Wallpaper with water-based paint composition

Abstract

The present invention provides a water-based wallpaper coating composition that is less likely to drip, has good adhesion, has a reduced VOC concentration, and has excellent antibacterial properties. This problem is solved by a water-based wallpaper coating composition characterized by containing polyphenols, surfactants, and cellulose nanofibers with an average fiber diameter of 1 to 1000 nm.

Description

Technical Field

[0001] The present invention relates to an aqueous paint composition for wallpaper.

Background Art

[0002] Conventionally, there are many buildings with wallpaper pasted on the inner walls and ceilings. Such wallpapers include wallpapers combined with resin materials such as vinyl chloride resins, wallpapers using natural materials such as hemp, and paper wallpapers using paper materials. In recent years, wallpapers are manufactured with low organic compound concentrations or without organic compounds (for example, low formaldehyde or zero formaldehyde), and their safety has been improved. However, organic compounds may be used in the manufacturing processes of furniture, electrical appliances, etc. brought in by residents. If these remain in the products, they will volatilize when installed indoors. In particular, some recent buildings have high airtightness. When the volatilized organic compounds, that is, volatile organic compounds (hereinafter also referred to as "VOC"), fill the building and the concentration increases, the VOC may have an adverse effect on humans (for example, the onset of sick house syndrome).

[0003] Under such circumstances, legally or socially, reduction of VOC concentration has been demanded. For example, Patent Document 1 discloses a technique for reducing the VOC concentration by providing a coating film layer containing a VOC adsorbing material on the surface of a base sheet.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0005] Incidentally, wallpaper is usually made using a water-repellent wallpaper substrate or a wallpaper substrate with a water-repellent coating layer (Patent Document 2) applied to it, in order to withstand changes in humidity within a building and to prevent the wallpaper substrate from deforming. When applying a coating layer to such a water-repellent wallpaper substrate, if the coating layer is water-based, it will be repelled by the wallpaper substrate, so oil-based coatings have been used until now. However, in order to apply such an oil-based coating layer to a wallpaper substrate, there was a problem in that the paint used to form the coating layer had to be made to not drip as much as possible.

[0006] On the other hand, in addition to the function of reducing VOC concentration, there is also a technology that gives wallpaper antibacterial properties (Patent Document 3), but in order to apply the antibacterial coating to the wallpaper substrate without dripping, the problem remains that dripping must be suppressed as much as possible.

[0007] Therefore, the present invention aims to provide a water-based coating composition for wallpaper that is less prone to dripping when applied to water-repellent wallpaper, has good adhesion, has reduced VOC concentration, and exhibits excellent antibacterial properties. [Means for solving the problem]

[0008] The aforementioned problem is solved by the following means. (First aspect) It contains polyphenols, surfactants, and cellulose nanofibers with an average fiber diameter of 1 nm or more and 1000 nm or less. A water-based paint composition for wallpaper characterized by the following features.

[0009] The water-based paint composition for wallpaper in this embodiment contains cellulose nanofibers, making it less likely to be repelled by water-repellent wallpapers. Furthermore, because it contains a surfactant along with polyphenols, the polyphenols are dispersed in the composition in the form of oil droplets, preventing uneven distribution of polyphenols. When the water-based paint composition for wallpaper is applied to wallpaper, the applied area is covered with cellulose nanofibers and the polyphenols are dispersed, resulting in good adhesion, reduced dripping, and excellent antibacterial properties.

[0010] (Second aspect) Furthermore, it contains a thickening agent, A water-based paint composition for wallpaper according to a first embodiment.

[0011] The water-based paint composition for wallpaper in this embodiment contains a thickening agent, resulting in excellent adhesion to wallpaper and reduced dripping.

[0012] (Third aspect) The aforementioned surfactant is a naturally derived surfactant. A water-based paint composition for wallpaper according to a first embodiment.

[0013] Since the surfactant contained in the water-based paint composition for wallpaper according to this embodiment is of natural origin, it offers excellent safety for the human body.

[0014] (Fourth aspect) The aforementioned polyphenol is a polyphenol derived from recycled materials. A water-based paint composition for wallpaper according to a first embodiment.

[0015] Since the surfactant contained in the water-based paint composition for wallpaper according to this embodiment is of natural origin, it offers excellent safety for the human body.

[0016] (Fifth aspect) Furthermore, it contains an antibacterial agent. A water-based paint composition for wallpaper according to a first embodiment.

[0017] In the case of the aqueous paint composition for wallpaper of this aspect, it will have more antibacterial properties.

[0018] (Sixth Aspect) With respect to the total amount of the aqueous paint composition for wallpaper, the polyphenol 1 is contained at 1 to 10%, and the surfactant is contained at 0.1% or more and 0.5% or less, The aqueous paint composition for wallpaper of the first aspect.

[0019] When the polyphenol and the surfactant are contained in the aqueous paint composition at such a ratio, the polyphenol is moderately dispersed, resulting in a homogeneous paint composition.

[0020] (Seventh Aspect) Applied to wallpaper having water repellency, The aqueous paint composition for wallpaper of the first aspect.

[0021] When the aqueous paint composition for wallpaper of the first aspect is applied to wallpaper, the applied portion is covered with cellulose nanofibers. However, unlike water, cellulose nanofibers are not easily repelled even by water-repellent wallpaper. Therefore, uniform application to the wallpaper is easy, and dripping after application is unlikely to occur.

[0022] (Eighth Aspect) Having a Brookfield viscosity of 20 to 1000 mPa·s, The aqueous paint composition for wallpaper of the first aspect.

[0023] For an aqueous paint composition for wallpaper having a Brookfield viscosity within this range, it is easy to apply to wallpaper and streaking is unlikely to occur. [[Effect of the Invention]]

[0024] According to the present invention, an aqueous paint composition for wallpaper is provided which is less likely to drip even when applied to water-repellent wallpaper, has good fixing properties, has a reduced VOC concentration, and is excellent in antibacterial properties. [[Brief Description of the Drawings]]

[0025] [Figure 1] This shows the results of the antiviral test. [Figure 2] This shows the results of the antibacterial test. [Modes for carrying out the invention]

[0026] Embodiments for carrying out the present invention are described below. Note that this embodiment is just one example of the present invention. The scope of the present invention is not limited to this embodiment.

[0027] The water-based paint composition for wallpaper according to this embodiment is characterized by having polyphenols, a surfactant, and cellulose nanofibers with an average fiber diameter of 1 to 1000 nm.

[0028] The polyphenols contained in the water-based paint composition for wallpaper according to this embodiment may be, for example, natural polyphenols, and may be flavonoid polyphenols or phenolic acid polyphenols. Examples of flavonoid polyphenols include flavones such as luteolin, isoflavones such as genistein, catechins such as tannin, cocoa polyphenols, catechin, and epicatechin, flavonols such as rutin, quercetin, and myricetin, flavanones such as hesperetin, and anthocyanidins such as anthocyanins and cyanidins. Examples of phenolic acid polyphenols include gingerols, ferulas, hydroxybenzoic acids such as gallic acid and ellagic acid, hydroxycinnamic acids such as caffeic acid, chlorogenic acid, neochlorogenic acid, diketones such as curcumin, and rosmarinic acid.

[0029] Among natural polyphenols, plant-derived polyphenols are preferred. Polyphenols obtained from extracts of persimmon leaves, Japanese knotweed, and mugwort are plant-derived, safe for the human body, and are preferred for removing VOCs. Examples of polyphenols obtained from persimmon leaf extracts include tannins, catechins, and rutin. Examples of polyphenols obtained from Japanese knotweed extracts include neochlorogenic acid, flavonols such as rutin, and chlorogenic acid. Examples of polyphenols obtained from mugwort extracts include catechins. Since polyphenols obtained from extracts of persimmon leaves, Japanese knotweed, and mugwort are plant-derived and safe for the human body, it is preferable for them to be included in water-based paint compositions for wallpaper. Plant-derived polyphenols can be obtained, for example, from hot water extracts of persimmon leaves, Japanese knotweed, or mugwort, as described in Japanese Patent Publication No. 2024-13172. On the other hand, among plant-derived polyphenols, those containing extracts from persimmon leaves, Japanese knotweed, and mugwort are particularly preferred because they exhibit a high removal effect on VOCs.

[0030] One mechanism by which VOCs are removed is through substitution reactions between VOCs and phenols. For example, taking formaldehyde and phenols as an example, formaldehyde is removed when it combines with phenols and a substitution reaction occurs. This substitution reaction is known to proceed under both acidic and alkaline conditions.

[0031] On the other hand, polyphenols have a bactericidal effect because they acquire a negative charge through proton transfer of phenolic hydroxyl groups, which then bind to positively charged bacterial membrane components, causing membrane damage.

[0032] Typical VOCs (volatile organic compounds) used in building materials include formaldehyde, acetaldehyde, toluene, xylene, styrene, ethylbenzene, and paradichlorobenzene. Formaldehyde, toluene, xylene, and paradichlorobenzene, in particular, are well known to have adverse effects on the human body.

[0033] (Surfactants) Examples of surfactants included in the water-based paint composition for wallpaper according to this embodiment include anionic surfactants, amine-type cationic surfactants, betaine-type amphoteric surfactants, nonionic surfactants, and naturally derived surfactants. Preferred anionic surfactants include alkyl sulfate salts, polyoxyethylene alkyl sulfate salts, alkylbenzene sulfonates, and α-olefin sulfonates. Preferred amine-type cationic surfactants include alkoxydimethylamine, alkylamide dimethylamine, and alkyldimethylamine. Preferred betaine-type amphoteric surfactants include alkyldimethylaminoacetic acid betaine and alkylamide dimethylaminoacetic acid betaine. Preferred nonionic surfactants include glycerin fatty acid esters, polyglycerin fatty acid esters, propylene glycol fatty acid esters, sorbitan fatty acid esters, and sorbitol fatty acid esters, as well as alkylene glycol adducts thereof, polyalkylene glycol fatty acid esters, sucrose fatty acid esters, polysorbate 20, polysorbate 60, polysorbate 80, polyoxyalkylene alkyl ethers, and polyoxyethylene alkylphenyl ethers.

[0034] Examples of naturally derived surfactants include cyclic lipopeptide surfactants. Cyclic lipopeptide surfactants have a cyclic peptide and a long-chain hydrocarbon group. Examples of cyclic lipopeptide surfactants include surfactant, a salt of surfactant, iturine, a salt of iturine, arsulofactin, a salt of arsulofactin, etc., and one or more combinations selected from these are preferred, with surfactant or a salt of surfactant being particularly preferred.

[0035] For example, the salts of surfactin can be represented by the following general formula (I). [ka] In the formula, X is an amino acid residue selected from leucine, isoleucine, and valine. X is an amino acid residue and can be either the L or D form. R is a linear or monovalent branched saturated hydrocarbon group having 9 to 18 carbon atoms. Examples include n-nonyl, 6-methyloctyl, n-decyl, 8-methylnonyl, n-heptadecyl, n-octadecyl, etc. + The alkali metal ion is not particularly limited, but examples include lithium ions, sodium ions, potassium ions, etc., with sodium ions being preferred.

[0036] Cyclic lipopeptide surfactants can be obtained by isolating them from microorganisms that produce them using known methods. For example, strains belonging to Bacillus subtilis can be cited as microorganisms that produce surfactant. Cyclic lipopeptide surfactants can also be obtained from the market.

[0037] Cyclic lipopeptide surfactant is particularly excellent as a surfactant for use in the water-based paint composition for wallpaper according to this embodiment. Although the exact mechanism is unknown, this is likely due to the cyclic lipopeptide surfactant having carboxyl groups or hydroxyl groups in its cyclic peptide portion. The cellulose nanofibers contained in the water-based paint composition for wallpaper have hydroxyl groups in their cellulose portion and are thought to form a three-dimensional network structure with the cyclic lipopeptide surfactant. Because cyclic lipopeptide surfactant has excellent transparency, when included in the water-based paint composition for wallpaper, the color of the wallpaper is not impaired even after several hours have passed and the moisture has decreased since the paint composition was applied to the wallpaper. Furthermore, because cyclic lipopeptide surfactant has excellent emulsifying and dispersible properties and stability, the water-based paint composition for wallpaper according to this embodiment containing cyclic lipopeptide surfactant has cellulose nanofibers and polyphenols uniformly dispersed in the composition and paint, and the dispersion state is maintained.

[0038] The surfactant content in the water-based paint composition for wallpaper according to this embodiment is preferably 0.1% or more, more preferably 0.2% or more, and optimally 0.3% of the total amount of the water-based paint composition for wallpaper. On the other hand, the upper limit of the surfactant content in the water-based paint composition for wallpaper according to this embodiment is 0.5% or less. When the surfactant content is within the above range, the water-based paint composition for wallpaper is less likely to be repelled by the wallpaper, can be applied evenly, and is less likely to cause unevenness in application.

[0039] On the other hand, a water-based paint composition for wallpaper containing a naturally derived surfactant, a plant-derived polyphenol, and cellulose nanofibers is one preferred form. Since the components of this water-based paint composition are derived from nature, it is particularly safe for the human body.

[0040] (Cellulose nanofiber) Cellulose nanofibers (also known as "CNF") can be obtained by defibrating (finely processing) raw material pulp, and can be manufactured using known processing methods such as chemical processing and mechanical processing.

[0041] As raw material pulp for cellulose nanofibers, one or more types can be selected and used from among, for example, wood pulp made from hardwoods, softwoods, etc., non-wood pulp made from straw, bagasse, cotton, hemp, pulp fibers, etc., and recycled paper pulp (DIP) made from brown waste paper, envelope waste paper, magazine waste paper, flyer waste paper, corrugated cardboard waste paper, white waste paper, imitation waste paper, polished waste paper, recycled waste paper, and waste paper. In recent years, there has been an increasing demand for products containing organic components that take into consideration the reduction of environmental impact, so wood pulp made from hardwoods and softwoods derived from plants other than recycled paper is particularly suitable.

[0042] As wood pulp, one or more types can be selected and used from, for example, hardwood kraft pulp (LKP), softwood kraft pulp (NKP), sulfite pulp (SP), dissolved pulp (DP), and mechanical pulp (TMP). In particular, wood pulp that increases the cellulose content, such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), is preferred, and bleached pulp (BKP) is also preferred.

[0043] As mechanical pulp, one or more types can be selected and used from, for example, stone gland pulp (SGP), pressure stone gland pulp (PGW), refiner gland pulp (RGP), chemigland pulp (CGP), thermo gland pulp (TGP), gland pulp (GP), thermomechanical pulp (TMP), chemothermetic pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP), etc.

[0044] From the standpoint of producing cellulose nanofibers with a relatively small average fiber diameter, it is preferable to use kraft pulp, which is easily defibrated and has high dispersibility.

[0045] Cellulose nanofibers may be pre-treated before defibration. For example, the raw pulp may be mechanically pre-beaten or chemically modified as a pre-treatment. The pre-beating method is not particularly limited, and known methods can be used.

[0046] Examples of chemical methods for modifying raw pulp include hydrolysis of polysaccharides with acids (e.g., sulfuric acid, etc.) (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkalis (alkali treatment), oxidation of polysaccharides with oxidizing agents (e.g., ozone, etc.) (oxidation treatment), reduction of polysaccharides with reducing agents (reduction treatment), oxidation with a TEMPO catalyst (oxidation treatment), anionization by phosphate esterification (anion treatment), and cationization (cation treatment).

[0047] Among the chemical modification treatments, oxidation with a TEMPO catalyst can be carried out by known methods (for example, the method disclosed in Japanese Patent Publication No. 2023-40759), but it can also be carried out by the following method. Oxidation with a TEMPO catalyst is a treatment by an oxidation reaction using TEMPO(2,2,6,6-tetramethylpiperidine 1-oxyl) as a catalyst. When cellulose fibers are oxidized with a TEMPO catalyst, the primary hydroxyl groups of the cellulose fibers are regioselectively oxidized to carboxyl groups, and further alkali treatment is performed to substitute the C6 position with a carboxylate. In oxidation with a TEMPO catalyst, cellulose fibers are obtained in which the C6 position is substituted with a carboxylate by reacting with hypochlorous acid under TEMPO or sodium bromide while maintaining a predetermined pH.

[0048] In the method of anionizing cellulose fibers by phosphate esterification, anionic functional groups are introduced into the cellulose fibers. Examples of cellulose nanofibers to which anionic functional groups have been introduced include cellulose nanofibers to which phosphorus oxo acid ester groups have been introduced, and cellulose nanofibers in which the hydroxyl group of the pyranose ring is directly oxidized to a carboxyl group. Esterification with phosphorus oxo acid can be carried out, for example, by the method described in Japanese Patent Publication No. 2019-199671.

[0049] Cellulose nanofibers modified by the introduction of anionic functional groups exhibit relatively high dispersibility. This is presumed to be due to factors such as the localized distribution of charge imbalances caused by the anionic functional groups, the resulting smaller fiber diameters of the defibrated cellulose nanofibers, thus reducing the variation in fiber diameter, and the ease with which the anionic functional groups form hydrogen bonds with water and organic solvents in the dispersion.

[0050] When cellulose fibers are subjected to esterification with phosphorus oxoacid, an example of anionization, the fiber raw material can be refined, and the resulting cellulose nanofibers have a large aspect ratio, excellent strength, high light transmittance, and high viscosity.

[0051] On the other hand, sodium carboxymethylcellulose, a polysaccharide in which a carboxymethyl group is ether-bonded to the hydroxyl group of cellulose, is also preferred as a cellulose nanofiber that has been chemically modified.

[0052] The defibration of cellulose fibers can be carried out by known methods, for example, by the defibration apparatus and methods shown below. This defibration can be carried out by selecting one or more means from among homogenizers such as high-pressure homogenizers and high-pressure homogenization devices, millstone-type friction machines such as grinders and crushers, refiners such as conical refiners and disc refiners, and various bacteria. However, it is preferable to carry out the defibration of cellulose fibers using an apparatus and method that pulverizes them with a water flow, especially a high-pressure water flow. With this apparatus and method, the resulting cellulose nanofibers have very high dimensional uniformity and dispersion uniformity. In contrast, if a grinder that grinds between rotating grinding wheels is used, for example, it is difficult to uniformly pulverize the cellulose fibers, and in some cases, some undissolved fiber clumps may remain.

[0053] Examples of grinders used for defibrating cellulose fibers include the Mascoloider from Masuko Sangyo Co., Ltd. Examples of devices that use high-pressure water jets for micronization include the Starburst (registered trademark) from Sugino Machine Co., Ltd. and the Nanovater (registered trademark) from Yoshida Machinery Industry Co., Ltd. Examples of high-speed rotary homogenizers used for defibrating cellulose fibers include the Creamix-11S from M-Technique.

[0054] Cellulose nanofibers obtained by chemically modifying cellulose fibers and then defibrating them can be called chemically modified cellulose nanofibers, while cellulose nanofibers obtained by defibrating them without chemical modification can be called unmodified cellulose nanofibers.

[0055] The cellulose nanofibers contained in the water-based paint composition for wallpaper according to this embodiment may consist only of unmodified cellulose nanofibers, or only of chemically modified cellulose nanofibers, or may contain both unmodified and chemically modified cellulose nanofibers.

[0056] The defibration of the raw pulp is preferably carried out in such a way that the physical properties of the resulting cellulose nanofibers meet the desired values ​​or evaluations shown below.

[0057] (Average fiber diameter) The upper limit of the average fiber diameter (average fiber width; average diameter of a single fiber) of cellulose nanofibers is 1000 nm, preferably 500 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or less. When the average fiber diameter of cellulose nanofibers is 1000 nm or less, the cellulose nanofibers attached to the wallpaper coated with the water-based paint composition for wallpaper according to this embodiment are not noticeable, and the design of the wallpaper itself is less likely to be impaired, which is preferable. On the other hand, the lower limit of the average fiber diameter of cellulose nanofibers is preferably 1 nm. If the average fiber diameter falls below the lower limit, it becomes more easily soluble in the paint composition, which causes the viscosity of the water-based paint composition for wallpaper to decrease.

[0058] The average fiber diameter of cellulose nanofibers can be adjusted, for example, by selecting the raw pulp, pre-treatment, and defibration.

[0059] The method for measuring the average fiber diameter of cellulose nanofibers is as follows: First, 100 ml of an aqueous dispersion of cellulose nanofibers with a solid content concentration of 0.01-0.1% by mass is filtered through a Teflon® membrane filter, and the solvent is replaced once with 100 ml of ethanol and three times with 20 ml of t-butanol. Next, the dispersion is freeze-dried and coated with osmium to prepare the sample. This sample is observed using an electron microscope (SEM) at a magnification of 3,000x to 30,000x depending on the width of the constituent fibers. Specifically, two diagonal lines are drawn on the observed image, and three arbitrary straight lines are drawn passing through the intersection of the diagonals. Furthermore, the width of a total of 100 fibers that intersect these three straight lines is measured visually. The median diameter of the measured values ​​is then taken as the average fiber diameter.

[0060] (Average fiber length) The average fiber length (average length of a single fiber) of the cellulose nanofibers is preferably 0.01 to 1000 μm, more preferably 0.03 to 500 μm. When the average fiber length is within this range, the cellulose nanofibers are less likely to entangle with each other, thus preventing aggregation and resulting in a water-based paint composition for wallpaper that maintains a dispersed state.

[0061] The average fiber length can be arbitrarily adjusted, for example, by selecting the raw pulp, pre-treatment, defibration, etc.

[0062] The average fiber length of cellulose nanofibers is measured visually, similar to the method used for measuring the average fiber diameter. The median length of the measured values ​​is taken as the average fiber length.

[0063] (Axle ratio) The axial ratio (average fiber length / average fiber width) of the cellulose nanofibers is preferably 10 to 1,000,000, more preferably 30 to 500,000, and particularly preferably 50 to 100,000. When the axial ratio of the cellulose nanofibers is within the above range, the degree of entanglement between the fibers is small, and the resulting water-based coating composition for wallpaper has a sufficiently dispersed state of cellulose nanofibers.

[0064] (Degree of crystallinity) The degree of crystallinity of cellulose nanofibers is preferably 50 or higher at the lower limit, more preferably 60 or higher, particularly preferably 70 or higher, and preferably 100 or lower at the upper limit, more preferably 95 or lower, particularly preferably 90 or lower. If the degree of crystallinity is less than 50, the entanglement of the fibers weakens due to the effects of temperature changes during drying, the holding power of other substances weakens, and it becomes difficult to form cellulose particles of the desired particle size.

[0065] The degree of crystallinity was measured by X-ray diffraction in accordance with the "General Rules for X-ray Diffraction Analysis" of JIS-K0131 (1996). Note that cellulose nanofibers consist of amorphous and crystalline portions, and the degree of crystallinity represents the proportion of the crystalline portion in the entire cellulose nanofiber.

[0066] (Water retention) The water retention capacity of cellulose nanofibers is not particularly limited, but for example, if the cellulose nanofibers are unmodified, it is 500% or less, more preferably 100-500%. If the water retention capacity is within the above range, the cellulose nanofibers will not dry out easily, the wallpaper to which the water-based coating composition for wallpaper has been applied will be kept above a predetermined humidity level, and the wallpaper will not deform easily due to drying.

[0067] The water retention capacity of cellulose nanofibers can be arbitrarily adjusted, for example, by selecting the raw pulp, pre-treatment, and defibration.

[0068] The water retention capacity of cellulose nanofibers was measured according to JAPAN TAPPI No. 26 (2000).

[0069] The water-based paint composition for wallpaper according to this embodiment preferably contains 1 to 10% polyphenols and 0.04 to 2%, more preferably 0.05 to 1%, and even more preferably 0.1 to 0.5% cellulose nanofibers based on solid content, relative to the total amount of the water-based paint composition for wallpaper. It is presumed that the cellulose nanofibers form a three-dimensional network structure in the water-based paint composition for wallpaper, but even a small amount will give the water-based paint composition sufficient viscosity. If the water-based paint composition for wallpaper contains cellulose nanofibers within the above range, sufficient viscosity is obtained, and it spreads well when applied due to the thixotropic effect, making it easy to apply.

[0070] (Antibacterial agent) An antibacterial agent may be added to the water-based paint composition for wallpaper according to this embodiment. Examples of antibacterial agents include sodium benzoate, alkyldiamine ethylglycine hydrochloride, sodium dehydroacetate, chlorhexidine gluconate, alkylisoquinonilium bromide, sodium lauryldiaminoethylglycine, chloroxylenol, thymol, piroctone olamine polyaminopropyl biguanide, chlorhexidine chloride, and quaternary ammonium salts. Examples of quaternary ammonium salts include alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzalkonium chloride, didecyldimethylammonium chloride, cetyltrimethylammonium chloride, and cetylpyridinium chloride. Quaternary ammonium salts are particularly preferred, and among them, benzalkonium chloride is more preferred because it has excellent antibacterial properties and is inexpensive. It exhibits excellent antibacterial properties even in small amounts. These antibacterial agents are preferred for use in water-based paint compositions for wallpaper because they exhibit antibacterial properties in small amounts and have high safety for human skin.

[0071] The amount of antibacterial agent contained in the water-based paint composition for wallpaper according to this embodiment is preferably 0.03% or less, more preferably 0.02% or less, even more preferably 0.01% or less, and optimally 0.005% of the total amount of the water-based paint composition for wallpaper. When the amount of antibacterial agent is within the above range, the antibacterial agent is dispersed in the water-based paint composition for wallpaper together with cellulose nanofibers, and when the water-based paint composition for wallpaper is applied to the wallpaper, the applied wallpaper is preferably kept antibacterial.

[0072] (Thickening agent) Incidentally, cellulose nanofibers are formed from cellulose that has numerous hydroxyl groups (OH groups). These numerous hydroxyl groups allow hydrogen bonds to form between the cellulose nanofibers, creating a three-dimensional network structure. Because of these characteristics, a liquid containing dispersed cellulose nanofibers has relatively high viscosity, as the individual nanofibers do not move freely easily. Furthermore, a liquid containing dispersed cellulose nanofibers exhibits both viscosity and thixotropy.

[0073] As described above, the water-based paint composition for wallpaper according to this embodiment contains cellulose nanofibers and therefore has a predetermined viscosity. However, if the adhesion to wallpaper is to be further improved, a thickening agent can be added to the water-based paint composition for wallpaper. Examples of thickening agents include gum arabic, starch, sodium alginate, pectin, carboxymethylcellulose, methylcellulose, ethylcellulose, or hydroxypropyl methylcellulose (HPMC). Sodium alginate is particularly preferred because it produces a thickening effect even in small amounts. When adding a thickening agent to the water-based paint composition for wallpaper according to this embodiment, for example, the amount is preferably 0.3% or less, more preferably 0.2% or less, and even more preferably 0.1% or less, based on the total amount of the water-based paint composition for wallpaper. If the thickening agent is included within the above range, the water-based paint composition for wallpaper applied to the wallpaper will be less likely to drip. However, if a large amount of thickening agent is included in the water-based paint composition for wallpaper, the viscosity will become too high, making it difficult to apply. When including a thickening agent in the water-based paint composition for wallpaper, the lower limit should be above 0%.

[0074] The water-based paint composition for wallpaper according to this embodiment can be applied with good adhesion to wallpaper whether it is water-repellent (hydrophobic) or hydrophilic, but it is particularly characterized by its ability to be applied to water-repellent wallpaper. With conventional water-based paints, even if applied to water-repellent wallpaper, the paint is repelled and forms droplets, making it difficult to apply evenly. However, the water-based paint composition for wallpaper according to this embodiment is less likely to be repelled by water-repellent wallpaper. The exact reason why the water-based paint composition for wallpaper according to this embodiment is less likely to be repelled is not known, but it is thought to be due to the action of cellulose nanofibers. When a water-based paint composition or water-based paint containing cellulose nanofibers is applied to water-repellent wallpaper, the applied area is covered with a large number of cellulose nanofibers and water. Since the cellulose nanofibers are hydrogen-bonded to each other and their free movement is restricted, it is thought that the cellulose nanofibers suppress the free deformation of the water contained in the water-based paint composition or water-based paint (for example, droplet formation due to surface tension), and thus maintain a form that is not repelled. Furthermore, it is believed that the polyphenols contained in the water-based paint composition for wallpaper are also restricted from free movement within the composition or paint by the three-dimensional network structure of cellulose nanofibers, thus maintaining a dispersed state. In addition, it is presumed that the presence of a surfactant in the water-based paint composition for wallpaper makes separation of polyphenols from water difficult, thus maintaining a well-dispersed state of polyphenols in the water-based paint composition or paint. This means that even poorly water-soluble polyphenols, which are difficult to dissolve in water, are prevented from free movement by the network structure of cellulose nanofibers and are maintained in a dispersed state in the water-based paint composition for wallpaper according to this embodiment.

[0075] The wallpaper to which the water-based paint composition for wallpaper according to this embodiment is applied is a sheet made of cloth, paper, or vinyl used as an interior finishing material for walls and ceilings in buildings, and is applied for purposes such as protecting and decorating the substrate of walls and ceilings. While not particularly limited, examples of wallpaper include fiber-based wallpaper, vinyl chloride resin-based wallpaper, and plastic-based wallpaper. Fiber-based wallpapers include, for example, those primarily made of plant fibers or cellulose-based regenerated fibers such as rayon (including chemical fibers), and those primarily made of chemical fibers (acrylic, polyester, etc.). Vinyl chloride resin-based wallpapers include, for example, those primarily made of vinyl chloride resin, or those whose substrate surface is covered with vinyl chloride resin. Plastic-based wallpapers include those primarily made of plastics other than vinyl chloride resin, or those whose substrate surface is covered with the aforementioned plastic. Other examples include wallpaper containing synthetic fibers made of polyester or acrylic resin as disclosed in Reference 2, wallpaper coated with a water-repellent coating composition characterized by containing copolymer particles of ethylenically unsaturated monomers, wax particles containing a hydrocarbon compound having 8 to 60 carbon atoms and a functional group, and a dispersion medium, and wallpaper with a fluorine-treated surface.

[0076] Water-repellent wallpaper is not particularly limited as long as it repels water, but it also refers to wallpaper that has the property of repelling water, and when a water droplet is placed on the wallpaper, the contact angle between the wallpaper and the water is preferably 40° or more and less than 180°, more preferably 90° or more and less than 180°.

[0077] The water-based paint composition for wallpaper according to this embodiment has a B-type viscosity of 20 to 1000 mPa·s, preferably 30 to 500 mPa·s, at 6 rpm. Furthermore, the B-type viscosity of the water-based paint composition for wallpaper according to this embodiment is 5 to 200 mPa·s, preferably 10 to 150 mPa·s, more preferably 10 to 100 mPa·s, at 60 rpm. On the other hand, the thixotropy index (Ti value) of the water-based paint composition for wallpaper according to this embodiment is 1 to 10, preferably 1 to 8, and even more preferably 1 to 5. The thixotropy index (Ti value) is calculated by dividing the B-type viscosity at 6 rpm by the B-type viscosity at 60 rpm. If the B-type viscosity and thixotropy index are within the above ranges, when applied to wallpaper with a brush, brush roller, etc., dripping is less likely, the paint is less likely to streak, and it can be applied smoothly.

[0078] The B-type viscosity of the water-based paint composition for wallpaper according to this embodiment can be adjusted by mixing an aqueous solvent, such as water, into the water-based paint composition for wallpaper. When the water-based paint composition for wallpaper according to this embodiment is actually applied to wallpaper, if the composition contains 1 to 10%, more preferably 3 to 9%, and even more preferably 4 to 8% polyphenols relative to the total amount of the water-based paint composition for wallpaper, it will have an excellent effect in reducing VOCs.

[0079] On the other hand, the water-based paint composition for wallpaper according to this embodiment can be applied to wallpaper in the form of an oil-in-water emulsion, and can be applied evenly even if the wallpaper is water-repellent.

[0080] The water-based paint composition for wallpaper according to this embodiment preferably has a film thickness of, for example, 0.1 to 5 μm on the wallpaper, and more preferably 1 to 3 μm.

[0081] The water-based paint composition for wallpaper according to this embodiment can be applied to wallpaper installed on walls and ceilings of buildings, for example. If the applied wallpaper is not unnecessarily touched by humans, the effects of applying the water-based paint composition for wallpaper according to this embodiment will last for a long period of time, for example, more than one year. [Examples]

[0082] (Preparation of test samples) The following is an example of a test. Polyphenols, cellulose nanofibers, surfactants, sodium alginate, and benzalkonium chloride were added to a beaker containing an appropriate amount of water while stirring, and then more water was added to make up 200 mL to prepare the test example. The amounts of each compound are shown in Table 1. The polyphenol used was "Mansei," a product of Nature Grace Co., Ltd. The cellulose nanofibers used were "ELLEX(registered trademark)-S" (hereinafter also referred to as "CNF1"), a product of Daio Paper Corporation with an average fiber diameter of 50 nm; "ELLEX(registered trademark)-☆ (Star)" (hereinafter also referred to as "CNF2"), a product of Daio Paper Corporation with an average fiber diameter of 3 nm; and "carboxymethylcellulose sodium" (hereinafter also referred to as "CNF3"), a product of Nippon Paper Industries Ltd. The surfactants used were "Kaneka Surfactin Sodium" (hereinafter referred to as "Surfactant 1"), a product of Kaneka Corporation; and "Polyflow KL-100" (hereinafter referred to as "Surfactant 2"), a product of Kyoeisha Chemical Co., Ltd. Sodium alginate was used as the product "Sodium Alginate" manufactured by Matsuba Pharmaceutical Co., Ltd. Benzalkonium chloride was used as the product "Benzalkonium Chloride Solution Osban S (10 w / v%)" manufactured by Nippon Pharmaceutical Co., Ltd. Note that the amounts of polyphenols, CNF1, CNF2, CNF3, and benzalkonium chloride in Table 1 are based on solid content.

[0083] [Table 1]

[0084] The test sample was applied to a water-repellent wallpaper (Lilycolor Co., Ltd. product "airrefre LW-4350") using a brush roller to achieve a film thickness of 2 μm. Antibacterial properties were evaluated (Lumitester test), liquid contact angle test, B-type viscosity measurement, unevenness of application was evaluated, and adhesion was evaluated for the test sample or the wallpaper coated with the test sample.

[0085] (Antibacterial evaluation test) The antibacterial properties were evaluated using a Lumitester. The Lumitester evaluates antibacterial properties based on the ATP method, which uses the luciferase, a bioluminescent enzyme from fireflies, to measure the amount of ATP (adenosine triphosphate) luminescence, which is contained in all living organisms as an energy substance, as an indicator of microorganisms and dirt. After applying each test sample to the wallpaper, it was left for 10 minutes. After confirming that no moisture soaked into the tissue paper placed on the wallpaper, the wallpaper was wiped with a cotton swab attached to the ATP measurement kit "Lucifer AT100" manufactured by Kikkoman Biochemifa Co., Ltd. The cotton swab was then inserted into the company's luminometer "Lumitester C-110" to emit light and measure the amount of ATP luminescence.

[0086] (Liquid contact angle test) The liquid contact angle of the surface of the test specimens was measured. The measuring device used was the "DMs-401" manufactured by Kyowa Interface Science Co., Ltd. The liquid contact angle test was conducted in accordance with JIS-R3257 (1999), by placing a droplet (test specimen) on the test piece and measuring the angle. The resulting values ​​were obtained by averaging three values ​​obtained by performing the test three times for each test specimen. The liquid contact angle test was conducted using a flat glass plate measuring 50 mm × 100 mm and 1.6 mm in thickness as the test specimen, under conditions of 23.5 ± 1 °C and 65 ± 1% relative humidity.

[0087] (B type viscosity, etc.) For the test example, the viscosity of type B at 6 rpm and the viscosity of type B at 60 rpm were measured, and the thixotropy index (Ti value) was determined. The Ti value is calculated using the following formula. (Ti value) = (B-type viscosity at 6 rpm) / (B-type viscosity at 60 rpm)

[0088] (Uneven paint application) The unevenness of the coating on the wallpaper treated with the test sample was checked after 60 minutes of standing, according to the following evaluation criteria. ◎: The entire coated area was visually inspected and no unevenness in the coating was observed. ○: Upon visual inspection of the entire coated area, no unevenness in the coating was generally observed. △: Upon visual inspection of the entire coated area, unevenness in the coating was observed, which could potentially cause problems in the future. ×: Upon visual inspection of the entire coated area, unevenness was observed, which is highly likely to cause problems in the future.

[0089] (Persistence) The adhesion of the test sample to the wallpaper was confirmed after 60 minutes of standing according to the following evaluation criteria. ◎: When applied as a test sample, it does not repel and exhibits excellent adhesion. ○: When the test sample was applied, there was generally no repulsion and the adhesion was good. △: When the test sample was applied, there was some repulsion, indicating a slight problem with adhesion. ×: When the sample was applied, it repelled, indicating a significant problem with adhesion.

[0090] The results are shown in Table 2. [Table 2]

[0091] Furthermore, VOC concentration tests, antiviral tests, and antibacterial tests were performed on Test Example 1 as follows.

[0092] (VOC concentration test) The concentration of formaldehyde was measured using the sampling bag method (ISO / IEC-17025). The test procedure was as follows: A 125 mm diameter filter paper coated with Test Example 1 was used as the test specimen. The test specimen was placed in a Tedlar bag with the bottom end cut off, and after removing as much air as possible from the bag, it was sealed with a sealing band. 3 L of formaldehyde gas, adjusted to a predetermined concentration from paraformaldehyde, was sealed into the bag. The bag containing formaldehyde was left undisturbed in the dark, and an empty bag was also left undisturbed in the dark as a blank test and the same test was performed. The test results are shown in Table 3.

[0093] [Table 3]

[0094] (Antiviral testing) Antiviral testing was conducted in accordance with ISO 21702. The viruses used in the test were influenza A virus (H3N2 type) and feline calicivirus (norovirus surrogate). The test procedure was as follows:

[0095] Polyethylene boards 1 and 2 (each 3 cm x 3 cm) were coated with Test Example 1 to a thickness of 2 μm. A polyethylene board 3 (blank) with no coating was prepared as a comparative example (blank). The liquid containing the virus was dropped onto the coated surfaces of polyethylene boards 1 and 2, and onto one side of polyethylene board 3, and the liquid was covered with a film and pressed down. Polyethylene board 1 (Test Example 1) and polyethylene board 3 (blank) were left at 25°C and 90% humidity for 24 hours. After 24 hours, the liquid was collected and inoculated into cells. The number of remaining viruses was measured by counting the pores formed in the cells by viral infection using the plaque method. For polyethylene board 2 (Test Example 1), the liquid containing the virus was dropped onto it, the liquid was covered with a film and pressed down, and the liquid was immediately collected and inoculated into cells. The number of remaining viruses was measured by counting the pores formed in the cells by viral infection using the plaque method. The results are shown in Figure 1. When comparing the results after 24 hours, polyethylene board 1 coated with test example 1 showed a significantly lower viral infectivity titer than the blank polyethylene board 3.

[0096] On the other hand, the antiviral activity value of the polyethylene board coated with Test Example 1 was 4.3, which significantly exceeded the threshold value of 2.0 or higher. This result indicates that the polyethylene board coated with Test Example 1 has high antiviral activity against influenza A virus (H3N2 type, enveloped virus).

[0097] (Antibacterial test) A polyethylene board 11 coated with Test Example 1 and a blank polyethylene board 12 were prepared, and an antibacterial test was conducted in accordance with JIS-Z-2801. The results are shown in Figure 2. The result showed that the antibacterial activity value of polyethylene board 11 coated with Test Example 1 was 3.9, which exceeded the judgment criterion value of 2.0, indicating an antibacterial effect against E. coli.

[0098] (others) The B-type viscosity of the water-based paint composition for wallpaper was measured at 25°C in accordance with JIS-Z8803 (2011) "Method for Measuring the Viscosity of Liquids". B-type viscosity is the resistance torque when the dispersion is stirred, and a higher value means that more energy is required for stirring. Unless otherwise specified, the JIS, TAPPI, and other tests and measurement methods described in the above specification are performed at room temperature, particularly 25°C, and at atmospheric pressure, particularly 1 atm. [Industrial applicability]

[0099] This invention can be used for wallpaper installed in buildings.

Claims

1. A polyphenol, a surfactant, and cellulose nanofibers with an average fiber diameter of 1 nm or more and 1000 nm or less, A water-based paint composition for wallpaper characterized by the following features.

2. Furthermore, it contains a thickening agent. The water-based paint composition for wallpaper according to claim 1.

3. The aforementioned surfactant is a naturally derived surfactant. The water-based paint composition for wallpaper according to claim 1.

4. The aforementioned polyphenol is a polyphenol derived from recycled materials. The water-based paint composition for wallpaper according to claim 1.

5. Furthermore, it contains an antibacterial agent. The water-based paint composition for wallpaper according to claim 1.

6. For the total amount of the water-based paint composition for wallpaper, The aforementioned polyphenol is contained in an amount of 1 to 10%, and the aforementioned surfactant is contained in an amount of 0.1% or more and 0.5% or less. The water-based paint composition for wallpaper according to claim 1.

7. To be applied to water-repellent wallpaper, The water-based paint composition according to claim 1.

8. The B-type viscosity at 6 rpm is 20 to 1000 mPa·s. The water-based paint composition for wallpaper according to claim 1.