Sheet and method for manufacturing the sheet

Abstract

To provide a sheet that has excellent basic performance and achieves improvements in the abrasion resistance of the front face and the non-slipperiness of the back face.SOLUTION: A sheet 10 comprises: a first film layer 11 including a first polyurethane film; a foamed layer 12 including polyurethane foam; and a second film layer 13 including a second polyurethane film, in the stated order. The average cell diameter of the polyurethane foam is 50-300 μm inclusive.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a sheet and a method for making the sheet. [Background technology]

[0002] Patent Document 1 discloses a urethane foam molded product that can be used as a floor mat or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-255995 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional polyurethane foam sheets are desired to be improved in terms of abrasion resistance on the surface and anti-slip properties on the back surface. In addition, it is also desired to improve basic performance such as shock absorption and fire resistance depending on the purpose and location of installation. The present disclosure aims to provide a sheet having excellent basic performance and improved surface abrasion resistance and back surface anti-slip properties, and a method for manufacturing a sheet having excellent basic performance and improved surface abrasion resistance and back surface anti-slip properties. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0005] a first film layer composed of a first polyurethane film; A foam layer made of polyurethane foam; a second film layer composed of a second polyurethane film, in this order; The polyurethane foam has an average cell diameter of 50 μm or more and 300 μm or less.

[0006] A method for producing the above sheet, comprising the steps of: A sheet manufacturing method comprising: supplying a polyurethane foam raw material between the first polyurethane film and the second polyurethane film traveling in one direction; and reacting and curing the polyurethane foam raw material to form the polyurethane foam.

[0007] a first film layer composed of a first polyurethane film; A foam layer made of a polyurethane foam containing a flame retardant; a second film layer composed of a second polyurethane film, in that order. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a sheet having excellent basic performance and improved abrasion resistance on the surface and anti-slip properties on the back surface, and a method for manufacturing a sheet having excellent basic performance and improved abrasion resistance on the surface and anti-slip properties on the back surface. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of a sheet according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a preferred embodiment of the sheet. [Diagram 3] 1A to 1C are diagrams for explaining a manufacturing method of a sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Here, a preferred example of the present disclosure is given.

[0011] The polyurethane foam sheet contains a flame retardant.

[0012] The second film layer is a sheet having an installation surface on the side opposite to the foam layer, the installation surface being in contact with an object to be installed, and the installation surface having an uneven shape.

[0013] The sheet has a static friction coefficient of the surface on the second film layer side, measured in accordance with JIS K7125, of 0.3 to 10.0 in an atmosphere having a temperature of 23° C. and a relative humidity of 50%.

[0014] A method for manufacturing a sheet, comprising heating the supplied polyurethane foam raw material with the second polyurethane film positioned above it, and reacting and hardening the polyurethane foam to form the polyurethane foam.

[0015] The present disclosure will be described in detail below. In this specification, a description using "~" for a numerical range includes the lower limit and the upper limit unless otherwise specified. For example, the description "10 to 20" includes both the lower limit "10" and the upper limit "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less".

[0016] Hereinafter, specific embodiments of the present disclosure will be described in detail. The sheet 10 of this embodiment comprises, in this order, a first film layer 11 made of a first polyurethane film, a foam layer 12 made of polyurethane foam, and a second film layer 13 made of a second polyurethane film.

[0017] 1. Foam layer 12 The foam layer 12 is made of polyurethane foam. Polyurethane foam can be obtained by reacting a mixed raw material containing polyols and polyisocyanates and foaming it by a mechanical froth method. The mechanical froth method is a method in which bubbles are formed by mixing compressed gas such as an inert gas when stirring and mixing the mixed raw material without adding a specific foaming agent to the mixed raw material.

[0018] As the polyols, it is preferable to use a combination of at least three kinds of polyols, namely, (A) a first polyol made of a polymer polyol, (B) a second polyol made of a polyether polyol, and (C) a third polyol made of a polyester polyol. By using a combination of polyols in this way, the low compression set and impact absorption resistance of the sheet 10 can be improved.

[0019] The first polyol is, for example, a polymer polyol having a number average molecular weight of 1500 to 4500 (preferably 2000 to 4000) and a functionality of 3 or 2. The first polyol, when used in combination with the second polyol and the third polyol, imparts strength such as tensile strength, and hardness and flexibility according to the application to the polyurethane foam. As the first polyol, for example, a polymer polyol obtained by graft copolymerizing vinyl monomers such as acrylonitrile and styrene in a polyether polyol having a functionality of 3 as a base polyol can be suitably used. As the base polyol, for example, a polyether polyol made of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a trihydric polyalcohol such as glycerin can be mentioned. In the case of a polymer polyol having a functionality of 2, for example, a polyether polyol made of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a dihydric polyalcohol such as glycol can be used as the base polyol. The number average molecular weight of the first polyol means the number average molecular weight of the base polyol.

[0020] The polymer content of the first polyol (the mass ratio of the portion other than the base polyol to the entire polymer polyol) is preferably 15% by mass to 45% by mass, more preferably 20% by mass to 40% by mass. From the viewpoint of improving the strength of the polyurethane foam, it is preferable that the polymer content of the first polyol is large, but if the polymer content exceeds 45% by mass, the viscosity may become too high and the workability may decrease. The first polyol may contain only one type of polymer polyol, or may contain a combination of two or more types of polymer polyols having different number average molecular weights, polymer contents, etc.

[0021] The content of the first polyol in the mixed raw material is preferably 80 parts by mass to 95 parts by mass, more preferably 85 parts by mass to 90 parts by mass, when the total amount of polyols is 100 parts by mass. If this content is equal to or higher than the lower limit, strength such as tensile strength, hardness, and flexibility can be improved. If this content is equal to or lower than the upper limit, strength such as tensile strength and tear strength can be ensured.

[0022] The second polyol is, for example, a polyether polyol having a number average molecular weight of 300 to 900 (preferably 450 to 750) and a functionality of 3. The second polyol, when used in combination with the first polyol, imparts strength such as tensile strength and low compression set to the polyurethane foam, and when used in combination with the third polyol, further improves strength such as tensile strength and low compression set of the polyurethane foam.

[0023] As the second polyol, for example, a polyether polyol consisting of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a trihydric polyalcohol such as glycerin can be suitably used. The second polyol may have a functional group other than a hydroxyl group such as an amino group. As the second polyol, only one type of polyether polyol may be contained, or two or more types of polyether polyols having different number average molecular weights, functional groups, etc. may be contained in combination.

[0024] The content of the second polyol in the mixed raw material is preferably 5 to 15 parts by mass when the total amount of polyols is 100 parts by mass. If this content is equal to or higher than the lower limit, low compression set can be obtained. If the content exceeds the upper limit, low resilience is expressed. From the viewpoint of obtaining a polyurethane foam with high resilience, it is preferable to set the content to the upper limit or lower. If the content of the second polyol is set to 5 to 15 parts by mass, high resilience can be imparted to the polyurethane foam. The content of the second polyol and the content of the third polyol are appropriately adjusted in consideration of the balance between hydrolysis property and hardness. The content of the second polyol is not particularly limited, but may be higher than the content of the third polyol.

[0025] The third polyol is, for example, a polyester polyol having a functionality of 2 or 3. The third polyol, when used in combination with the first polyol, imparts heat resistance and chemical resistance to the polyurethane foam, and when used in combination with the second polyol, improves the tensile strength and low compression set of the polyurethane foam. The third polyol also has the effect of making the cells of the polyurethane foam finer and more uniform.

[0026] The molecular weight (number average molecular weight) of the third polyol is preferably in the range of 400 to 2500, more preferably in the range of 450 to 1500. As the third polyol, for example, polycaprolactone-based polyester polyol, adipate-based polyester polyol, polycarbonate-based polyol, etc. can be used. As the polycaprolactone-based polyester polyol, for example, polyester polyol obtained by ring-opening addition polymerization of lactones such as ε-caprolactone can be mentioned. As the adipate-based polyester polyol, for example, polyester polyol obtained by polycondensation of polyfunctional carboxylic acid and polyfunctional hydroxy compound can be mentioned. Among these polyester polyols, it is preferable to use polycaprolactone-based polyester polyol having three functional groups from the viewpoint of making hydrolysis difficult to occur and reducing the content of volatile organic compounds.

[0027] The content of the third polyol in the mixed raw material is preferably 1 to 6 parts by mass, more preferably 2 to 5 parts by mass, when the total amount of polyols is 100 parts by mass. When the content is less than 1 part by mass, low resilience is exhibited. From the viewpoint of obtaining a polyurethane foam with high resilience, it is preferable to set the content to the lower limit or more. Also, when the content is 6 parts by mass or less, an increase in compression set can be suppressed, and low compression set can be ensured.

[0028] The polyols may contain other polyols than the first to third polyols. The other polyols may be any polyol that is generally used in polyurethane foams, without any particular limitations. The polyols may contain an antioxidant to suppress oxidation of the components, but from the viewpoint of reducing the content of volatile organic compounds, it is preferable to use BHT-free polyols that do not use dibutylhydroxytoluene (BHT) as an antioxidant. Examples of BHT-free polyols include polyols that use a hindered phenol-based antioxidant with a molecular weight of 300 or more.

[0029] Polyisocyanates are compounds having a plurality of isocyanate groups. Examples of polyisocyanates include aromatic polyisocyanates such as 4,4-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, and xylylene diisocyanate (XDI), alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), and dicyclohexylmethane diisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), and free isocyanate prepolymers obtained by reacting these with polyols, and modified polyisocyanates such as carbodiimide-modified polyisocyanates. These polyisocyanates may be contained in only one type, or in a combination of two or more types.

[0030] From the viewpoint of reducing the halogen content (especially the chlorine content), it is preferable to use a monomeric isocyanate (e.g., monomeric MDI), a carbodiimide-modified isocyanate, or a prepolymer having an isocyanate group terminal obtained from these as starting materials. The number of functional groups of the polyisocyanates is preferably in the range of 2.0 to 2.2.

[0031] The isocyanate index of the polyisocyanates is preferably in the range of 0.9 to 1.1. The isocyanate index is the equivalent ratio of the isocyanate groups of the polyisocyanates to the reactive groups such as hydroxyl groups in the polyols that can react with isocyanate. Therefore, when the value is less than 1, it means that the reactive groups such as hydroxyl groups are in excess of the isocyanate groups, and when it exceeds 1, it means that the isocyanate groups are in excess of the reactive groups such as hydroxyl groups. If the isocyanate index is 0.9 or more, the polyols can react sufficiently with the polyisocyanates. If the isocyanate index is 1.1 or less, it is preferable from the viewpoint of improving low compression set and high resilience.

[0032] The mixed raw material preferably contains a flame retardant. Examples of the flame retardant include expanded graphite, phosphorus-based flame retardants, melamine-based flame retardants, and halogen-based flame retardants. The flame retardant is preferably a non-halogen flame retardant in that it does not use environmentally hazardous substances, and more preferably one or more selected from the group consisting of expanded graphite and phosphorus-based flame retardants. The flame retardant may be used alone or in combination of two or more.

[0033] From the viewpoint of suppressing bleeding and blooming, it is preferable to use expanded graphite as the flame retardant. Expanded graphite is a material in which a chemical substance is inserted (intercalated) between layers of scaly graphite. Examples of the chemical substance to be inserted include nitric acid, potassium permanganate, and sulfuric acid. Among these, sulfuric acid, which has a high expansion start temperature, is preferable. From the viewpoint of suppressing expansion during the production of the sheet 10, it is preferable that the expansion start temperature of the expanded graphite is 170°C or higher. The expansion start temperature of the expanded graphite is usually 200°C or lower.

[0034] The content of the expanded graphite is preferably 10 parts by mass or more and 50 parts by mass or less, more preferably 20 parts by mass or more and 45 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the polyols. If the content of the expanded graphite is equal to or more than the lower limit, the flame retardancy can be improved. If the content of the expanded graphite is equal to or less than the upper limit, it is preferable from the viewpoint of the foamability of the polyurethane foam.

[0035] From the viewpoint of improving the flame retardancy while maintaining the physical properties of the polyurethane foam, it is preferable to use a phosphorus-based flame retardant in combination with expanded graphite. Examples of phosphorus-based flame retardants include compounds such as ammonium polyphosphate, phosphate ester, melamine phosphate, melamine polyphosphate, guanidine phosphate and ethylenediamine phosphate, triphenyl phosphate, tricresyl phosphate, bis(1,3-phenylenediphenyl)phosphate, compounds such as triaryl phosphate, trialkyl phosphate, alkylaryl phosphate, red phosphorus, etc. From the viewpoint of suppressing bleeding and blooming, the phosphorus-based flame retardant used in combination with expanded graphite is preferably a solid (powder) phosphorus-based flame retardant, and more preferably a powdered ammonium polyphosphate.

[0036] The content of the phosphorus-based flame retardant is preferably 10 parts by mass or more and 50 parts by mass or less, more preferably 20 parts by mass or more and 45 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the polyols. If the content of the phosphorus-based flame retardant is equal to or more than the lower limit, the flame retardancy can be improved. If the content of the phosphorus-based flame retardant is equal to or less than the upper limit, it is preferable from the viewpoint of the foamability of the polyurethane foam. The mass ratio of the expandable graphite to the phosphorus-based flame retardant (expandable graphite:phosphorus-based flame retardant) is preferably 5:1 to 1:5, and more preferably 2:1 to 1:2.

[0037] The mixed raw material preferably contains a foam stabilizer. The foam stabilizer is used to smoothly foam the mixed raw material. As the foam stabilizer, a known foam stabilizer that is usually used when the mechanical froth method is adopted, for example, a silicone-based foam stabilizer, can be used. Since such a foam stabilizer has a high viscosity, it is usually diluted with a solvent such as alkylbenzene and then mixed into the mixed raw material. As the solvent, a low-viscosity polyol having a viscosity of 500 cps or less (preferably a viscosity of 40 cps to 500 cps) may be used. Examples of low-viscosity polyols include polyether polyols having a molecular weight (number average molecular weight) of 1700 or less and polyols that are liquid at room temperature.

[0038] The content of the foam stabilizer in the mixed raw material is preferably 3 to 15 parts by mass relative to 100 parts by mass of polyols. If the content is 3 parts by mass or more, the foam stabilizing power is sufficient, and a uniform cell structure can be formed and the density can be reduced. Even if the content exceeds 15 parts by mass, no significant improvement in the foam stabilizing power can be expected. When the foam stabilizer is diluted with a solvent, the mass ratio (foam stabilizer:solvent) is preferably in the range of 15:85 to 85:15.

[0039] The catalyst is mainly for promoting the urethane reaction between polyols and polyisocyanates, and the mixed raw material preferably contains a catalyst. As the catalyst, known catalysts usually used in polyurethane foams, such as organometallic compounds such as ferric acetylacetonate, stannous octoate, and tin octoate (tin octoate), metal complex catalysts such as zinc amine catalysts, tertiary amines such as triethylenediamine, dimethylethanolamine, and N,N',N'-trimethylaminoethylpiperazine, acetates, and alkali metal alcoholates can be used. The catalysts may be used alone or in combination of two or more. Among these, it is particularly preferable to contain at least ferric acetylacetonate because of its stability, good catalytic activity and non-toxicity. The effects of this are disclosed, for example, in the specification of U.S. Patent No. 5,733,945.

[0040] The catalyst content in the mixed raw material is preferably 0.1 to 12.0 parts by mass relative to 100 parts by mass of polyols. If this content is 0.1 parts by mass or more, the urethane reaction can be sufficiently promoted. If the content is 12.0 parts by mass or less, the urethane reaction can be prevented from being excessively promoted, the formation of a cell structure can be made uniform, and the physical properties can be stabilized.

[0041] The crosslinking agent is used to form crosslinks between polyols to improve strength, etc., and the mixed raw material preferably contains a crosslinking agent. Examples of the crosslinking agent include known crosslinking agents commonly used in polyurethane foams, such as polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol, amines such as ethylenediamine, diethylenetriamine, hexamethylenediamine, hydrazine, diethyltoluenediamine, and diethylenetriamine, aminoalcohols such as diethanolamine and triethanolamine, and compounds obtained by adding ethylene oxide, polypropylene oxide, etc. to these active hydrogen compounds. The crosslinking agent may be used alone or in combination of two or more types.

[0042] The content of the crosslinking agent in the mixed raw material is preferably 2.0 parts by mass to 15.0 parts by mass relative to 100 parts by mass of polyols. If the content is 2.0 parts by mass or more, strength such as tensile strength can be ensured. Also, if the content is 15.0 parts by mass or less, appropriate hardness can be obtained and high resilience can be imparted.

[0043] The mixed raw material may contain other components other than those described above as necessary. Examples of the other components include antioxidants, ultraviolet absorbers, thickeners, plasticizers, antibacterial agents, and colorants. Examples of the antioxidant include dibutylhydroxytoluene and hindered phenol-based antioxidants, and from the viewpoint of reducing the content of volatile organic compounds, it is particularly preferable to use hindered phenol-based antioxidants having a molecular weight of 300 or more. Examples of the thickener include calcium carbonate, aluminum hydroxide, and magnesium hydroxide. These thickeners are also known to impart flame retardancy to polyurethane foam, and are also preferable from the viewpoint of improving the flame retardancy of the sheet 10.

[0044] From the viewpoint of impact resistance and absorption, the polyurethane foam preferably has either an open cell structure or a semi-open cell structure, and more preferably has an open cell structure. The open cell structure and the semi-open cell structure are structures in which the cells have pores, unlike the closed cell structure. The cell structure of the polyurethane foam can be evaluated by measuring the air permeability of the polyurethane foam. The air permeability of the polyurethane foam can be determined, for example, as the air permeability (Gurley air permeability) determined in accordance with the air permeability measurement method B (Gurley type method) defined in JIS L1096:2010. The Gurley air permeability of the polyurethane foam is, for example, 0.5 seconds / 100 mL or more and 50 seconds / 100 mL or less.

[0045] From the viewpoint of maintaining uniformity of the product, the average cell diameter of the polyurethane foam is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less. The average cell diameter of the polyurethane foam is preferably 50 μm or more. From these viewpoints, the average cell diameter of the polyurethane foam is preferably 50 μm or more and 300 μm or less, more preferably 50 μm or more and 250 μm or less, and even more preferably 50 μm or more and 200 μm or less. The average cell diameter of a polyurethane foam can be calculated by dividing the cumulative cell diameters of cells contacting a 25 mm straight line when the cross section of the polyurethane foam is observed under a scanning electron microscope at a magnification of 200 times by the number of cells. Moreover, from the viewpoint of maintaining the elasticity of the polyurethane foam, the thickness of the cell membrane constituting the cells is preferably 10 μm or less, and more preferably 5 μm or less.

[0046] From the viewpoint of maintaining uniformity of the product, the cell size distribution is preferably within ±50 μm of the average cell size for 70% or more of the cells, more preferably within ±30 μm, and particularly preferably within ±20 μm. The cell size distribution can be calculated based on the cell size when the above-mentioned average cell size is measured.

[0047] From the viewpoint of impact absorption, the shape of the cells is preferably approximately spherical. The shape of the cells can be confirmed by observing a cross section of the polyurethane foam under a microscope. For example, the cells preferably have an average circularity (hereinafter also referred to as average circularity) of 0.6 or more, calculated by the following formula (1): Circularity = 4π (cross-sectional area of ​​cell (mm 2 )) / (perimeter of cell cross section (mm)) 2 (1) The circularity indicates how close the cell cross section is to a perfect circle, with the circularity being closer to 1. The average circularity can be measured, for example, by using image analysis software to measure the bubble perimeter and bubble area of ​​all bubbles within an area of ​​1 mm x 1 mm, calculating the circularity of each, and averaging the results.

[0048] The cell structure, average cell size, cell size distribution, and cell shape of the polyurethane foam can be controlled by adjusting the production conditions in the mechanical froth method, the composition of the mixed raw materials, and the viscosity of the mixed raw materials.

[0049] The thickness of the polyurethane foam is not particularly limited. From the viewpoint of impact resistance and absorption, the thickness of the polyurethane foam is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more. From the viewpoint of reducing the step with the laying surface, the thickness of the polyurethane foam is preferably 20.0 mm or less, more preferably 10.0 mm or less, and even more preferably 5.0 mm or less. From these viewpoints, the thickness of the polyurethane foam is preferably 0.5 mm or more and 20.0 mm or less, more preferably 1.0 mm or more and 10.0 mm or less, and even more preferably 2.0 mm or more and 5.0 mm or less.

[0050] The specific gravity of the polyurethane foam is not particularly limited. From the viewpoint of hardness, the specific gravity of the polyurethane foam is 0.05 g / cm 3 More than 0.08 g / cm is preferable. 3 More preferably, 0.15 g / cm 3More preferably, the specific gravity of the polyurethane foam is 0.70 g / cm from the viewpoint of shock absorption. 3 Less than 0.60 g / cm is preferred. 3 Less than 0.50 g / cm is more preferable. 3 From these viewpoints, the specific gravity of the polyurethane foam is preferably 0.05 g / cm or less. 3 More than 0.70g / cm 3 Less than 0.08 g / cm is preferred. 3 More than 0.60g / cm 3 Less than 0.15 g / cm is more preferable. 3 More than 0.50g / cm 3 The following is even more preferred:

[0051] 2. First film layer 11 The first film layer 11 is composed of a first polyurethane film. In this embodiment, the first film layer 11 is exemplified as a surface layer that appears on the surface 10A of the sheet 10. The first polyurethane film can be obtained by reacting a mixed raw material containing polyols and polyisocyanates.

[0052] As the polyol, polyester polyol, polyether polyol, polycarbonate polyol, polymer polyol, and mixtures thereof can be used. Among these, polyester polyol is preferred from the viewpoint of abrasion resistance.

[0053] The polyester polyol can be obtained, for example, by reacting a dicarboxylic acid with a glycol according to a conventional method. Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, oxycarboxylic acids such as oxybenzoic acid, and ester-forming derivatives thereof. Examples of the glycol component include aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol, and triethylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, aromatic diols such as p-xylenediol, and polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These polyester polyols have a linear structure, but they can also be made into branched polyesters by using ester-forming components with a valence of 3 or more.

[0054] The content of polyester polyol in the mixed raw material is preferably 50 parts by mass to 100 parts by mass, more preferably 70 parts by mass to 98 parts by mass, and even more preferably 85 parts by mass to 95 parts by mass, when the total amount of polyols is 100 parts by mass. If the content of polyester polyol is equal to or more than the lower limit, the abrasion resistance is good. If the content of polyester polyol is equal to or less than the upper limit, it is preferable from the viewpoint of physical strength.

[0055] Polyisocyanates are compounds having a plurality of isocyanate groups. Examples of polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0056] The first polyurethane film may further contain additives such as flame retardants, adhesion promoters, colorants, plasticizers, and combinations thereof. The additives are selected so as not to significantly adversely affect the desired properties of the first polyurethane film. In a configuration in which the polyurethane foam contains expanded graphite as a flame retardant, it is preferable to use a first polyurethane film containing a colorant. If the first polyurethane film were colorless and transparent, the expanded graphite in the polyurethane foam would be visible through the first film layer, restricting the color of the sheet 10. By using a first polyurethane film containing a colorant, the degree of freedom in the color of the sheet 10 can be increased.

[0057] The thickness of the first polyurethane film is not particularly limited. From the viewpoint of abrasion resistance and moldability, the thickness of the first polyurethane film is preferably 0.001 mm or more, more preferably 0.005 mm or more, and even more preferably 0.010 mm or more. From the viewpoint of stretchability and cost, the thickness of the first polyurethane film is preferably 0.200 mm or less, more preferably 0.100 mm or less, and even more preferably 0.050 mm or less. From these viewpoints, the thickness of the first polyurethane film is preferably 0.001 mm or more and 0.200 mm or less, more preferably 0.005 mm or more and 0.100 mm or less, and even more preferably 0.010 mm or more and 0.050 mm or less.

[0058] The specific gravity of the first polyurethane film is not particularly limited. From the viewpoint of breathability, the specific gravity of the first polyurethane film is 0.8 g / cm. 3 More than 0.9 g / cm is preferable. 3 More preferably, 0.95 g / cm 3 From the viewpoint of flexibility, the specific gravity of the first polyurethane film is preferably 2.0 g / cm. 3 Less than 1.5 g / cm is preferred. 3 Less than 1.2 g / cm is more preferable. 3 From these viewpoints, the specific gravity of the first polyurethane film is preferably 0.8 g / cm or less. 3 More than 2.0g / cm3 Less than 0.9 g / cm is preferred. 3 More than 1.5g / cm 3 Less than 0.95 g / cm is more preferable. 3 More than 1.2g / cm 3 is more preferred.

[0059] The elongation of the first polyurethane film is not particularly limited. The elongation of the first polyurethane film is preferably 150% or more, more preferably 150% to 500%, and even more preferably 200% to 500%. When this elongation is equal to or more than the lower limit, the film has excellent conformability compared to the case where a general PET film or the like is used. The elongation is a value measured in accordance with JIS K 6251.

[0060] The first polyurethane film is preferably a non-foaming polyurethane film. It is more preferable to use a substantially non-porous film as the first polyurethane film. The first polyurethane film can be produced by a wet method, a dry method, or the like, but the dry method is preferable to obtain a substantially non-porous first polyurethane film. Specifically, the first polyurethane film is coated on a first substrate 21 having releasability such as release paper or release film using a normal coating method, for example, a knife coater, a comma coater, a reverse coater, or the like, to form a film. The first polyurethane film can be evaluated as being substantially non-porous by measuring the air permeability of the first polyurethane film. For example, the first polyurethane film may have a Gurley air permeability of more than 10,000 seconds / 100 mL.

[0061] As shown in Fig. 2, the first film layer 11 preferably has an uneven shape 11A on the surface 10A. The uneven shape 11A forms, for example, a grained pattern or a geometric pattern. The uneven shape 11A can be formed integrally with the first polyurethane film. For example, the uneven shape 11A can be formed by transferring a shape imparted to the first substrate 21, which will be described in the manufacturing method of the sheet 10 later.

[0062] 3. Second film layer 13 The second film layer 13 is composed of a second polyurethane film. In this embodiment, the second film layer 13 is exemplified as a back surface layer appearing on the back surface 10B of the sheet 10. That is, the second film layer 13 in this embodiment has a surface opposite to the foam layer 12 side that is an installation surface that contacts an object to be installed. The second polyurethane film can be obtained by reacting a mixed raw material containing polyols and polyisocyanates.

[0063] As the polyols, polyester polyols, polyether polyols, polycarbonate polyols, polymer polyols, and mixtures thereof can be used. Among these, in order to increase the coefficient of friction, it is preferable to use polyether polyols and polyester polyols in combination from the viewpoint of improving strength while maintaining flexibility.

[0064] As the polyether polyol, for example, a polyether polyol consisting of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a polyhydric alcohol such as glycerin or glycol can be suitably used. As the polyether polyol, only one type of polyether polyol may be contained, or two or more types of polyether polyols having different number average molecular weights, functional groups, etc. may be contained in combination.

[0065] The polyester polyol can be obtained, for example, by reacting a dicarboxylic acid with a glycol according to a conventional method. Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, oxycarboxylic acids such as oxybenzoic acid, and ester-forming derivatives thereof. Examples of the glycol component include aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol, and triethylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, aromatic diols such as p-xylenediol, and polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These polyester polyols have a linear structure, but they can also be made into branched polyesters by using ester-forming components with a valence of 3 or more.

[0066] The contents of polyether polyol and polyester polyol in the mixed raw material are appropriately adjusted according to the physical properties required for the second film layer 13 . The mass ratio of polyether polyol to polyester polyol (polyether polyol: polyester polyol) is preferably 5:95 to 50:50, more preferably 8:92 to 40:60, and further preferably 10:90 to 30:70. The total content of the polyether polyol and the polyester polyol is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, based on 100 parts by mass of the entire polyols.

[0067] Polyisocyanates are compounds having a plurality of isocyanate groups. Examples of polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0068] The second polyurethane film may further contain additives such as flame retardants, adhesion promoters, colorants, plasticizers, and combinations thereof. The additives are selected so as not to significantly adversely affect the desired properties of the second polyurethane film.

[0069] The thickness of the second polyurethane film is not particularly limited. From the viewpoint of durability and moldability, the thickness of the second polyurethane film is preferably 0.001 mm or more, more preferably 0.005 mm or more, and even more preferably 0.010 mm or more. From the viewpoint of stretchability and cost, the thickness of the second polyurethane film is preferably 0.200 mm or less, more preferably 0.100 mm or less, and even more preferably 0.050 mm or less. From these viewpoints, the thickness of the second polyurethane film is preferably 0.001 mm or more and 0.200 mm or less, more preferably 0.005 mm or more and 0.100 mm or less, and even more preferably 0.010 mm or more and 0.050 mm or less.

[0070] The specific gravity of the second polyurethane film is not particularly limited. From the viewpoint of enhancing durability, the specific gravity of the second polyurethane film is preferably 0.8 g / cm. 3 More than 0.9 g / cm is preferable. 3 More preferably, 0.95 g / cm 3 The specific gravity of the second polyurethane film is preferably 2.0 g / cm from the viewpoint of ease of handling of the product due to its light weight. 3 Less than 1.5 g / cm is preferred. 3Less than 1.2 g / cm is more preferable. 3 From these viewpoints, the specific gravity of the second polyurethane film is preferably 0.8 g / cm or less. 3 More than 2.0g / cm 3 Less than 0.9 g / cm is preferred. 3 More than 1.5g / cm 3 Less than 0.95 g / cm is more preferable. 3 More than 1.2g / cm 3 is more preferred.

[0071] As shown in FIG. 2, the second film layer 13 preferably has an uneven shape 13A on the installation surface. The uneven shape 13A is configured with a plurality of anti-slip protrusions, for example, columnar, hemispherical (dome) shaped, etc. The uneven shape 13A can be formed integrally with the second polyurethane film by embossing. Such a configuration having the uneven shape 13A is preferable because it can improve the anti-slip properties of the sheet 10 without performing a separate anti-slip treatment after forming the sheet. For example, the uneven shape 13A can be formed by transferring a shape given to the second substrate 23, which will be described in the manufacturing method of the sheet 10 described later.

[0072] 4. Sheet configuration The sheet 10 is a laminate in which, for example, a first film layer 11 of ester-based polyurethane, a foamed layer 12 of ether-based polyurethane, and a second film layer 13 of ether / ester-based polyurethane are laminated in this order. The foamed layer 12 and the first film layer 11 are preferably in direct contact and bonded together. Also, the foamed layer 12 and the second film layer 13 are preferably in direct contact and bonded together.

[0073] The sheet 10 is suitable as a carpet (carpet, flooring material). When used as a carpet, the sheet 10 is placed on a surface such as a room, a hallway, or a vehicle floor with the surface 10A facing up. The first film layer 11 is exposed on the side opposite to the foamed layer 12 and comes into contact with people walking on the surface 10A side or objects placed on the surface 10A side. That is, the first film layer 11 is interposed between the foamed layer 12 and people walking on the surface 10A side or objects placed on the surface 10A side. Therefore, even if an additive such as expanded graphite that may fall off or transfer color is added to the foamed layer 12, the additive can be prevented from coming into contact with people or objects. The second film layer 13 is exposed on the side opposite to the foam layer 12 and contacts the object to be installed, such as a floor. That is, the second film layer 13 is interposed between the object to be installed, such as a floor material, and the foam layer 12. Therefore, even if an additive such as expanded graphite that may fall off or transfer color is added to the foam layer 12, the additive can be prevented from adhering to the object to be installed. The configuration of the sheet is not limited to this. For example, unlike the present embodiment, the sheet may further include an optional layer on the upper side of the first film layer or between the first film layer and the foam layer. The sheet may further include an optional layer on the lower side of the second film layer or between the foam layer and the second film layer.

[0074] The Taber abrasion of the surface 10A of the sheet 10 facing the first film layer 11 is preferably 250 mg or less, more preferably 200 mg or less, and even more preferably 150 mg or less. A low Taber abrasion is an indicator of high abrasion resistance. The Taber abrasion of the foam layer 12 alone is greater than the Taber abrasion of the surface facing the first film layer 11, and is, for example, 250 mg or more and 300 mg or less. The Taber abrasion amount is measured in accordance with JIS K7204 under the conditions of an abrasive wheel H-22, a rotation speed of 60 rpm, a load of 250 g, and 1000 revolutions.

[0075] The static friction coefficient of the surface 10B of the sheet 10 facing the second film layer 13 is preferably 0.3 to 10.0, more preferably 0.5 to 7.0, and even more preferably 1.0 to 4.0. A high static friction coefficient is an indicator of high gripping ability. The static friction coefficient is measured in accordance with JIS K7125 at a temperature of 23° C. and a relative humidity of 50%.

[0076] When the surface of the second film layer 13 opposite to the foam layer 12 side is an installation surface that comes into contact with an object to be installed, the second film layer 13 functions as an anti-slip layer for the installation surface. Therefore, the grip of the sheet 10 on the installation surface can be ensured even if no adhesive layer or the like is provided between the sheet 10 and the installation surface.

[0077] There is no particular limitation on the 25% compression load of the sheet 10. The 25% compression load (25% CLD, JIS K 6254:2010) of the sheet 10 is preferably 0.01 to 0.5 MPa.

[0078] There is no particular limitation on the impact absorption properties of the sheet 10. The impact load of the sheet 10 measured by the measuring method described below is preferably 0.35 kN or less.

[0079] 5. Manufacturing method of sheet 10 The method for producing the sheet 10 includes, for example, supplying a polyurethane foam raw material between a first polyurethane film and a second polyurethane film traveling in one direction, and reacting and curing the polyurethane foam raw material to form a polyurethane foam. In order to suppress gas floating of the first polyurethane film appearing on the surface 10A, the method for producing the sheet 10 preferably includes heating the polyurethane foam raw material in a position where the second polyurethane film is located above the supplied polyurethane foam raw material, and reacting and curing the polyurethane foam to form the polyurethane foam. The method for producing the sheet 10 of this embodiment produces a polyurethane foam by a mechanical froth method. The sheet 10 can be produced, for example, using a production apparatus 30 shown in FIG. 3.

[0080] The manufacturing apparatus 30 includes a mixing section (not shown), a roll mechanism 32 including supply rolls 33 and 34 and a product recovery roll 35, a discharge nozzle 36, and a heating section 37. The mixing section is a section for obtaining polyurethane foam raw material M by mixing raw materials. The first supply roll 33 is a section on which a first polyurethane film with a first substrate 21 is wound, and supplies the first polyurethane film by a driving source (not shown). The second supply roll 34 is a section on which a second polyurethane film with a second substrate 23 is wound, and supplies the second polyurethane film by a driving source (not shown). The product recovery roll 35 is a section for winding the sheet 10 into a roll and recovering it. The discharge nozzle 36 is a section for supplying polyurethane foam raw material M between the first polyurethane film and the second polyurethane film. The heating section 37 is composed of a heater or the like for heating the supplied polyurethane foam raw material M. Furthermore, the manufacturing apparatus 30 is provided with a first substrate recovery roll 38 that peels off and recovers the first substrate 21 from the first polyurethane film, and a second substrate recovery roll 39 that peels off and recovers the second substrate 23 from the second polyurethane film.

[0081] The sheet 10 can be manufactured as follows. First, a first polyurethane film with a first substrate 21 is continuously supplied from a first supply roll 33, and a first polyurethane film with a second substrate 23 is continuously supplied from a second supply roll 34. During the process in which the first polyurethane film and the second polyurethane film are continuously supplied, polyurethane foam raw material M is supplied between the first polyurethane film and the second polyurethane film from a discharge nozzle 36. At this time, the thickness of the sheet 10 can be set according to the distance between the first polyurethane film and the second polyurethane film.

[0082] Next, the polyurethane foam raw material M is heated in the heating section 37 to react and harden. At this time, the polyurethane foam raw material M is heated under conditions that the product temperature is the expansion start temperature of the expanded graphite (for example, 170°C or less). Heating by the heating section 37 is performed in a position where the second polyurethane film is located on the upper side. In this way, even if the expanded graphite added to the polyurethane foam raw material expands partially and gas is generated, the gas is less likely to move to the first polyurethane film side, and the occurrence of gas floating on the surface 10A side of the sheet 10 can be suppressed. Thereafter, the first polyurethane film, the polyurethane foam, and the second polyurethane film in a laminated state are fixed, and then the first substrate 21 and the second substrate 23 are peeled off, and the sheet 10 is taken up on the product recovery roll 35.

[0083] The sheet 10 thus obtained can be cut into a predetermined shape and used as a rug (carpet, flooring material). In addition to rugs, the sheet 10 can also be used for coasters, trivets, shoe insoles, car seats, etc.

[0084] 6. Effects of this embodiment Traditionally, fiber materials and resin foams such as polyethylene foam and EVA have been used for personal use and removable rugs (carpets and flooring materials) in the home. Basic functions such as cleanability, easy installation, walkability, and durability are required for rugs. Furthermore, in recent years, especially in homes (facilities) for nursing care and childcare, rugs with few steps (thin thickness) and excellent shock absorption performance are required due to barrier-free access and safety in the event of a fall. Thus, there is an increasing demand for sheets that combine the basic functions of rugs and have high shock absorption. In addition, facilities and buildings where an unspecified number of people enter and exit, such as nursing homes and accommodation facilities, are required to meet the fire retardant performance standards set by the Fire Service Act, but the reality is that there are no rugs that meet all of these standards.

[0085] The sheet 10 of this embodiment comprises, in this order, a first film layer 11, a foam layer 12, and a second film layer 13, thereby ensuring basic performance such as impact absorption and flame retardancy while improving the abrasion resistance of the front surface 10A and the anti-slip properties of the back surface 10B. Since the sheet 10 has high shock absorption properties, it can be made thinner to accommodate wheelchairs and walkers required by people who need care or small children, and the step can be made smaller. Furthermore, it can absorb shock in the event of a fall, ensuring safety. If the foam layer 12 has high resilience, the feet do not sink too much when walking, and walking is easy. Similarly, if the foam layer 12 has high resilience, the wheels of the wheelchair or walker do not sink too much when running, making it easy to run.

[0086] The sheet 10 can ensure durability because the first film layer 11 has high abrasion resistance. For example, when used as a carpet, wear caused by friction associated with wheelchairs, walking, and cleaning can be suppressed, and damage to the sheet 10 can be suppressed. This allows the lifespan of the sheet 10 to be extended. Furthermore, in the sheet 10, solvents and dirt are less likely to penetrate into the first film layer 11, and any deposits on the first film layer 11 can be easily wiped off. This provides good cleaning properties for the sheet 10. Furthermore, the first film layer 11 has high chemical resistance, which contributes to improving the durability of the sheet 10.

[0087] The sheet 10 is easy to install because the second film layer 13 has a high gripping property. Specifically, the sheet 10 is not easily slippery on the surface on which it is placed, even when the second film layer 13 is simply placed in contact with the surface on which it is placed. Therefore, the sheet 10 can be placed directly on the surface on which it is placed, without using a pressure sensitive adhesive or glue as in the past. Furthermore, when no pressure sensitive adhesive or glue is used, there is no need to use a solvent to remove the pressure sensitive adhesive or glue remaining on the surface when the mat is removed. When the polyurethane foam contains a flame retardant, there is a concern that the static friction coefficient of the foam layer 12 alone will decrease. In this embodiment, since the second film layer 13 is provided together with the foam layer 12, the foam layer 12 can ensure functions such as shock absorption and flame retardancy, while the second film layer 13 can ensure gripping force.

[0088] When the polyurethane foam contains a flame retardant, it is possible to improve the flame retardancy of the sheet 10. Specifically, it is possible to impart flame retardancy that meets the criteria of Article 4-3 of the Enforcement Regulations of the Fire Service Act to the sheet 10. In addition, when a halogen-derived material is not used as the flame retardant, it is possible to make it an environmentally friendly formulation. Furthermore, in this embodiment, since the foam layer 12 is covered with the first film layer 11 and the second film layer 13, contact between the flame retardant and people and objects can be prevented, and the flame retardant in the polyurethane foam can be prevented from falling off.

[0089] In the manufacturing method of the sheet 10 of the present embodiment, the first film layer 11, the foam layer 12, and the second film layer 13 are integrally formed, and therefore there is no need to take the time and effort to bond the first film layer 11, the foam layer 12, and the second film layer 13. In addition, since the first film layer 11, the foam layer 12, and the second film layer 13 are all made of polyurethane resin, adhesive strength is ensured and peeling is unlikely to occur.

[0090] The manufacturing method of the sheet 10 of the present embodiment makes it easy to form the sheet 10 into a long, elongated shape that is long in one direction. Such a sheet 10 can be installed on a large surface area by itself, and is easy to use as a carpet. Moreover, the sheet 10 can be easily cut to a predetermined size to adjust the size.

[0091] Furthermore, in the manufacturing method of the sheet 10 of this embodiment, even when the sheet 10 is wound into a roll, the first film layer 11 and the second film layer 13 are interposed between the foamed layer 12 wound earlier and the foamed layer 12 wound later. If the foamed layer 12 wound earlier and the foamed layer 12 wound later come into contact with each other, measures are taken to prevent the foamed layers 12 from blocking each other, such as laminating a release paper or applying an ultraviolet (UV) coating to the foamed layer 12. In the sheet 10 of this embodiment, the first film layer 11 and the second film layer 13 are interposed between the foamed layer 12 wound earlier and the foamed layer 12 wound later, so that blocking can be suppressed without laminating a release paper or applying an ultraviolet coating to the foamed layer 12. In this way, the first film layer 11 and the second film layer 13 of this embodiment also function as layers that suppress blocking. When the sheet 10 of this embodiment is configured to be wound into a roll, the sheet 10 is easy to manufacture and easy to handle. EXAMPLES

[0092] Next, the above embodiment will be described more specifically with reference to examples and comparative examples. 1. Sheet Preparation First, a polyester polyurethane film (Luxkin U2245, manufactured by Seiko Chemical Industry Co., Ltd.) was prepared as the first polyurethane film of the Example and Comparative Example 2. The thickness of the first polyurethane film was 0.04 mm. The specific gravity of the first polyurethane film was 1.1 g / cm 3 It was. In addition, a film of polyether / ester polyurethane (Seiko Kasei, Luxkin U2462) was prepared as the second polyurethane film of the example. The thickness of the second polyurethane film was 0.02 mm. The specific gravity of the second polyurethane film was 1.1 g / cm 3 The surface of the second polyurethane film on which the film was placed was embossed to form a concave-convex shape. The thickness of the film having the concave-convex shape was measured as the dimension from the back surface to the top surface of the convex portion of the concave-convex shape.

[0093] Next, the components of the mixed raw materials used in the polyurethane foams of the examples and comparative examples 1 and 2 are shown below. Polymer polyol 1: Polymer polyol having a number average molecular weight of 3,000, a functional group number of 3, and a polymer content of 22% by mass (Asahi Glass Co., Ltd., EXCENOL 914) Polymer polyol 2: Polymer polyol having a number average molecular weight of 3,000, a functional group number of 2, and a polymer content of 20% by mass (Asahi Glass Co., Ltd., EXCENOL913) Polymer polyol 3: Polymer polyol having a number average molecular weight of 3,000, a functional group number of 3, and a polymer content of 40% by mass (manufactured by Sanyo Chemical Industries, Ltd., Sharp Flow FS-7301) Polyether polyol: Polyoxypropylene glyceryl ether having a number average molecular weight of 600 and a functional group of 3 (Sanyo Chemical Industries, Ltd., Sannix GP-600) Polyester polyol: polycaprolactone triol with a molecular weight of 540 and a functional group of 3 (Daicel Chemical Industries, Ltd., Plaxel 305) Crosslinker 1: Dipropylene glycol (manufactured by Asahi Glass Co., Ltd.) Crosslinker 2: MPO (2-methyl-1,3-propanediol) (manufactured by Dalian Chemical Co., Ltd.) Thickener: Aluminum hydroxide (Sumitomo Chemical Co., Ltd., C-31) Foam stabilizer: Dimethylpolysiloxane and polyether block copolymer (Toray Dow Corning Co., Ltd., SZ-1952 ADDITIVE) Catalyst 1: Iron catalyst (manufactured by Nippon Chemical Industry Co., Ltd., FIN-P1) Catalyst 2: Zinc amine catalyst (KING INDUSTRIES, K-KAT XK-622) Flame retardant 1: Expanded graphite (Shijiazhuang ADT Carbonic Material Factory, SYZR-802FP) Flame retardant 2: Ammonium polyphosphate (Terrage C-30, manufactured by CBC Corporation) Polyisocyanate: Polymeric MDI (BASF INOAC Polyurethanes, Formlite 500B)

[0094] [Table 1] The above components were mixed in the proportions shown in Table 1 to obtain mixed raw materials for polyurethane foams of the examples and comparative examples. The symbols (A) to (C) in Tables 1 and 2 indicate compounds corresponding to the components described in the embodiments. The numerical values ​​for each component in Table 1 indicate parts by mass.

[0095] The sheet of the embodiment was produced as follows. First, the mixed raw material was put into a mixing head, and stirred and mixed to become homogeneous while mixing in an inert gas (nitrogen) in the range of 10% by volume to 90% by volume. After that, the mixed raw material was supplied between the first polyurethane film and the second polyurethane film that were continuously supplied, and heat cured at 120°C to 170°C. In this way, a sheet was obtained in which a first film layer made of a first polyurethane film, a foamed layer made of a polyurethane foam, and a second film layer made of a second polyurethane film were laminated in this order.

[0096] The sheet of Comparative Example 1 was produced as follows. The foam layer was obtained in the same manner as the foam layer of the Example, except that a releasable substrate was used instead of the polyurethane film. After removing the releasable substrate, both sides of the obtained foam layer were UV-coated. The UV coating was performed by applying an acrylic resin and irradiating with UV. In this way, a sheet having coating layers on both sides and a foam layer made of polyurethane foam was obtained.

[0097] In the sheet of Comparative Example 1 thus obtained, the coating layer is exposed on the back side. The sheet of Comparative Example 1 is UV-coated mainly for the purpose of suppressing blocking. In other words, the sheet of Comparative Example 1 cannot actually eliminate the coating layer due to the convenience of production and handling. On the other hand, the sheet of the Example does not have a coating layer because blocking can be suppressed by the first film layer and the second film layer.

[0098] The sheet of Comparative Example 2 was produced as follows. The foam layer was obtained in the same manner as the foam layer of the Example, except that the mixed raw material was supplied onto the above-mentioned first polyurethane film, which was continuously supplied, and heat cured at 120°C to 170°C. In this manner, a sheet was obtained in which the first film layer made of the first polyurethane film and the foam layer made of polyurethane foam were laminated in this order. That is, the sheet of Comparative Example 2 differs from the Example in that it does not have a second film layer and the foam layer is exposed on the back surface.

[0099] 2. Measurement of Mean Cell Diameter For the sheets of the examples, the average cell diameter was measured by the method described in the embodiment. The average cell diameter of the polyurethane foams of the Examples was from 50 μm to 300 μm. Polyurethane foams having such cells have excellent impact absorption properties.

[0100] 3. Observation of the sheet The cross section of the sheet of the example was observed using a microscope. When the cross section of the first polyurethane film was observed over a length of 1200 μm, no holes were observed. Such a first polyurethane film has excellent cleaning properties. Furthermore, when the cross section of the polyurethane foam was observed, cells with a roughly spherical shape were observed. The size of the cells was highly uniform. A polyurethane foam having such cells has excellent impact absorption properties.

[0101] 4. Evaluation Next, the obtained sheets of the Examples and Comparative Examples 1 and 2 were evaluated under the following conditions: 25% compression load, flame resistance, Taber abrasion amount (mg) of the front surface, static friction coefficient of the back surface, Gurley air permeability (sec / 100 mL), and impact absorption. In the Examples, the front surface is the surface on the first polyurethane film (first film layer) side, and the back surface is the surface on the second polyurethane film (first film layer) side. In Comparative Example 1, both sides of the polyurethane foam are the front surface and the back surface. In Comparative Example 2, the front surface is the surface on the first polyurethane film side, and the back surface is the surface on the polyurethane foam (foam layer) side. The results are shown in Table 2.

[0102] [25% compression load] The 25% compression load (MPa) (25% CLD, JIS K 6254:2010) was measured as the compressive stress when a φ50 mm sample was compressed 25% at a speed of 1 mm / min. The 25% compression load of a commercially available pile carpet (thickness 8.0 mm) was 0.09 MPa. [Flame retardant] The test was conducted by the 45° air mix burner method in accordance with Article 4-3 of the Enforcement Regulations of the Fire Service Act. If the evaluation criteria were met, it was marked as "compliant" in Table 2. Note that no flame retardancy test was conducted on Comparative Example 1. [Amount of surface wear] In accordance with JIS K7204, the measurements were performed using an abrasive wheel H-22, a rotation speed of 60 rpm, a load of 250 g, and 1000 revolutions. Each condition was appropriately specified depending on the material of the sheet. [Static friction coefficient of back surface] The measurement was carried out in accordance with JIS K7125 at a temperature of 23° C. and a relative humidity of 50%. [Garley breathability] The air permeability was measured according to the B method (Gurley method) of the JIS L1096:2010 8.26.2. The compression amount was 50% and the range was 100 mL. Note that in the Example and Comparative Example 2, the air permeability exceeded 300 seconds / 100 mL, so the measurement was stopped and the results were recorded as "no air permeability" in Table 2. [Shock absorption] A sample was placed on a plastic tile (P tile), and a 112g steel ball was allowed to fall freely from a height of 200mm to measure the impact load (kN). The impact load measured without the sample was 0.97kN. The impact load of a commercially available pile carpet (thickness 8.0mm) was 0.36kN.

[0103] [Table 2]

[0104] As shown in Table 2, it was found that the Example had a smaller amount of wear on the surface than Comparative Example 1, and was therefore superior in wear resistance. It was also found that the Example had a larger static friction coefficient on the back surface than Comparative Examples 1 and 2, and was therefore superior in gripping ability. Furthermore, it was suggested that the Example had almost no breathability, and was therefore superior in cleaning ability. It was also confirmed that the Example had superior basic performance, such as 25% compression load, flame resistance, and impact absorption.

[0105] 5. Effects of the embodiment According to the above examples, it is possible to provide a sheet having excellent basic performance and improved surface abrasion resistance and back surface anti-slip properties, and a method for manufacturing a sheet having excellent basic performance and improved surface abrasion resistance and back surface anti-slip properties.

[0106] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present disclosure. [Explanation of symbols]

[0107] 10 ... sheet 10A…Surface 10B: Back side (surface facing the second film layer) 11 ... 1st film layer 11A…Uneven shape 12 ... Foam layer 13...Second film layer 13A…Uneven shape 21...First base material 23...Second base material 30...manufacturing equipment 32 ...Roll mechanism 33 ... First supply roll 34 ... 2nd supply roll 35 ... Product collection roll 36 ...Discharge nozzle 37...Heating part 38 ... First substrate recovery roll 39 ... Second substrate recovery roll

Claims

1. a first film layer composed of a first polyurethane film; A foam layer made of a polyurethane foam containing a flame retardant; a second film layer composed of a second polyurethane film, in this order; A sheet that satisfies the following (1). (1) The average cell diameter of the polyurethane foam is 50 μm or more and 300 μm or less, The sheet has a static friction coefficient of 0.3 to 10.0 on the surface of the second film layer side, measured in accordance with JIS K7125, in an atmosphere having a temperature of 23° C. and a relative humidity of 50%.

2. a first film layer composed of a first polyurethane film; A foam layer made of a polyurethane foam containing a flame retardant; a second film layer composed of a second polyurethane film, in this order; A sheet that satisfies the following (2). (2) The polyurethane foam is a polyurethane foam using a mixed raw material containing polyols and polyisocyanates, and the polyols include a polymer polyol. The content of the polymer polyol in the mixed raw material is 80 parts by mass or more when the total amount of the polyols is 100 parts by mass.

3. a first film layer composed of a first polyurethane film; A foam layer made of a polyurethane foam containing a flame retardant; a second film layer composed of a second polyurethane film, in this order; A sheet that satisfies the following (3). (3) The polyurethane foam contains, as the flame retardant, one or more of expandable graphite, melamine resin, and halogen-based flame retardant.

4. a first film layer composed of a first polyurethane film; A foam layer made of polyurethane foam; a second film layer composed of a second polyurethane film, in this order; The polyurethane foam has an average cell diameter of 50 μm or more and 300 μm or less, A method for producing a sheet having a thickness of the polyurethane foam of 2 mm or more and 20 mm or less, comprising the steps of: A method for manufacturing a sheet, comprising: supplying a polyurethane foam raw material between the first polyurethane film and the second polyurethane film traveling in one direction; and reacting and curing the polyurethane foam raw material to form the polyurethane foam.

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