Synthetic resin container

Abstract

To avoid any trouble caused by resistance due to large friction of coating layers, according to a synthetic resin container comprising the coating layers laminated in a peelable manner.SOLUTION: A container 1 comprises a container body 1a provided with a mouth part 2, a shoulder part 3, a trunk part 4 and a bottom part 5, that is formed into a predetermined container shape; and a coating layer 6 laminated on an outer peripheral face side of the container body 1a in a peelable manner. At least a part of a surface of the coating layer 6 is roughened, and the roughened surface is made to have a friction coefficient of less than 1.0.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a synthetic resin container provided with a coating layer laminated detachably.

Background Art

[0002] Conventionally, a preform formed into a bottomed cylindrical shape using a thermoplastic resin such as polyethylene terephthalate is produced, and a synthetic resin container formed into a bottle shape by biaxially stretching blow molding or the like of this preform is used in a wide range of fields as a container containing various beverages, various seasonings, etc. as contents.

[0003] This type of synthetic resin container has become an increasingly familiar presence in recent years, and various proposals have been made accordingly. In such recent circumstances, the present applicant has proposed in Patent Document 1 to produce a preform in which a coating material layer is laminated by double molding, and to produce a synthetic resin container provided with a coating layer laminated detachably by blow molding such a preform.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of the present invention have intensively studied the improvement points of a synthetic resin container provided with a coating layer as described above, and have found that if the resistance due to friction of the coating layer is large, there is a risk of problems caused thereby. And as a result of further intensive studies to prevent such problems from occurring, the present invention has been completed.

Means for Solving the Problems

[0006] The synthetic resin container according to the present invention comprises a container body formed in a predetermined container shape including a mouth, shoulder, body and bottom, and a coating layer peelably laminated on the outer circumferential surface side of the container body, wherein at least a portion of the surface of the coating layer is roughened. The measurements of the coating layers were taken in accordance with JIS K 7125:1999. The roughened surface Static friction coefficient It is considered to be less than 1.0 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 A relationship is established. It is part of the structure. [Effects of the Invention]

[0007] According to the present invention, in a synthetic resin container having a peelable laminated coating layer, the resistance due to friction of the coating layer can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view showing a synthetic resin container according to an embodiment of the present invention. [Figure 2] This is a schematic front view showing a synthetic resin container according to an embodiment of the present invention. [Figure 3] This is an explanatory diagram showing an example of a molding die. [Figure 4] This is a longitudinal cross-sectional view showing the general outline of the preform. [Figure 5] This is an explanatory diagram of the primary injection process. [Figure 6] This is an explanatory diagram of the secondary injection process. [Modes for carrying out the invention]

[0009] Preferred embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic perspective view of a synthetic resin container according to this embodiment, and Figure 2 is a front view thereof.

[0010] The container 1 shown in these figures comprises a container body 1a molded into a predetermined container shape including a mouth portion 2, shoulder portion 3, body portion 4, and bottom portion 5, and a coating layer 6 that is peelably laminated to the outer circumferential surface of the container body 1a. In the illustrated example, the container 1 (container body 1a) has a container shape generally referred to as a round bottle, with the body portion 4 formed in a cylindrical shape, but the shape of the container 1 is not limited to this. For example, it can have a container shape referred to as a square bottle, or a shape in which a part of the body portion 4 is partially significantly narrowed in diameter.

[0011] Note that Figure 2 shows a cross-section of the container body 1a and the covering layer 6, with parts of the mouth 2 and shoulder 3 cut out, and the thickness of these parts is exaggerated in the cross-section.

[0012] The mouth portion 2 is a cylindrical part that serves as an outlet for injecting the contents, and a screw thread 2a for attaching a lid (not shown) is provided on the side of the opening end of the mouth portion 2. Furthermore, the mouth portion 2 is provided with an annular neck ring 2b that protrudes outward along the circumferential direction. The mouth portion 2 includes the neck portion 2c, which hangs down in a cylindrical shape with approximately the same diameter directly below the neck ring 2b.

[0013] The lower end of the mouth portion 2 expands in diameter toward the body portion 4 and connects to a shoulder portion 3 that connects the mouth portion 2 and the body portion 4. In the illustrated example, the shoulder portion 3 is formed in the shape of a rounded frustocone, but the shape of the shoulder portion 3 is not limited to this. For example, it can also be formed in the shape of a so-called swan neck.

[0014] Furthermore, the body portion 4 occupies most of the height of the container 1, with its upper end connected to the shoulder portion 3 and its lower end connected to the bottom portion 5. In the illustrated example, the container 1 is equipped with a bottom portion 5 formed in a so-called petaloid shape to suit use with carbonated beverages as its contents, but the shape of the bottom portion 5 may be other shapes suitable for use with non-carbonated beverages, and can be changed as appropriate depending on the application.

[0015] Here, the height direction refers to the direction perpendicular to the horizontal plane when the container 1 is placed upright on the horizontal plane with the mouth portion 2 facing upward, and the up-down, left-right, and vertical-horizontal directions of the container 1 in this state (the state shown in FIG. 2) are defined.

[0016] In the container 1 formed 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 outer surface of the body 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 is laminated so as to cover the entire circumference of the neck portion 2c on the lower end side of the mouth portion 2 and reach directly below the neck ring 2b.

[0017] Next, a method for manufacturing a synthetic resin container according to the present 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 includes a body mold 104 for molding the shoulder portion 3 and the body portion 4, and a bottom mold 105 for molding the bottom portion 5. The body 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 cut along a plane including the parting surface of the body mold 104.

[0018] FIG. 4 shows an example of a preform 10 blow molded into the container 1 described above. The preform 10 includes a preform body 10a and a coating material layer 60 laminated on the outer peripheral surface side of the preform body 10a so as to be peelable.

[0019] The preform body 10a is formed into a bottomed cylindrical shape including a mouth formation region 20 that becomes the mouth portion 2 of the container body 1a while generally maintaining its appearance when blow molding as described later, and a stretching region 30 that is stretched and formed into the shoulder portion 3, the body portion 4, and the bottom portion 5 of the container body 1a. Threads 2a and a neck ring 2b, which are indicated by the same reference numerals as those attached to the container 1, are provided in the mouth formation region 20 of the preform body 10a, and the portion below the neck ring 2b in the mouth formation region 20 becomes the neck portion 2c of the container body 1a.

[0020] Here, Figure 4 is a longitudinal cross-sectional view of the preform 10, in which the thickness of the preform body 10a and the covering layer 60 appearing in the cross-section are exaggerated. Furthermore, the top, bottom, left, right, and vertical directions of the preform 10 shall be defined as shown in Figure 4, with the mouth-forming region 20 facing upwards.

[0021] Furthermore, the coating layer 60 laminated onto the preform body 10a can be laminated such that its end covers the lower end of the mouth-forming region 20. In the illustrated example, the entire stretched region 30 is covered with the coating layer 60, and the end of the coating layer 60 is laminated so that it covers the entire circumference of the lower part of the neck ring 2b of the mouth-forming region 20 (the part that becomes the neck lower part 2c of the container body 1a) and reaches directly below the neck ring 2b.

[0022] Such a preform 10 can be manufactured by an injection molding method, sometimes called a double mold, as follows.

[0023] First, the core mold 400, which forms the inner and upper end surfaces of the preform body 10a, the upper mold 401, which forms the upper outer surface of the preform body 10a including the upper and circumferential end surfaces of the neck ring 2b, and the first lower mold 402a, which forms the lower outer surface of the preform body 10a from the lower surface of the neck ring 2b to the bottom, are clamped together, and the resin material that will form the preform body 10a is injected (see Figure 5). This injection-moldes the preform body 10a, which is formed into a bottomed cylindrical shape including the mouth-forming region 20 and the stretched region 30 (first injection process).

[0024] Next, instead of the first lower mold 402a, a second lower mold 402b is used, which is configured to create a gap between it and the molded preform body 10a for forming the covering layer 60. After this, the mold is clamped again and the resin material for forming the covering layer 60 is injected (see Figure 6). This injection-moldes a covering layer 60 that is peelably laminated to the outer surface of the preform body 10a and whose end covers the lower end of the mouth-forming region 20 (the lower part of the neck ring 2b) (secondary injection step).

[0025] In addition, the first and second lower molds 402a and 402b are usually equipped with gates that serve as injection ports for the resin material at a position corresponding to the bottom side of the preform 10, but the gates are not shown in the examples shown in Figures 5 and 6.

[0026] As the resin material for forming the preform body 10a (i.e., the resin material for forming the container body 1a), considering the recyclability required for the container 1, an ethylene terephthalate-based thermoplastic polyester such as polyethylene terephthalate can be preferably used.

[0027] As the resin material forming the coating layer 60 (i.e., the resin material forming the coating layer 6), it is preferable to use a thermoplastic resin that is incompatible with the resin material forming the preform body 10a, from the viewpoint that the coating layer 60 (coating layer 6) can be peelably laminated onto the preform body 10a (container body 1a). For example, when an ethylene terephthalate-based thermoplastic polyester is used as the resin material forming the preform body 10a, it is particularly preferable to use a polyolefin-based resin such as polypropylene or polyethylene as the resin material forming the coating layer 60. However, if gas barrier properties are required for the container 1, a thermoplastic resin with gas barrier properties such as an ethylene-vinyl alcohol copolymer or polymetaxylylene adipamide (MXD6) can also be used as the resin material forming the coating layer 60. Pigments or colorants can be added to the resin material forming the coating layer 60 to color it to a desired hue and thereby impart light-shielding properties. To enhance the decorative effect, multiple pigments or colorants can be mixed and added to create a marble pattern. The resin material forming the coating layer 60 can be modified as needed, without being limited by the recyclability requirements of the container 1, and various additives can be added as necessary.

[0028] The preform 10 produced in this manner is softened by heating to a state where it can be blow-molded, and then set in the mold 100 as shown by the dashed line in Figure 3. It is stretched axially (longitudinal direction) by a stretching rod (not shown) as needed, and stretched axially and circumferentially (lateral direction) by blow air blown into the preform 10.

[0029] When heating the preform 10, it is preferable to appropriately adjust the heating temperature from both the inside and outside by, for example, heating the preform 10 from the coating layer 60 side using an infrared heater, and also heating the inner surface of the preform body 10a by inserting a rod-shaped high-frequency induction heating element, which is heated by high-frequency induction heating, into the preform 10.

[0030] In this way, by blow molding the preform 10, the mouth-forming region 20 of the preform body 10a is not stretched except for the connection part with the stretched region 30 at its lower end, and its appearance is generally maintained, becoming the mouth 2 of the container body 1a. Then, the stretched region 30 is stretched, and the shape of the cavity surface 101 of the mold 100 is transferred, forming the shoulder 3, body 4 and bottom 5 of the container body 1a. At the same time, the coating layer 60 laminated on the preform body 10a is molded integrally with the preform body 10a, becoming the coating layer 6 laminated on the container body 1a.

[0031] As described above, the container 1 manufactured by blow molding the preform 10 is usually transported to the filling process, filled and sealed with contents, then boxed and loaded onto a truck or other cargo bed for shipment. Therefore, the container 1 is required to have a product design that takes into account the effects of vibration during transportation. For example, if adjacent containers 1 rub against each other due to vibration during transportation while boxed, and the frictional resistance of the coating layers 6 that come into contact with each other is high, making them difficult to slide, then the surface of the coating layer 6 is prone to wear and tear, which may lead to a defective appearance and is therefore undesirable. Furthermore, in the transport and filling processes after the manufacture of container 1, container 1 may be slid along the line for transport. If the coating layer 6 makes container 1 less slippery, there is a risk that container 1 may tip over in the middle of the transport line, causing disruptions to transport.

[0032] In this embodiment, the surface of the coating layer 6 is roughened, and the coefficient of friction of the roughened surface is adjusted to be less than 1.0, thereby effectively avoiding such problems. The coefficient of friction of the surface of the coating layer 6 refers to the static friction coefficient μs between the coating layers 6, measured in accordance with JIS K 7125:1999 "Test Method for Coefficient of Friction".

[0033] Furthermore, in adjusting the coefficient of friction of the surface of the coating layer 6 by roughening its surface, the inventors investigated the correlation between the coefficient of friction of the surface of the coating layer 6 and the surface roughness parameters. They found that while the correlation with the arithmetic mean height Ra, which is an indicator of the height difference of the irregularities, was low, the correlation with the reciprocal of the arithmetic mean height Ra, 1 / Ra, tended to be somewhat high, and a partial correlation was observed with the skewness Rsk, which is an indicator of the degree of unevenness. Therefore, in addition to the arithmetic mean height Ra, skewness Rsk, which is an indicator of the degree of unevenness, was introduced as a parameter of surface roughness. For example, based on the example described later, a multiple regression analysis was performed with the reciprocal of the arithmetic mean height Ra, 1 / Ra, and skewness Rsk as explanatory variables and the coefficient of friction of the surface of the coating layer 6 (static friction coefficient μs) as the dependent variable. The following regression equation was derived, and a high correlation with an R value of +0.86 was found. Regression equation: μs = 0.035 / Ra + 0.097 × Rsk + 0.2

[0034] Since this 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 in the case of low-density polyethylene, such that the arithmetic mean height Ra is large and the skewness Rsk is small, within the range that satisfies 0.035 / Ra + 0.097 × Rsk + 0.2 < 1.0. Furthermore, the correlations shown in the regression equation above tend to be similar 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, in order to adjust the coefficient of friction of the roughened surface of the coating layer 6 to be less than 1.0, 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.

[0035] In order to roughen the surface of the coating layer 6, it is preferable to apply a roughening treatment to the cavity surface 101 of the mold 100 that forms the stretched stretched region 30 when blow molding the preform 10, as described above, so that the roughened cavity surface 101 is transferred to the surface of the coating layer 6 which is formed in close contact with the cavity surface 101.

[0036] Furthermore, the mold 100 is usually formed using hard materials such as stainless steel or aluminum alloy. To roughen the cavity surface 101 of such a mold 100, it can be roughened by blasting, for example, by shot blasting using abrasive materials such as glass beads, glass powder, alumina, or carborundum, or by laser blasting using laser irradiation. When roughening by shot blasting, the particle size of the abrasive material and the blasting pressure can be appropriately adjusted so that the arithmetic mean height Ra and skewness Rsk of the roughened surface transferred to the surface of the coating layer 6 are desired values. However, laser blasting is preferable because it allows for easier adjustment of the arithmetic mean height Ra and skewness Rsk of the roughened surface transferred to the surface of the coating layer 6.

[0037] Here, if the skewness Rsk is too small or too large, processing when roughening the cavity surface 101 tends to become difficult. If the arithmetic mean height Ra is too small, mold release defects tend to occur easily, and if the arithmetic mean height Ra is too large, the haze of the coating layer 6 tends to increase. Taking these factors into consideration, it is preferable to adjust the arithmetic mean height Ra and skewness Rsk of the rough surface transferred to the surface of the coating layer 6 to fall within the aforementioned ranges.

[0038] Furthermore, when roughening the surface of the coating layer 6, it is not limited to roughening the entire surface of the coating layer 6. For example, in order to avoid the aforementioned problems, at least a portion of the surface of the coating layer 6 may be roughened in accordance with any part of the container 1 where it is necessary to reduce the frictional resistance of the coating layer 6, such as the parts where adjacent containers 1 come into contact with each other when packed in a box, the sliding surface of the bottom 5 when sliding along a conveyor line, or the parts that come into contact with the conveyor guide when sliding along a conveyor line. [Examples]

[0039] The present invention will be described in more detail below with reference to specific examples.

[0040] [Example 1] Polyethylene terephthalate was used as the resin material to form the preform body 10a, and polyethylene (low-density polyethylene) was used as the resin material to form the coating layer 60, and the preform 10 shown in Figure 4 was manufactured by double molding. Then, the preform 10 was softened by heating to a state where it could be blow molded, and then set in the mold 100 and blow molded to produce the number of containers 1 shown in Figures 1 and 2 required for evaluation.

[0041] The cavity surface 101 of the mold 100 was roughened by shot blasting using glass beads (Potters Barotini: J70 GB705K) as the abrasive material. The blasting pressure was 0.3 MPa. The roughened cavity surface 101 was transferred, and the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument. The arithmetic mean height Ra was 1.8 and the skewness Rsk was -0.33.

[0042] Furthermore, test specimens were cut from the coating layer 6 of two containers 1, which were arbitrarily selected from the manufactured containers 1. Using these test specimens, the static friction coefficient μs between the coating layers 6 was measured in accordance with JIS K 7125:1999 "Test Method for Friction Coefficient," and the value was 0.18.

[0043] <Vibration Test> Twelve containers were randomly selected from the manufactured containers, filled with their contents, and sealed. These were then packed into a carton containing 12 (3x4) containers. This carton was then fixed to the vibration table of a vibration testing machine, and a random vibration test was conducted in accordance with JIS Z 0232:2020 "Packaged goods - Vibration test methods". The test conditions were: vibration direction: up and down (vertical), average acceleration: 5.8 m / s². 2 The vibration frequency was set to 10 Hz, and the test duration to 90 minutes.

[0044] <Rating> After the test was completed, each of the 12 containers removed from the carton was visually inspected for the presence or absence of powdering scratches and evaluated according to the following criteria. ◎: No problems with the exterior. ○: Minor powdery scratches that are difficult to judge by visual inspection. ×: Large, clearly visible powdery scratches The evaluation results are shown in Table 1.

[0045] [Table 1]

[0046] [Example 2] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that glass beads (manufactured by Potters Barotini: J80 GB704K) were used as a projectile to roughen the entire surface of the cavity 101 by shot blasting. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 1.6 and the skewness Rsk was -0.18. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.23.

[0047] [Example 3] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that glass beads (manufactured by Potters Barotini: J100 GB703K) were used as a projectile to roughen the entire surface of the cavity 101 by shot blasting. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 1.2 and the skewness Rsk was -0.12. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.22.

[0048] [Example 4] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that glass beads (Potters Barotini: J320 GB732) were used as a projectile to roughen the entire cavity surface 101 by shot blasting. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 0.9 and the skewness Rsk was -0.25. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.21.

[0049] [Example 5] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that glass beads (Potters Barotini: J400 GB731) were used as a projectile to roughen the entire cavity surface 101 by shot blasting. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 0.4 and the skewness Rsk was -0.13. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.27.

[0050] [Example 6] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Showa Denko Corporation: Morundum® F16) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 10.7 and the skewness Rsk was 0.16. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.22.

[0051] [Example 7] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Showa Denko Corporation: Morundum® F24) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 7.5 and the skewness Rsk was -0.02. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.20.

[0052] [Example 8] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Showa Denko Corporation: Morundum® F36) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 6.2 and the skewness Rsk was -0.13. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.20.

[0053] [Example 9] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using alumina (Showa Denko Corporation: Morundum® F60) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 3.4 and the skewness Rsk was 0.03. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.23.

[0054] [Example 10] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using carborundum (Showa Denko Corporation: Densik® C F46) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 4.8 and the skewness Rsk was 0.07. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.20.

[0055] [Example 11] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using carborundum (Showa Denko Corporation: Densik® C F100) as the abrasive material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 1.8 and the skewness Rsk was -0.09. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.21.

[0056] [Example 12] Container 1 was manufactured and evaluated in the same manner as in Example 1, except that the entire cavity surface 101 was roughened by shot blasting using glass powder (Potters Barotini: GP250A) as the projection material. In this embodiment, when the surface roughness of the roughened coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was 3.7 and the skewness Rsk was -0.08. Furthermore, the static friction coefficient μs between the coating layers 6 was 0.19.

[0057] [Comparative Example 1] Except for the cavity surface 101 being finished to a mirror surface without roughening treatment, container 1 was manufactured and evaluated in the same manner as in Example 1. In this comparative example, when the surface roughness of the coating layer 6 was measured using a surface roughness measuring instrument, the arithmetic mean height Ra was less than 0.1 and the skewness Rsk was -0.96. Furthermore, the static friction coefficient μs between the coating layers 6 was 1.00.

[0058] 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 embodiments described above, and various modifications can be made within the scope of the present invention. [Explanation of Symbols]

[0059] 1 container 1a Container body 2 Mouth 3 Shoulder 4 Torso 5 Bottom 6 Covering layer

Claims

1. A synthetic resin container comprising a container body formed in a predetermined container shape including a mouth, shoulders, body, and bottom, and a coating layer peelably laminated on the outer circumferential surface of the container body, At least a portion of the surface of the coating layer is roughened, and the static friction coefficient of the roughened surfaces of the coating layers, measured in accordance with JIS K 7125:1999, is less than 1.

0. 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 A synthetic resin container characterized by the following relationship:

2. The synthetic resin container according to claim 1, wherein the arithmetic mean height Ra of the roughened surface of the coating layer is 0.1 or more, and the skewness Rsk is 0.2 or less.

3. The synthetic resin container according to claim 1, wherein the arithmetic mean height Ra of the roughened surface of the coating layer is 1.8 to 10 and the skewness Rsk is -1.0 to 0.

4. The synthetic resin container according to any one of claims 1 to 3, wherein the coating layer is made of low-density polyethylene.

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