White Sheet

Abstract

To provide a white sheet having good antifouling property whose at least one of antibacterial property and mildew resistance is good.SOLUTION: A white sheet 10 has a base material sheet 1 containing a resin, and a coat layer 2 positioned on one surface side of the base material sheet, in which the coat layer contains an organic nitrogen sulfur-based compound, on the surface on the coat layer side of the white sheet, ISO whiteness according to JIS P 8148 is 80% or more, antifouling property according to JIS L 1919 (A-1 method) is the third grade or higher, and a mold growth level according to JIS Z 2911:2010 (Appendix A, method B) when 30 days have elapsed is 1 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a white sheet. [Background technology]

[0002] For example, from the viewpoint of public health, there is a demand for a sheet having at least one of good antibacterial and antifungal properties. For example, Patent Document 1 discloses a transfer sheet having a release agent layer containing 5 to 50% by weight of an antifungal agent and / or an antibacterial agent. Patent Document 2 discloses a hard coat made of an active energy ray-curable resin composition containing a multifunctional (meth)acrylate and (B) an organic nitrogen-sulfur-based antibacterial agent, and further discloses a decorative sheet including the hard coat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-47798 [Patent Document 2] JP 2017-222813 A Summary of the Invention [Problem to be solved by the invention]

[0004] Since antibacterial and antifungal ingredients usually act on the surface of a sheet, if the sheet surface becomes dirty, the antibacterial and antifungal properties are likely to decrease. In addition, if the sheet is transparent, dirt attached to the surface is difficult to see, and it is difficult to notice the decrease in functionality caused by dirt. Therefore, there is a demand for functional sheets (functional films) that make it easy to see that dirt is attached, that are difficult to get dirty, and that are easy to clean.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a white sheet having good antifouling properties and good at least one of antibacterial properties and antifungal properties. [Means for solving the problem]

[0006] The present disclosure provides a white sheet having a base sheet containing a resin and a coating layer located on one side of the base sheet, the coating layer containing an organic nitrogen-sulfur compound, the surface of the white sheet facing the coating layer having an ISO whiteness of 80% or more based on JIS P 8148, stain resistance of grade 3 or higher based on JIS L 1919 (A-1 method), and a mold growth level of 1 or less after 30 days based on JIS Z 2911:2010 (Annex A, Method B).

[0007] The present disclosure provides a white sheet having a base sheet containing a resin and a coating layer located on one side of the base sheet, wherein the coating layer contains an organic nitrogen-sulfur compound, and the surface of the white sheet facing the coating layer has an ISO whiteness of 80% or more based on JIS P 8148, a stain resistance of grade 3 or more based on JIS L 1919 (A-1 method), and an antibacterial activity value R against Escherichia coli of 5 or more based on JIS Z 2801:2010. Effect of the Invention

[0008] The white sheet of the present disclosure has the effect of having good antifouling properties, and also having good at least one of antibacterial properties and antifungal properties. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view illustrating a white sheet in the present disclosure. [Diagram 2] 1 is a schematic cross-sectional view illustrating a white sheet in the present disclosure. [Diagram 3] 1 is a schematic cross-sectional view illustrating a white sheet in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The white sheet in the present disclosure will be described in detail below. In this specification, when expressing an aspect in which another member is disposed relative to a certain member, the term "above" or "below" includes both a case in which another member is disposed directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is disposed above or below a certain member via another member, unless otherwise specified.

[0011] Similarly, when expressing an aspect in which another member is disposed on the surface of a certain member, the term "on the surface side" includes both a case in which another member is disposed so as to be in contact with the surface of a certain member, and a case in which another member is disposed on the surface of a certain member via another member, unless otherwise specified. In addition, the drawings in this disclosure may be shown in a schematic manner in terms of the width, thickness, and shape of each part compared to the actual form in order to make the explanation clearer. In addition, in this disclosure, "sheet" and "film" may be used synonymously.

[0012] FIG. 1 is a schematic cross-sectional view illustrating a white sheet according to the present disclosure. The white sheet 10 in FIG. 1 has a base sheet 1 and a coating layer 2 that is located on one side of the base sheet 1 and contains an organic nitrogen-sulfur compound. Furthermore, the surface S1 of the white sheet 10 on the side of the coating layer 2 has an ISO whiteness of a predetermined value or more, and an antifouling property of a predetermined rating or more. Furthermore, it is preferable that the mold growth level on the surface S1 after 30 days is a predetermined rating or less. Similarly, it is preferable that the antibacterial activity value R against Escherichia coli on the surface S1 is a predetermined rating or more.

[0013] The white sheet of the present disclosure has good antifouling properties and at least one of antibacterial properties and antifungal properties. As described above, antibacterial and antifungal components usually act on the sheet surface, so that if the sheet surface becomes dirty, the antibacterial and antifungal properties are likely to decrease. In contrast, the white sheet of the present disclosure has good antifouling properties, so that the sheet surface is not easily soiled, and even if it does become dirty, it can be easily cleaned. In addition, since the white sheet of the present disclosure has a high ISO whiteness, dirt is easily noticeable. In particular, the calculation of the antibacterial activity value R against E. coli and the evaluation of the mold growth level are based on visual or microscopic observation of the state, so the higher the ISO whiteness, the stricter the evaluation. Even with such a strict evaluation, the white sheet of the present disclosure has the effect of having at least one of good antibacterial properties and antifungal properties.

[0014] In addition, in the white sheet of the present disclosure, the coating layer contains an organic nitrogen-sulfur compound. Here, the antibacterial agent and antifungal agent are mainly known to be an organic synthetic system such as an organic nitrogen-sulfur system, a metal ion system such as an Ag ion system or a Cu ion system, a natural inorganic system such as TiO2, or a natural organic system such as hinokitiol, each of which has a different mechanism of antibacterial and antifungal properties.

[0015] Here, specific examples of the mechanism of the organic synthesis system include cell wall binding and enzyme inhibition. Organic synthesis systems are highly effective against bacteria and fungi (mold) and are also highly safe, so they are sometimes used in food and cosmetics. Another advantage of organic synthesis systems is that they can be easily made into ink and coated. On the other hand, specific examples of the mechanism of the metal ion system include protein function inhibition. Metal ion systems have the advantage of being long-lasting and highly safe, but they are prone to oxidation and the formation of coexisting substances (such as S). 2- , Cl - ) has the disadvantage of being easily affected.

[0016] Furthermore, a specific example of the mechanism of natural inorganic systems is a strong oxidation reaction. Natural inorganic systems have the advantage of being fast-acting and exhibiting strong bactericidal power, but the disadvantages are that they require activation by ultraviolet light and that they also embrittle other components of the sheet (e.g. resin). Furthermore, a specific example of the mechanism of natural organic systems is the inhibition of protein function. Natural organic systems have the advantage of being safe because they have a long history of use, but the disadvantage is that they place a large burden on the environment because they are dependent on natural resources.

[0017] As described above, there are many types of antibacterial and antifungal agents, but as mentioned above, organic synthetic agents have the advantages of being highly effective and safe, and easy to coat. They also have the advantages of being relatively less susceptible to oxidation and coexisting substances, not requiring activation by ultraviolet light, and having a small environmental impact.

[0018] 1. Coating layer The coating layer in the present disclosure is a layer located on one side of the base sheet. The coating layer contains an organic nitrogen-sulfur compound. The organic nitrogen-sulfur compound usually functions as at least one of an antifungal agent and an antibacterial agent.

[0019] An organic nitrogen-sulfur compound is usually an organic compound having one or more nitrogen atoms and one or more sulfur atoms in one molecule. An organic nitrogen-sulfur compound is a heterocyclic compound containing one or more nitrogen atoms as heteroatoms, and may have one or more sulfur atoms in one molecule.

[0020] Examples of organic nitrogen-sulfur compounds include isothiazoline compounds such as 2-methyl-4-isothiazolin-3-one (CAS number 2682-20-4), 1,2-benzoisothiazolin-3-one (CAS number 2634-33-5), 5-chloro-2-methyl-4-isothiazolin-3-one (CAS number 26472-55-4), and 2-n-octyl-4-isothiazolin-3-one (CAS number 26530-20-1); and pyrithione compounds such as 1-hydroxypyridine-2(1H)-thione.

[0021] Specific examples of organic nitrogen-sulfur compounds include the Neosintol series, such as Neosintol AF-362N and Neosintol AF935 (manufactured by Sumika Environmental Science Co., Ltd.), SB-50 (manufactured by Ohara Palladium Chemical Co., Ltd.), Sanaisol 5404 (manufactured by San-ai Oil Co., Ltd.), and Hokuside 6500 (manufactured by Hokko Sangyo Co., Ltd.) The coating layer may contain only one type of organic nitrogen-sulfur compound, or two or more types.

[0022] The ratio of the organic nitrogen sulfur-based compound in the coating layer is, for example, 5% by mass or more, 7% by mass or more, or 10% by mass or more, based on the resin contained in the coating layer. If the ratio of the organic nitrogen sulfur-based compound is too small, sufficient antibacterial or antifungal properties may not be obtained. On the other hand, the ratio of the organic nitrogen sulfur-based compound in the coating layer is, for example, 30% by mass or less, 20% by mass or less, or 15% by mass or less, based on the resin contained in the coating layer. If the ratio of the organic nitrogen sulfur-based compound is too high, there is no difference in the antibacterial and antifungal effects, and there is a possibility that it is disadvantageous in terms of cost. In addition, it is preferable to select a concentration within the above range appropriately from the viewpoint of effect persistence. The coating layer may be located only on one side of the substrate sheet, or may be located on one side and the other side of the substrate sheet.

[0023] The coating layer usually contains a resin in addition to the organic nitrogen-sulfur compound. The resin is not particularly limited, but may be, for example, a polyurethane resin, an acrylic resin, or a polyester resin. The coating layer may contain one type of resin, or may contain two or more types of resin. The polyurethane resin is preferable because it has a high surface strength as a thin film. Examples of the polyurethane resin include polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polycaprolactam polyurethane, and mixtures thereof.

[0024] The glass transition temperature Tg (° C.) of the polyurethane resin is not particularly limited, but is, for example, −60° C. or higher and 0° C. or lower. The weight average molecular weight Mw of the polyurethane resin is not particularly limited, but is, for example, 10,000 or higher and 80,000 or lower.

[0025] The polyurethane resin can be obtained by reacting a polyisocyanate compound with a polymer polyol by a known method such as solution polymerization, and, if necessary, using a chain extender and a reaction terminator in the urethane prepolymer.

[0026] Examples of the polyisocyanate compound include aliphatic isocyanates such as 1,6-hexamethylene diisocyanate, methylene diisocyanate, trimethylene diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, 1,2-propylene diisocyanate, isopropylene diisocyanate, and 1,3-butylene diisocyanate; alicyclic isocyanates such as 1,3- or 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, and methyl-2,6-cyclohexane diisocyanate; and aromatic isocyanates such as m- or p-phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, and naphthylene diisocyanate.

[0027] Examples of the polymer polyol include polyester polyols such as saturated hydrocarbon-based polyester polyols, polyether polyols, and polyether ester polyols.

[0028] Examples of polyester polyols include polyester polyols obtained from polyvalent carboxylic acids and polyhydric alcohols, and polyester polyols obtained by ring-opening polymerization of lactone rings.

[0029] Examples of polycarboxylic acids include aliphatic polycarboxylic acids such as linear saturated hydrocarbon-based adipic acid, azelaic acid, succinic acid, and sebacic acid; unsaturated aliphatic polycarboxylic acids such as unsaturated fatty acid-based fumaric acid and maleic acid; alicyclic polycarboxylic acids such as 1,4-cyclohexanedicarboxylic acid having a cyclohexyl group; and aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid.

[0030] Examples of polyhydric alcohols include aliphatic and alicyclic polyhydric alcohols and aromatic polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,3-propylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, xylylene glycol, polyethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, and 1,5-pentanediol.

[0031] On the other hand, examples of polyether polyols include polyether polyols obtained by polymerizing an oxirane compound such as ethylene oxide or propylene oxide with a polyhydric alcohol such as ethylene glycol, 1,2-propanediol, or glycerin as a polymerization initiator. Also, examples of polyether ester polyols include polyether ester polyols obtained by reacting the above polyether polyols with the above polyvalent carboxylic acids.

[0032] The coating layer may contain only one type of resin, or may contain two or more types of resin. The proportion of the resin in the coating layer is, for example, 60% by mass or more, or may be 70% by mass or more, or may be 80% by mass or more.

[0033] The ISO whiteness of the surface of the white sheet facing the coating layer as evaluated by JIS P 8148 is, for example, 80% or more, and may be 85% or more. The higher the ISO whiteness, the more easily stains are noticeable, and the white sheet can be made hygienic. Here, "the surface of the white sheet facing the coating layer" refers to the surface of the white sheet located on the coating layer side when the base sheet is used as a reference, and corresponds to, for example, the surface S1 in FIG. 1. On the other hand, the ISO whiteness of the surface of the white sheet facing the coating layer based on JIS P 8148 may be 100% or less than 100%. The method for measuring the ISO whiteness will be described in the examples below.

[0034] The visible light reflectance on the surface of the coating layer side of the white sheet is preferably high. The average reflectance of visible light (wavelength 380 nm or more and 780 nm or less) is, for example, 70% or more, and may be 80% or more, or may be 90% or more. The visible light reflectance can be measured by measuring the reflectance (total reflectance) in the visible region wavelength 380 nm or more and 780 nm or less at an incidence angle of 8° using an ultraviolet-visible-near infrared spectrophotometer (Shimadzu UV-3600) and an integrating sphere attachment (ISR-3100), and calculating the average reflectance. Note that Spectralon (made of Teflon (registered trademark)) manufactured by Labsphere, USA is used as the standard plate.

[0035] The stain-resistant property of the surface of the white sheet facing the coating layer based on JIS L 1919 (A-1 method) is, for example, grade 3 or higher, may be grade 3.5 or higher, or may be grade 4 or higher. The higher the stain-resistant property, the less likely the sheet is to be soiled, and even if soiled, the easier it is to remove the stain. On the other hand, the stain-resistant property of the surface of the white sheet facing the coating layer based on JIS L 1919 (A-1 method) may be grade 5 or lower. Details of the method for evaluating the stain-resistant property will be described in the examples below.

[0036] On the surface of the coating layer side of the white sheet, the mold growth level after 30 days based on JIS Z 2911:2010 (Annex A, Method B) is preferably 1 or less, and may be 0. Details of the mold growth level evaluation method will be described in the examples below.

[0037] The antibacterial activity value R against E. coli on the surface of the coating layer side of the white sheet based on JIS Z 2801:2010 is, for example, 5 or more, and may be 6 or more. On the other hand, the antibacterial activity value R against E. coli on the surface of the coating layer side of the white sheet is not particularly limited, but is, for example, 8 or less. Details of the method for calculating the antibacterial activity value R against E. coli will be described in the examples below.

[0038] The coating layer preferably does not have hard coat properties. "Not having hard coat properties" means that the standard when a pencil hardness test based on JIS K 5600 is carried out is 2H or less, and may be H or less.

[0039] The thickness of the coating layer is not particularly limited, but may be, for example, 0.1 μm or more, 0.3 μm or more, or 0.6 μm or more. If the coating layer is too thin, sufficient antibacterial or antifungal properties may not be obtained. On the other hand, the thickness of the coating layer may be, for example, 5.0 μm or less, or 2.5 μm or less. If the coating layer is too thick, the antifouling properties may be reduced. In addition, the white sheet may have a coating layer on the outermost surface or inside.

[0040] The method for forming the coating layer may be, for example, a method of coating a composition for forming a coating layer containing an organic nitrogen-sulfur compound. The coating method may be, for example, gravure coating, reverse roll coating, spray coating, knife coating, wire bar coating, air knife coating, doctor blade coating, dip coating, or die coating. After coating the composition for forming the coating layer, it is preferable to dry it.

[0041] 2. Base sheet The base sheet in the present disclosure contains a resin. The base sheet may be a non-oriented sheet or a oriented sheet (a uniaxially oriented sheet or a biaxially oriented sheet).

[0042] (1) Resin The type of resin in the base sheet is not particularly limited, and typically includes thermoplastic resin. Examples of the resin include polyolefin resin, acrylic resin, styrene resin, vinyl fluoride resin, amide resin, and saturated ester resin, and among them, polyolefin resin is preferred. This is because it has excellent heat resistance, water resistance, chemical resistance, and cost.

[0043] Examples of polyolefin resins include homopolymers of olefins, copolymers of two or more kinds of olefins, and copolymers of one or more kinds of olefins and one or more kinds of polymerizable monomers polymerizable with the olefins. Examples of the olefins (monomer units) include ethylene, propylene, butene, and hexene. The copolymers may be binary, ternary, or quaternary. The copolymers may be random or block copolymers.

[0044] Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of polyethylene resins include high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), and very low density polyethylene (VLDPE). These may be used alone or in combination of two or more.

[0045] Among these, high density polyethylene and linear low density polyethylene are preferred, and high density polyethylene is more preferred. This is because high density polyethylene has excellent weather resistance and tensile strength. Furthermore, a sheet containing high density polyethylene does not sag even when rolled into a long length, and is less likely to suffer from poor appearance due to whitening during folding processing. In addition, high density polyethylene is opaque, and the whiteness of the white sheet can be easily improved by adding inorganic fillers such as titanium oxide and calcium carbonate.

[0046] In particular, when the resin component is only a polyethylene resin, it is preferable to use at least one of high density polyethylene and linear low density polyethylene. High density polyethylene is particularly suitable for sheet molding by calendar processing because of its excellent heat resistance and processability during processing.

[0047] The polyethylene resin may have a melt flow rate (temperature 230° C., load 2.16 kg) of, for example, 0.1 g / 10 min or more and 4.0 g / 10 min or less, or 0.4 g / 10 min or more and 2.0 g / 10 min or less, measured based on JIS K 7210. When the melt flow rate (MFR) is in the above range, it is particularly suitable for sheet molding by calendar processing.

[0048] The base sheet may contain a polyethylene resin as a main resin component. The proportion of the polyethylene resin in the total amount of the resin components is, for example, 50% by mass or more, and may be 70% by mass or more.

[0049] On the other hand, examples of polypropylene-based resins include homopolymer polypropylene (h-PP), random copolymer polypropylene (r-PP), block copolymer polypropylene (b-PP), and metallocene polypropylene. These may be used alone or in combination of two or more. Among these, random copolymer polypropylene is preferred. This is because random copolymer polypropylene has more flexibility than homopolymer polypropylene and block copolymer polypropylene.

[0050] The polypropylene-based resin may be a copolymer of propylene and another α-olefin. The other α-olefin may be, for example, at least one of ethylene, butene-1, hexene-1, and heptene-1,4-methylpentene-1. The polypropylene-based resin preferably contains propylene as a main component of the monomer unit.

[0051] The polypropylene resin may have a melt flow rate (temperature 230° C., load 2.16 kg) of, for example, 0.1 g / 10 min or more and 4.0 g / 10 min or less, or may have a melt flow rate of 0.4 g / 10 min or more and 2.0 g / 10 min or less, as measured in accordance with JIS K 7210. When the melt flow rate (MFR) is in the above range, it is particularly suitable for sheet molding by calendar processing.

[0052] The base sheet may contain a polypropylene-based resin as a main component of the resin components. The ratio of the polypropylene-based resin to the total amount of the resin components is, for example, 50% by mass or more, and may be 70% by mass or more. The base sheet may contain both a polypropylene-based resin and a polyethylene-based resin as the resin components.

[0053] Other polyolefin resins include, for example, copolymers having at least one of an ethylene-propylene copolymer component and a polybutylene component, and a polypropylene component (so-called reactor TPO).

[0054] (2) Inorganic fillers The base sheet preferably contains an inorganic filler. This is because the whiteness and light reflectivity can be increased by adding an inorganic filler. Examples of inorganic fillers include calcium carbonate, titanium oxide, talc, and a solid solution of titanium oxide, antimony oxide, and nickel oxide. Among these, calcium carbonate and titanium oxide are preferred. This is because they are easy to increase the whiteness and light reflectivity. The base sheet preferably contains at least one of calcium carbonate and titanium oxide as the inorganic filler as a main component, and may contain only at least one of calcium carbonate and titanium oxide.

[0055] The content of the inorganic filler in the base sheet is, for example, 30% by mass or more, 50% by mass or more, 55% by mass or more, or 60% by mass or more, based on the resin. If the content of the inorganic filler is too low, the whiteness and light reflectivity of the base sheet may be reduced. On the other hand, the content of the inorganic filler is, for example, 80% by mass or less, 75% by mass or less, or 70% by mass or less, based on the resin. If the content of the inorganic filler is too high, the flexibility of the base sheet may be reduced.

[0056] (3) Additives The substrate sheet preferably contains additives such as a light stabilizer, an antioxidant, and an ultraviolet absorber.

[0057] (i) Light stabilizers The type of the light stabilizer is not particularly limited, but examples thereof include hindered amine-based light stabilizers, and among these, NOR-type hindered amine-based light stabilizers are preferred. This is because NOR-type hindered amine-based light stabilizers have excellent acid resistance. An example of the NOR-type hindered amine-based light stabilizer is a compound containing a group represented by general formula (1).

[0058] [ka]

[0059] In general formula (1), R is a substituted or unsubstituted hydrocarbon group or acyl group. Examples of R include an alkyl group, an alkenyl group, an alkylene group, a cycloalkyl group, a bicycloalkyl group, a phenyl group, a naphthyl group, a phenylalkyl group, an alkyl group-substituted phenyl group, a hydroxyl group-substituted alkyl group, an acyl group, an alkoxy-substituted alkyl group, and a thioalkoxy-substituted alkyl group. In general formula (1), * and ** indicate a state in which they can bond with other elements.

[0060] Other examples of the NOR type hindered amine light stabilizer include compounds represented by general formula (2) or general formula (3).

[0061] [ka]

[0062] In the general formula (2), R1 and R2 are each independently a substituted or unsubstituted hydrocarbon group or acyl group, similar to R in the above-mentioned general formula (1). Among them, it is preferable that R1 and R2 are each independently an alkyl group having 4 to 20 carbon atoms.

[0063] In general formula (3), R3 and R4 are each independently a substituted or unsubstituted hydrocarbon group or acyl group, similar to R in general formula (1) described above. Of these, R3 and R4 are each preferably independently an alkyl group having 4 to 20 carbon atoms. R5 is an alkylene group having 1 to 8 carbon atoms.

[0064] Specific examples of NOR type hindered amine light stabilizers include Adeka STAB LA-81 manufactured by Adeka Corporation and Tinuvin 123 (decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester) manufactured by BASF.

[0065] The content of the light stabilizer in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or may be 0.15% by mass or more, based on the resin. If the content of the light stabilizer is too low, the weather resistance of the base sheet may not be improved. Also, the content of the light stabilizer may be, for example, more than 5% by mass, based on the resin. On the other hand, the content of the light stabilizer is, for example, 20% by mass or less, may be 9.0% by mass or less, or may be 8.0% by mass or less, based on the resin. If the content of the light stabilizer is too high, the base sheet may have an appearance abnormality such as cracks.

[0066] (ii) Antioxidants The type of antioxidant is not particularly limited, and examples thereof include phenol-based antioxidants and phosphorus-based antioxidants. Examples of phenol-based antioxidants include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,6-di-t-butyl-4-methylphenol, 4,4'-methylene-bis(2,6-di-t-butyl)phenol, 4,4'-butylidene-bis(6-t-butyl-3-methyl)phenol, 2,2-methylene-bis(6-t-butyl-3-methyl)phenol, 2,2-methylene-bis(4-methyl)phenol, and the like. n-Octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-oc ...

[0067] On the other hand, examples of phosphorus-based antioxidants include trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl)phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, di(tridecyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2 ,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(tridecyl)-4,4'-n-butylidenebis(2-tert-butyl-5-methylphenol)diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert-butylphenyl)biphenylene diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl)amine.

[0068] The content of the antioxidant in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or may be 0.4% by mass or more, based on the resin. If the content of the antioxidant is too low, the weather resistance of the base sheet may not be improved. On the other hand, the content of the antioxidant in the base sheet is, for example, 5.0% by mass or less, may be 3.0% by mass or less, or may be 1.0% by mass or less, based on the resin. If the content of the antioxidant is too high, it may lead to poor appearance due to bleed-out.

[0069] (iii) Ultraviolet absorber The type of ultraviolet absorber is not particularly limited, but examples thereof include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Further, examples of benzotriazole-based ultraviolet absorbers include 2-hydroxyphenylbenzotriazole compounds such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-carboctoxyethylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole, and 2,2'-methylenebis(4-tert-octyl-6-benzotriazolylphenol).

[0070] The content of the ultraviolet absorbent in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or may be 0.4% by mass or more, based on the resin. If the content of the ultraviolet absorbent is too small, the weather resistance of the base sheet may not be improved. On the other hand, the content of the ultraviolet absorbent in the base sheet is, for example, 5.0% by mass or less, may be 3.0% by mass or less, or may be 1.0% by mass or less, based on the resin. If the content of the ultraviolet absorbent is too high, it may lead to poor appearance due to bleed-out, or poor appearance due to coloring depending on the type of ultraviolet absorbent.

[0071] (iv) Other The base sheet may contain a heavy metal deactivator. Examples of the heavy metal deactivator include oxalic acid derivatives, salicylic acid derivatives, and hydrazide derivatives. More specifically, Eastman Inhibitor OAB H (manufactured by Eastman Kodak Co.), Adeka STAB CDA-1, CDA-6 (both manufactured by Adeka Corp.), Chel-180, and Inganox MD 1024 (both manufactured by BASF Corp.) can be exemplified. The base sheet may also contain appropriate amounts of known additives such as lubricants, heat stabilizers, pigments, modifiers, flame retardants, antistatic agents, reinforcing agents, antibacterial agents, and fungicides. The base sheet may not contain an antibacterial agent, and may not contain a fungicide.

[0072] (4) Base sheet The substrate sheet may be a sheet without voids inside, or may be a sheet with voids inside (porous substrate sheet). The substrate sheet may have a single layer structure or a multi-layer structure. When the substrate sheet has a multi-layer structure, the resin components contained in each layer may be the same or different. An example of a substrate sheet with a multi-layer structure is a substrate sheet having an inner layer and two outer layers located on both sides of the inner layer, the resin components contained in the two outer layers are the same, and the resin components contained in the outer layers are different from the resin components contained in the inner layer.

[0073] The surface of the base sheet has an ISO whiteness based on JIS P 8148 of, for example, 80% or more, and may be 85% or more. The higher the ISO whiteness of the base sheet, the higher the ISO whiteness of the surface of the coating layer side of the white sheet. On the other hand, the surface of the base sheet has an ISO whiteness based on JIS P 8148 of, for example, 100% or less.

[0074] The surface of the base sheet preferably has a high visible light reflectance. The average reflectance of visible light (wavelength 380 nm or more and 780 nm or less) is, for example, 70% or more, or may be 80% or more, or may be 90% or more.

[0075] The surface of the base sheet has an antifouling property based on JIS L 1919 (A-1 method) of, for example, grade 3 or higher, may be grade 3.5 or higher, or may be grade 4 or higher. The higher the antifouling property of the base sheet, the higher the antifouling property of the surface of the coating layer side of the white sheet tends to be. On the other hand, the surface of the base sheet has an antifouling property based on JIS L 1919 (A-1 method) of, for example, grade 5 or lower.

[0076] Furthermore, on the surface of the base sheet, the mold growth level after 30 days based on JIS Z 2911:2010 (Annex A, Method B) is preferably 1 or less, and may be 0.

[0077] Furthermore, the antibacterial activity value R against E. coli on the surface of the base sheet based on JIS Z 2801:2010 is, for example, 5 or more, and may be 6 or more. On the other hand, the antibacterial activity value R against E. coli on the surface of the base sheet is not particularly limited, but is, for example, 8 or less.

[0078] The substrate sheet may be a porous substrate sheet as described above. The average diameter of the voids in the porous substrate sheet is, for example, 1 μm or more and 50 μm or less, 2 μm or more and 40 μm or less, or 5 μm or more and 30 μm or less. The maximum diameter (L) of the voids and the maximum diameter (M) in the direction perpendicular thereto are measured and averaged to obtain the diameter of the voids [(L+M) / 2]. The diameters of at least n voids (n is an integer of 1 or more, preferably an integer of 100 or more) are measured, and the average value is the average diameter of the voids. For example, a scanning electron microscope S-2400 manufactured by Hitachi, Ltd. can be used to observe the cross section of the sample.

[0079] The porosity of the porous substrate sheet is, for example, 15% to 70%, or may be 35% to 60%, or may be 40% to 58%. Here, the porosity indicates the proportion of voids in the porous substrate sheet, and can be calculated by the following formula. Density of each layer = m of each layer 2 Mass per layer / thickness of each layer Porosity = (1 - density of each layer / density of base sheet without voids) x 100

[0080] The substrate sheet is preferably a sheet that is less susceptible to deterioration in a predetermined weather resistance test. In the present disclosure, the "weather resistance test" refers to a test in which a sample is subjected to an irradiance of 90 mW / cm 2 More than 100mW / cm 2 This refers to conducting a metal halide lamp weather resistance test (equipment standard: JTMG-01:2000, Japan Testing Machinery Manufacturers Association) under the following conditions. Note that the irradiance varies slightly depending on the equipment, so it is set to 90mW / cm2 with a range. 2 More than 100mW / cm 2 The irradiation time of the metal halide lamp is set as follows. The irradiation time of the metal halide lamp varies depending on the object to be evaluated, but is, for example, any time between 100 hours and 300 hours. Note that "after weather resistance test (irradiation time 100 hours)" described later can be read as any time between 100 hours and 300 hours. For example, "after weather resistance test (irradiation time 100 hours)" can be read as "after weather resistance test (irradiation time 300 hours)."

[0081] The base sheet preferably has a high visible light reflectance after the above-mentioned weather resistance test (irradiation time 100 hours). The average reflectance of visible light (wavelength 380 nm or more and 780 nm or less) after the weather resistance test is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more. The average visible light reflectance of the base sheet before the weather resistance test is defined as R0 (%), and the average visible light reflectance of the base sheet after the weather resistance test (irradiation time 100 hours) is defined as R 100 (%), R 100 The value of / R0 is, for example, 0.90 or more, and may be 0.95 or more.

[0082] The substrate sheet preferably has a large tensile strength after the above-mentioned weather resistance test (irradiation time 100 hours). The tensile strength after the weather resistance test may be, for example, greater than 7N / 15mm, 10N / 15mm or more, or 15N / 15mm or more. The tensile strength can be measured based on JIS K 7127 and JIS K 7161 using a precision universal testing machine (Shimadzu Corporation's "Autograph AG-500N") under the conditions of machine direction (MD), sample width 15mm, gauge length 15mm, and tensile speed 200mm / min.

[0083] The base sheet preferably has a large breaking elongation after the above-mentioned weather resistance test (irradiation time 100 hours). The breaking elongation after the weather resistance test is, for example, 300% or more, may be 400% or more, or may be 500% or more. The breaking elongation can be measured based on JIS K 7127. Specifically, the breaking elongation can be calculated from the length at which the sample breaks when pulled in the machine direction (MD direction) under conditions of a sample width of 15 mm and a speed of 200 mm / min using a precision universal testing machine (Shimadzu Corporation's "Autograph AG-500N"). Breaking elongation (%) = (L-Lo) / Lo x 100 Lo: sample length before test, L: sample length at break The breaking elongation of the base sheet before the weather resistance test was defined as E0 (%), and the breaking elongation of the base sheet after the weather resistance test (irradiation time 100 hours) was defined as E 100 (%), E 100 The value of / E0 is, for example, 0.50 or more, and may be 0.70 or more.

[0084] The resin in the base sheet preferably has a large number average molecular weight after the above-mentioned weather resistance test (irradiation time 100 hours). The number average molecular weight after the weather resistance test depends on the type of resin, but is, for example, 20,000 or more, may be 30,000 or more, or may be 50,000 or more. A high-temperature GPC device (Senshu Scientific SSC-7120 HT-GPC System) can be used to measure the number average molecular weight. As a pretreatment, the base sheet (test piece) is left to stand in o-dichlorobenzene at 145°C for 1 hour, then stirred for 1 hour to dissolve, and pressure filtered using membrane filters with filter pore sizes of 0.5 μm and 1.0 μm. The measurement conditions are set as follows. Sample: Approximately 5 mg of test piece per 3 mL of solvent Injection volume: 300μL Guard column: HT-G Column: HT-806M x 2 Column temperature: 145℃ Mobile phase: o-dichlorobenzene (containing 0.025% BHT by mass) Flow rate: 1.0mL / min Detector: Differential refractometer Molecular weight calibration: Polystyrene equivalent

[0085] The resin in the substrate sheet preferably has a high retention rate of the number average molecular weight after the above-mentioned weather resistance test (irradiation time 100 hours). The number average molecular weight of the resin before the weather resistance test is defined as M0, and the number average molecular weight of the resin after the weather resistance test (irradiation time 100 hours) is defined as M 100 In this case, M 100 The value of / M0 is, for example, 0.50 or more, optionally 0.60 or more, optionally 0.70 or more, or optionally 0.90 or more.

[0086] The thickness of the base sheet is not particularly limited, but may be, for example, 25 μm or more, may be, for example, 30 μm or more, or may be, for example, 40 μm or more. On the other hand, the thickness of the base sheet may be, for example, 90 μm or less, or may be, for example, 80 μm or less. By having the thickness of the base sheet within the above range, for example, when the base sheet is produced by calendar processing, a sheet having excellent surface smoothness and high thickness accuracy can be obtained.

[0087] The base sheet may have at least one of moisture permeability, air permeability, and water impermeability. Note that moisture permeability refers to the property of allowing water in a gaseous state, i.e., water vapor, to pass through, air permeability refers to the property of allowing gases such as carbon dioxide to pass through, and water impermeability refers to the property of not allowing water in a liquid state to pass through.

[0088] (5) Method for manufacturing the base sheet The method for producing the base sheet is not particularly limited as long as it is a method that can produce the desired base sheet, and examples of the method include a production method that has a step of producing a resin composition that contains at least a resin, and a step of forming the resin composition into a sheet (film) to produce the base sheet.

[0089] The method for preparing the resin composition is not particularly limited, but a method for preparing the resin composition by melt-kneading a predetermined amount of each raw material is preferable. Examples of the device used for melt-kneading include a continuous kneader, a Banbury mixer, a kneader, and an extruder. The heating temperature during melt-kneading is, for example, 150°C or more and 200°C or less.

[0090] Examples of methods for forming a resin composition into a sheet include known molding methods such as calendar processing and extrusion molding, and calendar processing is particularly preferred. For example, when the thickness of the sheet is thin, it is suitable for producing a sheet of uniform thickness. In addition, calendar molding is also suitable in that it is easy to respond to the size and type of resin due to the structure of the molding machine, and is easy to respond to small lots. Furthermore, in the present disclosure, when a resin composition with a high content of inorganic filler is used, it is preferable to mold it by calendar processing. When a large amount of inorganic filler is contained, for example, when molding by extrusion molding, the surface of the obtained sheet becomes rough and the sheet becomes easy to tear, but when molding by calendar processing, such inconvenience does not occur, and a sheet with a smooth surface can be produced. Furthermore, the superiority of calendar processing when using a resin composition with a high content of inorganic filler is particularly noticeable when the thickness of the base sheet is thin, for example, about 30 μm or more and 70 μm or less.

[0091] In the calendering process, for example, the resin composition obtained by melt kneading is supplied to a heated calender roll and rolled to obtain a base sheet. The heating temperature of the calender roll is, for example, 150° C. or more and 220° C. or less, and may be 160° C. or more and 190° C. or less. As the calendering device, a suitable one such as a three-roll type, a four-roll L-roll type, a four-roll inverted L-roll type, a four-roll Z-roll type, or a six-roll type may be used.

[0092] After the resin composition is formed into a sheet, it may be subjected to various surface treatments as necessary. Examples of the surface treatments include corona treatment (corona discharge treatment), plasma treatment, ultraviolet treatment, and electron beam treatment (electron beam radiation treatment).

[0093] 2. Reinforcement sheet The white sheet may have a reinforcing sheet on the side opposite to the coating layer of the base sheet. The reinforcing sheet is a sheet that reinforces the base sheet. The white sheet 10 shown in FIG. 2 has a reinforcing sheet 3 on the side opposite to the coating layer 2 of the base sheet 1. As shown in FIG. 2, the base sheet 1 and the reinforcing sheet 3 may face each other via another layer such as an adhesive layer 4, and as shown in FIG. 3, the base sheet 1 and the reinforcing sheet 3 may face each other so as to be in direct contact with each other.

[0094] Examples of the reinforcing sheet include nonwoven fabrics and woven fabrics. Examples of the nonwoven fabric include cross-fiber nonwoven fabrics, long fiber nonwoven fabrics, short fiber nonwoven fabrics, wet nonwoven fabrics, dry nonwoven fabrics, airlaid nonwoven fabrics, carded nonwoven fabrics, parallel nonwoven fabrics, cross nonwoven fabrics, random nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, flash-spun nonwoven fabrics, chemically bonded nonwoven fabrics, hydroentangled nonwoven fabrics, needle-punched nonwoven fabrics, stitch-bonded nonwoven fabrics, thermally bonded nonwoven fabrics, burst fiber nonwoven fabrics, tow-opened nonwoven fabrics, split fiber nonwoven fabrics, composite nonwoven fabrics, laminated nonwoven fabrics, coated nonwoven fabrics, and laminated nonwoven fabrics.

[0095] The cross-fiber nonwoven fabric is a nonwoven fabric formed by laminating two or more stretched sheets so that the stretching directions are perpendicular to each other, and an example of such a nonwoven fabric is Warif (registered trademark) manufactured by JX ANCI Co., Ltd. The cross-fiber nonwoven fabric has a basis weight of, for example, 5 g / m 2 More than 100g / m 2 Less than or equal to 20 g / m 2 More than 50g / m 2 The fiber diameter of the long fiber nonwoven fabric is, for example, 3 μm or more and 20 μm or less. The fiber diameter of the short fiber nonwoven fabric is, for example, less than 3 μm.

[0096] On the other hand, another example of the reinforcing sheet is a cross-type nonwoven fabric. An example of the cross-type nonwoven fabric is the polyolefin mesh cloth disclosed in JP 2007-259734 A. The polyolefin mesh cloth is preferably a polyethylene mesh cloth. The polyethylene mesh cloth is preferably used in consideration of the adhesiveness in extrusion molding, for example. The cross-type nonwoven fabric may have a thickness of, for example, 30 μm or more and 100 μm or less, and may be 50 μm or more and 80 μm or less.

[0097] The reinforcing sheet preferably contains a resin. The type of resin is not particularly limited, but is typically a thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins, acrylic resins, styrene resins, vinyl fluoride resins, amide resins, and saturated ester resins, and among these, polyolefin resins are preferred. In the present disclosure, the reinforcing sheet is preferably a fiber-crossed nonwoven fabric containing a polyolefin resin. This is because it has excellent heat resistance, water resistance, chemical resistance, and cost.

[0098] In the present disclosure, it is preferable that both the reinforcing sheet and the base sheet contain a polyethylene-based resin. This is because a white sheet in which both are firmly bonded can be obtained. In addition, since the degree of expansion and contraction due to heat, moisture, etc. is similar, there is also the advantage that warping is unlikely to occur. As a result, a white sheet with high durability is obtained. In addition, by using a polyethylene-based resin, a white sheet with high water resistance is obtained. In addition, when both the reinforcing sheet and the base sheet contain a polyethylene-based resin, the white sheet is recyclable and the environmental load at the time of disposal is small. In particular, it is preferable that the entire layer of the white sheet contains a polyethylene-based resin. In addition, the reinforcing sheet may contain a polypropylene-based resin, and the base sheet may contain a polyethylene-based resin. By adopting such a combination, the processability of the white sheet is improved.

[0099] The thickness of the reinforcing sheet is not particularly limited, but may be, for example, 10 μm or more and 150 μm or less, or may be 20 μm or more and 100 μm or less. In addition, the white sheet may have the reinforcing sheet on the outermost surface, or may have the reinforcing sheet inside.

[0100] 3.Adhesive layer When the white sheet has a base sheet and a reinforcing sheet, the white sheet may or may not have an adhesive layer between the base sheet and the reinforcing sheet. The adhesive layer preferably contains a resin such as a polyolefin resin. Such an adhesive layer can be obtained, for example, by extrusion coating a resin.

[0101] In the extrusion coating, resins that can be melted and mutually fused by heat can be used. Examples of such resins include polyethylene resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene, polypropylene resins such as polypropylene, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-propylene copolymers, methylpentene polymers, polybutene polymers, acid-modified polyolefin resins obtained by modifying polyolefin resins such as polyethylene or polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, polyvinyl acetate resins, poly(meth)acrylic resins, and polyvinyl chloride resins.

[0102] These may be used alone or in combination of two or more. Among these, polyethylene resins are suitable, with low-density polyethylene and linear low-density polyethylene being preferred, and low-density polyethylene being more preferred. Low-density polyethylene has excellent processability, excellent adhesion to polyethylene nonwoven fabrics, and is inexpensive.

[0103] The polyethylene resin may have a melt flow rate (temperature 230° C., load 2.16 kg) of, for example, 0.1 g / 10 min or more and 4.0 g / 10 min or less, or may have a melt flow rate of 0.4 g / 10 min or more and 2.0 g / 10 min or less, as measured based on JIS K 7210. When the melt flow rate (MFR) is in the above range, it is particularly suitable for extrusion coating.

[0104] In order to strengthen the adhesion between the base sheet and the reinforcing sheet, an anchor coating agent layer may be provided by coating the base sheet with an anchor coating agent. Examples of the anchor coating agent that forms the anchor coating agent layer include organic titanium anchor coating agents such as alkyl titanates, isocyanate anchor coating agents, polyethyleneimine anchor coating agents, and polybutadiene anchor coating agents.

[0105] The adhesive layer in the present disclosure may be a layer containing an adhesive material described later. Such an adhesive layer may be obtained, for example, by applying an adhesive composition. The type of adhesive is not particularly limited, but examples thereof include polyether-based adhesives, polyester-based adhesives, polyurethane-based adhesives, vinyl-based adhesives, (meth)acrylic adhesives, polyamide-based adhesives, epoxy-based adhesives, and rubber-based adhesives. The adhesive may be of one-component curing type or two-component curing type.

[0106] The thickness of the adhesive layer is, for example, 20 μm or less. For example, when the adhesive layer is formed by extrusion coating, the thickness of the adhesive layer is preferably 10 μm or more and 20 μm or less. Also, for example, when the adhesive layer is formed by applying an adhesive composition, the thickness of the adhesive layer is preferably 10 μm or less.

[0107] 4. White sheet The white sheet has at least a base sheet and a coating layer. The white sheet may further have other members such as a reinforcing sheet. It is preferable that the white sheet has a predetermined ISO whiteness, antifouling property, mold growth level, and antibacterial activity value R against E. coli on the surface on the coating layer side. These points are the same as those described in "1. Coating layer" above, so the description here is omitted.

[0108] The white sheet preferably has a high ISO whiteness after the above-mentioned weather resistance test (irradiation time 100 hours). The ISO whiteness (after weather resistance test) evaluated by JIS P 8148 on the surface of the coating layer side of the white sheet is, for example, 80% or more, and may be 85% or more. The higher the ISO whiteness, the more noticeable dirt becomes, and the more hygienic the white sheet can be. On the other hand, the ISO whiteness (after weather resistance test) based on JIS P 8148 on the surface of the coating layer side of the white sheet may be 100% or less than 100%.

[0109] The white sheet preferably has a high visible light reflectance after the above-mentioned weather resistance test (irradiation time 100 hours). The average reflectance of visible light (wavelength 380 nm or more and 780 nm or less) after the weather resistance test is, for example, 70% or more, or may be 80% or more, or may be 90% or more on the surface of the white sheet on the coating layer side. In addition, the above-mentioned average visible light reflectance of the white sheet before the weather resistance test is defined as R0 (%), and the above-mentioned average visible light reflectance of the white sheet after the weather resistance test (irradiation time 100 hours) is defined as R 100 (%), R 100 The value of / R0 is, for example, 0.90 or more, and may be 0.95 or more.

[0110] The white sheet (particularly the white sheet having the reinforcing sheet) preferably has a high tensile strength after the above-mentioned weather resistance test (irradiation time 100 hours). The tensile strength after the weather resistance test is, for example, greater than 40 N / 15 mm, may be 45 N / 15 mm or more, or may be 80 N / 15 mm or more.

[0111] The white sheet has a tear strength as measured by the Elmendorf tear method of, for example, 1.4 N or more, and may be 2.5 N or more. On the other hand, the tear strength is, for example, 15 N or less, and may be 10 N or less.

[0112] The white sheet may have a plurality of through holes penetrating from one surface to the other surface. The ratio of the through holes is, for example, 10,000 pieces / m 2 More than 1 million pieces / m 2 Less than 100,000 pieces / m 2 More than 700,000 pieces / m 2 It may be the following.

[0113] The thickness of the white sheet is not particularly limited, but is, for example, 25 μm or more, may be 50 μm or more, or may be 80 μm or more, while the thickness of the white sheet is, for example, 200 μm or less, or may be 150 μm or less.

[0114] The use of the white sheet is not particularly limited, and it can be used for any use that requires at least one of antibacterial properties and antifungal properties. Examples of uses of the white sheet include a covering sheet for covering the surface of a partition, a covering sheet for covering a floor or wall, a shoe rack (e.g., a shoe cabinet), a shelf for displaying goods, a covering sheet for furniture such as a bed or a sofa (particularly, a temporary covering sheet for furniture used by an unspecified number of people), and an apron such as a bib apron or a waist apron (particularly, a disposable apron). In addition, since the white sheet in the present disclosure has a high ISO whiteness, it can also be used as an agricultural sheet. The agricultural sheet can be used, for example, as a mulching sheet for covering soil or agricultural crops. In addition, the agricultural sheet can be used for general agricultural purposes such as resolving light deficiency, promoting coloring of harvested products, suppressing soil temperature, and controlling weeds.

[0115] The present disclosure is not limited to the above-described embodiment. The above-described embodiment is merely an example, and any embodiment that has substantially the same configuration as the technical idea described in the claims and exhibits similar effects is included in the technical scope of the present disclosure in any case. EXAMPLES

[0116] [Example 1] (Preparation of base sheet) 100 parts by mass of linear low-density polyethylene (LLDPE, melting point 125°C, MFR (190°C, 2160g): 2.0g / 10min) as a polyethylene resin, 0.1 parts by mass of 2(2'-hydroxy-5'-tert-octylphenyl)benzotriazole as an ultraviolet absorber, 0.4 parts by mass of NOR-type hindered amine-based light stabilizer (manufactured by Adeka Corporation, Adeka STAB LA-81, bis(1-undecaneoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate), 0.1 parts by mass of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as a phenolic antioxidant, 20 parts by mass of calcium carbonate (heavy calcium carbonate (PE master batch with a filling rate of 60%): PE content of 8 parts by mass) as inorganic filler 1, and 40 parts by mass of titanium pigment (PE master batch with a filling rate of 80%): PE content of 8 parts by mass) as inorganic filler 2 were mixed and melt-kneaded at 180°C using a Banbury mixer.

[0117] The total amount of the polyethylene resin contained in the kneaded product was 116 parts by mass, the content of the NOR type hindered amine light stabilizer relative to the polyethylene resin was 0.34% by mass, and the content of the inorganic fillers 1 and 2 relative to the polyethylene resin was 51.7% by mass.

[0118] Next, the obtained kneaded product was fed to a 12 inch diameter×30 L common head type mixing roll (rotation speed: 18 rpm) and rolled at a roll temperature of 165° C. to 190° C. to obtain a base sheet (polyethylene sheet) having a thickness of 30 μm.

[0119] (Preparation of white sheet) A urethane-based anchor coating agent was applied to the obtained substrate sheet to a thickness of 0.5 g / m 2An anchor coating agent layer (in a dry state) was formed. Furthermore, linear low density polyethylene (LLDPE, MI=8.0, density=0.911) was melt-extruded onto the anchor coating agent layer, and the melt-extruded resin surface was treated with ozone while being extrusion-coated to a thickness of 15 μm, and then laminated to a reinforcing sheet. The melt resin temperature of LLDPE was 260°C.

[0120] Next, a urethane-based ink containing an organic nitrogen-sulfur-based compound was applied to the surface of the base sheet opposite to the reinforcing sheet using a Mayer bar to form a coating layer, thereby obtaining a white sheet. <Composition of the urethane-based ink> - Two-part liquid type consisting of a base agent and a hardener - Ratio of base agent and hardener (base agent 91.3% by mass, hardener 8.7% by mass) Main component composition (organic nitrogen-sulfur compound (Neosintol AF-362N, Sumika Environmental Science Co., Ltd.) 6.6% by mass, varnish components (polyol, acrylic, solvent) 93.4% by mass) Hardener composition (isocyanate, ethyl acetate)

[0121] [Comparative Example 1] A white sheet was obtained in the same manner as in Example 1, except that no coating layer was formed.

[0122] [Comparative Example 2] A white sheet was obtained in the same manner as in Example 1, except that a silver-based compound (AC-10, manufactured by Sinanen Zeomic Co., Ltd.) was used instead of the organic nitrogen-sulfur-based compound.

[0123] [Comparative Example 3] A white sheet was obtained in the same manner as in Example 1, except that a copper-based compound (G99, manufactured by CMS Technology, Inc.) was used instead of the organic nitrogen-sulfur-based compound.

[0124] [Comparative Example 4] A white sheet was obtained in the same manner as in Example 1, except that a nickel-based compound (Kenifine SH, manufactured by Takaaki Chemical Industry Co., Ltd.) was used instead of the organic nitrogen-sulfur-based compound.

[0125] [Comparative Example 5] A commercially available white sheet (HALSICKY (registered trademark), manufactured by Nichiei Shinka Co., Ltd.) was prepared.

[0126] [evaluation] (ISO whiteness measurement) The ISO whiteness was measured for the white sheets obtained in Example 1 and Comparative Examples 1 to 5. Specifically, based on JIS P 8148, a test piece was placed on a black background so as not to pick up the reflection of transmitted light, and the ISO whiteness of the surface of the white sheet on the coating layer side was measured using a spectrophotometer (CM-700d manufactured by Konica Minolta). The light source was set to D65 light source, and the viewing angle was set to 2°. The measurement was performed in the reflection mode SCI (Specular Component Include, including regular reflection light) mode.

[0127] The test pieces after the weathering test were also subjected to the ISO whiteness measurement. In the weathering test, the test pieces (5 cm x 5 cm) were subjected to a metal halide lamp weathering test (equipment standard: JTMG01:2000, Japan Testing Machinery Manufacturers Association) (irradiance 90 mW / cm 2 More than 100mW / cm 2 Below, irradiation time is 100 hours).

[0128] (Anti-stain evaluation) The white sheets obtained in Example 1 and Comparative Examples 1 to 5 were subjected to an antifouling evaluation. Specifically, the antifouling properties of the surface of the coating layer side of the white sheets were evaluated by the Boken Quality Evaluation Organization, a general incorporated foundation, based on JIS L 1919 (A-1 method).

[0129] (Antibacterial evaluation) The white sheets obtained in Example 1 and Comparative Examples 1 to 5 were subjected to an antibacterial evaluation. Specifically, based on JIS Z 2801:2010, the white sheet obtained in Comparative Example 1 was treated as an untreated product, and the antibacterial activity value R against Escherichia coli on the surface of the coating layer side of the white sheet was obtained. First, Escherichia coli NBRC3972 was suspended in 1 / 100 NB medium and 10 5 A bacterial solution of CFU / ml was prepared. Then, a PE film was prepared as a control test piece, and white sheet test pieces obtained in Example 1 and Comparative Examples 1 to 5 were prepared as comparative test pieces. Each test piece was placed on a petri dish, inoculated with 0.4 ml of the bacterial solution, and covered with a PE covering film from above. After culturing at 37°C for 24 hours, the bacteria on the test piece were washed and collected with SCDLP medium, the viable bacteria count was measured, and the antibacterial activity value R was calculated. The antibacterial activity value R is the logarithmic value obtained by dividing the viable bacteria count of the control test piece after 24 hours by the viable bacteria count of the target test piece. When the antibacterial activity value R is 2 or more, it is determined to have antibacterial properties.

[0130] (Mold resistance evaluation) The white sheets obtained in Example 1 and Comparative Examples 1 to 5 were subjected to an antifungal evaluation. Specifically, the antifungal properties of the surface of the coating layer side of the white sheets were evaluated based on JIS Z 2911:2010 (Appendix A, Method B). Specifically, the following mold spores were suspended in a glucose-added inorganic salt solution containing 0.005% by mass of the surfactant Aerosol OT, and 10 6 After adjusting the concentration to spores / ml, equal amounts of these were mixed to obtain a mixed spore suspension. Aspergillus niger NBRC 105649 Penicillium citrinum NBRC 6352 Cladosporium cladosporioides NBRC 6348 Rhizopus oryzae NBRC 311005 Chaetomium globosum NBRC 6348

[0131] Next, the test specimens were placed on a glucose-added inorganic salt agar medium and inoculated with the mixed spore suspension by spraying. After that, they were cultured under an atmosphere of 28°C and 80% RH, and the growth of the mold was observed after one month. The evaluation criteria for antifungal properties are shown in Table 1.

[0132] [Table 1]

[0133] Table 2 shows the results of the ISO whiteness, antifouling properties, antibacterial properties, and antifungal properties for the white sheets obtained in Example 1 and Comparative Examples 1 to 5.

[0134] [Table 2]

[0135] As shown in Table 2, it was confirmed that Example 1 had good antifouling properties, antibacterial properties, and antifungal properties. Example 1 also had good ISO whiteness after the weather resistance test. On the other hand, Comparative Example 1 had good antifouling properties, but both antibacterial properties and antifungal properties were low. From this, it was confirmed that by providing a coating layer, it was possible to improve antifouling properties and antifungal properties while maintaining antifouling properties.

[0136] In addition, Comparative Examples 2 to 4 had poorer antifouling properties than Example 1. The reason for this is thought to be that the metal compounds contained in the coating layer may have deteriorated the surface condition of the white sheet. In addition, Comparative Examples 2 to 4 had better antibacterial properties than Example 1, but were significantly inferior in antifungal properties. In contrast, Example 1 was able to exhibit good antibacterial properties and antifungal properties in a well-balanced manner. In addition, Comparative Example 5 had lower ISO whiteness and antifouling properties than Example 1. [Explanation of symbols]

[0137] 1...Base sheet 2…Coat layer 3…Reinforcing sheet 4...adhesive layer 10…White sheet

Claims

1. A base sheet containing a polyolefin resin; A white sheet having a coating layer located on one side of the base sheet, The coating layer contains an organic nitrogen-sulfur compound which is at least one of a fungicide and an antibacterial agent, the white sheet has a reinforcing sheet on the side of the base sheet opposite to the coating layer, and does not have an aluminum plate; On the surface of the white sheet on the coating layer side, The ISO whiteness based on JIS P 8148 is 80% or more, The stain resistance based on JIS L 1919 (A-1 method) is grade 3 or higher. Based on JIS Z 2911:2010 (Annex A, Method B), the mold growth level after 30 days is 1 or less. The white sheet has a thickness of 25 μm or more and 200 μm or less.

2. On the surface of the white sheet on the coating layer side, 2. The white sheet according to claim 1, having an antibacterial activity value R against Escherichia coli based on JIS Z 2801:2010 of 5 or more.

3. A base sheet containing a polyolefin resin; A white sheet having a coating layer located on one side of the base sheet, The coating layer contains an organic nitrogen-sulfur compound which is at least one of a fungicide and an antibacterial agent, the white sheet has a reinforcing sheet on the side of the base sheet opposite to the coating layer, and does not have an aluminum plate; On the surface of the white sheet on the coating layer side, The ISO whiteness based on JIS P 8148 is 80% or more, The stain resistance based on JIS L 1919 (A-1 method) is grade 3 or higher. The antibacterial activity value R against Escherichia coli based on JIS Z 2801:2010 is 5 or more, The white sheet has a thickness of 25 μm or more and 200 μm or less.

4. 4. The white sheet according to claim 1, wherein the coating layer has a pencil hardness of 2H or less according to a pencil hardness test based on JIS K 5600.

5. The white sheet according to claim 1 , wherein the base sheet contains a polyethylene resin as the polyolefin resin.

6. The base sheet further contains an inorganic filler, The white sheet according to claim 1 , wherein the content of the inorganic filler in the base sheet is 30% by mass or more relative to the polyolefin resin.

7. The white sheet according to any one of claims 1 to 6, wherein the substrate sheet has a thickness of 90 µm or less.

8. The white sheet was exposed to a radiant intensity of 90 mW / cm ２ 100mW / cm or more ２ 8. The white sheet according to claim 1, wherein the white sheet has an ISO whiteness of 80% or more based on JIS P 8148 when subjected to a metal halide lamp weather resistance test under the condition of an irradiation time of 100 hours.

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