Antibacterial molded body and its manufacturing method

Abstract

To provide an antibacterial molded article that can increase options for materials and shapes of the molded article.SOLUTION: An antibacterial molded article includes a plastic molded article, the plastic molded article being a molded composition including thermoplastic resin (excluding polyethylene), and also having a rough region with an arithmetic average roughness Ra of a roughness curve in accordance with JIS B 0601 (2013) being 0.14 μm or greater and 0.72 μm or less, provided on a bacteria-contactable surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an antibacterial molded article and a method for producing the same. [Background technology]

[0002] Due to the increasing awareness of consumers, many antibacterial products are available on the market. Most of the antibacterial products are coated with antibacterial agents or embedded with silver nanoparticles, but the former lose their antibacterial activity over time, and the latter have too high antibacterial activity, which limits the environment in which they can be used due to safety concerns for the living body.

[0003] In recent years, patent applications and papers have been submitted regarding a technique for forming a nano-order surface uneven structure on a surface and exerting antibacterial properties by physical puncturing. For example, Patent Document 1 and Patent Document 2 describe a method for forming a plurality of nano-sized protrusions on the surface of a resin composition to impart antibacterial properties to the surface. According to the methods described in these documents, it is believed that antibacterial properties are exerted by bacteria that come into contact with the protrusions being pierced by the protrusions and dying. With this mechanism, a high antibacterial effect can be expected even against multidrug-resistant bacteria, which have become a problem in recent years.

[0004] Specifically, Patent Document 1 describes an antibacterial article that exhibits antibacterial performance by making the spacing between the protrusions sufficiently smaller than the size of the bacteria to facilitate contact with cells, and by making the protrusions have a needle-like shape with a large aspect ratio that bacteria can penetrate. Patent Document 1 also describes that when the static contact angle of pure water on the surface of the antibacterial article is 30° or less, the surface becomes hydrophilic, making it easier for bacteria to penetrate the microprotrusions, thereby improving antibacterial properties. According to Patent Document 1, the antibacterial article can be produced by a method in which a base plate having a desired uneven shape is pressed against the surface of a liquid resin composition while the liquid resin composition is cured.

[0005] Patent Document 2 also describes a synthetic polymer film having a plurality of convex portions, the two-dimensional size of the plurality of convex portions being in the range of more than 20 nm and less than 500 nm when viewed from the normal direction of the synthetic polymer film. Patent Document 2 also describes that the contact angle of the surface of the synthetic polymer film with hexadecane is 51° or less, the bactericidal properties are good, but the contact angle of water (hydrophilicity) is not directly related to the bactericidal action. According to Patent Document 2, the synthetic polymer film can be produced by a method in which an anodized porous alumina layer is pressed against the surface of an ultraviolet curing resin using the layer as a mold, while the ultraviolet curing resin is cured.

[0006] Patent Document 3 describes an antibacterial and antifungal article in which a plurality of microprotrusions are arranged, the average distance between the microprotrusions being 1 μm or less, the height of the microprotrusions being 80 nm to 1000 nm, and the vicinity of the tip of the microprotrusions being thinner than the base. According to Patent Document 3, since the size of bacteria is generally 1 μm, by making the shape and arrangement of the microprotrusions as described above, bacteria and fungi come into contact with the tips of the microprotrusions without getting between the microprotrusions, and are killed by being pierced by the tips of the microprotrusions.

[0007] Patent Document 4 describes an antibacterial article having a plurality of microprotrusions arranged thereon, the microprotrusions having a height of 0.125 μm or more and an average distance between the microprotrusions being greater than 0.5 μm and less than 5.0 μm. According to Patent Document 4, by making the average distance between the microprotrusions greater than 0.5 μm and less than 5.0 μm, bacteria can be attached while being sterilized by piercing the microprotrusions, and the article is easy to manufacture. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2016-093939 A [Patent Document 2] JP 2016-120478 A [Patent Document 3] JP 2016-215622 A [Patent Document 4] JP 2017-132916 A Summary of the Invention [Problem to be solved by the invention]

[0009] As described in Patent Documents 1 to 4, a resin molded body having a plurality of nano-sized protrusions formed on the surface of a plastic molded body is less susceptible to a decrease in antibacterial properties due to peeling and falling off of the antibacterial agent compared to a resin molded body having an antibacterial agent applied to the surface of the molded body, and is therefore expected to be able to maintain antibacterial performance for a longer period of time.

[0010] However, in Patent Documents 1 to 4, the minute protrusions are formed by pressing the uneven surface of an original plate having a desired uneven shape against a coating of a resin composition while curing the resin composition. However, this method has problems in that antibacterial protrusions can only be formed on curable resins, so there are limitations on applicable materials and productivity is low.

[0011] The present invention has been made in consideration of the above problems, and has an object to provide an antibacterial molded body and a manufacturing method thereof that can expand the options for materials and shapes of the molded body. [Means for solving the problem]

[0012] An antibacterial molded body according to one embodiment of the present invention for solving the above-mentioned problems includes a plastic molded body, and the plastic molded body has a rough region on its surface with which bacteria can come into contact, the roughness curve of which has an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less, as defined in JIS B0601 (2013).

[0013] In addition, a manufacturing method for an antibacterial molded body according to another aspect of the present invention for solving the above problem includes a step of preparing a substrate having a plastic surface, and a step of performing a blast treatment on at least the plastic-containing surface of the substrate. Effect of the Invention

[0014] The present invention provides an antibacterial molded article and a method for producing the same that can expand the possibilities for selecting materials and shapes of the molded article. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1A is a photograph of the surface of Sample 1-1 in Example 1 taken with a scanning electron microscope (SEM), and FIG. 1B is a photograph of the cross section of Sample 1-1 taken with the SEM. [Diagram 2] FIG. 2A is a photograph of the surface of Sample 2-1 (LLDPE) in Example 2 taken with a scanning electron microscope (SEM), and FIG. 2B is a photograph of the cross section of Sample 2-1 (LLDPE) taken with an SEM. [Diagram 3] FIG. 3A is a photograph of the surface of Sample 2-3 (PVDF) in Example 2 taken with a scanning electron microscope (SEM), and FIG. 3B is a photograph of the cross section of Sample 2-3 (PVDF) taken with an SEM. [Figure 4] FIG. 4A is a photograph of the surface of Sample 2-4 (PVDC) in Example 2 taken with a scanning electron microscope (SEM), and FIG. 4B is a photograph of the cross section of Sample 2-4 (PVDC) taken with an SEM. [Diagram 5] FIG. 5A is a photograph of the surface of Sample 2-5 (PPS) in Example 2 taken with a scanning electron microscope (SEM), and FIG. 5B is a photograph of the cross section of Sample 2-5 (PPS) taken with an SEM. [Figure 6] FIG. 6A is a photograph of the surface of Sample 2-6 (PET) in Example 2 taken with a scanning electron microscope (SEM), and FIG. 6B is a photograph of the cross section of Sample 2-6 (PET) taken with an SEM. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] As a result of intensive research into the above-mentioned problems, the inventors have found that antibacterial properties are fully exhibited by using a plastic molded body having a rough area on its surface with which bacteria can come into contact, the rough area having an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less, and after further research, have completed the present invention.

[0017] [Antibacterial molded body] One embodiment of the present invention relates to an antibacterial molded body including a plastic molded body, the plastic molded body having a rough region on its surface with an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less.

[0018] The antibacterial molded body may include a plastic molded body having the rough region on its surface, and may be entirely made of the plastic molded body, may be a composite of the plastic molded body and another plastic molded body not having the rough region on its surface, or may be a composite of the plastic molded body and a metal or ceramic. Note that the "antibacterial molded body" is a molded body to which antibacterial properties have been imparted by the rough region, and the antibacterial molded body itself may be used for antibacterial purposes, or may be a molded body to which antibacterial properties have been imparted in addition to the original use of the antibacterial molded body.

[0019] The plastic molded body may be any molded body obtained by molding plastic into a predetermined or indefinite shape and imparting a shape. The shape of the plastic molded body is not particularly limited and can be selected as desired depending on the application of the antibacterial molded body. For example, the molded body may have a predetermined shape such as a film, sheet, tube, ring, bulk (e.g., cube, rectangular parallelepiped, cylinder, sphere, etc.), plate, bag, fiber, mesh, and a three-dimensional structure obtained by processing these, or may have an amorphous shape.

[0020] For example, when in the form of a film or sheet, the thickness of the plastic molded body is preferably 1 μm or more and 1000 μm or less, more preferably 3 μm or more and 800 μm or less, even more preferably 5 μm or more and 500 μm or less, and particularly preferably 10 μm or more and 300 μm or less.

[0021] By forming the above-mentioned rough region on the surface of a plastic molded body, the present invention has the advantages of enabling mass production by injection molding or the like, having a high degree of design freedom so that it can be processed into various shapes, being flexible so that it can be attached and applied to various shapes, and further enabling the antibacterial molded body to be made lighter than metal.

[0022] The rough region may be at least a part of the surface of the plastic molded body, but the entire surface of the plastic molded body may be the rough region. The rough region may be formed on all of the multiple surfaces of the plastic molded body having multiple surfaces such as a polyhedron, or may be formed on at least one surface (the entire surface, or a partial area included in the surface). Alternatively, the rough region may be formed on the entire one surface of the plastic molded body having one surface such as a sphere, or may be formed on a partial area included in the one surface.

[0023] The rough region is formed on a surface of the antibacterial molded body that can be contacted by bacteria. The surface that can be contacted by bacteria means a surface of the antibacterial molded body that may come into contact with external bacteria when the antibacterial molded body is in use, on standby, or during storage. For example, the rough region may be formed in a part that a user touches when using the antibacterial molded body. In addition, when there is a part that can be predicted to have a high chance of contact with bacteria, such as a part that is hit by a water flow or an air flow during use, or a part that can be predicted to come into contact with food, medicine, or a living body, the rough region may be formed at least in that part. When the plastic molded body has a shape such as a bag or a tube, the rough region may be formed on its inner surface. In addition, the rough region may not be exposed to the outside when not in use by sealing or a lid.

[0024] The rough region has an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less. When the Ra is 0.14 μm or more, a concave-convex shape of sufficient height (depth) is formed in the rough region, bacteria can be captured in the concaves of the concave-convex shape, and free movement and proliferation of bacteria can be suppressed, so that the rough region is considered to have sufficient antibacterial properties. On the other hand, when the Ra is 0.72 μm or less, the height of the concaves and convexities formed in the rough region is not too high, so that bacteria can be captured in both the convexities and concaves (both the oblique sides and bottoms of the concave-convex shape), and the area in which bacteria can be captured can be made larger, so that free movement and proliferation of bacteria can be more effectively suppressed. In addition, the convexities are less likely to wear during use, making it easier to maintain the antibacterial effect. In addition, the appearance of the molded product is good. From the above viewpoint, the Ra is preferably 0.14 μm or more and 0.70 μm or less, more preferably 0.20 μm or more and 0.60 μm or less, even more preferably 0.23 μm or more and 0.50 μm or less, and particularly preferably 0.25 μm or more and 0.35 μm or less.

[0025] In addition, the rough region preferably has an average length Rsm of the contour curve element of 1.0 μm or more and 50.0 μm or less. When the Rsm is 1.0 μm or more, the length of the recess between the convex portions is greater than the size of a single bacterium, and the rough region exhibits sufficient antibacterial properties. Although the mechanism of antibacterial properties is unclear, it is believed that bacteria are captured in the recess and their movement is inhibited, thereby inhibiting their proliferation. For example, Escherichia coli has a size of 0.5 μm×1.0 to 2.0 μm, and Staphylococcus aureus has a size of 0.5 μm×1.0 μm. From the viewpoint of more reliably inhibiting bacterial movement, the Rsm is preferably 5.0 μm or more. On the other hand, when the Rsm is 50.0 μm or less, the rough region has a sufficient number of recesses in a unit length (unit area), and the rough region exhibits sufficient antibacterial properties. From the above viewpoint, the Rsm is more preferably 10.0 μm or more and 33.0 μm or less, further preferably 13.0 μm or more and 32.0 μm or less, and particularly preferably 15.0 μm or more and 30.0 μm or less.

[0026] The rough region preferably has a large number of minute depressions. In a rough region having an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less and a large number of minute depressions, the size of the depressions is considered to be approximately the same as that of bacteria. The depressions are considered to be capable of capturing bacteria that come into contact with the rough region. The depressions are considered to inhibit the division of the captured bacteria, thereby inhibiting bacterial proliferation and reducing the number of bacteria. For example, the rough region can be formed regardless of the type of resin by changing the conditions of the blasting process described later according to the physical properties of the resin type.

[0027] In addition, the ratio of Ra to Rsm (Ra / Rsm) is preferably 0.004 or more and 0.720 or less. When Ra / Rsm is 0.004 or more and 0.720 or less, the inclination of each depression is moderate, so that bacteria can be captured by both the convex and concave parts (both the oblique side and the bottom part of the uneven shape), and the area for capturing bacteria can be increased, so that free movement and proliferation of bacteria can be more effectively suppressed. From the above viewpoint, Ra / Rsm is more preferably 0.005 or more and 0.500 or less, even more preferably 0.007 or more and 0.100 or less, particularly preferably 0.008 or more and 0.050 or less, particularly preferably 0.009 or more and 0.030 or less, and particularly preferably 0.010 or more and 0.025 or less.

[0028] In this specification, the arithmetic mean roughness Ra and the average length Rsm of the profile curve element are parameters defined in accordance with JIS B 0601 (2013). Specifically, first, the cross section of the substrate is imaged with a shape analysis laser microscope (Vk-X250). Then, the obtained image is processed to identify the open broken line tracing the surface. Then, the inclination and waviness are removed from the open broken line by a conventional method to obtain a roughness curve. The average value of the absolute values ​​for 10 μm at any position on the roughness curve is the arithmetic mean roughness Ra, and the average value of the length of the profile curve element is the average length Rsm of the profile curve element. The above Ra and Rsm can be values ​​measured using a shape analysis laser microscope (Vk-X250) manufactured by Keyence Corporation.

[0029] In addition, in this specification, the height of the microprotrusions can be a value measured by the following method. First, the non-closed side of the open bend line in the analysis result of the cross section of the substrate with a laser microscope is the bottom of the protrusion, and the side of the open bend line relative to the bottom is the protrusion. Then, among the triangles formed by connecting any one vertex on the open bend line of each protrusion and any two vertices on the open bend line on the bottom side, the height of the triangle with the greatest height from the side (called the base side) connecting the two vertices on the bottom side is the height of each protrusion.

[0030] The rough region has antibacterial properties against a wide variety of bacteria. For example, the rough region has antibacterial properties against at least one of Escherichia coli, Staphylococcus aureus, Lactobacillus, and Pseudomonas aeruginosa, and preferably has antibacterial properties against at least one of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, and has antibacterial properties against at least Escherichia coli and Staphylococcus aureus.

[0031] In this specification, antibacterial means both killing bacteria present in the medium and inactivating the bacteria to inhibit their growth. In addition, in this specification, having antibacterial properties means that the Δlog number of bacteria (logarithm of the number of live bacteria in the unprocessed sample after 24 hours - logarithm of the number of live bacteria in the evaluation sample whose surface is the rough region after 24 hours) is 0.2 or more, which is determined by inoculating bacteria and measuring the number of live bacteria immediately after inoculation and 24 hours after inoculation using a method similar to that described in JIS Z 2801 (2012). In addition, Δlog is more preferably 1.0 or more, even more preferably 2.0 or more, even more preferably 3.0 or more, and particularly preferably 4.0 or more.

[0032] The plastic molded body may be a molded body obtained by molding a composition (resin composition) containing a resin. The resin composition contains, for example, 30% by mass or more of the resin relative to the total mass of the resin. The resin composition may contain any additives for adjusting the properties of the antibacterial molded body depending on the application of the antibacterial molded body. Examples of the additives include known fillers, lubricants, plasticizers, ultraviolet stabilizers, coloring inhibitors, matting agents, deodorants, flame retardants, weather resistance agents, antistatic materials, antioxidants, colorants (dyes, pigments), and the like. These additives may be used in an optimal combination within a range that does not impair the effects of the present invention. Depending on the application or desire, organic substances (which may be other polymers) and inorganic substances such as metal nanoparticles may be used as other additives.

[0033] The type of the resin can be selected arbitrarily depending on the application of the antibacterial molded body. The resin may be a thermoplastic resin or a curable resin. The curable resin may be a thermosetting resin, a photocurable resin, or an electron beam curable resin. The resin may be a crystalline resin or a non-crystalline resin. The resin may be a rubber such as synthetic rubber or natural rubber. According to the findings of the present inventors, a plastic molded body containing a crystalline resin is easy to process, and compared with a plastic molded body containing a non-crystalline resin, the conditions of the blasting treatment described below are milder, and therefore it is easy to impart antibacterial properties. However, even if the plastic molded body contains a resin other than a crystalline resin, it is possible to impart sufficient antibacterial properties by appropriately adjusting the blasting conditions.

[0034] Examples of the resins include polyethylene (including linear low density polyethylene (LLDPE), low density polyethylene (LDPE), and high density polyethylene (HDPE)), polypropylene (including solid polypropylene (CPP), oriented polypropylene (OPP) such as uniaxially oriented polypropylene and biaxially oriented polypropylene), other polyolefin resins, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), non-aromatic polyamide (including nylon 6, nylon 66, nylon 12, and the like), non-aromatic polyimide, polyacetal (POM), polyurethane, ethylene-vinyl alcohol copolymer (EVOH), polyvinyl chloride (PVC), and acrylic polymers. Examples of such materials include ethylene-vinyl acetate copolymers (EVA), polylactic acid (PLA), polycaprolactone (PCL), and polyglycolic acid (PGA), polystyrene (PS), polyesters (including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN), etc.), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), semi-aromatic polyamides (including nylon 6T and nylon 9T, etc.), fully aromatic polyamides, semi-aromatic polyimides, fully aromatic polyimides, polystyrene (PS), acrylonitrile-styrene copolymers (AS), acrylonitrile-butadiene-styrene copolymers (ABS), polycarbonate (PC), polyarylate (PAR), polyphenylene ether (PPE), polyphenol resins, and epoxy resins.

[0035] Examples of the synthetic rubbers include isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), ethylene-propylene rubber (EPM), and other thermoplastic elastomers (including SEBS, SBS, and SEPS).

[0036] Among these resins, polyolefin resins, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyacetal (POM), acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC), polyethylene terephthalate (PET), polyurethane, ethylene-vinyl alcohol, etc. Preferred are ethylene-vinyl copolymer (EVOH), polyvinyl chloride (PVC), acrylic polymer, ethylene-vinyl acetate copolymer (EVA), polylactic acid (PLA), polycaprolactone (PCL), and polyglycolic acid (PGA), more preferred are polyethylene, polypropylene, polyvinylidene chloride, polyethylene terephthalate, and polyphenylene sulfide, further preferred are polyethylene, polypropylene, and polyvinylidene chloride, particularly preferred are polyethylene, and particularly preferred is LLDPE.

[0037] The antibacterial molded article can be used in a wide range of applications, including packaging, building equipment, home appliances, electronic devices and their peripherals, automotive parts, various coatings, medical instruments, agricultural supplies, stationery, and personal accessories, etc. The use of the antibacterial molded article includes the antibacterial molded article being an article used for these applications, and the antibacterial molded article being incorporated as a part of these articles.

[0038] For example, when used for the above-mentioned packaging applications, the antibacterial molding can form the above-mentioned rough area on the outer or inner surface of a film or sheet used to package an article, thereby preventing the intrusion of bacteria into the packaged article and improving the shelf life of the packaged article.

[0039] Examples of the facilities of the above buildings include toilets and toilet seats, washstands, water and sewage pipes, foot mats, interior materials, and items that are regularly touched by people's hands, such as door handles, handrails, and switches.

[0040] Examples of such home appliances include rice cookers, microwave ovens, refrigerators, irons, hair dryers, air conditioners, and air purifiers.

[0041] Examples of the above electronic devices and their peripherals include laptops, smartphones, tablets, digital cameras, medical electronic devices, POS systems, printers, televisions, mice and keyboards.

[0042] Examples of the above-mentioned automobile parts include steering wheels, seats, shift levers, and various pipes.

[0043] Examples of such packaging include packaging for medicines, food, and the like.

[0044] Examples of such coatings include coatings for walls, floors and ceilings of factories, operating rooms, storage facilities and shipping containers.

[0045] Examples of such medical devices include forceps, syringes, stents, artificial blood vessels, catheters, wound dressings, scaffolding materials for regenerative medicine, adhesion barriers, and pacemakers.

[0046] Examples of the agricultural products include expansion films for agricultural greenhouses.

[0047] Examples of the body accessories include clothing including outerwear and underwear, hats, shoes, gloves, diapers, napkins and storage bags thereof.

[0048] The antibacterial molded article can also be used to kill bacteria contained in building facilities, personal accessories, tableware, beverages, foodstuffs, etc. by contacting them with the objects.

[0049] [Method of manufacturing antibacterial molded body] The antibacterial molded body can be manufactured by a method including a step of mechanically processing the plastic-containing surface of a molded body substrate (hereinafter also simply referred to as "substrate") having a plastic surface, to make the surface into a rough area having the above-mentioned shape.

[0050] Specifically, a substrate on which a rough region is to be formed is first prepared. The material and shape of the plastic contained in the surface of the substrate are as described above for the plastic molded body.

[0051] The mechanical processing is applied to the area of ​​the surface of the substrate where a rough area should be formed on the plastic surface (area where antibacterial properties should be imparted). The mechanical processing is not particularly limited as long as it can impart the above-mentioned shape to the surface, but for example, the surface of the substrate may be ground by blasting and polishing with sandpaper and a grinder. The methods described in Patent Documents 1 to 4 are limited to applicable materials because they can form antibacterial protrusions only in curable resins, and the shape of the molded body to which antibacterial properties can be imparted is almost limited to a film shape. However, by forming a rough surface using these methods, a plastic molded body having a rough surface can be produced regardless of the material or shape. As an example of these mechanical processing, an example of blasting is shown below.

[0052] The blasting process may be performed by a known method of impacting an abrasive material biased by a compressed fluid against the plastic-containing surface of the substrate. In this case, the conditions of the blasting process may be changed according to the physical properties of the resin composition so that the rough region is formed. The abrasive material may be impacted against at least the plastic-containing surface of the substrate, but may also be impacted against a surface that partially contains a material other than plastic.

[0053] The compressed fluid may be a gas such as air, a liquid such as water, or a mixture of gas and liquid.

[0054] The injection pressure (processing pressure) of the compressed fluid may be selected, for example, in the range of 0.01 MPa to 5 MPa, preferably 0.03 MPa to 0.7 MPa, more preferably 0.05 MPa to 0.5 MPa.

[0055] The abrasive may be selected from abrasive grains made from known materials, including plants (such as seed pieces), metals (such as steel and stainless steel), ceramics (such as fused alumina, silicon carbide, and zircon), plastics (such as polyamides and melamine resins), sublimable solids such as dry ice, and other inorganic materials such as diamond and glass.

[0056] In this embodiment, the abrasive is preferably a particle containing the abrasive grains and an elastic body. The elastic body absorbs the impact when the abrasive collides with the surface of the substrate, making it easier to form the rough region of the above-mentioned shape. For example, the abrasive can be a particle in which the abrasive grains are dispersed inside or on the surface of an elastic body particle serving as a base material, or a particle in which the abrasive grains are attached or bonded to the surface of a resin particle serving as a base material. The abrasive generally has a particle size of 20 to 20,000 mesh, preferably 100 to 10,000 mesh.

[0057] The elastic body as the base material preferably has elasticity while having a relatively small impact resilience, and may be any of various rubbers, thermoplastic elastomers, and gels.

[0058] The rubber may be natural rubber or synthetic rubber, and examples of the synthetic rubber include isoprene rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, chloroprene rubber, ethylene propylene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, silicone rubber, epichlorohydrin rubber, and butyl rubber.

[0059] Examples of the thermoplastic elastomer include styrene block copolymers, chlorinated polyethylene-based elastomers, polyester-based elastomers, nitrile-based elastomers, fluorine-based elastomers, silicone-based elastomers, ester halogen-based polymer alloys, olefin-based elastomers, vinyl chloride-based elastomers, urethane-based elastomers, polyamide-based elastomers, and ester halogen-based polymer alloys.

[0060] Examples of such gels include mixtures of water and gelatin.

[0061] The above abrasive is preferably Sirius Media SIG080-7 manufactured by Fuji Manufacturing Co., Ltd. Sirius Media SIG080-7 is an abrasive in which green silicon carbide 8,000 mesh abrasive grains are bonded and aggregated with a synthetic rubber elastic body. A blasting process using a general single abrasive grain such as SiC forms a simple surface roughness by the collision of a single vector, but SIG080-7 makes it possible to form the desired surface by a phenomenon involving complex abrasion, in which a lateral vector is added to the surface due to deformation at the time of collision due to the effect of the elastic body.

[0062] The amount of the abrasive to be sprayed may be selected within the range of 0.1 kg / min to 10 kg / min, preferably 0.3 kg / min to 9 kg / min, and more preferably 0.5 kg / min to 8 kg / min.

[0063] The angle of the abrasive jet is preferably adjusted so that the abrasive impinges on the surface of the substrate from a direction closer to perpendicular to the substrate. The angle of the jet can be 20 degrees or more and 160 degrees or less, preferably 25 degrees or more and 165 degrees or less, and more preferably 30 degrees or more and 150 degrees or less, relative to the surface of the substrate.

[0064] The distance over which the abrasive is sprayed can be, for example, 10 mm or more and 700 mm or less, preferably 20 mm or more and 600 mm or less, and more preferably 30 mm or more and 500 mm or less, from the spray nozzle to the material to be blasted.

[0065] The processing time for blasting is, for example, 0.1 sec / cm 2 More than 20sec / cm 2 The processing time should be selected within the following range. 2 More than 15sec / cm 2 It is preferable to set the speed to 0.1 sec / cm or less. 2 More than 10sec / cm 2 It is more preferable to set it as follows:

[0066] In this embodiment, it is preferable to cool the surface of the substrate during the blasting process. When the substrate heats up due to the collision of the abrasive, the plastic on the blasted surface may deform, and the desired shape may not be obtained. In contrast, by performing cooling simultaneously with the blasting process, it is possible to easily obtain a rough region of the desired shape. In particular, when the substrate contains a thermoplastic resin as the plastic, deformation due to the heat generation is likely to occur, and therefore the effect of obtaining a surface having antibacterial properties by performing cooling is remarkable.

[0067] The cooling method is not particularly limited, and may be cooling by bringing water or a refrigerant into contact with the substrate surface, cooling by the surrounding air using dry ice or the like, or, when continuously blasting a thin substrate such as a film, cooling from the back side using a heat exchanger.

[0068] The blasting process can be carried out using a normal blasting device. Specifically, the sandblasting device "Pneumatic Blaster" SG type gravity type, FD type direct pressure type, and SC type fine powder abrasive type manufactured by Fuji Manufacturing Co., Ltd. can be used.

[0069] The conditions of the blasting treatment may be adjusted according to the type and various physical properties of the resin composition so that the rough region having the above-mentioned shape is formed.

[0070] The plastic molded body produced by the mechanical processing may be further molded or combined with other members. For example, the surface of a film-like or sheet-like molded body may be blasted to make the surface into the rough region, and then the molded body may be further molded into a bag-like or tubular shape, etc., to obtain a bag-like or tubular molded body having antibacterial properties on its inner surface.

[0071] The combination with the other member may be performed before or after the blast treatment. By combining the plastic molded body with the other member in this manner, a desired antibacterial article can be obtained.

[0072] [Antibacterial method] The antibacterial molded article can be used in various antibacterial methods.

[0073] Specifically, by contacting the antibacterial molded article with a liquid, solid, or gas containing bacteria, the bacteria contained in the contacted liquid, solid surface, or gas can be killed, and the liquid, solid, or gas can be sterilized. The contact is preferably performed on the rough area of ​​the antibacterial molded article.

[0074] The contact may be performed by a known method. For example, contact with a liquid may be performed by immersing the antibacterial molded body in a flowing or stationary liquid, by injecting or spraying the liquid onto the antibacterial molded body, or by applying or dripping the liquid onto the antibacterial molded body. Contact with a solid may be performed by abutting or pressing the stationary or sliding antibacterial molded body against the surface of the stationary or sliding solid. Contact with a gas may be performed by placing the antibacterial molded body in an atmosphere containing the flowing or stationary gas, or by injecting the gas onto the antibacterial molded body. EXAMPLES

[0075] Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these.

[0076] [Experiment 1] 1-1. Preparation of antibacterial articles 1-1-1. Preparation of the substrate The following substrate film was prepared as a substrate to which antibacterial properties were to be imparted. The substrate film had a square shape measuring 15 cm x 15 cm. Linear low-density polyethylene (LLDPE): Mitsui Chemicals Tocello Co., Ltd., TUS-TCS#60, thickness 53 μm

[0077] 1-1-2.Surface treatment The surface of the above-mentioned base film was blasted using blasting equipment FDDSR-4 or SGF-4 manufactured by Fuji Manufacturing Co., Ltd. An abrasive (SIG080-7 manufactured by Fuji Manufacturing Co., Ltd.) consisting of a resin matrix with abrasive grains dispersed therein was sprayed from a nozzle with a nozzle diameter of 6 mm against the base film, with a processing pressure of 0.1 MPa, a spray rate of 3 kg / min, a nozzle angle of 70 to 90 degrees, and a distance of 150 mm between the nozzle and the object to be blasted. The above-mentioned abrasive was sprayed while the base film was cooled by applying water. The processing time for the blasting treatment was 0.07 to 0.4 sec / cm 2 After the blasting treatment, the substrate film was washed and dried to obtain a film having fine projections and recesses.

[0078] The blasting conditions for each sample are shown in Table 1. Samples 1-1 to 1-4, which were subjected to the blasting treatment, were used as evaluation samples, and the samples which were not subjected to the blasting treatment were used as comparative samples.

[0079] [Table 1]

[0080] 1-2.Evaluation 1-2-1.Surface shape The arithmetic mean roughness Ra of the roughness curve defined in JIS B0601 (2013) and the average length Rsm of the roughness curve elements defined in JIS B0601 (2013) of each sample were determined under the following conditions. (Measuring equipment) Keyence Corporation, shape analysis laser microscope, VK-X250 (Measurement conditions) Laser wavelength: 658nm Output power: 0.95mW Pulse width: 1ns Measurement magnification: 50x Number of measurements: 11

[0081] When measuring Rsm, any height (depth) less than 10% of the maximum height or length less than 1% of the length of the calculation interval (10 μm) was regarded as noise and was considered to be part of the preceding or following peak or valley.

[0082] The surface and cross section of each evaluation sample were photographed with a scanning electron microscope (SEM). Figure 1 shows surface and cross section photographs of sample 1-1. Figure 1A is a surface photograph at a magnification of 10,000 times, and Figure 1B is a cross section photograph at a magnification of 30,000 times. As shown in Figure 1, many depressions were formed on the surface of the evaluation sample that had been subjected to the blast treatment.

[0083] 1-2-2. Antibacterial properties The antibacterial properties of each of the above samples against E. coli or S. aureus were evaluated. Specifically, similar to the method described in JIS Z 2801 (2012), the following E. coli or S. aureus were inoculated and cultured for 24 hours under the following conditions. Each evaluation sample was seeded so that E. coli or S. aureus would adhere to the rough area. (bacterial species) Escherichia coli, NBRC No. 3972 Staphylococcus aureus, NBRC No. 12732 (Culture conditions) Temperature: 35℃±1℃ (Measurement of viable bacteria count) Media used: Standard agar medium

[0084] Immediately after inoculation and 24 hours after inoculation, the viable cell count was measured according to the method described in JIS Z 2801 (2012), and the Δlog cell count (logarithmic value of viable cell count after 24 hours in the control (unprocessed) sample - logarithmic value of viable cell count after 24 hours in each evaluation sample) was calculated. If the Δlog for Escherichia coli or Staphylococcus aureus was 0.2 or higher, it was determined to have antibacterial properties.

[0085] Table 2 shows the viable cell count (expressed as a logarithmic value) and Δlog for each evaluation sample.

[0086] [Table 2]

[0087] As shown in Table 2, it was confirmed that the films (samples 1-1 to 1-4) having rough regions with an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less had antibacterial properties.

[0088] [Experiment 2] 2. Preparation of the substrate 2-1. Surface treatment of substrate Six types of substrate films were prepared, and the surfaces of each substrate film were subjected to a blasting treatment to prepare evaluation samples. For each substrate film, a comparative sample was also prepared that was not subjected to the surface treatment.

[0089] The substrate films used were as follows: All substrate films had a square shape of 50 mm x 50 mm. Linear low-density polyethylene (LLDPE): Mitsui Chemicals Tocello Co., Ltd., TUS-TCS#60, thickness 53 μm Non-oriented polypropylene (CPP): Toray Film Processing Co., Ltd., Torayfan ZK93FM, thickness 60 μm Polyvinylidene fluoride (PVDF): Made by Kureha Corporation, thickness 16 μm Polyvinylidene chloride (PVDC): Made by Kureha Corporation, thickness 40 μm Polyphenylene sulfide (PPS): Made by Kureha Corporation, thickness 50 μm Polyethylene terephthalate (PET): Toyobo Co., Ltd., Toyobo Ester Film E5000, thickness 75 μm

[0090] 2-1-2.Surface treatment Surface treatment (blasting, cleaning and drying) was carried out in the same manner as in Experiment 1.

[0091] The blasting conditions for each sample are shown in Table 3. Samples 2-1 to 2-6 that were subjected to the blasting treatment were used as evaluation samples, and samples that were not subjected to the blasting treatment for each film were used as comparison samples. Sample 2-1 was the same as Sample 1-1 in Experiment 1.

[0092] [Table 3]

[0093] 2. Surface profile measurement The surface profile was measured in the same manner as in Experiment 1.

[0094] The surface and cross section of each evaluation sample were photographed with a scanning electron microscope (SEM). Figures 2 to 6 show surface and cross section photographs of samples 2-1, 2-3 to 2-6 at a magnification of 3000 times. Figure 2A is a surface photograph of sample 2-1 (LLDPE), and Figure 2B is a cross section photograph of sample 2-1 (LLDPE). Figure 3A is a surface photograph of sample 2-3 (PVDF), and Figure 3B is a cross section photograph of sample 2-3 (PVDF). Figure 4A is a surface photograph of sample 2-4 (PVDC), and Figure 4B is a cross section photograph of sample 2-4 (PVDC). Figure 5A is a surface photograph of sample 2-5 (PPS), and Figure 5B is a cross section photograph of sample 2-5 (PPS). Figure 6A is a surface photograph of sample 2-6 (PET), and Figure 6B is a cross section photograph of sample 2-6 (PET).

[0095] 3. Antibacterial evaluation The antibacterial evaluation was carried out in the same manner as in Experiment 1.

[0096] Table 4 shows the surface roughness (arithmetic mean roughness Ra and average length of profile curve element Rsm) of each evaluation sample and comparative sample, as well as Δlog for the evaluation samples. Note that the results for LLDPE are the same as those for sample 1-1 and the comparative sample in Experiment 1.

[0097] [Table 4]

[0098] As shown in Table 4, the evaluation samples having a rough region with an arithmetic mean roughness Ra of 0.14 μm or more and 0.72 μm or less exhibited high antibacterial properties. In addition, the LLDPE having the above-mentioned rough region had particularly high antibacterial properties.

[0099] This application claims priority to Japanese Application No. 2019-184043, filed on October 4, 2019, and the contents of the claims, specification, and drawings of that application are incorporated herein by reference. [Industrial Applicability]

[0100] The antibacterial molded article of the present invention can be used in various applications where bactericidal and antibacterial actions are desired.

Claims

1. Including plastic moldings, The plastic molded body is formed by molding a composition containing a thermoplastic resin (excluding polyethylene), and has a rough region on a surface that can be contacted by bacteria, the roughness curve having an arithmetic mean roughness Ra of 0.18 μm or more and 0.32 μm or less, a mean length Rsm of a profile curve element defined in JIS B0601 (2013) of 24.1 μm or more and 35.8 μm or less, and a ratio (Ra / Rsm) of the arithmetic mean roughness Ra of the roughness curve defined in JIS B0601 (2013) to the mean length Rsm of the profile curve element defined in JIS B0601 (2013) of 0.0050 or more and 0.0124 or less, However, this does not include those containing 0.2 parts by weight or more of an inorganic antibacterial agent per 100 parts by weight of thermoplastic resin, and does not include those in which an inorganic compound containing silver with a particle size of 1 μm or less has penetrated and been fixed in the recesses. Antibacterial molded body.

2. The antibacterial molded article according to claim 1 , wherein the rough region is a region in which a large number of depressions are formed.

3. The plastic molded body is a molded body containing at least one resin selected from the group consisting of polyolefin resins (excluding polyethylene), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyacetal (POM), acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC), polyethylene terephthalate (PET), polyurethane, ethylene-vinyl alcohol copolymer (EVOH), polyvinyl chloride (PVC), acrylic polymer, ethylene-vinyl acetate copolymer (EVA), polylactic acid (PLA), polycaprolactone (PCL), and polyglycolic acid (PGA). The antibacterial molded body according to claim 1 or 2.

4. The antibacterial molded body according to any one of claims 1 to 3, wherein the plastic molded body is a molded body containing at least one resin selected from the group consisting of polypropylene, polyvinylidene chloride, polyethylene terephthalate, and polyphenylene sulfide.

5. The antibacterial molded article according to any one of claims 1 to 4, which is used for packaging, building facilities, home appliances, electronic devices or peripheral devices thereof, automobile parts, various coatings, medical instruments, agricultural supplies, stationery, or personal accessories.

6. The antibacterial molded article according to any one of claims 1 to 5, which is a forceps, a syringe, a stent, an artificial blood vessel, a catheter, a wound dressing, a scaffolding material for regenerative medicine, an adhesion inhibitor, or a pacemaker.

7. Providing a substrate having a surface including a composition including a thermoplastic resin (excluding polyethylene); and performing a blasting process on at least the surface of the substrate, the surface containing the thermoplastic resin, to form a rough region having an arithmetic mean roughness Ra of a roughness curve defined in JIS B0601 (2013) of 0.18 μm or more and 0.32 μm or less, an average length Rsm of a profile curve element defined in JIS B0601 (2013) of 24.1 μm or more and 35.8 μm or less, and a ratio (Ra / Rsm) of the arithmetic mean roughness Ra of the roughness curve defined in JIS B0601 (2013) to the average length Rsm of a profile curve element defined in JIS B0601 (2013) of 0.0050 or more and 0.0124 or less. A method for producing an antibacterial molded article.

8. The step of performing the blast treatment includes: A step of colliding an abrasive material, which is biased by a compressed fluid, with the thermoplastic resin-containing surface of the substrate while cooling the substrate. A method for producing the antibacterial molded article according to claim 7.

9. The method for producing an antibacterial molded article according to claim 8 , wherein the abrasive material comprises abrasive grains and an elastomer.

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