Synthetic resin containers

Abstract

To provide a synthetic resin container having a design feature.SOLUTION: There is provided a synthetic resin container 1 including: a container body 1a molded into a predetermined container shape including a mouth portion 2, a body portion 3, and a bottom portion 4; and a coating layer 5 provided on a surface of the container body 1a so as to be peelable from the container body 1a. At least a part of the coating layer 5 contains a thermosensitive colorant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a synthetic resin container, and more particularly to a synthetic resin container having a coating layer on the surface of the container body. [Background technology]

[0002] BACKGROUND ART Conventionally, synthetic resin containers have been used in a wide range of fields as containers for various beverages, seasonings, and the like, and are obtained by forming a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate, and then molding this preform into a bottle by biaxial stretch blow molding or the like.

[0003] This type of container is filled and sealed with the contents, and is usually provided on the market with a label attached that has printed thereon the product name, contents indication, and even decorative designs, etc. Known examples of such labels include shrink labels that are attached by heat shrinkage and seal labels that are attached with an adhesive (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-230579 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, as the use of this type of container has become more common in a wide range of fields, there has been a growing demand for products with distinctive designs to differentiate them from other products.

[0006] Therefore, the present inventors have conducted extensive research to provide a synthetic resin container with distinctive design features, and as a result have completed the present invention. [Means for solving the problem]

[0007] The synthetic resin container according to the present invention is a synthetic resin container comprising a container body formed into a predetermined container shape including a mouth, a body, and a bottom, and a coating layer laminated on the surface of the container body so as to be peelable from the container body, and the container body has a band-shaped recess that is recessed inward of the container with a predetermined width and extends in a band-like shape, and a , the peripheral surface of the adjacent body portion and the bottom surface of the band-shaped recess The coating layer has a linear thin-walled portion that is thinner than the periphery along the step portions formed on both ends of the band-shaped recess in the width direction, and the edges of the recess that rise from the bottom surface of the band-shaped recess and connect to the bottom surface of the band-shaped recess are formed. To the department Location On the surface a thick portion in which the thickness of the coating layer is thicker than the surrounding area is formed on the bottom surface of the recessed portion, and the thick portion is connected to the thick portion and On the side Location On the surface A thin portion is formed in the coating layer, where the thickness of the coating layer is thinner than the surrounding area, and at least a part of the coating layer contains a thermochromic colorant. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a synthetic resin container having a design feature in which the color applied to the surface of the container changes with temperature. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view showing an outline of a synthetic resin container according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the AA end of FIG. [Figure 3] FIG. 2 is a BB end view of FIG. [Figure 4] FIG. 2 is a longitudinal cross-sectional view showing an example of a preform. [Figure 5] 1 is an explanatory diagram showing an outline of an example of a blow molding mold used in a method for producing a synthetic resin container according to an embodiment of the present invention. [Figure 6]FIG. 6 is a perspective view of a main part of the blow molding die shown in FIG. 5. [Figure 7] FIG. 7 is a CC end view of FIG. 6. [Figure 8] 6 is an explanatory view showing a process in which a band-shaped recess is formed by a protrusion formed on the cavity surface of the blow molding die shown in FIG. 5. FIG. [Figure 9] 6 is an explanatory view showing a process in which a band-shaped recess is formed by a protrusion formed on the cavity surface of the blow molding die shown in FIG. 5. FIG. [Figure 10] FIG. 7 is a DD end view of FIG. 6. [Figure 11] 6 is an explanatory view showing a process in which a depression is formed by a protrusion formed on the cavity surface of the blow molding die shown in FIG. 5. FIG. [Figure 12] 6 is an explanatory view showing a process in which a depression is formed by a protrusion formed on the cavity surface of the blow molding die shown in FIG. 5. FIG. [Figure 13] 6 is an explanatory view showing a process in which a depression is formed by a protrusion formed on the cavity surface of the blow molding die shown in FIG. 5. FIG. [Figure 14] 1 is a graph showing the total light transmittance of a synthetic resin container according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0011] [Synthetic resin container] FIG. 1 is a front view showing an outline of a synthetic resin container according to this embodiment, FIG. 2 is an AA end view of FIG. 1, and FIG. 3 is a BB end view of FIG.

[0012] The container 1 shown in these figures comprises a container body 1a formed into a predetermined container shape including a mouth 2, a body 3, and a bottom 4, and a coating layer 5 provided on the surface of the container body 1a so as to be peelable from the container body 1a. In the example shown, the container 1 (container body 1a) has a container shape including a body 3 formed into a roughly cylindrical shape with the diameter of the upper portion in the height direction narrowing toward the mouth 2, and a bottom 4 formed into a so-called petaloid shape, but the shape of the container 1 is not limited to this.

[0013] 1 shows a cross section of a portion cut away from the mouth 2 toward the upper end of the body 3, and the thicknesses of the container body 1a and the coating layer 5 that appear in the cross section are exaggerated for schematic depiction. In the other drawings, the thicknesses of the container body 1a, the coating layer 5, and the like that appear in the cross section are also exaggerated as appropriate. Furthermore, 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 2 facing upward, and defines the up / down, left / right and length / width directions of the container 1 in this state (the state shown in Figure 1).

[0014] The mouth 2 is a cylindrical portion that serves as a spout for pouring the contents. A screw thread 21 is provided on the side of the open end of the mouth 2 for attaching a lid (not shown). Further, an annular neck ring 22 is provided on the lower end side of the mouth portion 2 so as to protrude outward in the circumferential direction.

[0015] In the illustrated example, the coating layer 5 covers the entire peripheral surface of the body 3 from the bottom surface of the bottom 4, and is laminated on the outer peripheral surface of the container body 1a so that its end reaches the peripheral edge of the neck ring 22 while covering the underside of the neck ring 22 provided on the lower end side of the mouth 2.

[0016] According to this embodiment, the coating layer 5 covers the entire container 1 except for a portion of the mouth side, which is preferable because it allows the entire container 1 to be given a color design and the appearance of the container 1 to be easily changed without being restricted by the recyclability required of the container body 1a.

[0017] At least a portion of the coating layer 5 contains a thermochromic colorant, so that the color can change according to temperature. According to such a container 1, it is possible to provide a synthetic resin container having a design feature in which the appearance of the container 1 changes with temperature changes. Furthermore, since the temperature of container 1 can be determined visually, consumers can purchase products at the desired temperature without touching the product, for example, when products using container 1 are displayed in a store.

[0018] Furthermore, when the coating layer 5 is laminated on the outer peripheral surface of the container body 1a excluding a portion on the mouth portion 2 side as in this embodiment, the container body 1a and the coating layer 5 containing the thermochromic colorant are more closely adhered than when the coating layer 5 is provided on the surface of the container body 1a like a shrink label or seal label applied to conventional containers, and the color change of the thermochromic colorant is more susceptible to temperature changes inside the container 1, making this more preferable when the purpose is to visually check the temperature inside the container 1.

[0019] Examples of thermochromic colorants that can be used include Chromicolor PE Concentrate BW (manufactured by Matsui Pigment Chemical Industry Co., Ltd.) and Chromicolor PP Concentrate BW (manufactured by Matsui Pigment Chemical Industry Co., Ltd.). Chromicolor PE Concentrate BW is a masterbatch in which a thermochromic dye is blended at a high concentration in a polyethylene resin, and Chromicolor PP Concentrate BW is a masterbatch in which a thermochromic dye is blended at a high concentration in a polypropylene resin. By blending these thermochromic colorants into the resin material that forms the coating layer 5 and then injection molding the mixture, a thermochromic molded product can be obtained.

[0020] The thermochromic colorant can be selected based on the desired temperature change range and color. For example, Chromicolor PE Concentrate BW Grade #15 G-0 (Fast Blue) (manufactured by Matsui Pigment Chemical Industry Co., Ltd.) changes color as the temperature changes from high to low, with the color change starting at 19°C and completing at 11°C. In this case, the color is white at temperatures above 19°C, gradually changes to blue when the temperature drops below 19°C, and is completely blue when cooled to 11°C. This color change is reversible. It is preferable that the light transmittance at temperatures lower than the end point of the temperature change range is reduced by 10% or more in the wavelength range of 380 to 780 nm compared to the light transmittance at temperatures higher than the start point of the temperature change range. This makes it possible to clearly recognize the color change caused by the thermochromic colorant in the visible light wavelength range. For example, when Chromicolor PE Conc BW Grade #15 G-0 (Fast Blue) is used, the color change when the temperature drops from room temperature is clearly recognized, making it easy to confirm whether the temperature inside the container 1 has cooled.

[0021] The thermochromic colorant may be mixed with a colorant normally used to color the container label or coating layer 5. For example, mixing the aforementioned Chromicolor PE Concentrated BW Grade #15 G-0 with a yellow colorant will produce a light yellow color before discoloration and a green color after discoloration due to temperature change. Furthermore, thermochromic colorants with multiple different color-developing temperature ranges may be combined to cause the container 1 to undergo multiple color changes due to temperature changes.

[0022] The coating layer 5 of the container 1 in this embodiment is releasably laminated to the container body 1a so that it can be peeled off from the used container 1 and disposed of separately after the contents have been consumed, and the coating layer 5 can be provided with a tear guide portion to make it easier to tear the coating layer 5 when peeling it off from the container 1. In the example shown in the figure, the coating layer 5 includes a thin-walled portion that is thinner than the surrounding area, and a tear guide portion is provided in which this thin-walled portion extends linearly in a predetermined direction.

[0023] The specific form of the tear guide portion is not particularly limited, but in the example shown, the body 3 of the container body 1a is provided with a band-shaped recess 6 that is recessed inward into the container and extends in a band-like shape, and a recess 7 on one end side of the band-shaped recess 6 that is lower than the surrounding area, and the coating layer 5 is formed with a linear thin-walled portion 5c corresponding to the band-shaped recess 6, and a thick-walled portion 5a and a thin-walled portion 5b connected to the thick-walled portion 5a corresponding to the recess 7, which serve as starting points for tearing the coating layer 5.

[0024] More specifically, a band-shaped recess 6 having a predetermined width extending inwardly of the container and in a band shape is provided in the body 3 of the container body 1a, from the upper end (mouth 2 side) to the lower end (bottom 4 side) of the body 3 along the height direction. Steps 6b are formed on both widthwise edges of the band-shaped recess 6, protruding from the bottom surface 6a of the band-shaped recess 6 and continuing to the circumferential surface of the body 3 (see FIG. 2). A recessed portion 7 that is lower than the surrounding area is provided adjacent to one end of the band-shaped recess 6. The bottom surface 7a of the recessed portion 7 is recessed further inward into the container than the circumferential surface of the adjacent body portion 3 and the bottom surface 6a of the band-shaped recess 6, and is bordered by an edge portion 7b that rises from the bottom surface 7a of the recessed portion 7 and continues to both the circumferential surface of the adjacent body portion 3 and the bottom surface 6a of the band-shaped recess 6 (see Figure 3). The bottom surface 7a of the recessed portion 7 may be a surface that is parallel or inclined along the axial direction, and may be a flat surface or a curved surface.

[0025] Meanwhile, the coating layer 5 laminated on the outer peripheral surface side of the container body 1a has a thick portion 5a that is thicker than the surrounding area, protruding from the bottom surface 7a of the recessed portion 7 and located on the edge portion 7b that continues to the bottom surface 6a of the band-shaped recess 6. At the same time, a thin portion 5b that is thinner than the surrounding area and connected to the thick portion 5a is formed in a portion that is located on the bottom surface 7a side of the recessed portion 7 (see FIG. 3). Additionally, the coating layer 5 is formed with linear thin portions 5c that are linearly thinner than the surrounding area along the step portions 6b formed on both end sides of the band-shaped recess 6 (see FIG. 2).

[0026] By doing this, when disposing of the container 1 after the contents have been consumed, the container body 1a and the coating layer 5 can be easily separated by hooking the thick portion 5a formed on the edge 7b of the recess 7 with the fingernail from the bottom surface 7a side of the recess 7, thereby breaking the thin portion 5b and separating the thick portion 5a from the thin portion 5b side, and then picking up the separated thick portion 5a with the fingers and tearing the coating layer 5 along the linear thin portion 5c formed as a tear guide portion.

[0027] [Manufacturing method for synthetic resin containers] The container 1 according to this embodiment can be manufactured by molding a preform 10 having a cylindrical preform body 10a with a bottom and an open end, in which a mouth 20 is formed on one end of a cylindrical body 30 and a hemispherical bottom 40 is formed on the other end, and a coating material layer 50 laminated on the outer peripheral surface of the preform body 10a, into a predetermined container shape by biaxial stretch blow molding or the like.

[0028] An example of the preform 10 is shown in Fig. 4. In the figure, the thicknesses of the preform body 10a and the coating material layer 50 that appear in the cross section are exaggerated for a schematic depiction. To manufacture a container 1 having a coating layer 5 laminated thereon in the manner described above, a preform 10 is used in which a coating layer 50 is laminated on the outer peripheral surface of the preform body 10a so that the coating layer 50 covers the entire outer peripheral surface of the preform body 10a from the bottom 40 to just below the mouth 20, and the end of the coating layer 50 covers the underside of the neck ring 22 provided on the lower end side of the mouth 20 and reaches the peripheral edge of the neck ring 22.

[0029] The preform 10 having the coating material layer 50 laminated on the outer peripheral surface side of the preform body 10a is preferably molded by an injection molding method called double molding as follows. The core mold that molds the inner peripheral surface of the preform 10 (preform body 10a) and the upper end surface of its mouth portion 20, the mouth mold that molds the outer surface of the mouth portion 20 including the upper surface and peripheral end surface of the neck ring 22, and the first body primary mold that molds the outer surface of the preform body 10a from the lower surface of the neck ring 22 to the bottom 40 are clamped together to injection mold the preform body 10a. Next, in place of the first body primary mold, a second body mold that is configured to form a gap between the molded preform body 10a and the second body mold so that a gap for molding the coating material layer 50 is formed between the molded preform body 10a and the second body mold, and the coating material layer 50 is injection molded onto the outer peripheral surface of the preform body 10a, thereby molding the preform 10 having the coating material layer 50 laminated on the outer peripheral surface of the preform body 10a.

[0030] To incorporate a thermochromic colorant into the coating layer 5, the desired thermochromic colorant can be mixed into the resin material forming the coating layer 50. The amount of thermochromic colorant to be incorporated can be selected within a range that does not impair the physical properties of the molded product, and when the aforementioned Chromicolor PE Conc BW Grade #15 G-0 is incorporated, the amount to be incorporated is preferably 5 to 10% of the base resin material.

[0031] When a thermochromic colorant is contained in the coating material layer 50 and the coating layer 5 is laminated on the container body 1a to form a container 1, the thermochromic coloring properties of the thermochromic colorant contained in the coating layer 5 are more susceptible to temperature changes inside the container 1 than when the thermochromic colorant is applied to the surface of the coating layer 5, which is preferable when the purpose is to visually check the temperature of the contents of the container 1.

[0032] The produced preform 10 is softened by heating to a state where it can be blow-molded, and then set in a blow mold 100. The portion from just below the neck ring 22 to the bottom 40 is stretched in the axial direction (longitudinal direction) by a stretching rod as necessary, and is also stretched in the axial and circumferential directions (lateral directions) by a high-pressure fluid blow. The cavity shape of the blow mold 100 is then transferred to the stretched portion, thereby forming a container 1 having a predetermined container shape. At this time, the stretched preform body 10a forms the container body 1a, and the coating material layer 50 laminated on the preform body 10a is molded integrally with the preform body 10a to form the coating layer 5 laminated on the container body 1a.

[0033] Fig. 5 is an explanatory diagram showing an outline of an example of a blow molding die used in this embodiment. In Fig. 5, the preform 10 set in the blow molding die 100 is shown by a dashed line.

[0034] The blow molding die 100 is intended to mold the container 1 shown in Fig. 1 and includes a body die 103 for molding the body 3 of the container 1 and a bottom die 104 for molding the bottom 4 of the container 1. The body die 103 is made up of a pair of split dies configured to be able to open and close, and Fig. 5 shows a simplified cross section of the blow molding die 100 taken along a plane including the parting surface of the body die 103.

[0035] In the illustrated example, a protrusion 106 that forms a band-shaped recess 6 in the container body 1a of the container 1 is provided on the cavity surface of the body mold 103, rising steeply so as to form an edge 106a along both widthwise edges of the protrusion 106 (see FIGS. 6 and 7). The protrusion 106 protrudes a predetermined width and extends from the upper end to the lower end of the body mold 103, and a protrusion 107 that forms a recess 7 in the container body 1a of the container 1 is provided on the lower end of the body mold 103, connected to one end of the protrusion 106. The protrusion 107 protrudes higher than the surrounding area, i.e., protrudes higher than the adjacent cavity surface and the upper surface of the protrusion 106, and is provided steeply so as to form an edge 107a on the periphery (see FIGS. 6 and 10). 6 shows an oblique view of the main part of the cavity surface of the body mold 103, including part of the protrusion 106 and the protrusion 107, FIG. 7 is a CC end view of FIG. 6, and FIG. 10 is a DD end view of FIG. 6.

[0036] As described above, when the preform 10 is set in such a blow molding mold 100, the preform body 10a is heated to a temperature below the melting point and above the glass transition point of the resin material forming the preform body 10a, thereby softening the preform body 10a so that it can be stretched, and the coating material layer 50 is heated to a temperature close to the melting point of the resin material forming the coating material layer 50 (for example, [melting point -30] to [melting point +30] °C), thereby keeping the coating material layer 50 in a highly fluid molten or semi-molten state, and thereby a container 1 having the tear guide portion described above can be manufactured. The process of blow-molding the preform 10 thus heated into a container 1 having a tear guide portion in the covering layer 5 will be described in detail below.

[0037] In order to heat the preform 10 so that the preform body 10a and the coating material layer 50 are each heated as described above, the preform 10 may be heated from the outside using an infrared heater or the like, and the preform 10 may also be heated from the inside by inserting a rod-shaped high-frequency induction heating element that has been heated by high-frequency induction heating into the preform 10, thereby appropriately adjusting the heating temperatures from inside and outside.

[0038] When blow molding of the preform 10 begins in the blow molding mold 100, the stretched portion comes into contact with the cavity surface, and a band-shaped recess 6 is formed in the preform body 10a (body portion 3 of the container body 1a) by the protrusion portion 106, and a depression portion 7 is formed by the protrusion portion 107.

[0039] At this time, the band-shaped recess 6 formed in the preform body 10a is not formed exactly in the shape of the protrusion 106, which is provided abruptly so that edge portions 106a are formed along both end edges. As shown in Figures 8 and 9, the preform body 10a is stretched so that both end sides of the part that contacts the upper surface of the protrusion 106 via the coating layer 50 are curved relative to the steps on both end edge sides of the protrusion 106. As a result, the band-shaped recess 6 is shaped so that step portions 6b are formed at both end edges that rise from the bottom surface 6a of the band-shaped recess 6 and continue to the circumferential surface of the body portion 3 (see Figure 2).

[0040] In contrast, the coating material layer 50 is in a molten or semi-molten state with high fluidity. Therefore, as the preform body 10a is stretched so as to curve relative to the steps on both end edges of the protrusions 106, the coating material layer 50 is pressed against the edge portions 106a formed along both end edges of the protrusions 106, and the portions of the coating material layer 50 that are pressed against the edge portions 106a are pushed aside and flow to fill the gap between the curved stretched portions of the preform body 10a and the steps on both end edges of the protrusions 106. As a result, the coating material layer 50 is shaped roughly to the shape of the protrusions 106 and is formed so as to have a thin linear shape along the edge portions 106a of the protrusions 106 (see FIG. 9).

[0041] As a result, in the container 1 after blow molding, a linear thin-walled portion 5c that is linearly thinner than the surrounding area is formed in the coating layer 5 along the step portion 6b formed on both end edges of the band-shaped recess 6 (see Figure 2).

[0042] In this way, when linear thin portions 5c are formed in the covering layer 5, the thinner and more clearly the linear thin portions 5c are formed, the easier it is to tear the covering layer 5 along the linear thin portions 5c. From this perspective, the shape, dimensions, etc. of the protrusions 106 can be designed appropriately.

[0043] For example, the step h1 of the protrusion portion 106, i.e., in the illustrated example, the difference in height h1 between the upper surface of the protrusion portion 106 and the adjacent cavity surface, and the angle θ1 of the edge portion 106a formed along both end edges of the protrusion portion 106, i.e., the angle θ1 between the upper surface of the protrusion portion 106 and the side surface of the protrusion portion 106 which forms the edge portion 106a together with the upper surface, are appropriately designed from the above perspective. If the linear thin portions 5c can be formed in the coating layer 5 as described above, the edge portions 106a formed along both end edges of the protrusions 106 may be rounded as shown in FIG.

[0044] Similarly, the depression 7 formed in the preform body 10a is not formed exactly in the shape of the protrusion 107, which is provided steeply so that an edge 107a is formed on the periphery. As shown in Figures 11 to 13, when the stretched preform body 10a comes into contact with the upper surface of the protrusion 107 via the coating material layer 50, the part on the periphery side where the edge 107a is formed is stretched so as to curve relative to the step on the periphery side. As a result, the depression 7 is shaped so as to protrude from its bottom surface 7a and be bordered by an edge 7b that is continuous with the periphery of the adjacent trunk portion 3 and the bottom surface 6a of the band-shaped recess 6 (see Figure 3).

[0045] At this time, if there is a step of a certain level or more on the peripheral side where the edge portion 107a of the protrusion 107 is formed, as the preform body 10a stretches so as to curve over the step, the coating material layer 50 sandwiched between the preform body 10a and the upper surface of the protrusion 107 is pressed and flows so as to protrude from the upper surface of the protrusion 107 toward the peripheral side (see FIG. 12). As a result, a material pool is formed between the step and the peripheral side where the edge portion 107a of the protrusion 107 is formed, and the coating material layer 50 sandwiched between the preform body 10a and the upper surface of the protrusion 107 is molded to be thick, while the coating material layer 50 sandwiched between the preform body 10a and the upper surface of the protrusion 107 is molded to be thin (see FIG. 13).

[0046] As a result, in the container 1 after blow molding, a thick portion 5a in which the coating layer 5 is thicker than the surrounding area is formed in the coating layer 5 at a portion located on the edge 7b of the recess 7 that protrudes from the bottom surface 7a of the recess 7, and a thin portion 5b in which the coating layer 5 is thinner than the surrounding area is formed in the coating layer 5 at a portion connected to this thick portion 5a and located on the bottom surface 7a side of the recess 7 (see Figure 3).

[0047] In this way, when forming the thick portion 5a and the thin portion 5b connected to each other in the coating layer 5, the shape, dimensions, etc. of the protrusion 107 can be appropriately designed from the viewpoint of more easily breaking the thin portion 5b and separating the thick portion 5a from the thin portion 5b side, as described above.

[0048] For example, the step h2 on the peripheral side where the edge portion 107a of the protrusion 107 is formed, i.e., in the example shown, the difference in height h2 between the upper surface of the protrusion 107 and the upper surface of the protrusion portion 106, and the angle θ2 of the edge portion 107a formed on the periphery of the protrusion 107, i.e., the angle θ2 between the upper surface of the protrusion 107 and the side surface of the protrusion 107 which forms the edge portion 107a together with the upper surface, are appropriately designed from the above perspective. Furthermore, if the thick-walled portion 5a and the thin-walled portion 5b can be formed in the coating layer 5 in a connected manner as described above, the edge portion 107a formed on the periphery of the protrusion 107 may be rounded as shown in Figure 10.

[0049] In addition, in this embodiment, the protrusion 107 is configured so that, on the side connected to the protrusion 106, the side surface that forms the edge portion 107a together with the upper surface of the protrusion 107 is concavely curved toward both end edges of the protrusion 106. When the protrusion 107 is formed in such a shape, the coating material layer 50 that protrudes from the upper surface of the protrusion 107 toward the periphery due to pressure between the preform body 10a and the upper surface of the protrusion 107 is gathered toward the center of the side surface, which is preferable because it makes the thick-walled portion 5a formed in the coating layer 5 thicker and makes it easier to separate from the thin-walled portion 5b side.

[0050] In this way, when preform 10 is blow molded, mouth portion 20 of preform 10 including neck ring 22 is not stretched by blow molding and becomes mouth portion 2 of container 1 as is. Therefore, if preform 10 shown in Fig. 4 is used, the distal end side of coating material layer 50 covering the lower surface of neck ring 22 also becomes the distal end side of coating layer 5 of container 1 as is, so that container 1 having coating layer 5 laminated thereon in the manner described above can be manufactured.

[0051] In this embodiment, any thermoplastic resin that can be blow molded can be used as the resin material for forming the container body 1a (preform body 10a), but in consideration of recyclability, ethylene terephthalate-based thermoplastic polyesters such as polyethylene terephthalate are preferably used.

[0052] As the resin material for forming the coating layer 5 (coating material layer 50), it is preferable to use a thermoplastic resin that is incompatible with the resin material for forming the container body 1a, in order to make it easy to separate the container body 1a and the coating layer 5. For example, when an ethylene terephthalate-based thermoplastic polyester is used as the resin material for forming the container body 1a, the resin material for forming the coating layer 5 may be a polyolefin-based resin such as polyethylene or polypropylene, an ethylene-vinyl alcohol copolymer, or a polyamide-based resin such as polymetaxylylene adipamide (MXD6). Furthermore, when a thermochromic colorant is to be contained in the coating layer 5, it is preferable to appropriately select a resin material that is highly compatible with the thermochromic colorant used. For example, the above-mentioned Chromicolor PE Concentrated BW grade is a masterbatch in which a thermochromic dye is blended at a high concentration in a polyethylene resin, so when this thermochromic colorant is to be contained in the coating layer 5, it is preferable to use polyethylene as the resin material for forming the coating layer 5.

[0053] Here, the molecular structure of a thermochromic colorant generally tends to be destroyed at around 250°C, resulting in a loss of thermochromic properties. When such a thermochromic colorant is mixed with a resin material and injection-molded to form the coating layer 5 (coating layer 50), it is preferable to select a resin material having a melting point of 200°C or lower for forming the coating layer 5. Furthermore, when a preform 10 having a coating layer 50 containing a thermochromic colorant is subjected to blow molding, it is preferable to select a resin material for forming the coating layer 5 and the container body 1a that can be blow-molded at 200°C or lower. By appropriately selecting the resin materials for the coating layer 5 and the container body 1a in this manner, for example, when producing the container 1 as described above, even if the coating layer 50 is injection-molded at a melting temperature of around 200°C and the preform 10 is blow-molded at a mold temperature of approximately 100 to 150°C, the container 1 can be produced without losing the thermochromic properties of the thermochromic colorant contained in the coating layer 5. It goes without saying that depending on the thermochromic colorant used and the manufacturing method of the container 1, the resin material of the coating layer 5 and the container body 1a can be appropriately selected according to the conditions, as long as the thermochromic properties are not lost.

[0054] Furthermore, as mentioned above, when forming a tear guide portion including a thin-walled portion in the coating layer 5, the preform 10 is heated during blow molding to soften the preform body 10a so that it can be stretched, while bringing the coating layer 50 into a molten or semi-molten state. In this way, it is necessary to select the resin materials forming the container body 1a and the coating layer 5 taking into consideration the melting point and glass transition point of these resin materials.

[0055] Furthermore, the resin material forming the coating layer 5 (coating material layer 50) is not limited by the recyclability required of the container body 1a, and various additives such as the aforementioned thermochromic colorants, pigments, and colorants can be added as needed.

[0056] The synthetic resin container 1 according to the present embodiment can be manufactured in this manner, but when manufacturing the container 1, the characteristic that the color of the coating layer 5 changes depending on the temperature can also be utilized, for example, as follows. When it is desired to color the coating layer 5 after molding to a color such as black, which has a high light-blocking rate, and when the container 1 is manufactured by blow molding the coating layer 50 together with the preform body 10a, if the coating layer 50 is subjected to blow molding while colored black, etc., the coating layer 50 will have a high light-blocking rate and the heating efficiency of the preform 10 may be reduced. However, by making the coating layer 50 contain a thermochromic colorant that is adjusted to develop a color with a low light-blocking rate above a specified temperature and to develop a black color below the specified temperature, the heating efficiency of both the preform body 10a and the coating layer 50 during blow molding can be increased, and this can be used to improve blow moldability. Furthermore, the container 1 (preform 10) contains a thermochromic colorant in the coating layer 5 (coating material layer 50) so that the light transmittance of the coating layer 5 (coating material layer 50 of the preform 10) of the container 1 is high at a predetermined temperature, and by ensuring that the light transmittance of the coating layer 5 (coating material layer 50) is high during inspection on the container 1 production line, this can be used to improve the accuracy of the inspection. [Example]

[0057] The present invention will be described in more detail below with reference to specific examples.

[0058] Using the double molding method described above, a preform 10 was molded, which had a preform body 10a made of colorless and transparent polyethylene terephthalate resin and a coating material layer 50 made of colorless and transparent polyethylene mixed with a thermochromic colorant. The thermochromic colorant used was Chromicolor PE Conc BW Grade #15 G-0 (Fast Blue), and the amount of the thermochromic colorant mixed in the coating layer 50 was adjusted to 10% relative to the polyethylene. The preform 10 was molded into the container shape shown in FIG. 1 by biaxial stretch blow molding, to produce a container 1 having a container body 1a and a coating layer 5 on the surface of the container body 1a. A 10 mm × 10 mm sample piece was cut out from the smooth portion near the center of the body 30 of the manufactured container 1, and the total light transmittance of the sample piece was measured using a UV-Vis-NIR spectrophotometer V-770 (manufactured by JASCO Corporation) when it was placed at 20°C (room temperature) and when it was cooled to 10°C with a cooling spray. The results are shown in Figure 14.

[0059] The light transmittance of the sample piece at a temperature of 20°C at a wavelength of 380 nm was 0.07%T, and the light transmittance of the sample piece at a temperature of 10°C was 0.06%T. In addition, the light transmittance of the sample piece at a wavelength of 780 nm at a temperature of 20°C was 35.5%T, and the light transmittance of the sample piece at a temperature of 10°C was 25.5%T. In the container 1 of this embodiment, it was confirmed that the light transmittance at temperatures lower than 11°C, which is the completion point at which the color change is completed, is reduced by 10% or more in the wavelength range of visible light (wavelengths of 380 to 780 nm), compared to the light transmittance at temperatures higher than 19°C, which is the starting point at which the color change begins.

[0060] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0061] For example, the method for manufacturing the container 1 is not limited to the method shown in the embodiment described above, in which the preform 10, in which the coating material layer 50 is laminated on the outer peripheral surface side of the preform main body 10a by two-color molding, is molded into a predetermined container shape by biaxial stretch blow molding or the like. A film may be attached to the outer peripheral surface side of the preform main body to form a preform with a coating material layer, and the preform may be blow molded into the container 1. The preform may be blow molded to form an intermediate, a heat-shrinkable film that will become the coating layer may be attached to the intermediate, and the intermediate may be further blow molded into the container 1.

[0062] Furthermore, in the above-described embodiment, a tear guide portion is provided in the coating layer 5 to make it easier to tear the coating layer 5, but the tear guide portion may be omitted. In this case, for example, an incision may be made in the coating layer 5 near the upper end of the body portion 3 using a blade or the like, and the coating layer 5 may be torn from that incision. Peeling the coating layer 5 in this manner ensures that the distal end of the coating layer 5 can be torn off reliably, and the container body 1a and the coating layer 5 can be easily separated by peeling off the distal end of the coating layer 5 that has been peeled off from the container body 1a and peeling off the remaining portion. [Explanation of symbols]

[0063] 1 container 1a Container body 2 Mouth 3. Torso 4 Bottom 5 Covering layer 10 Preform 10a Preform body 50 coating layer

Claims

1. A synthetic resin container comprising a container body formed into a predetermined container shape including a mouth, a body, and a bottom, and a coating layer laminated on the surface of the container body so as to be peelable from the container body, The container body is provided with a band-shaped recess that is recessed inward of the container by a predetermined width and extends in a band shape, and a recess that is provided at one end side of the band-shaped recess and is lower than the circumferential surface of the adjacent body portion and the bottom surface of the band-shaped recess, The coating layer has linear thin-walled portions formed along step portions formed on both widthwise edges of the band-shaped recess, the linear thin-walled portions being thinner than the surrounding area, and thick-walled portions formed on the surface of the portions located at the edges of the recess that rise from the bottom surface of the recess and connect to the bottom surface of the band-shaped recess, the thick-walled portions being thicker than the surrounding area, and thin-walled portions formed on the surface of the portions connected to the thick-walled portions and located on the bottom surface side of the recess, the thin-walled portions being thinner than the surrounding area, At least a part of the coating layer contains a thermochromic colorant. A synthetic resin container characterized by:

2. 2. The synthetic resin container according to claim 1, wherein the coating layer containing the thermochromic colorant is laminated on the outer surface of the container body except for a portion on the mouth side.

3. The synthetic resin container according to claim 1 or 2, characterized in that the thermochromic colorant has a temperature change range from a change start point, at which a color change begins, to a change completion point, at which the color change is completed, as the temperature changes from high to low, and the light transmittance at a temperature lower than the change completion point is reduced by 10% or more in a wavelength range of 380 to 780 nm, compared to the light transmittance at a temperature higher than the change start point.

4. A method for manufacturing a synthetic resin container according to any one of claims 1 to 3, A preform including a bottomed cylindrical preform body made of a thermoplastic resin and a coating material layer made of a thermoplastic resin containing a thermochromic colorant is molded by a double molding method, The preform is blow molded to form a synthetic resin container having a container body molded into a predetermined container shape and a coating layer containing the thermochromic colorant on the surface of the container body. A method for manufacturing a synthetic resin container.

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