JP2012062087A - Synthetic resin cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin cap with a thinned top wall while suppressing bleeding in print on an exterior surface of the thinned top wall and also suppressing read error from occurring when optically read-checking information printed on the exterior surface of the thinned top wall.SOLUTION: In the synthetic resin cap 1 having the top wall 2 for covering a container mouth, an exterior rough surface part 2d where fine irregularities are formed is prepared on the exterior surface 2a of the top wall 2 and also an interior rough surface part 2e where fine irregularities are formed is prepared on the interior surface 2b of the top wall 2. Here, the exterior rough surface part 2d is used as a printing part.

Description

  The present invention relates to a synthetic resin cap mounted on a container.

  In the synthetic resin cap attached to the container mouth as its sealing member, printing may be performed on the outer surface of the top wall that covers the container mouth from above. When the surface is smooth, the printing is easily peeled off. Therefore, when printing on the outer surface of the top wall, in order to increase the adhesion of the printing, fine irregularities are formed on the outer surface of the top wall, roughened, and printed on the rough surface. The method of applying is conventionally used (see, for example, Patent Document 1).

  Manufacturing information such as the date of manufacture is a typical example of information printed on the outer surface of the top wall of the cap. Usually, manufacturing information is printed at a bottling factory. Reading inspection is also performed (see, for example, Patent Document 2).

  In recent years, synthetic resin caps have been widely used as caps for milk bottle mouths, but rough surfaces are also applied to these synthetic resin caps for milk bottles. Manufacturing information may be printed on the outer surface of the top wall to which is applied (see, for example, Patent Document 3).

  In the case of a cap made of synthetic resin for milk bottles, it is usually made of a resin material that is not colored. If the outer surface of the top wall is not roughened, the haze (turbidity) of the top wall is low and transparent. High nature. For this reason, if the outer surface of the top surface wall is not roughened, the light from the inspection machine light source can easily pass through the top surface wall during the optical reading inspection of the print information, and the liquid level of the milk in the container The intensity of the reflected light from the surface becomes high, and the reflected light (especially light reflected on the bubble part on the liquid level) obstructs the optical reading of the printing information on the outer surface of the top wall, and the reading Error is likely to occur. On the other hand, when the rough surface processing is performed on the outer surface of the top wall, the haze of the top wall is high and the transparency is low compared to the case where the rough surface processing is not performed. Difficult to transmit through the top wall, and the intensity of the reflected light from the liquid level of milk in the container is low, which is unlikely to interfere with the optical reading of the printed information on the outer surface of the top wall, causing an error in the reading It is hard to do.

  In other words, in the case of a cap made of a resin material that is not colored, such as a cap made of synthetic resin for milk bottles, printing on the outer surface of the top wall is performed by roughening the outer surface of the top wall. This not only provides the advantage of improving adhesion, but also provides the advantage of suppressing the occurrence of reading errors during the reading inspection of the printed information.

  By the way, in the cap made of synthetic resin, in recent years, in order to save resources, it is required to reduce the amount of resin material used by reducing the thickness of the cap, but in the case of a cap, it is reduced in thickness including the top wall. If possible, since the top wall has a large area, the range of reduction in the amount of resin material used by thinning can be increased.

  However, when the top wall is thinned in a cap made of a resin material that is not colored, such as a synthetic resin cap for milk bottles, the attenuation of light transmitted through the top wall is small due to the thinning. Even if the outer surface of the top wall is roughened and manufacturing information is printed on it, the light from the inspection machine light source at the time of printing information reading inspection is easily transmitted, and from the liquid level of the container contents The intensity of the reflected light may increase, which may easily cause an error in reading print information on the outer surface of the top wall due to the reflected light.

  Therefore, when thinning the top wall of a cap made of a resin material without coloring, such as a synthetic resin cap for milk bottles, roughen the outer surface of the top wall to a rougher surface. It is conceivable to increase the amount of scattered light on the outer surface of the top wall to increase the haze so that the translucency of the top surface wall does not increase. Since the concave portion in the rough surface becomes deep, printing with an ink jet printer is not preferable because ink tends to flow in the concave portion and bleeding tends to occur in printing.

Japanese Utility Model Publication No. 4-65757 JP 2009-281795 A JP 2000-255610 A

  In view of the above circumstances, the present invention prevents the printing on the outer surface of the top wall from bleeding easily, and easily causes a reading error in the optical reading inspection of the printed information on the outer surface of the top wall. An object of the present invention is to obtain a cap made of a synthetic resin capable of reducing the thickness of the top wall while avoiding this.

  According to the present invention, in a cap made of synthetic resin having a top wall covering the container mouth portion, a fine unevenness is formed on the outer surface of the top wall to provide an outer rough surface portion, and the inner surface of the top wall is also fine. The synthetic resin cap is characterized in that an inner rough surface portion is formed by forming a rough surface and the outer rough surface portion is used as a printing portion.

  Further, the present invention is characterized in that the surface roughness of the outer rough surface portion is an arithmetic average roughness Ra of 1 to 100 μm, and an average length RSm between irregularities is 0.5 mm or less. It is a resin cap.

  The present invention also provides the synthetic resin cap, wherein the top wall has a thickness of less than 1.2 mm.

  In the present invention, the surface roughness of the inner rough surface portion is an arithmetic average roughness Ra of 0.1 to 50 μm, and an average length RSm between irregularities is 0.5 mm or less. It is a cap made of the synthetic resin.

  In addition, the present invention provides a cylindrical wall provided so as to extend downward from the peripheral edge of the top wall, and is positioned inside the cylindrical wall and extends downward from the inner surface of the top wall. The synthetic resin cap according to claim 1, further comprising an inner ring provided on the inner ring, wherein the inner rough surface portion is provided only on the inner surface of the top wall inside the inner ring.

  Further, the invention is characterized in that the synthetic resin cap is made of a polyolefin resin, and the polyolefin resin does not contain a colorant.

  According to this invention, the rough surface portion is also provided on the inner surface of the top wall, and not only the rough surface portion of the outer surface but also the inner rough surface portion can increase the haze of the top wall. Even if the thickness of the top wall is reduced compared to the conventional product without a rough surface on the inner surface, the rough surface processing of the outer rough surface portion is made so that printing does not easily spread. By having the surface part, the haze of the top wall can be set to a value equal to or higher than that of the conventional product.

  Therefore, according to the present invention, printing on the outer surface of the top wall is not easily smeared, and reading errors are not likely to occur during optical reading inspection of printed information on the outer surface of the top wall. In addition, the top wall can be thinned.

It is sectional drawing of the synthetic resin caps of this invention. It is a top view of a cap same as the above. It is a bottom view of a cap same as the above.

  An embodiment in which the embodiment of the synthetic resin cap of the present invention is applied to a milk bottle cap will be described with reference to FIGS. The cap made of synthetic resin of the present invention can also be applied to caps of containers other than milk bottles.

  First, the basic configuration of the cap 1 of the present invention will be described.

  Reference numeral 1 denotes a cap for a milk bottle, which is attached to the mouth portion 10 of the milk bottle and used as its sealing member. As shown in the drawing, the cap 1 includes a top wall 2, a cylindrical wall 3 extending below the peripheral edge 2 c of the top wall 2, and an inner surface of the top wall 2 while being positioned inside the cylindrical wall 3. The inner ring 4 extends downward from 2b, and when the milk bottle is attached to the mouth portion 10, the top wall 2 covers the mouth portion 10 from above while the inner peripheral surface 3b of the cylindrical wall 3 is covered. The formed engaging convex portion 3c is engaged with the engaging concave portion formed on the outer peripheral surface 10a of the mouth portion 10, and the sealing convex portion 4c formed on the outer peripheral surface 4a of the inner ring 4 is the mouth. The inner peripheral surface 10b of the portion 10 can be pressed and sealed between the surfaces (between the surface 4a and the surface 10b). Reference numeral 5 denotes a tab for opening the cap 1.

  The cap 1 is injection-molded with a polyolefin-based resin. Specifically, the cap 1 is integrally formed as a whole by injection molding using, as a material, polyethylene that does not include (addition of) a pigment or the like and is not colored. Note that the cap 1 is thinned, and in particular, the thickness t of the top wall 2 is thinner than that of the conventional product. Thereby, the cap 1 respond | corresponds to the request | requirement of thickness reduction.

  Next, the cap 1 of the present invention is provided with rough surface portions on both the outer surface 2a and the inner surface 2b of the top wall 2, and these rough surface portions will be described.

  In the cap 1, the outer surface 2a of the top wall 2 is provided with an outer rough surface portion 2d formed with fine irregularities, and manufacturing information such as the manufacturing date is printed on the rough surface by a printing means such as an ink jet printer. Is provided with a printing unit 2f. Here, the outer surface 1a of the cap 1 includes not only the outer surface 2a of the top wall 2 but also the outer peripheral surface 3a of the cylindrical wall 3 and the outer surface 5a of the tab 5 on the outer surface 2a of the top wall 2. Similar to the rough surface portion 2d, fine irregularities are formed and roughened. That is, the cap 1 has a roughened outer surface 1a as shown in FIG. 2 with point hatching for the sake of convenience of explanation, so that the whole has a white translucent appearance. It is supposed to present. In the present embodiment, as described above, the entire outer surface 1a of the cap 1 is roughened. However, the roughening of the outer surface of the cap 1 is performed on the outer rough surface portion of the outer surface 2a of the top wall 2. Only the 2d portion may be used.

  The cap 1 is also provided with an inner rough surface portion 2 e formed with fine irregularities on the inner surface 2 b of the top wall 2. The inner rough surface portion 2e is provided only in a portion of the inner surface 2b of the top surface wall 2 located inside the inner ring 4, and the other portions of the inner surface 2b are not roughened. The outer peripheral surface 4a, the inner peripheral surface 4b, and the inner peripheral surface 3b of the cylindrical wall 3 are not roughened. That is, as shown in FIG. Only the inner rough surface portion 2e located inside the inner ring 4 on the inner surface 2b of the top wall 2 is roughened. The inner surface 1b of the cap 1 may be roughened except for the inner rough surface portion 2e. However, the inner surface 1b of the cap 1 can be easily roughened by using only the inner rough surface portion 2e. In addition, the sealing performance of the sealing projection 4c of the inner ring 4 can be prevented from being deteriorated.

  As a roughening method of the rough surface portions such as the outer rough surface portion 2d and the inner rough surface portion 2e, for example, a method in which the surface of the molding die is processed and roughened at the stage of the molding process is used. Can be adopted.

  As described above, the outer rough surface portion 2d is provided with the printing portion 2f by printing manufacturing information such as a manufacturing date on the rough surface by printing means such as an ink jet printer. The degree of the surface roughness of the outer rough surface portion 2d is within the range of the surface roughness of the conventional product that is supposed to be able to increase the adhesion of the ink to be printed while preventing the ink from bleeding easily. Can be set.

  As for the degree of the surface roughness of the outer rough surface portion 2d, the range of the roughness can be set from the degree of roughness of the conventional product as described above, but the minimum value of the haze required for the top wall 2 is also the conventional product. Can be set from the haze. That is, the reason why haze is required on the top wall 2 is to prevent occurrence of a reading error due to reflected light from the liquid surface of milk during the optical reading inspection of manufacturing information printed on the outer rough surface portion 2d. The haze of the top wall of the conventional product can suppress the occurrence rate of reading errors within the allowable range. If there is a haze of the same or higher than the haze of the top wall of the conventional product, it is about the same as the conventional product As described above, the occurrence rate of the reading error of the inspection machine can be suppressed, that is, a value comparable to the haze of the top wall of the conventional product can be set as the minimum value of the haze required for the top wall 2. .

  Here, the cap 1 is provided with the inner rough surface portion 2 e as described above, and the inner surface 2 b of the top wall 2 is also provided with the rough surface portion. By providing the inner rough surface portion 2e, the cap 1 can haze the top wall 2 without making the outer rough surface portion 2d rougher even if the thickness t of the top wall 2 is reduced. Can be more than the required value. That is, the cap 1 prevents the printing on the outer rough surface portion 2d of the top wall 2 from easily bleeding, and prevents the reading error from easily occurring during the optical reading inspection of the printed information. The top wall 2 can be thinned.

  As for the degree of the surface roughness of the inner rough surface portion 2e, at least the roughness that allows the haze of the top surface wall 2 to be equal to or greater than the set value is necessary, but the minimum value of the necessary surface roughness is the above-mentioned The minimum value of the haze required for the top wall 2 set as described above, the surface roughness of the outer rough surface portion 2d, and the thickness t of the top wall 2 can be determined. In the case of the inner rough surface portion 2e, printing is not performed unlike the outer rough surface portion 2d, and even if the degree of roughness is increased, there is no problem in printing, and the inner ring 4 If the inner rough surface portion 2e is provided in the inner portion of the inner ring 4 while avoiding the sealing convex portion 4c, the problem of deterioration in sealing performance does not occur even if the degree of roughness is increased. Therefore, the degree of roughness can be made high, and the haze of the top wall 2 can be made higher than that of the conventional product so that a reading error at the time of inspection does not easily occur.

  Finally, specific examples of the thickness t of the top wall 2 of the cap 1, the haze, the degree of the surface roughness of the outer rough surface part 2d, and the degree of the surface roughness of the inner rough surface part 2e will be described.

  Specifically, the thickness t of the top wall 2 can be less than that of the conventional product of 1.2 mm, for example, 0.6 mm to 0.9 mm. That is, the thickness t of the top wall 2 can be 25% or more thinner than the conventional product. The thickness t of the top wall 2 preferably has a thickness of at least about 0.6 mm to 0.7 mm, for example, when high-density polyethylene is used as the material in order to ensure the sealing performance of the inner solution. When low density polyethylene is used, it preferably has a thickness of at least about 0.8 mm to 0.9 mm. That is, the thickness t of the top wall 2 can be 0.6 mm or more and less than 1.2 mm.

  The degree of the surface roughness of the outer rough surface portion 2d of the top wall 2 can be set within the range of the surface roughness of the conventional product as described above. Specifically, the standard of JIS-B-0601 is used. The surface roughness based on the arithmetic average roughness Ra can be 1 to 100 μm, and the average length RSm between irregularities can be 0.5 mm or less, for example, the arithmetic average roughness Ra is 2 μm, And average length RSm between unevenness | corrugation can be about 0.2 mm. The surface roughness of the outer rough surface portion 2d is not preferable if the arithmetic average roughness Ra is less than 1 μm because the ink attached to the printing portion 2f is easily peeled off. Further, if the arithmetic average roughness Ra is greater than 100 μm, problems such as bleeding of ink adhering to the printing portion 2f are likely to occur, and if the average length RSm between irregularities is greater than 0.5 mm, This is not preferable because the haze of the face wall 2 becomes small and reading errors during inspection cannot be completely prevented.

  The degree of surface roughness of the inner rough surface portion 2e of the top wall 2 is based on the standard of JISB0601, with an arithmetic average Ra of 0.1 to 50 μm, and an average length RSm between irregularities of 0.5 mm. For example, the arithmetic average roughness Ra can be set to 0.3 μm, and the average length RSm between the irregularities can be set to about 0.01 mm. The surface roughness of the inner rough surface portion 2e is not preferable if the arithmetic average roughness Ra is less than 0.1 μm, because it becomes difficult to process the unevenness and the productivity is poor. Further, when the arithmetic average roughness Ra is larger than 50 μm, it becomes a factor of reducing the sealing performance. When the average length RSm between the irregularities is larger than 0.5 mm, the top wall is similar to the outer rough surface portion 2d. This is not preferable because the haze of 2 may be reduced and reading errors during inspection may not be completely prevented. Here, in the case where the inner rough surface portion 2e is only a portion located inside the inner ring 4, even if the inner rough surface portion 2e is made rougher, the sealing performance does not deteriorate, so the degree of the surface roughness is The arithmetic average roughness Ra may be 50 μm or more.

  In addition, the specific example of the said surface roughness is based on the measurement result using the Mitutoyo company surface roughness measuring device (SV-C624) about both the outer side rough surface part 2d and the inner side rough surface part 2e.

DESCRIPTION OF SYMBOLS 1: Cap 1a: Outer surface 1b: Inner surface 2: Top surface wall 2a: Outer surface 2b: Inner surface 2c: Peripheral part 2d: Outer rough surface part 2e: Inner rough surface part 2f: Printing part 3: Cylindrical wall 3a: Outer surface 3b : Convex part for engagement 4: inner ring 4a: outer peripheral surface 4b: inner peripheral surface 4c: convex part for sealing 5: tab 5a: outer surface 10: bottle mouth part 10a: outer peripheral surface 10b: inner peripheral surface

Claims (6)

In the cap made of synthetic resin having the top wall covering the container mouth,
A fine unevenness is formed on the outer surface of the top wall to provide an outer rough surface portion, an inner rough surface portion is provided to form an inner rough surface portion on the inner surface of the top wall, and the outer rough surface portion is used as a printing portion. A synthetic resin cap characterized by   2. The synthetic resin according to claim 1, wherein the outer rough surface portion has an arithmetic average roughness Ra of 1 to 100 μm and an average length RSm between irregularities of 0.5 mm or less. Made of caps.   The synthetic resin cap according to claim 1 or 2, wherein a thickness of the top wall is less than 1.2 mm.   4. The surface roughness of the inner rough surface portion is an arithmetic average roughness Ra of 0.1 to 50 μm, and an average length RSm between irregularities of 0.5 mm or less. A synthetic resin cap according to any one of the above.   A cylindrical wall continuously provided on the peripheral edge of the top wall; and an inner ring located on the inner surface of the top wall and positioned on the inner surface of the top wall. The synthetic resin cap according to any one of claims 1 to 4, wherein the cap is provided only on the inner surface of the top wall inside the ring.   6. The synthetic resin cap according to claim 1, wherein the synthetic resin cap is made of a polyolefin-based resin, and the polyolefin-based resin does not contain a colorant.

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