WO2019044586A1

WO2019044586A1 - Synthetic polymer film having surface provided with bactericidal action, and sterilization method using surface of synthetic polymer film

Info

Publication number: WO2019044586A1
Application number: PCT/JP2018/030788
Authority: WO
Inventors: 芝井　康博; 美穂山田; 賢厚母; 箕浦　潔
Original assignee: シャープ株式会社
Priority date: 2017-08-29
Filing date: 2018-08-21
Publication date: 2019-03-07
Also published as: JP7042278B2; JPWO2019044586A1

Abstract

A synthetic polymer film (34A, 34B) is provided with a surface having a plurality of first projections (34Ap, 34Bp); when viewed from the normal direction of the synthetic polymer film, the plurality of first projections (34Ap, 34Bp) has a two-dimensional size within the range from more than 20 nm to less than 500 nm and has a crosslinked structure; the crosslinked structure does not contain elemental nitrogen and elemental fluorine and has an ethylene oxide unit and/or water-soluble monomer unit; and the crosslinking density n determined from the formula n = Er'/(3∙R∙Tr), taking the minimum value of the dynamic storage modulus E' in the temperature region exceeding the glass transition temperature as Er' (Pa), taking the minimum temperature that gives Er' as Tr (K), and taking the gas constant R as 8.3 J/mol∙K, is within the range of 2.8 × 10-3 mol/cc to 9.5 × 10-3 mol/cc inclusive.

Description

Synthetic polymer film having a surface having a bactericidal action and sterilization method using the surface of the synthetic polymer film

The present invention relates to a synthetic polymer membrane having a surface with a bactericidal action and a sterilization method using the surface of the synthetic polymer membrane.

Recently, it was announced that nanosurface structures possessed by black silicon, semi- and dragonfly wings have a bactericidal action (Non-patent Document 1). It is believed that the physical structure of nanopillars possessed by black silicon, semi- and dragonfly wings exerts a bactericidal action.

According to Non-Patent Document 1, the bactericidal action against Gram-negative bacteria is the strongest in black silicon, and becomes weaker in the order of dragonfly wings and semi wings. Black silicon has nanopillars with a height of 500 nm, and semi and dragonfly wings have nanopillars with a height of 240 nm. In addition, the static contact angle (hereinafter simply referred to as the “contact angle”) of these surfaces against water is 80 ° for black silicon, while that of the dragonfly is 153 ° and that of the semi is It is 159 °. In addition, it is considered that black silicon is mainly formed of silicon, and the wings of semi and dragonfly are formed of chitin. According to Non-Patent Document 1, the composition of the surface of the black silicon is approximately silicon oxide, and the composition of the surface of the semi and dragonfly wings is a lipid.

Patent No. 4265729 JP, 2009-166502, A International Publication No. 2011/125486 International Publication No. 2013/183576 WO 2015/163018 (Patent No. 5788128) WO 2016/080245 (Patent No. 5933151) International Publication No. 2016/208540

From the results described in Non-Patent Document 1, the mechanism by which bacteria are killed by nanopillars is not clear. Furthermore, whether the reason that black silicon has a stronger bactericidal action than dragonflies and semi-feathers is the difference in the height and shape of nanopillars, or the difference in surface free energy (which can be evaluated by the contact angle) It is unclear whether it is the constituent material or the chemical nature of the surface.

Further, even if the bactericidal action of black silicon is used, black silicon is poor in mass productivity and hard and brittle, so that there is a problem that shape processability is low.

The present invention has been made to solve the above-mentioned problems, and its main object is to provide a synthetic polymer membrane having a surface having a bactericidal action and a sterilization method using the surface of the synthetic polymer membrane. It is to do. Another object of the present invention is to provide a synthetic polymer film having a bactericidal surface, which is excellent in water resistance and / or mass productivity.

The synthetic polymer film according to an embodiment of the present invention is a synthetic polymer film provided with a surface having a plurality of first convex portions, and when viewed from the normal direction of the synthetic polymer film, the plurality of the synthetic polymer films The two-dimensional size of the first convex portion is in the range of more than 20 nm and less than 500 nm, and has a crosslinked structure, and the crosslinked structure does not contain nitrogen and fluorine, and ethylene oxide units and / or water soluble monomers The minimum value of the dynamic storage elastic modulus E ′ in the temperature range having a unit and exceeding the glass transition temperature is Er ′ (Pa), the minimum temperature giving Er ′ is Tr (K), and the gas constant R is 8. The crosslinking density n calculated from the equation n = Er '/ (3 · R · Tr) as 3 J / mol · K is 2.8 × 10 ^-3 mol / cc or more and 9.5 × 10 ^-3 mol / cc It is in the following range.

Here, dynamic storage elastic modulus Er '(Pa) and Tr (K) are calculated | required by DMA (it is also called dynamic mechanical analysis and dynamic viscoelasticity measurement).

In one embodiment, the crosslink density n is 8.4 × 10 ⁻³ mol / cc or less.

In one embodiment, the crosslink density n is 5.8 × 10 ⁻³ mol / cc or less.

In one embodiment, the crosslink density n is 3.7 × 10 ⁻³ mol / cc or more.

In one embodiment, the total content of ethylene oxide units and water-soluble monomer units contained in the cross-linked structure is more than 40% by mass relative to the entire synthetic polymer film.

In one embodiment, the total content of ethylene oxide units and water-soluble monomer units contained in the crosslinked structure is 70% by mass or less based on the total weight of the synthetic polymer film.

In one embodiment, the dynamic storage modulus Er 'is greater than 20 MPa and less than 90 MPa.

In one embodiment, the dynamic storage modulus Er 'is less than 75 MPa.

In one embodiment, the crosslinked structure contains a monomer unit having a siloxane bond.

A method of sterilizing a liquid according to an embodiment of the present invention is a method of sterilizing the liquid by bringing the liquid containing water into contact with the surface of the synthetic polymer membrane described in any of the above.

According to an embodiment of the present invention, a synthetic polymer membrane having a surface having a bactericidal action and a sterilization method using the surface of the synthetic polymer membrane are provided. According to an embodiment of the present invention, a synthetic polymer membrane having a bactericidal surface excellent in water resistance and / or mass productivity is provided.

(A) And (b) is typical sectional drawing of synthetic-

polymer film

34A and 34B by embodiment of this invention, respectively. (A) to (e) are diagrams for explaining the manufacturing method of the moth-eye mold 100A and the structure of the moth-eye mold 100A. (A) to (c) are diagrams for explaining the manufacturing method of the moth-eye mold 100B and the structure of the moth-eye mold 100B. (A) shows the SEM image of the surface of the aluminum substrate, (b) shows the SEM image of the surface of the aluminum film, and (c) shows the SEM image of the cross section of the aluminum film. (A) is a schematic plan view of a porous alumina layer of a mold, (b) is a schematic cross-sectional view, and (c) is a view showing an SEM image of a prototype manufactured. It is a figure for demonstrating the manufacturing method of the synthetic polymer film using the type | mold 100 for moth-eye. (A) And (b) is a figure which shows the SEM image which observed the Pseudomonas aeruginosa which died on the surface which has a moth-eye structure by SEM (scanning electron microscope). It is a graph which shows the result of having measured temperature dependence of dynamic storage elastic modulus E 'of a synthetic polymer film of Example 1. It is a graph which shows the relationship of the crosslink density of the synthetic polymer membrane of Examples 1-8 and Comparative Examples 2-7, and a viable cell rate.

Hereinafter, with reference to the drawings, a sterilizing method using a surface of a synthetic polymer film having a bactericidal effect and a surface of the synthetic polymer film according to an embodiment of the present invention will be described.

In the present specification, the following terms will be used.

"Sterilization (microbicidal)" refers to reducing the number of viable organisms contained in a limited space or an object such as an object or liquid, by an effective number.

"Microbes" include viruses, bacteria (bacteria), fungi (molds).

"Antimicrobial" broadly includes suppressing and preventing the growth of microorganisms, and includes suppressing darkening and slimming due to microorganisms.

The applicant has developed a method for producing an antireflective film (antireflective surface) having a moth-eye structure using an anodized porous alumina layer. By using the anodized porous alumina layer, a mold having an inverted moth-eye structure can be manufactured with high mass productivity.

The inventor of the present invention has developed a synthetic polymer film having a bactericidal effect on the surface by applying the above-mentioned technology (see, for example, Patent Documents 5, 6 and 7). The entire disclosures of the above-mentioned Patent Documents 5, 6 and 7 are incorporated herein by reference.

The structure of a synthetic polymer membrane according to an embodiment of the present invention will be described with reference to FIGS. 1 (a) and (b).

FIGS. 1 (a) and (b) show schematic cross-sectional views of

synthetic polymer films

34A and 34B, respectively, according to an embodiment of the present invention. The

synthetic polymer films

34A and 34B exemplified here are each formed on the

base films

42A and 42B respectively, but of course is not limited thereto. The

synthetic polymer films

34A and 34B can be formed directly on the surface of any object.

A film 50A shown in FIG. 1A includes a base film 42A and a synthetic polymer film 34A formed on the base film 42A. The synthetic polymer film 34A has a plurality of projections 34Ap on the surface, and the plurality of projections 34Ap form a moth-eye structure. When viewed in the normal direction of the synthetic polymer film 34A, the two-dimensional size D _p of the convex portion 34Ap is in the range of more than 20 nm and less than 500 nm. Here, the “two-dimensional size” of the convex portion 34Ap refers to the area circle equivalent diameter of the convex portion 34Ap when viewed from the normal direction of the surface. For example, in the case where the convex portion 34Ap has a conical shape, the two-dimensional size of the convex portion 34Ap corresponds to the diameter of the base of the cone. Further, a typical adjacent distance D _int of the convex portion 34Ap is more than 20 nm and 1000 nm or less. As illustrated in FIG. 1A, in the case where the convex portions 34Ap are densely arranged and there is no gap between adjacent convex portions 34Ap (for example, the bottom of the cone partially overlaps), the convex is The two-dimensional size D _p of the part 34 Ap is equal to the distance D _int between adjacent parts. Typical height D _h of convex part 34Ap is 50 nm or more and less than 500 nm. As described later, even if the height D _h of the convex portion 34Ap is 150 nm or less, the bactericidal action is exhibited. There is no particular limitation on the thickness t _s of the synthetic polymer film 34A, and it may be larger than the height D _h of the convex portion 34Ap.

The synthetic polymer film 34A shown in FIG. 1 (a) has a moth-eye structure similar to the antireflective film described in Patent Documents 1 to 4. In order to exhibit an anti-reflection function, it is preferable that there is no flat portion on the surface, and the convex portions 34Ap are densely arranged. In addition, the convex portion 34Ap has a shape in which a cross-sectional area (a cross section parallel to a plane perpendicular to the incident light beam, for example, a cross section parallel to the plane of the base film 42A) increases from the air side to the base film 42A side. Preferably it is conical. Further, in order to suppress light interference, it is preferable to arrange the convex portions 34Ap preferably at random so as to have no regularity. However, these characteristics are not necessary when the bactericidal action of the synthetic polymer film 34A is exclusively used. For example, the protrusions 34Ap do not have to be arranged densely, and may be arranged regularly. However, it is preferable that the shape and arrangement of the projections 34Ap be selected so as to effectively act on microorganisms.

A film 50B shown in FIG. 1B has a base film 42B and a synthetic polymer film 34B formed on the base film 42B. The synthetic polymer film 34B has a plurality of projections 34Bp on its surface, and the plurality of projections 34Bp constitute a moth-eye structure. In the film 50B, the structure of the projections 34Bp of the synthetic polymer film 34B is different from the structure of the projections 34Ap of the synthetic polymer film 34A of the film 50A. Description of features common to the film 50A may be omitted.

When viewed in the normal direction of the synthetic polymer film 34B, the two-dimensional size D _p of the convex portion 34Bp is in the range of more than 20 nm and less than 500 nm. Further, a typical adjacent distance D _int of the convex portion 34Bp is more than 20 nm and not more than 1000 nm, and D _p <D _int . That is, in the synthetic polymer film 34B, a flat portion exists between the adjacent convex portions 34Bp. The convex portion 34Bp has a cylindrical shape having a conical portion on the air side, and a typical height D _h of the convex portion 34Bp is 50 nm or more and less than 500 nm. The convex portions 34Bp may be regularly arranged or irregularly arranged. If the projections 34Bp are regularly arranged, D _int will also represent the period of the arrangement. This is, of course, the same for the synthetic polymer film 34A.

Incidentally, in the present specification, the “moth-eye structure” is a convex having a shape in which the cross-sectional area (the cross section parallel to the film surface) increases like the convex portion 34Ap of the synthetic polymer film 34A shown in FIG. The cross-sectional area (cross section parallel to the film surface) is not only the nanosurface structure having an excellent reflection function, but also the convex portion 34Bp of the synthetic polymer film 34B shown in FIG. 1 (b). Also includes a nanosurface structure composed of a convex portion having a constant portion. In addition, in order to destroy the cell wall and / or cell membrane of microorganisms, it is preferable to have a conical part. However, the conical tip does not necessarily have to be a nanosurface structure, and may have a roundness (about 60 nm) of a nanopillar that constitutes a nanosurface structure possessed by semi-wings.

A mold for forming a moth-eye structure as illustrated in FIGS. 1A and 1B (hereinafter referred to as “moth-eye mold”) is an inverted moth-eye structure obtained by inverting the moth-eye structure. Have. If the anodized porous alumina layer having the inverted moth-eye structure is used as a mold as it is, the moth-eye structure can be manufactured inexpensively. In particular, when a cylindrical moth-eye mold is used, a moth-eye structure can be efficiently manufactured by a roll-to-roll method. Such moth-eye molds can be manufactured by the methods described in Patent Documents 2 to 4.

A method of manufacturing the moth-eye mold 100A for forming the synthetic polymer film 34A will be described with reference to FIGS. 2 (a) to 2 (e).

First, as shown in FIG. 2A, an aluminum substrate 12, an inorganic material layer 16 formed on the surface of the aluminum substrate 12, and aluminum deposited on the inorganic material layer 16 are used as a mold substrate. A mold base 10 having a membrane 18 is provided.

As the aluminum base 12, a relatively rigid aluminum base having a purity of 99.50 mass% to less than 99.99 mass% is used. The impurities contained in the aluminum base 12 include iron (Fe), silicon (Si), copper (Cu), manganese (Mn), zinc (Zn), nickel (Ni), titanium (Ti), lead (Pb) It is preferable to include at least one element selected from the group consisting of tin (Sn) and magnesium (Mg), and in particular, Mg is preferable. Since the mechanism by which pits (pits) are formed in the etching step is a local cell reaction, ideally it contains no element nobler than aluminum at all, and it is a basic metal Mg (standard electrode potential is It is preferable to use an aluminum base 12 containing 2.36 V) as an impurity element. If the content of the element nobler than aluminum is 10 ppm or less, it can be said that the element is not substantially contained from an electrochemical viewpoint. The content of Mg is preferably 0.1 mass% or more of the whole, and more preferably in the range of about 3.0 mass% or less. If the content of Mg is less than 0.1 mass%, sufficient rigidity can not be obtained. On the other hand, when the content ratio is high, segregation of Mg is likely to occur. Segregation near the surface forming the moth-eye mold causes no problem electrochemically, but Mg forms an anodic oxide film having a form different from that of aluminum, which causes defects. The content rate of the impurity element may be appropriately set in accordance with the required rigidity according to the shape, thickness and size of the aluminum base 12. For example, in the case of producing the plate-like aluminum base 12 by rolling, the content of Mg is suitably about 3.0 mass%, and the aluminum base 12 having a three-dimensional structure such as a cylinder is produced by extrusion. In the case where the content of Mg is to be added, the content of Mg is preferably 2.0 mass% or less. When the content of Mg exceeds 2.0 mass%, extrusion processability generally decreases.

As the aluminum base 12, for example, a cylindrical aluminum pipe formed of JIS A1050, an Al-Mg-based alloy (for example, JIS A5052), or an Al-Mg-Si-based alloy (for example, JIS A6063) is used.

It is preferable that the surface of the aluminum base 12 is subjected to cutting with a cutting tool. For example, when abrasive grains remain on the surface of the aluminum base 12, conduction between the aluminum film 18 and the aluminum base 12 is facilitated in the portion where the abrasives are present. In addition to the abrasive grains, in the places where the unevenness is present, local conduction between the aluminum film 18 and the aluminum base 12 is facilitated. Local conduction between the aluminum film 18 and the aluminum substrate 12 may cause a cell reaction to occur locally between the impurity in the aluminum substrate 12 and the aluminum film 18.

As a material of the inorganic material layer 16, for example, tantalum oxide (Ta ₂ O ₅ ) or silicon dioxide (SiO ₂ ) can be used. The inorganic material layer 16 can be formed, for example, by sputtering. When a tantalum oxide layer is used as the inorganic material layer 16, the thickness of the tantalum oxide layer is, for example, 200 nm.

The thickness of the inorganic material layer 16 is preferably 100 nm or more and less than 500 nm. When the thickness of the inorganic material layer 16 is less than 100 nm, defects (mainly voids, that is, gaps between crystal grains) may occur in the aluminum film 18. In addition, when the thickness of the inorganic material layer 16 is 500 nm or more, the surface state of the aluminum base 12 easily insulates between the aluminum base 12 and the aluminum film 18. In order to anodize the aluminum film 18 by supplying the current to the aluminum film 18 from the aluminum base 12 side, it is necessary to flow the current between the aluminum base 12 and the aluminum film 18. If a configuration is employed in which current is supplied from the inner surface of cylindrical aluminum base 12, no electrode needs to be provided on aluminum film 18, so that aluminum film 18 can be anodized over the entire surface, and the current flows as the anodic oxidation progresses. The aluminum film 18 can be uniformly anodized over the entire surface without the problem of difficulty in supplying the aluminum film 18.

In addition, in order to form the thick inorganic material layer 16, generally, it is necessary to prolong the film formation time. When the film forming time is long, the surface temperature of the aluminum base 12 is unnecessarily increased. As a result, the film quality of the aluminum film 18 may be deteriorated to cause defects (mainly voids). If the thickness of the inorganic material layer 16 is less than 500 nm, the occurrence of such a defect can also be suppressed.

For example, as described in Patent Document 3, the aluminum film 18 is a film formed of aluminum having a purity of 99.99 mass% or more (hereinafter, sometimes referred to as “high purity aluminum film”). The aluminum film 18 is formed, for example, using a vacuum evaporation method or a sputtering method. The thickness of the aluminum film 18 is preferably in the range of about 500 nm to about 1500 nm, for example, about 1 μm.

Further, as the aluminum film 18, an aluminum alloy film described in Patent Document 4 may be used instead of the high purity aluminum film. The aluminum alloy film described in Patent Document 4 contains aluminum, a metal element other than aluminum, and nitrogen. In the present specification, the “aluminum film” includes not only the high purity aluminum film but also the aluminum alloy film described in Patent Document 4.

When the aluminum alloy film is used, a mirror surface having a reflectance of 80% or more can be obtained. The average grain size of the crystal grains constituting the aluminum alloy film as viewed in the normal direction of the aluminum alloy film is, for example, 100 nm or less, and the maximum surface roughness Rmax of the aluminum alloy film is 60 nm or less. The content of nitrogen contained in the aluminum alloy film is, for example, 0.5 mass% or more and 5.7 mass% or less. The absolute value of the difference between the standard electrode potential of a metal element other than aluminum contained in the aluminum alloy film and the standard electrode potential of aluminum is 0.64 V or less, and the content of the metal element in the aluminum alloy film is 1.0 mass. % Or more and 1.9 mass% or less is preferable. The metal element is, for example, Ti or Nd. However, the metal element is not limited to this, and other metal elements (for example, Mn, Mg, Zr, V and the like) whose absolute value of the difference between the standard electrode potential of the metal element and the standard electrode potential of aluminum is 0.64 V or less It may be Pb). Furthermore, the metal element may be Mo, Nb or Hf. The aluminum alloy film may contain two or more of these metal elements. The aluminum alloy film is formed, for example, by DC magnetron sputtering. The thickness of the aluminum alloy film is also preferably in the range of about 500 nm to about 1500 nm, for example, about 1 μm.

Next, as shown in FIG. 2B, the surface 18s of the aluminum film 18 is anodized to form a porous alumina layer 14 having a plurality of recesses (pores) 14p. The porous alumina layer 14 has a porous layer having a recess 14 p and a barrier layer (the bottom of the recess (pore) 14 p). It is known that the distance (center-to-center distance) between adjacent recesses 14p corresponds to approximately twice the thickness of the barrier layer and is approximately proportional to the voltage at the time of anodic oxidation. This relationship also holds true for the final porous alumina layer 14 shown in FIG.

The porous alumina layer 14 is formed, for example, by anodizing the surface 18s in an acidic electrolyte solution. The electrolytic solution used in the step of forming the porous alumina layer 14 is, for example, an aqueous solution containing an acid selected from the group consisting of oxalic acid, tartaric acid, phosphoric acid, sulfuric acid, chromic acid, citric acid and malic acid. For example, the porous alumina layer 14 is formed by anodizing the surface 18s of the aluminum film 18 for 55 seconds at an applied voltage of 80 V using a boric acid aqueous solution (concentration 0.3 mass%, solution temperature 10 ° C.).

Next, as shown in FIG. 2C, the opening of the recess 14p is enlarged by etching the porous alumina layer 14 by a predetermined amount by bringing the porous alumina layer 14 into contact with an etchant of alumina. The amount of etching (that is, the size and depth of the recess 14p) can be controlled by adjusting the type and concentration of the etching solution and the etching time. As an etching solution, for example, an aqueous solution of 10 mass% of phosphoric acid, an organic acid such as formic acid, acetic acid, citric acid or the like, sulfuric acid, or a mixed aqueous solution of chromic acid and phosphoric acid can be used. For example, etching is performed using a phosphoric acid aqueous solution (10 mass%, 30 ° C.) for 20 minutes.

Next, as shown in FIG. 2D, the aluminum film 18 is partially anodized again to grow the recess 14 p in the depth direction and to thicken the porous alumina layer 14. Here, since the growth of the recess 14p starts from the bottom of the recess 14p already formed, the side surface of the recess 14p is stepped.

After this, if necessary, the pore diameter of the recess 14p is further expanded by further etching the porous alumina layer 14 by contacting it with an etchant of alumina. As the etching solution, it is preferable to use the above-described etching solution, and in reality, the same etching bath may be used.

Thus, as shown in FIG. 2 (e), the anodization step and the etching step are alternately repeated a plurality of times (for example, 5 times: 5 times of anodization and 4 times of etching). A moth-eye mold 100A having a porous alumina layer 14 having a moth-eye structure is obtained. By ending in the anodizing step, the bottom of the recess 14p can be made point. That is, a mold capable of forming a convex portion with a sharp tip is obtained.

The porous alumina layer 14 (thickness t _p ) shown in FIG. 2 (e) has a porous layer (thickness corresponds to the depth D _d of the recess 14 p) and a barrier layer (thickness t _b ). Since the porous alumina layer 14 has a structure obtained by inverting the moth-eye structure of the synthetic polymer film 34A, the same symbol may be used as the corresponding parameter characterizing its size.

The recess 14 p of the porous alumina layer 14 is, for example, conical, and may have stepped side surfaces. Two-dimensional size of the recess 14p is D _p (area equivalent circle diameter of the recess when viewed from the direction normal to the surface) is less than 20nm ultra 500 nm, the depth D _d in the order of less than 50nm over 1000 nm (1 [mu] m) Is preferred. Further, it is preferable that the bottom of the recess 14p be pointed (the bottom is a point). Assuming that the shape of the recess 14p when viewed from the normal direction of the porous alumina layer 14 is a circle when the recess 14p is densely packed, adjacent circles overlap each other, and a ridge is formed between the adjacent recesses 14p. It is formed. Incidentally, when the concave portion 14p of the substantially conical adjacent so as to form a saddle, two-dimensional size D _p of the concave portion 14p is equal to the distance between adjacent D _int. The thickness t _p of the porous alumina layer 14 is, for example, about 1 μm or less.

Under the porous alumina layer 14 shown in FIG. 2E, an aluminum remaining layer 18r which has not been anodized in the aluminum film 18 is present. If necessary, the aluminum film 18 may be substantially completely anodized so that the aluminum residual layer 18r is not present. For example, when the inorganic material layer 16 is thin, current can be easily supplied from the aluminum base 12 side.

The moth-eye mold manufacturing method exemplified here can manufacture a mold for manufacturing the anti-reflection film described in Patent Documents 2 to 4. Since high uniformity is required for the antireflective film used for a high definition display panel, as described above, selection of the material of the aluminum substrate, mirror processing of the aluminum substrate, control of the purity and composition of the aluminum film Although it is preferable to carry out the above-mentioned method, it is possible to simplify the manufacturing method of the above-mentioned type since high uniformity is not required for the bactericidal action. For example, the surface of the aluminum substrate may be anodized directly. At this time, even if pits are formed due to the effect of impurities contained in the aluminum base, local structural disorder is generated in the moth-eye structure of the synthetic polymer film 34A finally obtained, which gives the bactericidal action. It is considered that there is almost no impact.

In addition, according to the above-described method of manufacturing a mold, it is possible to manufacture a mold having low regularity of the arrangement of the recesses, which is suitable for the preparation of an antireflective film. When utilizing the bactericidal property of the moth-eye structure, it is considered that the regularity of the arrangement of the projections does not affect. The type | mold for forming the moth-eye structure which has the regularly arranged convex part can be manufactured as follows, for example.

For example, after a porous alumina layer having a thickness of about 10 μm is formed, the generated porous alumina layer may be removed by etching, and then anodic oxidation may be performed under the conditions for forming the above-mentioned porous alumina layer. A 10 μm thick porous alumina layer is formed by prolonging the anodic oxidation time. Thus, a relatively thick porous alumina layer is formed, and removing the porous alumina layer results in regular alignment without being affected by irregularities or processing distortion due to grains present on the surface of the aluminum film or aluminum substrate. It is possible to form a porous alumina layer having recessed portions. In addition, it is preferable to use the liquid mixture of chromic acid and phosphoric acid for the removal of a porous alumina layer. Galvanic corrosion may occur when etching is performed for a long time, but a mixture of chromic acid and phosphoric acid has an effect of suppressing galvanic corrosion.

The moth-eye mold for forming the synthetic polymer film 34B shown in FIG. 1 (b) can also be manufactured basically by combining the above-described anodic oxidation step and etching step. A method of manufacturing the moth-eye mold 100B for forming the synthetic polymer film 34B will be described with reference to FIGS. 3 (a) to 3 (c).

First, in the same manner as described with reference to FIGS. 2A and 2B, the mold base 10 is prepared, and the surface 18s of the aluminum film 18 is anodized to form a plurality of recesses (pores). A porous alumina layer 14 having 14p is formed.

Next, as shown in FIG. 3A, the porous alumina layer 14 is etched by a predetermined amount by contacting with an etchant of alumina to enlarge the opening of the recess 14p. At this time, the etching amount is made smaller than the etching process described with reference to FIG. That is, the size of the opening of the recess 14p is reduced. For example, etching is performed using a phosphoric acid aqueous solution (10 mass%, 30 ° C.) for 10 minutes.

Next, as shown in FIG. 3B, the aluminum film 18 is partially anodized again to grow the recess 14 p in the depth direction and to thicken the porous alumina layer 14. At this time, the concave portion 14p is made to grow deeper than the anodic oxidation process described with reference to FIG. 2 (d). For example, anodization is performed for 165 seconds at an applied voltage of 80 V using an aqueous oxalic acid solution (concentration 0.3 mass%, solution temperature 10 ° C.) (55 seconds in FIG. 2D).

Thereafter, the etching step and the anodizing step are alternately repeated several times in the same manner as described with reference to FIG. For example, by alternately repeating the etching process three times and the anodizing process three times alternately, as shown in FIG. 3C, a moth-eye mold 100B having a porous alumina layer 14 having an inverted moth-eye structure is obtained. Be At this time, the two-dimensional size D _p of the recess 14 _p is smaller than the adjacent distance D _int (D _p <D _int ).

The size of the microorganism depends on its type. For example, although the size of Pseudomonas aeruginosa is about 1 μm, some bacteria have a size of several hundred nm to about 5 μm, and fungi have several μm or more. For example, a convex portion having a two-dimensional size of about 200 nm is considered to have a bactericidal action against microorganisms having a size of about 0.5 μm or more, but for bacteria having a size of several hundred nm. Because the convex portion is too large, sufficient bactericidal action may not be exhibited. Further, the size of the virus is several tens nm to several hundreds nm, and many viruses are 100 nm or less. Although the virus does not have a cell membrane, it has a protein shell called a capsid that surrounds the viral nucleic acid. Viruses are divided into viruses with a membrane-like envelope outside this shell and viruses without an envelope. In the case of an enveloped virus, since the envelope is mainly composed of lipids, it is thought that the convex portion acts similarly on the envelope. Examples of enveloped viruses include influenza virus and Ebola virus. In viruses that do not have an envelope, it is thought that the convex portion acts similarly on the shell of a protein called this capsid. When the convex portion contains a nitrogen element, affinity with a protein composed of amino acids can be strong.

Therefore, the structure of a synthetic polymer film having a convex portion capable of exhibiting a bactericidal action even against a microorganism having a size of several hundred nm or less and a method for producing the same will be described below.

Below, the convex part which has a two-dimensional magnitude | size in the range of more than 20 nm and less than 500 nm which the synthetic polymer membrane illustrated above has is called 1st convex part. Further, a convex portion formed to overlap the first convex portion is referred to as a second convex portion, and a two-dimensional size of the second convex portion is a two-dimensional size of the first convex portion. Less than 100 nm. When the two-dimensional size of the first convex portion is less than 100 nm, particularly less than 50 nm, it is not necessary to provide the second convex portion. Further, the concave portion of the mold corresponding to the first convex portion is referred to as a first concave portion, and the concave portion of the mold corresponding to the second convex portion is referred to as a second concave portion.

By alternately performing the anodizing step and the etching step described above, the second recess can not be formed even if the method of forming the first recess having a predetermined size and shape is applied as it is.

FIG. 4 (a) shows a SEM image of the surface of the aluminum base (12 in FIG. 2), and FIG. 4 (b) shows a SEM image of the surface of the aluminum film (18 in FIG. 2). FIG. 4C shows an SEM image of the cross section of the aluminum film (reference numeral 18 in FIG. 2). As can be seen from these SEM images, grains (grains) are present on the surface of the aluminum substrate and the surface of the aluminum film. The grains of the aluminum film form asperities on the surface of the aluminum film. The surface asperities affect the formation of the recess during anodization, thus preventing the formation of a second recess in which D _p or D _int is smaller than 100 nm.

Thus, a method of producing a mold used for producing a synthetic polymer membrane according to an embodiment of the present invention comprises the steps of: (a) preparing an aluminum film deposited on an aluminum substrate or support; (b) Anodizing step of forming a porous alumina layer having a first recess by applying a first level voltage while the surface of the aluminum substrate or aluminum film is in contact with the electrolytic solution; (c) After the step (b), the porous alumina layer was brought into contact with the electrolytic solution after the etching step of enlarging the first recess by bringing the porous alumina layer into contact with the etching solution and (d) the step (c) Forming a second recess in the first recess by applying a second level voltage lower than the first level in the state. For example, the first level is above 40V and the second level is below 20V.

That is, in the anodizing process at a first level of voltage, a first recess having a size that is not affected by the aluminum substrate or the grain of the aluminum film is formed, and then the thickness of the barrier layer is After being made smaller, a second recess is formed in the first recess in an anodizing process at a second level voltage lower than the first level. In this way, forming the second recess eliminates the influence of grains.

Referring to FIG. 5, a mold having a first recess 14pa and a second recess 14pb formed in the first recess 14pa will be described. FIG. 5 (a) is a schematic plan view of a porous alumina layer of a mold, FIG. 5 (b) is a schematic cross-sectional view, and FIG. 5 (c) shows an SEM image of the prototype manufactured.

As shown in FIGS. 5 (a) and 5 (b), the surface of the mold according to this embodiment has a plurality of first recesses 14pa having a two-dimensional size in the range of more than 20 nm and less than 500 nm; It further has a plurality of second recesses 14pb formed to overlap the first recesses 14pa. The two-dimensional size of the plurality of second recesses 14pb is smaller than the two-dimensional size of the plurality of first recesses 14pa and does not exceed 100 nm. The height of the second recess 14pb is, for example, more than 20 nm and not more than 100 nm. Similarly to the first recess 14pa, the second recess 14pb preferably includes a substantially conical portion.

The porous alumina layer shown in FIG. 5 (c) was produced as follows.

As an aluminum film, an aluminum film containing 1 mass% of Ti was used. An aqueous solution of oxalic acid (concentration 0.3 mass%, temperature 10 ° C.) was used as the anodizing solution, and an aqueous solution of phosphoric acid (concentration 10 mass%, temperature 30 ° C.) was used as the etching solution. After anodizing at a voltage of 80 V for 52 seconds, etching was carried out for 25 minutes, followed by anodizing at a voltage of 80 V for 52 seconds and etching for 25 minutes. This was followed by anodizing at 20 V for 52 seconds, etching for 5 minutes, and anodizing at 20 V for 52 seconds.

Figure 5 (c) As can be seen from, among D _p is in the first recess of about 200 nm, a second recess of D _p is about 50nm is formed. In the above manufacturing method, when the porous alumina layer is formed by changing the voltage of the first level from 80 V to 45 V, the first recess having a D _p of about 100 nm has a D _p of about 50 nm Two recesses were formed.

When a synthetic polymer film is produced using such a mold, a synthetic polymer having a convex portion obtained by inverting the structure of the first concave portion 14pa and the second concave portion 14pb shown in FIGS. 5A and 5B. A membrane is obtained. That is, a synthetic polymer film further having a plurality of second convex portions formed to overlap a plurality of first convex portions is obtained.

Thus, the synthetic polymer film having the first convex portion and the second convex portion formed to overlap the first convex portion is relatively large by 5 μm or more from relatively small microorganisms of about 100 nm. It can have a bactericidal action on microorganisms.

Of course, depending on the size of the target microorganism, only recesses having a two-dimensional size in the range of more than 20 nm and less than 100 nm may be formed. A mold for forming such a convex portion can be produced, for example, as follows.

Anodize with a neutral salt aqueous solution such as ammonium tartrate aqueous solution (ammonium borate, ammonium citrate etc.) or an organic acid with a low degree of ion dissociation (maleic acid, malonic acid, phthalic acid, citric acid, tartaric acid etc) To form a barrier-type anodic oxide film, remove the barrier-type anodic oxide film by etching, and then anodize with a predetermined voltage (the voltage of the second level described above) to obtain a two-dimensional size. Recesses in the range of more than 20 nm and less than 100 nm can be formed.

For example, using an aluminum film containing 1 mass% of Ti as the aluminum film, the barrier type anodic oxide film is formed by performing anodic oxidation at 100 V for 2 minutes using an aqueous solution of tartaric acid (concentration 0.1 mol / l, temperature 23 ° C.) Form Thereafter, the barrier type anodic oxide film is removed by etching for 25 minutes using a phosphoric acid aqueous solution (concentration 10 mass%, temperature 30 ° C.). After that, similarly to the above, an aqueous solution of oxalic acid (concentration 0.3 mass%, temperature 10 ° C.) is used as the anodic oxidation solution, anodic oxidation at 20 V for 52 seconds, etching using the above etching solution for 5 minutes alternately. By repeating anodization five times and etching four times, it is possible to uniformly form a recess having a two-dimensional size of about 50 nm.

As described above, moth-eye molds capable of forming various moth-eye structures can be manufactured.

Next, with reference to FIG. 6, a method of manufacturing a synthetic polymer film using the moth-eye mold 100 will be described. FIG. 6 is a schematic cross-sectional view for explaining a method for producing a synthetic polymer film by a roll-to-roll method. Hereinafter, a method of producing a synthetic polymer film on the surface of a base film as a workpiece using the above-mentioned roll type will be described, but a method of producing a synthetic polymer film according to an embodiment of the present invention is Other shapes of shapes can be used to produce synthetic polymer films on the surface of various workpieces.

First, a cylindrical moth-eye mold 100 is prepared. The cylindrical moth-eye mold 100 is manufactured by, for example, the manufacturing method described with reference to FIG.

As shown in FIG. 6, in a state where the base film 42 to which the ultraviolet curing resin 34 'is applied is pressed against the moth-eye mold 100, the ultraviolet curing resin 34' is irradiated with ultraviolet (UV) radiation. Cure the resin 34 '. As ultraviolet-ray cured resin 34 ', acrylic resin can be used, for example. The base film 42 is, for example, a PET (polyethylene terephthalate) film or a TAC (triacetyl cellulose) film. The base film 42 is unrolled from an unrolling roller (not shown), and then an ultraviolet curing resin 34 'is applied to the surface, for example, by a slit coater or the like. The base film 42 is supported by

support rollers

46 and 48, as shown in FIG. The

support rollers

46 and 48 have a rotation mechanism and transport the base film 42. Further, the cylindrical moth-eye mold 100 is rotated at a rotational speed corresponding to the transport speed of the base film 42 in the direction indicated by the arrow in FIG.

Thereafter, by separating the moth-eye mold 100 from the base film 42, the synthetic polymer film 34 to which the inverted moth-eye structure of the moth-eye mold 100 is transferred is formed on the surface of the base film 42. The base film 42 with the synthetic polymer film 34 formed on the surface is wound up by a winding roller (not shown).

The surface of the synthetic polymer film 34 has a moth-eye structure in which the nano surface structure of the moth-eye mold 100 is inverted. The

synthetic polymer films

34A and 34B shown in FIGS. 1 (a) and 1 (b) can be produced according to the nano surface structure of the moth-eye mold 100 used. The material for forming the synthetic polymer film 34 is not limited to an ultraviolet curable resin, and a visible light curable photocurable resin can be used, or a thermosetting resin can also be used.

The bactericidal property of the synthetic polymer film having a moth-eye structure on the surface is correlated not only with the physical structure of the synthetic polymer film but also with the chemical properties of the synthetic polymer film. For example, the applicant of the present application has, as chemical properties, the contact angle of the surface of the synthetic polymer film (Patent Document 5), the concentration of nitrogen element contained in the surface (Patent Document 6), and the concentration of nitrogen element, further ethylene. A correlation was found with the content of oxide units (—CH ₂ CH ₂ O—) (Patent Document 7).

The SEM image shown by the said patent document 6 (FIG. 8) in FIG. 7 is shown. FIGS. 7 (a) and 7 (b) are views showing SEM images of Pseudomonas aeruginosa that has died on the surface having the moth-eye structure shown in FIG. 1 (a) as observed by SEM (scanning electron microscope).

From these SEM images, it can be seen that the tip of the convex portion invades the cell wall (outer membrane) of P. aeruginosa. Also, looking at FIGS. 7 (a) and 7 (b), it does not appear that the convex part has pierced the cell wall, but it looks as if the convex part has been taken into the cell wall. This may be explained by the mechanism suggested in Supplemental Information of Non-Patent Document 1. That is, when the outer membrane (lipid bilayer membrane) of a gram-negative bacterium is deformed in close proximity to the convex portion, the lipid bilayer membrane locally resembles a first-order phase transition (spontaneous reorientation) An opening may be formed in a portion close to the projection, and the projection may intrude into the opening. Alternatively, the convex part may be taken up by a mechanism (endocytosis) which takes in a substance having polarity (including a nutrient source) that the cell has.

When the present inventor further examined a synthetic polymer membrane suitably used for sterilizing a liquid containing water, the synthetic polymer membranes described in Patent Documents 5 to 7 have mass productivity (transferability) and It has been found that there is room for improvement in water resistance.

The synthetic polymer films described in Patent Documents 5 to 7 use an acrylate containing elemental nitrogen and / or elemental fluorine. As a cause of the decrease in transferability and / or water resistance, the contribution of quaternary ammonium salt, amino group, amide group and urethane bond containing nitrogen element is considered. A compound containing a quaternary ammonium salt or an amino group or an amido group has a high permeability to the release agent, so there is a concern that the releasability may be reduced. In addition, since the compound having a urethane bond has a relatively high viscosity, it tends to lower the releasability. Therefore, productivity declines when mass producing by roll-to-roll method. In addition, since the compound containing nitrogen element has high polarity, it acts against water resistance. On the other hand, when an acrylate containing a fluorine element is used, it works favorably for the releasability, but the water repellency is high and it becomes difficult for water to penetrate. As a result, there is a concern that the effect of sterilizing the liquid containing water may be weakened.

Therefore, the present inventor manufactured various synthetic polymer films using acrylate (including methacrylate) containing neither nitrogen element nor fluorine element, and evaluated transferability and water resistance as well as sterilization. Sample films having different contents of water-soluble monomers and / or ethylene oxide units (-CH ₂ CH ₂ O-, hereinafter sometimes referred to as "EO units") contained in the synthetic polymer film and crosslink density were prepared.

Here, the water-soluble monomer refers to one in which the amount of water (about 20 ° C.) required to dissolve 1 g or 1 ml of monomer is less than 100 ml. As the water soluble monomer, one having less than 30 ml of water (about 20 ° C.) required to dissolve 1 g or 1 ml of monomer is preferable.

The water soluble monomer has a hydroxyl group, a carbonyl group and / or a carboxyl group. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate and 4-hydroxybutyl acrylate. Examples of the monomer having a carbonyl group include 2-acetoacetoxyethyl methacrylate and the like. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, 2-methacryloyloxyethyl succinic acid and the like.

[Synthetic polymer membrane]
The sample film which has a structure similar to the film 50A shown to Fig.1 (a) was produced using the ultraviolet curable resin from which a composition differs. The raw materials used are shown in Table 1.

As sample films of synthetic polymer films, as in the synthetic polymer films described in Patent Documents 5 to 7, reference examples 1 to 4 containing nitrogen and / or fluorine elements, transferability and / or water resistance are improved Examples 1 to 9 and Comparative Examples 1 to 9 were prepared. The compositions of Reference Examples 1 to 4 are shown in Table 2, the compositions of Examples 1 to 9 in Table 3, and the compositions of Comparative Examples 1 to 9 in Table 4. In Table 2, it is shown that (N) after the abbreviation of acrylic monomer contains a nitrogen element and (F) contains a fluorine element. In Comparative Example 1, the same ultraviolet curable resin as in Example 1 was used, and the moth-eye structure was not formed. That is, the sample film of Comparative Example 1 is a film (flat plate) having a flat surface.

As the base film 42A, a PET film (A4300 manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm was used. The synthetic polymer film was produced by the same method as that described with reference to FIG. 6 using the moth-eye mold 100A to produce a synthetic polymer film 34A having a moth-eye structure on the surface. The exposure dose was about 200 mJ / cm ² (based on light having a wavelength of 375 nm). In each sample film, D _p was about 200 nm, D _int was about 200 nm, and D _h was about 150 nm. In all cases, a synthetic polymer film was produced without using any solvent.

The evaluation results of bactericidal property, transferability and water resistance, and the content of water-soluble monomer unit and / or ethylene oxide unit (EO unit) are shown in Tables 5 to 7 below for each sample film. Table 5 shows Reference Examples 1 to 4, Table 6 shows Examples 1 to 9, and Table 7 shows Comparative Examples 1 to 9.

[Evaluation of sterilization]
The bactericidal activity of the bacterial solution (water) scattered on the sample film was evaluated. Since the bactericidal property when the sample film to which the bacterial solution was applied was left in the air at room temperature was evaluated, the influence of drying is added. Here, the bactericidal activity against Staphylococcus aureus was evaluated. The specific evaluation method is as follows. An experiment was performed at N = 3 for each sample film.
(1) Bacterial fluid containing S. aureus was prepared using 1/500 NB medium such that the initial number of bacteria was 1E + 06 CFU / mL.
(2) 10 μL of the above bacterial solution was dropped onto each sample film (5 cm square).
(3) After leaving for 15 minutes in the air at room temperature (about 25 ° C.), the SCDLP medium was flushed on a sample film to wash out the bacteria (washout solution).
(4) The washout solution was appropriately diluted with PBS, cultured on a standard agar medium or the like, and the number of bacteria was counted.

The bactericidal properties were evaluated on the basis of the bactericidal properties of the reference film. As a reference film, a 50 μm-thick PET film (A4300 manufactured by Toyobo Co., Ltd.) used as a base film was used. The number of bacteria was counted in the above-mentioned procedure for PET film, and the bactericidal property of each sample film was evaluated by the ratio (%) of the number of bacteria of each sample film to the number of bacteria obtained for this PET film. Specifically, the viable cell rate was determined according to the following formula.
Viable cell ratio (%) = number of bacteria of each sample film (total of N = 3) / number of bacteria of PET film (total of N = 3) x 100

The criteria for determining bactericidal properties were とした: 0%,: 0: more than 0% and less than 10%, Δ: 10% or more and less than 50%, x: 50% or more based on the viable cell rate. That is, if the viable cell rate was less than 50%, it was considered as usable.

[Evaluation of transferability]
In order to evaluate the transferability, an aluminum film (thickness: about 1 μm) is formed on a glass substrate (about 5 cm × about 5 cm), and this aluminum film is alternately repeated by anodic oxidation and etching, similarly to the above. porous alumina layer (D _p is about 200 nm, D _int of about 200 nm, D _h is approximately 150 nm) were formed. The surface of the obtained porous alumina layer was subjected to oxygen plasma cleaning (100 W, 25 seconds), and the contact angle to water was adjusted to 100 ° to 110 °. This is to reduce the releasability of the surface of the mold to the ultraviolet curable resin.

A synthetic polymer film was produced ten times on a PET film using an ultraviolet curable resin. The formation of a synthetic polymer film on a PET film is expressed as transfer of the synthetic polymer film onto a PET film. For ultraviolet irradiation, a UV lamp manufactured by Fusion UV Systems (product name: LIGHT HANMAR 6J6P3) was used, and the exposure dose was about 200 mJ / cm ² (based on light at 375 nm). Transfer is performed manually, transferred ten times, and sense of lightness at transfer (degree of force required to peel the mold from the synthetic polymer film), and index of surface condition of the mold at transfer And
○: No change after 10 transfers.
Fair: There is a tendency for the film to become heavy when peeling off the mold after 10 transfers, but there is no occurrence of a defect such as a synthetic polymer film (ultraviolet curable resin) remaining on the surface of the mold.
X: A defect occurs in which the synthetic polymer film remains on the surface of the mold during 10 times of transfer.
××: A problem occurs in which the synthetic polymer film remains on the entire surface of the mold during 10 times of transfer.
Here, 〇 and とした were accepted.

[Evaluation of water resistance]
Each sample film was immersed in water and allowed to stand at 37 ° C. for 72 hours, then removed from the water, and the state of each sample film was visually observed.
○: There was no change from before immersion.
Fair: There is whitening but there is no part where the synthetic polymer film is peeled from the base film.
X: There is a portion where the synthetic polymer film is peeled from the base film.
×: The synthetic polymer film is peeled off from the base film over almost the entire surface.
Here, the ones with the judgment of ○ or とした were made usable.

Crosslink density
The synthetic polymer film produced here is formed of an ultraviolet curable resin containing a polyfunctional acrylate, and thus has a crosslinked structure (network structure). As well known, the crosslink density of a polymer having a crosslink structure is a temperature giving Er ′ (Pa) as the minimum value of the dynamic storage elastic modulus E ′ in a temperature range exceeding the glass transition temperature. It is calculated | required from the formula of n = Er '/ (3 * R * Tr) by making Tr (K) and the gas constant R into 8.3 J / mol * K.

When it is difficult to specify the minimum value of the dynamic storage elastic modulus E 'in the temperature range exceeding the glass transition temperature, the minimum value of the dynamic storage elastic modulus E' in the temperature range exceeding the glass transition temperature is Er '. (Pa), and the minimum temperature for giving Er 'may be Tr (K).

Here, the dynamic storage elastic modulus Er '(Pa) is determined by DMA (Dynamic Mechanical Analysis: referred to as dynamic mechanical analysis or dynamic viscoelasticity measurement). Here, it asked as follows.

Using a visco-elasticity measuring device (product name: DMA7100) manufactured by Hitachi High-Tech Science, in the tensile mode, under the conditions of measurement temperature range -50 ° C to 250 ° C, temperature rising rate 5 ° C / min, and frequency 10Hz The temperature change of the dynamic storage modulus E 'was measured. The minimum value (typically, the minimum value) of the dynamic storage modulus E 'in the temperature range above the glass transition temperature Tg is the dynamic storage modulus Er', and the minimum temperature giving Er 'is Tr (K) did. The glass transition temperature Tg was determined, for example, as a temperature at which the loss elastic modulus E ′ ′ takes a maximum value (peak value). The test piece had a length of 35 mm, a width of 5 mm, and a thickness of 1 mm, and the unclamped portion had a length of 20 mm.

The result of having measured temperature dependence of dynamic storage elastic modulus E 'of a synthetic polymer film of Example 1 in Drawing 8 is shown. In the temperature range above the glass transition temperature (around room temperature), the dynamic storage modulus E ′ decreases and takes a local minimum value at 91 ° C. (Tr = 91 + 273 K). The dynamic storage modulus Er ′ at 91 ° C. is 53 MPa. From these values, according to the above equation, the crosslink density n is 5.8 × 10 ⁻³ mol / cc. In the same manner, the crosslink density was determined for Reference Examples 1 to 4, Examples 1 to 9, and Comparative Examples 1 to 9.

In Tables 5 to 7, Tr is expressed in degrees Celsius (° C.), but the absolute temperature (K) is used to calculate the crosslink density. Moreover, “water soluble m amount” in Tables 5 to 7 represents the mass% of the water soluble monomer with respect to the whole of each ultraviolet curable resin, and “EO amount” represents ethylene oxide units with respect to the whole of each ultraviolet curable resin ( It represents the mass% of the EO unit).

See Table 5.

The synthetic polymer films of Reference Examples 1 to 4 are produced using an acrylic monomer containing an element of nitrogen and / or an element of fluorine, and the element has a crosslinked structure containing an element of nitrogen and / or an element of fluorine. Also, these synthetic polymer membranes contain water soluble monomer units and EO units. The "water-soluble monomer unit" refers to a structural unit after the water-soluble monomer is polymerized.

The reference examples 1 to 3 containing the nitrogen element have excellent bactericidal properties but have poor transferability. Although the reference example 4 containing a fluorine element is excellent in transferability and water resistance, its bactericidal property is low. It is presumed that this is because bacteria contained in water are hard to approach the surface of the synthetic polymer film due to the water repellent effect of the fluorine element.

Next, refer to Table 6.

The synthetic polymer films of Examples 1 to 9 have ethylene oxide units and / or water-soluble monomer units in the cross-linked structure without containing any of the nitrogen element and the fluorine element. The crosslink density n of any of the synthetic polymer films is in the range of 2.8 × 10 ⁻³ mol / cc to 9.5 × 10 ⁻³ mol / cc, and any of bactericidal property, transferability and water resistance Is also at a usable level.

From the viewpoint of sterilization, the crosslink density n is preferably 8.4 × 10 ⁻³ mol / cc or less, and more preferably 5.8 × 10 ⁻³ mol / cc or less.

From the viewpoint of water resistance, the crosslink density n is preferably 3.7 × 10 ⁻³ mol / cc or more.

The total content of ethylene oxide units and water-soluble monomer units contained in the cross-linked structure is over 40% by mass. From the fact that the water resistance of Examples 2, 4 and 5 is somewhat inferior, it is considered that the total content of the ethylene oxide unit and the water-soluble monomer unit contained in the crosslinked structure is preferably 70% by mass or less.

The dynamic storage moduli Er 'are all in the range of more than 20 MPa and less than 90 MPa. Since the bactericidal properties of Examples 6 and 7 are somewhat inferior, it is considered preferable that the dynamic storage elastic modulus Er 'is less than 75 MPa.

Example 9 is produced from what mixed the acrylic monomer which has a siloxane bond with the ultraviolet curable resin of Example 6, and its bactericidal property is improving. The compound (silicone compound) which has a siloxane bond is often used as a material which provides mold release property like a fluorine-type compound. From the comparison between Example 9 and Example 6, it is considered that releasability, that is, transferability can be improved by using a monomer having a siloxane bond without sacrificing sterilization.

Next, refer to Table 7.

The synthetic polymer films of Comparative Examples 1 to 9 do not contain any of the nitrogen element and the fluorine element in the cross-linked structure, like the synthetic polymer films of the examples. The synthetic polymer membranes of Comparative Examples 1 to 7 have ethylene oxide units and / or water-soluble monomer units.

The synthetic polymer film of Comparative Example 1 is a synthetic polymer film in which a moth-eye structure is not formed using the same ultraviolet curable resin as that of Example 1, and has a low sterilizing property. That is, it is understood that the bactericidal property can be imparted or improved by the moth-eye structure of the surface of the synthetic polymer film.

The synthetic polymer membranes of Comparative Examples 2 to 4 have excellent bactericidal properties but have poor water resistance. The crosslink density n of these synthetic polymer films is 2.3 × 10 ⁻³ mol / cc or less. From the comparison with the examples, it is understood that when the crosslink density n is too small, the water resistance is lowered.

The synthetic polymer membranes of Comparative Examples 5 to 7 are excellent in water resistance but poor in bactericidal property. The crosslinking density n of these synthetic polymer films is 11.0 × 10 ⁻³ mol / cc or more. As is clear from the graph showing the relationship between the crosslink density and the viable cell ratio of the synthetic polymer films of Examples 1 to 8 and Comparative Examples 2 to 7 shown in FIG. Is found to decrease.

From this, in order for water to be sterilized by contact with the surface of the synthetic polymer film, the surface of the synthetic polymer film should have such a degree of hydrophilicity and crosslink density that it can be swollen by water. Is considered preferable. That is, the probability that the polymer chain on the surface of the synthetic polymer membrane interacts with the bacteria contained in water is considered to increase, as a result, the bactericidal property is improved.

The synthetic polymer membranes of Comparative Examples 8 and 9 do not contain ethylene oxide units and have poor sterilizing properties. From this, it is considered that the ethylene oxide unit contributes to the sterilization.

The synthetic polymer membrane according to the embodiment of the present invention can sterilize water attached to the surface in a short time. Therefore, the infection can be suppressed / prevented by arranging on the inner surface of the hand insertion space of the hand dryer.

The synthetic polymer membrane according to the embodiment of the present invention is suitably used in applications where it is desired to sterilize water in a short time.

34A, 34B Synthetic polymer film 34Ap,

34Bp Convex part

42A,

42B Base film

50A,

50B film

100, 100A, 100B Moss eye mold

Claims

A synthetic polymer membrane comprising a surface having a plurality of first projections,
When viewed in the normal direction of the synthetic polymer film, the two-dimensional size of the plurality of first protrusions is in the range of more than 20 nm and less than 500 nm,
It has a crosslinked structure, and the crosslinked structure does not contain elemental nitrogen and elemental fluorine, and has ethylene oxide units and / or water-soluble monomer units,
The minimum value of the dynamic storage elastic modulus E ′ in the temperature range exceeding the glass transition temperature is Er ′ (Pa), the minimum temperature giving Er ′ is Tr (K), and the gas constant R is 8.3 J / mol · K The crosslinking density n calculated from the formula n = Er '/ (3 · R · Tr) is in the range of 2.8 × 10 −3 mol / cc to 9.5 × 10 −3 mol / cc. , Synthetic polymer membrane.
The synthetic polymer membrane according to claim 1, wherein the crosslink density n is 8.4 × 10 -3 mol / cc or less.
The synthetic polymer membrane according to claim 1, wherein the crosslink density n is 5.8 × 10 −3 mol / cc or less.
The synthetic polymer membrane according to any one of claims 1 to 3, wherein the crosslink density n is at least 3.7 10-3 mol / cc.
5. The synthetic polymer according to any one of claims 1 to 4, wherein the total content of ethylene oxide units and water-soluble monomer units contained in the crosslinked structure with respect to the entire synthetic polymer film is more than 40% by mass. Molecular film.
The synthetic polymer film according to claim 5, wherein the total content of the ethylene oxide unit and the water-soluble monomer unit contained in the crosslinked structure with respect to the entire synthetic polymer film is 70% by mass or less.
The synthetic polymer membrane according to any one of claims 1 to 6, wherein the dynamic storage modulus Er 'is more than 20 MPa and less than 90 MPa.
The synthetic polymer membrane of claim 7, wherein said dynamic storage modulus Er 'is less than 75 MPa.
The synthetic polymer membrane according to any one of claims 1 to 8, wherein the crosslinked structure comprises a monomer unit having a siloxane bond.
A method of sterilizing the liquid by bringing the liquid containing water into contact with the surface of the synthetic polymer membrane according to any one of claims 1 to 9.