Hard flooring

Abstract

To provide a resin flooring material that is less prone to conforming to uneven surfaces and has excellent dimensional stability. [Solution] A hard flooring material comprising a resin-containing hard layer and a transparent resin layer above it, and a back resin layer below the resin-containing hard layer, characterized in that (1) the resin-containing hard layer contains at least a resin component and an inorganic filler, (2) the resin component content in the resin-containing hard layer is 35% by weight or less, (3) the plasticizer content in the resin-containing hard layer is less than 1% by weight, and (4) the inorganic filler content in the resin-containing hard layer is 65% by weight or more.

Description

Technical Field

[0001] The present invention relates to a novel rigid flooring material.

Background Art

[0002] As residential flooring materials, for example, wooden flooring, resin flooring, carpets, tatami mats, etc. are used in living spaces such as living rooms, kitchens, corridors, etc. according to the space. Among these, resin flooring materials are widely used as flooring materials for various living spaces because they are excellent in cushioning, flexibility, water resistance, etc., easy to maintain, and have a rich variety of designs (for example, Patent Documents 1 to 3).

[0003] However, due to its flexibility, the resin flooring material may follow unevenness of the floor base, etc., and the entire floor surface may exhibit a wavy appearance. At the same time, because it is flexible, it tends to be easily dented, and in some cases, dent marks may remain. It is more desirable in terms of appearance to have less unevenness and dents and form a flatter floor surface.

[0004] In contrast, the applicant of the present application has developed a novel rigid flooring material in order to solve the above problems and has reached the stage of filing a patent application (Patent Document 4). This rigid flooring material is a flooring material that is hard but has a slight creaking sound, so it is difficult to follow unevenness of the floor base, etc., can form a flatter floor surface, and can obtain a high aesthetic appearance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0006] On the other hand, from the perspective of partial replacement of flooring, replacement of flooring during renovation, re-laying flooring for positioning during construction, and removal of only flooring for recycling during building demolition, there is a growing trend to use adhesives that allow for non-destructive attachment and detachment of flooring materials to the subfloor, rather than adhesives, when installing flooring materials to the subfloor. When installing such hard flooring materials, if it becomes difficult to follow the unevenness of the subfloor, there is room for further improvement when using adhesives to attach the flooring to the subfloor.

[0007] In this regard, the inventors have found through their many years of research and experience that problems arise when using adhesives for installation. Specifically, when hard flooring materials like those described above are attached to a subfloor with an adhesive, the hard flooring material expands or contracts over time, and the adhesive becomes unable to withstand this expansion or contraction force, resulting in problems such as the flooring material lifting or shifting. This phenomenon is particularly due to the fact that adhesives have a weaker fixing force compared to glues.

[0008] In response to this, one possible method to suppress expansion or contraction is to introduce a shape-stabilizing layer containing glass nonwoven fabric or the like into the layer structure of the flooring material. However, this not only increases material and manufacturing costs, but the glass fibers contained in the shape-stabilizing layer also hinder the recycling of the flooring material. For this reason, there is a demand to avoid using this type of shape-stabilizing layer as much as possible. Furthermore, even if a shape-stabilizing layer is used, dimensional changes tend to increase as the total thickness of the flooring material decreases, so in this respect as well, it is necessary to further improve dimensional stability.

[0009] Therefore, the present invention has been made to solve the above-mentioned problems, and its main objective is to provide a resin flooring material that is less prone to conforming to uneven surfaces and has excellent dimensional stability. [Means for solving the problem]

[0010] In view of the problems of the prior art, the inventors conducted extensive research and, as a result, discovered that a resin flooring material containing a layer having a specific composition can achieve the above objective, thus completing the present invention.

[0011] In other words, the present invention relates to the following hard flooring material. 1. A flooring material comprising a resin-containing hard layer and a transparent resin layer above it, and a back resin layer below the resin-containing hard layer, (1) The resin-containing hard layer comprises at least a resin component and an inorganic filler, (2) The resin component content in the resin-containing hard layer is 35% by weight or less, (3) The plasticizer content in the resin-containing hard layer is less than 1% by weight, (4) The inorganic filler content in the resin-containing hard layer is 65% by weight or more. A hard flooring material characterized by the following features. 2. The hard flooring material according to item 1, wherein the resin-containing hard layer contains a vinyl chloride resin. 3. A hard flooring material as described in item 1 above, with a total thickness of 2.5 mm or less. 4. The hard flooring material described in item 1, which does not include a shape-stabilizing layer containing inorganic fibers. 5. The rigid flooring material according to item 1, wherein the transparent resin layer contains a vinyl chloride resin containing 13% by weight or more of a plasticizer. 6. A floor structure in which the hard flooring material described in any one of paragraphs 1 to 5 above is attached to the subfloor using at least one of an adhesive, adsorbent, or adhesive tape that allows the hard flooring material to be attached to the subfloor. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a resin flooring material that is less prone to conforming to uneven surfaces and has excellent dimensional stability.

[0013] Particularly, since the resin-containing rigid layer serving as the core material of the rigid floor covering of the present invention is controlled to have a specific resin component content and plasticizer content, a floor covering having desired hardness and dimensional stability can be obtained without relying on a shape stabilizing layer containing inorganic fibers. For this reason, construction using an adhesive or an adhesive tape becomes easier. Further, instead of an adhesive, a so-called "adsorbent" that is easier to attach and detach can be used, but in the present invention, an adhesive that provides a relatively strong bond to the floor surface can be preferably used.

[0014] Since the dimensional change over time of the rigid floor covering of the present invention is effectively suppressed, even if the floor covering is attached by an adhesive, an adsorbent or an adhesive tape during construction, abnormalities on the floor surface due to the dimensional change can be prevented in advance. At the same time, when it is constructed with an adhesive, an adsorbent or an adhesive tape, due to the slight "flexibility" of the floor covering and the ease of detachment, reattachment, replacement, etc. of the floor covering can be easily performed in a relatively short time. As a result, it can contribute to reduction of construction costs, shortening of the construction period, etc.

[0015] Further, since the rigid floor covering of the present invention has a desired hardness, even if there are irregularities (concave portions) etc. on the floor base, it can span them without following them. Thereby, a floor surface having a flatter appearance rather than a wavy appearance can be formed.

[0016] Such a rigid floor covering can be used as various floor coverings, and can be particularly preferably used as a floor covering for housing.

Brief Description of Drawings

[0017] [Figure 1] It is a diagram showing the basic layer configuration of the rigid floor covering of the present invention. [Figure 2] It is a diagram showing an example of a layer configuration according to an embodiment of the rigid floor covering of the present invention. [Figure 3] It is a diagram showing a state in which chamfered portions (tapered portions) are formed at the upper corner portions on the four sides of the rigid floor covering (rectangular tile) of the present invention. [Figure 4]This is a schematic diagram showing the sample placed in the apparatus to measure the amount of drooping in Test Example 1. [Figure 5] Figure 5A shows the state before the weight is placed. Figure 5B shows the state as seen from direction A (with weight 72 placed) in Figure 4A. [Figure 6] This figure shows an example of the planar shape of the flooring material of the present invention. [Modes for carrying out the invention]

[0018] 1. Hard flooring The flooring material of the present invention (the flooring material of the present invention) is a flooring material comprising a resin-containing hard layer and a transparent resin layer above it, and a back resin layer below the resin-containing hard layer, (1) The resin-containing hard layer comprises at least a resin component and an inorganic filler, (2) The resin component content in the resin-containing hard layer is 35% by weight or less, (3) The plasticizer content in the resin-containing hard layer is less than 1% by weight, (4) The inorganic filler content in the resin-containing hard layer is 65% by weight or more. It is characterized by the following:

[0019] 1) Basic configuration of the flooring material of the present invention The basic structure of the flooring material of the present invention will now be described. Figure 1 shows the basic layer structure of the flooring material of the present invention. In the flooring material 10 of the present invention, a transparent resin layer 12 is laminated on top of a resin-containing hard layer 11, and a back surface resin layer 13 is laminated on the opposite side of the resin-containing hard layer 11.

[0020] In Figure 1, a transparent resin layer 12 is formed in direct contact with the resin-containing hard layer 11, and a back resin layer 13 is formed on the opposite side of the resin-containing hard layer 11. However, other layers may be formed as long as the transparent resin layer 12 is positioned above the resin-containing hard layer 11 and the back resin layer 13 is laminated on the back surface of the resin-containing hard layer 11. Therefore, for example, a layer configuration like that shown in Figure 2 is also included as an embodiment of the present invention. In Figure 2, the flooring material 10 of the present invention is a laminate in which a back resin layer 13, a resin-containing hard layer 11, a printed layer 14, a transparent resin layer 12, and a protective layer 15 are formed in that order from bottom to top.

[0021] The planar shape of the flooring material of the present invention can be, for example, a square, rectangle, rhombus, or other rectangular shape. The size of the flooring material of the present invention can also be changed according to, for example, the installation location, the desired design, etc. For example, if it is rectangular, it can be appropriately set within the range of approximately 30 to 100 cm in length and 30 to 100 cm in width, but is not limited to this. For example, as shown in Figure 6, a roughly rectangular flooring material 1 in which the length in the first direction is L1 and the length in the second direction is L2 is generally difficult to remove in conventional installations. In contrast, even if the flooring material of the present invention has a planar shape as shown in Figure 6, it can be installed by attaching it with an adhesive, adsorbent, etc. Combined with the slight "flexibility" of the flooring material, the attachment and detachment of the flooring material becomes easy. As a result, if either end of the first direction is lifted, the detachment point advances significantly in the first direction, so even such a roughly rectangular shape can be easily removed from the floor surface.

[0022] In particular, the flooring material of the present invention is a sheet-like shape with a roughly rectangular shape in plan view, as described above, for example, the ratio L1:L2 of the length in the first direction to the length in the second direction is 1:1 to 10:1, preferably 1:1 to 8:1. By adopting such a ratio, when one end in the first direction (longitudinal direction) is lifted, the flooring material of the present invention flexes and braces appropriately, making it easier to remove from the floor surface. In particular, the effective size is in the range of 300mm to 1200mm × 100mm to 500mm, preferably around 400 to 1000mm × 150 to 500mm, with the length in the first direction L1 × length in the second direction L2 being.

[0023] 2) Physical properties of the flooring material of the present invention 2-1) Drooping amount In the flooring material of the present invention, at a temperature of 23°C, when a region B measuring 5 cm wide and 10 cm long is fixed from the edge of a rectangular sample measuring 5 cm wide and 30 cm long in the flooring material, the amount of sagging due to the self-weight of the remaining region A measuring 5 cm wide and 20 cm long is preferably 0.5 to 8 mm, more preferably 1 to 5 mm, and most preferably 2 to 4 mm.

[0024] In this invention, the amount of sag serves as an indicator of the flexibility (flexibility) of the flooring material. Within the above range, even if there are irregularities in the substrate, the flooring material can gently bend into an arc while maintaining the smoothness of the surface, preventing it from following the irregularities. Furthermore, the flexibility of the flooring material contributes to shortening the construction time and makes it easier to correct the position during construction, thus improving the accuracy of the construction. In the flooring material of this invention, if the amount of sag is less than 0.5 mm, it becomes difficult to bend into an arc, and depending on the layer structure, the edges may lift or the flooring material itself may become wobbly due to irregularities, protrusions, or unevenness in the substrate, and the difference in height at the joints between flooring materials may become noticeable. This phenomenon is particularly pronounced in the case of small flooring materials such as tile flooring. On the other hand, with the flooring material of the present invention, if the amount of sagging exceeds 8 mm, depending on the layer structure, it may not be able to cross over small unevenness, depressions, or protrusions in the substrate, and there is a risk that unevenness or irregularities will become visible on the surface of the flooring material as it follows the unevenness or irregularities.

[0025] Furthermore, when the temperature is 35°C, the amount of drooping is usually preferably around 2 to 10 mm, and more preferably 2 to 6 mm. By controlling it within this range, the same effect as that achieved by controlling the amount of drooping at 23°C can be obtained even in relatively high-temperature environments.

[0026] 2-2) Hardness The surface hardness of the flooring material of the present invention is not limited, but preferably the indentation value (Japanese Industrial Standard JIS A1454) measured by a MacBurney indentation tester against the transparent resin layer at 23°C is 0.2 mm or less, and more preferably 0.15 mm or less. By setting such a relatively small indentation value, an appropriate surface hardness can be obtained, resulting in the construction of a floor surface that can sufficiently withstand high pressure caused by localized loads such as those applied by casters. The lower limit of the indentation value can be, for example, about 0.05 mm, but is not limited thereto.

[0027] Furthermore, when the temperature condition is 45°C, the above-mentioned indentation value is usually preferably around 0.5 mm or less, and more preferably between 0.05 and 0.45 mm. By controlling it within this range, the same effect as that achieved by controlling the indentation value at 23°C can be obtained even in relatively high-temperature environments.

[0028] The amount of residual indentation on the surface of the flooring material of the present invention is not particularly limited, but is usually 0.05 mm or less, and preferably in the range of 0.03 mm or less. This makes it possible to provide a durable flooring material even if it is relatively thin.

[0029] 2-3) Thickness The total thickness of the flooring material of the present invention is not limited, but can usually be set within a range of 5 mm or less, and is particularly preferably 3 mm or less, and more preferably 2.5 mm or less. The lower limit of the above thickness can be, for example, about 1.5 mm, but is not limited to this. By reducing the total thickness of the flooring material of the present invention, good flexibility can be obtained while maintaining high dimensional stability. In particular, by setting the total thickness of the flooring material to 2.5 mm or less, the cutability is also improved, and it becomes possible for installers to easily cut the flooring material with a utility knife or the like without needing special tools. This improves workability and leads to a reduction in installation time.

[0030] 2-4) Coefficient of thermal expansion Since the thermal expansion of the flooring material of the present invention is effectively suppressed, even when installed with adhesives, problems that may occur over time due to thermal expansion can be prevented. In this case, the smaller the thermal expansion coefficient of the flooring material of the present invention, the more desirable, for example, 6.0 × 10 -5 ( / ℃) or lower, especially 2.2 × 10 -5 ~3.5×10 -5 It can be set to approximately ( / °C), but is not limited to this.

[0031] 3) Uses of the flooring material of the present invention The flooring material of the present invention can be used as a flooring material for various types of floor surfaces, but it is particularly suitable for use as a flooring material for residential buildings due to its excellent ability to conform to uneven surfaces and its ease of installation. For example, it is more suitable for use as a flooring material for interiors where the entire or partial flooring is replaced relatively frequently, such as in rental housing.

[0032] 4) Each layer constituting the flooring material of the present invention In the following, in addition to the resin-containing hard layer, transparent resin layer, and back resin layer which are essential for the flooring material of the present invention, optional laminated layers will also be described.

[0033] <Resin-containing hard layer> In the flooring material of the present invention, the resin-containing hard layer serves as the core material and is a layer that contributes to the physical properties of the flooring material of the present invention (physical properties of the present invention) as described below.

[0034] The composition of the resin-containing hard layer in the flooring material of the present invention includes at least a resin component and an inorganic filler.

[0035] Examples of resin components include various synthetic resins such as vinyl chloride resins, polyolefin resins, polyurethane resins, and acrylic resins. In particular, at least one of vinyl chloride resins and polyolefin resins can be suitably used because they provide high hardness.

[0036] Examples of vinyl chloride resins include vinyl chloride resin (homopolymer), as well as copolymers containing vinyl chloride as a copolymer component, such as vinyl chloride-vinyl acetate copolymer and ethylene-vinyl chloride copolymer. Examples of polyolefin resins include polypropylene resin.

[0037] In this case, a vinyl chloride resin with an average degree of polymerization of 700 to 1300 is preferred as the vinyl chloride resin. Furthermore, a polypropylene resin with an average degree of polymerization of 800 to 1000 can be suitably used as the polypropylene resin.

[0038] In particular, the present invention more preferably contains at least a vinyl chloride resin because it is inexpensive, has excellent flexibility and durability, and is also easy to process. As the vinyl chloride resin, a vinyl chloride resin containing 3% by weight or less of a plasticizer is preferred. In particular, a vinyl chloride resin containing less than 0.3% by weight of a plasticizer is more preferred, and among these, a vinyl chloride resin containing 0 to 0.3% by weight of a plasticizer is most preferred. By applying such a vinyl chloride resin with an extremely low or no plasticizer content (especially a rigid vinyl chloride resin) to the resin-containing rigid layer, a rigid flooring material that combines hardness and high dimensional stability can be provided more reliably.

[0039] The plasticizer is not particularly limited, and examples include at least one of dioctyl phthalate (DOP), diheptyl phthalate (DHP), diisononyl phthalate (DINP), trioctyl phosphate (TOP), triphenyl phosphate (TPP), dioctyl terephthalate (DOTP), dioctyl isophthalate (DOIP), and diisononylcyclohexyl phthalate (DINCH). Commercially available products of these can also be used.

[0040] The resin content in the resin-containing hard layer is usually 35% by weight or less, preferably 30% by weight or less, and more preferably 28% by weight or less. The lower limit of the resin content is preferably 15% by weight, preferably 20% by weight, but is not limited to this. In this invention, if a vinyl chloride resin containing a plasticizer is included in the resin-containing hard layer, the above "resin content" refers to the content of the vinyl chloride resin excluding the plasticizer. This standard for content is the same for other layers.

[0041] The plasticizer content in the resin-containing hard layer is usually less than 1% by weight, and is particularly preferably 0.9% by weight or less, and more preferably 0 to 0.5% by weight. In this invention, if a vinyl chloride resin containing a plasticizer is included in the resin-containing hard layer, the above "plasticizer content" shall also include the plasticizer content contained in the vinyl chloride resin. This standard for content shall be the same for other layers as well.

[0042] By setting the resin component content and plasticizer content as described above, it is possible to more reliably provide flooring materials that are hard and have excellent dimensional stability.

[0043] The filler material can be one that is known or formulated in commercially available flooring materials. In the present invention, inorganic fillers are particularly preferred from the viewpoint of dimensional stability, etc. Examples of inorganic fillers include oxides, hydroxides, carbonates, chlorides, silicates, etc. of inorganic or metallic elements. More specifically, examples include calcium oxide, barium carbonate, magnesium hydroxide, aluminum hydroxide, clay, talc, mica, calcium carbonate, silica sand, aluminum oxide, calcium carbonate, calcium silicate, etc. The calcium carbonate may be either heavy calcium carbonate or light calcium carbonate. These can be used one or more times. In the present invention, it is particularly preferable to include calcium carbonate as the inorganic filler material.

[0044] The filler can usually be used in powder form. When in powder form, the average particle size is not limited, but it can be appropriately set within a range of approximately 1 to 300 μm.

[0045] The filler content in the resin-containing hard layer is usually 60% by weight or more, and is particularly preferably 65-85% by weight, and more preferably set within the range of 65-80% by weight. By setting the content to the above level, it is possible to more reliably provide a flooring material that is hard yet has excellent dimensional stability.

[0046] The resin-containing hard layer may contain other additives as long as they do not interfere with the effects of the present invention. Examples include stabilizers, processing aids, fungicides, flame retardants, antioxidants, lubricants, and colorants. The total content of additives in the resin-containing hard layer can usually be 5% by weight or less, but is not limited to this. In particular, in the present invention, by incorporating a colorant into the resin-containing hard layer, it is possible to create a resin-containing hard layer with a desired color, thereby providing a hard flooring material with a more aesthetically pleasing design.

[0047] Furthermore, if these additives are inorganic compounds, the content of such additives shall also be included in the content of the inorganic filler mentioned above.

[0048] The thickness of the resin-containing hard layer is not particularly limited, but can be, for example, about 1 to 3 mm, and especially 1.5 to 2.5 mm. By setting the thickness within the above range, the strength and hardness of the resin-containing hard layer can be ensured while keeping the overall thickness of the flooring material relatively thin.

[0049] The method for forming the resin-containing hard layer is not particularly limited, but usually a pre-formed sheet can be used. That is, a sheet for the resin-containing hard layer can be obtained by melting the resin composition that will be used as the starting material and forming it into a sheet.

[0050] Furthermore, such sheets can be laminated in two or more layers. The molding method is not particularly limited, and various methods such as extrusion molding, blow molding, and calendering can be employed. In addition, the resin-containing rigid layer and the adjacent layer can be formed by simultaneous extrusion lamination. Moreover, the sheet can be obtained by forming a coating film of a mixed liquid in which the resin components are dissolved or dispersed.

[0051] <Transparent resin layer> The transparent resin layer primarily serves to protect the resin-containing hard layer. Therefore, the transparent resin layer may be formed directly on the resin-containing hard layer, or it may be formed via other layers such as a design layer (printed layer).

[0052] The transparent resin layer is usually formed from a resin composition containing a resin component, but the resin component is not particularly limited. Examples include vinyl chloride resins, polyolefin resins, acrylic resins, polyester resins, etc. More specifically, thermoplastic resins such as vinyl chloride resin, low-density polyethylene resin, high-density polyethylene resin, polyester resin, vinyl chloride-vinyl acetate copolymer resin, and ethylene-vinyl acetate copolymer resin can be used. Among these, vinyl chloride resin is preferred because of its excellent durability and processability. Examples of vinyl chloride resins include vinyl chloride resin (homopolymer), as well as copolymers containing vinyl chloride as a copolymer component, such as vinyl chloride-vinyl acetate copolymer and ethylene-vinyl chloride copolymer. Because vinyl chloride resin has excellent flexibility, by increasing its strength and hardness, it can withstand high pressures that occur when a localized load is applied.

[0053] In particular, in the present invention, it is preferable that the transparent resin layer contains at least a vinyl chloride resin because it is inexpensive, has excellent flexibility and durability, and is also easy to process. In particular, a vinyl chloride resin containing 13% by weight or more of a plasticizer is preferred, a vinyl chloride resin containing 20% ​​by weight or more of a plasticizer is even more preferred, and among these, a vinyl chloride resin containing 22 to 37% by weight of a plasticizer is most preferred. In the present invention, by applying a vinyl chloride resin having such a plasticizer-rich composition to the transparent resin layer, chipping of corners, edges, etc. of the flooring material can be effectively suppressed, and warping of the flooring material can also be effectively suppressed.

[0054] The plasticizer is not particularly limited, and examples include at least one of dioctyl phthalate (DOP), diheptyl phthalate (DHP), diisononyl phthalate (DINP), trioctyl phosphate (TOP), triphenyl phosphate (TPP), dioctyl terephthalate (DOTP), dioctyl isophthalate (DOIP), and diisononylcyclohexyl phthalate (DINCH). Commercially available products of these can also be used.

[0055] The resin component content in the transparent resin layer is usually 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more. The upper limit of the resin component content can be, for example, 80% by weight (especially 75% by weight), but is not limited to this.

[0056] The plasticizer content in the transparent resin layer is usually 10% by weight or more, more preferably 20% by weight or more, and more preferably 25% by weight or more. The upper limit of the above content is preferably 40% by weight, and more preferably 35% by weight, but is not limited to this.

[0057] In particular, to more reliably achieve the above-mentioned effects of the transparent resin layer, it is preferable that the total content of the resin component, especially the vinyl chloride resin and plasticizer, be higher. For example, the total content is preferably around 80 to 99% by weight, and more preferably 85 to 98% by weight.

[0058] Other additives may be included in the transparent resin layer, but from the viewpoint of ensuring that the total content of resin components and plasticizers remains within a specific range, as described above, it is desirable to keep the amount of other additives to as little as possible. Examples include fillers, stabilizers, processing aids, fungicides, flame retardants, antioxidants, lubricants, and colorants, but it is generally desirable that the total content of additives in the transparent resin layer be 2% by weight or less. In particular, it is preferable that the content of fillers in the transparent resin layer be 0 to 1% by weight.

[0059] The transparent resin layer only needs to be transparent enough to allow the underlying layer to be visible, and may be semi-transparent to that extent. As shown in Figure 2, when a design layer 14 is formed beneath the transparent resin layer 12, the haze value of the transparent resin layer 12 is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less, from the viewpoint of improving the identifiability of the design layer 14. By setting it to such a value, it is possible to create a configuration in which the surface of the layer that serves as the base for the transparent resin layer, such as the design layer of the sheet body, can be more reliably seen.

[0060] While there is no strict lower limit for the haze value, it is usually sufficient to set it at around 1%. When the transparent resin layer is to be transparent, it is most desirable that it contains virtually no filler. A lower filler content results in higher resin strength and hardness, which in turn increases its resistance to high pressures caused by localized loads, effectively preventing chipping and other damage as described above.

[0061] The thickness of the transparent resin layer is not particularly limited, but can be, for example, about 0.03 to 1.5 mm, preferably 0.04 to 1.0 mm, and more preferably 0.05 to 0.5 mm. By setting the thickness of the transparent resin layer within the above range, the strength and hardness of the resin can be ensured while keeping the overall thickness of the flooring material relatively thin. Therefore, in combination with the above conditions, it is possible to ensure durability against high pressure that occurs when a localized load is applied.

[0062] Furthermore, while the ratio of the thickness of the transparent resin layer to the thickness of the resin-containing hard layer is not particularly limited, it is generally desirable that the thickness of the transparent resin layer be about 1-10% of the thickness of the resin-containing hard layer.

[0063] The method for forming the transparent resin layer is not particularly limited and can be carried out by, for example, coating and drying a paste for forming the transparent resin layer, or by heat-pressing a film for forming the transparent resin layer. In the present invention, for example, a method of laminating a flexible polyvinyl chloride resin film can be suitably adopted as the film for forming the transparent resin layer. In this case, a method of heat-pressing (heat sealing) can be adopted as the joining method.

[0064] <Protective layer> In the flooring material of the present invention, as shown in Figure 2, a protective layer can be formed on the surface of the transparent resin layer as needed. The protective layer is an optional layer, but if formed, it protects the transparent resin layer and can also provide functions such as stain resistance. Typically, the protective layer is formed on top of the transparent resin layer (especially in direct contact with the transparent resin layer). Furthermore, it is desirable that the protective layer be placed on the outermost surface of the hard flooring material and constitute a surface exposed to the outside. This allows for more reliable protection of the hard flooring material against external pressure, friction, etc.

[0065] The protective layer is formed from a resin composition containing a resin component, for example, but the resin component is not particularly limited. Examples include unsaturated polyesters such as condensates of unsaturated dicarboxylic acids and polyhydric alcohols, methacrylates such as polyester methacrylate, polyether methacrylate, polyol methacrylate, and melamine methacrylate, and UV-curable resins such as polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, and melamine acrylate.

[0066] Among the resin components mentioned above, it is preferable to use an ultraviolet-curable resin because it possesses a combination of surface hardness, transparency, and other desirable properties. In this invention, if the protective layer is transparent or semi-transparent, the identifiability and visibility of the design layer formed beneath it can be further enhanced. The transparency (haze value) of the protective layer is not particularly limited, but can be appropriately set within the same range as that of the transparent resin layer. That is, the haze value is preferably 40% or less, more preferably 30% or less, and even more preferably 1 to 20%.

[0067] Furthermore, other additives may be incorporated into the protective layer as needed, within the limits that do not hinder the effects of the present invention. Examples of additives that can be incorporated into the protective layer include fillers. In particular, hard particles can be added as fillers for purposes such as improving slip resistance or durability, or adjusting gloss. Examples of fillers include oxides, hydroxides, carbonates, chlorides, silicates, and other silicates of inorganic or metallic elements. More specifically, examples include calcium oxide, barium carbonate, magnesium hydroxide, aluminum hydroxide, clay, talc, mica, calcium carbonate, silica sand, aluminum oxide, calcium carbonate, and calcium silicate. These can be used individually or in combination of two or more. In the present invention, it is particularly preferable to include aluminum oxide or silica as a filler. Aluminum oxide can be suitably used to improve slip resistance and durability, while silica can reduce gloss and prevent glare.

[0068] The filler can usually be used in powder form. When in powder form, the average particle size is not limited, but it can usually be set appropriately within a range of about 1 to 200 μm.

[0069] The content of the filler in the protective layer is not particularly limited, but it is generally preferable to set it to 10% by weight or less. In particular, hard particles may be included as a filler in the transparent protective layer to improve abrasion resistance, etc., but when the flooring material is used for residential purposes, it is preferable that the filler content be 1% by weight or less, and more preferably 0% by weight, in order to ensure smoothness when stepped on with bare feet. Therefore, it can be set, for example, within the range of 0 to 1% by weight.

[0070] Other additives besides fillers include, for example, stabilizers, processing aids, fungicides, antibacterial agents, antiviral agents, surfactants, antistatic agents, deodorants, anti-allergic agents, flame retardants, antioxidants, and colorants. The total content of these additives can be, for example, around 0-5% by weight, but is not limited to this.

[0071] The thickness of the protective layer is not particularly limited, but if it is set too thick, the protective layer itself will warp significantly, and the edges of the flooring material of the present invention will warp upwards. This makes it difficult to optimize the composition settings or thickness balance of each layer in order to control this. Therefore, it is preferable to set it appropriately within a range of less than 10 μm, and more preferably between 1 and 9 μm. By controlling the thickness to be relatively thin in this way, the function of the protective layer can be ensured while more effectively suppressing the warping of the protective layer itself. If the edges of the flooring material warp significantly upwards, it will require extra effort during installation, and as mentioned above, concerns such as lifting or displacement of the flooring material may arise after installation. For example, in the case of flooring material with a large protective layer thickness, such as the one described in Example 9 of Patent Document 4, the flooring material before the protective layer is applied is intentionally warped significantly downwards to control the upward warping of the flooring material after the protective layer is applied.

[0072] The protective layer can be formed, for example, by applying a coating liquid containing the resin component described above and then curing it. The application method is not limited, and for example, a roll coater, bar coater, die coater, air knife coater, flow coater, spray coating, etc., can be used. Roll coaters and flow coaters are particularly preferred due to their excellent processability. The curing method is not limited and can be appropriately selected depending on the type of resin component, etc. For example, curing can be performed by aging, drying, UV irradiation, heating, etc. Therefore, when using a coating liquid containing a UV-curable resin, the desired protective layer can be formed by curing the coating film by UV irradiation.

[0073] In the present invention, as described below, joint-like regions can also be formed in the flooring material of the present invention, and in that case, a protective layer can also be formed on the joint-like regions.

[0074] <Resin layer on the back> The back resin layer is formed to protect the back surface of the flooring material of the present invention and to suppress or prevent the entire flooring material from warping in a concave or convex shape. In particular, if the flooring material of the present invention warps in a concave shape as a whole, lifting may occur at the joints when multiple flooring materials of the present invention are butted together to form a floor surface. For this reason, a back resin layer is provided on the back side of the flooring material of the present invention to suppress such concave warping. In particular, as shown in Figure 1, the back resin layer can be formed on the surface of the back surface of the resin-containing hard layer.

[0075] Warping of flooring materials occurs when the resin constituting the flooring material shrinks or expands due to environmental changes such as temperature and humidity changes, or deterioration due to light or aging, causing dimensional changes. For this reason, it is preferable to make the amount of shrinkage on the back side greater than that on the surface side to create a convex-shaped warp. In conventional technology, methods to balance the shrinkage and expansion of the entire flooring material are generally used to ensure the effect of preventing warping, such as using a nonwoven fabric on the back side or adjusting the shrinkage rate of the transparent resin layer. In contrast, the flooring material of the present invention has a structural limitation in that the strength and hardness of the flooring material surface must be increased to withstand localized loads, making it difficult to balance the shrinkage and expansion of the entire flooring material in some cases. For this reason, in the present invention, the same material as the transparent resin layer is used as the back resin layer, and the shrinkage and expansion behavior of the transparent resin layer side and the back side are made almost identical, making it possible to more reliably prevent warping of the flooring material even in the above cases. Furthermore, it is possible to adjust the amount of shrinkage on the back side to be greater than that on the surface side to create a convex-shaped warp.

[0076] From this viewpoint, in the present invention, it is preferable to directly laminate the back resin layer onto the back surface of the resin-containing hard layer. By directly laminating the back resin layer onto the back surface of the resin-containing hard layer, not only is it possible to adjust the warping, but even if the overall thickness of the flooring material is thin, a strong structure is achieved, dimensional changes are minimal, and high straightness can be ensured. This is thought to be due to the fact that the sandwich-like structure, in which the resin-containing hard layer is sandwiched between soft resin layers on both sides, becomes a strong structure due to the shrinkage caused by the resins on both sides. Furthermore, the strength of the sandwich-like structure can be increased by adjusting the distance between the transparent resin layer and the back resin layer to an appropriate distance. When the transparent resin layer and the back resin layer are directly laminated onto the front and back surfaces of the resin-containing hard layer without interposing a shape-stabilizing layer or the like, the thickness of the resin-containing hard layer becomes the approximate distance between the transparent resin layer and the back resin layer. Therefore, by adjusting the resin-containing hard layer, the distance between the transparent resin layer and the back resin layer can also be adjusted, making it possible to provide a flooring material with high strength even if it is thin.

[0077] The back resin layer is usually not visible after installation, so it can be transparent or opaque. If a transparent back resin layer is used, the same haze as that used for the transparent resin layer can be adopted.

[0078] The back resin layer is usually formed from a resin composition containing resin components, but the resin components are not particularly limited. Examples include vinyl chloride resins, polyolefin resins, acrylic resins, polyester resins, etc. More specifically, thermoplastic resins such as vinyl chloride resin, low-density polyethylene resin, high-density polyethylene resin, polyester resin, vinyl chloride-vinyl acetate copolymer resin, and ethylene-vinyl acetate copolymer resin can be used. Among these, vinyl chloride resin is preferred because of its excellent durability and processability. Examples of vinyl chloride resins include vinyl chloride resin (homopolymer), as well as copolymers containing vinyl chloride as a copolymer component, such as vinyl chloride-vinyl acetate copolymer and ethylene-vinyl chloride copolymer. Because vinyl chloride resin has excellent flexibility, increasing its strength and hardness makes it possible to withstand high pressures that occur when a localized load is applied.

[0079] In particular, in the present invention, it is preferable to include at least a vinyl chloride resin in the back resin layer because it is inexpensive, has excellent flexibility and durability, and is also easy to process. In particular, a vinyl chloride resin containing 3% by weight or more of a plasticizer is preferred, and among these, a vinyl chloride resin containing 4 to 13% by weight of a plasticizer is more preferred. Therefore, for example, a vinyl chloride resin containing 6 to 11% by weight of a plasticizer can also be suitably used.

[0080] The plasticizer is not particularly limited, and examples include at least one of dioctyl phthalate (DOP), diheptyl phthalate (DHP), diisononyl phthalate (DINP), trioctyl phosphate (TOP), triphenyl phosphate (TPP), dioctyl terephthalate (DOTP), dioctyl isophthalate (DOIP), and diisononylcyclohexyl phthalate (DINCH). Commercially available products of these can also be used.

[0081] The resin content in the back resin layer is usually 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more. The upper limit of the resin content is preferably 99% by weight, and can be about 95% by weight, but is not limited to this.

[0082] The plasticizer content in the back resin layer is usually 2% by weight or more, and is particularly preferably 5% by weight or more. The upper limit of the above content is preferably 20% by weight, and is particularly likely to be around 15% by weight, but is not limited thereto.

[0083] In particular, to more reliably achieve the above-mentioned effects of the back resin layer, it is preferable that the total content of the resin component (especially vinyl chloride resin) and plasticizer be as high as possible. For example, the total content is preferably around 80 to 99% by weight, and more preferably 85 to 98% by weight.

[0084] The back resin layer may contain other additives, but from the viewpoint of ensuring that the total content of resin components and plasticizers remains within a specific range, as described above, it is desirable to keep the amount of additives to as little as possible. Examples include fillers, stabilizers, processing aids, antifungal agents, flame retardants, antioxidants, lubricants, and colorants, but it is generally desirable that the total content of additives in the back resin layer be 3% by weight or less. In particular, it is preferable that the content of fillers in the back resin layer be 0 to 1% by weight.

[0085] The thickness of the resin layer on the back surface is not limited, but is usually about 0.03 to 1.5 mm, preferably 0.04 to 1.0 mm, and more preferably 0.05 to 0.5 mm.

[0086] Furthermore, while the ratio of the thickness of the back resin layer to the thickness of the resin-containing hard layer is not particularly limited, it is generally desirable that the thickness of the back resin layer be 25% or less of the thickness of the resin-containing hard layer.

[0087] When forming the back surface resin layer, the same composition and formation method as for the transparent resin layer can be used. For example, it can be formed using a resin composition containing resin components, plasticizers, and stabilizers.

[0088] <Design layer> The design layer is a layer that has the function of expressing a desired design, such as a picture, design, pattern, or characters, and giving the flooring material of the present invention an aesthetic appearance. By providing the above design layer, the flooring material of the present invention can be given a desired aesthetic appearance simply and inexpensively. Furthermore, the design layer may be a single colored layer or a colored layer consisting of two or more colored regions.

[0089] The design layer is preferably formed from a resin composition containing a thermoplastic resin that facilitates bonding with layers positioned above or below it. Examples of the thermoplastic resin include vinyl chloride resins, olefin resins, acrylic resins such as ethylene-vinyl acetate copolymers and ethylene-methacrylate resins, amide resins, ester resins, vinyl acetate resins, various elastomers such as olefin elastomers and styrene elastomers, and rubber.

[0090] Among these, it is preferable that the material be formed from a resin composition containing a vinyl chloride resin. This provides superior flexibility, and allows for the easy formation of diverse designs by adding colorants or printing, thus enabling the inexpensive and easy formation of design layers.

[0091] Various additives may be incorporated into the aforementioned resin composition as needed. Known or commercially available additives can be used. Examples include fillers, plasticizers, flame retardants, stabilizers, antioxidants, lubricants, colorants, and foaming agents. Therefore, a resin composition containing, for example, a resin component, a plasticizer, and a stabilizer can be employed.

[0092] The thickness of the design layer is not particularly limited, but is preferably 0.02 to 1.50 mm, and preferably 0.05 to 1.00 mm.

[0093] The method for forming the design layer is not particularly limited. For example, it can be formed by directly printing a pattern onto the upper surface of a thermoplastic resin sheet using a known printing method, or by laminating a printed pattern film onto the upper surface of a thermoplastic resin sheet. In addition, it can be formed using a resin composition containing a coloring agent and a thermoplastic resin, or by preparing multiple resin compositions containing coloring agents of different colors and thermoplastic resins and kneading them together.

[0094] Methods for directly printing patterns onto the upper surface of a thermoplastic resin sheet include using various devices such as gravure printing, screen printing, and flexographic printing, as well as printing using transfer sheets. Additionally, a method of laminating a printed film with a pre-formed design layer onto a resin film can also be employed.

[0095] The method of attaching a patterned film printed on it to the upper surface of a thermoplastic resin sheet is preferable because it allows for the easy expression of a variety of patterns. For example, the patterned film can be used to easily and inexpensively impart complex designs to the flooring material of the present invention, such as stone patterns, wood grain patterns, and geometric patterns. The thickness of the patterned film is usually preferably about 0.05 to 1 mm, and more preferably 0.05 to 0.5 mm. If the thickness of the patterned film is too thin, light may pass through and the surface of the thermoplastic resin sheet laminated on the lower surface may become visible, potentially preventing the full expression of the design of the patterned film. On the other hand, if the thickness of the patterned film is too thin, the boundaries of the flooring material may become noticeable when the flooring material is laid.

[0096] Furthermore, by changing the pattern film, the appearance elements of the flooring material of the present invention can be easily varied using the same production equipment, including patterns, brightness, saturation, and hue. By laying the flooring material with varying appearance elements irregularly, a unified design can be expressed across the entire floor surface. An example of expressing a unified design using flooring material with varying appearance elements is to vary the brightness, saturation, or hue of the stone pattern, thereby creating a texture across the entire floor surface that resembles a floor made of various types of wood. When flooring material with varying appearance elements is laid irregularly in this way, even if the flooring material is partially replaced, it does not create a sense of incongruity in design, and a texture that resembles a floor made of various types of wood can be expressed across the entire floor surface.

[0097] <Adhesive layer> Adhesive layers can be formed as needed to join each layer. These adhesive layers can be formed, for example, using an adhesive. Known or commercially available adhesives can be used as appropriate.

[0098] The type of adhesive can be appropriately selected according to the material of each layer. For example, adhesives containing one or more types of adhesive components selected from urethane resins, vinyl acetate resins, styrene-butadiene copolymer resins, acrylic resins, vinyl chloride resins, and epoxy resins are examples. Among these, adhesives using urethane resin as the adhesive component are preferable due to their excellent moisture resistance and other properties.

[0099] Furthermore, the curing type of the adhesive is not limited; various types of adhesives can be used, such as one-component adhesives, two-component adhesives, thermosetting adhesives, hot-melt adhesives, and UV-curing adhesives. Among these adhesives, hot-melt adhesives are preferable because they have a short curing time and provide high productivity. More preferably, reactive hot-melt adhesives are preferred. This allows for more effective suppression of deterioration over time, resulting in strong adhesion over a long period. Therefore, in the present invention, reactive hot-melt adhesives containing urethane resin as an adhesive component can be suitably used. These adhesives are resistant to humidity, maintain stable quality over a long period, and do not require special equipment such as UV irradiation, allowing for the manufacture of flooring materials with simple equipment or operations.

[0100] In this invention, by using an adhesive, thermal degradation of the product during the production process can be suppressed, and even when each layer is made of a different material, it can be joined together effectively.

[0101] The thickness of the adhesive layer is not particularly limited, but is usually around 1 to 200 μm, and is particularly preferably 30 to 100 μm. Setting the thickness within this range makes it possible to bond each layer more effectively.

[0102] The adhesive layer can be formed, for example, by applying the adhesive to the lower surface of a substrate sheet that will become a resin-containing rigid layer, and then curing it. The curing method can be appropriately selected according to the curing type of the adhesive used, and various processes such as aging, drying, heating, and ultraviolet irradiation can be employed. The conditions for these processes can be in accordance with known methods.

[0103] <Other layers> As described above, the flooring material of the present invention requires a back resin layer, a resin-containing hard layer, and a transparent resin layer. However, as long as it does not hinder the effects of the present invention, it may also include other layers such as an adhesive layer and a design layer. Therefore, for example, as shown in Figure 2, a hard flooring material consisting of a "back resin layer / resin-containing hard layer / design layer / transparent resin layer / protective layer" can be cited as a preferred embodiment, as can a hard flooring material consisting of a "back resin layer / resin-containing hard layer / design layer / transparent resin layer".

[0104] However, it is preferable that the hard flooring material of the present invention does not contain a shape-stabilizing layer containing inorganic fibers. Such a layer is also called a "reinforcement layer," and these are also included in the above-mentioned shape-stabilizing layer. When a shape-stabilizing layer containing inorganic fibers, especially inorganic fibers such as glass fibers, is included, it becomes an obstacle when recycling used flooring material, but when it is not included, it can be recycled relatively easily. In addition, since a shape-stabilizing layer containing inorganic fibers is relatively expensive, the manufacturing cost of the hard flooring material itself can be reduced by omitting its use.

[0105] 5) Method for manufacturing the flooring material of the present invention The flooring material of the present invention can be manufactured by forming or laminating each layer in the manner described above. That is, in addition to the method of applying an adhesive to each layer, methods such as joining the layers by heat fusion without applying an adhesive can also be employed for laminating each layer.

[0106] When using adhesive coating, the adhesive layer can be the one described above. The adhesive layer can be formed by applying the adhesive to one surface of the layers to be joined, or by applying the adhesive to both surfaces.

[0107] Furthermore, in this invention, when joining by heat fusion without the application of an adhesive, the method of heat fusion is not particularly limited. For example, the layers can be joined by melting and softening them under heat and pressure while they are stacked on top of each other. More specifically, the layers can be joined by hot pressing or continuous pressing, which is a continuous process of hot pressing. Heat fusion joining is advantageous in that the material of each layer is not plasticized, it is less prone to deterioration over time, and it can provide a strong bond for a long period of time.

[0108] Furthermore, when joining by heat fusion, it is desirable that at least one of the layers to be joined contains a component that has heat-sealing properties. Examples include polyethylene, polypropylene, and ethylene vinyl acetate copolymer.

[0109] Furthermore, when joining the layers by heat fusion, two or more layers can also be formed by extrusion lamination. The laminate obtained in this way can be used as part of the layer structure of the flooring material of the present invention.

[0110] After laminating each layer, the laminated body may be cut, processed, etc., according to known methods as needed. Furthermore, if a tongue-and-groove structure is to be formed on the side surface of the flooring material of the present invention, a male or female tongue-and-groove structure may be formed on the side surface according to known processing methods.

[0111] 2. Floor structure using hard flooring materials The present invention encompasses a floor structure in which the flooring material of the present invention is attached to the subfloor using at least one of an adhesive, adsorbent, or adhesive tape that allows the hard flooring material to be attached to the subfloor in a non-destructive manner.

[0112] Here, "non-destructive" means that, in this invention, when removing flooring materials attached with adhesive, adsorbent, or adhesive tape, the flooring materials do not crack or chip due to the adhesive force, and can be removed while substantially maintaining the original form of the flooring materials. Furthermore, "removable" means that flooring materials attached with adhesive, adsorbent, or adhesive tape can be removed and reattached. In this case, the method of removing the flooring materials is not limited, but manual methods such as removing them by hand or using tools such as scrapers are preferred because they are simple.

[0113] When forming a floor structure, multiple pieces of the present invention's flooring material, which are roughly rectangular in shape such as roughly square, roughly rectangular, roughly rhombic, or roughly parallelogram, are prepared, and these are placed on a subfloor such as a concrete slab using at least one of an adhesive, an adsorbent, and an adhesive tape to form a floor structure composed of the present invention's flooring material. In particular, with the present invention, a floor structure can be formed by directly laying the present invention's flooring material on such a subfloor.

[0114] As described above, in the present invention, the flooring material of the present invention can be installed on the subfloor using at least one of an adhesive, an adsorbent, and an adhesive tape. Therefore, tasks such as partial replacement of flooring when repairing some of the flooring, replacement of flooring during renovation, re-laying flooring for positioning during construction, and removal of only the flooring for recycling when demolishing a building can be performed more easily and reliably.

[0115] The adhesive described above is not particularly limited as long as it allows for non-destructive attachment and detachment of the flooring material to the subfloor by hand. For example, at least one of the following can be suitably used: urethane-based adhesive, acrylic-based adhesive, silicone-based adhesive, rubber-based adhesive, etc., with acrylic-based adhesive being particularly preferred. Furthermore, the properties and form of the adhesive are not limited, and any type such as solvent-based, emulsion-based, or solvent-free can be used, with emulsion-based being particularly preferred. Commercially available adhesives can also be used.

[0116] An "adhesive material" mainly consists of foamed resin and adheres to the floor surface by suction or adhesion. When a load is applied to the laid flooring material, the adhesive material adheres strongly to the floor surface, preventing the flooring material from shifting. On the other hand, when no load is applied, it adheres weakly to the floor surface, allowing the flooring material to be removed relatively easily. The part on which the adhesive material is provided is sometimes referred to as the "adhesive part." As the adhesive material, a foamed resin having a porous structure with multiple micropores and flexibility is preferably used. The foamed resin may have either an open-cell structure or a closed-cell structure, but an open-cell structure is preferred because it has sufficient suction cup function and exhibits high adsorption force. The material of the foamed resin is not particularly limited and examples include thermoplastic resins such as acrylic resin, urethane resin, ethylene vinyl acetate, polyvinyl alcohol, polyvinyl acetate, epoxy resin, acrylic acid ester, and polyester. Due to its excellent adhesion, it is preferable to use foamed acrylic resin, which is obtained by foaming acrylic resin, as the material for forming the adhesive material. The foaming ratio of the foamed resin is not particularly limited, but from the viewpoint of ensuring sufficient adhesion to the floor substrate and minimizing material damage, it is preferably greater than 1.1 times and less than or equal to 6 times, more preferably between 1.6 times and less than or equal to 5 times, and even more preferably between 1.6 times and less than 3 times. These adsorbents can be those that are known or commercially available.

[0117] Furthermore, the adhesive tape only needs to allow for non-destructive attachment and detachment of the flooring material to the subfloor by hand, and can be a tape in which an adhesive layer of the above-mentioned adhesive is formed on one or both sides of the base film. For example, double-sided adhesive tape can be suitably used. Commercially available adhesive tapes can also be used.

[0118] When constructing a floor structure, the present invention can use a hard floor material having flat sides as shown in Figure 2, but it is also possible to use a hard floor material that has a roughly rectangular planar shape with chamfered areas on all four sides.

[0119] The method for forming the chamfered area is not particularly limited, but for example, as shown in Figure 3, the chamfered area T can be formed by machining the upper corner of the side surface. This makes it possible to form a smoother floor surface. Therefore, even when a joint area is formed by butting adjacent floor materials together, the protruding parts are reduced, which can suppress the feeling of catching on something when walking in the joint area and prevent incidents such as tripping. In addition, even if the unevenness of the floor base cannot be completely concealed and the edges of adjacent hard floor materials lift upward, creating a step, the step can be made less visible by forming the chamfered area T.

[0120] As shown in Figure 3A, in a side view, the chamfered area T has an inclination angle θ with respect to the horizontal plane, for example, 20 to 70 degrees, preferably 40 to 50 degrees, and more preferably 45 degrees. If the angle is too shallow, the effect of concealing unevenness by the chamfer is reduced, making it difficult to obtain a visual effect. If the angle is too deep, dirt is more likely to accumulate and difficult to remove, making it prone to staining, and when walking barefoot on the flooring material, the tactile sensation of the corners may be stronger, causing discomfort. As shown in Figure 3B, in a plan view, the width W of the chamfered area T is for example, 0.2 mm to 1.0 mm, preferably 0.3 mm to 0.8 mm. It is preferable, but not limited to, that these angles θ and width W are set to be the same on all four sides of a single hard flooring material.

[0121] The flooring material of the present invention has a resin-containing hard layer and a transparent resin layer. Therefore, a chamfered area can be formed by scraping from the top down to the middle of the resin-containing hard layer in the area where the chamfered area is to be formed. As a result, the resin-containing hard layer is exposed in the chamfered area, and by coloring the resin-containing hard layer with any color, the difference from the transparent resin layer can be made visible, and the joint-like area formed where adjacent flooring materials are joined can be made into a design accent. In particular, a configuration in which a design layer is placed between the resin-containing hard layer and the transparent resin layer can form a more complex design. Furthermore, these design effects can make lifting of the flooring material that may occur due to the inability to absorb the unevenness of the floor substrate less noticeable, resulting in a better appearance. In addition to the method of forming the chamfered area by scraping, there is also a method of forming a curved chamfered area by pressing. Using this method, the sharp corners become invisible, giving a softer impression. [Examples]

[0122] Examples and comparative examples are shown below to more specifically describe the features of the present invention. However, the scope of the present invention is not limited to the examples.

[0123] Example 1 As shown in Figure 2, a hard flooring material was fabricated consisting of the following layers from bottom to top: "backside resin layer 13 / resin-containing hard layer 11 / design layer 14 / transparent resin layer 12 / transparent protective layer 15". To form the back resin layer 13, the resin-containing hard layer 11, and the transparent resin layer 12, a vinyl chloride resin sheet having the composition shown in Table 1 was prepared, and a commercially available printed film for forming the design layer 14 was also prepared. These were manufactured by extrusion molding using the resin compositions shown in Table 1. Each of these films was prepared separately, wound into a roll, and a laminate consisting of a "backside resin layer 13 / resin-containing hard layer 11 / design layer 14 / transparent resin layer 12" was fabricated by continuously pulling them out in the longitudinal direction so that each layer would be stacked in order, and pressing them under heating at a temperature of 140-150°C. Next, a coating liquid containing a commercially available UV-curable resin was applied to the surface of the transparent resin layer 12 of the laminate, and a transparent protective layer 15 was formed by curing it with UV irradiation. In this way, a hard flooring material (50cm long x 50cm wide, total thickness approximately 2.2mm) was obtained, consisting of the following layers from bottom to top: "backside resin layer (thickness approximately 0.2mm) / resin-containing hard layer (thickness approximately 1.83mm) / design layer (thickness approximately 0.07mm) / transparent resin layer (thickness approximately 0.1mm) / transparent protective layer (thickness approximately 6μm)".

[0124] [Table 1]

[0125] The composition and other details of the resin-containing hard layer in Table 1 are as follows: • PVC: Polyvinyl chloride resin, commercially available DOTP: Dioctyl terephthalate, commercially available (plasticizer) • Filler: Calcium carbonate, commercially available (particle size approximately 74-149 μm)

[0126] Test Example 1 The following physical properties were measured for the hard flooring material (sample) obtained in Example 1. The results are shown in Table 2.

[0127] (1) Thermal expansion coefficient For hard flooring materials, measurements were taken in the flow direction (longitudinal direction) (V direction) and the width direction (perpendicular to the longitudinal direction) (H direction) of the manufacturing line using the following method. The test specimen is placed face up on a stainless steel plate or glass plate, then placed horizontally in an air dryer with a stirrer, with a distance of at least 5 cm in all directions (top, bottom, left, and right) and at least 5 cm from the inner wall of the oven. After maintaining a temperature of 80±2℃ for 6 hours, it is removed and left at room temperature for about 1 hour. Next, the length of the specimen at the measurement point is measured after leaving it in a constant temperature chamber at 20±2℃ for 2 hours. Furthermore, the length is measured again after leaving it in a variable temperature chamber at 40±1℃ for 2 hours. The coefficient of thermal expansion is calculated using the following formula.

number

[0128] (2) Amount of drooping To evaluate the bending stiffness, the amount of sagging of the rigid flooring material was measured according to the following measurement method. First, the rigid flooring material was cut into pieces measuring 5 cm wide x 30 cm long to prepare test samples. These were placed in a constant temperature room at 23°C and 50% RH humidity and cured for 24 hours. Next, the sample was placed in the measuring device. Figure 4A shows the device with the sample in place, and Figure 5B shows Figure 4A viewed from direction A (above). The device includes pedestals 71a and 71b for placing the sample, a rectangular parallelepiped weight 72 for fixing the sample, and a ruler 73 for measuring the amount of sag. Both pedestals are substantially the same shape, 20 cm high, and are rectangular parallelepipeds with a top surface area sufficiently larger than the sample, as shown in Figure 4A. Pedestal 71b is also movable toward and away from pedestal 71a. As shown in Figure 4A, at a temperature of 23°C, with the transparent resin layer side of sample S facing upwards, a 10 cm long region B of the sample was placed on base 71a and the remaining 20 cm long region A was placed on base 71b, so that the sample straddled bases 71a and 71b. Next, as shown in Figures 4B and 5B, a rectangular parallelepiped weight 72 was placed over the entire surface of region B. After that, base 71b was slid away from base 71a and removed. Figure 5A shows the arrangement of the sample before the weight was placed on it. Next, 30 seconds later, the distance h at which region A of sample S sagged downwards was measured with a ruler 73 as the amount of sagging. As shown in Figure 3C, the distance h was defined as the shortest straight-line length (mm) between the surface (top surface) of the base 71a and the lower right corner T of sample S.

[0129] (3) Surface indentations The dent depth (mm) of the sample was measured using a McBurney dent tester in accordance with the Japanese Industrial Standard JIS A1454. Measurements were taken under two temperature conditions: 23°C and 45°C. For the dent test (23°C), a value of 0.2 mm or less is preferred, and a value of 0.15 mm or less is more preferred.

[0130] (4) Residual indentations After curing the sample at a temperature of 23°C and a humidity of 50% for 24 hours, the residual indentation (mm) of the sample was measured in accordance with the Japanese Industrial Standard JIS A1454.

[0131] [Table 2]

[0132] As is clear from the results in Table 2, the hard flooring material of the present invention has a low coefficient of thermal expansion, excellent dimensional stability, and possesses the desired hardness and flexibility as seen in terms of sagging amount, indentation amount, etc.

Claims

1. A flooring material comprising a resin-containing hard layer and a transparent resin layer above it, and a back resin layer below the resin-containing hard layer, (1) The resin-containing hard layer comprises at least a resin component and an inorganic filler, (2) The resin component content in the resin-containing hard layer is 35% by weight or less, (3) The plasticizer content in the resin-containing hard layer is less than 1% by weight, (4) The inorganic filler content in the resin-containing hard layer is 65% by weight or more. A hard flooring material characterized by the following features.

2. The hard flooring material according to claim 1, wherein the resin-containing hard layer contains a vinyl chloride resin.

3. The hard flooring material according to claim 1, wherein the total thickness is 2.5 mm or less.

4. A hard flooring material according to claim 1, which does not include a shape-stabilizing layer containing inorganic fibers.

5. The rigid flooring material according to claim 1, wherein the transparent resin layer contains a vinyl chloride resin containing 13% by weight or more of a plasticizer.

6. A floor structure in which the hard flooring material described in any one of claims 1 to 5 is attached to the subfloor using at least one of a removable adhesive, an adsorbent, and an adhesive tape.

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