position of the preform so that the preform cover is attached to the preform. Composed of
The sliding resistance between the preform and the preform cover in the first state until the inserted end reaches a position immediately before the predetermined position, and the inserted end is at the immediately preceding position. A composite preform configured to be smaller than a sliding resistance between the preform and the preform cover in the second state after exceeding.
The sliding resistance between the insertion end vicinity part and the preform cover in the first state is a part between the insertion end vicinity part and the preform cover in the second state. The composite preform according to claim 1, wherein the composite preform is smaller than dynamic resistance.
The similarity ratio of the inner surface shape of the preform cover to the outer surface shape of the preform is an inner surface similarity ratio,
The site near the opposite end that is the end opposite to the inserted end is the site near the opposite end,
When the insertion end side portion is a portion closer to the insertion end than the portion near the opposite end,
3. The composite preform according to claim 1, wherein an inner surface similarity ratio in the vicinity of the opposite end is smaller than an inner surface similarity ratio in the inserted end side portion.
The composite preform according to claim 3, wherein the thickness of the preform cover in the vicinity of the opposite end is larger than the thickness of the inserted end side portion.
When the similarity ratio of the outer surface shape of the preform cover to the outer surface shape of the preform is the outer surface similarity ratio,
The composite preform according to claim 3 or 4, wherein an outer surface similarity ratio in the vicinity of the opposite end is smaller than an outer surface similarity ratio in the inserted end side portion.
When a portion near the inserted end of the preform cover is a portion near the inserted end,
The sliding resistance between the preform in the first state and the portion near the insertion end is smaller than the sliding resistance between the preform in the second state and the portion near the insertion end. The composite preform according to any one of claims 1 to 5.
The preform includes a preform small diameter part and a preform large diameter part,
The preform large-diameter portion has a larger outer surface shape than the preform small-diameter portion, and is disposed at a position farther from the insertion end than the preform small-diameter portion. A composite preform according to any one of the above.
The preform cover includes a preform cover small diameter portion and a preform cover large diameter portion,
The composite preform according to claim 7, wherein the preform cover small-diameter portion and the preform cover large-diameter portion are disposed at positions facing the preform small-diameter portion and the preform large-diameter portion, respectively.
The composite preform according to claim 8, wherein a thickness at the large diameter portion of the preform cover is larger than a thickness at the small diameter portion of the preform cover.
When the similarity ratio of the outer surface shape of the preform cover to the outer surface shape of the preform is the outer surface similarity ratio,
The composite preform according to claim 8 or 9, wherein an outer surface similarity ratio at the preform cover large diameter portion is smaller than an outer surface similarity ratio at the preform cover small diameter portion.
A preform cover having an EVOH layer made of EVOH resin,
The EVOH resin is a preform cover having a maximum value of uniaxial elongation viscosity measured at a temperature of 180 ° C. and a strain rate of 10 s −1 of 3.0 × 10 4 (Pa · s) or more.
The preform cover according to claim 11, wherein the EVOH resin has an ethylene content of 32 mol% or less.
The preform cover according to claim 11 or 12, wherein the EVOH resin has an MFR measured under conditions of a temperature of 210 ° C and a load of 2.16 kg of 6 g / 10 min or less.
The preform cover according to any one of claims 11 to 13, wherein the EVOH layer is sandwiched between a pair of polyolefin layers.
The preform cover according to any one of claims 11 to 14, wherein the EVOH layer has a thickness of 0.3 to 1 mm.
A composite preform comprising a preform and a preform cover superimposed on the preform,
The composite preform, wherein the preform cover is the preform cover according to any one of claims 11 to 15.
A method for producing a container comprising a step of biaxially stretching blow molding the composite preform according to claim 16.