JP7205022B2 - RESIN MOLDED PRODUCT, RESIN MOLDED PRODUCT MANUFACTURING METHOD, AND STERILIZATION METHOD - Google Patents

Description

The present invention relates to a resin molded article, a method for producing a resin molded article, and a sterilization method.

A method for imparting antibacterial properties to the surface by processing the surface of a resin composition molded body is known.

For example, Patent Documents 1 to 3 describe a method of 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 the antibacterial properties are exerted by the bacteria coming into contact with the projections sticking to the projections and being killed.

Specifically, in Patent Document 1, the distance between the protrusions is made sufficiently small compared to the size of bacteria to facilitate contact with cells, and the protrusions have a large aspect ratio and can be pierced by bacteria. It describes an antibacterial article that exhibits antibacterial performance by forming it into a square shape. In addition, in Patent Document 1, when the static contact angle of pure water on the surface of the antibacterial article is 30 ° or less, the surface becomes hydrophilic, and bacteria easily stick into the microprojections. is stated to improve. According to Patent Document 1, the antibacterial article is produced by a method of curing the liquid resin composition while pressing an original plate having a desired uneven shape against the surface of the liquid resin composition. can be done.

In addition, US Pat. No. 6,200,000 describes a synthetic germicidal surface, such as black silicon, in which an array of nanospikes having a height of about 100 nm to about 600 nm are formed. According to Patent Document 2, the nanospikes are lethal to cells because they perforate cell membranes. According to Patent Document 2, the array of nanospikes can be made by a method such as reactive ion beam etching.

Further, Patent Document 3 discloses a synthetic polymer film having a plurality of convex portions, wherein the two-dimensional size of the plurality of convex portions is 20 nm when viewed from the normal direction of the synthetic polymer film. Synthetic polymer membranes have been described that range from >500 nm. In Patent Document 3, when the contact angle to hexadecane on the surface of the synthetic polymer film is 51° or less, the bactericidal property is good, but the contact angle of water (hydrophilicity) directly affects the bactericidal action. stated to be unrelated. According to Patent Document 3, the synthetic polymer film can be produced by a method of curing the ultraviolet curable resin while pressing an anodized porous alumina layer as a mold against the surface of the ultraviolet curable resin.

In addition, in Patent Document 4, the surface of tetrafluoroethylene/hexafluoropropylene copolymer (FEP) is irradiated with an atomic oxygen beam obtained by a laser detonation method (the maximum irradiation dose is 6.0 × 10 ¹⁹ atoms/cm ² ), an uneven structure with a height of about 10 nm is formed, thereby imparting cell adhesiveness to the surface. Patent Document 4 describes that when the surface of low-density polyethylene (LDPE) was irradiated with an atomic oxygen beam under the same conditions, a similar uneven structure was not formed and no change in cell adhesiveness was observed. there is In addition, the inventor of Patent Document 4 set the energy of the laser in the laser detonation method to 5 J/pulse to 7 J/pulse, and set the number of repetitions per second (pulse rate) of the laser to about 1 Hz, and conducted experiments. It is known (Non-Patent Document 1 and Non-Patent Document 2).

JP 2016-093939 A Japanese Patent Publication No. 2017-503554 JP 2016-120478 A Japanese Patent Application Laid-Open No. 2005-036106

Tagawa et al., "Synchrotron Radiation Photoelectron Emission Study of SiO2 Film Formed by Hyperthermal O-Atom Beam at Room Temperature," Japanese Journal of Applied Physics, 2005, Vol. 44, No. 12, pp.8300-8304 Tagawa et al., "Atomic Beam-Induced Fluorination of Polyimide and its Application to Site-Selective Cu Metallization," Langmuir, 2007, Vol. 23, pp.11351-11354

As described in Patent Documents 1 to 3, a resin molded product obtained by forming a plurality of nano-sized protrusions on the surface of a molded product of a resin composition is a resin obtained by applying an antibacterial agent to the surface of the molded product. It is expected that the antibacterial performance can be maintained for a longer period of time because the antibacterial properties are less likely to deteriorate due to peeling and falling off of the antibacterial agent compared to molded articles. However, the methods described in Patent Document 1 and Patent Document 3 can only form projections having antibacterial properties on curable resins, so there is a limit to the materials that can be applied, and antibacterial properties can be imparted. The shape of the molded body was almost limited to a film shape. In addition, Patent Document 2 does not describe a method for producing the nanospike array other than black silicon produced by reactive ion beam etching. Black silicon is hard, brittle, and has low shape workability, which limits its use and makes it difficult to apply it to sterilization treatment in various situations.

The present invention has been made in view of the above problems, and is a resin molded article having an antibacterial surface imparted with an antibacterial property, and a method for producing the resin molded article, which can expand the possibilities of selecting the material and the shape of the molded article. and to provide a sterilization method using the resin molding.

A molded product of a resin composition according to one aspect of the present invention for solving the above problems has, on its surface, a region imparted with antibacterial properties by irradiation with an atomic oxygen beam.

In addition, a method for producing a resin molded article having a surface imparted with antibacterial properties according to another aspect of the present invention for solving the above problems includes the steps of preparing a molded article of a resin composition, and an atomic oxygen beam. and a step of imparting antibacterial properties to the surface of the molded article by irradiation.

In addition, a sterilization method related to another aspect of the present invention for solving the above problems is a step of preparing the resin molded body, a step of contacting the resin molded body with a liquid, solid or gas containing bacteria, including.

INDUSTRIAL APPLICABILITY According to the present invention, a resin molded article having an antibacterial property on its surface, which can expand the possibility of selecting the material and the shape of the molded article, a method for producing the resin molded article, and sterilization using the resin molded article A method is provided.

FIG. 1A is a schematic side view showing a projection having an inwardly recessed inclined surface, which a molded body of a resin composition according to an embodiment of the present invention has, and FIG. FIG. 11 is a schematic side view showing a projection having a sloping surface that is convex toward the surface; FIG. 2A is a graph obtained by plotting Δlog for each bacterial species on the horizontal axis and the contact angle with pure water on the vertical axis for each evaluation sample and comparative sample in the example, and FIG. 2B. 2C is a graph obtained by plotting the Δlog for each bacterial species on the horizontal axis and the contact angle with diiodomethane on the vertical axis for each evaluation sample and comparative sample in the example. is a graph obtained by plotting Δlog for each bacterial strain on the horizontal axis and the contact angle with n-hexadecane on the vertical axis for each evaluation sample and comparison sample. FIG. 3A shows the total value (A + B) of the value of the dispersion component (A) and the value of the hydrogen bond component (B), with the horizontal axis representing Δlog for each bacterial species for each evaluation sample and comparative sample in the example. is a graph obtained by plotting on the vertical axis, and FIG. 3B shows Δlog for each bacterial species of each evaluation sample and comparative sample in the example on the horizontal axis, with respect to the value of the variance component (A) Fig. 3C is a graph obtained by plotting the ratio (B/A) of the value of the hydrogen bonding component (B) on the vertical axis, and Fig. 3C shows each bacterial species of each evaluation sample and comparison sample in Examples. is a graph obtained by plotting Δlog against the horizontal axis and the ratio of the value of the hydrogen bond component (B) to the total value (B/(A+B)) on the vertical axis. FIG. 4A shows the total value (A + C) of the value of the dispersion component (A) and the value of the polar component (C) on the horizontal axis of Δlog for each bacterial species of each evaluation sample and comparison sample in the example. It is a graph obtained by plotting on the vertical axis, and FIG. 4B shows Δlog for each bacterial species of each evaluation sample and comparative sample in the example on the horizontal axis, and the polarity with respect to the value of the dispersion component (A). It is a graph obtained by plotting the ratio (C / A) of the value of component (C) on the vertical axis, and FIG. is plotted on the horizontal axis and the ratio of the value of the polar component (C) to the total value (C/(A+C)) on the vertical axis.

As a result of intensive studies on the above problems, the present inventors have developed a method for imparting antibacterial properties to the surface of a resin composition molded article by irradiating the surface with an atomic oxygen beam. According to this method, antibacterial properties can be imparted to molded articles of resin compositions containing a wide variety of resins. In addition, according to the method, the surface of the molded body is irradiated with an atomic oxygen beam after the molded body having the desired shape is produced, so that the method can be applied to molded bodies having various shapes.

[Resin molded article having an antibacterial surface]
One embodiment of the present invention relates to a molded article of a resin composition, the resin molded article having, on its surface, a region imparted with antibacterial properties by irradiation with an atomic oxygen beam.

The antibacterial-imparted region has a plurality of nano-sized protrusions formed by irradiation with an atomic oxygen beam. The plurality of projections protrude in a direction substantially perpendicular to the surface, and it is thought that the projections pierce bacteria that come into contact with the region, thereby killing the bacteria.

In the present embodiment, the plurality of protrusions have slopes that are recessed toward the inside of the protrusions. FIG. 1A is a schematic side view showing a projection having an inwardly concave slope, and FIG. 1B is a schematic side view showing a projection having an outwardly convex slope. It is a diagram. At this time, it is preferable that eight or more of the arbitrarily selected ten protrusions have a shape such that the width of the protrusion monotonically decreases in the height direction. According to the findings of the present inventors, when the plurality of projections have slopes that are recessed toward the inside (see FIG. 1A), the plurality of protrusions have slopes that are convex toward the outside. The antibacterial properties of the resin molding are remarkably enhanced as compared with the case of having (see FIG. 1B). This is presumably because the plurality of protrusions are sharper and more needle-like, making it easier for the protrusions to pierce the bacteria coming into contact with the region to which the antibacterial property has been imparted.

It should be noted that simply irradiating the surface of a molded article of a resin composition with an atomic oxygen beam does not provide sufficient antibacterial properties, or rather provides cell adhesiveness as described in Patent Document 4. Sometimes I feel relaxed. Therefore, it is considered necessary to appropriately set the irradiation conditions of the atomic oxygen beam in order to impart sufficient antibacterial properties to the surface of the molded body of the resin composition.

The shape of the protrusion can be determined based on the protrusion curvature index calculated by the following method.

(Calculation method of projection curvature index)
A cross section of each evaluation sample is imaged with a scanning electron microscope (SEM), and 10 protrusion shapes are arbitrarily selected from the obtained SEM image. The two oblique sides (total of 20) forming the selected protrusion shape are converted into actual size XY coordinate data converted as 0.0099 μm per pixel. For one oblique side, out of the converted XY coordinate data, data for 5 pixels in the X axis direction is extracted as one group, and a two-dimensional polynomial least squares approximation formula (ax ² +bx + c of formula) and find the value of a in the formula. This calculation is shifted by one pixel with respect to the X coordinate, and the value of a is calculated for all the coordinate data of the slope. The average value of all the obtained values of a is determined and taken as the hypotenuse average value. Similarly, the average value of the oblique sides is calculated for all 20 oblique sides, and the average value of the 20 calculated average values of the oblique sides is used as the projection curvature index for the evaluation sample.

When the projection curvature index is a positive value, the projections included in the evaluation sample have slopes that are recessed toward the inside of the projection (see FIG. 1A). When the projection curvature index is a negative value, the projection included in the evaluation sample has an outwardly convex slope. The projection curvature index may be any positive value, but is preferably 2.00 or more, more preferably 3.00 or more, and even more preferably 3.50 or more. If the projection curvature index is 2.00 or more, the projections will probably more easily pierce bacteria, so that the antibacterial properties can be further enhanced. Although the upper limit of the projection curvature index is not particularly limited, it is considered that the effect reaches a plateau when it exceeds a certain numerical value, so it can be set to 6.00, for example.

Although the average height of the plurality of projections is not particularly limited, it is preferably 100 nm or more, more preferably 200 nm or more, and even more preferably 400 nm or more. When the average height is 200 nm or more, it is considered that the protrusions are more likely to pierce bacteria coming into contact with the region to which the antibacterial property is imparted, thereby further enhancing the antibacterial property. Although the upper limit of the average height of the projections is not particularly limited, it is considered that the effect reaches a plateau when it exceeds a certain value, so it can be set to 1700 nm, for example.

The average width of the protrusions included in the plurality of protrusions is not particularly limited, but is preferably 80 nm or more and 400 nm or less, more preferably 130 nm or more and 400 nm or less. When the average width of the projections is 130 nm or more and 400 nm or less, the projections probably more easily pierce the bacteria coming into contact with the region to which the antibacterial property is imparted, and thus the antibacterial property is further enhanced.

The average value of the distance between protrusions included in the plurality of protrusions is not particularly limited, but is preferably 220 nm or more and 770 nm or less, more preferably 350 nm or more and 770 nm or less. When the average distance between the protrusions is 350 nm or more and 770 nm or less, the protrusions probably more easily pierce the bacteria coming into contact with the region to which the antibacterial property is imparted, so that the antibacterial property is further enhanced.

The average height of the protrusions, the average width of the protrusions, and the average spacing between protrusions are obtained by SEM image analysis obtained by imaging the cross section of the evaluation sample with an SEM, and measuring the surface with a confocal laser microscope. It can be a value measured by analysis of the obtained cross-sectional curve. Specifically, draw an open fold line outlining the protrusion, either visually or by some automated means. When the non-closed side of the fold line is the bottom of the projection and the side of the fold line with respect to the bottom is the protrusion, any one vertex on the fold line at the protrusion of a certain protrusion and any two vertices on the fold line at the bottom side Among the triangles formed by connecting Defined as the protrusion width of the protrusion. The distance between protrusions is defined as the distance between the vertices of the protrusions in the triangles having the highest heights formed as described above for each of the adjacent protrusions. The arithmetic mean of the protrusion heights of all the analyzed protrusions is defined as the average height of the protrusions, the arithmetic mean of the protrusion widths is defined as the average value of the protrusion widths, and the arithmetic mean of the protrusion spacing is defined as the average value of the spacing between protrusions. .

The region imparted with antibacterial properties has antibacterial properties against a wide variety of bacteria. For example, the region has antibacterial properties against at least one of Escherichia coli, Staphylococcus aureus, lactic acid bacteria, and Pseudomonas aeruginosa, preferably against at least one of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. have sex.

In this specification, sterilization means both killing bacteria present in the medium and inactivating bacteria to suppress their growth. In addition, in this specification, having antibacterial properties means inoculating bacteria and measuring the number of viable bacteria immediately after inoculation and 24 hours after inoculation according to the method described in JIS Z 2801 (2012). Δlog number of bacteria (logarithmic number of viable bacteria after 24 hours of sample not irradiated with atomic oxygen beam-logarithmic number of viable bacteria after 24 hours of evaluation sample irradiated with atomic oxygen beam) is 2 .0 or more.

The resin composition may be any composition containing a resin. For example, the resin content of the resin composition is 20% by mass or more with respect to the total mass. The resin composition may optionally contain an additive for adjusting the properties according to the application of the resin molding. Examples of the above additives include known fillers (fillers), lubricants, plasticizers, UV stabilizers, anti-coloring agents, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, antioxidants, agents, colorants (dyes, pigments), and the like. An optimum combination of these additives may be selected and used as long as the effects of the present invention are not impaired. In addition, organic substances (other polymers may be used) and inorganic substances such as metal nanoparticles may be used as other additives depending on the application and desires.

The type of the resin can be arbitrarily selected according to the use of the resin molding. The resin may be a thermoplastic resin or a thermosetting resin. Further, the resin may be a crystalline resin or an amorphous resin. Further, the resin may be rubber such as synthetic rubber and natural rubber. According to the findings of the present inventors, a molded article of a resin composition having a non-aromatic resin having no aromatic ring in the repeating unit constituting the resin has an aromatic ring in the repeating unit constituting the resin. It is easier to impart antibacterial properties than a molded article of a resin composition containing an aromatic resin containing. However, even a molded body of a resin composition containing an aromatic resin can be given sufficient antibacterial properties by appropriately adjusting the irradiation conditions of the atomic oxygen beam.

Examples of the non-aromatic resin include polyethylene (including linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high-density polyethylene (HDPE)), polypropylene, and other polyolefin-based Resin, polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), non-aromatic polyamide (nylon 6, nylon 66 and nylon 12, etc.), non-aromatic polyimide, polyacetal (POM), polyurethane, ethylene-vinyl alcohol copolymer (EVOH), polyvinyl chloride (PVC), acrylic polymer, ethylene-vinyl acetate copolymer Polymer (EVA), polylactic acid (PLA), polycaprolactone (PCL), polyglycolic acid (PGA), and the like.

Examples of the aromatic resins include polystyrene (PS), polyester (including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN)), polyphenylene sulfide (PPS). , polyether ether ketone (PEEK), semi-aromatic polyamide, wholly aromatic polyamide, semi-aromatic polyimide, wholly aromatic polyimide, polystyrene (PS), acrylonitrile-styrene copolymer (AS), acrylonitrile-butadiene Styrene copolymer (ABS), polycarbonate (PC), polyarylate (PAR), polyphenylene ether (PPE), polyphenolic resin, aromatic epoxy resin and the like are included.

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

The molded article is obtained by molding the resin composition into a two-dimensional or three-dimensional shape and imparting a shape. The shape of the molded article is not particularly limited, and can be arbitrarily selected according to the use of the resin molded article. For example, the molded body can have a film-like, sheet-like, plate-like, bag-like, tubular, fibrous, mesh-like, predetermined shape, amorphous solid body shape, or the like.

It is sufficient that at least part of the surface of these moldings is imparted with antibacterial properties by irradiation with an atomic oxygen beam, but the entire surface is imparted with antibacterial properties by irradiation with an atomic oxygen beam. may be If it is possible to predict which parts may come into contact with bacteria during use, or which parts may come into contact with foods, medicines, or living organisms, at least those parts should be given antibacterial properties. These moldings may have an antibacterial property imparted to their outer surface, or may have an antibacterial property imparted to their inner surface when they have a bag-like or tubular shape.

The above resin moldings 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 devices, agricultural supplies, stationery and body accessories. be.

Examples of facilities in the above buildings include toilets and toilet seats, washstands, water and sewage pipes, foot wiping mats, interior materials, and handles such as doors, handrails, and switches that people touch on a daily basis. This includes items.

Examples of the home appliances include rice cookers, microwave ovens, refrigerators, irons, hair dryers, air conditioners and air purifiers.

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

Examples of the automotive parts include steering wheels, seats, shift levers and various types of piping.

Examples of such packaging include packaging for pharmaceuticals, foods, and the like.

Examples of such coatings include wall, floor and ceiling coatings for factories, operating rooms, storage and shipping containers, and the like.

Examples of such medical devices include forceps, syringes, stents, artificial blood vessels, catheters, wound dressings, scaffolds for regenerative medicine, and anti-adhesion materials.

Examples of the agricultural products include spread films for agricultural greenhouses.

Examples of the body accessories include clothes including outerwear and underwear, hats, shoes, gloves, diapers, napkins and their storage bags, and the like.

In addition, the above-mentioned resin molding can be used for sterilizing bacteria contained in building equipment, body accessories, tableware, beverages, foodstuffs, etc. by contacting them.

[Method for producing a resin molding having an antibacterial surface]
The resin molded article having the antibacterial surface can be formed by irradiating the molded article of the resin composition with an atomic oxygen beam.

Specifically, first, a molded body of a resin composition whose surface is to be imparted with antibacterial properties is prepared. The type of the resin composition and the shape of the molded article are as described above.

Irradiation of the atomic oxygen beam is carried out on a region of the surface of the molded article to be imparted with antibacterial properties.

Atomic oxygen beams can be generated by known methods such as gas dynamic expansion, ion neutralization, electron stimulated desorption (ESD), and laser detonation. Among these, the laser detonation method is preferable because it can efficiently generate an atomic oxygen beam with high kinetic energy.

In the laser detonation method, both oxygen molecular gas and laser (particularly CO ₂ laser) are emitted in pulses, and the oxygen molecular gas is plasmatized by irradiating the oxygen molecular gas with the laser. When the plasma is further irradiated with the laser to generate a bombardment wave (detonation), the thermal energy of the plasma is converted into kinetic energy, and at the same time the ions and electrons in the plasma recombine to form a beam of atomic oxygen. occurs.

The energy of the introduced laser is preferably 8 J/pulse or more, more preferably 10 J/pulse or more. When the energy of the laser is 8 J/pulse or more, antibacterial properties can be efficiently imparted to molded articles of a wide variety of resin compositions. Although the upper limit of the laser energy is not particularly limited, it is more preferably 20 J/pulse or less.

The number of repetitions per second (pulse rate) of the introduced laser is preferably 5 Hz or more, more preferably 12 Hz or more. When the pulse rate of the laser is 12 Hz or more, antibacterial properties can be efficiently imparted to molded articles of a wide variety of resin compositions. Although the upper limit of the pulse rate of the laser is not particularly limited, it is more preferably 20 Hz or less.

The translational energy of the atomic oxygen beam is preferably 1 eV or more and 20 eV or less, preferably 2 eV or more and 15 eV or less, and more preferably 3 eV or more and 10 eV or less.

The speed of the atomic oxygen beam is preferably 5 km/s or more and 13 km/s or less, more preferably 6 km/s or more and 10 km/s or less.

The cumulative irradiation dose of the atomic oxygen beam is preferably 1.0×10 ¹⁷ atoms/cm ² or more, more preferably 1.0×10 ¹⁹ atoms/cm ² or more, and 1.0× It is more preferably 10 ²⁰ atoms/cm ² or more. In particular, when the cumulative irradiation dose is 1.0×10 ²⁰ atoms/cm ² or more, antibacterial properties can be efficiently imparted to a wide variety of resin moldings. Although the upper limit of the cumulative irradiation dose is not particularly limited, it can be 1.0×10 ²² atoms/cm ² or less.

The irradiation time of the atomic oxygen beam is not particularly limited, but is preferably 2 hours or longer, more preferably 5 hours or longer, further preferably 8 hours or longer, and 10 hours or longer. I especially like it. The upper limit of the irradiation time is not particularly limited, but since the effect seems to reach a plateau after a certain time, it can be set to 30 hours, for example.

Irradiation conditions for these atomic oxygen beams may be adjusted to conditions that impart antibacterial properties according to the type and various physical properties of the resin composition. For example, the irradiation conditions of these atomic oxygen beams are determined by referring to a correspondence table showing the relationship between the type of resin composition and the irradiation conditions of the atomic oxygen beams. can decide. Alternatively, the irradiation conditions of these atomic oxygen beams are determined by calculating the relationship between the type of resin composition and the irradiation conditions of the atomic oxygen beams in a processing apparatus that has undergone machine learning or the like. be able to.

The resin molding may be further molded after being imparted with antibacterial properties by irradiation with an atomic oxygen beam. For example, after irradiating the surface of a film-like or sheet-like molded article with an atomic oxygen beam to impart antibacterial properties to the surface, the inner surface of the formed article is given antibacterial properties by further forming it into a bag-like or tubular shape. It can be a molded body such as a bag-shaped or tubular shaped body.

[Sterilization method]
The resin molding having the antibacterial surface can be used in various sterilization methods.

Specifically, the resin molding is brought into contact with a liquid, solid, or gas containing bacteria to kill the bacteria contained in the contacted liquid, solid surface, or gas, and remove the liquid, solid, or gas. Can be sterilized.

The contact may be performed by a known method. For example, contact with a liquid includes immersion of the resin molded body in the liquid that is flowing or stationary, injection or spraying of the liquid onto the resin molded body, and application or dripping of the liquid onto the resin molded body. It can be performed by a method such as Further, the contact with the solid can be carried out by a method such as contacting or pressing the stationary or sliding resin molded body against the surface of the stationary or sliding solid. Further, the contact with the gas can be carried out by a method such as placing the resin molding in an atmosphere containing the flowing or stationary gas, or injecting the gas into the resin molding.

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

1. Surface Treatment of Molded Body of Resin Composition Five types of base films were prepared, and the surface of each base film was irradiated with an atomic oxygen beam under the following conditions to prepare samples for evaluation. For each base film, a comparative sample was also prepared in which the atomic oxygen beam was not irradiated.
(Device)
Atomic oxygen irradiation device: PSI, FAST-II (laser detonation method)
Laser irradiation device: IR-SP manufactured by Usho Co., Ltd.
Laser type: _CO2 laser Laser wavelength: 10.6 μm
(Irradiation conditions of atomic oxygen beam)
Average oxygen content: approximately 120 sccm/12 Hz
Laser energy: 10J/Pulse
Laser pulse rate: 12Hz
Beam velocity: 8.11 km/s
Irradiation time: 6 hours or 12 hours Irradiation dose: 7.765×10 ¹⁹ atoms/cm ² (when irradiated for 6 hours)
1.553×10 ²⁰ atoms/cm ² (when irradiated for 12 hours)
Irradiation temperature: room temperature

The used base film is as follows. All base films had a 50 mm x 50 mm square shape.
Polyethylene (LLDPE): TUS-TCS#60 manufactured by Mitsui Chemicals Tohcello Co., Ltd., thickness 53 μm
Polypropylene (CPP): manufactured by Toray Advanced Film Co., Ltd., Torayfan ZK93FM, thickness 60 μm
Polyethylene terephthalate (PET): manufactured by Toyobo Co., Ltd., E5000, thickness 75 μm
Polyvinylidene fluoride (PVDF): manufactured by Kureha Co., Ltd., thickness 16 μm
Polyvinylidene chloride (PVDC): manufactured by Kureha Co., Ltd., thickness 45 μm

2. Evaluation 2-1. Antibacterial property The antibacterial property against Escherichia coli or Staphylococcus aureus of the evaluation sample and the comparative sample was evaluated according to the method described in JIS Z 2801 (2012). Lactic acid bacteria or Pseudomonas aeruginosa were also evaluated in the same manner as Escherichia coli or Staphylococcus aureus. Specifically, the following Escherichia coli, Staphylococcus aureus, lactic acid bacteria, or Pseudomonas aeruginosa were inoculated and cultured for 24 hours under the following conditions.
(Bacterial species)
Escherichia coli: Escherichia coli, NBRC No. 3972
Staphylococcus aureus: Staphylococcus aureus, NBRC No. 12732
Lactic acid bacteria: Lactobacillus casei, NBRC No. 15883
Pseudomonas aeruginosa: Pseudomonas aeruginosa, NBRC No. 12689
(Culture conditions)
Temperature: Escherichia coli, Staphylococcus aureus, lactic acid bacteria 35°C ± 1°C, Pseudomonas aeruginosa 30°C ± 1°C
(Measurement of viable count)
Medium used: Standard agar medium

Immediately after inoculation and 24 hours after inoculation, the viable count was measured according to the method described in JIS Z 2801 (2012), and the Δlog count (the logarithmic value of the viable count after 24 hours of the comparative sample-evaluation The logarithmic value of the number of viable bacteria after 24 hours of the sample was obtained. When the Δlog number of bacteria was 2.0 or more, it was evaluated that the sample for evaluation had sufficient antibacterial properties.

Table 1 shows the Δlog and antibacterial evaluation results for each evaluation sample (“○” indicates that sufficient antibacterial properties are observed, and “×” indicates that sufficient antibacterial properties are not observed.) indicates

As shown in Table 1, it was confirmed that the surface of the substrate film was imparted with antibacterial properties by the irradiation of the atomic oxygen beam.

In particular, when the irradiation time of the atomic oxygen beam is 12 hours (irradiation dose: 1.553×10 ²⁰ atoms/cm ² ), the irradiation time is 6 hours (irradiation dose: 7.765×10 ¹⁹ atoms/cm 2 ). ² ) was more likely to be imparted with antibacterial properties.

In addition, non-aromatic resins (LLDPE, PVDC and PVDF) were more likely to be imparted with antibacterial properties than aromatic resins (PET), and LLDPE was particularly likely to be imparted with antibacterial properties.

2-2. Surface Shape A cross-section of each evaluation sample was imaged with a scanning electron microscope (SEM), and 10 protrusion shapes were arbitrarily selected from the obtained SEM image. Two oblique sides (20 in total) constituting the selected protrusion shape were converted into actual size XY coordinate data converted as 0.0099 μm per pixel. For one hypotenuse, out of the transformed coordinate data, data at positions starting from the data where the X coordinate is 0 and shifted by 5 pixels in the X-axis direction are extracted, and the extracted data are converted into two-dimensional data. A polynomial least squares approximation was fitted to find the value of a in the equation ax ² +bx+c that fits the above extracted data. Starting from data with X coordinates of 1, 2, 3 and 4, data at positions shifted by 5 pixels in the X-axis direction are also extracted, and each extracted data is similarly subjected to polynomial least squares. It was fitted to an approximation formula. The average value of the values of a in the five approximation formulas obtained in this manner was obtained and used as the value of a for the hypotenuse. Similarly, the value of a was calculated for all 20 oblique sides, and the average value of the 20 calculated values of a was used as the projection curvature index for the evaluation sample.

When the projection curvature index is a positive value, the projections included in the evaluation sample have slopes that are recessed toward the inside of the projection (see FIG. 1A). When the projection curvature index is a negative value, the projection included in the evaluation sample has an outwardly convex slope (see FIG. 1B).

Table 2 shows the protrusion curvature index and antibacterial evaluation results of each evaluation sample.

As shown in Table 2, the evaluation samples with a positive projection curvature index value had antibacterial properties, but the evaluation samples with a negative projection curvature index value did not exhibit antibacterial properties.

2-3. Contact Angle Using a CA-V type contact angle meter manufactured by Kyowa Interface Science Co., Ltd., the contact angles between each evaluation sample and comparative sample and pure water, diiodomethane and n-hexadecane were determined.

Specifically, 1 μl of a liquid droplet of either pure water, diiodomethane, or n-hexadecane was dropped on the surface of each of the evaluation sample and the comparison sample, and the contact angle from 1000 msec to 10000 msec after dropping was 1000 msec. The contact angle at 1000 msec after dropping was taken as the contact angle between the evaluation sample and the liquid. In addition, when the wettability of the dropped liquid is high and the contact angle is less than 10°, the contact angle from 100 msec to 1000 msec after dropping is measured at intervals of 100 msec, and the contact angle at 1000 msec after dropping is measured. , the contact angle between the evaluation sample or the comparative sample and the liquid.

Table 3 shows the contact angles of each evaluation sample and comparison sample. In addition, those with "atomic oxygen beam irradiation time" of 0 indicate comparative samples that were not irradiated with the atomic oxygen beam.

The relationship between the contact angle and the antibacterial evaluation results is shown in FIGS. 2A, 2B and 2C. FIG. 2A is a graph obtained by plotting Δlog for each bacterial species for each evaluation sample and comparison sample on the horizontal axis and the contact angle with pure water on the vertical axis, and FIG. 2C is a graph obtained by plotting the Δlog for each bacterial species on the horizontal axis and the contact angle with diiodomethane on the vertical axis, and FIG. 2C shows each evaluation sample and comparison sample. 1 is a graph obtained by plotting Δlog for each bacterial species on the horizontal axis and the contact angle with n-hexadecane on the vertical axis. In addition, in FIGS. 2A, 2B and 2C, the dotted line indicates the boundary at which Δlog=2, which is an index for evaluating the presence of antibacterial properties.

As is clear from FIGS. 2A, 2B and 2C, no clear correlation was observed between the contact angle between the evaluation sample and the comparative sample and each liquid and the antibacterial properties.

2-4. Surface Free Energy Using the contact angles obtained above, the surface free energies of the respective evaluation samples and comparison samples were calculated.

Specifically, using two contact angles, the contact angle with pure water and the contact angle with diiodomethane, the surface free energy was calculated by the Owen and Wendt method, and the contact angle with pure water and the contact angle with n-hexadecane were calculated. The surface free energy was calculated by the Kaelble-Uy method using two contact angles.

Table 4 shows the surface free energy of each evaluation sample and comparison sample calculated by the Owen and Wendt method (value of dispersion component (A), value of hydrogen bond component (B), (A) and (B) , the ratio of the value of the hydrogen bonding component (B) to the value of the dispersion component (A), and the ratio of the value of the hydrogen bonding component (B) to the total value). In addition, those with "atomic oxygen beam irradiation time" of 0 indicate comparative samples that were not irradiated with the atomic oxygen beam.

FIG. 3A, FIG. 3B and FIG. 3C show the relationship between the surface free energy calculated by the Owen and Wendt method and the antibacterial evaluation results. In FIG. 3A, the horizontal axis is Δlog for each bacterial species of each evaluation sample and comparative sample, and the vertical axis is the total value (A + B) of the value of the dispersion component (A) and the value of the hydrogen bond component (B). 3B is a graph obtained by plotting, and FIG. 3B shows Δlog for each bacterial species of each evaluation sample and comparison sample on the horizontal axis, and the hydrogen bond component (B) with respect to the value of the dispersion component (A). 3C is a graph obtained by plotting the ratio (B / A) of the value on the vertical axis, and FIG. It is a graph obtained by plotting the ratio (B/(A+B)) of the value of the hydrogen bonding component (B) to the vertical axis. In addition, in FIGS. 3A, 3B, and 3C, the dotted line indicates the boundary at which Δlog=2, which is an index for evaluating the presence of antibacterial properties.

Table 5 shows the surface free energy of each evaluation sample and comparison sample calculated by the Kaelble-Uy method (value of dispersion component (A), value of polar component (C), values of (A) and (C) total value, the ratio of the value of the polar component (C) to the value of the variance component (A), and the ratio of the value of the polar component (C) to the total value). In addition, those with "atomic oxygen beam irradiation time" of 0 indicate comparative samples that were not irradiated with the atomic oxygen beam.

The relationship between the surface free energy calculated by the Kaelble-Uy method and the antibacterial evaluation results is shown in FIGS. 4A, 4B and 4C. In FIG. 4A, the horizontal axis is Δlog for each bacterial species of each evaluation sample and comparative sample, and the vertical axis is the total value (A + C) of the value of the dispersion component (A) and the value of the polar component (C). , is a graph obtained by plotting, and FIG. 4B shows the value of the polar component (C) with respect to the value of the variance component (A), with the horizontal axis representing Δlog for each bacterial species for each evaluation sample and comparison sample. 4C is a graph obtained by plotting the ratio (C / A) on the vertical axis, and FIG. It is a graph obtained by plotting the ratio (C/(A+C)) of the value of component (C) on the vertical axis. In addition, in FIGS. 4A, 4B, and 4C, the dotted line indicates the boundary at which Δlog=2, which is an index for evaluating the presence of antibacterial properties.

As is clear from FIGS. 3A, 3B, 3C, 4A, 4B and 4C, there is a clear correlation between the surface free energy of the evaluation sample and the comparative sample and the antibacterial properties. I couldn't.

This application is an application claiming priority based on Japanese Application No. 2018-149404 filed on August 8, 2018, and the contents described in the claims, specification and drawings of the application are herein incorporated in the application.

The resin molded article of the present invention can be used for various sterilization and antibacterial applications.

Claims (9)

A molded body of a resin composition, having a region on its surface imparted with antibacterial properties by irradiation with an atomic oxygen beam,
The resin molded body, wherein the cumulative irradiation dose of the atomic oxygen beam to the region imparted with the antibacterial property is 1.0 × 10 ²⁰ atoms/cm ² or more and 1.0 × 10 ²² atoms/cm ² or less . . The region imparted with antibacterial properties has a plurality of nano-sized protrusions protruding from the surface,
The plurality of nano-sized projections have slopes that are recessed toward the inside of the projections,
The resin molding according to claim 1. 3. The resin molding according to claim 1, wherein the resin composition contains a non-aromatic resin. 4. According to any one of claims 1 to 3, wherein the region imparted with antibacterial properties has antibacterial properties against at least one bacterium selected from the group consisting of Escherichia coli, Staphylococcus aureus, lactic acid bacteria and Pseudomonas aeruginosa. The resin molding described. The resin molded article according to any one of claims 1 to 4, wherein the molded article is a film-like molded article. A step of preparing a molded body of the resin composition;
A step of imparting antibacterial properties to the surface of the molded body by irradiation with an atomic oxygen beam;
has
In the step of imparting antibacterial properties, the cumulative irradiation dose of the atomic oxygen beam is 1.0 × 10 ²⁰ atoms/cm ² or more and 1.0 × 10 ²² atoms/cm ² or less . A method for producing a resin molded body having a surface having a scalloped surface. 7. The resin molding according to claim 6, wherein the atomic oxygen beam is generated by a laser detonation method in which both oxygen molecular gas and laser are emitted in a pulsed manner, and the energy of the laser is 8 J/pulse or more. Production method. 6. The atomic oxygen beam is generated by a laser detonation method in which both an oxygen molecular gas and a laser are emitted in pulses, and the laser has a repetition rate (pulse rate) of 5 Hz or more per second. 8. The method for producing a resin molded product according to 7 above. A step of preparing the resin molding according to any one of claims 1 to 5;
a step of contacting the resin molding with a liquid, solid or gas containing bacteria;
A sterilization method, comprising:

Images