JP2023018701A - Formation method of treatment layer - Google Patents

Abstract

To provide a formation method of a treatment layer having a sterilization ability on a substrate surface by a comparatively simple technique.SOLUTION: A formation method of a treatment layer for forming a treatment layer having a sterilization ability on a substrate surface, includes: a crystal grain precipitation step of obtaining an aqueous solution obtained by dissolving a bath component comprising a water-soluble zinc salt and an amine-based or borane-based reducing agent as a main component in water and precipitating a crystal grain of zinc oxide in the aqueous solution; and a treatment layer formation step of coating the crystal grain obtained in the crystal grain precipitation step together with a binder on the substrate surface so as to form th treatment layer.SELECTED DRAWING: Figure 1

Description

The present invention, for example, relates to a method for forming a treated layer having bactericidal activity on the surface of a substrate.

Patent Documents 1, 2 and 3 can be cited as prior art relating to this type of treatment layer having bactericidal activity.
Patent Document 1 is an application relating to an antibacterial composition containing a metal-resin composite material which is a composite of metal particles (a1) and a phenolic resin (a2) and has a metal atom-oxygen atom-carbon atom bond. , metal particles (a1) are preferably at least one selected from the group consisting of silver, copper, tin, nickel, iron, zinc, manganese and polyimide. This antibacterial composition can also be used by applying it to the surface of a substrate.

The technology disclosed in Patent Document 2 relates to a surface exhibiting a novel surface topography that kills cells upon contact, and is a method for producing a synthetic sterilizing surface that includes an array of nanospikes having nano-order sizes. Regarding.

On the other hand, Patent Document 3 discloses the use of zinc oxide particles as a substance having bactericidal activity.
The technique disclosed in this document is an aqueous solution containing zinc ions, chloride ions and sulfate ions, adjusting the molar ratio of the chloride ions and the sulfate ions to a predetermined ratio, precipitating a precursor, and precipitating the precursor. It can be obtained by hydrothermally treating an aqueous solution containing the body at a predetermined temperature.
The particle size of zinc oxide particles that can be obtained by this technique is about 10 μm to 500 μm.

JP 2017-71562 A Japanese Patent Publication No. 2017-503554 JP 2007-223873 A

The techniques described in the aforementioned Patent Documents 1, 2, and 3 each have the following drawbacks.

In the technique disclosed in Patent Document 1, by using the described antibacterial composition, an antibacterial resin layer can be formed on the surface of the substrate, but the production process of the composition becomes complicated, and it becomes an effective bactericidal ingredient. The effective area is limited because the metal is exposed on the surface while being covered with resin.

Although WO 2005/010021 mentions zinc oxide as a material to form a synthetic antiseptic surface, it is not clear how this material can be used to obtain a truly antiseptic surface.

The technique disclosed in Patent Document 3 relates to a method for obtaining zinc oxide particles as a sterilizing component, but the particle size of the obtained particles is large, and the sterilizing ability of these particles is not due to nanospike formation disclosed in Patent Document 2. , is understood to be due to the inherent bactericidal ability of the zinc oxide particles as a material.

In view of this situation, the main object of the present invention is to provide a method for forming a treated layer having bactericidal activity on the surface of a substrate by a relatively simple technique.

The first characteristic configuration of the present invention is
a crystal grain precipitating step of obtaining an aqueous solution obtained by dissolving a bath component mainly composed of a water-soluble zinc salt and an amine-based or borane-based reducing agent in water, and precipitating crystal grains of zinc oxide in the aqueous solution;
The method comprises a treated layer forming step of applying the crystal grains obtained in the crystal grain deposition step together with a binder to the substrate surface to form a treated layer.

Hereinafter, an amine-based or borane-based reducing agent may be simply referred to as a reducing agent.

According to this characteristic configuration, in the crystal grain precipitation step, an aqueous solution containing at least a water-soluble zinc salt and a reducing agent is prepared to grow crystal grains of zinc oxide.
Here, the processing required is preparation of an aqueous solution, and crystal grains can be produced easily. Moreover, in an aqueous solution in which a water-soluble zinc salt and a reducing agent are mixed in an appropriate ratio, zinc oxide crystals with spike-like protrusions protruding from the periphery of the crystal nuclei, which the inventor calls nanospikes, are formed ( (see Figures 3-6).

As can be seen from FIGS. 3 to 6, this crystal grain has a form in which spike-like protrusions protrude from the periphery of the crystal nucleus, and the protrusions (nanospikes, which will be described later) are several to several hundred nm in size. , nano-order. As a result, it exhibits bactericidal activity.

The second characteristic configuration of the present invention is
The water-soluble zinc salt is zinc nitrate hexahydrate, and the amine-based or borane-based reducing agent is either dimethylamine borane (DMAB) or hexamethylenetetramine (HMTA), or both. be.

According to this characteristic configuration, the desired product can be obtained using these inexpensive and readily available starting materials (zinc nitrate hexahydrate, dimethylamine borane, or hexamethylenetetraamine).

The third characteristic configuration of the present invention is
In the crystal grain precipitation step, while adjusting the concentrations of the water-soluble zinc salt and the amine-based or borane-based reducing agent in the aqueous solution,
The point is that the growth time of the crystal grains is adjusted to adjust the average grain size of the crystal grains.

As shown in the embodiments described later, the crystal particles of zinc oxide according to the present invention greatly depend on the concentration relationship between the water-soluble zinc salt and the reducing agent, which are starting materials, and the growth time.
In principle, it is necessary to adjust the concentration of the starting materials so that the formation of crystal grains is not excessive or deficient.
Therefore, crystal grains having a desired grain size can be obtained by appropriately adjusting the concentration of the starting material and the growth time.

The fourth characteristic configuration of the present invention is
In the aqueous solution,
The concentration of the water-soluble zinc salt is set to 5 mmol/L or more and 200 mmol/L or less,
The molar ratio of the water-soluble zinc salt and the amine-based or borane-based reducing agent is 0.1:1 or more and 60:1 or less,
The point is to maintain the temperature of the aqueous solution at 75°C or higher and 95°C or lower.

As noted above, the concentration and ratio of the starting materials in the aqueous solution are factors that determine the particle size formed, and when the concentration of this water-soluble zinc salt is lower than 5 mmol/L, the desired crystal particles are formed. may be difficult to obtain. On the other hand, when it is higher than 200 mmol/L, the particle size tends to be too small.

On the other hand, regarding the ratio of reducing agent to water-soluble zinc salt, a molar ratio lower than 0.1:1 or higher than 60:1 promotes an appropriate reaction between water-soluble zinc salt and reducing agent. It is easy to become difficult. As for the temperature of the aqueous solution, the predetermined reaction proceeds favorably within this temperature range. Therefore, by selecting the concentration of the water-soluble zinc salt and the molar ratio between the water-soluble zinc salt and the reducing agent as described above, and controlling the aqueous solution within a predetermined temperature range, the inventors can easily and reliably A crystal grain structure can be obtained with a grain size of .

The fifth characteristic configuration of the present invention is
The crystal grain growth time in the crystal grain precipitation step is set to 30 minutes or more and 6 hours or less.

According to this characteristic configuration, the nanospikes aimed by the inventors can be formed within the range of 30 minutes to 6 hours.
Here, if it is shorter than 30 minutes, the growth may be insufficient and the sterilization performance may be inferior. On the other hand, if it is longer than 6 hours, it grows too much.

The sixth characteristic configuration of the present invention is
The point is that zinc oxide particles are mixed into the aqueous solution.

According to this characteristic configuration, in the crystal grain precipitation step, the growth of the crystal grains can be promoted with the mixed zinc oxide particles as nuclei. When zinc oxide particles are mixed in this way, the crystal grains tend to have a smaller crystal size than when zinc oxide particles are not mixed. In other words, by adding zinc oxide particles, it is possible to increase the number of core particles, but when the raw material concentration is the same, the larger the amount of zinc oxide particles added, the smaller the particle size tends to be. show.

The seventh characteristic configuration of the present invention is
The coating liquid applied to the surface of the substrate is formed by mixing the crystal particles, the binder and a volatile solvent,
Regarding the mass of the crystal particles and the mass of the binder in the coating liquid,
[mass of crystal grains]/[mass of crystal grains]+[mass of binder]] is set to 0.5 or more and 0.9 or less.

According to this characteristic configuration, as will be described later with reference to FIG. 7, in the treated layer, the crystal grains are kept attached to the base material surface while realizing a state in which the projections of the crystal grains protrude from the treated layer surface. can. If it is less than 0.5, the protrusions may be covered with the binder and deactivation may deteriorate. On the other hand, if it is larger than 0.9, the adhesion of crystal grains is poor.

The eighth characteristic configuration of the present invention is
A treated layer forming portion having the treated layer formed thereon is provided on the surface of the base material,
The thickness of the layer is equal to or greater than the thickness of the treatment layer, and the protection part is provided that is harder than the treatment layer.

The treatment layer according to the present invention is structurally susceptible to friction and the like, and the loss of nanospikes reduces the intended bactericidal activity.
Therefore, physical protection of the treatment layer becomes possible by providing a protection portion for the treatment layer forming portion. This type of protection part can achieve the purpose of protecting the treatment layer by making the layer thickness equal to or greater than the thickness of the treatment layer and by forming it from a material harder than the treatment layer.
As will be introduced later, this type of protective portion can be striped, grid-shaped, or the like, but for example, a large number of simple projections may be provided.

As described above, the treatment layer forming method described above can appropriately form a treatment layer having a nanospike structure on the substrate surface.

Additionally, this treatment layer is capable of inactivating one or more of Qβ phage, E. coli, Staphylococcus aureus, and filamentous fungi, as shown below.
This is the ninth characteristic configuration of the present invention relating to the deactivation method.

Explanatory drawing showing the formation process of the treatment layer Diagram showing reaction system of starting material 1 Figure showing the results of examination using starting material 1 Figure showing the results of examination using starting material 1 Figure showing the results of examination using starting material 2 Figure showing the results of examination using starting material 2 The figure which shows the formation state of a coating layer. The figure which shows another embodiment which formed the coating layer in the recessed part.

An embodiment of the present invention will be described based on the drawings.
FIG. 1 shows the formation process of the treatment layer 1 according to the present application.
As can be seen from the drawing, the method for forming the treated layer 1 according to the present invention includes (a) a crystal grain precipitation step and (b) a treated layer forming step.

(a) and (b) schematically show each step, and on the right side of those steps, for (a), a photograph of crystal grains 3 having nanospikes produced in this step is shown ( For b), a photograph of the treated layer 1 produced in this step is shown. All photographs herein are SEM photographs. Magnification is indicated by “×〇〇〇”. In this specification, the magnification of the photograph is basically “×3000”. However, the magnification of the photograph shown on the right side of FIG. 1(b) and the three photographs on the upper side of FIG. 3 is "×30000".

The above treated layer 1 is formed by adhering the crystal grains 3 to the base material 10 with the binder B. In the examples shown below, the base material 10 is polyimide. However, when the method of the present invention is adopted as the base material 10, any base material 10 can be obtained by selecting a binder B that allows the crystal grains 3 to adhere to the base material surface 10a as shown in another embodiment. be able to.

1. Crystal Particle Precipitation Step In this step, an aqueous solution 2 is obtained by dissolving a bath component mainly composed of a water-soluble zinc salt and an amine-based or borane-based reducing agent in water, and crystals of zinc oxide are obtained in the aqueous solution 2. Particles 3 are deposited. At the time of precipitation, for example, after the mixing operation, the aqueous solution 2 may be allowed to stand still to precipitate the crystal grains 3 (natural precipitation), or zinc oxide particles (hereinafter, referred to as The crystal grains 3 may be grown by mixing seed grains 5 . In FIG. 1(a), the mixed state of the seed particles 5 is indicated by a virtual line for this purpose.

As shown in FIG. 1(a), the aqueous solution 2 can be obtained by dissolving in water a bath component composed mainly of a water-soluble zinc salt and an amine or borane reducing agent. The figure shows an example in which the water-soluble zinc salt is zinc nitrate hexahydrate (Zn(NO ₃ ) _{2.6H 2} O) and the reducing agent is hexamethylenetetramine (HMTA) or dimethylamine borane (DMAB). is representatively shown.

In the following description, the starting material in which the water-soluble zinc salt is zinc nitrate hexahydrate and the reducing agent is hexamethylenetetramine (HMTA) is referred to as "starting material 1," and the water-soluble zinc salt is zinc nitrate 6. The starting material when it is a hydrate and the reducing agent is dimethylamine borane (DMAB) shall be referred to as "starting material 2".

When the aqueous solution 2 is obtained, the concentration of the solvent component is such that the concentration of the water-soluble zinc salt is 5 mmol/L (liter) or more and 200 mmol/L (liter) or less, and the molar ratio of the reducing agent to the water-soluble zinc salt is 0.1. : 1 or more and 60:1 or less.

After appropriately mixing and stirring, the resulting aqueous solution 2 is allowed to stand to grow a plurality of crystal particles 3 of zinc oxide. In practice, it is stirred for a predetermined time while being heated.

At this stage, the temperature of the aqueous solution 2 can be maintained at 75° C.-95° C., and the formation time of the crystal grains 3 can be 0.5-6 hours.
Inside the aqueous solution 2, a large number of crystal particles 3 of zinc oxide having nano-order nanospikes growing around the central nucleus are randomly precipitated. The size of the nanospikes can range from 0.1 μm to 5 μm. In the examples shown in FIGS. 3 to 6, the size is 1 μm or more and 5 μm or less.

2. Treated Layer Forming Step As shown in FIG. 1(b), the crystal grains 3 obtained in the crystal grain precipitation step are taken out from the aqueous solution 2 and coated on the surface 10a of the substrate 10 together with the binder B to form the treated layer 1. Form.
The photograph shown on the right side of the same figure, which will be described later, is shown in FIG. 7(c).

Below, 1. Manufacture of crystal grains, 2. Formation of treated layer, and 3. Examination of inactivation will be described in this order.
1. Regarding the production of crystal grains, an example using starting material 1 and starting material 2 as starting materials is shown, and 2. forming a treated layer shows an example using starting material 1 as the starting material.

1. Production of crystal grains1. -1 Use of Starting Material 1 When using the starting material 1, the reaction system for the formation of zinc oxide is as shown in FIG.
In this reaction system, hydrolysis of raw materials, formation of OH ^- and formation of zinc oxide due to interactions between zinc ions and OH ^- occur.

Table 1 shows the conditions of each example in this study.
In the table, "presence or absence of seed particles" means that "no" means spontaneous precipitation without adding seed particles 5, and "manufacturer, particle size and concentration" are shown for examples in which seed particles 5 are added.

Regarding the particle size of the seed particles 5, the seed particles 5 manufactured by Company A had a particle size of 20 nm, which was one type (Examples 2 and 4). On the other hand, the seed particles 5 manufactured by Company B had three particle sizes of 20 nm, 60 nm and 280 nm (Examples 3 and 6).

Concerning the concentration of the seed particles 5, three levels of 0.003 wt%, 0.001 wt%, and 0.0002 wt% were used for the seed particles 5 manufactured by Company A (Example 2). Regarding the seed particles 5 manufactured by Company B, one level of 0.01 wt% was used (Examples 3, 4, and 6).
Here, the concentration (wt%) of the seed particles 5 is [mass of the seed particles 5 added]/[mass of the seed particles 5 added] + [mass of zinc nitrate hexahydrate] + [mass of HMTA or DMAB mass]+[mass of solvent]].

In Table 1, the numerical values for starting materials are concentrations (mmol/500 mL (milliliters)) of each component (zinc nitrate hexahydrate and hexamethylenetetramine).
That is, each component was mixed with the amount of water in the aqueous solution 2 set to 500 g.

The deposition conditions were 75° C. and 6 hours. However, the inventors have confirmed that the desired precipitation of the crystal grains 3 occurs within the range of 0.5 to 6 hours.

Photographs of crystal grains 3 obtained for each example shown in Table 1 are shown in FIGS. 3 to 6. FIG.

FIG. 3 shows the state of crystal grains 3 according to the presence or absence of seed grains 5 and changes in grain size. The figure shows Example 1, Example 5, and Example 6. FIG. For Example 6, three different particle sizes are shown.

As can be seen from this figure, regardless of the presence or absence of the seed particles 5, when the method of the present invention is employed, spike-shaped zinc oxide crystal grains in which spike-shaped protrusions protrude from the periphery of the crystal nucleus can be obtained. 3 can be formed. Furthermore, since the number of crystal nuclei formed is smaller when the seed particles 5 are not added, relatively large spike-like crystal particles 3 can be obtained.
Moreover, when the seed particles 5 were added, the spike-like crystal particles 3 tended to be smaller because the number of crystal nuclei increased. Also, the larger the grain size of the seed grains 5, the larger the crystal grains 3 become.

FIG. 4 shows the concentration of the seed particles 5 when the seed particles 5 are added and the state of the crystal grains 3 as the particle size changes at a predetermined concentration.
In the figure, Example 2, Example 3, Example 4 and Example 6 are shown. For Example 2, three levels with different densities are shown. For Examples 3 and 6, three types each having different particle sizes are shown.

As is clear from this figure, when the seed particles 5 were added, the formed crystal grains 3 tended to be smaller as the concentration of the seed particles 5 increased. Also, the larger the grain size of the seed grains 5, the larger the crystal grains 3 become.

1. -2 Use of starting material 2 The reaction system in this case is as follows.

B. Decomposition of zinc nitrate hexahydrate,
[Chemical 1]
Zn( _NO3 ) _{2.6H2O →} Zn2 ⁺ + _2NO3 + _6H2O

(b) hydrolysis of dimethylamine borane,
[Chemical 2]
( _CH3 ⁾ _{2.NHBH3 + 2H2O} →( _CH3 ) _{2NH2 ++ HBO3} +5H ^{++ 6e-}

C. Generation ^of OH by the action of nitrate ions and water,
[Chemical 3]
NO ₃ ⁻ +H ₂ O+2e ⁻ →NO ₂ ⁻ +2OH ⁻

D. Formation of zinc oxide by interaction of zinc ions and OH ^- [Chemical 4]
Zn ²⁺ +2OH ⁻ →Zn(OH) ₂ →ZnO+2H ₂ O

As a result, crystal particles 3 can be obtained in the aqueous solution.

In this example, the following two items were examined.
B. State of crystal particles obtained when the amount ratio of the reducing agent to zinc is kept constant (1:1), the amount in the aqueous solution 2 is changed, and the concentration of the seed particles 5 is changed.

The results are shown in FIG.
The seed particles 5 were manufactured by Company B and had a particle size of 60 nm.

In the figure, the vertical axis indicates the amount ratio of the starting material 2 (expressed as Zn (mM)/DMAB (mM)). Zn (mM) indicates the amount of zinc nitrate hexahydrate in mmol and DMAB (mM) indicates the amount of dimethylamine borane in mmol. As indicated above, the amount of water in aqueous solution 2 is 500 g. The horizontal axis indicates the concentration (wt %) of the seed particles 5 . The definition of the concentration (wt %) of the seed particles 5 is the same as for the starting material 1 .

As can be seen from the figure, spike-shaped zinc oxide crystal grains 3 having spike-shaped protrusions protruding from the periphery of the crystal nuclei are obtained from the starting material 2 by adopting the method of the present invention. can be formed. Furthermore, when the seed particles 5 were added, the spike-like crystal particles 3 tended to be smaller than in the case of spontaneous precipitation because the number of crystal nuclei increased. Also, the lower the seed particle concentration, the larger the crystal grains 3 .

State of crystal grains obtained by changing the amount ratio of the reducing agent to zinc and the amount of these in the aqueous solution 2 while keeping the particle size and concentration of the seed particles 5 constant. The results are shown in FIG.
The seed particles 5 were manufactured by Company B and had a particle diameter of 60 nm, and the concentration thereof was 0.001 wt %.

In the figure, the vertical axis indicates the amount of dimethylamine borane, which is the reducing agent in the starting material 2, in mmol (expressed as DMAB [mM]). The horizontal axis indicates the amount of zinc nitrate hexahydrate in starting material 2 in mmol (denoted as Zn [mM]). As indicated above, the amount of water in aqueous solution 2 is 500 g.

As can be seen from the figure, spike-like zinc oxide crystal grains 3 having spike-like projections projecting from the periphery of the crystal nucleus were formed under any condition. Furthermore, it was found that the spike-like crystal particles 3 of zinc oxide are easier to obtain when the amount of dimethylamine borane, which is a reducing agent for zinc, is secured.

Process of Forming Treated Layer As shown in FIG. 1(b), a mixture of the crystal grains 3 obtained through the crystal grain forming process described above, the binder B and the solvent is obtained, coated on the substrate 10 and dried. A treated layer 1 was formed on a substrate 10 .

In the crystal grain precipitation step, a liquid mixture having the following composition was used. This example corresponds to Example 6 in which the seed particles 5 in Table 1 describing the starting material 1 had a particle size of 60 nm (top center in FIG. 3).

Aqueous solution composition for obtaining crystal particles Water-soluble zinc salt: Zinc nitrate hexahydrate
Concentration: 10mmol
Reducing agent: HMTA
Concentration: 10mmol
Seed particles 5: ZnO particles with a particle size of 60 nm Concentration: 0.001 wt%
Water: 500g

Table 2 below shows the amount ratio of each component of the mixed liquid obtained by mixing the crystal particles 3 used for coating with the binder B and diluting it with a solvent.
Binder B: Polystyrene Solvent: Toluene Substrate 10: Polyimide

Here, the crystal grain concentration is defined as the relationship between the mass of the crystal grains 3 and the mass of the binder B as follows.
[mass of crystal particles]/[[mass of crystal particles] + [mass of binder]]

Regarding the dilution of these mixtures with a solvent (specifically, toluene), the weights of solvents in Examples 7 to 10 were 4.5 g, 4.8 g, 5 g, and 3.9 g in the order listed.
In this example, the solid content is the crystal grains 3 and the binder B, and the concentration (solid content concentration) of these solid content in the mixed liquid is constant at 2.7% as shown in Table 2.

The results are shown in FIG.
Therefore, by setting the crystal grain concentration to 50% or more and 90% or less, it is possible to obtain the desired treated layer in which spikes are exposed on the surface.

Examination of deactivation ability Regarding the treated layer 1 obtained as described above, antiviral performance, bactericidal performance, and antifungal performance (hereinafter simply referred to as deactivation performance) were examined.
The viruses, fungi, and molds to be examined were as follows.

Target virus Qβ phage
(NBRC20012)
The virus was non-enveloped and the host was E. coli (Escherichia coil NBRC106373).
Target bacteria 1. Escherichia coli NBRC15034, a Gram-negative bacterium
Target bacteria 2 . Staphylococcus aureus, a Gram-positive bacterium (Staphylococcus aureus NBRC12732)
Target fungus 3 . Black mold (Aspergillus niger van tieghem NBRC105649) which is a filamentous fungus belonging to Fungi

As described above, Example 9 shown in Table 2 above was used to confirm its inactivating ability.

In order to confirm the inactivation ability, the viruses were quantitatively evaluated by the virus plaque method, and the target bacteria 1 and 2 were quantitatively evaluated by the colony count method.

For mold, a visual observation method was adopted. Specifically, 1. 2. spore fluid preparation; 2. processing time and conditions; The maintenance and evaluation methods are as follows.
1. The inoculum was seeded on a spore liquid-conditioned PDA agar medium and cultured at 30°C for 7 days.
The spores were collected with a 50 mg/L dioctyl sodium sulfosuccinate solution, and after counting the spore concentration with an optical microscope, the spore concentration was diluted to 1×10 5 /mL to prepare a spore solution for inoculation.
500 μL of spore solution for inoculum, 50 μL of PD liquid medium and 200 μL of 50 mg/L dioctyl sodium sulfosuccinate solution were added to the test piece to start the test.
2. Treatment time/conditions The product was allowed to stand in a constant temperature bath at 30°C, 100% humidity, and in a dark place. (Set the sample in the humidification box)
3. Maintenance and evaluation method 1
From the start of the test, visual observation evaluation and photography were performed twice a week. (Monday/Thursday)
50 μL of PD liquid medium was added for each evaluation.

Evaluation of antiviral performance Table 3 shows the evaluation (viral inactivation rate (%) after a predetermined period of time has elapsed from the initial stage).

As a result, almost 90% inactivation rate can be achieved for viruses in about 180 minutes.

Inactivation evaluation for target bacteria 1 and 2 Table 4 shows the evaluation (bacteria inactivation rate (%) after a predetermined period of time has elapsed from the initial stage).

As a result, for E. coli, an inactivation rate of 90% or more can be achieved in about 60 minutes, and an inactivation rate of 99% can be achieved in 180 minutes. In addition, although the inactivation rate is somewhat inferior to Staphylococcus aureus, approximately 90% is inactivated in 180 minutes.

Inactivation evaluation for mold With regard to black mold, which is a filamentous fungus belonging to fungi, the reference (aluminum base) was found to generate mold in 3 to 4 days, whereas mold growth continued for 17 days. was not accepted.

As described above, the treatment layer 1 targeted by the present invention is effective against viruses, Gram-negative bacteria, Gram-positive bacteria, and filamentous fungi.

[Another embodiment]
(1) In the above embodiments and examples, zinc nitrate hexahydrate was used as the water-soluble zinc salt. Zinc, zinc chloride, zinc acetate, zinc lactate and the like can also be used.

(2) In the above embodiments and examples, examples of hexamethylenetetramine (HMTA) and dimethylamine borane (DMAB) were shown as reducing agents, but trimethylamine borane (TMAB) and triethylamine borane (TEAB) ), etc. can also be used.

(3) In the above examples, the ratio of the reducing agent to the water-soluble zinc salt was mainly 1:1. A treatment layer can also be formed in the range of 1 to 60:1.

(4) In the above embodiments and examples, polyimide (PI) was used as the base material. , polytetrafluoroethylene (PTFE) can also be selected. Alternatively, a metal substrate may be used as the base material and a treated layer may be provided on the surface thereof.

(5) In the above embodiment, an example in which the surface of the substrate 10 is flat has been mainly described. The treated layer 1 provided in the concave portion may remain over time so that the sterilizing ability can be exerted.
In this configuration, the convex portion effectively becomes the protective portion, and the concave portion becomes the treated layer forming portion.
As shown in FIG. 8, the protective portion 21 and the treated layer forming portion 20 can be provided separately, and the treated layer 1 can be provided on the treated layer forming portion 20 without such abrasion. In this case, it is preferable that the protective portion 21 has a layer thickness equal to or greater than the thickness of the treatment layer 1 and is harder than the treatment layer 1 .

1 treated layer 2 aqueous solution 3 crystal grain 10 substrate 10a substrate surface 20 treated layer forming portion 21 protective portion B binder

Claims (9)

A method for forming a treated layer for forming a treated layer having bactericidal activity on a substrate surface,
a crystal grain precipitating step of obtaining an aqueous solution obtained by dissolving a bath component mainly composed of a water-soluble zinc salt and an amine-based or borane-based reducing agent in water, and precipitating crystal grains of zinc oxide in the aqueous solution;
A method of forming a treated layer, comprising a treated layer forming step of applying the crystal grains obtained in the crystal grain deposition step together with a binder onto the substrate surface to form a treated layer. 2. The treated layer according to claim 1, wherein said water-soluble zinc salt is zinc nitrate hexahydrate, and said amine-based or borane-based reducing agent is either one or both of dimethylamine borane and hexamethylenetetramine. Forming method. In the crystal grain precipitation step, while adjusting the concentrations of the water-soluble zinc salt and the amine-based or borane-based reducing agent in the aqueous solution,
3. The method of forming a treated layer according to claim 1, wherein the growth time of the crystal grains is adjusted to adjust the average grain size of the crystal grains. In the aqueous solution,
The concentration of the water-soluble zinc salt is set to 5 mmol/L or more and 200 mmol/L or less,
The molar ratio of the water-soluble zinc salt and the amine-based or borane-based reducing agent is 0.1:1 or more and 60:1 or less,
3. The method of forming a treated layer according to claim 1, wherein the temperature of said aqueous solution is maintained at 75[deg.] C. or more and 95[deg.] C. or less. 5. The method of forming a treated layer according to claim 4, wherein the growth time of the crystal grains in the crystal grain precipitation step is 30 minutes or more and 6 hours or less. 6. The method of forming a treated layer according to claim 1, wherein zinc oxide particles are mixed in the aqueous solution. The coating liquid applied to the surface of the substrate is formed by mixing the crystal particles, the binder and a volatile solvent,
Regarding the mass of the crystal particles and the mass of the binder in the coating liquid,
[mass of crystal particles] / [mass of crystal particles] + [mass of binder]],
7. The method of forming a treated layer according to any one of claims 1 to 6, wherein the ratio is 0.5 or more and 0.9 or less. A treated layer forming portion having the treated layer formed thereon is provided on the surface of the base material,
The method of forming a treatment layer according to any one of claims 1 to 7, wherein the treatment layer has a layer thickness equal to or greater than the thickness of the treatment layer, and a protective portion harder than the treatment layer is provided. A treatment layer is formed on the substrate surface by the method for forming a treatment layer according to any one of claims 1 to 8, and the treatment layer inactivates one or more of Qβ phage, Escherichia coli, Staphylococcus aureus, and filamentous fungi. inactivation method.

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