JP2023148934A - Antibacterial molding and manufacturing method thereof - Google Patents

Abstract

To provide an antibacterial molding capable of heightening antibacterial performance.SOLUTION: An antibacterial molding has an antibacterial region formed by combining a plurality of independent antibacterial surfaces having different heights. The plurality of antibacterial surfaces have a first antibacterial surface having a highest height, a second antibacterial surface having a lowest height, and an intermediate antibacterial surface having an intermediate height between the height of the first antibacterial surface and the height of the second antibacterial surface. Among the plurality of antibacterial surfaces, all of an average value of the first antibacterial surface, the average value of the second antibacterial surface and the average value of the intermediate antibacterial surface are 35.0 μm2 or more. 95.0 μm2 or less, and all of the difference of the most frequent value of a height distribution between the first antibacterial surface and the intermediate antibacterial surface and difference of most frequent value of a height distribution between the intermediate antibacterial surface and second antibacterial surface are 1.70 μm or more and 10.0 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an antibacterial molded article and a method for producing the same.

Many products with antibacterial properties are on the market due to increasing consumer awareness. In many cases, antibacterial properties are imparted to the article by coating the surface of the article with an antibacterial agent or by embedding silver nanoparticles.

Furthermore, in recent years, attempts have been made to physically obtain an antibacterial effect by providing a fine uneven structure on the surface of an article (for example, Patent Documents 1 and 2). Most of these attempts to kill bacteria or suppress the movement of bacteria by providing minute protrusions on the surface of the article. Therefore, sharp protrusions were provided to kill the bacteria, and protrusions were provided with the same spacing as the bacteria.

Japanese Patent Application Publication No. 2017-132916 JP 2019-151614 Publication

Here, the effects of the above-mentioned antibacterial agents and antibacterial articles containing silver nanoparticles may disappear over time, and there have also been concerns about their safety to living organisms. As a result, there have been cases where restrictions have been placed on applications and usage environments. According to the method of providing a fine uneven structure on the surface of an article as disclosed in Patent Document 1 and Patent Document 2, the above concerns are resolved. However, the methods described in Patent Document 1 and Patent Document 2 have a problem in that the antibacterial activity does not increase as much as expected.

The present invention has been made in view of the above problems. The object of the present invention is to provide an antibacterial molded article, which is provided with a fine uneven structure on the surface thereof to impart antibacterial activity, and has enhanced antibacterial activity, and a method for producing the same.

The antibacterial molded article for solving the above problems has an antibacterial region formed by combining a plurality of independent antibacterial surfaces having different heights. The plurality of antibacterial surfaces have a first antibacterial surface having the highest height, a second antibacterial surface having the lowest height, and a height intermediate between the height of the first antibacterial surface and the height of the second antibacterial surface. The plurality of antibacterial surfaces include an intermediate antibacterial surface, and the average value of the surface area of the first antibacterial surface, the average value of the surface area of the second antibacterial surface, and the average value of the surface area of the intermediate antibacterial surface are all 35.0 μm ² greater than or equal to 95.0 ^μm2 , and the difference in the mode of the height distribution between the first antibacterial surface and the intermediate antibacterial surface, and the difference between the mode of the height distribution between the intermediate antibacterial surface and the second antibacterial surface. The difference in the mode of the height distribution is 1.70 μm or more and 10.0 μm or less in all cases.

In addition, a method for producing an antibacterial molded article to solve the above problem includes forming the antibacterial region on the surface of the molded article, or molding a molded article having the antibacterial region on the surface. This is the manufacturing method.

According to the present invention, there is provided an antibacterial molded article, which is provided with a fine uneven structure on the surface thereof to impart antibacterial activity, and has enhanced antibacterial activity.

FIG. 1 is a laser micrograph showing an example of an antibacterial area according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing the antibacterial area shown in FIG. FIG. 3A is a schematic diagram showing the antibacterial area cut along the imaginary line AA shown in FIG. 2 when viewed in the direction of the arrow in the figure, and FIG. FIG. 3 is a schematic diagram showing the cut antibacterial region when viewed in the direction of the arrow in the figure. FIG. 4 is a schematic plan view showing an antibacterial region having only a first antibacterial surface having the highest height and a second antibacterial surface having the shortest height. FIG. 5 is a plan view schematically showing another example of the antibacterial region according to an embodiment of the present invention. FIG. 6 is a plan view schematically showing still another example of the antibacterial region according to an embodiment of the present invention. FIG. 7 is an example of a height distribution spectrum obtained by observing an antibacterial region with a laser microscope. FIG. 8 is an example of a contour curve obtained for a profile line arbitrarily set in an antibacterial region.

The antibacterial molded article according to one embodiment of the present invention has an antibacterial region imparted with antibacterial activity on at least a portion of its surface. The antibacterial area is formed by a combination of a plurality of antibacterial surfaces having different heights.

[Antibacterial area]
FIG. 1 is a laser micrograph showing an example of the antibacterial area. Figure 1 shows a photograph in which the height of the surface of the antibacterial area was measured using a laser microscope, and different colors were assigned to each height. FIG. 2 is a plan view schematically showing the antibacterial area shown in FIG. FIG. 3A is a schematic diagram showing the antibacterial area cut along the imaginary line AA shown in FIG. 2 when viewed in the direction of the arrow in the figure. (The cross-sectional shape of the area is shown by a dotted line.) FIG. 3B is a schematic diagram showing the antibacterial region cut along the imaginary line BB shown in FIG. 2 when viewed in the direction of the arrow in the figure.

As shown in FIGS. 1, 2, 3A, and 3B, the antimicrobial region 100 has a first antimicrobial surface 110 with the highest height, a second antimicrobial surface 120 with the lowest height, and an intermediate height. It has an intermediate antimicrobial surface 130. The antibacterial area 100 is formed by combining and arranging a plurality of antibacterial surfaces having different heights.

Many bacteria have a mechanism by which when their density increases, their growth slows down and they die. Furthermore, each bacterium releases an attractant, and its density is recognized by sensing the attractant. In other words, as the amount of attractant increases, the growth of bacteria is suppressed, and as the bacteria die, the density decreases. Here, since each of the above-mentioned antibacterial surfaces has a surface area set within a predetermined range, even if the amount of bacteria is relatively small, the concentration of the attractant released by the bacteria is sufficiently increased. As a result, the bacteria stop growing and die in a relatively short period of time and before they can grow significantly. Therefore, it is difficult for the amount of bacteria to increase beyond a certain amount over a long period of time, and a state in which there are few bacteria can be maintained.

By making the average value of the surface area of each of the antibacterial surfaces smaller, the antibacterial effect due to the density of bacteria can be more fully exhibited. On the other hand, by increasing the average value of the surface area of each antibacterial surface to a certain extent, a certain amount of bacteria can be present on the antibacterial surface, and the antibacterial effect due to the density of the bacteria can be exerted on each antibacterial surface. be able to. From the viewpoint of balancing these, the first antibacterial surface 110, the second antibacterial surface 120, and the intermediate antibacterial surface 130 all have an average surface area of 35.0 μm ² or more and 95.0 μm ² or less, and 35 μm ² It is preferably 70 μm ² or more, and more preferably 35 μm ² or more and 50 μm ² or less.

By increasing the height difference between adjacent antibacterial surfaces to some extent, it is possible to make it difficult for bacteria to overcome the wall between adjacent antibacterial surfaces and to move to a higher antibacterial surface. On the other hand, by suppressing the height difference between adjacent antibacterial surfaces within a predetermined range, it is possible to suppress the growth of bacteria on the walls between the antibacterial surfaces. From the viewpoint of balancing these, the difference between the mode of the height distribution of the first antibacterial surface 110 and the mode of the height distribution of the intermediate antibacterial surface 130, and the mode of the height distribution of the intermediate antibacterial surface 130 are determined. The difference between the value and the mode of the height distribution of the second antibacterial surface 120 is 1.70 μm or more and 10.0 μm or less, preferably 1.70 μm or more and 8.00 μm or less, and 2. More preferably, the thickness is 00 μm or more and 3.00 μm or less. Note that the difference in the mode of these height distributions does not directly reflect the difference in height between adjacent antibacterial surfaces, but even if the difference in the mode of these height distributions is within the above range. For example, it is presumed that for more antibacterial surfaces, the difference in height between adjacent antibacterial surfaces will be within a sufficient range.

The first antibacterial surface 110, the second antibacterial surface 120, and the intermediate antibacterial surface 130 all have a surface area set within a predetermined range, making it difficult for bacteria to overcome the wall between them and the adjacent antibacterial surface. Difficult to transfer to highly antibacterial surfaces. Therefore, the bacteria present on each antibacterial surface can only remain on the antibacterial surface or migrate to an adjacent antibacterial surface with a lower height. If the bacteria remain on the antibacterial surface, the density of the bacteria (concentration of the attractant) will increase sufficiently even if the bacteria multiply slightly, and the bacteria will stop multiplying and die. Additionally, if bacteria move to an antibacterial surface that is lower in height, the density of the bacteria (concentration of the attractant) on the antibacterial surface will increase sufficiently, so the bacteria will stop multiplying and die. . In this way, by inhibiting the movement of bacteria to higher antibacterial surfaces, it is possible to suppress the spread of bacteria and inhibit the proliferation of the bacteria on each antibacterial surface, or to kill them.

As shown in FIG. 1, in this embodiment, each of the plurality of first antibacterial surfaces 110 is arranged independently, and no other first antibacterial surfaces 110 are arranged in contact with the outer periphery thereof. More specifically, each first antibacterial surface 110 has only the second antibacterial surface 120 and the intermediate antibacterial surface 130 in contact with its outer periphery, and the other surfaces are arranged in series so as to be in contact with the outer periphery. There is no first antimicrobial surface 110. Therefore, the bacteria present on each first antibacterial surface 110 cannot move to other first antibacterial surfaces 110 and can only stay on the first antibacterial surface 110. As a result, when the density of the bacteria (concentration of the attractant) on the first antibacterial surface 110 increases, the bacteria stop multiplying and die.

Moreover, as shown in FIG. 1, in this embodiment, the plurality of second antibacterial surfaces 120 are all arranged independently, and there are no other second antibacterial surfaces 120 arranged in contact with the outer periphery thereof. . More specifically, each of the second antibacterial surfaces 120 has its outer periphery in contact with only the first antibacterial surface 110 and the intermediate antibacterial surface 130, and other surfaces arranged in series so as to be in contact with the outer periphery. There is no second antimicrobial surface 120. Therefore, the bacteria present on each second antibacterial surface 120 cannot move to other second antibacterial surfaces 120 and may remain on the second antibacterial surface 120, or may remain on an adjacent antibacterial surface with a lower height. I can only move to. As a result, the density of the bacteria (concentration of the attractant) on the second antibacterial surface 120 or the adjacent antibacterial surface increases sufficiently, so that the bacteria stop multiplying and die.

In this embodiment, the antimicrobial region 100 has a first antimicrobial surface 110 with the highest height and a second antimicrobial surface 120 with the lowest height, as well as an intermediate antimicrobial surface 130 with an intermediate height. By arranging the intermediate antibacterial surface 130 and combining a plurality of antibacterial surfaces with different heights in at least three ways, the other first antibacterial surface is placed in contact with the outer periphery of the first antibacterial surface 110 and the second antibacterial surface. 110 and the second antibacterial surface may be difficult to place.

FIG. 4 is a schematic plan view showing a region 400 having only a first surface 410 with the highest height and a second surface 420 with the lowest height. In the region 400 shown in FIG. 4, a certain first surface 410a is in contact with an adjacent first surface 410b at a point P. If the bacteria move and spread from the first surface 410a to the first surface 410b via this point P, the density of the bacteria (concentration of the attractant) on the first surface 410 will not increase sufficiently, and the bacteria will Growth arrest and death may not be achieved sufficiently. If the first surfaces 410 of reduced size are arranged at the same position so that the adjacent first surfaces 410 do not touch each other, then the adjacent second surfaces 420 are connected at the bottom of the region 400. As a result, bacteria move and spread from one second surface 420 to an adjacent second surface 420. As a result, the density of bacteria (concentration of attractant) on the second surface 420 (bottom surface) may not be sufficiently increased, and the growth of bacteria may not be sufficiently stopped or killed. In contrast, in this embodiment, by providing the intermediate antibacterial surface 130, it is possible to arrange the adjacent first antibacterial surfaces 110 and the adjacent second antibacterial surfaces 120 so that they do not touch each other (see FIG. 2). The effect of stopping and killing bacteria (antibacterial effect) due to the recent increase in density on each antibacterial surface can be more fully exerted.

More effectively moves bacteria between the first antibacterial surfaces 110 placed at different positions, between the second antibacterial surfaces 120 placed at different positions, and between the intermediate antibacterial surfaces 130 placed at different positions. From the viewpoint of suppressing antibacterial effects, it is preferable that the distances between different first antibacterial surfaces 110, the distances between different second antibacterial surfaces 120, and the distances between different intermediate antibacterial surfaces 130 are as far as possible. On the other hand, from the viewpoint of keeping the average value of the surface area of each antibacterial surface within the above-mentioned range, the distance between each first antibacterial surface 110, each second antibacterial surface 120, and each intermediate antibacterial surface 130 should be It is preferable not to separate them too far. From the viewpoint of balancing these, the average value of the distance between a certain first antibacterial surface 110 and the first antibacterial surface 110 that is closest to it, and the distance between a certain second antibacterial surface 120 and the second antibacterial surface 120 that is closest to it, It is preferable that the average value of the distance between the intermediate antibacterial surface 130 and the intermediate antibacterial surface 130 closest to it are both 0.5 μm or more and 95 μm or less, and 1.5 μm. It is more preferably 45 μm or less, and even more preferably 2.0 μm or more and 14 μm or less.

In addition, when forming each antibacterial surface by forming convex portions from the surface of the base material, the shape tends to be such that multiple convex portions protrude from the surface with the lowest height (bottom surface). Due to its shape, the bottom surface is continuous, making it easy for bacteria to grow on the bottom surface. When forming each antibacterial surface, the formation conditions are adjusted so that the bottom surface has a discontinuous shape, and the average value of the surface area of the second antibacterial surface 120 having the lowest height is 35.0 μm ² or more and 95.0 μm ² Hereinafter, preferably 35 μm ² or more and 70 μm ² or less, more preferably 35 μm ² or more and 50 μm ^{2 or} less. Similarly, by adjusting the formation conditions, the average value of the distance between a certain first antibacterial surface 110 and the nearest first antibacterial surface 110 is 0.5 μm or more and 95 μm or less, preferably 1.5 μm or more and 45 μm. Hereinafter, it is more preferably 2.0 μm or more and 14 μm or less.

In addition, the first antibacterial surface having the highest height is likely to cause bacteria to move between adjacent antibacterial surfaces, and bacteria will likely multiply therein. Therefore, by adjusting the formation conditions, the average value of the surface area of the first antibacterial surface 110 is set to 35.0 μm ² or more and 95.0 μm ² or less, preferably 35 μm ² or more and 70 μm ² or less, and more preferably 35 μm ² or more and 50 μm ^{2 or} less. do. Similarly, by adjusting the formation conditions, the average value of the distance between a certain second antibacterial surface 120 and the second antibacterial surface 120 closest to it is 0.5 μm or more and 95 μm or less, preferably 1.5 μm or more and 45 μm. Hereinafter, it is more preferably 2.0 μm or more and 14 μm or less.

Similarly, the formation conditions are adjusted so that the average value of the surface area of the intermediate antibacterial surface 130 is 35.0 μm ² or more and 95.0 μm ² or less, preferably 35 μm ² or more and 70 μm ² or less, and more preferably 35 μm ² or more and 50 μm ^{2 or} less. do. Similarly, by adjusting the formation conditions, the distance between a certain intermediate antibacterial surface 130 and the nearest intermediate antibacterial surface 130 is 0.5 μm or more and 95 μm or less, preferably 1.5 μm or more and 45 μm or less, more preferably It is desirable that the thickness be 2.0 μm or more and 14 μm or less.

In this embodiment, the first antibacterial surface 110, the second antibacterial surface 120, and the intermediate antibacterial surface 130 are arranged in a rectangular lattice shape such that the lines of each antibacterial surface are orthogonal in the vertical and horizontal directions. In the rows, the first antibacterial surfaces 110 and the intermediate antibacterial surfaces 130 are arranged alternately (FIG. 3A), and in the other adjacent rows, the second antibacterial surfaces 120 and the intermediate antibacterial surfaces 130 are arranged alternately (FIG. 3B), and The arrangement of the second antibacterial surfaces 120 is shifted between the first row and the other rows (FIGS. 3A and 3B). However, the arrangement of each antibacterial surface is not limited to this, and may be arranged irregularly or regularly.

Even when the antibacterial surfaces are arranged regularly, the arrangement of the antibacterial surfaces is not limited to that shown in FIGS. , each antibacterial surface may be arranged on two non-orthogonal straight lines that intersect at a predetermined angle (FIG. 5). Further, the first antibacterial surface 610, the second antibacterial surface 620, and the intermediate antibacterial surface 630 may be arranged in a shape other than a square lattice, such as a triangular lattice (FIG. 6).

In this embodiment, the first antibacterial surface 110 is composed of a plurality of antibacterial surfaces having the same height, but the antibacterial region 100 may have only one first antibacterial surface 110 having the highest height. good. Further, although the second antibacterial surface 120 is composed of a plurality of antibacterial surfaces having the same height, the antibacterial region 100 may have only one second antibacterial surface 120 having the lowest height. Further, in the present embodiment, the intermediate antibacterial surface 130 is composed of a plurality of antibacterial surfaces having the same height, but the antibacterial region 100 may have a plurality of intermediate antibacterial surfaces 130 having different heights. . When the antibacterial region 100 has a plurality of intermediate antibacterial surfaces 130 with different heights, the intermediate antibacterial surfaces 130 of each height satisfy the above-mentioned average value of the surface area, and the height is the same as the one closest to the other surface area. It is preferable that the height difference between the first antibacterial surface 110, the intermediate antibacterial surface 130, and the second antibacterial surface 120 satisfies the condition of the difference in the mode of the height distribution described above for the first antibacterial surface 110, the intermediate antibacterial surface 130, and the second antibacterial surface 120. Note that from the viewpoint of facilitating the production of the antibacterial region 100, it is preferable that all the intermediate antibacterial surfaces of the antibacterial region 100 have substantially the same height, and when the antibacterial region 100 has intermediate antibacterial surfaces of different heights, It is desirable to have intermediate antibacterial surfaces having two to five types of heights, preferably two to three types, and more preferably two types. The existence of "intermediate antibacterial surfaces with different heights" means that there is a clear difference between the modes of the height distribution, and the threshold described below can be set between each intermediate antibacterial surface. , means that two or more clusters of intermediate antibacterial surfaces can be confirmed. At this time, the average value of the surface area of the intermediate antibacterial surface, the mode of the height distribution, and the distance between the intermediate antibacterial surface and the nearest intermediate antibacterial surface are for each of the plurality of intermediate antibacterial surfaces that are a group of predetermined heights. Measured are the mean value of the surface area, the mode of the height distribution and the distance between the nearest intermediate antimicrobial surface.

Note that the first antibacterial surface 110, the second antibacterial surface 120, and the intermediate antibacterial surface 130 may have the same average surface area as described above, or may have different surface areas for each antibacterial surface. The average values may differ within the ranges mentioned above.

The average value of the surface area of each antibacterial surface can be determined by the following method. First, the antibacterial area is observed using a laser microscope to obtain a height distribution spectrum that shows the distribution (frequency) of measurement points relative to height. FIG. 7 is an example of a height distribution spectrum obtained at this time. From FIG. 7, it can be confirmed that there are three peaks: peak 710 (corresponding to the first antibacterial surface 110), peak 720 (corresponding to the second antibacterial surface 120), and peak 730 (corresponding to the intermediate antibacterial surface 130). . Assuming that the height distribution spectrum shown in Figure 7 is a set of normal distributions corresponding to these peaks, the intersection of adjacent normal distributions (if there is no intersection, the normal distribution with lower height becomes 0) point) as the threshold. In FIG. 7, a threshold 740 between peaks 710 and 730 and a threshold 750 between peaks 730 and 720 can be seen. Then, by calculating the total area of regions whose height is higher than the highest threshold 740 and dividing the obtained total area by the number of regions whose height is higher than the highest threshold 740, the height is calculated. The average value of the surface area of the first antibacterial surface with the highest value can be determined. Next, the total area of the regions whose height is higher than the next highest threshold 750 is determined, and the total area of the regions higher than the threshold 740 is subtracted from the obtained total area. By dividing the area obtained in this way (corresponding to the intermediate antibacterial surface 130) by the number of regions whose height is higher than the threshold value 750 and smaller than the threshold value 740, the average surface area of the intermediate antibacterial surface is calculated. You can find the value. Finally, the total area of areas above threshold 750 is subtracted from the total surface area of the antimicrobial area. By dividing the area obtained in this way (corresponding to the second antibacterial surface 120) by the number of regions whose height is smaller than the threshold value 750, the average value of the surface area of the second antibacterial surface with the lowest height is calculated. can be found. Note that when the antibacterial region has a plurality of intermediate antibacterial surfaces having different heights, more peaks and thresholds can be set in the height distribution spectrum. By repeating the calculation of the average value of the surface area of the intermediate antibacterial surface based on these peaks and threshold values, it is possible to calculate the average value of the surface area of each intermediate antibacterial surface. The number of regions corresponding to each peak can be measured using known image analysis software or the like.

Further, the difference between the mode of the height distribution of the first antibacterial surface 110 and the mode of the height distribution of the intermediate antibacterial surface 130 is the difference in height between the peak 710 and the peak 730 in FIG. can do. Similarly, the difference between the mode of the height distribution of the intermediate antibacterial surface 130 and the mode of the height distribution of the second antibacterial surface 120 is the difference in height between the peak 730 and the peak 720 in FIG. It can be done.

Further, the average value of the distance between a certain first antibacterial surface 110 and the first antibacterial surface 110 closest thereto can be calculated from the cross-sectional curve obtained by observing the antibacterial area using the laser microscope. FIG. 8 is an example of a cross-sectional curve obtained for a profile line arbitrarily set in an antibacterial region. This cross-sectional curve shows a first antibacterial surface 110, a second antibacterial surface 120, and an intermediate antibacterial surface 130. On this cross-sectional curve, a virtual line is set that indicates the height corresponding to the threshold value 740 and the threshold value 750 set in the measurement of the average value of the surface area. Determine the distance D1 between the intersections of the virtual line corresponding to the threshold 740 and the cross-sectional curve between a set of first antibacterial surfaces 110 set so that no other first antibacterial surfaces are sandwiched therebetween; Let the distance between these one antibacterial surfaces 110 be. In this way, the distance between one first antibacterial surface 110 is determined for each of the ten arbitrarily set profile lines, and the average of these is calculated between a certain first antibacterial surface 110 and the nearest one. 1 and the antibacterial surface 110. The average value of the distance D2 between a certain second antibacterial surface 120 and the nearest second antibacterial surface 120, and the average value of the distance D3 between a certain intermediate antibacterial surface 130 and the nearest intermediate antibacterial surface 130. The same is true. Note that the distance between the intermediate antibacterial surfaces 130 is the distance between the cross-sectional curves at the height of the threshold value 750 in FIG. The distance may be determined based on the virtual line intersecting each intermediate antibacterial surface 130, such as the distance between the cross-sectional curves at the height of the threshold value 740.

These measurements and calculations can be performed using, for example, VK-X250 manufactured by Keyence Corporation as a laser microscope and the multi-file analysis application VK-HIXM as analysis software.

The above-mentioned antibacterial region may be formed on the entire surface of the antibacterial molded article, or may be formed only in the region to which bacteria are likely to adhere. Furthermore, the above-mentioned antibacterial regions may be dispersed and arranged in a part of the region where bacteria are likely to adhere.

[Material and shape of antibacterial molded body]
The material of the antibacterial molded article is not particularly limited, and is appropriately selected depending on the use of the antibacterial molded article. As long as it has the above-mentioned antibacterial region, the same effect can be obtained regardless of the material of the antibacterial molded article. Here, the material of the antibacterial molded body may be, for example, an inorganic material such as a metal or a ceramic, an organic material such as a resin, or a composite thereof. Note that it is preferable that the surface does not contain an antibacterial agent or silver nanoparticles.

Examples of metals include stainless steel, aluminum, copper, silver, iron, titanium, and the like. Further, examples of ceramics include silicon carbide, lead zircolate titanate, and the like. On the other hand, the resin may be a thermoplastic resin or a thermosetting resin. Further, the resin may be a crystalline resin or a non-crystalline resin. Further, the resin may be rubber such as synthetic rubber and natural rubber.

Examples of the above resins include polyolefin resins such as polyethylene and polypropylene; cyclic olefin resins; polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polyvinylidene fluoride ( PVDF), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and other halogenated hydrocarbons; polyamide; polyimide; polyacetal (POM); polyurethane; ethylene-vinyl alcohol copolymer (EVOH); acrylic polymer; Ethylene-vinyl acetate copolymer (EVA); polylactic acid (PLA); polycaprolactone (PCL); polyglycolic acid (PGA); polystyrene (PS); polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and Polyesters such as butylene naphthalate (PBN); polyphenylene sulfide (PPS); polyether ether ketone (PEEK); acrylonitrile-styrene copolymer (AS); acrylonitrile-butadiene-styrene copolymer (ABS); polycarbonate ( PC); polyarylate (PAR); polyphenylene ether (PPE); polyphenol resin; epoxy resin; isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), ethylene- Rubbers such as propylene rubber (EPM); etc. are included.

Among the above, stainless steel, polycarbonate, and cyclic olefin resin are preferred from the viewpoint of processability, versatility, and the like. Polycarbonate and cyclic olefin resins are preferable because they can form a transparent film and provide a good appearance as a packaging material or a protective sheet for electronic devices.

Further, the shape of the antibacterial molded product is not particularly limited as long as it has the above-mentioned antibacterial region, and can be made into any shape depending on the use of the antibacterial molded product. Antibacterial molded bodies can be, for example, film-like, sheet-like, tube-like, ring-like, bulk-like (cubic, rectangular parallelepiped, cylindrical, spherical, etc.), plate-like, bag-like, or three types obtained by processing these. It can be made into a desired shape such as a dimensional three-dimensional structure.

[Applications of antibacterial molded bodies]
Applications of antibacterial molded bodies are not particularly limited, and include packaging materials, medical instruments, home appliances, building equipment, space suits, spacecraft interiors, electronic devices and their peripherals, automobile parts, agricultural supplies, stationery, and body accessories. It can be used for a wide range of purposes, including Note that the mode of use of the antibacterial molded article includes that the antibacterial molded article is an article used for these purposes, and that the antibacterial molded article is incorporated as a part of these articles. included.

Examples of packaging materials include films, sheets, boxes, cases, decorative items, and the like. Further, at this time, the antibacterial region of the antibacterial molded article may be placed on either the surface that contacts the packaged object or the surface that does not contact the packaged object. By using the above-mentioned antibacterial molded article in the packaging material, it is possible to prevent the growth of bacteria in the packaged article and improve its shelf life.

Among packaging materials, food packaging materials are required to have high antibacterial properties. Therefore, the antibacterial molded article is particularly suitable as a food packaging material, and in this case, it is preferable to arrange an antibacterial region on the surface that comes into contact with the food. As mentioned above, the antibacterial molded article is highly safe because it does not need to contain an antibacterial agent or silver nanoparticles. Furthermore, the antibacterial molded article kills bacteria by concentrating attractants released by bacteria. Therefore, it is more likely to be effective in an environment where a specific type of bacteria is present than in an environment where many types of bacteria are present. Therefore, for example, if the antibacterial molded article is used inside a food packaging material used to seal food, it becomes possible to suppress the growth of specific bacteria and extend the expiration date.

On the other hand, examples of medical devices include forceps, syringes, stents, artificial blood vessels, catheters, wound dressings, scaffolds for regenerative medicine, anti-adhesion materials, pacemakers, and the like. Particularly, among these, the antibacterial molded article is very useful as a member of an indwelling device such as a pacemaker. Normally, bacteria do not enter or leave a living body, but bacteria may enter the living body via surgical instruments or the like. On the other hand, by using the above-mentioned antibacterial molded body as a part of an indwelling device, it is possible to suppress the growth of bacteria in a living body.

Further, examples of the above-mentioned home appliances include rice cookers, microwave ovens, refrigerators, irons, hair dryers, air conditioners, filter parts of air cleaners, and the like.

Examples of the above building equipment include toilets and toilet seat sheets, vanities, water and sewage pipes, foot wiping mats, interior materials, bathtub handrails and exterior parts, bathtub bodies, bathtub covers, door handles, and handrails. It also includes items such as switches and other items that people touch on a daily basis.

The antibacterial molded article is also useful for spacesuits, spacecraft interiors, electronic equipment brought into spaceships, various devices, and the like. In outer space, the only bacteria that exist are things brought in from the ground or brought in through the human body. However, in outer space, the proliferation of bacteria poses a major risk because human immunity is weakened. Therefore, by using the above-mentioned antibacterial molded article in various members, the growth of bacteria can be effectively suppressed.

Examples of electronic devices and their peripherals include notebook computers, smartphones, tablets, digital cameras, medical electronic devices, POS systems, printers, televisions, mice and keyboards, and the like.

Examples of the above-mentioned automobile parts include a steering wheel, a seat, a shift lever, and various types of piping.

Examples of the above-mentioned agricultural products include spreading films for agricultural greenhouses and the like.

Examples of the body equipment include clothing including outerwear and underwear, hats, shoes, gloves, diapers, napkins and storage bags thereof, and the like.

Among the above, preferred are food packaging materials in which at least a portion of the surface in contact with food is the antibacterial region, or devices for indwelling in vivo, such as pacemakers.

[Method for producing antibacterial molded article]
The method for forming the above-mentioned antibacterial molded product is not particularly limited, and is appropriately selected depending on the material, purpose, shape, etc. of the antibacterial molded product.

For example, when forming the antibacterial region on the surface of an antibacterial molded article, recesses having a desired depth and opening area can be formed at desired intervals by laser processing or the like. At this time, for example, in the case of the shape shown in FIG. 2, by scanning the laser in the vertical direction to form a concave portion and then scanning in the horizontal direction to form a concave portion, both vertical and horizontal scanning can be performed. The area processed by the process is defined as the second antibacterial surface with the lowest height, the area processed by only one of the vertical scanning and the horizontal scanning is defined as the intermediate antibacterial surface, and the area not irradiated with the laser is defined as the second antibacterial surface. The first antibacterial surface may have the highest height. At this time, it is desirable to control the laser irradiation conditions so that the first antibacterial surface, the second antibacterial surface, and the intermediate antibacterial surface that satisfy the above-mentioned conditions are formed. Moreover, at this time, by changing the scanning direction of the laser, it is also possible to form an antibacterial region having a shape as shown in FIGS. 5 and 6.

Alternatively, the antibacterial region can be formed by molding a resin or metal using a mold that has a convex portion on the inner surface that is in the shape of the antibacterial region, or by additive modeling to form the antibacterial region. may be formed. On the other hand, an antibacterial region may be formed on the surface of a molded article according to the intended use by nanoimprinting, etching, or the like.

The antibacterial region may be formed on a coating layer such as a plating layer or film formed on the surface of the molded body, or a coating having the antibacterial region may be formed by a printing method such as an inkjet method. good.

Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited thereto.

1. Preparation of antibacterial molded body [Example 1]
The surface of a metal plate made of stainless steel (material) is irradiated with a laser by adjusting the irradiation conditions and number of irradiations so that it forms a shape with a width of 10 μm and a depth of 2 μm. The angle was 90°). The interval between each concave portion was 1.5 μm. Figure 1 shows a micrograph of the metal plate surface after laser irradiation. In addition, since the intensity of the laser is strong in the center and the number of irradiations required to form the recesses of the above depth is small, the edges irradiated with the laser are not processed sufficiently, and the spacing between the recesses is less than 1.5 μm. It is also wider. The obtained processed area is designated as antibacterial area 1.

[Example 2]
The surface of the metal plate was irradiated with a laser under the same conditions as in Example 1, except that the interval between the respective recesses was 5.0 μm, to form groove-shaped recesses in all directions. The obtained processed area is designated as antibacterial area 2.

[Comparative example 1]
The surface of the metal plate was irradiated with a laser under the same conditions as in Example 1 except that the width of each recess was 20 μm to form groove-shaped recesses in all directions. The obtained processed area is designated as antibacterial area 3.

2. Measurement of surface shape Antibacterial region 1 to antibacterial region 3 were observed using a laser microscope, and a height distribution spectrum indicating the distribution (frequency) of measurement points with respect to height was obtained. Three peaks were confirmed in the height distribution spectrum obtained from each antibacterial region (designated as peak 1, peak 2, and peak 3 in descending order). Assuming that the height distribution spectrum is a set of normal distributions corresponding to these three peaks, the intersection points of adjacent normal distributions are defined as thresholds (threshold 1 and threshold 2 in descending order). did. By determining the total area of regions higher than threshold 1 and dividing the obtained total area by the number of regions corresponding to peak 1, the average value of the surface area of the second antibacterial surface with the highest height is determined. Ta. Next, calculate the total area of the region higher than threshold 2, and subtract the total area of the region higher than threshold 1 from the obtained total area, and calculate the area corresponding to peak 2. The average surface area of the intermediate antibacterial surface was determined by dividing by the number of regions. Finally, from the surface area of the entire antibacterial area, divide the total area of areas higher than threshold 2 by the number of areas corresponding to peak 3, and calculate the area with the lowest height. The average value of the surface area of the first antibacterial surface was determined.

Furthermore, in the above height distribution spectrum, the difference in height between peak 1 and peak 2 in FIG. The difference from the mode of Further, the difference in height between peak 2 and peak 3 was determined, and was defined as the difference between the mode of the height distribution of the intermediate antibacterial surface and the mode of the height distribution of the first antibacterial surface.

Note that these measurements and calculations were performed using VK-X250 manufactured by Keyence Corporation as a laser microscope and a multi-file analysis application VK-HIXM as analysis software.

In addition, 10 profile lines arbitrarily set to include a certain first antibacterial surface and the first antibacterial surface closest to it were set in the antibacterial area measured by the laser microscope, and a cross-sectional curve obtained from each profile line was set. In the above, the distance between a certain first antibacterial surface and the first antibacterial surface closest to it was determined from the distance between these antibacterial surfaces at the height of the threshold value 1. The distance between one antibacterial surface was calculated for each profile line, and the average value of these was taken as the average value of the distance between a certain first antibacterial surface and the first antibacterial surface closest to it. .

In the antibacterial area measured by the laser microscope, 10 profile lines are arbitrarily set to include a certain second antibacterial surface and the second antibacterial surface closest to it, and in the cross-sectional curve obtained from each profile line, The distance between a certain second antibacterial surface and the second antibacterial surface closest to it was determined from the distance between these antibacterial surfaces at the height of the threshold value 2. The distance between one antibacterial surface was calculated for each profile line, and the average value of these was taken as the average value of the distance between a certain second antibacterial surface and the second antibacterial surface closest to it. .

Ten profile lines arbitrarily set to include a certain intermediate antibacterial surface and the nearest intermediate antibacterial surface are set in the antibacterial area measured by the laser microscope, and in the cross-sectional curve obtained from each profile line, a certain intermediate antibacterial surface is found. The distance between the antibacterial surface and the intermediate antibacterial surface closest to it was determined from the distance between these antibacterial surfaces at the threshold 1 or threshold 2 height. The distance between one antibacterial surface was calculated for each profile line, and the average value of these values was taken as the average value of the distance between a certain intermediate antibacterial surface and the closest intermediate antibacterial surface.

3. Evaluation of antibacterial activity The antibacterial activity of each antibacterial area against E. coli was evaluated according to the method described in JIS Z 2801 (2012). Specifically, the following E. coli bacteria were inoculated onto each antibacterial area and cultured for 24 hours under the following conditions. As a comparative sample, the surface of a sample whose surface was not processed was also inoculated with the following Escherichia coli and cultured for 24 hours under the following conditions.

(Bacterial species)
Escherichia coli, NBRC No. 3972
(Culture conditions)
Temperature: 35℃±1℃
(Measurement of viable bacteria count)
Medium used: Standard agar medium

Immediately after inoculation and 24 hours after inoculation, the number of viable bacteria was measured according to the method described in JIS Z 2801 (2012), and Δlog bacterial count (logarithm of the number of viable bacteria after 24 hours of the comparative sample - evaluation The logarithmic value of the number of viable bacteria after 24 hours for the sample was determined.

Table 1 shows the shape of each antibacterial region, and the evaluation results of Δlog bacterial count (antibacterial activity) and antibacterial properties. Those with high antibacterial properties (Δlog bacterial count of 2.0 or more) are marked as “○”, and those with insufficient antibacterial properties (Δlog bacterial count of less than 2.0) are marked with “×”.

As shown in Table 1, the average value of the surface area is 35.0 μm ² or more and 95.0 μm ² or less, and the difference in the mode of the height distribution is 1.70 μm or more and 10.0 μm or less. Good antibacterial activity was obtained in antibacterial region 1 and antibacterial region 2 forming the first antibacterial surface, intermediate antibacterial surface, and second antibacterial surface.

On the other hand, in antibacterial region 3, where the average value of the surface area of the first antibacterial surface was large, the antibacterial activity did not increase significantly. This is thought to be because bacteria were more likely to be scattered on the first antibacterial surface, and the concentration of the attractant was less likely to increase, making it easier for bacteria to proliferate.

According to the antibacterial molded article of the present invention, high antibacterial properties can be obtained. Furthermore, there is no need to use antibacterial agents, silver nanoparticles, etc., and it is also excellent in safety. Furthermore, there is no need to provide protrusions on the surface, and the antibacterial area is less likely to wear out. Therefore, since it exhibits high antibacterial properties over a long period of time, it can be applied to various uses such as food packaging materials and in-vivo indwelling devices.

100, 500, 600 Antibacterial area 110, 510, 610 First antibacterial surface 120, 520, 620 Second antibacterial surface 130, 530, 630 Intermediate antibacterial surface 400 Antibacterial area 410 First surface 420, 420a, 420b Second surface 710, 720, 730 peak 740, 750 threshold

Claims (10)

An antibacterial molded article having an antibacterial region formed by a combination of a plurality of independent antibacterial surfaces having different heights,
The plurality of antibacterial surfaces have a first antibacterial surface having the highest height, a second antibacterial surface having the lowest height, and a height intermediate between the height of the first antibacterial surface and the height of the second antibacterial surface. Contains an intermediate antibacterial surface,
The plurality of antibacterial surfaces each have an average value of the surface area of the first antibacterial surface, an average value of the surface area of the second antibacterial surface, and an average value of the surface area of the intermediate antibacterial surface of 35.0 μm ² or more and 95.0 μm ² or less. and the difference in the mode of the height distribution between the first antibacterial surface and the intermediate antibacterial surface, and the mode of the height distribution between the intermediate antibacterial surface and the second antibacterial surface. The difference in value is 1.70 μm or more and 10.0 μm or less,
Antibacterial molded body. The antibacterial molded article according to claim 1, wherein the first antibacterial surface is in contact with only the second antibacterial surface and the intermediate antibacterial surface on its outer periphery. The antibacterial molded article according to claim 1 or 2, wherein the second antibacterial surface is in contact with only the first antibacterial surface and the intermediate antibacterial surface on its outer periphery. The antibacterial molded article according to any one of claims 1 to 3, wherein the plurality of antibacterial surfaces are regularly arranged. The antibacterial molded article according to any one of claims 1 to 4, wherein the plurality of antibacterial surfaces are arranged in a grid pattern. The antibacterial device according to any one of claims 1 to 5, wherein the first antibacterial surface is disposed at a distance from the nearest other first antibacterial surface to 0.5 μm or more and 95 μm or less. sexual molded body. The antibacterial surface according to any one of claims 1 to 6, wherein the second antibacterial surface is disposed at a distance from the nearest other second antibacterial surface to 0.5 μm or more and 95 μm or less. sexual molded body. The antibacterial molded article according to any one of claims 1 to 7, which is a food packaging material. The antibacterial molded article according to any one of claims 1 to 8, which is a device for indwelling in a living body. Antibacterial properties, such as forming the antibacterial region of the antibacterial molded product according to claim 1 on the surface of the molded product, or molding a molded product having the antibacterial region of the antibacterial molded product according to claim 1 on its surface. Method for manufacturing a molded object.

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