JP7699314B2 - Sheet - Google Patents

Description

This disclosure relates to a sheet and a method for manufacturing the sheet.

Patent document 1 discloses a urethane foam molded product that can be used as a floor mat, etc.

JP 2013-255995 A

Conventional polyurethane foam sheets are desired to be improved in terms of abrasion resistance and impact absorption.
The present disclosure aims to provide a sheet having high abrasion resistance and impact absorption properties, and a method for manufacturing a sheet having high abrasion resistance and impact absorption properties.
The present disclosure can be realized in the following forms.

A surface layer made of a polyurethane film;
A foam layer made of polyurethane foam,
The polyurethane foam has an average cell diameter of 50 μm or more and 300 μm or less.

A surface layer made of a polyurethane film;
A sheet comprising: an installation layer made of polyurethane foam.

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

The present disclosure provides a sheet with high abrasion resistance and impact absorption properties, and a method for manufacturing a sheet with high abrasion resistance and impact absorption properties.

FIG. 2 is a cross-sectional view of a sheet according to an embodiment. 1 is a photograph showing an observed image of a cross section of a sheet. 1A to 1C are diagrams for explaining a manufacturing method of a sheet. FIG. 2 is a cross-sectional view of a polyurethane film with release paper.

Here is a preferred example of this disclosure:

The above sheet preferably has a Taber abrasion of 250 mg or less on the surface of the skin layer, measured according to JIS K7204 using an abrasive wheel H-22, a rotation speed of 60 rpm, a load of 250 g, and 1,000 rotations.

The static friction coefficient of the foam layer or the surface facing the installation layer of the above-mentioned sheet, measured in accordance with JIS K7125, should be 0.3 or more and 10.0 or less in an atmosphere having a temperature of 23°C and a relative humidity of 50%.

The present disclosure is described in detail below. In this specification, when a numerical range is described using "to" it is intended to include the lower limit and the upper limit unless otherwise specified. For example, the description "10 to 20" is intended to include 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".

Hereinafter, specific embodiments of the present disclosure will be described in detail.
The sheet 10 of this embodiment includes a surface layer 11 made of a polyurethane film and a foam layer 12 made of polyurethane foam. In this embodiment, the foam layer 12 corresponds to the installation layer.

1. Foam layer 12
The foam layer 12 is made of polyurethane foam. The 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 the mixed raw material is stirred and mixed without adding a specific foaming agent to the mixed raw material.

As the polyols, it is preferable to use a combination of at least three types of polyols: (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 residual strain and impact absorption resistance of the sheet 10 can be improved. Furthermore, in a configuration in which the foam layer 12 is the installation layer, the gripping properties of the sheet 10 can be improved.

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 functional number of 3. The first polyol, when used in combination with the second polyol and the third polyol, imparts strength such as tensile strength, hardness and flexibility according to the application to the polyurethane foam. As the first polyol, for example, a polymer polyol obtained by graft copolymerization of vinyl monomers such as acrylonitrile and styrene in a polyether polyol having a functional number 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 polyhydric alcohol such as glycerin can be mentioned. The number average molecular weight of the first polyol means the number average molecular weight of the base polyol.

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, and 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 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 with different number average molecular weights, polymer contents, etc.

The content of the first polyol in the mixed raw material is preferably 50 parts by mass to 80 parts by mass, more preferably 55 parts by mass to 78 parts by mass, and even more preferably 58 parts by mass to 70 parts by mass, when the total amount of polyols is 100 parts by mass. If this content is equal to or greater than the lower limit, strength such as tensile strength, hardness, and flexibility can be improved. If this content is equal to or less than the upper limit, strength such as tensile strength and tear strength can be ensured.

The second polyol is, for example, a polyether polyol having a number average molecular weight of 300 to 900 (preferably 450 to 750) and three functional groups. 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 the strength, such as tensile strength, and low compression set of the polyurethane foam.

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 polyhydric alcohol 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. The second polyol may contain only one type of polyether polyol, or may contain a combination of two or more types of polyether polyols with different number average molecular weights, functional groups, etc.

The content of the second polyol in the mixed raw material is preferably 5 parts by mass to 16 parts by mass, when the total amount of polyols is 100 parts by mass. If this content is 5 parts by mass or more, low compression set can be sufficiently obtained. If the content exceeds 16 parts by mass, low resilience is expressed. From the viewpoint of obtaining a polyurethane foam with high resilience, it is preferable to set the content to 16 parts by mass or less. If the content of the second polyol is set to 7 parts by mass to 10 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 greater than the content of the third polyol.

The third polyol is, for example, a polyester polyol having two or three functional groups. 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.

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, 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 with three functional groups from the viewpoint of making hydrolysis difficult to occur and reducing the content of volatile organic compounds.

The content of the third polyol in the mixed raw material is preferably 1 to 6 parts by mass, and more preferably 2 to 5 parts by mass, when the total amount of polyols is 100 parts by mass. If this 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 at or above the lower limit. Furthermore, if the content is 6 parts by mass or less, an increase in compression set can be suppressed, and low compression set can be ensured.

The polyols may contain other polyols in addition to the first to third polyols. Any other polyols that are generally used in polyurethane foams can be used 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 hindered phenol-based antioxidants with a molecular weight of 300 or more.

Polyisocyanates are compounds having multiple isocyanate groups. Examples of polyisocyanates that can be used 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), or free isocyanate prepolymers obtained by reacting these with polyols, and modified polyisocyanates such as carbodiimide-modified polyisocyanates. Only one of these polyisocyanates may be contained, or two or more of them may be contained in combination.

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. In addition, the number of functional groups of the polyisocyanates is preferably in the range of 2.0 to 2.2.

The isocyanate index of 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, if the value is less than 1, it means that the reactive groups, such as hydroxyl groups, are in excess of the isocyanate groups, and if 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.

The mixed raw material preferably contains a foam stabilizer. The foam stabilizer is used to facilitate the foaming of the mixed raw material. As the foam stabilizer, a known foam stabilizer that is usually used when the mechanical froth method is adopted, such as a silicone-based foam stabilizer, can be used. Since such foam stabilizers have a high viscosity, they are usually diluted with a solvent such as alkylbenzene and then mixed into the mixed raw material. As the solvent, a low-viscosity polyol with 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 with a molecular weight (number average molecular weight) of 1700 or less and polyols that are liquid at room temperature.

The content of the foam stabilizer in the mixed raw material is preferably 3 to 6 parts by mass per 100 parts by mass of polyols. If the content is 3 parts by mass or more, the foam stabilization power is sufficient, and a uniform cell structure can be formed and the density can be reduced. Furthermore, even if the content exceeds 6 parts by mass, no significant improvement in foam stabilization power can be expected. Furthermore, when the foam stabilizer is diluted with a solvent, the mass ratio (foam stabilizer:solvent) is preferably in the range of 25:75 to 75:25.

The catalyst is primarily intended to promote the urethane reaction between polyols and polyisocyanates, and the mixed raw material preferably contains a catalyst. As the catalyst, known catalysts commonly used in polyurethane foams, such as organometallic compounds such as ferric acetylacetonate, stannous octoate, and tin octoate (tin octoate), tertiary amines such as triethylenediamine, dimethylethanolamine, and N,N',N'-trimethylaminoethylpiperazine, acetates, and alkali metal alcoholates can be used.

The catalyst content in the mixed raw material is preferably 0.1 to 5.0 parts by mass per 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 5.0 parts by mass or less, the urethane reaction is prevented from being excessively promoted, and the cell structure can be formed uniformly.

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 in which ethylene oxide, polypropylene oxide, etc. are added to these active hydrogen compounds.

The content of the crosslinking agent in the mixed raw material is preferably 2.0 to 10.0 parts by mass per 100 parts by mass of polyols. If this content is 2.0 parts by mass or more, strength such as tensile strength can be ensured. Also, if the above content is 10.0 parts by mass or less, appropriate hardness and high resilience can be imparted.

The mixed raw material may contain other components in addition to those mentioned above, as necessary. Examples of the other components include antioxidants, ultraviolet absorbers, thickeners, plasticizers, antibacterial agents, flame retardants, 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 with a molecular weight of 300 or more. Examples of the thickener include calcium carbonate, aluminum hydroxide, and magnesium hydroxide. Examples of the flame retardant include expanded graphite, phosphate esters, melamine resins, and halogen-based flame retardants.

From the viewpoint of shock absorption resistance, it is preferable that the polyurethane foam has either an open cell structure or a semi-open cell structure, and it is more preferable that the polyurethane foam has an open cell structure. Unlike a closed cell structure, an open cell structure and a semi-open cell structure have pores in the bubbles. The cell structure of a polyurethane foam can be evaluated by measuring the air permeability of the polyurethane foam. The air permeability of a 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 a polyurethane foam is, for example, 5 seconds/100 mL or more and 20 seconds/100 mL or less.

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 a 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, the thickness of the cell membrane constituting the cells is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of maintaining the elasticity of the polyurethane foam.

From the viewpoint of maintaining uniformity of the product, it is preferable that 70% or more of the cells have a cell size distribution within ±50 μm of the average cell size, more preferably within ±30 μm, and particularly preferably within ±20 μm. The cell size distribution can be calculated based on the cell size obtained when the average cell size described above is measured.

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 a 1 mm x 1 mm area, calculating the circularity of each, and averaging the results.

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

The thickness of the polyurethane foam is not particularly limited. From the viewpoint of shock absorption resistance, 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.

The specific gravity of the polyurethane foam is not particularly limited. From the viewpoint of hardness, the specific gravity of the polyurethane foam is preferably 0.05 g/cm ³ or more, more preferably 0.08 g/cm ³ or more, and even more preferably 0.15 g/cm ³ or more. From the viewpoint of impact absorption, the specific gravity of the polyurethane foam is preferably 0.70 g/cm ³ or less, more preferably 0.60 g/cm ³ or less, and even more preferably 0.50 g/cm ³ or less. From these viewpoints, the specific gravity of the polyurethane foam is preferably 0.05 g/cm ³ or more and 0.70 g/cm ³ or less, more preferably 0.08 g/cm ³ or more and 0.60 g/cm ³ or less, and even more preferably 0.15 g/cm ³ or more and 0.50 g/cm ³ or less.

2. Epidermal layer 11
The surface layer 11 is made of a polyurethane film. The polyurethane film can be obtained by reacting a mixed raw material containing polyols and polyisocyanates.

Polyols that can be used include polyester polyols, polyether polyols, polycarbonate polyols, polymer polyols, and mixtures thereof. Among these, polyester polyols are preferred from the standpoint of abrasion resistance.

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 branched polyesters can also be obtained by using ester-forming components with a valence of 3 or more.

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 greater than the above lower limit, the abrasion resistance is good. If the content of polyester polyol is equal to or less than the above upper limit, it is preferable from the viewpoint of physical strength.

Polyisocyanates are compounds that have multiple 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.

The 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 polyurethane film.

The thickness of the polyurethane film is not particularly limited. From the viewpoints of abrasion resistance and moldability, the thickness of the polyurethane film is preferably 0.001 mm or more, more preferably 0.002 mm or more, and even more preferably 0.003 mm or more. From the viewpoints of stretchability and cost, the thickness of the polyurethane film is preferably 0.100 mm or less, more preferably 0.050 mm or less, and even more preferably 0.010 mm or less. From these viewpoints, the thickness of the polyurethane film is preferably 0.001 mm or more and 0.100 mm or less, more preferably 0.002 mm or more and 0.050 mm or less, and even more preferably 0.003 mm or more and 0.010 mm or less.

The specific gravity of the polyurethane film is not particularly limited. From the viewpoint of breathability, the specific gravity of the polyurethane film is preferably 0.8 g/cm ³ or more, more preferably 0.9 g/cm ³ or more, and even more preferably 1.0 g/cm ³ or more. From the viewpoint of flexibility, the specific gravity of the polyurethane film is preferably 1.5 g/cm ³ or less, more preferably 1.3 g/cm ³ or less, and even more preferably 1.2 g/cm ³ or less. From these viewpoints, the specific gravity of the polyurethane film is preferably 0.8 g/cm ³ or more and 1.5 g/cm ³ or less, more preferably 0.9 g/cm ³ or more and 1.3 g/cm ³ or less, and even more preferably 1.0 g/cm ³ or more and 1.2 g/cm ³ .

The elongation of the polyurethane film is not particularly limited. The elongation of the polyurethane film is preferably 150% or more, more preferably 150% to 500%, and even more preferably 200% to 500%. When the elongation is equal to or more than the lower limit, the polyurethane 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.

The polyurethane film is preferably a non-foaming polyurethane film. It is more preferable to use a substantially non-porous polyurethane film. The polyurethane film may be produced by a wet method, a dry method, or the like, but the dry method is preferable to obtain a substantially non-porous polyurethane film. Specifically, the polyurethane film is applied to a releasable substrate 13 such as release paper or release film by a normal coating method, for example, a knife coater, a comma coater, a reverse coater, or the like, to form a film.
The polyurethane film can be evaluated for its substantially non-porous nature by measuring its air permeability. For example, the polyurethane film may have a Gurley air permeability of more than 10,000 seconds/100 mL.

Figure 4 shows an example of a film 11P with a substrate 13 used in polyurethane films. One side of this film 11P has an uneven shape 11A. The uneven shape 11A forms, for example, a grained or geometric pattern. When such a film 11P is used, the uneven shape 11A appears on the surface 10A of the sheet 10 shown in Figure 1, improving the appearance and feel of the sheet 10. The uneven shape 11A can be formed, for example, by transferring a shape given to the substrate 13.

3. Structure of the Sheet The sheet 10 is, for example, a laminate of a surface layer 11 of ester-based polyurethane and a foam layer 12 of ether-based polyurethane. The foam layer 12 and the surface layer 11 are preferably in direct contact with each other and bonded to each other. The surface layer 11 is exposed on the side opposite to the foam layer 12 and constitutes the front surface 10A of the sheet 10. In this embodiment, the foam layer 12 is exposed on the side opposite to the surface layer 11 and constitutes the back surface 10B of the sheet 10. In the present disclosure, when the foam layer 12 is exposed on the side opposite to the surface layer 11, the foam layer 12 is also referred to as an installation layer.

The sheet 10 is suitable as a rug (carpet, flooring material). When used as a rug, the sheet 10 is placed with the surface 10A facing up on a surface such as a room, a hallway, or the floor of a vehicle. The configuration of the sheet is not limited to this. For example, unlike this embodiment, the sheet may further include an optional layer such as an anti-slip layer on the opposite side of the foam layer from the skin layer.

The Taber abrasion of the surface 10A of the sheet 10 facing the skin 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 surface 10B of the sheet 10 facing the foam layer 12 is greater than the Taber abrasion of the surface of the sheet 10 facing the skin 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.

The static friction coefficient of the surface 10B of the sheet 10 facing the foam layer 12 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%.

When the foam layer 12 is the installation layer, the foam layer 12 comes into contact with the installation surface. The foam layer 12 has a high static friction coefficient and functions as an anti-slip layer for the installation surface. Therefore, the grip of the sheet 10 against the installation surface can be ensured even if there is no adhesive layer or the like between the sheet 10 and the installation surface.

4. Sheet Manufacturing Method The sheet manufacturing method includes, for example, supplying polyurethane foam raw material to the surface of a polyurethane film traveling in one direction, and reacting and curing the polyurethane foam raw material to form the polyurethane foam. In the sheet manufacturing method of this embodiment, polyurethane foam is manufactured by a mechanical froth method. The sheet can be manufactured using a manufacturing apparatus 30.

The manufacturing device 30 includes a mixing section 31, a roll mechanism 32 including a supply roll 33 and a product recovery roll 34, a discharge nozzle 35, a thickness regulation section 36, and a heating section 38. The mixing section 31 is a section for mixing raw materials to obtain polyurethane foam raw material M. The supply roll 33 is a section on which a polyurethane film with a substrate 13 is wound, and supplies the polyurethane film by a driving source (not shown). The product recovery roll 34 is a section for winding the sheet 10 into a roll and recovering it. The discharge nozzle 35 is a section for supplying polyurethane foam raw material M onto the polyurethane film. The thickness regulation section 36 is composed of a doctor knife or the like that controls the thickness of the polyurethane foam raw material M on the polyurethane film. The heating section 38 is composed of a heater or the like that heats the polyurethane foam raw material M on the polyurethane film. Furthermore, the manufacturing device 30 includes a substrate recovery roll 39 that peels off the substrate 13 from the polyurethane film and recovers it.

The sheet 10 can be manufactured as follows. First, a polyurethane film with a substrate 13 is continuously supplied from a supply roll 33. As the polyurethane film is continuously supplied, polyurethane foam raw material M is supplied from a discharge nozzle 35 to the polyurethane film. The thickness of the supplied polyurethane foam raw material M is adjusted to a predetermined thickness by a thickness regulation section 36. Next, the polyurethane foam raw material M is heated in a heating section 38 to react and harden. After the polyurethane foam and polyurethane film in a laminated state are fixed together, the substrate 13 is peeled off, and the sheet 10 is taken up on a product recovery roll 34.

The sheet 10 thus obtained can be cut into a desired 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.

Next, the effects of this embodiment will be described.
Traditionally, fiber materials and resin foams such as polyethylene foam and EVA have been used for personal use and in removable rugs (carpet materials, floor 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 fewer steps (thin thickness) and excellent shock absorption performance are required due to barrier-free access and safety measures in the event of a fall. Thus, there is an increasing demand for sheets that have the basic functions of carpets and have high shock absorption properties.

The sheet 10 of this embodiment includes the surface layer 11 and the foam layer 12, and thus has high abrasion resistance and impact absorption properties.
Since the sheet 10 has high shock absorption properties, it can be made thinner to accommodate wheelchairs and walkers needed by people who need care or small children, and the difference in level can be reduced. Furthermore, it can absorb shock in the event of a fall, ensuring safety.
The sheet 10 has high abrasion resistance, so durability can be ensured. 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.

The sheet 10 of this embodiment is easy to install because the foam layer 12 has a high grip. Specifically, the sheet 10 is not easily slippery on the installation surface even when the foam layer 12 is simply placed in contact with the installation surface. Therefore, when installing the sheet 10, it can be installed directly on the installation surface without using an adhesive or glue as in the past. Furthermore, when an adhesive or glue is not used, there is no need to use a solvent to remove the adhesive or glue remaining on the installation surface when the mat is removed.

The sheet 10 of this embodiment is resistant to solvents and dirt from penetrating the surface layer 11, and any deposits on the surface layer 11 can be easily wiped off. This makes the sheet 10 easy to clean. In addition, the surface layer 11 has high chemical resistance, which contributes to improving the durability of the sheet 10.

If the foam layer 12 is highly resilient, the feet do not sink too much when walking, making it easy to walk. Similarly, if the foam layer 12 is highly resilient, the wheels of a wheelchair or walker do not sink too much when running, making it easy to run.

In the manufacturing method of the sheet 10 of this embodiment, the skin layer 11 and the foam layer 12 are molded integrally, so there is no need to take the time to bond the skin layer 11 and the foam layer 12 together. In addition, since both the skin layer 11 and the foam layer 12 are made of polyurethane resin, the adhesive strength is ensured and peeling is unlikely to occur.

The manufacturing method of the sheet 10 of this 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 with just one sheet, making it easy to use as a carpet. In addition, the sheet 10 can be easily cut to a specified size to adjust the size.

Furthermore, in the manufacturing method of the sheet 10 of this embodiment, even when the sheet 10 is wound into a roll, the surface layer 11 is interposed between the first-wound foam layer 12 and the second-wound foam layer 12. If the first-wound foam layer 12 and the second-wound foam layer 12 come into contact with each other, measures are taken to prevent the foam layers 12 from blocking each other, such as laminating a release paper or applying a UV (ultraviolet) coating to the foam layer 12. In the sheet 10 of this embodiment, the surface layer 11 is interposed between the first-wound foam layer 12 and the second-wound foam layer 12, so that blocking can be suppressed without laminating a release paper or applying a UV coating to the foam layer 12. In this way, the surface layer 11 of this embodiment also functions as a layer that suppresses 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.

Next, the above embodiment will be described more specifically with reference to examples and comparative examples.
1. Preparation of Sheet First, a polyester polyurethane film (Rackskin U2245, manufactured by Seiko Kasei) was prepared as the polyurethane film of the example. The thickness of the polyurethane film was 0.004 mm. The specific gravity of the polyurethane film was 1.1 g/ ^cm3 .

Next, the components of the mixed raw materials used in the polyurethane foams of the Examples and Comparative Examples 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 (manufactured by 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 (manufactured by Asahi Glass Co., Ltd., EXCENOL 913)
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 having a molecular weight of 540 and a functional group of 3 (manufactured by Daicel Chemical Industries, Ltd., Plaxel 305)
Crosslinking agent 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: Block copolymer of dimethylpolysiloxane and polyether (manufactured by Dow Corning Toray Co., Ltd., SZ-1952 ADDITIVE)
Catalyst: Ferric acetylacetonate (Nippon Chemical Industry Co., Ltd., Nursem Ferric)
Isocyanate: Polymeric MDI (BASF INOAC Polyurethanes, Formlite 500B)

上記各成分を表１に示す配合割合で調製し、実施例及び比較例のポリウレタンフォームの混合原料を得た。なお、表１及び２中の（Ａ）～（Ｃ）の標記は実施形態に記載の各成分に対応する化合物を示す。表１中の各成分の数値は質量部を表す。

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.

The sheets of the examples were produced as follows. First, the mixed raw materials were charged into a mixing head and mixed homogeneously while mixing in an inert gas (nitrogen) in the range of 69% to 77% by volume. The mixed raw materials were then fed onto the polyurethane film, which was continuously fed, and heat cured at 120°C to 200°C. In this way, a sheet was obtained in which a surface layer made of polyurethane film and a foam layer made of polyurethane foam were laminated.

The sheet of the comparative example 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 light. In this way, a sheet was obtained that had coating layers on both sides and was made of a foam layer made of polyurethane foam.

In the comparative sheet obtained in this manner, the coating layer is exposed on the side opposite the skin layer, whereas in the example sheet, the foam layer is exposed on the side opposite the skin layer. The comparative sheet is UV coated mainly for the purpose of suppressing blocking. In other words, the comparative sheet cannot actually dispense with the coating layer due to manufacturing and handling reasons. On the other hand, the example sheet does not have a coating layer, as blocking can be suppressed by the polyurethane film skin layer.

2. Measurement of Average Cell Diameter The average cell diameter of the sheets of the examples 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.

3. Observation of the Sheet The cross section of the sheet of the example was observed using a microscope. The observed image of the cross section of the sheet is shown in FIG.
When the cross section of the polyurethane film was observed over a length of 1200 μm, no holes were observed. Such a 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.

4. Evaluation Next, the obtained sheets of the examples and comparative examples were evaluated under the following conditions for the Taber abrasion amount (mg) of the front surface, the static friction coefficient of the back surface, and the Gurley air permeability (sec/100 mL). In the examples, the front surface is the surface on the polyurethane film (skin layer) side, and the back surface is the surface on the polyurethane foam (foam layer) side. In the comparative examples, both sides of the polyurethane foam are the front surface and the back surface. The results are shown in Table 2.

[Amount of surface wear]
The measurement was performed 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 a number of rotations of 1000. Note that 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%.
[Gurley breathability]
The air permeability was measured according to the B method (Gurley method) of the air permeability test set forth in JIS L1096:2010 8.26.2. The compression amount was 50% and the range was 100 mL. In the examples, the air permeability exceeded 300 seconds/100 mL, so the measurement was stopped and the results are indicated as "-" in Table 2.

As shown in Table 2, the Examples showed less wear on the film surface than the Comparative Examples, demonstrating superior wear resistance. The Examples also showed a greater static friction coefficient on the foam surface than the Comparative Examples, demonstrating superior grip. Furthermore, the Examples showed almost no breathability, suggesting superior cleaning properties.

5. Effects of the Examples According to the above examples, it is possible to provide a sheet having high abrasion resistance and impact absorbing properties, and a method for manufacturing a sheet having high abrasion resistance and impact absorbing properties.

This disclosure is not limited to the embodiments detailed above, and various modifications and variations are possible within the scope of the claims of this disclosure.

10 ... sheet 10A ... surface (surface on the skin layer side)
10B: Back surface (foam layer side)
REFERENCE SIGNS LIST 11: surface layer 11A: uneven shape 11P: film 12: foam layer 13: substrate 30: manufacturing device 31: mixing section 32: roll mechanism 33: supply roll 34: product recovery roll 35: discharge nozzle 36: thickness regulation section 38: heating section 39: substrate recovery roll

Claims (2)

A surface layer made of a polyurethane film;
A foam layer made of polyurethane foam,
The polyurethane foam has an average cell diameter of 50 μm or more and 300 μm or less,
A sheet that satisfies the following (2).
(2) The polyurethane foam uses polyols including polymer polyols and polyether polyols as raw materials,
The content of the polymer polyol in the raw material is 50 parts by mass or more when the total amount of the polyols is 100 parts by mass,
The content of the polyether polyol in the raw material is 16 parts by mass or less when the total amount of the polyols is 100 parts by mass. A surface layer made of a polyurethane film;
A mounting layer made of polyurethane foam;
A sheet that satisfies the following (1).
(1) The polyurethane film has a thickness of 0.010 mm or less,
The polyurethane foam is a polyurethane foam using a mixed raw material containing polyols and polyisocyanates, and the polyols include a first polyol composed of a polymer polyol and a second polyol composed of a polyether polyol,
The content of the first polyol in the mixed raw material is 50 parts by mass or more when the total amount of the polyols is 100 parts by mass,
The content of the second polyol in the mixed raw material is 16 parts by mass or less when the total amount of the polyols is 100 parts by mass.

Images