JP2020124384A - Floor mat and leg fatigue evaluation method - Google Patents

Abstract

To provide a floor mat having high fatigue reduction effect, and to provide a leg fatigue evaluation method capable of objectively determining a sense of fatigue of a user who performs such as standing work and walking on the floor mat.SOLUTION: A floor mat 120 has an urethane layer comprising a polyurethane foam. The polyurethane foam is so formed that an apparent density is 0.25 g/cmor more and 0.60 g/cmor less, a C hardness is 40 or more and 70 or less, and a rebound resilience ratio is 40% or more and 80% or less. A leg fatigue evaluation method includes: attaching a myoelectric potential measuring electric terminal 320 capable of measuring the myoelectric potentials of muscles to a part in which a prescribed muscle is positioned, on a skin surface of the leg of an examiner 300; making the examiner stand on a floor mat arranged on a floor face 150 and repeat prescribed performance for a prescribed time; measuring the myoelectric potential of the muscle with time in the prescribed time; acquiring a regression line from the measured myoelectric potential value; and evaluating a fatigue degree of the leg of the examiner from the inclination of the regression line.SELECTED DRAWING: Figure 3

Description

The present invention relates to a floor mat and a leg fatigue evaluation method for evaluating a degree of fatigue of a leg when operating on the floor mat.

It is known that there are many people who have bad legs due to long standing work in factories and stores. Therefore, for the purpose of reducing fatigue, a rubber mat to be laid on the floor of a site where standing work is performed has been proposed (for example, Patent Documents 1 and 2).

In addition, the floor performance evaluation guidelines issued by the Architectural Institute of Japan show an evaluation of the effect of the hardness of the floor surface on daily activities, and a floor showing appropriate softness is suitable for daily operations. (Non-patent document 1, Chapter 2, “Hardness, non-vibration”, Section 2, “Hardness of floor during daily operation”, page 8 to page 14, section 12).

Generally, a mat used for the purpose of reducing fatigue such as standing work has a proper flexibility and shock absorbing property and tends to be preferred because it gives a comfortable feel to the sole of the foot.

JP, 2011-046152, A JP, 2013-215312, A Floor performance evaluation guideline, Publisher; Architectural Institute of Japan, Date of issue; November 20, 2015

However, even when a conventional fatigue-reducing mat is laid on the floor, the legs may feel tired due to long-term work or the like. Therefore, the inventors diligently studied the relationship between the mat and fatigue. As a result, a mat with high flexibility can feel the comfort of the sole of the foot in a short time, but when the user sits on the mat, the sinking is great and the next movement is difficult to perform, and fatigue is reduced. It has been found that there is a large accumulation of. Therefore, it has been found that when the user performs standing work or the like for a long time on a highly flexible mat, the user may feel strong fatigue.

Further, conventionally, the evaluation of the mat for reducing fatigue is mainly judged by the subjectivity of the user. Therefore, in a short-time work, comfort due to being soft comes first, and there is a possibility that accumulation of fatigue cannot be objectively evaluated.

The present invention has been made in view of the above problems. That is, the present invention provides a floor mat having a high fatigue reducing effect, and a leg fatigue evaluation method capable of objectively determining the tiredness of a user who performs an operation such as standing work or walking on the floor mat. The challenge is to provide.

The floor mat of the present invention has a urethane layer made of polyurethane foam, and the polyurethane foam has an apparent density of 0.25 g/cm ³ or more and 0.60 g/cm ³ or less,
The C hardness is 40 or more and 70 or less, and the impact resilience is 40% or more and 80% or less.

Further, the leg fatigue evaluation method of the present invention is a place where a predetermined muscle is located on the skin surface of the leg of the tester, and a myoelectric potential measurement terminal capable of measuring the myoelectric potential of the muscle is attached to the tester. Stands up on a floor mat placed on the floor, repeats a predetermined operation for a predetermined time, measures the myoelectric potential of the muscle over time within the predetermined time, and from the value of the measured myoelectric potential, A regression line is obtained, and the degree of fatigue of the leg of the tester is evaluated by the slope of the regression line.

The floor mat of the present invention having the above structure has a higher fatigue reducing effect than the conventional mat made of rubber or the like.
Further, the leg fatigue evaluation method of the present invention can easily and objectively evaluate the fatigue of the leg of a person who has operated on various floor mats including the floor mat of the present invention. Therefore, according to the leg fatigue evaluation method of the present invention, it is possible to objectively evaluate the floor mat, which has been evaluated with the subjective contents that "it is hard to get tired" and "easy to get tired" up to now. This makes it possible to provide a floor mat that exhibits an excellent fatigue reducing effect.

It is sectional drawing of 1st embodiment of the floor mat of this invention. It is a perspective view of a second embodiment of the floor mat of the present invention. It is explanatory drawing explaining the leg fatigue|exhaustion evaluation method of this invention. It is explanatory drawing for demonstrating the shape of the weight used in the drop impact test. It is a graph which shows the data obtained by the leg fatigue|exhaustion evaluation, FIG. 5a shows the result of the myoelectric potential measurement at the time of using the test sheet produced from Example 1, and FIG. 5b produced from Example 4. 5C shows the result of myoelectric potential measurement when using the test sheet, FIG. 5C shows the result of myoelectric potential measurement when using the test sheet produced from Comparative Example 3, and FIG. 5D was produced from Comparative Example 4. The result of myoelectric potential measurement when using a test sheet is shown.

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the duplicate description will be appropriately omitted. It should be noted that the drawings used for the description of the present invention do not limit the size and shape of the present invention and members included in the present invention.
Some terms used in this specification are as follows. The user refers to a person who operates on the floor mat, and the above-mentioned operation includes not only the operation but also the operation other than the operation. The floor refers to a structural portion that constitutes a walking surface of a building, and the floor surface is an upper surface of the floor and a surface with which the soles of people walking or the like come into contact. In the present invention, the floor mat is a sheet-like object laid on the floor, is a type that is fixed to the floor and is used, and a table that is placed on the floor and is easily movable. Includes all types of flooring. The floor-standing floor mat is highly versatile because it can be easily moved as the work area moves.

<First embodiment>
The floor mat 100 according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing a cross section obtained by cutting the floor mat 100 in the thickness direction. FIG. 4 is an explanatory diagram for explaining the shape of the weight W used in the drop impact test described later.

As shown in FIG. 1, the floor mat 100 has a urethane layer 10 made of polyurethane foam. The polyurethane foam exhibits an apparent density, C hardness and impact resilience within a predetermined range. The floor mat 100 having such a configuration has an appropriate hardness to suppress the sinking of the user's legs, and an appropriate impact resilience to facilitate the next operation, This significantly reduces the fatigue of the legs of the user who works on the floor mat 100.

In the floor mat 100 according to this embodiment, the protective layer 20 is provided on the upper surface side of the urethane layer 10. This is one embodiment of the present invention, and the floor mat of the present invention has a single-layer structure consisting essentially of a urethane layer, and a lower surface laminated structure in which an arbitrary layer is laminated on the lower surface side of the urethane layer 10. Both the aspect and the aspect of the upper and lower area layers in which arbitrary layers are laminated on the upper and lower surfaces of the urethane layer 10. When an arbitrary layer is laminated on the urethane layer 10, the arbitrary layer may be a single layer or a plurality of layers. The aspect of the single layer will be described later as a second embodiment.

[Urethane layer]
The thickness of the urethane layer 10 is not particularly limited, and can be appropriately changed in consideration of the content of work performed on the floor mat 100 and the like. From the viewpoint of better reducing the fatigue of the legs of the user, the thickness of the urethane layer 10 is preferably 6 mm or more, and more preferably 10 mm or more. Further, from the viewpoint of exerting a good fatigue reducing effect without economical disadvantage, the thickness of the urethane layer 10 is preferably 20 mm or less, and more preferably 17 mm or less. When the urethane layer 10 has a substantially uniform thickness, the thickness of the urethane layer 10 refers to, for example, an arithmetic average value of the thicknesses actually measured at 10 randomly selected locations.

(Apparent density)
The urethane layer 10 is made of polyurethane foam. The apparent density of the polyurethane foam forming the urethane layer 10 is 0.25 g/cm ³ or more and 0.60 g/cm ³ or less. By realizing such an apparent density, it is easy to adjust the C hardness and the impact resilience of the polyurethane foam within a predetermined range.
If the apparent density of the polyurethane foam is less than 0.25 g/cm ³ , the C hardness of the polyurethane foam becomes too small, and the legs of the user may sink into the mat to the extent of promoting fatigue.
On the other hand, when the apparent density of the polyurethane foam is more than 0.60 g/cm ³ , the C hardness of the polyurethane foam becomes too large, and there is a risk of lacking flexibility and impairing the feeling of use.

The apparent density of the urethane layer 10 is measured according to JIS K7222.

(C hardness)
The C hardness of the polyurethane foam forming the urethane layer 10 is 40 or more and 70 or less.
If the C hardness of the polyurethane foam is less than 40, the legs of the user may sink into the floor mat 100 to the extent that fatigue is promoted. The C hardness is preferably 42 or more, and more preferably 45 or more, from the viewpoint of favorably preventing sinking.
On the other hand, when the C hardness of the polyurethane foam exceeds 70, the floor mat 100 may lack flexibility and the usability may be impaired. Therefore, from the viewpoint of the flexibility of the floor mat 100, the C hardness is preferably 68 or less, and more preferably 65 or less.

The C hardness of the polyurethane foam is measured according to JIS K 7312, using an Asker rubber hardness meter C type. More specifically, the C hardness is measured by the above measuring method using a sheet-shaped test piece having a thickness of 12.5 mm and made of polyurethane foam forming the urethane layer 10.

(Rebound resilience)
The impact resilience of the polyurethane foam forming the urethane layer 10 is 40% or more and 80% or less.
By setting the impact resilience of the polyurethane foam to 40% or more, the floor mat 100 can sufficiently exert the force of pushing back the user's legs (particularly the soles of the feet). To make it easier to perform. As a result, when the user repeats the operation on the floor mat 100, the accumulation of fatigue is suppressed to be small, and the fatigue of the legs is reduced. From the viewpoint of exhibiting the fatigue reducing effect more favorably, the impact resilience is preferably 42% or more, more preferably 45% or more, and further preferably 48% or more.
On the other hand, when the impact resilience of the polyurethane foam exceeds 80%, the stability of the sole of the foot is deteriorated, which may cause fatigue to accumulate. From the viewpoint of the stability of the sole, the impact resilience is preferably 78% or less, more preferably 75% or less.

The method for measuring the impact resilience of the polyurethane foam is measured according to JIS K 6255. To measure the impact resilience, more specifically, the impact resilience is measured by the above measurement method using a sheet-shaped test piece having a thickness of 12.5 mm and made of polyurethane foam that constitutes the urethane layer 10. ..

(Maximum impact load)
The maximum impact load of the polyurethane foam constituting the urethane layer 10 is not particularly limited, but is preferably 0.6 kN or more and 1.2 kN or less, and more preferably 0.7 kN or more and 1.2 kN or less. The maximum impact load indicates that the smaller the value is, the more the impact is absorbed. Within the above range, the impact on the sole of the foot is not impaired on the floor mat 100 without impairing the stability of the sole of the foot. Can be absorbed well.

The maximum impact load of the polyurethane foam is measured by the drop impact test shown below. The shape of the weight W used in the drop impact test is shown in FIG.
Drop impact test;
A sheet-shaped test piece having a thickness of 12.5 mm made of polyurethane foam constituting the urethane layer 10 is prepared, the test piece is placed on a horizontal test stand, and a 5.1 kg weight W is dropped from a height of 50 mm. Then, the test piece is made to collide with the test piece, and the maximum impact load at that time is measured. More specifically, the maximum impact load can be measured using, for example, product name Dynatup GRC8200 manufactured by Instron Co., Ltd.

(Compression set)
The compression set of the polyurethane foam forming the urethane layer 10 is preferably 30% or less, more preferably 20% or less, and further preferably 15% or less. By setting the compression set to 30% or less, the durability of the floor mat 100 can be improved.

The compression set of the polyurethane foam is measured according to JIS K 6262. More specifically, the compression set is measured under the conditions of a compression rate of 25%, 40° C., and 24 hours using a sheet-shaped test piece having a thickness of 12.5 mm and made of polyurethane foam that constitutes the urethane layer 10. To be done.

(Composition of polyurethane foam)
The polyurethane foam forming the urethane layer 10 is formed by reacting a polyurethane raw material composition containing a polyol component, an isocyanate component, a foaming agent and the like. The polyurethane foam can be manufactured by a known method for manufacturing polyurethane foam.

[Polyol component]
Examples of the polyol component include polyether polyol and polyester polyol.

As the polyether polyol, for example, a polyether polyol obtained by ring-opening polymerization of alkylene oxide is suitable. Examples of the alkylene oxide include propylene oxide (PO), ethylene oxide (EO) and butylene oxide, and these may be used alone or in combination of two or more. More specific preferable examples include polytetramethylene ether glycol or polypropylene glycol.

In particular, a polyurethane foam formed by using polytetramethylene ether glycol as a polyol has an appropriate hardness (C hardness) by adjusting the foam to a density within a predetermined range at the time of molding, and has a rebound resilience. It is also easy to make it moderately high. Therefore, the floor mat 100 including the urethane layer 10 made of such a polyurethane foam can provide the floor mat 100 including the polyurethane layer having a particularly high fatigue reducing effect.
In order to solve the intended problem of the present invention, polypropylene glycol is also preferably selected as the above polyol.

Examples of polyester polyols include polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid, and adipic acid, and aromatic carboxylic acids such as phthalic acid, and polyhydric alcohols such as ethylene glycol, diethylene glycol, and propylene glycol. The obtained product can be used.

As the polyol component, a polyether polyol having a number average molecular weight of 300 or more and 5000 or less is preferable. For example, as the polyol component, a single compound may be used, a plurality of polyol components having the same composition but different number average molecular weights may be mixed and used, or a plurality of polyols having different compositions and number average molecular weights may be used. You may mix and use a component.

When the number average molecular weight of the polyol component is less than 300, the flexibility of the floor mat 100 is likely to be impaired, and it may be difficult to obtain the user's leg fatigue reducing effect.
On the other hand, when the number average molecular weight of the polyol component exceeds 5,000, the impact resilience in the predetermined range specified in the present invention may not be obtained.

In addition, you may add a crosslinking agent to a polyol component as needed. Examples of the cross-linking agent include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, tetramethylene ether glycol, glycerin, pentaerythritol, trimethylolpropane, monoethanolamine, diethanolamine, isopropanolamine, amino. Alcohols such as ethyl ethanolamine, sucrose, sorbitol and glucose can be used. Of these, trifunctional or higher functional ones are particularly preferable.

[Isocyanate component]
Generally, the isocyanate component constituting the polyurethane foam is appropriately selected from the isocyanates used in the production of urethane by reacting with a polyol. Specific examples thereof include aromatic isocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate group-terminated prepolymers.

More specifically, as the isocyanate component for reacting with the polyol, diphenylmethane diisocyanate (4,4′-MDI), polymeric MDI (crude MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2 , 6-tolylene diisocyanate (2,6-TDI) and other aromatic isocyanates, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) and other aliphatic diisocyanates, isophorone diisocyanate, hydrogenated TDI, hydrogenated MDI and other alicyclics Examples thereof include group diisocyanates and isocyanate group-terminated prepolymers obtained by prepolymerizing these, and these can be used alone or in combination of two or more kinds. Among the above-mentioned compounds, the isocyanate component is preferably an isocyanate group-terminated prepolymer.

Examples of preferable isocyanate components include those containing an isocyanate group-terminated prepolymer described below and a modified MDI described below. The content ratio of the isocyanate group-terminated prepolymer and the modified MDI is 97.0 in terms of the ratio of the isocyanate group-terminated prepolymer to the modified MDI when the total amount of the isocyanate group-terminated prepolymer and the modified MDI described below is 100 parts by mass. It is preferably in the range of 3.0 to 80.0/20.0.

[Isocyanate group-terminated prepolymer]
As the isocyanate group-terminated prepolymer, it is preferable to use one having a number average molecular weight of 500 or more and 4000 or less, an average number of functional groups of 2 or more and 3 or less, and an isocyanate group content of 3% by mass or more and 10% by mass or less.

When the isocyanate group-terminated prepolymer has a number average molecular weight of more than 4000 and/or an isocyanate group content of less than 3% by mass, the obtained polyurethane foam is difficult to foam and becomes too hard, and has a viscosity. It is large and tends to be difficult to mix with other materials. When the isocyanate group-terminated prepolymer has a number average molecular weight of less than 500 and/or an isocyanate group content of more than 10% by mass, the resulting polyurethane foam tends to foam and becomes too soft, and the present invention There is a possibility that the impact resilience in the predetermined range specified in 1 may not be obtained.

[Modified MDI]
As the modified MDI, one having an isocyanate group content of 25% by mass or more and 33% by mass or less is preferably used. This is because such modified MDI is liquid at room temperature, so that the viscosity of the isocyanate component can be lowered.

If the modified MDI having an isocyanate group content of less than 25% by mass has a small effect of increasing the NCO group content when mixed with the isocyanate group-terminated prepolymer, the foamability is insufficient and a foam having an appropriate apparent density cannot be obtained. There is a risk. On the other hand, with modified MDI having an isocyanate group content of more than 33% by mass, the NCO group content can be increased with a very small amount, but since the amount of modified MDI becomes small, the viscosity of the isocyanate group-terminated prepolymer is reduced. Cannot be reduced, and the mixing property when reacting with the polyol component becomes poor.

Specific examples of the modified MDI that is liquid at room temperature include polymeric MDI (crude MDI), urethane modified MDI, urea modified MDI, allophanate modified MDI, biuret modified MDI, carbodiimide modified MDI, uretonimine modified MDI, and uretdione modified MDI. , Isocyanurate-modified MDI, and the like. In particular, from the viewpoint of easily obtaining a polyurethane foam having a good balance of apparent density, C hardness, and impact resilience, which is highly effective in reducing fatigue, polymeric MDI (crude MDI) or carbodiimide modified MDI is selected as the modified MDI. It is preferable.

[Foaming agent]
Water (ion-exchanged water) can be preferably used as the foaming agent. The amount of the foaming agent added to the polyurethane raw material composition is preferably 0.5 parts by mass or more and 3 parts by mass or less based on 100 parts by mass of the above-mentioned polyol component. If the amount added is less than 0.5 parts by mass, foaming will be insufficient and impact resilience will be exhibited, but impact absorption will be poor. When the amount added exceeds 3 parts by mass, the cells of the polyurethane foam obtained by over-foaming become rough and the inside thereof is liable to be broken, so that the foam state is inferior, and the impact resilience within a predetermined range may not be obtained.

[catalyst]
The catalyst is not particularly limited as long as it can be used for producing a polyurethane foam. Examples of catalysts that have been conventionally used include amine catalysts such as triethylenediamine and diethanolamine, and metal catalysts such as bismuth catalysts. The addition amount of the catalyst in the polyurethane raw material composition is preferably 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the above-mentioned polyol component.

[Foam stabilizer]
The foam stabilizer is not particularly limited as long as it can be used in urethane foam, but from the viewpoint of easily obtaining a repulsion elastic modulus in a predetermined range, the viscosity is 300 mPa·s (25° C.) or more and 2000 mPa·s (25 It is preferable to use a silicone-based compound having a temperature of ℃) or less. Examples of commercially available foam stabilizers include, but are not limited to, trade names SF2969, PRX607, SZ1671 manufactured by Toray Dow Corning Silicone Co., Ltd. When the viscosity of the silicone-based compound used as the foam stabilizer is less than 300 mPa·s (25° C.), the foam stabilizing effect is weak and the cells become coarse, and it is difficult to obtain a high impact resilience. On the other hand, when the viscosity exceeds 2000 mPa·s (25°C), it becomes difficult to uniformly disperse in the polyurethane raw material, the cell size of the obtained foam is not uniform, and the physical properties locally change (measurement Physical properties change depending on the location). Considering these points, the viscosity of the silicone compound used as the foam stabilizer is more preferably 600 mPa·s (25°C) or more and 1000 mPa·s (25°C) or less. The viscosity of the silicone compound is a value measured by a B-type rotational viscometer.

The addition amount of the silicone compound added as a foam stabilizer is preferably 0.5 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the above-mentioned polyol component. When the amount of the silicone compound added is less than 0.5 parts by mass, the foam-stabilizing action is weak, the resulting polyurethane foam has a repulsion elastic modulus lower than a predetermined range, and the fatigue-reducing effect may not be sufficiently exhibited. If the amount of the silicone compound added exceeds 9 parts by mass, not only the resulting polyurethane foam tends to be inferior in impact resilience, but also the foam stabilizer may bleed out from the foam surface.

[Other additives]
In addition to the polyol component, the isocyanate component, the foaming agent, the catalyst, and the foam stabilizer, the polyurethane raw material composition for producing the polyurethane foam of the present invention may further contain other additives, if necessary. Good. Other additives include plasticizers, fillers, antioxidants, defoamers, compatibilizers, colorants, stabilizers, ultraviolet absorbers, and other additives generally used in the production of polyurethane foams. be able to. The addition amount of other additives may be appropriately selected within a range that does not impair the effects of the present invention.

[Molding of urethane layer]
The urethane layer 10 is preferably formed from a polyurethane foam having a desired shape obtained by reacting the above-mentioned polyurethane raw material composition by molding. Molding is a method in which the polyurethane raw material (stock solution) is injected into a mold (molding die), foamed and cured in the mold, and then demolded to obtain a foam.

The apparent density of the polyurethane foam can be adjusted, for example, by the injection amount of the polyurethane raw material composition injected into a mold having a predetermined shape.

(Protective layer)
The protective layer 20 may be any layer that can be laminated on and fixed to the urethane layer 10. For example, the protective layer 20 may be a vinyl chloride sheet or the like. The protective layer 20 is provided for an appropriate purpose such as protecting the urethane layer 10, improving the appearance, or improving the feel of the sole.

The thickness of the protective layer 20 is not particularly limited and can be appropriately determined without departing from the spirit of the present invention. For example, the protective layer 20 made of vinyl chloride can be adjusted within a range of 0.1 mm or more and 3.0 mm or less. Further, the thickness of the protective layer 20 is preferably smaller than the thickness of the urethane layer 10.

<Second embodiment>
The floor mat 200 according to the second embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a perspective view of the floor mat 200.
The floor mat 200 according to the present embodiment includes only the urethane layer 12.

As shown in FIG. 2, a plurality of protrusions 30 are formed on the surface of the urethane layer 12. The convex portion 30 appears on the upper surface of the floor mat 200, and forms unevenness on the upper surface of the floor mat 200. The floor mat 200 (urethane layer 12) according to the present embodiment includes a substrate surface 32 that forms a substantially flat surface on the upper surface, and a convex portion 30 that projects upward from the substrate surface 32. The protrusions 30 according to the present embodiment are provided on the upper surface of the urethane layer 12 substantially continuously over the entire surface in a regular manner, and when the user walks on the floor mat 200, the protrusions are always formed on the soles of the feet. They are arranged so densely as to come into contact with each other. However, as a modification of the present embodiment, the convex portions 30 may be irregularly provided on the upper surface of the urethane layer 12.

The floor mat 200 in which the plurality of convex portions 30 are provided on the surface of the urethane layer 12 as in the present embodiment exerts an anti-slip effect on the sole of the user's foot, and the foot on the leg of the user during operation. It can suppress the contraction of muscles that occur due to resisting the slipping of the back. Further, the convex portion 30 can give acupuncture to the acupoints on the soles of the user, and it is expected that fatigue recovery of the soles of the feet is achieved.

The height of the convex portion 30 is not particularly limited, but from the viewpoint of exerting the above-mentioned anti-slip effect and fatigue recovery effect without giving discomfort to the sole of the user, for example, 2 mm or more and 6 mm or less. Is preferred.
Here, the height of the convex portion 30 refers to the distance from the apex 34 of the convex portion 30 to the lower end of the convex portion 30 (the substrate surface 32 in the present embodiment). When the heights of the plurality of convex portions 30 are not uniform, the individual heights of the randomly selected ten convex portions 30 are actually measured, and the value obtained by arithmetically averaging the heights is used as the convex portion 30. Can be the height of.

The thickness of the urethane layer 12 provided with the convex portion 30 is as follows. That is, when the total area of the protrusions 30 in the top view is larger than the total area of the substrate surface 32, the arithmetic mean value of the thicknesses actually measured at the respective apexes 34 of the 10 randomly selected protrusions 30. Is the thickness of the urethane layer 12. On the other hand, when the total area of the convex portions 30 is smaller than the total area of the substrate surface 32, the urethane layer 12 is obtained by calculating the arithmetic average value of the thickness measured at each of the 10 randomly selected substrate surfaces 32. Thickness.

Although the embodiment of the floor mat of the present invention has been described above, the floor mat of the present invention is not limited to the above description, and a part of the configuration is appropriately included without departing from the spirit of the present invention. Can be changed. For example, the floor mat can be composed of only the urethane layer 10 having a flat surface shown in the first embodiment, or the upper surface of the urethane layer 12 having the convex portion 30 on the surface shown in the second embodiment is further protected. The layers may be laminated. In this case, the convex shape of the convex portion 30 may be visually recognized on the surface of the laminated protective layer, or the protective layer has a hardness lower than that of the urethane layer 10, and the protective layer may be applied to the sole from the top of the protective layer. It may be configured so that the feel of the convex portion 30 is transmitted.

<Third embodiment>
As a third embodiment of the present invention, a leg fatigue evaluation method of the present invention (hereinafter, also simply referred to as an evaluation method of the present invention) will be described below. In the following description, FIG. 3 is used as appropriate. FIG. 3 is an explanatory diagram for explaining the evaluation method of the present invention, and shows a state in which the tester 300 repeats the first posture (left side of the drawing) and the second posture (right side of the drawing).
In the present embodiment, a floor mat 120 composed of only the urethane layer 10 used in the floor mat 100 described in the above-described first embodiment will be described as an example of the floor mat to be evaluated. However, the evaluation method of the present invention is not limited to this, and can be applied to the evaluation of the floor mat of the present invention in another aspect or a floor mat other than the floor mat of the present invention.

The evaluation method of the present invention is to attach a myoelectric potential measurement terminal capable of measuring a myoelectric potential of a muscle at a position where a predetermined muscle is located on the skin surface of the leg of the examiner 300, and in that state, the examiner 300 stands up on the floor mat 120 placed on the floor surface 150, repeats a predetermined operation for a predetermined time, and measures the myoelectric potential of the muscle over time within the predetermined time. Then, a regression line is obtained from the measured myoelectric potential value, and the degree of fatigue of the leg of the tester 300 is evaluated by the slope of the regression line.
According to the evaluation method of the present invention, regarding the floor mat for which the degree of fatigue reduction has been mainly evaluated by softness so far, the muscle fatigue of the leg of the tester operating on the floor mat is quantified. Thus, the degree of fatigue reduction of the floor mat can be objectively evaluated.

Recent studies show that myoelectric potential changes when muscle fatigue occurs. For example, when a myoelectric potential is detected by a change in frequency, it is known that the frequency tends to decrease as the muscle fatigue increases. Therefore, when the frequency of the muscle is measured over time during operation and a regression line is obtained from the measured values, a negative slope is usually shown. The present inventors have focused on this and completed the above-described evaluation method of the present invention. Here, the myoelectric potential means an action potential generated when the muscle contracts, and in particular, the action potential recorded from the surface of the skin is called a surface myopotential. In the following description, an evaluation mode in which the surface myoelectric potential is captured by frequency elements will be described as an example.

The evaluation method in this embodiment will be specifically described below. As shown in FIG. 3, a frequency at which the frequency of the muscle can be measured at a location on the skin surface of the furoragi 302, which is the leg of the tester 300, where a predetermined muscle (in this embodiment, the lateral gastrocnemius muscle) is located. The measurement terminal 320 is attached. Examples of the frequency measuring terminal 320 include an electrode that can measure the potential of the leg.
In the present embodiment, as a predetermined operation, the tester 300 lifts the heel to a first height t1 which is a height at which the heel does not touch the upper surface of the floor mat 120 and stands up, and the heel. The second posture of floating up to the second height t2, which is a position higher than the first height t1, is defined as an operation of repeating a predetermined number of times with a constant rhythm. In order to obtain evaluation stability, the first posture and the second posture may be defined in more detail. For example, a first posture of standing up on the floor mat 120 and floating the heel so that one or two fingers are inserted between the upper surface of the floor mat 120 and the heel (first height t1), and the first height. The second height t2 wider than t1 can be ensured and the second posture in which the back stretches to the extent that the muscle tension of the calf 302 is sufficiently felt can be repeated.

As described above, the present evaluation method objectively evaluates the influence of the floor mat 120 on muscular fatigue even by a simple motion of repeatedly raising and lowering the heel without moving in the plane on the upper surface of the floor mat 120. It is possible. By performing the evaluation with a simple operation, the stability of the evaluation result is easily obtained, and even when the evaluation method of the present invention is carried out by a plurality of testers, the evaluation conditions are easily unified.

The myoelectric potential measurement terminal (frequency measurement terminal 320 in the present embodiment) may be attached at any position on the leg, and a muscle site that significantly contracts in the operation performed in the evaluation may be selected. As described above, in the operation of raising and lowering the heel, the contraction of the lateral gastrocnemius muscle is remarkable, which is suitable for attaching the frequency measurement terminal 320.

In order to repeat the above-described first posture and second posture with a constant rhythm, it is preferable to use a metronome or the like to transmit a constant rhythm with a sound and let the tester 300 hear it.

In the present embodiment, the tester 300 wears shoes 310. Whether or not the shoes 310 are worn can be matched with whether or not the shoes 310 are worn by the user in an environment where the floor mat 120 is expected to be used.

The predetermined time for repeating the above-described predetermined operation is not particularly limited, and can be appropriately determined in consideration of the age and sex of the tester 300. For example, when the tester 300 is a woman in her twenties, the tendency of muscle fatigue can be achieved by repeating the first posture and the second posture for several minutes. The muscle potential (frequency) can be measured over time at predetermined intervals while repeating a predetermined operation. A regression line is obtained from the value of the electric potential (frequency) thus measured, and the degree of fatigue of the leg can be evaluated by the inclination thereof.

According to the research conducted by the present inventors, when the evaluation method of the present invention is carried out by a plurality of testers 300, it depends on the content of the operation, but there are variations in the frequency measured when a predetermined operation is repeated for a predetermined time. It has been found that may occur. In such a case, a more stable evaluation result can be obtained by adopting the following aspect.
That is, after performing an operation term in which the first posture and the second posture are repeated a predetermined number of times as a predetermined action, a break term that causes the tester 300 to take a break for a certain period of time is performed, and the above-mentioned motion term and the break term are set as one set. Finish the first set. Next, after the completion of the first set, at least one more test having the same contents as the first set is immediately carried out (that is, two or more sets are carried out). Then, the regression line is obtained from the myoelectric potentials measured in the second and subsequent sets. In the myoelectric potentials of the second and subsequent sets, the relationship between frequency and fatigue is more stable than in the first set of myoelectric potentials, and leg fatigue can be evaluated more objectively.

Examples 1 to 6 and Comparative Examples 1 and 2 were manufactured as follows.
A tetragonal mold having an inner chamber of 600 mm×900 mm×17 mm was prepared, and a polyol component, an isocyanate component, a catalyst, a foaming agent, and a foam stabilizer were stirred with a screw according to the composition shown in Table 1 to prepare a polyurethane raw material. A composition was prepared and poured into the mold while mixing. The injection amount of the polyurethane raw material composition into the mold was adjusted so that the apparent density of the formed polyurethane foam was a desired value. The rotation speed of the screw was set to 3000 rpm.
After the polyurethane raw material composition was injected into the mold, the polyurethane raw material composition was reacted under the condition of the mold temperature of 50°C. After the reaction, the mold was removed to obtain a polyurethane foam.

The polyol component, the isocyanate component, the catalyst, the foaming agent, and the foam stabilizer in Table 1 are as shown below. In addition, the unit of the numerical value showing the composition of the material in Table 1 is a mass part.
Polyol 1: Polytetramethylene ether glycol (trade name; PTMG2000, Mn=2000, manufactured by Mitsubishi Chemical Corporation)
Polyol 2: Polypropylene glycol (trade name; Actcor D-2000, Mn=2000, manufactured by Mitsui Chemicals, Inc.)
Amine catalyst: triethylenediamine (trade name; TEDA-L33, manufactured by Tosoh Corporation)
Foam stabilizer: Silicone compound (trade name; SZ1671, manufactured by Toray Dow Corning Silicone Co., Ltd., viscosity 900 mPa·s (25° C.))
Blowing agent: Ion-exchanged water Bismuth catalyst: Bismuth catalyst (trade name; Pcat 25, manufactured by Nippon Kagaku Sangyo Co., Ltd.)
Isocyanate 1: Isocyanate group-terminated prepolymer (number average molecular weight obtained by reacting PTMG with 4,4'-MDI 1000, average number of functional groups 2, isocyanate group content 8%)
Isocyanate 2: Carbodiimide modified MDI (average number of functional groups: 2, isocyanate group content: 29%)

Comparative Examples 3-4 were prepared as follows.
As Comparative Example 3, a commercially available polyvinyl chloride mat having a thickness of 8 mm (trade name; Zedlan Comfort King, manufactured by Ludlow Composites Corporation) was used.
As Comparative Example 4, a commercially available 17 mm-thick polyurethane foam mat (trade name: Sofmat D, manufactured by Achilles Co., Ltd.) was used.

The physical properties of Examples and Comparative Examples manufactured or prepared as described above were evaluated as follows.
The evaluation results are shown in Table 1. In addition, all evaluations other than compression set were performed at room temperature (23° C.±2° C.).

(Apparent density)
From each of the polyurethane foams of Examples and Comparative Examples, a rectangular test piece having a length of 15 mm, a width of 15 mm and a thickness of 10 mm was cut out to obtain a density measuring test piece. The apparent density (g/cm ³ ) was measured according to JIS K 7222 using the test piece for measuring density.
Further, a test having dimensions of 15 mm in length, 15 mm in width, and 10 mm in thickness was cut out from the polyvinyl chloride mat used in Comparative Example 3, and the apparent density (g/cm ³ ) was measured by the same method as described above.

(C hardness)
From each example and each comparative example, a square test piece having a length of 100 mm, a width of 100 mm and a thickness of 12.5 mm was cut out to obtain a hardness measuring test piece. The hardness of the polyurethane foam was measured using an Asker rubber hardness tester C type according to JIS K 7312 using the above-mentioned hardness measuring test piece.

(Rebound resilience)
A cylindrical test piece having a diameter of 29 mm and a thickness of 12.5 mm was cut out from each example and each comparative example to obtain a test piece for measuring the impact resilience. The impact resilience (%) was measured according to JIS K 6255 using the above-mentioned impact resilience measurement test piece.

(Maximum impact load)
From each example and each comparative example, a square test having a length of 100 mm, a width of 100 mm, and a thickness of 12.5 mm was cut out to obtain a test piece for measuring an impact load. The maximum impact load was measured by a drop impact test using the impact load measurement test piece. In the drop impact test, using a "dynatop GRC8200 (manufactured by Instron)", a cannonball-shaped weight W (made of iron, 5.1 kg) as shown in FIG. Then, it was carried out by specifying the maximum impact load (kN) when the test piece was made to collide.

(Compression set)
A cylindrical test piece having a diameter of 29 mm and a thickness of 12.5 mm was cut out from each example and each comparative example to obtain a test piece for measuring compression set. The compression set (%) was measured according to JIS K 6262 under the conditions of a compression rate of 25%, 40° C., and 24 hours using the above compression set test piece.

For Example 1, Example 4, Comparative Example 3, and Comparative Example 4 manufactured as described above, matte evaluation was performed as follows.

(Evaluation of hardness during daily operation)
A sheet having a length of 600 mm, a width of 900 mm, and a thickness of 17 mm obtained in each of the examples and each of the comparative examples was used as a test sheet. The test piece was used for hardness evaluation during daily operation. Using the hardness evaluation test piece during daily operation, the hardness during daily operation was evaluated according to the performance evaluation method of Non-Patent Document 1 described above. The weight to be dropped had a mass of 40 kg.

The hardness of each Example and each Comparative Example was evaluated as follows based on the measurement values measured by the evaluation during the daily operation.
⊚: The evaluation value in daily operation is 0.9 or more and 1.2 or less.
◯: The evaluation value in daily operation is 0.7 or more and less than 0.9.
Δ: The evaluation value in daily operation is 0.5 or more and less than 0.7.
X: The evaluation value during daily operation is less than 0.5.

(Leg fatigue reduction evaluation)
Using each example and comparative example, the leg fatigue reduction evaluation was performed as follows.
First, a sheet having a length of 600 mm, a width of 900 mm, and a thickness of 17 mm obtained in each of the examples and each of the comparative examples was used as a test sheet. As a myoelectric meter, a cordless myoelectric meter (MQ-Air, manufactured by Kissei Comtech Co., Ltd.) was prepared.
The testers were 10 randomly selected women in their early twenties. Each tester wore easy-to-wear clothes and safety shoes, and the cordless measuring terminal of the electromyographic instrument was attached to the lateral gastrocnemius muscle of the left leg. In that state, the tester repeated a predetermined operation on each test sheet under the following conditions.

The tester stood up with the heel on the upper surface of the test sheet in the center of the test sheet, and maintained the standing posture for 1 minute. After that, the first posture and the second posture were alternately repeated for 3 minutes as shown in FIG. The timing of raising and lowering the heel was signaled by the metronome. Specifically, the tester changed the first posture and the second posture every 2 seconds. During this operation, the first myoelectric potential measurement was performed.
After performing the above operation for 3 minutes, the tester sat on a chair installed beside the test sheet and rested for 45 minutes. After the break was completed, the operator stood up again in the center of the test sheet for 1 minute in the same manner as described above, and then repeatedly performed the operation for repeating the first posture and the second posture for 3 minutes in the same manner as described above. During this operation, the second myoelectric potential measurement was performed.

Frequency components were analyzed from the first and second myoelectric potential measurement values measured as described above, and plotted on a graph in which the vertical axis represents frequency (Hz) and the horizontal axis represents measurement time (seconds). Also, a regression line was obtained from the above-mentioned myoelectric potential measurement values measured over time by the least squares method. In addition, the recording software (VitalRecorder2, manufactured by Kissei Comtech Co., Ltd.) and the analysis software (BIMUTASII, manufactured by Kissei Comtec Co., Ltd.) were used for recording and analyzing the myoelectric potential data.

Incidentally, in all the test sheets, the frequency values obtained from the first measurement had large variations, and therefore a graph showing the second measurement results is shown in FIG. 5a is a graph showing the result of myoelectric potential measurement when using the test sheet produced from Example 1, and FIG. 5b is a graph showing the result of myoelectric potential measurement when using the test sheet produced from Example 4. 5c is a graph showing the results of myoelectric potential measurement when using the test sheet prepared from Comparative Example 3, and FIG. 5d is a graph showing the result obtained using the test sheet prepared from Comparative Example 4. 3 is a graph showing the results of measurement of myoelectric potential of the above. All plotted values are the arithmetic mean of the measurements of 10 testers. Table 1 shows the slope of the regression line obtained from the second myoelectric potential measurement of each test sheet and the fatigue reduction evaluation evaluated from the slope as follows.

◯: The slope of the regression line is −0.05 or more and 0.05 or less.
Δ: The slope of the regression line is −0.07 or more and less than −0.05.
X: The slope of the regression line is less than -0.07.

The results of the hardness evaluations of Examples 1 and 4 and Comparative Examples 3 and 4 during daily operation were all ○ or ◎. However, it was confirmed that in Examples 1 and 4, the absolute value of the negative slope of the regression line obtained from the myoelectric potential measurement was smaller and the degree of fatigue was smaller than in Comparative Examples 3 and 4. That is, the fatigue reduction evaluations of Examples 1 and 4 were significantly good.
All Examples including Examples 1 and 4 showed appropriate C hardness and impact resilience, and were confirmed to be suitable as floor mats.

The above embodiment includes the following technical ideas.
(1) Having a urethane layer made of polyurethane foam,
The polyurethane foam is
The apparent density is 0.25 g/cm ³ or more and 0.60 g/cm ³ or less,
A floor mat having a C hardness of 40 or more and 70 or less and a rebound resilience of 40% or more and 80% or less.
(2) The floor mat according to (1), wherein the polyurethane foam has a maximum impact load of 0.6 kN or more and 1.2 kN or less.
(3) The floor mat according to (1) or (2) above, wherein the polyurethane foam contains polytetramethylene ether glycol as a polyol.
(4) The floor mat according to (1) or (2) above, wherein the polyurethane foam contains polypropylene glycol as a polyol.
(5) The floor mat according to any one of (1) to (4) above, wherein a plurality of convex portions are provided on the surface of the urethane layer.
(6) A myoelectric potential measurement terminal capable of measuring myoelectric potential of the muscle is attached to a place where a predetermined muscle is located on the skin surface of the leg of the tester,
The tester stands up on the floor mat placed on the floor, repeats a predetermined operation for a predetermined time,
Within the predetermined time, the myoelectric potential of the muscle is measured over time, and a regression line is obtained from the value of the measured myoelectric potential,
A leg fatigue evaluation method, characterized in that the degree of fatigue of the leg of the tester is evaluated by the slope of the regression line.
(7) The muscle is the gastrocnemius muscle located in the calf,
The predetermined operation, the tester, the first posture to float up the heel to a first height that is a height that does not touch the upper surface of the floor mat, and the heel than the first height The leg fatigue evaluation method according to (6), which is an operation of repeating a second posture of floating to a second height, which is a high position, a predetermined number of times with a constant rhythm.
(8) After performing an action term in which the first posture and the second posture are repeated a predetermined number of times as the predetermined action, a break term that causes the tester to take a break for a certain period of time is carried out, and the motion term and the break term are set once. Then, the first set is finished, and after the first set is finished, at least one more test of the same content as the first set is promptly carried out,
The leg fatigue evaluation method according to (6) or (7) above, wherein the regression line is obtained from the value of the myoelectric potential measured in the second and subsequent sets.

10, 12... Urethane layer 20... Protective layer 30... Convex portion 32... Substrate surface 34... Apex 100, 120, 200... Floor mat 150... Floor surface 300... ..Tester 302...calf 310...shoes 320...frequency measurement terminal t1...first height t2...second height W...weight

Claims (8)

Having a urethane layer made of polyurethane foam,
The polyurethane foam is
The apparent density is 0.25 g/cm ³ or more and 0.60 g/cm ³ or less,
A floor mat having a C hardness of 40 or more and 70 or less and a rebound resilience of 40% or more and 80% or less. The floor mat according to claim 1, wherein the maximum impact load of the polyurethane foam is 0.6 kN or more and 1.2 kN or less. The floor mat according to claim 1 or 2, wherein the polyurethane foam contains polytetramethylene ether glycol as a polyol. The floor mat according to claim 1, wherein the polyurethane foam contains polypropylene glycol as a polyol. The floor mat according to any one of claims 1 to 4, wherein a plurality of convex portions are provided on a surface of the urethane layer. At the place where the predetermined muscle is located on the skin surface of the leg of the tester, a myoelectric potential measurement terminal capable of measuring the myoelectric potential of the muscle is attached,
The tester stands up on the floor mat placed on the floor, repeats a predetermined operation for a predetermined time,
Within the predetermined time, the myoelectric potential of the muscle is measured over time, and a regression line is obtained from the value of the measured myoelectric potential,
A leg fatigue evaluation method, characterized in that the degree of fatigue of the leg of the tester is evaluated by the slope of the regression line. The muscle is the gastrocnemius muscle located in the calf,
The predetermined operation, the tester, the first posture to float up the heel to a first height that is a height that does not touch the upper surface of the floor mat, and the heel than the first height The leg fatigue evaluation method according to claim 6, which is an operation of repeating a second posture of floating up to a second height, which is a high position, a predetermined number of times with a constant rhythm. After performing an action term that repeats the first posture and the second posture a predetermined number of times as the predetermined action, a break term that causes the tester to take a break for a certain period of time is performed, and the motion term and the break term are set as one set. One set is completed, and immediately after the first set is completed, at least one more test having the same contents as the first set is carried out,
The leg fatigue evaluation method according to claim 6 or 7, wherein the regression line is obtained from the value of the myoelectric potential measured after the second set.

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