Synthetic resin products

Abstract

To provide a synthetic resin product having a resin surface more improved in liquid repellency.SOLUTION: In a synthetic resin product 1 having a liquid-repellent resin surface 2, the resin surface 2 has a fine uneven pattern formed by injection molding, and the uneven pattern is formed of a base bottom surface 4 and protruding parts 3 having a cylindrical shape with a predetermined diameter W and a predetermined height H, which vertically protrude from the base bottom surface 4 and are aligned in both of an X direction and a Y direction vertical to each other with predetermined intervals D. The predetermined diameter W is 30 μm to 80 μm, and the predetermined interval D is 30 μm to 90 μm, and irregularities 3b like interference fringes are formed on a top surface 3a of the protruding part 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a synthetic resin product having a liquid-repellent resin surface. [Background technology]

[0002] Synthetic resin products having a liquid-repellent resin surface are used in a variety of applications, such as food containers for holding liquid foods such as soy sauce, sauce, honey, cake syrup, and soup, and the caps that are components thereof. Synthetic resin products having a liquid-repellent resin surface can, for example, provide a liquid-repellent resin surface on the inner surface of a container, thereby making it difficult for liquid foods to adhere to the inner surface and reducing leftover food. Furthermore, providing a liquid-repellent resin surface on the inner surface of a cap can make it difficult for liquid foods to adhere to the inner surface, thereby suppressing dripping and staining.

[0003] Conventionally, as a synthetic resin product having such a liquid-repellent resin surface, there has been known a product in which the resin surface has a fine uneven pattern formed by injection molding, the uneven pattern being formed by a substantially smooth base surface and cylindrical convex portions of a predetermined diameter and a predetermined height that protrude perpendicularly from the base surface and are arranged at predetermined intervals in both the X direction and the Y direction that are perpendicular to each other, the predetermined diameter of the convex portions being 30 μm to 80 μm and the predetermined intervals being 30 μm to 90 μm (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-188616 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the above-mentioned conventional synthetic resin products, there are cases where sufficient liquid repellency cannot be obtained depending on the type and viscosity of the liquid, and further improvement in liquid repellency has been desired.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a synthetic resin product having a resin surface with improved liquid repellency. [Means for solving the problem]

[0007] The synthetic resin product of the present invention is a synthetic resin product having a liquid-repellent resin surface, wherein the resin surface has a fine uneven pattern formed by injection molding, and the uneven pattern is formed by a base surface and cylindrical convex portions of a predetermined diameter and a predetermined height that protrude perpendicularly from the base surface and are arranged at predetermined intervals in both the X direction and the Y direction that are perpendicular to each other, wherein the predetermined diameter is 30 μm to 80 μm and the predetermined interval is 30 μm to 90 μm, and interference fringe-like unevenness is formed on the top surfaces of the convex portions.

[0008] In the synthetic resin product of the present invention having the above configuration, the predetermined height is preferably 20 μm to 160 μm.

[0009] In the synthetic resin product of the present invention having the above configuration, the predetermined height is preferably 20 μm to 100 μm.

[0010] In the above-described configuration, the synthetic resin product of the present invention is preferably a food container or a container-constituting member.

[0011] In the synthetic resin product of the present invention, in the above-mentioned configuration, the food is 0 ~10 6 It preferably has a viscosity of 10 ... [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a synthetic resin product having a resin surface with improved liquid repellency. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a plan view showing an uneven pattern on a resin surface of a synthetic resin product according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 2 is an enlarged view of the top surface of the protrusion shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A synthetic resin product according to one embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0015] In this specification and claims, the X direction means a direction along a first line parallel to the base plane of the resin surface, and the Y direction means a direction along a second line perpendicular to the first line and parallel to the base plane of the resin surface.

[0016] As shown in FIGS. 1 and 2, a synthetic resin product 1 according to this embodiment has a liquid-repellent resin surface 2.

[0017] The synthetic resin product 1 is an injection-molded product formed by injection molding a synthetic resin material using a mold. The resin surface 2 has a fine uneven pattern (a periodic structure of fine unevenness) formed by the injection molding. In other words, the resin surface 2 is an injection-molded surface having a fine uneven pattern.

[0018] The concave-convex pattern is formed by convex portions 3 and a base surface 4 .

[0019] The protrusions 3 are cylindrical and have a predetermined diameter W and a predetermined height H. They protrude perpendicularly from the base surface 4 and are arranged at predetermined intervals D in both the X and Y directions, which are perpendicular to each other. The predetermined diameter W of the protrusions 3 is 30 μm to 80 μm, and the predetermined interval D between the protrusions 3 is 30 μm to 90 μm. The predetermined diameter W / predetermined interval D is preferably 0.88 to 1.40. The base surface 4 is substantially smooth and may be a flat surface or a curved surface. Thus, the resin surface 2 is composed of the base surface 4 and a large number of protrusions 3 that protrude from the base surface 4 to a predetermined height H in the Z direction, which is perpendicular to both the X and Y directions.

[0020] The resin surface 2 having the above-mentioned uneven pattern has good liquid repellency against liquids.

[0021] In order to obtain good liquid repellency against liquid foods such as soy sauce, sauce, honey, cake syrup, and soup, the predetermined height H of the convex portion 3 is preferably 20 μm to 160 μm, and more preferably 20 μm to 100 μm.

[0022] The resin surface 2 can be easily obtained by providing the surface inside the cavity of a mold used for injection molding with irregularities (fine periodic structure) for transferring the irregular pattern. In this embodiment, a mold was used in which the fine periodic structure was formed by processing an aluminum surface that had been electrolessly nickel-phosphorus plated with a diamond blade. The material from which the mold body is formed is not particularly limited, and die steel, powder high-speed steel, cemented carbide, etc. can be used. Although photolithography, laser processing, etc. can be used to process the mold to provide the fine periodic structure, cutting processing using a diamond blade is preferred because it facilitates processing in the height direction (Z direction) and can also be used to process curved surfaces.

[0023] The specific method for forming the fine periodic structure was, for example, to first perform electroless nickel-phosphorus plating on the machining surface of the mold, forming a coating several tens to several hundreds of micrometers thick. Next, the nickel-phosphorus coating was cut using a flat groove machine to achieve a flatness on the top surface of the plated area with a flatness on the order of 10 nm. The flat groove machine was a type of cutting machine, using a single-crystal diamond blade with a sharp cutting edge and minimal irregularities, capable of machining grooves on a two-dimensional plane. The machining method was milling using a rotary tool. Milling is suitable for machining fine structures on the order of 10 μm because the cutting reaction force is minimal. After the above flattening process, the machining surface of the mold was fixed, and the cutting tool of the flat groove machine was replaced to create the fine periodic structure by cutting on the machining surface.

[0024] As described above, the protrusions 3 are cylindrical, but the outer peripheral surface may have a draft angle of the mold. That is, the outer peripheral surface of the cylindrical protrusions 3 may have a slight gradient that gradually increases in diameter toward the base surface 4. In this case, the predetermined diameter W means the diameter of the top surface 3a of the protrusions 3. Also, in this case, the predetermined distance D means the distance between the top surfaces 3a of the protrusions 3.

[0025] The synthetic resin material for forming the synthetic resin product 1 is not particularly limited and may be, for example, polyethylene terephthalate (PET), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), polypropylene (PP), silicone resin, polytetrafluoroethylene (PTFE), etc. From the viewpoint of enhancing liquid repellency, the synthetic resin material for forming the synthetic resin product 1 is preferably a material with a surface free energy equal to or less than that of PE (the surface free energy of PE is 32 mN / m), such as PP, silicone resin, or PTFE. In this embodiment, polypropylene (PP: for example, "BC08F" manufactured by Japan Polypropylene Corporation) is used as the synthetic resin material. It should be noted that the polypropylene may be "X1H" manufactured by Japan Polypropylene Corporation, the linear low-density polyethylene may be "25200J" manufactured by Prime Polymer Corporation, and the high-density polyethylene may be "HJ362" manufactured by Japan Polypropylene Corporation, but these materials are not limited to these.

[0026] To reduce the apparent surface free energy, a fluorine-containing coating or silicone coating may be applied to the fine periodic structure of the mold and the coating may be transferred to the resin molding surface, or silicone-containing PP may be used as the synthetic resin material.

[0027] The synthetic resin product 1 may be a container component such as a food container or cap. Alternatively, the synthetic resin product 1 may be tableware or the like. When the liquid-repellent resin surface 2 is provided on the inside of the container, adhesion of liquid food to the inner surface of the container can be suppressed, thereby reducing the amount of unused content (leftover content). Furthermore, when the liquid-repellent resin surface 2 is provided on the outside of the container, adhesion of liquid food to the outer surface of the container can be suppressed, thereby suppressing the occurrence of stains.

[0028] When the synthetic resin product 1 is used as a food container, the container may include a container body having a cylindrical mouth, a body continuing below the mouth, and a bottom closing the lower end of the body, and a cap having, for example, a cylindrical discharge portion that is attached to the mouth of the container body and can discharge a liquid food. The synthetic resin product 1 may also be such a cap, and the liquid-repellent resin surface 2 may be provided on the discharge portion of such a cap. When the body of the container body is squeezed (pressed) to discharge the contents, such as soy sauce, sauce, honey, cake syrup, or noodle soup, through the discharge portion of the cap, the liquid food can be drained smoothly at the discharge portion and the adhesion of the liquid food to the discharge portion can be suppressed. This can suppress the generation of stains at the discharge portion.

[0029] Generally, liquid foods have a shelf life of 10°C at 20°C. 0 ~10 6 It has a viscosity of 10 mPa·s. For example, the viscosity of Worcestershire sauce is 10 0.3 mPa·s, the viscosity of glucose syrup is 10 5.3 The synthetic resin product 1 can be suitably used as a container or a container component for food with such a viscosity.

[0030] 3, in the synthetic resin product 1 according to this embodiment, interference fringe-like irregularities 3b are formed on the top surface 3a (surface that is substantially parallel to and faces the same direction as the base surface 4) of each of the protrusions 3. That is, while the base surface 4 is substantially smooth, the top surface 3a of the protrusions 3 is not smooth, but has a shape that has interference fringe-like irregularities 3b.

[0031] The interference fringe-like irregularities 3b are formed by a plurality of arc-shaped grooves arranged concentrically with one another. The number of arc-shaped grooves may be one or more. The interference fringe-like irregularities 3b are formed by injection molding a synthetic resin material using a mold. That is, a mold for injection molding the synthetic resin product 1 is used in which fine interference fringe-like irregularities are formed by multi-beam processing on the bottom surface of the circular recess that forms the convex portion 3, and the interference fringe pattern of the mold is transferred to the top surface 3a of the convex portion 3 after molding, thereby forming the interference fringe-like irregularities 3b.

[0032] Direct laser interference patterning (DLIP) is a technique for forming nano-period uneven structures on a substrate by irradiating the surface of the substrate with multiple laser pulse beams that are overlapped (interfered). In this embodiment, the wavelength and fluence are 515 nm and 43 mJ / cm, respectively. 2 Two laser pulse beams with a frequency of 10 kHz are irradiated onto the mold 100 times at a pitch of 780 nm, thereby forming fine interference fringe-like irregularities on the bottom surface of the circular recess that forms the protrusion 3 of the mold.

[0033] 3, two interference fringe-like irregularities 3b are formed on the top surface 3a of one protrusion 3, but it is sufficient if at least one interference fringe-like irregularity 3b is formed. Also, it is preferable that interference fringe-like irregularities 3b are formed on the top surfaces 3a of all of the multiple protrusions 3, but some of the multiple protrusions 3 may have a substantially smooth top surface 3a on which no interference fringe-like irregularities 3b are formed.

[0034] In this way, in the synthetic resin product 1 of this embodiment, interference fringe-like irregularities 3b are provided on the top surface 3a of each of the numerous convex portions 3 that make up the fine uneven pattern on the resin surface 2. Therefore, compared to conventional synthetic resin products in which the top surfaces 3a of the convex portions 3 are approximately smooth, the contact area of ​​the top surfaces 3a of the convex portions 3 with liquid is reduced, thereby further improving the liquid repellency against liquids, particularly liquid foods such as soy sauce, sauce, honey, cake syrup, and noodle soup.

[0035] In order to verify the effects of the present invention, polypropylene (PP), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE) were used as base materials (synthetic resin materials) and were injection-molded to produce two sample surfaces: one with a substantially smooth base surface and a concavo-convex pattern formed by cylindrical convex portions of a predetermined diameter and a predetermined height that protrude perpendicularly from the base surface and are arranged at predetermined intervals in both the X and Y directions, which are perpendicular to each other, with interference fringe-like concavo-convex portions formed on the top surface of each convex portion ("with interference fringe-like concavo-convex portions"); and one with a substantially smooth base surface and a concavo-convex pattern formed by cylindrical convex portions of a predetermined diameter and a predetermined height that protrude perpendicularly from the base surface and are arranged at predetermined intervals in both the X and Y directions, which are perpendicular to each other, with interference fringe-like concavo-convex portions formed on the top surface of each convex portion ("without interference fringe-like concavo-convex portions"). For each sample surface, four types of projections were prepared, each with a diameter of 80 μm, a height of 100 μm, and intervals between the projections of 60 μm, 90 μm, 145 μm, and 205 μm.

[0036] The injection molding temperatures were 200°C for linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), and 240°C for polypropylene (PP). The polypropylene (PP) used was "X1H" manufactured by Japan Polypropylene Corporation, the linear low-density polyethylene (LLDPE) used was "25200J" manufactured by Prime Polymer Co., Ltd., and the high-density polyethylene (HDPE) used was "HJ362" manufactured by Japan Polypropylene Corporation.

[0037] For each of the sample surfaces described above, a drop of each liquid was applied to the sample surface: water, sauce (Bulldog Sauce's "Chunou Sauce" and "Worcestershire Sauce"), and soy sauce (Kikkoman Corporation's "Special Selection Whole Soybean Soy Sauce"), and the liquid repellency against the liquid was evaluated. The evaluation was performed as follows: if the liquid rolled without remaining in place on a horizontally placed sample surface, it was rated as Excellent; if the liquid rolled when the sample surface was tilted, it was rated as Good; if the liquid rolled but got caught when the sample surface was tilted, it was rated as Fair; and if the liquid adhered to the sample surface, it was rated as Bad. Table 1 shows the evaluation results.

[0038] [Table 1]

[0039] From the above evaluation results, it was confirmed that when the synthetic resin product according to this embodiment has a configuration in which the diameter of the convex portions is 80 μm, the height is 100 μm, the spacing is 60 μm or 90 μm, and interference fringe-like irregularities are formed on the top surfaces of the convex portions, better liquid repellency can be obtained for all liquids, including water, sauce, and soy sauce, compared to products in which no interference fringe-like irregularities are formed on the top surfaces of the convex portions, or products in which interference fringe-like irregularities are formed on the top surfaces of the convex portions but the spacing between the convex portions is greater than 90 μm.

[0040] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention.

[0041] For example, the synthetic resin product 1 is not limited to the above-mentioned food containers or container components such as caps, but may be containers or articles for various uses that come into contact with liquid. [Explanation of symbols]

[0042] 1. Synthetic resin products 2 Resin surface 3 Convex part 3a Top 3b Interference fringe pattern 4 Basal plane D. Predetermined interval W specified diameter H specified height

Claims

1. A synthetic resin product having a liquid-repellent resin surface, the resin surface has a fine uneven pattern formed by injection molding, the concave-convex pattern is formed by a base surface and cylindrical convex portions of a predetermined diameter and a predetermined height that protrude perpendicularly from the base surface and are arranged at predetermined intervals in both an X direction and a Y direction that are perpendicular to each other, the predetermined diameter is 30 μm to 80 μm; the predetermined interval is 30 μm to 90 μm, A synthetic resin product characterized in that interference fringe-like irregularities are formed on the top surfaces of the convex portions.

2. 2. The synthetic resin product according to claim 1, wherein the predetermined height is 20 μm to 160 μm.

3. 2. The synthetic resin product according to claim 1, wherein the predetermined height is 20 μm to 100 μm.

4. The synthetic resin product according to any one of claims 1 to 3, which is a food container or a container component.

5. The food product is 10 ０ ~10 ６ The synthetic resin product according to claim 4, having a viscosity of 1000 kJ / cm2.

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