STRUCTURE AND METHOD FOR FLOOR-SURFACE COVERING

Abstract: To effectively improve the durability against polishing of a floor sheet by placing a seal part having an improved material and shape on the periphery of edges of the floor sheet bonded to a floor surface. A floor-surface covering structure, comprising: a floor of a building; a floor sheet having an outside size smaller than the size of the floor surface, bonded to the surface of the floor (floor surface); and a seal part that is placed along the edge of the floor sheet and set to the edge and the floor surface, wherein: a material of the seal part is an epoxy resin or a polyester resin, and the seal part has a width that is substantially uniform when viewed in a direction vertical to the floor surface.

Description: STRUCTURE AND METHOD FOR FLOOR- SURFACE COVERING Field of the Invention The present invention relates to a floor-surface covering structure that is formed by bonding a floor sheet to a floor surface in a manner so as to cover it. The floor sheet, used in this floor-surface covering structure, is a so-called decorative sheet that is applied to a floor surface of a building for the purpose of decoration, protection. Background of the Invention In general, a finishing floor member (plastic floor, stone material floor, coated floor, wooden floor, etc.), which is placed on a floor part of a room in a building, is applied to the floor part by using a bonding agent so as to form the floor surface of the room of a building. For such floor surfaces, application of decorative sheets (decorative bonding sheets, also referred to as dressed sheets) has been attempted. This attempt has been made so that decorative sheets, which have been widely used for interior decoration, and for covering and decorating walls and ceilings, are applied to cover floor surfaces. With respect to the decorative sheets of this type, for example, an arrangement has been proposed in which a fluorine polymer film is laminated onto a base layer as a protective layer by using a bonding agent so that the anti-contamination property and anti- scratch property are improved (Japanese Patent Kokoku Publication No. 11752/1989, Japanese Patent Kokai Publication No. 118553/1996). Moreover, Japanese Patent Kokai Publication No. 175270/1998 has disclosed a dressed sheet using a fluorine polymer layer in which an antistatic agent and an antibacterial agent are contained in a protective layer. Since such decorative sheets have a structure in which a thin film having a pattern is laminated onto the surface, the surface part tends to separate at the edge. When the surface of the decorative sheet is damaged by separation, etc., the decorative function of the decorative sheet is impaired; therefore, this problem should be prevented. Consequently, in order to lengthen the service life of the decorative sheet, it is necessary to protect the edges so as to prevent separation on the surface part. A generally used method for protecting the edges of the decorative sheet is to solidify the edges of the decorative sheet with a bonding agent. That is, an attempt is made so as to prevent separation by firmly bonding the film laminated on the surface of the decorative sheet at the edges of the decorative sheet. For example, after a decorative sheet has been affixed, the edges thereof are generally sealed with a material containing a resin. The term "seal material" is referred to as a resin material prior to application, for use in protecting edges of a decorative sheet. The seal material includes materials such as a resin solution, a resin composition that is in a liquid state at room temperature and a hot- melt type resin which melts with heating. In contrast, the term "seal part" is referred to as a member formed by applying the seal material onto the edges of the decorative sheet. The seal part includes materials such as a dried resin, a cured resin composition and a hot- melt type resin that is cooled after once heated. With respect to conventionally known seal materials for protecting the edges, for example, there are (A) those materials containing a solvent and a resin, and (B) those materials containing a non-solvent-type curing resin of a two-liquid curing type. The above-mentioned (A) solvent-type seal materials have a great volume reduction after having been dried, thereby failing to completely cover the edges so as to effectively protect them. Moreover, they have a comparatively low hardness, failing to provide a sufficient protecting effect in some cases. Furthermore, since they need a long drying time, the operability at the working site tends to be lowered. For these reasons, the above-mentioned (B) non-solvent-type curing resins have been preferably used. For example, Japanese Patent Kokai Publication No. 318663/1993 has disclosed an edge protection method using such a non-solvent-type curing seal material. In this method, after a floor sheet has been bonded to a floor surface of a veranda, etc. a seal material, which contains a room-temperature curing urethane resin having a thixotropic property, is applied to the peripheral parts of the edges, and this is cured to form a seal part. Since the urethane resin has rubber elasticity and hardness in a well-balanced state, it is comparatively superior in the abrasion resistant property. Japanese Patent Kokai Publication No. 246643/1996 discloses a line-shaped floor material that prevents separation by machining the edges into a tapered shape. However, since the base layer of the floor sheet is normally very thin, that is, normally, less than 1 mm (normally, not less than 100 μm), it is technically very difficult to machine the edges of the base layer (base film) into a tapered shape according to the same manner as described in the line-shaped floor materials. The inventors, etc. of the present invention have made extensive research efforts to form a desirable floor-surface covering structure by utilizing normal decorative sheets as floor sheets, and have found the following problems with the conventional techniques. With respect to the floor-surface covering structure including floor sheets, there have been ever-increasing cases in which, on floors in hotels and shops, floor sheets are bonded to a floor (to a floor material forming a floor) for the purpose of temporary renovations, advertisements and directing signs. In contrast, in large-scale supermarkets, convenience stores, etc., floor polishing devices, such as high-speed buff machines, have come to be used for cleaning floors. In these devices, a cleaning tool consisting of floor- polishing buffs (buff pads, etc.) and brushes is rotated at comparatively high speeds so as to clean soiled surfaces of floors and floor sheets placed on floor surfaces by utilizing the frictional contact between the cleaning tool and the floor surface. In this case, unless edges of a floor sheet are effectively protected, the durability of a floor-surface covering structure, that is, the durability against polishing, can not be improved to a level which can withstand the cleaning operation made by such floor polishing devices. For example, in some ultra-high-speed polishing devices, the number of revolutions of the cleaning tool is set to 1,000 to 3,000 rpm. In the case when such a polishing device is used for cleaning, unless edges of a floor sheet are effectively protected, separation, rapture, damage, etc. might occur from the edges (end parts). The above-mentioned seal part, formed by using the normal seal material containing a urethane resin, is not advantageous in improving the durability against polishing. This is because the normal urethane resin, which is a comparatively soft rubber elastic member, is not suitable for improving the durability against polishing. Summary of the Invention Therefore, the objective of the present invention is to place a seal part having an improved material and shape on the periphery of the edges of a floor sheet bonded to a floor surface and consequently to improve the durability against polishing of the floor sheet. The present invention provides a floor-surface covering structure, comprising: a floor of a building; a floor sheet having an outside size smaller than the size of the floor surface, bonded to the surface of the floor (floor surface); and a seal part that is placed along the edge of the floor sheet and set to the edge and the floor surface, wherein: a material of the seal part is an epoxy resin or a polyester resin, and the seal part has a width that is substantially uniform when viewed in a direction vertical to the floor surface, thereby the above-mentioned problems are solved. The present invention also provides a floor-surface covering method comprising the steps of: (i) bonding a floor sheet to a floor surface, the floor sheet having an outside size smaller than the size of the floor surface; and (ii) forming a seal part along the edge of the floor sheet, the seal part being set to the edge and the floor surface, wherein: a material of the seal part is an epoxy resin or a polyester resin, and the seal part has a width that is substantially constant when viewed in a direction vertical to the floor surface, thereby the above-mentioned problems are solved. Brief Description of the Drawings FIG. 1 is a cross-sectional view showing one example of a floor-surface covering structure of the present invention. FIG. 2 is a cross-sectional view showing one process in a floor-surface covering method of the present invention. FIG. 3 is a schematic plan view that shows one example of a test for evaluation the durability against polishing of the floor-surface covering structure of the present invention. Description of the Preferred Embodiment(s) Function In the floor-surface covering structure of the present invention, the material of the seal part is a cured epoxy resin or a cured polyester resin. These materials are advantageous in effectively improving the durability against polishing for the floor sheet. Moreover, the seal part has a substantially constant width along the periphery of the edges of the floor sheet. Therefore, it is possible to effectively improve the durability against polishing in cooperation with the fact that the above-mentioned resin is contained. Therefore, in the floor-surface covering structure containing the floor sheet, the edges of the floor sheet are effectively protected, thereby making it possible to prevent separation, rapture and damage of the edges effectively. Not intending to be bound by theory, it appears that the cured epoxy resin and cured polyester resin exert such effects and form a comparatively hard seal part as compared with conventional urethane resin. Moreover, the seal part containing such a hard resin can effectively improve the contamination resistant property. Therefore, the floor-surface covering structure of the present invention is particularly suitable for floor surfaces of hotels, stores, etc. where there are many people coming together. Floor-surface covering structure Referring to FIG. 1, the following description will discuss one preferred embodiment of a floor-surface covering structure in accordance with the present invention. A floor-surface covering structure (100) is provided with a floor (1) of a building having a predetermined area, and a floor sheet (2) that is bonded to the surface of the floor, that is, a floor surface (11), and has an outside size smaller than the floor surface (11), and a seal part (3) that is placed on the periphery of edges (23) of the floor sheet (2). The floor sheet (2) is generally bonded to the floor surface (11) through a bonding layer (not shown) fixed to the rear face (22) of the floor sheet. In the example shown in FIG. 1, the seal part (3) is fixed at least to the edges (23) of the floor sheet (2) and the floor surface (11). Moreover, as indicated by a broken line, the seal material of the seal part (3) may be placed over the floor sheet surface (21) in the vicinity of the edges (23) of the floor sheet, and bonded thereto. In this case, outer boundary of the seal part (3) (the edge apart from edge of the floor sheet) is approximately parallel with edge circumference (outer boundary) of the floor sheet (2), and distance between the outer boundary of the seal part (3) and the edge circumference of the floor sheet (2), (that is, substantial width of the seal part (3)) is approximately constant. The seal part (3) is normally formed by applying a seal member and curing it so as to be molded. As described below, the seal member contains an epoxy resin or an unsaturated polyester resin, and is a curable resin composition containing a curing agent in combination therewith. The seal part (3) is preferably designed to have a substantially constant width (W) along the edges (23) of the floor sheet (2). In order to form the seal part (3) so as to have this constant width (W), the floor-surface covering structure is preferably manufactured by effectively using a masking tape, which will be described later. As illustrated in FIG. 1, the seal part (3), when cut by a face vertical to the floor surface, has a cross-sectional shape that is tapered in such a manner that the height from the floor surface is made smaller from the edge of the floor sheet toward the edge of the seal part. The seal part (3) is not necessarily provided with this tapered shape; however, it is preferable to form it into such a tapered shape shown in the Figure. This tapered shape is very effective so as to improve the durability against polishing of the floor sheet. The inclination of the taper is not particularly limited. However, the relationship between the height (H) of the edge (23) of the floor sheet and the height (h) of the edge (30) of the seal part is normally set as follows: 0 < h < 0.9 H, and more preferably, : 0.01H ≤ h ≤ 0.7 H. The floor-surface covering structure of the present invention is, for example, formed in the following processes. As illustrated in FIG. 2, the processes are: (i) first, bonding the floor sheet (2) to the floor surface (11), (ii) placing a masking tape (4) thinner than the floor sheet on the floor surface (11) with a predetermined space from the edge (23) of the floor sheet (2), (iii) applying a resin composition containing an epoxy resin or a polyester resin onto the floor surface (12) between the edge (23) of the floor sheet (2) and the masking tape (4), (iv) forming a seal part by curing the resin composition; and (v) removing the masking tape (4). With this arrangement, it is possible to easily form the seal part (3) having a substantially constant width (W) along the periphery of the edge (23) of the floor sheet (2). Moreover, the above-mentioned taper shape is easily provided to the seal part (3), thereby making it possible to improve the durability against polishing. The masking tape is formed by using a comparatively thin base material and an adhesive tape having a bonding layer containing an adhesive agent. The base material is normally formed by paper, nonwoven fabric, woven fabric, a polymer film, etc. With respect to the adhesive agent contained in the bonding layer, examples thereof normally include materials containing adhesive polymers such as acrylic-based, rubber-based, polyolefin-based and urethane-based polymers. The thickness of the base material is normally set in the range of 0.01 to 0.5 mm, and preferably, 0.03 to 0.3 mm; and the thickness of the bonding layer is normally set in the range of 0.01 to 0.2 mm, and preferably, 0.02 to 0.1 mm. More preferably, the thickness of the entire masking tape (h) is set so as to be thinner than the thickness (H) of the floor sheet. With respect to specific examples of such a masking tape, for example, a masking tape "item number: 2479H" made by 3M K.K. is listed. The thickness (W) of the seal part (3) is normally set in the range of 1 to 10 mm, preferably, 1.5 to 7 mm, and more preferably, 2 to 5 mm. When the width (W) is too small, the durability against polishing might not be improved, and when it is too large, although the durability against polishing can be improved, the external appearance of the floor-surface covering structure after the seal part has been placed (applied) might be impaired. The application of the seal material is carried out by using a normal applying tool such as a roller and a blade. The following description will discuss the seal material in detail. Seal material The seal material contains an epoxy resin or a unsaturated polyester resin, and this also contains a curing agent in combination therewith. In general, a main resin made from an epoxy resin or a unsaturated polyester resin, and a curing agent are prepared in a separate manner, and at the time of application (coating), these are mixed to form a seal material. Here, in the case when a main resin which is curable upon application of radioactive rays such as ultraviolet rays is used, no curing agent is required. With respect to the seal material, a material which is in a liquid state at normal temperature prior to curing is preferably used, and a material of a hot-melt type, which becomes a liquid upon application of heat, may also be used. The viscosity of the seal material is set to any range as long as it can be applied along the periphery of the edges of the floor sheet, and in general, is set in the range of 1,000 to 600,000 cps, and more preferably 2,000 to 500,000 cps. Moreover, beside the liquefied type, a material of a heat active type or heat-sensitive type, which is softened upon application of heat, may also be used. Here, the seal member is preferably designed so as not to contain substantially any volatile solvent. Moreover, the ratio of blending of the main resin and the curing agent is appropriately determined depending on the respective chemical equivalents so that the seal part made from the cured seal material is provided with predetermined effects (durability against polishing, and preferably, contamination resistance). The seal member preferably contains an epoxy resin. The seal part containing the cured epoxy resin has an effect for improving the durability against polishing of the floor- surface covering structure and is inherently superior in the contamination resistant property. The seal part containing the cured epoxy resin hardly adsorbs and absorbs stain components containing fine dusts and oil. Therefore, the stain components can be easily removed by only cleaning the surface of the seal part through a polishing operation, etc. As compared with the epoxy resin, a seal part containing a polyester resin is inferior in the contamination resistant property. With respect to the epoxy resin, examples thereof include: a bisphenol-A type epoxy resin, a bisphenol-F type epoxy resin, a cresol-novolak type epoxy resin, a phenol- novolak type epoxy resin, etc. The epoxy equivalent of the epoxy resin is normally set in the range of 100 to 600, and more preferably, 120 to 500. Here, with respect to these epoxy resins, two or more kinds of them may be mixed so as to adjust the viscosity, etc. thereof. With respect to the curing agent, normal curing agents used for epoxy resins, such as polyhydric amines, polybasic acids, polybasic anhydrides, polyhydric phenols and polyhydric mercaptans (also referred to as polymercaptans), may be used. More preferably, a polyhydric mercaptan curing agent is used. A seal material containing an epoxy resin and a polyhydric mercaptan curing agent is allowed to have a high contamination resistant property against stain components containing fine dusts and oil. Moreover, this is also quickly cured at room temperature (approximately 25°C)(normally, within 4 hours), and is less susceptible to dimensional contraction, thereby making it possible to provide a superior external appearance after application. With respect to such a polyhydric mercaptan curing agent, examples thereof include: pentaerythritol, tetrathioglycol, polysulfide, trioxyantrimethylenemercaptan, etc. hi addition to the main resin made from an epoxy resin and an unsaturated polyester resin and the curing agent, a curing accelerator may be added thereto. With respect to the curing accelerator for the epoxy resin, benzylmethylamine, 2- (dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl) phenol, etc. may he used. Besides the above-mentioned curing components (main resin, curing agent and accelerator), the seal material may contain various additive agents. Examples of these additive agents include a filler, a coloring pigment, a catalyst, glass bubbles, a thermoplastic resin, an adhesive polymer, an adhesion-applying resin, a plasticizer, an ultraviolet stabilizer, a heat balancing agent, etc. In the case of the addition of these additive agents, the rate of the curing components is normally set in the range of 40 to 95 % by mass with respect to the entire seal material. The above-mentioned seal material is commercially available as putty and adhesive agents. Specific examples of epoxy-based putty include PLASTIC PARTS PUTTY made by 3M K.K. and FLEET Putty made by Kansai Paint K.K. Moreover, specific examples of polyester-based putty include EASY POLISHING Putty made by Isamu Paint K.K. Floor sheet The floor sheet is generally provided with a base layer and a protective layer placed on the base layer. Moreover, a bonding layer is placed on the rear surface of the base layer, and the floor sheet is bonded to a floor surface through this bonding layer. The thickness (H) of the floor sheet is normally set in the range of 0.1 to 0.7 mm, and more preferably, 0.2 to 0.5 mm. If the thickness of the floor sheet is too great, the durability against polishing might deteriorate, and in contrast, the thickness of the floor sheet is too small, the bonding operation of the floor sheet to the surface of the floor might be difficult. The protective layer preferably contains hard beads. Thus, the hard beads serves effectively so as to improve the durability against polishing. The protective layer may have a multi-layered structure; and in this case, the hard beads are preferably contained in the uppermost layer. Moreover, in order to improve the durability against polishing, the protective layer is preferably allowed to contain a cured resin (resin that has been cured) in addition to the beads. The content of the beads is preferably set in the range of 100 to 450 parts by mass, and more preferably, 110 to 400 parts by mass, with respect to 100 parts by mass of the cured resin (non- volatile component). In the case when the base layer has a decorative layer (printed layer, etc.), the protective layer is designed to have sufficient transparency so that the decorative layer can be clearly seen, hi this case, hard beads are preferably provided as transparent beads such as inorganic oxide beads, glass beads, ceramics beads and glass-ceramics beads. Moreover, from this point of view, those beads having high transparency are preferably used, and the diameter of the beads is preferably set as great as possible. The diameter of the beads is normally set in the range of 5 to 100 μm, and more preferably, 10 to 50 μm. The diameter of the beads is normally measured by applying an image-processing device using an optical microscope. The Nickers hardness of the hard beads is preferably set at 500 kg/mm 2 . The hardness less than 500 kg/mm 2 tends to cause degradation in the durability against polishing. Here, "Nickers hardness" is measured as described below: Approximately 10 to 20 hard beads having a particle size of approximately 1 mm are mixed with 10 g of an epoxy resin and this is cured to form a cylindrical sample having a diameter of 3 cm and a height of approximately 1 cm. This is polished so that the beads are exposed to the surface, and a fine hardness meter is applied to the surface of the bead thus exposed so as to obtain measured values. Here, at the time of the measurements, the measuring load is set to 300 g, and the loaded time is 15 seconds. The hard beads are preferably provided as inorganic oxide beads. Organic oxide beads have a high binding function (affinity) to the resin of the protective layer, and makes it possible to achieve a high abrasion resistant property and durability against polishing. With respect to such inorganic fine beads, those containing alumina, silica, titania, zirconia, etc. are preferably used. In particular, beads containing alumina are more preferably used. The refractive index of the hard beads is preferably set to be substantially the same as the refractive index of the curable resin in order to improve the transparency of the surface layer. Therefore, the refractive index of the hard beads is preferably set in the range of 1.3 to 1.9. With respect to the curable resin, those resins that form a cured resin having superior transparency and abrasion resistant property after having been cured are preferably used. The light transmittance of the cured resin (resin that has been cured) is normally set at not less than 70 %, more preferably, not less than 80 %, and most preferably, not less than 90 %. Examples thereof include urethane resins, acrylic resins, polyester resins, silicone resins and epoxy resins. In the case when the base layer has a decorative layer, the light transmittance of the protective layer is normally set at not less than 60 %, and preferably, not less than 80 %. Here, "light transmittance" in the present specification is the rate of light ray transmission measured in accordance with JIS K 7105 "Method for Measuring the Rate of Light Ray Transmission". The above-mentioned floor sheet is, for example, manufactured as follows: A support member, which contains a base layer and a protective layer fixed on the surface of the base layer, is prepared, and a bonding layer is placed on the rear surface (that is, the rear surface of the base layer) of the support member. In the same manner as a normal floor sheet, the bonding layer may be formed by an adhesive agent, a heat-sensitive bonding agent and a hot-melt bonding agent. Moreover, with respect to the adhesive agent, it is preferable to use a re-separable adhesive agent. This allows for easy separation at the time of re-application. Moreover, fine irregularities may be formed on the bonding surface of the adhesive layer through a transferring process of separation paper (liner) having fine irregularities on its surface so as to control the adhesive strength and to improve a bubble-releasing property at the time of application. Here, the thickness of the bonding layer is normally set in the range of 10 to 200 μm, and preferably, 15 to 100 μm. With respect to the protective layer, one that only consists of a surface layer may be used; however, more preferably, it is designed to have (a) a surface layer containing a surface-modifying agent, a curable resin, and hard beads dispersed in the curable resin and (b) a primer layer interpolated between the surface layer and the base layer. The base layer to which the protective layer is fixed is normally formed by a resin layer, and this is because this layer can be fixed to the base layer with a high adhesive strength (bonding strength) so that the durability and abrasion resistance of the floor sheet can be effectively improved. The above-mentioned protective layer is preferably prepared as the following protective film, and this is laminated with the base layer, separately prepared, so as to form a floor sheet. In other words, a floor sheet protective film, used as the protective layer for the floor sheet, is characterized by including (a) a surface layer containing a surface-modifying agent, a curable resin and hard beads dispersed in the cured resin, and (b) a primer layer that is inteφolated between the surface layer and the base layer and used for fixing the protective film to the base layer. With this arrangement, it is fixed on the above-mentioned base layer with a high bonding strength, thereby making it possible to manufacture the floor sheet with the protective layer more easily. The thickness of the protective layer is not particularly limited, as long as it does not impair the effects of the present intention; and it is normally set in the range of 10 to 200 μm, and preferably, 20 to 150 μm. The thickness of the primer layer is normally set in the range of 10 to 150 μm, and preferably, 20 to 100 μm. In addition to the above-mentioned essential components such as the curable resin, the surface layer preferably contains curing-use components, such as a surface-modifying agent, a curing agent, a cross-linking agent, a curing accelerator, a polymerization initiator and. a catalyst. Moreover, other additive agents, such as a surfactant, a filler, a flame retarder, an ultraviolet absorbing agent, an oxidation stabilizer, an adhesion-applying resin, a colorant and an antibacterial agent, may be contained. For example, in some cases, a plurality of fine irregularities, derived from the hard beads, are formed on the surface of the surface layer. In these cases, when dusts, etc. adhere to the surface, the contact area between the dusts, etc. and the surface of the surface layer becomes comparatively large, as compared with a case in which dusts, etc. adhere to a smooth surface. In such a case, in order to allow stains caused by the dusts, etc. to be easily removed without the necessity of polishing strongly, it is preferable to minimize the surface tension by modifying the surface of the surface layer, hi order to minimize the surface tension, a surface-modifying agent is preferably used. The surface-modifying agent is normally a silicone-based or fluorine-based surface-modifying agent. The surface layer of the protective layer may be formed, for example, as follows: A slurry containing the essential components such as hard beads and the curable resin is formed, and this is applied and solidified to form the surface layer. Upon mixing the respective components of the slurry, the concentration of non- volatile components of a solution of a binding material is preliminarily adjusted in the range of 20 to 40 % by mass; thus, it is possible to obtain a slurry having a superior applying property. Since such a slurry contains beads, it is preferably applied by using a notch bar, a round bar, etc. The primer layer is used for improving the adhesive property between the base layer and the protective layer, and is normally prepared as a thermal bonding layer containing a thermoplastic resin having high transparency. The thermoplastic resin is set to have a light transmittance of normally not less than 70 %, preferably, not less than 80 %, and more preferably, not less than 90 %. With respect to the thermoplastic resin, examples thereof include: vinylchloride resins (including copolymers between vinylchloride and another vinyl monomer), urethane resins, acrylic resins, polyester resins, silicone resins, etc. The primer layer may be formed by applying an application solution containing a primer layer resin and forming it as a film through a normal coating means. With respect to the protective layer (protective film) of such a laminated layer structure, for example, a primer layer is placed on a temporary base member (such as a liner) and a surface layer is placed on the primer layer; thus, this layer is easily manufactured. The base layer is required for maintaining the mechanical strength of the entire floor sheet properly. Besides this, the base layer also serves as a layer for supporting a print layer which is placed on the sheet surface so as to add a decorative appearance thereto. The print layer is a layer used for coloring the base layer, for placing images such as characters and patterns on the surface, and for subsequently adding decorative effects thereto. The print layer is placed (1) on the uppermost surface of the base layer, (2) inside the base layer, or on the uppermost rear surface of the base layer (on the side contacting the bonding layer). The base layer is formed by using materials normally used for floor sheets; and for example, paper, a metal film, a resin film, etc. may be used. With respect to the resin, vinyl chloride resins (including copolymers between vinyl chloride and another vinyl monomer), polyolefm resins, urethane resins, acrylic resins, polyester resins, silicone resins, etc. may be used. With respect to the metal film, metal foil, such as aluminum foil and copper foil, may be used. In the case when metal foil is used as the base material, this can be bonded desirably along the seam of tiles. Here, the thickness of the base layer is normally set in the range of 10 to 200 μm, and preferably, 15 to 150 μm. In this case, the thickness of the base layer represents the total thickness of the print layer and the base layer in the case when the base layer includes the print layer. The print layer can be formed in the same manner as a conventional print layer for a decorative sheet. For example, this can be formed by means of screen printing, gravure printing, thermotransfer printing, etc. by using printing ink. The thickness of the print layer is determined in the same manner as a conventional print layer for a decorative sheet. Moreover, in place of the print layer, a metallic layer containing a metal vapor deposition layer may be used so as to apply a metallic appearance thereto. Furthermore, such a metallic layer may be used as a decorative layer in combination with a print layer formed thereon. The above-mentioned floor sheet can be obtained as a commercial product. Specific examples include floor markings, etc. formed by using a floor sheet "Floor-use Dynoc Film (trade name)" made by 3M K.K., "Floor Minder (trade name)" made by the same company, and a printing medium "Visual Marking (trade mark) Lag System" made by Linteck K. Example 1 First, as illustrated in FIG. 3, onto a floor surface (11) made of the surface of plastic floor tiles "P-tile" made by Tajima K.K. was bonded a floor sheet (2) "Floor-use (trade mark) Dynoc Film (item number) D/N21 ; thickness: 0.4 mm". The plane shape of the floor sheet is set to be a square 150 mm long in each side. Moreover, this floor sheet includes a protective layer containing glass beads and a curable resin. On the periphery of the edges of the floor sheet was formed a seal part (3) having an application width of 5 mm by using epoxy putty containing an epoxy resin, a polyhydric mercaptan curing agent and a curing accelerator as a seal material; thus, a floor-surface covering structure of the present example having a structure shown in FIG. 1 was formed. The epoxy putty used here was "PLASTIC PARTS Putty 8108" made by 3M K.K. This putty was a two-liquid type curable putty consisting of A-liquid and B-liquid. Here, the application operation of the seal material was carried out by using a masking tape as described earlier so as to provide a constant width and a tapered shape to the seal part. The masking tape was a Masking Tape No. 2479H" having a tape thickness of 0.09 mm made by 3M K.K. After four hours had elapsed since the application of the putty, it was confirmed that the putty had been sufficiently cured. Thereafter, in a manner as shown in FIG. 3, on the part at which the floor sheet of the floor-surface covering structure of the present invention had been bonded, a floor-use pad (5) (Speed Burnish Pad made by 3M K.K.) was allowed to move with a load of 3 kg, at a speed of 150 mm/sec, while being rotated at 2,000 rpm; thus, the durability against polishing was evaluated. As a result of the evaluation, it was confirmed that, even after 100 passages of the high-speed polisher, no damage was observed at the edges so that the floor-surface covering structure of the present example had achieved superior durability against polishing. Moreover, the contamination resistant property of the seal part was evaluated by using a contamination recovery rate test in accordance with JIS A 5709-1979. The following description will briefly discuss this testing method. First, the seal material used in the present example was applied to the surface of the same floor tiles to form a coat film having a thickness of 5 mm and a substantially square shape having a plane dimension of 3 cm x 3 cm; thus, a specimen was formed. After the coat film surface of this specimen had been cleaned with a cloth immersed in a soap solution having a concentration of 5 %, the initial diffusion reflectivity YO was measured. Next, the specimen was smeared with lg of a stain component, which will be described later, and this was left for 30 minutes. After the stain component had been wiped out sufficiently with a dry cloth, the diffusion reflectivity Yl after having been recovered from the contamination was measured. The above-mentioned stain component was formed by mixing white Vaseline (derived from the Japan pharmaceutical codex) with carbon black at a mass ratio of 10: 1. The percentage (Y = YI/YO x 100) of the two diffusion reflectivities thus measured was calculated, and this calculated value was defined as the contamination recovery rate. The contamination recovery rate thus evaluated was 98 % so that it was confirmed that the floor-surface covering structure of the present example was superior in the contamination resistant property of the seal part. Examples 2 to 5 The same processes as Example 1 were carried out except that the application width of the seal member was changed from 5 mm to 1 mm (Example 2), 2 mm (Example 3), 3 mm (Example 4) and 7 mm (Example 5) respectively; thus, the corresponding floor-surface covering structures were formed respectively. With respect to these floor-surface covering structures, the durability against polishing was evaluated respectively in the same manner as Example 1, and the results showed that in all the Examples, no damage to the edges was observed even after 100 passages of the high-speed polisher. Thus, it was confirmed that the structures were superior in the durability against polishing. Moreover, since the same seal material as Example 1 was used, the contamination resistance of the seal part was superior in all the Examples. Example 6 The same processes as Example 1 were carried out except that the putty was changed to EASY POLISH polyester made by Isamu Paint K.K. to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that no damage to the edges was observed even after 100 passages of the high- speed polisher. Thus, it was confirmed that the structure was superior in the durability against polishing. Moreover, the contamination resistant property was evaluated in the same manner as Example 1, and the contamination recovery rate was 41 %. Example 7 The same processes as Example 1 were carried out except that the putty was changed to HIGH SOFT polyester putty made by 3M K.K. to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that no damage to the edges was observed even after 100 passages of the high- speed polisher. Thus, it was confirmed that the structure was superior in the durability against polishing. Moreover, the contamination resistant property was evaluated in the same manner as Example 1, and the contamination recovery rate was 50 %. Example 8 The same processes as Example 1 were carried out except that the putty was changed to FLEET PUTTY epoxy made by Kansai Paint K.K. to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that no damage to the edges was observed even after 100 passages of the high- speed polisher. Thus, it was confirmed that the structure was superior in the durability against polishing. Comparative Example 1 The same processes as Example 1 were carried out except that the seal material was changed to a solvent-containing acrylic seal material (No. EC-1103 made by 3M K.K.) to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that a damage to the edges was observed after 10 passages of the high-speed polisher. Comparative Example 2 The same processes as Example 1 were carried out except that the seal material was changed to a solvent-containing urethane-based seal material (New Urethane Sealer No. 8540 made by 3M K.K.) to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that a damage to the edges was observed after 10 passages of the high-speed polisher. Comparative Example 3 The same processes as Example 1 were carried out except that no seal material was used to provide a floor-surface covering structure of the present Example. With respect to the floor-surface covering structure of the present Example, the durability against polishing was evaluated in the same manner as Example 1. The results showed that a damage to the edges was observed only after 1 passage of the high-speed polisher. The present invention makes it possible to improve the durability (durability against polishing) of a part (floor sheet part) on which a floor sheet has been bonded at the time when a floor-surface covering structure is polished by a floor polishing device, and consequently to effectively prevent separation and damages to the edges (end parts) of the floor sheet.

Claims: What is Claimed is: 1. A floor-surface covering structure, comprising: a floor of a building; a floor sheet having an outside size smaller than the size of the floor surface, bonded to the surface of the floor (floor surface); and a seal part that is placed along the edge of the floor sheet and set to the edge and the floor surface, wherein: a material of the seal part is an epoxy resin or a polyester resin, and the seal part has a width that is substantially constant when viewed in a direction vertical to the floor surface. 2. The floor-surface covering structure according to claim 1, wherein the seal part has a cross-section, cut by a face vertical to the floor surface, having a tapered shape in which the height from the floor face is made smaller from the edge of the floor sheet toward the edge of the seal part. 3. The floor-surface covering structure according to claim 1, wherein the seal part is made from a resin composition containing an epoxy resin and a polyhydric mercaptan curing agent. 4. A floor-surface covering method comprising the steps of: (i) bonding a floor sheet to a floor surface, the floor sheet having an outside size smaller than the size of the floor surface; and (ii) forming a seal part along the edge of the floor sheet, the seal part being set to the edge and the floor surface, wherein: a material of the seal part is an epoxy resin or a polyester resin, and the seal part has a width that is substantially constant when viewed in a direction vertical to the floor surface. 5. A floor-surface covering method comprising the steps of: (i) bonding a floor sheet to a floor surface, the floor sheet having an outside size smaller than the size of the floor surface; (ii) placing a masking tape thinner than the floor sheet on the floor surface with a predetermined space from the edge of the floor sheet; (iii) coating the floor surface between the edge of the floor sheet and the masking tape with a resin composition containing an epoxy resin or a polyester resin; (iv) curing the resin composition so as to form the seal part; and (v) removing the masking tape.

Inventors: MIYAMOTO SHUJI, MIYAMOTO, SHUJI
Applicants: 3M INNOVATIVE PROPERTIES CO, MIYAMOTO SHUJI, 3M INNOVATIVE PROPERTIES COMPANY, MIYAMOTO, SHUJI
Application year: 2001
Main classification: E04F15
IPC codes: E04F15, E04F19