JP2018202629A - Preform, container and manufacturing method thereof - Google Patents

Abstract

To provide a preform that can be easily discriminated whether a gas barrier layer is appropriately formed.SOLUTION: According to the present invention, a preform composed of an injection molding is provided. The preform includes an outer layer, a gas barrier layer, and an inner layer in order from the outer surface side. The gas barrier layer is an EVOH resin layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a preform, a container, and a manufacturing method thereof.

  As a method for molding a plastic container, Patent Document 1 discloses a biaxial stretch blow molding method in which an injection-molded preform is set in a mold and air is blown into the shape of the mold cavity. ing.

  Patent Document 1 includes a preform having a laminated structure of three or more layers including a structure in which a cyclic olefin resin layer (A), a gas barrier layer (B), and a cyclic olefin resin layer (C) are sequentially arranged. A method for producing a container having excellent gas barrier properties by using it is disclosed.

JP 2011-235569 A

  By the way, when the preform is manufactured by injection molding by the method of Patent Document 1, it is necessary to cause the resin constituting the layers (A) to (C) to flow while maintaining the laminar flow in the cavity of the mold. . For this reason, when the flow of any of the resins constituting the layers (A) to (C) becomes insufficient, the layer may be interrupted in the middle. Since the gas barrier layer (B) is usually a thin layer of about 100 μm, it is particularly easy to break. When the gas barrier layer (B) is interrupted, the gas barrier properties are deteriorated. Therefore, when the gas barrier layer (B) is interrupted, it is necessary to detect this. However, since the preform of Patent Document 1 is transparent regardless of the presence or absence of the gas barrier layer (B) and has no difference in appearance, the gas barrier layer (B) is interrupted even when the manufactured preform is inspected. It is difficult to determine whether or not.

  The present invention has been made in view of such circumstances, and provides a preform that can easily determine whether or not a gas barrier layer is appropriately formed.

  According to the present invention, a preform composed of an injection-molded body, wherein the preform includes an outer layer, a gas barrier layer, and an inner layer in order from the outer surface side, and the gas barrier layer is an EVOH resin layer. A preform is provided.

  The present invention has been intensively studied. As a result, when the gas barrier layer is an EVOH resin layer, the gas barrier layer is formed because the portion where the gas barrier layer is formed becomes clouded by crystallization of the EVOH resin. Has been found to be easily discriminable in appearance, 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 outer layer and the inner layer are cyclic olefin resin layers.
Preferably, the EVOH resin contained in the EVOH resin layer has a melt flow rate measured at 210 ° C. and a load of 2.16 kg of 15 g / 10 min or less.
Preferably, the EVOH resin has a melt flow rate of 8 g / 10 min or less.
Preferably, the cyclic olefin resin contained in the cyclic olefin resin layer has a melt flow rate measured at a load of 2.16 kg at 280 ° C. of 40 g / 10 min or less.
Preferably, the melt flow rate of the cyclic olefin resin is 20 g / 10 min or less.

According to another aspect of the present invention, there is provided a container composed of the above-described biaxially stretched blow-molded preform.
Preferably, the container has a shape having a body portion, and the wall thickness of the container is 0.8 mm or more.
Preferably, the container has a shape having a body portion, and the container has a thickness of the gas barrier layer at the body portion of 20 μm or more.

  According to another viewpoint of this invention, the manufacturing method of a container provided with the process of carrying out the biaxial stretch blow molding of the preform described above is provided.

1 shows a configuration of a preform 1 according to an embodiment of the present invention, in which a left side of an alternate long and short dash line is a front view and a right side of the alternate long and short dash line is a cross-sectional view passing through the center of the preform 1. The structure of the container 11 of one Embodiment of this invention is shown, the left side of a dashed-dotted line is a front view, and the right side of a dashed-dotted line is sectional drawing which passes along the center of the container 11. FIG. FIG. 4 is an enlarged view of a region X in FIG. 3. It is an optical microscope photograph of the state which colored the gas barrier layer 6 by dividing the preform 1 of Example 5 into two.

  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.

1. Preform 1
As shown in FIG. 1, a preform 1 according to an embodiment of the present invention includes a cylindrical (preferably cylindrical) trunk portion 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 a bottom portion 4. Although the bottom part 4 is a curved surface shape in an example, the shape is not specifically limited. The preform 1 is formed of an injection molded body that can be formed by injection molding of a resin material.

  The thickness of the preform 1 at the body portion 2 is, for example, 1 to 10 mm, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 mm. It may be within a range between any two of the exemplified numerical values.

  The preform 1 includes an outer layer 5, a gas barrier layer 6, and an inner layer 7 in order from the outer surface side.

(Outer layer 5 and inner layer 7)
The outer layer 5 and the inner layer 7 are preferably composed of a cyclic olefin resin layer. The cyclic olefin resin layer is excellent in water vapor barrier properties. The cyclic olefin resin contained in the cyclic olefin resin layer is a polymer having an alicyclic structure in the main chain and / or side chain. Examples of the alicyclic structure of the polymer include a saturated cyclic hydrocarbon (cycloalkane) structure and an unsaturated cyclic hydrocarbon (cycloalkene) structure. Among these, from the viewpoints of mechanical strength, heat resistance and the like, a cycloalkane structure or a cycloalkene structure is preferable, and a cycloalkane structure is most preferable.

  The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15 in the mechanical strength, The properties of heat resistance and moldability are highly balanced and suitable.

  The proportion of the repeating unit having an alicyclic structure in the cyclic olefin resin may be appropriately selected according to the purpose of use, but is usually 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more. It is. If the ratio of the repeating unit having an alicyclic structure in the cyclic olefin resin is too small, the transparency and heat resistance are inferior.

  The remainder other than the repeating unit having an alicyclic structure in the cyclic olefin resin is not particularly limited and is appropriately selected according to the purpose of use.

  Specific examples of the cyclic olefin resin include norbornene-based polymers. The norbornene-based polymer is a known polymer disclosed in, for example, Japanese Patent Laid-Open Nos. 3-14882 and 3-122137, and specifically, a ring-opening polymer of a norbornene-based monomer. , Addition polymers of norbornene monomers, addition copolymers of norbornene monomers and vinyl compounds, and hydrogenated products thereof.

  The norbornene-based monomer is a monomer having a norbornene ring structure in the molecule, and specifically, bicyclo [2.2.1] -hept-2-ene, 5-ethylidene-bicyclo [2.2.1] -hepta. -2-ene, tricyclo [4.3.0.12,5] -deca-3,7-diene and the like. These norbornene monomers can be used alone or in combination of two or more.

  The vinyl compound is not particularly limited as long as it is copolymerizable with a norbornene monomer. For example, ethylene having 2 to 20 carbon atoms such as ethylene, propylene and 1-hexene or α-olefin; cycloolefin such as cyclobutene, cyclopentene, cyclohexene and cyclooctene; non-such as 1,4-hexadiene and 1,7-octadiene Conjugated dienes; and the like. These vinyl compounds can be used alone or in combination of two or more.

  The cyclic olefin resin preferably has a melt flow rate (MFR) measured at a load of 2.16 kg at 280 ° C. of 40 g / 10 min or less, and more preferably 20 g / 10 min or less. This MFR is, for example, 3 to 40 g / 10 min, specifically, for example, 3, 5, 10, 15, 20, 25, 30, 35, 40 g / 10 min. Or within a range between the two. MFR can be measured according to JIS K7210.

  The cyclic olefin resin preferably has a glass transition temperature (Tg) of 90 ° C. or higher, and more preferably 115 ° C. or higher. This Tg is, for example, 90 to 160 ° C., specifically, for example, 90, 100, 110, 120, 130, 140, 150, 160 ° C., and a range between any two of the numerical values exemplified here. It may be within. Tg can be measured according to JIS K7121.

  The cyclic olefin resin preferably has a molding shrinkage ratio of 12/1000 or less when injection-molded at 280 ° C., and is 8/1000 or less. This molding shrinkage is, for example, 1/1000 to 12/1000, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12/1000. It may be within a range between any two of the numerical values exemplified here. The molding shrinkage rate can be measured according to JIS K7152.

  The thicknesses of the outer layer 5 and the inner layer 7 are each preferably 500 to 5000 μm, and more preferably 1500 to 4000 μm. Specifically, this thickness is, for example, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000 μm, and is within a range between any two of the numerical values exemplified here. Also good.

(Gas barrier layer 6)
The gas barrier layer 6 is an EVOH (ethylene-vinyl alcohol copolymer) resin layer. In the case where the gas barrier layer 6 is an EVOH resin layer, the region where the gas barrier layer 6 is formed by crystallization of the EVOH resin becomes clouded, so it is easy to determine whether the gas barrier layer 6 is formed. The EVOH resin contained in the EVOH resin layer is obtained by hydrolysis of ethylene and vinyl acetate copolymer. The ethylene content of the EVOH resin is, for example, 25 to 50 mol%, and preferably 32 mol% or less from the viewpoint of oxygen barrier properties. Although the minimum of ethylene content is not prescribed | regulated in particular, since the softness | flexibility of EVOH resin layer tends to fall, so that ethylene content is small, 25 mol% or more is preferable.

  The EVOH resin preferably has a melt flow rate (MFR) measured at 210 ° C. under a load of 2.16 kg of 15 g / 10 min or less, and more preferably 8 g / 10 min or less. The MFR is, for example, 1 to 15 g / 10 min. Specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 g / 10 minutes, and may be within a range between any two of the numerical values exemplified here. A MFR of 8 g / 10 min or less is preferable because the peel resistance and film formability are particularly good.

  The EVOH resin preferably has a glass transition temperature (Tg) of 40 to 80 ° C, and more preferably 50 to 70 ° C. Specifically, this Tg is, for example, 40, 45, 50, 55, 60, 65, 70, 75, 80 ° C., and may be within a range between any two of the numerical values exemplified here. .

  The EVOH resin preferably has a molding shrinkage ratio of 12/1000 or less when injection molded at 280 ° C., and is 8/1000 or less. This molding shrinkage is, for example, 1/1000 to 12/1000, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12/1000. It may be within a range between any two of the numerical values exemplified here.

  The difference between the molding shrinkage rate of the gas barrier layer 6 and the molding shrinkage rate of the outer layer 5 or the inner layer 7 is preferably 8/1000 or less, and more preferably 5/1000 or less. This difference is, for example, 0 to 8/1000, specifically, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8/1000, and any one of the numerical values illustrated here is 2 It may be within a range between the two. When this difference is small, the peel resistance is good.

EVOH resin preferably has a weight average molecular weight of 1 to 100,000, specifically 1, 2, 3, 4, 5, 6, 7, 8, 9, 100,000. It may be within a range between any two. The EVOH resin having a weight average molecular weight of 30,000 or more is preferable because the interface between the gas barrier layer 6 and the outer layer 5 and the inner layer 7 becomes closer due to the slow crystallization speed. In measuring the weight average molecular weight of EVOH, EVOH can be re-acetylated and measured according to the method described in Journal of Japan Adhesion Association, 13 , 186 (1977).

  The thickness of the gas barrier layer 6 is preferably 20 μm or more, and more preferably 100 μm or more. The thickness is, for example, 20 to 600 μm, and specifically, for example, 20, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600 μm, and exemplified here. It may be within a range between any two of the numerical values. When the thickness of the gas barrier layer 6 is 100 μm or more, the visibility of the gas barrier layer 6 is particularly good, which is preferable.

(Other layers)
An adhesive layer may be provided between the layers in order to improve adhesiveness. The adhesive layer is made of, for example, a material obtained by adding an acid-modified polyolefin (for example, maleic anhydride-modified polyethylene) in which a carboxyl group is introduced to polyolefin, or an ethylene vinyl acetate copolymer (EVA). However, the provision of the adhesive layer leads to an increase in cost because the manufacturing difficulty of the preform 1 is increased and the yield is reduced. Therefore, the outer layer 5, the gas barrier layer 6, and the inner layer 7 are formed of the adhesive layer. It is preferable to directly contact without interposing.

2. Container 11
As shown in FIG. 2, the preform 1 is set in a mold and biaxially stretch blow-molded to form a container 11 corresponding to the cavity shape inside the mold. The preform 1 is biaxially stretched blow-molded before being set in a mold or after being set and heated and softened.

  As shown in FIG. 2, the container 11 includes a cylindrical (preferably cylindrical) body 12. A mouth portion 13 is provided at one end of the body portion 12, and an engaging portion 13 a for attaching a cap (not shown) is provided at the mouth portion 13. The cap may be attached by a stopper type or may be attached by a screw type. The other end of the trunk portion 12 is a bottom portion 14. The container 11 includes an outer layer 15, a gas barrier layer 16, and an inner layer 17 in order from the outer surface side. The outer layer 15, the gas barrier layer 16, and the inner layer 17 are layers formed by extending the outer layer 5, the gas barrier layer 6, and the inner layer 7, respectively.

  The draw ratio defined by (the thickness of the body portion 2 of the preform 1) / (the thickness of the body portion 12 of the container 11) is, for example, 2 to 10 times, specifically, for example, 2, 3, It is 4, 5, 6, 7, 8, 9, 10 times, and may be in the range between any two of the numerical values exemplified here.

  The wall thickness of the body 12 of the container 11 is, for example, 0.2 to 2 mm, and specifically, for example, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1 .4, 1.6, 1.8, and 2 mm, and may be within a range between any two of the numerical values exemplified here. This wall thickness is preferably 0.8 mm or more. In this case, sterilization suitability and drop resistance are particularly good, which is preferable.

  The thicknesses of the outer layer 15 and the inner layer 17 are each preferably 100 to 1000 μm, and more preferably 300 to 800 μm. Specifically, this thickness is, for example, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 μm, and is within a range between any two of the numerical values exemplified here. Also good.

  The thickness of the gas barrier layer 16 is preferably 5 μm or more, and more preferably 20 μm or more. This thickness is, for example, 5 to 120 μm, specifically, for example, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120 μm, and is exemplified here. It may be within a range between any two of the numerical values. When the thickness of the gas barrier layer 16 is 20 μm or more, the visibility of the gas barrier layer 16 is particularly good, which is preferable.

1. Production and Evaluation of Preform 1 Using the resin shown in Table 1, Preform 1 having the layer configuration shown in Table 2 and having the shape shown in FIG. 1 was formed by injection molding under the condition of a mold temperature of 280 ° C. The thickness shown in Table 2 is an average value of values measured at eight points in the circumferential direction at the center in the height direction of the body portion 2 of the preform 1.

  About the obtained preform 1, various evaluation was performed with the following method. For each of the examples and comparative examples, 10 samples were prepared and evaluated. Of the 10 samples, the one with the lowest evaluation was used as the evaluation of the examples and comparative examples. The results are shown in Table 2.

<Visibility of gas barrier layer>
Using a spectrophotometer UV-2400PC manufactured by Tsu Seisakusho, the total light transmittance at a wavelength of 450 nm of the preform 1 was measured and evaluated according to the following criteria. If the gas barrier layer visibility is poor, it is difficult to confirm whether the gas barrier layer is formed.
○: Light transmittance is 40% or less Δ: Light transmittance is more than 40% and less than 65% ×: Light transmittance is 65% or more

<Peeling resistance>
The preform 1 was visually observed immediately after molding and after cooling to confirm whether the gas barrier layer 6 was peeled from the outer layer 5 or the inner layer 7 and evaluated according to the following criteria. If the peel resistance is poor, the handling property of the preform 1 is deteriorated.
○: not peeled Δ: peeled when cooled ×: peeled immediately after molding

<Film-forming properties>
The preform 1 was divided into four in the circumferential direction, the state of the gas barrier layer 16 in each cross section was observed with an optical microscope, and evaluated according to the following criteria. If the film forming property is poor, the gas barrier layer is easily interrupted during blow molding. FIG. 4 is a photograph taken in a state where the preform 1 of Example 5 is divided into two and the gas barrier layer 16 is colored, and shows a state in which a non-uniform portion 6 a is formed in the vicinity of the mouth 3. The gas barrier layer 16 was colored using an iodine solution (Japanese Pharmacopoeia, dilute iodine tincture, manufactured by Kenei Pharmaceutical Co., Ltd.).
○: Gas barrier layer is formed uniformly Δ: Non-uniform portion is formed in the gas barrier layer ×: Gas barrier layer is interrupted

Details of each resin in Table 1 are as follows.
COP: Cyclic olefin resin (manufactured by Nippon Zeon Co., Ltd., model “ZEONEX690R”)
COP2: Cyclic olefin resin (manufactured by Nippon Zeon Co., Ltd., model “ZEONOR1020R”)
EVOH: EVOH resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., model “DC3203FB”)
EVOH2: EVOH resin 2 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., model “DC3212B”)
MXD: Nylon MXD6 (Mitsubishi Gas Chemical Co., Ltd., Model “MX Nylon S6007”)

<Discussion>
In Comparative Example 1 using MXD as the gas barrier layer 6, the preform 1 was transparent, and the visibility of the gas barrier layer was poor. On the other hand, in all examples using EVOH resin as the gas barrier layer 6, the preform 1 was cloudy and the light transmittance was less than 65% (40% or less in Examples 1, 2, 4 and 5). It was. In addition, the comparison between Example 1 and Example 4 demonstrates that the use of EVOH resin having a melt flow rate measured at 210 ° C. of 8 g / 10 min or less improves the peel resistance and film forming property. It was. Further, by comparing Example 1 and Example 5, it was demonstrated that the film forming property was improved by using a cyclic olefin resin having a melt flow rate measured at 280 ° C. of 20 g / 10 min or less.

2. Production and Evaluation of Container 11 Biaxial stretch blow molding was performed so that the stretch ratio was about 4.5 times while the preform 1 was heated to 100 ° C. to form the container 11 shown in FIG. The diameter of the body 11 of the container 11 was 50 mm. The thickness of the obtained container at the body portion 12 was as shown in Table 3. The thickness shown in Table 3 is an average value of values measured at eight points in the circumferential direction at the center of the body portion 12 of the container 11 in the height direction. Various evaluations were performed on this container by the following methods.

<Sterilization aptitude>
Autoclave sterilization was carried out at 121 ° C. for 20 minutes, and it was visually confirmed whether the container 11 was deformed and evaluated according to the following criteria. If the sterilization suitability is poor, the sterilization time is extended, or the container 11 is deformed during sterilization.
○: No deformation △: Slight deformation ×: Large deformation

<Peeling resistance>
The container 11 was visually observed immediately after film formation to confirm whether the gas barrier layer 16 was peeled off from the outer layer 15 or the inner layer 17. Further, the state in which the center of the body portion 12 of the container 11 was recessed by 5 mm toward the center was also visually observed and evaluated according to the following criteria. When the peel resistance is poor, the handling property of the container 11 is poor.
○: not peeled even if recessed, Δ: peeled when recessed ×: peeled immediately after molding

<Gas barrier properties>
Using a MOCON OX-TRAN 2/20 measuring instrument, measure the inside of the bottle at 90% RH in a measurement environment of 23 ° C.-55% RH under atmospheric pressure, and permeate the container body per day. The amount of oxygen (cc) was measured and evaluated according to the following criteria. If the gas barrier property is poor, the contents are likely to deteriorate.
○: 0.0005 cc / day or less Δ: More than 0.0005 cc / day, less than 0.0025 cc / day ×: 0.0025 cc / day or more

<Drop resistance>
The container 11 was dropped 10 times onto a flat rigid plate having a thickness of 25 mm from a height of 1 m at room temperature with the bottom 14 facing downward, and the container 11 was visually observed and evaluated according to the following criteria. . If the drop resistance is poor, the container 11 is likely to be damaged when dropped.
○: No change △: Cracks entered ×: Content liquid leaks

<Discussion>
Comparison between Example 1 and Example 4 demonstrated that the peel resistance was improved by using an EVOH resin having a melt flow rate measured at 210 ° C. of 8 g / 10 min or less. Further, by comparing Example 1 and Example 5, it was demonstrated that sterilization resistance was improved by using a cyclic olefin resin having a melt flow rate measured at 280 ° C. of 20 g / 10 min or less.

  The preform 1 that was cloudy in Examples 1 to 5 was subjected to biaxial stretch blow molding, so that the molded container 11 became transparent. At the time of the preform 1, it is easy to detect the gas barrier layer by being clouded, but after forming the container, a transparent container can be obtained without clouding.

1: Preform 2: Body part 3: Mouth part 3a: Engagement part 4: Bottom part 5: Outer layer 6: Gas barrier layer 6a: Inhomogeneous part 7: Inner layer 11: Container 12: Body part 13: Mouth part 13a: Engagement Part 14: bottom 15: outer layer 16: gas barrier layer 17: inner layer X: region

Claims (10)

A preform composed of an injection molded body,
The preform includes an outer layer, a gas barrier layer, and an inner layer in order from the outer surface side.
The preform, wherein the gas barrier layer is an EVOH resin layer.   The preform according to claim 1, wherein the outer layer and the inner layer are cyclic olefin resin layers.   The preform according to claim 1 or 2, wherein the EVOH resin contained in the EVOH resin layer has a melt flow rate measured at 210 ° C and a load of 2.16 kg of 15 g / 10 min or less.   The preform according to claim 3, wherein a melt flow rate of the EVOH resin is 8 g / 10 minutes or less.   The cyclic olefin resin contained in the cyclic olefin resin layer has a melt flow rate measured at a load of 2.16 kg at 280 ° C of 40 g / 10 min or less, according to any one of claims 1 to 4. preform.   The preform according to claim 5, wherein the cyclic olefin resin has a melt flow rate of 20 g / 10 min or less.   A container comprising the biaxially stretched blow molded product of the preform according to any one of claims 1 to 6. The container has a shape having a trunk,
The said container is a container of Claim 7 whose thickness in the said trunk | drum is 0.8 mm or more. The container has a shape having a trunk,
The said container is a container of Claim 7 or Claim 8 whose thickness of the said gas barrier layer in the said trunk | drum is 20 micrometers or more.   The manufacturing method of a container provided with the process of carrying out the biaxial stretch blow molding of the preform as described in any one of Claims 1-6.