JP2000170360A - Core material for synthetic thin tatami mat, base for synthetic thin tatami mat and synthetic thin tatami mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core material for synthetic thin Tatami mat, a base for synthetic thin Tatami mat and a synthetic thin Tatami mat which are capable of preventing deformation such as warping arising from largeness in coefficient of linear expansion of polypropylene resin foam from occurring to a thin Tatami mat after being laid while maintaining strength, flexibility and lightness in weight almost as they are. SOLUTION: For a core material for synthetic thin Tatami mat having a synthetic resin foam layer and in the entire thickness of more than 8 mm and less than 30 mm, the foam layer has a PP foam layer 1 comprising a polypropylene resin foam in an expansion ratio of more than 1.1 times and less than 10 times and stress relaxation parts 2a and 2b are provided for relaxing the stress produced by thermal expansion at the PP foam layer 1 with the thickness of the PP foam layer 1 partially reduced, or a restriction face material for restricting the thermal expansion at the PP foam layer 1 being united in lamination together with the PP foam layer 1 is provided, or a displacement absorbing part which absorbs deformation arising from the thermal expansion at the PP foam layer 1 and reduces transmission of stress to edges of a Tatami mat is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core material for synthetic thin tatami mats, a tatami floor, and a synthetic thin tatami mat using the same, which has a synthetic resin foam layer and can be used in a sea or a barrier-free house.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for thin tatami mats having a thickness of less than 30 mm in Japanese-style flooring rooms, laying tatami mats in gymnasiums, and barrier-free dwellings corresponding to aging. When using the traditional tatami floor made of straw, insulation board, and styrofoam as they are, the strength and rigidity are not enough. There were problems such as difficulty in carrying.

In order to solve such problems, a thin tatami mat having improved strength and rigidity has been produced by laminating a material having high rigidity on one or both surfaces of the above-mentioned materials. But,
Since such a thin tatami mat has a hard feel, there are problems such as a poor sitting comfort and an uncomfortable feeling when walking.

[0004]

On the other hand, as another method for solving the above-mentioned problems, by reducing the expansion ratio of the synthetic resin foam used as the core material, the strength and strength are maintained while maintaining the flexibility to some extent. It is conceivable to improve the rigidity.
However, resin foam has a large linear expansion coefficient,
It has been found that when the tatami is cooled after construction (for example, in winter), there is a problem that a gap is left between tatami mats. Conversely, if the tatami is heated after construction (for example, in summer), the coefficient of linear expansion of the resin foam is large, and the elastic modulus also increases due to the decrease in the expansion ratio. ) And deformation such as swelling was found to occur. Specifically, the linear expansion coefficient of the polypropylene resin foam is a value of about 10 × 10 ⁻⁵ / ° C., and a thin tatami mat having a long side of about 1800 mm due to a temperature change of 30 ° C.
It was expected to expand and contract by about 5 mm, but it was found to expand and contract by about 5 mm as expected. Then, it is considered that the stress generated by this expansion is greatly deforming the thin tatami mat in combination with the thinness of the tatami mat, and is considered to be a barrier in constructing the thin tatami mat.

[0005] In view of the above situation, the present invention has a strength,
Synthetic core material for thin tatami mats that can suppress deformation such as warpage of thin tatami mats after construction due to the magnitude of linear expansion coefficient of polypropylene resin foam while maintaining flexibility and light weight almost. An object of the present invention is to provide a tatami mat floor and a tatami mat.

[0006]

The above objects can be achieved by the present invention as described below. The present invention includes the first to third inventions as means for solving the common problem.

That is, the synthetic tatami mat core material of the present invention (first invention) has a synthetic resin foam layer and has an overall thickness of 8 m.
m and less than 30 mm, the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 to 10 times, and the PP foam layer Is characterized in that a stress relieving portion for relieving stress generated by thermal expansion of the PP foam layer by partially reducing the thickness of the PP foam layer is provided. Here, the PP
The stress generated by the thermal expansion of the foam layer refers to the stress generated by the constraint of the end of the synthetic tatami mat or the thermal expansion limited by the layer laminated and integrated with the PP foam layer. This is a concept that includes the stress generated by

[0008] According to the above-mentioned stress relaxation portion, the PP foam layer existing in the vicinity of the space caused by partially reducing the thickness of the PP foam layer can partially and freely expand into the space. As a result, the generated stress can be reduced. In the vicinity of the thinned part, although some stress is transmitted to that part, the stress is absorbed by expansion into the space near the thinned part, and the overall stress is considerably reduced. become. Furthermore, by partially reducing the thickness of the PP foam layer, the weight of the synthetic thin tatami mat core can be reduced. As a result, a synthetic thin tatami that can suppress deformation such as warpage of the thin tatami after construction due to the magnitude of the linear expansion coefficient of the polypropylene resin foam while substantially maintaining strength, flexibility, and lightness. The core material can be provided.

By setting the expansion ratio of the foam layer to 1.1 times or more and 10 times or less, the mechanical strength, lightness, and flexibility become moderate. From this viewpoint, the expansion ratio is preferably 1. 5 times or more and 6 times or less. On the other hand, if the total thickness is less than 8 mm, the strength and rigidity are weakened, and it is not practical. If the total thickness is 30 mm or more, not only the function as a thin tatami mat is lost, but also the material cost is increased and it is not practical ( These points are the same in the second and third inventions).

[0010] In the above, the foam layer is formed by laminating two layers of the PP foam layer, and the stress relieving portion is provided with a plurality of slit grooves on each of opposing sides of the PP foam layer. It is preferable that the slit grooves opposed to each other are arranged so that the directions are substantially equal in both layers. By such a slit groove, the thickness portion of the PP foam layer corresponding to the depth,
Since it is possible to expand to some extent freely in the space of the slit groove, the generated stress can be reduced, and the stress to the remaining portion of the slit groove is transmitted near the bottom of the slit groove, but the overall stress is considerably large Will be eased. In addition, by facing the slit groove inside,
Since there is no slit groove on the surface, strength and rigidity against bending are increased, and transport for laying and laying the tatami surface becomes easy. Furthermore, since the upper and lower PP foam layers are mechanically substantially symmetrical, warpage to one side is less likely to occur.

As the stress relaxing portion, various forms are exemplified as described later. The stress relaxing portion is formed by providing a plurality of slit grooves substantially parallel to the short side or the long side of the composite thin tatami mat. Is preferred. With such a slit groove, while having the above-mentioned effect, since the slit groove is provided substantially parallel to the short side or the long side of the synthetic thin tatami,
The stress due to expansion substantially perpendicular to the short side or long side of the composite thin tatami can be efficiently relieved, and deformation such as warpage of the thin tatami can be efficiently suppressed. The slit groove is preferably provided substantially parallel to both the short side and the long side, but it is also possible to provide the slit groove in either one. In this case, it is preferable to provide the slit groove substantially parallel to the short side.

As the form of the slit groove, various forms are exemplified as described later. The depth of the slit groove is 40% or more and 90% or less of the thickness of the PP foamed resin layer, and is in the same direction. It is preferable that the total width of the slit grooves formed in the above is not less than 1% and not more than 40% of the length of the side in the direction perpendicular to the slit grooves. If the depth of the slit groove is less than 40%, the amount of relaxation of the stress by the space portion of the slit groove becomes small, and if it exceeds 90%, the overall strength tends to be insufficient. Also, if the total width of the slit grooves is less than 1%,
The amount of relaxation of the stress by the space of the slit groove is also small,
If it exceeds 40%, an unnecessarily large space portion is generated, and the overall strength tends to be insufficient.

The synthetic tatami mat core material of the present invention (the second invention)
It has a synthetic resin foam layer, and the overall thickness is 8 mm or more 3
In a synthetic tatami mat core material having a foaming ratio of less than 0 mm, the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 to 10 times, and is laminated with the PP foam layer. The present invention is characterized in that a constraining surface material that is integrated and restrains the thermal expansion of the PP foam layer is provided.

Since the PP foam layer has a large thermal expansion and a relatively high elastic modulus, it is apt to be deformed due to thermal expansion in combination with its thinness. Thermal expansion in the plane direction of the body layer can be restrained and reduced. As a result, a synthetic thin tatami that can suppress deformation such as warpage of the thin tatami after construction due to the magnitude of the linear expansion coefficient of the polypropylene resin foam while substantially maintaining strength, flexibility, and lightness. The core material can be provided.

In the above, the constraining surface material has a coefficient of linear expansion of 5 × 10 ⁻⁵ / ° C. or less and a tensile modulus of 500 M
It is preferably Pa or more. It is desirable that the constraining surface material has a small coefficient of linear expansion and a large tensile modulus of elasticity. However, by setting the numerical value in such a range, the above-described effects can be suitably achieved. From this perspective,
Preferably, the coefficient of linear expansion is 2 × 10 ⁻⁵ / ° C. or less,
The tensile modulus is 1000 MPa or more.

Examples of the restraining surface material include an insulation board, a veneer plate, an aluminum plate, a steel plate, a glass fiber reinforced resin plate, a glass fiber reinforced foamed resin plate, a perforated product thereof, and a steel mesh surface. The material is preferably at least one selected from the group consisting of a glass fiber, a high elasticity polyethylene fiber net, a woven fabric, and a nonwoven fabric. These are because the coefficient of linear expansion is small and the tensile modulus is large. Above all, an insulation board is most preferable in consideration of the cutting property of a kitchen knife as a tatami mat. Further, the thickness is preferably from 0.1 to 10 mm.

The synthetic thin mat core material of the present invention (third invention)
It has a synthetic resin foam layer, and the overall thickness is 8 mm or more 3
In the core material for synthetic thin tatami having a thickness of less than 0 mm, the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 to 10 times, and the heat of the PP foam layer is reduced. It is characterized in that a displacement absorbing portion for absorbing displacement due to expansion and reducing transmission of stress to the end of the tatami mat is provided. By providing such a displacement absorbing portion, it is possible to suppress the generation of stress by allowing the thermal expansion of the PP foam layer, and as a result, to reduce the transmission of stress to the end of the tatami mat. be able to. As a result, strength,
Provide a core material for synthetic thin tatami mats that can suppress deformation such as warpage of thin tatami mats after construction caused by the linear expansion coefficient of the polypropylene resin foam while maintaining flexibility and lightness almost We were able to.

[0018] It is preferable that the displacement absorbing portion is a soft material having an elastic modulus of 100 MPa or less provided at least at an end portion on the long side of the synthetic thin tatami mat core material. By using such a soft material having an elastic modulus of 100 MPa or less, PP
While appropriately absorbing the displacement due to the thermal expansion of the foam layer, the generation of stress due to its own displacement can be reduced, and as a result, the transmission of stress to the end of the tatami mat can be greatly reduced. From this viewpoint, the elastic modulus is preferably 50 MPa.
The following soft materials are used. In addition, since the displacement absorbing portion is provided at least at the end on the long side, it is difficult to reduce the strength and rigidity of the entire tatami, and it is hard to cause a partial discomfort when using the tatami.

In the first to third aspects of the present invention, the P
The P foam layer can be manufactured by various manufacturing methods as described below, and the structure of the obtained foam is slightly different, but it is preferable that the upper and lower surfaces have a skin layer having a lower expansion ratio than the inner layer portion. . With this configuration, the flexural modulus of the material is increased, so it is possible to prevent surface dents due to local loads and to efficiently distribute local loads without losing the flexibility of the tatami surface material, Permanent depression is less likely to occur. More specifically, foaming ratio of 1.
A layer less than 5 times and smaller than the expansion ratio of the substrate is 0.05 mm
It is preferable to have a thickness of not less than 1.0 mm.

In the first to third inventions, it is preferable that the respective layers are integrated by sewing or bonding.
With this configuration, it is possible to increase the rigidity of the composite thin tatami mat core material, to prevent warpage deformation due to a temperature change, and to prevent bending during transfer.

On the other hand, the tatami floor for synthetic thin tatami of the present invention is characterized in that a moisture absorbing and releasing paper or paperboard is provided on at least the front side of the tatami mat and the back side of the tatami mat of the first to third aspects. It has been arranged. With this configuration, in addition to the function and effect of the core material for synthetic thin tatami mats described above, it becomes possible to impart hygroscopicity to the core material for tatami mats made of an independent foamed resin having no water absorption, thereby giving a sticky feeling in actual use. Can be prevented.

Further, in the tatami floor for synthetic tatami mats of the present invention, a flame-retardant synthetic resin film or sheet is further provided on the outermost tatami surface of the core material for tatami mats of the first to third inventions. It is what is being done. According to this configuration, it is possible to make the thin tatami flame-retardant in addition to the function and effect of the core material for the synthetic thin tatami mat.

Further, the tatami floor for synthetic thin tatami of the present invention is provided with fire resistance, heat resistance or heat insulation on the most tatami front side of the synthetic thin tatami mat core material according to any one of the first to third inventions. A fire-preventive paint or a fire-resistant paint having a property is applied.
With this configuration, it is possible to make the thin tatami flame-retardant in addition to the function and effect of the above-mentioned core material for synthetic thin tatami mats.

Further, in the tatami floor for synthetic tatami mats of the present invention, a back sheet is further provided on the most rear side of the tatami mat of the core material for tatami mats of the first to third inventions. With this configuration,
In addition to the effect of the core material for the synthetic thin tatami mat, the sewing of the tatami mat surface can be facilitated, and the cosmetics, durability, and moisture proofness can be imparted.

In view of the above, it is preferable that the back sheet is a woven polypropylene sheet.

On the other hand, a synthetic tatami mat according to the present invention is characterized in that a tatami mat is provided on the tatami mat side closest to the tatami mat floor for synthetic tatami mat described above. With this configuration, the same operation and effect as those of the above-described cores for composite thin tatami and the tatami floor can be obtained. As a result, it was possible to provide a synthetic thin tatami mat capable of suppressing deformation such as warpage of the thin tatami mat after construction due to the linear expansion coefficient of the polypropylene resin foam.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in the order of the core material for synthetic thin tatami mat, the tatami floor for synthetic thin tatami mat, and the synthetic thin tatami mat according to the first to third inventions.

(First Embodiment of the Invention) The first embodiment of the present invention
The invention is characterized in that the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 times or more and 10 times or less, and partially reduces the thickness of the PP foam layer. Although a stress relaxation portion for relaxing stress generated by thermal expansion of the foam layer is provided, in the present embodiment, as shown in FIG. An example in which the stress relaxation portion is formed by providing a plurality of slit grooves 2a substantially parallel to the short side and a plurality of slit grooves 2b substantially parallel to the long side of the synthetic thin tatami mat. Show.

As long as the PP foam layer 1 is a polypropylene resin foam having an expansion ratio of 1.1 times or more and 10 times or less, any of a manufacturing method, an additive component, a foaming agent and the like may be used. Further, the polypropylene resin may include other mixed resin components, copolymer components, and the like as long as the resin contains polypropylene as a main resin component.

The method for producing a polypropylene resin foam is as follows:
Generally, mixing a pyrolysis type foaming agent and a polypropylene resin, kneading and homogenizing the resin and foaming gas while heating and melting the resin and decomposing the foaming agent with an extruder, suitable for foaming After cooling to the temperature, the resin is extruded from a die and foamed, then cooled and molded by a take-off machine, or a physical foaming agent is pressed into an extruder instead of a pyrolysis type foaming agent. The details thereof are disclosed in, for example, Japanese Patent Publication No. 58-31098. The expansion ratio can be adjusted by adjusting the type and amount of the foaming agent. In order to obtain a sheet having the above-mentioned skin layer, a method in which the upper and lower surfaces of a sheet extruded at a constant expansion ratio are heated and melted, and the sheet is formed by pressure bonding with a pressure roller may be used. Further, after the skin layer is formed in another step, the skin layer can be formed by laminating the foam layer by fusion or adhesion. In addition, the said polypropylene resin foam is used similarly in 2nd-3rd invention.

The depth of the slit groove 2a is about 60% of the thickness of the PP foamed resin layer 1, and since seven slit grooves having a width of 4 mm are provided, the total width is 28 mm.
This corresponds to about 1.6% of the length of the long side (1800 mm).
The slit groove 2 b has a depth of the PP foamed resin layer 1.
Is about 60% of the thickness, and three of those having a width of 4 mm are provided, so that the total width is 12 mm, which corresponds to about 1.3% of the length of the short side (900 mm).

The total width and depth of the slit grooves 2a and 2b are preferably in the above-mentioned ranges, but are not limited thereto, and the positions and directions of the slit grooves 2a and 2b are also limited to those shown in the drawings. Not something. As the groove shape,
For example, there are various shapes such as a shape widened toward the opening and a shape widened toward the bottom of the groove.

(Another Embodiment of the First Invention) (1) In the embodiment shown in FIG. 1, the core is constituted by only one PP foam layer 1, but the PP shown in FIG. It is preferable that the foam layer 1 is formed, and the surfaces provided with the slit grooves 2a and 2b are joined and integrated (see FIG. 2). In this case, in addition to the sewing, the joining and integrating method may employ a method of bonding the entire surface with an adhesive or an adhesive / adhesive tape or the like, or a method of joining and integrating by heat welding.

According to the above configuration, since no slit groove is present on the surface, the strength and rigidity against bending are increased, and the tatami mat is easily transported for sticking or laying.
In addition, since the upper and lower PP foam layers 1 are mechanically symmetric, warpage to one side is less likely to occur.

It is to be noted that a structure in which the surfaces on which the slit grooves 2a and 2b are not provided and joined and integrated is also effective for preventing warpage to one side. Slits 2a, 2b on both sides of a core material composed of
May be provided (see FIG. 3).

(2) In the embodiment shown in FIG. 1, an example is shown in which the stress relaxation portion is formed by providing the slit grooves 2a and 2b. However, the thickness of the PP foam layer is partially reduced. Any other shape may be used as long as the shape is determined. For example, the length of the slit groove is reduced so that it does not extend to the end of the core material, a rectangular parallelepiped concave portion 2c as shown in FIG. 4A, or a circle as shown in FIG. It can also be formed by providing the columnar recess 2d. The rectangular parallelepiped concave portion 2c and the columnar concave portion 2d are preferably arranged at the positions where the slit grooves 2a and 2b of the embodiment shown in FIG. 1 are provided, but may be uniformly provided on the entire surface of the PP foam layer 1. Good. Also, a PP provided with the concave portion 2c or the concave portion 2d
Also in the foam layer, similarly to the case where the slit groove is provided, it is preferable to stack the PP foam layers so that the concave portions of the PP foam layers face each other.

(3) In the embodiment shown in FIG.
Although a layer composed only of the PP foam layer 1 is illustrated, the slit groove forming surface of the PP foam layer 1 shown in FIG.
Another layer may be integrally laminated. In that case, examples of another layer include a PP foam layer and other synthetic resin foam layers.

(Embodiment of the Second Invention) The second embodiment of the present invention
The invention is characterized in that the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 to 10 times, and is laminated and integrated with the PP foam layer. Although a constraining surface member for restricting thermal expansion is provided, in this embodiment, as shown in FIG. 5, the foam layer is composed of two PP foam layers 1, and the entire surface therebetween. Fig. 1 shows an example in which a restraint surface member 3 made of an aluminum plate or the like is laminated and integrated.

According to the present embodiment, since the PP foam layer 1 is mechanically symmetrically laminated and integrated via the constraining face material 3, the warping stress generated by the restraint of the expansion by the constraining face material 3 cancels out. Warping is less likely to occur. Note that mechanically symmetric means that the stress generated on both sides of the constrained surface material 3 is due to substantially equal linear expansion coefficient × elastic modulus × second moment of area of each surface from the center line (plane). It means to balance.

Although the physical properties and materials of the constraining face material 3 are as described above, if the thickness of the constraining face material 3 is too small, the effect of restraining the thermal expansion of the PP foam layer becomes small, and the thickness is too large. Therefore, it is preferable to make the thickness appropriate. This thickness is determined by the tensile modulus of the constrained face material 3 and the PP.
It is almost determined by the total thickness of the foam layer 1,
When the total thickness of the foam layer 1 is about 20 mm, the tensile elastic modulus is about 2 to 10 mm when the elastic modulus is 500 to 1000 MPa, and when the elastic modulus is 1000 to 10,000 MPa,
About 5 mm and a tensile modulus of 10,000 MPa or more, preferably about 0.1 to 5 mm. The upper limit of each thickness is arbitrary in relation to the effect of restricting thermal expansion.

The bonding and integration in this embodiment can be performed by the same bonding and integration method as in the first embodiment of the present invention. However, a bonding method in which creep between surfaces is as small as possible is preferable. Adhesion with an agent and heat fusion are preferred. In addition, in order to manufacture the above-mentioned core material in a continuous process, using a restraining face material 3 that can be wound into a roll, in a post-process of manufacturing a PP foam,
There is a method of laminating and integrating while continuously applying an adhesive.

The sum of the thicknesses of the respective layers of the core material for synthetic thin tatami mats is not less than 8 mm and less than 30 mm, and is suitably used as a core material for so-called thin tatami mats.

(Another Embodiment of the Second Invention) (1) In the embodiment shown in FIG. 5, the core material is exemplified by two PP foam layers 1, but the PP foam layer 1
May be a single layer or three or more layers. However, in consideration of the warpage of the core material itself, it is preferable that the core material be composed of a plurality of layers and have a good mechanical balance.

In the case of three or more layers, each PP
It is preferable that the constraining face material 3 is laminated and integrated between the foam layers 1. In the case where the intermediate foam layer is composed of three or more layers, a foam layer other than the PP foam layer may be used, and a polystyrene resin foam, another synthetic resin foam, a straw material And a tatami substrate such as an insulation board. These synthetic resin foams can be produced by a generally known method for producing a resin foam, and various commercially available products can be used.

(2) In the embodiment shown in FIG. 5, an example is shown in which the constraining surface material 3 is laminated and integrated over the entire surface of the PP foam layer 1. However, it is necessary to restrict the thermal expansion of the PP foam layer. It is sufficient that the constraining surface material 3 has a sufficient area, and for the same reason,
Perforated insulation board, veneer board, aluminum board, steel board, glass fiber reinforced resin board, and glass fiber reinforced foamed resin board, perforated steel plate, and mesh of glass fiber and high elasticity polyethylene fiber , Woven fabric, non-woven fabric and the like can be used.

(Embodiment of the Third Invention) The third embodiment of the present invention
The invention is characterized in that the foam layer has a PP foam layer made of a polypropylene resin foam having an expansion ratio of 1.1 times or more and 10 times or less, and absorbs a displacement due to thermal expansion of the PP foam layer to form a fold end. Although it is characterized by having a displacement absorbing portion that reduces the transmission of stress to the portion, in the present embodiment,
As shown in FIG. 6, the foam layer is composed of two PP foam layers 1, and a flexible material made of a flexible polyurethane foam is provided as a displacement absorbing portion 4a at the long end 1a. Here is an example.

Since the soft material is adhered to the end 1a and can be easily deformed, for example, the right end of the displacement absorbing portion 4a is fixed, and the PP foam layer 1 is thermally expanded. Also, the rightward displacement can be absorbed and the transmission of stress to the right end can be reduced. In order to cause this effect, it is preferable that the member in contact with the surface of the PP foam layer 1 does not restrain the thermal expansion of the PP foam layer 1, and both can be displaced or the surface member can expand and contract. Should be fine. In order to generate the displacement properly,
It is preferable to use a nonwoven fabric in which the core material is displaced up and down, a surface paper that is not sewn, a plywood, and the like.

The width W of the displacement absorbing portion 4a depends on the type of the soft material, but is about 5 to 20 mm at each portion (total 10).
-40 mm), and the displacement absorbing portion 4a preferably has a thickness equivalent to that of the core material.

(Another Embodiment of Third Invention) (1) In the embodiment shown in FIG. 6, an example is shown in which a soft material made of a flexible polyurethane foam is used, but various soft rubbers, soft elastomers, soft resin foams, etc. May be used. Further, the shape of the soft material is not limited to a square pillar, but may be a cylinder, a hollow cylinder, a honeycomb, or the like.

(2) In the embodiment shown in FIG. 6, an example in which the displacement absorbing portion is formed only at the end portion on the long side is shown. However, the displacement absorbing portion may be provided on the short side. May be wound.

(3) In the embodiment shown in FIG. 6, an example is shown in which the displacement absorbing portion is formed of a soft material separate from the PP foam layer 1, but as shown in FIG. PP
At the end of the foam layer 1, a rectangular column-shaped concave portion 4b or a groove-shaped concave portion 4 is formed.
By forming c, the displacement absorbing portion may be configured. In other words, since the area of the remaining portion where the rectangular column-shaped concave portion 4b and the groove-shaped concave portion 4c are formed becomes small, the stress generated by the displacement becomes small. The transmission of stress to the tatami end can be reduced. In this way, by forming the displacement absorbing portion in the PP foam layer 1 itself, the manufacturing process can be simplified, the raw materials can be unified, and recycling can be facilitated.

The shapes of the recesses 4b and 4c are not particularly limited, and any shape may be used as long as the area of the remaining portion is small and the portion can be displaced to some extent.

As shown in FIG. 8A, the PP foam layer 1
May be divided into two or more portions, and a gap 4d may be provided between the portions to constitute a displacement absorbing portion. Thereby, the displacement of each part of the divided PP foam layer can be absorbed, and as a result, the transmission of stress to the tatami mat end can be reduced. In addition, in such a structure, each part of the divided PP foam layer may be partially connected to each other as shown in FIG. 8B.

On the other hand, the first invention, the second invention and the third invention
The invention can be appropriately combined.

For example, by combining the second invention and the third invention, as shown in the cross-sectional view of FIG. 9, the PP foam layer 1 is laminated on both sides of the restraint face material 3 (for example, an insulation board) and sewn. In each of the above structures, each PP foam layer is divided into two or more parts, and a gap 4 serving as a displacement absorbing part is provided between each part.
d may be formed.

(Synthetic Tatami Floor for Synthetic Thin Tatami and Synthetic Thin Tatami) The synthetic tatami floor for synthetic thin tatami of the present invention uses the synthetic tatami mat core material according to the first to third inventions, and further absorbs and absorbs moisture. It is obtained by laminating layers composed of paper or paperboard, a flame-retardant synthetic resin film or sheet, a fire-resistant paint or fire-resistant paint having fire resistance, heat resistance or heat insulation, a back sheet, and the like.

As the moisture absorbing / releasing paper, papers having air permeability and a relatively large surface area such as cardboard paper (for example, MF sheet manufactured by Marusan Paper Co., Ltd.) can be used. Water-permeable and moisture-permeable films, sheets and the like can be used.

Examples of the flame-retardant synthetic resin film or sheet include a film or sheet using a heat-resistant resin or a flame-retardant resin, or a synthetic resin film or a synthetic resin sheet to which a flame retardant is added. Is mentioned.

As the fire spread paint or fire resistant paint,
For example, "Fire spike system (product name)"
Fire-resistant paints manufactured by Highwood System Co., Ltd. and "SK Fire Resistant Coat (trade name)" manufactured by SK Kaken Co., Ltd. The same effect can be exerted by forming a coating film by applying and drying an aqueous solution in which clay mineral is finely dispersed in a water-soluble resin (such as polyvinyl alcohol) in the same manner.

Examples of the back sheet include a woven polypropylene sheet made of a polypropylene thread or a narrow polypropylene band.

On the other hand, the synthetic thin tatami mat of the present invention is provided with a tatami mat on the most tatami mat side of the tatami mat floor as described above. As the tatami mat, woven grass or the like with hemp yarn or the like made of synthetic resin such as polypropylene (synthetic rush) can be used.

Hereinafter, the structure of the tatami floor for synthetic thin tatami and the structure of the synthetic thin tatami of the present invention will be described with reference to the drawings. Note that the present embodiment is an example in which the core according to the second invention is used as the core material for synthetic thin tatami mats, and the core material C shown in FIG. 5 is used.

The tatami floor for synthetic thin tatami mats shown in FIG. 10 has a back sheet 11 made of polyolefin cloth laminated on the lower surface of the core material C shown in FIG. It is made by laminating a moisture absorbing / releasing paper 12 (or paperboard) and a flame-retardant sheet material layer 13 made of a flame-retardant synthetic resin sheet.

In this embodiment, the layers of the composite thin tatami floor are sewn to each other with sewing threads, and the tatami mat 14 is further sewn to the synthetic thin tatami floor. At that time, tatami table 1
As shown in FIG. 10, 4 is folded back to the back of the tatami mat so as to surround the end of the tatami floor for synthetic thin tatami mats, and is sewn at that portion. Notches are provided in the core material C and the back sheet 11 so that a step is not generated.

When forming a tatami floor for synthetic thin tatami mats in which moisture absorbing and desorbing paper is arranged on the back side of the core material C, the moisture absorbing and desorbing paper is interposed between the back sheet 11 and the core material C. Further, instead of the flame-retardant sheet material layer 13, a fire spread paint or a fire-resistant paint having fire resistance, heat resistance or heat insulation property may be applied to the underlying layer. In addition, other foam layers or other layers may be provided in the middle of each layer, and other foam layers or other layers may be provided on the front or back of the tatami mat unless the function of each layer is impaired. May be provided.

The composite tatami floor shown in FIG. 11 is an embodiment using the composite tatami mat core material according to the third invention, and the lower surface of the core material C shown in FIG. A face material 15 for enabling the core material C (particularly, the PP foam layer 1) to be displaced is laminated on the front side of the tatami mat. The tatami mat 14 is sewn to the front side of the tatami mat floor, but is sewn to the face material 15 to make it difficult to restrain the core material C from being displaced. Examples of the face material 15 include a nonwoven fabric, a surface paper, and a plywood, which are likely to be displaced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a core material for synthetic thin tatami of the first invention.

FIG. 2 is a front view showing another embodiment of the synthetic thin tatami mat core material of the first invention.

FIG. 3 is a front view showing another embodiment of the synthetic thin tatami mat core material of the first invention.

FIG. 4 is a perspective view showing a main part of another embodiment of the synthetic thin tatami mat core material of the first invention.

FIG. 5 is a front view showing an embodiment of the core material for synthetic thin tatami of the second invention.

FIG. 6 is a front view showing an embodiment of a core material for a synthetic thin tatami mat according to the third invention;

FIG. 7 is a perspective view showing a main part of another embodiment of the synthetic thin tatami mat core material of the third invention.

FIG. 8 is a perspective view showing a main part of another embodiment of the synthetic tatami mat core material of the third invention.

FIG. 9 is a cross-sectional view showing a main part of an embodiment of a synthetic thin tatami mat core material according to a combination of the second invention and the third invention.

FIG. 10 is a cross-sectional view showing an embodiment of a synthetic tatami floor and a synthetic tatami mat.

FIG. 11 is a cross-sectional view showing another embodiment of the synthetic tatami floor and the synthetic tatami mat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PP foam layer 2a, 2b Stress relaxation part 3 Constraining surface material 4a Displacement absorption part 11 Back sheet 12 Moisture absorbing / release paper 13 Flame retardant sheet material layer 14 Tatami table 15 Face material C core material

Claims (17)

[Claims] 1. A synthetic tatami mat core material having a synthetic resin foam layer and having a total thickness of 8 mm or more and less than 30 mm, wherein the foam layer has an expansion ratio of 1.1 to 10 times. A PP foam layer made of a polypropylene resin foam is provided, and a stress relieving portion is provided to partially reduce the thickness of the PP foam layer to relieve stress generated by thermal expansion of the PP foam layer. A core material for synthetic thin tatami mats. 2. The foam layer is formed by laminating two layers of the PP foam layer, and the stress relieving section has a plurality of slit grooves on each of opposite sides of the PP foam layer. 2. The synthetic thin tatami mat core material according to claim 1, wherein said slit grooves are formed by providing said slit grooves, and said slit grooves are arranged so that the directions thereof are substantially equal in both layers. 3. The core material for a synthetic thin tatami according to claim 1, wherein the stress relaxation portion is formed by providing a plurality of slit grooves substantially parallel to a short side or a long side of the synthetic thin tatami. 4. The depth of the slit groove is 40% or more and 90% or less of the thickness of the PP foamed resin layer, and the total width of the slit grooves formed in the same direction is perpendicular to the slit groove. The core material for a synthetic thin tatami mat according to claim 2 or 3, which is 1% or more and 40% or less of the length of the side. 5. A synthetic tatami mat core material having a synthetic resin foam layer and having an overall thickness of 8 mm or more and less than 30 mm, wherein the foam layer has an expansion ratio of 1.1 to 10 times. A synthetic thin tatami mat having a PP foam layer made of a polypropylene resin foam, and having a restraining face material laminated and integrated with the PP foam layer to restrain thermal expansion of the PP foam layer. Core material. 6. The restricted face material has a linear expansion coefficient of 5 × 10.
^The core material for a synthetic thin tatami according to claim 5, wherein the core material has a tensile modulus of not more than ^-5 / ° C and a tensile modulus of not less than 500 MPa. 7. The restraining surface material is an insulation board, a veneer plate, an aluminum plate, a steel plate, a glass fiber reinforced resin plate, a glass fiber reinforced foamed resin plate, a perforated product thereof, and a steel mesh. The core material for synthetic thin tatami according to claim 5 or 6, wherein the core material is at least one selected from the group consisting of a face material, a net of glass fiber and high elasticity polyethylene fiber, a woven fabric, and a nonwoven fabric. 8. A synthetic thin tatami mat core material having a synthetic resin foam layer and having an overall thickness of 8 mm or more and less than 30 mm, wherein the foam layer has an expansion ratio of 1.1 to 10 times. It has a PP foam layer made of a polypropylene resin foam, and is provided with a displacement absorbing portion that absorbs displacement due to thermal expansion of the PP foam layer and reduces transmission of stress to the end of the tatami mat. Core material for synthetic thin tatami. 9. An elastic modulus of 100 MPa, wherein the displacement absorbing portion is provided at least at an end portion on a long side of a synthetic thin tatami mat core material.
The core material for synthetic thin tatami according to claim 8, which is a soft material as described below. 10. The synthetic thin tatami mat core material according to claim 1, wherein the PP foam layer has skin layers on upper and lower surfaces. 11. The synthetic thin tatami mat core material according to claim 1, wherein each layer is integrated by sewing or adhesion. 12. A synthetic thin tatami mat according to any one of claims 1 to 11, wherein moisture absorbent paper or paperboard is arranged on at least the front side of the tatami mat and the back side of the tatami mat. Tatami floor. 13. A tatami mat for synthetic tatami mats, wherein a flame-retardant synthetic resin film or sheet is further provided on the front side of the tatami mat material according to any one of claims 1 to 11. floor. 14. A synthetic flame-retardant paint or fire-resistant paint having fire resistance, heat resistance or heat insulating property applied to the front side of the tatami mat of the synthetic thin tatami mat core material according to any one of claims 1 to 11. Tatami floor for thin tatami mats. 15. A tatami floor for synthetic tatami mats, wherein a back sheet is further provided on the most rear side of the tatami mat of the core material for tatami mat according to any one of claims 1 to 11. 16. The tatami floor according to claim 15, wherein the back sheet is a woven polypropylene sheet. 17. A synthetic thin tatami mat, wherein a tatami mat is provided at the most tatami mat side of the tatami mat floor according to any one of claims 12 to 16.