Cap and packaging container

Abstract

To provide a cap hard to produce powder dust when being assembled with a hard container body, and does not require a liner material.SOLUTION: A cap 50 mounted on an opening of a container body 10 by screw fitting contains 70% or more of a base resin having bending elastic modulus of 800 MPa or more, and 30% or less of a sub-resin having bending elastic modulus of 1,000 MPa or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cap that is attached to a container, and also to a packaging container using the cap. [Background technology]

[0002] 2. Description of the Related Art Packaging containers having a plastic container body with a plastic cap attached to an opening thereof are widely used. Efforts are being made to reduce the environmental impact of plastic containers. One such effort is to use plastic made from plant-based raw materials to form the container body and cap.

[0003] Since the container body is filled with the contents, a relatively hard plastic is often used to ensure good shape retention, but some container bodies made of plastic made from plant-based materials are quite hard. Therefore, when the cap is attached with a screw, the cap may be scraped by the container body, generating dust from the cap material.

[0004] In relation to this problem, Patent Document 1 describes a cap having a liner material provided on the inner surface of the top plate of a cap shell consisting of a top plate and a skirt portion, which suppresses the generation of dust. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4947935 Summary of the Invention [Problem to be solved by the invention]

[0006] The cap described in Patent Document 1 is formed of two parts, a cap shell and a liner material, and therefore the manufacturing process is complicated. The inventors have conducted studies into a configuration capable of suppressing the generation of dust without using a liner material, and have completed the present invention.

[0007] An object of the present invention is to provide a cap which is less likely to generate dust when combined with a hard container body and does not require a liner material. [Means for solving the problem]

[0008] A first aspect of the present invention is a cap that is attached to an opening of a container body by screw engagement. The cap contains 70% or more of a base resin having a flexural modulus of 800 megapascals or more, and 30% or less of a sub-resin having a flexural modulus of 1000 megapascals or more.

[0009] A second aspect of the present invention is a packaging container comprising the cap according to the first aspect, and a container body formed of a synthetic resin and having an opening into which the cap can be screwed. Effect of the Invention

[0010] The packaging container according to the present invention can be deformed into a shape suitable for consumption by unfolding, and can ensure a large volume when deformed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a packaging container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the packaging container with a hinged lid open. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described with reference to FIGS. 1 is a perspective view of a packaging container 1 according to this embodiment. The packaging container 1 includes a container body 10 and a cap 50 attached to the container body 10. The shape of the container body 10 in this embodiment is a cylinder with a bottom, but there is no particular limitation, and it may be of another shape as long as it has an opening and can contain the contents.

[0013] Although not shown in Fig. 1, the container body 10 has an opening at the top and a screw on the outer circumferential surface near the opening. The cap 50 is attached to the container body 10 by being screwed onto the screw to cover the opening. The container body 10 may be transparent or opaque. When it is opaque, it may be configured by covering a transparent resin molded body with a shrink film having a print layer.

[0014] The container body 10 is made of a plastic harder than the cap 50. Examples of such plastics include polyethylene terephthalate (PET), polycarbonate (PC), ABS resin, etc. If so-called bio-polyethylene terephthalate (bio-PET), which includes PET made from plant-derived materials, is used as the PET, the environmental impact of the entire packaging container 1 can be reduced.

[0015] The cap 50 has a hinged lid 51 at the top. When the hinged lid 51 is rotated upward, an upper surface 52 having a plurality of holes 52a is exposed as shown in Fig. 2. This allows the contents contained in the container body 10 to be dispensed from the holes 52a during use without removing the cap 50 from the container body 10, and after use, the inside of the container body 10 can be sealed by closing the hinged lid 51 again.

[0016] In the manufacturing process of a package that contains a specified content within the container body 10, a specified amount of content is filled into the container body 10 through the opening of the container body 10, and then a capping device holding the cap 50 with a chuck or the like rotates the cap and screws it into the container body 10 to attach it. In this process, the cap 50 is chucked with a relatively large force and rotated at a relatively high speed, which causes a large friction between the inner surface of the cap 50, on which the threads are formed, and the screw of the container body, and the relatively soft cap 50 is scraped off, generating dust.

[0017] Since the occurrence of the above-mentioned friction is unavoidable during the automatic mounting process using a capping device, the inventors have conducted various studies on the configuration of a cap that is less likely to generate dust even when subjected to such friction.

[0018] After detailed investigation, it was determined that the dust was generated when the cap rotated relative to the container body during screw fitting, overcoming tiny protrusions (burrs) along the parting line that were generated when the container body was injection molded. Therefore, the inventors considered that by conversely decreasing the rigidity of the cap, it would be easier to tolerate elongation caused by friction, and dust could be suppressed.

[0019] Based on this, the inventors conducted further studies and succeeded in suppressing the generation of dust by incorporating two types of resin with different flexural moduli in the cap. More specifically, the cap 50 according to this embodiment has a configuration in which a resin with a flexural modulus of 800 megapascals (MPa) or more is used as a base resin, and a sub-resin with a flexural modulus of 1000 MPa or more is mixed into this.

[0020] In the present invention, the flexural modulus of each resin is a value measured in accordance with JIS K 6921-2 using a test piece consisting of the respective resin alone. The types and ratios of the base resin and the sub resin in the cap 50 can be identified by measurement using a differential scanning calorimeter (DSC).

[0021] The base resin is typically polypropylene. There is no particular restriction on the type of polypropylene, but random polymers are preferred. There is no particular upper limit to the flexural modulus of the base resin, but if it is 1200 MPa or less, the connecting portion that is the pivot axis of the hinge lid 51 becomes less likely to break, which is preferable. The mass ratio of the base resin in the cap 50 needs only to exceed 50%, and is preferably 70% or more.

[0022] The sub-resin is typically high density polyethylene (HDPE), but medium density polyethylene (MDPE) and the like can also be used.

[0023] The effects of the cap according to this embodiment will be further described using experimental examples. The technical scope of the present invention is not limited in any way by the specific contents of each experimental example.

[0024] The materials used in each experimental example are shown below. (Base resin) PP1: Flexural modulus 970MPa (SunAllomer polypropylene PM731V) PP2: Flexural modulus 800MPa (Japan Polypropylene WSX03) PP3: Flexural modulus 750MPa (Japan Polypropylene WMX03)

[0025] (Sub resin) HDPE1: Flexural modulus 1350MPa (Braskem plant-derived polyethylene SHA7260) HDPE2: Flexural modulus 1180MPa (Japan Polyethylene Co., Ltd., fossil fuel-derived polyethylene HJ580N) HDPE3: Flexural modulus 850MPa (Japan Polyethylene Corporation, fossil fuel-derived polyethylene HJ360)

[0026] Screw-fittable caps of the same shape and size for each experimental example were produced by injection molding using a resin composition made by mixing the base resin and sub resin in the ratio shown in Table 1. The number of samples was 200 for each experimental example. An appropriate amount of red pigment was mixed into the resin composition to make dust easier to see when it is generated.

[0027] [Table 1]

[0028] The prepared samples were mechanically attached to a container body made of PET using plant-derived resin with a biomass degree of 30, which could be screwed onto the sample. The torque during attachment was controlled at 350 N·cm using a torque meter (manufactured by NIDEK Drive Technology Co., Ltd.). After attaching the cap, the cap was manually removed from the packaging container, and the presence or absence of red dust was visually confirmed, and the number of samples that had been generated was recorded.

[0029] As shown in Table 1, in Experimental Example 6, in which only the base resin was used, dust generation was observed in 64 out of 200 samples (32%), whereas in the remaining Experimental Examples, in which the base resin and sub resin were mixed, no dust generation was observed in any of the samples, and dust was effectively suppressed.

[0030] On the other hand, deformation was observed in some samples in Experimental Examples 7 and 8. Most of the deformation occurred when the capping device chucked the cap, which resulted in the cap not being centered smoothly with the container body when attached, or poor appearance after attachment. Comparing Experimental Examples 1 to 5, in which no deformation occurred, with Experimental Examples 7 and 8, in which deformation occurred, it was inferred that a base resin having a flexural modulus of 800 MPa or more is preferable, and a sub-resin having a flexural modulus of more than 850 MPa and greater than the flexural modulus of the base resin, generally a flexural modulus of 1000 MPa or more, is preferable.

[0031] As described above, the cap according to the present embodiment is formed from a resin composition obtained by mixing a predetermined base resin and a sub resin, so that even when combined with a main container having higher rigidity than the cap, dust is unlikely to be generated, and deformation during the automatic capping process can be suppressed. Furthermore, there is no need to provide a separate liner material, and the cap can be easily manufactured. Furthermore, up to 30% plant-based plastic can be used as a sub-resin, and this can be effectively applied to the container body, including bio-PET, allowing the packaging container to be highly environmentally friendly.

[0032] Each embodiment of the present invention has been described above with reference to experimental examples. However, the specific configurations are not limited to these embodiments, and modifications and combinations of the configurations that do not depart from the gist of the present invention are also included.

[0033] For example, the cap according to this embodiment does not necessarily need to have a hinged lid, and may be a cap having only a screw. [Explanation of symbols]

[0034] 1 Packaging container 10 Container body 50 Cap

Claims

1. A cap that is attached to the opening of a container body by screw fitting, Contains 70% or more of a base resin with a bending modulus of 800 megapascals or more, Contains 30% or less of a sub-resin having a flexural modulus of 1000 MPa or more; cap.

2. The base resin is polypropylene. The cap of claim 1.

3. The sub resin is high density polyethylene; The cap of claim 1.

4. The high-density polyethylene is made from raw materials derived from plants. The cap according to claim 3.

5. having a hinged lid, The cap of claim 1.

6. A cap according to any one of claims 1 to 5; a container body formed of a synthetic resin and having an opening into which the cap can be screwed; Equipped with packaging container.

7. The container body contains biopolyethylene terephthalate. The packaging container according to claim 6.

8. The biopolyethylene terephthalate contains polyethylene terephthalate made from raw materials derived from plants. The packaging container according to claim 7.

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