JP2017088509A - Antibacterial member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antibacterial member capable of killing bacteria at a short time compared with a time required for killing bacteria in prior arts, and maintaining the effect.SOLUTION: There are provided the antibacterial member comprising a base material and cuprous oxide nanoparticles arranged on the base material surface and having an average primary particle diameter equal to or less than 100 nm, and a production method of the antibacterial member comprising a step for preparing a colloidal dispersion of the cuprous oxide nanoparticles, and a step for coating the colloidal dispersion to the substrate and drying the coated colloidal dispersion.SELECTED DRAWING: None

Description

  The present invention relates to an antibacterial member containing cuprous oxide nanoparticles capable of exerting an effect of suppressing various bacteria and viruses as an active ingredient.

Due to the recent increase in hygiene ideas, fungi such as bacteria and fungi in food and pharmaceutical factories, buildings such as hospitals and nursing homes, food kitchen utensils, medical utensils, medical devices and even general household goods Antibacterial agents, antifungal agents, disinfectants, antiviral agents and the like are used for the spread and prevention of viruses.
In recent years, deaths due to viral infections such as MARS, SARS (severe acute respiratory syndrome), norovirus, avian influenza, etc. have been reported. The danger of a pandemic spreading out is screaming.
Therefore, it is desired to impart antibacterial and antiviral properties to various members not only in public facilities but also in general households.

In order to solve these problems, organic or inorganic antibacterial agents have been proposed.
In particular, for inorganic antibacterial agents, conventionally, metal ions such as silver ions (Ag ⁺ ), zinc ions (Zn ²⁺ ), and divalent copper ions (Cu ²⁺ ) suppress the growth of microorganisms, or microorganisms It is known to act against bacteria. Based on this knowledge, a number of antimicrobial materials in which these metal ions are supported on a substance such as zeolite or silica gel, and antimicrobial materials combining the above metals with titanium oxide having a photocatalytic action have been developed.
Examples of such a material include a paint containing an antiviral component containing calcium or magnesium oxide or hydroxide (Patent Document 1), and a paint containing fine particles carrying metal ions on an inorganic oxide (Patent Document). 2) is exemplified.

JP 2007-106876 A JP 2003-221304 A

However, in the method using calcium or magnesium oxide or hydroxide, it is difficult to develop antibacterial properties unless the content of the antibacterial component is 50 mass% or more with respect to the coating resin component. Thus, when it is contained in a large amount of oxide or hydroxide of calcium or magnesium, the coating film formed by coating and drying of the paint becomes hard, and its usage is limited.
In addition, in the case of a coating containing fine particles carrying metal ions on an inorganic oxide, it is necessary to stabilize the metal ions by mixing with other substances, so the ratio of copper ions contained in the composition However, since it is essential to include a metal ion stabilizer, the degree of freedom in designing the composition is reduced. In this case, since a large amount of fine particles need to be added in order to exhibit a desired effect, the stability of the coating film may be sacrificed.

  Then, in order to solve the said subject, this invention aims at providing the antibacterial member which can kill a microbe in a short time compared with a prior art, and can maintain the effect.

That is, the gist of the present invention is as follows.
The antibacterial member of the present invention includes a base material and cuprous oxide nanoparticles having an average primary particle size of 100 nm or less arranged on the surface of the base material.
Here, the average primary particle size is preferably 20 nm or less. Moreover, it is preferable that the said base material is fibrous form. Furthermore, it is preferable that the base material has a functional group capable of hydrogen bonding to the cuprous oxide nanoparticles on the surface thereof. Furthermore, the substrate is preferably a cellulose resin.

  The method for producing an antibacterial member of the present invention includes a step of preparing a colloidal dispersion of cuprous oxide nanoparticles, and a step of applying and drying the colloidal dispersion on a substrate.

  The antibacterial member of the present invention can suppress the growth of bacteria in a shorter time than the prior art, and can stably obtain such an inhibitory effect.

  Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The antibacterial member of the present embodiment includes a base material and cuprous oxide nanoparticles having an average primary particle size of 100 nm or less arranged on the surface of the base material.

Here, the cuprous oxide nanoparticles and the substrate are not particularly limited as long as the cuprous oxide nanoparticles are disposed on the substrate surface, but more specifically, such as hydrogen bonding and intermolecular force. It may be attached, adhered, adsorbed, supported, etc. by interaction.
In particular, from the viewpoint of maintaining the content of cuprous oxide nanoparticles, adhesion (described later) by hydrogen bonding between the cuprous oxide nanoparticles and the hydroxyl group of the substrate is preferable.

  The average primary particle size means an average value of primary particle sizes obtained for a plurality of primary particles by image analysis. Here, the primary particle diameter means particles of primary particles obtained from image data obtained when observing cuprous oxide nanoparticles dispersed in a dispersion medium using a transmission electron microscope (TEM). An average primary particle size is calculated by cutting out an arbitrary portion of an image and calculating an average value of primary particle sizes of 100 or more particles contained in the portion.

The average primary particle size of the cuprous oxide nanoparticles is not particularly limited as long as it is 100 nm or less, but is preferably 50 nm or less, particularly preferably 20 nm or less, and most preferably 15 nm or less.
When the average primary particle size exceeds 100 nm, the adhesion with the resin is lowered, and the antibacterial property tends to deteriorate early.
In particular, when the average primary particle size is 20 nm or less, the adhesion to the resin is significantly improved. The reason why the adhesion is improved is not necessarily clear, but it is presumed that a hydrogen bond can be formed between the hydroxyl group that can be formed on the surface of the cuprous oxide nanoparticles and the substrate.

In the antibacterial member of the present embodiment, when the cuprous oxide nanoparticles form secondary particles, the average secondary particle size of the cuprous oxide nanoparticles is from the viewpoint of adhesion to the substrate, The thickness is preferably 1 μm or less, more preferably 500 nm or less, and particularly preferably 200 nm or less.
The average secondary particle size means an average value of secondary particle sizes obtained for a plurality of secondary particles by image analysis. Here, the secondary particle diameter means the secondary particles obtained from image data obtained when observing cuprous oxide nanoparticles dispersed in diethylene glycol using a transmission electron microscope (TEM). This refers to the particle diameter. Usually, an arbitrary portion of an image is cut out, and the average secondary particle size is calculated by calculating the average value of the secondary particle sizes of 100 or more particles contained in this portion.

  The cuprous oxide used in the antibacterial member of the present embodiment can be prepared by a known method such as a gas phase method or a liquid phase method, and from the viewpoint of controlling the particle size and cohesiveness, It is preferable to use a method by a liquid phase method in which a copper compound as a raw material of monocopper is dispersed and dissolved in a solvent, and then the copper compound is chemically converted.

Examples of the base material used in the present embodiment include resins, resin compositions, ceramics, metals, and the like, and resins and resin compositions are preferable from the viewpoint of ease of workability.
Examples of the resin include cellulose resin, polyester resin, polyamide resin, polyolefin resin, polyimide resin, polyurethane resin, acrylic resin, vinyl resin, fluororesin, silicone resin, polyether resin, etc., which can be hydrogen bonded to the side chain. Cellulosic resins having various functional groups are preferred.

  The shape of the substrate used in the present embodiment is not particularly limited, and examples thereof include a fiber shape, a film shape, a plate shape, a complicated three-dimensional structure shape, and the like, and a fiber shape is particularly preferable.

It is particularly preferable that the base material has a functional group capable of hydrogen bonding with respect to cuprous oxide nanoparticles on its surface. Examples of the functional group capable of hydrogen bonding include a hydroxyl group, an amide group, an imide group, and a urethane. Groups.
In addition, the functional group capable of hydrogen bonding to the cuprous oxide nanoparticles may be inherent in the molecular structure of the base material (preferably a resin) or introduced into the surface of the base material by a surface reaction or the like. It may be what was done.
Examples of functional groups capable of hydrogen bonding in the molecular structure of the substrate include hydroxyl groups in cellulosic resins, ester groups in polyester resins, amide groups in polyamide resins, imide groups in polyimide resins, and polyurethane resins. Of urethane groups. Among these, a hydroxyl group in the cellulosic resin is preferable from the viewpoint of adhesion and the like.
Techniques for introducing functional groups capable of hydrogen bonding to the substrate surface include etching treatment using chemicals such as acid and alkali, corona treatment, atmospheric plasma treatment, flame treatment, ozone treatment, treatment with a silane coupling agent, etc. Can be mentioned.

  The content of the cuprous oxide nanoparticles in the antibacterial member of the present embodiment is preferably 0.001 to 20% by mass, with the antibacterial member being 100% by mass, from the viewpoint of sufficiently obtaining antibacterial properties. More preferably, it is 0.1-10 mass%.

(Method for producing antibacterial member)
The method for producing an antibacterial member of this embodiment is characterized by including a step of preparing a colloidal dispersion of cuprous oxide nanoparticles and a step of applying and drying the colloidal dispersion on a substrate.

  Here, the colloidal dispersion of cuprous oxide nanoparticles refers to a mixture in which the cuprous oxide nanoparticles are floating without being settled in the liquid, and the liquid at this time is used as a dispersion medium. That's it.

The dispersion medium used in the present embodiment is not particularly limited as long as it does not impair the colloidal properties of cuprous oxide nanoparticles, but alcohols including monohydric alcohols and polyhydric alcohols are particularly preferable.
Examples of the monohydric alcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol and the like, and examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propane. Examples include diol, 1,2-butanediol, 1,3-butanediol, pentanediol, and hexanediol. These may be used alone or in combination of two or more.
In the present embodiment, a dispersion medium other than alcohol may be used instead of alcohol or in addition to alcohol as long as the colloidal properties of cuprous oxide nanoparticles are not impaired.
Dispersants other than such alcohols include ether, n-hexane, diethyl ether, n-heptane, diisobutyl ketone, methylcyclohexane, diisopropyl ketone, isobutyl chloride, cyclohexane, ethyl amyl ketone, isobutyl acetate, benzonitrile, isopropyl acetate. , Methyl isobutyl ketone, amyl acetate, butyl acetate, cellosolve acetate, diethyl carbonate, diethyl ketone, ethylbenzene, xylene, butyl carbitol, toluene, ethyl acetate, diacetone alcohol, benzene, chloroform, methyl ethyl ketone, styrene, ethyl carbitol, Methyl acetate, anisole, cellosolve, diethyl acetamide, diethyl carbonate, dioxane, acetone, methyl isobutyl carbinol, Toro benzene, acrylonitrile, diethyl formamide, dimethyl acetamide, butanol, cyclohexanol, acetonitrile, propyl alcohol, benzyl alcohol, butylene carbonate, dimethyl formamide, ethylene carbonate, and methyl formamide.

The content of cuprous oxide nanoparticles in the cuprous oxide nanoparticle colloidal dispersion may be usually 0.1 to 60% by mass, preferably 100% by mass of the cuprous oxide nanoparticle colloidal dispersion. Is 0.1-30 mass%, More preferably, it is 0.1-20 mass%.
When the content of cuprous oxide nanoparticles exceeds 60% by mass, the viscosity of the dispersion tends to increase, which may make it difficult to apply to a substrate such as a resin, and 0.1% by mass. If it is smaller than that, the amount of cuprous oxide nanoparticles that can be applied by one application decreases, and the application process needs to be repeated many times, which may increase the cost.

Moreover, in this embodiment, you may add an additive to the colloid dispersion liquid of cuprous oxide nanoparticle as needed.
Additives include plasticizers, desiccants, curing agents, anti-skinning agents, leveling agents, anti-sagging agents, anti-fungal agents, antibacterial agents, ultraviolet absorbers, heat ray absorbers, lubricants, surfactants, dispersions Agents, thickeners, viscosity modifiers, stabilizers, drying modifiers, and the like, and further antiviral compositions, antibacterial compositions, antifungal compositions, antiallergen compositions, catalysts, antireflection materials, Examples thereof include materials having heat shielding properties.

In the present embodiment, the method for applying and drying the colloidal dispersion of cuprous oxide nanoparticles on a substrate is not particularly limited.
Examples of the coating method include a dip coating method, a dipping method, a spray method, a roll coater method, a bar coater method, a spin coating method, a gravure printing method, an offset printing method, a screen printing method, and an ink jet method.
Examples of the drying method include heat drying and natural drying. If necessary, irradiation with ultraviolet rays, infrared rays, electron beams, γ rays, or the like may be performed during drying.

  Although it does not specifically limit as an application of the antibacterial member of this embodiment, For example, a textile fabric, a nonwoven fabric, etc. are mentioned, More specifically, an application example is a mask; a filter for an air conditioner, a filter for an air cleaner, a cleaning Machine filters, ventilation fan filters, vehicle filters, air conditioning filters, etc .; nets for clothes, bedding, nets for screen doors, nets for poultry houses, etc .; sheets for wallpaper, windows, ceilings, vehicle seats, etc. -Films: Interior materials for various facilities such as doors, blinds, chairs, sofas, flooring (virus handling facilities, trains / vehicles, hospitals, buildings in general), etc.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

[Example 1]
<Preparation of colloidal dispersion of cuprous oxide nanoparticles>
80 g of anhydrous copper acetate (manufactured by Nippon Kagaku Sangyo) was added to a SUS reactor, and 700 mL of purified water was added thereto. The temperature of the reactor was raised to 40 ° C. and copper acetate was dissolved while stirring. The solution was then cooled to -15 ° C. Next, a 40 wt% hydrazine solution was adjusted so that the ratio (mol) of hydrazine to copper acetate in the reactor was 1.2, and this was added to the reactor over 15 minutes. After the addition was complete, the reactor temperature was raised to 25 ° C. and stirring in the reactor was continued for 1 hour.
About the obtained reaction liquid, the cuprous oxide nanoparticle was obtained by performing solid-liquid separation using a centrifuge.
Next, the obtained cuprous oxide nanoparticles are put into a SUS tank, and 100 mL of diethylene glycol is added thereto, and ultrasonically dispersed in the mixture, whereby a colloidal dispersion of cuprous oxide nanoparticles (colloid) The content of cuprous oxide nanoparticles with respect to the dispersion: 10% by mass) was obtained. The average primary particle size of the cuprous oxide nanoparticles in this dispersion was 15 nm, and the average secondary particle size was 80 nm.

<Application and drying of colloidal dispersion on cellulose fiber>
As a non-woven fabric made of cellulose fibers, Benise manufactured by Asahi Kasei Fibers Co., Ltd. was used. Benlyse was cut into a size of 10 cm × 10 cm and immersed in a colloidal dispersion of the obtained cuprous oxide nanoparticles.
The nonwoven fabric after the cuprous oxide was adhered was pulled out of the colloidal dispersion, and the excess dispersion was washed away with ethanol.
The washed nonwoven fabric was heated to 100 ° C. with a vacuum dryer and dried to remove ethanol.
Thus, an antibacterial sheet (content of cuprous oxide nanoparticles with respect to cellulose fibers: 3% by mass) was obtained.

(Antimicrobial evaluation)
The antibacterial properties of the obtained antibacterial sheet were evaluated according to JIS L 1902: 2008 “bacterial solution absorption method”. Staphylococcus aureus (NBRC number: 12732) was used as the test strain.
The evaluation criteria are shown below.
A: Common logarithm of the number of viable cells after 18 hours of culture is less than 1.3 B: Common logarithm of the number of viable cells after 18 hours of culture is 1.3 or more, less than the value immediately after inoculation C: After 18 hours of culture When the antibacterial sheet of Example 1 is present, the common logarithm of the number of viable bacteria immediately after inoculation was 3.7, whereas after 18 hours of cultivation The common logarithm of was significantly reduced to <1.3 below the sensitivity. From this result, it was found that the antibacterial sheet of Example 1 has high antibacterial properties. The results are shown in Table 1.

(Evaluation of antifungal properties)
The antifungal property of the obtained antibacterial sheet was evaluated by applying JIS Z 2911: 2010 “7.
The test strains include Aspergillus niger (NBRC number: 105649), Penicillium citrinum (NBRC number: 6352), Ketomium globosum (MBRC), NBRC number, 47 4 types of verrucaria, NBRC number: 6113) were used.
The evaluation criteria are shown below.
A: Mycelium growth is not observed in the inoculated part of the test piece.
B: The area of the growth part of the mycelium recognized in the inoculated part of the test piece does not exceed 1/3 of the total area.
C: The area of the growth part of the mycelium recognized in the inoculated part of the test piece exceeds 1/3 of the total area.
The fungi resistance after 2 weeks of the wet method and the fungus resistance after 4 weeks of the dry method were confirmed together, but no hyphal growth was observed in the inoculated portion of the antibacterial sheet of Example 1. From this result, it was confirmed that the antibacterial sheet of Example 1 has high antifungal properties. The results are shown in Table 1.

(Evaluation of stability)
The stability of the obtained antibacterial sheet was evaluated by the degree of adhesion of cuprous oxide to the tape when a scotch tape was applied to the surface of the obtained antibacterial sheet and then the tape was peeled off.
The evaluation criteria are shown below.
A: No transfer of cuprous oxide B: A portion of cuprous oxide is transferred C: All of cuprous oxide is transferred In the antibacterial sheet of Example 1, transfer of cuprous oxide is not confirmed on the tape. It was. The results are shown in Table 1.

  Further, as described above, the antibacterial evaluation and the antifungal evaluation of the antibacterial sheet of Example 1 after the evaluation of the stability were conducted. The same antibacterial and antifungal properties were maintained.

(Example 2)
<Preparation of colloidal dispersion of cuprous oxide nanoparticles>
To a SUS reactor, 40 g of anhydrous copper acetate (manufactured by Nippon Kagaku Sangyo) was added, and 700 mL of purified water was added thereto. The temperature of the reactor was raised to 40 ° C. and copper acetate was dissolved while stirring. The solution was then cooled to -15 ° C. Next, a 64 wt% hydrazine solution was adjusted so that the ratio (mol) of hydrazine to copper acetate in the reactor was 0.2, and this was added to the reactor over 15 minutes. After the addition was complete, the reactor temperature was raised to 25 ° C. and stirring in the reactor was continued for 1 hour.
About the obtained reaction liquid, the cuprous oxide nanoparticle was obtained by performing solid-liquid separation using a centrifuge.
Next, the obtained cuprous oxide nanoparticles are put into a SUS tank, and 100 mL of diethylene glycol is added thereto, and ultrasonically dispersed in the mixture, whereby a colloidal dispersion of cuprous oxide nanoparticles (colloid) The content of cuprous oxide nanoparticles with respect to the dispersion: 10% by mass) was obtained. Precipitation components were observed in this dispersion in Example 2. The average primary particle size of the cuprous oxide nanoparticles in this dispersion was 50 nm, and the average secondary particle size was 300 nm.

<Application and drying of colloidal dispersion on cellulose fiber>
In order to make the sediment component in the dispersion ubiquitous, a nonwoven fabric made of cellulose fibers used in Example 1 (Benlyse manufactured by Asahi Kasei Fibers Co., Ltd.) used in Example 1 is 10 cm × 10 cm in size while stirring the dispersion using a stir bar. And was immersed in a colloidal dispersion of the obtained cuprous oxide nanoparticles.
The nonwoven fabric after the cuprous oxide was adhered was pulled out of the colloidal dispersion, and the excess dispersion was washed away with ethanol.
The washed nonwoven fabric was heated to 100 ° C. with a vacuum dryer and dried to remove ethanol.
Thus, an antibacterial sheet (content of cuprous oxide nanoparticles with respect to cellulose fibers: 5% by mass) was obtained.

About the antibacterial sheet of Example 2, as in the case of the antibacterial sheet of Example 1, antibacterial evaluation, antifungal evaluation, and stability evaluation were performed. The results are shown in Table 1.
The antibacterial sheet of Example 2 showed high antibacterial and antifungal properties as in the case of the antibacterial sheet of Example 1, while some adhesion of cuprous oxide to the tape was observed in the Scotch tape test. It was.

(Comparative Example 1)
<Preparation of colloidal dispersion of cuprous oxide nanoparticles>
To a SUS reactor, 10 g of anhydrous copper acetate (manufactured by Nippon Chemical Industry Co., Ltd.) was added, and 700 mL of purified water was added thereto. The temperature of the reactor was raised to 40 ° C. and copper acetate was dissolved while stirring. The solution was then cooled to -15 ° C. Next, a 20 wt% hydrazine solution was prepared so that the ratio (mol) of hydrazine to copper acetate in the reactor was 0.1, and this was added to the reactor over 15 minutes. After the addition was complete, the reactor temperature was raised to 25 ° C. and stirring in the reactor was continued for 1 hour.
About the obtained reaction liquid, the cuprous oxide nanoparticle was obtained by performing solid-liquid separation using a centrifuge.
Next, the obtained cuprous oxide nanoparticles are put into a SUS tank, and 100 mL of diethylene glycol is added thereto, and ultrasonically dispersed in the mixture, whereby a colloidal dispersion of cuprous oxide nanoparticles (colloid) The content of cuprous oxide nanoparticles with respect to the dispersion: 10% by mass) was obtained. A sedimentation component was observed in this dispersion in Comparative Example 1. The average primary particle size of the cuprous oxide nanoparticles in this dispersion was 200 nm, and the average secondary particle size was 2000 nm.

<Application and drying of colloidal dispersion on cellulose fiber>
In order to make the sediment component in the dispersion ubiquitous, a nonwoven fabric made of cellulose fibers used in Example 1 (Benlyse manufactured by Asahi Kasei Fibers Co., Ltd.) used in Example 1 is 10 cm × 10 cm size while stirring the dispersion using a stir bar And was immersed in a colloidal dispersion of the obtained cuprous oxide nanoparticles.
The nonwoven fabric after the cuprous oxide was adhered was pulled out of the colloidal dispersion, and the excess dispersion was washed away with ethanol.
The washed nonwoven fabric was heated to 100 ° C. with a vacuum dryer and dried to remove ethanol.
Thus, an antibacterial sheet (content of cuprous oxide nanoparticles with respect to cellulose fibers: 5% by mass) was obtained.

For the antibacterial sheet of Comparative Example 1, as in the case of the antibacterial sheet of Example 1, antibacterial evaluation, antifungal evaluation, and stability evaluation were performed. The results are shown in Table 1.
The antibacterial sheet of Comparative Example 1 showed high antibacterial and antifungal properties as in the case of the antibacterial sheet of Example 1, while adhesion of cuprous oxide to the tape was observed in the Scotch tape test.

  As in the case of the antibacterial sheet of Example 1, the antibacterial property and the antifungal property were evaluated as described above for the antibacterial sheet of Comparative Example 1 after the stability evaluation. In the evaluation of mold resistance after a week, hyphal growth was observed.

(Comparative Example 2)
Instead of the colloidal dispersion of cuprous oxide nanoparticles, a colloidal dispersion of silver nanoparticles (manufactured by Wako Pure Chemical Industries, Ltd.) (average primary particle size of silver nanoparticles: 10 nm, average secondary particle size: 100 nm) was used. Except for the points , the antibacterial sheet of Comparative Example 2 was obtained in the same manner as in Example 1.
About the antimicrobial sheet of the comparative example 2, antimicrobial evaluation and antifungal evaluation were performed similarly to the case of the antimicrobial sheet of Example 1. The results are shown in Table 1.
In the antibacterial sheet of Comparative Example 2, in the evaluation of mold resistance after 4 weeks of the dry method, growth to a level exceeding 1/3 of the total area of the mycelium was recognized, and it was found that the antifungal property was inferior.

The antibacterial member of the present invention can suppress the growth of bacteria in a shorter time than the prior art, and can stably obtain such an inhibitory effect.
In addition, according to the antibacterial member of the present invention, it is possible to obtain skin wrinkle improvement and wound healing effects by utilizing the skin active action of copper.

Claims (6)

  An antibacterial member comprising: a base material; and cuprous oxide nanoparticles having an average primary particle size of 100 nm or less arranged on the surface of the base material.   The antibacterial member according to claim 1, wherein the average primary particle size is 20 nm or less.   The antibacterial member according to claim 1 or 2, wherein the substrate is fibrous.   The antibacterial member according to any one of claims 1 to 3, wherein the base material has a functional group capable of hydrogen bonding to the cuprous oxide nanoparticles on the surface thereof.   The antibacterial member according to any one of claims 1 to 4, wherein the base material is a cellulose resin. Preparing a colloidal dispersion of cuprous oxide nanoparticles;
Applying and drying the colloidal dispersion on a substrate;
The method for producing an antibacterial member according to claim 1, comprising: