WO2023095409A1

WO2023095409A1 - Synthetic resin container

Info

Publication number: WO2023095409A1
Application number: PCT/JP2022/032909
Authority: WO
Inventors: 弘光清都; 秀人門前; 仁藤岡; 誠士柴田
Original assignee: 東洋製罐株式会社
Priority date: 2021-11-26
Filing date: 2022-09-01
Publication date: 2023-06-01
Also published as: JP2023078988A

Abstract

Provided is a container comprising: a container body formed in a predetermined container shape including a mouth part, a shoulder part, a trunk part, and a bottom part; and a coating layer releasably laminated on the outer peripheral surface side of the container body, wherein at least a portion of the surface of the coating layer is roughened, and the friction coefficient of the roughened surface is less than 1.0.

Description

Synthetic resin container

The present invention relates to a synthetic resin container provided with a detachably laminated covering layer.

Conventionally, synthetic resin containers have been manufactured by using a thermoplastic resin such as polyethylene terephthalate to prepare a bottomed tubular preform, and molding this preform into a bottle shape by biaxial stretch blow molding or the like. , various beverages, and various seasonings.

In recent years, this type of synthetic resin container has become more and more familiar, and various proposals have been made accordingly. Under such circumstances in recent years, the present applicant, in Patent Document 1, produced a preform in which a coating material layer was laminated by double molding, and blow-molded the preform, thereby detachably laminated. It is proposed to produce a synthetic resin container with a coating layer.

JP 2020-90297 A

The inventors of the present invention have made intensive studies on points for improving the synthetic resin container provided with the coating layer as described above. I found In order to prevent such a problem from occurring, the present invention was completed as a result of repeated further studies.

A synthetic resin container according to the present invention comprises a container body formed into a predetermined container shape including a mouth portion, a shoulder portion, a body portion and a bottom portion, and a coating layer detachably laminated on the outer peripheral surface side of the container body. At least part of the surface of the coating layer is roughened, and the roughened surface has a coefficient of friction of less than 1.0.

According to the present invention, in a synthetic resin container provided with a releasably laminated coating layer, it is possible to reduce resistance due to friction of the coating layer.

1 is a perspective view showing an outline of a synthetic resin container according to an embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows the outline of the synthetic resin containers which concern on embodiment of this invention. It is an explanatory view showing an example of a mold. It is a longitudinal section showing an outline of a preform. FIG. 4 is an explanatory diagram of a primary injection process; It is explanatory drawing of a secondary injection process.

Preferred embodiments of the present invention are described below with reference to the drawings.
FIG. 1 is a perspective view schematically showing a synthetic resin container according to this embodiment, and FIG. 2 is a front view of the same.

The container 1 shown in these figures comprises a container body 1a molded into a predetermined container shape including a mouth portion 2, a shoulder portion 3, a body portion 4 and a bottom portion 5, and a container body 1a which is detachably laminated on the outer peripheral surface side of the container body 1a. and a coated coating layer 6 . In the illustrated example, the container 1 (container main body 1a) has a container shape generally called a round bottle, in which the body portion 4 is formed in a cylindrical shape. is not limited to For example, a container shape called a rectangular bottle, or a constricted shape in which a portion of the body portion 4 is partially greatly reduced in diameter may be used.

FIG. 2 shows a cross section of the mouth portion 2 and the shoulder portion 3 with part cut away, and the thicknesses of the container body 1a and the coating layer 6 appearing in the cross section are exaggerated. .

The mouth portion 2 is a cylindrical part that serves as an outlet for pouring contents, and a side surface of the mouth portion 2 on the open end side is provided with a screw thread 2a for attaching a lid (not shown).
Further, the mouth portion 2 is provided with an annular neck ring 2b protruding outward along the circumferential direction. The mouth portion 2 includes the neck portion 2c which has a substantially uniform diameter and extends in a cylindrical shape from directly below the neck ring 2b.

The lower end of such a mouth portion 2 is connected to a shoulder portion 3 that expands in diameter toward the body portion 4 and connects the mouth portion 2 and the body portion 4 . In the illustrated example, the shoulder portion 3 is formed in a rounded truncated cone shape, but the shape of the shoulder portion 3 is not limited to this. For example, it can be formed in a so-called hanging neck shape.

Also, the body portion 4 is a portion that occupies most of the height direction of the container 1 , and has an upper end connected to the shoulder portion 3 and a lower end connected to the bottom portion 5 . In the illustrated example, the container 1 has a bottom portion 5 formed in a so-called petaloid shape so as to be suitable for use with a carbonated beverage as its content, but the shape of the bottom 5 is different for a non-carbonated beverage as its content. It may have other shapes suitable for the intended use, and can be changed as appropriate according to the intended use.

Here, the height direction refers to the direction perpendicular to the horizontal surface when the container 1 is erected on a horizontal surface with the mouth portion 2 facing up. up, down, left, right, and vertical and horizontal directions.

In the container 1 molded into such a container shape, the coating layer 6 can be laminated so as to cover at least the body portion 4 . In the illustrated example, the entire peripheral surface of the trunk portion 4 from the bottom surface of the bottom portion 5 is covered with the coating layer 6, and the end side of the coating layer 6 covers the entire circumference of the neck portion 2c on the lower end side of the mouth portion 2. It is laminated so as to cover and reach directly below the neck ring 2b.

Next, a method for manufacturing a synthetic resin container according to this embodiment will be described.
FIG. 3 shows an example of a mold 100 used for blow-molding the container 1 described above. The mold 100 forms a body mold 104 for molding the shoulder portion 3 and the body portion 4 and the bottom portion 5. A bottom mold 105 is provided. The barrel mold 104 is composed of a pair of split molds that can be opened and closed, and FIG. 3 shows a simplified cross section of the mold 100 taken along a plane including the parting surface of the barrel mold 104 .

Further, FIG. 4 shows an example of a preform 10 blow-molded into the container 1 described above. The preform 10 is detachably laminated on the preform main body 10a and the outer peripheral surface side of the preform main body 10a. and a covering material layer 60 .

When the preform body 10a is blow-molded as will be described later, the preform body 10a has a mouth portion forming region 20 which substantially maintains its appearance and becomes the mouth portion 2 of the container body 1a and a shoulder portion 3 of the container body 1a which is stretched. , a body portion 4 and an elongated region 30 formed on the bottom portion 5, and are formed into a bottomed cylindrical shape. The mouth forming region 20 of the preform body 10a is provided with a screw thread 2a and a neck ring 2b indicated by the same reference numerals as the container 1, and the neck ring 2b of the mouth forming region 20 is provided. The lower portion of is the neck portion 2c of the container body 1a.

Here, FIG. 4 is a vertical cross-sectional view of the preform 10, in which the thicknesses of the preform main body 10a and the coating material layer 60 appearing in the cross section are exaggerated.
Further, the vertical and horizontal directions and the vertical and horizontal directions of the preform 10 are defined in the state shown in FIG.

Also, the covering material layer 60 laminated on the preform main body 10 a can be laminated so that the end side thereof covers the lower end side of the mouth forming region 20 . In the illustrated example, the entire surface of the stretched region 30 is covered with the covering material layer 60, and the distal end of the covering material layer 60 is positioned below the neck ring 2b of the mouth forming area 20 (the neck of the container body 1a). It is laminated so as to cover the entire periphery of the lower portion 2c and reach directly below the neck ring 2b.

Such a preform 10 can be produced as follows by an injection molding method called double molding.

First, a core mold 400 for molding the inner peripheral surface and the upper end surface of the preform body 10a, an upper mold 401 for molding the upper outer peripheral surface of the preform body 10a including the upper surface and the peripheral end surface of the neck ring 2b, and the neck ring. The first lower mold 402a for molding the lower outer peripheral surface of the preform body 10a from the lower surface to the bottom of 2b is clamped, and the resin material forming the preform body 10a is injected (see FIG. 5). ). As a result, the preform body 10a molded into a cylindrical shape with a bottom including the opening forming region 20 and the extending region 30 is injection molded (primary injection step).

Next, instead of the first lower mold 402a, a second lower mold 402b configured to form a gap for molding the coating material layer 60 between the molded preform body 10a is used. After re-closing the molds, the resin material forming the covering material layer 60 is injected (see FIG. 6). As a result, the covering material layer 60 that is detachably laminated on the outer peripheral surface side of the preform main body 10a and whose terminal side covers the lower end side of the mouth portion forming region 20 (the part below the neck ring 2b) is injection molded (second next injection process).

The first and second

lower molds

402a and 402b are usually provided with a gate serving as an injection port for the resin material at a position corresponding to the bottom side of the preform 10. However, as shown in FIGS. In the example shown in , illustration of gates is omitted.

As the resin material forming the preform main body 10a (that is, the resin material forming the container main body 1a), considering the recyclability required for the container 1, it is preferable to use ethylene terephthalate-based thermoplastic polyester such as polyethylene terephthalate. can.

As the resin material forming the coating material layer 60 (that is, the resin material forming the coating layer 6), the coating material layer 60 (coating layer 6) is detachably laminated on the preform body 10a (container body 1a). From the viewpoint of making the preform main body 10a compatible, it is preferable to use a thermoplastic resin that is incompatible with the resin material forming the preform main body 10a. For example, when ethylene terephthalate-based thermoplastic polyester is used as the resin material forming the preform body 10a, it is particularly preferable to use a polyolefin resin such as polypropylene or polyethylene as the resin material forming the coating material layer 60. If the container 1 is required to have gas barrier properties, the resin material forming the coating material layer 60 may be a thermoplastic resin having gas barrier properties such as ethylene-vinyl alcohol copolymer or polymeta-xylylene adipamide (MXD6). Resin can also be used. A pigment or a coloring agent may be added to the resin material forming the coating material layer 60 to give it a desired hue, thereby imparting light-shielding properties. In order to enhance the decorative effect, a plurality of pigments or colorants may be mixed and added to form a marble pattern. Various additives can be added to the resin material forming the coating material layer 60 as necessary without being restricted by the recyclability required for the container 1 .

The preform 10 produced in this manner is softened by heating to be ready for blow molding, and then set in a mold 100 as indicated by the dashed line in FIG. While being stretched in the axial direction (longitudinal direction) by a non-stretching rod, the preform 10 is stretched in the axial direction and the circumferential direction (lateral direction) by blow air blown into the preform 10 .

When heating the preform 10 , for example, the preform 10 is heated from the coating material layer 60 side by an infrared heater or the like, and a rod-shaped high-frequency induction heating element heated by high-frequency induction heating is inserted into the preform 10 . It is preferable to appropriately adjust the heating temperature from the inside and outside by heating the preform main body 10a from the inside as well.

By blow-molding the preform 10 in this manner, the mouth forming region 20 of the preform body 10a is not stretched except for the connecting portion with the stretching region 30 on the lower end side, and the appearance is generally It is maintained and becomes the mouth portion 2 of the container main body 1a. Then, the stretched region 30 is stretched and the shape of the cavity surface 101 of the mold 100 is transferred, thereby forming the shoulder portion 3, the body portion 4 and the bottom portion 5 of the container body 1a, and the preform body 10a. The covering material layer 60 laminated on the container body 1a is molded integrally with the preform body 10a to form the covering layer 6 laminated on the container body 1a.

The container 1 manufactured by blow-molding the preform 10 as described above is usually transported to a filling process, where the contents are filled and sealed, then boxed, and then loaded onto a truck or the like. shipped. Therefore, the container 1 is required to be designed in consideration of the influence of vibration during transportation. If the frictional resistance of the layer 6 is large and it is in a non-slip state, the surface of the coating layer 6 is likely to be damaged by abrasion, which may lead to poor appearance, which is not preferable.
In addition, in the conveying process after manufacturing the container 1 and the filling process, the container 1 may be slid and conveyed on the line, and the coating layer 6 prevents the container 1 from slipping. As a result, there is a risk that the container 1 will fall over in the middle of the transport line, causing trouble in transport.

In this embodiment, the surface of the coating layer 6 is roughened, and the coefficient of friction of the roughened surface is appropriately adjusted to be less than 1.0, thereby effectively solving such problems. make it avoidable.
The coefficient of friction of the surface of the coating layer 6 is the coefficient of static friction μs between the coating layers 6 measured according to JIS K 7125:1999 "Test method for coefficient of friction".

Also, in adjusting the coefficient of friction of the surface of the coating layer 6 by roughening the surface of the coating layer 6, the correlation between the coefficient of friction of the surface of the coating layer 6 and the surface roughness parameter , According to the inventors' examination, although the correlation with the arithmetic mean height Ra, which is an index of the height difference of unevenness, is low, the correlation with the reciprocal 1/Ra of the arithmetic mean height Ra tends to be slightly high. It was found that there is a partial correlation with the skewness Rsk, which is an index of unevenness of unevenness. Therefore, as a parameter of the surface roughness, in addition to the arithmetic mean height Ra, skewness Rsk, which is an index of unevenness of unevenness, is introduced. /Ra and skewness Rsk as explanatory variables, and the friction coefficient (static friction coefficient μs) of the surface of the coating layer 6 as an objective variable, multiple regression analysis was performed. A high correlation was found.
Regression formula: μs=0.035/Ra+0.097×Rsk+0.2

Such a correlation is particularly strong when the resin material forming the coating layer 6 is low-density polyethylene. It is preferable to roughen the surface of the coating layer 6 so that the arithmetic mean height Ra is large and the skewness Rsk is small within the range satisfying Ra+0.097×Rsk+0.2<1.0.
Further, the correlation shown in the above regression equation tends to be recognized regardless of the resin material forming the coating layer 6, although there are some differences in the values of the coefficients and constant terms. In view of this, regardless of the resin material forming the coating layer 6, the arithmetic mean height Ra is preferably 0.1 or more, more preferably 1.8 to 10, and the skewness Rsk is preferably 0.2 or less, more preferably -1.0 to 0.

In order to roughen the surface of the coating layer 6, as described above, when the preform 10 is blow-molded, the cavity surface 101 of the mold 100 for molding the stretched stretched region 30 is roughened. It is preferable to transfer the roughened cavity surface 101 to the surface of the coating layer 6 that is molded in close contact with the cavity surface 101 by performing the roughening treatment.

Mold 100 is usually formed using a hard material such as stainless steel or aluminum alloy. The surface can be roughened by blasting such as shot blasting using a projecting material such as glass powder, alumina, or carborundum, or laser blasting by laser irradiation. When the surface is roughened by shot blasting, the particle size of the projection material, the spraying pressure, etc. are appropriately adjusted so that the arithmetic mean height Ra and the skewness Rsk of the roughened surface transferred to the surface of the coating layer 6 are desired values. However, laser blasting is preferable because the arithmetic mean height Ra and the skewness Rsk of the rough surface transferred to the surface of the coating layer 6 can be adjusted more easily.

Here, if the skewness Rsk is too small or too large, it tends to be difficult to process the cavity surface 101 when performing the roughening treatment. If the arithmetic mean height Ra is too small, mold release failure tends to occur, and if the arithmetic mean height Ra is too large, the haze of the coating layer 6 tends to increase. In consideration of these matters, it is preferable to adjust the arithmetic mean height Ra and the skewness Rsk of the rough surface transferred to the surface of the coating layer 6 so as to fall within the ranges described above.

In addition, roughening the surface of the coating layer 6 is not limited to roughening the entire surface of the coating layer 6 . For example, the portion where adjacent containers 1 in a boxed state come into contact with each other, the sliding surface of the bottom portion 5 when the conveying line is slid, the portion where the conveying guide is contacted when the conveying line is slid, etc., as described above. In order to avoid problems, at least a part of the surface of the coating layer 6 may be roughened corresponding to an arbitrary portion of the container 1 where the resistance due to friction of the coating layer 6 is required to be reduced. good.

The present invention will be described in more detail below with specific examples.

[Example 1]
Using polyethylene terephthalate as the resin material forming the preform main body 10a and using polyethylene (low-density polyethylene) as the resin material forming the coating layer 60, the preform 10 shown in FIG. 4 was produced by double molding. . Then, after softening the preform 10 by heating so that it can be blow-molded, it is set in the mold 100 and blow-molded to obtain the number of containers 1 shown in FIGS. 1 and 2 required for evaluation. manufactured.

The entire surface of the cavity surface 101 of the mold 100 was roughened by shot blasting using glass beads (J70 GB705K manufactured by Potters Barrotini) as a projection material. At that time, the blowing pressure was 0.3 MPa. Cavity surface 101 subjected to such a roughening treatment was transferred, and the surface roughness of roughened coating layer 6 was measured by a surface roughness measuring instrument, and the arithmetic average height Ra was 1.8. , the skewness Rsk was −0.33.

Also, a test piece was cut out from the coating layer 6 of each of two containers 1 arbitrarily selected from the manufactured containers 1 . Using this test piece, the static friction coefficient μs between the coating layers 6 was measured according to JIS K 7125:1999 "Friction coefficient test method", and the value was 0.18.

<Vibration test>
Each of 12 containers 1, which were arbitrarily selected from the manufactured containers 1, were filled and sealed and packed in a carton containing 12 (3×4) pieces. This was fixed to a vibration table of a vibration tester, and a random vibration test was performed in accordance with JIS Z 0232:2020 "Packaged freight-Vibration test method". The test conditions were vibration direction: vertical (longitudinal), average acceleration: 5.8 m/s ² , vibration frequency: 10 Hz, and test time: 90 minutes.

<Evaluation>
After completion of the test, each of the 12 containers 1 taken out of the carton was visually observed for the occurrence of dust blowing scratches, and evaluated according to the following evaluation criteria.
⊚: No problem in appearance ⊚: Small-level dust blowing flaws that are difficult to judge visually ×: Large-level dust blowing flaws that can be clearly judged visually Table 1 shows the evaluation results.

[Example 2]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass beads (J80 GB704K manufactured by Potters-Barotini) as a projection material. evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 1.6 and the skewness Rsk was -0.18.
Also, the coefficient of static friction μs between the coating layers 6 was 0.23.

[Example 3]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass beads (J100 GB703K manufactured by Potters-Barotini) as a projection material. evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 1.2 and the skewness Rsk was -0.12.
Also, the coefficient of static friction μs between the coating layers 6 was 0.22.

[Example 4]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass beads (J320 GB732 manufactured by Potters-Barotini) as a projection material. evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 0.9 and the skewness Rsk was -0.25.
Also, the coefficient of static friction μs between the coating layers 6 was 0.21.

[Example 5]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass beads (J400 GB731 manufactured by Potters-Barotini) as a projection material. evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 0.4 and the skewness Rsk was -0.13.
Also, the coefficient of static friction μs between the coating layers 6 was 0.27.

[Example 6]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Morundum (registered trademark) F16 manufactured by Showa Denko) as a projection material. and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic average height Ra was 10.7 and the skewness Rsk was 0.16.
Also, the coefficient of static friction μs between the coating layers 6 was 0.22.

[Example 7]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Morundum (registered trademark) F24 manufactured by Showa Denko) as a projection material. and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic average height Ra was 7.5 and the skewness Rsk was -0.02.
Also, the coefficient of static friction μs between the coating layers 6 was 0.20.

[Example 8]
The container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Morundum (registered trademark) F36 manufactured by Showa Denko) as a projection material. and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 6.2 and the skewness Rsk was -0.13.
Also, the coefficient of static friction μs between the coating layers 6 was 0.20.

[Example 9]
The container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Morundum (registered trademark) F60 manufactured by Showa Denko) as a projection material. and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic average height Ra was 3.4 and the skewness Rsk was 0.03.
Also, the coefficient of static friction μs between the coating layers 6 was 0.23.

[Example 10]
Container 1 in the same manner as in Example 1, except that carborundum (manufactured by Showa Denko Co., Ltd.: Densic (registered trademark) CF46) was used as a projection material and the entire cavity surface 101 was roughened by shot blasting. was manufactured and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 4.8 and the skewness Rsk was 0.07.
Also, the coefficient of static friction μs between the coating layers 6 was 0.20.

[Example 11]
Container 1 in the same manner as in Example 1, except that carborundum (manufactured by Showa Denko Co., Ltd.: Densic (registered trademark) CF100) was used as a projection material and the entire cavity surface 101 was roughened by shot blasting. was manufactured and evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 1.8 and the skewness Rsk was -0.09.
Also, the coefficient of static friction μs between the coating layers 6 was 0.21.

[Example 12]
A container 1 was manufactured in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass powder (manufactured by Potters-Barotini: GP250A) as a projection material. evaluated.
In this example, when the surface roughness of the roughened coating layer 6 was measured with a surface roughness measuring machine, the arithmetic mean height Ra was 3.7 and the skewness Rsk was -0.08.
Also, the coefficient of static friction μs between the coating layers 6 was 0.19.

[Comparative Example 1]
The container 1 was manufactured and evaluated in the same manner as in Example 1, except that the cavity surface 101 was not roughened and the cavity surface 101 was mirror-finished.
In this comparative example, when the surface roughness of the coating layer 6 was measured by a surface roughness measuring machine, the arithmetic mean height Ra was less than 0.1 and the skewness Rsk was −0.96.
Also, the coefficient of static friction μs between the coating layers 6 was 1.00.

Although the present invention has been described above with reference to preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications can be made within the scope of the present invention. Nor.

REFERENCE SIGNS LIST 1 container 1a container body 2 mouth portion 3 shoulder portion 4 trunk portion 5 bottom portion 6 coating layer

Claims

A synthetic resin container comprising a container body formed into a predetermined container shape including a mouth, a shoulder, a body and a bottom, and a coating layer detachably laminated on the outer peripheral surface of the container body. ,
A synthetic resin container, wherein at least a portion of the surface of the coating layer is roughened, and the friction coefficient of the roughened surface is less than 1.0.
The synthetic resin container according to claim 1, wherein the roughened surface of the coating layer has an arithmetic mean height Ra of 0.1 or more and a skewness Rsk of 0.2 or less.
The synthetic resin container according to claim 1 or 2, wherein the coating layer is made of low-density polyethylene.
Between the arithmetic mean height Ra of the roughened surface of the coating layer and the skewness Rsk,
0.035/Ra+0.097×Rsk+0.2<1.0
4. The synthetic resin container according to claim 3, wherein the following relationship holds.